Science.gov

Sample records for fundamental binding forces

  1. Correlation between fundamental binding forces and clinical prognosis of Staphylococcus aureus infections of medical implants

    SciTech Connect

    Yongsunthon, Ruchirej; Fowler, Vance; Lower, Brian H.; Vellano, Francis P.; Alexander, Emily; Reller, L. Barth; Corey, G. Ralph; Lower, Steven

    2007-03-01

    Atomic force microscopy was used to “fish” for binding reactions between a fibronectin-coated probe (i.e., substrate simulating an implant device) and each of 15 different strains of S. aureus isolated from either patients with infected cardiac prosthesis (invasive group) or healthy human subjects (control group). There is a strong distinction (p=0.01) in the binding force-signature observed for the invasive vs. control populations. This observation suggests that a microorganism’s “force taxonomy” may provide a fundamental and practical indicator of the risk that bacterial infections pose to patients with implanted medical devices.

  2. Correlation between fundamental binding forces and clinical prognosis of Staphylococcus aureus infections of medical implants

    SciTech Connect

    Yongsunthon, Ruchirej; Fowler, Vance; Lower, Brian H.; Vellano, Francis P.; Alexander, Emily; Reller, L. Barth; Corey, G. Ralph; Lower, Steven

    2007-02-01

    Implanted medical devices (e.g., prosthetic heart valves, permanent pacemakers) significantly improve the quality of life for many humans. However, a common clinical observation is that such devices become colonized with potentially life-threatening Staphylococcus aureus biofilms, which are difficult to combat with host defenses or antibiotics. This study attempts to draw a correlation between the clinical outcome of patients with implanted cardiac devices and the fundamental binding forces ultimately responsible for the initiation of an S. aureus biofilm in-situ. Atomic force microscopy was used to measure forces between a fibronectin-coated probe (simulating a prosthetic implant) and 15 different strains of S. aureus isolated from either patients with infected cardiac devices (invasive population) or healthy human subjects (control population). The fibronectin-coated probe was repeatedly brought into and out of contact with a bacterium’s surface, “fishing” for a reaction with the cell’s fibronectin-binding proteins. More than 40,000 force profiles were measured on 5-10 different cells for each of the 15 clinical strains. A unique force-signature was observed for a binding event between the fibronectin-coated probe and the bacteria. When grouped by the frequency of this force-signature, there was a strong distinction (p=0.01) between the invasive and control populations of S. aureus. This discovery suggests that biofilm forming bacteria may be classified according to their “force taxonomy”, which could have a positive effect on health care as it bridges the long-standing disconnect between macroscopic, clinical investigations and nanometer-scale forces ultimately responsible for a bond between S. aureus and the surface of a prosthetic device.

  3. Unification of Fundamental Forces

    NASA Astrophysics Data System (ADS)

    Salam, Abdus; Taylor, Foreword by John C.

    2005-10-01

    Foreword John C. Taylor; 1. Unification of fundamental forces Abdus Salam; 2. History unfolding: an introduction to the two 1968 lectures by W. Heisenberg and P. A. M. Dirac Abdus Salam; 3. Theory, criticism, and a philosophy Werner Heisenberg; 4. Methods in theoretical physics Paul Adrian Maurice Dirac.

  4. Short-range Fundamental forces

    SciTech Connect

    Antoniadis, I; Baessler, Stefan; Buechner, M; Fedorov, General Victor; Hoedl, S.; Lambrecht, A; Nesvizhevsky, V.; Pignol, G; Reynaud, S.; Sobolev, Yu.

    2011-01-01

    We consider theoretical motivations to search for extra short-range fundamental forces as well as experiments constraining their parameters. The forces could be of two types: (1) spin-independent forces; and (2) spin-dependent axion-like forces. Different experimental techniques are sensitive in respective ranges of characteristic distances. The techniques include measurements of gravity at short distances, searches for extra interactions on top of the Casimir force, precision atomic and neutron experiments. We focus on neutron constraints, thus the range of characteristic distances considered here corresponds to the range accessible for neutron experiments.

  5. An Accurate Quartic Force Field, Fundamental Frequencies, and Binding Energy for the High Energy Density Material T(d)N4

    NASA Technical Reports Server (NTRS)

    Lee, Timothy J.; Martin, Jan M. L.; Kwak, Dochan (Technical Monitor)

    2002-01-01

    The CCSD(T) method has been used to compute a highly accurate quartic force field and fundamental frequencies for all N-14 and N-15 isotopomers of the high energy density material T(sub d)N(sub 4). The computed fundamental frequencies show beyond doubt that the bands observed in a matrix isolation experiment by Radziszewski and coworkers are not due to different isotopomers of T(sub d)N(sub 4). The most sophisticated thermochemical calculations to date yield a N(sub 4) -> 2N(sub 2) heat of reaction of 182.22 +/- 0.5 kcal/mol at 0 K (180.64 +/- 0.5 at 298 K). It is hoped that the data reported herein will aid in the ultimate detection of T(sub d)N(sub 4).

  6. Fundamental limits of optical force and torque

    NASA Astrophysics Data System (ADS)

    Rahimzadegan, A.; Alaee, R.; Fernandez-Corbaton, I.; Rockstuhl, C.

    2017-01-01

    Optical force and torque provide unprecedented control on the spatial motion of small particles. A valid scientific question, that has many practical implications, concerns the existence of fundamental upper bounds for the achievable force and torque exerted by a plane wave illumination with a given intensity. Here, while studying isotropic particles, we show that different light-matter interaction channels contribute to the exerted force and torque, and analytically derive upper bounds for each of the contributions. Specific examples for particles that achieve those upper bounds are provided. We study how and to which extent different contributions can add up to result in the maximum optical force and torque. Our insights are important for applications ranging from molecular sorting, particle manipulation, and nanorobotics up to ambitious projects such as laser-propelled spaceships.

  7. Redefinition of the Four Fundamental Forces,

    DTIC Science & Technology

    1980-06-01

    super-strong force. Such a force has been qualitatively predicted and attributed to Kaufman by Feynman (10, p. 609) and to Kogut, Wilson and Susskind by...Theory of Gravitation. Physical Review D, 13, 6, 1538-1560 (March 1976) 6. CHARLES W. MISNER, KIP S. THORNE, AND JOHN ARCHIBALD WHEELER . Gravitation. San...E. MEYERHOF. Elements of Nuclear Physics. New York: McGraw-Hill (1957) 216 Ala.--------- HEASTON 10. RICHARD P. FEYNMAN . Structure of the Proton

  8. Conformal invariance and the metrication of the fundamental forces

    NASA Astrophysics Data System (ADS)

    Mannheim, Philip D.

    2016-07-01

    We revisit Weyl’s metrication (geometrization) of electromagnetism. We show that by making Weyl’s proposed geometric connection be pure imaginary, not only are we able to metricate electromagnetism, an underlying local conformal invariance makes the geometry be strictly Riemannian and prevents observational gravity from being complex. Via torsion, we achieve an analogous metrication for axial-vector fields. We generalize our procedure to Yang-Mills theories, and achieve a metrication of all the fundamental forces. Only in the gravity sector does our approach differ from the standard picture of fundamental forces, with our approach requiring that standard Einstein gravity be replaced by conformal gravity. We show that quantum conformal gravity is a consistent and unitary quantum gravitational theory, one that, unlike string theory, only requires four spacetime dimensions.

  9. Saturation of color forces and nuclear binding

    NASA Astrophysics Data System (ADS)

    Matsuoka, Hiroshi; Sivers, Dennis

    1986-03-01

    We discuss an approach to understanding the saturation of forces in chromodynamics. Our formulation is suggested by the observation that many lattice-gauge-theory calculations give results well approximated by considering the dynamics of stringlike flux tubes. By looking at multiquark Green's functions in the strong-coupling, quenched, approximations of lattice chromodynamics we find examples of configuration mixing which can allow the binding of color-singlet hadrons into larger composite systems. We surmise that this configuration mixing is crucial to the understanding of nuclear binding. As a simple example we discuss the binding of two mesons composed of heavy, static, quarks into a deuteronlike object. Our results suggest that the magnitude of nuclear binding can be deduced by measuring a finite number of Wilson-loop configurations in lattice QCD.

  10. The Gap and the origin of the fundamental forces

    NASA Astrophysics Data System (ADS)

    Zichichi, Antonino

    2016-12-01

    The energy level where the best values of the three fundamental gauge couplings (α1,α2,α3) converge is at least two orders of magnitude below the Planck energy level. The existence of this Gap could imply that the gravitational force ‘comes into being’ before QED, QFD and QCD. The most interesting consequence of the Gap would then be the existence of matter whose charge is only the gravitational charge. If this is so, events should be detected where only gravitational waves are produced. Primordial black holes (PBHs) would be produced much more frequently than the standard black holes (SBHs) since SBHs would be ‘derivative’ effects produced later, after matter made with protons, electrons, neutrons, and stars can exist. Collisions between PBHs generating only gravitational waves should be more frequent than SBHs collisions.

  11. Fundamental study of phosphor separation by controlling magnetic force

    NASA Astrophysics Data System (ADS)

    Wada, Kohei; Mishima, Fumihito; Akiyama, Yoko; Nishijima, Shigehiro

    2013-11-01

    The phosphor wastes consist of phosphors with different emission colors, green (LAP), red (YOX), blue (BAM) and white (HP). It is required to recover and reuse the rare earth phosphors with high market value. In this study, we tried to separate the phosphor using the magnetic separation by HTS bulk magnet utilizing the differences of magnetic susceptibility by the type of phosphors. We succeeded in the successive separation of HP with low market value from YOX and BAM including the rare earth using the magnetic Archimedes method. In this method, vertical and radial components of the magnetic force were used.

  12. The Sequential Evolution of Universes Based on Fundamental Forces

    NASA Astrophysics Data System (ADS)

    Derow, Catherine Kari

    2015-08-01

    Universes may arise as nature abhors a void. Upon ending of a universe, a new universe forms to fill a new void, forming after perhaps a period of nothingness.The nature of a new universe and the nature of formation, may be related to the nature of the previous universe and the nature of its ending, respectively, e.g., if the end of a universe was prolonged, this might be followed by a short period of nothingness and then an explosive creation of a new universe. Long approach to nothingness and a brief period of nothingness may mean a universe arises quickly and energetically in response to this long latent period of expectancy of void-filling. In terms of order in a universe, order may engender new more ordered universes, until need for chaos means a more chaotic universe arises. Ordered universes may cause new even more ordered universes to atise. The order principle dictates the type of matter organization that arises in universes in series. An ordered universe may have a latent energy of order which leads to a smaller more ordered universe. This minimizes the expectancy of a void, as a smaller more regularly filled void will then ensue in the new universe, until the energy held in by this order is released in the formation of a large much less ordered and slower forming and expanding universe, with more regions of near void. Nature may strive for a build up of intensity of focused order filling an ever- smaller void, averting the void, until the principle of chaos predominates and the energy that this requirement builds causes explosive formation of a large and disordered universe. The need to fill any void that arises and a force that favors a small void arising as void is abhorred and this void being regularly and densely filled competes with the force that favors matter tending towards chaos. These principles governs universes arising in series, until a period of nothingness can prevail until the need to create a void predominates. Nothingness is able to

  13. Biophysical characterization of DNA binding from single molecule force measurements

    NASA Astrophysics Data System (ADS)

    Chaurasiya, Kathy R.; Paramanathan, Thayaparan; McCauley, Micah J.; Williams, Mark C.

    2010-09-01

    Single molecule force spectroscopy is a powerful method that uses the mechanical properties of DNA to explore DNA interactions. Here we describe how DNA stretching experiments quantitatively characterize the DNA binding of small molecules and proteins. Small molecules exhibit diverse DNA binding modes, including binding into the major and minor grooves and intercalation between base pairs of double-stranded DNA (dsDNA). Histones bind and package dsDNA, while other nuclear proteins such as high mobility group proteins bind to the backbone and bend dsDNA. Single-stranded DNA (ssDNA) binding proteins slide along dsDNA to locate and stabilize ssDNA during replication. Other proteins exhibit binding to both dsDNA and ssDNA. Nucleic acid chaperone proteins can switch rapidly between dsDNA and ssDNA binding modes, while DNA polymerases bind both forms of DNA with high affinity at distinct binding sites at the replication fork. Single molecule force measurements quantitatively characterize these DNA binding mechanisms, elucidating small molecule interactions and protein function.

  14. Biophysical characterization of DNA binding from single molecule force measurements

    PubMed Central

    Chaurasiya, Kathy R.; Paramanathan, Thayaparan; McCauley, Micah J.; Williams, Mark C.

    2010-01-01

    Single molecule force spectroscopy is a powerful method that uses the mechanical properties of DNA to explore DNA interactions. Here we describe how DNA stretching experiments quantitatively characterize the DNA binding of small molecules and proteins. Small molecules exhibit diverse DNA binding modes, including binding into the major and minor grooves and intercalation between base pairs of double-stranded DNA (dsDNA). Histones bind and package dsDNA, while other nuclear proteins such as high mobility group proteins bind to the backbone and bend dsDNA. Single-stranded DNA (ssDNA) binding proteins slide along dsDNA to locate and stabilize ssDNA during replication. Other proteins exhibit binding to both dsDNA and ssDNA. Nucleic acid chaperone proteins can switch rapidly between dsDNA and ssDNA binding modes, while DNA polymerases bind both forms of DNA with high affinity at distinct binding sites at the replication fork. Single molecule force measurements quantitatively characterize these DNA binding mechanisms, elucidating small molecule interactions and protein function. PMID:20576476

  15. Binding Forces and Teachers' School Life: A Recursive Model.

    ERIC Educational Resources Information Center

    Pang, Nicolas Sun-Keung

    2003-01-01

    Formulates theoretical model of four binding forces in school organizations--bureaucratic linkage, cultural linkage, tight coupling, and loose coupling--and examines their effects on teachers' feelings about school life. Finds, for example, that loose coupling had a positive effect on teachers' sense of community, job satisfaction, and commitment.…

  16. Ultra-fast force-clamp laser trapping of single molecular motors and DNA binding proteins

    NASA Astrophysics Data System (ADS)

    Capitanio, Marco; Monico, Carina; Vanzi, Francesco; Pavone, Francesco S.

    2013-09-01

    Forces play a fundamental role in a wide array of biological processes, regulating enzymatic activity, kinetics of molecular bonds, and molecular motors mechanics. Single molecule force spectroscopy techniques have enabled the investigation of such processes, but they are inadequate to probe short-lived (millisecond and sub-millisecond) molecular complexes. We developed an ultrafast force-clamp spectroscopy technique that uses a dual trap configuration to apply constant loads to a single intermittently interacting biological polymer and a binding protein. Our system displays a delay of only ˜10 μs between formation of the molecular bond and application of the force and is capable of detecting interactions as short as 100 μs. The force-clamp configuration in which our assay operates allows direct measurements of load-dependence of lifetimes of single molecular bonds. Moreover, conformational changes of single proteins and molecular motors can be recorded with sub-nanometer accuracy and few tens of microseconds of temporal resolution. We demonstrate our technique on molecular motors, using myosin II from fast skeletal muscle and on protein-DNA interaction, specifically on Lactose repressor (LacI). The apparatus is stabilized to less than 1 nm with both passive and active stabilization, allowing resolving specific binding regions along the actin filament and DNA molecule. Our technique extends single-molecule force-clamp spectroscopy to molecular complexes that have been inaccessible up to now, opening new perspectives for the investigation of the effects of forces on biological processes.

  17. Mechanical forces regulate elastase activity and binding site availability in lung elastin.

    PubMed

    Jesudason, Rajiv; Sato, Susumu; Parameswaran, Harikrishnan; Araujo, Ascanio D; Majumdar, Arnab; Allen, Philip G; Bartolák-Suki, Erzsébet; Suki, Béla

    2010-11-03

    Many fundamental cellular and extracellular processes in the body are mediated by enzymes. At the single molecule level, enzyme activity is influenced by mechanical forces. However, the effects of mechanical forces on the kinetics of enzymatic reactions in complex tissues with intact extracellular matrix (ECM) have not been identified. Here we report that physiologically relevant macroscopic mechanical forces modify enzyme activity at the molecular level in the ECM of the lung parenchyma. Porcine pancreatic elastase (PPE), which binds to and digests elastin, was fluorescently conjugated (f-PPE) and fluorescent recovery after photobleach was used to evaluate the binding kinetics of f-PPE in the alveolar walls of normal mouse lungs. Fluorescent recovery after photobleach indicated that the dissociation rate constant (k(off)) for f-PPE was significantly larger in stretched than in relaxed alveolar walls with a linear relation between k(off) and macroscopic strain. Using a network model of the parenchyma, a linear relation was also found between k(off) and microscopic strain on elastin fibers. Further, the binding pattern of f-PPE suggested that binding sites on elastin unfold with strain. The increased overall reaction rate also resulted in stronger structural breakdown at the level of alveolar walls, as well as accelerated decay of stiffness and decreased failure stress of the ECM at the macroscopic scale. These results suggest an important role for the coupling between mechanical forces and enzyme activity in ECM breakdown and remodeling in development, and during diseases such as pulmonary emphysema or vascular aneurysm. Our findings may also have broader implications because in vivo, enzyme activity in nearly all cellular and extracellular processes takes place in the presence of mechanical forces.

  18. Unphosphorylated calponin enhances the binding force of unphosphorylated myosin to actin

    PubMed Central

    Roman, Horia Nicolae; Zitouni, Nedjma B.; Kachmar, Linda; Ijpma, Gijs; Hilbert, Lennart; Matusovskiy, Oleg; Benedetti, Andrea; Sobieszek, Apolinary; Lauzon, Anne-Marie

    2013-01-01

    Background Smooth muscle has the distinctive ability to maintain force for long periods of time and at low energy costs. While it is generally agreed that this property, called the latch-state, is due to the dephosphorylation of myosin while attached to actin, dephosphorylated-detached myosin can also attach to actin and may contribute to force maintenance. Thus, we investigated the role of calponin in regulating and enhancing the binding force of unphosphorylated tonic muscle myosin to actin. Methods To measure the effect of calponin on the binding of unphosphorylated myosin to actin, we used the laser trap assay to quantify the average force of unbinding (Funb) in the absence and presence of calponin or phosphorylated calponin. Results Funb from F-actin alone (0.12±0.01pN; mean±SE) was significantly increased in the presence of calponin (0.20±0.02pN). This enhancement was lost when calponin was phosphorylated (0.12±0.01pN). To further verify that this enhancement of Funb was due to cross-linking of actin to myosin by calponin, we repeated the measurements at high ionic strength. Indeed, the Funb obtained at a [KCl] of 25mM (0.21±0.02pN; mean±SE) was significantly decreased at a [KCl] of 150mM, (0.13±0.01pN). Conclusions This study provides direct molecular level-evidence that calponin enhances the binding force of unphosphorylated myosin to actin by cross-linking them and that this is reversed upon calponin phosphorylation. Thus, calponin might play an important role in the latch-state. General Significance This study suggests a new mechanism that likely contributes to the latch-state, a fundamental and important property of smooth muscle that remains unresolved. PMID:23747303

  19. Atomic force microscopy: Unraveling the fundamental principles governing secretion and membrane fusion in cells.

    PubMed

    Jena, Bhanu P

    2009-07-01

    The story of cell secretion and membrane fusion is as old as life itself. Without these fundamental cellular processes known to occur in yeast to humans, life would cease to exist. In the last 15 years, primarily using the atomic force microscope, a detailed understanding of the molecular process and of the molecular machinery and mechanism of secretion and membrane fusion in cells has come to light. This has led to a paradigm shift in our understanding of the underlying mechanism of cell secretion. The journey leading to the discovery of a new cellular structure the 'porosome',-the universal secretory machinery in cells, and the contributions of the AFM in our understanding of the general molecular machinery and mechanism of cell secretion and membrane fusion, is briefly discussed in this article.

  20. Fundamental Study of Local Heat Transfer in Forced Convective Boiling of Ammonia on Vertical Flat Plate

    NASA Astrophysics Data System (ADS)

    Kim, Jeong-Hun; Arima, Hirofumi; Ikegami, Yasuyuki

    In the present study, the fundamental experiments that investigate characteristics of local heat transfer in forced convective boiling on vertical flat plate with 2-mm channel height are taken to realize plate type compact evaporator for OTEC or STEC. The experiments are performed with ammonia as the working fluid. The experiments are also carried out with the following test conditions; saturated pressure = 0.7, 0.8, 0.9 MPa, mass flux = 7.5, 10, 15 kg/(m2•s), heat flux = 15, 20, 25 kW/m2 and inlet quality = 0.1 ~ 0.4 [-]. The result shows that the wall superheated temperature of forced convective boiling is lower than that of pool boiling. And the heat transfer coefficient increases with an increase in quality and the decrease in the local heat flux and saturated pressure for prescribed experimental conditions. However, local heat transfer coefficients are not affected by mass fluxes in the prescribed experimental conditions. An empirical correlation that can predict the local heat transfer coefficient on vertical flat plate within experimental conditions is also proposed.

  1. Fundamental Distinctions in Physics underlying Nonsteady Forcings of Wind Turbine Power vs. Drivetrain by Atmospheric Turbulence

    NASA Astrophysics Data System (ADS)

    Brasseur, James; Lavely, Adam; Nandi, Tarak

    2016-11-01

    Whereas the primary function of a wind turbine (WT) is the generation of electricity, wind farm profitability is decreased both by integrated losses in power and increases in premature failures of drivetrain components resulting from energetic nonsteady aerodynamic forcings of WT rotors by atmospheric and wake turbulence. Here we contrast the physics underlying dominant nonsteady atmospheric turbulence forcings of the bending moments in the WT rotor plane (torque/power) vs. the out-of-plane bending moments (OPBM) that underlie premature drivetrain component failure. Using an advanced actuator line model of the 5 MW NREL and the 1.5 MW GE wind turbine rotors embedded within a high-fidelity spectral LES of a typical daytime convective atmospheric boundary layer, we show that (1) the physics underlying large torque vs. OBPM fluctuations are associated with fundamentally different turbulence eddy characteristics and (2) nonsteady response centers on 4 characteristic time scales associated advection of eddies and load response of blades cutting through internal turbulence eddy structure. Supported by DOE. Computer resources by NSF/XSEDE.

  2. Spatial Analysis and Quantification of the Thermodynamic Driving Forces in Protein-Ligand Binding: Binding Site Variability

    PubMed Central

    Raman, E. Prabhu; MacKerell, Alexander D.

    2015-01-01

    The thermodynamic driving forces behind small molecule-protein binding are still not well understood, including the variability of those forces associated with different types of ligands in different binding pockets. To better understand these phenomena we calculate spatially resolved thermodynamic contributions of the different molecular degrees of freedom for the binding of propane and methanol to multiple pockets on the proteins Factor Xa and p38 MAP kinase. Binding thermodynamics are computed using a statistical thermodynamics based end-point method applied on a canonical ensemble comprising the protein-ligand complexes and the corresponding free states in an explicit solvent environment. Energetic and entropic contributions of water and ligand degrees of freedom computed from the configurational ensemble provides an unprecedented level of detail into the mechanisms of binding. Direct protein-ligand interaction energies play a significant role in both non-polar and polar binding, which is comparable to water reorganization energy. Loss of interactions with water upon binding strongly compensates these contributions leading to relatively small binding enthalpies. For both solutes, the entropy of water reorganization is found to favor binding in agreement with the classical view of the “hydrophobic effect”. Depending on the specifics of the binding pocket, both energy-entropy compensation and reinforcement mechanisms are observed. Notable is the ability to visualize the spatial distribution of the thermodynamic contributions to binding at atomic resolution showing significant differences in the thermodynamic contributions of water to the binding of propane versus methanol. PMID:25625202

  3. A fundamental model of mistuning for system identification and forced response prediction

    NASA Astrophysics Data System (ADS)

    Feiner, Drew M.

    The vibratory response of a turbine blade is very sensitive to small changes in the blade properties. Therefore, the variations that come from the manufacturing process and wear can significantly increase a blade's vibratory stress at resonance. This phenomenon, referred to as mistuning, can cause blades in a gas turbine engine to fail from high cycle fatigue. A new reduced order model of mistuned bladed disk vibration is presented. This new approach is shown to accurately represent the response of real turbine geometries when only a single family of modes is excited. Yet its mathematical form is even simpler than that of a mass-spring model. Because it requires only minimal input data, this model is much easier to use than previous reduced order methods. Furthermore, its simplicity allows the fundamental parameters that control mistuning to be readily identified. This model is then used to develop a set of analysis tools to assess the mistuning in an engine component and predict its vibratory response under rotating conditions. These tools include a completely experimental method of system identification which uses vibratory response measurements of the bladed disk system as a whole to infer its mistuning. As a system-based method, this approach is particularly well suited to integrally bladed rotors, whose blades cannot be removed for individual testing. Next, an analytical method is developed to adjust mistuning for the effects of centrifugal stiffening. The approach allows mistuning measured from a stationary rotor to be used to predict the part's forced response under rotating conditions. Finally, the system identification method is extended to allow forced response measurements from a rotating test to be used as input. The mistuning measured through this approach will reflect all effects present during the operating conditions. One particular advantage of this method is that it can capture the effect of centrifugal loading on the mistuning of conventionally

  4. Fundamental High-Speed Limits in Single-Molecule, Single-Cell, and Nanoscale Force Spectroscopies.

    PubMed

    Amo, Carlos A; Garcia, Ricardo

    2016-07-26

    Force spectroscopy is enhancing our understanding of single-biomolecule, single-cell, and nanoscale mechanics. Force spectroscopy postulates the proportionality between the interaction force and the instantaneous probe deflection. By studying the probe dynamics, we demonstrate that the total force acting on the probe has three different components: the interaction, the hydrodynamic, and the inertial. The amplitudes of those components depend on the ratio between the resonant frequency and the frequency at which the data are measured. A force-distance curve provides a faithful measurement of the interaction force between two molecules when the inertial and hydrodynamic components are negligible. Otherwise, force spectroscopy measurements will underestimate the value of unbinding forces. Neglecting the above force components requires the use of frequency ratios in the 50-500 range. These ratios will limit the use of high-speed methods in force spectroscopy. The theory is supported by numerical simulations.

  5. A study on the fundamental mechanism and the evolutionary driving forces behind aerobic fermentation in yeast.

    PubMed

    Hagman, Arne; Piškur, Jure

    2015-01-01

    Baker's yeast Saccharomyces cerevisiae rapidly converts sugars to ethanol and carbon dioxide at both anaerobic and aerobic conditions. The later phenomenon is called Crabtree effect and has been described in two forms, long-term and short-term effect. We have previously studied under fully controlled aerobic conditions forty yeast species for their central carbon metabolism and the presence of long-term Crabtree effect. We have also studied ten steady-state yeast cultures, pulsed them with glucose, and followed the central carbon metabolism and the appearance of ethanol at dynamic conditions. In this paper we analyzed those wet laboratory data to elucidate possible mechanisms that determine the fate of glucose in different yeast species that cover approximately 250 million years of evolutionary history. We determine overflow metabolism to be the fundamental mechanism behind both long- and short-term Crabtree effect, which originated approximately 125-150 million years ago in the Saccharomyces lineage. The "invention" of overflow metabolism was the first step in the evolution of aerobic fermentation in yeast. It provides a general strategy to increase energy production rates, which we show is positively correlated to growth. The "invention" of overflow has also simultaneously enabled rapid glucose consumption in yeast, which is a trait that could have been selected for, to "starve" competitors in nature. We also show that glucose repression of respiration is confined mainly among S. cerevisiae and closely related species that diverged after the whole genome duplication event, less than 100 million years ago. Thus, glucose repression of respiration was apparently "invented" as a second step to further increase overflow and ethanol production, to inhibit growth of other microbes. The driving force behind the initial evolutionary steps was most likely competition with other microbes to faster consume and convert sugar into biomass, in niches that were semi-anaerobic.

  6. Fundamental High-Speed Limits in Single-Molecule, Single-Cell, and Nanoscale Force Spectroscopies

    PubMed Central

    2016-01-01

    Force spectroscopy is enhancing our understanding of single-biomolecule, single-cell, and nanoscale mechanics. Force spectroscopy postulates the proportionality between the interaction force and the instantaneous probe deflection. By studying the probe dynamics, we demonstrate that the total force acting on the probe has three different components: the interaction, the hydrodynamic, and the inertial. The amplitudes of those components depend on the ratio between the resonant frequency and the frequency at which the data are measured. A force–distance curve provides a faithful measurement of the interaction force between two molecules when the inertial and hydrodynamic components are negligible. Otherwise, force spectroscopy measurements will underestimate the value of unbinding forces. Neglecting the above force components requires the use of frequency ratios in the 50–500 range. These ratios will limit the use of high-speed methods in force spectroscopy. The theory is supported by numerical simulations. PMID:27359243

  7. Fundamental aspects of electric double layer force-distance measurements at liquid-solid interfaces using atomic force microscopy

    PubMed Central

    Black, Jennifer M.; Zhu, Mengyang; Zhang, Pengfei; Unocic, Raymond R.; Guo, Daqiang; Okatan, M. Baris; Dai, Sheng; Cummings, Peter T.; Kalinin, Sergei V.; Feng, Guang; Balke, Nina

    2016-01-01

    Atomic force microscopy (AFM) force-distance measurements are used to investigate the layered ion structure of Ionic Liquids (ILs) at the mica surface. The effects of various tip properties on the measured force profiles are examined and reveal that the measured ion position is independent of tip properties, while the tip radius affects the forces required to break through the ion layers as well as the adhesion force. Force data is collected for different ILs and directly compared with interfacial ion density profiles predicted by molecular dynamics. Through this comparison it is concluded that AFM force measurements are sensitive to the position of the ion with the larger volume and mass, suggesting that ion selectivity in force-distance measurements are related to excluded volume effects and not to electrostatic or chemical interactions between ions and AFM tip. The comparison also revealed that at distances greater than 1 nm the system maintains overall electroneutrality between the AFM tip and sample, while at smaller distances other forces (e.g., van der waals interactions) dominate and electroneutrality is no longer maintained. PMID:27587276

  8. Fundamental aspects of electric double layer force-distance measurements at liquid-solid interfaces using atomic force microscopy

    DOE PAGES

    Black, Jennifer M.; Zhu, Mengyang; Zhang, Pengfei; ...

    2016-09-02

    In this paper, atomic force microscopy (AFM) force-distance measurements are used to investigate the layered ion structure of Ionic Liquids (ILs) at the mica surface. The effects of various tip properties on the measured force profiles are examined and reveal that the measured ion position is independent of tip properties, while the tip radius affects the forces required to break through the ion layers as well as the adhesion force. Force data is collected for different ILs and directly compared with interfacial ion density profiles predicted by molecular dynamics. Through this comparison it is concluded that AFM force measurements aremore » sensitive to the position of the ion with the larger volume and mass, suggesting that ion selectivity in force-distance measurements are related to excluded volume effects and not to electrostatic or chemical interactions between ions and AFM tip. Finally, the comparison also revealed that at distances greater than 1 nm the system maintains overall electroneutrality between the AFM tip and sample, while at smaller distances other forces (e.g., van der waals interactions) dominate and electroneutrality is no longer maintained.« less

  9. Fundamental aspects of electric double layer force-distance measurements at liquid-solid interfaces using atomic force microscopy

    SciTech Connect

    Black, Jennifer M.; Zhu, Mengyang; Zhang, Pengfei; Unocic, Raymond R.; Guo, Daqiang; Okatan, M. Baris; Dai, Sheng; Cummings, Peter T.; Kalinin, Sergei V.; Feng, Guang; Balke, Nina

    2016-09-02

    In this paper, atomic force microscopy (AFM) force-distance measurements are used to investigate the layered ion structure of Ionic Liquids (ILs) at the mica surface. The effects of various tip properties on the measured force profiles are examined and reveal that the measured ion position is independent of tip properties, while the tip radius affects the forces required to break through the ion layers as well as the adhesion force. Force data is collected for different ILs and directly compared with interfacial ion density profiles predicted by molecular dynamics. Through this comparison it is concluded that AFM force measurements are sensitive to the position of the ion with the larger volume and mass, suggesting that ion selectivity in force-distance measurements are related to excluded volume effects and not to electrostatic or chemical interactions between ions and AFM tip. Finally, the comparison also revealed that at distances greater than 1 nm the system maintains overall electroneutrality between the AFM tip and sample, while at smaller distances other forces (e.g., van der waals interactions) dominate and electroneutrality is no longer maintained.

  10. Fundamental aspects of electric double layer force-distance measurements at liquid-solid interfaces using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Black, Jennifer M.; Zhu, Mengyang; Zhang, Pengfei; Unocic, Raymond R.; Guo, Daqiang; Okatan, M. Baris; Dai, Sheng; Cummings, Peter T.; Kalinin, Sergei V.; Feng, Guang; Balke, Nina

    2016-09-01

    Atomic force microscopy (AFM) force-distance measurements are used to investigate the layered ion structure of Ionic Liquids (ILs) at the mica surface. The effects of various tip properties on the measured force profiles are examined and reveal that the measured ion position is independent of tip properties, while the tip radius affects the forces required to break through the ion layers as well as the adhesion force. Force data is collected for different ILs and directly compared with interfacial ion density profiles predicted by molecular dynamics. Through this comparison it is concluded that AFM force measurements are sensitive to the position of the ion with the larger volume and mass, suggesting that ion selectivity in force-distance measurements are related to excluded volume effects and not to electrostatic or chemical interactions between ions and AFM tip. The comparison also revealed that at distances greater than 1 nm the system maintains overall electroneutrality between the AFM tip and sample, while at smaller distances other forces (e.g., van der waals interactions) dominate and electroneutrality is no longer maintained.

  11. Fundamental Studies of Friction, Lubrication, and Wear by Atomic Force Microscopy

    DTIC Science & Technology

    1993-04-14

    34 If fiber interferometer is used RESULTS "*Present address: Department of Chemical Physics, Weirmann Institute The t-p- surface force normal to the...small as 30 nm. The normal force between these tips and diamond (100) and (Il 1) surfaces agrees with calculated dispersion forces . The frictional... force variation on the (100) surface are tentatively associated with a reconstructed geometry convoluted over an asymmetric tip shape, while the (11

  12. Potential of mean force in confined colloids: integral equations with fundamental measure bridge functions.

    PubMed

    Ayadim, A; Malherbe, J G; Amokrane, S

    2005-06-15

    The potential of mean force for uncharged macroparticles suspended in a fluid confined by a wall or a narrow pore is computed for solvent-wall and solvent-macroparticle interactions with attractive forces. Bridge functions taken from Rosenfeld's density-functional theory are used in the reference hypernetted chain closure of the Ornstein-Zernike integral equations. The quality of this closure is assessed by comparison with simulation. As an illustration, the role of solvation forces is investigated. When the "residual" attractive tails are given a range appropriate to "hard sphere-like" colloids, the unexpected role of solvation forces previously observed in bulk colloids is confirmed in the confinement situation.

  13. Supramolecular Polymers with Multiple Types of Binding Motifs: From Fundamental Studies to Multifunctional Materials

    DTIC Science & Technology

    2015-07-10

    the goal of preparing multi-responsive polymer actuators, we have incorporated liquid crystalline metal-binding Bip monomers into polymeric networks...SECURITY CLASSIFICATION OF: This research project is focused on the development and investigation of a new class of multi-stimuli-responsive polymers ...studies metallo and hydrogen bonded supramolecular polymers that exhibit defect healing characteristics and multi- 1. REPORT DATE (DD-MM-YYYY) 4

  14. Force spectroscopy of biomolecular folding and binding: theory meets experiment

    NASA Astrophysics Data System (ADS)

    Dudko, Olga

    2015-03-01

    Conformational transitions in biological macromolecules usually serve as the mechanism that brings biomolecules into their working shape and enables their biological function. Single-molecule force spectroscopy probes conformational transitions by applying force to individual macromolecules and recording their response, or ``mechanical fingerprints,'' in the form of force-extension curves. However, how can we decode these fingerprints so that they reveal the kinetic barriers and the associated timescales of a biological process? I will present an analytical theory of the mechanical fingerprints of macromolecules. The theory is suitable for decoding such fingerprints to extract the barriers and timescales. The application of the theory will be illustrated through recent studies on protein-DNA interactions and the receptor-ligand complexes involved in blood clot formation.

  15. Carbonic anhydrase binding site parameterization in OPLS-AA force field.

    PubMed

    Bernadat, Guillaume; Supuran, Claudiu T; Iorga, Bogdan I

    2013-03-15

    The parameterization of carbonic anhydrase binding site in OPLS-AA force field was performed using quantum chemistry calculations. Both OH2 and OH(-) forms of the binding site were considered, showing important differences in terms of atomic partial charges. Three different parameterization protocols were used, and the results obtained highlighted the importance of including an extended binding site in the charge calculation. The force field parameters were subsequently validated using standard molecular dynamics simulations. The results presented in this work should greatly facilitate the use of molecular dynamics simulations for studying the carbonic anhydrase, and more generally, the metallo-enzymes.

  16. Force-dependent conformational switch of α-catenin controls vinculin binding

    NASA Astrophysics Data System (ADS)

    Yao, Mingxi; Qiu, Wu; Liu, Ruchuan; Efremov, Artem K.; Cong, Peiwen; Seddiki, Rima; Payre, Manon; Lim, Chwee Teck; Ladoux, Benoit; Mège, René-Marc; Yan, Jie

    2014-07-01

    Force sensing at cadherin-mediated adhesions is critical for their proper function. α-Catenin, which links cadherins to actomyosin, has a crucial role in this mechanosensing process. It has been hypothesized that force promotes vinculin binding, although this has never been demonstrated. X-ray structure further suggests that α-catenin adopts a stable auto-inhibitory conformation that makes the vinculin-binding site inaccessible. Here, by stretching single α-catenin molecules using magnetic tweezers, we show that the subdomains MI vinculin-binding domain (VBD) to MIII unfold in three characteristic steps: a reversible step at ~5 pN and two non-equilibrium steps at 10-15 pN. 5 pN unfolding forces trigger vinculin binding to the MI domain in a 1:1 ratio with nanomolar affinity, preventing MI domain refolding after force is released. Our findings demonstrate that physiologically relevant forces reversibly unfurl α-catenin, activating vinculin binding, which then stabilizes α-catenin in its open conformation, transforming force into a sustainable biochemical signal.

  17. Investigating the binding behaviour of two avidin-based testosterone binders using molecular recognition force spectroscopy.

    PubMed

    Rangl, Martina; Leitner, Michael; Riihimäki, Tiina; Lehtonen, Soili; Hytönen, Vesa P; Gruber, Hermann J; Kulomaa, Markku; Hinterdorfer, Peter; Ebner, Andreas

    2014-02-01

    Molecular recognition force spectroscopy, a biosensing atomic force microscopy technique allows to characterise the dissociation of ligand-receptor complexes at the molecular level. Here, we used molecular recognition force spectroscopy to study the binding capability of recently developed testosterone binders. The two avidin-based proteins called sbAvd-1 and sbAvd-2 are expected to bind both testosterone and biotin but differ in their binding behaviour towards these ligands. To explore the ligand binding and dissociation energy landscape of these proteins, we tethered biotin or testosterone to the atomic force microscopy probe while the testosterone-binding protein was immobilized on the surface. Repeated formation and rupture of the ligand-receptor complex at different pulling velocities allowed determination of the loading rate dependence of the complex-rupturing force. In this way, we obtained the molecular dissociation rate (k(off)) and energy landscape distances (x(β)) of the four possible complexes: sbAvd-1-biotin, sbAvd-1-testosterone, sbAvd-2-biotin and sbAvd-2-testosterone. It was found that the kinetic off-rates for both proteins and both ligands are similar. In contrast, the x(β) values, as well as the probability of complex formations, varied considerably. In addition, competitive binding experiments with biotin and testosterone in solution differ significantly for the two testosterone-binding proteins, implying a decreased cross-reactivity of sbAvd-2. Unravelling the binding behaviour of the investigated testosterone-binding proteins is expected to improve their usability for possible sensing applications.

  18. Revised periodic boundary conditions: Fundamentals, electrostatics, and the tight-binding approximation

    NASA Astrophysics Data System (ADS)

    Kit, Oleg O.; Pastewka, Lars; Koskinen, Pekka

    2011-10-01

    Many nanostructures today are low-dimensional and flimsy, and therefore get easily distorted. Distortion-induced symmetry breaking makes conventional, translation-periodic simulations invalid, which has triggered developments for new methods. Revised periodic boundary conditions (RPBC) is a simple method that enables simulations of complex material distortions, either classically or quantum mechanically. The mathematical details of this easy-to-implement approach, however, have not been discussed before. Therefore, in this paper, we summarize the underlying theory, present the practical details of RPBC, especially related to a nonorthogonal tight-binding formulation, discuss selected features, electrostatics in particular, and suggest some examples of usage. We hope this article can give more insight into RPBC, and it will help and inspire new software implementations capable of exploring the physics and chemistry of distorted nanomaterials.

  19. Protonated Nitrous Oxide, NNOH(+): Fundamental Vibrational Frequencies and Spectroscopic Constants from Quartic Force Fields

    NASA Technical Reports Server (NTRS)

    Huang, Xinchuan; Fortenberry, Ryan C.; Lee, Timothy J.

    2013-01-01

    The interstellar presence of protonated nitrous oxide has been suspected for some time. Using established high-accuracy quantum chemical techniques, spectroscopic constants and fundamental vibrational frequencies are provided for the lower energy O-protonated isomer of this cation and its deuterated isotopologue. The vibrationally-averaged B0 and C0 rotational constants are within 6 MHz of their experimental values and the D(subJ) quartic distortion constants agree with experiment to within 3%. The known gas phase O-H stretch of NNOH(+) is 3330.91 cm(exp-1), and the vibrational configuration interaction computed result is 3330.9 cm(exp-1). Other spectroscopic constants are also provided, as are the rest of the fundamental vibrational frequencies for NNOH(+) and its deuterated isotopologue. This high-accuracy data should serve to better inform future observational or experimental studies of the rovibrational bands of protonated nitrous oxide in the ISM and the laboratory.

  20. Going Lean: Impending Money Woes Force Tough Choices, Forecast Fundamental Shift in Community College Funding

    ERIC Educational Resources Information Center

    Joch, Alan

    2011-01-01

    The numbers were already bad, and they keep getting worse, for the Dallas County Community College District (DCCCD). Given the weak economy, administrators planned for a 5 percent reduction in state funding in the 2010-11 academic year. The actual reduction ballooned to more than 7.5 percent, an additional $13 million that DCCCD would be forced to…

  1. Binding Force Dynamics of Streptococcus mutans–glucosyltransferase B to Candida albicans

    PubMed Central

    Hwang, G.; Marsh, G.; Gao, L.; Waugh, R.

    2015-01-01

    Candida albicans cells are often detected with Streptococcus mutans in plaque biofilms from children affected with early childhood caries. The coadhesion between these 2 organisms appears to be largely mediated by the S. mutans–derived exoenzyme glucosyltransferase B (GtfB); GtfB readily binds to C. albicans cells in an active form, producing glucans locally that provide enhanced binding sites for S. mutans. However, knowledge is limited about the mechanisms by which the bacterial exoenzyme binds to and functions on the fungal surface to promote this unique cross-kingdom interaction. In this study, we use atomic force microscopy to understand the strength and binding dynamics modulating GtfB–C. albicans adhesive interactions in situ. Single-molecule force spectroscopy with GtfB-functionalized atomic force microscopy tips demonstrated that the enzyme binds with remarkable strength to the C. albicans cell surface (~2 nN) and showed a low dissociation rate, suggesting a highly stable bond. Strikingly, the binding strength of GtfB to the C. albicans surface was ~2.5-fold higher and the binding stability, ~20 times higher, as compared with the enzyme adhesion to S. mutans. Furthermore, adhesion force maps showed an intriguing pattern of GtfB binding. GtfB adhered heterogeneously on the surface of C. albicans, showing a higher frequency of adhesion failure but large sections of remarkably strong binding forces, suggesting the presence of GtfB binding domains unevenly distributed on the fungal surface. In contrast, GtfB bound uniformly across the S. mutans cell surface with less adhesion failure and a narrower range of binding forces (vs. the C. albicans surface). The data provide the first insights into the mechanisms underlying the adhesive and mechanical properties governing GtfB interactions with C. albicans. The strong and highly stable GtfB binding to C. albicans could explain, at least in part, why this bacterially derived exoenzyme effectively modulates this

  2. Calculating binding free energies of host-guest systems using the AMOEBA polarizable force field.

    PubMed

    Bell, David R; Qi, Rui; Jing, Zhifeng; Xiang, Jin Yu; Mejias, Christopher; Schnieders, Michael J; Ponder, Jay W; Ren, Pengyu

    2016-11-09

    Molecular recognition is of paramount interest in many applications. Here we investigate a series of host-guest systems previously used in the SAMPL4 blind challenge by using molecular simulations and the AMOEBA polarizable force field. The free energy results computed by Bennett's acceptance ratio (BAR) method using the AMOEBA polarizable force field ranked favorably among the entries submitted to the SAMPL4 host-guest competition [Muddana, et al., J. Comput.-Aided Mol. Des., 2014, 28, 305-317]. In this work we conduct an in-depth analysis of the AMOEBA force field host-guest binding thermodynamics by using both BAR and the orthogonal space random walk (OSRW) methods. The binding entropy-enthalpy contributions are analyzed for each host-guest system. For systems of inordinate binding entropy-enthalpy values, we further examine the hydrogen bonding patterns and configurational entropy contribution. The binding mechanism of this series of host-guest systems varies from ligand to ligand, driven by enthalpy and/or entropy changes. Convergence of BAR and OSRW binding free energy methods is discussed. Ultimately, this work illustrates the value of molecular modelling and advanced force fields for the exploration and interpretation of binding thermodynamics.

  3. How Force Might Activate Talin's Vinculin Binding Sites: SMD Reveals a Structural Mechanism

    PubMed Central

    Hytönen, Vesa P; Vogel, Viola

    2008-01-01

    Upon cell adhesion, talin physically couples the cytoskeleton via integrins to the extracellular matrix, and subsequent vinculin recruitment is enhanced by locally applied tensile force. Since the vinculin binding (VB) sites are buried in the talin rod under equilibrium conditions, the structural mechanism of how vinculin binding to talin is force-activated remains unknown. Taken together with experimental data, a biphasic vinculin binding model, as derived from steered molecular dynamics, provides high resolution structural insights how tensile mechanical force applied to the talin rod fragment (residues 486–889 constituting helices H1–H12) might activate the VB sites. Fragmentation of the rod into three helix subbundles is prerequisite to the sequential exposure of VB helices to water. Finally, unfolding of a VB helix into a completely stretched polypeptide might inhibit further binding of vinculin. The first events in fracturing the H1–H12 rods of talin1 and talin2 in subbundles are similar. The proposed force-activated α-helix swapping mechanism by which vinculin binding sites in talin rods are exposed works distinctly different from that of other force-activated bonds, including catch bonds. PMID:18282082

  4. Assembly of reconfigurable one-dimensional colloidal superlattices due to a synergy of fundamental nanoscale forces

    PubMed Central

    Young, Kaylie L.; Jones, Matthew R.; Zhang, Jian; Macfarlane, Robert J.; Esquivel-Sirvent, Raul; Nap, Rikkert J.; Wu, Jinsong; Schatz, George C.; Lee, Byeongdu; Mirkin, Chad A.

    2012-01-01

    We report that triangular gold nanoprisms in the presence of attractive depletion forces and repulsive electrostatic forces assemble into equilibrium one-dimensional lamellar crystals in solution with interparticle spacings greater than four times the thickness of the nanoprisms. Experimental and theoretical studies reveal that the anomalously large d spacings of the lamellar superlattices are due to a balance between depletion and electrostatic interactions, both of which arise from the surfactant cetyltrimethylammonium bromide. The effects of surfactant concentration, temperature, ionic strength of the solution, and prism edge length on the lattice parameters have been investigated and provide a variety of tools for in situ modulation of these colloidal superstructures. Additionally, we demonstrate a purification procedure based on our observations that can be used to efficiently separate triangular nanoprisms from spherical nanoparticles formed concomitantly during their synthesis. PMID:22308436

  5. Noncontact Atomic Force Microscopy: An Emerging Tool for Fundamental Catalysis Research.

    PubMed

    Altman, Eric I; Baykara, Mehmet Z; Schwarz, Udo D

    2015-09-15

    Although atomic force microscopy (AFM) was rapidly adopted as a routine surface imaging apparatus after its introduction in 1986, it has not been widely used in catalysis research. The reason is that common AFM operating modes do not provide the atomic resolution required to follow catalytic processes; rather the more complex noncontact (NC) mode is needed. Thus, scanning tunneling microscopy has been the principal tool for atomic scale catalysis research. In this Account, recent developments in NC-AFM will be presented that offer significant advantages for gaining a complete atomic level view of catalysis. The main advantage of NC-AFM is that the image contrast is due to the very short-range chemical forces that are of interest in catalysis. This motivated our development of 3D-AFM, a method that yields quantitative atomic resolution images of the potential energy surfaces that govern how molecules approach, stick, diffuse, and rebound from surfaces. A variation of 3D-AFM allows the determination of forces required to push atoms and molecules on surfaces, from which diffusion barriers and variations in adsorption strength may be obtained. Pushing molecules towards each other provides access to intermolecular interaction between reaction partners. Following reaction, NC-AFM with CO-terminated tips yields textbook images of intramolecular structure that can be used to identify reaction intermediates and products. Because NC-AFM and STM contrast mechanisms are distinct, combining the two methods can produce unique insight. It is demonstrated for surface-oxidized Cu(100) that simultaneous 3D-AFM/STM yields resolution of both the Cu and O atoms. Moreover, atomic defects in the Cu sublattice lead to variations in the reactivity of the neighboring O atoms. It is shown that NC-AFM also allows a straightforward imaging of work function variations which has been used to identify defect charge states on catalytic surfaces and to map charge transfer within an individual

  6. Resolving dual binding conformations of cellulosome cohesin-dockerin complexes using single-molecule force spectroscopy.

    PubMed

    Jobst, Markus A; Milles, Lukas F; Schoeler, Constantin; Ott, Wolfgang; Fried, Daniel B; Bayer, Edward A; Gaub, Hermann E; Nash, Michael A

    2015-10-31

    Receptor-ligand pairs are ordinarily thought to interact through a lock and key mechanism, where a unique molecular conformation is formed upon binding. Contrary to this paradigm, cellulosomal cohesin-dockerin (Coh-Doc) pairs are believed to interact through redundant dual binding modes consisting of two distinct conformations. Here, we combined site-directed mutagenesis and single-molecule force spectroscopy (SMFS) to study the unbinding of Coh:Doc complexes under force. We designed Doc mutations to knock out each binding mode, and compared their single-molecule unfolding patterns as they were dissociated from Coh using an atomic force microscope (AFM) cantilever. Although average bulk measurements were unable to resolve the differences in Doc binding modes due to the similarity of the interactions, with a single-molecule method we were able to discriminate the two modes based on distinct differences in their mechanical properties. We conclude that under native conditions wild-type Doc from Clostridium thermocellum exocellulase Cel48S populates both binding modes with similar probabilities. Given the vast number of Doc domains with predicted dual binding modes across multiple bacterial species, our approach opens up new possibilities for understanding assembly and catalytic properties of a broad range of multi-enzyme complexes.

  7. Evidence for a force-dependent component of calcium binding to cardiac troponin C

    SciTech Connect

    Hofmann, P.A.; Fuchs, F. )

    1987-10-01

    The duration of activation in cardiac muscle is a function of the load. On the basis of studies of Ca{sup 2+} transients in muscles subjected to quick release, it has been suggested that force or shortening-mediated changes in Ca{sup 2+}-troponin C affinity may provide a mechanism for a contraction-activation feedback. This study was designed to test the hypothesis that the formation of force-generating complexes between actin and myosin enhances the affinity of cardiac troponin C for Ca{sup 2+}. This was done by first establishing the normal relationship between Ca{sup 2+} binding and force development in chemically skinned bovine ventricular muscle bundles and then comparing the Ca{sup 2+}-saturation curves obtained with relaxed and contracting muscle bundles. A double isotope technique was used to measure Ca{sup 2+} binding during ATP-induced force generation and during relaxation maintained by the phosphate analogue vanadate. The results showed that the generation of force was associated with an enhanced binding of Ca{sup 2+} to the Ca{sup 2+}-specific regulatory site of cardiac troponin C. These data provide direct evidence that feedback between force and activation in the heart may be mediated by the Ca{sup 2+}-regulatory site of troponin C.

  8. Effects of dielectric charging on fundamental forces and reliability in capacitive microelectromechanical systems radio frequency switch contacts

    NASA Astrophysics Data System (ADS)

    Patton, Steven T.; Zabinski, Jeffrey S.

    2006-05-01

    Microelectromechanical systems (MEMS) radio frequency switches hold great promise in a myriad of commercial, aerospace, and military applications. In particular, capacitive-type switches with metal-to-dielectric contacts (typically gold-on-silicon nitride) are suitable for high frequency (>=10 GHz) applications. However, the devices are known to be unstable in their performance due to parasitic dielectric charging. Although several authors have previously reported the switch failure along with shifts in pull-down and release voltages due to charging, there is some disagreement and lack of understanding among the various reports. This study uses a switch simulator capable of measuring microscale electrostatic and adhesive forces to investigate charging and its effect on reliability and fundamental forces acting within MEMS capacitive switches. An important advantage of the switch simulator is that it can be actuated with or without a bias voltage. Electrostatic force and dielectric charging increased as surfaces were worn smooth by cycling. This is because the surface smoothening decreases separation and increases the electric field strength inside the dielectric. A simple analytical model was developed using electromagnetic theory for the electrostatic force in terms of bias voltage and the areal density of parasitic charge. Using the model and experimental data, it was determined that ``charging'' (net charge is zero) with the same polarity as the bias voltage resulted in reduced electrostatic force (under bias voltage) when a worn-in switch was actuated repeatedly at constant bias voltage >=40 V. Small electrostatic force under bias voltage can explain failure in the ``up'' position (failure to actuate and self-release). Reversing the polarity of the bias voltage between actuations prevented charge buildup and doubled the electrostatic force, which can help explain the effectiveness of bipolar actuation. The charging time constant for parasitic dielectric charge

  9. Polypyrimidine tract binding protein homologs from Arabidopsis are key regulators of alternative splicing with implications in fundamental developmental processes.

    PubMed

    Rühl, Christina; Stauffer, Eva; Kahles, André; Wagner, Gabriele; Drechsel, Gabriele; Rätsch, Gunnar; Wachter, Andreas

    2012-11-01

    Alternative splicing (AS) generates transcript variants by variable exon/intron definition and massively expands transcriptome diversity. Changes in AS patterns have been found to be linked to manifold biological processes, yet fundamental aspects, such as the regulation of AS and its functional implications, largely remain to be addressed. In this work, widespread AS regulation by Arabidopsis thaliana Polypyrimidine tract binding protein homologs (PTBs) was revealed. In total, 452 AS events derived from 307 distinct genes were found to be responsive to the levels of the splicing factors PTB1 and PTB2, which predominantly triggered splicing of regulated introns, inclusion of cassette exons, and usage of upstream 5' splice sites. By contrast, no major AS regulatory function of the distantly related PTB3 was found. Dependent on their position within the mRNA, PTB-regulated events can both modify the untranslated regions and give rise to alternative protein products. We find that PTB-mediated AS events are connected to diverse biological processes, and the functional implications of selected instances were further elucidated. Specifically, PTB misexpression changes AS of PHYTOCHROME INTERACTING FACTOR6, coinciding with altered rates of abscisic acid-dependent seed germination. Furthermore, AS patterns as well as the expression of key flowering regulators were massively changed in a PTB1/2 level-dependent manner.

  10. Electrostatic binding and hydrophobic collapse of peptide-nucleic acid aggregates quantified using force spectroscopy.

    PubMed

    Camunas-Soler, Joan; Frutos, Silvia; Bizarro, Cristiano V; de Lorenzo, Sara; Fuentes-Perez, Maria Eugenia; Ramsch, Roland; Vilchez, Susana; Solans, Conxita; Moreno-Herrero, Fernando; Albericio, Fernando; Eritja, Ramón; Giralt, Ernest; Dev, Sukhendu B; Ritort, Felix

    2013-06-25

    Knowledge of the mechanisms of interaction between self-aggregating peptides and nucleic acids or other polyanions is key to the understanding of many aggregation processes underlying several human diseases (e.g., Alzheimer's and Parkinson's diseases). Determining the affinity and kinetic steps of such interactions is challenging due to the competition between hydrophobic self-aggregating forces and electrostatic binding forces. Kahalalide F (KF) is an anticancer hydrophobic peptide that contains a single positive charge that confers strong aggregative properties with polyanions. This makes KF an ideal model to elucidate the mechanisms by which self-aggregation competes with binding to a strongly charged polyelectrolyte such as DNA. We use optical tweezers to apply mechanical forces to single DNA molecules and show that KF and DNA interact in a two-step kinetic process promoted by the electrostatic binding of DNA to the aggregate surface followed by the stabilization of the complex due to hydrophobic interactions. From the measured pulling curves we determine the spectrum of binding affinities, kinetic barriers, and lengths of DNA segments sequestered within the KF-DNA complex. We find there is a capture distance beyond which the complex collapses into compact aggregates stabilized by strong hydrophobic forces and discuss how the bending rigidity of the nucleic acid affects this process. We hypothesize that within an in vivo context, the enhanced electrostatic interaction of KF due to its aggregation might mediate the binding to other polyanions. The proposed methodology should be useful to quantitatively characterize other compounds or proteins in which the formation of aggregates is relevant.

  11. A programmable DNA origami nanospring that reveals force-induced adjacent binding of myosin VI heads.

    PubMed

    Iwaki, M; Wickham, S F; Ikezaki, K; Yanagida, T; Shih, W M

    2016-12-12

    Mechanosensitive biological nanomachines such as motor proteins and ion channels regulate diverse cellular behaviour. Combined optical trapping with single-molecule fluorescence imaging provides a powerful methodology to clearly characterize the mechanoresponse, structural dynamics and stability of such nanomachines. However, this system requires complicated experimental geometry, preparation and optics, and is limited by low data-acquisition efficiency. Here we develop a programmable DNA origami nanospring that overcomes these issues. We apply our nanospring to human myosin VI, a mechanosensory motor protein, and demonstrate nanometre-precision single-molecule fluorescence imaging of the individual motor domains (heads) under force. We observe force-induced transitions of myosin VI heads from non-adjacent to adjacent binding, which correspond to adapted roles for low-load and high-load transport, respectively. Our technique extends single-molecule studies under force and clarifies the effect of force on biological processes.

  12. A programmable DNA origami nanospring that reveals force-induced adjacent binding of myosin VI heads

    PubMed Central

    Iwaki, M.; Wickham, S. F.; Ikezaki, K.; Yanagida, T.; Shih, W. M.

    2016-01-01

    Mechanosensitive biological nanomachines such as motor proteins and ion channels regulate diverse cellular behaviour. Combined optical trapping with single-molecule fluorescence imaging provides a powerful methodology to clearly characterize the mechanoresponse, structural dynamics and stability of such nanomachines. However, this system requires complicated experimental geometry, preparation and optics, and is limited by low data-acquisition efficiency. Here we develop a programmable DNA origami nanospring that overcomes these issues. We apply our nanospring to human myosin VI, a mechanosensory motor protein, and demonstrate nanometre-precision single-molecule fluorescence imaging of the individual motor domains (heads) under force. We observe force-induced transitions of myosin VI heads from non-adjacent to adjacent binding, which correspond to adapted roles for low-load and high-load transport, respectively. Our technique extends single-molecule studies under force and clarifies the effect of force on biological processes. PMID:27941751

  13. Determining force dependence of two-dimensional receptor-ligand binding affinity by centrifugation.

    PubMed Central

    Piper, J W; Swerlick, R A; Zhu, C

    1998-01-01

    Analyses of receptor-ligand interactions are important to the understanding of cellular adhesion. Traditional methods of measuring the three-dimensional (3D) dissociation constant (Kd) require at least one of the molecular species in solution and hence cannot be directly applied to the case of cell adhesion. We describe a novel method of measuring 2D binding characteristics of receptors and ligands that are attached to surfaces and whose bonds are subjected to forces. The method utilizes a common centrifugation assay to quantify adhesion. A model for the experiment has been formulated, solved exactly, and tested carefully. The model is stochastically based and couples the bond force to the binding affinity. The method was applied to examine tumor cell adherence to recombinant E-selectin. Satisfactory agreement was found between predictions and data. The estimated zero-force 2D Kd for E-selectin/carbohydrate ligand binding was approximately 5 x 10(3) microm(-2), and the bond interaction range was subangstrom. Our results also suggest that the number of bonds mediating adhesion was small (<5). PMID:9449350

  14. Improving fundamental abilities of atomic force microscopy for investigating quantitative nanoscale physical properties of complex biological systems

    NASA Astrophysics Data System (ADS)

    Cartagena-Rivera, Alexander X.

    Measurements of local material properties of complex biological systems (e.g. live cells and viruses) in their respective physiological conditions are extremely important in the fields of biophysics, nanotechnology, material science, and nanomedicine. Yet, little is known about the structure-function-property relationship of live cells and viruses. In the case of live cells, the measurements of progressive variations in viscoelastic properties in vitro can provide insight to the mechanistic processes underpinning morphogenesis, mechano-transduction, motility, metastasis, and many more fundamental cellular processes. In the case of living viruses, the relationship between capsid structural framework and the role of the DNA molecule interaction within viruses influencing their stiffness, damping and electrostatic properties can shed light in virological processes like protein subunits assembly/dissassembly, maturation, and infection. The study of mechanics of live cells and viruses has been limited in part due to the lack of technology capable of acquiring high-resolution (nanoscale, subcellular) images of its heterogeneous material properties which vary widely depending on origin and physical interaction. The capabilities of the atomic force microscope (AFM) for measuring forces and topography with sub-nm precision have greatly contributed to research related to biophysics and biomechanics during the past two decades. AFM based biomechanical studies have the unique advantage of resolving/mapping spatially the local material properties over living cells and viruses. However, conventional AFM techniques such as force-volume and quasi-static force-distance curves are too low resolution and low speed to resolve interesting biophysical processes such as cytoskeletal dynamics for cells or assembly/dissasembly of viruses. To overcome this bottleneck, a novel atomic force microscopy mode is developed, that leads to sub-10-nm resolution and sub-15-minutes mapping of local

  15. DNA interaction with DAPI fluorescent dye: Force spectroscopy decouples two different binding modes.

    PubMed

    Reis, L A; Rocha, M S

    2017-05-01

    In this work, we use force spectroscopy to investigate the interaction between the DAPI fluorescent dye and the λ-DNA molecule under high (174 mM) and low (34 mM) ionic strengths. Firstly, we have measured the changes on the mechanical properties (persistence and contour lengths) of the DNA-DAPI complexes as a function of the dye concentration in the sample. Then, we use recently developed models in order to connect the behavior of both mechanical properties to the physical chemistry of the interaction. Such analysis has allowed us to identify and to decouple two main binding modes, determining the relevant physicochemical (binding) parameters for each of these modes: minor groove binding, which saturates at very low DAPI concentrations ( CT ∼ 0.50 μM) and presents equilibrium binding constants of the order of ∼10(7) M(-1) for the two ionic strengths studied; and intercalation, which starts to play a significant role only after the saturation of the first mode, presenting much smaller equilibrium binding constants (∼10(5) M(-1) ).

  16. Electron binding energies and the fundamental gap of a push-pull dye in a polar environment: p-nitroaniline in liquid water

    NASA Astrophysics Data System (ADS)

    Cabral, Benedito J. C.

    2017-01-01

    The outer valence electron binding energies and the fundamental gap of p-nitroaniline (PNA) in water were determined by electron propagator theory. The adopted methodology relies on the calculation of electron binding energies by using configurations generated by Born-Oppenheimer molecular dynamics of PNA in water. The fundamental gap (Eg) of PNA in water was estimated from the first ionisation energy (IE) and the first vertical electron affinity VEA (Eg = IE-VEA). In liquid water Eg is predicted to be 6.5 ± 0.5 eV (OVGF), which is ∼3.3 eV greater than the experimental optical gap (3.25 eV).

  17. Quantum dot binding to DNA: single-molecule imaging with atomic force microscopy.

    PubMed

    Li, Kungang; Zhang, Wen; Chen, Yongsheng

    2013-01-01

    The interaction between nanoparticles (NPs) and DNA is of significance for both application and implication research of NPs. In this study, a single-molecule imaging technique based on atomic force microscopy (AFM) was employed to probe the NP-DNA interactions with quantum dots (QDs) as model NPs. Reproducible high-quality images of single DNA molecules in air and in liquids were acquired on mica by optimizing sample preparation conditions. Furthermore, the binding of QDs to DNA was explored using AFM. The DNA concentration was found to be a key factor influencing AFM imaging quality. In air and liquids, the optimal DNA concentration for imaging DNA molecules was approximately 2.5 and 0.25 μg/mL, and that for imaging DNA binding with QDs was 0.5 and 0.25 μg/mL, respectively. In the presence of QDs, the DNA conformation was altered with the formation of DNA condensates. Finally, the fine conformation of QD-DNA binding sites was examined to analyze the binding mechanisms. This work will benefit investigations of NP-DNA interactions and the understanding of the structure of NP-DNA bioconjugates. See accompanying article by Wang DOI: 10.1002/biot.201200309.

  18. Understanding chemical binding using the Berlin function and the reaction force

    NASA Astrophysics Data System (ADS)

    Chakraborty, Debajit; Cárdenas, Carlos; Echegaray, Eleonora; Toro-Labbe, Alejandro; Ayers, Paul W.

    2012-06-01

    We use the derivative of the electron density with respect to the reaction coordinate, interpreted through the Berlin binding function, to identify portions of the reaction path where chemical bonds are breaking and forming. The results agree with the conventional description for SN2 reactions, but they are much more general and can be used to elucidate other types of reactions also. Our analysis offers support for, and detailed information about, the use of the reaction force profile to separate the reaction coordinates into intervals, each with characteristic extents of geometry change and electronic rearrangement.

  19. Pion tensor force and nuclear binding energy in the relativistic Hartree-Fock formalism

    NASA Astrophysics Data System (ADS)

    Marcos, S.; López-Quelle, M.; Niembro, R.; Savushkin, L. N.

    2014-03-01

    The binding energies of several isotopic families are studied within the relativistic Hartree-Fock approximation with the pseudovector coupling for the πN vertex, to find out a suitable strength for the effective pion tensor force (EPTF). An approximation for determining separately the contributions of the central and tensor forces generated by pion is considered. The results for heavy nuclei indicate that a realistic strength for the EPTF is smaller than a half of that appearing in the OPEP. This conclusion also applies to the results for the single-particle energies. Besides, it has been found that there is a genuine relativistic contribution of the EPTF in nuclear matter which is small but significant.

  20. Elementary Particles and Forces.

    ERIC Educational Resources Information Center

    Quigg, Chris

    1985-01-01

    Discusses subatomic particles (quarks, leptons, and others) revealed by higher accelerator energies. A connection between forces at this subatomic level has been established, and prospects are good for a description of forces that encompass binding atomic nuclei. Colors, fundamental interactions, screening, camouflage, electroweak symmetry, and…

  1. Progressing single biomolecule force spectroscopy measurements for the screening of DNA binding agents

    NASA Astrophysics Data System (ADS)

    Zhang, Wenke; Barbagallo, Romina; Madden, Claire; Roberts, Clive J.; Woolford, Alison; Allen, Stephanie

    2005-10-01

    Recent studies have indicated that the force-extension properties of single molecules of double stranded (ds) DNA are sensitive to the presence of small molecule DNA binding agents, and also to their mode of binding. These observations raise the possibility of using this approach as a highly sensitive tool for the screening of such agents. However, particularly for studies employing the atomic force microscope (AFM), several non-trivial barriers hinder the progress of this approach to the non-specialist arena and hence also the full realization of this possibility. In this paper, we therefore address a series of key reproducibility and metrological issues associated with this type of measurement. Specifically, we present an improved immobilization method that covalently anchors one end (5' end) of a dual labelled (5'-thiol, 3'-biotin) p53 DNA molecule onto a gold substrate via gold-thiol chemistry, whilst the biotinylated 3' end is available for 'pick-up' using a streptavidin modified AFM tip. We also show that co-surface immobilization of DNA with 6-mercapto-1-hexanol (MCH) can also lead to a further increase the measured contour length. We demonstrate the impact of these improved protocols through the observation of the cooperative transition plateau in a DNA fragment of approximately 118 bp, a significantly smaller fragment than previously investigated. The results of a comparative study of the effects of a model minor groove binder (Hoechst 33258) and an intercalating drug (proflavine), alone, as a mixture and under different buffer conditions, are also presented.

  2. Binding Dynamics of Targeted Microbubbles in Response to Modulated Acoustic Radiation Force

    PubMed Central

    Wang, Shiying; Hossack, John A; Klibanov, Alexander L; Mauldin, F William

    2014-01-01

    Detection of molecular targeted microbubbles plays a foundational role in ultrasound-based molecular imaging and targeted gene or drug delivery. In this paper, an empirical model describing the binding dynamics of targeted microbubbles in response to modulated acoustic radiation forces in large vessels is presented and experimentally verified using tissue-mimicking flow phantoms. Higher flow velocity and microbubble concentration led to faster detaching rates for specifically bound microbubbles (p < 0.001). Higher time-averaged acoustic radiation force intensity led to faster attaching rates and a higher saturation level of specifically bound microbubbles (p < 0.05). The level of residual microbubble signal in targeted experiments after cessation of radiation forces was the only response parameter that was reliably different between targeted and control experiments (p < 0.05). A related parameter, the ratio of residual-to-saturated microbubble signal (Rresid), is proposed as a measurement that is independent of absolute acoustic signal magnitude and therefore able to reliably detect targeted adhesion independently of control measurements (p < 0.01). These findings suggest the possibility of enhanced detection of specifically bound microbubbles in real-time, using relatively short imaging protocols (approximately 3 min), without waiting for free microbubble clearance. PMID:24374866

  3. Directed Binding of Gliding Bacterium, Mycoplasma mobile, Shown by Detachment Force and Bond Lifetime

    PubMed Central

    Tanaka, Akihiro; Nakane, Daisuke; Mizutani, Masaki; Nishizaka, Takayuki

    2016-01-01

    ABSTRACT Mycoplasma mobile, a fish-pathogenic bacterium, features a protrusion that enables it to glide smoothly on solid surfaces at a velocity of up to 4.5 µm s−1 in the direction of the protrusion. M. mobile glides by a repeated catch-pull-release of sialylated oligosaccharides fixed on a solid surface by hundreds of 50-nm flexible “legs” sticking out from the protrusion. This gliding mechanism may be explained by a possible directed binding of each leg with sialylated oligosaccharides, by which the leg can be detached more easily forward than backward. In the present study, we used a polystyrene bead held by optical tweezers to detach a starved cell at rest from a glass surface coated with sialylated oligosaccharides and concluded that the detachment force forward is 1.6- to 1.8-fold less than that backward, which may be linked to a catch bond-like behavior of the cell. These results suggest that this directed binding has a critical role in the gliding mechanism. PMID:27353751

  4. The Role of Caldesmon and its Phosphorylation by ERK on the Binding Force of Unphosphorylated Myosin to Actin

    PubMed Central

    Roman, Horia Nicolae; Zitouni, Nedjma B.; Kachmar, Linda; Benedetti, Andrea; Sobieszek, Apolinary; Lauzon, Anne-Marie

    2014-01-01

    Background Studies conducted at the whole muscle level have shown that smooth muscle can maintain tension with low ATP consumption. Whereas it is generally accepted that this property (latch-state) is a consequence of the dephosphorylation of myosin during its attachment to actin, free dephosphorylated myosin can also bind to actin and contribute to force maintenance. We investigated the role of caldesmon (CaD) in regulating the binding force of unphosphorylated tonic smooth muscle myosin to actin. Methods To measure the effect of CaD on the binding of unphosphorylated myosin to actin (in the presence of ATP), we used a single beam laser trap assay to quantify the average unbinding force (Funb) in the absence or presence of caldesmon, ERK-phosphorylated CaD, or CaD plus tropomyosin. Results Funb from unregulated actin (0.10 ± 0.01 pN) was significantly increased in the presence of CaD (0.17 ± 0.02 pN), tropomyosin (0.17 ± 0.02 pN) or both regulatory proteins (0.18 ± 0.02 pN). ERK phosphorylation of CaD significantly reduced the Funb (0.06 ± 0.01 pN). Inspection of the traces of the Funb as a function of time suggests that ERK phosphorylation of CaD decreases the binding force of myosin to actin or accelerates its detachment. Conclusions CaD enhances the binding force of unphosphorylated myosin to actin potentially contributing to the latch-state. ERK phosphorylation of CaD decreases this binding force to very low levels. General Significance This study suggests a mechanism that likely contributes to the latch-state and that explains the muscle relaxation from the latch-state. PMID:25108062

  5. Fibronectin forms the most extensible biological fibers displaying switchable force-exposed cryptic binding sites

    PubMed Central

    Klotzsch, Enrico; Smith, Michael L.; Kubow, Kristopher E.; Muntwyler, Simon; Little, William C.; Beyeler, Felix; Gourdon, Delphine; Nelson, Bradley J.; Vogel, Viola

    2009-01-01

    Rather than maximizing toughness, as needed for silk and muscle titin fibers to withstand external impact, the much softer extracellular matrix fibers made from fibronectin (Fn) can be stretched by cell generated forces and display extraordinary extensibility. We show that Fn fibers can be extended more than 8-fold (>700% strain) before 50% of the fibers break. The Young's modulus of single fibers, given by the highly nonlinear slope of the stress-strain curve, changes orders of magnitude, up to MPa. Although many other materials plastically deform before they rupture, evidence is provided that the reversible breakage of force-bearing backbone hydrogen bonds enables the large strain. When tension is released, the nano-sized Fn domains first contract in the crowded environment of fibers within seconds into random coil conformations (molten globule states), before the force-bearing hydrogen bond networks that stabilize the domain's secondary structures are reestablished within minutes (double exponential). The exposure of cryptic binding sites on Fn type III modules increases steeply upon stretching. Thus fiber extension steadily up-regulates fiber rigidity and cryptic epitope exposure, both of which are known to differentially alter cell behavior. Finally, since stress-strain relationships cannot directly be measured in native extracellular matrix (ECM), the stress-strain curves were correlated with stretch-induced alterations of intramolecular fluorescence resonance energy transfer (FRET) obtained from trace amounts of Fn probes (mechanical strain sensors) that can be incorporated into native ECM. Physiological implications of the extraordinary extensibility of Fn fibers and contraction kinetics are discussed. PMID:19826086

  6. Oriented covalent immobilization of antibodies for measurement of intermolecular binding forces between zipper-like contact surfaces of split inteins

    PubMed Central

    Sorci, Mirco; Dassa, Bareket; Liu, Hongwei; Anand, Gaurav; Dutta, Amit K.; Pietrokovski, Shmuel; Belfort, Marlene; Belfort, Georges

    2013-01-01

    In order to measure the intermolecular binding forces between two halves (or partners) of naturally split protein splicing elements called inteins, a novel thiol-hydrazide linker was designed and used to orient immobilized antibodies specific for each partner. Activation of the surfaces was achieved in one step allowing direct force measurements of the formation of a peptide bond catalyzed by the binding of the two partners of the split intein (called protein trans-splicing). Through this binding process, a whole functional intein is formed resulting in subsequent splicing. Atomic force microscopy (AFM) was used to directly measure the split intein partner binding at 1µm/s between native (wild-type) and mixed pairs of C- and N-terminal partners of naturally occurring split inteins from three cyanobacteria. Native and mixed pairs exhibit similar binding forces within the error of the measurement technique (~52 pN). Bioinformatic sequence analysis and computational structural analysis discovered a zipper-like contact between the two partners with electrostatic and non-polar attraction between multiple aligned ion pairs and hydrophobic residues. Also, we tested the Jarzynski’s equality and demonstrated, as expected, that non-equilibrium dissipative measurements obtained here gave larger energies of interaction as compared with those for equilibrium. Hence, AFM coupled with our immobilization strategy and computational studies provides a useful analytical tool for the direct measurement of intermolecular association of split inteins and could be extended to any interacting protein pair. PMID:23679912

  7. Fundamental ecology is fundamental.

    PubMed

    Courchamp, Franck; Dunne, Jennifer A; Le Maho, Yvon; May, Robert M; Thébaud, Christophe; Hochberg, Michael E

    2015-01-01

    The primary reasons for conducting fundamental research are satisfying curiosity, acquiring knowledge, and achieving understanding. Here we develop why we believe it is essential to promote basic ecological research, despite increased impetus for ecologists to conduct and present their research in the light of potential applications. This includes the understanding of our environment, for intellectual, economical, social, and political reasons, and as a major source of innovation. We contend that we should focus less on short-term, objective-driven research and more on creativity and exploratory analyses, quantitatively estimate the benefits of fundamental research for society, and better explain the nature and importance of fundamental ecology to students, politicians, decision makers, and the general public. Our perspective and underlying arguments should also apply to evolutionary biology and to many of the other biological and physical sciences.

  8. Free energy profiles of cocaine esterase-cocaine binding process by molecular dynamics and potential of mean force simulations.

    PubMed

    Zhang, Yuxin; Huang, Xiaoqin; Han, Keli; Zheng, Fang; Zhan, Chang-Guo

    2016-11-25

    The combined molecular dynamics (MD) and potential of mean force (PMF) simulations have been performed to determine the free energy profile of the CocE)-(+)-cocaine binding process in comparison with that of the corresponding CocE-(-)-cocaine binding process. According to the MD simulations, the equilibrium CocE-(+)-cocaine binding mode is similar to the CocE-(-)-cocaine binding mode. However, based on the simulated free energy profiles, a significant free energy barrier (∼5 kcal/mol) exists in the CocE-(+)-cocaine binding process whereas no obvious free energy barrier exists in the CocE-(-)-cocaine binding process, although the free energy barrier of ∼5 kcal/mol is not high enough to really slow down the CocE-(+)-cocaine binding process. In addition, the obtained free energy profiles also demonstrate that (+)-cocaine and (-)-cocaine have very close binding free energies with CocE, with a negligible difference (∼0.2 kcal/mol), which is qualitatively consistent with the nearly same experimental KM values of the CocE enzyme for (+)-cocaine and (-)-cocaine. The consistency between the computational results and available experimental data suggests that the mechanistic insights obtained from this study are reasonable.

  9. Water-mediated forces between the nucleotide binding domains generate the power stroke in an ABC transporter

    NASA Astrophysics Data System (ADS)

    Furukawa-Hagiya, Tomoka; Yoshida, Norio; Chiba, Shuntaro; Hayashi, Tomohiko; Furuta, Tadaomi; Sohma, Yoshiro; Sakurai, Minoru

    2014-11-01

    ATP binding cassette proteins shuttle a variety of molecules across cell membranes. The substrate transportation process is initiated by the ATP-driven dimerization of nucleotide binding domains (NBDs). Here, the integral-equation theory of liquids was applied to simulated NBD structures to analyze their dimerization process from the viewpoint of thermodynamics and the water-mediated interaction between the NBDs. It was found that a long-range hydration force of enthalpic origin drives the two NBDs to approach from a large separation. In the subsequent step, the water-mediated attraction of entropic origin brings about a structural adjustment between the two NBDs and their tighter contact.

  10. Prediction of SAMPL3 Host-Guest Binding Affinities: Evaluating the Accuracy of Generalized Force-Fields

    PubMed Central

    Muddana, Hari S.; Gilson, Michael K.

    2012-01-01

    We used the second-generation mining minima method (M2) to compute the binding affinities of the novel host-guest complexes in the SAMPL3 blind prediction challenge. The predictions were in poor agreement with experiment, and we conjectured that much of the error might derive from the force field, CHARMm with Vcharge charges. Repeating the calculations with other generalized force-fields led to no significant improvement, and we observed that the predicted affinities were highly sensitive to the choice of force-field. We therefore embarked on a systematic evaluation of a set of generalized force fields, based upon comparisons with PM6-DH2, a fast yet accurate semi-empirical quantum mechanics method. In particular, we compared gas-phase interaction energies and entropies for the host-guest complexes themselves, as well as for smaller chemical fragments derived from the same molecules. The mean deviations of the force field interaction energies from the quantum results were greater than 3 kcal/mol and 9 kcal/mol, for the fragments and host-guest systems respectively. We further evaluated the accuracy of force-fields for computing the vibrational entropies and found the mean errors to be greater than 4 kcal/mol. Given these errors in energy and entropy, it is not surprising in retrospect that the predicted binding affinities deviated from the experiment by several kcal/mol. These results emphasize the need for improvements in generalized force-fields and also highlight the importance of systematic evaluation of force-field parameters prior to evaluating different free-energy methods. PMID:22274835

  11. Molecular shape and binding force of Mycoplasma mobile's leg protein Gli349 revealed by an AFM study

    SciTech Connect

    Lesoil, Charles; Nonaka, Takahiro; Sekiguchi, Hiroshi; Osada, Toshiya; Miyata, Makoto; Afrin, Rehana; Ikai, Atsushi

    2010-01-15

    Recent studies of the gliding bacteria Mycoplasma mobile have identified a family of proteins called the Gli family which was considered to be involved in this novel and yet fairly unknown motility system. The 349 kDa protein called Gli349 was successfully isolated and purified from the bacteria, and electron microscopy imaging and antibody experiments led to the hypothesis that it acts as the 'leg' of M. mobile, responsible for attachment to the substrate as well as for gliding motility. However, more precise evidence of the molecular shape and function of this protein was required to asses this theory any further. In this study, an atomic force microscope (AFM) was used both as an imaging and a force measurement device to provide new information about Gli349 and its role in gliding motility. AFM images of the protein were obtained revealing a complex structure with both rigid and flexible parts, consistent with previous electron micrographs of the protein. Single-molecular force spectroscopy experiments were also performed, revealing that Gli349 is able to specifically bind to sialyllactose molecules and withstand unbinding forces around 70 pN. These findings strongly support the idea that Gli349 is the 'leg' protein of M. mobile, responsible for binding and also most probably force generation during gliding motility.

  12. "Could charm (& τ) transitions be the `poor princess' providing a deeper understanding of fundamental dynamics ?" or: "Finding novel forces"

    NASA Astrophysics Data System (ADS)

    Bigi, Ikaros I.

    2015-06-01

    We know that our Universe is composed of only ˜ 4.5% "known" matter; therefore, our understanding is incomplete. This can be seen directly in the case of neutrino oscillations (without even considering potential other universes). Charm quarks have had considerable impact on our understanding of known matter, and quantum chromodynamics (QCD) is the only local quantum field theory to describe strong forces. It is possible to learn novel lessons concerning strong dynamics by measuring rates around the thresholds of [ Q¯ Q] states with Q = b, c. Furthermore, these states provide us with gateways towards new dynamics (ND), where we must transition from "accuracy" to "precision" eras. Finally, we can make connections with τ transitions and, perhaps, with dark matter. Charm dynamics acts as a bridge between the worlds of light- and heavy-flavor hadrons (namely, beauty hadrons), and finding regional asymmetries in many-body final states may prove to be a "game changer". There are several different approaches to achieving these goals: for example, experiments such as the Super Tau-Charm Factory, Super Beauty Factory, and the Super Z 0 Factory act as gatekeepers - and deeper thinking regarding symmetries.

  13. Force.

    ERIC Educational Resources Information Center

    Gamble, Reed

    1989-01-01

    Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)

  14. Nonlinear force dependence on optically bound micro-particle arrays in the evanescent fields of fundamental and higher order microfibre modes.

    PubMed

    Maimaiti, Aili; Holzmann, Daniela; Truong, Viet Giang; Ritsch, Helmut; Nic Chormaic, Síle

    2016-07-25

    Particles trapped in the evanescent field of an ultrathin optical fibre interact over very long distances via multiple scattering of the fibre-guided fields. In ultrathin fibres that support higher order modes, these interactions are stronger and exhibit qualitatively new behaviour due to the coupling of different fibre modes, which have different propagation wave-vectors, by the particles. Here, we study one dimensional longitudinal optical binding interactions of chains of 3 μm polystyrene spheres under the influence of the evanescent fields of a two-mode microfibre. The observation of long-range interactions, self-ordering and speed variation of particle chains reveals strong optical binding effects between the particles that can be modelled well by a tritter scattering-matrix approach. The optical forces, optical binding interactions and the velocity of bounded particle chains are calculated using this method. Results show good agreement with finite element numerical simulations. Experimental data and theoretical analysis show that higher order modes in a microfibre offer a promising method to not only obtain stable, multiple particle trapping or faster particle propulsion speeds, but that they also allow for better control over each individual trapped object in particle ensembles near the microfibre surface.

  15. Nonlinear force dependence on optically bound micro-particle arrays in the evanescent fields of fundamental and higher order microfibre modes

    PubMed Central

    Maimaiti, Aili; Holzmann, Daniela; Truong, Viet Giang; Ritsch, Helmut; Nic Chormaic, Síle

    2016-01-01

    Particles trapped in the evanescent field of an ultrathin optical fibre interact over very long distances via multiple scattering of the fibre-guided fields. In ultrathin fibres that support higher order modes, these interactions are stronger and exhibit qualitatively new behaviour due to the coupling of different fibre modes, which have different propagation wave-vectors, by the particles. Here, we study one dimensional longitudinal optical binding interactions of chains of 3 μm polystyrene spheres under the influence of the evanescent fields of a two-mode microfibre. The observation of long-range interactions, self-ordering and speed variation of particle chains reveals strong optical binding effects between the particles that can be modelled well by a tritter scattering-matrix approach. The optical forces, optical binding interactions and the velocity of bounded particle chains are calculated using this method. Results show good agreement with finite element numerical simulations. Experimental data and theoretical analysis show that higher order modes in a microfibre offer a promising method to not only obtain stable, multiple particle trapping or faster particle propulsion speeds, but that they also allow for better control over each individual trapped object in particle ensembles near the microfibre surface. PMID:27451935

  16. Binding affinity and adhesion force of organophosphate hydrolase enzyme with soil particles related to the isoelectric point of the enzyme.

    PubMed

    Islam, Shah Md Asraful; Yeasmin, Shabina; Islam, Md Saiful; Islam, Md Shariful

    2017-03-16

    The binding affinity of organophosphate hydrolase enzyme (OphB) with soil particles in relation to the isoelectric point (pI) was studied. Immobilization of OphB with soil particles was observed by confocal microscopy, Fourier transform infrared spectroscopy (FT-IR), and Atomic force microscopy (AFM). The calculated pI of OphB enzyme was increased from 8.69 to 8.89, 9.04 and 9.16 by the single, double and triple mutant of OphB enzyme, respectively through the replacement of negatively charged aspartate with positively charged histidine. Practically, the binding affinity was increased to 5.30%, 11.50%, and 16.80% for single, double and triple mutants, respectively. In contrast, enzyme activity of OphB did not change by the mutation of the enzyme. On the other hand, adhesion forces were gradually increased for wild type OphB enzyme (90 pN) to 96, 100 and 104 pN for single, double and triple mutants of OphB enzyme, respectively. There was an increasing trend of binding affinity and adhesion force by the increase of isoelectric point (pI) of OphB enzyme.

  17. Computational model for nanocarrier binding to endothelium validated using in vivo, in vitro, and atomic force microscopy experiments.

    PubMed

    Liu, Jin; Weller, Gregory E R; Zern, Blaine; Ayyaswamy, Portonovo S; Eckmann, David M; Muzykantov, Vladimir R; Radhakrishnan, Ravi

    2010-09-21

    A computational methodology based on Metropolis Monte Carlo (MC) and the weighted histogram analysis method (WHAM) has been developed to calculate the absolute binding free energy between functionalized nanocarriers (NC) and endothelial cell (EC) surfaces. The calculated NC binding free energy landscapes yield binding affinities that agree quantitatively when directly compared against analogous measurements of specific antibody-coated NCs (100 nm in diameter) to intracellular adhesion molecule-1 (ICAM-1) expressing EC surface in in vitro cell-culture experiments. The effect of antibody surface coverage (σ(s)) of NC on binding simulations reveals a threshold σ(s) value below which the NC binding affinities reduce drastically and drop lower than that of single anti-ICAM-1 molecule to ICAM-1. The model suggests that the dominant effect of changing σ(s) around the threshold is through a change in multivalent interactions; however, the loss in translational and rotational entropies are also important. Consideration of shear flow and glycocalyx does not alter the computed threshold of antibody surface coverage. The computed trend describing the effect of σ(s) on NC binding agrees remarkably well with experimental results of in vivo targeting of the anti-ICAM-1 coated NCs to pulmonary endothelium in mice. Model results are further validated through close agreement between computed NC rupture-force distribution and measured values in atomic force microscopy (AFM) experiments. The three-way quantitative agreement with AFM, in vitro (cell-culture), and in vivo experiments establishes the mechanical, thermodynamic, and physiological consistency of our model. Hence, our computational protocol represents a quantitative and predictive approach for model-driven design and optimization of functionalized nanocarriers in targeted vascular drug delivery.

  18. Fundamental study on transient bubble (slug) behavior by characterizing transient forces of solid particles in fluidized beds. Topical report, January 1991--June 1992

    SciTech Connect

    Kono, H.

    1992-10-01

    The objective of this work is to recognize and interpret the signals of transient motion of bubbles (slugs) in fluidized beds (METC/DOE) by measuring and utilizing the signals of transient gas phase pressure fluctuation, and also by taking the video pictures of transient motions of the bubbles and emulsion phase in fluidized beds. The two signals were measured simultaneously in a three dimensional fluidized bed. Correlation study on the voidage signal and pressure fluctuation was carried out. A domain concept was introduced and new bubble classification was suggested. A video recording approach was also developed to record the transient bubble motion in a two dimensional fluidized bed with a special consideration. This new approach enhances the understanding of bubble image and the physical meaning of transient particle forces. The fundamental mechanism of bubble flow was experimentally investigated and interesting new findings of the transient bubble flow were obtained.

  19. Motion as manipulation: implementation of force-motion analogies by event-file binding and action planning.

    PubMed

    Fields, Chris

    2012-08-01

    Tool-improvisation analogies are structure-mapping inferences implemented, in many species, by event-file binding and pre-motor action planning. These processes act on multi-modal representations of currently perceived situations and eventuate in motor acts that can be directly evaluated for success or failure; they employ implicit representations of force-motion relations encoded by the pre-motor system and do not depend on explicit, language-like representations of relational concepts. A detailed reconstruction of the analogical reasoning steps involved in Rutherford's and Bohr's development of the first quantized-orbit model of atomic structure is used to show that human force-motion analogies can in general be implemented by these mechanisms. This event-file manipulation model of the implementation of force-motion analogies is distinguished from the standard view that structure-mapping analogies require the manipulation of explicit, language-like representations of relational concepts.

  20. Specific binding of the regulatory protein ExpG to promoter regions of the galactoglucan biosynthesis gene cluster of Sinorhizobium meliloti--a combined molecular biology and force spectroscopy investigation.

    PubMed

    Bartels, Frank Wilco; Baumgarth, Birgit; Anselmetti, Dario; Ros, Robert; Becker, Anke

    2003-08-01

    Specific protein-DNA interaction is fundamental for all aspects of gene transcription. We focus on a regulatory DNA-binding protein in the Gram-negative soil bacterium Sinorhizobium meliloti 2011, which is capable of fixing molecular nitrogen in a symbiotic interaction with alfalfa plants. The ExpG protein plays a central role in regulation of the biosynthesis of the exopolysaccharide galactoglucan, which promotes the establishment of symbiosis. ExpG is a transcriptional activator of exp gene expression. We investigated the molecular mechanism of binding of ExpG to three associated target sequences in the exp gene cluster with standard biochemical methods and single molecule force spectroscopy based on the atomic force microscope (AFM). Binding of ExpG to expA1, expG-expD1, and expE1 promoter fragments in a sequence specific manner was demonstrated, and a 28 bp conserved region was found. AFM force spectroscopy experiments confirmed the specific binding of ExpG to the promoter regions, with unbinding forces ranging from 50 to 165 pN in a logarithmic dependence from the loading rates of 70-79000 pN/s. Two different regimes of loading rate-dependent behaviour were identified. Thermal off-rates in the range of k(off)=(1.2+/-1.0) x 10(-3)s(-1) were derived from the lower loading rate regime for all promoter regions. In the upper loading rate regime, however, these fragments exhibited distinct differences which are attributed to the molecular binding mechanism.

  1. Following aptamer-ricin specific binding by single molecule recognition and force spectroscopy measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The atomic force microscope (AFM) recognition and dynamic force spectroscopy (DFS) experiments provide both morphology and interaction information of the aptamer and protein, which can be used for the future study on the thermodynamics and kinetics properties of ricin-aptamer/antibody interactions. ...

  2. Molecular dynamics study of DNA binding by INT-DBD under a polarized force field.

    PubMed

    Yao, Xue X; Ji, Chang G; Xie, Dai Q; Zhang, John Z H

    2013-05-15

    The DNA binding domain of transposon Tn916 integrase (INT-DBD) binds to DNA target site by positioning the face of a three-stranded antiparallel β-sheet within the major groove. As the negatively charged DNA directly interacts with the positively charged residues (such as Arg and Lys) of INT-DBD, the electrostatic interaction is expected to play an important role in the dynamical stability of the protein-DNA binding complex. In the current work, the combined use of quantum-based polarized protein-specific charge (PPC) for protein and polarized nucleic acid-specific charge (PNC) for DNA were employed in molecular dynamics simulation to study the interaction dynamics between INT-DBD and DNA. Our study shows that the protein-DNA structure is stabilized by polarization and the calculated protein-DNA binding free energy is in good agreement with the experimental data. Furthermore, our study revealed a positive correlation between the measured binding energy difference in alanine mutation and the occupancy of the corresponding residue's hydrogen bond. This correlation relation directly relates the contribution of a specific residue to protein-DNA binding energy to the strength of the hydrogen bond formed between the specific residue and DNA.

  3. Cu(2+) affects amyloid-β (1-42) aggregation by increasing peptide-peptide binding forces.

    PubMed

    Hane, Francis; Tran, Gary; Attwood, Simon J; Leonenko, Zoya

    2013-01-01

    The link between metals, Alzheimer's disease (AD) and its implicated protein, amyloid-β (Aβ), is complex and highly studied. AD is believed to occur as a result of the misfolding and aggregation of Aβ. The dyshomeostasis of metal ions and their propensity to interact with Aβ has also been implicated in AD. In this work, we use single molecule atomic force spectroscopy to measure the rupture force required to dissociate two Aβ (1-42) peptides in the presence of copper ions, Cu(2+). In addition, we use atomic force microscopy to resolve the aggregation of Aβ formed. Previous research has shown that metal ions decrease the lag time associated with Aβ aggregation. We show that with the addition of copper ions the unbinding force increases notably. This suggests that the reduction of lag time associated with Aβ aggregation occurs on a single molecule level as a result of an increase in binding forces during the very initial interactions between two Aβ peptides. We attribute these results to copper ions acting as a bridge between the two peptide molecules, increasing the stability of the peptide-peptide complex.

  4. Evaluation of Selected Classical Force Fields for Alchemical Binding Free Energy Calculations of Protein-Carbohydrate Complexes.

    PubMed

    Mishra, Sushil K; Calabró, Gaetano; Loeffler, Hannes H; Michel, Julien; Koča, Jaroslav

    2015-07-14

    Protein-carbohydrate recognition is crucial in many vital biological processes including host-pathogen recognition, cell-signaling, and catalysis. Accordingly, computational prediction of protein-carbohydrate binding free energies is of enormous interest for drug design. However, the accuracy of current force fields (FFs) for predicting binding free energies of protein-carbohydrate complexes is not well understood owing to technical challenges such as the highly polar nature of the complexes, anomerization, and conformational flexibility of carbohydrates. The present study evaluated the performance of alchemical predictions of binding free energies with the GAFF1.7/AM1-BCC and GLYCAM06j force fields for modeling protein-carbohydrate complexes. Mean unsigned errors of 1.1 ± 0.06 (GLYCAM06j) and 2.6 ± 0.08 (GAFF1.7/AM1-BCC) kcal·mol(-1) are achieved for a large data set of monosaccharide ligands for Ralstonia solanacearum lectin (RSL). The level of accuracy provided by GLYCAM06j is sufficient to discriminate potent, moderate, and weak binders, a goal that has been difficult to achieve through other scoring approaches. Accordingly, the protocols presented here could find useful applications in carbohydrate-based drug and vaccine developments.

  5. Structure, mechanics, and binding mode heterogeneity of LEDGF/p75-DNA nucleoprotein complexes revealed by scanning force microscopy

    NASA Astrophysics Data System (ADS)

    Vanderlinden, Willem; Lipfert, Jan; Demeulemeester, Jonas; Debyser, Zeger; de Feyter, Steven

    2014-04-01

    LEDGF/p75 is a transcriptional coactivator implicated in the pathogenesis of AIDS and leukemia. In these contexts, LEDGF/p75 acts as a cofactor by tethering protein cargo to transcriptionally active regions in the human genome. Our study - based on scanning force microscopy (SFM) imaging - is the first to provide structural information on the interaction of LEDGF/p75 with DNA. Two novel approaches that allow obtaining insights into the DNA conformation inside nucleoprotein complexes revealed (1) that LEDGF/p75 can bind at least in three different binding modes, (2) how DNA topology and protein dimerization affect these binding modes, and (3) geometrical and mechanical aspects of the nucleoprotein complexes. These structural and mechanical details will help us to better understand the cellular mechanisms of LEDGF/p75 as a transcriptional coactivator and as a cofactor in disease.LEDGF/p75 is a transcriptional coactivator implicated in the pathogenesis of AIDS and leukemia. In these contexts, LEDGF/p75 acts as a cofactor by tethering protein cargo to transcriptionally active regions in the human genome. Our study - based on scanning force microscopy (SFM) imaging - is the first to provide structural information on the interaction of LEDGF/p75 with DNA. Two novel approaches that allow obtaining insights into the DNA conformation inside nucleoprotein complexes revealed (1) that LEDGF/p75 can bind at least in three different binding modes, (2) how DNA topology and protein dimerization affect these binding modes, and (3) geometrical and mechanical aspects of the nucleoprotein complexes. These structural and mechanical details will help us to better understand the cellular mechanisms of LEDGF/p75 as a transcriptional coactivator and as a cofactor in disease. Electronic supplementary information (ESI) available: SFM topographs of phage lambda DNA in situ, in the absence and presence of LEDGF/p75; model-independent tests for DNA chain equilibration in 2D; SFM topographs of

  6. Energetic driving force for preferential binding of self-interstitial atoms to Fe grain boundaries over vacancies

    SciTech Connect

    Tschopp, Mark A.; Horstemeyer, Mark; Gao, Fei; Sun, Xin; Khaleel, Mohammad A.

    2011-05-02

    Molecular dynamics simulations of 50 Fe grain boundaries were used to understand their interaction with vacancies and self-interstitial atoms at all atomic positions within 20 °A of the boundary, which is important for designing radiation-resistant polycrystalline materials. Site-to-site variation within the boundary of both vacancy and self-interstitial formation energies is substantial, with the majority of sites having lower formation energies than in the bulk. Comparing the vacancy and self-interstitial atom binding energies for each site shows that there is an energetic driving force for interstitials to preferentially bind to grain boundary sites over vacancies. Furthermore, these results provide a valuable dataset for quantifying uncertainty bounds for various grain boundary types at the nanoscale, which can be propagated to higher scale simulations of microstructure evolution.

  7. Exploring the binding of 4-thiothymidine with human serum albumin by spectroscopy, atomic force microscopy, and molecular modeling methods.

    PubMed

    Zhang, Juling; Gu, Huaimin; Zhang, Xiaohui

    2014-01-30

    The interaction of 4-thiothymidine (S(4)TdR) with human serum albumin (HSA) was studied by equilibrium dialysis under normal physiological conditions. In this work, the mechanism of the interaction between S(4)TdR and human serum albumin (HSA) was exploited by fluorescence, UV, CD circular, and SERS spectroscopic. Fluorescence and UV spectroscopy suggest that HSA intensities are significantly decreased when adding S(4)TdR to HAS, and the quenching mechanism of the fluorescence is static. Also, the ΔG, ΔH, and ΔS values across temperature indicated that hydrophobic interaction was the predominant binding force. The CD circular results show that there is little change in the secondary structure of HSA except the environment of amino acid changes when adding S(4)TdR to HSA. The surface-enhanced Raman scattering (SERS) shows that the interaction between S(4)TdR and HSA can be achieved through different binding sites which are probably located in the II A and III A hydrophobic pockets of HSA which correspond to Sudlow's I and II binding sites. In addition, the molecular modeling displays that S(4)TdR-HSA complex is stabilized by hydrophobic forces, which result from amino acid residues. The atomic force microscopy results revealed that the single HSA molecular dimensions were larger after interaction of 4-thiothymidine. This work would be useful to understand the state of the transportation, distribution, and metabolism of the anticancer drugs in the human body, and it could provide a useful biochemistry parameter for the development of new anti-cancer drugs and research of pharmacology mechanisms.

  8. Unraveling the motion of single-stranded DNA binding proteins on DNA using force and fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Ha, Taekjip

    2012-02-01

    Single-stranded DNA binding (SSB) proteins bind to and control the accessibility of single stranded (ss) DNA generated as a transient intermediate during a variety of cellular processes. For subsequent DNA processing, however, such a tightly wrapped, high-affinity protein--DNA complex still needs to be removed or repositioned quickly for unhindered action of other proteins. Here we show, using single-molecule two- and three-colour fluorescence resonance energy transfer, that SSB can spontaneously migrate along ssDNA. Diffusional migration of SSB helps in the local displacement of SSB by an elongating RecA filament. SSB diffusion also melts short DNA hairpins transiently and stimulates RecA filament elongation on DNA with secondary structure. This observation of diffusional movement of a protein on ssDNA introduces a new model for how an SSB protein can be redistributed, while remaining tightly bound to ssDNA during recombination and repair processes. In addition, using an optomechanical tool combining single-molecule fluorescence and force methods, we probed how proteins with such a large binding site size (˜ 65 nucleotides) can migrate rapidly on DNA and how protein-protein interactions and tension may modulate the motion. We observed force-induced progressive unravelling of ssDNA from the SSB surface between 1 and 6 pN, followed by SSB dissociation at ˜10 pN, and obtained experimental evidence of a reptation mechanism for protein movement along DNA wherein a protein slides via DNA bulge formation and propagation. SSB diffusion persists even when bound with RecO, and at forces under which the fully wrapped state is perturbed, suggesting that even in crowded cellular conditions SSB can act as a sliding platform to recruit and carry its interacting proteins for use in DNA replication, recombination and repair.

  9. Multiple stepwise pattern for potential of mean force in unfolding the thrombin binding aptamer in complex with Sr2+.

    PubMed

    Yang, Changwon; Jang, Soonmin; Pak, Youngshang

    2011-12-14

    Using all-atom molecular dynamics simulation in conjunction with umbrella sampling, we obtained the unfolding free energy and the force extension profiles of the thrombin binding DNA aptamer (15-TBA) in complex with Sr(2+) (Protein Data Bank code: 1RDE). The resulting potential of mean force (PMF) displays a multiple stepwise pattern with distinct plateau regions. The detailed analysis of the simulation result indicated that each plateau was created by the interplay of the metal ion interacting with self-arranging guanine bases and the successive uptakes of water molecules. The current PMF simulation provides a quantitative description of the unfolding process of 15-TBA DNA driven by stretching and gives molecular insight on its detailed changes of base pair interactions in the presence of the metal cation.

  10. Differential roles of regulatory light chain and myosin binding protein-C phosphorylations in the modulation of cardiac force development

    SciTech Connect

    Colson, Brett A.; Locher, Matthew R.; Bekyarova, Tanya; Patel, Jitandrakumar R.; Fitzsimons, Daniel P.; Irving, Thomas C.; Moss, Richard L.

    2010-05-25

    Phosphorylation of myosin regulatory light chain (RLC) by myosin light chain kinase (MLCK) and myosin binding protein-C (cMyBP-C) by protein kinase A (PKA) independently accelerate the kinetics of force development in ventricular myocardium. However, while MLCK treatment has been shown to increase the Ca{sup 2+} sensitivity of force (pCa{sub 50}), PKA treatment has been shown to decrease pCa{sub 50}, presumably due to cardiac troponin I phosphorylation. Further, MLCK treatment increases Ca{sup 2+}-independent force and maximum Ca{sup 2+}-activated force, whereas PKA treatment has no effect on either force. To investigate the structural basis underlying the kinase-specific differential effects on steady-state force, we used synchrotron low-angle X-ray diffraction to compare equatorial intensity ratios (I{sub 1,1}/I{sub 1,0}) to assess the proximity of myosin cross-bridge mass relative to actin and to compare lattice spacings (d{sub 1,0}) to assess the inter-thick filament spacing in skinned myocardium following treatment with either MLCK or PKA. As we showed previously, PKA phosphorylation of cMyBP-C increases I{sub 1,1}/I{sub 1,0} and, as hypothesized, treatment with MLCK also increased I{sub 1,1}/I{sub 1,0}, which can explain the accelerated rates of force development during activation. Importantly, interfilament spacing was reduced by {approx}2 nm ({Delta} 3.5%) with MLCK treatment, but did not change with PKA treatment. Thus, RLC or cMyBP-C phosphorylation increases the proximity of cross-bridges to actin, but only RLC phosphorylation affects lattice spacing, which suggests that RLC and cMyBP-C modulate the kinetics of force development by similar structural mechanisms; however, the effect of RLC phosphorylation to increase the Ca{sup 2+} sensitivity of force is mediated by a distinct mechanism, most probably involving changes in interfilament spacing.

  11. Analysis of adhesive binding forces between laminin-1 and C2C12 muscle cell membranes measured via high resolution force spectroscopy

    NASA Astrophysics Data System (ADS)

    Gluck, George; Gilbert, Richard; Ortiz, Christine

    2002-03-01

    Laminins are a family of glycoproteins that regulate cell differentiation, shape, and motility through interactions with various cell surface receptors. Here, we have directly measured the biomolecular adhesive binding forces between a cantilever / probe tip that was covalently attached with laminin-1 and membrane receptors on C2C12 muscle cells using the technique of high-resolution force spectroscopy (HRFS). On retraction of the probe tip away from the membrane surface, discrete, long-range adhesive unbinding events were always observed. Statistical analysis of the data revealed an initial broad distribution of heterogeneous unbinding events (occurring at separation distances, D=0-2µm from the point of maximum compression) of magnitude 92.23±37.87pN followed by a narrow distribution of homogeneous unbinding events (occurring at D > 2µm) of magnitude 38.16±9.10pN, which is suggestive of an individual biomolecular adhesive interaction. On-going studies include loading rate dependence and effect of dystroglycan mutation.

  12. Force transduction and lipid binding in MscL: A continuum-molecular approach

    DOE PAGES

    Vanegas, Juan M.; Arroyo, Marino; Fotiadis, Dimitrios

    2014-12-01

    The bacterial mechanosensitive channel MscL, a small protein mainly activated by membrane tension, is a central model system to study the transduction of mechanical stimuli into chemical signals. Mutagenic studies suggest that MscL gating strongly depends on both intra-protein and interfacial lipid-protein interactions. However, there is a gap between this detailed chemical information and current mechanical models of MscL gating. Here, we investigate the MscL bilayer-protein interface through molecular dynamics simulations, and take a combined continuum-molecular approach to connect chemistry and mechanics. We quantify the effect of membrane tension on the forces acting on the surface of the channel, andmore » identify interactions that may be critical in the force transduction between the membrane and MscL. We find that the local stress distribution on the protein surface is largely asymmetric, particularly under tension, with the cytoplasmic side showing significantly larger and more localized forces, which pull the protein radially outward. The molecular interactions that mediate this behavior arise from hydrogen bonds between the electronegative oxygens in the lipid headgroup and a cluster of positively charged lysine residues on the amphipathic S1 domain and the C-terminal end of the second trans-membrane helix. We take advantage of this strong interaction (estimated to be 10–13 kT per lipid) to actuate the channel (by applying forces on protein-bound lipids) and explore its sensitivity to the pulling magnitude and direction. We conclude by highlighting the simple motif that confers MscL with strong anchoring to the bilayer, and its presence in various integral membrane proteins including the human mechanosensitive channel K2P1 and bovine rhodopsin.« less

  13. Force Transduction and Lipid Binding in MscL: A Continuum-Molecular Approach

    PubMed Central

    Vanegas, Juan M.; Arroyo, Marino

    2014-01-01

    The bacterial mechanosensitive channel MscL, a small protein mainly activated by membrane tension, is a central model system to study the transduction of mechanical stimuli into chemical signals. Mutagenic studies suggest that MscL gating strongly depends on both intra-protein and interfacial lipid-protein interactions. However, there is a gap between this detailed chemical information and current mechanical models of MscL gating. Here, we investigate the MscL bilayer-protein interface through molecular dynamics simulations, and take a combined continuum-molecular approach to connect chemistry and mechanics. We quantify the effect of membrane tension on the forces acting on the surface of the channel, and identify interactions that may be critical in the force transduction between the membrane and MscL. We find that the local stress distribution on the protein surface is largely asymmetric, particularly under tension, with the cytoplasmic side showing significantly larger and more localized forces, which pull the protein radially outward. The molecular interactions that mediate this behavior arise from hydrogen bonds between the electronegative oxygens in the lipid headgroup and a cluster of positively charged lysine residues on the amphipathic S1 domain and the C-terminal end of the second trans-membrane helix. We take advantage of this strong interaction (estimated to be 10–13 kT per lipid) to actuate the channel (by applying forces on protein-bound lipids) and explore its sensitivity to the pulling magnitude and direction. We conclude by highlighting the simple motif that confers MscL with strong anchoring to the bilayer, and its presence in various integral membrane proteins including the human mechanosensitive channel K2P1 and bovine rhodopsin. PMID:25437007

  14. Insulin binding and glucose uptake of adipocytes in rats adapted to hypergravitational force

    NASA Technical Reports Server (NTRS)

    Kobayashi, M.; Mondon, C. E.; Oyama, J.

    1980-01-01

    Rats were exposed to 4.15 g for 1 yr and weight and age matched, and lean noncentrifuged rats were used as control groups. Rats exposed to chronic hypergravity (hypergravic rats) were found to show lower ambient insulin levels, greater food intake with smaller body weight gain, and decreased size of isolated adipocytes. The ability of adipocytes from the hypergravic rats to bind insulin was increased. With Scatchard analysis, both number and affinity of receptors were increased. In contrast to the increased binding, glucose transport was found to be decreased in adipocytes from these animals. However, when the data were expressed as a percentage of maximal effect, the half maximal insulin effect for both the hypergravic and lean control groups was produced at an insulin concentration of 0.23 + or - 0.02 ng/ml, which was lower than the insulin concentration of 0.31 + or - 0.02 ng/ml for the weight-matched control group (P less than 0.05). This increased insulin sensitivity in the hypergravic group was accounted for by an increased number of receptors.

  15. Tether fundamentals

    NASA Technical Reports Server (NTRS)

    Carroll, J. A.

    1986-01-01

    Some fundamental aspects of tethers are presented and briefly discussed. The effects of gravity gradients, dumbbell libration in circular orbits, tether control strategies and impact hazards for tethers are among those fundamentals. Also considered are aerodynamic drag, constraints in momentum transfer applications and constraints with permanently deployed tethers. The theoretical feasibility of these concepts are reviewed.

  16. Regulation of protein binding toward a ligand on chromatographic matrixes by masking and forced-releasing effects using thermoresponsive polymer.

    PubMed

    Yoshizako, Kimihiro; Akiyama, Yoshikatsu; Yamanaka, Hidenori; Shinohara, Yasuro; Hasegawa, Yukio; Carredano, Enrique; Kikuchi, Akihiko; Okano, Teruo

    2002-08-15

    A novel concept of affinity regulation based on masking and forced-releasing effects using a thermoresponsive polymer was elucidated. Affinity chromatographic matrixes were prepared using either poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) or poly(glycidyl methacrylate-co-triethyleneglycol dimethacrylate) beads immobilized with ligand molecule, Cibacron Blue F3G-A (CB), together with poly(N-isopropylacrylamide) (PIPAAm), a polymer with a cloud point of 32 degrees C. Two different lengths of spacer molecules were used for the immobilization of CB while maintaining the PIPAAm size constant. Chromatographic analyses using bovine serum albumin as a model protein showed a clear correlation between spacer length and binding capacity at temperatures lower than the lower critical solution temperature (LCST) of PIPAAm. The binding capacity under the LCST was significantly reduced only when the calculated spacer length was shorter than the mean size of the extended PIPAAm. Furthermore, the adsorbed protein could be desorbed (released) from the matrix surface by lowering the temperature to below the LCST while maintaining other factors such as pH and ion strength. Selective recovery of human albumin from human sera was demonstrated using this newly developed thermoresponsive affinity column.

  17. Vascular binding of a pathogen under shear force through mechanistically distinct sequential interactions with host macromolecules

    PubMed Central

    Moriarty, Tara J.; Shi, Meiqing; Lin, Yi-Pin; Ebady, Rhodaba; Zhou, Hong; Odisho, Tanya; Hardy, Pierre-Olivier; Salman-Dilgimen, Aydan; Wu, Jing; Weening, Eric H.; Skare, Jon T.; Kubes, Paul; Leong, John; Chaconas, George

    2012-01-01

    SUMMARY Systemic dissemination of microbial pathogens permits microbes to spread from the initial site of infection to secondary target tissues and is responsible for most mortality due to bacterial infections. Dissemination is a critical stage of disease progression by the Lyme spirochete, Borrelia burgdorferi. However, many mechanistic features of the process are not yet understood. A key step is adhesion of circulating microbes to vascular surfaces in the face of the shear forces present in flowing blood. Using real-time microscopic imaging of the Lyme spirochete in living mice we previously identified the first bacterial protein (B. burgdorferi BBK32) shown to mediate vascular adhesion in vivo. Vascular adhesion is also dependent on host fibronectin (Fn) and glycosaminoglycans (GAGs). In the present study, we investigated the mechanisms of BBK32-dependent vascular adhesion in vivo. We determined that BBK32-Fn interactions (tethering) function as a molecular braking mechanism that permits the formation of more stable BBK32-GAG interactions (dragging) between circulating bacteria and vascular surfaces. Since BBK32-like proteins are expressed in a variety of pathogens we believe that the vascular adhesion mechanisms we have deciphered here may be critical for understanding the dissemination mechanisms of other bacterial pathogens. PMID:23095033

  18. Effective binding force calculation in a dimeric protein by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Sergi, Alessandro; Ciccotti, Giovanni; Falconi, Mattia; Desideri, Alessandro; Ferrario, Mauro

    2002-04-01

    A good example of macromolecular recognition is found in the interaction of the two monomers of the dimeric superoxide dismutase protein found in Photobacterium leiognathi. We have produced, by molecular dynamics simulation techniques, a specific path for the rupture of the dimer and calculated the effective force involved in the process by extending a well established free energy calculation scheme, the molecular dynamics blue moon approach to rare events. Within this picture we have generalized the approach to a vectorial reaction coordinate and performed a number of different simulations in function of the monomer-momomer separation, at fixed relative orientation. We find a deep minimum and we compute the height of the free energy barrier to break the dimer. As for the system characterization we have found that, when the separation distance increases, the protein structure is stable and the monomer-monomer interface is uniformly hydrated. Moreover, identifying the crucial contacts for the stabilization of the dimer, we have found the sequence of the different microscopic events in the monomer-monomer recognition and we have developed a view of the process which requires a merging of standard explanations, in agreement with the recent picture of recognition as a dynamical process mixing the various mechanisms previously considered [Kimura et al., Biophys. J. 80 635 (2001)].

  19. Dialysis purification of integrase-DNA complexes provides high-resolution atomic force microscopy images: dimeric recombinant HIV-1 integrase binding and specific looping on DNA.

    PubMed

    Tsuruyama, Tatsuaki; Nakai, Tonau; Ohmori, Rei; Ozeki, Munetaka; Tamaki, Keiji; Yoshikawa, Kenichi

    2013-01-01

    It remains difficult to obtain high-resolution atomic force microscopy images of HIV-1 integrase bound to DNA in a dimeric or tetrameric fashion. We therefore constructed specific target DNAs to assess HIV-1 integrase binding and purified the complex by dialysis prior to analysis. Our resulting atomic force microscopy analyses indicated precise size of binding human immunodeficiency virus type 1 (HIV-1) recombinant integrase in a tetrameric manner, inducing formation of a loop-like or figure-eight-like secondary structure in the target DNA. Our findings regarding the target DNA secondary structure provide new insights into the intermediate states of retroviral integration.

  20. The microtubule-binding and coiled-coil domains of Kid are required to turn off the polar ejection force at anaphase.

    PubMed

    Soeda, Shou; Yamada-Nomoto, Kaori; Ohsugi, Miho

    2016-10-01

    Mitotic chromosomes move dynamically along the spindle microtubules using the forces generated by motor proteins such as chromokinesin Kid (also known as KIF22). Kid generates a polar ejection force and contributes to alignment of the chromosome arms during prometaphase and metaphase, whereas during anaphase, Kid contributes to chromosome compaction. How Kid is regulated and how this regulation is important for chromosome dynamics remains unclear. Here, we address these questions by expressing mutant forms of Kid in Kid-deficient cells. We demonstrate that Cdk1-mediated phosphorylation of Thr463 is required to generate the polar ejection force on Kid-binding chromosomes, whereas dephosphorylation of Thr463 prevents generation of the ejection force on such chromosomes. In addition to activation of the second microtubule-binding domain through dephosphorylation of Thr463, the coiled-coil domain is essential in suspending generation of the polar ejection force, preventing separated chromosomes from becoming recongressed during anaphase. We propose that phosphorylation of Thr463 switches the mitotic chromosome movement from an anti-poleward direction to a poleward direction by converting the Kid functional mode from polar-ejection-force-ON to -OFF during the metaphase-anaphase transition, and that both the second microtubule-binding domain and the coiled-coil domain are involved in this switching process.

  1. Binding Structures of tri-N-acetyl-β-glucosamine in Hen Egg White Lysozyme using Molecular Dynamics with a Polarizable Force Field

    PubMed Central

    Zhong, Yang; Patel, Sandeep

    2014-01-01

    Lysozyme is a well-studied enzyme that hydrolyzes the β-(1,4)-glycosidic linkage of N-acetyl-β-glucosamine (NAG)n oligomers. The active site of hen egg-white lysozyme (HEWL) is believed to consist of six subsites, A-F that can accommodate six sugar residues. We present studies exploring the use of polarizable force fields in conjunction with all-atom molecular dynamics simulations to analyze binding structures of complexes of lysozyme and NAG trisaccharide, (NAG)3. Molecular dynamics trajectories are applied to analyze structures and conformation of the complex as well as protein-ligand interactions, including the hydrogen-bonding network in the binding pocket. Two binding modes (ABC and BCD) of (NAG)3 are investigated independently based on a fixed-charge model and a polarizable model. We also apply MM-GBSA methods based on molecular dynamics using both non-polarizable and polarizable force fields in order to compute binding free energies. We also study the correlation between RMSD and binding free energies of the wildtype and W62Y mutant; we find that for this prototypical system, approaches using the MD trajectories coupled with implicit solvent models are equivalent for polarizable and fixed-charge models. PMID:23109228

  2. Marketing fundamentals.

    PubMed

    Redmond, W H

    2001-01-01

    This chapter outlines current marketing practice from a managerial perspective. The role of marketing within an organization is discussed in relation to efficiency and adaptation to changing environments. Fundamental terms and concepts are presented in an applied context. The implementation of marketing plans is organized around the four P's of marketing: product (or service), promotion (including advertising), place of delivery, and pricing. These are the tools with which marketers seek to better serve their clients and form the basis for competing with other organizations. Basic concepts of strategic relationship management are outlined. Lastly, alternate viewpoints on the role of advertising in healthcare markets are examined.

  3. Neutrons and Fundamental Symmetries

    SciTech Connect

    Plaster, Bradley

    2016-01-11

    The research supported by this project addressed fundamental open physics questions via experiments with subatomic particles. In particular, neutrons constitute an especially ideal “laboratory” for fundamental physics tests, as their sensitivities to the four known forces of nature permit a broad range of tests of the so-called “Standard Model”, our current best physics model for the interactions of subatomic particles. Although the Standard Model has been a triumphant success for physics, it does not provide satisfactory answers to some of the most fundamental open questions in physics, such as: are there additional forces of nature beyond the gravitational, electromagnetic, weak nuclear, and strong nuclear forces?, or why does our universe consist of more matter than anti-matter? This project also contributed significantly to the training of the next generation of scientists, of considerable value to the public. Young scientists, ranging from undergraduate students to graduate students to post-doctoral researchers, made significant contributions to the work carried out under this project.

  4. A Fundamental Relationship Between Hydrophobic Properties and Biological Activity for the Duocarmycin Class of DNA Alkylating Antitumor Drugs: Hydrophobic Binding-Driven-Bonding

    PubMed Central

    Wolfe, Amanda L.; Duncan, Katharine K.; Lajiness, James P.; Zhu, Kaicheng; Duerfeldt, Adam S.; Boger, Dale L.

    2013-01-01

    Two systematic series of increasingly hydrophilic derivatives of duocarmycin SA are described that feature the incorporation of ethylene glycol units (n = 1–5) into the methoxy substituents of the trimethoxyindole subunit. These derivatives exhibit progressively increasing water solubility, along with progressive decreases in cell growth inhibitory activity and DNA alkylation efficiency with the incremental ethylene glycol unit incorporations. A linear relationship between cLogP and –logIC50 for cell growth inhibition and –logAE (AE = cell free DNA alkylation efficiency) is observed where cLogP values span the productive range of 2.5–0.49 and –logIC50 values span the range of 11.2–6.4, representing IC50 values covering a 105 range (0.008 to 370 nM). The results quantify a fundamental role the compound hydrophobic character plays in the expression of the biological activity of members in this class, driving the intrinsically reversible DNA alkylation reaction, and define the stunning magnitude of its effect. PMID:23944748

  5. Accurate determination of pyridine-poly(amidoamine) dendrimer absolute binding constants with the OPLS-AA force field and direct integration of radial distribution functions.

    PubMed

    Peng, Yong; Kaminski, George A

    2005-08-11

    OPLS-AA force field and direct integration of intermolecular radial distribution functions (RDF) were employed to calculate absolute binding constants of pyridine molecules to amino group (NH2) and amide group hydrogen atoms in and first generation poly(amidoamine) dendrimers in chloroform. The average errors in the absolute and relative association constants, as predicted with the calculations, are 14.1% and 10.8%, respectively, which translate into ca. 0.08 and 0.06 kcal/mol errors in the absolute and relative binding free energies. We believe that this level of accuracy proves the applicability of the OPLS-AA, force field, in combination with the direct RDF integration, to reproducing and predicting absolute intermolecular association constants of low magnitudes (ca. 0.2-2.0 range).

  6. Accurate Determination of Pyridine -- Poly (Amidoamine) Dendrimer Absolute Binding Constants with the OPLS-AA Force Field and Direct Integration of Radial Distribution Functions

    NASA Astrophysics Data System (ADS)

    Peng, Yong; Kaminski, George

    2006-03-01

    OPLS-AA force field and direct integration of intermolecular radial distribution functions (RDF) were employed to calculate absolute binding constants of pyridine molecules to NH2 and amide group hydrogen atoms in 0th and 1st generation poly (amidoamine) dendrimers in chloroform. The average errors in the absolute and relative association constants, as predicted with the calculations, are 14.1% and 10.8%, respectively, which translate into ca. 0.08 kcal/mol and 0.06 kcal/mol errors in the absolute and relative binding free energies. We believe that this level of accuracy proves the applicability of the OPLS-AA, force field, in combination with the direct RDF integration, to reproducing and predicting absolute intermolecular association constants of low magnitudes (ca. 0.2 -- 2.0 range).

  7. Role of ICAM-1 polymorphisms (G241R, K469E) in mediating its single-molecule binding ability: Atomic force microscopy measurements on living cells

    SciTech Connect

    Bai, Rui; Yi, Shaoqiong; Zhang, Xuejie; Liu, Huiliang; Fang, Xiaohong

    2014-06-13

    Highlights: • We evaluated both single molecule binding ability and expression level of 4 ICAM-1 mutations. • AFM was used to measure single-molecule binding ability on living cells. • The SNP of ICAM-1 may induce changes in expressions rather than single-molecule binding ability. - Abstract: Atherosclerosis (As) is characterized by chronic inflammation and is a major cause of human mortality. ICAM-1-mediated adhesion of leukocytes in vessel walls plays an important role in the pathogenesis of atherosclerosis. Two single nucleotide polymorphisms (SNPs) of human intercellular adhesion molecule-1 (ICAM-1), G241R and K469E, are associated with a number of inflammatory diseases. SNP induced changes in ICAM-1 function rely not only on the expression level but also on the single-molecule binding ability which may be affected by single molecule conformation variations such as protein splicing and folding. Previous studies have shown associations between G241R/K469E polymorphisms and ICAM-1 gene expression. Nevertheless, few studies have been done that focus on the single-molecule forces of the above SNPs and their ligands. In the current study, we evaluated both single molecule binding ability and expression level of 4 ICAM-1 mutations – GK (G241/K469), GE (G241/E469), RK (R241/K469) and RE (R241/E469). No difference in adhesion ability was observed via cell adhesion assay or atomic force microscopy (AFM) measurement when comparing the GK, GE, RK, or RE genotypes of ICAM-1 to each other. On the other hand, flow cytometry suggested that there was significantly higher expression of GE genotype of ICAM-1 on transfected CHO cells. Thus, we concluded that genetic susceptibility to diseases related to ICAM-1 polymorphisms, G241R or K469E, might be due to the different expressions of ICAM-1 variants rather than to the single-molecule binding ability of ICAM-1.

  8. Fundamentals of negative refractive index optical trapping: forces and radiation pressures exerted by focused Gaussian beams using the generalized Lorenz-Mie theory.

    PubMed

    Ambrosio, Leonardo A; Hernández-Figueroa, Hugo E

    2010-11-04

    Based on the generalized Lorenz-Mie theory (GLMT), this paper reveals, for the first time in the literature, the principal characteristics of the optical forces and radiation pressure cross-sections exerted on homogeneous, linear, isotropic and spherical hypothetical negative refractive index (NRI) particles under the influence of focused Gaussian beams in the Mie regime. Starting with ray optics considerations, the analysis is then extended through calculating the Mie coefficients and the beam-shape coefficients for incident focused Gaussian beams. Results reveal new and interesting trapping properties which are not observed for commonly positive refractive index particles and, in this way, new potential applications in biomedical optics can be devised.

  9. Demonstration of specific binding of heparin to Plasmodium falciparum-infected vs. non-infected red blood cells by single-molecule force spectroscopy

    NASA Astrophysics Data System (ADS)

    Valle-Delgado, Juan José; Urbán, Patricia; Fernàndez-Busquets, Xavier

    2013-04-01

    Glycosaminoglycans (GAGs) play an important role in the sequestration of Plasmodium falciparum-infected red blood cells (pRBCs) in the microvascular endothelium of different tissues, as well as in the formation of small clusters (rosettes) between infected and non-infected red blood cells (RBCs). Both sequestration and rosetting have been recognized as characteristic events in severe malaria. Here we have used heparin and pRBCs infected by the 3D7 strain of P. falciparum as a model to study GAG-pRBC interactions. Fluorescence microscopy and fluorescence-assisted cell sorting assays have shown that exogenously added heparin has binding specificity for pRBCs (preferentially for those infected with late forms of the parasite) vs. RBCs. Heparin-pRBC adhesion has been probed by single-molecule force spectroscopy, obtaining an average binding force ranging between 28 and 46 pN depending on the loading rate. No significant binding of heparin to non-infected RBCs has been observed in control experiments. This work represents the first approach to quantitatively evaluate GAG-pRBC molecular interactions at the individual molecule level.Glycosaminoglycans (GAGs) play an important role in the sequestration of Plasmodium falciparum-infected red blood cells (pRBCs) in the microvascular endothelium of different tissues, as well as in the formation of small clusters (rosettes) between infected and non-infected red blood cells (RBCs). Both sequestration and rosetting have been recognized as characteristic events in severe malaria. Here we have used heparin and pRBCs infected by the 3D7 strain of P. falciparum as a model to study GAG-pRBC interactions. Fluorescence microscopy and fluorescence-assisted cell sorting assays have shown that exogenously added heparin has binding specificity for pRBCs (preferentially for those infected with late forms of the parasite) vs. RBCs. Heparin-pRBC adhesion has been probed by single-molecule force spectroscopy, obtaining an average binding force

  10. Large-scale symmetry-adapted perturbation theory computations via density fitting and Laplace transformation techniques: Investigating the fundamental forces of DNA-intercalator interactions

    NASA Astrophysics Data System (ADS)

    Hohenstein, Edward G.; Parrish, Robert M.; Sherrill, C. David; Turney, Justin M.; Schaefer, Henry F.

    2011-11-01

    Symmetry-adapted perturbation theory (SAPT) provides a means of probing the fundamental nature of intermolecular interactions. Low-orders of SAPT (here, SAPT0) are especially attractive since they provide qualitative (sometimes quantitative) results while remaining tractable for large systems. The application of density fitting and Laplace transformation techniques to SAPT0 can significantly reduce the expense associated with these computations and make even larger systems accessible. We present new factorizations of the SAPT0 equations with density-fitted two-electron integrals and the first application of Laplace transformations of energy denominators to SAPT. The improved scalability of the DF-SAPT0 implementation allows it to be applied to systems with more than 200 atoms and 2800 basis functions. The Laplace-transformed energy denominators are compared to analogous partial Cholesky decompositions of the energy denominator tensor. Application of our new DF-SAPT0 program to the intercalation of DNA by proflavine has allowed us to determine the nature of the proflavine-DNA interaction. Overall, the proflavine-DNA interaction contains important contributions from both electrostatics and dispersion. The energetics of the intercalator interaction are are dominated by the stacking interactions (two-thirds of the total), but contain important contributions from the intercalator-backbone interactions. It is hypothesized that the geometry of the complex will be determined by the interactions of the intercalator with the backbone, because by shifting toward one side of the backbone, the intercalator can form two long hydrogen-bonding type interactions. The long-range interactions between the intercalator and the next-nearest base pairs appear to be negligible, justifying the use of truncated DNA models in computational studies of intercalation interaction energies.

  11. Large-scale symmetry-adapted perturbation theory computations via density fitting and Laplace transformation techniques: investigating the fundamental forces of DNA-intercalator interactions.

    PubMed

    Hohenstein, Edward G; Parrish, Robert M; Sherrill, C David; Turney, Justin M; Schaefer, Henry F

    2011-11-07

    Symmetry-adapted perturbation theory (SAPT) provides a means of probing the fundamental nature of intermolecular interactions. Low-orders of SAPT (here, SAPT0) are especially attractive since they provide qualitative (sometimes quantitative) results while remaining tractable for large systems. The application of density fitting and Laplace transformation techniques to SAPT0 can significantly reduce the expense associated with these computations and make even larger systems accessible. We present new factorizations of the SAPT0 equations with density-fitted two-electron integrals and the first application of Laplace transformations of energy denominators to SAPT. The improved scalability of the DF-SAPT0 implementation allows it to be applied to systems with more than 200 atoms and 2800 basis functions. The Laplace-transformed energy denominators are compared to analogous partial Cholesky decompositions of the energy denominator tensor. Application of our new DF-SAPT0 program to the intercalation of DNA by proflavine has allowed us to determine the nature of the proflavine-DNA interaction. Overall, the proflavine-DNA interaction contains important contributions from both electrostatics and dispersion. The energetics of the intercalator interaction are are dominated by the stacking interactions (two-thirds of the total), but contain important contributions from the intercalator-backbone interactions. It is hypothesized that the geometry of the complex will be determined by the interactions of the intercalator with the backbone, because by shifting toward one side of the backbone, the intercalator can form two long hydrogen-bonding type interactions. The long-range interactions between the intercalator and the next-nearest base pairs appear to be negligible, justifying the use of truncated DNA models in computational studies of intercalation interaction energies.

  12. Cardiac MyBP-C regulates the rate and force of contraction in mammalian myocardium Cardiac Myosin Binding Protein C

    PubMed Central

    Moss, Richard L.; Fitzsimons, Daniel P.; Ralphe, J. Carter

    2014-01-01

    Cardiac myosin binding protein-C (cMyBP-C) is a thick filament-associated protein that appears to contribute to the regulation of cardiac contraction through interactions with either myosin or actin or both. Several studies over the past several years have suggested that the interactions of cMyBP-C with its binding partners vary with its phosphorylation state, binding predominantly to myosin when dephosphorylated and to actin when it is phosphorylated by PKA or other kinases. Here, we summarize evidence suggesting that phosphorylation of cMyBP-C is a key regulator of the kinetics and amplitude of cardiac contraction during β-adrenergic stimulation and increased stimulus frequency. We propose a model for these effects via a phosphorylation-dependent regulation of the kinetics and extent of cooperative recruitment of cross-bridges to the thin filament – phosphorylation of cMyBP-C accelerates cross-bridge binding to actin, thereby accelerating recruitment and increasing the amplitude of the cardiac twitch. In contrast, enhanced lusitropy as a result of phosphorylation appears to be due to a direct effect of phosphorylation to accelerate cross-bridge detachment rate. Depression or elimination of one or both of these processes in a disease such as end-stage heart failure appears to contribute to the systolic and diastolic dysfunction that characterizes the disease. PMID:25552695

  13. Hybrid Steered Molecular Dynamics Approach to Computing Absolute Binding Free Energy of Ligand-Protein Complexes: A Brute Force Approach That Is Fast and Accurate.

    PubMed

    Chen, Liao Y

    2015-04-14

    Computing the free energy of binding a ligand to a protein is a difficult task of essential importance for which purpose various theoretical/computational approaches have been pursued. In this paper, we develop a hybrid steered molecular dynamics (hSMD) method capable of resolving one ligand–protein complex within a few wall-clock days with high enough accuracy to compare with the experimental data. This hSMD approach is based on the relationship between the binding affinity and the potential of mean force (PMF) in the established literature. It involves simultaneously steering n (n = 1, 2, 3, ...) centers of mass of n selected segments of the ligand using n springs of infinite stiffness. Steering the ligand from a single initial state chosen from the bound state ensemble to the corresponding dissociated state, disallowing any fluctuations of the pulling centers along the way, one can determine a 3n-dimensional PMF curve connecting the two states by sampling a small number of forward and reverse pulling paths. This PMF constitutes a large but not the sole contribution to the binding free energy. Two other contributors are (1) the partial partition function containing the equilibrium fluctuations of the ligand at the binding site and the deviation of the initial state from the PMF minimum and (2) the partial partition function containing rotation and fluctuations of the ligand around one of the pulling centers that is fixed at a position far from the protein. We implement this hSMD approach for two ligand–protein complexes whose structures were determined and whose binding affinities were measured experimentally: caprylic acid binding to bovine β-lactoglobulin and glutathione binding to Schistosoma japonicum glutathione S-transferase tyrosine 7 to phenylalanine mutant. Our computed binding affinities agree with the experimental data within a factor of 1.5. The total time of computation for these two all-atom model systems (consisting of 96K and 114K atoms

  14. DOE Fundamentals Handbook: Classical Physics

    SciTech Connect

    Not Available

    1992-06-01

    The Classical Physics Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of physical forces and their properties. The handbook includes information on the units used to measure physical properties; vectors, and how they are used to show the net effect of various forces; Newton's Laws of motion, and how to use these laws in force and motion applications; and the concepts of energy, work, and power, and how to measure and calculate the energy involved in various applications. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility systems and equipment.

  15. Fundamental studies of polymer filtration

    SciTech Connect

    Smith, B.F.; Lu, M.T.; Robison, T.W.; Rogers, Y.C.; Wilson, K.V.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The objectives of this project were (1) to develop an enhanced fundamental understanding of the coordination chemistry of hazardous-metal-ion complexation with water-soluble metal-binding polymers, and (2) to exploit this knowledge to develop improved separations for analytical methods, metals processing, and waste treatment. We investigated features of water-soluble metal-binding polymers that affect their binding constants and selectivity for selected transition metal ions. We evaluated backbone polymers using light scattering and ultrafiltration techniques to determine the effect of pH and ionic strength on the molecular volume of the polymers. The backbone polymers were incrementally functionalized with a metal-binding ligand. A procedure and analytical method to determine the absolute level of functionalization was developed and the results correlated with the elemental analysis, viscosity, and molecular size.

  16. Mitochondrial motility in axons: membranous organelles may interact with the force generating system through multiple surface binding sites.

    PubMed

    Martz, D; Lasek, R J; Brady, S T; Allen, R D

    1984-01-01

    In living tissue, membrane-bound organelles, including mitochondria, move along parallel cytoplasmic pathways. Motion is directed and tends to be confined to a single path. Deviations from this single path motion are rare. When present, however, they tend to occur at points of intersection of cytoskeletal linear elements (LE). Such intersections are relatively uncommon in intact axons and extruded axoplasm. However, we have found that such intersections can be produced in extruded preparations by shear forces directed tangential to the axoplasmic surface. We have studied the detailed behavior of mitochondria in extruded squid axoplasm. Special attention was directed to the relationship between mitochondrial shape changes and orientation of cytoskeletal LE. The most striking of these changes in shape is branching. In this process, the mitochondrion transiently assumes a triradial (three-ended) shape. This appearance may be maintained for seconds to minutes before the normal cylindrical shape is resumed by absorption of either the newly formed end or, more commonly, one of the original ends. The frequency of branching appears to be dependent on the degree of cytoskeletal organization. It becomes more common as the number of apparent intersections between cytoskeletal LE increases. Further, the formation of new ends seems to occur along paths defined by cytoskeletal elements. These observations suggest that the mitochondrial membrane is multivalent. That is, it contains multiple sites capable of interacting with the axonal force generation apparatus. Furthermore, LE in the cytoskeleton may indicate the paths along which these interactions are permissible.

  17. Non-uniform binding of single-stranded DNA binding proteins to hybrids of single-stranded DNA and single-walled carbon nanotubes observed by atomic force microscopy in air and in liquid

    NASA Astrophysics Data System (ADS)

    Umemura, Kazuo; Ishizaka, Kei; Nii, Daisuke; Izumi, Katsuki

    2016-12-01

    Using atomic force spectroscopy (AFM), we observed hybrids of single-stranded DNA (ssDNA) and single-walled carbon nanotubes (SWNTs) with or without protein molecules in air and in an aqueous solution. This is the first report of ssDNA-SWNT hybrids with proteins in solution analyzed by AFM. In the absence of protein, the height of the ssDNA-SWNT hybrids was 1.1 ± 0.3 nm and 2.4 ± 0.6 nm in air and liquid, respectively, suggesting that the ssDNA molecules adopted a flexible structure on the SWNT surface. In the presence of single-stranded DNA binding (SSB) proteins, the heights of the hybrids in air and liquid increased to 6.4 ± 3.1 nm and 10.0 ± 4.5 nm, respectively. The AFM images clearly showed binding of the SSB proteins to the ssDNA-SWNT hybrids. The morphology of the SSB-ssDNA-SWNT hybrids was non-uniform, particularly in aqueous solution. The variance of hybrid height was quantitatively estimated by cross-section analysis along the long-axis of each hybrid. The SSB-ssDNA-SWNT hybrids showed much larger variance than the ssDNA-SWNT hybrids.

  18. A combined atomic force microscopy imaging and docking study to investigate the complex between p53 DNA binding domain and Azurin.

    PubMed

    Bizzarri, Anna Rita; Di Agostino, Silvia; Andolfi, Laura; Cannistraro, Salvatore

    2009-01-01

    The tumor suppressor p53 interacts with the redox copper protein Azurin (AZ) forming a complex which is of some relevance in biomedicine and cancer therapy. To obtain information on the spatial organization of this complex when it is immobilized on a substrate, we have used tapping mode-atomic force microscopy (TM-AFM) imaging combined with computational docking. The vertical dimension and the bearing volume of the DNA binding domain (DBD) of p53, anchored to functionalized gold substrate through exposed lysine residues, alone and after deposing AZ, have been measured by TM-AFM. By a computational docking approach, a three-dimensional model for the DBD of p53, before and after addition of AZ, have been predicted. Then we have calculated the possible arrangements of these biomolecular systems on gold substrate by finding a good agreement with the related experimental distribution of the height. The potentiality of the approach combining TM-AFM imaging and computational docking for the study of biomolecular complexes immobilized on substrates is briefly discussed.

  19. Combustion Fundamentals Research

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Increased emphasis is placed on fundamental and generic research at Lewis Research Center with less systems development efforts. This is especially true in combustion research, where the study of combustion fundamentals has grown significantly in order to better address the perceived long term technical needs of the aerospace industry. The main thrusts for this combustion fundamentals program area are as follows: analytical models of combustion processes, model verification experiments, fundamental combustion experiments, and advanced numeric techniques.

  20. Exchange Rates and Fundamentals.

    ERIC Educational Resources Information Center

    Engel, Charles; West, Kenneth D.

    2005-01-01

    We show analytically that in a rational expectations present-value model, an asset price manifests near-random walk behavior if fundamentals are I (1) and the factor for discounting future fundamentals is near one. We argue that this result helps explain the well-known puzzle that fundamental variables such as relative money supplies, outputs,…

  1. Fundamental Limits to Cellular Sensing

    NASA Astrophysics Data System (ADS)

    ten Wolde, Pieter Rein; Becker, Nils B.; Ouldridge, Thomas E.; Mugler, Andrew

    2016-03-01

    In recent years experiments have demonstrated that living cells can measure low chemical concentrations with high precision, and much progress has been made in understanding what sets the fundamental limit to the precision of chemical sensing. Chemical concentration measurements start with the binding of ligand molecules to receptor proteins, which is an inherently noisy process, especially at low concentrations. The signaling networks that transmit the information on the ligand concentration from the receptors into the cell have to filter this receptor input noise as much as possible. These networks, however, are also intrinsically stochastic in nature, which means that they will also add noise to the transmitted signal. In this review, we will first discuss how the diffusive transport and binding of ligand to the receptor sets the receptor correlation time, which is the timescale over which fluctuations in the state of the receptor, arising from the stochastic receptor-ligand binding, decay. We then describe how downstream signaling pathways integrate these receptor-state fluctuations, and how the number of receptors, the receptor correlation time, and the effective integration time set by the downstream network, together impose a fundamental limit on the precision of sensing. We then discuss how cells can remove the receptor input noise while simultaneously suppressing the intrinsic noise in the signaling network. We describe why this mechanism of time integration requires three classes (groups) of resources—receptors and their integration time, readout molecules, energy—and how each resource class sets a fundamental sensing limit. We also briefly discuss the scheme of maximum-likelihood estimation, the role of receptor cooperativity, and how cellular copy protocols differ from canonical copy protocols typically considered in the computational literature, explaining why cellular sensing systems can never reach the Landauer limit on the optimal trade

  2. The fundamental ribosomal RNA transcription initiation factor-IB (TIF-IB, SL1, factor D) binds to the rRNA core promoter primarily by minor groove contacts.

    PubMed

    Geiss, G K; Radebaugh, C A; Paule, M R

    1997-11-14

    Acanthamoeba castellanii transcription initiation factor-IB (TIF-IB) is the TATA-binding protein-containing transcription factor that binds the rRNA promoter to form the committed complex. Minor groove-specific drugs inhibit TIF-IB binding, with higher concentrations needed to disrupt preformed complexes because of drug exclusion by bound TIF-IB. TIF-IB/DNA interactions were mapped by hydroxyl radical and uranyl nitrate footprinting. TIF-IB contacts four minor grooves in its binding site. TIF-IB and DNA wrap around each other in a right-handed superhelix of high pitch, so the upstream and downstream contacts are on opposite faces of the helix. Dimethyl sulfate protection assays revealed limited contact with a few guanines in the major groove. This detailed analysis suggests significant DNA conformation dependence of the interaction.

  3. Altered responsiveness to cocaine and increased immobility in the forced swim test associated with elevated cAMP response element-binding protein expression in nucleus accumbens.

    PubMed

    Pliakas, A M; Carlson, R R; Neve, R L; Konradi, C; Nestler, E J; Carlezon, W A

    2001-09-15

    Drugs of abuse regulate the transcription factor cAMP response element-binding protein (CREB) in striatal regions, including the nucleus accumbens (NAc). To explore how regulation of CREB in the NAc affects behavior, we used herpes simplex virus (HSV) vectors to elevate CREB expression in this region or to overexpress a dominant-negative mutant CREB (mCREB) that blocks CREB function. Rats treated with HSV-mCREB in place conditioning studies spent more time in environments associated with cocaine, indicating increased cocaine reward. Conversely, rats treated with HSV-CREB spent less time in cocaine-associated environments, indicating increased cocaine aversion. Studies in which drug-environment pairings were varied to coincide with either the early or late effects of cocaine suggest that CREB-associated place aversions reflect increased cocaine withdrawal. Because cocaine withdrawal can be accompanied by symptoms of depression, we examined how altered CREB function in the NAc affects behavior in the forced swim test (FST). Elevated CREB expression increased immobility in the FST, an effect that is opposite to that caused by standard antidepressants and is consistent with a link between CREB and dysphoria. Conversely, overexpression of mCREB decreased immobility, an effect similar to that caused by antidepressants. Moreover, the kappa opioid receptor antagonist nor-Binaltorphimine decreased immobility in HSV-CREB- and HSV-mCREB-treated rats, suggesting that CREB-mediated induction of dynorphin (an endogenous kappa receptor ligand) contributes to immobility behavior in the FST. Exposure to the FST itself dramatically increased CREB function in the NAc. These findings raise the possibility that CREB-mediated transcription within the NAc regulates dysphoric states.

  4. Fundamental Physical Constants

    National Institute of Standards and Technology Data Gateway

    SRD 121 CODATA Fundamental Physical Constants (Web, free access)   This site, developed in the Physics Laboratory at NIST, addresses three topics: fundamental physical constants, the International System of Units (SI), which is the modern metric system, and expressing the uncertainty of measurement results.

  5. Fundamentals of Physics

    NASA Astrophysics Data System (ADS)

    Halliday, David; Resnick, Robert; Walker, Jearl

    2003-01-01

    No other book on the market today can match the success of Halliday, Resnick and Walker's Fundamentals of Physics! In a breezy, easy-to-understand style the book offers a solid understanding of fundamental physics concepts, and helps readers apply this conceptual understanding to quantitative problem solving.

  6. Water clusters in an argon matrix: infrared spectra from molecular dynamics simulations with a self-consistent charge density functional-based tight binding/force-field potential.

    PubMed

    Simon, Aude; Iftner, Christophe; Mascetti, Joëlle; Spiegelman, Fernand

    2015-03-19

    The present theoretical study aims at investigating the effects of an argon matrix on the structures, energetics, dynamics, and infrared (IR) spectra of small water clusters (H2O)n (n = 1-6). The potential energy surface is obtained from a hybrid self-consistent charge density functional-based tight binding/force-field approach (SCC-DFTB/FF) in which the water clusters are treated at the SCC-DFTB level and the matrix is modeled at the FF level by a cluster consisting of ∼340 Ar atoms with a face centered cubic (fcc) structure, namely (H2O)n/Ar. With respect to a pure FF scheme, this allows a quantum description of the molecular system embedded in the matrix, along with all-atom geometry optimization and molecular dynamics (MD) simulations of the (H2O)n/Ar system. Finite-temperature IR spectra are derived from the MD simulations. The SCC-DFTB/FF scheme is first benchmarked on (H2O)Arn clusters against correlated wave function results and DFT calculations performed in the present work, and against FF data available in the literature. Regarding (H2O)n/Ar systems, the geometries of the water clusters are found to adapt to the fcc environment, possibly leading to intermolecular distortion and matrix perturbation. Several energetical quantities are estimated to characterize the water clusters in the matrix. In the particular case of the water hexamer, substitution and insertion energies for the prism, bag, and cage are found to be lower than that for the 6-member ring isomer. Finite-temperature MD simulations show that the water monomer has a quasifree rotation motion at 13 K, in agreement with experimental data. In the case of the water dimer, the only large-amplitude motion is a distortion-rotation intermolecular motion, whereas only vibration motions around the nuclei equilibrium positions are observed for clusters with larger sizes. Regarding the IR spectra, we find that the matrix environment leads to redshifts of the stretching modes and almost no shift of the

  7. The selective glucocorticoid receptor antagonist ORG 34116 decreases immobility time in the forced swim test and affects cAMP-responsive element-binding protein phosphorylation in rat brain.

    PubMed

    Bachmann, Cornelius G; Bilang-Bleuel, Alicia; De Carli, Sonja; Linthorst, Astrid C E; Reul, Johannes M H M

    2005-01-01

    Glucocorticoid receptor (GR) antagonists can block the retention of the immobility response in the forced swimming test. Recently, we showed that forced swimming evokes a distinct spatiotemporal pattern of cAMP-responsive element-binding protein (CREB) phosphorylation in the dentate gyrus (DG) and neocortex. In the present study, we found that chronic treatment of rats with the selective GR antagonist ORG 34116 decreased the immobility time in the forced swim test, increased baseline levels of phosphorylated CREB (P-CREB) in the DG and neocortex and affected the forced swimming-induced changes in P-CREB levels in a time- and site-specific manner. Overall, we observed that, in control rats, forced swimming evoked increases in P-CREB levels in the DG and neocortex, whereas in ORG 34116-treated animals a major dephosphorylation of P-CREB was observed. These observations underscore an important role of GRs in the control of the phosphorylation state of CREB which seems to be of significance for the immobility response in the forced swim test and extend the molecular mechanism of action of GRs in the brain.

  8. The Strong Nuclear Force

    SciTech Connect

    Lincoln, Don

    2016-05-24

    Scientists are aware of four fundamental forces- gravity, electromagnetism, and the strong and weak nuclear forces. Most people have at least some familiarity with gravity and electromagnetism, but not the other two. How is it that scientists are so certain that two additional forces exist? In this video, Fermilab’s Dr. Don Lincoln explains why scientists are so certain that the strong force exists.

  9. The Strong Nuclear Force

    ScienceCinema

    Lincoln, Don

    2016-07-12

    Scientists are aware of four fundamental forces- gravity, electromagnetism, and the strong and weak nuclear forces. Most people have at least some familiarity with gravity and electromagnetism, but not the other two. How is it that scientists are so certain that two additional forces exist? In this video, Fermilab’s Dr. Don Lincoln explains why scientists are so certain that the strong force exists.

  10. Arguing against fundamentality

    NASA Astrophysics Data System (ADS)

    McKenzie, Kerry

    This paper aims to open up discussion on the relationship between fundamentality and naturalism, and in particular on the question of whether fundamentality may be denied on naturalistic grounds. A historico-inductive argument for an anti-fundamentalist conclusion, prominent within the contemporary metaphysical literature, is examined; finding it wanting, an alternative 'internal' strategy is proposed. By means of an example from the history of modern physics - namely S-matrix theory - it is demonstrated that (1) this strategy can generate similar (though not identical) anti-fundamentalist conclusions on more defensible naturalistic grounds, and (2) that fundamentality questions can be empirical questions. Some implications and limitations of the proposed approach are discussed.

  11. Monte Carlo fundamentals

    SciTech Connect

    Brown, F.B.; Sutton, T.M.

    1996-02-01

    This report is composed of the lecture notes from the first half of a 32-hour graduate-level course on Monte Carlo methods offered at KAPL. These notes, prepared by two of the principle developers of KAPL`s RACER Monte Carlo code, cover the fundamental theory, concepts, and practices for Monte Carlo analysis. In particular, a thorough grounding in the basic fundamentals of Monte Carlo methods is presented, including random number generation, random sampling, the Monte Carlo approach to solving transport problems, computational geometry, collision physics, tallies, and eigenvalue calculations. Furthermore, modern computational algorithms for vector and parallel approaches to Monte Carlo calculations are covered in detail, including fundamental parallel and vector concepts, the event-based algorithm, master/slave schemes, parallel scaling laws, and portability issues.

  12. Fundamentals of fluid sealing

    NASA Technical Reports Server (NTRS)

    Zuk, J.

    1976-01-01

    The fundamentals of fluid sealing, including seal operating regimes, are discussed and the general fluid-flow equations for fluid sealing are developed. Seal performance parameters such as leakage and power loss are presented. Included in the discussion are the effects of geometry, surface deformations, rotation, and both laminar and turbulent flows. The concept of pressure balancing is presented, as are differences between liquid and gas sealing. Mechanisms of seal surface separation, fundamental friction and wear concepts applicable to seals, seal materials, and pressure-velocity (PV) criteria are discussed.

  13. Fundamentals of fluid lubrication

    NASA Technical Reports Server (NTRS)

    Hamrock, Bernard J.

    1991-01-01

    The aim is to coordinate the topics of design, engineering dynamics, and fluid dynamics in order to aid researchers in the area of fluid film lubrication. The lubrication principles that are covered can serve as a basis for the engineering design of machine elements. The fundamentals of fluid film lubrication are presented clearly so that students that use the book will have confidence in their ability to apply these principles to a wide range of lubrication situations. Some guidance on applying these fundamentals to the solution of engineering problems is also provided.

  14. Binding of an antibody mimetic of the human low density lipoprotein receptor to apolipoprotein E is governed through electrostatic forces. Studies using site-directed mutagenesis and molecular modeling.

    PubMed

    Raffaï, R; Weisgraber, K H; MacKenzie, R; Rupp, B; Rassart, E; Hirama, T; Innerarity, T L; Milne, R

    2000-03-10

    Monoclonal antibody 2E8 is specific for an epitope that coincides with the binding site of the low density lipoprotein receptor (LDLR) on human apoE. Its reactivity with apoE variants resembles that of the LDLR: it binds well with apoE3 and poorly with apoE2. The heavy chain complementarity-determining region (CDRH) 2 of 2E8 shows homology to the ligand-binding domain of the LDLR. To define better the structural basis of the 2E8/apoE interaction and particularly the role of electrostatic interactions, we generated and characterized a panel of 2E8 variants. Replacement of acidic residues in the 2E8 CDRHs showed that Asp(52), Glu(53), and Asp(56) are essential for high-affinity binding. Although Asp(31) (CDRH1), Glu(58) (CDRH2), and Asp(97) (CDRH3) did not appear to be critical, the Asp(97) --> Ala variant acquired reactivity with apoE2. A Thr(57) --> Glu substitution increased affinity for both apoE3 and apoE2. The affinities of wild-type 2E8 and variants for apoE varied inversely with ionic strength, suggesting that electrostatic forces contribute to both antigen binding and isoform specificity. We propose a model of the 2E8.apoE immune complex that is based on the 2E8 and apoE crystal structures and that is consistent with the apoE-binding properties of wild-type 2E8 and its variants. Given the similarity between the LDLR and 2E8 in terms of specificity, the LDLR/ligand interaction may also have an important electrostatic component.

  15. The Vα14 invariant natural killer T cell TCR forces microbial glycolipids and CD1d into a conserved binding mode

    PubMed Central

    Li, Yali; Girardi, Enrico; Wang, Jing; Yu, Esther Dawen; Painter, Gavin F.; Kronenberg, Mitchell

    2010-01-01

    Invariant natural killer T cells (iNKT cells) rapidly produce effector cytokines. In this study, we report the first crystal structures of the iNKT cell T cell receptor (TCR) bound to two natural, microbial glycolipids presented by CD1d. Binding of the TCR induced CDR3-α–dependent structural changes in the F′ roof of CD1d; these changes resemble those occurring in the absence of TCR engagement when the highly potent synthetic antigen α-galactosylceramide (α-GalCer) binds CD1d. Furthermore, in the Borrelia burgdorferi α–galactosyl diacylglycerol–CD1d complex, TCR binding caused a marked repositioning of the galactose sugar into an orientation that closely resembles α-GalCer. The TCR-dependent reorientation of the sugar, together with the induced CD1d fit, may explain the weaker potency of the microbial antigens compared with α-GalCer. We propose that the TCR of iNKT cells binds with a conserved footprint onto CD1d, regardless of the bound glycolipid antigen, and that for microbial antigens this unique binding mode requires TCR-initiated conformational changes. PMID:20921281

  16. Mechanical regulation of a molecular clutch defines force transmission and transduction in response to matrix rigidity.

    PubMed

    Elosegui-Artola, Alberto; Oria, Roger; Chen, Yunfeng; Kosmalska, Anita; Pérez-González, Carlos; Castro, Natalia; Zhu, Cheng; Trepat, Xavier; Roca-Cusachs, Pere

    2016-05-01

    Cell function depends on tissue rigidity, which cells probe by applying and transmitting forces to their extracellular matrix, and then transducing them into biochemical signals. Here we show that in response to matrix rigidity and density, force transmission and transduction are explained by the mechanical properties of the actin-talin-integrin-fibronectin clutch. We demonstrate that force transmission is regulated by a dynamic clutch mechanism, which unveils its fundamental biphasic force/rigidity relationship on talin depletion. Force transduction is triggered by talin unfolding above a stiffness threshold. Below this threshold, integrins unbind and release force before talin can unfold. Above the threshold, talin unfolds and binds to vinculin, leading to adhesion growth and YAP nuclear translocation. Matrix density, myosin contractility, integrin ligation and talin mechanical stability differently and nonlinearly regulate both force transmission and the transduction threshold. In all cases, coupling of talin unfolding dynamics to a theoretical clutch model quantitatively predicts cell response.

  17. Food Service Fundamentals.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on food service fundamentals is designed to provide a general background in the basic aspects of the food service program in the Marine Corps; it is adaptable for nonmilitary instruction. Introductory materials include specific information for MCI…

  18. Basic Publication Fundamentals.

    ERIC Educational Resources Information Center

    Savedge, Charles E., Ed.

    Designed for students who produce newspapers and newsmagazines in junior high, middle, and elementary schools, this booklet is both a scorebook and a fundamentals text. The scorebook provides realistic criteria for judging publication excellence at these educational levels. All the basics for good publications are included in the text of the…

  19. Reading Is Fundamental, 1977.

    ERIC Educational Resources Information Center

    Smithsonian Institution, Washington, DC. National Reading is Fun-damental Program.

    Reading Is Fundamental (RIF) is a national, nonprofit organization designed to motivate children to read by making a wide variety of inexpensive books available to them and allowing the children to choose and keep books that interest them. This annual report for 1977 contains the following information on the RIF project: an account of the…

  20. Laser Fundamentals and Experiments.

    ERIC Educational Resources Information Center

    Van Pelt, W. F.; And Others

    As a result of work performed at the Southwestern Radiological Health Laboratory with respect to lasers, this manual was prepared in response to the increasing use of lasers in high schools and colleges. It is directed primarily toward the high school instructor who may use the text for a short course in laser fundamentals. The definition of the…

  1. Homeschooling and Religious Fundamentalism

    ERIC Educational Resources Information Center

    Kunzman, Robert

    2010-01-01

    This article considers the relationship between homeschooling and religious fundamentalism by focusing on their intersection in the philosophies and practices of conservative Christian homeschoolers in the United States. Homeschooling provides an ideal educational setting to support several core fundamentalist principles: resistance to…

  2. The Fundamental Property Relation.

    ERIC Educational Resources Information Center

    Martin, Joseph J.

    1983-01-01

    Discusses a basic equation in thermodynamics (the fundamental property relation), focusing on a logical approach to the development of the relation where effects other than thermal, compression, and exchange of matter with the surroundings are considered. Also demonstrates erroneous treatments of the relation in three well-known textbooks. (JN)

  3. Fundamentals of Library Instruction

    ERIC Educational Resources Information Center

    McAdoo, Monty L.

    2012-01-01

    Being a great teacher is part and parcel of being a great librarian. In this book, veteran instruction services librarian McAdoo lays out the fundamentals of the discipline in easily accessible language. Succinctly covering the topic from top to bottom, he: (1) Offers an overview of the historical context of library instruction, drawing on recent…

  4. Fundamentals of soil science

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study guide provides comments and references for professional soil scientists who are studying for the soil science fundamentals exam needed as the first step for certification. The performance objectives were determined by the Soil Science Society of America's Council of Soil Science Examiners...

  5. Fundamentals of Electromagnetic Phenomena

    NASA Astrophysics Data System (ADS)

    Lorrain, Paul; Corson, Dale R.; Lorrain, Francois

    Based on the classic Electromagnetic Fields and Waves by the same authors, Fundamentals of Electromagnetic Phenomena capitalizes on the older text's traditional strengths--solid physics, inventive problems, and an experimental approach--while offering a briefer, more accessible introduction to the basic principles of electromagnetism.

  6. Fundamentals of Solid Lubrication

    DTIC Science & Technology

    2012-03-01

    NOTES 14. ABSTRACT During this program, we have worked to develop a fundamental understanding of the chemical and tribological issues related to...approach, tribological measurements performed over a range of length scales, and the correlation of the two classes of information. Research activities...correlated measurements of surface composition and environmentally specific tribological performance of thin film solid lubricants. • Correlate shear

  7. Fundamentals of Diesel Engines.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the fundamentals of diesel engine mechanics. Addressed in the three individual units of the course are the following topics: basic principles of diesel mechanics; principles, mechanics, and…

  8. Fundamental properties of resonances.

    PubMed

    Ceci, S; Hadžimehmedović, M; Osmanović, H; Percan, A; Zauner, B

    2017-03-27

    All resonances, from hydrogen nuclei excited by the high-energy gamma rays in deep space to newly discovered particles produced in Large Hadron Collider, should be described by the same fundamental physical quantities. However, two distinct sets of properties are used to describe resonances: the pole parameters (complex pole position and residue) and the Breit-Wigner parameters (mass, width, and branching fractions). There is an ongoing decades-old debate on which one of them should be abandoned. In this study of nucleon resonances appearing in the elastic pion-nucleon scattering we discover an intricate interplay of the parameters from both sets, and realize that neither set is completely independent or fundamental on its own.

  9. Fundamental properties of resonances

    PubMed Central

    Ceci, S.; Hadžimehmedović, M.; Osmanović, H.; Percan, A.; Zauner, B.

    2017-01-01

    All resonances, from hydrogen nuclei excited by the high-energy gamma rays in deep space to newly discovered particles produced in Large Hadron Collider, should be described by the same fundamental physical quantities. However, two distinct sets of properties are used to describe resonances: the pole parameters (complex pole position and residue) and the Breit-Wigner parameters (mass, width, and branching fractions). There is an ongoing decades-old debate on which one of them should be abandoned. In this study of nucleon resonances appearing in the elastic pion-nucleon scattering we discover an intricate interplay of the parameters from both sets, and realize that neither set is completely independent or fundamental on its own. PMID:28345595

  10. Fundamentals of Polarized Light

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael

    2003-01-01

    The analytical and numerical basis for describing scattering properties of media composed of small discrete particles is formed by the classical electromagnetic theory. Although there are several excellent textbooks outlining the fundamentals of this theory, it is convenient for our purposes to begin with a summary of those concepts and equations that are central to the subject of this book and will be used extensively in the following chapters. We start by formulating Maxwell's equations and constitutive relations for time- harmonic macroscopic electromagnetic fields and derive the simplest plane-wave solution that underlies the basic optical idea of a monochromatic parallel beam of light. This solution naturally leads to the introduction of such fundamental quantities as the refractive index and the Stokes parameters. Finally, we define the concept of a quasi-monochromatic beam of light and discuss its implications.

  11. Fundamentals of neurobiology.

    PubMed

    Greg Hall, D

    2011-01-01

    Session 1 of the 2010 STP/IFSTP Joint Symposium on Toxicologic Neuropathology, titled "Fundamentals of Neurobiology," was organized to provide a foundation for subsequent sessions by presenting essential elements of neuroanatomy and nervous system function. A brief introduction to the session titled "Introduction to Correlative Neurobiology" was provided by Dr. Greg Hall (Eli Lilly and Company, Indianapolis, IN). Correlative neurobiology refers to considerations of the relationships between the highly organized and compartmentalized structure of nervous tissues and the functioning within this system.

  12. Fundamental studies in geodynamics

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.; Hager, B. H.; Kanamori, H.

    1981-01-01

    Research in fundamental studies in geodynamics continued in a number of fields including seismic observations and analysis, synthesis of geochemical data, theoretical investigation of geoid anomalies, extensive numerical experiments in a number of geodynamical contexts, and a new field seismic volcanology. Summaries of work in progress or completed during this report period are given. Abstracts of publications submitted from work in progress during this report period are attached as an appendix.

  13. Fundamentals of petroleum maps

    SciTech Connect

    Mc Elroy, D.P.

    1986-01-01

    It's a complete guide to the fundamentals of reading, using, and making petroleum maps. The topics covered are well spotting, lease posting, contouring, hanging cross sections, and ink drafting. This book not only tells the how of petroleum mapping, but it also tells the why to better understand the principles and techniques. The books does not teach ''drafting,'' but does describe the proper care and use of drafting equipment for those who are totally new to the task.

  14. Fundamentals of Monte Carlo

    SciTech Connect

    Wollaber, Allan Benton

    2016-06-16

    This is a powerpoint presentation which serves as lecture material for the Parallel Computing summer school. It goes over the fundamentals of the Monte Carlo calculation method. The material is presented according to the following outline: Introduction (background, a simple example: estimating π), Why does this even work? (The Law of Large Numbers, The Central Limit Theorem), How to sample (inverse transform sampling, rejection), and An example from particle transport.

  15. Value of Fundamental Science

    NASA Astrophysics Data System (ADS)

    Burov, Alexey

    Fundamental science is a hard, long-term human adventure that has required high devotion and social support, especially significant in our epoch of Mega-science. The measure of this devotion and this support expresses the real value of the fundamental science in public opinion. Why does fundamental science have value? What determines its strength and what endangers it? The dominant answer is that the value of science arises out of curiosity and is supported by the technological progress. Is this really a good, astute answer? When trying to attract public support, we talk about the ``mystery of the universe''. Why do these words sound so attractive? What is implied by and what is incompatible with them? More than two centuries ago, Immanuel Kant asserted an inseparable entanglement between ethics and metaphysics. Thus, we may ask: which metaphysics supports the value of scientific cognition, and which does not? Should we continue to neglect the dependence of value of pure science on metaphysics? If not, how can this issue be addressed in the public outreach? Is the public alienated by one or another message coming from the face of science? What does it mean to be politically correct in this sort of discussion?

  16. Force-clamp laser trapping of rapidly interacting molecules

    NASA Astrophysics Data System (ADS)

    Capitanio, Marco; Monico, Carina; Vanzi, Francesco; Pavone, Francesco S.

    2013-06-01

    Forces play a fundamental role in a wide array of biological processes, regulating enzymatic activity, kinetics of molecular bonds, and molecular motors mechanics. Single molecule force spectroscopy techniques have enabled the investigation of such processes, but they are inadequate to probe short-lived (millisecond and sub-millisecond) molecular complexes. We developed an ultrafast force-clamp spectroscopy technique that uses a dual trap configuration to apply constant loads to a single intermittently interacting biological polymer and a binding protein. Our system displays a delay of only ˜10 μs between formation of the molecular bond and application of the force and is capable of detecting interactions as short as 100 μs. The force-clamp configuration in which our assay operates allows direct measurements of load-dependence of lifetimes of single molecular bonds. Moreover, conformational changes of single proteins and molecular motors can be recorded with sub-nanometer accuracy and few tens of microseconds of temporal resolution. We demonstrate our technique on molecular motors, using myosin II from fast skeletal muscle and on protein-DNA interaction, specifically on Lactose repressor (LacI). The apparatus is stabilized to less than 1 nm with both passive and active stabilization, allowing resolving specific binding regions along the actin filament and DNA molecule. Our technique extends single-molecule force-clamp spectroscopy to molecular complexes that have been inaccessible up to now, opening new perspectives for the investigation of the effects of forces on biological processes.

  17. Electrostatic Forces as Dominant Interactions Between Proteins and Polyanions: an ESI MS Study of Fibroblast Growth Factor Binding to Heparin Oligomers.

    PubMed

    Minsky, Burcu Baykal; Dubin, Paul L; Kaltashov, Igor A

    2017-04-01

    The interactions between fibroblast growth factors (FGFs) and their receptors (FGFRs) are facilitated by heparan sulfate (HS) and heparin (Hp), highly sulfated biological polyelectrolytes. The molecular basis of FGF interactions with these polyelectrolytes is highly complex due to the structural heterogeneity of HS/Hp, and many details still remain elusive, especially the significance of charge density and minimal chain length of HS/Hp in growth factor recognition and multimerization. In this work, we use electrospray ionization mass spectrometry (ESI MS) to investigate the association of relatively homogeneous oligoheparins (octamer, dp8, and decamer, dp10) with acidic fibroblast growth factor (FGF-1). This growth factor forms 1:1, 2:1, and 3:1 protein/heparinoid complexes with both dp8 and dp10, and the fraction of bound protein is highly dependent on protein/heparinoid molar ratio. Multimeric complexes are preferentially formed on the highly sulfated Hp oligomers. Although a variety of oligomers appear to be binding-competent, there is a strong correlation between the affinity and the overall level of sulfation (the highest charge density polyanions binding FGF most strongly via multivalent interactions). These results show that the interactions between FGF-1 and Hp oligomers are primarily directed by electrostatics, and also demonstrate the power of ESI MS as a tool to study multiple binding equilibria between proteins and structurally heterogeneous polyanions. Graphical Abstract ᅟ.

  18. Electrostatic Forces as Dominant Interactions Between Proteins and Polyanions: an ESI MS Study of Fibroblast Growth Factor Binding to Heparin Oligomers

    NASA Astrophysics Data System (ADS)

    Minsky, Burcu Baykal; Dubin, Paul L.; Kaltashov, Igor A.

    2017-02-01

    The interactions between fibroblast growth factors (FGFs) and their receptors (FGFRs) are facilitated by heparan sulfate (HS) and heparin (Hp), highly sulfated biological polyelectrolytes. The molecular basis of FGF interactions with these polyelectrolytes is highly complex due to the structural heterogeneity of HS/Hp, and many details still remain elusive, especially the significance of charge density and minimal chain length of HS/Hp in growth factor recognition and multimerization. In this work, we use electrospray ionization mass spectrometry (ESI MS) to investigate the association of relatively homogeneous oligoheparins (octamer, dp8, and decamer, dp10) with acidic fibroblast growth factor (FGF-1). This growth factor forms 1:1, 2:1, and 3:1 protein/heparinoid complexes with both dp8 and dp10, and the fraction of bound protein is highly dependent on protein/heparinoid molar ratio. Multimeric complexes are preferentially formed on the highly sulfated Hp oligomers. Although a variety of oligomers appear to be binding-competent, there is a strong correlation between the affinity and the overall level of sulfation (the highest charge density polyanions binding FGF most strongly via multivalent interactions). These results show that the interactions between FGF-1 and Hp oligomers are primarily directed by electrostatics, and also demonstrate the power of ESI MS as a tool to study multiple binding equilibria between proteins and structurally heterogeneous polyanions.

  19. Quantum electrodynamics and fundamental constants

    NASA Astrophysics Data System (ADS)

    Wundt, Benedikt Johannes Wilhelm

    The unprecedented precision achieved both in the experimental measurements as well as in the theoretical description of atomic bound states make them an ideal study object for fundamental physics and the determination of fundamental constants. This requires a careful study of the effects from quantum electrodynamics (QED) on the interaction between the electron and the nucleus. The two theoretical approaches for the evaluation of QED corrections are presented and discussed. Due to the presence of two energy scales from the binding potential and the radiation field, an overlapping parameter has to be used in both approaches in order to separate the energy scales. The different choices for the overlapping parameter in the two methods are further illustrated in a model example. With the nonrelativistic theory, relativistic corrections in order ( Zalpha)2 to the two-photon decay rate of ionic states are calculated, as well as the leading radiative corrections of alpha( Zalpha)2ln[(Zalpha)-2 ]. It is shown that the corrections is gauge-invariant under a "hybrid" gauge transformation between Coulomb and Yennie gauge. Furthermore, QED corrections for Rydberg states in one-electron ions are investigated. The smallness of the corrections and the absence of nuclear size corrections enable very accurate theoretical predictions. Measuring transition frequencies and comparing them to the theoretical predictions, QED theory can be tested more precisely. In turn, this could yield a more accurate value for the Rydberg constant. Using a transition in a nucleus with a well determined mass, acting as a reference, a comparison to transition in other nuclei can even allow to determined nuclear masses. Finally, in order to avoid an additional uncertainty in nuclei with non zero nuclear spin, QED self-energy corrections to the hyperfine structure up to order alpha(Zalpha)2Delta EHFS are determined for highly excited Rydberg states.

  20. Structural Properties of MgSiO3 Perovskite, Twin Walls and Their Binding to Oxygen Vacancies at High Pressures from Force Field Simulations

    NASA Astrophysics Data System (ADS)

    Goncalves-Ferreira, L.; Redfern, S. A.; Artacho, E.

    2007-12-01

    Aiming to understand possible origins of seismic wave attenuation and variations in the quality factor (Q) of minerals at the Earth's interior, it has been accepted that the friction in the motion of twin domain walls under applied stress leads to a reduction in Q [1]. To interpret this behaviour one must first appreciate the influence of pressure on wall motion and dynamics. Experimental observations of twin wall motion at high pressure are difficult at present. For this reason, we have undertaken a computational study of wall structure and dynamics in MgSiO3 perovskite, in the absence or presence of defects, as a function of pressure between 0 and 140 GPa. This work is based on previous studies on CaTiO3 perovskite [2,3] (symmetry Pbnm) with 7800 atoms and orthorhombic periodic boundary conditions. It has been geometrically adapted to lower mantle's MgSiO3 perovskite. The system comprises two (100) ferroelastic twin walls separated by 34.2 Å, relaxed within a variable supercell of 26x10x6 unit cells, with the rigid ion set of interatomic potentials with partial ionic charges employed by Alfredsson et al., 2005 [4]. The degree of distortion in the system is manifest in the octahedral tilting angles along each of the crystallographic directions. The octahedral tilting orientations close to the walls are well described by the behaviour of two order parameters: the main one, defining the wall, goes as α tanh(2(x - x')/w) , where α = 11.14° is the bulk value for the tilt, and w = 11.11 Å is the wall width. The secondary order parameters describe a slight breather at the wall. As wall dynamics are influenced by the presence of oxygen vacancies, we have calculated their binding energies to the described twin walls as a function of pressure. We find that this binding strongly depends on the vacancy disposition. For a vacancy between Si atoms in an axis perpendicular to the wall the binding energy is 1.09 eV at zero pressure. For vacancies along Si-Si axes parallel

  1. Fundamental experiments in velocimetry

    SciTech Connect

    Briggs, Matthew Ellsworth; Hull, Larry; Shinas, Michael

    2009-01-01

    One can understand what velocimetry does and does not measure by understanding a few fundamental experiments. Photon Doppler Velocimetry (PDV) is an interferometer that will produce fringe shifts when the length of one of the legs changes, so we might expect the fringes to change whenever the distance from the probe to the target changes. However, by making PDV measurements of tilted moving surfaces, we have shown that fringe shifts from diffuse surfaces are actually measured only from the changes caused by the component of velocity along the beam. This is an important simplification in the interpretation of PDV results, arising because surface roughness randomizes the scattered phases.

  2. Chemical Force Spectroscopy Evidence Supporting the Layer-by-Layer Model of Organic Matter Binding to Iron (oxy)Hydroxide Mineral Surfaces.

    PubMed

    Chassé, Alexander W; Ohno, Tsutomu; Higgins, Steven R; Amirbahman, Aria; Yildirim, Nadir; Parr, Thomas B

    2015-08-18

    The adsorption of dissolved organic matter (DOM) to metal (oxy)hydroxide mineral surfaces is a critical step for C sequestration in soils. Although equilibrium studies have described some of the factors controlling this process, the molecular-scale description of the adsorption process has been more limited. Chemical force spectroscopy revealed differing adhesion strengths of DOM extracted from three soils and a reference peat soil material to an iron (oxy)hydroxide mineral surface. The DOM was characterized using ultrahigh-resolution negative ion mode electrospray ionization Fourier Transform ion cyclotron resonance mass spectrometry. The results indicate that carboxyl-rich aromatic and N-containing aliphatic molecules of DOM are correlated with high adhesion forces. Increasing molecular mass was shown to decrease the adhesion force between the mineral surface and the DOM. Kendrick mass defect analysis suggests that mechanisms involving two carboxyl groups result in the most stable bond to the mineral surface. We conceptualize these results using a layer-by-layer "onion" model of organic matter stabilization on soil mineral surfaces.

  3. Binding Strength and Dynamics of Invariant Natural Killer Cell T Cell Receptor/CD1d-Glycosphingolipid Interaction on Living Cells by Single Molecule Force Spectroscopy*

    PubMed Central

    Bozna, Bianca L.; Polzella, Paolo; Rankl, Christian; Zhu, Rong; Salio, Mariolina; Shepherd, Dawn; Duman, Memed; Cerundolo, Vincenzo; Hinterdorfer, Peter

    2011-01-01

    Invariant natural killer T (iNKT) cells are a population of T lymphocytes that play an important role in regulating immunity to infection and tumors by recognizing endogenous and exogenous CD1d-bound lipid molecules. Using soluble iNKT T cell receptor (TCR) molecules, we applied single molecule force spectroscopy for the investigation of the iNKT TCR affinity for human CD1d molecules loaded with glycolipids differing in the length of the phytosphingosine chain using either recombinant CD1d molecules or lipid-pulsed THP1 cells. In both settings, the dissociation of the iNKT TCR from human CD1d molecules loaded with the lipid containing the longer phytosphingosine chain required higher unbinding forces compared with the shorter phytosphingosine lipid. Our findings are discussed in the context of previous results obtained by surface plasmon resonance measurements. We present new insights into the energy landscape and the kinetic rate constants of the iNKT TCR/human CD1d-glycosphingolipid interaction and emphasize the unique potential of single molecule force spectroscopy on living cells. PMID:21454514

  4. Binding strength and dynamics of invariant natural killer cell T cell receptor/CD1d-glycosphingolipid interaction on living cells by single molecule force spectroscopy.

    PubMed

    Bozna, Bianca L; Polzella, Paolo; Rankl, Christian; Zhu, Rong; Salio, Mariolina; Shepherd, Dawn; Duman, Memed; Cerundolo, Vincenzo; Hinterdorfer, Peter

    2011-05-06

    Invariant natural killer T (iNKT) cells are a population of T lymphocytes that play an important role in regulating immunity to infection and tumors by recognizing endogenous and exogenous CD1d-bound lipid molecules. Using soluble iNKT T cell receptor (TCR) molecules, we applied single molecule force spectroscopy for the investigation of the iNKT TCR affinity for human CD1d molecules loaded with glycolipids differing in the length of the phytosphingosine chain using either recombinant CD1d molecules or lipid-pulsed THP1 cells. In both settings, the dissociation of the iNKT TCR from human CD1d molecules loaded with the lipid containing the longer phytosphingosine chain required higher unbinding forces compared with the shorter phytosphingosine lipid. Our findings are discussed in the context of previous results obtained by surface plasmon resonance measurements. We present new insights into the energy landscape and the kinetic rate constants of the iNKT TCR/human CD1d-glycosphingolipid interaction and emphasize the unique potential of single molecule force spectroscopy on living cells.

  5. Fundamentals of Space Systems

    NASA Astrophysics Data System (ADS)

    Pisacane, Vincent L.

    2005-06-01

    Fundamentals of Space Systems was developed to satisfy two objectives: the first is to provide a text suitable for use in an advanced undergraduate or beginning graduate course in both space systems engineering and space system design. The second is to be a primer and reference book for space professionals wishing to broaden their capabilities to develop, manage the development, or operate space systems. The authors of the individual chapters are practicing engineers that have had extensive experience in developing sophisticated experimental and operational spacecraft systems in addition to having experience teaching the subject material. The text presents the fundamentals of all the subsystems of a spacecraft missions and includes illustrative examples drawn from actual experience to enhance the learning experience. It included a chapter on each of the relevant major disciplines and subsystems including space systems engineering, space environment, astrodynamics, propulsion and flight mechanics, attitude determination and control, power systems, thermal control, configuration management and structures, communications, command and telemetry, data processing, embedded flight software, survuvability and reliability, integration and test, mission operations, and the initial conceptual design of a typical small spacecraft mission.

  6. Testing Our Fundamental Assumptions

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-06-01

    Science is all about testing the things we take for granted including some of the most fundamental aspects of how we understand our universe. Is the speed of light in a vacuum the same for all photons regardless of their energy? Is the rest mass of a photon actually zero? A series of recent studies explore the possibility of using transient astrophysical sources for tests!Explaining Different Arrival TimesArtists illustration of a gamma-ray burst, another extragalactic transient, in a star-forming region. [NASA/Swift/Mary Pat Hrybyk-Keith and John Jones]Suppose you observe a distant transient astrophysical source like a gamma-ray burst, or a flare from an active nucleus and two photons of different energies arrive at your telescope at different times. This difference in arrival times could be due to several different factors, depending on how deeply you want to question some of our fundamental assumptions about physics:Intrinsic delayThe photons may simply have been emitted at two different times by the astrophysical source.Delay due to Lorentz invariance violationPerhaps the assumption that all massless particles (even two photons with different energies) move at the exact same velocity in a vacuum is incorrect.Special-relativistic delayMaybe there is a universal speed for massless particles, but the assumption that photons have zero rest mass is wrong. This, too, would cause photon velocities to be energy-dependent.Delay due to gravitational potentialPerhaps our understanding of the gravitational potential that the photons experience as they travel is incorrect, also causing different flight times for photons of different energies. This would mean that Einsteins equivalence principle, a fundamental tenet of general relativity (GR), is incorrect.If we now turn this problem around, then by measuring the arrival time delay between photons of different energies from various astrophysical sources the further away, the better we can provide constraints on these

  7. Finite-difference analysis of plasmon-induced forces of metal nano-clusters by the Lorentz force formulation.

    PubMed

    Fujii, Masafumi

    2010-12-20

    We analyze light-induced forces on metal nano-spheres by using the three-dimensional finite-difference time-domain method with the Lorentz force formulation. Convergent analysis of the force on metal nano-particle clusters has been achieved by integrating the Lorentz and the Coulomb forces over the volume of the metal particles. Comparison to the Mie theory of radiation pressure on metal spheres under a plane wave illumination has verified rigorously the accuracy of the numerical method. We also analyze separate two metal spheres in close proximity and the results of the induced forces are compared to those in previous publications. The present method allows analysis of forces on various irregular structures; we apply the method to touching metal spheres, forming a simple cluster with a slight deformation at the contact point, to analyze the forces induced by the plasmonic resonance of the clusters. We show that the fundamental resonance modes, which newly appear in an infrared range when spheres are touching, exhibit strong binding forces within the clusters. Based on the numerical analyses we identify the resonance modes and evaluate quantitatively the infrared-induced forces on metal nano-sphere clusters.

  8. Mapping the force-field of a hydrogen bonded assembly

    NASA Astrophysics Data System (ADS)

    Moriarty, Philip

    2014-03-01

    Hydrogen-bonding underpins the structure, properties, and dynamics of a vast array of systems spanning a wide variety of scientific fields. From the striking complexity of the phase diagram of H2O and the elegance of base pair interactions in DNA, to the directionality inherent in supramolecular self-assembly at surfaces, hydrogen bonds play an essential role in directing intermolecular forces. Yet fundamental aspects of the H-bond, including the magnitude of the force and binding energy, force constant, and decay length associated with the interaction, have been vigorously debated for many decades. I will discuss how dynamic force microscopy (DFM) using a qPlus sensor can quantitatively map the tip-sample force-field for naphthalene tetracarboxylic diimide (NTCDI) molecules hydrogen-bonded in 2D assemblies. A comparison of experimental images and force spectra with their simulated counterparts from density functional theory calculations shows that image contrast due to intermolecular hydrogen bonds arises fundamentally from charge density depletion due to strong tip-sample interactions. Interpretation of DFM images of hydrogen bonds therefore necessitates detailed consideration of the coupled tip-molecule system: analyses based on intermolecular charge density in the absence of the tip fail to capture the essential physical chemistry underpinning the imaging mechanism.

  9. Binding Energy and Enzymatic Catalysis.

    ERIC Educational Resources Information Center

    Hansen, David E.; Raines, Ronald T.

    1990-01-01

    Discussed is the fundamental role that the favorable free energy of binding of the rate-determining transition state plays in catalysis. The principle that all of the catalytic factors discussed are realized by the use of this binding energy is reviewed. (CW)

  10. Fundamentals of zoological scaling

    NASA Astrophysics Data System (ADS)

    Lin, Herbert

    1982-01-01

    Most introductory physics courses emphasize highly idealized problems with unique well-defined answers. Though many textbooks complement these problems with estimation problems, few books present anything more than an elementary discussion of scaling. This paper presents some fundamentals of scaling in the zoological domain—a domain complex by any standard, but one also well suited to illustrate the power of very simple physical ideas. We consider the following animal characteristics: skeletal weight, speed of running, height and range of jumping, food consumption, heart rate, lifetime, locomotive efficiency, frequency of wing flapping, and maximum sizes of animals that fly and hover. These relationships are compared to zoological data and everyday experience, and match reasonably well.

  11. Nuclei and Fundamental Symmetries

    NASA Astrophysics Data System (ADS)

    Haxton, Wick

    2016-09-01

    Nuclei provide marvelous laboratories for testing fundamental interactions, often enhancing weak processes through accidental degeneracies among states, and providing selection rules that can be exploited to isolate selected interactions. I will give an overview of current work, including the use of parity violation to probe unknown aspects of the hadronic weak interaction; nuclear electric dipole moment searches that may shed light on new sources of CP violation; and tests of lepton number violation made possible by the fact that many nuclei can only decay by rare second-order weak interactions. I will point to opportunities in both theory and experiment to advance the field. Based upon work supported in part by the US Department of Energy, Office of Science, Office of Nuclear Physics and SciDAC under Awards DE-SC00046548 (Berkeley), DE-AC02-05CH11231 (LBNL), and KB0301052 (LBNL).

  12. Wall of fundamental constants

    SciTech Connect

    Olive, Keith A.; Peloso, Marco; Uzan, Jean-Philippe

    2011-02-15

    We consider the signatures of a domain wall produced in the spontaneous symmetry breaking involving a dilatonlike scalar field coupled to electromagnetism. Domains on either side of the wall exhibit slight differences in their respective values of the fine-structure constant, {alpha}. If such a wall is present within our Hubble volume, absorption spectra at large redshifts may or may not provide a variation in {alpha} relative to the terrestrial value, depending on our relative position with respect to the wall. This wall could resolve the contradiction between claims of a variation of {alpha} based on Keck/Hires data and of the constancy of {alpha} based on Very Large Telescope data. We derive the properties of the wall and the parameters of the underlying microscopic model required to reproduce the possible spatial variation of {alpha}. We discuss the constraints on the existence of the low-energy domain wall and describe its observational implications concerning the variation of the fundamental constants.

  13. Fundamentals of gel dosimeters

    NASA Astrophysics Data System (ADS)

    McAuley, K. B.; Nasr, A. T.

    2013-06-01

    Fundamental chemical and physical phenomena that occur in Fricke gel dosimeters, polymer gel dosimeters, micelle gel dosimeters and genipin gel dosimeters are discussed. Fricke gel dosimeters are effective even though their radiation sensitivity depends on oxygen concentration. Oxygen contamination can cause severe problems in polymer gel dosimeters, even when THPC is used. Oxygen leakage must be prevented between manufacturing and irradiation of polymer gels, and internal calibration methods should be used so that contamination problems can be detected. Micelle gel dosimeters are promising due to their favourable diffusion properties. The introduction of micelles to gel dosimetry may open up new areas of dosimetry research wherein a range of water-insoluble radiochromic materials can be explored as reporter molecules.

  14. Fundamental frequency from classical molecular dynamics.

    PubMed

    Yamada, Tomonori; Aida, Misako

    2015-02-07

    We give a theoretical validation for calculating fundamental frequencies of a molecule from classical molecular dynamics (MD) when its anharmonicity is small enough to be treated by perturbation theory. We specifically give concrete answers to the following questions: (1) What is the appropriate initial condition of classical MD to calculate the fundamental frequency? (2) From that condition, how accurately can we extract fundamental frequencies of a molecule? (3) What is the benefit of using ab initio MD for frequency calculations? Our analytical approaches to those questions are classical and quantum normal form theories. As numerical examples we perform two types of MD to calculate fundamental frequencies of H2O with MP2/aug-cc-pVTZ: one is based on the quartic force field and the other one is direct ab initio MD, where the potential energies and the gradients are calculated on the fly. From those calculations, we show comparisons of the frequencies from MD with the post vibrational self-consistent field calculations, second- and fourth-order perturbation theories, and experiments. We also apply direct ab initio MD to frequency calculations of C-H vibrational modes of tetracene and naphthalene. We conclude that MD can give the same accuracy in fundamental frequency calculation as second-order perturbation theory but the computational cost is lower for large molecules.

  15. No fifth force?

    NASA Astrophysics Data System (ADS)

    Maggs, William Ward

    Hopes that geophysicists might be able to document a fifth force of nature have diminished, as new measurements and analyses of earlier geodetic experiments have yielded no solid evidence of a non-Newtonian component of gravity.Modern physics recognizes four fundamental forces with distinct spheres of influence: The strong and weak nuclear forces operate over the range of one atom, while gravity and electromagnetism have an infinite range. Gravity measurements over a few centimeters in laboratories and over millions of kilometers in space continue to buttress Issac Newton's conclusion that the gravitational force between two objects decreases as the square of the distance between them.

  16. Evaluation of the grand-canonical partition function using expanded Wang-Landau simulations. IV. Performance of many-body force fields and tight-binding schemes for the fluid phases of silicon

    NASA Astrophysics Data System (ADS)

    Desgranges, Caroline; Delhommelle, Jerome

    2016-03-01

    We extend Expanded Wang-Landau (EWL) simulations beyond classical systems and develop the EWL method for systems modeled with a tight-binding Hamiltonian. We then apply the method to determine the partition function and thus all thermodynamic properties, including the Gibbs free energy and entropy, of the fluid phases of Si. We compare the results from quantum many-body (QMB) tight binding models, which explicitly calculate the overlap between the atomic orbitals of neighboring atoms, to those obtained with classical many-body (CMB) force fields, which allow to recover the tetrahedral organization in condensed phases of Si through, e.g., a repulsive 3-body term that favors the ideal tetrahedral angle. Along the vapor-liquid coexistence, between 3000 K and 6000 K, the densities for the two coexisting phases are found to vary significantly (by 5 orders of magnitude for the vapor and by up to 25% for the liquid) and to provide a stringent test of the models. Transitions from vapor to liquid are predicted to occur for chemical potentials that are 10%-15% higher for CMB models than for QMB models, and a ranking of the force fields is provided by comparing the predictions for the vapor pressure to the experimental data. QMB models also reveal the formation of a gap in the electronic density of states of the coexisting liquid at high temperatures. Subjecting Si to a nanoscopic confinement has a dramatic effect on the phase diagram with, e.g. at 6000 K, a decrease in liquid densities by about 50% for both CMB and QMB models and an increase in vapor densities between 90% (CMB) and 170% (QMB). The results presented here provide a full picture of the impact of the strategy (CMB or QMB) chosen to model many-body effects on the thermodynamic properties of the fluid phases of Si.

  17. GRBs and Fundamental Physics

    NASA Astrophysics Data System (ADS)

    Petitjean, Patrick; Wang, F. Y.; Wu, X. F.; Wei, J. J.

    2016-12-01

    Gamma-ray bursts (GRBs) are short and intense flashes at the cosmological distances, which are the most luminous explosions in the Universe. The high luminosities of GRBs make them detectable out to the edge of the visible universe. So, they are unique tools to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal evolution of the Universe. First, they can be used to constrain the history of cosmic acceleration and the evolution of dark energy in a redshift range hardly achievable by other cosmological probes. Second, long GRBs are believed to be formed by collapse of massive stars. So they can be used to derive the high-redshift star formation rate, which can not be probed by current observations. Moreover, the use of GRBs as cosmological tools could unveil the reionization history and metal evolution of the Universe, the intergalactic medium (IGM) properties and the nature of first stars in the early universe. But beyond that, the GRB high-energy photons can be applied to constrain Lorentz invariance violation (LIV) and to test Einstein's Equivalence Principle (EEP). In this paper, we review the progress on the GRB cosmology and fundamental physics probed by GRBs.

  18. Overlay accuracy fundamentals

    NASA Astrophysics Data System (ADS)

    Kandel, Daniel; Levinski, Vladimir; Sapiens, Noam; Cohen, Guy; Amit, Eran; Klein, Dana; Vakshtein, Irina

    2012-03-01

    Currently, the performance of overlay metrology is evaluated mainly based on random error contributions such as precision and TIS variability. With the expected shrinkage of the overlay metrology budget to < 0.5nm, it becomes crucial to include also systematic error contributions which affect the accuracy of the metrology. Here we discuss fundamental aspects of overlay accuracy and a methodology to improve accuracy significantly. We identify overlay mark imperfections and their interaction with the metrology technology, as the main source of overlay inaccuracy. The most important type of mark imperfection is mark asymmetry. Overlay mark asymmetry leads to a geometrical ambiguity in the definition of overlay, which can be ~1nm or less. It is shown theoretically and in simulations that the metrology may enhance the effect of overlay mark asymmetry significantly and lead to metrology inaccuracy ~10nm, much larger than the geometrical ambiguity. The analysis is carried out for two different overlay metrology technologies: Imaging overlay and DBO (1st order diffraction based overlay). It is demonstrated that the sensitivity of DBO to overlay mark asymmetry is larger than the sensitivity of imaging overlay. Finally, we show that a recently developed measurement quality metric serves as a valuable tool for improving overlay metrology accuracy. Simulation results demonstrate that the accuracy of imaging overlay can be improved significantly by recipe setup optimized using the quality metric. We conclude that imaging overlay metrology, complemented by appropriate use of measurement quality metric, results in optimal overlay accuracy.

  19. Assessment of DNA binding to human Rad51 protein by using quartz crystal microbalance and atomic force microscopy: effects of ADP and BRC4-28 peptide inhibitor.

    PubMed

    Esnault, Charles; Renodon-Cornière, Axelle; Takahashi, Masayuki; Casse, Nathalie; Delorme, Nicolas; Louarn, Guy; Fleury, Fabrice; Pilard, Jean-François; Chénais, Benoît

    2014-12-01

    The interaction of human Rad51 protein (HsRad51) with single-stranded deoxyribonucleic acid (ssDNA) was investigated by using quartz crystal microbalance (QCM) monitoring and atomic force microscopy (AFM) visualization. Gold surfaces for QCM and AFM were modified by electrografting of the in situ generated aryldiazonium salt from the sulfanilic acid to obtain the organic layer Au-ArSO3 H. The Au-ArSO3 H layer was activated by using a solution of PCl5 in CH2 Cl2 to give a Au-ArSO2 Cl layer. The modified surface was then used to immobilize long ssDNA molecules. The results obtained showed that the presence of adenosine diphosphate promotes the protein autoassociation rather than nucleation around DNA. In addition, when the BRC4-28 peptide inhibitor was used, both QCM and AFM confirmed the inhibitory effect of BRC4-28 toward HsRad51 autoassociation. Altogether these results show the suitability of this modified surface to investigate the kinetics and structure of DNA-protein interactions and for the screening of inhibitors.

  20. On Correlation Effect of the Van-der-Waals and Intramolecular Forces for the Nucleotide Chain - Metallic Nanoparticles - Carbon Nanotube Binding

    PubMed Central

    Khusenov, M.A.; Dushanov, E.B.; Kholmurodov, Kh.T; Zaki, M.M.; Sweilam, N.H.

    2016-01-01

    Background: The tertiary system of nucleotide chain (NC) - gold nanoparticles (NPs) - carbon nanotube (CNT) represents a great interest in the modern research and application of the bio-nano-technologies. The application aspects include, for example, the development of electronic mobile diagnostic facilities, nanorobotic design for a drug delivery inside living cell, and so on. The small NC chain represents an important stage in the understanding of the interaction mechanism of a full DNA or RNA molecule with NP and CNT. In this regard, one has to mention the development of the DNA-CNT devices for the purposes of diagnostic applications in the chemical or drug delivery. Methods: For the NC-NP-CNT system, we have built up a series of the molecular dynamics (MD) models with different NC-NP configurations and performed their MD analysis. The entire system (the NC chain, gold NPs and CNT) was allowed to interact with each other by the only VdW forces. The Lennard-Jones short-ranged interaction was assumed between the NC, NP and CNT. For the CNT a many body Tersoff potential having a quantum-chemistry nature was used. So far, the so-called hybrid MD approach was realized, where the quantum-chemistry potential in combination with a classical trajectory calculation applied . Results: The peculiarities of the NC-NP interaction and bond formation inside of a CNT matrix were investigated along with the structural and dynamical behavior. The correlation effects between the weak Van der Waals (VdW) forces and intramolecular vibrations were enlighten for the molecular system consisting of a small nucleotide chain (NC), gold nanoparticles (NPs) and carbon nanotube (CNT) using molecular dynamics (MD) simulation method. Conclusion: The NC intermolecular motions were estimated from MD data thereby building the distance distributions, the angular and dihedral (torsional) bond energy graphs versus simulation time at different temperatures from T=100 K up to 300 K. The MD simulation

  1. Fundamentals of Space Medicine

    NASA Astrophysics Data System (ADS)

    Clément, Gilles

    2005-03-01

    A total of more than 240 human space flights have been completed to date, involving about 450 astronauts from various countries, for a combined total presence in space of more than 70 years. The seventh long-duration expedition crew is currently in residence aboard the International Space Station, continuing a permanent presence in space that began in October 2000. During that time, investigations have been conducted on both humans and animal models to study the bone demineralization and muscle deconditioning, space motion sickness, the causes and possible treatment of postflight orthostatic intolerance, the changes in immune function, crew and crew-ground interactions, and the medical issues of living in a space environment, such as the effects of radiation or the risk of developing kidney stones. Some results of these investigations have led to fundamental discoveries about the adaptation of the human body to the space environment. Gilles Clément has been active in this research. This readable text presents the findings from the life science experiments conducted during and after space missions. Topics discussed in this book include: adaptation of sensory-motor, cardio-vascular, bone, and muscle systems to the microgravity of spaceflight; psychological and sociological issues of living in a confined, isolated, and stressful environment; operational space medicine, such as crew selection, training and in-flight health monitoring, countermeasures and support; results of space biology experiments on individual cells, plants, and animal models; and the impact of long-duration missions such as the human mission to Mars. The author also provides a detailed description of how to fly a space experiment, based on his own experience with research projects conducted onboard Salyut-7, Mir, Spacelab, and the Space Shuttle. Now is the time to look at the future of human spaceflight and what comes next. The future human exploration of Mars captures the imagination of both the

  2. Fundamentals of Space Medicine

    NASA Astrophysics Data System (ADS)

    Clément, G.

    2003-10-01

    As of today, a total of more than 240 human space flights have been completed, involving about 450 astronauts from various countries, for a combined total presence in space of more than 70 years. The seventh long-duration expedition crew is currently in residence aboard the International Space Station, continuing a permanent presence in space that began in October 2000. During that time, investigations have been conducted on both humans and animal models to study the bone demineralization and muscle deconditioning, space motion sickness, the causes and possible treatment of postflight orthostatic intolerance, the changes in immune function, crew and crew-ground interactions, and the medical issues of living in a space environment, such as the effects of radiation or the risk of developing kidney stones. Some results of these investigations have led to fundamental discoveries about the adaptation of the human body to the space environment. Gilles Clément has been active in this research. This book presents in a readable text the findings from the life science experiments conducted during and after space missions. Topics discussed in this book include: adaptation of sensory-motor, cardiovascular, bone and muscle systems to the microgravity of spaceflight; psychological and sociological issues of living in a confined, isolated and stressful environment; operational space medicine, such as crew selection, training and in-flight health monitoring, countermeasures and support; results of space biology experiments on individual cells, plants, and animal models; and the impact of long-duration missions such as the human mission to Mars. The author also provides a detailed description of how to fly a space experiment, based on his own experience with research projects conducted onboard Salyut-7, Mir, Spacelab, and the Space Shuttle. Now is the time to look at the future of human spaceflight and what comes next. The future human exploration of Mars captures the imagination

  3. Plasma Sail Concept Fundamentals

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Delamere, P.; Kabin, K.; Linde, T. J.

    2004-01-01

    The mini-magnetospheric plasma propulsion (M2P2) device, originally proposed by Winglee et al., predicts that a 15-km standoff distance (or 20-km cross-sectional dimension) of the magnetic bubble will provide for sufficient momentum transfer from the solar wind to accelerate a spacecraft to unprecedented speeds of 50 C80 km/s after an acceleration period of 3 mo. Such velocities will enable travel out of the solar system in period of 7 yr almost an order of magnitude improvement over present chemical-based propulsion systems. However, for the parameters of the simulation of Winglee et al., a fluid model for the interaction of M2P2 with the solar wind is not valid. It is assumed in the magnetohydrodynamic (MHD) fluid model, normally applied to planetary magnetospheres, that the characteristic scale size is much greater than the Larmor radius and ion skin depth of the solar wind. In the case of M2P2, the size of the magnetic bubble is actually less than or comparable to the scale of these characteristic parameters. Therefore, a kinetic approach, which addresses the small-scale physical mechanisms, must be used. A two-component approach to determining a preliminary estimate of the momentum transfer to the plasma sail has been adopted. The first component is a self-consistent MHD simulation of the small-scale expansion phase of the magnetic bubble. The fluid treatment is valid to roughly 5 km from the source and the steady-state MHD solution at the 5 km boundary was then used as initial conditions for the hybrid simulation. The hybrid simulations showed that the forces delivered to the innermost regions of the plasma sail are considerably ( 10 times) smaller than the MHD counterpart, are dominated by the magnetic field pressure gradient, and are directed primarily in the transverse direction.

  4. Air Force Officer Specialty Structure. Reviewing the Fundamentals

    DTIC Science & Technology

    2009-01-01

    the tables of organization to reflect the changes. Major com- mands revised non –table-of- organization documents to reflect the changes. Individual...representation of RAND intellectual property is provided for non -commercial use only. Unauthorized posting of RAND PDFs to a non -RAND Web site is prohibited...research organization providing objective analysis and effective solutions that address the challenges facing the public and private sectors around

  5. Entropic force between biomembranes

    NASA Astrophysics Data System (ADS)

    Li, Long; Song, Fan

    2016-10-01

    Undulation force, an entropic force, stems from thermally excited fluctuations, and plays a key role in the essential interactions between neighboring surfaces of objects. Although the characteristics of the undulation force have been widely studied theoretically and experimentally, the distance dependence of the force, which constitutes its most fundamental characteristic, remains poorly understood. In this paper, first, we obtain a novel expression for the undulation force by employing elasticity and statistical mechanics and prove it to be in good agreement with existing experimental results. Second, we clearly demonstrate that the two representative forms of the undulation force proposed by Helfrich and Freund were respectively the upper and lower bounds of the present expression when the separation between membranes is sufficiently small, which was intrinsically different from the existing results where Helfrich's and Freund's forms of the undulation force were only suitable for the intermediate and small separations. The investigations show that only in a sufficiently small separation does Helfrich's result stand for the undulation force with a large wave number and Freund's result express the force with a small wave number. Finally, a critical acting distance of the undulation force, beyond which the entropic force will rapidly decay approaching zero, is presented.

  6. Liposculpture 4. Fundamentals of good liposculpture technique.

    PubMed

    Fischer, G

    1992-03-01

    The fundamentals for good liposculpture are discussed. Horizontal tunneling is to be avoided because the more horizontally the tunnel is angled, the more likely the overlying skin will drape in folds, resulting in poor cosmesis. Superficial tunneling (less than 1 cm) is to be avoided. The author believes that it is important to maintain the adhesive forces and lymphatics of the superficial layer of fat because it leads to more even healing and remodelling postoperatively. Liposuction within 3 cm of the subgluteal fold should be avoided because it can lead to ptosis of the buttocks postoperatively.

  7. Measurement of Surface Forces

    DTIC Science & Technology

    1990-11-16

    hydration forces were observed in solutions containing chloride salts of Li+ , K+ , Na 4 , and Cs+ , resulting from electrostatic binding of the cation...concentrated solutions of a series of tetraalkylammonium bromide salts [46] [Fig. 13]. In these measurements, the distance of closest approach of the two...solid metal electrodes separated by an electrolytic solution . Electrostatic forces, which are intimately related to electrode kinetics and adsorption

  8. An Evaluation of Fundamental Schools.

    ERIC Educational Resources Information Center

    Weber, Larry J.; And Others

    1984-01-01

    When compared with regular schools in the same district, fundamental school students performed as well as or better than regular school students; fundamental schools rated better on learning climate, discipline, and suspensions; and there were no differences in student self-concept. (Author/BW)

  9. Fundamental mechanisms of micromachine reliability

    SciTech Connect

    DE BOER,MAARTEN P.; SNIEGOWSKI,JEFFRY J.; KNAPP,JAMES A.; REDMOND,JAMES M.; MICHALSKE,TERRY A.; MAYER,THOMAS K.

    2000-01-01

    Due to extreme surface to volume ratios, adhesion and friction are critical properties for reliability of Microelectromechanical Systems (MEMS), but are not well understood. In this LDRD the authors established test structures, metrology and numerical modeling to conduct studies on adhesion and friction in MEMS. They then concentrated on measuring the effect of environment on MEMS adhesion. Polycrystalline silicon (polysilicon) is the primary material of interest in MEMS because of its integrated circuit process compatibility, low stress, high strength and conformal deposition nature. A plethora of useful micromachined device concepts have been demonstrated using Sandia National Laboratories' sophisticated in-house capabilities. One drawback to polysilicon is that in air the surface oxidizes, is high energy and is hydrophilic (i.e., it wets easily). This can lead to catastrophic failure because surface forces can cause MEMS parts that are brought into contact to adhere rather than perform their intended function. A fundamental concern is how environmental constituents such as water will affect adhesion energies in MEMS. The authors first demonstrated an accurate method to measure adhesion as reported in Chapter 1. In Chapter 2 through 5, they then studied the effect of water on adhesion depending on the surface condition (hydrophilic or hydrophobic). As described in Chapter 2, they find that adhesion energy of hydrophilic MEMS surfaces is high and increases exponentially with relative humidity (RH). Surface roughness is the controlling mechanism for this relationship. Adhesion can be reduced by several orders of magnitude by silane coupling agents applied via solution processing. They decrease the surface energy and render the surface hydrophobic (i.e. does not wet easily). However, only a molecular monolayer coats the surface. In Chapters 3-5 the authors map out the extent to which the monolayer reduces adhesion versus RH. They find that adhesion is independent of

  10. Nanofluids mediating surface forces.

    PubMed

    Pilkington, Georgia A; Briscoe, Wuge H

    2012-11-01

    Fluids containing nanostructures, known as nanofluids, are increasingly found in a wide array of applications due to their unique physical properties as compared with their base fluids and larger colloidal suspensions. With several tuneable parameters such as the size, shape and surface chemistry of nanostructures, as well as numerous base fluids available, nanofluids also offer a new paradigm for mediating surface forces. Other properties such as local surface plasmon resonance and size dependent magnetism of nanostructures also present novel mechanisms for imparting tuneable surface interactions. However, our fundamental understanding, experimentally and theoretically, of how these parameters might affect surface forces remains incomplete. Here we review recent results on equilibrium and dynamic surface forces between macroscopic surfaces in nanofluids, highlighting the overriding trends in the correlation between the physical parameters that characterise nanofluids and the surface forces they mediate. We also discuss the challenges that confront existing surface force knowledge as a result of this new paradigm.

  11. Chiral discrimination in optical binding

    NASA Astrophysics Data System (ADS)

    Forbes, Kayn A.; Andrews, David L.

    2015-05-01

    The laser-induced intermolecular force that exists between two or more particles in the presence of an electromagnetic field is commonly termed "optical binding." Distinct from the single-particle forces that are at play in optical trapping at the molecular level, the phenomenon of optical binding is a manifestation of the coupling between optically induced dipole moments in neutral particles. In other, more widely known areas of optics, there are many examples of chiral discrimination—signifying the different response a chiral material has to the handedness of an optical input. In the present analysis, extending previous work on chiral discrimination in optical binding, a mechanism is identified using a quantum electrodynamical approach. It is shown that the optical binding force between a pair of chiral molecules can be significantly discriminatory in nature, depending upon both the handedness of the interacting particles and the polarization of the incident light, and it is typically several orders of magnitude larger than previously reported.

  12. Fundamental principles of particle detectors

    SciTech Connect

    Fernow, R.C.

    1988-01-01

    This paper goes through the fundamental physics of particles-matter interactions which is necessary for the detection of these particles with detectors. A listing of 41 concepts and detector principles are given. 14 refs., 11 figs.

  13. Ablative Thermal Protection System Fundamentals

    NASA Technical Reports Server (NTRS)

    Beck, Robin A. S.

    2013-01-01

    This is the presentation for a short course on the fundamentals of ablative thermal protection systems. It covers the definition of ablation, description of ablative materials, how they work, how to analyze them and how to model them.

  14. Lateral optical binding between two colloidal particles

    PubMed Central

    Wei, Ming-Tzo; Ng, Jack; Chan, C. T.; Ou-Yang, H. Daniel

    2016-01-01

    An optical binding force between two nearby colloidal particles trapped by two coherent laser beams is measured by phase-sensitive detection. The binding force is long-range and spatially oscillatory. For identical linearly-polarized incident beams, the oscillation period is equal to the optical wavelength. For mutually perpendicular polarizations, a new force appears with half-wavelength periodicity, caused by double inter-particle scattering. This force is observable only with cross-polarized incident beams, for which the stronger single-scattering forces are forbidden by parity. PMID:27982052

  15. Binding Procurement

    NASA Technical Reports Server (NTRS)

    Rao, Gopalakrishna M.; Vaidyanathan, Hari

    2007-01-01

    This viewgraph presentation reviews the use of the binding procurement process in purchasing Aerospace Flight Battery Systems. NASA Engineering and Safety Center (NESC) requested NASA Aerospace Flight Battery Systems Working Group to develop a set of guideline requirements document for Binding Procurement Contracts.

  16. Astrophysical probes of fundamental physics

    NASA Astrophysics Data System (ADS)

    Martins, C. J. A. P.

    2009-10-01

    I review the motivation for varying fundamental couplings and discuss how these measurements can be used to constrain fundamental physics scenarios that would otherwise be inaccessible to experiment. I highlight the current controversial evidence for varying couplings and present some new results. Finally I focus on the relation between varying couplings and dark energy, and explain how varying coupling measurements might be used to probe the nature of dark energy, with some advantages over standard methods. In particular I discuss what can be achieved with future spectrographs such as ESPRESSO and CODEX.

  17. Forces in yeast flocculation

    NASA Astrophysics Data System (ADS)

    El-Kirat-Chatel, Sofiane; Beaussart, Audrey; Vincent, Stéphane P.; Abellán Flos, Marta; Hols, Pascal; Lipke, Peter N.; Dufrêne, Yves F.

    2015-01-01

    In the baker's yeast Saccharomyces cerevisiae, cell-cell adhesion (``flocculation'') is conferred by a family of lectin-like proteins known as the flocculin (Flo) proteins. Knowledge of the adhesive and mechanical properties of flocculins is important for understanding the mechanisms of yeast adhesion, and may help controlling yeast behaviour in biotechnology. We use single-molecule and single-cell atomic force microscopy (AFM) to explore the nanoscale forces engaged in yeast flocculation, focusing on the role of Flo1 as a prototype of flocculins. Using AFM tips labelled with mannose, we detect single flocculins on Flo1-expressing cells, showing they are widely exposed on the cell surface. When subjected to force, individual Flo1 proteins display two distinct force responses, i.e. weak lectin binding forces and strong unfolding forces reflecting the force-induced extension of hydrophobic tandem repeats. We demonstrate that cell-cell adhesion bonds also involve multiple weak lectin interactions together with strong unfolding forces, both associated with Flo1 molecules. Single-molecule and single-cell data correlate with microscale cell adhesion behaviour, suggesting strongly that Flo1 mechanics is critical for yeast flocculation. These results favour a model in which not only weak lectin-sugar interactions are involved in yeast flocculation but also strong hydrophobic interactions resulting from protein unfolding.

  18. Fundamental Limits to Nonlinear Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Haji Hosseinloo, Ashkan; Turitsyn, Konstantin

    2015-12-01

    Linear and nonlinear vibration energy harvesting has been the focus of considerable research in recent years. However, fundamental limits on the harvestable energy of a harvester subjected to an arbitrary excitation force and different constraints is not yet fully understood. Understanding these limits is not only essential for an assessment of the technology potential, but it also provides a broader perspective on the current harvesting mechanisms and guidance in their improvement. Here, we derive the fundamental limits on the output power of an ideal energy harvester for arbitrary excitation waveforms and build on the current analysis framework for the simple computation of this limit for more sophisticated setups. We show that the optimal harvester maximizes the harvested energy through a mechanical analog of a buy-low-sell-high strategy. We also propose a nonresonant passive latch-assisted harvester to realize this strategy for an effective harvesting. It is shown that the proposed harvester harvests energy more effectively than its linear and bistable counterparts over a wider range of excitation frequencies and amplitudes. The buy-low-sell-high strategy also reveals why the conventional bistable harvester works well at low-frequency excitation.

  19. Brake Fundamentals. Automotive Articulation Project.

    ERIC Educational Resources Information Center

    Cunningham, Larry; And Others

    Designed for secondary and postsecondary auto mechanics programs, this curriculum guide contains learning exercises in seven areas: (1) brake fundamentals; (2) brake lines, fluid, and hoses; (3) drum brakes; (4) disc brake system and service; (5) master cylinder, power boost, and control valves; (6) parking brakes; and (7) trouble shooting. Each…

  20. Light as a Fundamental Particle

    ERIC Educational Resources Information Center

    Weinberg, Steven

    1975-01-01

    Presents two arguments concerning the role of the photon. One states that the photon is just another particle distinguished by a particular value of charge, spin, mass, lifetime, and interaction properties. The second states that the photon plays a fundamental role with a deep relation to ultimate formulas of physics. (GS)

  1. Environmental Law: Fundamentals for Schools.

    ERIC Educational Resources Information Center

    Day, David R.

    This booklet outlines the environmental problems most likely to arise in schools. An overview provides a fundamental analysis of environmental issues rather than comprehensive analysis and advice. The text examines the concerns that surround superfund cleanups, focusing on the legal framework, and furnishes some practical pointers, such as what to…

  2. Fundamentals of the Slide Library.

    ERIC Educational Resources Information Center

    Boerner, Susan Zee

    This paper is an introduction to the fundamentals of the art (including architecture) slide library, with some emphasis on basic procedures of the science slide library. Information in this paper is particularly relevant to the college, university, and museum slide library. Topics addressed include: (1) history of the slide library; (2) duties of…

  3. Fundamentals of Environmental Education. Report.

    ERIC Educational Resources Information Center

    1976

    An outline of fundamental definitions, relationships, and human responsibilities related to environment provides a basis from which a variety of materials, programs, and activities can be developed. The outline can be used in elementary, secondary, higher education, or adult education programs. The framework is based on principles of the science…

  4. Fundamentals of Welding. Teacher Edition.

    ERIC Educational Resources Information Center

    Fortney, Clarence; And Others

    These instructional materials assist teachers in improving instruction on the fundamentals of welding. The following introductory information is included: use of this publication; competency profile; instructional/task analysis; related academic and workplace skills list; tools, materials, and equipment list; and 27 references. Seven units of…

  5. Fundamentals of Microelectronics Processing (VLSI).

    ERIC Educational Resources Information Center

    Takoudis, Christos G.

    1987-01-01

    Describes a 15-week course in the fundamentals of microelectronics processing in chemical engineering, which emphasizes the use of very large scale integration (VLSI). Provides a listing of the topics covered in the course outline, along with a sample of some of the final projects done by students. (TW)

  6. FUNdamental Movement in Early Childhood.

    ERIC Educational Resources Information Center

    Campbell, Linley

    2001-01-01

    Noting that the development of fundamental movement skills is basic to children's motor development, this booklet provides a guide for early childhood educators in planning movement experiences for children between 4 and 8 years. The booklet introduces a wide variety of appropriate practices to promote movement skill acquisition and increased…

  7. The Fundamental Manifold of Spheroids

    NASA Astrophysics Data System (ADS)

    Zaritsky, Dennis; Gonzalez, Anthony H.; Zabludoff, Ann I.

    2006-02-01

    We present a unifying empirical description of the structural and kinematic properties of all spheroids embedded in dark matter halos. We find that the intracluster stellar spheroidal components of galaxy clusters, which we call cluster spheroids (CSphs) and which are typically 100 times the size of normal elliptical galaxies, lie on a ``fundamental plane'' as tight as that defined by elliptical galaxies (rms in effective radius of ~0.07) but having a different slope. The slope, as measured by the coefficient of the logσ term, declines significantly and systematically between the fundamental planes of ellipticals, brightest cluster galaxies (BCGs), and CSphs. We attribute this decline primarily to a continuous change in Me/Le, the mass-to-light ratio within the effective radius re, with spheroid scale. The magnitude of the slope change requires that it arise principally from differences in the relative distributions of luminous and dark matter, rather than from stellar population differences such as in age and metallicity. By expressing the Me/Le term as a function of σ in the simple derivation of the fundamental plane and requiring the behavior of that term to mimic the observed nonlinear relationship between logMe/Le and logσ, we simultaneously fit a two-dimensional manifold to the measured properties of dwarf elliptical and elliptical galaxies, BCGs, and CSphs. The combined data have an rms scatter in logre of 0.114 (0.099 for the combination of ellipticals, BCGs, and CSphs), which is modestly larger than each fundamental plane has alone, but which includes the scatter introduced by merging different studies done in different filters by different investigators. This ``fundamental manifold'' fits the structural and kinematic properties of spheroids that span a factor of 100 in σ and 1000 in re. While our mathematical form is neither unique nor derived from physical principles, the tightness of the fit leaves little room for improvement by other unification

  8. Force As A Momentum Current

    SciTech Connect

    Munera, Hector A.

    2010-07-28

    Advantages of a neo-Cartesian approach to classical mechanics are noted. If conservation of linear momentum is the fundamental principle, Newton's three laws become theorems. A minor paradox in static Newtonian mechanics is identified, and solved by reinterpreting force as a current of momentum. Contact force plays the role of a mere midwife in the exchange of momentum; however, force cannot be eliminated from physics because it provides the numerical value for momentum current. In this sense, in a neo-Cartesian formulation of mechanics the concept of force becomes strengthened rather than weakened.

  9. Astrophysical Probes of Fundamental Physics

    NASA Astrophysics Data System (ADS)

    Martins, C. J. A. P.

    I review the theoretical motivation for varying fundamental couplings and discuss how these measurements can be used to constrain a number of fundamental physics scenarios that would otherwise be inacessible to experiment. As a case study I will focus on the relation between varying couplings and dark energy, and explain how varying coupling measurements can be used to probe the nature of dark energy, with important advantages over the standard methods. Assuming that the current observational evidence for varying α. and μ is correct, a several-sigma detection of dynamical dark energy is feasible within a few years, using currently operational ground-based facilities. With forthcoming instruments like CODEX, a high-accuracy reconstruction of the equation of state may be possible all the way up to redshift z ˜ 4.

  10. Fundamental neutron physics at LANSCE

    SciTech Connect

    Greene, G.

    1995-10-01

    Modern neutron sources and science share a common origin in mid-20th-century scientific investigations concerned with the study of the fundamental interactions between elementary particles. Since the time of that common origin, neutron science and the study of elementary particles have evolved into quite disparate disciplines. The neutron became recognized as a powerful tool for studying condensed matter with modern neutron sources being primarily used (and justified) as tools for neutron scattering and materials science research. The study of elementary particles has, of course, led to the development of rather different tools and is now dominated by activities performed at extremely high energies. Notwithstanding this trend, the study of fundamental interactions using neutrons has continued and remains a vigorous activity at many contemporary neutron sources. This research, like neutron scattering research, has benefited enormously by the development of modern high-flux neutron facilities. Future sources, particularly high-power spallation sources, offer exciting possibilities for continuing this research.

  11. Microplasmas: from applications to fundamentals

    NASA Astrophysics Data System (ADS)

    Nguon, Olivier; Huang, Sisi; Gauthier, Mario; Karanassios, Vassili

    2014-05-01

    Microplasmas are receiving increasing attention in the scientific literature and in recent conferences. Yet, few analytical applications of microplasmas for elemental analysis using liquid samples have been described in the literature. To address this, we describe two applications: one involves the determination of Zn in microsamples of the metallo-enzyme Super Oxide Dismutase. The other involves determination of Pd-concentration in microsamples of Pd nanocatalysts. These applications demonstrate the potential of microplasmas and point to the need for future fundamental studies.

  12. Quantifying Coulombic and solvent polarization-mediated forces between DNA helices.

    PubMed

    He, Zhaojian; Chen, Shi-Jie

    2013-06-20

    One of the fundamental problems in nucleic acids biophysics is to predict the different forces that stabilize nucleic acid tertiary folds. Here we provide a quantitative estimation and analysis for the forces between DNA helices in an ionic solution. Using the generalized Born model and the improved atomistic tightly binding ions model, we evaluate ion correlation and solvent polarization effects in interhelix interactions. The results suggest that hydration, Coulomb correlation and ion entropy act together to cause the repulsion and attraction between nucleic acid helices in Mg(2+) and Mn(2+) solutions, respectively. The theoretical predictions are consistent with experimental findings. Detailed analysis further suggests that solvent polarization and ion correlation both are crucial for the interhelix interactions. The theory presented here may provide a useful framework for systematic and quantitative predictions of the forces in nucleic acids folding.

  13. Labor Force

    ERIC Educational Resources Information Center

    Occupational Outlook Quarterly, 2012

    2012-01-01

    The labor force is the number of people ages 16 or older who are either working or looking for work. It does not include active-duty military personnel or the institutionalized population, such as prison inmates. Determining the size of the labor force is a way of determining how big the economy can get. The size of the labor force depends on two…

  14. Fundamental molecular differences between alcohol dehydrogenase classes.

    PubMed Central

    Danielsson, O; Atrian, S; Luque, T; Hjelmqvist, L; Gonzàlez-Duarte, R; Jörnvall, H

    1994-01-01

    Two types of alcohol dehydrogenase in separate protein families are the "medium-chain" zinc enzymes (including the classical liver and yeast forms) and the "short-chain" enzymes (including the insect form). Although the medium-chain family has been characterized in prokaryotes and many eukaryotes (fungi, plants, cephalopods, and vertebrates), insects have seemed to possess only the short-chain enzyme. We have now also characterized a medium-chain alcohol dehydrogenase in Drosophila. The enzyme is identical to insect octanol dehydrogenase. It is a typical class III alcohol dehydrogenase, similar to the corresponding human form (70% residue identity), with mostly the same residues involved in substrate and coenzyme interactions. Changes that do occur are conservative, but Phe-51 is of functional interest in relation to decreased coenzyme binding and increased overall activity. Extra residues versus the human enzyme near position 250 affect the coenzyme-binding domain. Enzymatic properties are similar--i.e., very low activity toward ethanol (Km beyond measurement) and high selectivity for formaldehyde/glutathione (S-hydroxymethylglutathione; kcat/Km = 160,000 min-1.mM-1). Between the present class III and the ethanol-active class I enzymes, however, patterns of variability differ greatly, highlighting fundamentally separate molecular properties of these two alcohol dehydrogenases, with class III resembling enzymes in general and class I showing high variation. The gene coding for the Drosophila class III enzyme produces an mRNA of about 1.36 kb that is present at all developmental stages of the fly, compatible with the constitutive nature of the vertebrate enzyme. Taken together, the results bridge a previously apparent gap in the distribution of medium-chain alcohol dehydrogenases and establish a strictly conserved class III enzyme, consistent with an important role for this enzyme in cellular metabolism. Images PMID:8197167

  15. Thermodynamics fundamentals of energy conversion

    NASA Astrophysics Data System (ADS)

    Dan, Nicolae

    The work reported in the chapters 1-5 focuses on the fundamentals of heat transfer, fluid dynamics, thermodynamics and electrical phenomena related to the conversion of one form of energy to another. Chapter 6 is a re-examination of the fundamental heat transfer problem of how to connect a finite-size heat generating volume to a concentrated sink. Chapter 1 extends to electrical machines the combined thermodynamics and heat transfer optimization approach that has been developed for heat engines. The conversion efficiency at maximum power is 1/2. When, as in specific applications, the operating temperature of windings must not exceed a specified level, the power output is lower and efficiency higher. Chapter 2 addresses the fundamental problem of determining the optimal history (regime of operation) of a battery so that the work output is maximum. Chapters 3 and 4 report the energy conversion aspects of an expanding mixture of hot particles, steam and liquid water. At the elemental level, steam annuli develop around the spherical drops as time increases. At the mixture level, the density decreases while the pressure and velocity increases. Chapter 4 describes numerically, based on the finite element method, the time evolution of the expanding mixture of hot spherical particles, steam and water. The fluid particles are moved in time in a Lagrangian manner to simulate the change of the domain configuration. Chapter 5 describes the process of thermal interaction between the molten material and water. In the second part of the chapter the model accounts for the irreversibility due to the flow of the mixture through the cracks of the mixing vessel. The approach presented in this chapter is based on exergy analysis and represents a departure from the line of inquiry that was followed in chapters 3-4. Chapter 6 shows that the geometry of the heat flow path between a volume and one point can be optimized in two fundamentally different ways. In the "growth" method the

  16. Fundamental Characteristics of Breather Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Chabchoub, Amin

    2014-05-01

    The formation of oceanic rogue waves can be explained by the modulation instability of deep-water Stokes waves. In particular, being doubly-localized and amplifying the background wave amplitude by a factor of three or higher, the class of Peregrine-type breather solutions of the nonlinear Schrödinger equation (NLS) are considered to be appropriate models to describe extreme ocean wave dynamics. Here, we present an experimental validation of fundamental properties of the NLS within the context of Peregrine breather dynamics and we discuss the long-term behavior of such in time and space localized structures.

  17. Reconstruction of fundamental SUSY parameters

    SciTech Connect

    P. M. Zerwas et al.

    2003-09-25

    We summarize methods and expected accuracies in determining the basic low-energy SUSY parameters from experiments at future e{sup +}e{sup -} linear colliders in the TeV energy range, combined with results from LHC. In a second step we demonstrate how, based on this set of parameters, the fundamental supersymmetric theory can be reconstructed at high scales near the grand unification or Planck scale. These analyses have been carried out for minimal supergravity [confronted with GMSB for comparison], and for a string effective theory.

  18. Solid Lubrication Fundamentals and Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2001-01-01

    Solid Lubrication Fundamentals and Applications description of the adhesion, friction, abrasion, and wear behavior of solid film lubricants and related tribological materials, including diamond and diamond-like solid films. The book details the properties of solid surfaces, clean surfaces, and contaminated surfaces as well as discussing the structures and mechanical properties of natural and synthetic diamonds; chemical-vapor-deposited diamond film; surface design and engineering toward wear-resistant, self-lubricating diamond films and coatings. The author provides selection and design criteria as well as applications for synthetic and natural coatings in the commercial, industrial and aerospace industries..

  19. Interpreting the widespread nonlinear force spectra of intermolecular bonds

    PubMed Central

    Friddle, Raymond W.; Noy, Aleksandr; De Yoreo, James J.

    2012-01-01

    Single molecule force spectroscopy probes the strength, lifetime, and energetic details of intermolecular interactions in a simple experiment. A growing number of these studies have reported distinctly nonlinear trends in rupture force with loading rate that are typically explained in conventional models by invoking complex escape pathways. Recent analyses suggested that these trends should be expected even for simple barriers based on the basic assumptions of bond rupture dynamics and thus may represent the norm rather than the exception. Here we explore how these nonlinear trends reflect the two fundamental regimes of bond rupture: (i) a near-equilibrium regime, produced either by bond reforming in the case of a single bond or by asynchronized rupture of multiple individual bonds, and (ii) a kinetic regime produced by fast, non-equilibrium bond rupture. We analyze both single- and multi-bonded cases, describe the full evolution of the system as it transitions between near- and far-from-equilibrium loading regimes, and show that both interpretations produce essentially identical force spectra. Data from 10 different molecular systems show that this model provides a comprehensive description of force spectra for a diverse suite of bonds over experimentally relevant loading rates, removes the inconsistencies of previous interpretations of transition state distances, and gives ready access to both kinetic and thermodynamic information about the interaction. These results imply that single-molecule binding free energies for a vast number of bonds have already been measured. PMID:22869712

  20. [From fundamental research to clinical development: a review of orthodontics].

    PubMed

    Zhao, Zhi-he; Bai, Ding

    2011-11-01

    In recent years, new approaches to the diagnosis and treatment of malocclusion have emerged. The diagnostic and therapeutic techniques of orthodontics have evolved from two dimensions to five dimensions with the development of computer technology, auto-machining and imaging. Furthermore, interdisciplinary study has become the driving force for the advancement of fundamental research in orthodontics. The mechanisms of malocclusion and orthodontic tooth movement have been extensively studied to the details at the level of cells and molecules.

  1. Fundamental tribological properties of ceramics

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.; Miyoshi, K.

    1985-01-01

    When a ceramic is brought into contact with itself, another ceramic, or a metal, strong bond forces can develop between the materials. Adhesion between a ceramic and itself or another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to the interface resulting from solid state contact. Elastic, plastic, and fracture behavior of ceramics in solid-state contact are discussed as they relate to friction and wear. The contact load necessary to initiate fracture in ceramics is shown to be appreciably reduced with tangential motion. Both friction and wear of ceramics are anisotropic and relate to crystal structure as with metals. Both free energy of oxide formation and the d valence bond character of metals are related to the friction and wear characteristics for metals in contact with ceramics. Lubrication is found to increase the critical load necessary to initiate fracture of ceramics with sliding or rubbing contact.

  2. Field Theory of Fundamental Interactions

    NASA Astrophysics Data System (ADS)

    Wang, Shouhong; Ma, Tian

    2017-01-01

    First, we present two basic principles, the principle of interaction dynamics (PID) and the principle of representation invariance (PRI). Intuitively, PID takes the variation of the action under energy-momentum conservation constraint. We show that the PID is the requirement of the presence of dark matter and dark energy, the Higgs field and the quark confinement. PRI requires that the SU(N) gauge theory be independent of representations of SU(N). It is clear that PRI is the logic requirement of any gauge theory. With PRI, we demonstrate that the coupling constants for the strong and the weak interactions are the main sources of these two interactions, reminiscent of the electric charge. Second, we emphasize that symmetry principles-the principle of general relativity and the principle of Lorentz invariance and gauge invariance-together with the simplicity of laws of nature, dictate the actions for the four fundamental interactions. Finally, we show that the PID and the PRI, together with the symmetry principles give rise to a unified field model for the fundamental interactions, which is consistent with current experimental observations and offers some new physical predictions. The research is supported in part by the National Science Foundation (NSF) grant DMS-1515024, and by the Office of Naval Research (ONR) grant N00014-15-1-2662.

  3. Force cycles and force chains.

    PubMed

    Tordesillas, Antoinette; Walker, David M; Lin, Qun

    2010-01-01

    We examine the coevolution of N cycles and force chains as part of a broader study which is designed to quantitatively characterize the role of the laterally supporting contact network to the evolution of force chains. Here, we elucidate the rheological function of these coexisting structures, especially in the lead up to failure. In analogy to force chains, we introduce the concept of force cycles: N cycles whose contacts each bear above average force. We examine their evolution around force chains in a discrete element simulation of a dense granular material under quasistatic biaxial loading. Three-force cycles are shown to be stabilizing structures that inhibit relative particle rotations and provide strong lateral support to force chains. These exhibit distinct behavior from other cycles. Their population decreases rapidly during the initial stages of the strain-hardening regime-a trend that is suddenly interrupted and reversed upon commencement of force chain buckling prior to peak shear stress. Results suggest that the three-force cycles are called upon for reinforcements to ward off failure via shear banding. Ultimately though, the resistance to buckling proves futile; buckling wins under the combined effects of dilatation and increasing compressive load. The sudden increase in three-force cycles may thus be viewed as an indicator of imminent failure via shear bands.

  4. How vinculin regulates force transmission.

    PubMed

    Dumbauld, David W; Lee, Ted T; Singh, Ankur; Scrimgeour, Jan; Gersbach, Charles A; Zamir, Evan A; Fu, Jianping; Chen, Christopher S; Curtis, Jennifer E; Craig, Susan W; García, Andrés J

    2013-06-11

    Focal adhesions mediate force transfer between ECM-integrin complexes and the cytoskeleton. Although vinculin has been implicated in force transmission, few direct measurements have been made, and there is little mechanistic insight. Using vinculin-null cells expressing vinculin mutants, we demonstrate that vinculin is not required for transmission of adhesive and traction forces but is necessary for myosin contractility-dependent adhesion strength and traction force and for the coupling of cell area and traction force. Adhesion strength and traction forces depend differentially on vinculin head (V(H)) and tail domains. V(H) enhances adhesion strength by increasing ECM-bound integrin-talin complexes, independently from interactions with vinculin tail ligands and contractility. A full-length, autoinhibition-deficient mutant (T12) increases adhesion strength compared with VH, implying roles for both vinculin activation and the actin-binding tail. In contrast to adhesion strength, vinculin-dependent traction forces absolutely require a full-length and activated molecule; V(H) has no effect. Physical linkage of the head and tail domains is required for maximal force responses. Residence times of vinculin in focal adhesions, but not T12 or V(H), correlate with applied force, supporting a mechanosensitive model for vinculin activation in which forces stabilize vinculin's active conformation to promote force transfer.

  5. Quantum repeaters: fundamental and future

    NASA Astrophysics Data System (ADS)

    Li, Yue; Hua, Sha; Liu, Yu; Ye, Jun; Zhou, Quan

    2007-04-01

    An overview of the Quantum Repeater techniques based on Entanglement Distillation and Swapping is provided. Beginning with a brief history and the basic concepts of the quantum repeaters, the article primarily focuses on the communication model based on the quantum repeater techniques, which mainly consists of two fundamental modules --- the Entanglement Distillation module and the Swapping module. The realizations of Entanglement Distillation are discussed, including the Bernstein's Procrustean method, the Entanglement Concentration and the CNOT-purification method, etc. The schemes of implementing Swapping, which include the Swapping based on Bell-state measurement and the Swapping in Cavity QED, are also introduced. Then a comparison between these realizations and evaluations on them are presented. At last, the article discusses the experimental schemes of quantum repeaters at present, documents some remaining problems and emerging trends in this field.

  6. Astronomical reach of fundamental physics

    NASA Astrophysics Data System (ADS)

    Burrows, Adam S.; Ostriker, Jeremiah P.

    2014-02-01

    Using basic physical arguments, we derive by dimensional and physical analysis the characteristic masses and sizes of important objects in the universe in terms of just a few fundamental constants. This exercise illustrates the unifying power of physics and the profound connections between the small and the large in the cosmos we inhabit. We focus on the minimum and maximum masses of normal stars, the corresponding quantities for neutron stars, the maximum mass of a rocky planet, the maximum mass of a white dwarf, and the mass of a typical galaxy. To zeroth order, we show that all these masses can be expressed in terms of either the Planck mass or the Chandrasekar mass, in combination with various dimensionless quantities. With these examples, we expose the deep interrelationships imposed by nature between disparate realms of the universe and the amazing consequences of the unifying character of physical law.

  7. Astronomical reach of fundamental physics.

    PubMed

    Burrows, Adam S; Ostriker, Jeremiah P

    2014-02-18

    Using basic physical arguments, we derive by dimensional and physical analysis the characteristic masses and sizes of important objects in the universe in terms of just a few fundamental constants. This exercise illustrates the unifying power of physics and the profound connections between the small and the large in the cosmos we inhabit. We focus on the minimum and maximum masses of normal stars, the corresponding quantities for neutron stars, the maximum mass of a rocky planet, the maximum mass of a white dwarf, and the mass of a typical galaxy. To zeroth order, we show that all these masses can be expressed in terms of either the Planck mass or the Chandrasekar mass, in combination with various dimensionless quantities. With these examples, we expose the deep interrelationships imposed by nature between disparate realms of the universe and the amazing consequences of the unifying character of physical law.

  8. Fundamentals of Condensed Matter Physics

    NASA Astrophysics Data System (ADS)

    Cohen, Marvin L.; Louie, Steven G.

    2016-05-01

    Part I. Basic Concepts: Electrons and Phonons: 1. Concept of a solid: qualitative introduction and overview; 2. Electrons in crystals; 3. Electronic energy bands; 4. Lattice vibrations and phonons; Part II. Electron Intercations, Dynamics and Responses: 5. Electron dynamics in crystals; 6. Many-electron interactions: the interacting electron gas and beyond; 7. Density functional theory; 8. The dielectric function for solids; Part III. Optical and Transport Phenomena: 9. Electronic transitions and optical properties of solids; 10. Electron-phonon interactions; 11. Dynamics of crystal electrons in a magnetic field; 12. Fundamentals of transport phenomena in solids; Part IV. Superconductivity, Magnetism, and Lower Dimensional Systems: 13. Using many-body techniques; 14. Superconductivity; 15. Magnetism; 16. Reduced-dimensional systems and nanostructures; Index.

  9. Fundamentals of Acoustic Backscatter Imagery

    DTIC Science & Technology

    2011-09-20

    pressure, I,, of 1 /iPa, corresponds to 0.67 x 10- 8 Wim2. Assuming spherical spreading, the one meter distance reference frame, and the definition of dB (Eq...then be approximated by an infinite series Fundamentals ofAcoustic Backscatter Imagery 11 W(r) = Wm (r) + X Fjsc (r) j=O where "tic(r) is the incident...f( x ,y, Z)Iz=h(xy) = 0 f( x , y, z)I z=h( x ,y)= f( x , y, Z) I z o + h di+ h 2 d2f +zz z= The function ftx,y,z) can represent, for example, the stress

  10. Fundamental Travel Demand Model Example

    NASA Technical Reports Server (NTRS)

    Hanssen, Joel

    2010-01-01

    Instances of transportation models are abundant and detailed "how to" instruction is available in the form of transportation software help documentation. The purpose of this paper is to look at the fundamental inputs required to build a transportation model by developing an example passenger travel demand model. The example model reduces the scale to a manageable size for the purpose of illustrating the data collection and analysis required before the first step of the model begins. This aspect of the model development would not reasonably be discussed in software help documentation (it is assumed the model developer comes prepared). Recommendations are derived from the example passenger travel demand model to suggest future work regarding the data collection and analysis required for a freight travel demand model.

  11. Fundamental concepts of quantum chaos

    NASA Astrophysics Data System (ADS)

    Robnik, M.

    2016-09-01

    We review the fundamental concepts of quantum chaos in Hamiltonian systems. The quantum evolution of bound systems does not possess the sensitive dependence on initial conditions, and thus no chaotic behaviour occurs, whereas the study of the stationary solutions of the Schrödinger equation in the quantum phase space (Wigner functions) reveals precise analogy of the structure of the classical phase portrait. We analyze the regular eigenstates associated with invariant tori in the classical phase space, and the chaotic eigenstates associated with the classically chaotic regions, and the corresponding energy spectra. The effects of quantum localization of the chaotic eigenstates are treated phenomenologically, resulting in Brody-like level statistics, which can be found also at very high-lying levels, while the coupling between the regular and the irregular eigenstates due to tunneling, and of the corresponding levels, manifests itself only in low-lying levels.

  12. Cognition is … Fundamentally Cultural

    PubMed Central

    Bender, Andrea; Beller, Sieghard

    2013-01-01

    A prevailing concept of cognition in psychology is inspired by the computer metaphor. Its focus on mental states that are generated and altered by information input, processing, storage and transmission invites a disregard for the cultural dimension of cognition, based on three (implicit) assumptions: cognition is internal, processing can be distinguished from content, and processing is independent of cultural background. Arguing against each of these assumptions, we point out how culture may affect cognitive processes in various ways, drawing on instances from numerical cognition, ethnobiological reasoning, and theory of mind. Given the pervasive cultural modulation of cognition—on all of Marr’s levels of description—we conclude that cognition is indeed fundamentally cultural, and that consideration of its cultural dimension is essential for a comprehensive understanding. PMID:25379225

  13. Fundamental reaction pathways during coprocessing

    SciTech Connect

    Stock, L.M.; Gatsis, J.G. . Dept. of Chemistry)

    1992-12-01

    The objective of this research was to investigate the fundamental reaction pathways in coal petroleum residuum coprocessing. Once the reaction pathways are defined, further efforts can be directed at improving those aspects of the chemistry of coprocessing that are responsible for the desired results such as high oil yields, low dihydrogen consumption, and mild reaction conditions. We decided to carry out this investigation by looking at four basic aspects of coprocessing: (1) the effect of fossil fuel materials on promoting reactions essential to coprocessing such as hydrogen atom transfer, carbon-carbon bond scission, and hydrodemethylation; (2) the effect of varied mild conditions on the coprocessing reactions; (3) determination of dihydrogen uptake and utilization under severe conditions as a function of the coal or petroleum residuum employed; and (4) the effect of varied dihydrogen pressure, temperature, and residence time on the uptake and utilization of dihydrogen and on the distribution of the coprocessed products. Accomplishments are described.

  14. Astronomical reach of fundamental physics

    PubMed Central

    Burrows, Adam S.; Ostriker, Jeremiah P.

    2014-01-01

    Using basic physical arguments, we derive by dimensional and physical analysis the characteristic masses and sizes of important objects in the universe in terms of just a few fundamental constants. This exercise illustrates the unifying power of physics and the profound connections between the small and the large in the cosmos we inhabit. We focus on the minimum and maximum masses of normal stars, the corresponding quantities for neutron stars, the maximum mass of a rocky planet, the maximum mass of a white dwarf, and the mass of a typical galaxy. To zeroth order, we show that all these masses can be expressed in terms of either the Planck mass or the Chandrasekar mass, in combination with various dimensionless quantities. With these examples, we expose the deep interrelationships imposed by nature between disparate realms of the universe and the amazing consequences of the unifying character of physical law. PMID:24477692

  15. Ultra-fast optical manipulation of single proteins binding to the actin cytoskeleton

    NASA Astrophysics Data System (ADS)

    Capitanio, Marco; Gardini, Lucia; Pavone, Francesco Saverio

    2014-02-01

    In the last decade, forces and mechanical stresses acting on biological systems are emerging as regulatory factors essential for cell life. Emerging evidences indicate that factors such as applied forces or the rigidity of the extracellular matrix (ECM) determine the shape and function of cells and organisms1. Classically, the regulation of biological systems is described through a series of biochemical signals and enzymatic reactions, which direct the processes and cell fate. However, mechanotransduction, i.e. the conversion of mechanical forces into biochemical and biomolecular signals, is at the basis of many biological processes fundamental for the development and differentiation of cells, for their correct function and for the development of pathologies. We recently developed an in vitro system that allows the investigation of force-dependence of the interaction of proteins binding the actin cytoskeleton, at the single molecule level. Our system displays a delay of only ~10 μs between formation of the molecular bond and application of the force and is capable of detecting interactions as short as 100 μs. Our assay allows direct measurements of load-dependence of lifetimes of single molecular bonds and conformational changes of single proteins and molecular motors. We demonstrate our technique on molecular motors, using myosin II from fast skeletal muscle and on protein-DNA interaction, specifically on Lactose repressor (LacI). The apparatus is stabilized to less than 1 nm with both passive and active stabilization, allowing resolving specific binding regions along the actin filament and DNA molecule. Our technique extends single-molecule force-clamp spectroscopy to molecular complexes that have been inaccessible up to now, opening new perspectives for the investigation of the effects of forces on biological processes.

  16. Rare Isotopes and Fundamental Symmetries

    NASA Astrophysics Data System (ADS)

    Brown, B. Alex; Engel, Jonathan; Haxton, Wick; Ramsey-Musolf, Michael; Romalis, Michael; Savard, Guy

    2009-01-01

    Experiments searching for new interactions in nuclear beta decay / Klaus P. Jungmann -- The beta-neutrino correlation in sodium-21 and other nuclei / P. A. Vetter ... [et al.] -- Nuclear structure and fundamental symmetries/ B. Alex Brown -- Schiff moments and nuclear structure / J. Engel -- Superallowed nuclear beta decay: recent results and their impact on V[symbol] / J. C. Hardy and I. S. Towner -- New calculation of the isospin-symmetry breaking correlation to superallowed Fermi beta decay / I. S. Towner and J. C. Hardy -- Precise measurement of the [symbol]H to [symbol]He mass difference / D. E. Pinegar ... [et al.] -- Limits on scalar currents from the 0+ to 0+ decay of [symbol]Ar and isospin breaking in [symbol]Cl and [symbol]Cl / A. Garcia -- Nuclear constraints on the weak nucleon-nucleon interaction / W. C. Haxton -- Atomic PNC theory: current status and future prospects / M. S. Safronova -- Parity-violating nucleon-nucleon interactions: what can we learn from nuclear anapole moments? / B. Desplanques -- Proposed experiment for the measurement of the anapole moment in francium / A. Perez Galvan ... [et al.] -- The Radon-EDM experiment / Tim Chupp for the Radon-EDM collaboration -- The lead radius Eexperiment (PREX) and parity violating measurements of neutron densities / C. J. Horowitz -- Nuclear structure aspects of Schiff moment and search for collective enhancements / Naftali Auerbach and Vladimir Zelevinsky -- The interpretation of atomic electric dipole moments: Schiff theorem and its corrections / C. -P. Liu -- T-violation and the search for a permanent electric dipole moment of the mercury atom / M. D. Swallows ... [et al.] -- The new concept for FRIB and its potential for fundamental interactions studies / Guy Savard -- Collinear laser spectroscopy and polarized exotic nuclei at NSCL / K. Minamisono -- Environmental dependence of masses and coupling constants / M. Pospelov.

  17. Fundamental enabling issues in nanotechnology :

    SciTech Connect

    Floro, Jerrold Anthony; Foiles, Stephen Martin; Hearne, Sean Joseph; Hoyt, Jeffrey John; Seel, Steven Craig; Webb III, Edmund Blackburn; Morales, Alfredo Martin; Zimmerman, Jonathan A.

    2007-10-01

    To effectively integrate nanotechnology into functional devices, fundamental aspects of material behavior at the nanometer scale must be understood. Stresses generated during thin film growth strongly influence component lifetime and performance; stress has also been proposed as a mechanism for stabilizing supported nanoscale structures. Yet the intrinsic connections between the evolving morphology of supported nanostructures and stress generation are still a matter of debate. This report presents results from a combined experiment and modeling approach to study stress evolution during thin film growth. Fully atomistic simulations are presented predicting stress generation mechanisms and magnitudes during all growth stages, from island nucleation to coalescence and film thickening. Simulations are validated by electrodeposition growth experiments, which establish the dependence of microstructure and growth stresses on process conditions and deposition geometry. Sandia is one of the few facilities with the resources to combine experiments and modeling/theory in this close a fashion. Experiments predicted an ongoing coalescence process that generates signficant tensile stress. Data from deposition experiments also supports the existence of a kinetically limited compressive stress generation mechanism. Atomistic simulations explored island coalescence and deposition onto surfaces intersected by grain boundary structures to permit investigation of stress evolution during later growth stages, e.g. continual island coalescence and adatom incorporation into grain boundaries. The predictive capabilities of simulation permit direct determination of fundamental processes active in stress generation at the nanometer scale while connecting those processes, via new theory, to continuum models for much larger island and film structures. Our combined experiment and simulation results reveal the necessary materials science to tailor stress, and therefore performance, in

  18. Fundamental Physics and Precision Measurements

    NASA Astrophysics Data System (ADS)

    Hänsch, T. W.

    2006-11-01

    "Very high precision physics has always appealed to me. The steady improvement in technologies that afford higher and higher precision has been a regular source of excitement and challenge during my career. In science, as in most things, whenever one looks at something more closely, new aspects almost always come into play …" With these word from the book "How the Laser happened", Charles H. Townes expresses a passion for precision that is now shared by many scientists. Masers and lasers have become indispensible tools for precision measurements. During the past few years, the advent of femtosecond laser frequency comb synthesizers has revolutionized the art of directly comparing optical and microwave frequencies. Inspired by the needs of precision laser spectroscopy of the simple hydrogen atom, such frequency combs are now enabling ultra-precise spectroscopy over wide spectral ranges. Recent laboratory experiments are already setting stringent limits for possible slow variations of fundamental constants. Laser frequency combs also provide the long missing clockwork for optical atomic clocks that may ultimately reach a precision of parts in 1018 and beyond. Such tools will open intriguing new opportunities for fundamental experiments including new tests of special and general relativity. In the future, frequency comb techniques may be extended into the extreme ultraviolet and soft xray regime, opening a vast new spectral territory to precision measurements. Frequency combs have also become a key tool for the emerging new field of attosecond science, since they can control the electric field of ultrashort laser pulses on an unprecedented time scale. The biggest surprise in these endeavours would be if we found no surprise.

  19. From self-assembly fundamental knowledge to nanomedicine developments.

    PubMed

    Monduzzi, Maura; Lampis, Sandrina; Murgia, Sergio; Salis, Andrea

    2014-03-01

    This review highlights the key role of NMR techniques in demonstrating the molecular aspects of the self-assembly of surfactant molecules that nowadays constitute the basic knowledge which modern nanoscience relies on. The aim is to provide a tutorial overview. The story of a rigorous scientific approach to understand self-assembly in surfactant systems and biological membranes starts in the early seventies when the progresses of SAXRD and NMR technological facilities allowed to demonstrate the existence of ordered soft matter, and the validity of Tanford approach concerning self-assembly at a molecular level. Particularly, NMR quadrupolar splittings, NMR chemical shift anisotropy, and NMR relaxation of dipolar and quadrupolar nuclei in micellar solutions, microemulsions, and liquid crystals proved the existence of an ordered polar-apolar interface, on the NMR time scale. NMR data, rationalized in terms of the two-step model of relaxation, allowed to quantify the dynamic aspects of the supramolecular aggregates in different soft matter systems. In addition, NMR techniques allowed to obtain important information on counterion binding as well as on size of the aggregate through molecular self-diffusion. Indeed NMR self-diffusion proved without any doubt the existence of bicontinuous microemulsions and bicontinuous cubic liquid crystals, suggested by pioneering and brilliant interpretation of SAXRD investigations. Moreover, NMR self-diffusion played a fundamental role in the understanding of microemulsion and emulsion nanostructures, phase transitions in phase diagrams, and particularly percolation phenomena in microemulsions. Since the nineties, globalization of the knowledge along with many other technical facilities such as electron microscopy, particularly cryo-EM, produced huge progresses in surfactant and colloid science. Actually we refer to nanoscience: bottom up/top down strategies allow to build nanodevices with applications spanning from ICT to food

  20. Natural convection: Fundamentals and applications

    NASA Astrophysics Data System (ADS)

    Kakac, S.; Aung, W.; Viskanta, R.

    Among the topics discussed are: stability solutions for laminar external boundary region flows; natural convection in plane layers and cavities with volumetric energy sources; and turbulence modelling equations. Consideration is also given to: natural convection in enclosures containing tube bundles; natural limiting behaviors in porous media cavity flows; numerical solutions in laminar and turbulent natural convection; and heat transfer in the critical region of binary mixtures. Additional topics discussed include: natural convective cooling of electronic equipment; natural convection suppression in solar collectors; and laser induced buoyancy and forced convection in vertical tubes.

  1. Was Fundamental Education Another Form Of Colonialism?

    NASA Astrophysics Data System (ADS)

    Watras, Joseph

    2007-01-01

    A description of the work of Pedro Tamesis Orata provides an opportunity to investigate the conflicts that can occur when educators seek to reduce poverty while trying to respect indigenous cultures. A native of the Philippines, Orata completed his doctoral studies at the Ohio State University in 1927. During US President Franklin Roosevelt's New Deal, he accepted the position of school principal for the US Bureau of Indian Affairs. After World War II, he directed the spread of fundamental education through the United Nations Educational, Scientific and Cultural Organization (UNESCO). In his final years, he returned to the Philippines where he began a movement to spread what were called self-help high schools. In these activities, Orata taught people to follow John Dewey's five steps of thinking while working to improve their standards of living. In the 1970s, educators, such as Paulo Freire, complained that problem-solving methods, similar to those Orata favored, reinforced the oppressive aspects of formerly colonial societies. While Freire may have been overly critical, conflicts among cultural orientations appear to be unavoidable. The hope behind this investigation is that the difficulties can be reduced when people understand the different forces that persist.

  2. Space-Based Research in Fundamental Physics and Quantum Technologies

    NASA Astrophysics Data System (ADS)

    Turyshev, Slava G.; Israelsson, Ulf E.; Shao, Michael; Yu, Nan; Kusenko, Alexander; Wright, Edward L.; Everitt, C. W. Francis; Kasevich, Mark; Lipa, John A.; Mester, John C.; Reasenberg, Robert D.; Walsworth, Ronald L.; Ashby, Neil; Gould, Harvey; Paik, Ho Jung

    Space offers unique experimental conditions and a wide range of opportunities to explore the foundations of modern physics with an accuracy far beyond that of ground-based experiments. Space-based experiments today can uniquely address important questions related to the fundamental laws of Nature. In particular, high-accuracy physics experiments in space can test relativistic gravity and probe the physics beyond the Standard Model; they can perform direct detection of gravitational waves and are naturally suited for investigations in precision cosmology and astroparticle physics. In addition, atomic physics has recently shown substantial progress in the development of optical clocks and atom interferometers. If placed in space, these instruments could turn into powerful high-resolution quantum sensors greatly benefiting fundamental physics. We discuss the current status of space-based research in fundamental physics, its discovery potential, and its importance for modern science. We offer a set of recommendations to be considered by the upcoming National Academy of Sciences' Decadal Survey in Astronomy and Astrophysics. In our opinion, the Decadal Survey should include space-based research in fundamental physics as one of its focus areas. We recommend establishing an Astronomy and Astrophysics Advisory Committee's interagency "Fundamental Physics Task Force" to assess the status of both ground- and space-based efforts in the field, to identify the most important objectives, and to suggest the best ways to organize the work of several federal agencies involved. We also recommend establishing a new NASA-led interagency program in fundamental physics that will consolidate new technologies, prepare key instruments for future space missions, and build a strong scientific and engineering community. Our goal is to expand NASA's science objectives in space by including "laboratory research in fundamental physics" as an element in the agency's ongoing space research efforts.

  3. Labor Force

    ERIC Educational Resources Information Center

    Occupational Outlook Quarterly, 2010

    2010-01-01

    The labor force is the number of people aged 16 or older who are either working or looking for work. It does not include active-duty military personnel or institutionalized people, such as prison inmates. Quantifying this total supply of labor is a way of determining how big the economy can get. Labor force participation rates vary significantly…

  4. How Do Fundamental Christians Deal with Depression?

    ERIC Educational Resources Information Center

    Spinney, Douglas Harvey

    1991-01-01

    Provides explanation of developmental dynamics in experience of fundamental Christians that provoke reactive depression. Describes depressant retardant defenses against depression that have been observed in Christian fundamental subculture. Suggests four counseling strategies for helping fundamentalists. (Author/ABL)

  5. Fundamentals and Techniques of Nonimaging

    SciTech Connect

    O'Gallagher, J. J.; Winston, R.

    2003-07-10

    This is the final report describing a long term basic research program in nonimaging optics that has led to major advances in important areas, including solar energy, fiber optics, illumination techniques, light detectors, and a great many other applications. The term ''nonimaging optics'' refers to the optics of extended sources in systems for which image forming is not important, but effective and efficient collection, concentration, transport, and distribution of light energy is. Although some of the most widely known developments of the early concepts have been in the field of solar energy, a broad variety of other uses have emerged. Most important, under the auspices of this program in fundamental research in nonimaging optics established at the University of Chicago with support from the Office of Basic Energy Sciences at the Department of Energy, the field has become very dynamic, with new ideas and concepts continuing to develop, while applications of the early concepts continue to be pursued. While the subject began as part of classical geometrical optics, it has been extended subsequently to the wave optics domain. Particularly relevant to potential new research directions are recent developments in the formalism of statistical and wave optics, which may be important in understanding energy transport on the nanoscale. Nonimaging optics permits the design of optical systems that achieve the maximum possible concentration allowed by physical conservation laws. The earliest designs were constructed by optimizing the collection of the extreme rays from a source to the desired target: the so-called ''edge-ray'' principle. Later, new concentrator types were generated by placing reflectors along the flow lines of the ''vector flux'' emanating from lambertian emitters in various geometries. A few years ago, a new development occurred with the discovery that making the design edge-ray a functional of some other system parameter permits the construction of whole

  6. Future Fundamental Combustion Research for Aeropropulsion Systems.

    DTIC Science & Technology

    1985-01-01

    AD-MISS 771 FUTURE FUNDAMENTAL COMBUSTION RESEARCH FOR I AEROPROPULSION SYSTEMS(U) NATIONAL AERONAUTICS AND I SPACE ADMINISTRATION CLEVELAND OH LEWIS... Future Fundamental Combustion Research for Aeropropulsion Systems u. Edward J. Mularz V Propulsion Laboratory A VSCOM Research and Technology Laboratories... FUTURE FUNDAMENTAL COMBUSTION RESEARCH FOR AEROPROPULSION SYSTEMS Edward J. Mularz

  7. Fundamental Scaling Laws in Nanophotonics

    PubMed Central

    Liu, Ke; Sun, Shuai; Majumdar, Arka; Sorger, Volker J.

    2016-01-01

    The success of information technology has clearly demonstrated that miniaturization often leads to unprecedented performance, and unanticipated applications. This hypothesis of “smaller-is-better” has motivated optical engineers to build various nanophotonic devices, although an understanding leading to fundamental scaling behavior for this new class of devices is missing. Here we analyze scaling laws for optoelectronic devices operating at micro and nanometer length-scale. We show that optoelectronic device performance scales non-monotonically with device length due to the various device tradeoffs, and analyze how both optical and electrical constrains influence device power consumption and operating speed. Specifically, we investigate the direct influence of scaling on the performance of four classes of photonic devices, namely laser sources, electro-optic modulators, photodetectors, and all-optical switches based on three types of optical resonators; microring, Fabry-Perot cavity, and plasmonic metal nanoparticle. Results show that while microrings and Fabry-Perot cavities can outperform plasmonic cavities at larger length-scales, they stop working when the device length drops below 100 nanometers, due to insufficient functionality such as feedback (laser), index-modulation (modulator), absorption (detector) or field density (optical switch). Our results provide a detailed understanding of the limits of nanophotonics, towards establishing an opto-electronics roadmap, akin to the International Technology Roadmap for Semiconductors. PMID:27869159

  8. Fundamental Scaling Laws in Nanophotonics

    NASA Astrophysics Data System (ADS)

    Liu, Ke; Sun, Shuai; Majumdar, Arka; Sorger, Volker J.

    2016-11-01

    The success of information technology has clearly demonstrated that miniaturization often leads to unprecedented performance, and unanticipated applications. This hypothesis of “smaller-is-better” has motivated optical engineers to build various nanophotonic devices, although an understanding leading to fundamental scaling behavior for this new class of devices is missing. Here we analyze scaling laws for optoelectronic devices operating at micro and nanometer length-scale. We show that optoelectronic device performance scales non-monotonically with device length due to the various device tradeoffs, and analyze how both optical and electrical constrains influence device power consumption and operating speed. Specifically, we investigate the direct influence of scaling on the performance of four classes of photonic devices, namely laser sources, electro-optic modulators, photodetectors, and all-optical switches based on three types of optical resonators; microring, Fabry-Perot cavity, and plasmonic metal nanoparticle. Results show that while microrings and Fabry-Perot cavities can outperform plasmonic cavities at larger length-scales, they stop working when the device length drops below 100 nanometers, due to insufficient functionality such as feedback (laser), index-modulation (modulator), absorption (detector) or field density (optical switch). Our results provide a detailed understanding of the limits of nanophotonics, towards establishing an opto-electronics roadmap, akin to the International Technology Roadmap for Semiconductors.

  9. Fundamental studies of fusion plasmas

    SciTech Connect

    Aamodt, R.E.; Catto, P.J.; D'Ippolito, D.A.; Myra, J.R.; Russell, D.A.

    1992-05-26

    The major portion of this program is devoted to critical ICH phenomena. The topics include edge physics, fast wave propagation, ICH induced high frequency instabilities, and a preliminary antenna design for Ignitor. This research was strongly coordinated with the world's experimental and design teams at JET, Culham, ORNL, and Ignitor. The results have been widely publicized at both general scientific meetings and topical workshops including the speciality workshop on ICRF design and physics sponsored by Lodestar in April 1992. The combination of theory, empirical modeling, and engineering design in this program makes this research particularly important for the design of future devices and for the understanding and performance projections of present tokamak devices. Additionally, the development of a diagnostic of runaway electrons on TEXT has proven particularly useful for the fundamental understanding of energetic electron confinement. This work has led to a better quantitative basis for quasilinear theory and the role of magnetic vs. electrostatic field fluctuations on electron transport. An APS invited talk was given on this subject and collaboration with PPPL personnel was also initiated. Ongoing research on these topics will continue for the remainder fo the contract period and the strong collaborations are expected to continue, enhancing both the relevance of the work and its immediate impact on areas needing critical understanding.

  10. Fundamental Scaling Laws in Nanophotonics.

    PubMed

    Liu, Ke; Sun, Shuai; Majumdar, Arka; Sorger, Volker J

    2016-11-21

    The success of information technology has clearly demonstrated that miniaturization often leads to unprecedented performance, and unanticipated applications. This hypothesis of "smaller-is-better" has motivated optical engineers to build various nanophotonic devices, although an understanding leading to fundamental scaling behavior for this new class of devices is missing. Here we analyze scaling laws for optoelectronic devices operating at micro and nanometer length-scale. We show that optoelectronic device performance scales non-monotonically with device length due to the various device tradeoffs, and analyze how both optical and electrical constrains influence device power consumption and operating speed. Specifically, we investigate the direct influence of scaling on the performance of four classes of photonic devices, namely laser sources, electro-optic modulators, photodetectors, and all-optical switches based on three types of optical resonators; microring, Fabry-Perot cavity, and plasmonic metal nanoparticle. Results show that while microrings and Fabry-Perot cavities can outperform plasmonic cavities at larger length-scales, they stop working when the device length drops below 100 nanometers, due to insufficient functionality such as feedback (laser), index-modulation (modulator), absorption (detector) or field density (optical switch). Our results provide a detailed understanding of the limits of nanophotonics, towards establishing an opto-electronics roadmap, akin to the International Technology Roadmap for Semiconductors.

  11. Information physics fundamentals of nanophotonics.

    PubMed

    Naruse, Makoto; Tate, Naoya; Aono, Masashi; Ohtsu, Motoichi

    2013-05-01

    Nanophotonics has been extensively studied with the aim of unveiling and exploiting light-matter interactions that occur at a scale below the diffraction limit of light, and recent progress made in experimental technologies--both in nanomaterial fabrication and characterization--is driving further advancements in the field. From the viewpoint of information, on the other hand, novel architectures, design and analysis principles, and even novel computing paradigms should be considered so that we can fully benefit from the potential of nanophotonics. This paper examines the information physics aspects of nanophotonics. More specifically, we present some fundamental and emergent information properties that stem from optical excitation transfer mediated by optical near-field interactions and the hierarchical properties inherent in optical near-fields. We theoretically and experimentally investigate aspects such as unidirectional signal transfer, energy efficiency and networking effects, among others, and we present their basic theoretical formalisms and describe demonstrations of practical applications. A stochastic analysis of light-assisted material formation is also presented, where an information-based approach provides a deeper understanding of the phenomena involved, such as self-organization. Furthermore, the spatio-temporal dynamics of optical excitation transfer and its inherent stochastic attributes are utilized for solution searching, paving the way to a novel computing paradigm that exploits coherent and dissipative processes in nanophotonics.

  12. Levitated Optomechanics for Fundamental Physics

    NASA Astrophysics Data System (ADS)

    Rashid, Muddassar; Bateman, James; Vovrosh, Jamie; Hempston, David; Ulbricht, Hendrik

    2015-05-01

    Optomechanics with levitated nano- and microparticles is believed to form a platform for testing fundamental principles of quantum physics, as well as find applications in sensing. We will report on a new scheme to trap nanoparticles, which is based on a parabolic mirror with a numerical aperture of 1. Combined with achromatic focussing, the setup is a cheap and readily straightforward solution to trapping nanoparticles for further study. Here, we report on the latest progress made in experimentation with levitated nanoparticles; these include the trapping of 100 nm nanodiamonds (with NV-centres) down to 1 mbar as well as the trapping of 50 nm Silica spheres down to 10?4 mbar without any form of feedback cooling. We will also report on the progress to implement feedback stabilisation of the centre of mass motion of the trapped particle using digital electronics. Finally, we argue that such a stabilised particle trap can be the particle source for a nanoparticle matterwave interferometer. We will present our Talbot interferometer scheme, which holds promise to test the quantum superposition principle in the new mass range of 106 amu. EPSRC, John Templeton Foundation.

  13. Gas cell neutralizers (Fundamental principles)

    SciTech Connect

    Fuehrer, B.

    1985-06-01

    Neutralizing an ion-beam of the size and energy levels involved in the neutral-particle-beam program represents a considerable extension of the state-of-the-art of neutralizer technology. Many different mediums (e.g., solid, liquid, gas, plasma, photons) can be used to strip the hydrogen ion of its extra electron. A large, multidisciplinary R and D effort will no doubt be required to sort out all of the ''pros and cons'' of these various techniques. The purpose of this particular presentation is to discuss some basic configurations and fundamental principles of the gas type of neutralizer cell. Particular emphasis is placed on the ''Gasdynamic Free-Jet'' neutralizer since this configuration has the potential of being much shorter than other type of gas cells (in the beam direction) and it could operate in nearly a continuous mode (CW) if necessary. These were important considerations in the ATSU design which is discussed in some detail in the second presentation entitled ''ATSU Point Design''.

  14. Hyperbolic metamaterials: fundamentals and applications.

    PubMed

    Shekhar, Prashant; Atkinson, Jonathan; Jacob, Zubin

    2014-01-01

    Metamaterials are nano-engineered media with designed properties beyond those available in nature with applications in all aspects of materials science. In particular, metamaterials have shown promise for next generation optical materials with electromagnetic responses that cannot be obtained from conventional media. We review the fundamental properties of metamaterials with hyperbolic dispersion and present the various applications where such media offer potential for transformative impact. These artificial materials support unique bulk electromagnetic states which can tailor light-matter interaction at the nanoscale. We present a unified view of practical approaches to achieve hyperbolic dispersion using thin film and nanowire structures. We also review current research in the field of hyperbolic metamaterials such as sub-wavelength imaging and broadband photonic density of states engineering. The review introduces the concepts central to the theory of hyperbolic media as well as nanofabrication and characterization details essential to experimentalists. Finally, we outline the challenges in the area and offer a set of directions for future work.

  15. Force sensor

    DOEpatents

    Grahn, A.R.

    1993-05-11

    A force sensor and related method for determining force components is described. The force sensor includes a deformable medium having a contact surface against which a force can be applied, a signal generator for generating signals that travel through the deformable medium to the contact surface, a signal receptor for receiving the signal reflected from the contact surface, a generation controller, a reception controller, and a force determination apparatus. The signal generator has one or more signal generation regions for generating the signals. The generation controller selects and activates the signal generation regions. The signal receptor has one or more signal reception regions for receiving signals and for generating detections signals in response thereto. The reception controller selects signal reception regions and detects the detection signals. The force determination apparatus measures signal transit time by timing activation and detection and, optionally, determines force components for selected cross-field intersections. The timer which times by activation and detection can be any means for measuring signal transit time. A cross-field intersection is defined by the overlap of a signal generation region and a signal reception region.

  16. Force sensor

    DOEpatents

    Grahn, Allen R.

    1993-01-01

    A force sensor and related method for determining force components. The force sensor includes a deformable medium having a contact surface against which a force can be applied, a signal generator for generating signals that travel through the deformable medium to the contact surface, a signal receptor for receiving the signal reflected from the contact surface, a generation controller, a reception controller, and a force determination apparatus. The signal generator has one or more signal generation regions for generating the signals. The generation controller selects and activates the signal generation regions. The signal receptor has one or more signal reception regions for receiving signals and for generating detections signals in response thereto. The reception controller selects signal reception regions and detects the detection signals. The force determination apparatus measures signal transit time by timing activation and detection and, optionally, determines force components for selected cross-field intersections. The timer which times by activation and detection can be any means for measuring signal transit time. A cross-field intersection is defined by the overlap of a signal generation region and a signal reception region.

  17. BOOK REVIEWS: Quantum Mechanics: Fundamentals

    NASA Astrophysics Data System (ADS)

    Whitaker, A.

    2004-02-01

    mechanics, which is assumed, but to examine whether it gives a consistent account of measurement. The conclusion is that after a measurement, interference terms are ‘effectively’ absent; the set of ‘one-to-one correlations between states of the apparatus and the object’ has the same form as that of everyday statistics and is thus a probability distribution. This probability distribution refers to potentialities, only one of which is actually realized in any one trial. Opinions may differ on whether their treatment is any less vulnerable to criticisms such as those of Bell. To sum up, Gottfried and Yan’s book contains a vast amount of knowledge and understanding. As well as explaining the way in which quantum theory works, it attempts to illuminate fundamental aspects of the theory. A typical example is the ‘fable’ elaborated in Gottfried’s article in Nature cited above, that if Newton were shown Maxwell’s equations and the Lorentz force law, he could deduce the meaning of E and B, but if Maxwell were shown Schrödinger’s equation, he could not deduce the meaning of Psi. For use with a well-constructed course (and, of course, this is the avowed purpose of the book; a useful range of problems is provided for each chapter), or for the relative expert getting to grips with particular aspects of the subject or aiming for a deeper understanding, the book is certainly ideal. It might be suggested, though, that, even compared to the first edition, the isolated learner might find the wide range of topics, and the very large number of mathematical and conceptual techniques, introduced in necessarily limited space, somewhat overwhelming. The second book under consideration, that of Schwabl, contains ‘Advanced’ elements of quantum theory; it is designed for a course following on from one for which Gottfried and Yan, or Schwabl’s own `Quantum Mechanics' might be recommended. It is the second edition in English, and is a translation of the third German edition

  18. T cell activation requires force generation

    PubMed Central

    Hu, Kenneth H.

    2016-01-01

    Triggering of the T cell receptor (TCR) integrates both binding kinetics and mechanical forces. To understand the contribution of the T cell cytoskeleton to these forces, we triggered T cells using a novel application of atomic force microscopy (AFM). We presented antigenic stimulation using the AFM cantilever while simultaneously imaging with optical microscopy and measuring forces on the cantilever. T cells respond forcefully to antigen after calcium flux. All forces and calcium responses were abrogated upon treatment with an F-actin inhibitor. When we emulated the forces of the T cell using the AFM cantilever, even these actin-inhibited T cells became activated. Purely mechanical stimulation was not sufficient; the exogenous forces had to couple through the TCR. These studies suggest a mechanical–chemical feedback loop in which TCR-triggered T cells generate forceful contacts with antigen-presenting cells to improve access to antigen. PMID:27241914

  19. Astronomia Motivadora no Ensino Fundamental

    NASA Astrophysics Data System (ADS)

    Melo, J.; Voelzke, M. R.

    2008-09-01

    O objetivo principal deste trabalho é procurar desenvolver o interesse dos alunos pelas ciências através da Astronomia. Uma pesquisa com perguntas sobre Astronomia foi realizada junto a 161 alunos do Ensino Fundamental, com o intuito de descobrir conhecimentos prévios dos alunos sobre o assunto. Constatou-se, por exemplo, que 29,3% da 6ª série responderam corretamente o que é eclipse, 30,0% da 8ª série acertaram o que a Astronomia estuda, enquanto 42,3% dos alunos da 5ª série souberam definir o Sol. Pretende-se ampliar as turmas participantes e trabalhar, principalmente de forma prática com: dimensões e escalas no Sistema Solar, construção de luneta, questões como dia e noite, estações do ano e eclipses. Busca-se abordar, também, outros conteúdos de Física tais como a óptica na construção da luneta, e a mecânica no trabalho com escalas e medidas, e ao utilizar uma luminária para representar o Sol na questão do eclipse, e de outras disciplinas como a Matemática na transformação de unidades, regras de três; Artes na modelagem ou desenho dos planetas; a própria História com relação à busca pela origem do universo, e a Informática que possibilita a busca mais rápida por informações, além de permitir simulações e visualizações de imagens importantes. Acredita-se que a Astronomia é importante no processo ensino aprendizagem, pois permite a discussão de temas curiosos como, por exemplo, a origem do universo, viagens espaciais a existência ou não de vida em outros planetas, além de temas atuais como as novas tecnologias.

  20. Investigation of fundamental limits to beam brightness available from photoinjectors

    SciTech Connect

    Bazarov, Ivan

    2015-07-09

    The goal of this project was investigation of fundamental limits to beam brightness available from photoinjectors. This basic research in accelerator physics spanned over 5 years aiming to extend the fundamental understanding of high average current, low emittance sources of relativistic electrons based on photoemission guns, a necessary prerequisite for a new generation of coherent X-ray synchrotron radiation facilities based on continuous duty superconducting linacs. The program focused on two areas critical to making advances in the electron source performance: 1) the physics of photocathodes for the production of low emittance electrons and 2) control of space charge forces in the immediate vicinity to the cathode via 3D laser pulse shaping.

  1. Forced Snaking

    NASA Astrophysics Data System (ADS)

    Ponedel, Benjamin; Knobloch, Edgar

    2016-11-01

    We study spatial localization in the real subcritical Ginzburg-Landau equation ut =m0 u +m1 cos2/π l x u +uxx +d | u | 2 u -| u | 4 u with spatially periodic forcing. When d > 0 and m1 = 0 this equation exhibits bistability between the trivial state u = 0 and a homogeneous nontrivial state u =u0 with stationary localized structures which accumulate at the Maxwell point m0 = - 3d2 / 16 . When spatial forcing is included its wavelength is imprinted on u0 creating conditions favorable to front pinning and hence spatial localization. We use numerical continuation to show that under appropriate conditions such forcing generates a sequence of localized states organized within a snakes-and-ladders structure centered on the Maxwell point, and refer to this phenomenon as forced snaking. We determine the stability properties of these states and show that longer lengthscale forcing leads to stationary trains consisting of a finite number of strongly localized, weakly interacting pulses exhibiting foliated snaking.

  2. Molecular force spectroscopy on cells.

    PubMed

    Liu, Baoyu; Chen, Wei; Zhu, Cheng

    2015-04-01

    Molecular force spectroscopy has become a powerful tool to study how mechanics regulates biology, especially the mechanical regulation of molecular interactions and its impact on cellular functions. This force-driven methodology has uncovered a wealth of new information of the physical chemistry of molecular bonds for various biological systems. The new concepts, qualitative and quantitative measures describing bond behavior under force, and structural bases underlying these phenomena have substantially advanced our fundamental understanding of the inner workings of biological systems from the nanoscale (molecule) to the microscale (cell), elucidated basic molecular mechanisms of a wide range of important biological processes, and provided opportunities for engineering applications. Here, we review major force spectroscopic assays, conceptual developments of mechanically regulated kinetics of molecular interactions, and their biological relevance. We also present current challenges and highlight future directions.

  3. Implementing fundamental care in clinical practice.

    PubMed

    Feo, Rebecca; Conroy, Tiffany; Alderman, Jan; Kitson, Alison

    2017-04-05

    Modern healthcare environments are becoming increasingly complex. Delivering high-quality fundamental care in these environments is challenging for nurses and has been the focus of recent media, policy, academic and public scrutiny. Much of this attention arises from evidence that fundamental care is being neglected or delivered inadequately. There are an increasing number of standards and approaches to the delivery of fundamental care, which may result in confusion and additional documentation for nurses to complete. This article provides nurses with an approach to reframe their thinking about fundamental care, to ensure they meet patients' care needs and deliver holistic, person-centred care.

  4. Intermolecular forces.

    PubMed

    Buckingham, A D

    1975-11-06

    The nature of molecular interactions is examined. Intermolecular forces are divided into long-range and short-range components; the former operate at distances where the effects of electron exchange are negligible and decrease as an inverse power of the separation. The long-range interactions may be subdividied into electrostatic, induction and dispersion contributions, where the electrostatic component is the interaction of the permanent charge distributions and the others originate in the fluctuations in the distributions. Typical magnitudes of the various contributions are given. The forces between macroscopic bodies are briefly considered, as are the effects of a medium. Some of the manifestations of molecular interactions are discussed.

  5. Fundamental Mistuning Model for Probabilistic Analysis Studied Experimentally

    NASA Technical Reports Server (NTRS)

    Griffin, Jerry H.

    2005-01-01

    The Fundamental Mistuning Model (FMM) is a reduced-order model for efficiently calculating the forced response of a mistuned bladed disk. FMM ID is a companion program that determines the mistuning in a particular rotor. Together, these methods provide a way to acquire mistuning data in a population of bladed disks and then simulate the forced response of the fleet. This process was tested experimentally at the NASA Glenn Research Center, and the simulated results were compared with laboratory measurements of a "fleet" of test rotors. The method was shown to work quite well. It was found that the accuracy of the results depends on two factors: (1) the quality of the statistical model used to characterize mistuning and (2) how sensitive the system is to errors in the statistical modeling.

  6. Loss of Desmoglein Binding Is Not Sufficient for Keratinocyte Dissociation in Pemphigus.

    PubMed

    Vielmuth, Franziska; Waschke, Jens; Spindler, Volker

    2015-12-01

    Pemphigus vulgaris (PV) is a severe autoimmune disease in which autoantibodies against the desmosomal cell adhesion molecules desmoglein (Dsg) 1 and Dsg3 cause intraepidermal blister formation. Mechanistically, the fundamental question is still unresolved whether loss of cell cohesion is a result of (1) direct inhibition of Dsg interaction by autoantibodies or (2) intracellular signaling events, which are altered in response to antibody binding and finally cause desmosome destabilization. We used atomic force microscopy (AFM) to perform Dsg3 adhesion measurements on living keratinocytes to investigate the contributions of direct inhibition and signaling to loss of cell cohesion after autoantibody treatment. Dsg3 binding was rapidly blocked following antibody exposure under conditions where no depletion of surface Dsg3 was detectable, demonstrating direct inhibition of Dsg3 interaction. Inhibition of p38MAPK, a central signaling molecule in PV pathogenesis, abrogated loss of cell cohesion, but had a minor effect on loss of Dsg3 binding. Similarly, the cholesterol-depleting agent methyl-β-cyclodextrin (β-MCD) fully blocked cell dissociation, but did not restore Dsg3 interactions or prevent the activation of p38MAPK. These results demonstrate that inhibition of Dsg3 binding is not sufficient to cause loss of cell cohesion, but rather alters signaling events which, in lipid raft-dependent manner, induce cell dissociation.

  7. Canonical Force Distributions in Pairwise Interatomic Interactions from the Perspective of the Hellmann-Feynman Theorem.

    PubMed

    Walton, Jay R; Rivera-Rivera, Luis A; Lucchese, Robert R; Bevan, John W

    2016-05-26

    Force-based canonical approaches have recently given a unified but different viewpoint on the nature of bonding in pairwise interatomic interactions. Differing molecular categories (covalent, ionic, van der Waals, hydrogen, and halogen bonding) of representative interatomic interactions with binding energies ranging from 1.01 to 1072.03 kJ/mol have been modeled canonically giving a rigorous semiempirical verification to high accuracy. However, the fundamental physical basis expected to provide the inherent characteristics of these canonical transformations has not yet been elucidated. Subsequently, it was shown through direct numerical differentiation of these potentials that their associated force curves have canonical shapes. However, this approach to analyzing force results in inherent loss of accuracy coming from numerical differentiation of the potentials. We now show that this serious obstruction can be avoided by directly demonstrating the canonical nature of force distributions from the perspective of the Hellmann-Feynman theorem. This requires only differentiation of explicitly known Coulombic potentials, and we discuss how this approach to canonical forces can be used to further explain the nature of chemical bonding in pairwise interatomic interactions. All parameter values used in the canonical transformation are determined through explicit physical based algorithms, and it does not require direct consideration of electron correlation effects.

  8. Fundamental optics: On-chip Casimir effect

    NASA Astrophysics Data System (ADS)

    Milton, Kimball A.

    2017-02-01

    Measurement of the forces that arise from quantum vacuum fluctuations between closely spaced surfaces typically requires large apparatus, making applications difficult. Now, an experiment on a silicon chip to measure the Casimir force has been realized.

  9. Individual differences in fundamental social motives.

    PubMed

    Neel, Rebecca; Kenrick, Douglas T; White, Andrew Edward; Neuberg, Steven L

    2016-06-01

    Motivation has long been recognized as an important component of how people both differ from, and are similar to, each other. The current research applies the biologically grounded fundamental social motives framework, which assumes that human motivational systems are functionally shaped to manage the major costs and benefits of social life, to understand individual differences in social motives. Using the Fundamental Social Motives Inventory, we explore the relations among the different fundamental social motives of Self-Protection, Disease Avoidance, Affiliation, Status, Mate Seeking, Mate Retention, and Kin Care; the relationships of the fundamental social motives to other individual difference and personality measures including the Big Five personality traits; the extent to which fundamental social motives are linked to recent life experiences; and the extent to which life history variables (e.g., age, sex, childhood environment) predict individual differences in the fundamental social motives. Results suggest that the fundamental social motives are a powerful lens through which to examine individual differences: They are grounded in theory, have explanatory value beyond that of the Big Five personality traits, and vary meaningfully with a number of life history variables. A fundamental social motives approach provides a generative framework for considering the meaning and implications of individual differences in social motivation. (PsycINFO Database Record

  10. Fundamentals of Physics, Problem Supplement No. 1

    NASA Astrophysics Data System (ADS)

    Halliday, David; Resnick, Robert; Walker, Jearl

    2000-05-01

    No other book on the market today can match the success of Halliday, Resnick and Walker's Fundamentals of Physics! In a breezy, easy-to-understand style the book offers a solid understanding of fundamental physics concepts, and helps readers apply this conceptual understanding to quantitative problem solving.

  11. Fundamentals of Physics, Student's Solutions Manual

    NASA Astrophysics Data System (ADS)

    Halliday, David; Resnick, Robert; Walker, Jearl

    2000-07-01

    No other book on the market today can match the success of Halliday, Resnick and Walker's Fundamentals of Physics! In a breezy, easy-to-understand style the book offers a solid understanding of fundamental physics concepts, and helps readers apply this conceptual understanding to quantitative problem solving.

  12. Fundamentals of Physics, 7th Edition

    NASA Astrophysics Data System (ADS)

    Halliday, David; Resnick, Robert; Walker, Jearl

    2004-05-01

    No other book on the market today can match the 30-year success of Halliday, Resnick and Walker's Fundamentals of Physics! In a breezy, easy-to-understand style the book offers a solid understanding of fundamental physics concepts, and helps readers apply this conceptual understanding to quantitative problem solving. This book offers a unique combination of authoritative content and stimulating applications.

  13. Energy profile of nanobody-GFP complex under force

    NASA Astrophysics Data System (ADS)

    Klamecka, Kamila; Severin, Philip M.; Milles, Lukas F.; Gaub, Hermann E.; Leonhardt, Heinrich

    2015-10-01

    Nanobodies (Nbs)—the smallest known fully functional and naturally occuring antigen-binding fragments—have attracted a lot of attention throughout the last two decades. Exploring their potential beyond the current use requires more detailed characterization of their binding forces as those cannot be directly derived from the binding affinities. Here we used atomic force microscope to measure rupture force of the Nb-green fluorescent protein (GFP) complex in various pulling geometries and derived the energy profile characterizing the interaction along the direction of the pulling force. We found that—despite identical epitopes—the Nb binds stronger (41-56 pN) to enhanced GFP than to wild-type GFP (28-45 pN). Measured forces make the Nb-GFP pair a potent reference for investigating molecular forces in living systems both in and ex vivo.

  14. Fundamentals of wetting and spreading with emphasis on soldering

    SciTech Connect

    Yost, F.G.

    1991-01-01

    Soldering is often referred to as a mature technology whose fundamentals were established long ago. Yet a multitude of soldering problems persist, not the least of which are related to the wetting and spreading of solder. The Buff-Goodrich approach to thermodynamics of capillarity is utilized in a review of basic wetting principles. These thermodynamics allow a very compact formulation of capillary phenomena which is used to calculate various meniscus shapes and wetting forces. These shapes and forces lend themselves to experimental techniques, such as the sessile drop and the Wilhelmy plate, for measuring useful surface and interfacial energies. The familiar equations of Young, Wilhelmy, and Neumann are all derived with this approach. The force-energy duality of surface energy is discussed and the force method is developed and used to derive the Herring relations for anisotropic surfaces. The importance of contact angle hysteresis which results from surface roughness and chemical inhomogeneity is presented and Young's equation is modified to reflect these ever present effects. Finally, an analysis of wetting with simultaneous metallurigical reaction is given and used to discuss solder wetting phenomena. 60 refs., 13 figs.

  15. The binding interactions of imidacloprid with earthworm fibrinolytic enzyme

    NASA Astrophysics Data System (ADS)

    Wang, Yan-Qing; Zhang, Hong-Mei; Chen, Tao

    2014-08-01

    In this paper, several studies were conducted to elucidate the binding mechanism of earthworm fibrinolytic enzyme (EFE) with imidocloprid (IMI) by using theoretical calculation, fluorescence, UV-vis, circular dichroism spectroscopy and an enzymatic inhibition assay. The spectral data showed that the binding interactions existed between IMI and EFE. The binding constants, binding site, thermodynamic parameters and binding forces were analyzed in detail. The results indicate a single class of binding sites for IMI in EFE and that this binding interaction is a spontaneous process with the estimated enthalpy and entropy changes being 2.195 kJ mol-1 and 94.480 J mol-1 K-1, respectively. A single class of binding site existed for IMI in EFE. The tertiary or secondary structure of EFE was partly destroyed by IMI. The visualized binding details were also exhibited by the theoretical calculation and the results indicated that the interaction between IMI and Phe (Tyr, or Trp) or EFE occurred. Combining the experimental data with the theoretical calculation data, we showed that the binding forces between IMI and EFE were mainly hydrophobic force accompanied by hydrogen binding, and π-π stacking. In addition, IMI did not obviously influence the activity of EFE. In a word, the above analysis offered insights into the binding mechanism of IMI with EFE and could provide some important information for the molecular toxicity of IMI for earthworms.

  16. Fundamental solutions in a half space of two-dimensional hexagonal quasicrystal and their applications

    SciTech Connect

    Wang, T.; Li, X. Y.; Zhang, X.; Müller, R.

    2015-04-21

    Fundamental phonon-phason field in a half-infinite space of two-dimensional hexagonal quasicrystal is derived, on the basis of general solutions in terms of quasi-harmonic functions, by virtue of the trial-and-error technique. Extended Boussinesq and Cerruti problems are studied. Appropriate potential functions are assumed and corresponding fundamental solutions are explicitly derived in terms of elementary functions. The boundary integral equations governing the contact and crack problems are constructed from the present fundament solutions. The obtained analytical solutions can serve as guidelines for future indentation tests via scanning probe microscopy and atomic force microscopy methods.

  17. Bacterial adhesion force quantification by fluidic force microscopy

    NASA Astrophysics Data System (ADS)

    Potthoff, Eva; Ossola, Dario; Zambelli, Tomaso; Vorholt, Julia A.

    2015-02-01

    Quantification of detachment forces between bacteria and substrates facilitates the understanding of the bacterial adhesion process that affects cell physiology and survival. Here, we present a method that allows for serial, single bacterial cell force spectroscopy by combining the force control of atomic force microscopy with microfluidics. Reversible bacterial cell immobilization under physiological conditions on the pyramidal tip of a microchanneled cantilever is achieved by underpressure. Using the fluidic force microscopy technology (FluidFM), we achieve immobilization forces greater than those of state-of-the-art cell-cantilever binding as demonstrated by the detachment of Escherichia coli from polydopamine with recorded forces between 4 and 8 nN for many cells. The contact time and setpoint dependence of the adhesion forces of E. coli and Streptococcus pyogenes, as well as the sequential detachment of bacteria out of a chain, are shown, revealing distinct force patterns in the detachment curves. This study demonstrates the potential of the FluidFM technology for quantitative bacterial adhesion measurements of cell-substrate and cell-cell interactions that are relevant in biofilms and infection biology.Quantification of detachment forces between bacteria and substrates facilitates the understanding of the bacterial adhesion process that affects cell physiology and survival. Here, we present a method that allows for serial, single bacterial cell force spectroscopy by combining the force control of atomic force microscopy with microfluidics. Reversible bacterial cell immobilization under physiological conditions on the pyramidal tip of a microchanneled cantilever is achieved by underpressure. Using the fluidic force microscopy technology (FluidFM), we achieve immobilization forces greater than those of state-of-the-art cell-cantilever binding as demonstrated by the detachment of Escherichia coli from polydopamine with recorded forces between 4 and 8 nN for many

  18. Rolling Contact Force Energy Reconstruction

    NASA Astrophysics Data System (ADS)

    BRACCIALI, A.; CASCINI, G.

    2000-09-01

    Knowledge of the forces at the wheel-rail contact is fundamental to estimate the consequences in terms of noise and vibration. The traditional use of strain gauges mounted on the wheel web and axle is not capable of determining the high-frequency content of the contact force. Measurements made on the rail are characterized by the spatial variability of input-output transfer functions which makes it difficult to estimate the contact force by simple inversion of the point frequency response function. In this study the problem of rolling contact force reconstruction has been approached through the following steps: (i) the track has been characterized precisely for a finite length by the analysis of the time series of several impacts supplied with an instrumented hammer by using an ARMAX model that proved to be capable of modelling the vertical dynamics of the rail up to 5 kHz; (ii) the response of the rail has been simulated with a random force acting on the system, and the variability of the transfer function has been taken into account by distributing the force on adjacent elements; (iii) the simulated response has been compared with the rail acceleration measured for the passage of several trains; (iv) the wheel-rail contact force has been estimated with a closed-loop algorithm. It has thus been possible to reconstruct the13octave power spectrum of contact forces with a simple and stable iterative procedure. Forces reconstructed from different sensors were found to be practically the same for a given wheel; forces from nominally similar wheels are statistically examined and partial results of comparisons made on different rolling stock are shown.

  19. The FP4026 Research Database on the fundamental period of RC infilled frame structures.

    PubMed

    Asteris, Panagiotis G

    2016-12-01

    The fundamental period of vibration appears to be one of the most critical parameters for the seismic design of buildings because it strongly affects the destructive impact of the seismic forces. In this article, important research data (entitled FP4026 Research Database (Fundamental Period-4026 cases of infilled frames) based on a detailed and in-depth analytical research on the fundamental period of reinforced concrete structures is presented. In particular, the values of the fundamental period which have been analytically determined are presented, taking into account the majority of the involved parameters. This database can be extremely valuable for the development of new code proposals for the estimation of the fundamental period of reinforced concrete structures fully or partially infilled with masonry walls.

  20. Representation of Ion–Protein Interactions Using the Drude Polarizable Force-Field

    PubMed Central

    2016-01-01

    Small metal ions play critical roles in numerous biological processes. Of particular interest is how metalloenzymes are allosterically regulated by the binding of specific ions. Understanding how ion binding affects these biological processes requires atomic models that accurately treat the microscopic interactions with the protein ligands. Theoretical approaches at different levels of sophistication can contribute to a deeper understanding of these systems, although computational models must strike a balance between accuracy and efficiency in order to enable long molecular dynamics simulations. In this study, we present a systematic effort to optimize the parameters of a polarizable force field based on classical Drude oscillators to accurately represent the interactions between ions (K+, Na+, Ca2+, and Cl–) and coordinating amino-acid residues for a set of 30 biologically important proteins. By combining ab initio calculations and experimental thermodynamic data, we derive a polarizable force field that is consistent with a wide range of properties, including the geometries and interaction energies of gas-phase ion/protein-like model compound clusters, and the experimental solvation free-energies of the cations in liquids. The resulting models display significant improvements relative to the fixed-atomic-charge additive CHARMM C36 force field, particularly in their ability to reproduce the many-body electrostatic nonadditivity effects estimated from ab initio calculations. The analysis clarifies the fundamental limitations of the pairwise additivity assumption inherent in classical fixed-charge force fields, and shows its dramatic failures in the case of Ca2+ binding sites. These optimized polarizable models, amenable to computationally efficient large-scale MD simulations, set a firm foundation and offer a powerful avenue to study the roles of the ions in soluble and membrane transport proteins. PMID:25578354

  1. Force decomposition in robot force control

    NASA Technical Reports Server (NTRS)

    Murphy, Steve H.; Wen, John T.

    1991-01-01

    The unit inconsistency in force decomposition has motivated an investigation into the force control problem in multiple-arm manipulation. Based on physical considerations, it is argued that the force that should be controlled is the internal force at the specified frame in the payload. This force contains contributions due to both applied forces from the arms and the inertial force from the payload and the arms. A least-squares scheme free of unit inconsistency for finding this internal force is presented. The force control issue is analyzed, and an integral force feedback controller is proposed.

  2. Strategic forces

    SciTech Connect

    Not Available

    1990-10-01

    The Air Force now plans to retain the Minuteman II and III missile force through fiscal year 2008. Introduced about 25 years ago, these missiles have served as a nuclear deterrence for longer than initially envisioned. Over the extended lives of the systems, questions have arisen over their continued reliability and operational effectiveness, particularly the Minuteman II system. Limited flight testing, due to a shortage of test missiles, and reduced reliability caused by age-related deterioration of guidance computers and propulsion motors are two factors undermining confidence in the Minuteman II. GAO believes that the Minuteman II could be retired before 1998 as presently contemplated under an assumption of a Strategic Arms Reduction Talks agreement. An alternative would be to reinstate the Air Force's plans to replace deteriorated missile components and acquire the assets needed to resume flight testing at rates necessary to restore and sustain confidence in the system's performance through fiscal year 2008. However, on the basis of current test schedules, GAO is concerned that components to test the missile's warheads will be depleted by about 1999.

  3. Fundamentals of preparative and nonlinear chromatography

    SciTech Connect

    Guiochon, Georges A; Felinger, Attila; Katti, Anita; Shirazi, Dean G

    2006-02-01

    The second edition of Fundamentals of Preparative and Nonlinear Chromatography is devoted to the fundamentals of a new process of purification or extraction of chemicals or proteins widely used in the pharmaceutical industry and in preparative chromatography. This process permits the preparation of extremely pure compounds satisfying the requests of the US Food and Drug Administration. The book describes the fundamentals of thermodynamics, mass transfer kinetics, and flow through porous media that are relevant to chromatography. It presents the models used in chromatography and their solutions, discusses the applications made, describes the different processes used, their numerous applications, and the methods of optimization of the experimental conditions of this process.

  4. Force measurement enabling precise analysis by dynamic force spectroscopy.

    PubMed

    Taninaka, Atsushi; Hirano, Yuuichi; Takeuchi, Osamu; Shigekawa, Hidemi

    2012-01-01

    Dynamic force spectroscopy (DFS) makes it possible to investigate specific interactions between two molecules such as ligand-receptor pairs at the single-molecule level. In the DFS method based on the Bell-Evans model, the unbinding force applied to a molecular bond is increased at a constant rate, and the force required to rupture the molecular bond is measured. By analyzing the relationship between the modal rupture force and the logarithm of the loading rate, microscopic potential barrier landscapes and the lifetimes of bonds can be obtained. However, the results obtained, for example, in the case of streptavidin/biotin complexes, have differed among previous studies and some results have been inconsistent with theoretical predictions. In this study, using an atomic force microscopy technique that enables the precise analysis of molecular interactions on the basis of DFS, we investigated the effect of the sampling rate on DFS analysis. The shape of rupture force histograms, for example, was significantly deformed at a sampling rate of 1 kHz in comparison with that of histograms obtained at 100 kHz, indicating the fundamental importance of ensuring suitable experimental conditions for further advances in the DFS method.

  5. Strategic Information Resources Management: Fundamental Practices.

    ERIC Educational Resources Information Center

    Caudle, Sharon L.

    1996-01-01

    Discusses six fundamental information resources management (IRM) practices in successful organizations that can improve government service delivery performance. Highlights include directing changes, integrating IRM decision making into a strategic management process, performance management, maintaining an investment philosophy, using business…

  6. Instructor Special Report: RIF (Reading Is FUNdamental)

    ERIC Educational Resources Information Center

    Instructor, 1976

    1976-01-01

    At a time when innovative programs of the sixties are quickly falling out of the picture, Reading Is FUNdamental, after ten years and five million free paperbacks, continues to expand and show results. (Editor)

  7. Language Policy and Planning: Fundamental Issues.

    ERIC Educational Resources Information Center

    Kaplan, Robert B.

    1994-01-01

    Fundamental issues in language policy and planning are discussed: language death, language survival, language change, language revival, language shift and expansion, language contact and pidginization or creolization, and literacy development. (Contains 21 references.) (LB)

  8. Accounting Fundamentals for Non-Accountants

    EPA Pesticide Factsheets

    The purpose of this module is to provide an introduction and overview of accounting fundamentals for non-accountants. The module also covers important topics such as communication, internal controls, documentation and recordkeeping.

  9. Fundamentals of Indoor Air Quality in Buildings

    EPA Pesticide Factsheets

    This module provides the fundamentals to understanding indoor air quality. It provides a rudimentary framework for understanding how indoor and outdoor sources of pollution affect the indoor air quality of buildings.

  10. Force spectroscopy of DNA: there is still a lot to learn

    NASA Astrophysics Data System (ADS)

    Paik, D. H.; Perkins, Thomas T.

    2012-10-01

    Single-molecule studies of the mechanical properties of individual double-stranded DNA have excited interest across many scientific disciplines because of DNA's fundamental role in biology and DNA's remarkable overstretching transition at higher forces. Here, we discuss a recent result on the overstretching transition of DNA and on the dynamics of dye molecules intercalating into DNA under tension. Overstretching DNA is mechanical transition whereby DNA's extension increases by 70% at 65 pN. Notwithstanding more than a decade of experimental and theoretical studies, there remains significant debate on the nature of overstretched DNA. We developed a topologically closed but torsionally unconstrained DNA assay that contains no nicks or free ends. DNA in this assay exhibited the canonical overstretching transition at 65 pN but without hysteresis upon retraction. Controlled introduction of a nick led to hysteresis in the force extension curve. Moreover, the degree of hysteresis increased with the number of nicks. In the second study, we isolated the effects of binding and intercalation of a DNA staining dye, by combining single molecule force spectroscopy with simple buffer exchange. We showed that force-enhanced intercalation can occur from a reservoir of bound dye that was not bis-intercalated, yet remained out of equilibrium with free dye for long periods (<5 min for YOPRO and <2 hr for YOYO). Our work highlights that binding/unbinding and intercalation/de-intercalation are distinct processes that can occur on very different time scales. Taken together, these works highlight ongoing discoveries based on a twenty year old technique, force spectroscopy of single DNA molecules.

  11. Does logic moderate the fundamental attribution error?

    PubMed

    Stalder, D R

    2000-06-01

    The fundamental attribution error was investigated from an individual difference perspective. Mathematicians were compared with nonmathematicians (Exp. 1; n: 84), and undergraduates who scored high on a test of logical reasoning ability were compared with those who scored low (Exp. 2; n: 62). The mathematicians and those participants scoring higher on logic appeared less prone to the fundamental attribution error, primarily using a measure of confidence in attributions.

  12. Fundamental Reaction Mechanism for Cocaine Hydrolysis in Human Butyrylcholinesterase

    PubMed Central

    Zhan, Chang-Guo; Zheng, Fang; Landry, Donald W.

    2010-01-01

    Butyrylcholinesterase (BChE)-cocaine binding and the fundamental pathway for BChE-catalyzed hydrolysis of cocaine have been studied by molecular modelling, molecular dynamics (MD) simulations, and ab initio calculations. Modelling and simulations indicate that the structures of the prereactive BChE-substrate complexes for (−)-cocaine and (+)-cocaine are all similar to that of the corresponding prereactive BChE-butyrylcholine (BCh) complex. The overall binding of BChE with (−)-cocaine and (+)-cocaine is also similar to that proposed with butyrylthiocholine and succinyldithiocholine, i.e. (−)-cocaine/(+)-cocaine first slides down the substrate-binding gorge to bind to Trp-82 and stands vertically in the gorge between Asp-70 and Trp-82 (non-prereactive complex) and then rotates to a position in the catalytic site within a favorable distance for nucleophilic attack and hydrolysis by Ser-198 (prereactive complex). In the prereactive complex, cocaine lies horizontally at the bottom of the gorge. The fundamental catalytic hydrolysis pathway, consisting of acylation and deacylation stages similar to those for ester hydrolysis by other serine hydrolases, was proposed based on the simulated prereactive complex and confirmed theoretically by ab initio reaction coordinate calculations. Both the acylation and deacylation follow a double-proton-transfer mechanism. The calculated energetic results show that within the chemical reaction process the highest energy barrier and Gibbs free energy barrier are all associated with the first step of deacylation. The calculated ratio of the rate constant (kcat) for the catalytic hydrolysis to that (k0) for the spontaneous hydrolysis is ~ 9.0 × 107. The estimated kcat/k0 value of ~ 9.0 × 107 is in excellent agreement with the experimentally-derived kcat/k0 value of ~ 7.2 × 107 for (+)-cocaine, whereas it is ~ 2000 times larger than the experimentally-derived kcat/k0 value of ~ 4.4 × 104 for (−)-cocaine. All of the results

  13. Compulsory Bible Reading in Arkansas and the Culture of Southern Fundamentalism.

    ERIC Educational Resources Information Center

    Bolton, S. Charles; Ledbetter, Cal Jr.

    1983-01-01

    Arkansas passed a law requiring Bible reading in public schools in 1930, two years after passing an antievolution act. Votes on both measures, which were the result of initiatives, are compared to explain the forces that produced them. The source of support of fundamentalism is traditional southern religious attitudes. (Author/IS)

  14. FUNDAMENTAL DIFFERENCES BETWEEN NATURAL ANTIBODIES AND POLYREACTIVE IMMUNOGLOBULINS.

    PubMed

    Bobrovnik, S A; Demchenko, M A; Komisarenko, S V

    2015-01-01

    A problem of similarity and differences between so-called polyreactive immunoglobulins (PRIGs) and natural antibodies (NAbs), capable of cross-reacting with some structurally dissimilar antigens, has been considered. The analysis of mechanisms of an unspecific interaction between PRIGs or NAbs and antigens evidences for the fact that essential differences exist between these substances. These differences permit classifying the abovementioned substances as different types of immunoglobulin molecules. The major difference between PRIGs and NAbs may include both the mechanisms of the above mentioned immunoglobulin molecules binding to antigens and their interaction affinity, as well as an absolutely different influence of some low-molecular substances on the efficiency of the interaction with antigens. Relying on the obtained data it can be assumed that, since PRIGs and NAbs have fundamental differences, they may perform not only similar but also different functions of the immune system.

  15. Ratiometric Tension Probes for Mapping Receptor Forces and Clustering at Intermembrane Junctions.

    PubMed

    Ma, Victor Pui-Yan; Liu, Yang; Blanchfield, Lori; Su, Hanquan; Evavold, Brian D; Salaita, Khalid

    2016-07-13

    Short-range communication between cells is required for the survival of multicellular organisms. One mechanism of chemical signaling between adjacent cells employs surface displayed ligands and receptors that only bind when two cells make physical contact. Ligand-receptor complexes that form at the cell-cell junction and physically bridge two cells likely experience mechanical forces. A fundamental challenge in this area pertains to mapping the mechanical forces experienced by ligand-receptor complexes within such a fluid intermembrane junction. Herein, we describe the development of ratiometric tension probes for direct imaging of receptor tension, clustering, and lateral transport within a model cell-cell junction. These probes employ two fluorescent reporters that quantify both the ligand density and the ligand tension and thus generate a tension signal independent of clustering. As a proof-of-concept, we applied the ratiometric tension probes to map the forces experienced by the T-cell receptor (TCR) during activation and showed the first direct evidence that the TCR-ligand complex experiences sustained pN forces within a fluid membrane junction. We envision that the ratiometric tension probes will be broadly useful for investigating mechanotransduction in juxtacrine signaling pathways.

  16. Natural transition from rate to force control of a manipulator

    NASA Technical Reports Server (NTRS)

    Harrison, F. W.; Soloway, Don; Williams, Robert L.; Hogge, Edward F.

    1992-01-01

    A method for teleoperator control which offers advantages over previous techniques is demonstrated. In the new method, a fundamental variable exchanged between the master and slave is the rate of change in position and force. An inherent capability of the control scheme is demonstrated for transition between control methods based on environmental constraints in a manner natural to the operator. Specifically, rate control of a manipulator makes the transition to force-force control when a force-reflecting hand controller is used with a local force accommodation algorithm running on the remote manipulator. The transition from rate to force occurs when contact is made with the environment.

  17. The role of nonlinear dynamics in quantitative atomic force microscopy.

    PubMed

    Platz, Daniel; Forchheimer, Daniel; Tholén, Erik A; Haviland, David B

    2012-07-05

    Various methods of force measurement with the atomic force microscope are compared for their ability to accurately determine the tip-surface force from analysis of the nonlinear cantilever motion. It is explained how intermodulation, or the frequency mixing of multiple drive tones by the nonlinear tip-surface force, can be used to concentrate the nonlinear motion in a narrow band of frequency near the cantilever's fundamental resonance, where accuracy and sensitivity of force measurement are greatest. Two different methods for reconstructing tip-surface forces from intermodulation spectra are explained. The reconstruction of both conservative and dissipative tip-surface interactions from intermodulation spectra are demonstrated on simulated data.

  18. A Fundamental Equation of State for Ethanol

    NASA Astrophysics Data System (ADS)

    Schroeder, J. A.; Penoncello, S. G.; Schroeder, J. S.

    2014-12-01

    The existing fundamental equation for ethanol demonstrates undesirable behavior in several areas and especially in the critical region. In addition, new experimental data have become available in the open literature since the publication of the current correlation. The development of a new fundamental equation for ethanol, in the form of Helmholtz energy as a function of temperature and density, is presented. New, nonlinear fitting techniques, along with the new experimental data, are shown to improve the behavior of the fundamental equation. Ancillary equations are developed, including equations for vapor pressure, saturated liquid density, saturated vapor density, and ideal gas heat capacity. Both the fundamental and ancillary equations are compared to experimental data. The fundamental equation can compute densities to within ±0.2%, heat capacities to within ±1%-2%, and speed of sound to within ±1%. Values of the vapor pressure and saturated vapor densities are represented to within ±1% at temperatures of 300 K and above, while saturated liquid densities are represented to within ±0.3% at temperatures of 200 K and above. The uncertainty of all properties is higher in the critical region and near the triple point. The equation is valid for pressures up to 280 MPa and temperatures from 160 to 650 K.

  19. Military Manpower and the All-Volunteer Force

    DTIC Science & Technology

    1977-09-01

    managed , not with the fundamental concept or policy. Other problems remain, such as those of reserve forces manning and first-term enlisted attrition...ways in which the DoD uses and manages its human resources. The legacy ofthe draft means that fundamental changes in manpower management and...mentioned, but these have been largely problems with the way that the transition was managed , not with the fundamental concept or policy. Other

  20. DNA Origami Seesaws as Comparative Binding Assay

    PubMed Central

    Nickels, Philipp C.; Høiberg, Hans C.; Simmel, Stephanie S.; Holzmeister, Phil; Tinnefeld, Philip

    2016-01-01

    Abstract The application of commonly used force spectroscopy in biological systems is often limited by the need for an invasive tether connecting the molecules of interest to a bead or cantilever tip. Here we present a DNA origami‐based prototype in a comparative binding assay. It has the advantage of in situ readout without any physical connection to the macroscopic world. The seesaw‐like structure has a lever that is able to move freely relative to its base. Binding partners on each side force the structure into discrete and distinguishable conformations. Model experiments with competing DNA hybridisation reactions yielded a drastic shift towards the conformation with the stronger binding interaction. With reference DNA duplexes of tuneable length on one side, this device can be used to measure ligand interactions in comparative assays. PMID:27038073

  1. Sensors, Volume 1, Fundamentals and General Aspects

    NASA Astrophysics Data System (ADS)

    Grandke, Thomas; Ko, Wen H.

    1996-12-01

    'Sensors' is the first self-contained series to deal with the whole area of sensors. It describes general aspects, technical and physical fundamentals, construction, function, applications and developments of the various types of sensors. This volume deals with the fundamentals and common principles of sensors and covers the wide areas of principles, technologies, signal processing, and applications. Contents include: Sensor Fundamentals, e.g. Sensor Parameters, Modeling, Design and Packaging; Basic Sensor Technologies, e.g. Thin and Thick Films, Integrated Magnetic Sensors, Optical Fibres and Intergrated Optics, Ceramics and Oxides; Sensor Interfaces, e.g. Signal Processing, Multisensor Signal Processing, Smart Sensors, Interface Systems; Sensor Applications, e.g. Automotive: On-board Sensors, Traffic Surveillance and Control, Home Appliances, Environmental Monitoring, etc. This volume is an indispensable reference work and text book for both specialits and newcomers, researchers and developers.

  2. The Fundamental Neutron Physics Facilities at NIST.

    PubMed

    Nico, J S; Arif, M; Dewey, M S; Gentile, T R; Gilliam, D M; Huffman, P R; Jacobson, D L; Thompson, A K

    2005-01-01

    The program in fundamental neutron physics at the National Institute of Standards and Technology (NIST) began nearly two decades ago. The Neutron Interactions and Dosimetry Group currently maintains four neutron beam lines dedicated to studies of fundamental neutron interactions. The neutrons are provided by the NIST Center for Neutron Research, a national user facility for studies that include condensed matter physics, materials science, nuclear chemistry, and biological science. The beam lines for fundamental physics experiments include a high-intensity polychromatic beam, a 0.496 nm monochromatic beam, a 0.89 nm monochromatic beam, and a neutron interferometer and optics facility. This paper discusses some of the parameters of the beam lines along with brief presentations of some of the experiments performed at the facilities.

  3. Fundamental understanding of matter: an engineering viewpoint

    SciTech Connect

    Cullingford, H.S.; Cort, G.E.

    1980-01-01

    Fundamental understanding of matter is a continuous process that should produce physical data for use by engineers and scientists in their work. Lack of fundamental property data in any engineering endeavor cannot be mitigated by theoretical work that is not confirmed by physical experiments. An engineering viewpoint will be presented to justify the need for understanding of matter. Examples will be given in the energy engineering field to outline the importance of further understanding of material and fluid properties and behavior. Cases will be cited to show the effects of various data bases in energy, mass, and momentum transfer. The status of fundamental data sources will be discussed in terms of data centers, new areas of engineering, and the progress in measurement techniques. Conclusions and recommendations will be outlined to improve the current situation faced by engineers in carrying out their work. 4 figures.

  4. Fundamental Interventions: How Clinicians Can Address the Fundamental Causes of Disease.

    PubMed

    Reich, Adam D; Hansen, Helena B; Link, Bruce G

    2016-06-01

    In order to enhance the "structural competency" of medicine-the capability of clinicians to address social and institutional determinants of their patients' health-physicians need a theoretical lens to see how social conditions influence health and how they might address them. We consider one such theoretical lens, fundamental cause theory, and propose how it might contribute to a more structurally competent medical profession. We first describe fundamental cause theory and how it makes the social causes of disease and health visible. We then outline the sorts of "fundamental interventions" that physicians might make in order to address the fundamental causes.

  5. Friction Force: From Mechanics to Thermodynamics

    ERIC Educational Resources Information Center

    Ferrari, Christian; Gruber, Christian

    2010-01-01

    We study some mechanical problems in which a friction force is acting on a system. Using the fundamental concepts of state, time evolution and energy conservation, we explain how to extend Newtonian mechanics to thermodynamics. We arrive at the two laws of thermodynamics and then apply them to investigate the time evolution and heat transfer of…

  6. Forces driving epithelial wound healing

    PubMed Central

    Veldhuis, Jim H.; Gupta, Mukund; Colombelli, Julien; Muñoz, José J.; Brodland, G. Wayne; Ladoux, Benoit; Trepat, Xavier

    2015-01-01

    A fundamental feature of multicellular organisms is their ability to self-repair wounds through the movement of epithelial cells into the damaged area. This collective cellular movement is commonly attributed to a combination of cell crawling and “purse-string” contraction of a supracellular actomyosin ring. Here we show by direct experimental measurement that these two mechanisms are insufficient to explain force patterns observed during wound closure. At early stages of the process, leading actin protrusions generate traction forces that point away from the wound, showing that wound closure is initially driven by cell crawling. At later stages, we observed unanticipated patterns of traction forces pointing towards the wound. Such patterns have strong force components that are both radial and tangential to the wound. We show that these force components arise from tensions transmitted by a heterogeneous actomyosin ring to the underlying substrate through focal adhesions. The structural and mechanical organization reported here provides cells with a mechanism to close the wound by cooperatively compressing the underlying substrate. PMID:27340423

  7. Forces driving epithelial wound healing

    NASA Astrophysics Data System (ADS)

    Brugués, Agustí; Anon, Ester; Conte, Vito; Veldhuis, Jim H.; Gupta, Mukund; Colombelli, Julien; Muñoz, José J.; Brodland, G. Wayne; Ladoux, Benoit; Trepat, Xavier

    2014-09-01

    A fundamental feature of multicellular organisms is their ability to self-repair wounds through the movement of epithelial cells into the damaged area. This collective cellular movement is commonly attributed to a combination of cell crawling and `purse-string’ contraction of a supracellular actomyosin ring. Here we show by direct experimental measurement that these two mechanisms are insufficient to explain force patterns observed during wound closure. At early stages of the process, leading actin protrusions generate traction forces that point away from the wound, showing that wound closure is initially driven by cell crawling. At later stages, we observed unanticipated patterns of traction forces pointing towards the wound. Such patterns have strong force components that are both radial and tangential to the wound. We show that these force components arise from tensions transmitted by a heterogeneous actomyosin ring to the underlying substrate through focal adhesions. The structural and mechanical organization reported here provides cells with a mechanism to close the wound by cooperatively compressing the underlying substrate.

  8. DOE Fundamentals Handbook: Mathematics, Volume 2

    SciTech Connect

    Not Available

    1992-06-01

    The Mathematics Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of mathematics and its application to facility operation. The handbook includes a review of introductory mathematics and the concepts and functional use of algebra, geometry, trigonometry, and calculus. Word problems, equations, calculations, and practical exercises that require the use of each of the mathematical concepts are also presented. This information will provide personnel with a foundation for understanding and performing basic mathematical calculations that are associated with various DOE nuclear facility operations.

  9. DOE Fundamentals Handbook: Mathematics, Volume 1

    SciTech Connect

    Not Available

    1992-06-01

    The Mathematics Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of mathematics and its application to facility operation. The handbook includes a review of introductory mathematics and the concepts and functional use of algebra, geometry, trigonometry, and calculus. Word problems, equations, calculations, and practical exercises that require the use of each of the mathematical concepts are also presented. This information will provide personnel with a foundation for understanding and performing basic mathematical calculations that are associated with various DOE nuclear facility operations.

  10. DOE Fundamentals Handbook: Electrical Science, Volume 1

    SciTech Connect

    Not Available

    1992-06-01

    The Electrical Science Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of electrical theory, terminology, and application. The handbook includes information on alternating current (AC) and direct current (DC) theory, circuits, motors, and generators; AC power and reactive components; batteries; AC and DC voltage regulators; transformers; and electrical test instruments and measuring devices. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility electrical equipment.

  11. DOE Fundamentals Handbook: Electrical Science, Volume 2

    SciTech Connect

    Not Available

    1992-06-01

    The Electrical Science Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding terminology, and application. The handbook includes information on alternating current (AC) and direct current (DC) theory, circuits, motors, and generators; AC power and reactive components; batteries; AC and DC voltage regulators; transformers; and electrical test instruments and measuring devices. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility electrical equipment.

  12. Dark Energy: A Crisis for Fundamental Physics

    ScienceCinema

    Stubbs, Christopher [Harvard University, Cambridge, Massachusetts, USA

    2016-07-12

    Astrophysical observations provide robust evidence that our current picture of fundamental physics is incomplete. The discovery in 1998 that the expansion of the Universe is accelerating (apparently due to gravitational repulsion between regions of empty space!) presents us with a profound challenge, at the interface between gravity and quantum mechanics. This "Dark Energy" problem is arguably the most pressing open question in modern fundamental physics. The first talk will describe why the Dark Energy problem constitutes a crisis, with wide-reaching ramifications. One consequence is that we should probe our understanding of gravity at all accessible scales, and the second talk will present experiments and observations that are exploring this issue.

  13. DOE Fundamentals Handbook: Electrical Science, Volume 4

    SciTech Connect

    Not Available

    1992-06-01

    The Electrical Science Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of electrical theory, terminology, and application. The handbook includes information on alternating current (AC) and direct current (DC) theory, circuits, motors, and generators; AC power and reactive transformers; and electrical test components; batteries; AC and DC voltage regulators; instruments and measuring devices. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility electrical equipment.

  14. Talin mediated force transmission and mechanosensing

    NASA Astrophysics Data System (ADS)

    Yan, Jie; Yao, Mingxi; Goult, Benjamin; Sheetz, Michael

    Cells adhere to extracellular matrix (ECM) through focal adhesion. Talin is a cytoplasmic adapter protein that links the actin cytoskeleton to focal adhesion, playing a central role in regulation of cell spreading and migration. Talin's functions depend on the binding of talin rod domains to a cytoplasmic protein vinculin in a force dependent manner. By stretching full-length talin rod using magnetic tweezers, we have determined the force-dependent unfolding and refolding rates of subdomains in talin rod. Kinetics simulations based on these rates have revealed that talin rod can serve as a force buffer, capable of maintaining tension in talin in a range of 5-10 pN over a wide range of extension change of talin rod from 50 nm to 400 nm. Further, this level of force is found able to expose the cryptic vinculin-binding sites, promoting subsequent binding of the head domain of vinculin with a nano Molar affinity. Such a force-sensitive interaction between talin rod and vinculin is described by a force-dependent dissociation constant derived based on the mechanical stability of the talin rod domains. Together, these results provide important insights into the mechanosensing at focal adhesion that is crucial for cells to sense and respond to their microenvironments. The research is supported by the National Research Foundation of Singapore through Mechanobiology Institute and NRF Investigatorship to YJ.

  15. Radio and Television Repairer Fundamentals. Student's Manual.

    ERIC Educational Resources Information Center

    Maul, Chuck

    This self-contained student manual on fundamentals of radio and television repair is designed to help trade and industrial students relate work experience on the job to information studied at school. Designed for individualized instruction under the supervision of a coordinator or instructor, the manual has 9 sections, each containing 2 to 10…

  16. Fundamental Concepts Bridging Education and the Brain

    ERIC Educational Resources Information Center

    Masson, Steve; Foisy, Lorie-Marlène Brault

    2014-01-01

    Although a number of papers have already discussed the relevance of brain research for education, the fundamental concepts and discoveries connecting education and the brain have not been systematically reviewed yet. In this paper, four of these concepts are presented and evidence concerning each one is reviewed. First, the concept of…

  17. A Fundamental Theorem on Particle Acceleration

    SciTech Connect

    Xie, Ming

    2003-05-01

    A fundamental theorem on particle acceleration is derived from the reciprocity principle of electromagnetism and a rigorous proof of the theorem is presented. The theorem establishes a relation between acceleration and radiation, which is particularly useful for insightful understanding of and practical calculation about the first order acceleration in which energy gain of the accelerated particle is linearly proportional to the accelerating field.

  18. Uncovering Racial Bias in Nursing Fundamentals Textbooks.

    ERIC Educational Resources Information Center

    Byrne, Michelle M.

    2001-01-01

    The portrayal of African Americans in nursing fundamentals textbooks was analyzed, resulting in 11 themes in the areas of history, culture, and physical assessment. Few African American leaders were included, and racial bias and stereotyping were apparent. Differences were often discussed using Eurocentric norms, and language tended to minimize…

  19. Biological and cognitive underpinnings of religious fundamentalism.

    PubMed

    Zhong, Wanting; Cristofori, Irene; Bulbulia, Joseph; Krueger, Frank; Grafman, Jordan

    2017-04-06

    Beliefs profoundly affect people's lives, but their cognitive and neural pathways are poorly understood. Although previous research has identified the ventromedial prefrontal cortex (vmPFC) as critical to representing religious beliefs, the means by which vmPFC enables religious belief is uncertain. We hypothesized that the vmPFC represents diverse religious beliefs and that a vmPFC lesion would be associated with religious fundamentalism, or the narrowing of religious beliefs. To test this prediction, we assessed religious adherence with a widely-used religious fundamentalism scale in a large sample of 119 patients with penetrating traumatic brain injury (pTBI). If the vmPFC is crucial to modulating diverse personal religious beliefs, we predicted that pTBI patients with lesions to the vmPFC would exhibit greater fundamentalism, and that this would be modulated by cognitive flexibility and trait openness. Instead, we found that participants with dorsolateral prefrontal cortex (dlPFC) lesions have fundamentalist beliefs similar to patients with vmPFC lesions and that the effect of a dlPFC lesion on fundamentalism was significantly mediated by decreased cognitive flexibility and openness. These findings indicate that cognitive flexibility and openness are necessary for flexible and adaptive religious commitment, and that such diversity of religious thought is dependent on dlPFC functionality.

  20. Fundamental Movement Skill Proficiency amongst Adolescent Youth

    ERIC Educational Resources Information Center

    O' Brien, Wesley; Belton, Sarahjane; Issartel, Johann

    2016-01-01

    Background: Literature suggests that physical education programmes ought to provide intense instruction towards basic movement skills needed to enjoy a variety of physical activities. Fundamental movement skills (FMS) are basic observable patterns of behaviour present from childhood to adulthood (e.g. run, skip and kick). Recent evidence indicates…

  1. Mathematical Literacy--It's Become Fundamental

    ERIC Educational Resources Information Center

    McCrone, Sharon Soucy; Dossey, John A.

    2007-01-01

    The rising tide of numbers and statistics in daily life signals a need for a fundamental broadening of the concept of literacy: mathematical literacy assuming a coequal role in the curriculum alongside language-based literacy. Mathematical literacy is not about studying higher levels of formal mathematics, but about making math relevant and…

  2. Fundamental Theorems of Algebra for the Perplexes

    ERIC Educational Resources Information Center

    Poodiak, Robert; LeClair, Kevin

    2009-01-01

    The fundamental theorem of algebra for the complex numbers states that a polynomial of degree n has n roots, counting multiplicity. This paper explores the "perplex number system" (also called the "hyperbolic number system" and the "spacetime number system") In this system (which has extra roots of +1 besides the usual [plus or minus]1 of the…

  3. Course Objectives: Electronic Fundamentals, EL16.

    ERIC Educational Resources Information Center

    Wilson, David H.

    The general objective, recommended text, and specific objectives of a course titled "Electronic Fundamentals," as offered at St. Lawrence College of Applied Arts and Technology, are provided. The general objective of the course is "to acquire an understanding of diodes, transistors, and tubes, and so be able to analyze the operation…

  4. Fundamental problems in provable security and cryptography.

    PubMed

    Dent, Alexander W

    2006-12-15

    This paper examines methods for formally proving the security of cryptographic schemes. We show that, despite many years of active research and dozens of significant results, there are fundamental problems which have yet to be solved. We also present a new approach to one of the more controversial aspects of provable security, the random oracle model.

  5. [Reading Is Fundamental: Pamphlets and Newsletters].

    ERIC Educational Resources Information Center

    Smithsonian Institution, Washington, DC.

    These pamphlets and newsletters are products of the Reading Is Fundamental (RIF) program, which provides free and inexpensive books to children through a variety of community organizations throughout the country. The newsletter appears monthly and contains reports on specific programs, trends in the national program, RIF involvement with other…

  6. Fundamentals of Energy Technology. Energy Technology Series.

    ERIC Educational Resources Information Center

    Center for Occupational Research and Development, Inc., Waco, TX.

    This course in fundamentals of energy technology is one of 16 courses in the Energy Technology Series developed for an Energy Conservation-and-Use Technology curriculum. Intended for use in two-year postsecondary technical institutions to prepare technicians for employment, the courses are also useful in industry for updating employees in…

  7. Solar Energy: Solar System Design Fundamentals.

    ERIC Educational Resources Information Center

    Knapp, Henry H., III

    This module on solar system design fundamentals is one of six in a series intended for use as supplements to currently available materials on solar energy and energy conservation. Together with the recommended texts and references (sources are identified), these modules provide an effective introduction to energy conservation and solar energy…

  8. Fundamental Movement Skills and Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Staples, Kerri L.; Reid, Greg

    2010-01-01

    Delays and deficits may both contribute to atypical development of movement skills by children with ASD. Fundamental movement skills of 25 children with autism spectrum disorders (ASD) (ages 9-12 years) were compared to three typically developing groups using the "Test of Gross Motor Development" ("TGMD-2"). The group matched on chronological age…

  9. Fundamental Movement Skills: An Important Focus

    ERIC Educational Resources Information Center

    Barnett, Lisa M.; Stodden, David; Cohen, Kristen E.; Smith, Jordan J.; Lubans, David Revalds; Lenoir, Matthieu; Iivonen, Susanna; Miller, Andrew D.; Laukkanen, Arto; Dudley, Dean; Lander, Natalie J.; Brown, Helen; Morgan, Philip J.

    2016-01-01

    Purpose: Recent international conference presentations have critiqued the promotion of fundamental movement skills (FMS) as a primary pedagogical focus. Presenters have called for a debate about the importance of, and rationale for teaching FMS, and this letter is a response to that call. The authors of this letter are academics who actively…

  10. Fundamental Ideas: Rethinking Computer Science Education.

    ERIC Educational Resources Information Center

    Schwill, Andreas

    1997-01-01

    Describes a way to teach computer science based on J.S. Bruner's psychological framework. This educational philosophy has been integrated into two German federal state schools. One way to cope with the rapid developments in computer science is to teach the fundamental ideas, principles, methods, and ways of thinking to K-12 students, (PEN)

  11. Man's Size in Terms of Fundamental Constants.

    ERIC Educational Resources Information Center

    Press, William H.

    1980-01-01

    Reviews calculations that derive an order of magnitude expression for the size of man in terms of fundamental constants, assuming that man satifies these three properties: he is made of complicated molecules; he requires an atmosphere which is not hydrogen and helium; he is as large as possible. (CS)

  12. Fundamentals of Library Science. Library Science 424.

    ERIC Educational Resources Information Center

    Foster, Donald L.

    An introductory letter, a list of general instructions on how to proceed with a correspondence course, a syllabus, and an examination request form are presented for a correspondence course in the fundamentals of library science offered by the University of New Mexico's Division of Continuing Education and Community Services. The course is a survey…

  13. The Failed Feminist Challenge to "Fundamental Epistemology"

    ERIC Educational Resources Information Center

    Pinnick, Cassandra L.

    2005-01-01

    Despite volumes written in the name of the new and fundamental feminist project in philosophy of science, and conclusions drawn on the strength of the hypothesis that the feminist project will boost progress toward cognitive aims associated with science and rationality (and, one might add, policy decisions enacted in the name of these aims), the…

  14. Fundamental and Gradient Differences in Language Development

    ERIC Educational Resources Information Center

    Herschensohn, Julia

    2009-01-01

    This article reexamines Bley-Vroman's original (1990) and evolved fundamental difference hypothesis that argues that differences in path and endstate of first language acquisition and adult foreign language learning result from differences in the acquisition procedure (i.e., language faculty and cognitive strategies, respectively). The evolved…

  15. Workshop on Fundamental Science using Pulsed Power

    SciTech Connect

    Wootton, Alan

    2016-02-20

    The project objective was to fund travel to a workshop organized by the Institute for High Energy Density Science (IHEDS) at the University of Texas at Austin. In so doing the intent was to a) Grow the national academic High Energy Density Science (HEDS) community, b) Expand high impact, discovery driven fundamental HEDS, and c) Facilitate user-oriented research

  16. Fundamentals of Electric Circuits. Laboratory Manual.

    ERIC Educational Resources Information Center

    Wentworth Inst., Boston, MA.

    This laboratory manual consists of three major sections. The first section deals with Direct Current (DC) fundamentals, and is divided into 17 phases leading towards the design and analysis of a DC ammeter and a DC voltmeter. Each phase consists of facts and problems to be learned in the phase, preliminary discussion, laboratory operation…

  17. The equivalent fundamental-mode source

    SciTech Connect

    Spriggs, G.D.; Busch, R.D.; Sakurai, Takeshi; Okajima, Shigeaki

    1997-02-01

    In 1960, Hansen analyzed the problem of assembling fissionable material in the presence of a weak neutron source. Using point kinetics, he defined the weak source condition and analyzed the consequences of delayed initiation during ramp reactivity additions. Although not clearly stated in Hansen`s work, the neutron source strength that appears in the weak source condition corresponds to the equivalent fundamental-mode source. In this work, we describe the concept of an equivalent fundamental-mode source and we derive a deterministic expression for a factor, g*, that converts any arbitrary source distribution to an equivalent fundamental-mode source. We also demonstrate a simplified method for calculating g* in subcritical systems. And finally, we present a new experimental method that can be employed to measure the equivalent fundamental-mode source strength in a multiplying assembly. We demonstrate the method on the zero-power, XIX-1 assembly at the Fast Critical Assembly (FCA) Facility, Japan Atomic Energy Research Institute (JAERI).

  18. Mechanical force characterization in manipulating live cells with optical tweezers.

    PubMed

    Wu, Yanhua; Sun, Dong; Huang, Wenhao

    2011-02-24

    Laser trapping with optical tweezers is a noninvasive manipulation technique and has received increasing attentions in biological applications. Understanding forces exerted on live cells is essential to cell biomechanical characterizations. Traditional numerical or experimental force measurement assumes live cells as ideal objects, ignoring their complicated inner structures and rough membranes. In this paper, we propose a new experimental method to calibrate the trapping and drag forces acted on live cells. Binding a micro polystyrene sphere to a live cell and moving the mixture with optical tweezers, we can obtain the drag force on the cell by subtracting the drag force on the sphere from the total drag force on the mixture, under the condition of extremely low Reynolds number. The trapping force on the cell is then obtained from the drag force when the cell is in force equilibrium state. Experiments on numerous live cells demonstrate the effectiveness of the proposed force calibration approach.

  19. Coupling mechanical forces to electrical signaling: molecular motors and the intracellular transport of ion channels.

    PubMed

    Barry, Joshua; Gu, Chen

    2013-04-01

    Proper localization of various ion channels is fundamental to neuronal functions, including postsynaptic potential plasticity, dendritic integration, action potential initiation and propagation, and neurotransmitter release. Microtubule-based forward transport mediated by kinesin motors plays a key role in placing ion channel proteins to correct subcellular compartments. PDZ- and coiled-coil-domain proteins function as adaptor proteins linking ionotropic glutamate and GABA receptors to various kinesin motors, respectively. Recent studies show that several voltage-gated ion channel/transporter proteins directly bind to kinesins during forward transport. Three major regulatory mechanisms underlying intracellular transport of ion channels are also revealed. These studies contribute to understanding how mechanical forces are coupled to electrical signaling and illuminating pathogenic mechanisms in neurodegenerative diseases.

  20. Photoelectron Spectroscopy and Theoretical Studies of Anion-pi Interactions: Binding Strength and Anion Specificity

    SciTech Connect

    Zhang, Jian; Zhou, Bin; Sun, Zhenrong; Wang, Xue B.

    2015-01-01

    Proposed in theory and confirmed to exist, anion–π interactions have been recognized as new and important non-covalent binding forces. Despite extensive theoretical studies, numerous crystal structural identifications, and a plethora of solution phase investigations, intrinsic anion–π interaction strengths that are free from complications of condensed phases’ environments, have not been directly measured in the gas phase. Herein we present a joint photoelectron spectroscopic and theoretical study on this subject, in which tetraoxacalix[2]arene[2]triazine 1, an electron-deficient and cavity self-tunable macrocyclic was used as a charge-neutral molecular host to probe its interactions with a series of anions with distinctly different shapes and charge states (spherical halides Cl⁻, Br⁻, I⁻, linear thiocyanate SCN⁻, trigonal planar nitrate NO₃⁻, pyramidic iodate IO₃⁻, and tetrahedral sulfate SO₄²⁻). The binding energies of the resultant gaseous 1:1 complexes (1•Cl⁻,1•Br⁻, 1•I⁻, 1•SCN⁻, 1•NO₃⁻, 1•IO₃⁻ and 1•SO₄²⁻) were directly measured experimentally, exhibiting substantial non-covalent interactions with pronounced anion specific effects. The binding strengths of Cl⁻, NO₃⁻, IO₃⁻ with 1 are found to be strongest among all singly charged anions, amounting to ca. 30 kcal/mol, but only about 40% of that between 1 and SO₄²⁻. Quantum chemical calculations reveal that all anions reside in the center of the cavity of 1 with anion–π binding motif in the complexes’ optimized structures, where 1 is seen to be able to self-regulate its cavity structure to accommodate anions of different geometries and three-dimensional shapes. Electron density surface and natural bond orbital charge distribution analysis further support anion–π binding formation. The calculated binding energies of the anions and 1 nicely reproduce the experimentally estimated electron binding energy increase. This work

  1. Nuclear actin-binding proteins as modulators of gene transcription.

    PubMed

    Gettemans, Jan; Van Impe, Katrien; Delanote, Veerle; Hubert, Thomas; Vandekerckhove, Joël; De Corte, Veerle

    2005-10-01

    Dynamic transformations in the organization of the cellular microfilament system are the driving force behind fundamental biological processes such as cellular motility, cytokinesis, wound healing and secretion. Eukaryotic cells express a plethora of actin-binding proteins (ABPs) allowing cells to control the organization of the actin cytoskeleton in a flexible manner. These structural proteins were, not surprisingly, originally described as (major) constituents of the cytoplasm. However, in recent years, there has been a steady flow of reports detailing not only translocation of ABPs into and out of the nucleus but also describing their role in the nuclear compartment. This review focuses on recent developments pertaining to nucleocytoplasmic transport of ABPs, including their mode of translocation and nuclear function. In particular, evidence that structurally and functionally unrelated cytoplasmic ABPs regulate transcription activation by various nuclear (steroid hormone) receptors is steadily accruing. Furthermore, the recent finding that actin is a necessary component of the RNA polymerase II-containing preinitiation complex opens up new opportunities for nuclear ABPs in gene transcription regulation.

  2. Toward Automated Benchmarking of Atomistic Force Fields: Neat Liquid Densities and Static Dielectric Constants from the ThermoML Data Archive.

    PubMed

    Beauchamp, Kyle A; Behr, Julie M; Rustenburg, Ariën S; Bayly, Christopher I; Kroenlein, Kenneth; Chodera, John D

    2015-10-08

    Atomistic molecular simulations are a powerful way to make quantitative predictions, but the accuracy of these predictions depends entirely on the quality of the force field employed. Although experimental measurements of fundamental physical properties offer a straightforward approach for evaluating force field quality, the bulk of this information has been tied up in formats that are not machine-readable. Compiling benchmark data sets of physical properties from non-machine-readable sources requires substantial human effort and is prone to the accumulation of human errors, hindering the development of reproducible benchmarks of force-field accuracy. Here, we examine the feasibility of benchmarking atomistic force fields against the NIST ThermoML data archive of physicochemical measurements, which aggregates thousands of experimental measurements in a portable, machine-readable, self-annotating IUPAC-standard format. As a proof of concept, we present a detailed benchmark of the generalized Amber small-molecule force field (GAFF) using the AM1-BCC charge model against experimental measurements (specifically, bulk liquid densities and static dielectric constants at ambient pressure) automatically extracted from the archive and discuss the extent of data available for use in larger scale (or continuously performed) benchmarks. The results of even this limited initial benchmark highlight a general problem with fixed-charge force fields in the representation low-dielectric environments, such as those seen in binding cavities or biological membranes.

  3. Fundamental Physics for Probing and Imaging

    NASA Astrophysics Data System (ADS)

    Allison, Wade

    2006-12-01

    This book addresses the question 'What is physics for?' Physics has provided many answers for mankind by extending his ability to see. Modern technology has enabled the power of physics to see into objects to be used in archaeology, medicine including therapy, geophysics, forensics and other spheres important to the good of society. The book looks at the fundamental physics of the various methods and how they are used by technology. These methods are magnetic resonance, ionising radiation and sound. By taking a broad view over the whole field it encourages comparisons, but also addresses questions of risk and benefit to society from a fundamental viewpoint. This textbook has developed from a course given to third year students at Oxford and is written so that it can be used coherently as a basis for shortened courses by omitting a number of chapters.

  4. Fundamental implications of intergalactic magnetic field observations

    NASA Astrophysics Data System (ADS)

    Vachaspati, Tanmay

    2017-03-01

    Helical intergalactic magnetic fields at the ˜10-14 G level on ˜10 Mpc length scales are indicated by current gamma ray observations. The existence of magnetic fields in cosmic voids and their nontrivial helicity suggest that they must have originated in the early Universe and thus have implications for the fundamental interactions. We derive the spectrum of the cosmological magnetic field as implied by observations and MHD evolution, yielding order nano Gauss fields on kiloparsec scales and a "large helicity puzzle" that needs to be resolved by the fundamental interactions. The importance of C P violation and a possible crucial role for chiral effects or axions in the early Universe are pointed out.

  5. Fundamental physics at the threshold of discovery

    NASA Astrophysics Data System (ADS)

    Toro, Natalia

    This thesis is divided into two parts: one driven by theory, the other by experiment. The first two chapters consider two model-building challenges: the little hierarchy of supersymmetry and the slowness of confinement in Randall-Sundrum models. In the third chapter, we turn to the question of determining the nature of fundamental physics at the TeV scale from LHC data. Crucial to this venture is a characterization for models of new physics. We present On-Shell Effective Theories (OSETs), a characterization of hadron collider data in terms of masses, production cross sections, and decay modes of new particles. We argue that such a description can likely be obtained from ≲ 1 year of LHC data, and in many scenarios is an essential intermediate step in describing fundamental physics at the TeV scale.

  6. 40 year retrospective of fundamental mechanisms

    NASA Astrophysics Data System (ADS)

    Soileau, M. J.

    2008-10-01

    Fundamental mechanisms of laser induced damage (LID) have been one of the most controversial topics during the forty years of the Boulder Damage Symposium (Ref. 1.) LID is fundamentally a very nonlinear process and sensitive to a variety of parameters including wavelength, pulse width, spot size, focal conditions, material band gap, thermal-mechanical prosperities, and component design considerations. The complex interplay of many of these parameters and sample to sample materials variations combine to make detailed, first principle, models very problematic at best. The phenomenon of self-focusing, the multi spatial and temporal mode structure of most lasers, and the fact that samples are 'consumed' in testing complicate experiential results. This paper presents a retrospective of the work presented at this meeting.

  7. Force-induced selective dissociation of noncovalent antibody-antigen bonds.

    PubMed

    Yao, Li; Xu, Shoujun

    2012-08-23

    Specific noncovalent binding between antibody and antigen molecules is the basis for molecular recognition in biochemical processes. Quantitative investigation of the binding forces could lead to molecular specific analysis and potentially mechanical manipulation of these processes. Using our force-induced remnant magnetization spectroscopy, we revealed a well-defined binding force for the bonds between mouse immunoglobulin G and magnetically labeled α-mouse immunoglobulin G. The force was calibrated to be 120 ± 15 pN. In comparison, the binding force was only 17 ± 3 pN for physisorption and much higher than 120 pN for biotin-streptavidin bonds. A unique rebinding method was used to confirm the dissociation of the antibody-antigen bonds. A well-defined and molecule-specific binding force opens a new avenue for distinguishing different noncovalent bonds in biochemical processes.

  8. DOE fundamentals handbook: Mechanical science. Volume 2

    SciTech Connect

    Not Available

    1993-01-01

    The Mechanical Science Handbook was developed to assist nuclear facility operating contractors in providing operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of mechanical components and mechanical science. The handbook includes information diesel engines, heat exchangers, pumps, valves, and miscellaneous mechanical components. This information will provide personnel with a foundation for understanding the construction and operation of mechanical components that are associated with various DOE nuclear facility operations and maintenance.

  9. Baryogenesis and its implications to fundamental physics

    SciTech Connect

    Yoshimura, M.

    2008-08-08

    In this talk I shall explain some basic concepts of baryogenesis and leptogenesis theory, and a new idea of experimental method of verification of fundamental ingredients of leptogenesis theory; the Majorana nature and the absolute magnitude of neutrino masses. Both of these are important to the quest of physics beyond the standard theory, and have far reaching implications irrespective of any particular medel of leptogenesis. If this new method works ideally, there is even a further possibility of detecting relic neutrinos.

  10. GN and C Fault Protection Fundamentals

    NASA Technical Reports Server (NTRS)

    Rasmussen, Robert D.

    2008-01-01

    This is a companion presentation for a paper by the same name for the same conference. The objective of this paper is to shed some light on the fundamentals of fault tolerant design for GN&C. The common heritage of ideas behind both faulted and normal operation is explored, as is the increasingly indistinct line between these realms in complex missions. Techniques in common practice are then evaluated in this light to suggest a better direction for future efforts.

  11. New Fundamental Station in Ny-Alesund

    NASA Technical Reports Server (NTRS)

    Langkaas, Line; Dahlen, Terje; Opseth, Per Erik

    2010-01-01

    The Norwegian Mapping Authority s (NMA) geodetic observatory has been operating in Ny-Alesund since 1994. To adapt to the VLBI2010 standard and extend our activity to also integrate SLR, NMA is in the process of funding a new fundamental station. Handling more intensive observations in real time requires a fiber optic cable to Ny-Alesund. The Norwegian Mapping Authority is currently applying for project funding of 26 million euros.

  12. Chiral phases of fundamental and adjoint quarks

    SciTech Connect

    Natale, A. A.

    2016-01-22

    We consider a QCD chiral symmetry breaking model where the gap equation contains an effective confining propagator and a dressed gluon propagator with a dynamically generated mass. This model is able to explain the ratios between the chiral transition and deconfinement temperatures in the case of fundamental and adjoint quarks. It also predicts the recovery of the chiral symmetry for a large number of quarks (n{sub f} ≈ 11 – 13) in agreement with lattice data.

  13. DOE fundamentals handbook: Material science. Volume 1

    SciTech Connect

    Not Available

    1993-01-01

    This handbook was developed to assist nuclear facility operating contractors in providing operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of the structure and properties of metals. This volume contains the two modules: structure of metals (bonding, common lattic types, grain structure/boundary, polymorphis, alloys, imperfections in metals) and properties of metals (stress, strain, Young modulus, stress-strain relation, physical properties, working of metals, corrosion, hydrogen embrittlement, tritium/material compatibility).

  14. DOE fundamentals handbook: Material science. Volume 1

    SciTech Connect

    Not Available

    1993-01-01

    The Mechanical Science Handbook was developed to assist nuclear facility operating contractors in providing operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of mechanical components and mechanical science. The handbook includes information on diesel engines, heat exchangers, pumps, valves, and miscellaneous mechanical components. This information will provide personnel with a foundation for understanding the construction and operation of mechanical components that are associated with various DOE nuclear facility operations and maintenance.

  15. Chiral phases of fundamental and adjoint quarks

    NASA Astrophysics Data System (ADS)

    Natale, A. A.

    2016-01-01

    We consider a QCD chiral symmetry breaking model where the gap equation contains an effective confining propagator and a dressed gluon propagator with a dynamically generated mass. This model is able to explain the ratios between the chiral transition and deconfinement temperatures in the case of fundamental and adjoint quarks. It also predicts the recovery of the chiral symmetry for a large number of quarks (nf ≈ 11 - 13) in agreement with lattice data.

  16. Fundamental plasma emission involving ion sound waves

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1987-01-01

    The theory for fundamental plasma emission by the three-wave processes L + or - S to T (where L, S and T denote Langmuir, ion sound and transverse waves, respectively) is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes are identified. In addition the rates, path-integrated wave temperatures, and limits on the brightness temperature of the radiation are derived.

  17. Fundamentals of Physics, Extended 7th Edition

    NASA Astrophysics Data System (ADS)

    Halliday, David; Resnick, Robert; Walker, Jearl

    2004-05-01

    No other book on the market today can match the 30-year success of Halliday, Resnick and Walker's Fundamentals of Physics! Fundamentals of Physics, 7th Edition and the Extended Version, 7th Edition offer a solid understanding of fundamental physics concepts, helping readers apply this conceptual understanding to quantitative problem solving, in a breezy, easy-to-understand style. A unique combination of authoritative content and stimulating applications. * Numerous improvements in the text, based on feedback from the many users of the sixth edition (both instructors and students) * Several thousand end-of-chapter problems have been rewritten to streamline both the presentations and answers * 'Chapter Puzzlers' open each chapter with an intriguing application or question that is explained or answered in the chapter * Problem-solving tactics are provided to help beginning Physics students solve problems and avoid common error * The first section in every chapter introduces the subject of the chapter by asking and answering, "What is Physics?" as the question pertains to the chapter * Numerous supplements available to aid teachers and students The extended edition provides coverage of developments in Physics in the last 100 years, including: Einstein and Relativity, Bohr and others and Quantum Theory, and the more recent theoretical developments like String Theory.

  18. Fundamental Processes in Plasmas. Final report

    SciTech Connect

    O'Neil, Thomas M.; Driscoll, C. Fred

    2009-11-30

    This research focuses on fundamental processes in plasmas, and emphasizes problems for which precise experimental tests of theory can be obtained. Experiments are performed on non-neutral plasmas, utilizing three electron traps and one ion trap with a broad range of operating regimes and diagnostics. Theory is focused on fundamental plasma and fluid processes underlying collisional transport and fluid turbulence, using both analytic techniques and medium-scale numerical simulations. The simplicity of these systems allows a depth of understanding and a precision of comparison between theory and experiment which is rarely possible for neutral plasmas in complex geometry. The recent work has focused on three areas in basic plasma physics. First, experiments and theory have probed fundamental characteristics of plasma waves: from the low-amplitude thermal regime, to inviscid damping and fluid echoes, to cold fluid waves in cryogenic ion plasmas. Second, the wide-ranging effects of dissipative separatrices have been studied experimentally and theoretically, finding novel wave damping and coupling effects and important plasma transport effects. Finally, correlated systems have been investigated experimentally and theoretically: UCSD experients have now measured the Salpeter correlation enhancement, and theory work has characterized the 'guiding center atoms of antihydrogen created at CERN.

  19. Binding energies of hypernuclei and hypernuclear interactions

    SciTech Connect

    Bodmer, A.R. |; Murali, S.; Usmani, Q.N.

    1996-05-01

    In part 1 the effect of nuclear core dynamics on the binding energies of {Lambda} hypernuclei is discussed in the framework of variational correlated wave functions. In particular, the authors discuss a new rearrangement energy contribution and its effect on the core polarization. In part 2 they consider the interpretation of the {Lambda} single-particle energy in terms of basic {Lambda}-nuclear interactions using a local density approximation based on a Fermi hypernetted chain calculation of the A binding to nuclear matter. To account for the data strongly repulsive 3-body {Lambda}NN forces are required. Also in this framework they discuss core polarization for medium and heavier hypernuclei.

  20. Ureaplasma urealyticum binds mannose-binding lectin.

    PubMed

    Benstein, Barbara D; Ourth, Donald D; Crouse, Dennis T; Shanklin, D Radford

    2004-10-01

    Mannose-binding C-type lectin (MBL) is an important component of innate immunity in mammals. Mannose-binding lectin (MBL), an acute phase protein, acts as an opsonin for phagocytosis and also activates the mannan-binding lectin complement pathway. It may play a particularly significant role during infancy before adequate specific protection can be provided by the adaptive immune system. Ureaplasma urealyticum has been linked to several diseases including pneumonia and chronic lung disease (CLD) in premature infants. We therefore investigated the ability of U. urealyticum to bind MBL. A guinea pig IgG anti-rabbit-MBL antiserum was produced. An immunoblot (dot-blot) assay done on nitrocellulose membrane determined that the anti-MBL antibody had specificity against both rabbit and human MBL. Pure cultures of U. urealyticum, serotype 3, were used to make slide preparations. The slides containing the organisms were then incubated with nonimmune rabbit serum containing MBL. Ureaplasma was shown to bind rabbit MBL with an immunocytochemical assay using the guinea pig IgG anti-rabbit MBL antiserum. Horseradish peroxidase (HRP)-labeled anti-guinea pig IgG was used to localize the reaction. The anti-MBL antiserum was also used in an immunocytochemical assay to localize U. urealyticum in histological sections of lungs from mice specifically infected with this organism. The same method also indicated binding of MBL by ureaplasma in human lung tissue obtained at autopsy from culture positive infants. Our results demonstrate that ureaplasma has the capacity to bind MBL. The absence of MBL may play a role in the predisposition of diseases related to this organism.

  1. PREFACE New developments in nanopore research—from fundamentals to applications New developments in nanopore research—from fundamentals to applications

    NASA Astrophysics Data System (ADS)

    Albrecht, Tim; Edel, Joshua B.; Winterhalter, Mathias

    2010-11-01

    Biological and solid-state nanopores are an exciting field of research, which has seen a rapid development over the last 10 to 20 years. Activities in this area range from theoretical and experimental work on the underlying fundamental (bio)physics to applications in single-molecule biosensing. And while the prospect of DNA sequencing continues to be a major driving force, other applications with potentially similar impact begin to emerge, for example the detection of small molecules, proteins, protein/protein and protein/DNA complexes, and RNA to name just a few. It has also become apparent that both classes of nanopore devices have intrinsic advantages and disadvantages; hybrid structures combining the better of the two worlds would be a logical consequence and are beginning to appear in the literature. Many other highly innovative ideas and concepts continue to emerge and the number of nanopore-related publications has increased drastically over recent years. We found that more than 100 research groups worldwide are active in this area; several commercial settings are in the process of translating fundamental research into real-life applications. We therefore felt that now is the right time to showcase these new developments in a special issue: to inspire researchers active in the field, to liberate inherent synergies, and not least, to demonstrate to the outside world the current state-of-the-art and future opportunities. The title 'New developments in nanopore research—from fundamentals to applications' in some way reflects these ambitions and, even though not everyone invited was able to contribute, we were able to assemble 34 high-quality research papers from all over the world. We would like to acknowledge and thank all the contributors for their submissions, which made this special issue possible in the first place. Moreover, we would like to thank the staff at IOP Publishing for helping us with the administrative aspects and for coordinating the

  2. Fundamental Physics Program and the NASA Mission

    NASA Technical Reports Server (NTRS)

    Trinh, Eugene

    2003-01-01

    The accomplishments of Physics, the increasing power of its instruments, and its expanding reach into other sciences have generated an unprecedented set of scientific opportunities. The committee has identified six such Grand Challenges listed below in no particular order: Developing quantum technologies. Creating new materials. Understanding complex systems. Unifying the forces of Nature. Exploring the universe Applying Physics to Biology.

  3. Fundamental behavior of a model biomolecular amphiphile system

    NASA Astrophysics Data System (ADS)

    Haverstick, Kraig Leonard

    An interest in the fundamental interactions between protein components, in the form of either single amino acids or peptides, unifies the work represented in this thesis. These fundamental interactions drive protein folding, enzyme-substrate binding, and cell adhesion to extracellular ligands. The technology of lipidation was used to isolate these protein interactions. Lipidation of a water-soluble amino acid or peptide sequence confined the protein component to the air-water interface or to a self-assembled structure in water. Compression of the molecules at the air-water interface ordered them into a solid-like monolayer, and Langmuir-Blodgett deposition produced a surface modification with protein component presented in a controlled, orderly manner. These molecules have potential applications as biomaterials coatings or drug delivery devices. A method for determination of specific hydrogen bonding interactions through cocrystallization of two complementary peptide sequences is also described. In order to understand the effect of lipidation and lipid structure on peptide behavior, a comprehensive study of tail designs was first undertaken. Tail length, linkage group, linker, spacer length, and headgroup chirality, orientation, and terminal group were systematically varied in simple amino acid amphiphiles. Monolayer assembly, thermal stability, and structure were studied with Langmuir isotherms and Fourier transform infrared spectroscopy. Each part of the tail structure was found to affect monolayer behavior. With lipid effects better understood, peptide amphiphiles were designed, synthesized, and studied using peptide sequences of importance for cell adhesion. The sequences [IV-H1] from type IV collagen and Arg-Gly-Asp (RGD) were lipidated and characterized in monolayers by Langmuir isotherms and Fourier transform infrared spectroscopy. Biological functionality was determined by melanoma cell spreading assays. Peptide presentation was found to be critical for

  4. Nucleolonema as a fundamental substructure of the nucleolus.

    PubMed

    Sato, Seiichi; Yano, Hiroyuki; Makimoto, Yuji; Kaneta, Tsuyoshi; Sato, Yasushi

    2005-04-01

    The nucleolus is the most obvious structure in the eukaryotic nucleus. It is known to be a ribosome-producing apparatus where ribosomal (r) DNA is transcribed and the primary rRNA transcripts are processed to produce three of the four rRNA species. Electron microscopy has shown that the nucleolus consists of three major components, a dense fibrillar component (DFC), a granular component (GC) and a fibrillar center (FC). The DFC and FCs are integrated into a fundamental nucleolar substructure called the nucleolonema. The DFC corresponds to the matrix of the nucleolonema, and the FC is an electron microscopic counterpart of argyrophobic lacunae localized in the nucleolonema. The spherical FCs are intermittently arranged along the length of the nucleolonema in actively growing cells but are fused with each other to form tubular FCs when rDNA transcription is hampered. The RNase-gold complex does not bind to the FC but to the DFC and the GC, suggesting that rDNA transcription does not occur in the FC although both fluorescence in situ hybridization (FISH) and electron microscopic in situ hybridization reveal that the rDNA is specifically localized in the FCs. Immunogold-labeling after bromo-UTP (BrUTP) incorporation shows that rDNA transcription takes place in the boundary region between the FC and the DFC, and primary rRNA transcripts are expected to be processed outward within the DFC. Data have accumulated suggesting that the nucleolonema is a fundamental substructure of the nucleolus, and its skeleton is the tandem arrangement of the FCs, which are resting harbors or storages of rDNA. This paper proposes that the transversal structural organization of the nucleolonema is centrifugally built up by several structural and functional domains: condensed and/or loosened rDNA, rDNA transcription zone, and transcript processing and ribosome assembly zones.

  5. Recent Progress in Molecular Recognition Imaging Using Atomic Force Microscopy.

    PubMed

    Senapati, Subhadip; Lindsay, Stuart

    2016-03-15

    Atomic force microscopy (AFM) is an extremely powerful tool in the field of bionanotechnology because of its ability to image single molecules and make measurements of molecular interaction forces with piconewton sensitivity. It works in aqueous media, enabling studies of molecular phenomenon taking place under physiological conditions. Samples can be imaged in their near-native state without any further modifications such as staining or tagging. The combination of AFM imaging with the force measurement added a new feature to the AFM technique, that is, molecular recognition imaging. Molecular recognition imaging enables mapping of specific interactions between two molecules (one attached to the AFM tip and the other to the imaging substrate) by generating simultaneous topography and recognition images (TREC). Since its discovery, the recognition imaging technique has been successfully applied to different systems such as antibody-protein, aptamer-protein, peptide-protein, chromatin, antigen-antibody, cells, and so forth. Because the technique is based on specific binding between the ligand and receptor, it has the ability to detect a particular protein in a mixture of proteins or monitor a biological phenomenon in the native physiological state. One key step for recognition imaging technique is the functionalization of the AFM tips (generally, silicon, silicon nitrides, gold, etc.). Several different functionalization methods have been reported in the literature depending on the molecules of interest and the material of the tip. Polyethylene glycol is routinely used to provide flexibility needed for proper binding as a part of the linker that carries the affinity molecule. Recently, a heterofunctional triarm linker has been synthesized and successfully attached with two different affinity molecules. This novel linker, when attached to AFM tip, helped to detect two different proteins simultaneously from a mixture of proteins using a so-called "two

  6. Periodicity in bimodal atomic force microscopy

    SciTech Connect

    Lai, Chia-Yun; Santos, Sergio Chiesa, Matteo; Barcons, Victor

    2015-07-28

    Periodicity is fundamental for quantification and the application of conservation principles of many important systems. Here, we discuss periodicity in the context of bimodal atomic force microscopy (AFM). The relationship between the excited frequencies is shown to affect and control both experimental observables and the main expressions quantified via these observables, i.e., virial and energy transfer expressions, which form the basis of the bimodal AFM theory. The presence of a fundamental frequency further simplifies the theory and leads to close form solutions. Predictions are verified via numerical integration of the equation of motion and experimentally on a mica surface.

  7. Force measurements in skinned muscle fibres

    PubMed Central

    Hellam, D. C.; Podolsky, R. J.

    1969-01-01

    1. Isometric force was measured in skinned segments of frog semitendinosus muscle fibres exposed to solutions in which the calcium ion concentration was controlled with EGTA. 2. The threshold for force development, calculated from an apparent stability constant for the CaEGTA complex of 106.69 M-1 at pH 7·0, was generally close to pCa 7·5. Maximum force was reached at about pCa 6·0. 3. Maximum force is proportional to the cross-sectional area of the fibres. 4. The rate of force development was slower than that expected from simple diffusion of a substance from the bathing solution into the fibre. The delay appears to be due to slow equilibration of the EGTA buffer system during calcium uptake by the sarcoplasmic reticulum. 5. Addition of deoxycholate (DOC) to the bathing solution produced a reversible increase in the rate of force development. The steady force was also increased for values of pCa that gave less than maximum force, which shifted the force—pCa relation toward lower calcium concentrations by about 0·5 pCa unit. 6. The length—force relation in partially activated preparations is similar to that reported for electrically activated intact fibres. This result suggests that in the region of myofilament overlap the affinity of the binding sites for calcium is uniform along the length of the calciumbinding myofilament. PMID:5765859

  8. Portfolio theory of optimal isometric force production: Variability predictions and nonequilibrium fluctuation dissipation theorem

    NASA Astrophysics Data System (ADS)

    Frank, T. D.; Patanarapeelert, K.; Beek, P. J.

    2008-05-01

    We derive a fundamental relationship between the mean and the variability of isometric force. The relationship arises from an optimal collection of active motor units such that the force variability assumes a minimum (optimal isometric force). The relationship is shown to be independent of the explicit motor unit properties and of the dynamical features of isometric force production. A constant coefficient of variation in the asymptotic regime and a nonequilibrium fluctuation-dissipation theorem for optimal isometric force are predicted.

  9. Measurement of non-monotonic Casimir forces between silicon nanostructures

    NASA Astrophysics Data System (ADS)

    Tang, L.; Wang, M.; Ng, C. Y.; Nikolic, M.; Chan, C. T.; Rodriguez, A. W.; Chan, H. B.

    2017-01-01

    Casimir forces are of fundamental interest because they originate from quantum fluctuations of the electromagnetic field. Apart from controlling this force via the optical properties of materials, a number of novel geometries have been proposed to generate repulsive and/or non-monotonic Casimir forces between bodies separated by vacuum gaps. Experimental realization of these geometries, however, is hindered by the difficulties in alignment when the bodies are brought into close proximity. Here, using an on-chip platform with integrated force sensors and actuators, we circumvent the alignment problem and measure the Casimir force between two surfaces with nanoscale protrusions. We demonstrate that the force depends non-monotonically on the displacement. At some displacements, the Casimir force leads to an effective stiffening of the nanomechanical spring. Our findings pave the way for exploiting the Casimir force in nanomechanical systems using structures of complex and non-conventional shapes.

  10. Binding of glutathione and melatonin to pepsin occurs via different binding mechanisms.

    PubMed

    Li, Xiangrong; Ni, Tianjun

    2016-03-01

    Glutathione is a hydrophilic antioxidant and melatonin is a hydrophobic antioxidant, thus, the binding mechanism of the two antioxidants interacting with protease may be different. In this study, binding of glutathione and melatonin to pepsin has been studied using isothermal titration calorimetry (ITC), equilibrium microdialysis, UV-Vis absorption spectroscopy, circular dichroism (CD) spectroscopy, and molecular modeling. Thermodynamic investigations reveal that the binding of glutathione/melatonin to pepsin is driven by favorable enthalpy and unfavorable entropy, and the major driving forces are hydrogen bond and van der Waals force. ITC, equilibrium microdialysis, and molecular modeling reveal that the binding of glutathione to pepsin is characterized by a high number of binding sites. For melatonin, one molecule of melatonin combines with one molecule of pepsin. These results confirm that glutathione/melatonin interact with pepsin through two different binding mechanisms. In addition, the UV-Vis absorption and CD experiments indicate that glutathione and melatonin may induce conformational and microenvironmental changes of pepsin. The conformational changes of pepsin may affect its biological function as protease.

  11. Molecular Mechanotransduction: how forces trigger cytoskeletal dynamics

    NASA Astrophysics Data System (ADS)

    Ehrlicher, Allen

    2012-02-01

    Mechanical stresses elicit cellular reactions mediated by chemical signals. Defective responses to forces underlie human medical disorders, such as cardiac failure and pulmonary injury. Despite detailed knowledge of the cytoskeleton's structure, the specific molecular switches that convert mechanical stimuli into chemical signals have remained elusive. Here we identify the actin-binding protein, filamin A (FLNa) as a central mechanotransduction element of the cytoskeleton by using Fluorescence Loss After photoConversion (FLAC), a novel high-speed alternative to FRAP. We reconstituted a minimal system consisting of actin filaments, FLNa and two FLNa-binding partners: the cytoplasmic tail of ß-integrin, and FilGAP. Integrins form an essential mechanical linkage between extracellular and intracellular environments, with ß integrin tails connecting to the actin cytoskeleton by binding directly to filamin. FilGAP is a FLNa-binding GTPase-activating protein specific for Rac, which in vivo regulates cell spreading and bleb formation. We demonstrate that both externally-imposed bulk shear and myosin II driven forces differentially regulate the binding of integrin and FilGAP to FLNa. Consistent with structural predictions, strain increases ß-integrin binding to FLNa, whereas it causes FilGAP to dissociate from FLNa, providing a direct and specific molecular basis for cellular mechanotransduction. These results identify the first molecular mechanotransduction element within the actin cytoskeleton, revealing that mechanical strain of key proteins regulates the binding of signaling molecules. Moreover, GAP activity has been shown to switch cell movement from mesenchymal to amoeboid motility, suggesting that mechanical forces directly impact the invasiveness of cancer.

  12. The swim force as a body force

    NASA Astrophysics Data System (ADS)

    Yan, Wen; Brady, John

    2015-11-01

    Net (as opposed to random) motion of active matter results from an average swim (or propulsive) force. It is shown that the average swim force acts like a body force - an internal body force [Yan and Brady, Soft Matter, DOI:10.1039/C5SM01318F]. As a result, the particle-pressure exerted on a container wall is the sum of the swim pressure [Takatori et al., Phys. Rev. Lett., 2014, 113, 028103] and the `weight' of the active particles. A continuum mechanical description is possible when variations occur on scales larger than the run length of the active particles and gives a Boltzmann-like distribution from a balance of the swim force and the swim pressure. Active particles may also display `action at a distance' and accumulate adjacent to (or be depleted from) a boundary without any external forces. In the momentum balance for the suspension - the mixture of active particles plus fluid - only external body forces appear.

  13. 146 Kepler-Lamost targets fundamental parameters

    NASA Astrophysics Data System (ADS)

    Wu, Yaqian

    2015-08-01

    Accurate stellar fundamental parameters with high precision are important for distinguishing stellar populationand star study.Turn-off stars are in the relatively vital stellar evolution state. Studying turn-off stars can help us to have a more comprehensive understand of the stellar physics.With the help of observation provided by Lamost project, we obtain atmospheric parameters of 146 turn-off stars from LSP3 pipeline. Combined with stellar pulsation data from Kepler, we can get asteroseismic characteristic of stars,such as Δν and νmax.In this paper,we constructed a grid of evolutionary models, with the mass range from 0.8 to 2.5 M⊙ and metallicities Zini = 0.0085, 0.0105, 0.0130, 0.0165, 0.0200, 0.0250, 0.0300, 0.0400 (i.e.[Fe/H] from -0.3 to 0.4dex).All evolutionary tracks were started in the pre-main sequence birth line and ended at the base of Red Giant Branch.Based on the stellar model grid we constructed,as well as Kepler-Lamost observations, we obtained fundamental parameters of 146 around turn-off stars, and found that 112 targets lied in turn-off state or in the Main Sequence,15 targets are subgiant stars and 7 targets have evolved to the red giants stage.Then we use pulsation code(JIG) of Guenther to extract theorical individual frequencies and calculate theorical Δν.Meanwhile we obtained more precise fundamental parameters of these stars.

  14. Chirped Laser Dispersion Spectroscopy: Fundamentals and Applications

    NASA Astrophysics Data System (ADS)

    Plant, Genevieve B.

    The subject of this thesis is the fundamentals, implementation, and applications of Chirped Laser Dispersion Spectroscopy (CLaDS), an alternative dispersion spectroscopy technique that aims to overcome some limitations of absorption-based sensing. CLaDS preserves many of the benefits of dispersion sensing, namely baseline-free operation, immunity to received intensity, and linearity with sample concentration, and is fairly easy to implement without the need for stabilized interferometers, mode-locked lasers, and complex optical configurations required by many other dispersion-based sensors. First an introduction to CLaDS and a derivation of the spectroscopic signals are provided, highlighting fundamental similarities and differences to absorption-based sensing. Next the fundamental limit of CLaDS is investigated through analysis of the shot-noise limited performance under ideal operating conditions. This in turn allows for a theoretical and direct comparison to the shot-noise-limited performance of direct laser absorption spectroscopy (DLAS). This investigation shows that when full spectral scan fitting of realistic unknown parameters for each technique is used, both techniques demonstrate the same efficiency of parameter extraction. Following this theoretical investigation of ideal CLaDS performance, the technical details, methods of implementation, and component-introduced limitations of real-world CLaDS systems are discussed. Also included is a discussion of the first demonstration of an optical heterodyne enhanced CLaDS technique (HE-CLaDS). To overcome some of the technical limitations imposed by system instability, a modulation based technique (CM-CLaDS) was developed; the theory, optimization and noise characteristics of which are detailed. Finally, several applications of CLaDS are provided. These include atmospheric sensing, distributed sensor networks, and fiber dispersion characterization, all of which aim at demonstrating the technical advantages of the

  15. Fundamental constraints on two-time physics

    NASA Astrophysics Data System (ADS)

    Piceno, E.; Rosado, A.; Sadurní, E.

    2016-10-01

    We show that generalizations of classical and quantum dynamics with two times lead to a fundamentally constrained evolution. At the level of classical physics, Newton's second law is extended and exactly integrated in a (1 + 2) -dimensional space, leading to effective single-time evolution for any initial condition. The cases 2 + 2 and 3 + 2 are also analyzed. In the domain of quantum mechanics, we follow strictly the hypothesis of probability conservation by extending the Heisenberg picture to unitary evolution with two times. As a result, the observability of two temporal axes is constrained by a generalized uncertainty relation involving level spacings, total duration of the effect and Planck's constant.

  16. Productive reduplication in a fundamentally monosyllabic language.

    PubMed

    Wilbur, Ronnie B

    2009-01-01

    The question to be addressed in this paper is how a language which is fundamentally monosyllabic in structure can have about a dozen different reduplication types with at least eight different linguistic functions. The language under discussion, American Sign Language (ASL), is one representative of a class of languages that makes widespread use of reduplication for lexical and morphological purposes. The goal here is to present the set of phonological features that permit the productive construction of these forms and a first approximation to the feature geometry in which they participate. Reduplication forms are dependent on the event structure of the predicate and the associated aspectual modifications.

  17. Fundamental Structure of Matter and Strong Interaction

    SciTech Connect

    Jian-Ping Chen

    2011-11-01

    More than 99% of the visible matter in the universe are the protons and neutrons. Their internal structure is mostly governed by the strong interaction. Understanding their internal structure in terms of fundamental degrees-of-freedom is one of the most important subjects in modern physics. Worldwide efforts in the last few decades have lead to numerous surprises and discoveries, but major challenges still remain. An overview of the progress will be presented with a focus on the recent studies of the proton and neutron's electromagnetic and spin structure. Future perspectives will be discussed.

  18. [Fundamental study of blood and bone marrow].

    PubMed

    Miura, Ikuo

    2009-10-01

    The WHO classification incorporated recent advances of immunology, cytogenetics, and molecular biology, which developed from FAB classification based on cell morphology and cytochemistry. One of the most distinct changes was "AML with recurrent genetic abnormalities." The immunological and cytogenetic studies are required to apply the classification to hematopoietic and lymphoid neoplasms in addition to conventional examinations of the blood and bone marrow. The fundamentals of specimen collection, cell counts, morphologic analysis of blood cells, special stains and other laboratory studies were described in related to the management of myeloid leukemias.

  19. Colored ultrafast acoustics: from fundamentals to applications.

    PubMed

    Devos, Arnaud

    2015-02-01

    The aim of this paper is to review the various laser-wavelength effects reported in the field of ultrafast acoustics (UA). First observed by chance in 1999, a wavelength change can indeed have a strong effect on the signal detected in UA. After the physical origin of the effect was clarified and from a systematic exploration we established that all the opto-acoustic mechanisms acting in UA are influenced by the laser-wavelength. From that we suggested original applications of UA to fundamental and applied physics. So emerged a new field, now referred as Colored Picosecond Acoustics or APiC.

  20. Fundamentals of Chemistry at Surfaces and Beyond

    DTIC Science & Technology

    2013-09-23

    results of this research were published in J. Phys. Chem. C.34 B4. Fundamental Theory of Organic/Inorganic Hybrid Solar Cells In the field of...B, 104, 538-547 (2000). 38B. O’Regan, M. Gratzel, “A Low-Cost, High-Efficiency Solar Cell Based on Dye-Sensitized Colloidal TiO2 Films,” Nature...N. Murakami, H. J. Snaith, “Efficient Hybrid Solar Cells Based on Meso-Superstructured Organometal Halide Perovskites,” Sci. Exp., DOI: 10.1126

  1. Flow cytometry: retrospective, fundamentals and recent instrumentation.

    PubMed

    Picot, Julien; Guerin, Coralie L; Le Van Kim, Caroline; Boulanger, Chantal M

    2012-03-01

    Flow cytometry is a complete technology given to biologists to study cellular populations with high precision. This technology elegantly combines sample dimension, data acquisition speed, precision and measurement multiplicity. Beyond the statistical aspect, flow cytometry offers the possibility to physically separate sub-populations. These performances come from the common endeavor of physicists, biophysicists, biologists and computer engineers, who succeeded, by providing new concepts, to bring flow cytometry to current maturity. The aim of this paper is to present a complete retrospective of the technique and remind flow cytometry fundamentals before focusing on recent commercial instrumentation.

  2. Fundamentals of fungal molecular population genetic analyses.

    PubMed

    Xu, Jianping

    2006-07-01

    The last two decades have seen tremendous growth in the development and application of molecular methods in the analyses of fungal species and populations. In this paper, I provide an overview of the molecular techniques and the basic analytical tools used to address various fundamental population and evolutionary genetic questions in fungi. With increasing availability and decreasing cost, DNA sequencing is becoming a mainstream data acquisition method in fungal evolutionary genetic studies. However, other methods, especially those based on the polymerase chain reaction, remain powerful in addressing specific questions for certain groups of taxa. These developments are bringing fungal population and evolutionary genetics into mainstream ecology and evolutionary biology.

  3. Fundamental Limits of Spatial Resolution in PET

    PubMed Central

    Moses, William W.

    2010-01-01

    The fundamental limits of spatial resolution in positron emission tomography (PET) have been understood for many years. The physical size of the detector element usually plays the dominant role in determining resolution, but the combined contributions from acollinearity, positron range, penetration into the detector ring, and decoding errors in the detector modules often combine to be of similar size. In addition, the sampling geometry and statistical noise further degrade the effective resolution. This paper describes quantitatively describes these effects, discusses potential methods for reducing the magnitude of these effects, and computes the ultimately achievable spatial resolution for clinical and pre-clinical PET cameras. PMID:21804677

  4. Fundamental investigation of duct/ESP phenomena

    SciTech Connect

    Brown, C.A. ); Durham, M.D. ); Sowa, W.A. . Combustion Lab.); Himes, R.M. ); Mahaffey, W.A. )

    1991-10-21

    Radian Corporation was contracted to investigate duct injection and ESP phenomena in a 1.7 MW pilot plant constructed for this test program. This study was an attempt to resolve problems found in previous studies and answer remaining questions for the technology using an approach which concentrates on the fundamental mechanisms of the process. The goal of the study was to obtain a better understanding of the basic physical and chemical phenomena that control: (1) the desulfurization of flue gas by calcium-based reagent, and (2) the coupling of an existing ESP particulate collection device to the duct injection process. Process economics are being studied by others. (VC)

  5. Fundamental bioprocessing research for coal applications

    SciTech Connect

    Kaufman, E.N.

    1996-06-01

    The purpose of this program is to gain a fundamental understanding and sound scientific technical basis for evaluating the potential roles of innovative bioprocessing concepts for the utilization and conversion of coal. The aim is to explore the numerous ways in which advanced biological processes and techniques can open new opportunities for coal utilization or can replace more conventional techniques by use of milder conditions with less energy consumption or loss. There are several roles where biotechnology is likely to be important in coal utilization and conversion. These include potential bioprocessing systems such.

  6. Fundamental science of nanometer-size clusters

    SciTech Connect

    Wilcoxon, J.P.; Newcomer, P.P.; Samara, G.A.; Venturini, E.L.; Williamson, R.L.

    1995-10-01

    This research has produced a variety of monodisperse, nanometer-size clusters (nanoclusters for short), characterized their size and crystal structure and developed a scientific understanding of the size dependence of their physical properties. Of specific interest were the influence of quantum electronic confinement on the optical properties, magnetic properties, and dielectric properties. These properties were chosen both for their potential practical impact on various applications identified in the National Critical Technologies list (e.g., catalysis, information storage, sensors, environmental remediation, ...) as well as for their importance to the fundamental science of clusters. An Executive Summary provides a description of the major highlights.

  7. Evolving nucleotide binding surfaces

    NASA Technical Reports Server (NTRS)

    Kieber-Emmons, T.; Rein, R.

    1981-01-01

    An analysis is presented of the stability and nature of binding of a nucleotide to several known dehydrogenases. The employed approach includes calculation of hydrophobic stabilization of the binding motif and its intermolecular interaction with the ligand. The evolutionary changes of the binding motif are studied by calculating the Euclidean deviation of the respective dehydrogenases. Attention is given to the possible structural elements involved in the origin of nucleotide recognition by non-coded primordial polypeptides.

  8. Vocal fundamental and formant frequencies are honest signals of threat potential in peripubertal males.

    PubMed

    Hodges-Simeon, Carolyn R; Gurven, Michael; Puts, David A; Gaulin, Steven J C

    2014-07-01

    Fundamental and formant frequencies influence perceived pitch and are sexually dimorphic in humans. The information content of these acoustic parameters can illuminate the forces of sexual selection shaping vocal sex differences as well as the mechanisms that ensure signal reliability. We use multiple regression to examine the relationships between somatic (height, adiposity, and strength) and acoustic (fundamental frequency [F0], formant position [Pf], and fundamental frequency variation [F0-SD]) characteristics in a sample of peripubertal Bolivian Tsimane. Results indicate that among males-but not females-strength is the strongest predictor of F0 and Pf and that F0 and Pf are independent predictors of strength when height and adiposity are controlled. These findings suggest that listeners may attend to vocal frequencies because they signal honest, nonredundant information about male strength and threat potential, which are strongly related to physical maturity and which cannot be ascertained from visual or other indicators of height or adiposity alone.

  9. Foundations of Physical Theory, I: Force and Energy. Physical Processes in Terrestrial and Aquatic Ecosystems, Fundamentals.

    ERIC Educational Resources Information Center

    Pearson, Nolan E.

    This module is part of a series designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module is one of two units on the foundations of physical theory and the…

  10. Confocal reference free traction force microscopy

    PubMed Central

    Bergert, Martin; Lendenmann, Tobias; Zündel, Manuel; Ehret, Alexander E.; Panozzo, Daniele; Richner, Patrizia; Kim, David K.; Kress, Stephan J. P.; Norris, David J.; Sorkine-Hornung, Olga; Mazza, Edoardo; Poulikakos, Dimos; Ferrari, Aldo

    2016-01-01

    The mechanical wiring between cells and their surroundings is fundamental to the regulation of complex biological processes during tissue development, repair or pathology. Traction force microscopy (TFM) enables determination of the actuating forces. Despite progress, important limitations with intrusion effects in low resolution 2D pillar-based methods or disruptive intermediate steps of cell removal and substrate relaxation in high-resolution continuum TFM methods need to be overcome. Here we introduce a novel method allowing a one-shot (live) acquisition of continuous in- and out-of-plane traction fields with high sensitivity. The method is based on electrohydrodynamic nanodrip-printing of quantum dots into confocal monocrystalline arrays, rendering individually identifiable point light sources on compliant substrates. We demonstrate the undisrupted reference-free acquisition and quantification of high-resolution continuous force fields, and the simultaneous capability of this method to correlatively overlap traction forces with spatial localization of proteins revealed using immunofluorescence methods. PMID:27681958

  11. Optical trapping and manipulation of plasmonic nanoparticles: fundamentals, applications, and perspectives.

    PubMed

    Urban, Alexander S; Carretero-Palacios, Sol; Lutich, Andrey A; Lohmüller, Theobald; Feldmann, Jochen; Jäckel, Frank

    2014-05-07

    This feature article discusses the optical trapping and manipulation of plasmonic nanoparticles, an area of current interest with potential applications in nanofabrication, sensing, analytics, biology and medicine. We give an overview over the basic theoretical concepts relating to optical forces, plasmon resonances and plasmonic heating. We discuss fundamental studies of plasmonic particles in optical traps and the temperature profiles around them. We place a particular emphasis on our own work employing optically trapped plasmonic nanoparticles towards nanofabrication, manipulation of biomimetic objects and sensing.

  12. Force distributions in granular materials

    NASA Astrophysics Data System (ADS)

    Jaeger, Heinrich M.

    2002-03-01

    A fundamental problem in the study of disordered materials concerns the propagation of forces. Static granular media, such as sand particles inside a rigid container, have emerged as an important model system as they embody the zero temperature limit of disordered materials comprised of hardsphere repulsive particles. In this talk, I will review recent results on the distribution forces along the boundaries of granular material subjected to an applied load. While the spatial distribution of mean forces sensitively reflects the (macroscopic) packing structure of the material, the ensemble-averaged probability distribution of force fluctuations around the mean value, P(f), exhibits universal behavior. The shape of P(f) is found to be independent not only of the macroscopic packing arrangement but also of the inter-particle friction and, over a wide range, of the applied external stress. This shape is characterized by an exponential decay in the probability density for fluctuations above the mean force and only a small reduction, by no more than a factor two, for fluctuations below the mean [1]. Surprisingly, the exponential, non-Gaussian behavior appears to hold up even in the case of highly compressible grains, and it also has been observed in simulations of supercooled liquids [2]. I will discuss the implications of these findings on our current understanding of stress transmission in disordered media in general, and on glassy behavior in particular. [1] D. L. Blair, N. W. Mueggenburg, A. H. Marshall, H. M. Jaeger, and S. R. Nagel, Phys. Rev. E 63, 041304 (2001). [2] S. O’Hern, S. A. Langer, A. J. Liu, and S. R. Nagel, Phys. Rev. Lett. 86, 111 (2001). * Work performed in collaboration with D. L. Blair, J. M. Erikson, A. H. Marshall, N. W. Mueggenburg, and S. R. Nagel.

  13. The fundamentals of adaptive grid movement

    NASA Technical Reports Server (NTRS)

    Eiseman, Peter R.

    1990-01-01

    Basic grid point movement schemes are studied. The schemes are referred to as adaptive grids. Weight functions and equidistribution in one dimension are treated. The specification of coefficients in the linear weight, attraction to a given grid or a curve, and evolutionary forces are considered. Curve by curve and finite volume methods are described. The temporal coupling of partial differential equations solvers and grid generators was discussed.

  14. Fundamental Mechanisms Affecting Friction Welding under Vacuum

    DTIC Science & Technology

    1991-06-01

    and interior, is a large problem for arc welding where inert gases replace oxygen inside and spatter can damage surface and cloud optical devices...welded to the surface holding the patch in place. Inside or outside the station, studs can be friction welded to surfaces to attach insulation material...vacuum, surface contamination, material, weld force and weld speed on the integrity of the weld. The vacuum conditions are limited to 10 torr or less

  15. Microbial Cellulose Utilization: Fundamentals and Biotechnology

    PubMed Central

    Lynd, Lee R.; Weimer, Paul J.; van Zyl, Willem H.; Pretorius, Isak S.

    2002-01-01

    Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for “consolidated bioprocessing” (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts. PMID:12209002

  16. Microbial cellulose utilization: fundamentals and biotechnology.

    PubMed

    Lynd, Lee R; Weimer, Paul J; van Zyl, Willem H; Pretorius, Isak S

    2002-09-01

    Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for "consolidated bioprocessing" (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts.

  17. The fundamental plane correlations for globular clusters

    NASA Technical Reports Server (NTRS)

    Djorgovski, S.

    1995-01-01

    In the parameter space whose axes include a radius (core, or half-light), a surface brightness (central, or average within the half-light radius), and the central projected velocity dispersion, globular clusters lie on a two-dimensional surface (a plane, if the logarithmic quantities are used). This is analogous to the 'fundamental plane' of elliptical galaxies. The implied bivariate correlations are the best now known for globular clusters. The derived scaling laws for the core properties imply that cluster cores are fully virialized, homologous systems, with a constant (M/L) ratio. The corresponding scaling laws on the half-light scale are differrent, but are nearly identical to those derived from the 'fundamental plane' of ellipticals. This may be due to the range of cluster concentrations, which are correlated with other parameters. A similar explanation for elliptical galaxies may be viable. These correlations provide new empirical constraints for models of globular cluster formation and evolution, and may also be usable as rough distance-indicator relations for globular clusters.

  18. Comparison of the electron-spin force and radiation reaction force

    NASA Astrophysics Data System (ADS)

    Mahajan, Swadesh M.; Asenjo, Felipe A.; Hazeltine, Richard D.

    2015-02-01

    It is shown that the forces that originate from the electron-spin interacting with the electromagnetic field can play, along with the Lorentz force, a fundamentally important role in determining the electron motion in a high energy density plasma embedded in strong high-frequency radiation, a situation that pertains to both laser-produced and astrophysical systems. These forces, for instance, dominate the standard radiation reaction force as long as there is a `sufficiently' strong ambient magnetic field for affecting spin alignment. The inclusion of spin forces in any advanced modelling of electron dynamics pertaining to high energy density systems (for instance in particle-in-cell codes), therefore, is a must.

  19. Universal spin-momentum locked optical forces

    SciTech Connect

    Kalhor, Farid; Thundat, Thomas; Jacob, Zubin

    2016-02-08

    Evanescent electromagnetic waves possess spin-momentum locking, where the direction of propagation (momentum) is locked to the inherent polarization of the wave (transverse spin). We study the optical forces arising from this universal phenomenon and show that the fundamental origin of recently reported non-trivial optical chiral forces is spin-momentum locking. For evanescent waves, we show that the direction of energy flow, the direction of decay, and the direction of spin follow a right hand rule for three different cases of total internal reflection, surface plasmon polaritons, and HE{sub 11} mode of an optical fiber. Furthermore, we explain how the recently reported phenomena of lateral optical force on chiral and achiral particles are caused by the transverse spin of the evanescent field and the spin-momentum locking phenomenon. Finally, we propose an experiment to identify the unique lateral forces arising from the transverse spin in the optical fiber and point to fundamental differences of the spin density from the well-known orbital angular momentum of light. Our work presents a unified view on spin-momentum locking and how it affects optical forces on chiral and achiral particles.

  20. Fundamental studies of supported bimetallic catalysts by NMR spectroscopy

    SciTech Connect

    Savargaonkar, Nilesh

    1996-10-17

    Various hydrogenation reactions on transition metals are important commercially whereas certain hydrogenolysis reactions are useful from fundamental point of view. Understanding the hydrogen mobility and kinetics of adsorption-desorption of hydrogen is important in understanding the mechanisms of such reactions involving hydrogen. The kinetics of hydrogen chemisorption was studied by means of selective excitation NMR on silica supported Pt, Rh and Pt-Rh catalysts. The activation energy of hydrogen desorption was found to be lower on silica supported Pt catalysts as compared to Rh and Pt-Rh catalysts. It was found that the rates of hydrogen adsorption and desorption on Pt-Rh catalyst were similar to those on Rh catalyst and much higher as compared to Pt catalyst. The Ru-Ag bimetallic system is much simpler to study than the Pt-Rh system and serves as a model system to characterize more complicated systems such as the K/Ru system. Ag was found to decrease the amounts of adsorbed hydrogen and the hydrogen-to-ruthenium stoichiometry. Ag reduced the populations of states with low and intermediate binding energies of hydrogen on silica supported Ru catalyst. The rates of hydrogen adsorption and desorption were also lower on silica supported Ru-Ag catalyst as compared to Ru catalyst. This report contains introductory information, the literature review, general conclusions, and four appendices. An additional four chapters and one appendix have been processed separately for inclusion on the data base.

  1. Nanoparticles for Biomedical Imaging: Fundamentals of Clinical Translation

    PubMed Central

    Choi, Hak Soo; Frangioni, John V.

    2010-01-01

    Because of their large size compared to small molecules, and their multi-functionality, nanoparticles (NPs) hold promise as biomedical imaging, diagnostic, and theragnostic agents. However, the key to their success hinges on a detailed understanding of their behavior after administration into the body. NP biodistribution, target binding, and clearance are a complex function of their physicochemical properties in serum, which include hydrodynamic diameter, solubility, stability, shape and flexibility, surface charge, composition, and formulation. Moreover, many materials used to construct NPs have real or potential toxicity, or may interfere with other medical tests. In this review, we discuss the design considerations that mediate NP behavior in the body and the fundamental principles that govern clinical translation. By analyzing those nanomaterials that have already received regulatory approval, most of which are actually therapeutic agents, we attempt to predict which types of NPs hold potential as diagnostic agents for biomedical imaging. Finally, using quantum dots as an example, we provide a framework for deciding whether an NP-based agent is the best choice for a particular clinical application. PMID:21084027

  2. DNABP: Identification of DNA-Binding Proteins Based on Feature Selection Using a Random Forest and Predicting Binding Residues

    PubMed Central

    Guo, Jing; Sun, Xiao

    2016-01-01

    DNA-binding proteins are fundamentally important in cellular processes. Several computational-based methods have been developed to improve the prediction of DNA-binding proteins in previous years. However, insufficient work has been done on the prediction of DNA-binding proteins from protein sequence information. In this paper, a novel predictor, DNABP (DNA-binding proteins), was designed to predict DNA-binding proteins using the random forest (RF) classifier with a hybrid feature. The hybrid feature contains two types of novel sequence features, which reflect information about the conservation of physicochemical properties of the amino acids, and the binding propensity of DNA-binding residues and non-binding propensities of non-binding residues. The comparisons with each feature demonstrated that these two novel features contributed most to the improvement in predictive ability. Furthermore, to improve the prediction performance of the DNABP model, feature selection using the minimum redundancy maximum relevance (mRMR) method combined with incremental feature selection (IFS) was carried out during the model construction. The results showed that the DNABP model could achieve 86.90% accuracy, 83.76% sensitivity, 90.03% specificity and a Matthews correlation coefficient of 0.727. High prediction accuracy and performance comparisons with previous research suggested that DNABP could be a useful approach to identify DNA-binding proteins from sequence information. The DNABP web server system is freely available at http://www.cbi.seu.edu.cn/DNABP/. PMID:27907159

  3. Guanylate-binding proteins: niche recruiters for antimicrobial effectors.

    PubMed

    Dupont, Christopher D; Hunter, Christopher A

    2012-08-24

    There are fundamental questions regarding how IFN-γ activates host cells to eliminate intracellular pathogens. In this issue of Immunity, Yamamoto et al. (2012) demonstrate a critical role for the p65 guanylate-binding proteins (GBPs) in this process during infection with Toxoplasma gondii.

  4. Fundamental Complex Plasma Research on Ground and under Microgravity Conditions

    NASA Astrophysics Data System (ADS)

    Thomas, Hubertus; Fortov, Vladimir; Thoma, Markus; Pustylnik, Mikhail; Lipaev, Andrey; Morfill, Gregor; Molotkov, Vladimir; Usachev, Alexander; Nosenko, Vladimir; Fink, Martin; Petrov, Oleg; Rubin-Zuzic, Milenko

    2016-07-01

    Complex (dusty) plasma is plasma containing small solid particles in the sub-mm range. Those "dust" particles are highly charged due to the collection of electrons and ions and they interact electrostatically. Depending on the charge, density, and kinetic temperature of the particles, the interaction may be strong leading to collective effects and the emergence of liquid or solid behavior. In that sense complex plasmas are perfect model systems for the investigation of fundamental processes in classical condensed matter physics since their constituent mesoscopic particles are individually observable and can be regarded as classically interacting "proxy atoms". The term "complex plasmas" is widely used in the literature to distinguish dusty plasmas composed of a weakly ionized gas and charged microparticles specially "designed" for investigations in classical condensed matter, from naturally occurring systems. Gravity influences the complex plasma, the microparticles sediment and stable systems can only be achieved through counteracting gravity with other volume forces, e.g. electric or thermophoretic force. This allows producing two-dimensional - monolayer - systems, or three-dimensional systems under stress. Only under weightlessness conditions, large and homogeneous 3D systems can be formed. Although phenomena in classical condensed matter physics are in the forefront of complex plasma research the basic know-how gained from experiments, theory and numerical simulations can be of importance for the understanding of naturally occurring dusty plasmas in space. Thus, in this presentation I will show recent work on complex plasmas from the ground and first results from the PK-4 facility onboard the International Space Station ISS. Acknowledgements: We would like to acknowledge the joint ESA-ROSCOSMOS Experiment «Plasma Kristall-4» onboard the International Space Station ISS. This work is partly supported by DLR grant 50WM1441/ 50WM1442 and by the Russian Science

  5. Melanin-binding radiopharmaceuticals

    SciTech Connect

    Packer, S; Fairchild, R G; Watts, K P; Greenberg, D; Hannon, S J

    1980-01-01

    The scope of this paper is limited to an analysis of the factors that are important to the relationship of radiopharmaceuticals to melanin. While the authors do not attempt to deal with differences between melanin-binding vs. melanoma-binding, a notable variance is assumed. (PSB)

  6. The Study of Biomolecule-Substrate Interactions by Single Molecule Force Spectroscopy and Brownian Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Cook, Sara Iliafar

    Hybrids of biomolecules and nanomaterials have been identified as promising candidates in the development of novel therapeutics and electronic devices. Single stranded DNA (ssDNA)-bound Single-walled carbon nanotubes (SWCNTs) are of particular interest as they may be the key to solving the challenges that face the carbon nanotube separation technology and because of their potential application in bio-nanomedicine. The ability of ssDNA to form a stable hybrid with CNTs has been attributed to the structure and amphiphilic nature of this macromolecule, enabling the dispersion, sorting and patterned placement of nanotubes. Considering the significant role of ssDNA-CNTs in future technologies and the potential toxicity of such nanomaterials in biological systems, it is essential to gain a quantitative and fundamental understanding on the interactions that allow, weaken or prevent the formation of these hybrids. In this dissertation, we use both experimental and theoretical methods to systematically investigate the major characteristics of these interactions. The free energy of binding of ssDNA homopolymers to solvated carbon nanotubes is one of the key characteristics that determine the stability of such dispersions. We used single molecule force spectroscopy (SMFS), first on graphite and next on single walled carbon nanotubes, to probe and directly quantify the binding strength of ssDNA homopolymer oligomers to these substrates. The force resisting removal of DNA molecules from these surfaces shows characteristic steady-state force plateaus which were distinguishable for each DNA sequence. The free energy of binding per nucleotide for these oligomers on graphite were ranked as T >= A > G >= C (11.3 +/- 0.8 kT, 9.9 +/- 0.4 kT, 8.3 +/- 0.2 kT, and 7.5 +/- 0.8 kT, respectively). On SWCNTs, these interactions decreased in the following order: A > G > T > C, and their magnitude was much larger than on graphite (38.1 +/- 0.2; 33.9 +/- 0.1; 23.3 +/- 0.1; 17.1 +/- 0.1 k

  7. Crude oil prices: Speculation versus fundamentals

    NASA Astrophysics Data System (ADS)

    Kolodziej, Marek Krzysztof

    Beginning in 2004, the price of crude oil fluctuates rapidly over a wide range. Large and rapid price increases have recessionary consequences and dampen long-term infrastructural investment. I investigate whether price changes are driven by market fundamentals or speculation. With regard to market fundamentals, I revisit econometric evidence for the importance of demand shocks, as proxied by dry maritime cargo rates, on oil prices. When I eliminate transportation costs from both sides of the equation, disaggregate OPEC and non-OPEC production, and allow for more than one cointegrating relation, I find that previous specifications are inconsistent with arguments that demand shocks play an important role. Instead, results confirm the importance of OPEC supply shocks. I investigate two channels by which speculation may affect oil prices; the direct effect of trader behavior and changes in oil from a commodity to a financial asset. With regard to trader behavior, I find evidence that trader positions are required to explain the spread between spot and futures prices of crude oil on the New York Mercantile Exchange. The inclusion of trader positions clarifies the process of equilibrium error correction, such that there is bidirectional causality between prices and trader positions. This creates the possibility of speculative bubbles. With regard to oil as a commodity and/or financial asset, I use a Kalman Filter model to estimate the time-varying partial correlation between returns to investments in equity and oil markets. This correlation changes from negative to positive at the onset of the 2008 financial crisis. The low interest rates used to rescue the economy depress convenience yields, which reduces the benefits of holding oil as a commodity. Instead, oil becomes a financial asset (on net) as the oil market changed from contango to backwardation. Contradicting simple political narratives, my research suggests that both market fundamentals and speculation drive

  8. The Aerodynamic Forces on Airship Hulls

    NASA Technical Reports Server (NTRS)

    Munk, M. M.

    1979-01-01

    The new method for making computations in connection with the study of rigid airships, which was used in the investigation of Navy's ZR-1 by the special subcommittee of the National Advisory Committee for Aeronautics appointed for this purpose is presented. The general theory of the air forces on airship hulls of the type mentioned is described and an attempt was made to develop the results from the very fundamentals of mechanics.

  9. Fundamentals of Physics, Part 1 (Chapters 1-11)

    NASA Astrophysics Data System (ADS)

    Halliday, David; Resnick, Robert; Walker, Jearl

    2003-12-01

    . 10-8 Torque. 10-9 Newton's Second Law for Rotation. 10-10 Work and Rotational Kinetic Energy. Review & Summary. Questions. Problems. Chapter 11.Rolling, Torque, and Angular Momentum. When a jet-powered car became supersonic in setting the land-speed record, what was the danger to the wheels? 11-1 What Is Physics? 11-2 Rolling as Translation and Rotation Combined. 11-3 The Kinetic Energy of Rolling. 11-4 The Forces of Rolling. 11-5 The Yo-Yo. 11-6 Torque Revisited. 11-7 Angular Momentum. 11-8 Newton's Second Law in Angular Form. 11-9 The Angular Momentum of a System of Particles. 11-10 The Angular Momentum of a Rigid Body Rotating About a Fixed Axis. 11-11 Conservation of Angular Momentum. 11-12 Precession of a Gyroscope. Review & Summary. Questions. Problems. Appendix A: The International System of Units (SI). Appendix B: Some Fundamental Constants of Physics. Appendix C: Some Astronomical Data. Appendix D: Conversion Factors. Appendix E: Mathematical Formulas. Appendix F: Properties of the Elements. Appendix G: Periodic Table of the Elements. Answers to Checkpoints and Odd-Numbered Questions and Problems. Index.

  10. Chronic THC intake modifies fundamental cerebellar functions

    PubMed Central

    Stella, Nephi

    2013-01-01

    Delta9-tetrahydrocannabinol (THC), the principal bioactive component in the Cannabis plant, is truly a captivating drug. Acute and chronic THC intake produces a spectrum of biological effects ranging from transient psychotropic effects to prolonged medicinal benefits, many of which have been fostered for centuries by our society. In the July 2013 issue of the JCI, Cutando et al. combined mouse genetics with classic mouse behavioral analysis to deepen our understanding of the physiological consequence of subchronic THC intake on eyeblink reflexes, a fundamental neuronal adaptive response, revealing that this regimen leads to downregulation of the cannabinoid CB1 receptor (referred to as CB1 in the Cutando et al. article) in cerebellar stress fibers and the activation of microglia, raising provocative new questions about the safety profile of regimented THC intake. PMID:23863631

  11. Fundamental studies on cavitation melt processing

    NASA Astrophysics Data System (ADS)

    Tzanakis, I.; Hodnett, M.; Lebon, G. S. B.; Eskin, D. G.; Pericleous, K.

    2016-05-01

    The application of ultrasound to industrial casting processes has attracted research interest during the last 50 years. However, the transfer and scale-up of this advanced and promising technology to industry has been hindered by difficulties in treating large volumes of liquid metal due to the lack of understanding of certain fundamentals. In the current study experimental results on ultrasonic processing in deionised water and in liquid aluminium (Al) are reported. Cavitation activity was determined in both liquid environments and acoustic pressures were successfully measured using an advanced high-temperature cavitometer sensor. Results showed that highest cavitation intensity in the liquid bulk is achieved at lower amplitudes of the sonotrode tip than the maximum available, suggesting nonlinearity in energy transfer to the liquid, while the location of the sonotrode is seen to substantially affect cavitation activity within the liquid. Estimation of real-time acoustic pressures distributed inside a crucible with liquid Al was performed for the first time.

  12. Quantum operations: technical or fundamental challenge?

    NASA Astrophysics Data System (ADS)

    Mielnik, Bogdan

    2013-09-01

    A class of unitary operations generated by idealized, semiclassical fields is studied. The operations implemented by sharp potential kicks are revisited and the possibility of performing them by softly varying external fields is examined. The possibility of using the ion traps as ‘operation factories’ transforming quantum states is discussed. The non-perturbative algorithms indicate that the results of abstract δ-pulses of oscillator potentials can become real. Some of them, if empirically achieved, could be essential to examine certain atypical quantum ideas. In particular, simple dynamical manipulations might contribute to the Aharonov-Bohm criticism of the time-energy uncertainty principle, while some others may verify the existence of fundamental precision limits of the position measurements or the reality of ‘non-commutative geometries’.

  13. Fundamentals of ergonomics in theory and practice.

    PubMed

    Wilson, J R

    2000-12-01

    In this paper ergonomics is defined as a discipline in its own right, as the theoretical and fundamental understanding of human behaviour and performance in purposeful interacting socio-technical systems, and the application of that understanding to design of interactions in the context of real settings. This definition is justified in the financial, technicat, legal, organisational, social, political and professional contexts in which ergonomists work. On the basis of the history of ergonomics and contemporary contributions, it is proposed that it is one of the modern sciences, drawing as much from the field as from the laboratory, and including elements of an art and a craft as well. Justification for the new definition is provided by examining the interacting systems which are prevalent in the modern world and which are the domain best understood through the holistic approach of ergonomics. Finally a number of challenges for ergonomics are identified.

  14. Future fundamental combustion research for aeropropulsion systems

    NASA Technical Reports Server (NTRS)

    Mularz, E. J.

    1985-01-01

    Physical fluid mechanics, heat transfer, and chemical kinetic processes which occur in the combustion chamber of aeropropulsion systems were investigated. With the component requirements becoming more severe for future engines, the current design methodology needs the new tools to obtain the optimum configuration in a reasonable design and development cycle. Research efforts in the last few years were encouraging but to achieve these benefits research is required into the fundamental aerothermodynamic processes of combustion. It is recommended that research continues in the areas of flame stabilization, combustor aerodynamics, heat transfer, multiphase flow and atomization, turbulent reacting flows, and chemical kinetics. Associated with each of these engineering sciences is the need for research into computational methods to accurately describe and predict these complex physical processes. Research needs in each of these areas are highlighted.

  15. Photoacoustic tomography: fundamentals, advances and prospects

    PubMed Central

    Yao, Junjie; Wang, Lihong V.

    2011-01-01

    Optical microscopy has been contributing to the development of life science for more than three centuries. However, due to strong optical scattering in tissue, its in vivo imaging ability has been restricted to studies at superficial depths. Advances in photoacoustic tomography (PAT) now allow multiscale imaging at depths from sub-millimeter to several centimeters, with spatial resolutions from sub-micrometer to sub-millimeter. Because of this high scalability and its unique optical absorption contrast, PAT is capable of performing anatomical, functional, molecular and fluid-dynamic imaging at various system levels, and is playing an increasingly important role in fundamental biological research and clinical practice. This Review discusses recent technical progress in PAT and presents corresponding applications. It ends with a discussion of several prospects and their technical challenges. PMID:22025335

  16. Fundamental movement skills and autism spectrum disorders.

    PubMed

    Staples, Kerri L; Reid, Greg

    2010-02-01

    Delays and deficits may both contribute to atypical development of movement skills by children with ASD. Fundamental movement skills of 25 children with autism spectrum disorders (ASD) (ages 9-12 years) were compared to three typically developing groups using the Test of Gross Motor Development (TGMD-2). The group matched on chronological age performed significantly better on the TGMD-2. Another comparison group matched on movement skill demonstrated children with ASD perform similarly to children approximately half their age. Comparisons to a third group matched on mental age equivalence revealed the movement skills of children with ASD are more impaired than would be expected given their cognitive level. Collectively, these results suggest the movement skills of children with ASD reflect deficits in addition to delays.

  17. Fundamental Power Couplers for Superconducting Cavities

    SciTech Connect

    Isidoro E. Campisi

    2001-09-01

    Fundamental power couplers (FPC's) for superconducting cavities must meet very strict requirements to perform at high power levels (hundreds of kilowatts) and in a variety of conditions (CS, pulsed, travelling wave, standing wave) without adversely affecting the performance of the cavities they are powering. Producing good coupler designs and achieving operational performances in accelerator environments are challenging tasks that have traditionally involved large resources from many laboratories. The designs involve state-of-the-art activities in RF, cryogenic and mechanical engineering, materials science, vacuum technology, and electromagnetic field modeling. Handling, assembly and conditioning procedures have been developed to achieve ever-increasing power levels and more reliable operation. In this paper, the technical issues associated with the design, construction, assembly, processing, and operation of FPC's will be reviewed, together with the progress in FPC activities in several laboratories during the past few years.

  18. Fundamental considerations for multiwavelength photoacoustic molecular imaging

    NASA Astrophysics Data System (ADS)

    Zemp, Roger J.; Li, Li; Wang, Lihong V.

    2006-02-01

    Photoacoustic technology offers great promise for molecular imaging in vivo since it offers significant penetration, and optical contrast with ultrasonic spatial resolution. In this article we examine fundamental technical issues impacting capabilities of photoacoustic tomography for molecular imaging. First we examine how reconstructed photoacoustic tomography images are related to true absorber distributions by studying the modulation transfer function of a circular scanning tomographic system employing a modified filtered backprojection algorithm. We then study factors influencing quantitative estimation by developing a forward model of photoacoustic signal generation, and show conditions for which the system of equations can be inverted. Errors in the estimated optical fluence are shown to be a source of bias in estimates of molecular agent concentration. Finally we discuss noise propagation through the matrix inversion procedure and discuss implications for molecular imaging sensitivity and system design.

  19. Sperm preservation: Fundamental cryobiology and practical implications

    SciTech Connect

    Watson, P.F.; Critser, J.K.; Mazur, P.

    1992-07-01

    Human spermatozoa were first frozen successfully almost 40 years ago. While developments in packaging and storing have occurred in the intervening period, there is still little known specifically about how spermatozoa are adversely affected by freezing and thawing. This is largely due to the fact that sufficient cells survive the challenge to give a reasonable expectation of fertilization, but the shift to the exclusive use of cryopreserved semen for donor insemination, occasioned by the awareness of the risks particularly of AIDS transmission, has resulted in a renewed critical interest in the process of cryopreservation. This review will cover the more significant contributions over the past few years, and develop an argument for a sustained fundamental approach to sperm cryobiology.

  20. Sperm preservation: Fundamental cryobiology and practical implications

    SciTech Connect

    Watson, P.F. ); Critser, J.K. ); Mazur, P. )

    1992-01-01

    Human spermatozoa were first frozen successfully almost 40 years ago. While developments in packaging and storing have occurred in the intervening period, there is still little known specifically about how spermatozoa are adversely affected by freezing and thawing. This is largely due to the fact that sufficient cells survive the challenge to give a reasonable expectation of fertilization, but the shift to the exclusive use of cryopreserved semen for donor insemination, occasioned by the awareness of the risks particularly of AIDS transmission, has resulted in a renewed critical interest in the process of cryopreservation. This review will cover the more significant contributions over the past few years, and develop an argument for a sustained fundamental approach to sperm cryobiology.

  1. Hormesis: a fundamental concept in biology

    PubMed Central

    Calabrese, Edward J.

    2014-01-01

    This paper assesses the hormesis dose response concept, including its historical foundations, frequency, generality, quantitative features, mechanistic basis and biomedical, pharmaceutical and environmental health implications. The hormetic dose response is highly generalizable, being independent of biology model (i.e. common from plants to humans), level of biological organization (i.e. cell, organ and organism), endpoint, inducing agent and mechanism, providing the first general and quantitative description of plasticity. The hormetic dose response describes the limits to which integrative endpoints (e.g. cell proliferation, cell migration, growth patterns, tissue repair, aging processes, complex behaviors such as anxiety, learning, memory, and stress, preconditioning responses, and numerous adaptive responses) can be modulated (i.e., enhanced or diminished) by pharmaceutical, chemical and physical means. Thus, the hormesis concept is a fundamental concept in biology with a wide range of biological implications and biomedical applications. PMID:28357236

  2. Fundamental molecular physics and chemistry, part 1

    NASA Astrophysics Data System (ADS)

    Stehney, A. F.; Inokuti, M.

    1983-12-01

    Scientifically, the work of the program deals with aspects of the physics and chemistry of molecules related to their interactions with photons, electrons, and other external agents. These areas of study were chosen in view of our goals; that is to say, they were chosen so that the eventual outcome of the work meets some of the needs of the US Department of Energy (DOE) and of other government agencies that support the research. First, cross sections for electron and photon interactions with molecules were determined theoretically and experimently, because those cross sections are indispensable for detailed microscopic analyses of the earliest processes of radiation action on any molecular substance, including biological materials. Those analyses in turn provide a sound basis for radiology and radiation dosimetry. Second, the spectroscopy of certain molecules and of small clusters of molecules were studied because this topic is fundamental to the full understanding of atmospheric-pollutant chemistry.

  3. Fundamental Concepts Associated with Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Gonzalez, W. D.; Parker, E. N.; Mozer, F. S.; Vasyliūnas, V. M.; Pritchett, P. L.; Karimabadi, H.; Cassak, P. A.; Scudder, J. D.; Yamada, M.; Kulsrud, R. M.; Koga, D.

    The chapter starts with a discussion about the importance of the concept of magnetic field lines in space plasmas and magnetic reconnection, followed by presentations on: (a) the meaning and validity of empirical constructs related with magnetic reconnection research, such as: "moving" magnetic field lines, "frozen-in" condition and "diffusion region" of reconnection; and (b) experimental evidence of the diffusion region and related energetics. Next, aims to link external (MHD) with internal (non-MHD) regions of reconnection are discussed in association with the so-called "Axford conjecture", followed by short presentations on: (a) global equilibria in reconnection; and (b) the role of the separatrices in global aspects of reconnection. In the last section, we present additional discussion about the concept of "diffusion region" and about the two fundamental questions associated with magnetic reconnection reviewed in this chapter.

  4. High precision modeling for fundamental physics experiments

    NASA Astrophysics Data System (ADS)

    Rievers, Benny; Nesemann, Leo; Costea, Adrian; Andres, Michael; Stephan, Ernst P.; Laemmerzahl, Claus

    With growing experimental accuracies and high precision requirements for fundamental physics space missions the needs for accurate numerical modeling techniques are increasing. Motivated by the challenge of length stability in cavities and optical resonators we propose the develop-ment of a high precision modeling tool for the simulation of thermomechanical effects up to a numerical precision of 10-20 . Exemplary calculations for simplified test cases demonstrate the general feasibility of high precision calculations and point out the high complexity of the task. A tool for high precision analysis of complex geometries will have to use new data types, advanced FE solver routines and implement new methods for the evaluation of numerical precision.

  5. Interfaces at equilibrium: A guide to fundamentals.

    PubMed

    Marmur, Abraham

    2016-05-20

    The fundamentals of the thermodynamics of interfaces are reviewed and concisely presented. The discussion starts with a short review of the elements of bulk thermodynamics that are also relevant to interfaces. It continues with the interfacial thermodynamics of two-phase systems, including the definition of interfacial tension and adsorption. Finally, the interfacial thermodynamics of three-phase (wetting) systems is discussed, including the topic of non-wettable surfaces. A clear distinction is made between equilibrium conditions, in terms of minimizing energies (internal, Gibbs or Helmholtz), and equilibrium indicators, in terms of measurable, intrinsic properties (temperature, chemical potential, pressure). It is emphasized that the equilibrium indicators are the same whatever energy is minimized, if the boundary conditions are properly chosen. Also, to avoid a common confusion, a distinction is made between systems of constant volume and systems with drops of constant volume.

  6. Top Ten Problems in Fundamental Physics

    NASA Astrophysics Data System (ADS)

    Duff, M. J.

    In 1900 the world-renowned mathematician David Hilbert presented twenty-three problems at the International Congress of Mathematicians in Paris. These problems have inspired mathematicians throughout the last century. As a piece of millennial madness, all participants of the Strings 2000 Conference were invited to help formulate the ten most important unsolved problems in fundamental physics. Each participant was allowed to submit one candidate problem for consideration. To qualify, the problem must not only have been important but also well-defined and stated in a clear way. The best ten problems were selected at the end of the conference by a selection panel consisting of David Gross, Edward Witten and myself.

  7. Top Ten Problems in Fundamental Physics

    NASA Astrophysics Data System (ADS)

    Duff, M. J.

    2001-04-01

    In 1900 the world-renowned mathematician David Hilbert presented twenty-three problems at the International Congress of Mathematicians in Paris. These problems have inspired mathematicians throughout the last century. As a piece of millennial madness, all participants of the Strings 2000 Conference were invited to help formulate the ten most important unsolved problems in fundamental physics. Each participant was allowed to submit one candidate problem for consideration. To qualify, the problem must not only have been important but also well-defined and stated in a clear way. The best ten problems were selected at the end of the conference by a selection panel consisting of David Gross, Edward Witten and myself.

  8. Fundamental study on gas monitoring in celss

    NASA Astrophysics Data System (ADS)

    Nishi, I.; Tateishi, T.; Tomizawa, G.; Nitta, K.; Oguchi, M.

    A mass spectrometer and computer system was developed for conducting a fundamental study on gas monitoring in CELSS. Respiration and metabolism of the hamster and photosynthesis of the Spirulina were measured in a combination system consisting of a hamster chamber and a Spirulina cultivator. They are connected through a membrane gas exchanger. Some technical problems were examined. In the mass spectrometric gas monitoring, a simultaneous multi-sample measurement was developed by employing a rotating exchange valve. Long term precise measurement was obtained by employing an automatic calibration system. The membrane gas sampling probe proved to be useful for long term measurement. The cultivation rate of the Spirulina was effectively changed by controlling CO2 and light supply. The experimental results are helpful for improving the hamster-spirulina system.

  9. Fundamental study on gas monitoring in CELSS

    NASA Technical Reports Server (NTRS)

    Nishi, I.; Tateishi, T.; Tomizawa, G.; Nitta, K.; Oguchi, M.

    1987-01-01

    A mass spectrometer and computer system was developed for conducting a fundamental study on gas monitoring in a Controlled Ecological Life Support System. Respiration and metabolism of the hamster and photosynthesis of the Spirulina were measured in a combination system consisting of a hamster chamber and a Spirulina cultivator. They are connected through a membrane gas exchanger. Some technical problems were examined. In the mass spectrometric gas monitoring, a simultaneous multisample measurement was developed by employing a rotating exchange valve. Long term precise measurement was obtained by employing an automatic calibration system. The membrane gas sampling probe proved to be useful for long term measurement. The cultivation rate of the Spirulina was effectively changed by controlling CO2 and light supply. The experimental results are helpful for improving the hamster-spirulina system.

  10. The Failed Feminist Challenge to `Fundamental Epistemology'

    NASA Astrophysics Data System (ADS)

    Pinnick, Cassandra L.

    Despite volumes written in the name of the new and fundamental feminist project in philosophy of science, and conclusions drawn on the strength of the hypothesis that the feminist project will boost progress toward cognitive aims associated with science and rationality (and, one might add, policy decisions enacted in the name of these aims), the whole rationale for the project remains (after 20 years, plus) wholly unsubstantiated. We must remain agnostic about its evidentiary merits or demerits. This is because we are without evidence to test the hypothesis: certainly, we have no data that would test the strength of the hypothesis as asserting a causal relationship between women and cognitive ends. Thus, any self-respecting epistemologist who places a premium on evidence-driven belief and justification ought not to accept the hypothesis. By extension, there is no reasoned basis to draw any definitive conclusion about the project itself. No matter how self-evidently correct.

  11. Fundamentals of bipolar high-frequency surgery.

    PubMed

    Reidenbach, H D

    1993-04-01

    In endoscopic surgery a very precise surgical dissection technique and an efficient hemostasis are of decisive importance. The bipolar technique may be regarded as a method which satisfies both requirements, especially regarding a high safety standard in application. In this context the biophysical and technical fundamentals of this method, which have been known in principle for a long time, are described with regard to the special demands of a newly developed field of modern surgery. After classification of this method into a general and a quasi-bipolar mode, various technological solutions of specific bipolar probes, in a strict and in a generalized sense, are characterized in terms of indication. Experimental results obtained with different bipolar instruments and probes are given. The application of modern microprocessor-controlled high-frequency surgery equipment and, wherever necessary, the integration of additional ancillary technology into the specialized bipolar instruments may result in most useful and efficient tools of a key technology in endoscopic surgery.

  12. Fundamentals and applications of gas hydrates.

    PubMed

    Koh, Carolyn A; Sloan, E Dendy; Sum, Amadeu K; Wu, David T

    2011-01-01

    Fundamental understanding of gas hydrate formation and decomposition processes is critical in many energy and environmental areas and has special importance in flow assurance for the oil and gas industry. These areas represent the core of gas hydrate applications, which, albeit widely studied, are still developing as growing fields of research. Discovering the molecular pathways and chemical and physical concepts underlying gas hydrate formation potentially can lead us beyond flowline blockage prevention strategies toward advancing new technological solutions for fuel storage and transportation, safely producing a new energy resource from natural deposits of gas hydrates in oceanic and arctic sediments, and potentially facilitating effective desalination of seawater. The state of the art in gas hydrate research is leading us to new understanding of formation and dissociation phenomena that focuses on measurement and modeling of time-dependent properties of gas hydrates on the basis of their well-established thermodynamic properties.

  13. Nonrelativistic Quantum Mechanics with Fundamental Environment

    NASA Astrophysics Data System (ADS)

    Gevorkyan, Ashot S.

    2011-03-01

    Spontaneous transitions between bound states of an atomic system, "Lamb Shift" of energy levels and many other phenomena in real nonrelativistic quantum systems are connected within the influence of the quantum vacuum fluctuations ( fundamental environment (FE)) which are impossible to consider in the limits of standard quantum-mechanical approaches. The joint system "quantum system (QS) + FE" is described in the framework of the stochastic differential equation (SDE) of Langevin-Schrödinger (L-Sch) type, and is defined on the extended space R 3 ⊗ R { ξ}, where R 3 and R { ξ} are the Euclidean and functional spaces, respectively. The density matrix for single QS in FE is defined. The entropy of QS entangled with FE is defined and investigated in detail. It is proved that as a result of interaction of QS with environment there arise structures of various topologies which are a new quantum property of the system.

  14. Fundamentals of tribology at the atomic level

    NASA Technical Reports Server (NTRS)

    Ferrante, John; Pepper, Stephen V.

    1989-01-01

    Tribology, the science and engineering of solid surfaces in moving contact, is a field that encompasses many disciplines: solid state physics, chemistry, materials science, and mechanical engineering. In spite of the practical importance and maturity of the field, the fundamental understanding of basic phenomena has only recently been attacked. An attempt to define some of these problems and indicate some profitable directions for future research is presented. There are three broad classifications: (1) fluid properties (compression, rheology, additives and particulates); (2) material properties of the solids (deformation, defect formation and energy loss mechanisms); and (3) interfacial properties (adhesion, friction chemical reactions, and boundary films). Research in the categories has traditionally been approached by considering macroscopic material properties. Recent activity has shown that some issues can be approached at the atomic level: the atoms in the materials can be manipulated both experimentally and theoretically, and can produce results related to macroscopic phenomena.

  15. Fundamentals of Digital Engineering: Designing for Reliability

    NASA Technical Reports Server (NTRS)

    Katz, R.; Day, John H. (Technical Monitor)

    2001-01-01

    The concept of designing for reliability will be introduced along with a brief overview of reliability, redundancy and traditional methods of fault tolerance is presented, as applied to current logic devices. The fundamentals of advanced circuit design and analysis techniques will be the primary focus. The introduction will cover the definitions of key device parameters and how analysis is used to prove circuit correctness. Basic design techniques such as synchronous vs asynchronous design, metastable state resolution time/arbiter design, and finite state machine structure/implementation will be reviewed. Advanced topics will be explored such as skew-tolerant circuit design, the use of triple-modular redundancy and circuit hazards, device transients and preventative circuit design, lock-up states in finite state machines generated by logic synthesizers, device transient characteristics, radiation mitigation techniques. worst-case analysis, the use of timing analyzer and simulators, and others. Case studies and lessons learned from spaceflight designs will be given as examples

  16. The neutrophil-activating Dps protein of Helicobacter pylori, HP-NAP, adopts a mechanism different from Escherichia coli Dps to bind and condense DNA.

    PubMed

    Ceci, Pierpaolo; Mangiarotti, Laura; Rivetti, Claudio; Chiancone, Emilia

    2007-01-01

    The Helicobacter pylori neutrophil-activating protein (HP-NAP), a member of the Dps family, is a fundamental virulence factor involved in H.pylori-associated disease. Dps proteins protect bacterial DNA from oxidizing radicals generated by the Fenton reaction and also from various other damaging agents. DNA protection has a chemical component based on the highly conserved ferroxidase activity of Dps proteins, and a physical one based on the capacity of those Dps proteins that contain a positively charged N-terminus to bind and condense DNA. HP-NAP does not possess a positively charged N-terminus but, unlike the other members of the family, is characterized by a positively charged protein surface. To establish whether this distinctive property could be exploited to bind DNA, gel shift, fluorescence quenching and atomic force microscopy (AFM) experiments were performed over the pH range 6.5-8.5. HP-NAP does not self-aggregate in contrast to Escherichia coli Dps, but is able to bind and even condense DNA at slightly acid pH values. The DNA condensation capacity acts in concert with the ferritin-like activity and could be used to advantage by H.pylori to survive during host-infection and other stress challenges. A model for DNA binding/condensation is proposed that accounts for all the experimental observations.

  17. The neutrophil-activating Dps protein of Helicobacter pylori, HP-NAP, adopts a mechanism different from Escherichia coli Dps to bind and condense DNA

    PubMed Central

    Mangiarotti, Laura; Rivetti, Claudio; Chiancone, Emilia

    2007-01-01

    The Helicobacter pylori neutrophil-activating protein (HP-NAP), a member of the Dps family, is a fundamental virulence factor involved in H.pylori-associated disease. Dps proteins protect bacterial DNA from oxidizing radicals generated by the Fenton reaction and also from various other damaging agents. DNA protection has a chemical component based on the highly conserved ferroxidase activity of Dps proteins, and a physical one based on the capacity of those Dps proteins that contain a positively charged N-terminus to bind and condense DNA. HP-NAP does not possess a positively charged N-terminus but, unlike the other members of the family, is characterized by a positively charged protein surface. To establish whether this distinctive property could be exploited to bind DNA, gel shift, fluorescence quenching and atomic force microscopy (AFM) experiments were performed over the pH range 6.5–8.5. HP-NAP does not self-aggregate in contrast to Escherichia coli Dps, but is able to bind and even condense DNA at slightly acid pH values. The DNA condensation capacity acts in concert with the ferritin-like activity and could be used to advantage by H.pylori to survive during host-infection and other stress challenges. A model for DNA binding/condensation is proposed that accounts for all the experimental observations. PMID:17371778

  18. Pain management: a fundamental human right.

    PubMed

    Brennan, Frank; Carr, Daniel B; Cousins, Michael

    2007-07-01

    This article surveys worldwide medical, ethical, and legal trends and initiatives related to the concept of pain management as a human right. This concept recently gained momentum with the 2004 European Federation of International Association for the Study of Pain (IASP) Chapters-, International Association for the Study of Pain- and World Health Organization-sponsored "Global Day Against Pain," where it was adopted as a central theme. We survey the scope of the problem of unrelieved pain in three areas, acute pain, chronic noncancer pain, and cancer pain, and outline the adverse physical and psychological effects and social and economic costs of untreated pain. Reasons for deficiencies in pain management include cultural, societal, religious, and political attitudes, including acceptance of torture. The biomedical model of disease, focused on pathophysiology rather than quality of life, reinforces entrenched attitudes that marginalize pain management as a priority. Strategies currently applied for improvement include framing pain management as an ethical issue; promoting pain management as a legal right, providing constitutional guarantees and statutory regulations that span negligence law, criminal law, and elder abuse; defining pain management as a fundamental human right, categorizing failure to provide pain management as professional misconduct, and issuing guidelines and standards of practice by professional bodies. The role of the World Health Organization is discussed, particularly with respect to opioid availability for pain management. We conclude that, because pain management is the subject of many initiatives within the disciplines of medicine, ethics and law, we are at an "inflection point" in which unreasonable failure to treat pain is viewed worldwide as poor medicine, unethical practice, and an abrogation of a fundamental human right.

  19. Fundamental Space Biology 2010-2020

    NASA Astrophysics Data System (ADS)

    Tomko, David; Souza, Kenneth; Quincy, Charles; Sun, Sidney

    The goal of NASA's Fundamental Space Biology (FSB) is to strive for U.S. excellence in the whole range of Space Biology -Cell and Molecular, Microbiology, Plant and Animal Biology, Developmental Biology. NASA plans to solicit and conduct research that will contribute to our basic knowledge of the effect of space on living systems. NASA will issue recurring FSB NASA Research Announcements (NRAs) to more fully engage the space biology community. In doing so, FSB research will optimize ISS utilization, develop and demonstrate technology and hard-ware that will enable new science, and contribute to the base of knowledge that will facilitate human countermeasure development. New research capabilities for whole animal and plant bi-ology will be added, and will be optimized by providing state-of-the-art automated technology and analytic techniques wherever possible to maximize scientific return and optimize animal use. Ground-based research to develop and test hypotheses for flight experiments, including hy-pergravity and hypogravity simulations will be an integral FSB activity. Flight experiments will use the most appropriate platform to achieve science results -e.g., ISS, free flyers, sub-orbital flights, and NASA will work with its international partners and other U.S. agencies to achieve these objectives. FSB's highest priority for the near future is the development of mammalian fundamental research capabilities. Another high priority is the development of hardware for studying multiple generations of large plants. Current research in cell and molecular biology will be expanded to include new analytical capabilities. By taking these steps, NASA hopes to energize the Space Biology user community and advance our knowledge of the effect of gravity on living systems.

  20. The Cytoskeleton and Force Response Mechanisms

    NASA Technical Reports Server (NTRS)

    Allen, Philip Goodwin

    2003-01-01

    The long term aim of this project was to define the mechanisms by which cells sense and respond to the physical forces experienced at 1g and missing in microgravity. Identification and characterization of the elements of the cells force response mechanism could provide pathways and molecules to serve as targets for pharmacological intervention to mitigate the pathologic effects of microgravity. Mechanical forces experienced by the organism can be transmitted to cells through molecules that allow cells to bind to the extracellular matrix and through other types of molecules which bind cells to each other. These molecules are coupled in large complexes of proteins to structural elements such as the actin cytoskeleton that give the cell the ability to sense, resist and respond to force. Application of small forces to tissue culture cells causes local elevation of intracellular calcium through stretch activated ion channels, increased tyrosine phosphorylation and a restructuring of the actin cytoskeleton. Using collagen coated iron oxide beads and strong magnets, we can apply different levels of force to cells in culture. We have found that force application causes the cells to polymerize actin at the site of mechanical deformation and unexpectedly, to depolymerize actin across the rest of the cell. Observations of GFP- actin expressing cells demonstrate that actin accumulates at the site of deformation within the first five minutes of force application and is maintained for many tens of minutes after force is removed. Consistent with the reinforcement of the cytoskeletal structures underlying the integrin-bead interaction, force also alters the motion of bound magnetic beads. This effect is seen following the removal of the magnetic field, and is only partially ablated by actin disruption with cytochalsin B. While actin is polymerizing locally at the site of force application, force also stimulates a global reduction in actin filament content within the cells. We have

  1. Acanthamoeba castellanii contains a ribosomal RNA enhancer binding protein which stimulates TIF-IB binding and transcription under stringent conditions.

    PubMed Central

    Yang, Q; Radebaugh, C A; Kubaska, W; Geiss, G K; Paule, M R

    1995-01-01

    The intergenic spacer (IGS) of Acanthamoeba castellanii rRNA genes contains repeated elements which are weak enhancers for transcription by RNA polymerase I. A protein, EBF, was identified and partially purified which binds to the enhancers and to several other sequences within the IGS, but not to other DNA fragments, including the rRNA core promoter. No consensus binding sequence could be discerned in these fragments and bound factor is in rapid equilibrium with unbound. EBF has functional characteristics similar to vertebrate upstream binding factors (UBF). Not only does it bind to the enhancer and other IGS elements, but it also stimulates binding of TIF-IB, the fundamental transcription initiation factor, to the core promoter and stimulates transcription from the promoter. Attempts to identify polypeptides with epitopes similar to rat or Xenopus laevis UBF suggest that structurally the protein from A.castellanii is not closely related to vertebrate UBF. Images PMID:7501455

  2. Acanthamoeba castellanii contains a ribosomal RNA enhancer binding protein which stimulates TIF-IB binding and transcription under stringent conditions.

    PubMed

    Yang, Q; Radebaugh, C A; Kubaska, W; Geiss, G K; Paule, M R

    1995-11-11

    The intergenic spacer (IGS) of Acanthamoeba castellanii rRNA genes contains repeated elements which are weak enhancers for transcription by RNA polymerase I. A protein, EBF, was identified and partially purified which binds to the enhancers and to several other sequences within the IGS, but not to other DNA fragments, including the rRNA core promoter. No consensus binding sequence could be discerned in these fragments and bound factor is in rapid equilibrium with unbound. EBF has functional characteristics similar to vertebrate upstream binding factors (UBF). Not only does it bind to the enhancer and other IGS elements, but it also stimulates binding of TIF-IB, the fundamental transcription initiation factor, to the core promoter and stimulates transcription from the promoter. Attempts to identify polypeptides with epitopes similar to rat or Xenopus laevis UBF suggest that structurally the protein from A.castellanii is not closely related to vertebrate UBF.

  3. Plasmon assisted optical trapping: fundamentals and biomedical applications

    NASA Astrophysics Data System (ADS)

    Serafetinides, Alexandros A.; Makropoulou, Mersini; Tsigaridas, Georgios N.; Gousetis, Anastasios

    2015-01-01

    The field of optical trapping has dramatically grown due to implementation in various arenas including physics, biology, medicine and nanotechnology. Certainly, optical tweezers are an invaluable tool to manipulate a variation of particles, such as small dielectric spheres, cells, bacteria, chromosomes and even genes, by highly focused laser beams through microscope. As the main disadvantage of the conventional optical trapping systems is the diffraction limit of the incident light, plasmon assisted nanotrapping is reported as a suitable technique for trapping sub-wavelength metallic or dielectric particles. In this work, firstly, we report briefly on the basic theory of plasmon excitation, focusing on the interaction of nanoscale metallic structures with laser light. Secondly, experimental and numerical simulation results are also presented, demonstrating enhancement of the trapping efficiency of glass or SiO2 substrates, coated with Au and Ag nanostructures, with or without nanoparticles. The optical forces were calculated by measuring the particle's escape velocity calibration method. Finally, representative applications of plasmon assisted optical trapping are reviewed, from cancer therapeutics to fundamental biology and cell nanosurgery.

  4. Fundamentals of inertial focusing in microchannels.

    PubMed

    Zhou, Jian; Papautsky, Ian

    2013-03-21

    Inertial microfluidics has been attracting considerable interest in recent years due to immensely promising applications in cell biology. Despite the intense attention, the primary focus has been on development of inertial microfluidic devices with less emphasis paid to elucidation of the inertial focusing mechanics. The incomplete understanding, and sometimes confusing experimental results that indicate a different number of focusing positions in square or rectangular microchannels under similar flow conditions, have led to poor guidelines and difficulties in design of inertial microfluidic systems. In this work, we describe and experimentally validate a two-stage model inertial focusing in microchannels. Our analysis and experimental results show that not only the well-accepted shear-induced and wall-induced lift forces act on particles within flow causing equilibration near microchannel sidewalls, but the rotation-induced lift force influences the position of these equilibria. In addition, for the first time, we experimentally measure lift coefficients, which previously could only be obtained from numerical simulations. More importantly, insights offered by our two-stage model of inertial focusing are broadly applicable to cross-sectional geometries beyond rectangular. With elucidation of the equilibration mechanism, we envision better guidelines for the inertial microfluidics community, ultimately leading to improved performance and broader acceptance of the inertial microfluidic devices in a wide range of applications, from filtration to cell separations.

  5. Prediction of nucleic acid binding probability in proteins: a neighboring residue network based score.

    PubMed

    Miao, Zhichao; Westhof, Eric

    2015-06-23

    We describe a general binding score for predicting the nucleic acid binding probability in proteins. The score is directly derived from physicochemical and evolutionary features and integrates a residue neighboring network approach. Our process achieves stable and high accuracies on both DNA- and RNA-binding proteins and illustrates how the main driving forces for nucleic acid binding are common. Because of the effective integration of the synergetic effects of the network of neighboring residues and the fact that the prediction yields a hierarchical scoring on the protein surface, energy funnels for nucleic acid binding appear on protein surfaces, pointing to the dynamic process occurring in the binding of nucleic acids to proteins.

  6. Master equation-based analysis of a motor-clutch model for cell traction force.

    PubMed

    Bangasser, Benjamin L; Odde, David J

    2013-12-01

    Microenvironmental mechanics play an important role in determining the morphology, traction, migration, proliferation, and differentiation of cells. A stochastic motor-clutch model has been proposed to describe this stiffness sensitivity. In this work, we present a master equation-based ordinary differential equation (ODE) description of the motor-clutch model, from which we derive an analytical expression to for a cell's optimum stiffness (i.e. the stiffness at which the traction force is maximal). This analytical expression provides insight into the requirements for stiffness sensing by establishing fundamental relationships between the key controlling cell-specific parameters. We find that the fundamental controlling parameters are the numbers of motors and clutches (constrained to be nearly equal), and the time scale of the on-off kinetics of the clutches (constrained to favor clutch binding over clutch unbinding). Both the ODE solution and the analytical expression show good agreement with Monte Carlo motor-clutch output, and reduce computation time by several orders of magnitude, which potentially enables long time scale behaviors (hours-days) to be studied computationally in an efficient manner. The ODE solution and the analytical expression may be incorporated into larger scale models of cellular behavior to bridge the gap from molecular time scales to cellular and tissue time scales.

  7. Astronomers Gain Clues About Fundamental Physics

    NASA Astrophysics Data System (ADS)

    2005-12-01

    An international team of astronomers has looked at something very big -- a distant galaxy -- to study the behavior of things very small -- atoms and molecules -- to gain vital clues about the fundamental nature of our entire Universe. The team used the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) to test whether the laws of nature have changed over vast spans of cosmic time. The Green Bank Telescope The Robert C. Byrd Green Bank Telescope CREDIT: NRAO/AUI/NSF (Click on image for GBT gallery) "The fundamental constants of physics are expected to remain fixed across space and time; that's why they're called constants! Now, however, new theoretical models for the basic structure of matter indicate that they may change. We're testing these predictions." said Nissim Kanekar, an astronomer at the National Radio Astronomy Observatory (NRAO), in Socorro, New Mexico. So far, the scientists' measurements show no change in the constants. "We've put the most stringent limits yet on some changes in these constants, but that's not the end of the story," said Christopher Carilli, another NRAO astronomer. "This is the exciting frontier where astronomy meets particle physics," Carilli explained. The research can help answer fundamental questions about whether the basic components of matter are tiny particles or tiny vibrating strings, how many dimensions the Universe has, and the nature of "dark energy." The astronomers were looking for changes in two quantities: the ratio of the masses of the electron and the proton, and a number physicists call the fine structure constant, a combination of the electron charge, the speed of light and the Planck constant. These values, considered fundamental physical constants, once were "taken as time independent, with values given once and forever" said German particle physicist Christof Wetterich. However, Wetterich explained, "the viewpoint of modern particle theory has changed in recent years," with ideas such as

  8. Theoretical Study of the Effect of Probe Shape on Adhesion Force Between Probe and Substrate in Atomic Force Microscope Experiment

    NASA Astrophysics Data System (ADS)

    Yang, Li; Hu, Junhui; Kong, Lingjiang

    2013-12-01

    The quantitative description of adhesion force dependence on the probe shape is of importance in many scientific and industrial fields. We performed a theoretical study on the influences of the probe shape (the sphere and parabolic probe) on the adhesion force at different humidity in order to elucidate how the adhesion force varied with the probe shape in atomic force microscope manipulation experiment. We found that the combined action of the triple point and the Kelvin radius is the guiding trend of the adhesion force, and these two fundamental parameters are closely related to the probe shape. Meanwhile, the theoretical results demonstrated that the adhesion force are in a good agreement with the experiment data if the van der Waals force is take into account.

  9. Investigating the Binding of Peptides to Graphene Surfaces for Biosensing Applications

    NASA Astrophysics Data System (ADS)

    Garley, Amanda; Saikia, Nabanita; Barr, Stephen; Leuty, Gary; Berry, Rajiv; Heinz, Hendrik

    The Air Force Research Lab is focused on developing highly selective and sensitive graphene-based sensors functionalized with peptides for biomolecule detection. To achieve this there is a need to model interfacial binding interactions between the organic and inorganic components to complement ongoing experimental investigations. It is important to characterize the binding behavior of individual amino acids, with the goal of predicting binding of large peptides. Since polarization is important in graphene systems, a new force field which includes polarizability is used. This allows for an in depth exploration of pi-pi interactions, electrostatics and van der Waals forces involved with binding. The binding strength is determined via enthalpy and free energy calculations. Additionally, structural quantities are computed, such as how aromatic rings align with the graphene surface and the arrangement of various residue substituents in relation to the surface and water layers. Computational results are useful in guiding experimental methods focused on rapidly screening optimal peptide sequence for binding.

  10. Direct DNA binding by Brca1

    PubMed Central

    Paull, Tanya T.; Cortez, David; Bowers, Blair; Elledge, Stephen J.; Gellert, Martin

    2001-01-01

    The tumor suppressor Brca1 plays an important role in protecting mammalian cells against genomic instability, but little is known about its modes of action. In this work we demonstrate that recombinant human Brca1 protein binds strongly to DNA, an activity conferred by a domain in the center of the Brca1 polypeptide. As a result of this binding, Brca1 inhibits the nucleolytic activities of the Mre11/Rad50/Nbs1 complex, an enzyme implicated in numerous aspects of double-strand break repair. Brca1 displays a preference for branched DNA structures and forms protein–DNA complexes cooperatively between multiple DNA strands, but without DNA sequence specificity. This fundamental property of Brca1 may be an important part of its role in DNA repair and transcription. PMID:11353843

  11. Fundamental Characterization Studies of Advanced Photocatalytic Materials

    NASA Astrophysics Data System (ADS)

    Phivilay, Somphonh Peter

    Solar powered photocatalytic water splitting has been proposed as a method for the production of sustainable, non-carbon hydrogen fuel. Although much technological progress has been achieved in recent years in the discovery of advanced photocatalytic materials, the progress in the fundamental scientific understanding of such novel, complex mixed oxide and oxynitride photocatalysts has significantly lagged. One of the major reasons for this slow scientific progress is the limited number of reported surface characterization studies of the complex bulk mixed oxide and oxynitride photocatalyst systems. Although photocatalytic splitting of water by bulk mixed oxide and oxynitride materials involves both bulk (generation of excited electrons and holes) and surface phenomena (reaction of H2O with excited electrons and holes at the surface), the photocatalysis community has almost completely ignored the surface characteristics of such complex bulk photocatalysts and correlates the photocatalytic properties with bulk properties. Some of the most promising photocatalyst systems (NaTaO3, GaN, (Ga1-xZnx)(N1-xOx) and TaON) were investigated to establish fundamental bulk/surface structure photoactivity relationships. The bulk molecular and electronic structures of the photocatalysts were determined with Raman and UV-vis spectroscopy. Photoluminescence (PL) and transient PL spectroscopy were provided insight into how recombination of photogenerated electrons is related to the photocatalysis activity. The chemical states and atomic compositions of the surface region of the photocatalysts were determined with high resolution X-ray photoelectron spectroscopy (˜1-3 nm) and high sensitivity-low energy ion scattering spectroscopy (˜0.3 nm). The new insights obtained from surface characterization clarified the role of La and Ni promoters species for the NaTaO3 photocatalyst system. The La2O3 additive was found to be a structural promoter that stabilizes small NaTaO3 nanoparticles (NPs

  12. Analysis of DNA interactions using single-molecule force spectroscopy.

    PubMed

    Ritzefeld, Markus; Walhorn, Volker; Anselmetti, Dario; Sewald, Norbert

    2013-06-01

    Protein-DNA interactions are involved in many biochemical pathways and determine the fate of the corresponding cell. Qualitative and quantitative investigations on these recognition and binding processes are of key importance for an improved understanding of biochemical processes and also for systems biology. This review article focusses on atomic force microscopy (AFM)-based single-molecule force spectroscopy and its application to the quantification of forces and binding mechanisms that lead to the formation of protein-DNA complexes. AFM and dynamic force spectroscopy are exciting tools that allow for quantitative analysis of biomolecular interactions. Besides an overview on the method and the most important immobilization approaches, the physical basics of the data evaluation is described. Recent applications of AFM-based force spectroscopy to investigate DNA intercalation, complexes involving DNA aptamers and peptide- and protein-DNA interactions are given.

  13. Translation Against An Applied Force.

    NASA Astrophysics Data System (ADS)

    Skinner, Gary M.; Seol, Yeonee; Visscher, Koen

    2008-02-01

    Ribosome structure and mechanism are largely conserved among all known forms of life. Therefore, the motions associated with translation may be among the most ancient and fundamental in biology. However, the molecular mechanism of translocation, the coordinated movement of tRNAs and associated mRNA on the ribosome, has eluded scientists and remains obscure. Single-molecule experiments using optical tweezers and fluorescence microscope are starting to shed new light on these questions. For example, we have observed that moderate forces reverse direction of motion and ribosomes seem to slip backward into the 5' direction along a poly(U) message. Although the detailed molecular mechanism for ribosome slippage is not fully understood, these observations raise interesting biological questions about e.g. -1 frameshifting. Is the -1 frameshift essential for HIV-1 replication a result of tension in the message? Single-molecule experiments open the way towards quantitative modeling of ribosome motion and related phenomena such as -1 frameshifting.

  14. Fundamental and Regular Elementary Schools: Do Differences Exist?

    ERIC Educational Resources Information Center

    Weber, Larry J.; And Others

    This study compared the academic achievement and other outcomes of three public fundamental elementary schools with three regular elementary schools in a metropolitan school district. Modeled after the John Marshal Fundamental School in Pasadena, California, which opened in the fall of 1973, fundamental schools differ from regular schools in that…

  15. 43 CFR 4180.1 - Fundamentals of rangeland health.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Fundamentals of rangeland health. 4180.1... Fundamentals of Rangeland Health and Standards and Guidelines for Grazing Administration § 4180.1 Fundamentals of rangeland health. Standards and guidelines developed or revised by a Bureau of Land...

  16. 43 CFR 4180.1 - Fundamentals of rangeland health.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Fundamentals of rangeland health. 4180.1... Fundamentals of Rangeland Health and Standards and Guidelines for Grazing Administration § 4180.1 Fundamentals of rangeland health. Standards and guidelines developed or revised by a Bureau of Land...

  17. 33 CFR 86.03 - Limits of fundamental frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Limits of fundamental frequencies... of fundamental frequencies. To ensure a wide variety of whistle characteristics, the fundamental frequency of a whistle shall be between the following limits: (a) 70-200 Hz, for a vessel 200 meters or...

  18. 33 CFR 86.03 - Limits of fundamental frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Limits of fundamental frequencies... of fundamental frequencies. To ensure a wide variety of whistle characteristics, the fundamental frequency of a whistle shall be between the following limits: (a) 70-200 Hz, for a vessel 200 meters or...

  19. 33 CFR 86.03 - Limits of fundamental frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Limits of fundamental frequencies... of fundamental frequencies. To ensure a wide variety of whistle characteristics, the fundamental frequency of a whistle shall be between the following limits: (a) 70-200 Hz, for a vessel 200 meters or...

  20. Discriminatory effects in the optical binding of chiral nanoparticles

    NASA Astrophysics Data System (ADS)

    Forbes, Kayn A.; Bradshaw, David S.; Andrews, David L.

    2015-08-01

    The laser-induced intermolecular force that exists between two or more particles subjected to a moderately intense laser beam is termed `optical binding'. Completely distinct from the single-particle forces that give rise to optical trapping, the phenomenon of optical binding is a manifestation of the coupling between optically induced dipole moments in neutral particles. In conjunction with optical trapping, the optomechanical forces in optical binding afford means for the manipulation and fabrication of optically bound matter. The Casimir-Polder potential that is intrinsic to all matter can be overridden by the optical binding force in cases where the laser beam is of sufficient intensity. Chiral discrimination can arise when the laser input has a circular polarization, if the particles are themselves chiral. Then, it emerges that the interaction between particles with a particular handedness is responsive to the left- or right-handedness of the light. The present analysis, which expands upon previous studies of chiral discrimination in optical binding, identifies a novel mechanism that others have previously overlooked, signifying that the discriminatory effect is much more prominent than originally thought. The new theory leads to results for freely-tumbling chiral particles subjected to circularly polarized light. Rigorous conditions are established for the energy shifts to be non-zero and display discriminatory effects with respect to the handedness of the incident beam. Detailed calculations indicate that the energy shift is larger than those previously reported by three orders of magnitude.

  1. Metallochaperones: bind and deliver

    SciTech Connect

    Rosenzweig, A.C.

    2010-03-08

    Metallochaperones deliver metal ions directly to target proteins via specific protein-protein interactions. Recent research has led to a molecular picture of how some metallochaperones bind metal ions, recognize their partner proteins, and accomplish metal ion transfer.

  2. Dosimetry and Risk Assessment: Fundamental Concepts

    SciTech Connect

    Fisher, Darrell R.

    2005-12-29

    Radiation dosimetry is important for characterizing radiation exposures and for risk assessment. In a medical setting, dosimetry is important for evaluating the safety of administered radiopharmaceuticals and for planning the safe administration of therapeutic radionuclides. Environmental dosimetry helps establish the safety of radionuclide releases from electric power production and other human activities. Internal and external dosimetry help us understand the consequences of radiation exposure. The absorbed dose is the fundamental quantity in radiation dosimetry from which all other operational values in radiation protection are obtained. Equivalent dose to tissue and effective dose to the whole body are derivatives of absorbed dose and constructs of risk. Mathematical systems supported by computer software facilitate dose calculations and make it possible to estimate internal dose based on bioassay or other biokinetic data. Risk coefficients for radiation-induced cancer rely primarily on data from animal studies and long-term observations of the Hiroshima and Nagasaki bomb survivors. Low-dose research shows that mechanisms of radiation interactions with tissue are dose-dependent, but the resulting biological effects are not necessarily linear with absorbed dose. Thus, the analysis of radiation effects and associated risks must account for the influences of microscopic energy distributions at the cellular level, dose-rate, cellular repair of sub-lethal radiation damage, and modifying factors such as bystander effects, adaptive response, and genomic instability.

  3. Fundamentals of trapped ion mobility spectrometry.

    PubMed

    Michelmann, Karsten; Silveira, Joshua A; Ridgeway, Mark E; Park, Melvin A

    2015-01-01

    Trapped ion mobility spectrometry (TIMS) is a relatively new gas-phase separation method that has been coupled to quadrupole orthogonal acceleration time-of-flight mass spectrometry. The TIMS analyzer is a segmented rf ion guide wherein ions are mobility-analyzed using an electric field that holds ions stationary against a moving gas, unlike conventional drift tube ion mobility spectrometry where the gas is stationary. Ions are initially trapped, and subsequently eluted from the TIMS analyzer over time according to their mobility (K). Though TIMS has achieved a high level of performance (R > 250) in a small device (<5 cm) using modest operating potentials (<300 V), a proper theory has yet to be produced. Here, we develop a quantitative theory for TIMS via mathematical derivation and simulations. A one-dimensional analytical model, used to predict the transit time and theoretical resolving power, is described. Theoretical trends are in agreement with experimental measurements performed as a function of K, pressure, and the axial electric field scan rate. The linear dependence of the transit time with 1/K provides a fundamental basis for determination of reduced mobility or collision cross section values by calibration. The quantitative description of TIMS provides an operational understanding of the analyzer, outlines the current performance capabilities, and provides insight into future avenues for improvement.

  4. Extracting Fundamental Periods to Segment Biomedical Signals.

    PubMed

    Motrenko, Anastasia; Strijov, Vadim

    2016-11-01

    We address the problem of segmenting nearly periodic time series into period-like segments. We introduce a definition of nearly periodic time series via triplets 〈 basic shape, shape transformation, time scaling 〉 that covers a wide range of time series. To split the time series into periods, we select a pair of principal components of the Hankel matrix. We then cut the trajectory of the selected principal components by its symmetry axis and, thus, obtaining half-periods that are merged into segments. We describe a method of automatic selection of periodic pairs of principal components, corresponding to the fundamental periodicity. We demonstrate the application of the proposed method to the problem of period extraction for accelerometric time series of human gait. We see the automatic segmentation into periods as a problem of major importance for human activity recognition problem, since it allows to obtain interpretable segments: each extracted period can be seen as an ultimate entity of gait. The method we propose is more general compared to the application specific methods and can be used for any nearly periodical time series. We compare its performance to classical mathematical methods of period extraction and find that it is not only comparable to the alternatives, but in some cases performs better.

  5. A Study of Fundamental Shock Noise Mechanisms

    NASA Technical Reports Server (NTRS)

    Meadows, Kristine R.

    1997-01-01

    This paper investigates two mechanisms fundamental to sound generation in shocked flows: shock motion and shock deformation. Shock motion is modeled numerically by examining the interaction of a sound wave with a shock. This numerical approach is validated by comparison with results obtained by linear theory for a small-disturbance case. Analysis of the perturbation energy with Myers' energy corollary demonstrates that acoustic energy is generated by the interaction of acoustic disturbances with shocks. This analysis suggests that shock motion generates acoustic and entropy disturbance energy. Shock deformation is modeled numerically by examining the interaction of a vortex ring with a shock. These numerical simulations demonstrate the generation of both an acoustic wave and contact surfaces. The acoustic wave spreads cylindrically. The sound intensity is highly directional and the sound pressure increases with increasing shock strength. The numerically determined relationship between the sound pressure and the Mach number is found to be consistent with experimental observations of shock noise. This consistency implies that a dominant physical process in the generation of shock noise is modeled in this study.

  6. Stability of fundamental couplings: A global analysis

    NASA Astrophysics Data System (ADS)

    Martins, C. J. A. P.; Pinho, A. M. M.

    2017-01-01

    Astrophysical tests of the stability of fundamental couplings are becoming an increasingly important probe of new physics. Motivated by the recent availability of new and stronger constraints we update previous works testing the consistency of measurements of the fine-structure constant α and the proton-to-electron mass ratio μ =mp/me (mostly obtained in the optical/ultraviolet) with combined measurements of α , μ and the proton gyromagnetic ratio gp (mostly in the radio band). We carry out a global analysis of all available data, including the 293 archival measurements of Webb et al. and 66 more recent dedicated measurements, and constraining both time and spatial variations. While nominally the full data sets show a slight statistical preference for variations of α and μ (at up to two standard deviations), we also find several inconsistencies between different subsets, likely due to hidden systematics and implying that these statistical preferences need to be taken with caution. The statistical evidence for a spatial dipole in the values of α is found at the 2.3 sigma level. Forthcoming studies with facilities such as ALMA and ESPRESSO should clarify these issues.

  7. [Fundamental and clinical aspects of cystatin C].

    PubMed

    Itoh, Yoshihisa; Kawabata, Isao; Akasaka, Kazumi; Kino, Shuichi

    2012-08-01

    Recent progress of fundamental and clinical studies on cystatin C was reviewed. Most of key studies are indebted to prof. Grubb A and his groups. International contributions from Japanese research work are included here. The protein is a basic low molecular weight protein of 13,300 with 120 amino acid residues and pI 9.3, functioning as a cysteine protease inhibitor. With an introduction of ERM-DA471, international reference material for serum cystatin C, global standardization for immunoassay systems has been much facilitated. No serious problems are present in the pre-analytical stage. Serum reference intervals are properly set in all Asian populations including Japanese with age and gender-related differences. The protein is a powerful serum intrinsic marker for glomerular filtration rate. Estimated glomerular filtration rate (eGFRcysC) in coupled with eGFRCr will definitely be a clinical routine for early detection and prevention of altered kidney function and cardiovascular events in general population. Genetic tests clinically indicated include hereditary cystatin C amyloid angiopathy (L68Q) and adult macular degeneration (A25T) although their frequency is extremely low.

  8. Fundamental quantitative security in quantum key generation

    SciTech Connect

    Yuen, Horace P.

    2010-12-15

    We analyze the fundamental security significance of the quantitative criteria on the final generated key K in quantum key generation including the quantum criterion d, the attacker's mutual information on K, and the statistical distance between her distribution on K and the uniform distribution. For operational significance a criterion has to produce a guarantee on the attacker's probability of correctly estimating some portions of K from her measurement, in particular her maximum probability of identifying the whole K. We distinguish between the raw security of K when the attacker just gets at K before it is used in a cryptographic context and its composition security when the attacker may gain further information during its actual use to help get at K. We compare both of these securities of K to those obtainable from conventional key expansion with a symmetric key cipher. It is pointed out that a common belief in the superior security of a quantum generated K is based on an incorrect interpretation of d which cannot be true, and the security significance of d is uncertain. Generally, the quantum key distribution key K has no composition security guarantee and its raw security guarantee from concrete protocols is worse than that of conventional ciphers. Furthermore, for both raw and composition security there is an exponential catch-up problem that would make it difficult to quantitatively improve the security of K in a realistic protocol. Some possible ways to deal with the situation are suggested.

  9. Fundamental Scientific Problems in Magnetic Recording

    SciTech Connect

    Schulthess, T.C.; Miller, M.K.

    2007-06-27

    Magnetic data storage technology is presently leading the high tech industry in advancing device integration--doubling the storage density every 12 months. To continue these advancements and to achieve terra bit per inch squared recording densities, new approaches to store and access data will be needed in about 3-5 years. In this project, collaboration between Oak Ridge National Laboratory (ORNL), Center for Materials for Information Technology (MINT) at University of Alabama (UA), Imago Scientific Instruments, and Seagate Technologies, was undertaken to address the fundamental scientific problems confronted by the industry in meeting the upcoming challenges. The areas that were the focus of this study were to: (1) develop atom probe tomography for atomic scale imaging of magnetic heterostructures used in magnetic data storage technology; (2) develop a first principles based tools for the study of exchange bias aimed at finding new anti-ferromagnetic materials to reduce the thickness of the pinning layer in the read head; (3) develop high moment magnetic materials and tools to study magnetic switching in nanostructures aimed at developing improved writers of high anisotropy magnetic storage media.

  10. Fundamental Considerations for Biobank Legacy Planning

    PubMed Central

    Fombonne, Benjamin; Watson, Peter Hamilton; Moore, Helen Marie

    2016-01-01

    Biobanking in its various forms is an activity involving the collection of biospecimens and associated data and their storage for differing lengths of time before use. In some cases, biospecimens are immediately used, but in others, they are stored typically for the term of a specified project or in perpetuity until the materials are used up or declared to be of little scientific value. Legacy planning involves preparing for the phase that follows either biobank closure or a significant change at an operational level. In the case of a classical finite collection, this may be brought about by the completion of the initial scientific goals of a project, a loss of funding, or loss of or change in leadership. Ultimately, this may require making a decision about when and where to transfer materials or whether to destroy them. Because biobanking in its entirety is a complex endeavour, legacy planning touches on biobank operations as well as ethical, legal, financial, and governance parameters. Given the expense and time that goes into setting up and maintaining biobanks, coupled with the ethical imperative to appropriately utilize precious resources donated to research, legacy planning is an activity that every biobanking entity should think about. This article describes some of the fundamental considerations for preparing and executing a legacy plan, and we envisage that this article will facilitate dialogue to help inform best practices and policy development in the future. PMID:26890981

  11. Ultralight porous metals: From fundamentals to applications

    NASA Astrophysics Data System (ADS)

    Tianjian, Lu

    2002-10-01

    Over the past few years a number of low cost metallic foams have been produced and used as the core of sandwich panels and net shaped parts. The main aim is to develop lightweight structures which are stiff, strong, able to absorb large amount of energy and cheap for application in the transport and construction industries. For example, the firewall between the engine and passenger compartment of an automobile must have adequate mechanical strength, good energy and sound absorbing properties, and adequate fire retardance. Metal foams provide all of these features, and are under serious consideration for this applications by a number of automobile manufacturers (e.g., BMW and Audi). Additional specialized applications for foam-cored sandwich panels range from heat sinks for electronic devices to crash barriers for automobiles, from the construction panels in lifts on aircraft carriers to the luggage containers of aircraft, from sound proofing walls along railway tracks and highways to acoustic absorbers in lean premixed combustion chambers. But there is a problem. Before metallic foams can find a widespread application, their basic properties must be measured, and ideally modeled as a function of microstructural details, in order to be included in a design. This work aims at reviewing the recent progress and presenting some new results on fundamental research regarding the micromechanical origins of the mechanical, thermal, and acoustic properties of metallic foams.

  12. Autonomous control systems - Architecture and fundamental issues

    NASA Technical Reports Server (NTRS)

    Antsaklis, P. J.; Passino, K. M.; Wang, S. J.

    1988-01-01

    A hierarchical functional autonomous controller architecture is introduced. In particular, the architecture for the control of future space vehicles is described in detail; it is designed to ensure the autonomous operation of the control system and it allows interaction with the pilot and crew/ground station, and the systems on board the autonomous vehicle. The fundamental issues in autonomous control system modeling and analysis are discussed. It is proposed to utilize a hybrid approach to modeling and analysis of autonomous systems. This will incorporate conventional control methods based on differential equations and techniques for the analysis of systems described with a symbolic formalism. In this way, the theory of conventional control can be fully utilized. It is stressed that autonomy is the design requirement and intelligent control methods appear at present, to offer some of the necessary tools to achieve autonomy. A conventional approach may evolve and replace some or all of the `intelligent' functions. It is shown that in addition to conventional controllers, the autonomous control system incorporates planning, learning, and FDI (fault detection and identification).

  13. Chiroptical signatures of life and fundamental physics.

    PubMed

    Macdermott, Alexandra J

    2012-09-01

    This paper aims to inspire experimentalists to carry out proposed new chiroptical experiments springing from the theoretical study of the role of parity violation in the origin of biomolecular homochirality and to provide a brief update on the current status of calculations of the electroweak parity-violating energy difference (PVED) between enantiomers. If the PVED did select life's handedness, we would expect to find life on other planets consistently using the same hand as terrestrial biochemistry. Much more importantly, even finding the "wrong" hand (rather than a racemic mixture) on another planet could be the homochiral signature of life, and we discuss our proposal for chiroptical detection of life on extra-solar planets. The PVED may also have an exciting future as a "molecular footprint" of fundamental physics: comparison of calculated PVEDs with measured values could one day allow chemists to do "table-top particle physics" more cheaply with improved chiroptical techniques instead of ever larger particle accelerators. We discuss our proposed chiroptical method to measure the PVED by using molecular beams. To our knowledge, optical rotation has not yet been measured in molecular beams, but the rewards of doing so include a host of other "first ever" results in addition to measurement of the PVED.

  14. Theory overview of testing fundamental symmetries

    NASA Astrophysics Data System (ADS)

    Mavromatos, Nick E.

    2014-04-01

    I review first some theoretical motivations for violation of Lorentz and/or CPT Invariance. Although the latter symmetries may be violated in a quantum gravity setting, nevertheless there are situations in which these violations are due to a given classical background geometry that may characterised early epochs of our Universe, and in fact be responsible for the observed dominance of matter over antimatter in the Universe. In this way I estimate some of the coefficients of the Standard Model Extension (SME), which is a framework for a field theoretic study of such a breakdown of fundamental symmetries. Then I describe briefly some tests of these symmetries, giving emphasis in low-energy antiproton physics and electric dipole moment measurements, of interest to this conference. I also mention the rôle of entangled states of neutral mesons in providing independent measurements of T(ime reversal) and CP Violation, thus providing independent tests of CPT symmetry, as well as novel ("smoking-gun" type) tests of decoherence-induced CPT violation, which may characterise some models of quantum gravity.

  15. TESTING DISTANCE ESTIMATORS WITH THE FUNDAMENTAL MANIFOLD

    SciTech Connect

    Zaritsky, Dennis; Zabludoff, Ann I.; Gonzalez, Anthony H.

    2012-03-20

    We demonstrate how the Fundamental Manifold (FM) can be used to cross-calibrate distance estimators even when those 'standard candles' are not found in the same galaxy. Such an approach greatly increases the number of distance measurements that can be utilized to check for systematic distance errors and the types of estimators that can be compared. Here we compare distances obtained using Type Ia supernova (SN Ia), Cepheids, surface brightness fluctuations, the luminosity of the tip of the red giant branch, circumnuclear masers, eclipsing binaries, RR Lyrae stars, and the planetary nebulae luminosity functions. We find no significant discrepancies (differences are <2{sigma}) between distance methods, although differences at the {approx}10% level cannot yet be ruled out. The potential exists for significant refinement because the data used here are heterogeneous B-band magnitudes that will soon be supplanted by homogeneous, near-infrared magnitudes. We illustrate the use of FM distances to (1) revisit the question of the metallicity sensitivity of various estimators, confirming the dependence of SN Ia distances on host galaxy metallicity, and (2) provide an alternative calibration of H{sub 0} that replaces the classical ladder approach in the use of extragalactic distance estimators with one that utilizes data over a wide range of distances simultaneously.

  16. Uncertainty as a fundamental scientific value.

    PubMed

    Clegg, Joshua W

    2010-09-01

    The author argues that, though social scientists generally value tolerance for ambiguity, and some even assert a fundamental indeterminacy in human systems, there is still a discipline-wide discomfort with uncertainty and ambiguity. It is argued that this distaste for uncertainty derives from a distorted view of the classical physical sciences, a view that ignores the essentially critical and radical foundations of scientific practice. The drive for certainty, it is argued, is essentially unscientific, in that certain, or adequate, forms of knowledge can only recapitulate the already known and in their dogmatic and institutionalized forms prevent the development of genuinely new knowledge. In contrast, uncertainty is defended as a positive condition, generative of new knowledge because it is open to discovery and to the mystery of the other. The conclusion drawn from this analysis is that the social sciences can only progress if uncertainty, or mystery, is protected and cultivated through a scientific discourse constituted in local and concrete terms (rather than in general and universal ones) and through a self-reflective and self-critical research praxis.

  17. Fundamentals of materials accounting for nuclear safeguards

    SciTech Connect

    Pillay, K.K.S.

    1989-04-01

    Materials accounting is essential to providing the necessary assurance for verifying the effectiveness of a safeguards system. The use of measurements, analyses, records, and reports to maintain knowledge of the quantities of nuclear material present in a defined area of a facility and the use of physical inventories and materials balances to verify the presence of special nuclear materials are collectively known as materials accounting for nuclear safeguards. This manual, prepared as part of the resource materials for the Safeguards Technology Training Program of the US Department of Energy, addresses fundamental aspects of materials accounting, enriching and complementing them with the first-hand experiences of authors from varied disciplines. The topics range from highly technical subjects to site-specific system designs and policy discussions. This collection of papers is prepared by more than 25 professionals from the nuclear safeguards field. Representing research institutions, industries, and regulatory agencies, the authors create a unique resource for the annual course titled ''Materials Accounting for Nuclear Safeguards,'' which is offered at the Los Alamos National Laboratory.

  18. Effects of water models on binding affinity: evidence from all-atom simulation of binding of tamiflu to A/H5N1 neuraminidase.

    PubMed

    Nguyen, Trang Truc; Viet, Man Hoang; Li, Mai Suan

    2014-01-01

    The influence of water models SPC, SPC/E, TIP3P, and TIP4P on ligand binding affinity is examined by calculating the binding free energy ΔG(bind) of oseltamivir carboxylate (Tamiflu) to the wild type of glycoprotein neuraminidase from the pandemic A/H5N1 virus. ΔG(bind) is estimated by the Molecular Mechanic-Poisson Boltzmann Surface Area method and all-atom simulations with different combinations of these aqueous models and four force fields AMBER99SB, CHARMM27, GROMOS96 43a1, and OPLS-AA/L. It is shown that there is no correlation between the binding free energy and the water density in the binding pocket in CHARMM. However, for three remaining force fields ΔG(bind) decays with increase of water density. SPC/E provides the lowest binding free energy for any force field, while the water effect is the most pronounced in CHARMM. In agreement with the popular GROMACS recommendation, the binding score obtained by combinations of AMBER-TIP3P, OPLS-TIP4P, and GROMOS-SPC is the most relevant to the experiments. For wild-type neuraminidase we have found that SPC is more suitable for CHARMM than TIP3P recommended by GROMACS for studying ligand binding. However, our study for three of its mutants reveals that TIP3P is presumably the best choice for CHARMM.

  19. SHBG (Sex Hormone Binding Globulin)

    MedlinePlus

    ... as: Testosterone-estrogen Binding Globulin; TeBG Formal name: Sex Hormone Binding Globulin Related tests: Testosterone , Free Testosterone, ... I should know? How is it used? The sex hormone binding globulin (SHBG) test may be used ...

  20. How to deal with multiple binding poses in alchemical relative protein-ligand binding free energy calculations.

    PubMed

    Kaus, Joseph W; Harder, Edward; Lin, Teng; Abel, Robert; McCammon, J Andrew; Wang, Lingle

    2015-06-09

    Recent advances in improved force fields and sampling methods have made it possible for the accurate calculation of protein–ligand binding free energies. Alchemical free energy perturbation (FEP) using an explicit solvent model is one of the most rigorous methods to calculate relative binding free energies. However, for cases where there are high energy barriers separating the relevant conformations that are important for ligand binding, the calculated free energy may depend on the initial conformation used in the simulation due to the lack of complete sampling of all the important regions in phase space. This is particularly true for ligands with multiple possible binding modes separated by high energy barriers, making it difficult to sample all relevant binding modes even with modern enhanced sampling methods. In this paper, we apply a previously developed method that provides a corrected binding free energy for ligands with multiple binding modes by combining the free energy results from multiple alchemical FEP calculations starting from all enumerated poses, and the results are compared with Glide docking and MM-GBSA calculations. From these calculations, the dominant ligand binding mode can also be predicted. We apply this method to a series of ligands that bind to c-Jun N-terminal kinase-1 (JNK1) and obtain improved free energy results. The dominant ligand binding modes predicted by this method agree with the available crystallography, while both Glide docking and MM-GBSA calculations incorrectly predict the binding modes for some ligands. The method also helps separate the force field error from the ligand sampling error, such that deviations in the predicted binding free energy from the experimental values likely indicate possible inaccuracies in the force field. An error in the force field for a subset of the ligands studied was identified using this method, and improved free energy results were obtained by correcting the partial charges assigned to the

  1. Aerodynamic Lifting Force.

    ERIC Educational Resources Information Center

    Weltner, Klaus

    1990-01-01

    Describes some experiments showing both qualitatively and quantitatively that aerodynamic lift is a reaction force. Demonstrates reaction forces caused by the acceleration of an airstream and the deflection of an airstream. Provides pictures of demonstration apparatus and mathematical expressions. (YP)

  2. Fluid force transducer

    DOEpatents

    Jendrzejczyk, Joseph A.

    1982-01-01

    An electrical fluid force transducer for measuring the magnitude and direction of fluid forces caused by lateral fluid flow, includes a movable sleeve which is deflectable in response to the movement of fluid, and a rod fixed to the sleeve to translate forces applied to the sleeve to strain gauges attached to the rod, the strain gauges being connected in a bridge circuit arrangement enabling generation of a signal output indicative of the magnitude and direction of the force applied to the sleeve.

  3. Giant vacuum forces via transmission lines

    PubMed Central

    Shahmoon, Ephraim; Mazets, Igor; Kurizki, Gershon

    2014-01-01

    Quantum electromagnetic fluctuations induce forces between neutral particles, known as the van der Waals and Casimir interactions. These fundamental forces, mediated by virtual photons from the vacuum, play an important role in basic physics and chemistry and in emerging technologies involving, e.g., microelectromechanical systems or quantum information processing. Here we show that these interactions can be enhanced by many orders of magnitude upon changing the character of the mediating vacuum modes. By considering two polarizable particles in the vicinity of any standard electric transmission line, along which photons can propagate in one dimension, we find a much stronger and longer-range interaction than in free space. This enhancement may have profound implications on many-particle and bulk systems and impact the quantum technologies mentioned above. The predicted giant vacuum force is estimated to be measurable in a coplanar waveguide line. PMID:25002503

  4. An integration of integrated information theory with fundamental physics

    PubMed Central

    Barrett, Adam B.

    2014-01-01

    To truly eliminate Cartesian ghosts from the science of consciousness, we must describe consciousness as an aspect of the physical. Integrated Information Theory states that consciousness arises from intrinsic information generated by dynamical systems; however existing formulations of this theory are not applicable to standard models of fundamental physical entities. Modern physics has shown that fields are fundamental entities, and in particular that the electromagnetic field is fundamental. Here I hypothesize that consciousness arises from information intrinsic to fundamental fields. This hypothesis unites fundamental physics with what we know empirically about the neuroscience underlying consciousness, and it bypasses the need to consider quantum effects. PMID:24550877

  5. An integration of integrated information theory with fundamental physics.

    PubMed

    Barrett, Adam B

    2014-01-01

    To truly eliminate Cartesian ghosts from the science of consciousness, we must describe consciousness as an aspect of the physical. Integrated Information Theory states that consciousness arises from intrinsic information generated by dynamical systems; however existing formulations of this theory are not applicable to standard models of fundamental physical entities. Modern physics has shown that fields are fundamental entities, and in particular that the electromagnetic field is fundamental. Here I hypothesize that consciousness arises from information intrinsic to fundamental fields. This hypothesis unites fundamental physics with what we know empirically about the neuroscience underlying consciousness, and it bypasses the need to consider quantum effects.

  6. Forces in General Relativity

    ERIC Educational Resources Information Center

    Ridgely, Charles T.

    2010-01-01

    Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…

  7. Debunking Coriolis Force Myths

    ERIC Educational Resources Information Center

    Shakur, Asif

    2014-01-01

    Much has been written and debated about the Coriolis force. Unfortunately, this has done little to demystify the paradoxes surrounding this fictitious force invoked by an observer in a rotating frame of reference. It is the purpose of this article to make another valiant attempt to slay the dragon of the Coriolis force! This will be done without…

  8. Crossflow force transducer. [LMFBR

    SciTech Connect

    Mulcahy, T M

    1982-05-01

    A force transducer for measuring lift and drag coefficients for a circular cylinder in turbulent water flow is presented. In addition to describing the actual design and construction of the strain-gauged force- ring based transducer, requirements for obtained valid fluid force test data are discussed, and pertinent flow test experience is related.

  9. Fundamental Principles of Proper Space Kinematics

    NASA Astrophysics Data System (ADS)

    Wade, Sean

    It is desirable to understand the movement of both matter and energy in the universe based upon fundamental principles of space and time. Time dilation and length contraction are features of Special Relativity derived from the observed constancy of the speed of light. Quantum Mechanics asserts that motion in the universe is probabilistic and not deterministic. While the practicality of these dissimilar theories is well established through widespread application inconsistencies in their marriage persist, marring their utility, and preventing their full expression. After identifying an error in perspective the current theories are tested by modifying logical assumptions to eliminate paradoxical contradictions. Analysis of simultaneous frames of reference leads to a new formulation of space and time that predicts the motion of both kinds of particles. Proper Space is a real, three-dimensional space clocked by proper time that is undergoing a densification at the rate of c. Coordinate transformations to a familiar object space and a mathematical stationary space clarify the counterintuitive aspects of Special Relativity. These symmetries demonstrate that within the local universe stationary observers are a forbidden frame of reference; all is in motion. In lieu of Quantum Mechanics and Uncertainty the use of the imaginary number i is restricted for application to the labeling of mass as either material or immaterial. This material phase difference accounts for both the perceived constant velocity of light and its apparent statistical nature. The application of Proper Space Kinematics will advance more accurate representations of microscopic, oscopic, and cosmological processes and serve as a foundation for further study and reflection thereafter leading to greater insight.

  10. The dependency of timbre on fundamental frequency.

    PubMed

    Marozeau, Jeremy; de Cheveigné, Alain; McAdams, Stephen; Winsberg, Suzanne

    2003-11-01

    The dependency of the timbre of musical sounds on their fundamental frequency (F0) was examined in three experiments. In experiment I subjects compared the timbres of stimuli produced by a set of 12 musical instruments with equal F0, duration, and loudness. There were three sessions, each at a different F0. In experiment II the same stimuli were rearranged in pairs, each with the same difference in F0, and subjects had to ignore the constant difference in pitch. In experiment III, instruments were paired both with and without an F0 difference within the same session, and subjects had to ignore the variable differences in pitch. Experiment I yielded dissimilarity matrices that were similar at different F0's, suggesting that instruments kept their relative positions within timbre space. Experiment II found that subjects were able to ignore the salient pitch difference while rating timbre dissimilarity. Dissimilarity matrices were symmetrical, suggesting further that the absolute displacement of the set of instruments within timbre space was small. Experiment III extended this result to the case where the pitch difference varied from trial to trial. Multidimensional scaling (MDS) of dissimilarity scores produced solutions (timbre spaces) that varied little across conditions and experiments. MDS solutions were used to test the validity of signal-based predictors of timbre, and in particular their stability as a function of F0. Taken together, the results suggest that timbre differences are perceived independently from differences of pitch, at least for F0 differences smaller than an octave. Timbre differences can be measured between stimuli with different F0's.

  11. Fundamental structures of dynamic social networks.

    PubMed

    Sekara, Vedran; Stopczynski, Arkadiusz; Lehmann, Sune

    2016-09-06

    Social systems are in a constant state of flux, with dynamics spanning from minute-by-minute changes to patterns present on the timescale of years. Accurate models of social dynamics are important for understanding the spreading of influence or diseases, formation of friendships, and the productivity of teams. Although there has been much progress on understanding complex networks over the past decade, little is known about the regularities governing the microdynamics of social networks. Here, we explore the dynamic social network of a densely-connected population of ∼1,000 individuals and their interactions in the network of real-world person-to-person proximity measured via Bluetooth, as well as their telecommunication networks, online social media contacts, geolocation, and demographic data. These high-resolution data allow us to observe social groups directly, rendering community detection unnecessary. Starting from 5-min time slices, we uncover dynamic social structures expressed on multiple timescales. On the hourly timescale, we find that gatherings are fluid, with members coming and going, but organized via a stable core of individuals. Each core represents a social context. Cores exhibit a pattern of recurring meetings across weeks and months, each with varying degrees of regularity. Taken together, these findings provide a powerful simplification of the social network, where cores represent fundamental structures expressed with strong temporal and spatial regularity. Using this framework, we explore the complex interplay between social and geospatial behavior, documenting how the formation of cores is preceded by coordination behavior in the communication networks and demonstrating that social behavior can be predicted with high precision.

  12. Fundamental physics of vacuum electron sources

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shigehiko

    2006-01-01

    The history of electron emission is reviewed from a standpoint of the work function that determines the electron emission capability and of applications in the fields of scientific instruments and displays. For years, in thermionic emission, a great deal of effort has been devoted to the search for low work function materials with high melting temperature, while reduction of the local change in time of the work function rather than the work function itself has been the main issue of field emission investigations. High brightness and long life are the central targets of emission material investigations for scientific instrument applications, while high current density and low power consumption are the guiding principles for display applications. In most of the present day industries, thermionic emission materials are exclusively used in such fields requiring high current and high reliability as cathode ray tubes, transmission and receiving tubes, x-ray sources and various electron beam machines. Field electron emission sources, however, since applied to high resolution electron microscopes in the 1970s have recently become dominant in research and development in the fields of scientific instruments as well as in the fields of various electron tubes and beam machines. The main issue in this report is to analyse the work function on the atomic scale and thereby to understand the fundamental physics behind the work function, the change in time of the local work function leading to field emission current fluctuation and the relationship between microscopic (on atomic scale) and macroscopic work functions. Our attempt is presented here, where the work function on the atomic scale is measured by utilizing a scanning tunnelling microscopy technique, and it is made clear how far the local work function extends its influence over neighbouring sites. As a result, a simple relationship is established between microscopic and macroscopic work functions.

  13. Fundamental formulae for wave-energy conversion.

    PubMed

    Falnes, Johannes; Kurniawan, Adi

    2015-03-01

    The time-average wave power that is absorbed from an incident wave by means of a wave-energy conversion (WEC) unit, or by an array of WEC units-i.e. oscillating immersed bodies and/or oscillating water columns (OWCs)-may be mathematically expressed in terms of the WEC units' complex oscillation amplitudes, or in terms of the generated outgoing (diffracted plus radiated) waves, or alternatively, in terms of the radiated waves alone. Following recent controversy, the corresponding three optional expressions are derived, compared and discussed in this paper. They all provide the correct time-average absorbed power. However, only the first-mentioned expression is applicable to quantify the instantaneous absorbed wave power and the associated reactive power. In this connection, new formulae are derived that relate the 'added-mass' matrix, as well as a couple of additional reactive radiation-parameter matrices, to the difference between kinetic energy and potential energy in the water surrounding the immersed oscillating WEC array. Further, a complex collective oscillation amplitude is introduced, which makes it possible to derive, by a very simple algebraic method, various simple expressions for the maximum time-average wave power that may be absorbed by the WEC array. The real-valued time-average absorbed power is illustrated as an axisymmetric paraboloid defined on the complex collective-amplitude plane. This is a simple illustration of the so-called 'fundamental theorem for wave power'. Finally, the paper also presents a new derivation that extends a recently published result on the direction-average maximum absorbed wave power to cases where the WEC array's radiation damping matrix may be singular and where the WEC array may contain OWCs in addition to oscillating bodies.

  14. Fundamental structures of dynamic social networks

    PubMed Central

    Sekara, Vedran; Stopczynski, Arkadiusz; Lehmann, Sune

    2016-01-01

    Social systems are in a constant state of flux, with dynamics spanning from minute-by-minute changes to patterns present on the timescale of years. Accurate models of social dynamics are important for understanding the spreading of influence or diseases, formation of friendships, and the productivity of teams. Although there has been much progress on understanding complex networks over the past decade, little is known about the regularities governing the microdynamics of social networks. Here, we explore the dynamic social network of a densely-connected population of ∼1,000 individuals and their interactions in the network of real-world person-to-person proximity measured via Bluetooth, as well as their telecommunication networks, online social media contacts, geolocation, and demographic data. These high-resolution data allow us to observe social groups directly, rendering community detection unnecessary. Starting from 5-min time slices, we uncover dynamic social structures expressed on multiple timescales. On the hourly timescale, we find that gatherings are fluid, with members coming and going, but organized via a stable core of individuals. Each core represents a social context. Cores exhibit a pattern of recurring meetings across weeks and months, each with varying degrees of regularity. Taken together, these findings provide a powerful simplification of the social network, where cores represent fundamental structures expressed with strong temporal and spatial regularity. Using this framework, we explore the complex interplay between social and geospatial behavior, documenting how the formation of cores is preceded by coordination behavior in the communication networks and demonstrating that social behavior can be predicted with high precision. PMID:27555584

  15. Fundamental bioprocessing research for coal applications

    SciTech Connect

    Kaufman, E.N.; Scott, T.C.

    1995-06-01

    The purpose of this program is to gain a fundamental understanding and sound scientific and technical basis for evaluating the potential roles of innovative bioprocessing concepts for the utilization and conversion of coal. The aim is to explore the numerous ways in which advanced biological processes and techniques can open new opportunities for coal utilization or can replace more conventional techniques by using milder conditions with less energy consumption or loss. There are several roles where biotechnology is likely to be important in coal utilization and conversion. These include potential bioprocessing systems such as conversion of coal to liquids or gases; biocatalytic beneficiation of coal-derived liquids and conversion to useful chemical feedstocks; biocatalytic removal of SO{sub x} and NO{sub x} from coal combustion off-gas; environmental control technology for the removal or destruction of hazardous materials in process effluents and/or solid residues; and the removal and utilization of CO{sub 2} from combustion off-gas. Effective bioprocesses for such applications will require detailed knowledge of the biological process mechanisms and advanced bioreactor technology than can be optimized for high productivity, as well as supporting upstream and downstream processes that will allow an effective integrated bioprocess. Of particular interest is the development of predictive models that can be used for process design and scaleup. In this program, a generic approach is taken so that there will be utility over a broad range of applications. In conjunction with the generic approach, model experimental systems that address real-world problems are used to verify the results.

  16. Fundamental Neutron Physics: Theory and Analysis

    SciTech Connect

    Gudkov, Vladimir

    2016-10-31

    The goal of the proposal was to study the possibility of searching for manifestations of new physics beyond the Standard model in fundamental neutron physics experiments. This involves detailed theoretical analyses of parity and time reversal invariance violating processes in neutron induced reactions, properties of neutron β-decay, and the precise description of properties of neutron interactions with nuclei. To describe neutron-nuclear interactions, we use both the effective field theory approach and the theory of nuclear reaction with phenomenological nucleon potentials for the systematic description of parity and time reversal violating effects in the consistent way. A major emphasis of our research during the funding period has been the study of parity violation (PV) and time reversal invariance violation (TRIV) in few-body systems. We studied PV effects in non-elastic processes in three nucleon system using both ”DDH-like” and effective field theory (EFT) approaches. The wave functions were obtained by solving three-body Faddeev equations in configuration space for a number of realistic strong potentials. The observed model dependence for the DDH approach indicates intrinsic difficulty in the description of nuclear PV effects and it could be the reason for the observed discrepancies in the nuclear PV data analysis. It shows that the DDH approach could be a reasonable approach for analysis of PV effects only if exactly the same strong and weak potentials are used in calculating all PV observables in all nuclei. However, the existing calculations of nuclear PV effects were performed using different potentials; therefore, strictly speaking, one cannot compare the existing results of these calculations among themselves.

  17. STAR CLUSTERS, GALAXIES, AND THE FUNDAMENTAL MANIFOLD

    SciTech Connect

    Zaritsky, Dennis; Zabludoff, Ann I.; Gonzalez, Anthony H. E-mail: azabludoff@as.arizona.edu

    2011-02-01

    We explore whether global observed properties, specifically half-light radii, mean surface brightness, and integrated stellar kinematics, suffice to unambiguously differentiate galaxies from star clusters, which presumably formed differently and lack dark matter halos. We find that star clusters lie on the galaxy scaling relationship referred to as the fundamental manifold (FM), on the extension of a sequence of compact galaxies, and so conclude that there is no simple way to differentiate star clusters from ultracompact galaxies. By extending the validity of the FM over a larger range of parameter space and a wider set of objects, we demonstrate that the physics that constrains the resulting baryon and dark matter distributions in stellar systems is more general than previously appreciated. The generality of the FM implies (1) that the stellar spatial distribution and kinematics of one type of stellar system do not arise solely from a process particular to that set of systems, such as violent relaxation for elliptical galaxies, but are instead the result of an interplay of all processes responsible for the generic settling of baryons in gravitational potential wells, (2) that the physics of how baryons settle is independent of whether the system is embedded within a dark matter halo, and (3) that peculiar initial conditions at formation or stochastic events during evolution do not ultimately disturb the overall regularity of baryonic settling. We also utilize the relatively simple nature of star clusters to relate deviations from the FM to the age of the stellar population and find that stellar population models systematically and significantly overpredict the mass-to-light ratios of old, metal-rich clusters. We present an empirical calibration of stellar population mass-to-light ratios with age and color. Finally, we use the FM to estimate velocity dispersions for the low surface brightness, outer halo clusters that lack such measurements.

  18. The dependency of timbre on fundamental frequency

    NASA Astrophysics Data System (ADS)

    Marozeau, Jeremy; de Cheveigné, Alain; McAdams, Stephen; Winsberg, Suzanne

    2003-11-01

    The dependency of the timbre of musical sounds on their fundamental frequency (F0) was examined in three experiments. In experiment I subjects compared the timbres of stimuli produced by a set of 12 musical instruments with equal F0, duration, and loudness. There were three sessions, each at a different F0. In experiment II the same stimuli were rearranged in pairs, each with the same difference in F0, and subjects had to ignore the constant difference in pitch. In experiment III, instruments were paired both with and without an F0 difference within the same session, and subjects had to ignore the variable differences in pitch. Experiment I yielded dissimilarity matrices that were similar at different F0's, suggesting that instruments kept their relative positions within timbre space. Experiment II found that subjects were able to ignore the salient pitch difference while rating timbre dissimilarity. Dissimilarity matrices were symmetrical, suggesting further that the absolute displacement of the set of instruments within timbre space was small. Experiment III extended this result to the case where the pitch difference varied from trial to trial. Multidimensional scaling (MDS) of dissimilarity scores produced solutions (timbre spaces) that varied little across conditions and experiments. MDS solutions were used to test the validity of signal-based predictors of timbre, and in particular their stability as a function of F0. Taken together, the results suggest that timbre differences are perceived independently from differences of pitch, at least for F0 differences smaller than an octave. Timbre differences can be measured between stimuli with different F0's.

  19. Fundamental formulae for wave-energy conversion

    PubMed Central

    Falnes, Johannes; Kurniawan, Adi

    2015-01-01

    The time-average wave power that is absorbed from an incident wave by means of a wave-energy conversion (WEC) unit, or by an array of WEC units—i.e. oscillating immersed bodies and/or oscillating water columns (OWCs)—may be mathematically expressed in terms of the WEC units' complex oscillation amplitudes, or in terms of the generated outgoing (diffracted plus radiated) waves, or alternatively, in terms of the radiated waves alone. Following recent controversy, the corresponding three optional expressions are derived, compared and discussed in this paper. They all provide the correct time-average absorbed power. However, only the first-mentioned expression is applicable to quantify the instantaneous absorbed wave power and the associated reactive power. In this connection, new formulae are derived that relate the ‘added-mass’ matrix, as well as a couple of additional reactive radiation-parameter matrices, to the difference between kinetic energy and potential energy in the water surrounding the immersed oscillating WEC array. Further, a complex collective oscillation amplitude is introduced, which makes it possible to derive, by a very simple algebraic method, various simple expressions for the maximum time-average wave power that may be absorbed by the WEC array. The real-valued time-average absorbed power is illustrated as an axisymmetric paraboloid defined on the complex collective-amplitude plane. This is a simple illustration of the so-called ‘fundamental theorem for wave power’. Finally, the paper also presents a new derivation that extends a recently published result on the direction-average maximum absorbed wave power to cases where the WEC array's radiation damping matrix may be singular and where the WEC array may contain OWCs in addition to oscillating bodies. PMID:26064612

  20. Equilibrium capillary forces with atomic force microscopy.

    PubMed

    Sprakel, J; Besseling, N A M; Leermakers, F A M; Cohen Stuart, M A

    2007-09-07

    We present measurements of equilibrium forces resulting from capillary condensation. The results give access to the ultralow interfacial tensions between the capillary bridge and the coexisting bulk phase. We demonstrate this with solutions of associative polymers and an aqueous mixture of gelatin and dextran, with interfacial tensions around 10 microN/m. The equilibrium nature of the capillary forces is attributed to the combination of a low interfacial tension and a microscopic confinement geometry, based on nucleation and growth arguments.