78 FR 61949 - Order Relating to Afshin (“Sean”) Naghibi

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-08

... the conspiracy was to bring about the export of ultrasound equipment and related accessories, items... Raytec SA (``Raytec''), to ship ultrasound units for UMI to Taban Saar in Iran for a small commission... them with the following text. `The coppers bvba [sic] sell all ultrasound machines to the belgium [sic...

Experimental evidence for a crossover between two distinct mechanisms of amorphization in ice Ih under pressure.

PubMed

Strässle, Thierry; Klotz, Stefan; Hamel, Gérard; Koza, Michael M; Schober, Helmut

2007-10-26

We report neutron scattering data which reveal the central role of phonon softening leading to a negative melting line, solid-state amorphization, and negative thermal expansion of ice. We find that pressure-induced amorphization is due to mechanical melting at low temperatures, while at higher temperatures amorphization is governed by thermal melting (violations of Born's and Lindemann's criteria, respectively). This confirms earlier conjectures of a crossover between two distinct amorphization mechanisms and provides a natural explanation for the strong annealing observed in high-density amorphous ice.

A quantum dynamical study of the He++2He-->He2++He reaction

NASA Astrophysics Data System (ADS)

Xie, Junkai; Poirier, Bill; Gellene, Gregory I.

2003-11-01

The temperature dependent rate of the He++2He→He2++He three-body association reaction is studied using two complementary quantum dynamical models. Model I presumes a two-step, reverse Lindemann mechanism, where the intermediate energized complex, He2+*, is interpreted as the rotational resonance states of He2+. The energy and width of these resonances are determined via "exact" quantum calculation using highly accurate potential-energy curves. Model II uses an alternate quantum rate expression as the thermal average of the cumulative recombination probability, N(E). This microcanonical quantity is computed approximately, over the He2+ space only, with the third-body interaction modeled using a special type of absorbing potential. Because Model II implicitly incorporates both the two-step reverse Lindemann mechanism, and a one-step, reverse collision induced dissociation mechanism, the relative importance of the two formation mechanisms can be estimated by a comparison of the Model I and Model II results. For T<300 K, the reaction is found to be dominated by the two-step mechanism, and a formation rate in good agreement with the available experimental results is obtained with essentially no adjustable parameters in the theory. Interestingly, a nonmonotonic He2+ formation rate is observed, with a maximum identified near 25 K. This maximum is associated with just two reaction intermediate resonance states, the lowest energy states that can contribute significantly to the formation kinetics.

Anisotropic Defect-Mediated Melting of Two-Dimensional Colloidal Crystals

NASA Astrophysics Data System (ADS)

Eisenmann, C.; Gasser, U.; Keim, P.; Maret, G.

2004-09-01

The melting transition of anisotropic two-dimensional (2D) crystals is studied in a model system of superparamagnetic colloids. The anisotropy of the induced dipole-dipole interaction is varied by tilting the external magnetic field off the normal to the particle plane. By analyzing the time-dependent Lindemann parameter as well as translational and orientational order we observe a 2D smecticlike phase. The Kosterlitz-Thouless-Halperin-Nelson-Young scenario of isotropic melting is modified: dislocation pairs and dislocations appear with different probabilities depending on their orientation with respect to the in-plane field.

The 2017 Eclipse: Centenary of the Einstein Light Deflection Experiment

NASA Astrophysics Data System (ADS)

Kennefick, Daniel

2017-01-01

August 21st, 2017 will see a total eclipse of the Sun visible in many parts of the United States. Coincidentally this date marks the centenary of the first observational attempt to test Einstein's General Theory of Relativity by measuring gravitational deflection of light by the Sun. This was attempted by the Kodaikanal Observatory in India during the conjunction of Regulus with the Sun in daylight on August 21st, 1917. The observation was attempted at the urging of the amateur German-British astronomer A. F. Lindemann, with his son, F. A. Lindemann, a well-known physicist, who later played a significant role as Churchill's science advisor during World War II. A century later Regulus will once again be in conjunction with the Sun, but by a remarkable coincidence, this will occur during a solar eclipse! Efforts will be made to measure the star deflection during the eclipse and the experiment is contrasted with the famous expeditions of 1919 which were the first to actually measure the light deflection, since the 1917 effort did not meet with success. Although in recent decades there have been efforts made to suggest that the 1919 eclipse team, led by Arthur Stanley Eddington and Sir Frank Watson Dyson, over-interpreted their results in favor of Einstein this talk will argue that such claims are wrong-headed. A close study of their data analysis reveals that they had good grounds for the decisions they made and this conclusion is reinforced by comparison with a modern re-analysis of the plates by the Greenwich Observatory conducted in 1977.

Molecular dynamics simulations of melting and the glass transition of nitromethane.

PubMed

Zheng, Lianqing; Luo, Sheng-Nian; Thompson, Donald L

2006-04-21

Molecular dynamics simulations have been used to investigate the thermodynamic melting point of the crystalline nitromethane, the melting mechanism of superheated crystalline nitromethane, and the physical properties of crystalline and glassy nitromethane. The maximum superheating and glass transition temperatures of nitromethane are calculated to be 316 and 160 K, respectively, for heating and cooling rates of 8.9 x 10(9) Ks. Using the hysteresis method [Luo et al., J. Chem. Phys. 120, 11640 (2004)] and by taking the glass transition temperature as the supercooling temperature, we calculate a value of 251.1 K for the thermodynamic melting point, which is in excellent agreement with the two-phase result [Agrawal et al., J. Chem. Phys. 119, 9617 (2003)] of 255.5 K and measured value of 244.73 K. In the melting process, the nitromethane molecules begin to rotate about their lattice positions in the crystal, followed by translational freedom of the molecules. A nucleation mechanism for the melting is illustrated by the distribution of the local translational order parameter. The critical values of the Lindemann index for the C and N atoms immediately prior to melting (the Lindemann criterion) are found to be around 0.155 at 1 atm. The intramolecular motions and molecular structure of nitromethane undergo no abrupt changes upon melting, indicating that the intramolecular degrees of freedom have little effect on the melting. The thermal expansion coefficient and bulk modulus are predicted to be about two or three times larger in crystalline nitromethane than in glassy nitromethane. The vibrational density of states is almost identical in both phases.

Migrating To The Cloud: Preparing The USMC CDET For MCEITS

DTIC Science & Technology

2016-03-01

Service SAAR System Authorization Access Request SaaS Software as a... Service (IaaS), Platform as a Service (PaaS), Software as a Service ( SaaS ), and Data as a Service (DaaS) (Takai, 2012). A closer examination of each...8 3. Software as a Service NIST described SaaS as a model of cloud computing where the service provider offers its customers fee-based access

East Europe Report, Economic and Industrial Affairs

DTIC Science & Technology

1984-08-20

plant with wet desulfurization of flue gas . This method was pre- viously only successful with hard coal. Before the end of this year a large- scale...REPUBLIC DM 40 Million Euro Credit to Foreign Trade Organization (HANDELSBLATT, 2 Jul 84) 21 Minister Interested in Flue Gas Desulfurization Equipment...Zurich and the Rhein-Saar-Lux AG. 12644 CSO: 2300/565 21 GERMAN DEMOCRATIC REPUBLIC MINISTER INTERESTED IN FLUE GAS DESULFURIZATION EQUIPMENT

Fat stigma and public health: a theoretical framework and ethical analysis.

PubMed

Abu-Odeh, Desiree

2014-09-01

This paper proposes a theoretical framework for understanding fat stigma and its impact on people's well-being. It argues that stigma should never be used as a tool to achieve public health ends. Drawing on Bruce Link and Jo Phelan's 2001 conceptualization of stigma as well as the works of Hilde Lindemann, Paul Benson, and Margaret Urban Walker on identity, positionality, and agency, this paper clarifies the mechanisms by which stigmatizing, oppressive conceptions of overweight and obesity damage identities and diminish moral agency, arguing that the use of obesity-related stigma for public health ends violates the bioethics principles of nonmaleficence, autonomy, and justice.

Hetero-phase fluctuations in the pre-melting region in ionic crystals

NASA Astrophysics Data System (ADS)

Matsunaga, S.; Tamaki, S.

2008-06-01

The theory of the pre-melting phenomena in ionic crystals on the basis of the concept of the hetero phase fluctuation has been applied to KCl and AgCl crystal. The large scale molecular dynamics simulations (MD) in KCl and AgCl crystals are also performed to examine the ionic configuration in premelting region in the vicinity of their melting points. The size of the liquid like clusters are estimated by the theory and MD. The structural features of liquid like clusters are discussed by MD results using the Lindemann instability condition. The ionic conductivities in the pre-melting region are also discussed on the same theoretical basis.

Birthing Ethics: What Mothers, Families, Childbirth Educators, Nurses, and Physicians Should Know About the Ethics of Childbirth

PubMed Central

Torres, Jennifer M; De Vries, Raymond G

2009-01-01

This article discusses current ethical issues associated with childbirth in the United States. It provides a review of moral problems and ethical choices made by parents and health-care professionals during the prenatal, intrapartum, and postpartum periods. Ethical issues are identified and framed through a “naturalized bioethics” approach, as recommended by Margaret Walker and her colleagues, Hilde Lindemann and Marian Verkerk. This approach critiques traditional bioethics and gives attention to everyday ethics and the social, economic, and political context within which ethical problems exist. This approach provides the reader with the tools needed to critically assess the way ethical problems are defined and resolved. PMID:19360141

Coulomb structures of charged macroparticles in static magnetic traps at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Vasiliev, M. M.; Petrov, O. F.; Statsenko, K. B.

2015-12-01

Electrically charged (up to 107 e) macroscopic superconducting particles with sizes in the micrometer range confined in a static magnetic trap in liquid nitrogen and in nitrogen vapor at temperatures of 77-91 K are observed experimentally. The macroparticles with sizes up to 60 μm levitate in a nonuniform static magnetic field B ~ 2500 G. The formation of strongly correlated structures comprising as many as ~103 particles is reported. The average particle distance in these structures amounts to 475 μm. The coupling parameter and the Lindemann parameter of these structures are estimated to be ~107 and ~0.03, respectively, which is characteristic of strongly correlated crystalline or glasslike structures.

[The Homburg clinic for nervous diseases in the National Socialist Era. Special features in the Saarland border region].

PubMed

Keller, I; Flöter, C; Ragoschke-Schumm, A; Faßbender, K

2016-02-01

When the National Socialists (NS) came to power in 1933, the German health care system was reorganized according to the principles of eugenics. Neuropsychiatric patients were victims of compulsory sterilisation and "euthanasia". As the Saar territory did not become part of the German Reich until the 1 March 1935, it is of special interest how quickly and completely NS health care policies were implemented. The analysis is based on medical records of the Homburg State Hospital's (HSH) clinic for nervous diseases from 1929 to 1945 (n =7,816) found in the Saarland University Medical Centre. 1,452 patients were sterilised by force between 1935 and 1939 in the HSH. The most frequent diagnoses were congenital debility, schizophrenia, and epilepsy. Some of the 441 Homburg patients who were transferred to other mental hospitals from 1939 to 1940 were killed in the context of "Aktion T4" and presumably in a nonsystematic manner. NS health care policies were implemented immediately after incorporation of the Saar territory in 1935. Physicians of the HSH were involved directly in compulsory sterilisation of neuropsychiatric patients. An initial intention to kill by the time of patient transfers from Homburg cannot be proven. Further research concerning the killing centres is necessary.

JPRS Report, West Europe.

DTIC Science & Technology

1998-06-01

choice. At that time, Geissler still held the post of minister of social affairs in Rhineland- Palatinate and party chairman Kohl, the then minister...Georg Welsch, a 41-year-old economist, who captured the influential post of director of munici- pal affairs. Welsch, who is fond of appearing in...in the Saar ministry of culture, to the prestigious cultural affairs post . FRANKFURTER ALLGEMEINE has called him a "well-versed expert in cultural

Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars. Symposium of the International Astronomical Union (286th) Held in Mendoza, Argentina on October 3-7, 2011

DTIC Science & Technology

2011-10-01

11:15 – 11:45 Invited Talk – Stars in Magnetic Grand Minima: Where Are They and What Are They Like? Steven Saar (Presentation file) 11:45 – 12:00...of Archaeology and Ancient History, University Rd, Leicester LE1 7RH, United Kingdom IAUS 279 Death of Massive Stars: Supernovae and Gamma-Ray Bursts...of Astronomy & Astrophysics, 525 Davey Lab, University Park, PA 16802, USA IAUS 283 Planetary Nebulae: an Eye to the Future A. MANCHADO, Instituto de

Theory of melting at high pressures: Amending density functional theory with quantum Monte Carlo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shulenburger, L.; Desjarlais, M. P.; Mattsson, T. R.

We present an improved first-principles description of melting under pressure based on thermodynamic integration comparing Density Functional Theory (DFT) and quantum Monte Carlo (QMC) treatments of the system. The method is applied to address the longstanding discrepancy between density functional theory (DFT) calculations and diamond anvil cell (DAC) experiments on the melting curve of xenon, a noble gas solid where van der Waals binding is challenging for traditional DFT methods. The calculations show excellent agreement with data below 20 GPa and that the high-pressure melt curve is well described by a Lindemann behavior up to at least 80 GPa, amore » finding in stark contrast to DAC data.« less

On high-pressure melting of tantalum

NASA Astrophysics Data System (ADS)

Luo, Sheng-Nian; Swift, Damian C.

2007-01-01

The issues related to high-pressure melting of Ta are discussed within the context of diamond-anvil cell (DAC) and shock wave experiments, theoretical calculations and common melting models. The discrepancies between the extrapolations of the DAC melting curve and the melting point inferred from shock wave experiments, cannot be reconciled either by superheating or solid-solid phase transition. The failure to reproduce low-pressure DAC melting curve by melting models such as dislocation-mediated melting and the Lindemann law, and molecular dynamics and quantum mechanics-based calculations, undermines their predictions at moderate and high pressures. Despite claims to the contrary, the melting curve of Ta (as well as Mo and W) remains inconclusive at high pressures.

Local symmetries and order-disorder transitions in small macroscopic Wigner islands.

PubMed

Coupier, Gwennou; Guthmann, Claudine; Noat, Yves; Jean, Michel Saint

2005-04-01

The influence of local order on the disordering scenario of small Wigner islands is discussed. A first disordering step is put in evidence by the time correlation functions and is linked to individual excitations resulting in configuration transitions, which are very sensitive to the local symmetries. This is followed by two other transitions, corresponding to orthoradial and radial diffusion, for which both individual and collective excitations play a significant role. Finally, we show that, contrary to large systems, the focus that is commonly made on collective excitations for such small systems through the Lindemann criterion has to be made carefully in order to clearly identify the relative contributions in the whole disordering process.

Premelting phenomena in pseudo-binary ionic crystals

NASA Astrophysics Data System (ADS)

Matsunaga, Shigeki

2010-04-01

The theory of the premelting phenomena in ionic crystals on the basis of the concept of the heterophase fluctuation has been applied to the pseudo-binary ionic crystals, KCl-NaCl, AgBr-AgCl and AgBr-CuBr systems. Molecular dynamics simulations (MD) have been performed to examine the ionic configurations in their premelting region in the vicinity of their melting points. Liquid-like clusters have been observed in the results of MD utilizing the Lindemann instability condition. The sizes of liquid-like clusters have been estimated by theory and MD. The characteristics of the dynamical behavior of ions in the premelting region have been examined by the mean square displacement and the velocity correlation functions.

Theory of melting at high pressures: Amending density functional theory with quantum Monte Carlo

DOE PAGES

Shulenburger, L.; Desjarlais, M. P.; Mattsson, T. R.

2014-10-01

We present an improved first-principles description of melting under pressure based on thermodynamic integration comparing Density Functional Theory (DFT) and quantum Monte Carlo (QMC) treatments of the system. The method is applied to address the longstanding discrepancy between density functional theory (DFT) calculations and diamond anvil cell (DAC) experiments on the melting curve of xenon, a noble gas solid where van der Waals binding is challenging for traditional DFT methods. The calculations show excellent agreement with data below 20 GPa and that the high-pressure melt curve is well described by a Lindemann behavior up to at least 80 GPa, amore » finding in stark contrast to DAC data.« less

Applications of liquid state physics to the earth's core

NASA Technical Reports Server (NTRS)

Stevenson, D. J.

1980-01-01

New results derived for application to the earth's outer core using the modern theory of liquids and the hard-sphere model of liquid structure are presented. An expression derived in terms of the incompressibility and pressure is valid for a high-pressure liquid near its melting point, provided that the pressure is derived from a strongly repulsive pair potential; a relation derived between the melting point and density leads to a melting curve law of essentially the same form as Lindemann's law. Finally, it is shown that the 'core paradox' of Higgins and Kennedy (1971) can occur only if the Gruneisen parameter is smaller than 2/3, and this constant is larger than this value in any liquid for which the pair potential is strongly repulsive.

Aromatized arborane/fernane hydrocarbons as biomarkers for cordaites

NASA Astrophysics Data System (ADS)

Auras, Stefan; Wilde, Volker; Scheffler, Kay; Hoernes, Stephan; Kerp, Hans; Püttmann, Wilhelm

2006-12-01

Previous palaeobotanical and palynological studies on coals from Euramerican Pennsylvanian (≡ Late Carboniferous) coal basins indicate a major change in coal-swamp floras, especially at the Westphalian Stephanian (≈Kasimovian Gzhelian, according to Geological Time Scale 2004) boundary. A flora dominated by arborescent lycophytes was replaced by a vegetation dominated by marattialean tree ferns in various Euramerican coal basins. Earlier combined palynological and organic geochemical studies on Westphalian/Stephanian coals and shales from the Saar-Nahe Basin (Germany) revealed that the distribution of aromatized arborane/fernane hydrocarbons in solvent extracts reflects the increasing importance of seed plants, especially cordaites (extinct group of gymnosperms), conifers and pteridosperms. However, the biological source of the precursor molecules could not be specified. To clarify if the arborane/fernane derivatives MATH, MAPH, DAPH 1, and DAPH 2 in Westphalian/Stephanian coals can be assigned to one of the three potential source plant groups, we analyzed coals, sediments and fossil plant remains from different Euramerican locations with respect to their biomarker composition and stable carbon isotopic composition. Thereby, stable carbon isotopic ratios showed only insignificant variations between Westphalian and Stephanian samples and proved to be an unsuitable tool to describe floral changes during the Westphalian/Stephanian of the Saar-Nahe Basin. In contrast, we were able to show for the first time that MATH, MAPH, DAPH 1 and DAPH 2 are prominent constituents only in extracts of cordaitean macrofossils and can therefore be regarded as biomarkers for this group of gymnosperms.

Aromatized arborane/fernane hydrocarbons as biomarkers for cordaites.

PubMed

Auras, Stefan; Wilde, Volker; Scheffler, Kay; Hoernes, Stephan; Kerp, Hans; Püttmann, Wilhelm

2006-12-01

Previous palaeobotanical and palynological studies on coals from Euramerican Pennsylvanian ( identical with Late Carboniferous) coal basins indicate a major change in coal-swamp floras, especially at the Westphalian-Stephanian ( approximately Kasimovian-Gzhelian, according to Geological Time Scale 2004) boundary. A flora dominated by arborescent lycophytes was replaced by a vegetation dominated by marattialean tree ferns in various Euramerican coal basins. Earlier combined palynological and organic geochemical studies on Westphalian/Stephanian coals and shales from the Saar-Nahe Basin (Germany) revealed that the distribution of aromatized arborane/fernane hydrocarbons in solvent extracts reflects the increasing importance of seed plants, especially cordaites (extinct group of gymnosperms), conifers and pteridosperms. However, the biological source of the precursor molecules could not be specified. To clarify if the arborane/fernane derivatives MATH, MAPH, DAPH 1, and DAPH 2 in Westphalian/Stephanian coals can be assigned to one of the three potential source plant groups, we analyzed coals, sediments and fossil plant remains from different Euramerican locations with respect to their biomarker composition and stable carbon isotopic composition. Thereby, stable carbon isotopic ratios showed only insignificant variations between Westphalian and Stephanian samples and proved to be an unsuitable tool to describe floral changes during the Westphalian/Stephanian of the Saar-Nahe Basin. In contrast, we were able to show for the first time that MATH, MAPH, DAPH 1 and DAPH 2 are prominent constituents only in extracts of cordaitean macrofossils and can therefore be regarded as biomarkers for this group of gymnosperms.

Shock-induced superheating and melting curves of geophysically important minerals

NASA Astrophysics Data System (ADS)

Luo, Sheng-Nian; Ahrens, Thomas J.

2004-06-01

Shock-state temperature and sound-speed measurements on crystalline materials, demonstrate superheating-melting behavior distinct from equilibrium melting. Shocked solid can be superheated to the maximum temperature, Tc'. At slightly higher pressure, Pc, shock melting occurs, and induces a lower shock temperature, Tc. The Hugoniot state, ( Pc, Tc), is inferred to lie along the equilibrium melting curve. The amount of superheating achieved on Hugoniot is, ΘH+= Tc'/ Tc-1. Shock-induced superheating for a number of silicates, alkali halides and metals agrees closely with the predictions of a systematic framework describing superheating at various heating rates [Appl. Phys. Lett. 82 (12) (2003) 1836]. High-pressure melting curves are constructed by integration from ( Pc, Tc) based on the Lindemann law. We calculate the volume and entropy changes upon melting at ( Pc, Tc) assuming the R ln 2 rule ( R is the gas constant) for the disordering entropy of melting [J. Chem. Phys. 19 (1951) 93; Sov. Phys. Usp. 117 (1975) 625; Poirier, J.P., 1991. Introduction to the Physics of the Earth's Interior. Cambridge University Press, Cambridge, 102 pp.]. ( Pc, Tc) and the Lindemann melting curves are in excellent accord with diamond-anvil cell (DAC) results for NaCl, KBr and stishovite. But significant discrepancies exist for transition metals. If we extrapolate the DAC melting data [Phys. Rev. B 63 (2001) 132104] for transition metals (Fe, V, Mo, W and Ta) to 200-400 GPa where shock melting occurs, shock temperature measurement and calculation would indicate ΘH+˜0.7-2.0. These large values of superheating are not consistent with the superheating systematics. The discrepancies could be reconciled by possible solid-solid phase transitions at high pressures. In particular, this work suggests that Fe undergoes a possible solid-solid phase transition at ˜200 GPa and melts at ˜270 GPa upon shock wave loading, and the melting temperature is ˜6300 K at 330 GPa.

Thermodynamics of freezing and melting

PubMed Central

Pedersen, Ulf R.; Costigliola, Lorenzo; Bailey, Nicholas P.; Schrøder, Thomas B.; Dyre, Jeppe C.

2016-01-01

Although the freezing of liquids and melting of crystals are fundamental for many areas of the sciences, even simple properties like the temperature–pressure relation along the melting line cannot be predicted today. Here we present a theory in which properties of the coexisting crystal and liquid phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio), and the liquid's diffusion constant and viscosity. The framework developed, which applies for the sizable class of systems characterized by hidden scale invariance, is validated by computer simulations of the standard 12-6 Lennard-Jones system. PMID:27530064

Phase behavior of charged colloids at a fluid interface

NASA Astrophysics Data System (ADS)

Kelleher, Colm P.; Guerra, Rodrigo E.; Hollingsworth, Andrew D.; Chaikin, Paul M.

2017-02-01

We study the phase behavior of a system of charged colloidal particles that are electrostatically bound to an almost flat interface between two fluids. We show that, despite the fact that our experimental system consists of only 103-104 particles, the phase behavior is consistent with the theory of melting due to Kosterlitz, Thouless, Halperin, Nelson, and Young. Using spatial and temporal correlations of the bond-orientational order parameter, we classify our samples into solid, isotropic fluid, and hexatic phases. We demonstrate that the topological defect structure we observe in each phase corresponds to the predictions of Kosterlitz-Thouless-Halperin-Nelson-Young theory. By measuring the dynamic Lindemann parameter γL(τ ) and the non-Gaussian parameter α2(τ ) of the displacements of the particles relative to their neighbors, we show that each of the phases displays distinctive dynamical behavior.

Narrative ARTifice and women's agency.

PubMed

Kalbian, Aline H

2005-04-01

The choice to pursue fertility treatments is a complex one. In this paper I explore the issues of choice, agency, and gender as they relate to assisted reproductive technologies (ARTs). I argue that narrative approaches to bioethics such as those by Arthur Frank and Hilde Lindemann Nelson clarify judgments about autonomy and fertility medicine. More specifically, I propose two broad narrative categories that help capture the experience of encounters with fertility medicine: narratives of hope and narratives of resistance. This narrative typology captures the inevitable conflict that women feel when they become subjects of fertility medicine. On the one hand, they must remain hopeful; on the other, they must not surrender themselves completely. Nelson's account of counterstories as narratives of resistance helps us see how women can reconcile the experience of a strong desire to have children with the desire to remain authentic and whole.

Analysis of the coupled electron-ripplon oscillations resonance spectra in the Wigner solid at different temperatures and modeling of the excitation process

NASA Astrophysics Data System (ADS)

Syvokon, V. E.; Sharapova, I. V.

2018-05-01

The spectrum of coupled electron-ripplon oscillations in a Wigner crystal on the surface of superfluid helium at various temperatures and excitation voltages, leading to spectrum distortion, was studied experimentally. It was shown that at all temperatures, increasing excitation voltage leads to the appearance of non-axisymmetric vibrational modes, which indicates distortions of the crystal lattice. The possibility of excitation of the non-axisymmetric modes in a cell was demonstrated by modeling electronic crystal oscillations using the molecular dynamics method. At several fixed frequencies, the amplitudes of the response of the electronic crystal to external excitation were measured as a function of the magnitude of excitation voltage, and jumps were detected at certain critical voltages. Using the Lindemann criterion, a correlation was found between the critical stress and stability limit of the crystal lattice. It was concluded that when the critical voltage is reached, dynamic melting of the electronic crystal occurs.

Fallbeispiel Kluftgrundwasserleiter - Charakterisierung eines Grundwasserleiters im Rotliegendsandstein des Saar-Nahe-Beckens

NASA Astrophysics Data System (ADS)

Altenbockum, Michael; Berens, Katharina; Enzmann, Frieder; Kersten, Michael; Rüde, Thomas R.; Wieber, Georg H. E.

2017-12-01

The present case study brings together different field- and laboratory methods and shows how the combination of different methods is able to lead to a plausible geological and hydrogeological conceptual model. The motivation for the study is a large groundwater-contamination site with volatile chlorinated hydrocarbons (CHC). The field work included core drilling, borehole geophysics, field mapping, remote sensing as well as pumping and packer tests. In the laboratory, thin section analyses, computed tomography, mercury porosimetry, compressed permeability measurements and triaxial cell tests were carried out. The Kreuznach- and Standenbühl-Formations can be identified as two types of aquifers by their hydrochemical composition. The hypothesis of continuous porous sandstone-layers in the Kreuznach-Formation as published in former articles (Fürst et al. 1987) was not confirmed. The primary strike of the joint system was identified as N-S and E-W with joint spacings of 3 to 8 m. The laboratory tests show an effective porosity of at most 4% and a high retention capacity for the sandstone of the Kreuznach-Formation. About 9% of the joints are water conduits. The results show that because of heterogeneities in the fractured aquifer, the efficiency of hydraulic remediation of groundwater contamination by pumping wells is unpredictable. Furthermore, the high matrix retention capacity has a negative impact on the release of contaminants and on groundwater remediation.

Fallbeispiel Kluftgrundwasserleiter - Charakterisierung eines Grundwasserleiters im Rotliegendsandstein des Saar-Nahe-Beckens

NASA Astrophysics Data System (ADS)

Altenbockum, Michael; Berens, Katharina; Enzmann, Frieder; Kersten, Michael; Rüde, Thomas R.; Wieber, Georg H. E.

2018-06-01

The present case study brings together different field- and laboratory methods and shows how the combination of different methods is able to lead to a plausible geological and hydrogeological conceptual model. The motivation for the study is a large groundwater-contamination site with volatile chlorinated hydrocarbons (CHC). The field work included core drilling, borehole geophysics, field mapping, remote sensing as well as pumping and packer tests. In the laboratory, thin section analyses, computed tomography, mercury porosimetry, compressed permeability measurements and triaxial cell tests were carried out. The Kreuznach- and Standenbühl-Formations can be identified as two types of aquifers by their hydrochemical composition. The hypothesis of continuous porous sandstone-layers in the Kreuznach-Formation as published in former articles (Fürst et al. 1987) was not confirmed. The primary strike of the joint system was identified as N-S and E-W with joint spacings of 3 to 8 m. The laboratory tests show an effective porosity of at most 4% and a high retention capacity for the sandstone of the Kreuznach-Formation. About 9% of the joints are water conduits. The results show that because of heterogeneities in the fractured aquifer, the efficiency of hydraulic remediation of groundwater contamination by pumping wells is unpredictable. Furthermore, the high matrix retention capacity has a negative impact on the release of contaminants and on groundwater remediation.

A Comparative Proteomic Analysis of the Simple Amino Acid Repeat Distributions in Plasmodia Reveals Lineage Specific Amino Acid Selection

PubMed Central

Dalby, Andrew R.

2009-01-01

Background Microsatellites have been used extensively in the field of comparative genomics. By studying microsatellites in coding regions we have a simple model of how genotypic changes undergo selection as they are directly expressed in the phenotype as altered proteins. The simplest of these tandem repeats in coding regions are the tri-nucleotide repeats which produce a repeat of a single amino acid when translated into proteins. Tri-nucleotide repeats are often disease associated, and are also known to be unstable to both expansion and contraction. This makes them sensitive markers for studying proteome evolution, in closely related species. Results The evolutionary history of the family of malarial causing parasites Plasmodia is complex because of the life-cycle of the organism, where it interacts with a number of different hosts and goes through a series of tissue specific stages. This study shows that the divergence between the primate and rodent malarial parasites has resulted in a lineage specific change in the simple amino acid repeat distribution that is correlated to A–T content. The paper also shows that this altered use of amino acids in SAARs is consistent with the repeat distributions being under selective pressure. Conclusions The study shows that simple amino acid repeat distributions can be used to group related species and to examine their phylogenetic relationships. This study also shows that an outgroup species with a similar A–T content can be distinguished based only on the amino acid usage in repeats, and suggest that this might be a useful feature for proteome clustering. The lineage specific use of amino acids in repeat regions suggests that comparative studies of SAAR distributions between proteomes gives an insight into the mechanisms of expansion and the selective pressures acting on the organism. PMID:19597555

Melting behavior of SnI4 reexamined

NASA Astrophysics Data System (ADS)

Fuchizaki, Kazuhiro

2013-12-01

The low-pressure crystalline phase of a molecular crystal, SnI4, has a rising melting curve that breaks abruptly at around 1.5 GPa, beyond which it becomes almost flat, with a slight maximum at about 3 GPa. Although the overall aspect of this melting curve can be captured by the Kumari-Dass-Kechin equation, the values for the parameters involved in the equation were definitely different from those predicted on the basis of the Clapeyron-Clausius relationship. On the other hand, the accuracy of our experimental data prevented us from judging whether the parameters are derivable from the Lindemann melting law, as shown independently by Kumari and Dass, and by Kechin. The Kraut-Kennedy and Magalinskii-Zubov relationships seem to be valid in the low-pressure region where the melting curve is rising. The breakdown of these relationships suggests a qualitative change in the intermolecular interaction upon compression, thereby making the melting behavior unusual.

Moral distress reexamined: a feminist interpretation of nurses' identities, relationships, and responsibilites.

PubMed

Peter, Elizabeth; Liaschenko, Joan

2013-10-01

Moral distress has been written about extensively in nursing and other fields. Often, however, it has not been used with much theoretical depth. This paper focuses on theorizing moral distress using feminist ethics, particularly the work of Margaret Urban Walker and Hilde Lindemann. Incorporating empirical findings, we argue that moral distress is the response to constraints experienced by nurses to their moral identities, responsibilities, and relationships. We recommend that health professionals get assistance in accounting for and communicating their values and responsibilities in situations of moral distress. We also discuss the importance of nurses creating "counterstories" of their work as knowledgeable and trustworthy professionals to repair their damaged moral identities, and, finally, we recommend that efforts toward shifting the goal of health care away from the prolongation of life at all costs to the relief of suffering to diminish the moral distress that is a common response to aggressive care at end-of-life.

Mermin-Wagner fluctuations in 2D amorphous solids.

PubMed

Illing, Bernd; Fritschi, Sebastian; Kaiser, Herbert; Klix, Christian L; Maret, Georg; Keim, Peter

2017-02-21

In a recent commentary, J. M. Kosterlitz described how D. Thouless and he got motivated to investigate melting and suprafluidity in two dimensions [Kosterlitz JM (2016) J Phys Condens Matter 28:481001]. It was due to the lack of broken translational symmetry in two dimensions-doubting the existence of 2D crystals-and the first computer simulations foretelling 2D crystals (at least in tiny systems). The lack of broken symmetries proposed by D. Mermin and H. Wagner is caused by long wavelength density fluctuations. Those fluctuations do not only have structural impact, but additionally a dynamical one: They cause the Lindemann criterion to fail in 2D in the sense that the mean squared displacement of atoms is not limited. Comparing experimental data from 3D and 2D amorphous solids with 2D crystals, we disentangle Mermin-Wagner fluctuations from glassy structural relaxations. Furthermore, we demonstrate with computer simulations the logarithmic increase of displacements with system size: Periodicity is not a requirement for Mermin-Wagner fluctuations, which conserve the homogeneity of space on long scales.

Mermin-Wagner fluctuations in 2D amorphous solids

NASA Astrophysics Data System (ADS)

Illing, Bernd; Fritschi, Sebastian; Kaiser, Herbert; Klix, Christian L.; Maret, Georg; Keim, Peter

2017-02-01

In a recent commentary, J. M. Kosterlitz described how D. Thouless and he got motivated to investigate melting and suprafluidity in two dimensions [Kosterlitz JM (2016) J Phys Condens Matter 28:481001]. It was due to the lack of broken translational symmetry in two dimensions—doubting the existence of 2D crystals—and the first computer simulations foretelling 2D crystals (at least in tiny systems). The lack of broken symmetries proposed by D. Mermin and H. Wagner is caused by long wavelength density fluctuations. Those fluctuations do not only have structural impact, but additionally a dynamical one: They cause the Lindemann criterion to fail in 2D in the sense that the mean squared displacement of atoms is not limited. Comparing experimental data from 3D and 2D amorphous solids with 2D crystals, we disentangle Mermin-Wagner fluctuations from glassy structural relaxations. Furthermore, we demonstrate with computer simulations the logarithmic increase of displacements with system size: Periodicity is not a requirement for Mermin-Wagner fluctuations, which conserve the homogeneity of space on long scales.

Dynamics and Melting of Finite Plasma Crystals

NASA Astrophysics Data System (ADS)

Ludwig, Patrick; K"Ahlert, Hanno; Baumgartner, Henning; Thomsen, Hauke; Bonitz, Michael

2009-11-01

Interacting few-particle systems in external trapping potentials are of strong current interest since they allow to realize and control strong correlation and quantum effects [1]. Here, we present our recent results on the structural and thermodynamic properties of the crystal-like Wigner phase of complex plasma confined in a 3D harmonic potential. We discuss the linear response of the strongly correlated system to external excitations, which can be described in terms of normal modes [2]. By means of first-principle simulations the details of the melting phase transitions of these mesoscopic systems are systematically analysed with the melting temperatures being determined by a modified Lindemann parameter for the pair distance fluctuations [3]. The critical temperatures turn out to be utmost sensitive to finite size effects (i.e., the exact particle number), and form of the (screened) interaction potential.[4pt] [1] PhD Thesis, P. Ludwig, U Rostock (2008)[0pt] [2] C. Henning et al., J. Phys. A 42, 214023 (2009)[0pt] [3] B"oning et al., Phys. Rev. Lett. 100, 113401 (2008)

Effect of grain size on the melting point of confined thin aluminum films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wejrzanowski, Tomasz; Lewandowska, Malgorzata; Sikorski, Krzysztof

2014-10-28

The melting of aluminum thin film was studied by a molecular dynamics (MD) simulation technique. The effect of the grain size and type of confinement was investigated for aluminum film with a constant thickness of 4 nm. The results show that coherent intercrystalline interface suppress the transition of solid aluminum into liquid, while free-surface gives melting point depression. The mechanism of melting of polycrystalline aluminum thin film was investigated. It was found that melting starts at grain boundaries and propagates to grain interiors. The melting point was calculated from the Lindemann index criterion, taking into account only atoms near to grainmore » boundaries. This made it possible to extend melting point calculations to bigger grains, which require a long time (in the MD scale) to be fully molten. The results show that 4 nm thick film of aluminum melts at a temperature lower than the melting point of bulk aluminum (933 K) only when the grain size is reduced to 6 nm.« less

Mermin–Wagner fluctuations in 2D amorphous solids

PubMed Central

Illing, Bernd; Fritschi, Sebastian; Kaiser, Herbert; Klix, Christian L.; Maret, Georg; Keim, Peter

2017-01-01

In a recent commentary, J. M. Kosterlitz described how D. Thouless and he got motivated to investigate melting and suprafluidity in two dimensions [Kosterlitz JM (2016) J Phys Condens Matter 28:481001]. It was due to the lack of broken translational symmetry in two dimensions—doubting the existence of 2D crystals—and the first computer simulations foretelling 2D crystals (at least in tiny systems). The lack of broken symmetries proposed by D. Mermin and H. Wagner is caused by long wavelength density fluctuations. Those fluctuations do not only have structural impact, but additionally a dynamical one: They cause the Lindemann criterion to fail in 2D in the sense that the mean squared displacement of atoms is not limited. Comparing experimental data from 3D and 2D amorphous solids with 2D crystals, we disentangle Mermin–Wagner fluctuations from glassy structural relaxations. Furthermore, we demonstrate with computer simulations the logarithmic increase of displacements with system size: Periodicity is not a requirement for Mermin–Wagner fluctuations, which conserve the homogeneity of space on long scales. PMID:28137872

New measurements of photospheric magnetic fields in late-type stars and emerging trends

NASA Technical Reports Server (NTRS)

Saar, S. H.; Linsky, J. L.

1986-01-01

The magnetic fields of late-type stars are measured using the method of Saar et al. (1986). The method includes radiative transfer effects and compensation for line blending; the photospheric magnetic field parameters are derived by comparing observed and theoretical line profiles using an LTE code that includes line saturation and full Zeeman pattern. The preliminary mean active region magnetic field strengths (B) and surface area coverages for 20 stars are discussed. It is observed that there is a trend of increasing B towards the cooler dwarfs stars, and the linear correlation between B and the equipartition value of the magnetic field strength suggests that the photospheric gas pressure determines the photospheric magnetic field strengths. A tendency toward larger filling factors at larger stellar angular velocities is also detected.

Dietrich Stauffer: Unconventional in Science and Life

NASA Astrophysics Data System (ADS)

Chowdhury, Debashish

Dietrich Stauffer (DS) was born in Bonn on 6th February, 1943. He was awarded the Ph.D. degree in Physics by the Technical University of Munich in 1970 for his thesis on phase transitions and superfluidity of helium. After doing postdoctoral research in USA over the next few years, on phase transitions [1], droplet model and nucleation [2], he returned to Germany to join Kurt Binder's group at the Saar State University, Saarbrücken. During this period the classic works of Binder and Stauffer on the cluster theory of nucleation were published [3]. He completed his “Habilitation” (required as eligibility for tenured professor positions in Germany) in Saarbrücken in 1975. Then, in 1977, he joined the faculty of the University of Cologne as an associate professor in the Institute of Theoretical Physics where he has remained ever since.

P651: Battlefield Analysis. The Saar River Crossing, 94th Infantry Division, February 1945

DTIC Science & Technology

1984-01-01

MAJOR THOMAS ELLIS MAJOR STANLEY EVANS MAJOR CHARLES JURGENSEN MAJOR (P) WILLIAM LARSON MAJOR BOBBY LUMHO MAJOR ROBERT MANNINO MAJOR MICHAEL...MAPLES MAJOR PHILLIP RAYMOND MAJOR <P> BURT VANDERCLUTE MAJOR THOMAS WILSON CAPTAIN ROBERT MILLER CAPTAIN MAMA TRAORE (MALI) FORT LEAVENWORTH...to Major Paul W. Marshall, of the 319th Engineers, who, in turn, received assistance from Major John N. Smith, Captain Thomas J. Mclntyre

Mirror of light

NASA Astrophysics Data System (ADS)

Ohlmann, Dietmar

2000-10-01

The making of holograms is better understood than their uses. As an artist who studied holography in Liverpool and at the Royal College of Art in London in the fine art section, I like to use this media in a quite unusual way avoiding the well-worn cliches of Laser-Light-Kitchen- Object-Table-Top-Photography and all these horrible, greenish, blinking plastics. After seeing a master and being introduced to its potential and being inspired by artists such as Rod Murray, Rick Silverman, Margaret Benyon, and Peter Miller I used to spend more time in the Laser- Laboratory than in my painting studio. However, this is no longer true. I have been working on the Millennium-Project since 1996. The project is the idea of Werner Lindemann who is creating a gigantic Amphitheater. On this site, I have the opportunity to meet all sorts of artists and craftsmen, such as opera singers, ceramics designers and architects, to whom I introduced several different large scale projects. Forced to work out installations of a minimum 20 square meters in dimension, I have developed what I call the None- Hologram.

Regional convergence platforms in Europe—Innovation for space through technology partnerships

NASA Astrophysics Data System (ADS)

Bütfering, Peter

2010-05-01

Upcoming European and national space exploration programs and projects require new capabilities and scientific-technological solutions, and therefore external contributions to innovation. On the other hand European core (industrial) regions are searching of partners for innovation to strengthen their regional economy. In this context the German-based company European Space Innovation AG (former Adam Alva Neil)—highly experienced in the area of convergence activities between space and other sectors—has developed the model of regional convergence platforms (named 'SpaceInnovation'). These platforms are designed to foster technology partnerships between regional companies and institutes from 'non-space' and the space sector (agencies/industry). The article reflects this regional approach and shows examples in three different directions: SpaceInnovation Saar, an benchmark convergence platform initiated by the Saarland region. SpaceInnovation Europe, an European regions network approach. European SpaceInnovation Agent, an interface approach for systematic and sustainable convergence activities.

Paradoxes of maternal mourning.

PubMed

Brice, C W

1991-02-01

It has been customary to conceptualize mourning as a phasic or stage phenomenon (Lindemann 1944; Parkes 1972; Bowlby 1980; Knapp 1986). Such a conceptualization has proved to be of tremendous didactic value, especially in terms of succinctly organizing and communicating the major affects, behaviors, and reactions of mourning. It is, however, my belief, based upon clinical experience with many forms of bereavement, that the phenomenon of mourning is not comprised of clearly delineated stages and phases. I have come to conceptualize the phenomenon of mourning the death of a loved person as involving the bereaved's struggle with a series of more or less unresolvable paradoxes rather than as a progression through stages that possess relatively distinct and predictable beginning and ending points. The specific paradoxes encountered by a bereaved person differ, of course, in accordance with the relationship that was lost (mother, father, spouse, child, or sibling), the developmental stage of the bereaved (childhood, adolescence, adulthood, or maturity), the type of death (sudden or prolonged), and the cause of death (illness, murder, suicide, or accident). In this paper, I will address those paradoxes that seem specific to maternal mourning - that is, to mothers who are mourning the death of a child.

Holding Ashley (X): Bestowing Identity Through Caregiving in Profound Intellectual Disability.

PubMed

Freitag, Lisa; Liaschenko, Joan

2017-01-01

The controversy over the so-called Ashley Treatment (AT), a series of medical procedures that inhibited both growth and sexual development in the body of a profoundly intellectually impaired girl, usually centers either on Ashley's rights, including a right to an intact, unaltered body, or on Ashley's parents' rights to make decisions for her. The claim made by her parents, that the procedure would improve their ability to care for her, is often dismissed as inappropriate or, at best, irrelevant. We argue, however, that caregiving is a central issue in the controversy, as Ashley's need for caregiving is a defining characteristic of her life. In this article, we analyze the ethics of the Ashley Treatment within the context of family caregiving. Through the physical and emotional work of caregiving, families participate in the formation and maintenance of personal identity, a process that Hilde Lindemann recently called "holding." We argue that, in an intellectually disabled person such as Ashley, who depends on her family for every aspect of her care, the family's contribution to identity is an essential source of personhood. We believe that the treatment can be justified if it is indeed an instance of appropriate family "holding" for Ashley. Copyright 2017 The Journal of Clinical Ethics. All rights reserved.

The concept of a hierarchical cosmos

NASA Astrophysics Data System (ADS)

Grujić, P. V.

2003-10-01

The idea of a hierachically structured cosmos can be traced back to the Presocratic Hellada. In the fifth century BC Anaxagoras from Clazomenae developed an idea of a sort of fractal material world, by introducing the concept of seeds (spermata), or homoeomeries as Aristotle dubbed it later (Grujić 2001). Anaxagoras ideas have been grossly neglected during the Middle Ages, to be invoked by a number of post-Renaissance thinkers, like Leibniz, Kant, etc, though neither of them referred to their Greek predecessor. But the real resurrections of the hierarchical paradigm started at the beginning of the last century, with Fournier and Charlier (Grujić 2002). Second half of the 20th century witnessed an intensive development of the theoretical models based on the (multi)fractal paradigm, as well as a considerable body of the observational evidence in favour of the hierarchical cosmos (Saar 1988). We overview the state of the art of the cosmological fractal concept, both within the astrophysical (Sylos Labini et al 1998), methodological (Ribeiro 2001) and epistemological (Ribeiro and Videira 1998) context.

The melting mechanism in binary Pd0.25Ni0.75 nanoparticles: molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Domekeli, U.; Sengul, S.; Celtek, M.; Canan, C.

2018-02-01

The melting mechanism for Pd0.25Ni0.75 alloy nanoparticles (NPs) was investigated using molecular dynamics (MD) simulations with quantum Sutton-Chen many-body potentials. NPs of six different sizes ranging from 682 to 22,242 atoms were studied to observe the effect of size on the melting point. The melting temperatures of the NPs were estimated by following the changes in both the thermodynamic and structural quantities such as the total energy, heat capacity and Lindemann index. We also used a thermodynamics model to better estimate the melting point and to check the accuracy of MD simulations. We observed that the melting points of the NPs decreased as their sizes decreased. Although the MD simulations for the bulk system yielded higher melting temperatures because of the lack of a seed for the liquid phase, the melting temperatures determined for both the bulk material and the NPs are in good agreement with those predicted from the thermodynamics model. The melting mechanism proceeds in two steps: firstly, a liquid-like shell is formed in the outer regions of the NP with increasing temperature. The thickness of the liquid-like shell increases with increasing temperature until the shell reaches a critical thickness. Then, the entire Pd-Ni NP including core-related solid-like regions melts at once.

On a possible melting curve of C60 fullerite

NASA Astrophysics Data System (ADS)

Zubov, V. I.; Rodrigues, C. G.; Zubov, I. V.

2003-07-01

We study the thermodynamic properties of the high-temperature modification of fullerites on the basis of the Girifalco intermolecular potential. In the present work, using Lindemann's melting criterion, we estimate a possible melting curve Tm(P) of C60 fullerite. To take into account the lattice anharmonicity, which has a strong effect at T > 700 K, we use the correlative method of unsymmetrized self-consistent field. To check this approach, first we have applied it to solid Ar. In the range between its triple point Tt = 83.807 K and 260 K we obtained the mean square relative deviation from experimental data of about 0.7%. The melting curve for C60 fullerite has been calculated from the melting point at normal pressure estimated at 1500 K up to 15 kbar, which corresponds to Tm = 4000 K, i.e. to the temperature estimated by Kim and Tománek [Phys. Rev. Lett. 72, 2418 (1994)] as that of the decomposition of the C60 molecule itself. The temperature dependence of the melting pressure is approximated very well by the Simon equation (Pm(T)/bar - 1)/b = (T/T0)c with T0 = 1500 K, b = 6643.8, and c = 1.209. The temperature dependence of the molar volume along the melting curve is described by Vs(T) = Vs(T0) - 29.20 ln (T/T0.

First-principles modeling of quantum nuclear effects and atomic interactions in solid 4He at high pressure

NASA Astrophysics Data System (ADS)

Cazorla, Claudio; Boronat, Jordi

2015-01-01

We present a first-principles computational study of solid 4He at T =0 K and pressures up to ˜160 GPa. Our computational strategy consists in using van der Waals density functional theory (DFT-vdW) to describe the electronic degrees of freedom in this material, and the diffusion Monte Carlo (DMC) method to solve the Schrödinger equation describing the behavior of the quantum nuclei. For this, we construct an analytical interaction function based on the pairwise Aziz potential that closely matches the volume variation of the cohesive energy calculated with DFT-vdW in dense helium. Interestingly, we find that the kinetic energy of solid 4He does not increase appreciably with compression for P ≥85 GPa. Also, we show that the Lindemann ratio in dense solid 4He amounts to 0.10 almost independently of pressure. The reliability of customary quasiharmonic DFT (QH DFT) approaches in describing quantum nuclear effects in solids is also studied. We find that QH DFT simulations, although provide a reasonable equation of state in agreement with experiments, are not able to reproduce correctly these critical effects in compressed 4He. In particular, we disclose huge discrepancies of at least ˜50 % in the calculated 4He kinetic energies using both the QH DFT and present DFT-DMC methods.

Do homologous thermophilic-mesophilic proteins exhibit similar structures and dynamics at optimal growth temperatures? A molecular dynamics simulation study.

PubMed

Basu, Sohini; Sen, Srikanta

2013-02-25

Structure and dynamics both are known to be important for the activity of a protein. A fundamental question is whether a thermophilic protein and its mesophilic homologue exhibit similar dynamics at their respective optimal growth temperatures. We have addressed this question by performing molecular dynamics (MD) simulations of a natural mesophilic-thermophilic homologue pair at their respective optimal growth temperatures to compare their structural, dynamical, and solvent properties. The MD simulations were done in explicit aqueous solvent under periodic boundary and constant pressure and temperature (CPT) conditions and continued for 10.0 ns using the same protocol for the two proteins, excepting the temperatures. The trajectories were analyzed to compare the properties of the two proteins. Results indicated that the dynamical behaviors of the two proteins at the respective optimal growth temperatures were remarkably similar. For the common residues in the thermophilic protein, the rms fluctuations have a general trend to be slightly higher compared to that in the mesophilic counterpart. Lindemann parameter values indicated that only a few residues exhibited solid-like dynamics while the protein as a whole appeared as a molten globule in each case. Interestingly, the water-water interaction was found to be strikingly similar in spite of the difference in temperatures while, the protein-water interaction was significantly different in the two simulations.

A Long-Lived Oscillatory Space-Time Correlation Function of Two Dimensional Colloids

NASA Astrophysics Data System (ADS)

Kim, Jeongmin; Sung, Bong June

2014-03-01

Diffusion of a colloid in solution has drawn significant attention for a century. A well-known behavior of the colloid is called Brownian motion : the particle displacement probability distribution (PDPD) is Gaussian and the mean-square displacement (MSD) is linear with time. However, recent simulation and experimental studies revealed the heterogeneous dynamics of colloids near glass transitions or in complex environments such as entangled actin, PDPD exhibited the exponential tail at a large length instead of being Gaussian at all length scales. More interestingly, PDPD is still exponential even when MSD was still linear with time. It requires a refreshing insight on the colloidal diffusion in the complex environments. In this work, we study heterogeneous dynamics of two dimensional (2D) colloids using molecular dynamics simulations. Unlike in three dimensions, 2D solids do not follow the Lindemann melting criterion. The Kosterlitz-Thouless-Halperin-Nelson-Young theory predicts two-step phase transitions with an intermediate phase, the hexatic phase between isotropic liquids and solids. Near solid-hexatic transition, PDPD shows interesting oscillatory behavior between a central Gaussian part and an exponential tail. Until 12 times longer than translational relaxation time, the oscillatory behavior still persists even after entering the Fickian regime. We also show that multi-layered kinetic clusters account for heterogeneous dynamics of 2D colloids with the long-lived anomalous oscillatory PDPD.

Home-based care, technology, and the maintenance of selves.

PubMed

Parks, Jennifer A

2015-06-01

In this paper, I will argue that there is a deep connection between home-based care, technology, and the self. Providing the means for persons (especially older persons) to receive care at home is not merely a kindness that respects their preference to be at home: it is an important means of extending their selfhood and respecting the unique selves that they are. Home-based technologies like telemedicine and robotic care may certainly be useful tools in providing care for persons at home, but they also have important implications for sustaining selfhood in ways that are of value to individuals and those who care for them. I will argue, by appealing to Hilde Lindemann's notion of "holding" persons' identities in place, that technological interventions are not only useful tools for improving and sustaining health and good care at home, but that they may also help to extend our personal identities and relational capacities in ways that are practically and ethically good. Because of these important goods, I will claim that there is a prima facie moral duty to do this "holding" work and that it is best done by family members and loved ones who are well suited to the job because of their history and relationship with the individual that needs to be "held" in place.

Folding thermodynamics of model four-strand antiparallel beta-sheet proteins.

PubMed Central

Jang, Hyunbum; Hall, Carol K; Zhou, Yaoqi

2002-01-01

The thermodynamic properties for three different types of off-lattice four-strand antiparallel beta-strand protein models interacting via a hybrid Go-type potential have been investigated. Discontinuous molecular dynamic simulations have been performed for different sizes of the bias gap g, an artificial measure of a model protein's preference for its native state. The thermodynamic transition temperatures are obtained by calculating the squared radius of gyration R(g)(2), the root-mean-squared pair separation fluctuation Delta(B), the specific heat C(v), the internal energy of the system E, and the Lindemann disorder parameter Delta(L). Despite these models' simplicity, they exhibit a complex set of protein transitions, consistent with those observed in experimental studies on real proteins. Starting from high temperature, these transitions include a collapse transition, a disordered-to-ordered globule transition, a folding transition, and a liquid-to-solid transition. The high temperature transitions, i.e., the collapse transition and the disordered-to-ordered globule transition, exist for all three beta-strand proteins, although the native-state geometry of the three model proteins is different. However the low temperature transitions, i.e., the folding transition and the liquid-to-solid transition, strongly depend on the native-state geometry of the model proteins and the size of the bias gap. PMID:11806908

Molecular dynamical simulations of melting Al nanoparticles using a reaxff reactive force field

NASA Astrophysics Data System (ADS)

Liu, Junpeng; Wang, Mengjun; Liu, Pingan

2018-06-01

Molecular dynamics simulations were performed to study thermal properties and melting points of Al nanoparticles by using a reactive force field under canonical (NVT) ensembles. Al nanoparticles (particle size 2–4 nm) were considered in simulations. A combination of structural and thermodynamic parameters such as the Lindemann index, heat capacities, potential energy and radial-distribution functions was employed to decide melting points. We used annealing technique to obtain the initial Al nanoparticle model. Comparison was made between ReaxFF results and other simulation results. We found that ReaxFF force field is reasonable to describe Al cluster melting behavior. The linear relationship between particle size and melting points was found. After validating the ReaxFF force field, more attention was paid on thermal properties of Al nanoparticles with different defect concentrations. 4 nm Al nanoparticles with different defect concentrations (5%–20%) were considered in this paper. Our results revealed that: the melting points are irrelevant with defect concentration at a certain particle size. The extra storage energy of Al nanoparticles is proportional to nanoparticles’ defect concentration, when defect concentration is 5%–15%. While the particle with 20% defect concentration is similar to the cluster with 10% defect concentration. After melting, the extra energy of all nanoparticles decreases sharply, and the extra storage energy is nearly zero at 600 K. The centro-symmetry parameter analysis shows structure evolution of different models during melting processes.

Why do ultrasoft repulsive particles cluster and crystallize? Analytical results from density-functional theory.

PubMed

Likos, Christos N; Mladek, Bianca M; Gottwald, Dieter; Kahl, Gerhard

2007-06-14

We demonstrate the accuracy of the hypernetted chain closure and of the mean-field approximation for the calculation of the fluid-state properties of systems interacting by means of bounded and positive pair potentials with oscillating Fourier transforms. Subsequently, we prove the validity of a bilinear, random-phase density functional for arbitrary inhomogeneous phases of the same systems. On the basis of this functional, we calculate analytically the freezing parameters of the latter. We demonstrate explicitly that the stable crystals feature a lattice constant that is independent of density and whose value is dictated by the position of the negative minimum of the Fourier transform of the pair potential. This property is equivalent with the existence of clusters, whose population scales proportionally to the density. We establish that regardless of the form of the interaction potential and of the location on the freezing line, all cluster crystals have a universal Lindemann ratio Lf=0.189 at freezing. We further make an explicit link between the aforementioned density functional and the harmonic theory of crystals. This allows us to establish an equivalence between the emergence of clusters and the existence of negative Fourier components of the interaction potential. Finally, we make a connection between the class of models at hand and the system of infinite-dimensional hard spheres, when the limits of interaction steepness and space dimension are both taken to infinity in a particularly described fashion.

Significance of DNA bond strength in programmable nanoparticle thermodynamics and dynamics.

PubMed

Yu, Qiuyan; Hu, Jinglei; Hu, Yi; Wang, Rong

2018-04-04

Assembly of nanoparticles (NPs) coated with complementary DNA strands leads to novel crystals with nanosized basic units rather than classic atoms, ions or molecules. The assembly process is mediated by hybridization of DNA via specific base pairing interaction, and is kinetically linked to the disassociation of DNA duplexes. DNA-level physiochemical quantities, both thermodynamic and kinetic, are key to understanding this process and essential for the design of DNA-NP crystals. The melting transition properties are helpful to judge the thermostability and sensitivity of relative DNA probes or other applications. Three different cases are investigated by changing the linker length and the spacer length on which the melting properties depend using the molecular dynamics method. Melting temperature is determined by sigmoidal melting curves based on hybridization percentage versus temperature and the Lindemann melting rule simultaneously. We provide a computational strategy based on a coarse-grained model to estimate the hybridization enthalpy, entropy and free energy from percentages of hybridizations which are readily accessible in experiments. Importantly, the lifetime of DNA bond dehybridization based on temperature and the activation energy depending on DNA bond strength are also calculated. The simulation results are in good agreement with the theoretical analysis and the present experimental data. Our study provides a good strategy to predict the melting temperature which is important for the DNA-directed nanoparticle system, and bridges the dynamics and thermodynamics of DNA-directed nanoparticle systems by estimating the equilibrium constant from the hybridization of DNA bonds quantitatively.

Physics in Oxford, 1839-1939 - Laboratories, Learning, and College Life

NASA Astrophysics Data System (ADS)

Fox, Robert; Gooday, Graeme

2005-08-01

Physics in Oxford 1839-1939 offers a challenging new interpretation of pre-war physics at the University of Oxford, which was far more dynamic than most historians and physicists have been prepared to believe. It explains, on the one hand, how attempts to develop the University's Clarendon Laboratory by Robert Clifton, Professor of Experimental Philosophy from 1865 to 1915, were thwarted by academic politics and funding problems, and latterly by Clifton's idiosyncratic concern with precision instrumentation. Conversely, by examining in detail the work of college fellows and their laboratories, the book reconstructs the decentralized environment that allowed physics to enter on a period of conspicuous vigor in the late nineteenth and early twentieth centuries, especially at the characteristically Oxonian intersections between physics, physical chemistry, mechanics, and mathematics. Whereas histories of Cambridge physics have tended to focus on the self-sustaining culture of the Cavendish Laboratory, it was Oxford's college-trained physicists who enabled the discipline to flourish in due course in university as well as college facilities, notably under the newly appointed professors, J. S. E. Townsend from 1900 and F. A. Lindemann from 1919. This broader perspective allows us to understand better the vitality with which physicists in Oxford responded to the demands of wartime research on radar and techniques relevant to atomic weapons and laid the foundations for the dramatic post-war expansion in teaching and research that has endowed Oxford with one of the largest and most dynamic schools of physics in the world.

Fostering Nurses' Moral Agency and Moral Identity: The Importance of Moral Community.

PubMed

Liaschenko, Joan; Peter, Elizabeth

2016-09-01

It may be the case that the most challenging moral problem of the twenty-first century will be the relationship between the individual moral agent and the practices and institutions in which the moral agent is embedded. In this paper, we continue the efforts that one of us, Joan Liaschenko, first called for in 1993, that of using feminist ethics as a lens for viewing the relationship between individual nurses as moral agents and the highly complex institutions in which they do the work of nursing. Feminist ethics, with its emphasis on the inextricable relationship between ethics and politics, provides a useful lens to understand the work of nurses in context. Using Margaret Urban Walker's and Hilde Lindemann's concepts of identity, relationships, values, and moral agency, we argue that health care institutions can be moral communities and profoundly affect the work and identity and, therefore, the moral agency of all who work within those structures, including nurses. Nurses are not only shaped by these organizations but also have the power to shape them. Because moral agency is intimately connected to one's identity, moral identity work is essential for nurses to exercise their moral agency and to foster moral community in health care organizations. We first provide a brief history of nursing's morally problematic relationship with institutions and examine the impact institutional master narratives and corporatism exert today on nurses' moral identities and agency. We close by emphasizing the significance of ongoing dialogue in creating and sustaining moral communities, repairing moral identities, and strengthening moral agency. © 2016 The Hastings Center.

[First experience in the thyroid and parathyroid surgery using the da Vinci® system].

PubMed

Al Kadah, B; Siemer, S; Schick, B

2014-01-01

Endoscopic surgery for the treatment of thyroid and parathyroid pathologies is gaining increasing attention. The da Vinci® system has been already widely used in different fields of medicine including recently thyroid and parathyroid surgery. Herein we report our first experiences in endoscopic surgery of thyroid and parathyroid pathologies using the da Vinci® system. 8 patients presenting with struma nodosa in 6 cases and parathyroid adenomas in 2 cases have been treated using the da Vinci® system at the ENT department of Homburg/Saar University. The skin incision to introduce the instruments with the da Vinci® system were axilar or at the lateral segment of the clavicle. The neurovascular structures like inferior laryngeal nerve as well as the pathologies were clearly 3-dimensional visualized in all 8 cases. No paralysis of the vocal cord was observed. All patients had in histological examination a benign pathology. The endoscopic surgery of the thyroid and parathyroid gland can be performed using the da Vinci® system and offers an excellent, intraoperative, 3-dimensional visualization of the neurovascular structures. Additionally the da Vinci® system enables skin incisions within considerable distance from the thyroid and parathyroid gland. © Georg Thieme Verlag KG Stuttgart · New York.

Quantitative comparison of initial soil erosion processes and runoff generation in Spanish and German vineyards.

PubMed

Rodrigo Comino, J; Iserloh, T; Lassu, T; Cerdà, A; Keestra, S D; Prosdocimi, M; Brings, C; Marzen, M; Ramos, M C; Senciales, J M; Ruiz Sinoga, J D; Seeger, M; Ries, J B

2016-09-15

The aim of this study was to enable a quantitative comparison of initial soil erosion processes in European vineyards using the same methodology and equipment. The study was conducted in four viticultural areas with different characteristics (Valencia and Málaga in Spain, Ruwer-Mosel valley and Saar-Mosel valley in Germany). Old and young vineyards, with conventional and ecological planting and management systems were compared. The same portable rainfall simulator with identical rainfall intensity (40mmh(-1)) and sampling intervals (30min of test duration, collecting the samples at 5-min-intervals) was used over a circular test plot with 0.28m(2). The results of 83 simulations have been analysed and correlation coefficients were calculated for each study area to identify the relationship between environmental plot characteristics, soil texture, soil erosion, runoff and infiltration. The results allow for identification of the main factors related to soil properties, topography and management, which control soil erosion processes in vineyards. The most important factors influencing soil erosion and runoff were the vegetation cover for the ecological German vineyards (with 97.6±8% infiltration coefficients) and stone cover, soil moisture and slope steepness for the conventional land uses. Copyright © 2016 Elsevier B.V. All rights reserved.

Generalized spheroidal wave equation and limiting cases

NASA Astrophysics Data System (ADS)

Figueiredo, B. D. Bonorino

2007-01-01

We find sets of solutions to the generalized spheroidal wave equation (GSWE) or, equivalently, to the confluent Heun equation. Each set is constituted by three solutions, one given by a series of ascending powers of the independent variable, and the others by series of regular and irregular confluent hypergeometric functions. For a fixed set, the solutions converge over different regions of the complex plane but present series coefficients proportional to each other. These solutions for the GSWE afford solutions to a double-confluent Heun equation by a taking-limit process due to Leaver. [E. W. Leaver, J. Math. Phys. 27, 1238 (1986)]. Another procedure, called Whittaker-Ince limit [B. D. Figueiredo, J. Math. Phys. 46, 113503 (2005)], provides solutions in series of powers and Bessel functions for two other equations with a different type of singularity at infinity. In addition, new solutions are obtained for the Whittaker-Hill and Mathieu equations [F. M. Arscott, Proc. R. Soc. Edinburg A67, 265 (1967)] by considering these as special cases of both the confluent and double-confluent Heun equations. In particular, we find that each of the Lindemann-Stieltjes solutions for the Mathieu equation [E. T. Whittaker and G. N. Watson, A Course of Modern Analysis, Cambridge University Press (1945)] is associated with two expansions in series of Bessel functions. We also discuss a set of solutions in series of hypergeometric and confluent hypergeometric functions for the GSWE and use their Leaver limits to obtain infinite-series solutions for the Schrödinger equation with an asymmetric double-Morse potential. Finally, the possibility of extending the solutions of the GSWE to the general Heun equation is briefly discussed.

Removing Activity-Related Radial Velocity Noise to Improve Extrasolar Planet Searches

NASA Technical Reports Server (NTRS)

Saar, Steven; Lindstrom, David M. (Technical Monitor)

2004-01-01

We have made significant progress towards the proposal goals of understanding the causes and effects of magnetic activity-induced radial velocity (v_r) jitter and developing methods for correcting it. In the process, we have also made some significant discoveries in the fields of planet-induced stellar activity, planet detection methods, M dwarf convection, starspot properties, and magnetic dynamo cycles. We have obtained super high resolution (R approximately 200,000), high S / N (greater than 300) echelle study of joint line bisector and radial velocity variations using the McDonald 2-D coude. A long observing run in October 2002 in particular was quite successful (8 clear nights). We now have close to three years of data, which begins to sample a good fraction of the magnetic cycle timescales for some of our targets (e.g., kappa Ceti; P_cyc = 5.6 yrs). This will be very helpful in unraveling the complex relationships between plage and radial velocity (v-r) changes which we have uncovered. Preliminary analysis (Saar et al. 2003) of the data in hand, reveals correlations between median line bisector displacement and v_r. The correlation appears to be specific the the particular star being considered, probably since it is a function of both spectral type and rotation rate. Further analysis and interpretation will be in the context of evolving plage models and is in progress.

Effect of ship locking on sediment oxygen uptake in impounded rivers

NASA Astrophysics Data System (ADS)

Lorke, A.; McGinnis, D. F.; Maeck, A.; Fischer, H.

2012-12-01

In the majority of large river systems, flow is regulated and/or otherwise affected by operational and management activities, such as ship locking. The effect of lock operation on sediment-water oxygen fluxes was studied within a 12.9 km long impoundment at the Saar River (Germany) using eddy-correlation flux measurements. The continuous observations cover a time period of nearly 5 days and 39 individual locking events. Ship locking is associated with the generation of surges propagating back and forth through the impoundment which causes strong variations of near-bed current velocity and turbulence. These wave-induced flow variations cause variations in sediment-water oxygen fluxes. While the mean flux during time periods without lock operation was 0.5 ± 0.1 g m-2 d-1, it increased by about a factor of 2 to 1.0 ± 0.5 g m-2 d-1within time periods with ship locking. Following the daily schedule of lock operations, fluxes are predominantly enhanced during daytime and follow a pronounced diurnal rhythm. The driving force for the increased flux is the enhancement of diffusive transport across the sediment-water interface by bottom-boundary layer turbulence and perhaps resuspension. Additional means by which the oxygen budget of the impoundment is affected by lock-induced flow variations are discussed.

Seasonal variability in Tibetan seismicity 1991-2013

NASA Astrophysics Data System (ADS)

Randolph-Flagg, N. G.; Day, J.; Burgmann, R.; Manga, M.

2013-12-01

Seismicity in the High Himalaya in Nepal (Bollinger et al., GRL, 2007, Bettinelli et al., EPSL, 2008), the San Andreas fault near Parkfield, California (Christiansen et al., 2007), Mt. Hochstaufen in Germany (Hainzl et al., 2006), and some Cascade Range volcanoes (Christiansen et al., GRL, 2005; Saar and Manga, EPSL, 2003) shows seasonal modulation. From 1991 to 2013, seismicity throughout the ~500 km by ~1000 km Tibetan Plateau also appears to be modulated with 66% more shallow (depth < 20km) earthquakes in spring and fall than in the summer and winter. This variation cannot be explained by seasonal changes in seismic network coverage or triggering by (or occurrence of) large magnitude earthquakes. Significant foreshocks and aftershocks of the 2008 M7.9 Wenchuan earthquake in Sichuan dominate the seismic record from 2008 to 2009 and those years are not considered in the statistical analysis. The Tibetan seismicity, although weaker, is very similar to the modulation observed in Nepal and in the locked section of the San Andreas fault at Parkfield. To explain this biannual signal, we assess the possible effects of hydrologic loading (and unloading), pore pressure diffusion, fault plane orientation, evapotranspiration, earth tides, and atmospheric pressure. The similarity in seasonal signals throughout the area suggests that many faults on the Tibetan Plateau are critically stressed and sensitive to small transient stresses.

String-like collective atomic motion in the melting and freezing of nanoparticles.

PubMed

Zhang, Hao; Kalvapalle, Pranav; Douglas, Jack F

2011-12-08

The melting of a solid represents a transition between a solid state in which atoms are localized about fixed average crystal lattice positions to a fluid state that is characterized by relative atomic disorder and particle mobility so that the atoms wander around the material as a whole, impelled by the random thermal impulses of surrounding atoms. Despite the fundamental nature and practical importance of this particle delocalization transition, there is still no fundamental theory of melting and instead one often relies on the semi-phenomenological Lindemann-Gilvarry criterion to estimate roughly the melting point as an instability of the crystal lattice. Even the earliest simulations of melting in hexagonally packed hard discs by Alder and Wainwright indicated the active role of nonlocal collective atomic motions in the melting process, and here we utilize molecular dynamics (MD) simulation to determine whether the collective particle motion observed in melting has a similar geometrical form as those in recent studies of nanoparticle (NP) interfacial dynamics and the molecular dynamics of metastable glass-forming liquids. We indeed find string-like collective atomic motion in NP melting that is remarkably similar in form to the collective interfacial motions in NPs at equilibrium and to the collective motions found in the molecular dynamics of glass-forming liquids. We also find that the spatial localization and extent of string-like motion in the course of NP melting and freezing evolves with time in distinct ways. Specifically, the collective atomic motion propagates from the NP surface and from within the NP in melting and freezing, respectively, and the average string length varies smoothly with time during melting. In contrast, the string-like cooperative motion peaks in an intermediate stage of the freezing process, reflecting a general asymmetry in the dynamics of NP superheating and supercooling. © 2011 American Chemical Society

Nurses' narratives of moral identity: Making a difference and reciprocal holding.

PubMed

Peter, Elizabeth; Simmonds, Anne; Liaschenko, Joan

2018-05-01

Explicating nurses' moral identities is important given the powerful influence moral identity has on the capacity to exercise moral agency. The purpose of this study was to explore how nurses narrate their moral identity through their understanding of their work. An additional purpose was to understand how these moral identities are held in the social space that nurses occupy. The Registered Nurse Journal, a bimonthly publication of the Registered Nurses' Association of Ontario, Canada, features a regular column entitled, 'In the End … What Nursing Means to Me …' These short narratives generally include a story of an important moment in the careers of the authors that defined their identities as nurses. All 29 narratives published before June 2015 were analysed using a critical narrative approach, informed by the work of Margaret Urban Walker and Hilde Lindemann, to identify a typology of moral identity. Ethical considerations: Ethics approval was not required because the narratives are publicly available. Two narrative types were identified that represent the moral identities of nurses as expressed through their work: (1) making a difference in the lives of individuals and communities and (2) holding the identities of vulnerable individuals. Nurses' moral identities became evident when they could see improvement in the health of patients or communities or when they could maintain the identity of their patients despite the disruptive forces of illness and hospitalization. In reciprocal fashion, the responses of their patients, including expressions of gratitude, served to hold the moral identities of these nurses. Ultimately, the sustainability of nurses' moral identities may be dependent on the recognition of their own needs for professional satisfaction and care in ways that go beyond the kind of acknowledgement that patients can offer.

Measurement of the force and torque produced in the calcium response of reactivated rat sperm flagella.

PubMed

Moritz, M J; Schmitz, K A; Lindemann, C B

2001-05-01

Rat sperm that are demembranated with Triton X-100 and reactivated with Mg-ATP show a strong mechanical response to the presence of free calcium ion. At pCa < 4, the midpiece region of the flagellum develops a strong and sustained curvature that gives the cell the overall appearance of a fishhook [Lindemann and Goltz, 1988: Cell Motil. Cytoskeleton 10:420-431]. In the present study, the force and torque that maintain the calcium-induced hook have been examined quantitatively. In addition, full-length and shortened flagella were manipulated to evaluate the plasticity of the hooks and determined the critical length necessary for maintaining the curvature. The hooks were found to be highly resilient, returning to their original configuration (>95%) after being straightened and released. The results from manipulating the shortened flagella suggest that the force holding the hook in the curved configuration is generated in the basal 60 microm of the flagellum. The force required to straighten the calcium-induced hooks was measured with force-calibrated glass microprobes, and the bending torque was calculated from the measured force. The force and torque required to straighten the flagellum were found to be proportional to the change in curvature of the hooked region of the flagellum, suggesting an elastic-like behavior. The average torque to open the hooks to a straight position was 2.6 (+/-1.4) x 10(-7) dyne x cm (2.6 x 10(-14) N x m) and the apparent stiffness was 4.3 (+/-1.3) x 10(-10) dyne x cm(2) (4.3 x 10(-19) N x m(2)). The stiffness of the hook was determined to be approximately one quarter the rigor stiffness of a rat sperm flagellum measured under comparable conditions.

Adhesion at Entangled Polymer Interfaces: A Unified Approach..

NASA Astrophysics Data System (ADS)

Wool, Richard

2006-03-01

A unified theory of fracture of polymer interfaces was developed which was based on the Rigidity Percolation model of fracture [R.P. Wool, J.Polym.Sci. Part A: Polym Phys., 43,168(2005)]. The polymer fractured critically when the normalized entanglement density p, approached the percolation threshold pc. The fracture energy was found to be G1c ˜ [p-pc]. When applied to interfaces of width X, containing an areal density σ of chains, each contributing L chain entanglements, the percolation term p ˜ σL/X and the percolation threshold was related to σc, Lc, or Xc. For welding of A/A symmetric interfaces, p = σL/X, and pc Lc/M 0, such that when σ/X ˜1/M for randomly distributed chain ends, p˜L ˜ (t/M)^1/2, G/G* = (t/τ*)^1/2, where the weld time τ* ˜ M. When the chain ends are segregated to the surface, σ is constant with time and G/G* = [t/τ*]^1/4. For sub-Tg welding, there exists a surface mobile layer (due to the critical Lindemann Atom fraction) of depth X ˜ 1/δT^ν such that G ˜ δT-2ν, where the critical exponent v = 0.8. For incompatible A/B interfaces of Helfand width d, normalized width w = d/Rge, and entanglement density Nent ˜ d/Le, p ˜ d such that, G1c ˜ [d-dc], G1c ˜ [w-1], and G ˜ [Nent-Nc]. For incompatible A/B interfaces reinforced by an areal density σ of compatibilizer chains, L and X are constant, p ˜ σ, pc ˜σc, such that G1c ˜ [σ-σc], which is in excellent agreement with experimental data.

Effect of Tool Offset and Tool Rotational Speed on Enhancing Mechanical Property of Al/Mg Dissimilar FSW Joints

NASA Astrophysics Data System (ADS)

Liang, Zhiyuan; Chen, Ke; Wang, Xiaona; Yao, Junshan; Yang, Qi; Zhang, Lanting; Shan, Aidang

2013-08-01

Friction stir welding (FSW) is a promising solid-state joining technique for producing effective welds between Al alloy and Mg alloy. However, previously reported Al/Mg dissimilar FSW joints generally have limited strength or barely any ductility with relatively high strength, which was blamed on the brittle intermetallics formed during welding. In this study, effective joints with comparably high strength (163 MPa) and large elongation (~6 pct) were obtained. Three crucial/weak zones were identified in the welds: (1) Al/Mg bottom interface (BI) zone that resulted from the insufficient materials' intermixing and interdiffusion; (2) banded structure (BS) zone which contains intermetallic particles possibly formed by constitutional liquation; and (3) softened Al alloy to the retreating side (SAA-RS) zone due to the dissolution and coarsening of the strengthening precipitates. Three fracture modes observed in the tensile specimens perpendicular to the weld seam were found closely related to these zones. Their microstructure evolution with the change of tool rotational speed and tool offset was characterized and the consequent effect on the fracture mode alteration was studied. It turned out that enhancing the strengths of all these zones, but keeping the strength of the SAA lowest, is an effective way for enhancing ductility while keeping comparatively high strength in Al/Mg FSW joints. Also, suggestions for further improving the mechanical property of the Al/Mg dissimilar FSW joints were made accordingly for practical applications.

Rainfall simulation experiments in ecological and conventional vineyards.

NASA Astrophysics Data System (ADS)

Adrian, Alexander; Brings, Christine; Rodrigo Comino, Jesús; Iserloh, Thomas; Ries, Johannes B.

2015-04-01

In October 2014, the Trier University started a measurement series, which defines, compares and evaluates the behavior of runoff and soil erosion with different farming productions in vineyards. The research area is located in Kanzem, a traditional wine village in the Saar Valley (Rheinland-Palatinate, Germany). The test fields show different cultivation methods: ecological (with natural vegetation cover under and around the vines) and conventional cultivated rows of wine. By using the small portable rainfall simulator of Trier University it shall be proved if the assumption that there is more runoff and soil erosion in the conventional part than in the ecological part of the tillage system. Rainfall simulations assess the generation of overland flow, soil erosion and infiltration. So, a trend of soil erosion and runoff of the different cultivation techniques are noted. The objective of this work is to compare the geomorphological dynamics of two different tillage systems. Therefore, 30 rainfall simulations plots were evenly distributed on a west exposition hillside with different slope angels (8-25°), vegetation- and stone-covers. In concrete, the plot surface reaches from strongly covered soil across lithoidal surfaces to bare soil often with compacted lanes of typical using machines. In addition, by using the collected substrate, an estimation and distribution of the grain size of the eroded material shall be given. The eroded substrate is compared to soil samples of the test plots. The first results have shown that there is slightly more runoff and soil erosion in the ecological area than on the conventional part of the vineyard.

Current levels and trends of selected EU Water Framework Directive priority substances in freshwater fish from the German environmental specimen bank.

PubMed

Fliedner, Annette; Lohmann, Nina; Rüdel, Heinz; Teubner, Diana; Wellmitz, Jörg; Koschorreck, Jan

2016-09-01

Under the German environmental specimen bank programme bream (Abramis brama) were sampled in six German rivers and analysed for the priority hazardous substances dicofol, hexabromocyclododecane (HBCDD), hexachlorobenzene (HCB), hexachlorobutadiene (HCBD), heptachlor + heptachlor epoxide (HC + HCE), polybrominated diphenylethers (PBDEs), polychlorinated dibenzo-p-dioxins and -furans and dioxin-like polychlorinated biphenyls (PCDD/Fs + dl-PCBs), and perfluorooctane sulfonic acid (PFOS). The aim was to assess compliance with the EU Water Framework Directive environmental quality standards for biota (EQSBiota) for the year 2013, and to analyse temporal trends for those substances that are of special concern. General compliance was observed for dicofol, HBCDD and HCBD whereas PBDEs exceeded the EQSBiota at all sites. For all other substances compliance in 2013 varied between locations. No assessment was possible for HC + HCE at some sites where the analytical sensitivity was not sufficient to cover the EQSBiota. Trend analysis showed decreasing linear trends for HCB and PFOS at most sampling sites between 1995 and 2014 indicating that the emission reduction measures are effective. Mostly decreasing trends or constant levels were also observed for PCDD/Fs and dl-PCBs. In contrast, increasing trends were detected for PBDEs and HBCDD which were especially pronounced at one Saar site located downstream of the industries and conurbation of Saarbrücken and Völklingen. This finding points to new sources of emissions which should be followed in the coming years. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Pre-Alpine (Variscan) Inheritance: A Key for the Location of the Future Valaisan Basin (Western Alps)

NASA Astrophysics Data System (ADS)

Ballèvre, M.; Manzotti, P.; Dal Piaz, G. V.

2018-03-01

The boundary between the Helvetic and the Penninic (=Briançonnais) Zones has long been recognized as a major fault ("Penninic Front") in the Western Alps. A narrow oceanic domain has been postulated at least along part of this boundary (the Valaisan Basin). However, the information provided by the pre-Triassic basement has not been fully exploited and will be discussed here in detail. The igneous and metamorphic history of the pre-Triassic basement shows significant differences between the External Massifs from the Helvetic Zone, with abundant Late Carboniferous granites, and the basement of the Briançonnais Zone, including the Internal Massifs (Dora-Maira, Gran Paradiso, and Monte Rosa), devoid of Carboniferous granites. A major coal-bearing basin, the "Zone Houillère," opened along this boundary. This limnic intramontane basin has never been properly investigated. The Zone Houillère is not comparable with the external, paralic, flexural, basins on both sides of the Variscan belt but shows similarities with the Saar-Saale Basin. Like the latter, we interpret the Zone Houillère as a transtensional basin opened along a major, crustal-scale, fault zone, namely, the East Variscan Shear Zone. The Permian magmatism and sedimentation displays contrasting distributions, being absent or very localized in the Helvetic Zone, and widespread in the Penninic Zone. The above data indicate that the structural inheritance from the Variscan belt plays a major role in defining the future location of the Valaisan Basin, that is, the boundary between the European paleomargin and the Briançonnais microcontinent.

Searching for Planets in the Hyades. V. Limits on Planet Detection in the Presence of Stellar Activity

NASA Astrophysics Data System (ADS)

Paulson, Diane B.; Cochran, William D.; Hatzes, Artie P.

2004-06-01

We present the results of a radial velocity survey of a sample of Hyades stars and discuss the effects of stellar activity on radial velocity measurements. The level of radial velocity scatter due to rotational modulation of stellar surface features for the Hyades is in agreement with the 1997 predictions of Saar & Donahue-the maximum radial velocity rms of up to ~50 m s-1, with an average rms of ~16 m s-1. In this sample of 94 stars we find one new binary, two stars with linear trends indicative of binary companions, and no close-in giant planets. We discuss the limits on extrasolar planet detection in the Hyades and the constraints imposed on radial velocity surveys of young stars. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration (NASA). The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Additional data were obtained with the Hobby-Eberly Telescope, which is operated by McDonald Observatory on behalf of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

Two-Stage, Integrated, Geothermal-CO2 Storage Reservoirs: An Approach for Sustainable Energy Production, CO2-Sequestration Security, and Reduced Environmental Risk

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buscheck, T A; Chen, M; Sun, Y

2012-02-02

We introduce a hybrid two-stage energy-recovery approach to sequester CO{sub 2} and produce geothermal energy at low environmental risk and low cost by integrating geothermal production with CO{sub 2} capture and sequestration (CCS) in saline, sedimentary formations. Our approach combines the benefits of the approach proposed by Buscheck et al. (2011b), which uses brine as the working fluid, with those of the approach first suggested by Brown (2000) and analyzed by Pruess (2006), using CO{sub 2} as the working fluid, and then extended to saline-formation CCS by Randolph and Saar (2011a). During stage one of our hybrid approach, formation brine,more » which is extracted to provide pressure relief for CO{sub 2} injection, is the working fluid for energy recovery. Produced brine is applied to a consumptive beneficial use: feedstock for fresh water production through desalination, saline cooling water, or make-up water to be injected into a neighboring reservoir operation, such as in Enhanced Geothermal Systems (EGS), where there is often a shortage of a working fluid. For stage one, it is important to find economically feasible disposition options to reduce the volume of brine requiring reinjection in the integrated geothermal-CCS reservoir (Buscheck et al. 2012a). During stage two, which begins as CO{sub 2} reaches the production wells; coproduced brine and CO{sub 2} are the working fluids. We present preliminary reservoir engineering analyses of this approach, using a simple conceptual model of a homogeneous, permeable CO{sub 2} storage formation/geothermal reservoir, bounded by relatively impermeable sealing units. We assess both the CO{sub 2} sequestration capacity and geothermal energy production potential as a function of well spacing between CO{sub 2} injectors and brine/CO{sub 2} producers for various well patterns and for a range of subsurface conditions.« less

[Growth Factors and Interleukins in Amniotic Membrane Tissue Homogenate].

PubMed

Stachon, T; Bischoff, M; Seitz, B; Huber, M; Zawada, M; Langenbucher, A; Szentmáry, N

2015-07-01

Application of amniotic membrane homogenate eye drops may be a potential treatment alternative for therapy resistant corneal epithelial defects. The purpose of this study was to determine the concentrations of epidermal growth factor (EGF), fibroblast growth factor basic (bFGF), hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), interleukin-6 (IL-6) and interleukin-8 (IL-8) in amniotic membrane homogenates. Amniotic membranes of 8 placentas were prepared and thereafter stored at - 80 °C using the standard methods of the LIONS Cornea Bank Saar-Lor-Lux, Trier/Westpfalz. Following defreezing, amniotic membranes were cut in two pieces and homogenized in liquid nitrogen. One part of the homogenate was prepared in cell-lysis buffer, the other part was prepared in PBS. The tissue homogenates were stored at - 20 °C until enzyme-linked immunosorbent assay (ELISA) analysis for EGF, bFGF, HGF, KGF, IL-6 and IL-8 concentrations. Concentrations of KGF, IL-6 and IL-8 were below the detection limit using both preparation techniques. The EGF concentration in tissue homogenates treated with cell-lysis buffer (2412 pg/g tissue) was not significantly different compared to that of tissue homogenates treated with PBS (1586 pg/g tissue, p = 0.72). bFGF release was also not significantly different using cell-lysis buffer (3606 pg/g tissue) or PBS treated tissue homogenates (4649 pg/g tissue, p = 0.35). HGF release was significantly lower using cell-lysis buffer (23,555 pg/g tissue), compared to PBS treated tissue (47,766 pg/g tissue, p = 0.007). Containing EGF, bFGF and HGF, and lacking IL-6 and IL-8, the application of amniotic membrane homogenate eye drops may be a potential treatment alternative for therapy-resistant corneal epithelial defects. Georg Thieme Verlag KG Stuttgart · New York.

Bingham fluid behavior of plagioclase-bearing basaltic magma: Approach from laboratory viscosity measurements

NASA Astrophysics Data System (ADS)

Ishibashi, H.; Sato, H.

2010-12-01

Datasets of one atmosphere high temperature rotational viscometry of the Fuji 1707 basalt (Ishibashi, 2009) were analyzed based on the Bingham fluid model, and both yield stress and Bingham viscosity were determined. Reproducibility of the dataset by the Bingham fluid model was slightly better than that by the power law fluid modes adopted in our previous study although both the fluid models well represent the dataset in practical perspective. The relation between Bingham viscosity and crystallinity was compared with the Krieger-Dougherty equation, and both the maximum packing fraction of crystals and intrinsic viscosity for Bingham viscosity were determined ca. 0.45 and ca. 5.25, respectively, revealing that the maximum packing fraction decreased and intrinsic viscosity increased concomitantly with the increase in shape-anisotropy of crystals. However, the obtained value of the product of the maximum packing fraction and intrinsic viscosity (= ca. 2.36) was similar to that of uniform, isotropic-shaped particles (= 2.5), indicating that the effect of crystal shape-anisotropy on Bingham viscosity might be predicted only by change of the maximum packing fraction. Finite yield stress was detected for crystallinity larger than 0.133; it increased with crystallinity which suggests that critical crystallinity for onset of yield stress is at least lower than 0.133. The upper limit value of the critical crystallinity resembles the value calculated numerically for randomly oriented uniform particles by Saar et al. (2001) (0.10-0.15 for width/length ratio of 0.1-0.2, which is similar to the ratios in the basalt) whereas crystals in the basalt were moderately parallel arranged and their sizes vary significantly. That fact might be explained as follows; effects of parallel arrangement and size variation of crystals on the critical crystallinity are offset by the effect of variation in crystal shape-anisotropy, which suggests that shape-anisotropy distribution of crystals must

Time resolved spectroscopic investigation of SiD2 + D2: kinetic study

NASA Astrophysics Data System (ADS)

Al-Rubaiey, Najem A.; Walsh, Robin

2017-03-01

Silylenes (silanediyls) have made an important impact on organosilicon chemistry even if it is of more recent foundation than carbenes in organic chemistry and much less complete. These species are highly reactive intermediates. They play a central role in the chemical vapour deposition (CVD) of various silicon-containing thin films which have a technological importance in microelectronics as well as in the dry etching processes of silicon wafers. Spectroscopic methods have been developed to observe these species, a necessary pre-requisite to their direct monitoring. In this work, deuterated phenylsilane precursor, PhSiD3 was chosen for SiD2 because its analogue phenylsilane, PhSiH3 proved to be a good precursor for SiH2 and the high quality decay signals observed revealed that SiD2 be readily detected from PhSiD3 and that if other decomposition pathways (e.g. PhSiD + D2) are occurring, they do not effect measurements of the rate constants for SiD2. The absorption spectrum of SiD2 formed from the flash photolysis of a mixture of PhSiD3 and SF6 at 193nm were found in the region 17384-17391 cm-1 with strong band at 17387.07 cm-1. This single rotational line of pQ1 was chosen to monitor SiD2 removal. Time-resolved studies of SiD2 have been carried out to obtain rate constants for its bimolecular reactions with D2. The reactions were studied over the pressure range 5-100 Torr (in SF6 bath gas) at four temperatures in the range 298-498K. Single decay from 10 photolysis laser shots were averaged and found to give reasonable first-order kinetics fits. Second order kinetics were obtained by pressure dependence of the pseudo first order decay constants and substance D2 pressures within experimental error. The reaction was found to be weakly pressure dependent at all temperatures, consistent with a third-body mediated association process. In addition, SiH2+ H2 reaction is approximately ca. 60% faster than SiD2+D2 reaction. Theoretical extrapolations (using Lindemann

The Time Is Now: Bioethics and LGBT Issues.

PubMed

Powell, Tia; Foglia, Mary Beth

2014-09-01

Our goal in producing this special issue is to encourage our colleagues to incorporate topics related to LGBT populations into bioethics curricula and scholarship. Bioethics has only rarely examined the ways in which law and medicine have defined, regulated, and often oppressed sexual minorities. This is an error on the part of bioethics. Medicine and law have served in the past as society's enforcement arm toward sexual minorities, in ways that robbed many people of their dignity. We feel that bioethics has an obligation to discuss that history and to help us as a society take responsibility for it. We can address only a small number of topics in this special issue of the Hastings Center Report, and we selected topics we believe will stimulate discourse. Andrew Solomon offers an elegant overview of the challenges that bioethics faces in articulating a solid basis for LGBT rights. Timothy F. Murphy asks whether bioethics still faces issues related to lesbian, gay, and bisexual people, given the deletion of homosexuality as a disease and the progress toward same-sex marriage. Jamie Lindemann Nelson's essay addresses the search for identity for transgender persons and the role of science in that search. Two articles, those by Brendan S. Abel and by Jack Drescher and Jack Pula, take up the complex issue of medical treatment for children who reject their assigned birth gender. Celia B. Fisher and Brian Mustanski address the special challenges of engaging LGBT youth in research, balancing the need for better information about this vulnerable group against the existing restrictions on research involving children. Tia Powell and Edward Stein consider the merits of legal bans on psychotherapies intended to change sexual orientation, particularly in the light of current research on orientation. Mary Beth Foglia and Karen I. Fredricksen-Goldsen highlight health disparities and resilience among LGBT older adults and then discuss the role of nonconscious bias in perpetuating

Fritz London

NASA Astrophysics Data System (ADS)

Gavroglu, Kostas

2005-11-01

Preface; Acknowledgements; Part I. From Philosophy to Physics: The years that left nothing unaffected; 1. The appeal of ideas; 2. Goëthe as a scientist; 3. How absolute is our knowledge?; 4. How do we come to know things?; 5. London's teachers in philosophy; 6. Husserl's teachings; 7. Expectations of things to come; 8. The thesis in philosophy; 9. Tolman's principle of similitude; 10. The necessary clarifications; 11. Work on quantum theory; 12. Transformation theory; 13. Unsuccessful attempts at unification; Part II. The Years in Berlin and the Beginnings of Quantum Chemistry: The mysterious bond; 14. London in Zürich; 15. Binding forces; 16. The Pauli principle; 17. Reactions to the Heitler-London paper; 18. Polyelectronic molecules and the application of group theory to problems of chemical valence; 19. Chemists as physicists?; 20. London's first contacts in Berlin; 21. Marriage; 22. Job offers; 23. Intermolecular forces; 24. The book which could not be written; 25. Leningrad and Rome; 26. Difficulties with group theory; 27. Linus Pauling's resonance structures; 28. Robert Mulliken's molecular orbitals; Part III. Oxford and Superconductivity: The rise of the Nazis; 29. Going to Oxford; 30. Lindemann, Simon and Heinz London; 31. Electricity in the very cold; 32. The end of old certainties; 33. The thermodynamic treatment; 34. The theory of Fritz and Heinz London; 35. Initial reactions by von Laue; 36. The discussion at the Royal Society; 37. Termination of the ICI fellowship; Part IV. Paris and Superfluidity: The Front Populaire; 38. The article in Nature 1937 and 'Nouvelle Conception'; 39. Laue again; 40. The structure of solid helium; 41. The peculiar properties of helium; 42. Bose-Einstein condensation; 43. The note in Nature; 44. The two-fluid model; 45. The trip to Jerusalem; 46. Leaving again; 47. The observer in quantum mechanics; Part V. United States and the Typing up of Loose Ends: Duke University, North Carolina; 48. The Soviet Union, Kapitza and

Lost in the Dark: A proto-history of dark matter

NASA Astrophysics Data System (ADS)

Trimble, Virginia L.; History 1

2016-01-01

Einasto, Kaasik, and Saar (published in Nature, in case you are thinking of more Meddelande). I feel enormous respect and affection for Vera Rubin and Fritz Zwicky, but the published papers as are they are.

[Correlation between microbial growth in conjunctival swabs of corneal donors and contamination of organ culture media].

PubMed

Li, S; Bischoff, M; Schirra, F; Langenbucher, A; Ong, M; Halfmann, A; Herrmann, M; Seitz, B

2014-06-01

The aim of the study was to determine the rate of contamination in conjunctival swabs from corneal donors by microbiological investigations and to correlate this with microbial contamination of the culture medium. Contamination of conjunctival swabs and culture media was analyzed retrospectively for the years 2009, 2010 and 2011 at the LIONS corneal bank of Saar-Lor-Lux Trier/Westpfalz at the Saarland University Medical Center. The total annual number of conjunctival swabs was 316 in 2009, 341 in 2010 and 381 in 2011. Conjunctival swabs were taken prior to 1.25% povidone-iodine application. After disinfection donor corneas were harvested by in situ corneoscleral disc excision in all cases. The correlation between positive conjunctival swabs and microbial contamination of the culture medium was analyzed. In every year examined the contamination rate of the culture medium was significantly higher in cases of contaminated conjunctival swabs (p < 0.05 in 2009, p < 0.001 in 2010 and p = 0.004 in 2011). Of the conjunctival swabs 38.3% (2009), 53.7% (2010) and 55.6% (2011), respectively exhibited microbial growth. The principal microorganisms detected in the conjunctival swabs were coagulase negative staphylococci, gram negative rods and Staphylococcus aureus. Extending the exposure time to povidone-iodine prior to removal of the corneoscleral disc from 3 min in the year 2009 to 5 min since the year 2010 resulted in a highly statistically significant (p < 0.001) reduction in contamination frequency of the medium from 10.8% (2009) to 7.0% (2010) and 4.5% (2011) was observed. In 2009, 2010 and 2011 the culture medium was contaminated in 16.5%, 11.5% and 7.6% of the donated corneas with positive conjunctival swabs and in 7.2%, 1.9% and 0.6% in donated corneas with negative conjunctival swabs, respectively. A positive correlation was found between contamination of the culture medium and microbial colonization of the conjunctival swabs, Nevertheless, microbial colonization of

Modifications of transaxillary approach in endoscopic da Vinci-assisted thyroid and parathyroid gland surgery.

PubMed

Al Kadah, Basel; Piccoli, Micaela; Mullineris, Barbara; Colli, Giovanni; Janssen, Martin; Siemer, Stephan; Schick, Bernhard

2015-03-01

Endoscopic surgery for treatment of thyroid and parathyroid pathologies is increasingly gaining attention. The da Vinci system has already been widely used in different fields of medicine and quite recently in thyroid and parathyroid surgery. Herein, we report about modifications of the transaxillary approach in endoscopic surgery of thyroid and parathyroid gland pathologies using the da Vinci system. 16 patients suffering from struma nodosa in 14 cases and parathyroid adenomas in two cases were treated using the da Vinci system at the ENT Department of Homburg/Saar University and in cooperation with the Department of General Surgery in New Sant'Agostino Hospital, Modena/Italy. Two different retractors, endoscopic preparation of the access and three different incision modalities were used. The endoscopic preparation of the access allowed us to have a better view during preparation and reduced surgical time compared to the use of a headlamp. To introduce the da Vinci instruments at the end of the access preparation, the skin incisions were over the axilla with one incision in eight patients, two incisions in four patients and three incisions in a further four patients. The two and three skin incisions modality allowed introduction of the da Vinci instruments without arm conflicts. The use of a new retractor (Modena retractor) compared to a self-developed retractor made it easier during the endoscopic preparation of the access and the reposition of the retractor. The scar was hidden in the axilla and independent of the incisions selected, the cosmetic findings were judged by the patients to be excellent. The neurovascular structures such as inferior laryngeal nerve, superior laryngeal nerve and vessels, as well as the different pathologies, were clearly 3D visualized in all 16 cases. No paralysis of the vocal cord was observed. All patients had a benign pathology in their histological examination. The endoscopic surgery of the thyroid and parathyroid gland can be

Effect of Hydrogen and Carbon on the Melting Temperature of the Core

NASA Astrophysics Data System (ADS)

Nakajima, Y.; Sakamaki, K.; Takahashi, E.; Fukai, Y.; Suzuki, T.; Funakoshi, K.

2007-12-01

, respectively. The melting temperatures of Fe3C determined by our experiments are >700 K lower than that of the previous estimation based on thermodynamic calculation (Wood, 1993). Our experimental results show a possibility that the hydrogen and carbon lower the melting temperature of iron (outer core) dramatically. The melting temperatures of γ-FeH and Fe3C at 20 GPa are already 500 K lower than that of pure iron estimated by Anderson and Isaak (2000). Extrapolating our experimental melting curves for FeH and Fe3C to core pressures using Lindemann's melting law, we obtained the melting temperatures to be ~2600 and ~2900 K at the core-mantle boundary (CMB), respectively. In the presence of both hydrogen and carbon, melting temperature of the Earth's outer core could be >1500 K lower than that of the previous estimates, implying that the temperature gap at CMB could be much smaller than the current estimates.

PREFACE: 3rd International Workshop on Infrared Plasma Spectroscopy

NASA Astrophysics Data System (ADS)

Davies, P. B.; Röpcke, Jürgen; Hempel, Frank

2009-07-01

the scientific committee felt that this time it would be useful to emphasise new spectroscopic developments as well as covering applications. This might serve as a guide as to where the subject of infrared spectroscopy in combination with plasma sources might be heading in the future i.e. to emphasize pure infrared spectroscopy developments. The first invited lecture (G Guelachvili and N Picque) and the last invited lecture (F K Tittel, Y Bakhirkin, R Curl, A Kosterev, R Lewicki, D Thomasz and S So) were chosen to set the scene and realise this objective. The second (R Engeln, R Zijlmans, S Welzel, O Gabriel, J-P van Helden, J Röpcke and D Schram) and third (X Aubert, C Lazzaroni, D Marinov, O Guaitella, S Welzel, A Pipa, J Röpcke and A Rousseau) invited talks focussed on the application of the IR laser techniques with particular emphasis on the role of surfaces in plasmas and the relevance of plasma surface interactions. Surface plasma interactions did not feature strongly in the two earlier meetings and so this topic too, along with the emphasis on novel infrared spectroscopy techniques, represents a new direction for the conference. Paul B Davies and Jürgen Röpcke International Scientific Committee P B Davies, Cambridge, UK: Chair J Röpcke, Greifswald, Germany: Co-Chair R Engeln, Eindhoven, Netherlands G Hancock, Oxford, U K M Hori, Nagoya, Japan H Linnartz, Leiden, Netherlands R Martini, New York, USA J Meichsner, Greifswald, Germany A Rousseau, Paris, France Local Organizing Committee J Röpcke (INP: Chair) F Hempel (INP: Secretary) J Meichsner (IfP, University of Greifswald) N Lang (INP) L Glawe (INP) C Krcka (INP) B Lindemann (INP) Conference photograph

Effects of high shock pressures and pore morphology on hot spot mechanisms in HMX

NASA Astrophysics Data System (ADS)

Springer, H. K.; Tarver, C. M.; Bastea, S.

2017-01-01

The shock initiation and detonation behavior of heterogeneous solid explosives is governed by its microstructure and reactive properties. New additive manufacturing techniques offer unprecedented control of explosive microstructures previously impossible, enabling us to develop novel explosives with tailored shock sensitivity and detonation properties. Since microstructure-performance relationships are not well established for explosives, there is little material design guidance for these manufacturing techniques. In this study, we explore the effects of high shock pressures (15-38 GPa) with long shock durations and different pore morphologies on hot spot mechanisms in HMX. HMX is chosen as the model material because we have experimental data on many of the chemical-thermal-mechanical properties required for pore collapse simulations. Our simulations are performed using the multi-physics arbitrary Lagrangian Eulerian finite element hydrocode, ALE3D, with Cheetah-based models for the unreacted and the product equation-of-states. We use a temperature-dependent specific heat with the unreacted equation-of-state and a temperature-dependent viscosity model to ensure accurate shock temperatures for subsequent chemistry. The Lindemann Law model is used for shock melting in HMX. In contrast to previous pore collapse studies at lower shock pressures (≤10 GPa) in HMX and shorter post-collapse burning times, our calculations show that shock melting occurs above 15 GPa due to higher bulk heating and a prominent elongated ("jet-like") hot spot region forms at later times. The combination of the elongated, post-collapse hot spot region and the higher bulk heating with increasing pressure dramatically increases the growth rate of reaction. Our calculations show that the reaction rate, dF/dt, increases with increasing shock pressure. We decompose the reaction rate into ignition ((dF/dt)ig) and growth ((dF/dt)gr) phases to better analyze our results. We define the ignition phase

Outcrop analogue study of Permocarboniferous geothermal sandstone reservoir formations (northern Upper Rhine Graben, Germany): impact of mineral content, depositional environment and diagenesis on petrophysical properties

NASA Astrophysics Data System (ADS)

Aretz, Achim; Bär, Kristian; Götz, Annette E.; Sass, Ingo

2016-07-01

The Permocarboniferous siliciclastic formations represent the largest hydrothermal reservoir in the northern Upper Rhine Graben in SW Germany and have so far been investigated in large-scale studies only. The Cenozoic Upper Rhine Graben crosses the Permocarboniferous Saar-Nahe Basin, a Variscan intramontane molasse basin. Due to the subsidence in this graben structure, the top of the up to 2-km-thick Permocarboniferous is located at a depth of 600-2900 m and is overlain by Tertiary and Quaternary sediments. At this depth, the reservoir temperatures exceed 150 °C, which are sufficient for geothermal electricity generation with binary power plants. To further assess the potential of this geothermal reservoir, detailed information on thermophysical and hydraulic properties of the different lithostratigraphical units and their depositional environment is essential. Here, we present an integrated study of outcrop analogues and drill core material. In total, 850 outcrop samples were analyzed, measuring porosity, permeability, thermal conductivity and thermal diffusivity. Furthermore, 62 plugs were taken from drillings that encountered or intersected the Permocarboniferous at depths between 1800 and 2900 m. Petrographic analysis of 155 thin sections of outcrop samples and samples taken from reservoir depth was conducted to quantify the mineral composition, sorting and rounding of grains and the kind of cementation. Its influence on porosity, permeability, the degree of compaction and illitization was quantified. Three parameters influencing the reservoir properties of the Permocarboniferous were detected. The strongest and most destructive influence on reservoir quality is related to late diagenetic processes. An illitic and kaolinitic cementation and impregnation of bitumina document CO2- and CH4-rich acidic pore water conditions, which are interpreted as fluids that migrated along a hydraulic contact from an underlying Carboniferous hydrocarbon source rock. Migrating

Using geoinformatics and cultural anthropology to identify links between land change, driving forces and actors in the Okavango catchment

NASA Astrophysics Data System (ADS)

Röder, Achim; Stellmes, Marion; Pröpper, Michael; Schneibel, Anne

2015-04-01

central institutions and are implemented in different ways at subordinate levels. Commonly, communities make their own decisions regarding the use of natural resources within the framework of statutory and traditional governance and national legislation. The Permanent Okavango River Basin Water Commission (OKACOM) has been created between Angola, Namibia and Botswana to deal with transboundary subjects and facilitate informed policies. Developing such informed policies is even more urgent given demographic and climatological predictions. The African population is expected to almost double by the end of this century (Haub 2012), while climate predictions indicate an overall increase in average temperatures, added to by an increase in dry spells during the wet season and overall decreases in precipitation (IPCC 2013). This will result in increasing demands for food, paralleled by less favorable production conditions. The appropriation of resources in the wider region is therefore characterized by various, potentially conflicting demands that are likely to accumulate in space and time (Röder, Stellmes et al. 2013). A particular constraint draws from upstream-downstream issues, with a predicted increase in upstream water utilization for drinking and irrigation, while the Delta region relies on regular flood pulses of clean water to sustain its biodiversity, to which the tourist sector as a major source of national income is linked. This is threatened by the increasing concentrations of pesticides and herbicides used in the frame of irrigation schemes lowering water quality, and the change of flood pulse cycles through damming projects (Lindemann 2009). Besides national policies and regional planning programs, an equally important element in understanding the utilization of natural resources is the individual perspective of actors that may range from the conservation of traditions and cultures to stronger market integration and consumerism (Pröpper, Falk et al. 2013) that

Contrasting Permo - Carboniferous Evolution of Resita and Sirinia - Presacina Basins (South Carpathians, Romania); an overview.

NASA Astrophysics Data System (ADS)

Tatu, M.; Seghedi, I.; Nutu, L. M.; Nicolae, I.

2009-04-01

- sinistral shear fault system adjacent to the Tornquist - Teisseyre Line, which induced the fragmentation of Variscan fold belt. With this process was associated the formation of many transtensional pull-apart continental - lacustrian sedimentary basins and intra-continental rifts in which or in adjacent areas the intrusive - extrusive magmatism was widespread and where the deep crustal fractures were active. From climatic point of view the main consequence of continue convergence between Laurasia and Gondwana is the transition from relatively wet regime during Stephanian to arid during the Permian induced by the elevation of the equatorial highlands Variscan fold belt was acted as a precipitation barrier for the whole territory located to the north. Tacking into account of all these aspects, the Resita domain presents the similarities in the lithological composition with Autun Basin and the Sirinia - Presacina zone displays many common features with Saar - Nahe and Thuringian Forest Basins and North German/Polish Depression. This work started during PALEOCLIM project (grant ANCS - PN2, 31-063/2007), which is gratefully acknowledged. References Nastaseanu S. 1987. In: Flügel E., Sassi F. & Grecula P. (eds): Pre-Variscan and Variscan events in the Alpine-Mediterranean mountain belts. - Mineralia Slovaca. Alfa Bratislava, 371-378. Stollhofen H., Frommherz B., Stanistreet I. G. 1999. J. Geol. Soc. London 156, 801-808. Ziegler P. A. 1990. Shell Int. Petrol. Mij. Dist. Geol. Soc. Publ. House, Bath, 1-239.