Improving spatial resolution in skin-contact thermography: comparison between a spline based and linear interpolation.

PubMed

Giansanti, Daniele

2008-07-01

A wearable device for skin-contact thermography [Giansanti D, Maccioni G. Development and testing of a wearable integrated thermometer sensor for skin contact thermography. Med Eng Phys 2006 [ahead of print

Calculations of two new dose metrics proposed by AAPM Task Group 111 using the measurements with standard CT dosimetry phantoms

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

Li, Xinhua; Zhang, Da; Liu, Bob

2013-08-15

Purpose: AAPM Task Group 111 proposed to measure the equilibrium dose-pitch product D-caret{sub eq} for scan modes involving table translation and the midpoint dose D{sub L}(0) for stationary-table modes on the central and peripheral axes of sufficiently long (e.g., at least 40 cm) phantoms. This paper presents an alternative approach to calculate both metrics using the measurements of scanning the standard computed tomographic (CT) dosimetry phantoms on CT scanners.Methods: D-caret{sub eq} was calculated from CTDI{sub 100} and ε(CTDI{sub 100}) (CTDI{sub 100} efficiency), and D{sub L}(0) was calculated from D-caret{sub eq} and the approach to equilibrium function H(L) =D{sub L}(0)/D{sub eq},more » where D{sub eq} was the equilibrium dose. CTDI{sub 100} may be directly obtained from several sources (such as medical physicist's CT scanner performance evaluation or the IMPACT CT patient dosimetry calculator), or be derived from CTDI{sub Vol} using the central to peripheral CTDI{sub 100} ratio (R{sub 100}). The authors have provided the required ε(CTDI{sub 100}) and H(L) data in two previous papers [X. Li, D. Zhang, and B. Liu, Med. Phys. 39, 901–905 (2012); and ibid. 40, 031903 (10pp.) (2013)]. R{sub 100} was assessed for a series of GE, Siemens, Philips, and Toshiba CT scanners with multiple settings of scan field of view, tube voltage, and bowtie filter.Results: The calculated D{sub L}(0) and D{sub L}(0)/D{sub eq} in PMMA and water cylinders were consistent with the measurements on two GE CT scanners (LightSpeed 16 and VCT) by Dixon and Ballard [Med. Phys. 34, 3399–3413 (2007)], the measurements on a Siemens CT scanner (SOMATOM Spirit Power) by Descamps et al. [J. Appl. Clin. Med. Phys. 13, 293–302 (2012)], and the Monte Carlo simulations by Boone [Med. Phys. 36, 4547–4554 (2009)].Conclusions: D-caret{sub eq} and D{sub L}(0) can be calculated using the alternative approach. The authors have provided the required ε(CTDI{sub 100}) and H(L) data in two previous papers. R{sub 100} is presented for a majority of multidetector CT scanners currently on the market, and can be easily assessed for other CT scanners or operating conditions not covered in this study. The central to peripheral D{sub eq} ratio is about 1.50 and 1.12 times of R{sub 100} for the 32- and 16-cm diameter PMMA phantom, respectively.« less

Stationary Digital Tomosynthesis System for Early Detection of Breast Tumors

DTIC Science & Technology

2012-05-01

Vol. 5745. 2005. 14. Y. Zhang, et al., A comparative study of limited-angle cone-beam reconstruction methods 505 for breast tomosynthesis. Med...opening angl em integratio designed line nia Dimension determine the try calibration th the detector ain is sent fro between XC urce not fou here...screening mammography. AJR, 2007. 189: p. 616. 12. P. Baldelli, et al., A prototype of a quasi-monochromatic system for mammography applications . Phys

X-Ray Phase Imaging for Breast Cancer Detection

DTIC Science & Technology

2011-09-01

the inline phase contrast imaging has good potential of greatly enhanc - ing the detection sensitivity and reducing radiation doses involved in the...the edge- enhancement generated by phase- contrast is generally useful for imaging the wrap, however, such edge- enhancements may lead interpretation...Kotre and I. P. Birch, “Phase contrast enhancement of x-ray mam- mography: A design study,” Phys. Med. Biol. 44, 2853–2866 (1999). 6F. Arfelli et al

Using weighted power mean for equivalent square estimation.

PubMed

Zhou, Sumin; Wu, Qiuwen; Li, Xiaobo; Ma, Rongtao; Zheng, Dandan; Wang, Shuo; Zhang, Mutian; Li, Sicong; Lei, Yu; Fan, Qiyong; Hyun, Megan; Diener, Tyler; Enke, Charles

2017-11-01

Equivalent Square (ES) enables the calculation of many radiation quantities for rectangular treatment fields, based only on measurements from square fields. While it is widely applied in radiotherapy, its accuracy, especially for extremely elongated fields, still leaves room for improvement. In this study, we introduce a novel explicit ES formula based on Weighted Power Mean (WPM) function and compare its performance with the Sterling formula and Vadash/Bjärngard's formula. The proposed WPM formula is ESWPMa,b=waα+1-wbα1/α for a rectangular photon field with sides a and b. The formula performance was evaluated by three methods: standard deviation of model fitting residual error, maximum relative model prediction error, and model's Akaike Information Criterion (AIC). Testing datasets included the ES table from British Journal of Radiology (BJR), photon output factors (S cp ) from the Varian TrueBeam Representative Beam Data (Med Phys. 2012;39:6981-7018), and published S cp data for Varian TrueBeam Edge (J Appl Clin Med Phys. 2015;16:125-148). For the BJR dataset, the best-fit parameter value α = -1.25 achieved a 20% reduction in standard deviation in ES estimation residual error compared with the two established formulae. For the two Varian datasets, employing WPM reduced the maximum relative error from 3.5% (Sterling) or 2% (Vadash/Bjärngard) to 0.7% for open field sizes ranging from 3 cm to 40 cm, and the reduction was even more prominent for 1 cm field sizes on Edge (J Appl Clin Med Phys. 2015;16:125-148). The AIC value of the WPM formula was consistently lower than its counterparts from the traditional formulae on photon output factors, most prominent on very elongated small fields. The WPM formula outperformed the traditional formulae on three testing datasets. With increasing utilization of very elongated, small rectangular fields in modern radiotherapy, improved photon output factor estimation is expected by adopting the WPM formula in treatment planning and secondary MU check. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

[Analysis on literatures about clinical treatment of low back pain with acupuncture and moxibustion published in the periodicals included by SCI in recent 5 years].

PubMed

Jiang, Chui-gang

2007-03-01

To explore the development state of acupuncture and moxibustion therapy in the world. Retrieve and analyze the literatures about clinically treating low back pain with acupuncture and moxibustion published at periodicals included by SCI in recent 5 years in Pubmed. Nineteen concerned literatures were retrieved. Authors of the literatures come from USA, Germany, Hong Kong of China, UK (including Northern Ireland) , Austria, Sweden and Italy. The literatures were published at Altern Ther Health Med, Am J Phys Med Rehabil, Anesth Analg, Arch Intern Med, Forsch Komplementärmed Klass Naturheilkd, Health Technol Assess, Rheumatology (Oxford), South Med J, Spine, Complment Ther Med, Pain. Three researches show that efficacy of acupuncture is uncertain. Other researches support the efficacy of acupuncture. The researches on treating low back pain with acupuncture and moxibustion are still mainly about efficacy of the acupuncture and moxibustion therapy. The acupuncture and moxibustion therapy is still in the process of gradually admitted by international medicine.

Enhancement of Radiation Therapy in Prostate Cancer by DNA-PKcs Inhibitor

DTIC Science & Technology

2013-07-01

Dawen Zhao, Masaya Takahashi, Timothy Dobin, Leah Gandee, Timothy D. Solberg, Amyn A. Habib and Debabrata Saha; International Journal of Oncology, 42...5] Kong Z, Xie D, Boike T, Raghavan P, Burma S, Chen DJ, Habib AA, Chakraborty A, Hsieh JT, and Saha D (2010). Downregulation of human DAB2IP gene...study. Phys Med Biol 56: 1243-1258, 2011. 4. De Crevoisier R, Tucker SL , Dong L, et al: Increased risk of biochemical and local failure in patients

EDITORIAL: Special section: Selected papers from the Third European Workshop on Monte Carlo Treatment Planning (MCTP2012) Special section: Selected papers from the Third European Workshop on Monte Carlo Treatment Planning (MCTP2012)

NASA Astrophysics Data System (ADS)

Spezi, Emiliano; Leal, Antonio

2013-04-01

The Third European Workshop on Monte Carlo Treatment Planning (MCTP2012) was held from 15-18 May, 2012 in Seville, Spain. The event was organized by the Universidad de Sevilla with the support of the European Workgroup on Monte Carlo Treatment Planning (EWG-MCTP). MCTP2012 followed two successful meetings, one held in Ghent (Belgium) in 2006 (Reynaert 2007) and one in Cardiff (UK) in 2009 (Spezi 2010). The recurrence of these workshops together with successful events held in parallel by McGill University in Montreal (Seuntjens et al 2012), show consolidated interest from the scientific community in Monte Carlo (MC) treatment planning. The workshop was attended by a total of 90 participants, mainly coming from a medical physics background. A total of 48 oral presentations and 15 posters were delivered in specific scientific sessions including dosimetry, code development, imaging, modelling of photon and electron radiation transport, external beam radiation therapy, nuclear medicine, brachitherapy and hadrontherapy. A copy of the programme is available on the workshop's website (www.mctp2012.com). In this special section of Physics in Medicine and Biology we report six papers that were selected following the journal's rigorous peer review procedure. These papers actually provide a good cross section of the areas of application of MC in treatment planning that were discussed at MCTP2012. Czarnecki and Zink (2013) and Wagner et al (2013) present the results of their work in small field dosimetry. Czarnecki and Zink (2013) studied field size and detector dependent correction factors for diodes and ion chambers within a clinical 6MV photon beam generated by a Siemens linear accelerator. Their modelling work based on the BEAMnrc/EGSnrc codes and experimental measurements revealed that unshielded diodes were the best choice for small field dosimetry because of their independence from the electron beam spot size and correction factor close to unity. Wagner et al (2013) investigated the recombination effect on liquid ionization chambers for stereotactic radiotherapy, a field of increasing importance in external beam radiotherapy. They modelled both radiation source (Cyberknife unit) and detector with the BEAMnrc/EGSnrc codes and quantified the dependence of the response of this type of detectors on factors such as the volume effect and the electrode. They also recommended that these dependences be accounted for in measurements involving small fields. In the field of external beam radiotherapy, Chakarova et al (2013) showed how total body irradiation (TBI) could be improved by simulating patient treatments with MC. In particular, BEAMnrc/EGSnrc based simulations highlighted the importance of optimizing individual compensators for TBI treatments. In the same area of application, Mairani et al (2013) reported on a new tool for treatment planning in proton therapy based on the FLUKA MC code. The software, used to model both proton therapy beam and patient anatomy, supports single-field and multiple-field optimization and can be used to optimize physical and relative biological effectiveness (RBE)-weighted dose distribution, using both constant and variable RBE models. In the field of nuclear medicine Marcatili et al (2013) presented RAYDOSE, a Geant4-based code specifically developed for applications in molecular radiotherapy (MRT). RAYDOSE has been designed to work in MRT trials using sequential positron emission tomography (PET) or single-photon emission tomography (SPECT) imaging to model patient specific time-dependent metabolic uptake and to calculate the total 3D dose distribution. The code was validated through experimental measurements in homogeneous and heterogeneous phantoms. Finally, in the field of code development Miras et al (2013) reported on CloudMC, a Windows Azure-based application for the parallelization of MC calculations in a dynamic cluster environment. Although the performance of CloudMC has been tested with the PENELOPE MC code, the authors report that software has been designed in a way that it should be independent of the type of MC code, provided that simulation meets a number of operational criteria. We wish to thank Elekta/CMS Inc., the University of Seville, the Junta of Andalusia and the European Regional Development Fund for their financial support. We would like also to acknowledge the members of EWG-MCTP for their help in peer-reviewing all the abstracts, and all the invited speakers who kindly agreed to deliver keynote presentations in their area of expertise. A final word of thanks to our colleagues who worked on the reviewing process of the papers selected for this special section and to the IOP Publishing staff who made it possible. MCTP2012 was accredited by the European Federation of Organisations for Medical Physics as a CPD event for medical physicists. Emiliano Spezi and Antonio Leal Guest Editors References Chakarova R, Müntzing K, Krantz M, E Hedin E and Hertzman S 2013 Monte Carlo optimization of total body irradiation in a phantom and patient geometry Phys. Med. Biol. 58 2461-69 Czarnecki D and Zink K 2013 Monte Carlo calculated correction factors for diodes and ion chambers in small photon fields Phys. Med. Biol. 58 2431-44 Mairani A, Böhlen T T, Schiavi A, Tessonnier T, Molinelli S, Brons S, Battistoni G, Parodi K and Patera V 2013 A Monte Carlo-based treatment planning tool for proton therapy Phys. Med. Biol. 58 2471-90 Marcatili S, Pettinato C, Daniels S, Lewis G, Edwards P, Fanti S and Spezi E 2013 Development and validation of RAYDOSE: a Geant4 based application for molecular radiotherapy Phys. Med. Biol. 58 2491-508 Miras H, Jiménez R, Miras C and Gomà C 2013 CloudMC: A cloud computing application for Monte Carlo simulation Phys. Med. Biol. 58 N125-33 Reynaert N 2007 First European Workshop on Monte Carlo Treatment Planning J. Phys.: Conf. Ser. 74 011001 Seuntjens J, Beaulieu L, El Naqa I and Després P 2012 Special section: Selected papers from the Fourth International Workshop on Recent Advances in Monte Carlo Techniques for Radiation Therapy Phys. Med. Biol. 57 (11) E01 Spezi E 2010 Special section: Selected papers from the Second European Workshop on Monte Carlo Treatment Planning (MCTP2009) Phys. Med. Biol. 55 (16) E01 Wagner A, Crop F, Lacornerie T, Vandevelde F and Reynaert N 2013 Use of a liquid ionization chamber for stereotactic radiotherapy dosimetry Phys. Med. Biol. 58 2445-59

An image-based skeletal dosimetry model for the ICRP reference newborn—internal electron sources

NASA Astrophysics Data System (ADS)

Pafundi, Deanna; Rajon, Didier; Jokisch, Derek; Lee, Choonsik; Bolch, Wesley

2010-04-01

In this study, a comprehensive electron dosimetry model of newborn skeletal tissues is presented. The model is constructed using the University of Florida newborn hybrid phantom of Lee et al (2007 Phys. Med. Biol. 52 3309-33), the newborn skeletal tissue model of Pafundi et al (2009 Phys. Med. Biol. 54 4497-531) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow (surrogate tissue for hematopoietic stem cells), shallow marrow (surrogate tissue for osteoprogenitor cells) and unossified cartilage (surrogate tissue for chondrocytes). Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following source tissues: active marrow, trabecular bone (surfaces and volumes), cortical bone (surfaces and volumes) and cartilage. Transport results are reported as specific absorbed fractions according to the MIRD schema and are given as skeletal-averaged values in the paper with bone-specific values reported in both tabular and graphic format as electronic annexes (supplementary data). The method utilized in this work uniquely includes (1) explicit accounting for the finite size and shape of newborn ossification centers (spongiosa regions), (2) explicit accounting for active and shallow marrow dose from electron emissions in cortical bone as well as sites of unossified cartilage, (3) proper accounting of the distribution of trabecular and cortical volumes and surfaces in the newborn skeleton when considering mineral bone sources and (4) explicit consideration of the marrow cellularity changes for active marrow self-irradiation as applicable to radionuclide therapy of diseased marrow in the newborn child.

Report of improved performance in Talbot–Lau phase-contrast computed tomography

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

Weber, Thomas, E-mail: thomas.weber@fau.de; Pelzer, Georg; Rieger, Jens

Purpose: Many expectations have been raised since the use of conventional x-ray tubes on grating-based x-ray phase-contrast imaging. Despite a reported increase in contrast-to-noise ratio (CNR) in many publications, there is doubt on whether phase-contrast computed tomography (CT) is advantageous in clinical CT scanners in vivo. The aim of this paper is to contribute to this discussion by analyzing the performance of a phase-contrast CT laboratory setup. Methods: A phase-contrast CT performance analysis was done. Projection images of a phantom were recorded, and image slices were reconstructed using standard filtered back projection methods. The resulting image slices were analyzed bymore » determining the CNRs in the attenuation and phase image. These results were compared to analytically calculated expectations according to the already published phase-contrast CT performance analysis by Raupach and Flohr [Med. Phys. 39, 4761–4774 (2012)]. There, a severe mistake was found leading to wrong predictions of the performance of phase-contrast CT. The error was corrected and with the new formulae, the experimentally obtained results matched the analytical calculations. Results: The squared ratios of the phase-contrast CNR and the attenuation CNR obtained in the authors’ experiment are five- to ten-fold higher than predicted by Raupach and Flohr [Med. Phys. 39, 4761–4774 (2012)]. The effective lateral spatial coherence length deduced outnumbers the already optimistic assumption of Raupach and Flohr [Med. Phys. 39, 4761–4774 (2012)] by a factor of 3. Conclusions: The authors’ results indicate that the assumptions made in former performance analyses are pessimistic. The break-even point, when phase-contrast CT outperforms attenuation CT, is within reach even with realistic, nonperfect gratings. Further improvements to state-of-the-art clinical CT scanners, like increasing the spatial resolution, could change the balance in favor of phase-contrast computed tomography even more. This could be done by, e.g., quantum-counting pixel detectors with four-fold smaller pixel pitches.« less

Reply to Comment: 'A novel method for fast and robust estimation of fluorescence decay dynamics using constrained least-square deconvolution with Laguerre expansion'.

PubMed

Ma, Dinglong; Liu, Jing; Qi, Jinyi; Marcu, Laura

2017-02-21

In this response we underscore that the instrumentation described in the original publication (Liu et al 2012 Phys. Med. Biol. 57 843-65) was based on pulse-sampling technique, while the comment by Zhang et al is based on the assumption that a time-correlated single photon counting (TCSPC) instrumentation was used. Therefore the arguments made in the comment are not applicable to the noise model reported by Liu et al. As reported in the literature (Lakowicz 2006 Principles of Fluorescence Spectroscopy (New York: Springer)), while in the TCSPC the experimental noise can be estimated from Poisson statistics, such an assumption is not valid for pulse-sampling (transient recording) techniques. To further clarify this aspect, we present here a comprehensive noise model describing the signal and noise propagation of the pulse sampling time-resolved fluorescence detection. Experimental data recorded in various conditions are analyzed as a case study to demonstrate the noise model of our instrumental system. In addition, regarding the statement of correcting equation (3) in Liu et al (2012 Phys. Med. Biol. 57 843-65), the notation of discrete time Laguerre function in the original publication was clear and consistent with literature conventions (Marmarelis 1993 Ann. Biomed. Eng. 21 573-89, Westwick and Kearney 2003 Identification of Nonlinear Physiological Systems (Hoboken, NJ: Wiley)). Thus, it does not require revision.

Experimental derivation of the fluence non-uniformity correction for air kerma near brachytherapy linear sources

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

Vianello, E. A.; Almeida, C. E. de

2008-07-15

In brachytherapy, one of the elements to take into account for measurements free in air is the non-uniformity of the photon fluence due to the beam divergence that causes a steep dose gradient near the source. The correction factors for this phenomenon have been usually evaluated by two available theories by Kondo and Randolph [Radiat. Res. 13, 37-60 (1960)] and Bielajew [Phys. Med. Biol. 35, 517-538 (1990)], both conceived for point sources. This work presents the experimental validation of the Monte Carlo calculations made by Rodriguez and deAlmeida [Phys. Med. Biol. 49, 1705-1709 (2004)] for the non-uniformity correction specifically formore » a Cs-137 linear source measured using a Farmer type ionization chamber. The experimental values agree very well with the Monte Carlo calculations and differ from the results predicted by both theoretical models widely used. This result confirms that for linear sources there are some important differences at short distances from the source and emphasizes that those theories should not be used for linear sources. The data provided in this study confirm the limitations of the mentioned theories when linear sources are used. Considering the difficulties and uncertainties associated with the experimental measurements, it is recommended to use the Monte Carlo data to assess the non-uniformity factors for linear sources in situations that require this knowledge.« less

Reply to Comment: ‘A novel method for fast and robust estimation of fluorescence decay dynamics using constrained least-square deconvolution with Laguerre expansion’

NASA Astrophysics Data System (ADS)

Ma, Dinglong; Liu, Jing; Qi, Jinyi; Marcu, Laura

2017-02-01

In this response we underscore that the instrumentation described in the original publication (Liu et al 2012 Phys. Med. Biol. 57 843-65) was based on pulse-sampling technique, while the comment by Zhang et al is based on the assumption that a time-correlated single photon counting (TCSPC) instrumentation was used. Therefore the arguments made in the comment are not applicable to the noise model reported by Liu et al. As reported in the literature (Lakowicz 2006 Principles of Fluorescence Spectroscopy (New York: Springer)), while in the TCSPC the experimental noise can be estimated from Poisson statistics, such an assumption is not valid for pulse-sampling (transient recording) techniques. To further clarify this aspect, we present here a comprehensive noise model describing the signal and noise propagation of the pulse sampling time-resolved fluorescence detection. Experimental data recorded in various conditions are analyzed as a case study to demonstrate the noise model of our instrumental system. In addition, regarding the statement of correcting equation (3) in Liu et al (2012 Phys. Med. Biol. 57 843-65), the notation of discrete time Laguerre function in the original publication was clear and consistent with literature conventions (Marmarelis 1993 Ann. Biomed. Eng. 21 573-89, Westwick and Kearney 2003 Identification of Nonlinear Physiological Systems (Hoboken, NJ: Wiley)). Thus, it does not require revision.

Simulations to Evaluate Accuracy and Patient Dose in Neutron-Stimulated, Emission-Computed Tomography (NSECT) for Diagnosis of Breast Cancer

DTIC Science & Technology

2009-04-01

table 1 and includes all of the excited state transitions that are included in the BNL database. In this study we considered only states that could be...16Cross Section Evaluation Working Group, ENDEIB-VI Summary Docu- mentation, Report BNL -NCS-17541 ENDF-201, edited by P. F. Rose, National Nuclear Data...Med. Phys., vol. 34, pp. 3866–3871, 2007. [37] National Nuclear Data Center BNL , NuDat 2.3 2007. [38] A. J. Kapadia and C. E. Floyd, “An attenuation

Comment on 'Imaging of prompt gamma rays emitted during delivery of clinical proton beams with a Compton camera: feasibility studies for range verification'.

PubMed

Sitek, Arkadiusz

2016-12-21

The origin ensemble (OE) algorithm is a new method used for image reconstruction from nuclear tomographic data. The main advantage of this algorithm is the ease of implementation for complex tomographic models and the sound statistical theory. In this comment, the author provides the basics of the statistical interpretation of OE and gives suggestions for the improvement of the algorithm in the application to prompt gamma imaging as described in Polf et al (2015 Phys. Med. Biol. 60 7085).

Comment on ‘Imaging of prompt gamma rays emitted during delivery of clinical proton beams with a Compton camera: feasibility studies for range verification’

NASA Astrophysics Data System (ADS)

Sitek, Arkadiusz

2016-12-01

The origin ensemble (OE) algorithm is a new method used for image reconstruction from nuclear tomographic data. The main advantage of this algorithm is the ease of implementation for complex tomographic models and the sound statistical theory. In this comment, the author provides the basics of the statistical interpretation of OE and gives suggestions for the improvement of the algorithm in the application to prompt gamma imaging as described in Polf et al (2015 Phys. Med. Biol. 60 7085).

Automation and Preclinical Evaluation of a Dedicated Emission Mammotomography System for Fully 3-D Molecular Breast Imaging

DTIC Science & Technology

2008-10-01

concentrated aqueous 99m Tc and taped to the exterior surface of the breast phantom to act as fiducial markers for registration purposes. Two...34 Physica Medica, vol. 21, pp. 48-55, 2006. [16] H. Erdogan and J. A. Fessler, "Ordered subsets algorithms for transmission tomography," Phys Med Biol

New horizons in Biophysics

PubMed Central

2011-01-01

This editorial celebrates the re-launch of PMC Biophysics previously published by PhysMath Central, in its new format as BMC Biophysics published by BioMed Central with an expanded scope and Editorial Board. BMC Biophysics will fill its own niche in the BMC series alongside complementary companion journals including BMC Bioinformatics, BMC Medical Physics, BMC Structural Biology and BMC Systems Biology. PMID:21595996

Advanced Restoration Therapies in Spinal Cord Injury

DTIC Science & Technology

2016-05-01

project. In addition, Dr. Belegu has performed SCI surgeries , electrode implantations, FES stimulation, and neurological assays. Name: Ali...month worked: 10.2 Contribution to Project: Dr. Liu has assisted Dr. Belegu in performing SCI surgeries , electrode implantation. In addition, she...training-based rehabilitation. Arch Phys Med Rehabil 93, 1508-1517. Karimi, M.T. (2013). Robotic rehabilitation of spinal cord injury individual

LETTER TO THE EDITOR: Comments on 'The influence of a novel transmission detector on 6 MV x-ray beam characteristics'

NASA Astrophysics Data System (ADS)

Harder, Dietrich

2010-02-01

In their recent paper (Venkataraman et al 2009 Phys. Med. Biol. 54 3173-83) the authors reported on photon beam attenuation and secondary electron production in the novel transmission detector COMPASS, to be placed in the accessory holder of the linac treatment head. In the interest of IMRT patient safety, space-resolved measurements by transmission detectors analysing the MLC-shaped photon fluence pattern in real time are in fact an urgent item for equipment designers. However, there are some constraints for the construction of such devices. The COMPASS system, at its present stage of development, has difficulties in complying with the constraints that the spatial sampling rate should fit the desired task and that the enhanced secondary electron contamination of the photon beam due to the presence of the device should be minimized. The authors also missed to mention a forerunner in this field, the DAVID transmission detector (Poppe et al 2006 Phys. Med. Biol. 51 1237-48), serving for the real-time supervision of the MLC aperture during patient treatment and ever since proven in clinical practice. The DAVID system, a transparent multiwire ionization chamber placed in the accessory holder, will be shortly described.

Mw Systematic Study of Alkaloids: the Distorted Tropane of Scopoline

NASA Astrophysics Data System (ADS)

Ecija, Patricia; Cocinero, Emilio J.; Basterretxea, Francisco J.; Fernandez, Jose A.; Castano, Fernando; Lesarri, Alberto

2013-06-01

Tropane alkaloids have diverse pharmacological uses and are well-known for their neurostimulant activity. Previous structure-activity-relationship established correlations between bioactivity and several aspects of ligand conformation and stereochemistry, including delicate intramolecular effects like nitrogen inversion^{a}. We have initiated a series of structural studies on tropane alkaloids^{b}, aimed to discerning their intrinsic stereochemical properties using rotational spectroscopy in supersonic jets^{c}. Here we extend these studies to the epoxytropanes, initially motivated to interrogate the influence of the epoxy group on nitrogen inversion and ring conformation. The rotational spectrum evidences a single structure in the gas phase, providing a first description of the (three ring) structurally-distorted tropane in scopoline. The determined rotational parameters of scopoline reveal the structural consequences of the intramolecular cyclation of scopine, which breaks the original epoxy group and creates a new ether bridge and a 7β-hydroxytropane configuration. The hydroxyl group further stabilizes the molecule by an O-H \\cdots N intramolecular hydrogen bond, which, in turn, forces the N-methyl group to the less stable axial form^{b}. The experimental work was supported by ab initio and DFT calculations. ^{a} i) S.Singh, Chem. Rev. 100, 925 (2000); ii) A. Krunic, D. Pan, W.J. Dunn III, S.V.S. Miariappan, Bioorg. & Med. Chem. 17, 811 (2009). ^{b} E.J. Cocinero, A. Lesarri, P. écija, J.-U. Grabow, J.A. Fernández, F. Castaño, Phys. Chem. Chem. Phys. 12, 6076 (2010). ^{c} E.J. Cocinero, A. Lesarri, P. écija, J.-U. Grabow, J.A. Fernández, F. Castaño, Phys. Chem. Chem. Phys. 12, 12486 (2010).

An experimental palladium-103 seed (OptiSeedexp) in a biocompatible polymer without a gold marker: characterization of dosimetric parameters including the interseed effect.

PubMed

Abboud, F; Scalliet, P; Vynckier, S

2008-12-01

Permanent implantation of 125I (iodine) or 103Pd (palladium) sources is a popular treatment option in the management of early stage prostate cancer. New sources are being developed, some of which are being marketed for different clinical applications. A new technique of adjuvant stereotactic permanent seed breast implant, similar to that used in the treatment of prostate cancer, has been proposed by [N. Jansen et al., Int. J. Radiat. Oncol. Biol. Phys. 67, 1052-1058 (2007)] with encouraging results. The presence of artifacts from the metallic seeds, however, can disturb follow-up imaging. The development of plastic seeds has reduced these artifacts. This paper presents a feasibility study of the advantages of palladium-103 seeds, encapsulated with a biocompatible polymer, for future clinical applications, and on the effect of the gold marker on the dosimetric characteristics of such seeds. Experimental palladium seeds, OptiSeedexp, were manufactured by International Brachytherapy (IBt), Seneffe, Belgium, from a biocompatible polymer, including the marker. Apart from the absence of a gold marker, the studied seed has an identical design to the OptiSeed103 [Phys. Med. Biol. 50, 1493-1504 (2005)]; [Appl. Radiat. Isot. 63, 311-321 (2005)]. Polymer encapsulation was preferred by IBt in order to reduce the quantity of radioactive material needed for a given dose rate and to reduce the anisotropy of the radiation field around the seed. In addition, this design is intended to decrease the interseed effects that can occur as a result of the marker and the encapsulation. Dosimetric measurements were performed using LiF thermoluminescent dosimeters (1 mm3) in solid water phantoms (WT1). Measured data were compared to Monte Carlo simulated data in solid water using the MCNP code, version 4C. Updated cross sections [Med. Phys. 30, 701-711 (2003)] were used. As the measured and calculated data were in agreement, Monte Carlo calculations were then performed in liquid water to obtain relevant dosimetric data as required by TG-43U1 recommendations. Comparison of the results with previous studies of OptiSeed103 [Phys. Med. Biol. 50, 1493-1504 (2005)]; [Appl. Radiat. Isot. 63, 311-321 (2005)], and of InterSource103 [Appl. Radiat. Isot. 57, 805-811 (2002)] showed very good agreement for the dose rate constant and for the radial dose function. With respect to the anisotropy function, the relative dose (anisotropy value relative to 90 degrees) from the polymer seed at a distance of 3 cm was close to unity (105%) at 0 degrees, whereas the relative values for the OptiSeed103 with a gold marker and the titanium-encapsulated InterSource103 seed decreased to 70% and 40%, respectively. The interseed effect from one seed was negligible and in the order of calculation uncertainty, making calculation of the dose rate distribution of the studied seeds, according to TG43U1 recommendations, more accurate and closer to reality. This feasibility study shows that due to the low energy of palladium-103, the negligible interseed effect and the reduced artifacts in postimplant medical imaging, this experimental plastic seed would be a good source for breast brachytherapy. This feasibility study was carried out in collaboration with IBt and will be continued with a study of its visibility in different tissues.

An experimental palladium-103 seed (OptiSeed{sup exp}) in a biocompatible polymer without a gold marker: Characterization of dosimetric parameters including the interseed effect

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

Abboud, F.; Scalliet, P.; Vynckier, S.

Permanent implantation of {sup 125}I (iodine) or {sup 103}Pd (palladium) sources is a popular treatment option in the management of early stage prostate cancer. New sources are being developed, some of which are being marketed for different clinical applications. A new technique of adjuvant stereotactic permanent seed breast implant, similar to that used in the treatment of prostate cancer, has been proposed by [N. Jansen et al., Int. J. Radiat. Oncol. Biol. Phys. 67, 1052-1058 (2007)] with encouraging results. The presence of artifacts from the metallic seeds, however, can disturb follow-up imaging. The development of plastic seeds has reduced thesemore » artifacts. This paper presents a feasibility study of the advantages of palladium-103 seeds, encapsulated with a biocompatible polymer, for future clinical applications, and on the effect of the gold marker on the dosimetric characteristics of such seeds. Experimental palladium seeds, OptiSeed{sup exp}, were manufactured by International Brachytherapy (IBt), Seneffe, Belgium, from a biocompatible polymer, including the marker. Apart from the absence of a gold marker, the studied seed has an identical design to the OptiSeed{sup 103}[Phys. Med. Biol. 50, 1493-1504 (2005)]; [Appl. Radiat. Isot. 63, 311-321 (2005)]. Polymer encapsulation was preferred by IBt in order to reduce the quantity of radioactive material needed for a given dose rate and to reduce the anisotropy of the radiation field around the seed. In addition, this design is intended to decrease the interseed effects that can occur as a result of the marker and the encapsulation. Dosimetric measurements were performed using LiF thermoluminescent dosimeters (1 mm{sup 3}) in solid water phantoms (WT1). Measured data were compared to Monte Carlo simulated data in solid water using the MCNP code, version 4C. Updated cross sections [Med. Phys. 30, 701-711 (2003)] were used. As the measured and calculated data were in agreement, Monte Carlo calculations were then performed in liquid water to obtain relevant dosimetric data as required by TG-43U1 recommendations. Comparison of the results with previous studies of OptiSeed{sup 103}[Phys. Med. Biol. 50, 1493-1504 (2005)]; [Appl. Radiat. Isot. 63, 311-321 (2005)], and of InterSource{sup 103}[Appl. Radiat. Isot. 57, 805-811 (2002)] showed very good agreement for the dose rate constant and for the radial dose function. With respect to the anisotropy function, the relative dose (anisotropy value relative to 90 degree sign ) from the polymer seed at a distance of 3 cm was close to unity (105%) at 0 degree sign , whereas the relative values for the OptiSeed{sup 103} with a gold marker and the titanium-encapsulated InterSource{sup 103} seed decreased to 70% and 40%, respectively. The interseed effect from one seed was negligible and in the order of calculation uncertainty, making calculation of the dose rate distribution of the studied seeds, according to TG43U1 recommendations, more accurate and closer to reality. This feasibility study shows that due to the low energy of palladium-103, the negligible interseed effect and the reduced artifacts in postimplant medical imaging, this experimental plastic seed would be a good source for breast brachytherapy. This feasibility study was carried out in collaboration with IBt and will be continued with a study of its visibility in different tissues.« less

Determination of absorbed dose to water around a clinical HDR {sup 192}Ir source using LiF:Mg,Ti TLDs demonstrates an LET dependence of detector response

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

Carlsson Tedgren, Aasa; Elia, Rouba; Hedtjaern, Haakan

2012-02-15

Purpose: Experimental radiation dosimetry with thermoluminescent dosimeters (TLDs), calibrated in a {sup 60}Co or megavoltage (MV) photon beam, is recommended by AAPM TG-43U1for verification of Monte Carlo calculated absorbed doses around brachytherapy sources. However, it has been shown by Carlsson Tedgren et al.[Med. Phys. 38, 5539-5550 (2011)] that for TLDs of LiF:Mg,Ti, detector response was 4% higher in a {sup 137}Cs beam than in a {sup 60}Co one. The aim of this work was to investigate if similar over-response exists when measuring absorbed dose to water around {sup 192}Ir sources, using LiF:Mg,Ti dosimeters calibrated in a 6 MV photon beam.more » Methods: LiF dosimeters were calibrated to measure absorbed dose to water in a 6 MV photon beam and used to measure absorbed dose to water at distances of 3, 5, and 7 cm from a clinical high dose rate (HDR) {sup 192}Ir source in a polymethylmethacrylate (PMMA) phantom. Measured values were compared to values of absorbed dose to water calculated using a treatment planning system (TPS) including corrections for the difference in energy absorption properties between calibration quality and the quality in the users'{sup 192}Ir beam and for the use of a PMMA phantom instead of the water phantom underlying dose calculations in the TPS. Results: Measured absorbed doses to water around the {sup 192}Ir source were overestimated by 5% compared to those calculated by the TPS. Corresponding absorbed doses to water measured in a previous work with lithium formate electron paramagnetic resonance (EPR) dosimeters by Antonovic et al. [Med. Phys. 36, 2236-2247 (2009)], using the same irradiation setup and calibration procedure as in this work, were 2% lower than those calculated by the TPS. The results obtained in the measurements in this work and those obtained using the EPR lithium formate dosimeters were, within the expanded (k = 2) uncertainty, in agreement with the values derived by the TPS. The discrepancy between the results using LiF:Mg,Ti TLDs and the EPR lithium formate dosimeters was, however, statistically significant and in agreement with the difference in relative detector responses found for the two detector systems by Carlsson Tedgren et al. [Med. Phys. 38, 5539-5550 (2011)] and by Adolfsson et al.[Med. Phys. 37, 4946-4959 (2010)]. Conclusions: When calibrated in {sup 60}Co or MV photon beams, correction for the linear energy transfer (LET) dependence of LiF:Mg,Ti detector response will be needed as to measure absorbed doses to water in a {sup 192}Ir beam with highest accuracy. Such corrections will depend on the manufacturing process (MTS-N Poland or Harshaw TLD-100) and details of the annealing and read-out schemes used.« less

Determination of absorbed dose to water around a clinical HDR (192)Ir source using LiF:Mg,Ti TLDs demonstrates an LET dependence of detector response.

PubMed

Carlsson Tedgren, Asa; Elia, Rouba; Hedtjarn, Hakan; Olsson, Sara; Alm Carlsson, Gudrun

2012-02-01

Experimental radiation dosimetry with thermoluminescent dosimeters (TLDs), calibrated in a (60)Co or megavoltage (MV) photon beam, is recommended by AAPM TG-43U1for verification of Monte Carlo calculated absorbed doses around brachytherapy sources. However, it has been shown by Carlsson Tedgren et al. [Med. Phys. 38, 5539-5550 (2011)] that for TLDs of LiF:Mg,Ti, detector response was 4% higher in a (137)Cs beam than in a (60)Co one. The aim of this work was to investigate if similar over-response exists when measuring absorbed dose to water around (192)Ir sources, using LiF:Mg,Ti dosimeters calibrated in a 6 MV photon beam. LiF dosimeters were calibrated to measure absorbed dose to water in a 6 MV photon beam and used to measure absorbed dose to water at distances of 3, 5, and 7 cm from a clinical high dose rate (HDR) (192)Ir source in a polymethylmethacrylate (PMMA) phantom. Measured values were compared to values of absorbed dose to water calculated using a treatment planning system (TPS) including corrections for the difference in energy absorption properties between calibration quality and the quality in the users' (192)Ir beam and for the use of a PMMA phantom instead of the water phantom underlying dose calculations in the TPS. Measured absorbed doses to water around the (192)Ir source were overestimated by 5% compared to those calculated by the TPS. Corresponding absorbed doses to water measured in a previous work with lithium formate electron paramagnetic resonance (EPR) dosimeters by Antonovic et al. [Med. Phys. 36, 2236-2247 (2009)], using the same irradiation setup and calibration procedure as in this work, were 2% lower than those calculated by the TPS. The results obtained in the measurements in this work and those obtained using the EPR lithium formate dosimeters were, within the expanded (k = 2) uncertainty, in agreement with the values derived by the TPS. The discrepancy between the results using LiF:Mg,Ti TLDs and the EPR lithium formate dosimeters was, however, statistically significant and in agreement with the difference in relative detector responses found for the two detector systems by Carlsson Tedgren et al. [Med. Phys. 38, 5539-5550 (2011)] and by Adolfsson et al. [Med. Phys. 37, 4946-4959 (2010)]. When calibrated in (60)Co or MV photon beams, correction for the linear energy transfer (LET) dependence of LiF:Mg,Ti detector response will be needed as to measure absorbed doses to water in a (192)Ir beam with highest accuracy. Such corrections will depend on the manufacturing process (MTS-N Poland or Harshaw TLD-100) and details of the annealing and read-out schemes used.

A parameterization method and application in breast tomosynthesis dosimetry

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

Li, Xinhua; Zhang, Da; Liu, Bob

2013-09-15

Purpose: To present a parameterization method based on singular value decomposition (SVD), and to provide analytical parameterization of the mean glandular dose (MGD) conversion factors from eight references for evaluating breast tomosynthesis dose in the Mammography Quality Standards Act (MQSA) protocol and in the UK, European, and IAEA dosimetry protocols.Methods: MGD conversion factor is usually listed in lookup tables for the factors such as beam quality, breast thickness, breast glandularity, and projection angle. The authors analyzed multiple sets of MGD conversion factors from the Hologic Selenia Dimensions quality control manual and seven previous papers. Each data set was parameterized usingmore » a one- to three-dimensional polynomial function of 2–16 terms. Variable substitution was used to improve accuracy. A least-squares fit was conducted using the SVD.Results: The differences between the originally tabulated MGD conversion factors and the results computed using the parameterization algorithms were (a) 0.08%–0.18% on average and 1.31% maximum for the Selenia Dimensions quality control manual, (b) 0.09%–0.66% on average and 2.97% maximum for the published data by Dance et al. [Phys. Med. Biol. 35, 1211–1219 (1990); ibid. 45, 3225–3240 (2000); ibid. 54, 4361–4372 (2009); ibid. 56, 453–471 (2011)], (c) 0.74%–0.99% on average and 3.94% maximum for the published data by Sechopoulos et al. [Med. Phys. 34, 221–232 (2007); J. Appl. Clin. Med. Phys. 9, 161–171 (2008)], and (d) 0.66%–1.33% on average and 2.72% maximum for the published data by Feng and Sechopoulos [Radiology 263, 35–42 (2012)], excluding one sample in (d) that does not follow the trends in the published data table.Conclusions: A flexible parameterization method is presented in this paper, and was applied to breast tomosynthesis dosimetry. The resultant data offer easy and accurate computations of MGD conversion factors for evaluating mean glandular breast dose in the MQSA protocol and in the UK, European, and IAEA dosimetry protocols. Microsoft Excel™ spreadsheets are provided for the convenience of readers.« less

SU-F-I-34: How Does Longitudinal Dose Profile Change with Tube Current Distribution in CT?

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

Li, X; Yang, K; Liu, B

Purpose: To investigate how longitudinal dose profile D{sub L}(z) in 30 cm-diameter water cylinder change with tube current (mA) distribution and scan length. Methods: A constant and four variable mA distributions from two previous papers [Dixon et al., Med. Phys. 40, 111920 (14pp.) (2013); Zhang et al., Med. Phys. 41, 091911 (9pp.) (2014)] were adopted in three scan lengths of 10, 28.6, and 50 cm, and all mA distributions had the same average mA over scan ranges. Using the symmetry based dose calculation algorithms and the previously published CT dose equilibration data [Li et al., Med. Phys. 40, 031903 (10pp.)more » (2013); 41, 111910 (5pp.) (2014)], the authors calculated DL(z) on the phantom central and peripheral axes. Kolmogorov-Smirnov (K-S) test was used to compare the lineshapes of two arbitrary distributions. Results: In constant mA scans, D{sub L}(z) was “bell-shaped”. In variable mA scans, D{sub L}(z) approximately followed the mA lineshape, and the K-S distance generally changed with mA distribution. The distance decreased with scan length, and was larger on the central axis than on the peripheral axis. However, the opposite trends were found in the K-S distance between the D{sub L}(z) distributions of constant and variable mA distributions. Conclusion: Radiation dose from TCM scan is best evaluated using the specific tube current distribution. A constant mA based evaluation may lead to inconsistent longitudinal dose profile with that of TCM scan. Their difference in lineshape is larger on the phantom peripheral axis than on the central axis and increases with scan length. This work confirms that radiation dose in CT depends on not only local mA but also the overall mA distribution and scan length. On the other hand, the concept of regional tube current may be useful when scan length is large, tube current peaks near scan range edge, or the target site is superficial.« less

The IPEM code of practice for determination of the reference air kerma rate for HDR 192Ir brachytherapy sources based on the NPL air kerma standard

NASA Astrophysics Data System (ADS)

Bidmead, A. M.; Sander, T.; Locks, S. M.; Lee, C. D.; Aird, E. G. A.; Nutbrown, R. F.; Flynn, A.

2010-06-01

This paper contains the recommendations of the high dose rate (HDR) brachytherapy working party of the UK Institute of Physics and Engineering in Medicine (IPEM). The recommendations consist of a Code of Practice (COP) for the UK for measuring the reference air kerma rate (RAKR) of HDR 192Ir brachytherapy sources. In 2004, the National Physical Laboratory (NPL) commissioned a primary standard for the realization of RAKR of HDR 192Ir brachytherapy sources. This has meant that it is now possible to calibrate ionization chambers directly traceable to an air kerma standard using an 192Ir source (Sander and Nutbrown 2006 NPL Report DQL-RD 004 (Teddington: NPL) http://publications.npl.co.uk). In order to use the source specification in terms of either RAKR, \\dot K_R (ICRU 1985 ICRU Report No 38 (Washington, DC: ICRU); ICRU 1997 ICRU Report No 58 (Bethesda, MD: ICRU)), or air kerma strength, SK (Nath et al 1995 Med. Phys. 22 209-34), it has been necessary to develop algorithms that can calculate the dose at any point around brachytherapy sources within the patient tissues. The AAPM TG-43 protocol (Nath et al 1995 Med. Phys. 22 209-34) and the 2004 update TG-43U1 (Rivard et al 2004 Med. Phys. 31 633-74) have been developed more fully than any other protocol and are widely used in commercial treatment planning systems. Since the TG-43 formalism uses the quantity air kerma strength, whereas this COP uses RAKR, a unit conversion from RAKR to air kerma strength was included in the appendix to this COP. It is recommended that the measured RAKR determined with a calibrated well chamber traceable to the NPL 192Ir primary standard is used in the treatment planning system. The measurement uncertainty in the source calibration based on the system described in this COP has been reduced considerably compared to other methods based on interpolation techniques.

Health-Related Fitness in the Royal Netherlands Army

DTIC Science & Technology

2009-10-01

autologous platelet - rich plasma application in traumatic tendon injuries, [7] and collagen hydrolysate in joint pain [8]. 3.0 LIFESTYLE-RELATED HEALTH...randomized controlled trial. Arch Phys Med Rehabil 2008;89:1675-85. [7] Mos de M, Windt van der AE, Jahr H, et al. Can platelet - rich plasma enhance tendon...devices (leg press, chest press, shoulder press, vertical traction) and cardio-stepper (progressive protocol), according to gender- and age- specific

MR Imaging Based Treatment Planning for Radiotherapy of Prostate Cancer

DTIC Science & Technology

2007-02-01

developed practical methods for heterogeneity correction for MRI - based dose calculations (Chen et al 2007). 6) We will use existing Monte Carlo ... Monte Carlo verification of IMRT dose distributions from a commercial treatment planning optimization system, Phys. Med. Biol., 45:2483-95 (2000) Ma...accuracy and consistency for MR based IMRT treatment planning for prostate cancer. A short paper entitled “ Monte Carlo dose verification of MR image based

Intercomparison of methods for image quality characterization. II. Noise power spectrum

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

Dobbins, James T. III; Samei, Ehsan; Ranger, Nicole T.

Second in a two-part series comparing measurement techniques for the assessment of basic image quality metrics in digital radiography, in this paper we focus on the measurement of the image noise power spectrum (NPS). Three methods were considered: (1) a method published by Dobbins et al. [Med. Phys. 22, 1581-1593 (1995)] (2) a method published by Samei et al. [Med. Phys. 30, 608-622 (2003)], and (3) a new method sanctioned by the International Electrotechnical Commission (IEC 62220-1, 2003), developed as part of an international standard for the measurement of detective quantum efficiency. In addition to an overall comparison of themore » estimated NPS between the three techniques, the following factors were also evaluated for their effect on the measured NPS: horizontal versus vertical directional dependence, the use of beam-limiting apertures, beam spectrum, and computational methods of NPS analysis, including the region-of-interest (ROI) size and the method of ROI normalization. Of these factors, none was found to demonstrate a substantial impact on the amplitude of the NPS estimates ({<=}3.1% relative difference in NPS averaged over frequency, for each factor considered separately). Overall, the three methods agreed to within 1.6%{+-}0.8% when averaged over frequencies >0.15 mm{sup -1}.« less

NOTE: Fluoroscopic gating without implanted fiducial markers for lung cancer radiotherapy based on support vector machines

NASA Astrophysics Data System (ADS)

Cui, Ying; Dy, Jennifer G.; Alexander, Brian; Jiang, Steve B.

2008-08-01

Various problems with the current state-of-the-art techniques for gated radiotherapy have prevented this new treatment modality from being widely implemented in clinical routine. These problems are caused mainly by applying various external respiratory surrogates. There might be large uncertainties in deriving the tumor position from external respiratory surrogates. While tracking implanted fiducial markers has sufficient accuracy, this procedure may not be widely accepted due to the risk of pneumothorax. Previously, we have developed a technique to generate gating signals from fluoroscopic images without implanted fiducial markers using template matching methods (Berbeco et al 2005 Phys. Med. Biol. 50 4481-90, Cui et al 2007b Phys. Med. Biol. 52 741-55). In this note, our main contribution is to provide a totally different new view of the gating problem by recasting it as a classification problem. Then, we solve this classification problem by a well-studied powerful classification method called a support vector machine (SVM). Note that the goal of an automated gating tool is to decide when to turn the beam ON or OFF. We treat ON and OFF as the two classes in our classification problem. We create our labeled training data during the patient setup session by utilizing the reference gating signal, manually determined by a radiation oncologist. We then pre-process these labeled training images and build our SVM prediction model. During treatment delivery, fluoroscopic images are continuously acquired, pre-processed and sent as an input to the SVM. Finally, our SVM model will output the predicted labels as gating signals. We test the proposed technique on five sequences of fluoroscopic images from five lung cancer patients against the reference gating signal as ground truth. We compare the performance of the SVM to our previous template matching method (Cui et al 2007b Phys. Med. Biol. 52 741-55). We find that the SVM is slightly more accurate on average (1-3%) than the template matching method, when delivering the target dose. And the average duty cycle is 4-6% longer. Given the very limited patient dataset, we cannot conclude that the SVM is more accurate and efficient than the template matching method. However, our preliminary results show that the SVM is a potentially precise and efficient algorithm for generating gating signals for radiotherapy. This work demonstrates that the gating problem can be considered as a classification problem and solved accordingly.

Computer Simulation of Breast Cancer Screening

DTIC Science & Technology

2001-07-01

21. Tompkins PA, Abreu CC, Carroll FE, Xiao therapeutic medical physics. Med Phys 14. Gentry JR, DeWerd LA. TLD measure- QF, MacDonald CA. Use of...capillary op- 1996; 23:1997-2005. ments of in vivo mammographic expo- tics as a beam intensifier for a Compton 28. Hammerstein GR, Miller DW, White DR...cm), and was only poorly correlated thicker slices. with breast thickness (r2 0.159). The For comparison images and dosimetry , magnification factor

Image Based Biomarker of Breast Cancer Risk: Analysis of Risk Disparity Among Minority Populations

DTIC Science & Technology

2014-03-01

attenuation coefficient of calcium hydroxyapatite ; is a parameter controlling the contrast of MCs in synthetic images (0< ə); and is the linear...effect of acquisition parameters and quantum noise," Med Phys, 37, 1591-600 (2010). [13] M. J. Yaffe, J. M. Boone, N. Packard, O. Alonzo-Proulx, S. Y...the acquisition of individual mammograms, the use of linear transformations does not seem appropriate for mammogram registration. Non-linear

On-line Adaptive Radiation Treatment of Prostate Cancer

DTIC Science & Technology

2009-01-01

12]. For intensity modulated radiation therapy (IMRT) plans , the beamlet weight can be re-optimized on a daily basis to mini- mize the dose to the OAR...Thongphiew D, Wang Z, Mathayomchan B, Chankong V, Yoo S, et al. On-line re-optimization of prostate IMRT plans for adaptive radiation therapy . Phys Med Biol...time. The treatment planning method for VMAT however is not mature. We are developing a robust VMAT treatment planning method which incorporates

B-1 Systems Approach to Training. Simulation Technology Assessment Report (STAR)

DTIC Science & Technology

1975-07-01

Psychology in the Air Force, 1974. Creelman , J.A., Evaluation of Approach Training Procedures, U.S. Naval School of Aviation Med., Proj. No. NM001-109-107...training. 3.2 PHYSICAL VERSUS PSYCHOLOGICAL SIMULATION In the previous section, the term "physical simulation" was used to represent the case where... psychology that there is no "step function" threshold. Rather, detection capability plotted against phys- ical parameter strength results in an ogival

Addendum: Measurement of charged particle yields from PMMA irradiated by a 220 MeV/u 12C beam

NASA Astrophysics Data System (ADS)

Mattei, I.; Battistoni, G.; Collini, F.; De Lucia, E.; Durante, M.; Fiore, S.; La Tessa, C.; Mancini-Terracciano, C.; Marafini, M.; Mirabelli, R.; Muraro, S.; Paramatti, R.; Piersanti, L.; Rucinski, A.; Russomando, A.; Sarti, A.; Schuy, C.; Sciubba, A.; Solfaroli Camillocci, E.; Toppi, M.; Traini, G.; Valle, S. M.; Vanstalle, M.; Patera, V.

2017-11-01

In this paper we report the re-analysis of the data published in Piersanti et al (2014 Phys. Med. Biol. 59 1857) documenting the charged secondary particles production induced by the interaction of a 220 MeV/u 12C ion beam impinging on a polymethyl methacrylate (PMMA) target, measured in 2012 at the GSI facility in Darmstadt (Germany). This re-analysis takes into account the inhomogeneous light response of the LYSO crystal in the experimental setup measured in a subsequent experiment (2014) performed in the Heidelberg Ion-Beam Therapy Center. A better description of the detector and re-calculation of the geometrical efficiencies have been implemented as well, based on an improved approach that accounts also for the energy dependence of the emission spectrum. The new analysis has little effect on the total secondary charged flux, but has an impact on the production yield and emission velocity distributions of the different particle species (protons, deuterons and tritons) at different angles with respect to the beam direction (60^\\circ and 90^\\circ ). All these observables indeed depend on the particle identification algorithms and hence on the LYSO detector energy response. The results of the data re-analysis presented here are intended to supersede and replace the results published in Piersanti et al (2014 Phys. Med. Biol. 59 1857).

Auto calibration of a cone-beam-CT

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

Gross, Daniel; Heil, Ulrich; Schulze, Ralf

2012-10-15

Purpose: This paper introduces a novel autocalibration method for cone-beam-CTs (CBCT) or flat-panel CTs, assuming a perfect rotation. The method is based on ellipse-fitting. Autocalibration refers to accurate recovery of the geometric alignment of a CBCT device from projection images alone, without any manual measurements. Methods: The authors use test objects containing small arbitrarily positioned radio-opaque markers. No information regarding the relative positions of the markers is used. In practice, the authors use three to eight metal ball bearings (diameter of 1 mm), e.g., positioned roughly in a vertical line such that their projection image curves on the detector preferablymore » form large ellipses over the circular orbit. From this ellipse-to-curve mapping and also from its inversion the authors derive an explicit formula. Nonlinear optimization based on this mapping enables them to determine the six relevant parameters of the system up to the device rotation angle, which is sufficient to define the geometry of a CBCT-machine assuming a perfect rotational movement. These parameters also include out-of-plane rotations. The authors evaluate their method by simulation based on data used in two similar approaches [L. Smekal, M. Kachelriess, S. E, and K. Wa, 'Geometric misalignment and calibration in cone-beam tomography,' Med. Phys. 31(12), 3242-3266 (2004); K. Yang, A. L. C. Kwan, D. F. Miller, and J. M. Boone, 'A geometric calibration method for cone beam CT systems,' Med. Phys. 33(6), 1695-1706 (2006)]. This allows a direct comparison of accuracy. Furthermore, the authors present real-world 3D reconstructions of a dry human spine segment and an electronic device. The reconstructions were computed from projections taken with a commercial dental CBCT device having two different focus-to-detector distances that were both calibrated with their method. The authors compare their reconstruction with a reconstruction computed by the manufacturer of the CBCT device to demonstrate the achievable spatial resolution of their calibration procedure. Results: Compared to the results published in the most closely related work [K. Yang, A. L. C. Kwan, D. F. Miller, and J. M. Boone, 'A geometric calibration method for cone beam CT systems,' Med. Phys. 33(6), 1695-1706 (2006)], the simulation proved the greater accuracy of their method, as well as a lower standard deviation of roughly 1 order of magnitude. When compared to another similar approach [L. Smekal, M. Kachelriess, S. E, and K. Wa, 'Geometric misalignment and calibration in cone-beam tomography,' Med. Phys. 31(12), 3242-3266 (2004)], their results were roughly of the same order of accuracy. Their analysis revealed that the method is capable of sufficiently calibrating out-of-plane angles in cases of larger cone angles when neglecting these angles negatively affects the reconstruction. Fine details in the 3D reconstruction of the spine segment and an electronic device indicate a high geometric calibration accuracy and the capability to produce state-of-the-art reconstructions. Conclusions: The method introduced here makes no requirements on the accuracy of the test object. In contrast to many previous autocalibration methods their approach also includes out-of-plane rotations of the detector. Although assuming a perfect rotation, the method seems to be sufficiently accurate for a commercial CBCT scanner. For devices which require higher dimensional geometry models, the method could be used as a initial calibration procedure.« less

Towards a quantitative, measurement-based estimate of the uncertainty in photon mass attenuation coefficients at radiation therapy energies

NASA Astrophysics Data System (ADS)

Ali, E. S. M.; Spencer, B.; McEwen, M. R.; Rogers, D. W. O.

2015-02-01

In this study, a quantitative estimate is derived for the uncertainty in the XCOM photon mass attenuation coefficients in the energy range of interest to external beam radiation therapy—i.e. 100 keV (orthovoltage) to 25 MeV—using direct comparisons of experimental data against Monte Carlo models and theoretical XCOM data. Two independent datasets are used. The first dataset is from our recent transmission measurements and the corresponding EGSnrc calculations (Ali et al 2012 Med. Phys. 39 5990-6003) for 10-30 MV photon beams from the research linac at the National Research Council Canada. The attenuators are graphite and lead, with a total of 140 data points and an experimental uncertainty of ˜0.5% (k = 1). An optimum energy-independent cross section scaling factor that minimizes the discrepancies between measurements and calculations is used to deduce cross section uncertainty. The second dataset is from the aggregate of cross section measurements in the literature for graphite and lead (49 experiments, 288 data points). The dataset is compared to the sum of the XCOM data plus the IAEA photonuclear data. Again, an optimum energy-independent cross section scaling factor is used to deduce the cross section uncertainty. Using the average result from the two datasets, the energy-independent cross section uncertainty estimate is 0.5% (68% confidence) and 0.7% (95% confidence). The potential for energy-dependent errors is discussed. Photon cross section uncertainty is shown to be smaller than the current qualitative ‘envelope of uncertainty’ of the order of 1-2%, as given by Hubbell (1999 Phys. Med. Biol 44 R1-22).

Sex determination from calcification of costal cartilages in a Scottish sample.

PubMed

Middleham, Helen P; Boyd, Laura E; Mcdonald, Stuart W

2015-10-01

The pelvic bones and skull are not always available when human remains are discovered in a forensic setting. This study investigates the suitability to a Scottish sample of existing methods of sexing based on calcification patterns in the costal cartilages. Radiographs of chest plates of 41 cadavers, 22 male and 19 female aged 57-96 years were analyzed for their calcification patterns according to the methods of McCormick et al. (1985, Am. J. Phys. Anthropol. 68:173-195) and Rejtarova et al. (2004, Biomed. Pap. Med. Fac. Univ. Palacky. Olomouc. Czech. Repub. 148:241-243). With the method of Rejtarova et al. (2004, Biomed. Pap. Med. Fac. Univ. Palacky. Olomouc. Czech. Repub. 148:241-243) none of the male specimens was sexed correctly. Of the chest plates that were suitable for sexing, the method of McCormick et al. (1985, Am. J. Phys. Anthropol. 68:173-195) correctly sexed 82.4% of the female specimens but only 41.2% of the males. To improve the reliability, we suggest a new method of sex determination based on whether the calcified deposits in the second to seventh costal cartilages are predominantly trabecular bone or sclerotic calcified deposits. Specimens with minimal amounts or similar amounts of trabecular bone or sclerotic deposits in the costal cartilages are not appropriate for our method. When such specimens (10 specimens) were excluded, our method correctly sexed 16 of 17 (94%) males and 12 of 14 (86%) females. The authors acknowledge that their sample is small and that many of their subjects were elderly and that the method should be tested on a larger sample group before application in a forensic context. © 2014 Wiley Periodicals, Inc.

Development and Translation of Hybrid Optoacoustic/Ultrasonic Tomography for Early Breast Cancer Detection

DTIC Science & Technology

2015-09-01

iterative algorithms of OAT to improve image fidelity. Laser ultrasound is generated through conversion of low -energy (about 100 µJ) 9 ns laser pulses ...Scherzinger, and T. Oughton, “Breast im- aging in coronal planes with simultaneous pulse echo and transmis- sion ultrasound ,” Science, vol. 214, no. 4525, pp...unidirectional pulse -echo ultrasound imaging,” Phys. Med. Biol., vol. 58, no. 17, art. no. 6163, 2013. [41] L. A. Romero, D. C. Ghiglia, C. C. Ober, and S. A

Variation of concentration of tetrakis and hydroquinone with post-irradiation times in PAGAT polymer gel dosimeter

NASA Astrophysics Data System (ADS)

Venning, Anthony J.; Hill, Brendan; Baldock, Clive

2006-12-01

Following on from the investigation of the normoxic PAGAT polymer gel dosimeter by Venning A J, Hill B, Brindha S, Healy B J and Baldock C 2005 Phys. Med. Biol. 50 3875-3888 this paper examines the change in transverse relaxation rate R2 with time for different concentrations of tetrakis (hydroxymethyl) phosphonium chloride and hydroquinone for fixed concentrations of N,N-methylene-bis-acrylamide, acrylamide, gelatine and H2M/O.

Fetal ECG Extraction From Maternal Body Surface Measurement Using Independent Component Analysis

DTIC Science & Technology

2001-10-25

Ibaraki 305-0901, Japan Abstract – A method applying independent component analysis (ICA) to detect the electrocardiogram of a prenatal cattle foetus is...monitoring the health status of an unborn cattle foetus is indispensable in preventing natural abortion and premature birth [3]. One of the applicable...and Y. Honda, “ECG and Heart Rate Detection of Prenatal Cattle Foetus Using Adaptive Digital Filtering,” World Congress on Med. Phys.& Biomed. Eng., Chicago TU-CXH-75, pp. 1-4, 2000.

Laryngeal flow due to longitudinal sweeping motion of the vocal folds and its contribution to auto-oscillation.

PubMed

Boutin, Henri; Smith, John; Wolfe, Joe

2015-07-01

Analysis of published depth-kymography data [George, de Mul, Qiu, Rakhorst, and Schutte (2008). Phys. Med. Biol. 53, 2667-2675] shows that, for the subject studied, the flow due to the longitudinal sweeping motion of the vocal folds contributes several percent of a typical acoustic flow at the larynx. This sweeping flow is a maximum when the glottis is closed. This observation suggests that assumption of zero laryngeal flow during the closed phase as a criterion when determining parameters in inverse filtering should be used with caution. Further, these data suggest that the swinging motion contributes work to overcome mechanical losses and thus to assist auto-oscillation.

Medial tibial stress syndrome: conservative treatment options.

PubMed

Galbraith, R Michael; Lavallee, Mark E

2009-10-07

Medial tibial stress syndrome (MTSS), commonly known as "shin splints," is a frequent injury of the lower extremity and one of the most common causes of exertional leg pain in athletes (Willems T, Med Sci Sports Exerc 39(2):330-339, 2007; Korkola M, Amendola A, Phys Sportsmed 29(6):35-50, 2001; Hreljac A, Med Sci Sports Exerc 36(5):845-849, 2004). Although often not serious, it can be quite disabling and progress to more serious complications if not treated properly. Often, the cause of MTSS is multi-factorial and involves training errors and various biomechanical abnormalities. Few advances have been made in the treatment of MTSS over the last few decades. Current treatment options are mostly based on expert opinion and clinical experience. The purpose of this article is to review published literature regarding conservative treatment options for MTSS and provide recommendations for sports medicine clinicians for improved treatment and patient outcomes.

Development and Optimization of a Dedicated, Hybrid Dual-Modality SPECT-CmT System for Improved Breast Lesion Diagnosis

DTIC Science & Technology

2008-01-01

CT contrast agent, four 6.0mm nylon balls (Small Parts, Inc. Miami Lakes, FL) soaked in aqueous 99mTc-pertechnetate were used as markers and taped ...Inc, Miramar, Fl) were soaked in concentrated aqueous 99mTc and taped to the exterior surface of the breast phantom to act as fiducial markers for...vol. 21, pp. 48-55, 2006. [16] H. Erdogan and J. A. Fessler, "Ordered subsets algorithms for transmission tomography," Phys Med Biol, vol. 44, pp

Development of a Computer-aided Diagnosis System for Early Detection of Masses Using Retrospectively Detected Cancers on Prior Mammograms

DTIC Science & Technology

2009-06-01

131 cases with 131 biopsy proven masses, of which 27 were malignant and 104 benign. The true locations of the masses were identified by an experi- enced ...two acquisitions would cause differ- ences in the subtlety of the masses on the FFDMs and SFMs. However, assuming that the differences are ran- dom... Lado , M. Souto, and J. J. Vidal, “Computer-aided diagnosis: Automatic detection of malignant masses in digitized mammograms,” Med. Phys. 25, 957–964

The Effects of an Acute Bout of Strenuous Aerobic Exercise on Plasma, Erythrocyte, Urinary and Dietary Values for Selected Trace Minerals

DTIC Science & Technology

1996-12-09

some serum copper parameters in trained professional soccer players and control subjects. J. Sports Med. Phys. Fitness. 31:4123-416, 1991. 110. Ruz, M...WOMAN’S UNIVERSITY DEPARTMENT OF NUTRITION AND FOOD SCIENCES COLLEGE OF HEALTH SCIENCES BY KIMBERLY K. EDGREN, RD, BS, CDE DENTON, TEXAS DECEMBER 1996...of the requirements for the degree of Master of Science, with a major in Nutrition . Bett,/B. Alfor ,Ph.D., Major Professor We have read this thesis and

Characteristic features of a high-energy x-ray spectra estimation method based on the Waggener iterative perturbation principle

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

Iwasaki, Akira; Kubota, Mamoru; Hirota, Junichi

2006-11-15

We have redeveloped a high-energy x-ray spectra estimation method reported by Iwasaki et al. [A. Iwasaki, H. Matsutani, M. Kubota, A. Fujimori, K. Suzaki, and Y. Abe, Radiat. Phys. Chem. 67, 81-91 (2003)]. The method is based on the iterative perturbation principle to minimize differences between measured and calculated transmission curves, originally proposed by Waggener et al. [R. G. Waggener, M. M. Blough, J. A. Terry, D. Chen, N. E. Lee, S. Zhang, and W. D. McDavid, Med. Phys. 26, 1269-1278 (1999)]. The method can estimate spectra applicable for media at least from water to lead using only about tenmore » energy bins. Estimating spectra of 4-15 MV x-ray beams from a linear accelerator, we describe characteristic features of the method with regard to parameters including the prespectrum, number of transmission measurements, number of energy bins, energy bin widths, and artifactual bipeaked spectrum production.« less

Sci-Sat AM: Radiation Dosimetry and Practical Therapy Solutions - 05: Not all geometries are equivalent for magnetic field Fano cavity tests

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

Malkov, Victor N.; Rogers, David W.O.

The coupling of MRI and radiation treatment systems for the application of magnetic resonance guided radiation therapy necessitates a reliable magnetic field capable Monte Carlo (MC) code. In addition to the influence of the magnetic field on dose distributions, the question of proper calibration has arisen due to the several percent variation of ion chamber and solid state detector responses in magnetic fields when compared to the 0 T case (Reynolds et al., Med Phys, 2013). In the absence of a magnetic field, EGSnrc has been shown to pass the Fano cavity test (a rigorous benchmarking tool of MC codes)more » at the 0.1 % level (Kawrakow, Med.Phys, 2000), and similar results should be required of magnetic field capable MC algorithms. To properly test such developing MC codes, the Fano cavity theorem has been adapted to function in a magnetic field (Bouchard et al., PMB, 2015). In this work, the Fano cavity test is applied in a slab and ion-chamber-like geometries to test the transport options of an implemented magnetic field algorithm in EGSnrc. Results show that the deviation of the MC dose from the expected Fano cavity theory value is highly sensitive to the choice of geometry, and the ion chamber geometry appears to pass the test more easily than larger slab geometries. As magnetic field MC codes begin to be used for dose simulations and correction factor calculations, care must be taken to apply the most rigorous Fano test geometries to ensure reliability of such algorithms.« less

Comment on ‘egs_brachy: a versatile and fast Monte Carlo code for brachytherapy’

NASA Astrophysics Data System (ADS)

Yegin, Gultekin

2018-02-01

In a recent paper (Chamberland et al 2016 Phys. Med. Biol. 61 8214) develop a new Monte Carlo code called egs_brachy for brachytherapy treatments. It is based on EGSnrc, and written in the C++ programming language. In order to benchmark the egs_brachy code, the authors use it in various test case scenarios in which complex geometry conditions exist. Another EGSnrc based brachytherapy dose calculation engine, BrachyDose, is used for dose comparisons. The authors fail to prove that egs_brachy can produce reasonable dose values for brachytherapy sources in a given medium. The dose comparisons in the paper are erroneous and misleading. egs_brachy should not be used in any further research studies unless and until all the potential bugs are fixed in the code.

Correlative Feature Analysis for Multimodality Breast CAD

DTIC Science & Technology

2007-09-01

Imaging 20,12751284 (2001)22. V. Caselles, R . Kimmel, and G. Sapiro. Geodesi a tive ontours. Int. J. Comput.Vision 22, 6179 (1997)23. R . Malladi , J. A...φ ‖ ) − λ1(f0 − c1) 2 + λ2(f0 − c2) 2] + v · div[(1− 1 ‖ ∇φ ‖ )∇φ]. (24)Referen es1. A. J. Jemal, R . Siegel, E. Ward, T. Murray, J. Xu, and M. J...Med. Phys. 31,958971 (2004)11. D. Guliato, R . M. Rangayyan, W. A. Carnielli, J. A. Zuo, and J. E. L. Desautels.Segmentation of breast tumors in

A modern Monte Carlo investigation of the TG-43 dosimetry parameters for an {sup 125}I seed already having AAPM consensus data

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

Aryal, Prakash; Molloy, Janelle A.; Rivard, Mark J., E-mail: mark.j.rivard@gmail.com

2014-02-15

Purpose: To investigate potential causes for differences in TG-43 brachytherapy dosimetry parameters in the existent literature for the model IAI-125A{sup 125}I seed and to propose new standard dosimetry parameters. Methods: The MCNP5 code was used for Monte Carlo (MC) simulations. Sensitivity of dose distributions, and subsequently TG-43 dosimetry parameters, was explored to reproduce historical methods upon which American Association of Physicists in Medicine (AAPM) consensus data are based. Twelve simulation conditions varying{sup 125}I coating thickness, coating mass density, photon interaction cross-section library, and photon emission spectrum were examined. Results: Varying{sup 125}I coating thickness, coating mass density, photon cross-section library, andmore » photon emission spectrum for the model IAI-125A seed changed the dose-rate constant by up to 0.9%, about 1%, about 3%, and 3%, respectively, in comparison to the proposed standard value of 0.922 cGy h{sup −1} U{sup −1}. The dose-rate constant values by Solberg et al. [“Dosimetric parameters of three new solid core {sup 125}I brachytherapy sources,” J. Appl. Clin. Med. Phys. 3, 119–134 (2002)], Meigooni et al. [“Experimental and theoretical determination of dosimetric characteristics of IsoAid ADVANTAGE™ {sup 125}I brachytherapy source,” Med. Phys. 29, 2152–2158 (2002)], and Taylor and Rogers [“An EGSnrc Monte Carlo-calculated database of TG-43 parameters,” Med. Phys. 35, 4228–4241 (2008)] for the model IAI-125A seed and Kennedy et al. [“Experimental and Monte Carlo determination of the TG-43 dosimetric parameters for the model 9011 THINSeed™ brachytherapy source,” Med. Phys. 37, 1681–1688 (2010)] for the model 6711 seed were +4.3% (0.962 cGy h{sup −1} U{sup −1}), +6.2% (0.98 cGy h{sup −1} U{sup −1}), +0.3% (0.925 cGy h{sup −1} U{sup −1}), and −0.2% (0.921 cGy h{sup −1} U{sup −1}), respectively, in comparison to the proposed standard value. Differences in the radial dose functions between the current study and both Solberg et al. and Meigooni et al. were <10% for r ≤ 5 cm, and increased for r > 5 cm with a maximum difference of 29% at r = 9 cm. In comparison to Taylor and Rogers, these differences were lower (maximum of 2% at r = 9 cm). For the similarly designed model 6711 {sup 125}I seed, differences did not exceed 0.5% for 0.5 ≤ r ≤ 10 cm. Radial dose function values varied by 1% as coating thickness and coating density were changed. Varying the cross-section library and source spectrum altered the radial dose function by 25% and 12%, respectively, but these differences occurred at r = 10 cm where the dose rates were very low. The 2D anisotropy function results were most similar to those of Solberg et al. and most different to those of Meigooni et al. The observed order of simulation condition variables from most to least important for influencing the 2D anisotropy function was spectrum, coating thickness, coating density, and cross-section library. Conclusions: Several MC radiation transport codes are available for calculation of the TG-43 dosimetry parameters for brachytherapy seeds. The physics models in these codes and their related cross-section libraries have been updated and improved since publication of the 2007 AAPM TG-43U1S1 report. Results using modern data indicated statistically significant differences in these dosimetry parameters in comparison to data recommended in the TG-43U1S1 report. Therefore, it seems that professional societies such as the AAPM should consider reevaluating the consensus data for this and others seeds and establishing a process of regular evaluations in which consensus data are based upon methods that remain state-of-the-art.« less

SU-F-I-75: Half-Value Layer Thicknesses and Homogeneity Coefficients for Fluoroscopic X-Ray Beam Spectra Incorporating Spectral Filtration

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

Wunderle, K; Wayne State University School of Medicine, Detroit, MI; Godley, A

Purpose: The purpose of this investigation is to quantify various first half-value-layers (HVLs), second HVLs and homogeneity coefficients (HCs) for a state-of-the-art fluoroscope utilizing spectral (copper) filtration. Methods: A Radcal (Monrovia, Ca) AccuPro dosimeter with a 10×6-6 calibrated ionization chamber was used to measure air kerma for radiographic x-ray exposures made on a Siemens (Erlangen, Germany) Artis ZeeGo fluoroscope operated in the service mode. The ionization chamber was centered in the x-ray beam at 72 cm from the focal spot with a source-to-image-distance of 120 cm. The collimators were introduced to limit the x-ray field to approximately 5 cm ×more » 5 cm at the ionization chamber plane. Type-1100 aluminum filters, in 0.5 mm increments, were used to determine the HVL. Two HVL calculation methods were used, log-linear interpolation and Lambert-W interpolation as described by Mathieu [Med Phys, 38(8), 4546 (2011)]. Multiple measurements were made at 60, 80, 100, 120 kVp at spectral filtration thicknesses of 0, 0.1, 0.3, 0.6 and 0.9 mm. Results: First HVL, second HVL, and HCs are presented for the fluoroscopic x-ray beam spectra indicated above, with nearly identical results from the two interpolation methods. Accuracy of the set kVp was also determined and deviated less than 2%. First HVLs for fluoroscopic x-ray beam spectra without spectral filtration determined in our study were 7%–16% greater than previously published data by Fetterly et al. [Med Phys, 28, 205 (2001)]. However, the FDA minimum HVL requirements changed since that publication, requiring larger HVLs as of 2006. Additionally, x-ray tube and generator architecture have substantially changed over the last 15 years providing different beam spectra. Conclusion: X-ray beam quality characteristics for state-of-the-art fluoroscopes with spectral filtration have not been published. This study provides reference data which will be useful for defining beam qualities encountered on fluoroscopes using spectral filtration.« less

On charged particle equilibrium violation in external photon fields.

PubMed

Bouchard, Hugo; Seuntjens, Jan; Palmans, Hugo

2012-03-01

In a recent paper by Bouchard et al. [Med. Phys. 36(10), 4654-4663 (2009)], a theoretical model of quality correction factors for idealistic so-called plan-class specific reference (PCSR) fields was proposed. The reasoning was founded on the definition of PCSR fields made earlier by Alfonso et al. [Med. Phys. 35(11), 5179-5186 (2008)], requiring the beam to achieve charged particle equilibrium (CPE), in a time-averaged sense, in the reference medium. The relation obtained by Bouchard et al. was derived using Fano's theorem (1954) which states that if CPE is established in a given medium, the dose is independent of point-to-point density variations. A potential misconception on the achievability of the condition required by Fano (1954) might be responsible for false practical conclusions, both in the definition of PCSR fields as well as the theoretical model of quality correction factor. In this paper, the practical achievability of CPE in external beams is treated in detail. The fact that this condition is not achievable in single or composite deliveries is illustrated by an intuitive method and is also formally demonstrated. Fano's theorem is not applicable in external beam radiation dosimetry without (virtually) removing attenuation effects, and therefore, the relation conditionally defined by Bouchard et al. (2009) cannot be valid in practice. A definition of PCSR fields in the recent formalism for nonstandard beams proposed by Alfonso et al. (2008) should be modified, revising the criterion of CPE condition. The authors propose reconsidering the terminology used to describe standard and nonstandard beams. The authors argue that quality correction factors of intensity modulated radiation therapy PCSR fields (i.e., k(Q(pcsr),Q) (f(pcsr),f(ref) )) could be unity under ideal conditions, but it is concluded that further investigation is necessary to confirm that hypothesis.

Review and resolution of some nomenclatural issues regarding the genus Psoroptes (Acari: Psoroptidae), scab-mites of domestic and wild mammals.

PubMed

OConnor, Barry M; Klimov, Pavel B

2015-07-01

Some classifications recognize a number of species in the scab-mite genus, Psoroptes, mites that are of considerable importance in livestock production and veterinary medicine. However, modern studies suggest that populations from some host species are not morphologically or genetically distinct, creating taxonomic confusion with older names, which treated mites from different hosts as separate species. We review the taxonomy and nomenclature of the genus and the two oldest binomens, most recently known as Psoroptes ovis and Psoroptes equi. Prior authors have attributed these names to various authorities, with most attributing both names to Hering (Nova Acta Phys-Med Acad Caesar Leopold-Carol Nat Curios 18(2):573-624, 1838). In particular, the priority between these names was recently a point of contention, with P. ovis being treated as junior synonym of P. equi. A review of all relevant nineteenth and twentieth century publications indicates, however, that these binomens should be cited as P. ovis (Viborg in Veterinair-Selskabets Skrifter 2:139-152, 1813) and P. equi (Raspail in Bull gener Theraput Med Chir 7:169-184, 1834), with the former having priority over the latter assuming their conspecificity. We also clarify attribution of the authorship and the type species of the genus Psoroptes.

A harmonic adiabatic approximation to calculate highly excited vibrational levels of ``floppy molecules''

NASA Astrophysics Data System (ADS)

Lauvergnat, David; Nauts, André; Justum, Yves; Chapuisat, Xavier

2001-04-01

The harmonic adiabatic approximation (HADA), an efficient and accurate quantum method to calculate highly excited vibrational levels of molecular systems, is presented. It is well-suited to applications to "floppy molecules" with a rather large number of atoms (N>3). A clever choice of internal coordinates naturally suggests their separation into active, slow, or large amplitude coordinates q', and inactive, fast, or small amplitude coordinates q″, which leads to an adiabatic (or Born-Oppenheimer-type) approximation (ADA), i.e., the total wave function is expressed as a product of active and inactive total wave functions. However, within the framework of the ADA, potential energy data concerning the inactive coordinates q″ are required. To reduce this need, a minimum energy domain (MED) is defined by minimizing the potential energy surface (PES) for each value of the active variables q', and a quadratic or harmonic expansion of the PES, based on the MED, is used (MED harmonic potential). In other words, the overall picture is that of a harmonic valley about the MED. In the case of only one active variable, we have a minimum energy path (MEP) and a MEP harmonic potential. The combination of the MED harmonic potential and the adiabatic approximation (harmonic adiabatic approximation: HADA) greatly reduces the size of the numerical computations, so that rather large molecules can be studied. In the present article however, the HADA is applied to our benchmark molecule HCN/CNH, to test the validity of the method. Thus, the HADA vibrational energy levels are compared and are in excellent agreement with the ADA calculations (adiabatic approximation with the full PES) of Light and Bačić [J. Chem. Phys. 87, 4008 (1987)]. Furthermore, the exact harmonic results (exact calculations without the adiabatic approximation but with the MEP harmonic potential) are compared to the exact calculations (without any sort of approximation). In addition, we compare the densities of the bending motion during the HCN/CNH isomerization, computed with the HADA and the exact wave function.

Photoinduced Partial Unfolding of Tubulin Bound to Meso-tetrakis(sulfonatophenyl) Porphyrin Leads to Inhibition of Microtubule Formation In Vitro

DTIC Science & Technology

2013-07-30

H. Nettles, B . Cornett, K . H. Downing, and E. Nogales, Proc. Natl. Acad. Sci. 98, 5312–5316 (2001). B . McMicken et al.: Photoinduced unfolding of...and R. K . Pandey, Chem Soc Rev. 40, 340–362 (2011). [23] B . C. Wilson and M. S. Patterson, Phys Med Biol. 53, R61–R109 (2008). [24] E. D. Sternberg, D... K . Subbarao and R. C. MacDonald, Analyst 118, 913–916 (1993). [30] F. V. Bright and C. Munson, Anal. Chim. Acta 500, 71–104 (2003). [31] Z. Li, T. Lu

Generalized lattice Boltzmann model for flow through tight porous media with Klinkenberg's effect

NASA Astrophysics Data System (ADS)

Chen, Li; Fang, Wenzhen; Kang, Qinjun; De'Haven Hyman, Jeffrey; Viswanathan, Hari S.; Tao, Wen-Quan

2015-03-01

Gas slippage occurs when the mean free path of the gas molecules is in the order of the characteristic pore size of a porous medium. This phenomenon leads to Klinkenberg's effect where the measured permeability of a gas (apparent permeability) is higher than that of the liquid (intrinsic permeability). A generalized lattice Boltzmann model is proposed for flow through porous media that includes Klinkenberg's effect, which is based on the model of Guo et al. [Phys. Rev. E 65, 046308 (2002), 10.1103/PhysRevE.65.046308]. The second-order Beskok and Karniadakis-Civan's correlation [A. Beskok and G. Karniadakis, Microscale Thermophys. Eng. 3, 43 (1999), 10.1080/108939599199864 and F. Civan, Transp. Porous Med. 82, 375 (2010), 10.1007/s11242-009-9432-z] is adopted to calculate the apparent permeability based on intrinsic permeability and the Knudsen number. Fluid flow between two parallel plates filled with porous media is simulated to validate the model. Simulations performed in a heterogeneous porous medium with components of different porosity and permeability indicate that Klinkenberg's effect plays a significant role on fluid flow in low-permeability porous media, and it is more pronounced as the Knudsen number increases. Fluid flow in a shale matrix with and without fractures is also studied, and it is found that the fractures greatly enhance the fluid flow and Klinkenberg's effect leads to higher global permeability of the shale matrix.

Organ and effective doses in newborn patients during helical multislice computed tomography examination

NASA Astrophysics Data System (ADS)

Staton, Robert J.; Lee, Choonik; Lee, Choonsik; Williams, Matt D.; Hintenlang, David E.; Arreola, Manuel M.; Williams, Jonathon L.; Bolch, Wesley E.

2006-10-01

In this study, two computational phantoms of the newborn patient were used to assess individual organ doses and effective doses delivered during head, chest, abdomen, pelvis, and torso examinations using the Siemens SOMATOM Sensation 16 helical multi-slice computed tomography (MSCT) scanner. The stylized phantom used to model the patient anatomy was the revised ORNL newborn phantom by Han et al (2006 Health Phys.90 337). The tomographic phantom used in the study was that developed by Nipper et al (2002 Phys. Med. Biol. 47 3143) as recently revised by Staton et al (2006 Med. Phys. 33 3283). The stylized model was implemented within the MCNP5 radiation transport code, while the tomographic phantom was incorporated within the EGSnrc code. In both codes, the x-ray source was modelled as a fan beam originating from the focal spot at a fan angle of 52° and a focal-spot-to-axis distance of 57 cm. The helical path of the source was explicitly modelled based on variations in collimator setting (12 mm or 24 mm), detector pitch and scan length. Tube potentials of 80, 100 and 120 kVp were considered in this study. Beam profile data were acquired using radiological film measurements on a 16 cm PMMA phantom, which yielded effective beam widths of 14.7 mm and 26.8 mm for collimator settings of 12 mm and 24 mm, respectively. Values of absolute organ absorbed dose were determined via the use of normalization factors defined as the ratio of the CTDI100 measured in-phantom and that determined by Monte Carlo simulation of the PMMA phantom and ion chamber. Across various technique factors, effective dose differences between the stylized and tomographic phantoms ranged from +2% to +9% for head exams, -4% to -2% for chest exams, +8% to +24% for abdominal exams, -16% to -12% for pelvic exams and -7% to 0% for chest-abdomen-pelvis (CAP) exams. In many cases, however, relatively close agreement in effective dose was accomplished at the expense of compensating errors in individual organ dose. Per cent differences in organ dose between the stylized and tomographic phantoms at 120 kVp and 12 mm collimator setting ranged from -25% (skin) to +164% (muscle) for head exams, -92% (thyroid) to +98% (ovaries) for chest exams, -144% (uterus) to +112% (ovaries) for abdominal exams, -98% (SI wall) to +20% (thymus) for pelvic exams and -60% (extrathoracic airways) to +13% (ovaries) for CAP exams. Better agreement was seen between the two phantom types for organs entirely within the scan field. In these cases, corresponding per cent differences in organ absorbed dose did not vary more than 17%. For all scans, the effective dose was found to range approximately 1-13 mSv across the scan parameters and scan regions. The largest effective dose occurred for CAP scans at 120 kVp.

TH-A-BRC-00: New Task Groups for External Beam QA: An Overview

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

NONE

2016-06-15

AAPM TG-135U1 QA for Robotic Radiosurgery - Sonja Dieterich Since the publication of AAPM TG-135 in 2011, the technology of robotic radiosurgery has rapidly developed. AAPM TG-135U1 will provide recommendations on the clinical practice for using the IRIS collimator, fiducial-less real-time motion tracking, and Monte Carlo based treatment planning. In addition, it will summarize currently available literature about uncertainties. Learning Objectives: Understand the progression of technology since the first TG publication Learn which new QA procedures should be implemented for new technologies Be familiar with updates to clinical practice guidelines AAPM TG-178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance -more » Steven Goetsch Purpose: AAPM Task Group 178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance was formed in August, 2008. The Task Group has 12 medical physicists, two physicians and two consultants. Methods: A round robin dosimetry intercomparison of proposed ionization chambers, electrometer and dosimetry phantoms was conducted over a 15 month period in 2011 and 2012 (Med Phys 42, 11, Nov, 2015). The data obtained at 9 institutions (with ten different Elekta Gamma Knife units) was analyzed by the lead author using several protocols. Results: The most consistent results were obtained using the Elekta ABS 16cm diameter phantom, with the TG-51 protocol modified as recommended by Alfonso et al (Med Phys 35, 11, Nov 2008). A key white paper (Med Phys, in press) sponsored by Elekta Corporation, was used to obtain correction factors for the ionization chambers and phantoms used in this intercomparison. Consistent results were obtained for both Elekta Gamma Knife Model 4C and Gamma Knife Perfexion units as measured with each of two miniature ionization chambers. Conclusion: The full report gives clinical history and background of gamma stereotactic radiosurgery, clinical examples and history, quality assurance recommendations and outline of possible dosimetry protocols. The report will be reviewed by the AAPM Working Group on Recommendations for Radiotherapy External Beam Quality Assurance and then by the AAPM Science Council before publication in Medical Physics Survey of possible calibration protocols for calibration of Gamma Stereotactic Radiosurgery (GSR) devices Overview of modern Quality Assurance techniques for GSR AAPM TG-218 Tolerance Levels and Methodologies for IMRT Verification QA - Moyed Miften Patient-specific IMRT QA measurement is a process designed to identify discrepancies between calculated and delivered doses. Error tolerance limits are not well-defined or consistently applied across centers. The AAPM TG-218 report has been prepared to improve the understanding and consistency of this process by providing recommendations for methodologies and tolerance limits in patient-specific IMRT QA. Learning Objectives: Review measurement methods and methodologies for absolute dose verification Provide recommendations on delivery methods, data interpretation, the use of analysis routines and choice of tolerance limits for IMRT QA Sonja Dieterich has a research agreement with Sun Nuclear Inc. Steven Goetsch is a part-time consultant for Elekta.« less

TH-A-BRC-03: AAPM TG218: Measurement Methods and Tolerance Levels for Patient-Specific IMRT Verification QA

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

Miften, M.

2016-06-15

AAPM TG-135U1 QA for Robotic Radiosurgery - Sonja Dieterich Since the publication of AAPM TG-135 in 2011, the technology of robotic radiosurgery has rapidly developed. AAPM TG-135U1 will provide recommendations on the clinical practice for using the IRIS collimator, fiducial-less real-time motion tracking, and Monte Carlo based treatment planning. In addition, it will summarize currently available literature about uncertainties. Learning Objectives: Understand the progression of technology since the first TG publication Learn which new QA procedures should be implemented for new technologies Be familiar with updates to clinical practice guidelines AAPM TG-178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance -more » Steven Goetsch Purpose: AAPM Task Group 178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance was formed in August, 2008. The Task Group has 12 medical physicists, two physicians and two consultants. Methods: A round robin dosimetry intercomparison of proposed ionization chambers, electrometer and dosimetry phantoms was conducted over a 15 month period in 2011 and 2012 (Med Phys 42, 11, Nov, 2015). The data obtained at 9 institutions (with ten different Elekta Gamma Knife units) was analyzed by the lead author using several protocols. Results: The most consistent results were obtained using the Elekta ABS 16cm diameter phantom, with the TG-51 protocol modified as recommended by Alfonso et al (Med Phys 35, 11, Nov 2008). A key white paper (Med Phys, in press) sponsored by Elekta Corporation, was used to obtain correction factors for the ionization chambers and phantoms used in this intercomparison. Consistent results were obtained for both Elekta Gamma Knife Model 4C and Gamma Knife Perfexion units as measured with each of two miniature ionization chambers. Conclusion: The full report gives clinical history and background of gamma stereotactic radiosurgery, clinical examples and history, quality assurance recommendations and outline of possible dosimetry protocols. The report will be reviewed by the AAPM Working Group on Recommendations for Radiotherapy External Beam Quality Assurance and then by the AAPM Science Council before publication in Medical Physics Survey of possible calibration protocols for calibration of Gamma Stereotactic Radiosurgery (GSR) devices Overview of modern Quality Assurance techniques for GSR AAPM TG-218 Tolerance Levels and Methodologies for IMRT Verification QA - Moyed Miften Patient-specific IMRT QA measurement is a process designed to identify discrepancies between calculated and delivered doses. Error tolerance limits are not well-defined or consistently applied across centers. The AAPM TG-218 report has been prepared to improve the understanding and consistency of this process by providing recommendations for methodologies and tolerance limits in patient-specific IMRT QA. Learning Objectives: Review measurement methods and methodologies for absolute dose verification Provide recommendations on delivery methods, data interpretation, the use of analysis routines and choice of tolerance limits for IMRT QA Sonja Dieterich has a research agreement with Sun Nuclear Inc. Steven Goetsch is a part-time consultant for Elekta.« less

TH-A-BRC-02: AAPM TG-178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance

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

Goetsch, S.

AAPM TG-135U1 QA for Robotic Radiosurgery - Sonja Dieterich Since the publication of AAPM TG-135 in 2011, the technology of robotic radiosurgery has rapidly developed. AAPM TG-135U1 will provide recommendations on the clinical practice for using the IRIS collimator, fiducial-less real-time motion tracking, and Monte Carlo based treatment planning. In addition, it will summarize currently available literature about uncertainties. Learning Objectives: Understand the progression of technology since the first TG publication Learn which new QA procedures should be implemented for new technologies Be familiar with updates to clinical practice guidelines AAPM TG-178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance -more » Steven Goetsch Purpose: AAPM Task Group 178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance was formed in August, 2008. The Task Group has 12 medical physicists, two physicians and two consultants. Methods: A round robin dosimetry intercomparison of proposed ionization chambers, electrometer and dosimetry phantoms was conducted over a 15 month period in 2011 and 2012 (Med Phys 42, 11, Nov, 2015). The data obtained at 9 institutions (with ten different Elekta Gamma Knife units) was analyzed by the lead author using several protocols. Results: The most consistent results were obtained using the Elekta ABS 16cm diameter phantom, with the TG-51 protocol modified as recommended by Alfonso et al (Med Phys 35, 11, Nov 2008). A key white paper (Med Phys, in press) sponsored by Elekta Corporation, was used to obtain correction factors for the ionization chambers and phantoms used in this intercomparison. Consistent results were obtained for both Elekta Gamma Knife Model 4C and Gamma Knife Perfexion units as measured with each of two miniature ionization chambers. Conclusion: The full report gives clinical history and background of gamma stereotactic radiosurgery, clinical examples and history, quality assurance recommendations and outline of possible dosimetry protocols. The report will be reviewed by the AAPM Working Group on Recommendations for Radiotherapy External Beam Quality Assurance and then by the AAPM Science Council before publication in Medical Physics Survey of possible calibration protocols for calibration of Gamma Stereotactic Radiosurgery (GSR) devices Overview of modern Quality Assurance techniques for GSR AAPM TG-218 Tolerance Levels and Methodologies for IMRT Verification QA - Moyed Miften Patient-specific IMRT QA measurement is a process designed to identify discrepancies between calculated and delivered doses. Error tolerance limits are not well-defined or consistently applied across centers. The AAPM TG-218 report has been prepared to improve the understanding and consistency of this process by providing recommendations for methodologies and tolerance limits in patient-specific IMRT QA. Learning Objectives: Review measurement methods and methodologies for absolute dose verification Provide recommendations on delivery methods, data interpretation, the use of analysis routines and choice of tolerance limits for IMRT QA Sonja Dieterich has a research agreement with Sun Nuclear Inc. Steven Goetsch is a part-time consultant for Elekta.« less

TH-A-BRC-01: AAPM TG-135U1 QA for Robotic Radiosurgery

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

Dieterich, S.

AAPM TG-135U1 QA for Robotic Radiosurgery - Sonja Dieterich Since the publication of AAPM TG-135 in 2011, the technology of robotic radiosurgery has rapidly developed. AAPM TG-135U1 will provide recommendations on the clinical practice for using the IRIS collimator, fiducial-less real-time motion tracking, and Monte Carlo based treatment planning. In addition, it will summarize currently available literature about uncertainties. Learning Objectives: Understand the progression of technology since the first TG publication Learn which new QA procedures should be implemented for new technologies Be familiar with updates to clinical practice guidelines AAPM TG-178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance -more » Steven Goetsch Purpose: AAPM Task Group 178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance was formed in August, 2008. The Task Group has 12 medical physicists, two physicians and two consultants. Methods: A round robin dosimetry intercomparison of proposed ionization chambers, electrometer and dosimetry phantoms was conducted over a 15 month period in 2011 and 2012 (Med Phys 42, 11, Nov, 2015). The data obtained at 9 institutions (with ten different Elekta Gamma Knife units) was analyzed by the lead author using several protocols. Results: The most consistent results were obtained using the Elekta ABS 16cm diameter phantom, with the TG-51 protocol modified as recommended by Alfonso et al (Med Phys 35, 11, Nov 2008). A key white paper (Med Phys, in press) sponsored by Elekta Corporation, was used to obtain correction factors for the ionization chambers and phantoms used in this intercomparison. Consistent results were obtained for both Elekta Gamma Knife Model 4C and Gamma Knife Perfexion units as measured with each of two miniature ionization chambers. Conclusion: The full report gives clinical history and background of gamma stereotactic radiosurgery, clinical examples and history, quality assurance recommendations and outline of possible dosimetry protocols. The report will be reviewed by the AAPM Working Group on Recommendations for Radiotherapy External Beam Quality Assurance and then by the AAPM Science Council before publication in Medical Physics Survey of possible calibration protocols for calibration of Gamma Stereotactic Radiosurgery (GSR) devices Overview of modern Quality Assurance techniques for GSR AAPM TG-218 Tolerance Levels and Methodologies for IMRT Verification QA - Moyed Miften Patient-specific IMRT QA measurement is a process designed to identify discrepancies between calculated and delivered doses. Error tolerance limits are not well-defined or consistently applied across centers. The AAPM TG-218 report has been prepared to improve the understanding and consistency of this process by providing recommendations for methodologies and tolerance limits in patient-specific IMRT QA. Learning Objectives: Review measurement methods and methodologies for absolute dose verification Provide recommendations on delivery methods, data interpretation, the use of analysis routines and choice of tolerance limits for IMRT QA Sonja Dieterich has a research agreement with Sun Nuclear Inc. Steven Goetsch is a part-time consultant for Elekta.« less

SU-E-T-195: Commissioning the Neutron Production of a Varian TrueBeam Linac

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

Irazola, L; Brualla, L; Rosello, J

2015-06-15

Purpose: The purpose of this work is the characterization of a new Varian TrueBeam™ facility in terms of neutron production, in order to estimate neutron equivalent dose in organs during radiotherapy treatments. Methods: The existing methodology [1] was used with the reference SRAMnd detector, calibrated in terms of thermal neutron fluence at the reference field operated by PTB (Physikalisch-Technische-Bundesanstalt) at the GeNF (Geesthacht-Neutron-Facility) with the GKSS reactor FRG-1 [2]. Thermal neutron fluence for the 5 available possibilities was evaluated: 15 MV and 10&6 MV with and without Flattening Filter (FF and FFF, respectively). Irradiation conditions are as described in [3].more » In addition, three different collimator-MLC configurations were studied for 15 MV: (a) collimator of 10×10 cm{sup 2} and MLC fully retracted (reference), (b) field sizes of 20×20 cm{sup 2} and 10×10 cm{sup 2} for collimator and MLC respectively, and (c) collimator and MLC aperture of 10×10 cm{sup 2}. Results: Thermal fluence rate at the “reference point” [3], as a consequence of the neutron production, obtained for (a) conformation in 15 MV is (1.45±0.11) x10{sup 4} n•cm{sup 2}/MU. Configurations (b) and (c) gave fluences of 96.6% and 97.8% of the reference (a). Neutron production decreases up to 8.6% and 5.7% for the 10 MV FF and FFF beams, respectively. Finally, it decreases up to 2.8% and 0.1% for the 6 MV FF and FFF modes, respectively. Conclusion: This work evaluates thermal neutron production of Varian TrueBeam™ system for organ equivalent dose estimation. The small difference in collimator-MLC configuration shows the universality of the methodology [3]. A decrease in this production is shown when decreasing energy from 15 to 10 MV and an almost negligible production was found for 6 MV. Moreover, a lower neutron contribution is observed for the FFF modes.[1]Phys Med Biol,2012;57:6167–6191.[2]Radiat Meas,2010;45:1513–1517.[3]Med Phys,2015;42:276–281.« less

SU-E-T-365: Estimation of Neutron Ambient Dose Equivalents for Radioprotection Exposed Workers in Radiotherapy Facilities Based On Characterization Patient Risk Estimation

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

Irazola, L; Terron, J; Sanchez-Doblado, F

2015-06-15

Purpose: Previous measurements with Bonner spheres{sup 1} showed that normalized neutron spectra are equal for the majority of the existing linacs{sup 2}. This information, in addition to thermal neutron fluences obtained in the characterization procedure{sup 3}3, would allow to estimate neutron doses accidentally received by exposed workers, without the need of an extra experimental measurement. Methods: Monte Carlo (MC) simulations demonstrated that the thermal neutron fluence distribution inside the bunker is quite uniform, as a consequence of multiple scatter in the walls{sup 4}. Although inverse square law is approximately valid for the fast component, a more precise calculation could bemore » obtained with a generic fast fluence distribution map around the linac, from MC simulations{sup 4}. Thus, measurements of thermal neutron fluences performed during the characterization procedure{sup 3}, together with a generic unitary spectra{sup 2}, would allow to estimate the total neutron fluences and H*(10) at any point{sup 5}. As an example, we compared estimations with Bonner sphere measurements{sup 1}, for two points in five facilities: 3 Siemens (15–23 MV), Elekta (15 MV) and Varian (15 MV). Results: Thermal neutron fluences obtained from characterization, are within (0.2–1.6×10{sup 6}) cm−{sup 2}•Gy{sup −1} for the five studied facilities. This implies ambient equivalent doses ranging from (0.27–2.01) mSv/Gy 50 cm far from the isocenter and (0.03–0.26) mSv/Gy at detector location with an average deviation of ±12.1% respect to Bonner measurements. Conclusion: The good results obtained demonstrate that neutron fluence and H*(10) can be estimated based on: (a) characterization procedure established for patient risk estimation in each facility, (b) generic unitary neutron spectrum and (c) generic MC map distribution of the fast component. [1] Radiat. Meas (2010) 45: 1391 – 1397; [2] Phys. Med. Biol (2012) 5 7:6167–6191; [3] Med. Phys (2015) 42:276 - 281. [4] IFMBE (2012) 39: 1245–1248. [5] ICRU Report 57 (1998)« less

Analysis of metabolic washout of positron emitters produced during carbon ion head and neck radiotherapy

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

Helmbrecht, Stephan; Enghardt, Wolfgang; Parodi, Katia

2013-09-15

Purpose: Particle Therapy Positron Emission Tomography (PT-PET) is a suitable method for verification of therapeutic dose delivery by measurements of irradiation-induced β{sup +}-activity. Due to metabolic processes in living tissue β{sup +}-emitters can be removed from the place of generation. This washout is a limiting factor for image quality. The purpose of this study is to investigate whether a washout model obtained by animal experiments is applicable to patient data.Methods: A model for the washout has been developed by Mizuno et al. [Phys. Med. Biol. 48(15), 2269–2281 (2003)] and Tomitani et al. [Phys. Med. Biol. 48(7), 875–889 (2003)]. It ismore » based upon measurements in a rabbit in living and dead conditions. This model was modified and applied to PET data acquired during the experimental therapy project at GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, Germany. Three components are expected: A fast one with a half life of 2 s, a medium one in the range of 2–3 min, and a slow component of the order of 2–3 h. Ten patients were selected randomly for investigation of the fast component. To analyze the other two components, 12 one-of-a-kind measurements from a single volunteer patient are available.Results: A fast washout on the time scale of a few seconds was not observed in the patient data. The medium processes showed a mean half life of 155.7 ± 4.6 s. This is in the expected range. Fractions of the activity not influenced by the washout were found.Conclusions: On the time scale of an in-beam or in-room measurement only the medium-time washout processes play a remarkable role. A slow component may be neglected if the measurements do not exceed 20 min after the end of the irradiation. The fast component is not observed due to the low relative blood filled volume in the brain.« less

Ethical violations and discriminatory behavior in the MedPhys Match.

PubMed

Hendrickson, Kristi R G; Juang, Titania; Rodrigues, Anna; Burmeister, Jay W

2017-09-01

The purpose of this survey study is to investigate behaviors in conflict with the ethical standards of the Medical Physics Residency (MedPhys) Match (MPM) process as stated in the MPM rules (a) and with the nondiscrimination regulations of the Equal Employment Opportunity Commission (EEOC) (b), in addition to other behaviors that may in other ways erode the fairness of the system. A survey was sent to all applicants and program directors registered for the 2015 and 2016 MPM. Survey questions asked about application, interview, and postinterview experiences, match results, and overall satisfaction with the process. Thirteen percent of 2015 respondents and 20% of 2016 respondents were asked by at least one program how highly they planned to rank them or which program they would rank first. Thirty-seven percent of 2015 and 40% of 2016 program directors indicated that candidates communicated to the program their rank intent, with 22.0% in 2015 and 12.5% in 2016 being told that their program would be ranked first. Twenty-three percent of 2015 respondents indicated being asked by at least one program during the interview about children or plans to have children; including 19% of males and 33% of females. In 2016, these values were 28% overall, 22% male, and 36% female. Fifty-seven percent of 2015 respondents who were asked this question indicated being uncomfortable or very uncomfortable answering, including 27.3% of males and 88.9% of females. In 2016, 42.9% of all respondents indicated being uncomfortable or very uncomfortable answering, including 10.0% of males and 80.0% of females. In the first two years of the MPM, there were widespread instances of ethical violations and discriminatory questioning during the interview process. Educating both interviewers and candidates on the MPM rules and general EEOC guidelines should decrease these instances and increase the fairness of the residency selection process. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

An overview of PET/MR, focused on clinical applications.

PubMed

Catalano, Onofrio Antonio; Masch, William Roger; Catana, Ciprian; Mahmood, Umar; Sahani, Dushyant Vasudeo; Gee, Michael Stanley; Menezes, Leon; Soricelli, Andrea; Salvatore, Marco; Gervais, Debra; Rosen, Bruce Robert

2017-02-01

Hybrid PET/MR scanners are innovative imaging devices that simultaneously or sequentially acquire and fuse anatomical and functional data from magnetic resonance (MR) with metabolic information from positron emission tomography (PET) (Delso et al. in J Nucl Med 52:1914-1922, 2011; Zaidi et al. in Phys Med Biol 56:3091-3106, 2011). Hybrid PET/MR scanners have the potential to greatly impact not only on medical research but also, and more importantly, on patient management. Although their clinical applications are still under investigation, the increased worldwide availability of PET/MR scanners, and the growing published literature are important determinants in their rising utilization for primarily clinical applications. In this manuscript, we provide a summary of the physical features of PET/MR, including its limitations, which are most relevant to clinical PET/MR implementation and to interpretation. Thereafter, we discuss the most important current and emergent clinical applications of such hybrid technology in the abdomen and pelvis, both in the field of oncologic and non-oncologic imaging, and we provide, when possible, a comparison with clinically consolidated imaging techniques, like for example PET/CT.

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

Li, Xinhua; Zhang, Da; Liu, Bob, E-mail: bliu7@mgh.harvard.edu

Purpose: The knowledge of longitudinal dose distribution provides the most direct view of the accumulated dose in computed tomography (CT) scanning. The purpose of this work was to perform a comprehensive study of dose distribution width and energy absorption with a wide range of subject sizes and beam irradiated lengths. Methods: Cumulative dose distribution along the z-axis was calculated based on the previously published CT dose equilibration data by Li, Zhang, and Liu [Med. Phys. 40, 031903 (10pp.) (2013)] and a mechanism for computing dose on axial lines by Li, Zhang, and Liu [Med. Phys. 39, 5347–5352 (2012)]. Full widthmore » at half maximum (FWHM), full width at tenth maximum (FWTM), the total energy (E) absorbed in a small cylinder of unit mass per centimeter square about the central or peripheral axis, and the energy (E{sub in}) absorbed inside irradiated length (L) were subsequently extracted from the dose distribution. Results: Extensive results of FWHM, FWTM, and E{sub in}/E were presented on the central and peripheral axes of infinitely long PMMA (diameters 6–50 cm) and water (diameters 6–55 cm) cylinders with L < 100 cm. FWHM was greater than the primary beam width only on the central axes of large phantoms and also with L ranging from a few centimeter to about 33 cm. FWTM generally increased with phantom diameter, and could be up to 32 cm longer than irradiated length, depending on L, phantom diameter and axis, but was insensitive to phantom material (PMMA or water). E{sub in}/E increased with L and asymptotically approached unity for large L. As phantom diameter increased, E{sub in}/E generally decreased, but asymptotically approached constant levels on the peripheral axes of large phantoms. A heuristic explanation of dose distribution width results was presented. Conclusions: This study enables the reader to gain a comprehensive view of dose distribution width and energy absorption and provides useful data for estimating doses to organs inside or beyond the irradiated region. The dose length product (DLP) presented by CT scanners is equal to neither E nor E{sub in}. Both E and E{sub in} can be evaluated using the equations and results presented in this paper and are robust with both constant and variable tube current scanning techniques.« less

Far Infrared, Magnetic and Electronic Studies of High Tc Superconducting Materials

DTIC Science & Technology

1992-09-30

Phys. Rev. Left. 63, 2421(1989). 8. K. H. Fischer and T. Nattermann, Phys. Rev. .43, 10372(1991). 9. R. E. Walstedt, R. F. Bell, and D. B. Mitzi , Phys...Duran, J. Yazyi, F. dela Cruz, D. J. Bishop, D. B. Mitzi , and A. Kapitulnik, Phys. Rev. B 44, 17737(1991). 14. Y. Yeshurun and A. P. Malozemoff, Phys

SU-G-TeP3-09: Proton Minibeam Radiation Therapy Increases Normal Tissue Resistance

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

Prezado, Y; Gonzalez-Infantes, W; Juchaux, M

Purpose: The dose tolerances of normal tissues continue being the main limitation in radiotherapy. To overcome it, we recently proposed a novel concept: proton minibeam radiation therapy (pMBRT) [1]. It allies the physical advantages of protons with the normal tissue preservation observed when irradiated with submillimetric spatially fractionated beams (minibeam radiation therapy) [2]. The dose distributions are such that the tumor receives a homogeneous dose distribution, while normal tissues benefit from the spatial fractionation of the dose. The objective of our work was to implement this promising technique at a clinical center (Proton therapy center in Orsay) in order tomore » evaluate the potential gain in tissue sparing. Methods: Dose distributions were measured by means of gafchromic films and a PTW microdiamond detector (60019). Once the dosimetry was established, the whole brain of 7 weeks old male Fischer 344 rats was irradiated. Half of the animals received conventional seamless proton irradiation (25 Gy in one fraction). The other rats were irradiated with pMBRT (58 Gy peak dose in one fraction). The average dose deposited in the same targeted volume was in both cases 25 Gy. Results: The first complete set of dosimetric data in such small proton field sizes was obtained [3]. Rats treated with conventional proton irradiation exhibited severe moist desquamation and permanent epilation afterwards. The minibeam group, on the other hand, exhibited no skin damage and no clinical symptoms. MRI imaging and histological analysis are planned at 6 months after irradiation. Conclusion: Our preliminary results indicate that pMBRT leads to an increase in tissue resistance. This can open the door to an efficient treatment of very radioresistant tumours. [1] Prezado et al. Med. Phys. 40, 031712, 1–8 (2013).[2] Prezado et al., Rad. Research. 184, 314-21 (2015). [3] Peucelle et al., Med. Phys. 42 7108-13 (2015).« less

Interior region-of-interest reconstruction using a small, nearly piecewise constant subregion

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

Taguchi, Katsuyuki; Xu Jingyan; Srivastava, Somesh

2011-03-15

Purpose: To develop a method to reconstruct an interior region-of-interest (ROI) image with sufficient accuracy that uses differentiated backprojection (DBP) projection onto convex sets (POCS) [H. Kudo et al., ''Tiny a priori knowledge solves the interior problem in computed tomography'', Phys. Med. Biol. 53, 2207-2231 (2008)] and a tiny knowledge that there exists a nearly piecewise constant subregion. Methods: The proposed method first employs filtered backprojection to reconstruct an image on which a tiny region P with a small variation in the pixel values is identified inside the ROI. Total variation minimization [H. Yu and G. Wang, ''Compressed sensing basedmore » interior tomography'', Phys. Med. Biol. 54, 2791-2805 (2009); W. Han et al., ''A general total variation minimization theorem for compressed sensing based interior tomography'', Int. J. Biomed. Imaging 2009, Article 125871 (2009)] is then employed to obtain pixel values in the subregion P, which serve as a priori knowledge in the next step. Finally, DBP-POCS is performed to reconstruct f(x,y) inside the ROI. Clinical data and the reconstructed image obtained by an x-ray computed tomography system (SOMATOM Definition; Siemens Healthcare) were used to validate the proposed method. The detector covers an object with a diameter of {approx}500 mm. The projection data were truncated either moderately to limit the detector coverage to diameter 350 mm of the object or severely to cover diameter 199 mm. Images were reconstructed using the proposed method. Results: The proposed method provided ROI images with correct pixel values in all areas except near the edge of the ROI. The coefficient of variation, i.e., the root mean square error divided by the mean pixel values, was less than 2.0% or 4.5% with the moderate or severe truncation cases, respectively, except near the boundary of the ROI. Conclusions: The proposed method allows for reconstructing interior ROI images with sufficient accuracy with a tiny knowledge that there exists a nearly piecewise constant subregion.« less

Series of (2+1)-dimensional stable self-dual interacting conformal field theories

NASA Astrophysics Data System (ADS)

Cheng, Meng; Xu, Cenke

2016-12-01

Using the duality between seemingly different (2+1)-dimensional [(2 +1 )d ] conformal field theories (CFT) proposed recently [D. T. Son, Phys. Rev. X 5, 031027 (2015), 10.1103/PhysRevX.5.031027; M. A. Metlitski and A. Vishwanath, Phys. Rev. B 93, 245151 (2016), 10.1103/PhysRevB.93.245151; C. Wang and T. Senthil, Phys. Rev. X 6, 011034 (2015), 10.1103/PhysRevX.6.011034; C. Wang and T. Senthil, Phys. Rev. X 5, 041031 (2015), 10.1103/PhysRevX.5.041031; C. Wang and T. Senthil, Phys. Rev. B 93, 085110 (2016), 10.1103/PhysRevB.93.085110; C. Xu and Y.-Z. You, Phys. Rev. B 92, 220416 (2015), 10.1103/PhysRevB.92.220416; D. F. Mross et al., Phys. Rev. Lett. 117, 016802 (2016), 10.1103/PhysRevLett.117.016802; A. Karch and D. Tong, arXiv:1606.01893; N. Seiberg et al., arXiv:1606.01989; P.-S. Hsin and N. Seiberg, arXiv:1607.07457], we study a series of (2 +1 )d stable self-dual interacting CFTs. These CFTs can be realized (for instance) on the boundary of the 3 d bosonic topological insulator protected by U(1) and time-reversal symmetry (T ), and they remain stable as long as these symmetries are preserved. When realized as a boundary system, these CFTs can be driven into anomalous fractional quantum Hall states once T is broken. We demonstrate that the newly proposed dualities allow us to study these CFTs quantitatively through a controlled calculation, without relying on a large flavor number of matter fields. We also propose a numerical test for our results, which would provide strong evidence for the originally proposed duality between Dirac fermion and QED.

Shock-wave ion acceleration by an ultra-relativistic short laser pulse

NASA Astrophysics Data System (ADS)

Zhidkov, A.; Batishchev, O.; Uesaka, M.

2002-11-01

Research on ion acceleration by intense short laser pulses grows in the last few years [1-9] because of various applications. However, the study is mainly focused on the forward ion acceleration. We study ion inward acceleration, which in contrast to other mechanisms has density of ions per unit energy not decreased with the laser intensity [8]. Magnetic field generated due to a finite size of laser spot can affect electron distribution. In the present work we study the effect of magnetic field on the shock wave formation and ion acceleration in a solid target via 2D PIC and Vlasov simulation. Though the PIC simulation can provide detailed information, in relativistic plasmas it may not calculate B correctly: (i) too many particles are needed to make B disappeared in thermal plasmas, (ii) local scheme [10] does not satisfy curl(Epl)=0. Therefore, two approaches are used in the present study. [1] S. P. Hatchett et al., Phys. Plas. 7, 2076 (2000); [2] A. Maksimchuk et al., Phys. Rev. Lett. 84, 4108 (2000); [3] E.L. Clark et al., Phys. Rev. Lett. 85, 1654 (2000); [4] A. Zhidkov et al., Phys. Rev. E60, 3273 (1999); E61, R2224 (2000); [5] Y. Murakami et al, Phys. Plasmas 8,4138 (2001); [6] T.Zh. Esirkepov et al, JETP Lett. 70, 82 (1999); [7] A. Pukhov, Phys. Rev. Lett. 86, 3562(2001); [8] A.A. Andreev et al., Plasma Phys. Contr. Fusion (2002); [9] O.V. Batishchev et al., Plasma Phys. Rep. 20, 587 (1994); [10] J. Villasenor et al., Comp. Phys. Comm. 69, 306 (1992).

NOTE: A BPF-type algorithm for CT with a curved PI detector

NASA Astrophysics Data System (ADS)

Tang, Jie; Zhang, Li; Chen, Zhiqiang; Xing, Yuxiang; Cheng, Jianping

2006-08-01

Helical cone-beam CT is used widely nowadays because of its rapid scan speed and efficient utilization of x-ray dose. Recently, an exact reconstruction algorithm for helical cone-beam CT was proposed (Zou and Pan 2004a Phys. Med. Biol. 49 941 59). The algorithm is referred to as a backprojection-filtering (BPF) algorithm. This BPF algorithm for a helical cone-beam CT with a flat-panel detector (FPD-HCBCT) requires minimum data within the Tam Danielsson window and can naturally address the problem of ROI reconstruction from data truncated in both longitudinal and transversal directions. In practical CT systems, detectors are expensive and always take a very important position in the total cost. Hence, we work on an exact reconstruction algorithm for a CT system with a detector of the smallest size, i.e., a curved PI detector fitting the Tam Danielsson window. The reconstruction algorithm is derived following the framework of the BPF algorithm. Numerical simulations are done to validate our algorithm in this study.

A BPF-type algorithm for CT with a curved PI detector.

PubMed

Tang, Jie; Zhang, Li; Chen, Zhiqiang; Xing, Yuxiang; Cheng, Jianping

2006-08-21

Helical cone-beam CT is used widely nowadays because of its rapid scan speed and efficient utilization of x-ray dose. Recently, an exact reconstruction algorithm for helical cone-beam CT was proposed (Zou and Pan 2004a Phys. Med. Biol. 49 941-59). The algorithm is referred to as a backprojection-filtering (BPF) algorithm. This BPF algorithm for a helical cone-beam CT with a flat-panel detector (FPD-HCBCT) requires minimum data within the Tam-Danielsson window and can naturally address the problem of ROI reconstruction from data truncated in both longitudinal and transversal directions. In practical CT systems, detectors are expensive and always take a very important position in the total cost. Hence, we work on an exact reconstruction algorithm for a CT system with a detector of the smallest size, i.e., a curved PI detector fitting the Tam-Danielsson window. The reconstruction algorithm is derived following the framework of the BPF algorithm. Numerical simulations are done to validate our algorithm in this study.

Comment on ‘Monte Carlo calculated microdosimetric spread for cell nucleus-sized targets exposed to brachytherapy 125I and 192Ir sources and 60Co cell irradiation’

NASA Astrophysics Data System (ADS)

Lindborg, Lennart; Lillhök, Jan; Grindborg, Jan-Erik

2015-11-01

The relative standard deviation, σr,D, of calculated multi-event distributions of specific energy for 60Co ϒ rays was reported by the authors F Villegas, N Tilly and A Ahnesjö (Phys. Med. Biol. 58 6149-62). The calculations were made with an upgraded version of the Monte Carlo code PENELOPE. When the results were compared to results derived from experiments with the variance method and simulated tissue equivalent volumes in the micrometre range a difference of about 50% was found. Villegas et al suggest wall-effects as the likely explanation for the difference. In this comment we review some publications on wall-effects and conclude that wall-effects are not a likely explanation.

Comment on 'Monte Carlo calculated microdosimetric spread for cell nucleus-sized targets exposed to brachytherapy (125)I and (192)Ir sources and (60)Co cell irradiation'.

PubMed

Lindborg, Lennart; Lillhök, Jan; Grindborg, Jan-Erik

2015-11-07

The relative standard deviation, σr,D, of calculated multi-event distributions of specific energy for (60)Co ϒ rays was reported by the authors F Villegas, N Tilly and A Ahnesjö (Phys. Med. Biol. 58 6149-62). The calculations were made with an upgraded version of the Monte Carlo code PENELOPE. When the results were compared to results derived from experiments with the variance method and simulated tissue equivalent volumes in the micrometre range a difference of about 50% was found. Villegas et al suggest wall-effects as the likely explanation for the difference. In this comment we review some publications on wall-effects and conclude that wall-effects are not a likely explanation.

Dual energy exposure control (DEEC) for computed tomography: algorithm and simulation study.

PubMed

Stenner, Philip; Kachelriess, Marc

2008-11-01

DECT means acquiring the same object at two different energies, respectively two different tube voltages U1 and U2. The raw data q1 and q2 undergo a decomposition process of type p = p(q1,q2). The raw data p are reconstructed to obtain monochromatic images of the attenuation mu, of the object density rho, or of a specific material distribution. Recent advances in DECT focus on noise reduction techniques [S. Richard and J. H. Siewerdsen, Med. Phys. 35(2), 586-600 (2008)] and enable high performance DECT such as lung nodule detection [Shkumat et al., Med. Phys. 35(2), 629-632 (2008)]. Given p and a raw data-based projection-wise patient dose estimation D(alpha) the authors determine the optimal tube current curves I1(alpha) and I2(alpha), with alpha being the view angle, which minimizes image noise for a given patient dose level. DEEC can perform online; I1(alpha) and I2(alpha) can be determined during the scan. Simulation studies using semianthropomorphic phantom data were carried out. In particular, functions p that generate mu-images and density images were evaluated. Image quality was compared to standard scans at U0=120 kV (clinical CT) and U0=45 kV (micro-CT) that were taken at the same dose level (D0=D1 + D2) and identical spatial resolution. Appropriate choice of p(q1, q2) allows to obtain mu-images that show fewer artifacts and yield image noise levels comparable to the noise of the standard scan. The authors compared the standard scan to mu-images at 70 keV, which is the effective energy used in clinical CT, and found optimal results with mu-images at 25 keV for micro-CT. Nonoptimal choice of the decomposition function will, however, significantly increase image noise. In particular mu-images at 511 keV, as needed for PET/CT attenuation correction, exhibit more than twice as much image noise as the standard scan. With DEEC, which guarantees best dose usage possible, monochromatic images are generated with only slightly increased noise levels at the same dose compared to a standard scan. The benefit of significantly decreased artifacts appears to allow using DEEC-generated monochromatic images in daily routine. Furthermore, DEEC is not restricted to DECT and the inherent tube current modulation algorithm may also be applied to single energy CT.

Dual energy exposure control (DEEC) for computed tomography: Algorithm and simulation study

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

Stenner, Philip; Kachelriess, Marc

2008-11-15

DECT means acquiring the same object at two different energies, respectively two different tube voltages U{sub 1} and U{sub 2}. The raw data q{sub 1} and q{sub 2} undergo a decomposition process of type p=p(q{sub 1},q{sub 2}). The raw data p are reconstructed to obtain monochromatic images of the attenuation {mu}, of the object density {rho}, or of a specific material distribution. Recent advances in DECT focus on noise reduction techniques [S. Richard and J. H. Siewerdsen, Med. Phys. 35(2), 586-600 (2008)] and enable high performance DECT such as lung nodule detection [Shkumat et al., Med. Phys. 35(2), 629-632 (2008)].more » Given p and a raw data-based projection-wise patient dose estimation D({alpha}) the authors determine the optimal tube current curves I{sub 1}({alpha}) and I{sub 2}({alpha}), with {alpha} being the view angle, which minimizes image noise for a given patient dose level. DEEC can perform online; I{sub 1}({alpha}) and I{sub 2}({alpha}) can be determined during the scan. Simulation studies using semianthropomorphic phantom data were carried out. In particular, functions p that generate {mu}-images and density images were evaluated. Image quality was compared to standard scans at U{sub 0}=120 kV (clinical CT) and U{sub 0}=45 kV (micro-CT) that were taken at the same dose level (D{sub 0}=D{sub 1}+D{sub 2}) and identical spatial resolution. Appropriate choice of p(q{sub 1},q{sub 2}) allows to obtain {mu}-images that show fewer artifacts and yield image noise levels comparable to the noise of the standard scan. The authors compared the standard scan to {mu}-images at 70 keV, which is the effective energy used in clinical CT, and found optimal results with {mu}-images at 25 keV for micro-CT. Nonoptimal choice of the decomposition function will, however, significantly increase image noise. In particular {mu}-images at 511 keV, as needed for PET/CT attenuation correction, exhibit more than twice as much image noise as the standard scan. With DEEC, which guarantees best dose usage possible, monochromatic images are generated with only slightly increased noise levels at the same dose compared to a standard scan. The benefit of significantly decreased artifacts appears to allow using DEEC-generated monochromatic images in daily routine. Furthermore, DEEC is not restricted to DECT and the inherent tube current modulation algorithm may also be applied to single energy CT.« less

Comment on 'Three-dimensional numerical investigation of electron transport with rotating spoke in a cylindrical anode layer Hall plasma accelerator'[Phys. Plasmas 19, 073519 (2012)

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

Ellison, C. L.; Parker, J. B.; Raitses, Y.

The oscillation behavior described by Tang et al.[Phys. Plasmas 19, 073519 (2012)] differs too greatly from previous experimental and numerical studies to claim observation of the same phenomenon. Most significantly, the rotation velocity by Tang et al.[Phys. Plasmas 19, 073519 (2012)] is three orders of magnitude larger than that of typical 'rotating spoke' phenomena. Several physical and numerical considerations are presented to more accurately understand the numerical results of Tang et al.[Phys. Plasmas 19, 073519 (2012)] in light of previous studies.

A study of the turn-up effect in the electron momentum spectroscopy

NASA Astrophysics Data System (ADS)

Dal Cappello, C.; Menas, F.; Houamer, S.; Popov, Yu V.; Roy, A. C.

2015-10-01

Recently, a number of electron momentum spectroscopy measurements for the ionization of atoms and molecules have shown that the triple differential cross section (TDCS) has an unexpected higher intensity in a low momentum regime (Brunger M J, Braidwood S W, Mc Carthy I E and Weigold E 1994 J. Phys. B: At. Mol. Opt. Phys. 27 L597, Hollebone B P, Neville J J, Zheng Y, Brion C E, Wang Y and Davidson E R 1995 Chem. Phys. 196 13, Brion C E, Zheng Y, Rolke J, Neville J J, McCarthy I E and Wang J 1998 J. Phys. B: At. Mol. Opt. Phys. 31 L223, Ren X G, Ning C G, Deng J K, Zhang S F, Su G L, Huang F and Li G Q 2005 Phys. Rev. Lett. 94 163201, Deng J K, et al 2001 J. Chem. Phys. 114 882, Ning C G, Ren X G, Deng J K, Su G L, Zhang S F and Li G Q 2006 Phys. Rev. A 73 022704). This surprising result is now called the turn-up effect. Our aim is to investigate such an effect by studying the case of the ionization of atomic hydrogen in an excited state using the 3C model (Brauner M, Briggs J S and Klar H 1989 J. Phys. B: At. Mol. Opt. Phys. 22 2265) which is able to describe all the measured results of the single ionization of atomic hydrogen in its ground state for an incident energy beyond 200 eV. A comparison is also made of the findings of the present method with those of the plane wave impulse approximation and distorted wave models.

Characterization of a prototype MR-compatible Delta4 QA system in a 1.5 tesla MR-linac

NASA Astrophysics Data System (ADS)

de Vries, J. H. W.; Seravalli, E.; Houweling, A. C.; Woodings, S. J.; van Rooij, R.; Wolthaus, J. W. H.; Lagendijk, J. J. W.; Raaymakers, B. W.

2018-01-01

To perform patient plan quality assurance (QA) on a newly installed MR-linac (MRL) it is necessary to have an MR-compatible QA device. An MR compatible device (MR-Delta4) has been developed together with Scandidos AB (Uppsala, Sweden). The basic characteristics of the detector response, such as short-term reproducibility, dose linearity, field size dependency, dose rate dependency, dose-per-pulse dependency and angular dependency, were investigated for the clinical Delta4-PT as well as for the MR compatible version. All tests were performed with both devices on a conventional linac and the MR compatible device was tested on the MRL as well. No statistically significant differences were found in the short-term reproducibility (<0.1%), dose linearity (⩽0.5%), field size dependency (<2.0% for field sizes larger than 5  ×  5 cm2), dose rate dependency (<1.0%) or angular dependency for any phantom/linac combination. The dose-per-pulse dependency (<0.8%) was found to be significantly different between the two devices. This difference can be explained by the fact that the diodes in the clinical Delta4-PT were irradiated with a much larger dose than the MR-Delta4-PT ones. The absolute difference between the devices (<0.5%) was found to be small, so no clinical impact is expected. For both devices, the results were consistent with the characteristics of the Delta4-PT device reported in the literature (Bedford et al 2009 Phys. Med. Biol. 54 N167-76 Sadagopan et al 2009 J. Appl. Clin. Med. Phys. 10 2928). We found that the characteristics of the MR compatible Delta4 phantom were found to be comparable to the clinically used one. Also, the found characteristics do not differ from the previously reported characteristics of the commercially available non-MR compatible Delta4-PT phantom. Therefore, the MR compatible Delta4 prototype was found to be safe and effective for use in the 1.5 tesla magnetic field of the Elekta MR-linac

The origin of the flatbed scanner artifacts in radiochromic film dosimetry—key experiments and theoretical descriptions

NASA Astrophysics Data System (ADS)

Schoenfeld, Andreas A.; Wieker, Soeren; Harder, Dietrich; Poppe, Bjoern

2016-11-01

The optical origin of the lateral response and orientation artifacts, which occur when using EBT3 and EBT-XD radiochromic films together with flatbed scanners, has been reinvestigated by experimental and theoretical means. The common feature of these artifacts is the well-known parabolic increase in the optical density OD(x)  =  -log10 I(x)/I 0(x) versus offset x from the scanner midline (Poppinga et al 2014 Med. Phys. 41 021707). This holds for landscape and portrait orientations as well as for the three color channels. Dose-independent optical subjects, such as neutral density filters, linear polarizers, the EBT polyester foil and diffusive glass, also present the parabolic lateral artifact when scanned with a flatbed scanner. The curvature parameter c of the parabola function OD(x)  =  c 0  +  cx 2 is found to be a linear function of the dose, the parameters of which are influenced by the film orientation and film type, EBT3 or EBT-XD. The ubiquitous parabolic shape of function OD(x) is attributed (a) to the optical path-length effect (van Battum et al 2016 Phys. Med. Biol. 61 625-49), due to the increasing obliquity of the optical scanner light associated with increasing offset x from the scanner midline, and (b) and (c) to the partial polarization and scattering of the light leaving the film, which affect the ratio ~I(x)/{{I}0}(x) , thus making OD(x) increase with x 2. The orientation effect results from the changes of effects (b) and (c) associated with turning the film position, and thereby the orientation of the polymer structure of the sensitive film layer. In a comparison of experimental results obtained with selected optical subjects, the relative weights of the contributions of the optical path-length effect and the polarization and scattering of light leaving the films to the lateral response artifact have been estimated to be of the same order of magnitude. Mathematical models of these causes for the parabolic shape of function OD(x) are given as appendices.

The origin of the flatbed scanner artifacts in radiochromic film dosimetry-key experiments and theoretical descriptions.

PubMed

Schoenfeld, Andreas A; Wieker, Soeren; Harder, Dietrich; Poppe, Bjoern

2016-11-07

The optical origin of the lateral response and orientation artifacts, which occur when using EBT3 and EBT-XD radiochromic films together with flatbed scanners, has been reinvestigated by experimental and theoretical means. The common feature of these artifacts is the well-known parabolic increase in the optical density OD(x)  =  -log 10 I(x)/I 0 (x) versus offset x from the scanner midline (Poppinga et al 2014 Med. Phys. 41 021707). This holds for landscape and portrait orientations as well as for the three color channels. Dose-independent optical subjects, such as neutral density filters, linear polarizers, the EBT polyester foil and diffusive glass, also present the parabolic lateral artifact when scanned with a flatbed scanner. The curvature parameter c of the parabola function OD(x)  =  c 0   +  cx 2 is found to be a linear function of the dose, the parameters of which are influenced by the film orientation and film type, EBT3 or EBT-XD. The ubiquitous parabolic shape of function OD(x) is attributed (a) to the optical path-length effect (van Battum et al 2016 Phys. Med. Biol. 61 625-49), due to the increasing obliquity of the optical scanner light associated with increasing offset x from the scanner midline, and (b) and (c) to the partial polarization and scattering of the light leaving the film, which affect the ratio [Formula: see text], thus making OD(x) increase with x 2 . The orientation effect results from the changes of effects (b) and (c) associated with turning the film position, and thereby the orientation of the polymer structure of the sensitive film layer. In a comparison of experimental results obtained with selected optical subjects, the relative weights of the contributions of the optical path-length effect and the polarization and scattering of light leaving the films to the lateral response artifact have been estimated to be of the same order of magnitude. Mathematical models of these causes for the parabolic shape of function OD(x) are given as appendices.

Reply to "Comment on `Troublesome aspects of the Renyi-MaxEnt treatment' "

NASA Astrophysics Data System (ADS)

Plastino, A.; Rocca, M. C.; Pennini, F.

2017-11-01

This Reply is intended as a refutation of the preceding Comment [Oikonomou and Bagci, Phys. Rev. E 96, 056101 (2017), 10.1103/PhysRevE.96.056101] on our paper [Plastino et al., Phys. Rev. E 94, 012145 (2016)., 10.1103/PhysRevE.94.012145]. We show that the Tsallis probability distribution of our paper does not coincide with the Tsallis distribution studied by Oikonomou and Bagci. Consequently, their findings do not apply to our paper.

Reply to "Comment on 'Troublesome aspects of the Renyi-MaxEnt treatment' ".

PubMed

Plastino, A; Rocca, M C; Pennini, F

2017-11-01

This Reply is intended as a refutation of the preceding Comment [Oikonomou and Bagci, Phys. Rev. E 96, 056101 (2017)10.1103/PhysRevE.96.056101] on our paper [Plastino et al., Phys. Rev. E 94, 012145 (2016).1539-375510.1103/PhysRevE.94.012145]. We show that the Tsallis probability distribution of our paper does not coincide with the Tsallis distribution studied by Oikonomou and Bagci. Consequently, their findings do not apply to our paper.

Lithotripter shock wave interaction with a bubble near various biomaterials.

PubMed

Ohl, S W; Klaseboer, E; Szeri, A J; Khoo, B C

2016-10-07

Following previous work on the dynamics of an oscillating bubble near a bio-material (Ohl et al 2009 Phys. Med. Biol. 54 6313-36) and the interaction of a bubble with a shockwave (Klaseboer et al 2007 J. Fluid Mech. 593 33-56), the present work concerns the interaction of a gas bubble with a traveling shock wave (such as from a lithotripter) in the vicinity of bio-materials such as fat, skin, muscle, cornea, cartilage, and bone. The bubble is situated in water (to represent a water-like biofluid). The bubble collapses are not spherically symmetric, but tend to feature a high speed jet. A few simulations are performed and compared with available experimental observations from Sankin and Zhong (2006 Phys. Rev. E 74 046304). The collapses of cavitation bubbles (created by laser in the experiment) near an elastic membrane when hit by a lithotripter shock wave are correctly captured by the simulation. This is followed by a more systematic study of the effects involved concerning shockwave bubble biomaterial interactions. If a subsequent rarefaction wave hits the collapsed bubble, it will re-expand to a very large size straining the bio-materials nearby before collapsing once again. It is noted that, for hard bio-material like bone, reflection of the shock wave at the bone-water interface can affect the bubble dynamics. Also the initial size of the bubble has a significant effect. Large bubbles (∼1 mm) will split into smaller bubbles, while small bubbles collapse with a high speed jet in the travel direction of the shock wave. The numerical model offers a computationally efficient way of understanding the complex phenomena involving the interplay of a bubble, a shock wave, and a nearby bio-material.

Lithotripter shock wave interaction with a bubble near various biomaterials

NASA Astrophysics Data System (ADS)

Ohl, S. W.; Klaseboer, E.; Szeri, A. J.; Khoo, B. C.

2016-10-01

Following previous work on the dynamics of an oscillating bubble near a bio-material (Ohl et al 2009 Phys. Med. Biol. 54 6313-36) and the interaction of a bubble with a shockwave (Klaseboer et al 2007 J. Fluid Mech. 593 33-56), the present work concerns the interaction of a gas bubble with a traveling shock wave (such as from a lithotripter) in the vicinity of bio-materials such as fat, skin, muscle, cornea, cartilage, and bone. The bubble is situated in water (to represent a water-like biofluid). The bubble collapses are not spherically symmetric, but tend to feature a high speed jet. A few simulations are performed and compared with available experimental observations from Sankin and Zhong (2006 Phys. Rev. E 74 046304). The collapses of cavitation bubbles (created by laser in the experiment) near an elastic membrane when hit by a lithotripter shock wave are correctly captured by the simulation. This is followed by a more systematic study of the effects involved concerning shockwave bubble biomaterial interactions. If a subsequent rarefaction wave hits the collapsed bubble, it will re-expand to a very large size straining the bio-materials nearby before collapsing once again. It is noted that, for hard bio-material like bone, reflection of the shock wave at the bone—water interface can affect the bubble dynamics. Also the initial size of the bubble has a significant effect. Large bubbles (˜1 mm) will split into smaller bubbles, while small bubbles collapse with a high speed jet in the travel direction of the shock wave. The numerical model offers a computationally efficient way of understanding the complex phenomena involving the interplay of a bubble, a shock wave, and a nearby bio-material.

The effect of intrinsic attenuation correction methods on the stationarity of the 3-D modulation transfer function of SPECT.

PubMed

Glick, S J; Hawkins, W G; King, M A; Penney, B C; Soares, E J; Byrne, C L

1992-01-01

The application of stationary restoration techniques to SPECT images assumes that the modulation transfer function (MTF) of the imaging system is shift invariant. It was hypothesized that using intrinsic attenuation correction (i.e., methods which explicitly invert the exponential radon transform) would yield a three-dimensional (3-D) MTF which varies less with position within the transverse slices than the combined conjugate view two-dimensional (2-D) MTF varies with depth. Thus the assumption of shift invariance would become less of an approximation for 3-D post- than for 2-D pre-reconstruction restoration filtering. SPECT acquisitions were obtained from point sources located at various positions in three differently shaped, water-filled phantoms. The data were reconstructed with intrinsic attenuation correction, and 3-D MTFs were calculated. Four different intrinsic attenuation correction methods were compared: (1) exponentially weighted backprojection, (2) a modified exponentially weighted backprojection as described by Tanaka et al. [Phys. Med. Biol. 29, 1489-1500 (1984)], (3) a Fourier domain technique as described by Bellini et al. [IEEE Trans. ASSP 27, 213-218 (1979)], and (4) the circular harmonic transform (CHT) method as described by Hawkins et al. [IEEE Trans. Med. Imag. 7, 135-148 (1988)]. The dependence of the 3-D MTF obtained with these methods, on point source location within an attenuator, and on shape of the attenuator, was studied. These 3-D MTFs were compared to: (1) those MTFs obtained with no attenuation correction, and (2) the depth dependence of the arithmetic mean combined conjugate view 2-D MTFs.(ABSTRACT TRUNCATED AT 250 WORDS)

Unified Theory of Plasma Correlations.

DTIC Science & Technology

1983-06-13

or more generally, the Balescu -Lenard Equation. 2 6 -3 3 An essential element of these studies is that the correlation functions are assumed to be... Balescu , Phys. Fluids 3, 52 (1960). 27. A. Lenard, Ann. Phys. (N.Y.) 3, 390 (1960). 28. R. L. Liboff and A. H. Merchant, J. Math. Phys. 14, 119 (1973

Pion distribution amplitude from Euclidean correlation functions

NASA Astrophysics Data System (ADS)

Bali, Gunnar S.; Braun, Vladimir M.; Gläßle, Benjamin; Göckeler, Meinulf; Gruber, Michael; Hutzler, Fabian; Korcyl, Piotr; Lang, Bernhard; Schäfer, Andreas; Wein, Philipp; Zhang, Jian-Hui

2018-03-01

Following the proposal in (Braun and Müller. Eur Phys J C55:349, 2008), we study the feasibility to calculate the pion distribution amplitude (DA) from suitably chosen Euclidean correlation functions at large momentum. In our lattice study we employ the novel momentum smearing technique (Bali et al. Phys Rev D93:094515, 2016; Bali et al. Phys Lett B774:91, 2017). This approach is complementary to the calculations of the lowest moments of the DA using the Wilson operator product expansion and avoids mixing with lower dimensional local operators on the lattice. The theoretical status of this method is similar to that of quasi-distributions (Ji. Phys Rev Lett 110:262002, 2013) that have recently been used in (Zhang et al. Phys Rev D95:094514, 2017) to estimate the twist two pion DA. The similarities and differences between these two techniques are highlighted.

α-decay systematics for superheavy elements

NASA Astrophysics Data System (ADS)

Duarte, S. B.; Teruya, N.

2012-01-01

In this Brief Report we extend the α-decay half-life calculation to the superheavy emitter region to verify whether these nuclei satisfy the recently observed systematics [D. N. Poenaru , Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.83.014601 83, 014601 (2011);C. Qi , Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.80.044326 80, 044326 (2009)]. To establish the systematics, we have used the α-cluster potential description, which was originally developed to study α decay in connection with nuclear energy level structure [B. Buck , Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.51.559 51, 559 (1995)]. The quantum-mechanical tunneling calculation has been employed to obtain the half-lives, showing that with this treatment the systematics are well reproduced in the region of heavy nuclei. Finally, the half-life calculation has been extended to the superheavy emitters to verify whether the systematics can still be observed.

Special issue: diagnostics of atmospheric pressure microplasmas

NASA Astrophysics Data System (ADS)

Bruggeman, Peter; Czarnetzki, Uwe; Tachibana, Kunihide

2013-11-01

In recent decades, a strong revival of non-equilibrium atmospheric pressure plasma studies has developed in the form of microplasmas. Microplasmas have typical scales of 1 mm or less and offer a very exciting research direction in the field of plasma science and technology as the discharge physics can be considerably different due to high collisionality and the importance of plasma-surface interaction. These high-pressure small-scale plasmas have a diverse range of physical and chemical properties. This diversity coincides with various applications including light/UV sources [1], material processing [2], chemical analysis [3], material synthesis [4], electromagnetics [5], combustion [6] and even medicine [7]. At atmospheric pressure, large scale plasmas have the tendency to become unstable due to the high collision rates leading to enhanced heating and ionization compared to their low-pressure counterparts. As low-pressure plasmas typically operate in reactors with sizes of tens of centimetres, scaling up the pressure to atmospheric pressure the size of the plasma reduces to typical sizes below 1 mm. A natural approach of stabilizing atmospheric pressure plasmas is thus the use of microelectrode geometries. Traditionally microplasmas have been produced in confined geometries which allow one to stabilize dc excited discharges. This stabilization is intrinsically connected to the large surface-to-volume ratio which enhances heat transfer and losses of charged and excited species to the walls. Currently challenging boundaries are pushed by producing microcavity geometries with dimensions of the order of 1 µm [8]. The subject of this special issue, diagnostics of microplasmas, is motivated by the many challenges in microplasma diagnostics in view of the complex chemistry and strong spatial (and even temporal) gradients of species densities and plasma properties. Atmospheric pressure plasmas have a very long history dating back more than 100 years, with early work of, e.g. Werner von Siemens [9], who studied a dielectric barrier discharge (DBD) in the context of ozone generation. DBD discharges often consist of numerous filamentary discharges which are inherently transient in nature and with a characteristic size similar to the dimensions of microplasmas. Several groups are investigating the stabilization of such plasma filaments to perform temporal and spatial resolved diagnostics. To this end and due to the many similar challenges for diagnostics, this type of discharge is also included in this special issue. Research on microplasmas is performed in many groups spread all over the world, and a biannual workshop is devoted to the topic. The 7th edition of this International Workshop on Microplasmas was held in Beijing in May 2013. Large research programs consisting of clusters of research labs such as in Japan, Germany, France and the USA have been producing a wealth of information available in the literature. As the editors of this special issue, we are very pleased to have attracted a collection of excellent papers from leading experts in the field covering most of the current diagnostics performed in microplasmas. As an introduction to the regular special issue papers, a review paper is included [10]. It describes the key characteristics of atmospheric pressure plasmas and microplasmas in particular, and reviews the state of the art in plasma diagnostics. Special attention has been given in this review to highlighting the issues and challenges to probe microplasmas. The regular papers cover a large range of different diagnostics including coherent anti-Stokes Raman scattering (CARS) [11], (two-photon) laser induced fluorescence ((Ta)LIF) [12, 13, 18, 24], absorption spectroscopy [13-18], optical emission spectroscopy [12, 16-21, 24], imaging [22, 23], surface diagnostics [24, 25] and mass spectrometry [26, 27]. Different aspects of microplasmas are broadly investigated from a perspective of diagnostics, modelling and applications. Diagnostics are pivotal to both the development of models and the optimization and exploration of novel applications. Consequently, this special issue is focused on the various aspects and challenges for diagnostics in microplasmas. In addition, previous special issues on the topic of microplasmas have already covered many aspects of source development, applications and modelling [28-31]. The reader who wishes to access additional background information on microplasmas is referred to the following review papers [32-35]. We would like to thank all the contributors and the editorial staff who were of tremendous support in the preparation of this special issue. It is our sincere hope that you enjoy reading this special issue and that it will be a reference and helpful guidance for young researchers embarking in the field of microplasmas. The continued effort to increase our understanding of plasmas by modelling and diagnostics is of key importance for plasma science and the development of novel technologies. References [1] Eden J G, Park S-J, Herring C M and Bulson J M 2011 J. Phys. D: Appl. Phys. 44 224011 [2] Lucas N, Ermel V, Kurrat M and Buttgenbach S 2008 J. Phys. D: Appl. Phys. 41 215202 [3] Karnassios V 2004 Spectrochim. Acta B 59 909-28 [4] Mariotti D and Sankaran RM 2010 J. Phys. D: Appl. Phys. 43 323001 [5] Sakai O and Tachibana K 2012 Plasma Sources Sci. Technol. 21 013001 [6] Starikovskaia S M 2006 Plasma assisted ignition and combustion J. Phys. D.: Appl. Phys. 39 R265-99 [7] Fridman G, Friedman G, Gutsol A, Shekhter A B, Vasilets V N and Fridman A 2008 Plasma Process. Polym. 5 503-33 [8] Eden G et al 2013 IEEE Trans. Plasma Sci. 41 661-75 [9] Siemens W 1857 Poggendorffs. Ann. Phys. Chem. 102 66-122 [10] Bruggeman P and Brandenburg R 2013 J. Phys. D: Appl. Phys. 46 464001 [11] Montello A et al 2013 J. Phys. D: Appl. Phys. 46 464002 [12] Schröder D et al 2013 J. Phys. D: Appl. Phys. 46 464003 [13] Verreycken T et al 2013 J. Phys. D: Appl. Phys. 46 464004 [14] Sousa J S and Puech V 2013 J. Phys. D: Appl. Phys. 46 464005 [15] Takeda K et al 2013 J. Phys. D: Appl. Phys. 46 464006 [16] Vallade J and Massines F 2013 J. Phys. D: Appl. Phys. 46 464007 [17] Wang C and Wu W 2013 J. Phys. D: Appl. Phys. 46 464008 [18] Schröter S et al 2013 J. Phys. D: Appl. Phys. 46 464009 [19] Rusterholtz D L et al 2013 J. Phys. D: Appl. Phys. 46 464010 [20] Huang B-D et al 2013 J. Phys. D: Appl. Phys. 46 464011 [21] Pothiraja R et al 2013 J. Phys. D: Appl. Phys. 46 464012 [22] Marinov I et al 2013 J. Phys. D: Appl. Phys. 46 464013 [23] Akishev Y et al 2013 J. Phys. D: Appl. Phys. 46 464014 [24] Brandenburg R et al 2013 J. Phys. D: Appl. Phys. 46 464015 [25] Houlahan T J Jret al 2013 J. Phys. D: Appl. Phys. 46 464016 [26] Benedikt J et al 2013 J. Phys. D: Appl. Phys. 46 464017 [27] McKay K et al 2013 J. Phys. D: Appl. Phys. 46 464018 [28] Selected papers from the 2nd International Workshop on Microplasmas 2005 J. Phys. D: Appl. Phys. 38 1633-759 [29] Special issue: 3rd International Workshop on Microplasmas 2007 Control. Plasma Phys. 47 3-128 [30] Cluster issue on Microplasmas: 4th International Workshop on Microplasmas 2008 J. Phys. D: Appl. Phys. 41 1904001 [31] Microplasmas: scientific challenges and technological opportunities 2010 Eur. Phys. J. D 60 437-608 [32] Becker K H, Schoenbach K H and Eden J G 2006 J. Phys. D: Appl. Phys. 39 R55 [33] Iza F, Kim G J, Lee S M, Lee J K, Walsh J L, Zhang Y T and Kong M G 2008 Plasma Process. Polym. 5 322-44 [34] Tachibana K 2006 Trans. Electr. Electron. Eng. 1 145-55 [35] Samukawa S et al 2012 J. Phys. D: Appl. Phys. 45 253001

Editorial

NASA Astrophysics Data System (ADS)

2003-06-01

In December 2002 we announced some changes to Journal of Physics B: Atomic, Molecular and Optical Physics: an extended scope to highlight the wide range of articles published in the journal and a new definition of Letters to the Editor. As always, comments and suggestions are welcome and should be sent to jphysb@iop.org. Extended scope of J. Phys. B J. Phys. B covers all aspects of atomic, molecular and optical physics. We publish articles on the study of atoms, ions, molecules, condensates or clusters, from their structure and interactions with particles, photons, fields and surfaces to all aspects of spectroscopy. Quantum optics, non-linear optics, laser physics, astrophysics, plasma physics, chemical physics, optical cooling and trapping and other investigations where the objects of study are the elementary atomic, ionic or molecular properties of processes are also included. With the introduction of the BEC Matters! portal and IOP Select, J. Phys. B, one of the major contributors, offers authors of articles in this research area wider visibility and more flexible publication with the opportunity to display multimedia attachments or web links to key groups and results. The recent papers listed below reflect the wide scope of J. Phys. B: Calculation of cross sections for very low-energy hydrogen-antihydrogen scattering using the Kohn variational method E A G Armour and C W Chamberlain J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 22 (28 November 2002) L489-L494 Imaging the electron transfer reaction of Ne2+ with Ar using position-sensitive coincidence spectroscopy Sarah M Harper, Wan-Ping Hu and Stephen D Price J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 21 (14 November 2002) 4409-4423 Ultraviolet-infrared wavelength scalings for strong field induced L-shell emissions from Kr and Xe clusters Alex B Borisov, Xiangyang Song, Fabrizio Frigeni, Yang Dai, Yevgeniya Koshman, W Andreas Schroeder, Jack Davis, Keith Boyer and Charles K Rhodes J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 21 (14 November 2002) L461-L467 A Bose-Einstein condensate in an optical lattice J Hecker Denschlag, J E Simsarian, H Häffner, C McKenzie, A Browaeys, D Cho, K Helmerson, S L Rolston and W D Phillips J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 14 (28 July 2002) 3095-3110 Locality of a class of entangled states I R Senitzky J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 14 (28 July 2002) 3029-3039 Solitons and vortices in ultracold fermionic gases Tomasz Karpiuk, Miroslaw Brewczyk and Kazimierz Rzazewski J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 14 (28 July 2002) L315-L321 Stable islands in chaotic atom-optics billiards, caused by curved trajectories M F Andersen, A Kaplan, N Friedman and N Davidson J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 9 (14 May 2002) 2183-2190 Emission probability and photon statistics of a coherently driven mazer Jin Xiong and Zhi-Ming Zhang J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 9 (14 May 2002) 2159-2172 The Li+-H2 system in a rigid-rotor approximation: potential energy surface and transport coefficients I Røeggen, H R Skullerud, T H Løvaas and D K Dysthe J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 7 (14 April 2002) 1707-1725 The stochastic Gross-Pitaevskii equation C W Gardiner, J R Anglin and T I A Fudge J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 6 (28 March 2002) 1555-1582 Oxygen ion impurity in the TEXTOR tokamak boundary plasma observed and analysed by Zeeman spectroscopy J D Hey, C C Chu, S Brezinsek, Ph Mertens and B Unterberg J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 6 (28 March 2002) 1525-1553 Electron-hexafluoropropene (C3F6) scattering at intermediate energies Czeslaw Szmytkowski, Pawel Mozejko and Stanislaw Kwitnewski J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 5 (14 March 2002) 1267-1274 High-resolution investigations of C2 and CN optical emissions in laser-induced plasmas during graphite ablation S Acquaviva and M L De Giorgi J. Phys. B: At. Mol. Opt. Phys. Vol 35, No 4 (28 February 2002) 795-806 New definition of a Letter to the Editor A Letter to the Editor should present new results, likely to stimulate further research and be of interest to the wider atomic, molecular and optical physics community. Above all the results should be sufficiently new and important to merit rapid publication as a Letter, which implies accelerated refereeing procedures. This should be made clear either in the body of the Letter, if appropriate, or with a supporting cover letter from the author on submission to the journal. Letters will have an upper limit of eight journal pages and, as an additional quality check, two referees instead of one will be used to review them. The Board will be asked to make a final publication decision in the event of two conflicting reports. With these measures in place it is hoped that the important new results will receive the exposure they deserve as a Letter. If you have any questions or comments on this or anything relating to J. Phys. B please contact Nicola Gulley, Publisher, J. Phys. B (E-mail: jphysb@iop.org).

Comment on “Theoretical analysis of high-field transport in graphene on a substrate” [J. Appl. Phys. 116, 034507 (2014)

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

Tan, Michael L. P.; Arora, Vijay K., E-mail: vijay.arora@wilkes.edu; Department of Electrical Engineering and Physics, Wilkes University, Wilkes-Barre, Pennsylvania 18766

2014-12-21

In a recent article, Serov et al. [J. Appl. Phys. 116, 034507 (2014)] claim: “This study represents the first time that the high-field behavior in graphene on a substrate was investigated taking into account intrinsic graphene properties,” ignoring the most recent anisotropic distribution function [V. K. Arora et al., J. Appl. Phys. 112, 114330 (2012)] also published in J. Appl. Phys., targeting the same experimental data [V. E. Dorgan et al., Appl. Phys. Lett. 97, 082112 (2010)]. The claim of Serov et al. of being first is refuted and many shortcomings of the hydrodynamic model for a highly quantum andmore » degenerate graphene nanolayer are pointed out.« less

Changes of the optical characteristics of radiochromic films in the transition from EBT3 to EBT-XD films.

PubMed

Schoenfeld, Andreas A; Wieker, Soeren; Harder, Dietrich; Poppe, Bjoern

2016-07-01

A new type of radiochromic film, the EBT-XD film, has been introduced with the aim to reduce the orientation effect and the lateral response artifact occurring in the use of radiochromic films together with flatbed scanners. The task of the present study is to quantify the changes of optical characteristics involved with the transition from the well-known EBT3 films to the new EBT-XD films, using the optical bench arrangement already applied by Schoenfeld et al (2014 Phys. Med. Biol. 59 3575-97). Largely reduced polarization effects and the almost complete loss of the anisotropy of the scattered light produced in a radiation-exposed film have been observed. The Rayleigh-Debye-Gans theory is used to understand these optical changes as arising from the reduced length-to-width ratio of the LiPCDA polymer crystals in the active layer of the EBT-XD film. The effect of these changes on the flatbed scanning artifacts will be shortly addressed, but treated in more detail in a further paper.

A model of mechanical interactions between heart and lungs.

PubMed

Fontecave Jallon, Julie; Abdulhay, Enas; Calabrese, Pascale; Baconnier, Pierre; Gumery, Pierre-Yves

2009-12-13

To study the mechanical interactions between heart, lungs and thorax, we propose a mathematical model combining a ventilatory neuromuscular model and a model of the cardiovascular system, as described by Smith et al. (Smith, Chase, Nokes, Shaw & Wake 2004 Med. Eng. Phys.26, 131-139. (doi:10.1016/j.medengphy.2003.10.001)). The respiratory model has been adapted from Thibault et al. (Thibault, Heyer, Benchetrit & Baconnier 2002 Acta Biotheor. 50, 269-279. (doi:10.1023/A:1022616701863)); using a Liénard oscillator, it allows the activity of the respiratory centres, the respiratory muscles and rib cage internal mechanics to be simulated. The minimal haemodynamic system model of Smith includes the heart, as well as the pulmonary and systemic circulation systems. These two modules interact mechanically by means of the pleural pressure, calculated in the mechanical respiratory system, and the intrathoracic blood volume, calculated in the cardiovascular model. The simulation by the proposed model provides results, first, close to experimental data, second, in agreement with the literature results and, finally, highlighting the presence of mechanical cardiorespiratory interactions.

Changes of the optical characteristics of radiochromic films in the transition from EBT3 to EBT-XD films

NASA Astrophysics Data System (ADS)

Schoenfeld, Andreas A.; Wieker, Soeren; Harder, Dietrich; Poppe, Bjoern

2016-07-01

A new type of radiochromic film, the EBT-XD film, has been introduced with the aim to reduce the orientation effect and the lateral response artifact occurring in the use of radiochromic films together with flatbed scanners. The task of the present study is to quantify the changes of optical characteristics involved with the transition from the well-known EBT3 films to the new EBT-XD films, using the optical bench arrangement already applied by Schoenfeld et al (2014 Phys. Med. Biol. 59 3575-97). Largely reduced polarization effects and the almost complete loss of the anisotropy of the scattered light produced in a radiation-exposed film have been observed. The Rayleigh-Debye-Gans theory is used to understand these optical changes as arising from the reduced length-to-width ratio of the LiPCDA polymer crystals in the active layer of the EBT-XD film. The effect of these changes on the flatbed scanning artifacts will be shortly addressed, but treated in more detail in a further paper.

Quantum Mechanical Studies of Molecular Hyperpolarizabilities.

DTIC Science & Technology

1980-04-30

exponent , reflects the screening of an electron in a given orbital by the interior electrons in the atom or molecule. In practice, when studying...Basis sets have evolved over the years in molecular quantum mechanics until sets of orbital exponents for the different atoms composing the molecule have...and R. P. Hurst , J. Chem. Phys. 46, 2356 (1967); S. P. LickmannI and J. W. Moskowitz, J. Chem. Phys. 54, 3622 7T971). 26. T. H. Dunning, J. Chem. Phys

Experimental determination of the lateral dose response functions of detectors to be applied in the measurement of narrow photon-beam dose profiles.

PubMed

Poppinga, D; Meyners, J; Delfs, B; Muru, A; Harder, D; Poppe, B; Looe, H K

2015-12-21

This study aims at the experimental determination of the detector-specific 1D lateral dose response function K(x) and of its associated rotational symmetric counterpart K(r) for a set of high-resolution detectors presently used in narrow-beam photon dosimetry. A combination of slit-beam, radiochromic film, and deconvolution techniques served to accomplish this task for four detectors with diameters of their sensitive volumes ranging from 1 to 2.2 mm. The particular aim of the experiment was to examine the existence of significant negative portions of some of these response functions predicted by a recent Monte-Carlo-simulation (Looe et al 2015 Phys. Med. Biol. 60 6585-607). In a 6 MV photon slit beam formed by the Siemens Artiste collimation system and a 0.5 mm wide slit between 10 cm thick lead blocks serving as the tertiary collimator, the true cross-beam dose profile D(x) at 3 cm depth in a large water phantom was measured with radiochromic film EBT3, and the detector-affected cross-beam signal profiles M(x) were recorded with a silicon diode, a synthetic diamond detector, a miniaturized scintillation detector, and a small ionization chamber. For each detector, the deconvolution of the convolution integral M(x)  =  K(x)  ∗  D(x) served to obtain its specific 1D lateral dose response function K(x), and K(r) was calculated from it. Fourier transformations and back transformations were performed using function approximations by weighted sums of Gaussian functions and their analytical transformation. The 1D lateral dose response functions K(x) of the four types of detectors and their associated rotational symmetric counterparts K(r) were obtained. Significant negative curve portions of K(x) and K(r) were observed in the case of the silicon diode and the diamond detector, confirming the Monte-Carlo-based prediction (Looe et al 2015 Phys. Med. Biol. 60 6585-607). They are typical for the perturbation of the secondary electron field by a detector with enhanced electron density compared with the surrounding water. In the cases of the scintillation detector and the small ionization chamber, the negative curve portions of K(x) practically vanish. It is planned to use the measured functions K(x) and K(r) to deconvolve clinical narrow-beam signal profiles and to correct the output factor values obtained with various high-resolution detectors.

Threshold Setting for Likelihood Function for Elasticity-Based Tissue Classification of Arterial Walls by Evaluating Variance in Measurement of Radial Strain

NASA Astrophysics Data System (ADS)

Tsuzuki, Kentaro; Hasegawa, Hideyuki; Kanai, Hiroshi; Ichiki, Masataka; Tezuka, Fumiaki

2008-05-01

Pathologic changes in arterial walls significantly influence their mechanical properties. We have developed a correlation-based method, the phased tracking method [H. Kanai et al.: IEEE Trans. Ultrason. Ferroelectr. Freq. Control 43 (1996) 791], for measurement of the regional elasticity of the arterial wall. Using this method, elasticity distributions of lipids, blood clots, fibrous tissue, and calcified tissue were measured in vitro by experiments on excised arteries (mean±SD: lipids 89±47 kPa, blood clots 131 ±56 kPa, fibrous tissue 1022±1040 kPa, calcified tissue 2267 ±1228 kPa) [H. Kanai et al.: Circulation 107 (2003) 3018; J. Inagaki et al.: Jpn. J. Appl. Phys. 44 (2005) 4593]. It was found that arterial tissues can be classified into soft tissues (lipids and blood clots) and hard tissues (fibrous tissue and calcified tissue) on the basis of their elasticity. However, there are large overlaps between elasticity distributions of lipids and blood clots and those of fibrous tissue and calcified tissue. Thus, it was difficult to differentiate lipids from blood clots and fibrous tissue from calcified tissue by simply thresholding elasticity value. Therefore, we previously proposed a method by classifying the elasticity distribution in each region of interest (ROI) (not a single pixel) in an elasticity image into lipids, blood clots, fibrous tissue, or calcified tissue based on a likelihood function for each tissue [J. Inagaki et al.: Jpn. J. Appl. Phys. 44 (2006) 4732]. In our previous study, the optimum size of an ROI was determined to be 1,500 µm in the arterial radial direction and 1,500 µm in the arterial longitudinal direction [K. Tsuzuki et al.: Ultrasound Med. Biol. 34 (2008) 573]. In this study, the threshold for the likelihood function used in the tissue classification was set by evaluating the variance in the ultrasonic measurement of radial strain. The recognition rate was improved from 50 to 54% by the proposed thresholding.

Complete set of essential parameters of an effective theory

NASA Astrophysics Data System (ADS)

Ioffe, M. V.; Vereshagin, V. V.

2018-04-01

The present paper continues the series [V. V. Vereshagin, True self-energy function and reducibility in effective scalar theories, Phys. Rev. D 89, 125022 (2014); , 10.1103/PhysRevD.89.125022A. Vereshagin and V. Vereshagin, Resultant parameters of effective theory, Phys. Rev. D 69, 025002 (2004); , 10.1103/PhysRevD.69.025002K. Semenov-Tian-Shansky, A. Vereshagin, and V. Vereshagin, S-matrix renormalization in effective theories, Phys. Rev. D 73, 025020 (2006), 10.1103/PhysRevD.73.025020] devoted to the systematic study of effective scattering theories. We consider matrix elements of the effective Lagrangian monomials (in the interaction picture) of arbitrary high dimension D and show that the full set of corresponding coupling constants contains parameters of both kinds: essential and redundant. Since it would be pointless to formulate renormalization prescriptions for redundant parameters, it is necessary to select the full set of the essential ones. This is done in the present paper for the case of the single scalar field.

Studies of giant magnetoresistance and interfacial structure in Cu/Co and Co/Re multilayers

NASA Astrophysics Data System (ADS)

Setty, Arun; Fernando, G.; Cooper, B. R.

2003-03-01

A study of giant magnetoresistance (GMR) in the Cu/Co [1]and Co/Re multilayer [2,3] systems is presented. The role of interface structure in such systems is significant, and is being investigated using an ab-initio based approach [4]. The role of intermixing [5], impurities and growth textures have been considered. Structural relaxation is taken into account using Hellman-Feynman and symmetry-based approaches. We find lattice spacings in agreement with experiment, energetically establish the favored growth textures and find results motivating the existence of the observed wavy interface in the Cu/Co system [6]. The transport properties of these multilayer systems will be studied using a theoretical model [7] incorporating material parameters obtained from the multiscale modeling approach we envisage. [1] S.S.P. Parkin, Z.G. Li, and D. J. Smith, Appl. Phys. Lett., 58, 2710-2712 (1991). [2] T. Charlton et al, Phys. Rev. B 63, 094404 (2001) [3] T. Charlton et al, Phys. Rev. B 59, 11897-11908 (1999) [4] C. Villagonzalo, A.K. Setty and B.R. Cooper, submitted to Phys. Rev. [5] J. Fassbender, R. Allenspach, and U. Durig. Surf. Sci., 383, L742-L748, (1997). [6] D.J. Larson et al, Appl. Phys. Lett., 73:1125-1127, (1998). [7] J. C. Slonczewski, Phys. Rev. B 39, 6995 (1989).

Magnetic and structural X-ray dichroïsms of metallic multilayers

NASA Astrophysics Data System (ADS)

Pizzini, Stefania; Fontaine, A.; Baudelet, F.; Minr, S.; Giorgetti, C.; Dartyge, E.; Bobo, J. F.; Piecuch, M.

1995-05-01

Fe/Cu and Co/Cu multilayers are intensively studied because of their exceptional magnetic properties, i.e., their giant magnetoresistance and the oscillations of the magnetic coupling between magnetic layers as a function of the thickness of the copper spacer [S.S. Parkin et al., Phys. Rev. Lett. 66 (1991) 2152; F. Petroff et al., Phys. Rev. B 44 (1991) 5355]. Spectroscopic approaches to the understanding of the coupling of ferromagnetic layers through a noble metal layer have been recently introduced, in particular spin-resolved photoemission [N.B. Brookes et al., Phys. Rev. Lett. 67 (1991) 354; C. Carbone et al., PRL 71 (1993) 2805] inverse photoemission [J.E. Ortega et al., Phys. Rev. Lett. 69 (1992) 844; Phys. Rev. B 47 (1993) 1540] and magnetic circular dichroism [S. Pizzini et al., MRS Symp. Proc., vol. 313 (1993); M.G. Samant et al. Phys. Rev. Lett. 72 (1994) 2152; S. Pizzini et al., Phys. Rev. Lett. 74 (1995) 1470]. X-ray absorption spectroscopy appears to be effective both for determination of the local structure, specific to the bidimensionality of the system but also for the electron symmetry-dependent evaluation of the spin polarisation of the noble metal as well as the magnetic element.

Dirac Magnons in Honeycomb Ferromagnets

NASA Astrophysics Data System (ADS)

Pershoguba, Sergey S.; Banerjee, Saikat; Lashley, J. C.; Park, Jihwey; Ågren, Hans; Aeppli, Gabriel; Balatsky, Alexander V.

2018-01-01

The discovery of the Dirac electron dispersion in graphene [A. H. Castro Neto, et al., The Electronic Properties of Graphene, Rev. Mod. Phys. 81, 109 (2009), 10.1103/RevModPhys.81.109] led to the question of the Dirac cone stability with respect to interactions. Coulomb interactions between electrons were shown to induce a logarithmic renormalization of the Dirac dispersion. With a rapid expansion of the list of compounds and quasiparticle bands with linear band touching [T. O. Wehling, et al., Dirac Materials, Adv. Phys. 63, 1 (2014), 10.1080/00018732.2014.927109], the concept of bosonic Dirac materials has emerged. We consider a specific case of ferromagnets consisting of van der Waals-bonded stacks of honeycomb layers, e.g., chromium trihalides CrX3 (X =F , Cl, Br and I), that display two spin wave modes with energy dispersion similar to that for the electrons in graphene. At the single-particle level, these materials resemble their fermionic counterparts. However, how different particle statistics and interactions affect the stability of Dirac cones has yet to be determined. To address the role of interacting Dirac magnons, we expand the theory of ferromagnets beyond the standard Dyson theory [F. J. Dyson, General Theory of Spin-Wave Interactions, Phys. Rev. 102, 1217 (1956), 10.1103/PhysRev.102.1217, F. J. Dyson, Thermodynamic Behavior of an Ideal Ferromagnet, Phys. Rev. 102, 1230 (1956), 10.1103/PhysRev.102.1230] to the case of non-Bravais honeycomb layers. We demonstrate that magnon-magnon interactions lead to a significant momentum-dependent renormalization of the bare band structure in addition to strongly momentum-dependent magnon lifetimes. We show that our theory qualitatively accounts for hitherto unexplained anomalies in nearly half-century-old magnetic neutron-scattering data for CrBr3 [W. B. Yelon and R. Silberglitt, Renormalization of Large-Wave-Vector Magnons in Ferromagnetic CrBr3 Studied by Inelastic Neutron Scattering: Spin-Wave Correlation Effects, Phys. Rev. B 4, 2280 (1971), 10.1103/PhysRevB.4.2280, E. J. Samuelsen, et al., Spin Waves in Ferromagnetic CrBr3 Studied by Inelastic Neutron Scattering, Phys. Rev. B 3, 157 (1971), 10.1103/PhysRevB.3.157]. We also show that honeycomb ferromagnets display dispersive surface and edge states, unlike their electronic analogs.

Interactions of Ultracold Impurity Particles with Bose-Einstein Condensates

DTIC Science & Technology

2015-06-23

Lukin et al ., Phys. Rev. Lett. 87, 037901 (2001). [2] D. Jaksch et al ., Phys. Rev. Lett. 85, 2208 (2000). [3] L. Isenhower et al ., Phys. Rev. Lett...104, 010503 (2010). [4] T. Wilk et al ., Phys. Rev. Lett. 104, 010502 (2010). [5] I. Mourachko et al ., Phys. Rev. Lett. 80, 253 (1998). [6] W. R...Phys. 12, 103044 (2010). [12] R. M. W. van Bijnen et al ., J. Phys. B 44, 184008 (2011). [13] I. Lesanovsky, Phys. Rev. Lett. 106, 025301 (2011). [14] E

Comparison of Exams for Active Learning Technologies vs. Traditional Lectures

NASA Astrophysics Data System (ADS)

Hornstra, Andrew; Djordjevic, Branislav; Dworzecka, Maria

2017-01-01

George Mason University has first semester (PHYS-160) and second semester (PHYS-260) physics course which consist of two sections. One is a traditional lecture style format (TRAD) and the other is a newer format which is a take on the ``flipped'' classroom. This newer style is referred to as Active Learning with Technologies (ALT). This course style has been in place for several years and has been studied before within George Mason University for final grade differences. These studies suggested that the ALT sections performed better, but grade weighting consistency, test time, and test content were not strictly controlled. The purpose of this study is to cross-examine the performance of students in these different class formats during Fall 2016 (PHYS-260) and Spring 2015 (PHYS-160) on very nearly identical exams over identical test times while controlling for almost every variable.

Computational Study of Chalcopyrite Semiconductors and Their Non-Linear Optical Properties

DTIC Science & Technology

2007-09-12

34 Xiaoshu Jiang, M. S. Miao , and Walter R. Lambrecht, Phys. Rev. B 71, 205212 (2005). 4. "Structure and phonons of ZnGeN 2 ," Walter R. Lambrecht, Erik All...dredge, and Kwiseon Kim Phys. Rev. B 72, 155202 (2005) 5. "Theoretical study of the phosphorus vacancy in ZnGeP 2 ," Xiaoshu Jiang, M. S. Miao , and...Rocksalt Phase Transitions," M. S. Miao and Walter R. Lambrecht, Phys. Rev. Lett. 94, 225501 (2005) 1 20070925383 b. Manuscripts submitted to peer

Multiple template-based fluoroscopic tracking of lung tumor mass without implanted fiducial markers

NASA Astrophysics Data System (ADS)

Cui, Ying; Dy, Jennifer G.; Sharp, Gregory C.; Alexander, Brian; Jiang, Steve B.

2007-10-01

Precise lung tumor localization in real time is particularly important for some motion management techniques, such as respiratory gating or beam tracking with a dynamic multi-leaf collimator, due to the reduced clinical tumor volume (CTV) to planning target volume (PTV) margin and/or the escalated dose. There might be large uncertainties in deriving tumor position from external respiratory surrogates. While tracking implanted fiducial markers has sufficient accuracy, this procedure may not be widely accepted due to the risk of pneumothorax. Previously, we have developed a technique to generate gating signals from fluoroscopic images without implanted fiducial markers using a template matching method (Berbeco et al 2005 Phys. Med. Biol. 50 4481-90, Cui et al 2007 Phys. Med. Biol. 52 741-55). In this paper, we present an extension of this method to multiple-template matching for directly tracking the lung tumor mass in fluoroscopy video. The basic idea is as follows: (i) during the patient setup session, a pair of orthogonal fluoroscopic image sequences are taken and processed off-line to generate a set of reference templates that correspond to different breathing phases and tumor positions; (ii) during treatment delivery, fluoroscopic images are continuously acquired and processed; (iii) the similarity between each reference template and the processed incoming image is calculated; (iv) the tumor position in the incoming image is then estimated by combining the tumor centroid coordinates in reference templates with proper weights based on the measured similarities. With different handling of image processing and similarity calculation, two such multiple-template tracking techniques have been developed: one based on motion-enhanced templates and Pearson's correlation score while the other based on eigen templates and mean-squared error. The developed techniques have been tested on six sequences of fluoroscopic images from six lung cancer patients against the reference tumor positions manually determined by a radiation oncologist. The tumor centroid coordinates automatically detected using both methods agree well with the manually marked reference locations. The eigenspace tracking method performs slightly better than the motion-enhanced method, with average localization errors less than 2 pixels (1 mm) and the error at a 95% confidence level of about 2-4 pixels (1-2 mm). This work demonstrates the feasibility of direct tracking of a lung tumor mass in fluoroscopic images without implanted fiducial markers using multiple reference templates.

Estimating radiofrequency power deposition in body NMR imaging.

PubMed

Bottomley, P A; Redington, R W; Edelstein, W A; Schenck, J F

1985-08-01

Simple theoretical estimates of the average, maximum, and spatial variation of the radiofrequency power deposition (specific absorption rate) during hydrogen nuclear magnetic resonance imaging are deduced for homogeneous spheres and for cylinders of biological tissue with a uniformly penetrating linear rf field directed axially and transverse to the cylindrical axis. These are all simple scalar multiples of the expression for the cylinder in an axial field published earlier (Med. Phys. 8, 510 (1981]. Exact solutions for the power deposition in the cylinder with axial (Phys. Med. Biol. 23, 630 (1978] and transversely directed rf field are also presented, and the spatial variation of power deposition in head and body models is examined. In the exact models, the specific absorption rates decrease rapidly and monotonically with decreasing radius despite local increases in rf field amplitude. Conversion factors are provided for calculating the power deposited by Gaussian and sinc-modulated rf pulses used for slice selection in NMR imaging, relative to rectangular profiled pulses. Theoretical estimates are compared with direct measurements of the total power deposited in the bodies of nine adult males by a 63-MHz body-imaging system with transversely directed field, taking account of cable and NMR coil losses. The results for the average power deposition agree within about 20% for the exact model of the cylinder with axial field, when applied to the exposed torso volume enclosed by the rf coil. The average values predicted by the simple spherical and cylindrical models with axial fields, the exact cylindrical model with transverse field, and the simple truncated cylinder model with transverse field were about two to three times that measured, while the simple model consisting of an infinitely long cylinder with transverse field gave results about six times that measured. The surface power deposition measured by observing the incremental power as a function of external torso radius was comparable to the average value. This is consistent with the presence of a variable thickness peripheral adipose layer which does not substantially increase surface power deposition with increasing torso radius. The absence of highly localized intensity artifacts in 63-MHz body images does not suggest anomalously intense power deposition at localized internal sites, although peak power is difficult to measure.

Three-Level Systems as Amplifiers and Attenuators: A Thermodynamic Analysis

NASA Astrophysics Data System (ADS)

Boukobza, E.; Tannor, D. J.

2007-06-01

Thermodynamics of a three-level maser was studied in the pioneering work of Scovil Schulz-DuBois [Phys. Rev. Lett. 2, 262 (1959)PRLTAO0031-900710.1103/PhysRevLett.2.262]. In this Letter we consider the same three-level model, but we give a full thermodynamic analysis based on Hamiltonian and dissipative Lindblad superoperators. The first law of thermodynamics is obtained using a recently developed alternative [Phys. Rev. A 74, 063823 (2006)PLRAAN1050-294710.1103/PhysRevA.74.063823] to Alicki’s definitions for heat flux and power [J. Phys. AJPHAC50305-4470 12, L103 (1979)10.1088/0305-4470/12/5/007]. Using a novel variation on Spohn’s entropy production function [J. Math. Phys. (N.Y.)JMAPAQ0022-2488 19, 1227 (1978)10.1063/1.523789], we obtain Carnot’s efficiency inequality and the Scovil Schulz-DuBois maser efficiency formula when the three-level system is operated as a heat engine (amplifier). Finally, we show that the three-level system has two other modes of operation—a refrigerator mode and a squanderer mode —both of which attenuate the electric field.

Variational Two-Particle Density Matrix Calculation for the Hubbard Model Below Half Filling Using Spin-Adapted Lifting Conditions

NASA Astrophysics Data System (ADS)

Verstichel, Brecht; van Aggelen, Helen; Poelmans, Ward; Van Neck, Dimitri

2012-05-01

The variational determination of the two-particle density matrix is an interesting, but not yet fully explored technique that allows us to obtain ground-state properties of a quantum many-body system without reference to an N-particle wave function. The one-dimensional fermionic Hubbard model has been studied before with this method, using standard two- and three-index conditions on the density matrix [J. R. Hammond , Phys. Rev. A 73, 062505 (2006)PLRAAN1050-294710.1103/PhysRevA.73.062505], while a more recent study explored so-called subsystem constraints [N. Shenvi , Phys. Rev. Lett. 105, 213003 (2010)PRLTAO0031-900710.1103/PhysRevLett.105.213003]. These studies reported good results even with only standard two-index conditions, but have always been limited to the half-filled lattice. In this Letter, we establish the fact that the two-index approach fails for other fillings. In this case, a subset of three-index conditions is absolutely needed to describe the correct physics in the strong-repulsion limit. We show that applying lifting conditions [J. R. Hammond , Phys. Rev. APLRAAN1050-2947 71, 062503 (2005)10.1103/PhysRevA.71.062503] is the most economical way to achieve this, while still avoiding the computationally much heavier three-index conditions. A further extension to spin-adapted lifting conditions leads to increased accuracy in the intermediate repulsion regime. At the same time, we establish the feasibility of such studies to the more complicated phase diagram in two-dimensional Hubbard models.

Fifty years of Jaynes-Cummings physics

NASA Astrophysics Data System (ADS)

Greentree, Andrew D.; Koch, Jens; Larson, Jonas

2013-11-01

This special issue commemorates the 50th anniversary of the seminal paper published by E T Jaynes and F W Cummings [1], the fundamental model which they introduced and now carries their names, and celebrates the remarkable host of exciting research on Jaynes-Cummings physics throughout the last five decades. The Jaynes-Cummings model has been taking the prominent stance as the 'hydrogen atom of quantum optics' [2]. Generally speaking, it provides a fundamental quantum description of the simplest form of coherent radiation-matter interaction. The Jaynes-Cummings model describes the interaction between a single electromagnetic mode confined to a cavity, and a two-level atom. Energy is exchanged between the field and the atom, which leads directly to coherent population oscillations (Rabi oscillations) and superposition states (dressed states). Being exactly solvable, the Jaynes-Cummings model serves as a most useful toy model, and as such it is a textbook example of the physicists' popular strategy of simplifying a complex problem to its most elementary constituents. Thanks to the simplicity of the Jaynes-Cummings model, this caricature of coherent light-matter interactions has never lost its appeal. The Jaynes-Cummings model is essential when discussing experiments in quantum electrodynamics (indeed the experimental motivation of the Jaynes-Cummings model was evident already in the original paper, dealing as it does with the development of the maser), and it has formed the starting point for much fruitful research ranging from ultra-cold atoms to cavity quantum electrodynamics. In fact, Jaynes-Cummings physics is at the very heart of the beautiful experiments by S Haroche and D Wineland, which recently earned them the 2012 Nobel Prize in physics. Indeed, as with most significant models in physics, the model is invoked in settings that go far beyond its initial framework. For example, recent investigations involving multi-level atoms, multiple atoms [3, 4], multiple electromagnetic modes, arrays of coupled cavities [5-7], and optomechanical systems [8] have further enriched the physics of the Jaynes-Cummings model. From the early interests in masers and the consistent quantum description of radiation and atom-photon interaction, the Jaynes-Cummings model has evolved into a cornerstone of quantum state engineering [9]. The authors of this editorial had not been born when Jaynes and Cummings wrote their remarkable paper. It is, therefore, a special honour for us to be able to draw the reader's attention to the accompanying reminiscence contributed by Frederick Cummings where he gives us a glimpse of the early history of the Jaynes-Cummings model from his perspective [11]. By now, the original 1963 paper by Jaynes and Cummings has gathered numerous citations and, at the time of writing, the number of articles involving Jaynes-Cummings physics is approaching 15 000.1 This special issue does not attempt to review this impressive wealth of research. The interested reader, however, is urged to consult the definitive article by Shore and Knight [10] for a comprehensive review of the first 30 years of Jaynes-Cummings physics. The collection of 26 papers presented in this issue, showcases a snapshot of some of the most recent and continuing research devoted to Jaynes-Cummings physics. We begin our special issue with Professor Cumming's recollections [11]. We then have six papers on quantum information aspects of the Jaynes-Cummings model [12-17]. The next topic includes seven papers on the Dicke and generalized Jaynes-Cummings models [18-24], followed by six papers on circuit QED, which is one of the most important experimental frameworks for Jaynes-Cummings systems [25-30]. Finally, we have six papers on the extension to many cavities, the Jaynes-Cummings-Hubbard model [31-36]. The snapshot of research captured in this special issue illustrates the unifying language provided by the Jaynes-Cummings model, tying together research in a number of subfields in physics. Jaynes-Cummings physics started with the diagonalization of a 2 × 2 matrix, as Frederick Cummings points out. There is no doubt that this elegance of simplicity will continue to guide exciting new research in the decades to come. References [1] Jaynes E T and Cummings F W 1963 Comparison of quantum and semiclassical radiation theories with application to the beam maser Proc. IEEE 51 89 [2] Shore B W and Knight P L 2004 Physics and Probability: Essays in Honor of Edwin T Jaynes (Cambridge: Cambridge University Press) [3] Tavis M and Cummings F W 1968 Exact solution for an N -molecule-radiation-field Hamiltonian Phys. Rev. 170 379-84 [4] Tavis M and Cummings F W 1969 Approximate solutions for an N -molecule-radiation-field Hamiltonian Phys. Rev. 188 692-5 [5] Hartmann M J, Brandão F G S L and Plenio M B 2006 Strongly interacting polaritons in coupled arrays of cavities Nature Phys. 2 849-55 [6] Greentree A D, Tahan C, Cole J H and Hollenberg L C L 2006 Quantum phase transitions of light Nature Phys. 2 856-61 [7] Angelakis D G, Santos M F and Bose S 2007 Photon-blockade-induced Mott transitions and XY spin models in coupled cavity arrays Phys. Rev. A 76 031805(R) [8] Schwab K C and Roukes M L 2005 Putting mechanics into quantum mechanics Phys. Today 58 36-42 [9] Blatt R, Milburn G J and Lvovksy A 2013 The 20th anniversary of quantum state engineering J. Phys. B: At. Mol. Opt. Phys. 46 100201 [10] Shore B and Knight P L 1993 The Jaynes-Cummings model J. Mod. Opt. 40 1195-238 [11] Cummings F W 2013 J. Phys. B: At. Mol. Opt. Phys. 46 220202 [12] Arenz C 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224001 [13] Quesada N 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224002 [14] Everitt M 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224003 [15] Kitajima S 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224004 [16] Groves E 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224005 [17] Bougouffa S 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224006 [18] Braak D 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224007 [19] Emary C 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224008 [20] Miroshnychenko Y 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224009 [21] Dombi A 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224010 [22] Tavis M 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224011 [23] Grimsmo A 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224012 [24] Stenholm S I 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224013 [25] Kockum A F 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224014 [26] Larson J 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224015 [27] Larson J 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224016 [28] Agarwal S 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224017 [29] Deng W-W 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224018 [30] Leppaekangas J 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224019 [31] Schmidt S 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224020 [32] Schiro M 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224021 [33] Susa C 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224022 [34] del Valle E 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224023 [35] Correa B V 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224024 [36] Schetakis N 2013 J. Phys. B: At. Mol. Opt. Phys. 46 224025 1Number estimate based on a Google Scholar search.

Binding energy of e^+Li using the Peach model potential.

NASA Astrophysics Data System (ADS)

Shertzer, Janine; Ward, Sandra

2006-05-01

The l-independent, parametric model potential developed by Peach^1 for describing the electron interaction with the alkali ion core yields energy levels that are in excellent agreement with experiment. Because of its relative simplicity, this model potential is an attractive choice for studying e^+- Li collisions;^2,3 the e^+-ion core interaction is obtained by changing the sign of the static term in the interaction. In order to test the usefulness of the potential for describing the physics of an effective three-body system, we calculated the binding energy of e^+Li. This is a stringent test, because the system is very weakly bound. Our results are in excellent agreement with previous calculations,^4 including those using the exact four-body Hamiltonian.^5 This work was funded by NSF under collaborative Grant PHYS-0440714 (JS) and PHYS-0440565 (SJW). ^1G. Peach, H.E. Saraph and M.J. Seaton, J. Phys. B 21, 3669 (1988). ^2M.S.T. Watts and J.W. Humberston, J. Phys. B 25, L491 (1992). ^3S. J. Ward and J. Shertzer, Phys. Rev. A 68, 032720 (2003). ^4J. Mitroy, M.W.J. Bromley, and G.G. Ryzhikh, J. Phys. B 35, R81 (2002). ^5Massimo Mella, Gabriele Morosi, and Dario Bressanini, J. Chem. Phys. 111, 108 (1999).

Study of Various Types of Resonances within the Phonon Damping Model

NASA Astrophysics Data System (ADS)

Dang, Nguyen Dinh

2001-10-01

The main successes of the Phonon Damping Model (PDM)(N. Dinh Dang and A. Arima, Phys. Rev. Lett. 80), 4145 (1998); Nucl. Phys. A 636, 427 (1998); N. Dinh Dang, K. Tanabe, and A. Arima, Phys. Rev. C 58, 3374 (1998). are presented in the description of: 1) the giant dipole resonance (GDR) in highly excited nuclei, 2) the double giant dipole resonance (DGDR) and multiple phonon resonances, 3) the Gamow-Teller resonance (GTR), and 4) the damping of pygmy dipole resonance (PDR) in neutron-rich nuclei. The analyses of results of numerical calculations are discussed in comparison with the experimental systematics on i) the width and the shape of the GDR at finite temperature ^1,(N. Dinh Dang et al., Phys. Rev. C 61), 027302 (2000). and angular momentum(N. Dinh Dang, Nucl. Phys. A 687), 261c (2001). for tin isotopes , ii) the electromagnetic cross sections of DGDR for ^136Xe and ^208Pb on a lead target at relativistic energies(N. Dinh Dang, V. Kim Au, and A. Arima, Phys. Rev. Lett. 85), 1827 (2000)., iii) the strength function of GTR(N. Dinh Dang, T. Suzuki, and A. Arima, Preprint RIKEN-AF-NF 377 (2000), submitted.), and iv) the PDR in oxygen and calcium isotopes(N. Dinh Dang et al., Phys. Rev. C 63), 044302 (2001)..

Research-based resources on PhysPort

NASA Astrophysics Data System (ADS)

Sayre, Eleanor

2017-01-01

PhysPort (http://physport.org) is a website that supports physics faculty in implementing research-based teaching practices in their classrooms. We provide expert recommendations and practical information about teaching methods and assessment. The PhysPort Data Explorer is an intuitive online tool for physics faculty to analyze their assessment data. Faculty upload their students' responses using our secure interface. The Data Explorer matches their pre/post data, scores it, compares it to national data, and graphs it in an interactive and intuitive manner. The Periscope collection on Physport brings together classroom video of students working groups with professional development materials for faculty, pre-service teachers, and learning assistants. To support PhysPort's development efforts, we conduct research on faculty needs around teaching and assessment, secondary analysis of published PER studies, and primary analysis of assessment data. In this talk, I'll introduce some of PhysPort's research-based resources and the research results which support them.

A Physics-Based Vibrotactile Feedback Library for Collision Events.

PubMed

Park, Gunhyuk; Choi, Seungmoon

2017-01-01

We present PhysVib: a software solution on the mobile platform extending an open-source physics engine in a multi-rate rendering architecture for automatic vibrotactile feedback upon collision events. PhysVib runs concurrently with a physics engine at a low update rate and generates vibrotactile feedback commands at a high update rate based on the simulation results of the physics engine using an exponentially-decaying sinusoidal model. We demonstrate through a user study that this vibration model is more appropriate to our purpose in terms of perceptual quality than more complex models based on sound synthesis. We also evaluated the perceptual performance of PhysVib by comparing eight vibrotactile rendering methods. Experimental results suggested that PhysVib enables more realistic vibrotactile feedback than the other methods as to perceived similarity to the visual events. PhysVib is an effective solution for providing physically plausible vibrotactile responses while reducing application development time to great extent.

Comment on "Many-body localization in Ising models with random long-range interactions"

NASA Astrophysics Data System (ADS)

Maksymov, Andrii O.; Rahman, Noah; Kapit, Eliot; Burin, Alexander L.

2017-11-01

This Comment is dedicated to the investigation of many-body localization in a quantum Ising model with long-range power-law interactions r-α, relevant for a variety of systems ranging from electrons in Anderson insulators to spin excitations in chains of cold atoms. It has earlier been argued [arXiv:cond-mat/0611387 (2005); Phys. Rev. B 91, 094202 (2015), 10.1103/PhysRevB.91.094202] that this model obeys the dimensional constraint suggesting the delocalization of all finite-temperature states in the thermodynamic limit for α ≤2 d in a d -dimensional system. This expectation conflicts with the recent numerical studies of the specific interacting spin model of Li et al. [Phys. Rev. A 94, 063625 (2016), 10.1103/PhysRevA.94.063625]. To resolve this controversy we reexamine the model of Li et al. [Phys. Rev. A 94, 063625 (2016), 10.1103/PhysRevA.94.063625] and demonstrate that the infinite-temperature states there obey the dimensional constraint. The earlier developed scaling theory for the critical system size required for delocalization is extended to small exponents 0 ≤α ≤d . The disagreements between the two works are explained by the nonstandard selection of investigated states in the ordered phase in the work of Li et al. [Phys. Rev. A 94, 063625 (2016)10.1103/PhysRevA.94.063625].

Three-dimensional Numerical Investigation of Electron Transport with Rotating Spoke in a Cylindrical Anode Layer Hall Plasma Accelerator

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

Ellison, C. Leland; Matyash, K.; Parker, J. B.

The oscillation behavior described in [Tang et. al, Phys. Plasmas 19, 073519 (2012)] di ers too greatly from previous experimental and numerical studies to claim observation of the same phenomenon. Most signi cantly, the rotation velocity in [Tang et. al, Phys. Plasmas 19, 073519 (2012)] is three orders of magnitude larger than that of typical \\rotating spoke" phenomena. Several physical and numerical considerations are presented to more accurately understand the numerical results of [Tang et. al, Phys. Plasmas 19, 073519 (2012)] in light of previous studies.

Joint Services Electronics Program.

DTIC Science & Technology

1985-03-30

Greenberg , Research Assistant LCE 17FI’w C OBJECTIVE: The general objective of this research unit is to study the interaction of excited molecules...helium - SiH mixtures. REFIRNCES: 1. V.M. Donnelly, D.C Flamn, WC. Dantremont-Smith, DJ. Werder, J. AppL Phys. 53,242 (1983. 2. KE. Greenberg , G.A...Hebner, and J.T. Verdeyen, Appl. Phys. Lett. 44, 299 (1984). 3. K.E. Greenberg , J.T. Verdeyen, J. Appl. Phys. 57, 1596 (1985). PUBLICATION& .0 Journal

Electronic Structure in Thin Film Organic Semiconductors

DTIC Science & Technology

2009-06-27

Peltekis, C. McGuinness, and A. Matsuura, J. Chem. Phys. 129, 224705, (2008) c) "The Local Electronic Structure of Tin Phthalocyanine studied by...interfaces in a Cu(100)-benzenethiolate- pentacene heterostructure", Phys. Rev. Lett. 100, 027601 (2008). 21. O.V. Molodtsova, M. Grobosch, M. Knupfer...1999). 37. N.J. Watkins, S. Zorba, and Y. Gao, "Interface formation of pentacene on Al2O3", J. Appl. Phys. 96, 425 (2004). 38. K.V. Chauhan, I

Automated Discovery of New Chemical Reactions and Accurate Calculation of Their Rates

DTIC Science & Technology

2015-06-02

formation of organic acids in reactions of the Criegee intermediate with aldehydes and ketones . Phys. Chem. Chem. Phys. 2013, 15, 16841-16852. [39...dioxolan-3-ol – our second case study - we confirmed that fragmentation of the cyclic peroxide leads to two possible pairs of acid and aldehyde products...Rate Prediction via Group Additivity, Part 2: H-Abstraction from Alkenes, Alkynes, Alcohols, Aldehydes , and Acids by H Atoms. J. Phys. Chem. A 2001, 105

Theoretical and numerical study of axisymmetric lattice Boltzmann models

NASA Astrophysics Data System (ADS)

Huang, Haibo; Lu, Xi-Yun

2009-07-01

The forcing term in the lattice Boltzmann equation (LBE) is usually used to mimic Navier-Stokes equations with a body force. To derive axisymmetric model, forcing terms are incorporated into the two-dimensional (2D) LBE to mimic the additional axisymmetric contributions in 2D Navier-Stokes equations in cylindrical coordinates. Many axisymmetric lattice Boltzmann D2Q9 models were obtained through the Chapman-Enskog expansion to recover the 2D Navier-Stokes equations in cylindrical coordinates [I. Halliday , Phys. Rev. E 64, 011208 (2001); K. N. Premnath and J. Abraham, Phys. Rev. E 71, 056706 (2005); T. S. Lee, H. Huang, and C. Shu, Int. J. Mod. Phys. C 17, 645 (2006); T. Reis and T. N. Phillips, Phys. Rev. E 75, 056703 (2007); J. G. Zhou, Phys. Rev. E 78, 036701 (2008)]. The theoretical differences between them are discussed in detail. Numerical studies were also carried out by simulating two different flows to make a comparison on these models’ accuracy and τ sensitivity. It is found all these models are able to obtain accurate results and have the second-order spatial accuracy. However, the model C [J. G. Zhou, Phys. Rev. E 78, 036701 (2008)] is the most stable one in terms of τ sensitivity. It is also found that if density of fluid is defined in its usual way and not directly relevant to source terms, the lattice Boltzmann model seems more stable.

Non-Abelian fermionization and fractional quantum Hall transitions

NASA Astrophysics Data System (ADS)

Hui, Aaron; Mulligan, Michael; Kim, Eun-Ah

2018-02-01

There has been a recent surge of interest in dualities relating theories of Chern-Simons gauge fields coupled to either bosons or fermions within the condensed matter community, particularly in the context of topological insulators and the half-filled Landau level. Here, we study the application of one such duality to the long-standing problem of quantum Hall interplateaux transitions. The key motivating experimental observations are the anomalously large value of the correlation length exponent ν ≈2.3 and that ν is observed to be superuniversal, i.e., the same in the vicinity of distinct critical points [Sondhi et al., Rev. Mod. Phys. 69, 315 (1997), 10.1103/RevModPhys.69.315]. Duality motivates effective descriptions for a fractional quantum Hall plateau transition involving a Chern-Simons field with U (Nc) gauge group coupled to Nf=1 fermion. We study one class of theories in a controlled limit where Nf≫Nc and calculate ν to leading nontrivial order in the absence of disorder. Although these theories do not yield an anomalously large exponent ν within the large Nf≫Nc expansion, they do offer a new parameter space of theories that is apparently different from prior works involving Abelian Chern-Simons gauge fields [Wen and Wu, Phys. Rev. Lett. 70, 1501 (1993), 10.1103/PhysRevLett.70.1501; Chen et al., Phys. Rev. B 48, 13749 (1993), 10.1103/PhysRevB.48.13749].

On the calculation of line strengths, oscillator strengths and lifetimes for very large principal quantum numbers in hydrogenic atoms and ions by the McLean-Watson formula

NASA Astrophysics Data System (ADS)

Hey, J. D.

2014-08-01

As a sequel to an earlier study (Hey 2009 J. Phys. B: At. Mol. Opt. Phys. 42 125701), we consider further the application of the line strength formula derived by Watson (2006 J. Phys. B: At. Mol. Opt. Phys. 39 L291) to transitions arising from states of very high principal quantum number in hydrogenic atoms and ions (Rydberg-Rydberg transitions, n > 1000). It is shown how apparent difficulties associated with the use of recurrence relations, derived (Hey 2006 J. Phys. B: At. Mol. Opt. Phys. 39 2641) by the ladder operator technique of Infeld and Hull (1951 Rev. Mod. Phys. 23 21), may be eliminated by a very simple numerical device, whereby this method may readily be applied up to n ≈ 10 000. Beyond this range, programming of the method may entail greater care and complexity. The use of the numerically efficient McLean-Watson formula for such cases is again illustrated by the determination of radiative lifetimes and comparison of present results with those from an asymptotic formula. The question of the influence on the results of the omission or inclusion of fine structure is considered by comparison with calculations based on the standard Condon-Shortley line strength formula. Interest in this work on the radial matrix elements for large n and n‧ is related to measurements of radio recombination lines from tenuous space plasmas, e.g. Stepkin et al (2007 Mon. Not. R. Astron. Soc. 374 852), Bell et al (2011 Astrophys. Space Sci. 333 377), to the calculation of electron impact broadening parameters for such spectra (Watson 2006 J. Phys. B: At. Mol. Opt. Phys. 39 1889) and comparison with other theoretical methods (Peach 2014 Adv. Space Res. in press), to the modelling of physical processes in H II regions (Roshi et al 2012 Astrophys. J. 749 49), and the evaluation bound-bound transitions from states of high n during primordial cosmological recombination (Grin and Hirata 2010 Phys. Rev. D 81 083005, Ali-Haïmoud and Hirata 2010 Phys. Rev. D 82 063521, Ali-Haïmoud 2013 Phys. Rev. D 87 023526).

Understanding quantum work in a quantum many-body system.

PubMed

Wang, Qian; Quan, H T

2017-03-01

Based on previous studies in a single-particle system in both the integrable [Jarzynski, Quan, and Rahav, Phys. Rev. X 5, 031038 (2015)2160-330810.1103/PhysRevX.5.031038] and the chaotic systems [Zhu, Gong, Wu, and Quan, Phys. Rev. E 93, 062108 (2016)1539-375510.1103/PhysRevE.93.062108], we study the the correspondence principle between quantum and classical work distributions in a quantum many-body system. Even though the interaction and the indistinguishability of identical particles increase the complexity of the system, we find that for a quantum many-body system the quantum work distribution still converges to its classical counterpart in the semiclassical limit. Our results imply that there exists a correspondence principle between quantum and classical work distributions in an interacting quantum many-body system, especially in the large particle number limit, and further justify the definition of quantum work via two-point energy measurements in quantum many-body systems.

Estimation of shear viscosity based on transverse momentum correlations

NASA Astrophysics Data System (ADS)

STAR Collaboration; Sharma, Monika; STAR Collaboration

2009-11-01

Event anisotropy measurements at RHIC suggest the strongly interacting matter created in heavy ion collisions flows with very little shear viscosity. Precise determination of “shear viscosity-to-entropy” ratio is currently a subject of extensive study [S. Gavin and M. Abdel-Aziz, Phys. Rev. Lett. 97 (2006) 162302]. We present preliminary results of measurements of the evolution of transverse momentum correlation function with collision centrality of Au+Au interactions at s=200 GeV. We compare two differential correlation functions, namely inclusive [J. Adams et al. (STAR Collaboration), Phys. Rev. C 72 (2005) 044902] and a differential version of the correlation measure C˜ introduced by Gavin et al. [S. Gavin and M. Abdel-Aziz, Phys. Rev. Lett. 97 (2006) 162302; M. Sharma and C. A. Pruneau, Phys. Rev. C 79 (2009) 024905.]. These observables can be used for the experimental study of the shear viscosity per unit entropy.

Theoretical description of the mixed-field orientation of asymmetric-top molecules: A time-dependent study

NASA Astrophysics Data System (ADS)

Omiste, Juan J.; González-Férez, Rosario

2016-12-01

We present a theoretical study of the mixed-field-orientation of asymmetric-top molecules in tilted static electric field and nonresonant linearly polarized laser pulse by solving the time-dependent Schrödinger equation. Within this framework, we compute the mixed-field orientation of a state-selected molecular beam of benzonitrile (C7H5N ) and compare with the experimental observations [J. L. Hansen et al., Phys. Rev. A 83, 023406 (2011), 10.1103/PhysRevA.83.023406] and with our previous time-independent descriptions [J. J. Omiste et al., Phys. Chem. Chem. Phys. 13, 18815 (2011), 10.1039/c1cp21195a]. For an excited rotational state, we investigate the field-dressed dynamics for several field configurations as those used in the mixed-field experiments. The nonadiabatic phenomena and their consequences on the rotational dynamics are analyzed in detail.

Beyond detection: biological physics informing progression and treatment of cancer Beyond detection: biological physics informing progression and treatment of cancer

NASA Astrophysics Data System (ADS)

Newman, T. J.; Thompson, A. M.

2012-12-01

The full text of the Preface is given in the PDF file. References [1] Kaur P et al 2012 Phys. Biol. 9 065001 [2] Lobikin M et al 2012 Phys. Biol. 9 065002 [3] Tanner K 2012 Phys. Biol. 9 065003 [4] Liu S V et al 2012 Phys. Biol. 9 065004 [5] Liao D et al 2012 Phys. Biol. 9 065005 [6] Liao D et al 2012 Phys. Biol. 9 065006 [7] Orlando P A et al 2012 Phys. Biol. 9 065007

Revisited comparison of thermal instability theory with MARFE density limit experiment in TEXTOR.

NASA Astrophysics Data System (ADS)

Kelly, Frederick

2006-03-01

Density limit shots in TEXTOR [Tokamak EXperiment for Technology Oriented Research] that ended in MARFE [Multifaceted Asymmetric Radiation From the Edge] are analyzed by several thermal instability theories^1-7 with convective effects included. ^1W. M. Stacey, Phys. Plasmas 3, 2673 (1996); Phys. Plasmas 3, 3032 (1996); Phys. Plasmas 4, 134 (1997); Phys. Plasmas 4, 242 (1997). ^2W. M. Stacey, Plasma Phys. Contr. Fusion 39, 1245 (1997). ^3W. M. Stacey, Fusion Technol. 36, 38 (1999).^ ^4W. M. Stacey, Phys. Plasmas 7, 3464 (2000). ^5F. A. Kelly, W. M. Stacey, J. Rapp and M. Brix, Phys. Plasmas 8, 3382 (2001). ^6M. Z. Tokar and F. A. Kelly, Phys. Plasmas 10, 4378 (2003). ^7M. Z. Tokar, F. A. Kelly and X. Loozen, Phys. Plasmas 12, 052510 (2005).

Theoretical prediction of probable isotopes of superheavy nuclei of Z = 122

NASA Astrophysics Data System (ADS)

Manjunatha, H. C.

2016-11-01

We have studied the α-decay half-life and spontaneous fission half-lives of isotopes of superheavy element Z = 122 in the range 275 ≤ A ≥ 326. A comparison of calculated alpha half-lives with the literature [D. N. Poenaru, R. A. Gherghescu and W. Greiner, Phys. Rev. C 83 (2011) 014601, D. N. Poenaru, R. A. Gherghescu and W. Greiner, Phys. Rev. C 85 (2012) 034615] and the analytical formulas of Royer [G. Royer, J. Phys. G; Nucl. Part. Phys. 26 (2000) 1149] shows good agreement with each other. To identify the mode of decay of these isotopes, the spontaneous-fission half-lives were also evaluated using the semiempirical relation given by [C. Xu, Z. Ren and Y. Guo, Phys. Rev. C 78 (2008) 044329]. A comparative study on the competition of alpha decay versus spontaneous fission of superheavy nuclei (SHN) reveals that around eight isotopes (307-314122) survive fission and have alpha decay channel as the prominent mode of decay and hold the possibility to be synthesized in the laboratory. The alpha decay half-lives and spontaneous fission half-lives of SHN with Z = 122, A = 299-306, with Z = 120, A = 294-300, and with Z = 119, A = 292-297 are also studied. The present study will be useful in the synthesis of superheavy elements Z > 118 by using the actinide based reactions with stable projectiles heavier than 48Ca.

Ionospheric Storm Effects at Subauroral Latitudes: A Case Study

DTIC Science & Technology

1991-02-01

Island: Z70 m/s) are consistent with corresponding model predictions [e.g., Testud et al., 1975: Richmond and Marsushitl, 1975]. Note that while...Atmos. Terr. Phys., 44. 161-171. 1982. in the morning sector. There it is marked by an anomalously Alcayde. D.. J. Testud . G. Vasseur. and P. Wadteufel...34-pile up" F-region trough. J. Atmos. Terr. Phys.. 33. 647-656. 1973. in the F-region. J. Atmos. Terr. Phys., 36, 70 -706. 1974. Testud . J.. P. Amayenc

Weak Hydrogen Bonds from Aliphatic and Fluorinated Alocohols to Molecular Nitrogen Detected by Supersonic Jet FTIR Spectroscopy

NASA Astrophysics Data System (ADS)

Oswald, Soenke; Suhm, Martin A.

2017-06-01

Complexes of organic molecules with the main component of earth's atmosphere are of interest, also for a stepwise understanding of the phenomenon of matrix isolation. Via its large quadrupole moment, nitrogen binds strongly to polarized OH groups in hydrogen-bonded dimers. Further complexation leads to a smooth spectral transition from free to embedded molecules which we probe in supersonic jets. Results for 1,1,1,3,3,3-hexafluoro-2-propanol, methanol, t-butyl alcohol, and the conformationally more complex ethanol are presented and assigned with the help of quantum chemical calculations. Kuma, S., Slipchenko, M. N., Kuyanov, K. E., Momose, T., Vilesov, A. F., Infrared Spectra and Intensities of the H_2O and N_2 Complexes in the Range of the ν_1- and ν_3-Bands of Water, J. Phys. Chem. A, 2006, 110, 10046-10052. Coussan, S., Bouteiller, Y., Perchard, J. P., Zheng, W. Q., Rotational Isomerism of Ethanol and Matrix Isolation Infrared Spectroscopy, J. Phys. Chem. A, 1998, 102, 5789-5793. Suhm, M. A., Kollipost, F., Femtisecond single-mole infrared spectroscopy of molecular clusters, Phys. Chem. Chem. Phys., 2013, 15, 10702-10721. Larsen, R. W., Zielke, P., Suhm, M. A., Hydrogen bonded OH stretching modes of methanol clusters: a combined IR and Raman isotopomer study, J. Chem. Phys., 2007, 126, 194307. Zimmermann, D., Häber, T., Schaal, H., Suhm, M. A., Hydrogen bonded rings, chains and lassos: The case of t-butyl alcohol clusters, Mol. Phys., 2001, 99, 413-425. Wassermann, T. N., Suhm, M. A., Ethanol Monomers and Dimers Revisited: A Raman Study of Conformational Preferences and Argon Nanocoating Effects, J. Phys. Chem. A, 2010, 114, 8223-8233.

Comment on "Comparative study of ab initio nonradiative recombination rate calculations under different formalisms"

NASA Astrophysics Data System (ADS)

Wickramaratne, Darshana; Shen, Jimmy-Xuan; Alkauskas, Audrius; Van de Walle, Chris G.

2018-02-01

In a recent article [Phys. Rev. B 91, 205315 (2015), 10.1103/PhysRevB.91.205315] Shi, Xu, and Wang presented a comparison of several formalisms to calculate nonradiative recombination rates and concluded the "one-dimensional (1D) quantum formula" that was used by Alkauskas et al. [Phys. Rev. B 90, 075202 (2014), 10.1103/PhysRevB.90.075202] is insufficient to accurately describe nonradiative capture rates. Our analysis of the results of Shi, Xu, and Wang indicates that their conclusions about the 1D quantum formula are unfounded and stem from an error in their calculations. Our own calculations demonstrate that the 1D quantum formula approach yields reliable and accurate results for nonradiative recombination rates.

High energy neutrinos from astrophysical accelerators of cosmic ray nuclei

NASA Astrophysics Data System (ADS)

Anchordoqui, Luis A.; Hooper, Dan; Sarkar, Subir; Taylor, Andrew M.

2008-02-01

Ongoing experimental efforts to detect cosmic sources of high energy neutrinos are guided by the expectation that astrophysical accelerators of cosmic ray protons would also generate neutrinos through interactions with ambient matter and/or photons. However, there will be a reduction in the predicted neutrino flux if cosmic ray sources accelerate not only protons but also significant numbers of heavier nuclei, as is indicated by recent air shower data. We consider plausible extragalactic sources such as active galactic nuclei, gamma ray bursts and starburst galaxies and demand consistency with the observed cosmic ray composition and energy spectrum at Earth after allowing for propagation through intergalactic radiation fields. This allows us to calculate the expected neutrino fluxes from the sources, normalized to the observed cosmic ray spectrum. We find that the likely signals are still within reach of next generation neutrino telescopes such as IceCube.PACS95.85.Ry98.70.Rz98.54.Cm98.54.EpReferencesFor a review, see:F.HalzenD.HooperRep. Prog. Phys.6520021025A.AchterbergIceCube CollaborationPhys. Rev. Lett.972006221101A.AchterbergIceCube CollaborationAstropart. Phys.262006282arXiv:astro-ph/0611063arXiv:astro-ph/0702265V.NiessANTARES CollaborationAIP Conf. Proc.8672006217I.KravchenkoPhys. Rev. D732006082002S.W.BarwickANITA CollaborationPhys. Rev. Lett.962006171101V.Van ElewyckPierre Auger CollaborationAIP Conf. Proc.8092006187For a survey of possible sources and event rates in km3 detectors see e.g.,W.BednarekG.F.BurgioT.MontaruliNew Astron. Rev.4920051M.D.KistlerJ.F.BeacomPhys. Rev. D742006063007A. Kappes, J. Hinton, C. Stegmann, F.A. Aharonian, arXiv:astro-ph/0607286.A.LevinsonE.WaxmanPhys. Rev. Lett.872001171101C.DistefanoD.GuettaE.WaxmanA.LevinsonAstrophys. J.5752002378F.A.AharonianL.A.AnchordoquiD.KhangulyanT.MontaruliJ. Phys. Conf. Ser.392006408J.Alvarez-MunizF.HalzenAstrophys. J.5762002L33F.VissaniAstropart. Phys.262006310F.W.SteckerC.DoneM.H.SalamonP.SommersPhys. Rev. Lett.6619912697(Erratum-ibid. 69 (1992) 2738)F.W.SteckerPhys. Rev. D722005107301A.AtoyanC.D.DermerPhys. Rev. Lett.872001221102L.A.AnchordoquiH.GoldbergF.HalzenT.J.WeilerPhys. Lett. B6002004202E.WaxmanJ.N.BahcallPhys. Rev. Lett.7819972292C.D.DermerA.AtoyanPhys. Rev. Lett.912003071102D.GuettaD.HooperJ.Alvarez-MunizF.HalzenE.ReuveniAstropart. Phys.202004429J.Alvarez-MunizF.HalzenD.W.HooperPhys. Rev. D622000093015A.LoebE.WaxmanJCAP06052006003S. Inoue, G. Sigl, F. Miniati, E. Armengaud, arXiv:astro-ph/0701167.E.WaxmanJ.N.BahcallPhys. Rev. D591999023002Phys. Rev. D642001023002K.MannheimR.J.ProtheroeJ.P.RachenPhys. Rev. D632001023003arXiv:astro-ph/9908031M.AhlersL.A.AnchordoquiH.GoldbergF.HalzenA.RingwaldT.J.WeilerPhys. Rev. D722005023001E.WaxmanAstrophys. J.4521995L1Note that the neutrino spectral shape can deviate from that for protons if the Feynman plateau is not flat in pseudo-rapidity space;L.AnchordoquiH.GoldbergC.NunezPhys. Rev. D712005065014This is in fact suggested by Tevatron data;F.AbeCDF CollaborationPhys. Rev. D4119902330J.G.LearnedS.PakvasaAstropart. Phys.31995267F.HalzenD.SaltzbergPhys. Rev. Lett.8119984305J.F.BeacomN.F.BellD.HooperS.PakvasaT.J.WeilerPhys. Rev. D682003093005(Erratum-ibid. D 72 (2005) 019901)L.A.AnchordoquiH.GoldbergF.HalzenT.J.WeilerPhys. Lett. B593200442L.A.AnchordoquiH.GoldbergF.HalzenT.J.WeilerPhys. Lett. B621200518A.M.HillasAnn. Rev. Astron. Astrophys.221984425For a general discussion on the acceleration time-scale in these sources see, e.g.,D.F.TorresL.A.AnchordoquiRep. Prog. Phys.6720041663M.C.BegelmanB.RudakM.SikoraAstrophys. J.362199038M.J.ChodorowskiA.A.ZdziarskiM.SikoraAstrophys. J.4001992181S.MichalowskiD.AndrewsJ.EickmeyerT.GentileN.MistryR.TalmanK.UenoPhys. Rev. Lett.391977737J.L.PugetF.W.SteckerJ.H.BredekampAstrophys. J.2051976638D.HooperS.SarkarA.M.TaylorAstropart. Phys.272007199The non-thermal energy release in GRBs is much smaller than that output by AGN.P.L.BiermannP.A.StrittmatterAstrophys. J.3221987643R.J.ProtheroeA.P.SzaboPhys. Rev. Lett.6919922885J.P.RachenP.L.BiermannAstron. Astrophys.2721993161J.P.RachenT.StanevP.L.BiermannAstron. Astrophys.2731993377R.C.HartmanEGRET CollaborationAstrophys. J. Suppl.123199979See e.g.,M.PunchNature3581992477D.PetryHEGRA CollaborationAstron. Astrophys.3111996L13P.M.ChadwickAstrophys. J.5131999161C.D.DermerR.SchlickeiserA.MastichiadisAstron. Astrophys.2561992L27S.D.BloomA.P.MarscherAstrophys. J.4611996657K.MannheimAstron. Astrophys.269199367K.MannheimScience2791998684A.DarA.LaorAstrophys. J.4781997L5F.A.AharonianNew Astron.52000377M.BoettcherAstrophys. J.5151999L21C.D.DermerR.SchlickeiserAstrophys. J.4161993458F.W.SteckerPhys. Rev. Lett.2119681016G.J.FishmanC.A.MeeganAnn. Rev. Astron. Astrophys.331995415For a list of papers related to SWIFT, see: http://swift.gsfc.nasa.gov/docs/swift/results/publist/.B.LinkR.I.EpsteinAstrophys. J.4661996764C.A.MeeganNature3551992143M.R.MetzgerNature3871997878See e.g.,T.PiranPhys. Rep.3141999575T.PiranPhys. Rep.3332000529For a recent review of GRB phenomenology, see:P.MeszarosRep. Prog. Phys.6920062259E.WaxmanLect. Notes Phys.5762001122M.MilgromV.UsovAstrophys. J.4491995L37E.WaxmanPhys. Rev. Lett.751995386M.VietriPhys. Rev. Lett.7819974328D.BandAstrophys. J.4131993281F. Halzen, in: K. Oliver (Ed.), Proceedings of the TASI’98, Boulder, 1998, p. 524.J.W.ElbertP.SommersAstrophys. J.4411995151L.A.AnchordoquiG.E.RomeroJ.A.CombiPhys. Rev. D601999103001L.A. Anchordoqui, J.F. Beacom, H. Goldberg, S. Palomares-Ruiz, T.J. Weiler, arXiv:astro-ph/0611580; arXiv:astro-ph/0611581.The factor 9/(4R) results from calculating ∫dr∫dr|r-r|(4πR/3), where r is the position of a star and r is the position of an observer (the position of the reaction), in a region of radius R uniformly filled with sources.D.A.ForbesM.J.WardV.RotaciucM.BlietzR.GenzelS.DrapatzP.P.van der WerfA.KrabbeAstrophys. J.4061993L11P. Chanial, H. Flores, B. Guiderdoni, D. Elbaz, F. Hammer, L. Vigroux, arXiv:astro-ph/0610900.P.O.LagageC.J.CesarskyAstron. Astrophys.1181983223S.P.LaiJ.M.GirartR.CrutcherAstrophys. J.5982003392W.BednarekMon. Not. R. Astron. Soc.3452003847W.BednarekR.J.ProtheroeAstropart. Phys.162002397P.BlasiA.V.OlintoPhys. Rev. D591999023001F.W.SteckerAstropart. Phys.262007398F.W. Stecker, arXiv:astro-ph/0610208.A γ-ray signal from the nearby starburst galaxy NGC253 was reported by the CANGAROO-II Collaboration but their subsequent re-analysis of the data is consistent with the expectation from backgrounds:C.ItohCANGAROO-II CollaborationAstron. Astrophys.3962002L1(Erratum-ibid. 462 (2007) 67)T.A. Thompson, E. Quataert, E. Waxman, A. Loeb, arXiv:astro-ph/0608699.D.J.BirdFly’s Eye CollaborationPhys. Rev. Lett.7119933401D.R.BergmanHiRes CollaborationNucl. Phys. Proc. Suppl.136200440T.Abu-ZayyadHiRes-MIA CollaborationAstrophys. J.5572001686M.NaganoJ. Phys. G181992423V.BerezinskyA.Z.GazizovS.I.GrigorievaPhys. Rev. D742006043005R.U.AbbasiHiRes CollaborationPhys. Rev. Lett.922004151101V.BerezinskyA.Z.GazizovS.I.GrigorievaPhys. Lett. B6122005147V.S.BerezinskyS.I.GrigorievaB.I.HnatykAstropart. Phys.212004617See Fig. 21 in:L.AnchordoquiM.T.DovaA.MariazziT.McCauleyT.PaulS.ReucroftJ.SwainAnn. Phys.3142004145D.AllardE.ParizotE.KhanS.GorielyA.V.OlintoAstron. Astrophys.4432005L29D.AllardE.ParizotA.V.OlintoAstropart. Phys.27200761T.Abu-ZayyadHigh Resolution Fly’s Eye CollaborationAstropart. Phys.232005157P. Sommers, et al., Pierre Auger Collaboration, arXiv:astro-ph/0507150.R.U.AbbasiHiRes CollaborationAstrophys. J.6222005910B.N. Afanasiev, et al., Yakutsk Collaboration, in: M. Nagano (Ed.), Proceedings of the Tokyo Workshop on Techniques for the Study of the Extremely High Energy Cosmic Rays, 1993.J. Knapp, private communication.J.RanftPhys. Rev. D51199564R.S.FletcherT.K.GaisserP.LipariT.StanevPhys. Rev. D5019945710J.EngelT.K.GaisserT.StanevP.LipariPhys. Rev. D4619925013N.N.KalmykovS.S.OstapchenkoA.I.PavlovNucl. Phys. Proc. Suppl.52B19977It is important to stress that the Auger data are still at a preliminary stage and the reconstruction procedures are still to be finalised. However, even allowing for the systematic uncertainties still present, it does appear that at the highest energies fewer events are seen than expected from the AGASA analysis.V.S.BerezinskyG.T.ZatsepinPhys. Lett. B281969423F.W.SteckerAstrophys. J.2281979919R.EngelD.SeckelT.StanevPhys. Rev. D642001093010Z.FodorS.D.KatzA.RingwaldH.TuJCAP03112003015D.De MarcoT.StanevF.W.SteckerPhys. Rev. D732006043003D.HooperA.TaylorS.SarkarAstropart. Phys.23200511M.AveN.BuscaA.V.OlintoA.A.WatsonT.YamamotoAstropart. Phys.23200519A point worth noting at this juncture: If iron nuclei are accelerated to very high energies (much higher than the energy spectrum has been measured), then disintegration can lead to large numbers of protons above the spectrum cutoff. In this case, the resulting cosmogenic neutrino flux is not dramatically suppressed. On the other hand, if iron nuclei are only largely accelerated to around 10eV or less, then the liberated protons will only rarely interact with the CMB to produce pions, hence the cosmogenic neutrino flux will be significantly reduced.

Citations Prize 2010 Citations Prize 2010

NASA Astrophysics Data System (ADS)

Webb, Steve; Harris, Simon

2010-12-01

Physics in Medicine & Biology (PMB) awards its 'Citations Prize' to the authors of the original research paper that has received the most citations in the preceding five years (according to the Institute for Scientific Information (ISI)). The lead author of the winning paper is presented with the Rotblat Medal (named in honour of Professor Sir Joseph Rotblat who was the second—and longest serving—Editor of PMB, from 1961-1972). The winning co-authors each receive a certificate. Photograph of the 2010 Citations Prize winners The winning authors Fernando Rannou (left), George Alexandrakis (holding the Rotblat Medal) and Arion Chatziioannou (right). The winner of the 2010 Citations Prize for the paper which has received the most citations in the previous 5 years (2005-2009) is Tomographic bioluminescence imaging by use of a combined optical-PET (OPET) system: a computer simulation feasibility study Authors: George Alexandrakis, Fernando R Rannou and Arion F Chatziioannou Reference: George Alexandrakis et al 2005 Phys. Med. Biol. 50 4225-41 Discussion of the significance of the winning paper can be found on medicalphysicsweb (medicalphysicsweb.org/cws/article/research/44334). Our congratulations go to the winning authors. Steve Webb Editor-in-Chief Simon Harris Publisher

Review of ultrasound image guidance in external beam radiotherapy: I. Treatment planning and inter-fraction motion management

NASA Astrophysics Data System (ADS)

Fontanarosa, Davide; van der Meer, Skadi; Bamber, Jeffrey; Harris, Emma; O'Shea, Tuathan; Verhaegen, Frank

2015-02-01

In modern radiotherapy, verification of the treatment to ensure the target receives the prescribed dose and normal tissues are optimally spared has become essential. Several forms of image guidance are available for this purpose. The most commonly used forms of image guidance are based on kilovolt or megavolt x-ray imaging. Image guidance can also be performed with non-harmful ultrasound (US) waves. This increasingly used technique has the potential to offer both anatomical and functional information. This review presents an overview of the historical and current use of two-dimensional and three-dimensional US imaging for treatment verification in radiotherapy. The US technology and the implementation in the radiotherapy workflow are described. The use of US guidance in the treatment planning process is discussed. The role of US technology in inter-fraction motion monitoring and management is explained, and clinical studies of applications in areas such as the pelvis, abdomen and breast are reviewed. A companion review paper (O’Shea et al 2015 Phys. Med. Biol. submitted) will extensively discuss the use of US imaging for intra-fraction motion quantification and novel applications of US technology to RT.

Review of ultrasound image guidance in external beam radiotherapy: I. Treatment planning and inter-fraction motion management.

PubMed

Fontanarosa, Davide; van der Meer, Skadi; Bamber, Jeffrey; Harris, Emma; O'Shea, Tuathan; Verhaegen, Frank

2015-02-07

In modern radiotherapy, verification of the treatment to ensure the target receives the prescribed dose and normal tissues are optimally spared has become essential. Several forms of image guidance are available for this purpose. The most commonly used forms of image guidance are based on kilovolt or megavolt x-ray imaging. Image guidance can also be performed with non-harmful ultrasound (US) waves. This increasingly used technique has the potential to offer both anatomical and functional information.This review presents an overview of the historical and current use of two-dimensional and three-dimensional US imaging for treatment verification in radiotherapy. The US technology and the implementation in the radiotherapy workflow are described. The use of US guidance in the treatment planning process is discussed. The role of US technology in inter-fraction motion monitoring and management is explained, and clinical studies of applications in areas such as the pelvis, abdomen and breast are reviewed. A companion review paper (O'Shea et al 2015 Phys. Med. Biol. submitted) will extensively discuss the use of US imaging for intra-fraction motion quantification and novel applications of US technology to RT.

Using data sources beyond PubMed has a modest impact on the results of systematic reviews of therapeutic interventions.

PubMed

Halladay, Christopher W; Trikalinos, Thomas A; Schmid, Ian T; Schmid, Christopher H; Dahabreh, Issa J

2015-09-01

Searching multiple sources when conducting systematic reviews is considered good practice. We aimed to investigate the impact of using sources beyond PubMed in systematic reviews of therapeutic interventions. We randomly selected 50 Cochrane reviews that searched the PubMed (or MEDLINE) and EMBASE databases and included a meta-analysis of ≥10 studies. We checked whether each eligible record in each review (n = 2,700) was retrievable in PubMed and EMBASE. For the first-listed meta-analysis of ≥10 studies in each review, we examined whether excluding studies not found in PubMed affected results. A median of one record per review was indexed in EMBASE but not in PubMed; a median of four records per review was not indexed in PubMed or EMBASE. Meta-analyses included a median of 13.5 studies; a median of zero studies per meta-analysis was indexed in EMBASE but not in PubMed; a median of one study per meta-analysis was not indexed in PubMed or EMBASE. Meta-analysis using only PubMed-indexed vs. all available studies led to a different conclusion in a single case (on the basis of conventional criteria for statistical significance). In meta-regression analyses, effects in PubMed- vs. non-PubMed-indexed studies were statistically significantly different in a single data set. For systematic reviews of the effects of therapeutic interventions, gains from searching sources beyond PubMed, and from searching EMBASE in particular are modest. Copyright © 2015 Elsevier Inc. All rights reserved.

Operation of SCINDA Receiver at the University of Calcutta and Space Weather Studies

DTIC Science & Technology

2015-02-18

Terr . Phys., 2014]. (ii) The pole ward gradient of the Equatorial Ionization Anomaly (EIA) introduces more intense propagation effects on...in the Indian longitude sector: Case studies, T. Das, K.S. Paul and A. Paul, J. Atmos. Sol. Terr . Phys., http://dx.doi.org/10.1016/j.jastp

Analogical Scaffolding and the Learning of Abstract Ideas in Physics: Empirical Studies

ERIC Educational Resources Information Center

Podolefsky, Noah S.; Finkelstein, Noah D.

2007-01-01

Previously, we proposed a model of student reasoning which combines the roles of representation, analogy, and layering of meaning--analogical scaffolding [Podolefsky and Finkelstein, Phys. Rev. ST Phys. Educ. Res. 3, 010109 (2007)]. The present empirical studies build on this model to examine its utility and demonstrate the vital intertwining of…

Multiple scattering of 13 and 20 MeV electrons by thin foils: a Monte Carlo study with GEANT, Geant4, and PENELOPE.

PubMed

Vilches, M; García-Pareja, S; Guerrero, R; Anguiano, M; Lallena, A M

2009-09-01

In this work, recent results from experiments and simulations (with EGSnrc) performed by Ross et al. [Med. Phys. 35, 4121-4131 (2008)] on electron scattering by foils of different materials and thicknesses are compared to those obtained using several Monte Carlo codes. Three codes have been used: GEANT (version 3.21), Geant4 (version 9.1, patch03), and PENELOPE (version 2006). In the case of PENELOPE, mixed and fully detailed simulations have been carried out. Transverse dose distributions in air have been obtained in order to compare with measurements. The detailed PENELOPE simulations show excellent agreement with experiment. The calculations performed with GEANT and PENELOPE (mixed) agree with experiment within 3% except for the Be foil. In the case of Geant4, the distributions are 5% narrower compared to the experimental ones, though the agreement is very good for the Be foil. Transverse dose distribution in water obtained with PENELOPE (mixed) is 4% wider than those calculated by Ross et al. using EGSnrc and is 1% narrower than the transverse dose distributions in air, as considered in the experiment. All the codes give a reasonable agreement (within 5%) with the experimental results for all the material and thicknesses studied.

Dose Volume Histogram (DVH) Analysis in Intensity Modulation Radiation Therapy (IMRT) Treatments for Prostate Cancers

NASA Astrophysics Data System (ADS)

Pyakuryal, Anil

2009-05-01

Studies have shown that as many as 8 out of 10 men had prostate cancer by age 80.Prostate cancer begins with small changes (prostatic intraepithelial neoplasia(PIN)) in size and shape of prostate gland cells,known as prostate adenocarcinoma.With advent in technology, prostate cancer has been the most widely used application of IMRT with the longest follow-up periods.Prostate cancer fits the ideal target criteria for IMRT of adjacent sensitive dose-limiting tissue (rectal, bladder).A retrospective study was performed on 10 prostate cancer patients treated with radiation to a limited pelvic field with a standard 4 field arrangements at dose 45 Gy, and an IMRT boost field to a total isocenter dose of 75 Gy.Plans were simulated for 4 field and the supplementary IMRT treatments with proposed dose delivery at 1.5 Gy/fraction in BID basis.An automated DVH analysis software, HART (S. Jang et al., 2008,Med Phys 35,p.2812)was used to perform DVH assessments in IMRT plans.A statistical analysis of dose coverage at targets in prostate gland and neighboring critical organs,and the plan indices(homogeneity, conformality etc) evaluations were also performed using HART extracted DVH statistics.Analyzed results showed a better correlation with the proposed outcomes (TCP, NTCP) of the treatments.

Response functions for computing absorbed dose to skeletal tissues from neutron irradiation

NASA Astrophysics Data System (ADS)

Bahadori, Amir A.; Johnson, Perry; Jokisch, Derek W.; Eckerman, Keith F.; Bolch, Wesley E.

2011-11-01

Spongiosa in the adult human skeleton consists of three tissues—active marrow (AM), inactive marrow (IM) and trabecularized mineral bone (TB). AM is considered to be the target tissue for assessment of both long-term leukemia risk and acute marrow toxicity following radiation exposure. The total shallow marrow (TM50), defined as all tissues lying within the first 50 µm of the bone surfaces, is considered to be the radiation target tissue of relevance for radiogenic bone cancer induction. For irradiation by sources external to the body, kerma to homogeneous spongiosa has been used as a surrogate for absorbed dose to both of these tissues, as direct dose calculations are not possible using computational phantoms with homogenized spongiosa. Recent micro-CT imaging of a 40 year old male cadaver has allowed for the accurate modeling of the fine microscopic structure of spongiosa in many regions of the adult skeleton (Hough et al 2011 Phys. Med. Biol. 56 2309-46). This microstructure, along with associated masses and tissue compositions, was used to compute specific absorbed fraction (SAF) values for protons originating in axial and appendicular bone sites (Jokisch et al 2011 Phys. Med. Biol. 56 6857-72). These proton SAFs, bone masses, tissue compositions and proton production cross sections, were subsequently used to construct neutron dose-response functions (DRFs) for both AM and TM50 targets in each bone of the reference adult male. Kerma conditions were assumed for other resultant charged particles. For comparison, AM, TM50 and spongiosa kerma coefficients were also calculated. At low incident neutron energies, AM kerma coefficients for neutrons correlate well with values of the AM DRF, while total marrow (TM) kerma coefficients correlate well with values of the TM50 DRF. At high incident neutron energies, all kerma coefficients and DRFs tend to converge as charged-particle equilibrium is established across the bone site. In the range of 10 eV to 100 MeV, substantial differences are observed among the kerma coefficients and DRF. As a result, it is recommended that the AM kerma coefficient be used to estimate the AM DRF, and that the TM kerma coefficient be used to estimate the TM50 DRF below 10 eV. Between 10 eV and 100 MeV, the appropriate DRF should be used as presented in this study. Above 100 MeV, spongiosa kerma coefficients apply well for estimating skeletal tissue doses. DRF values for each bone site as a function of energy are provided in an electronic annex to this article available at http://stacks.iop.org/0031-9155/56/6873/mmedia.

Response functions for computing absorbed dose to skeletal tissues from neutron irradiation.

PubMed

Bahadori, Amir A; Johnson, Perry; Jokisch, Derek W; Eckerman, Keith F; Bolch, Wesley E

2011-11-07

Spongiosa in the adult human skeleton consists of three tissues-active marrow (AM), inactive marrow (IM) and trabecularized mineral bone (TB). AM is considered to be the target tissue for assessment of both long-term leukemia risk and acute marrow toxicity following radiation exposure. The total shallow marrow (TM(50)), defined as all tissues lying within the first 50 µm of the bone surfaces, is considered to be the radiation target tissue of relevance for radiogenic bone cancer induction. For irradiation by sources external to the body, kerma to homogeneous spongiosa has been used as a surrogate for absorbed dose to both of these tissues, as direct dose calculations are not possible using computational phantoms with homogenized spongiosa. Recent micro-CT imaging of a 40 year old male cadaver has allowed for the accurate modeling of the fine microscopic structure of spongiosa in many regions of the adult skeleton (Hough et al 2011 Phys. Med. Biol. 56 2309-46). This microstructure, along with associated masses and tissue compositions, was used to compute specific absorbed fraction (SAF) values for protons originating in axial and appendicular bone sites (Jokisch et al 2011 Phys. Med. Biol. 56 6857-72). These proton SAFs, bone masses, tissue compositions and proton production cross sections, were subsequently used to construct neutron dose-response functions (DRFs) for both AM and TM(50) targets in each bone of the reference adult male. Kerma conditions were assumed for other resultant charged particles. For comparison, AM, TM(50) and spongiosa kerma coefficients were also calculated. At low incident neutron energies, AM kerma coefficients for neutrons correlate well with values of the AM DRF, while total marrow (TM) kerma coefficients correlate well with values of the TM(50) DRF. At high incident neutron energies, all kerma coefficients and DRFs tend to converge as charged-particle equilibrium is established across the bone site. In the range of 10 eV to 100 MeV, substantial differences are observed among the kerma coefficients and DRF. As a result, it is recommended that the AM kerma coefficient be used to estimate the AM DRF, and that the TM kerma coefficient be used to estimate the TM(50) DRF below 10 eV. Between 10 eV and 100 MeV, the appropriate DRF should be used as presented in this study. Above 100 MeV, spongiosa kerma coefficients apply well for estimating skeletal tissue doses. DRF values for each bone site as a function of energy are provided in an electronic annex to this article available at http://stacks.iop.org/0031-9155/56/6873/mmedia.

Rovibrational Quantum Dynamics of the Methane-Water Dimer

NASA Astrophysics Data System (ADS)

Sarka, János; Császár, Attila; Mátyus, Edit

2017-06-01

The challenging quantum dynamical description of the CH_4.H_2O complex has been solved variationally to provide theoretical explanation and assignment to the high-resolution spectroscopic measurements of the methane-water dimer carried out some twenty years ago. The computational results are in excellent agreement with the reported experimental transitions and the experimentally observed reversed rovibrational sequences, i.e., formally negative rotational excitation energies, are also obtained in the computations. In order to better understand the origin of these peculiar features in the energy-level spectrum, we studied all four possible combinations of the light and heavy isotopologues of methane and water and analyzed their rovibrational states using two limiting model systems: the rigidly rotating (RR) molecule and the coupled rotor (CR) system corresponding to the coupling of the two rotating monomers. All rovibrational quantum dynamical computations^{a,c} were carried out with rigid monomers and J = 0,1,2 total angular momentum quantum numbers using the fourth-age quantum chemical code GENIUSH and two different methane-water potential energy surfaces (PES). The numerical and formal analysis of the wave functions give insight into a fascinating complex world worth for further theoretical and experimental inquiries. J. Sarka, A. G. Császár, S. C. Althorpe, D. J. Wales and E. Mátyus, Phys. Chem. Chem. Phys. 18, 22816 (2016). L. Dore, R. C. Cohen, C. A. Schmuttenmaer, K. L. Busarow, M. J. Elrod, J. G. Loeser and R. J. Saykally, J. Chem. Phys. 100, 863 (1994). J. Sarka, A. G. Császár and E. Mátyus, Phys. Chem. Chem. Phys. accepted for publication (2017).} E. Mátyus, G. Czakó and A. G. Császár, J. Chem. Phys. 130, 134112 (2009). C. Fábri, E. Mátyus and A. G. Császár, J. Chem. Phys. 134, 074105 (2011). O. Akin-Ojo and K. Szalewicz, J. Chem. Phys. 123, 134311 (2005). C. Qu, R. Conte, P. L. Houston and J. M. Bowman, Phys. Chem. Chem. Phys. 17, 8172 (2015).

BrainPhys® increases neurofilament levels in CNS cultures, and facilitates investigation of axonal damage after a mechanical stretch-injury in vitro.

PubMed

Jackson, Travis C; Kotermanski, Shawn E; Jackson, Edwin K; Kochanek, Patrick M

2018-02-01

Neurobasal®/B27 is a gold standard culture media used to study primary neurons in vitro. An alternative media (BrainPhys®/SM1) was recently developed which robustly enhances neuronal activity vs. Neurobasal® or DMEM. To the best of our knowledge BrainPhys® has not been explored in the setting of neuronal injury. Here we characterized the utility of BrainPhys® in a model of in vitro mechanical-stretch injury. Primary rat cortical neurons were maintained in classic Neurobasal®, or sequentially maintained in Neurocult® followed by BrainPhys® (hereafter simply referred to as "BrainPhys® maintained neurons"). The levels of axonal markers and proteins involved in neurotransmission were compared on day in vitro 10 (DIV10). BrainPhys® maintained neurons had higher levels of GluN2B, GluR1, Neurofilament light/heavy chain (NF-L & NF-H), and protein phosphatase 2 A (PP2A) vs. neurons in Neurobasal®. Mechanical stretch-injury (50ms/54% biaxial stretch) to BrainPhys® maintained neurons modestly (albeit significantly) increased 24h lactate dehydrogenase (LDH) levels but markedly decreased axonal NF-L levels post-injury vs. uninjured controls or neurons given a milder 38% stretch-injury. Furthermore, two 54% stretch-injuries (in tandem) exacerbated 24h LDH release, increased α-spectrin breakdown products (SBDPs), and decreased Tau levels. Also, BrainPhys® maintained cultures had decreased markers of cell damage 24h after a single 54% stretch-injury vs. neurons in Neurobasal®. Finally, we tested the hypothesis that lentivirus mediated overexpression of the pro-death protein RBM5 exacerbates neuronal and/or axonal injury in primary CNS cultures. RBM5 overexpression vs. empty-vector controls increased 24h LDH release, and SBDP levels, after a single 54% stretch-injury but did not affect NF-L levels or Tau. BrainPhys® is a promising new reagent which facilities the investigation of molecular targets involved in axonal and/or neuronal injury in vitro. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Aging and Rejuvenation with Fractional Derivatives

DTIC Science & Technology

2004-09-10

Chechkin , J. Klafter, V . Yu . Gonchar , R. Metzler, and L. V . Tanatarov, Phys. Rev. E 67, 010102(R) (2003). [12] I. M. Sokolov and R. Metzler, Phys. Rev. E 67...051106 (2001). [7] A . V . Chechkin , R. Gorenflo, and I. M. Sokolov, Phys. Rev. E 66, 046129 (2002). [8] J. Bisquert, Phys. Rev. Lett. 91, 010602 (2003...9] R. Metzler and J. Klafter, J. Phys. Chem. B 104 3851 (2000). [10] E. Barkai and R. J. Silbey, J. Phys. Chem. B 104 3866 (2000).

A comparative study of the single-mode Richtmyer-Meshkov instability

NASA Astrophysics Data System (ADS)

Bai, X.; Deng, X.-L.; Jiang, L.

2018-07-01

In this work, the single-mode Richtmyer-Meshkov instability is studied numerically to find a reasonable nonlinear theoretical model which can be applied to predict the interface evolution from the linear stage to the early nonlinear stage. The cut-cell-based sharp-interface methods MuSiC+ (Chang et al. in J Comput Phys 242:946-990, 2013) and CCGF (Bai and Deng in Adv Appl Math Mech 9(5):1052-1075, 2017) are applied to generate numerical results for comparisons. Classical Air-SF6 and Air-Helium conditions are applied in this study, and initial amplitude and Atwood number are varied for comparison. Comparisons to the simulation results from the literature show the applicability of MuSiC+ and CCGF. Comparisons to the nonlinear theoretical models show that ZS (Zhang and Sohn in Phys Lett A 212:149-155, 1996; Phys Fluids 9:1106-1124, 1997), SEA (Sadot et al. in Phys Rev Lett 80:1654-1657, 1998), and DR (Dimonte and Ramaprabhu in Phys Fluids 22:014104, 2010) models are valid for both spike and bubble growth rates, and MIK (Mikaelian in Phys Rev E 67:026319, 2003) and ZG (Zhang and Guo in J Fluid Mech 786:47-61, 2016) models are valid for bubble growth rate, when the initial perturbation is small and the Atwood number is low, but only the DR model is applicable for both spike and bubble growth rates when the initial perturbation amplitude and the Atwood number are large. A new term of non-dimensional initial perturbation amplitude is presented and multiplied to the DR model to get a unified fitted DR model, which gives consistent results to the simulation ones for small and large initial amplitudes.

Direct evidence of three-body interactions in a cold Rb85 Rydberg gas

NASA Astrophysics Data System (ADS)

Han, Jianing

2010-11-01

Cold Rydberg atoms trapped in a magneto-optical trap (MOT) are not isolated and they interact through dipole-dipole and multipole-multipole interactions. First-order dipole-dipole interactions and van der Waals interactions between two atoms have been intensively studied. However, the facts that the first-order dipole-dipole interactions and van der Waals interactions show the same size of broadening [A. Reinhard, K. C. Younge, T. C. Liebisch, B. Knuffman, P. R. Berman, and G. Raithel, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.100.233201 100, 233201 (2008)] and there are transitions between two dimer states [S. M. Farooqi, D. Tong, S. Krishnan, J. Stanojevic, Y. P. Zhang, J. R. Ensher, A. S. Estrin, C. Boisseau, R. Cote, E. E. Eyler, and P. L. Gould, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.91.183002 91, 183002 (2003); K. R. Overstreet, Arne Schwettmann, Jonathan Tallant, and James P. Shaffer, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.76.011403 76, 011403(R) (2007)] cannot be explained by the two-atom picture. The purpose of this article is to show the few-body nature of a dense cold Rydberg gas by studying the molecular-state microwave spectra. Specifically, three-body energy levels have been calculated. Moreover, the transition from three-body energy levels to two-body coupled molecular energy levels and to isolated atomic energy levels as a function of the internuclear spacing is studied. Finally, single-body, two-body, and three-body interaction regions are estimated according to the experimental data. The results reported here provides useful information for plasma formation, further cooling, and superfluid formation.

A comparative study of the single-mode Richtmyer-Meshkov instability

NASA Astrophysics Data System (ADS)

Bai, X.; Deng, X.-L.; Jiang, L.

2017-11-01

In this work, the single-mode Richtmyer-Meshkov instability is studied numerically to find a reasonable nonlinear theoretical model which can be applied to predict the interface evolution from the linear stage to the early nonlinear stage. The cut-cell-based sharp-interface methods MuSiC+ (Chang et al. in J Comput Phys 242:946-990, 2013) and CCGF (Bai and Deng in Adv Appl Math Mech 9(5):1052-1075, 2017) are applied to generate numerical results for comparisons. Classical Air-SF6 and Air-Helium conditions are applied in this study, and initial amplitude and Atwood number are varied for comparison. Comparisons to the simulation results from the literature show the applicability of MuSiC+ and CCGF. Comparisons to the nonlinear theoretical models show that ZS (Zhang and Sohn in Phys Lett A 212:149-155, 1996; Phys Fluids 9:1106-1124, 1997), SEA (Sadot et al. in Phys Rev Lett 80:1654-1657, 1998), and DR (Dimonte and Ramaprabhu in Phys Fluids 22:014104, 2010) models are valid for both spike and bubble growth rates, and MIK (Mikaelian in Phys Rev E 67:026319, 2003) and ZG (Zhang and Guo in J Fluid Mech 786:47-61, 2016) models are valid for bubble growth rate, when the initial perturbation is small and the Atwood number is low, but only the DR model is applicable for both spike and bubble growth rates when the initial perturbation amplitude and the Atwood number are large. A new term of non-dimensional initial perturbation amplitude is presented and multiplied to the DR model to get a unified fitted DR model, which gives consistent results to the simulation ones for small and large initial amplitudes.

BiF/NF2 Kinetics Studies: Mechanism and Conversion Efficiency

DTIC Science & Technology

1990-08-31

68A, 61 (1964) 9. R. F Heidner III, H . Helvajian , J. S. Holloway, and J. B. Koffend, J. Chem. Phys. 84, 2137 (1986). 10. R. J. Malins and D. W Setser, J...Heidner III, H . Helvajian , J. S. Holloway, and J. B. Koffend, J. Chem. Phys. 93, 7818 (1989). 15. C. H . Corliss and W R. Bozman, Experimental Transition...MS Informal Report, UC-34a, UC-LASL (July 1980). 18. R. F Heidner III, H . Helvajian , J. S. Holloway, and J. B. Koffend, J. Chem. Phys. 93, 7813 (1989

Optimal Universal Uncertainty Relations

PubMed Central

Li, Tao; Xiao, Yunlong; Ma, Teng; Fei, Shao-Ming; Jing, Naihuan; Li-Jost, Xianqing; Wang, Zhi-Xi

2016-01-01

We study universal uncertainty relations and present a method called joint probability distribution diagram to improve the majorization bounds constructed independently in [Phys. Rev. Lett. 111, 230401 (2013)] and [J. Phys. A. 46, 272002 (2013)]. The results give rise to state independent uncertainty relations satisfied by any nonnegative Schur-concave functions. On the other hand, a remarkable recent result of entropic uncertainty relation is the direct-sum majorization relation. In this paper, we illustrate our bounds by showing how they provide a complement to that in [Phys. Rev. A. 89, 052115 (2014)]. PMID:27775010

Three-electron spin qubits

NASA Astrophysics Data System (ADS)

Russ, Maximilian; Burkard, Guido

2017-10-01

The goal of this article is to review the progress of three-electron spin qubits from their inception to the state of the art. We direct the main focus towards the exchange-only qubit (Bacon et al 2000 Phys. Rev. Lett. 85 1758-61, DiVincenzo et al 2000 Nature 408 339) and its derived versions, e.g. the resonant exchange (RX) qubit, but we also discuss other qubit implementations using three electron spins. For each three-spin qubit we describe the qubit model, the envisioned physical realization, the implementations of single-qubit operations, as well as the read-out and initialization schemes. Two-qubit gates and decoherence properties are discussed for the RX qubit and the exchange-only qubit, thereby completing the list of requirements for quantum computation for a viable candidate qubit implementation. We start by describing the full system of three electrons in a triple quantum dot, then discuss the charge-stability diagram, restricting ourselves to the relevant subsystem, introduce the qubit states, and discuss important transitions to other charge states (Russ et al 2016 Phys. Rev. B 94 165411). Introducing the various qubit implementations, we begin with the exchange-only qubit (DiVincenzo et al 2000 Nature 408 339, Laird et al 2010 Phys. Rev. B 82 075403), followed by the RX qubit (Medford et al 2013 Phys. Rev. Lett. 111 050501, Taylor et al 2013 Phys. Rev. Lett. 111 050502), the spin-charge qubit (Kyriakidis and Burkard 2007 Phys. Rev. B 75 115324), and the hybrid qubit (Shi et al 2012 Phys. Rev. Lett. 108 140503, Koh et al 2012 Phys. Rev. Lett. 109 250503, Cao et al 2016 Phys. Rev. Lett. 116 086801, Thorgrimsson et al 2016 arXiv:1611.04945). The main focus will be on the exchange-only qubit and its modification, the RX qubit, whose single-qubit operations are realized by driving the qubit at its resonant frequency in the microwave range similar to electron spin resonance. Two different types of two-qubit operations are presented for the exchange-only qubits which can be divided into short-ranged and long-ranged interactions. Both of these interaction types are expected to be necessary in a large-scale quantum computer. The short-ranged interactions use the exchange coupling by placing qubits next to each other and applying exchange-pulses (DiVincenzo et al 2000 Nature 408 339, Fong and Wandzura 2011 Quantum Inf. Comput. 11 1003, Setiawan et al 2014 Phys. Rev. B 89 085314, Zeuch et al 2014 Phys. Rev. B 90 045306, Doherty and Wardrop 2013 Phys. Rev. Lett. 111 050503, Shim and Tahan 2016 Phys. Rev. B 93 121410), while the long-ranged interactions use the photons of a superconducting microwave cavity as a mediator in order to couple two qubits over long distances (Russ and Burkard 2015 Phys. Rev. B 92 205412, Srinivasa et al 2016 Phys. Rev. B 94 205421). The nature of the three-electron qubit states each having the same total spin and total spin in z-direction (same Zeeman energy) provides a natural protection against several sources of noise (DiVincenzo et al 2000 Nature 408 339, Taylor et al 2013 Phys. Rev. Lett. 111 050502, Kempe et al 2001 Phys. Rev. A 63 042307, Russ and Burkard 2015 Phys. Rev. B 91 235411). The price to pay for this advantage is an increase in gate complexity. We also take into account the decoherence of the qubit through the influence of magnetic noise (Ladd 2012 Phys. Rev. B 86 125408, Mehl and DiVincenzo 2013 Phys. Rev. B 87 195309, Hung et al 2014 Phys. Rev. B 90 045308), in particular dephasing due to the presence of nuclear spins, as well as dephasing due to charge noise (Medford et al 2013 Phys. Rev. Lett. 111 050501, Taylor et al 2013 Phys. Rev. Lett. 111 050502, Shim and Tahan 2016 Phys. Rev. B 93 121410, Russ and Burkard 2015 Phys. Rev. B 91 235411, Fei et al 2015 Phys. Rev. B 91 205434), fluctuations of the energy levels on each dot due to noisy gate voltages or the environment. Several techniques are discussed which partly decouple the qubit from magnetic noise (Setiawan et al 2014 Phys. Rev. B 89 085314, West and Fong 2012 New J. Phys. 14 083002, Rohling and Burkard 2016 Phys. Rev. B 93 205434) while for charge noise it is shown that it is favorable to operate the qubit on the so-called ‘(double) sweet spots’ (Taylor et al 2013 Phys. Rev. Lett. 111 050502, Shim and Tahan 2016 Phys. Rev. B 93 121410, Russ and Burkard 2015 Phys. Rev. B 91 235411, Fei et al 2015 Phys. Rev. B 91 205434, Malinowski et al 2017 arXiv: 1704.01298), which are least susceptible to noise, thus providing a longer lifetime of the qubit.

Comment on ``Performance of different synchronization measures in real data: A case study on electroencephalographic signals''

NASA Astrophysics Data System (ADS)

Nicolaou, N.; Nasuto, S. J.

2005-12-01

We agree with Duckrow and Albano [Phys. Rev. E 67, 063901 (2003)] and Quian Quiroga [Phys. Rev. E 67, 063902 (2003)] that mutual information (MI) is a useful measure of dependence for electroencephalogram (EEG) data, but we show that the improvement seen in the performance of MI on extracting dependence trends from EEG is more dependent on the type of MI estimator rather than any embedding technique used. In an independent study we conducted in search for an optimal MI estimator, and in particular for EEG applications, we examined the performance of a number of MI estimators on the data set used by Quian Quiroga in their original study, where the performance of different dependence measures on real data was investigated [Phys. Rev. E 65, 041903 (2002)]. We show that for EEG applications the best performance among the investigated estimators is achieved by k -nearest neighbors, which supports the conjecture by Quian Quiroga in Phys. Rev. E 67, 063902 (2003) that the nearest neighbor estimator is the most precise method for estimating MI.

Quasi-additive estimates on the Hamiltonian for the one-dimensional long range Ising model

NASA Astrophysics Data System (ADS)

Littin, Jorge; Picco, Pierre

2017-07-01

In this work, we study the problem of getting quasi-additive bounds for the Hamiltonian of the long range Ising model, when the two-body interaction term decays proportionally to 1/d2 -α , α ∈(0,1 ) . We revisit the paper by Cassandro et al. [J. Math. Phys. 46, 053305 (2005)] where they extend to the case α ∈[0 ,ln3/ln2 -1 ) the result of the existence of a phase transition by using a Peierls argument given by Fröhlich and Spencer [Commun. Math. Phys. 84, 87-101 (1982)] for α =0 . The main arguments of Cassandro et al. [J. Math. Phys. 46, 053305 (2005)] are based in a quasi-additive decomposition of the Hamiltonian in terms of hierarchical structures called triangles and contours, which are related to the original definition of contours introduced by Fröhlich and Spencer [Commun. Math. Phys. 84, 87-101 (1982)]. In this work, we study the existence of a quasi-additive decomposition of the Hamiltonian in terms of the contours defined in the work of Cassandro et al. [J. Math. Phys. 46, 053305 (2005)]. The most relevant result obtained is Theorem 4.3 where we show that there is a quasi-additive decomposition for the Hamiltonian in terms of contours when α ∈[0,1 ) but not in terms of triangles. The fact that it cannot be a quasi-additive bound in terms of triangles lead to a very interesting maximization problem whose maximizer is related to a discrete Cantor set. As a consequence of the quasi-additive bounds, we prove that we can generalise the [Cassandro et al., J. Math. Phys. 46, 053305 (2005)] result, that is, a Peierls argument, to the whole interval α ∈[0,1 ) . We also state here the result of Cassandro et al. [Commun. Math. Phys. 327, 951-991 (2014)] about cluster expansions which implies that Theorem 2.4 that concerns interfaces and Theorem 2.5 that concerns n point truncated correlation functions in Cassandro et al. [Commun. Math. Phys. 327, 951-991 (2014)] are valid for all α ∈[0,1 ) instead of only α ∈[0 ,ln3/ln2 -1 ) .

Recommendations for physical therapists on the treatment of lumbopelvic pain during pregnancy: a systematic review.

PubMed

van Benten, Esther; Pool, Jan; Mens, Jan; Pool-Goudzwaard, Annelies

2014-07-01

Systematic review of the literature. To review and assess the peer-reviewed literature on the effectiveness of physical therapy interventions in treating lumbopelvic pain during pregnancy. Current guidelines on interventions for lumbopelvic pain during pregnancy differ in their recommendations for assessment and intervention. Recent publications may allow revising current recommendations for the treatment of this complex problem. An electronic search strategy was conducted in PubMed, PEDro, Scopus, and CINAHL of literature published from January 1992 to November 2013. Two authors independently assessed all abstracts for eligibility. Articles were independently rated for quality by 2 authors, using the Cochrane Back Review Group criteria for methodological quality. Where possible, effect sizes were calculated for the different interventions. A total of 22 articles (all randomized controlled trials) reporting on 22 independent studies were included. Overall, the methodological quality of the studies was moderate. Data for 4 types of interventions were considered: a combination of interventions (7 studies, n = 1202), exercise therapy (9 studies, n = 2149), manual therapy (5 studies, n = 360), and material support (1 study, n = 115). All included studies on exercise therapy, and most of the studies on interventions combined with patient education, reported a positive effect on pain, disability, and/or sick leave. Evidence-based recommendations can be made for the use of exercise therapy for the treatment of lumbopelvic pain during pregnancy. Therapy, level 1a-. J Orthop Sports Phys Ther 2014;44(7):464-473. Epub 10 May 2014. doi:10.2519/jospt.2014.5098.

Evaluation of the sensitivity and fading characteristics of an image plate system for x-ray diagnostics

NASA Astrophysics Data System (ADS)

Meadowcroft, A. L.; Bentley, C. D.; Stott, E. N.

2008-11-01

Image plates (IPs) are a reusable recording media capable of detecting ionizing radiation, used to diagnose x-ray emission from laser-plasma experiments. Due to their superior performance characteristics in x-ray applications [C. C. Bradford, W. W. Peppler, and J. T. Dobbins III, Med. Phys. 26, 27 (1999) and J. Digit. Imaging. 12, 54 (1999)], the Fuji Biological Analysis System (BAS) IPs are fielded on x-ray diagnostics for the HELEN laser by the Plasma Physics Department at AWE. The sensitivities of the Fuji BAS IPs have been absolutely calibrated for absolute measurements of x-ray intensity in the energy range of 0-100 keV. In addition, the Fuji BAS IP fading as a function of time was investigated. We report on the characterization of three Fuji BAS IP responses to x-rays using a radioactive source, and discrete x-ray line energies generated by the Excalibur soft x-ray facility and the Defense Radiological Standards Centre filter-fluorescer hard x-ray system at AWE.

Investigation of the High, Finite n Ballooning Mode Limit for Compact Quasi-Axially Symmetric Stellarators

NASA Astrophysics Data System (ADS)

Redi, Martha; Canik, John; Fredrickson, E.; Fu, G.; Nuehrenberg, C.; Boozer, A. H.

2000-10-01

The standard ballooning-mode beta limit comes from an infinite-n, radially local, ideal magnetohydrodynamic (MHD) calculation. Finite-n ballooning modes have been observed in tokamak plasmas [1]. Investigations of optimized quasiaxially symmetric stellarators with three dimensional, global, ideal MHD codes have recently shown good stability for the external kink, ``vertical" and infinite-n ballooning modes [2,3]. However, infinite-n ballooning stability may be too restrictive, due to its sensitivity to features in the local shear and curvature. The CAS3D [4] code is being used to compare the stability of the high-n ballooning modes to the infinite-n calculations from TERPSICHORE [5]. [1] E. Fredrickson, et al. Phys. Plas. 3 (1996) 2620. [2] G. Fu, Phys. Plas. 7 (2000)1079; Phys. Plas. 7 (2000) 1809. M. Redi, et al. Phys. Plas 7 (2000)1911. [3] A. Reiman, et al., Plas. Phys. Cont. Fus. 41 (1999) B273. [4] C. Nuehrenberg, Phys. Plas. 6 (1999) 275. C. Nuehrenberg, Phys. Plas. 3 (1996) 2401. C. Schwab, Phys. Fluids B5 (1993) 3195. [5] W. A. Cooper, Phys. Plas. 3 (1996) 275.

ep→epπ0 reaction studied in the Δ(1232) mass region using polarization asymmetries

NASA Astrophysics Data System (ADS)

Biselli, A.; Adams, G. S.; Amaryan, M. J.; Anciant, E.; Anghinolfi, M.; Asavapibhop, B.; Asryan, G.; Audit, G.; Auger, T.; Avakian, H.; Barrow, S.; Battaglieri, M.; Beard, K.; Bektasoglu, M.; Bertozzi, W.; Bianchi, N.; Boiarinov, S.; Bonner, B. E.; Bosted, P.; Bouchigny, S.; Bradford, R.; Branford, D.; Brooks, W. K.; Bueltmann, S.; Burkert, V. D.; Calarco, J. R.; Carman, D. S.; Carnahan, B.; Cetina, C.; Ciciani, L.; Cole, P. L.; Coleman, A.; Connelly, J.; Cords, D.; Corvisiero, P.; Crabb, D.; Crannell, H.; Cummings, J.; de Sanctis, E.; de Vita, R.; Degtyarenko, P. V.; Demirchyan, R. A.; Denizli, H.; Dennis, L. C.; Dharmawardane, K. V.; Dhuga, K. S.; Djalali, C.; Dodge, G. E.; Domingo, J.; Doughty, D.; Dragovitsch, P.; Dugger, M.; Dytman, S.; Eckhause, M.; Efremenko, Y. V.; Egiyan, H.; Egiyan, K. S.; Elouadrhiri, L.; Empl, A.; Eugenio, P.; Farhi, L.; Fatemi, R.; Feuerbach, R. J.; Ficenec, J.; Fissum, K.; Forest, T. A.; Freyberger, A.; Frolov, V.; Funsten, H.; Gaff, S. J.; Gai, M.; Gavalian, G.; Gavrilov, V. B.; Gilad, S.; Gilfoyle, G. P.; Giovanetti, K. L.; Girard, P.; Golovatch, E.; Griffioen, K. A.; Guidal, M.; Guillo, M.; Guo, L.; Gyurjyan, V.; Hanock, D.; Hardie, J.; Heddle, D.; Hersman, F. W.; Hicks, K.; Hicks, R. S.; Holtrop, M.; Hu, J.; Hyde-Wright, C. E.; Ito, M. M.; Jenkins, D.; Joo, K.; Kelley, J. H.; Khandaker, M.; Kim, K. Y.; Kim, K.; Kim, W.; Klein, A.; Klein, F. J.; Klimenko, A. V.; Klusman, M.; Kossov, M.; Kramer, L. H.; Kuang, Y.; Kuhn, J.; Kuhn, S. E.; Lachniet, J.; Laget, J. M.; Lawrence, D.; Leksin, G. A.; Longhi, A.; Loukachine, K.; Major, R. W.; Manak, J. J.; Marchand, C.; Matthews, S. K.; McAleer, S.; McNabb, J. W.; McCarthy, J.; Mecking, B. A.; Mestayer, M. D.; Meyer, C. A.; Minehart, R.; Mirazita, M.; Miskimen, R.; Mokeev, V.; Muccifora, V.; Mueller, J.; Murphy, L. Y.; Mutchler, G. S.; Napolitano, J.; Nelson, S. O.; Niculescu, G.; Niczyporuk, B.; Niyazov, R. A.; Nozar, M.; O'Brien, J. T.; O'Rielly, G. V.; Ohandjanyan, M. S.; Osipenko, M.; Park, K.; Patois, Y.; Peterson, G. A.; Philips, S.; Pivnyuk, N.; Pocanic, D.; Pogorelko, O.; Polli, E.; Preedom, B. M.; Price, J. W.; Qin, L. M.; Raue, B. A.; Riccardi, G.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Rock, S.; Ronchetti, F.; Rossi, P.; Rowntree, D.; Rubin, P. D.; Sabourov, K.; Salgado, C. W.; Sapunenko, V.; Sargsyan, M.; Schumacher, R. A.; Serov, V. S.; Sharabian, Y. G.; Shaw, J.; Shuvalov, S. M.; Simionatto, S.; Skabelin, A.; Smith, E. S.; Smith, L. C.; Smith, T.; Sober, D. I.; Sorrell, L.; Spraker, M.; Stepanyan, S.; Stoler, P.; Strakovsky, I. I.; Taiuti, M.; Taylor, S.; Tedeschi, D.; Thoma, U.; Thompson, R.; Todor, L.; Tung, T. Y.; Tur, C.; Ungaro, M.; Vineyard, M. F.; Vlassov, A.; Wang, K.; Weinstein, L. B.; Weller, H.; Welsh, R.; Weygand, D. P.; Whisnant, S.; Witkowski, M.; Wolin, E.; Yegneswaran, A.; Yun, J.; Zhang, B.; Zhao, J.; Zhou, Z.

2003-09-01

Measurements of the angular distributions of target and double-spin asymmetries for the Δ+(1232) in the exclusive channel p→(e→,e'p)π0 obtained at the Jefferson Lab in the Q2 range from 0.5 to 1.5 GeV2/c2 are presented. Results of the asymmetries are compared with the unitary isobar model [D. Drechsel et al., Nucl. Phys. A645, 145 (1999)], dynamical models [T. Sato and T. S. Lee, Phys. Rev. C 54, 2660 (1996); S. S. Kamalov et al., Phys. Lett. B 27, 522 (2001)], and the effective Lagrangian theory [R. M. Davidson et al., Phys. Rev. D 43, 71 (1991)]. Sensitivity to the different models was observed, particularly in relation to the description of background terms on which the target asymmetry depends significantly.

Thermal solitons as revealed by the static structure factor

NASA Astrophysics Data System (ADS)

Gawryluk, Krzysztof; Brewczyk, Mirosław; Rzążewski, Kazimierz

2017-04-01

We study, within a framework of the classical fields approximation, the static structure factor of a weakly interacting Bose gas at thermal equilibrium. As in a recent experiment [R. Schley et al., Phys. Rev. Lett. 111, 055301 (2013), 10.1103/PhysRevLett.111.055301], we find that the thermal distribution of phonons in a three-dimensional Bose gas follows the Planck distribution. On the other hand we find a disagreement between the Planck and phonon (calculated just as for the bulk gas) distributions in the case of elongated quasi-one-dimensional systems. We attribute this discrepancy to the existence of spontaneous dark solitons [i.e., thermal solitons as reported in T. Karpiuk et al., Phys. Rev. Lett. 109, 205302 (2012), 10.1103/PhysRevLett.109.205302] in an elongated Bose gas at thermal equilibrium.

Link-Prediction Enhanced Consensus Clustering for Complex Networks (Open Access)

DTIC Science & Technology

2016-05-20

92:022816. Available from: http://link.aps.org/doi/10.1103/PhysRevE.92.022816. doi: 10. 1103 /PhysRevE.92.022816 16. Aldecoa R, Marín I. Exploring the...from: http://link.aps.org/doi/10.1103/PhysRevE.80.056117. doi: 10. 1103 /PhysRevE.80.056117 18. Dahlin J, Svenson P. Ensemble approaches for improving...046110. Available from: http://link.aps.org/doi/10.1103/PhysRevE.81.046110. doi: 10. 1103 /PhysRevE.81.046110 28. Gfeller D, Chappelier JC, De Los Rios P

Theoretical Study of Hydrogen Adsorption on the GaN(0001) Surface

DTIC Science & Technology

2004-06-01

423 (1999) 70. [39] J.E. Northrup, J. Neugebauer, R.M. Feenstra, A.R. Smith, Phys. Rev. B 61 (2000) 9932. [40] K. Nakamura, T. Hayashi , A. Tachibana, K...Hasegawa, I.S.T. Tsong, T. Sakurai, T. Ohno , Phys. Rev. Lett. 82 (1999) 3074. [45] K. Raghavachari, Q. Fu, G. Chen, L. Li, C.H. Li, D.C. Law, R.F. Hicks, J...Xue, S. Kuwano, J.T. Sadowski, K.F. Kelly, T. Sakurai, T. Ohno , Phys. Rev. Lett. 84 (2000) 4015. [78] S. Vézian, F. Semond, J. Massies, D.W. Bullock, Z

Feasibility study for using an extended three-wave model to simulate plasma-based backward Raman amplification in one spatial dimension

NASA Astrophysics Data System (ADS)

Wang, T.-L.; Michta, D.; Lindberg, R. R.; Charman, A. E.; Martins, S. F.; Wurtele, J. S.

2009-12-01

Results are reported of a one-dimensional simulation study comparing the modeling capability of a recently formulated extended three-wave model [R. R. Lindberg, A. E. Charman, and J. S. Wurtele, Phys. Plasmas 14, 122103 (2007); Phys. Plasmas 15, 055911 (2008)] to that of a particle-in-cell (PIC) code, as well as to a more conventional three-wave model, in the context of the plasma-based backward Raman amplification (PBRA) [G. Shvets, N. J. Fisch, A. Pukhov et al., Phys. Rev. Lett. 81, 4879 (1998); V. M. Malkin, G. Shvets, and N. J. Fisch, Phys. Rev. Lett. 82, 4448 (1999); Phys. Rev. Lett. 84, 1208 (2000)]. The extended three-wave model performs essentially as well as or better than a conventional three-wave description in all temperature regimes tested, and significantly better at the higher temperatures studied, while the computational savings afforded by the extended three-wave model make it a potentially attractive tool that can be used prior to or in conjunction with PIC simulations to model the kinetic effects of PBRA for nonrelativistic laser pulses interacting with underdense thermal plasmas. Very fast but reasonably accurate at moderate plasma temperatures, this model may be used to perform wide-ranging parameter scans or other exploratory analyses quickly and efficiently, in order to guide subsequent simulation via more accurate if intensive PIC techniques or other algorithms approximating the full Vlasov-Maxwell equations.

Radiation dose calculations for CT scans with tube current modulation using the approach to equilibrium function

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

Li, Xinhua; Zhang, Da; Liu, Bob, E-mail: bliu7@mgh.harvard.edu

2014-11-01

Purpose: The approach to equilibrium function has been used previously to calculate the radiation dose to a shift-invariant medium undergoing CT scans with constant tube current [Li, Zhang, and Liu, Med. Phys. 39, 5347–5352 (2012)]. The authors have adapted this method to CT scans with tube current modulation (TCM). Methods: For a scan with variable tube current, the scan range was divided into multiple subscan ranges, each with a nearly constant tube current. Then the dose calculation algorithm presented previously was applied. For a clinical CT scan series that presented tube current per slice, the authors adopted an efficient approachmore » that computed the longitudinal dose distribution for one scan length equal to the slice thickness, which center was at z = 0. The cumulative dose at a specific point was a summation of the contributions from all slices and the overscan. Results: The dose calculations performed for a total of four constant and variable tube current distributions agreed with the published results of Dixon and Boone [Med. Phys. 40, 111920 (14pp.) (2013)]. For an abdomen/pelvis scan of an anthropomorphic phantom (model ATOM 701-B, CIRS, Inc., VA) on a GE Lightspeed Pro 16 scanner with 120 kV, N × T = 20 mm, pitch = 1.375, z axis current modulation (auto mA), and angular current modulation (smart mA), dose measurements were performed using two lines of optically stimulated luminescence dosimeters, one of which was placed near the phantom center and the other on the surface. Dose calculations were performed on the central and peripheral axes of a cylinder containing water, whose cross-sectional mass was about equal to that of the ATOM phantom in its abdominal region, and the results agreed with the measurements within 28.4%. Conclusions: The described method provides an effective approach that takes into account subject size, scan length, and constant or variable tube current to evaluate CT dose to a shift-invariant medium. For a clinical CT scan, dose calculations may be performed with a water-containing cylinder whose cross-sectional mass is equal to that of the subject. This method has the potential to substantially improve evaluations of patient dose from clinical CT scans, compared to CTDI{sub vol}, size-specific dose estimate (SSDE), or the dose evaluated for a TCM scan with a constant tube current equal to the average tube current of the TCM scan.« less

Accelerated prompt gamma estimation for clinical proton therapy simulations.

PubMed

Huisman, Brent F B; Létang, J M; Testa, É; Sarrut, D

2016-11-07

There is interest in the particle therapy community in using prompt gammas (PGs), a natural byproduct of particle treatment, for range verification and eventually dose control. However, PG production is a rare process and therefore estimation of PGs exiting a patient during a proton treatment plan executed by a Monte Carlo (MC) simulation converges slowly. Recently, different approaches to accelerating the estimation of PG yield have been presented. Sterpin et al (2015 Phys. Med. Biol. 60 4915-46) described a fast analytic method, which is still sensitive to heterogeneities. El Kanawati et al (2015 Phys. Med. Biol. 60 8067-86) described a variance reduction method (pgTLE) that accelerates the PG estimation by precomputing PG production probabilities as a function of energy and target materials, but has as a drawback that the proposed method is limited to analytical phantoms. We present a two-stage variance reduction method, named voxelized pgTLE (vpgTLE), that extends pgTLE to voxelized volumes. As a preliminary step, PG production probabilities are precomputed once and stored in a database. In stage 1, we simulate the interactions between the treatment plan and the patient CT with low statistic MC to obtain the spatial and spectral distribution of the PGs. As primary particles are propagated throughout the patient CT, the PG yields are computed in each voxel from the initial database, as a function of the current energy of the primary, the material in the voxel and the step length. The result is a voxelized image of PG yield, normalized to a single primary. The second stage uses this intermediate PG image as a source to generate and propagate the number of PGs throughout the rest of the scene geometry, e.g. into a detection device, corresponding to the number of primaries desired. We achieved a gain of around 10 3 for both a geometrical heterogeneous phantom and a complete patient CT treatment plan with respect to analog MC, at a convergence level of 2% relative uncertainty in the 90% yield region. The method agrees with reference analog MC simulations to within 10 -4 , with negligible bias. Gains per voxel range from 10 2 to 10 4 . The presented generic PG yield estimator is drop-in usable with any geometry and beam configuration. We showed a gain of three orders of magnitude compared to analog MC. With a large number of voxels and materials, memory consumption may be a concern and we discuss the consequences and possible tradeoffs. The method is available as part of Gate 7.2.

Accelerated prompt gamma estimation for clinical proton therapy simulations

NASA Astrophysics Data System (ADS)

Huisman, Brent F. B.; Létang, J. M.; Testa, É.; Sarrut, D.

2016-11-01

There is interest in the particle therapy community in using prompt gammas (PGs), a natural byproduct of particle treatment, for range verification and eventually dose control. However, PG production is a rare process and therefore estimation of PGs exiting a patient during a proton treatment plan executed by a Monte Carlo (MC) simulation converges slowly. Recently, different approaches to accelerating the estimation of PG yield have been presented. Sterpin et al (2015 Phys. Med. Biol. 60 4915-46) described a fast analytic method, which is still sensitive to heterogeneities. El Kanawati et al (2015 Phys. Med. Biol. 60 8067-86) described a variance reduction method (pgTLE) that accelerates the PG estimation by precomputing PG production probabilities as a function of energy and target materials, but has as a drawback that the proposed method is limited to analytical phantoms. We present a two-stage variance reduction method, named voxelized pgTLE (vpgTLE), that extends pgTLE to voxelized volumes. As a preliminary step, PG production probabilities are precomputed once and stored in a database. In stage 1, we simulate the interactions between the treatment plan and the patient CT with low statistic MC to obtain the spatial and spectral distribution of the PGs. As primary particles are propagated throughout the patient CT, the PG yields are computed in each voxel from the initial database, as a function of the current energy of the primary, the material in the voxel and the step length. The result is a voxelized image of PG yield, normalized to a single primary. The second stage uses this intermediate PG image as a source to generate and propagate the number of PGs throughout the rest of the scene geometry, e.g. into a detection device, corresponding to the number of primaries desired. We achieved a gain of around 103 for both a geometrical heterogeneous phantom and a complete patient CT treatment plan with respect to analog MC, at a convergence level of 2% relative uncertainty in the 90% yield region. The method agrees with reference analog MC simulations to within 10-4, with negligible bias. Gains per voxel range from 102 to 104. The presented generic PG yield estimator is drop-in usable with any geometry and beam configuration. We showed a gain of three orders of magnitude compared to analog MC. With a large number of voxels and materials, memory consumption may be a concern and we discuss the consequences and possible tradeoffs. The method is available as part of Gate 7.2.

Kinetic water-bag model of global collisional drift waves and ion temperature gradient instabilities in cylindrical geometry

NASA Astrophysics Data System (ADS)

Gravier, E.; Plaut, E.

2013-04-01

Collisional drift waves and ion temperature gradient (ITG) instabilities are studied using a linear water-bag kinetic model [P. Morel et al., Phys. Plasmas 14, 112109 (2007)]. An efficient spectral method, already validated in the case of drift waves instabilities [E. Gravier et al., Eur. Phys. J. D 67, 7 (2013)], allows a fast solving of the global linear problem in cylindrical geometry. The comparison between the linear ITG instability properties thus computed and the ones given by the COLUMBIA experiment [R. G. Greaves et al., Plasma Phys. Controlled Fusion 34, 1253 (1992)] shows a qualitative agreement. Moreover, the transition between collisional drift waves and ITG instabilities is studied theoretically as a function of the ion temperature profile.

Reply to "Comment on 'Origin of tilted-phase generation in systems of ellipsoidal molecules with dipolar interactions' "

NASA Astrophysics Data System (ADS)

Bose, Tushar Kanti; Saha, Jayashree

2014-04-01

In a recent article [T. K. Bose and J. Saha, Phys. Rev. E 86, 050701 (2012), 10.1103/PhysRevE.86.050701], we have presented the results of a Monte Carlo simulation study of the systems of dipolar Gay-Berne ellipsoids where two terminal antiparallel dipoles are placed symmetrically on the long axis of each ellipsoid, and the results revealed the combined contribution of dipolar separation and transverse orientations in controlling the tilt angle in the tilted hexatic smectic phase. The tilt angle changed from zero to a significant value, in the case of transverse dipoles, with a change in the dipolar separation. In the related comment, Madhusudana [preceding Comment, Phys. Rev. E 89, 046501 (2014), 10.1103/PhysRevE.89.046501] has claimed that the physical origin of the molecular tilt in the significantly tilted phases found in the simulations is similar to that proposed by McMillan [Phys. Rev. A 8, 1921 (1973), 10.1103/PhysRevA.8.1921]. Here, we explain that the claim is not correct and make it clear that the two compared pictures are quite different. In the preceding Comment, Madhusudana has also suggested an alternative explanation for tilt generation in the simulations by criticizing the original one proposed by us. We argue here in support of the original explanation and clarify that his explanation does not follow the simulation results.

Physics and chemistry-driven artificial neural network for predicting bioactivity of peptides and proteins and their design.

PubMed

Huang, Ri-Bo; Du, Qi-Shi; Wei, Yu-Tuo; Pang, Zong-Wen; Wei, Hang; Chou, Kuo-Chen

2009-02-07

Predicting the bioactivity of peptides and proteins is an important challenge in drug development and protein engineering. In this study we introduce a novel approach, the so-called "physics and chemistry-driven artificial neural network (Phys-Chem ANN)", to deal with such a problem. Unlike the existing ANN approaches, which were designed under the inspiration of biological neural system, the Phys-Chem ANN approach is based on the physical and chemical principles, as well as the structural features of proteins. In the Phys-Chem ANN model the "hidden layers" are no longer virtual "neurons", but real structural units of proteins and peptides. It is a hybridization approach, which combines the linear free energy concept of quantitative structure-activity relationship (QSAR) with the advanced mathematical technique of ANN. The Phys-Chem ANN approach has adopted an iterative and feedback procedure, incorporating both machine-learning and artificial intelligence capabilities. In addition to making more accurate predictions for the bioactivities of proteins and peptides than is possible with the traditional QSAR approach, the Phys-Chem ANN approach can also provide more insights about the relationship between bioactivities and the structures involved than the ANN approach does. As an example of the application of the Phys-Chem ANN approach, a predictive model for the conformational stability of human lysozyme is presented.

Thermodynamics of quantum spacetime histories

NASA Astrophysics Data System (ADS)

Smolin, Lee

2017-11-01

We show that the simplicity constraints, which define the dynamics of spin foam models, imply, and are implied by, the first law of thermodynamics, when the latter is applied to causal diamonds in the quantum spacetime. This result reveals an intimate connection between the holographic nature of gravity, as reflected by the Bekenstein entropy, and the fact that general relativity and other gravitational theories can be understood as constrained topological field theories. To state and derive this correspondence we describe causal diamonds in the causal structure of spin foam histories and generalize arguments given for the near horizon region of black holes by Frodden, Gosh and Perez [Phys. Rev. D 87, 121503 (2013); , 10.1103/PhysRevD.87.121503Phys. Rev. D 89, 084069 (2014); , 10.1103/PhysRevD.89.084069Phys. Rev. Lett. 107, 241301 (2011); , 10.1103/PhysRevLett.107.241301Phys. Rev. Lett.108, 169901(E) (2012)., 10.1103/PhysRevLett.108.169901] and Bianchi [arXiv:1204.5122.]. This allows us to apply a recent argument of Jacobson [Phys. Rev. Lett. 116, 201101 (2016).10.1103/PhysRevLett.116.201101] to show that if a spin foam history has a semiclassical limit described in terms of a smooth metric geometry, that geometry satisfies the Einstein equations. These results suggest also a proposal for a quantum equivalence principle.

Brownian motion and entropic torque driven motion of domain walls in antiferromagnets

NASA Astrophysics Data System (ADS)

Yan, Zhengren; Chen, Zhiyuan; Qin, Minghui; Lu, Xubing; Gao, Xingsen; Liu, Junming

2018-02-01

We study the spin dynamics in antiferromagnetic nanowire under an applied temperature gradient using micromagnetic simulations on a classical spin model with a uniaxial anisotropy. The entropic torque driven domain-wall motion and the Brownian motion are discussed in detail, and their competition determines the antiferromagnetic wall motion towards the hotter or colder region. Furthermore, the spin dynamics in an antiferromagnet can be well tuned by the anisotropy and the temperature gradient. Thus, this paper not only strengthens the main conclusions obtained in earlier works [Kim et al., Phys. Rev. B 92, 020402(R) (2015), 10.1103/PhysRevB.92.020402; Selzer et al., Phys. Rev. Lett. 117, 107201 (2016), 10.1103/PhysRevLett.117.107201], but more importantly gives the concrete conditions under which these conclusions apply, respectively. Our results may provide useful information on the antiferromagnetic spintronics for future experiments and storage device design.

Influence of the parallel nonlinearity on zonal flows and heat transport in global gyrokinetic particle-in-cell simulations

NASA Astrophysics Data System (ADS)

Jolliet, S.; McMillan, B. F.; Vernay, T.; Villard, L.; Hatzky, R.; Bottino, A.; Angelino, P.

2009-07-01

In this paper, the influence of the parallel nonlinearity on zonal flows and heat transport in global particle-in-cell ion-temperature-gradient simulations is studied. Although this term is in theory orders of magnitude smaller than the others, several authors [L. Villard, P. Angelino, A. Bottino et al., Plasma Phys. Contr. Fusion 46, B51 (2004); L. Villard, S. J. Allfrey, A. Bottino et al., Nucl. Fusion 44, 172 (2004); J. C. Kniep, J. N. G. Leboeuf, and V. C. Decyck, Comput. Phys. Commun. 164, 98 (2004); J. Candy, R. E. Waltz, S. E. Parker et al., Phys. Plasmas 13, 074501 (2006)] found different results on its role. The study is performed using the global gyrokinetic particle-in-cell codes TORB (theta-pinch) [R. Hatzky, T. M. Tran, A. Könies et al., Phys. Plasmas 9, 898 (2002)] and ORB5 (tokamak geometry) [S. Jolliet, A. Bottino, P. Angelino et al., Comput. Phys. Commun. 177, 409 (2007)]. In particular, it is demonstrated that the parallel nonlinearity, while important for energy conservation, affects the zonal electric field only if the simulation is noise dominated. When a proper convergence is reached, the influence of parallel nonlinearity on the zonal electric field, if any, is shown to be small for both the cases of decaying and driven turbulence.

Reversed Field Pinch helical self-organization studies with the volume preserving field line tracing code NEMATO

NASA Astrophysics Data System (ADS)

Bonfiglio, D.; Veranda, M.; Cappello, S.; Chacon, L.; Escande, D. F.; Piovesan, P.

2009-11-01

The existence of a Reversed Field Pinch (RFP) dynamo as a (laminar) helical self-organization was anticipated by MHD numerical studies [1]. High current operation in RFX-mod experiment shows such a helical self-organization: strong internal electron transport barriers (ITB) appear and magnetic chaos healing is diagnosed when Single Helical Axis (SHAx) regimes are achieved [2]. We present results of the field line tracing code NEMATO [3] applied to study the magnetic topology resulting from 3D MHD simulations, with the aim of clarifying the conditions for chaos healing in SHAx states. First tests confirm the basic picture: the magnetic chaos due to island overlap is significantly reduced after the expulsion of the dominant mode separatrix. The possible synergy with the presence of magnetic and/or flow shear at the SHAx ITB will also be discussed [4].[4pt] [1] S. Cappello, Plasma Phys. Control. Fusion (2004) & references therein [0pt] [2] R. Lorenzini et al., Nature Phys. (2009) [0pt] [3] J. M. Finn and L. Chacon, Phys. Plasmas (2005) [0pt] [4] M.E. Puiatti et al invited presentation EPS 2009 conference, submitted to Plasma Phys. Control. Fusion

iNuc-PhysChem: A Sequence-Based Predictor for Identifying Nucleosomes via Physicochemical Properties

PubMed Central

Feng, Peng-Mian; Ding, Chen; Zuo, Yong-Chun; Chou, Kuo-Chen

2012-01-01

Nucleosome positioning has important roles in key cellular processes. Although intensive efforts have been made in this area, the rules defining nucleosome positioning is still elusive and debated. In this study, we carried out a systematic comparison among the profiles of twelve DNA physicochemical features between the nucleosomal and linker sequences in the Saccharomyces cerevisiae genome. We found that nucleosomal sequences have some position-specific physicochemical features, which can be used for in-depth studying nucleosomes. Meanwhile, a new predictor, called iNuc-PhysChem, was developed for identification of nucleosomal sequences by incorporating these physicochemical properties into a 1788-D (dimensional) feature vector, which was further reduced to a 884-D vector via the IFS (incremental feature selection) procedure to optimize the feature set. It was observed by a cross-validation test on a benchmark dataset that the overall success rate achieved by iNuc-PhysChem was over 96% in identifying nucleosomal or linker sequences. As a web-server, iNuc-PhysChem is freely accessible to the public at http://lin.uestc.edu.cn/server/iNuc-PhysChem. For the convenience of the vast majority of experimental scientists, a step-by-step guide is provided on how to use the web-server to get the desired results without the need to follow the complicated mathematics that were presented just for the integrity in developing the predictor. Meanwhile, for those who prefer to run predictions in their own computers, the predictor's code can be easily downloaded from the web-server. It is anticipated that iNuc-PhysChem may become a useful high throughput tool for both basic research and drug design. PMID:23144709

In Situ Studies of the Decomposition of Simulated Chemical Warfare Agents on Nanoparticle Catalysts

DTIC Science & Technology

2009-10-04

University of South Carolina NUMBER Office of Sponsored Programs & Research James F. Byrnes International Center Columbia, SC 29208 - 9...P.; Barrat , J. L. Phys. Rev. B 1997, 56, 2248. (28) Ercolessi, F.; Andreoni, W.; Tosatti, E. Phys. Rev. Lett. 1991, 66, 911. (29) Marks, L. D

Theoretical Study of the Saturated Stage of a Relativistic Magnetron

DTIC Science & Technology

2008-11-30

mentioned that an earlier method to estimate the validity of a variational approximation had been given in Ref. [28], where Dexais, Anderson and Lasik ...Zemlyanaya. Phys. Rev. Lett. 80 (1998)5117. [28] M. Dexais. D. Anderson. M. Lasik . Phys. Rev. A 40 (1989) 2441. This research was supported in part by

SU-F-T-445: Effect of Triaxial Cables and Microdetectors in Small Field Dosimetry

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

Das, I; Andersen, A

2016-06-15

Purpose: Advances in radiation treatment especially with smaller fields used in SRS, Gamma knife, Tomotherapy, Cyberknife, and IMRT, require a high degree of precision especially with microdetectors for small field dosimetry (Das et al, Med Ph, 35, 206, 2008; Alfonso et al, Med Phys, 35, 5179, 2008). Due to small signal, the triaxial cable becomes critical in terms of signal to noise ratio (SNR) which is studied with microdetectors. Methods: Six high quality triaxial cables, 9.1 meters long from different manufacturers without any defects were acquired along with 5 most popular microdetectors (microdiamond, plastic scintillators, SRS-diode, edge-diode and pinpoint). Amore » dedicated electrometer was used for each combination except W1 which has its own supermax electrometer. A 6MV photon beam from Varian True beam with 100 MU at a 600 MU/min was used. Measurements were made at a depth of 5 cm in water phantom. Field sizes were varied from 0.5 cm to 10 cm square fields. Readings were taken with combination of cables and microdetectors. Results: Signal is dependent on the quality of the connectors, cables and types of microdetector. The readings varied from nC to pC depending on the type of microdetector. The net signal, S, (Sc-Sn), where Sc is signal with chamber and Sn is without chamber is a linear function of sensitive volume, v; (S = α+β•V), where α and β are constants. The standard deviation (SD) in 3 sets of reading with each combination of cable-detector was extremely low <0.02%. As expected the SD is higher in small fields (<3cm). Maximum estimated error was only ±0.2% in cables-detector combinations. Conclusion: The choice of cables has relatively small effect (±0.2%) with microdosimeter and should be accounted in overall error estimation in k value that is needed to convert ratio of reading to dose in small field dosimetry.« less

EDITORIAL: Special section on signal transduction Special section on signal transduction

NASA Astrophysics Data System (ADS)

Shvartsman, Stanislav

2012-08-01

This special section of Physical Biology focuses on multiple aspects of signal transduction, broadly defined as the study of the mechanisms by which cells communicate with their environment. Mechanisms of cell communication involve detection of incoming signals, which can be chemical, mechanical or electromagnetic, relaying these signals to intracellular processes, such as cytoskeletal networks or gene expression systems, and, ultimately, converting these signals to responses such as cell differentiation or death. Given the multiscale nature of signal transduction systems, they must be studied at multiple levels, from the identities and structures of molecules comprising signal detection and interpretation networks, to the systems-level properties of these networks. The 11 papers in this special section illustrate some of the most exciting aspects of signal transduction research. The first two papers, by Marie-Anne Félix [1] and by Efrat Oron and Natalia Ivanova [2], focus on cell-cell interactions in developing tissues, using vulval patterning in worm and cell fate specification in mammalian embryos as prime examples of emergent cell behaviors. Next come two papers from the groups of Julio Saez-Rodriguez [3] and Kevin Janes [4]. These papers discuss how the causal relationships between multiple components of signaling systems can be inferred using multivariable statistical analysis of empirical data. An authoritative review by Zarnitsyna and Zhu [5] presents a detailed discussion of the sequence of signaling events involved in T-cell triggering. Once the structure and components of the signaling systems are determined, they can be modeled using approaches that have been successful in other physical sciences. As two examples of such approaches, reviews by Rubinstein [6] and Kholodenko [7], present reaction-diffusion models of cell polarization and thermodynamics-based models of gene regulation. An important class of models takes the form of enzymatic networks, where a single molecule can participate in multiple types of interactions. Mathematical analysis of these models is discussed in the papers by Del Vecchio [8], Seaton and Krishnan [9], and Hatzimanikatis and colleagues [10]. Finally, all signaling systems are information processing devices. While this point is broadly accepted, there have been only a few attempts to apply information theory to experimental signaling systems. A review by Andre Levchenko and colleagues [11] provides a very clear introduction to information theory and its potential applications to signal transduction in cellular systems. References [1] Félix M-A 2012 Phys. Biol. 9 045001 [2] Oron E and Ivanova N 2012 Phys. Biol. 9 045002 [3] MacNamara A et al 2012 Phys. Biol. 9 045003 [4] Jensen K J and Janes K A 2012 Phys. Biol. 9 045004 [5] Zarnitsyna V and Zhu C 2012 Phys. Biol. 9 045005 [6] Rubinstein B et al 2012 Phys. Biol. 9 045006 [7] Frank T D et al 2012 Phys. Biol. 9 045007 [8] Del Vecchio D et al 2012 Phys. Biol. 9 045008 [9] Seaton D D and Krishnan J 2012 Phys. Biol. 9 045009 [10] Radivojevic A et al 2012 Phys. Biol. 9 045010 [11] Rhee A et al 2012 Phys. Biol. 9 045011

On the use temperature parameterized rate coefficients in the estimation of non-equilibrium reaction rates

NASA Astrophysics Data System (ADS)

Shizgal, Bernie D.; Chikhaoui, Aziz

2006-06-01

The present paper considers a detailed analysis of the nonequilibrium effects for a model reactive system with the Chapman-Eskog (CE) solution of the Boltzmann equation as well as an explicit time dependent solution. The elastic cross sections employed are a hard sphere cross section and the Maxwell molecule cross section. Reactive cross sections which model reactions with and without activation energy are used. A detailed comparison is carried out with these solutions of the Boltzmann equation and the approximation introduced by Cukrowski and coworkers [J. Chem. Phys. 97 (1992) 9086; Chem. Phys. 89 (1992) 159; Physica A 188 (1992) 344; Chem. Phys. Lett. A 297 (1998) 402; Physica A 275 (2000) 134; Chem. Phys. Lett. 341 (2001) 585; Acta Phys. Polonica B 334 (2003) 3607.] based on the temperature of the reactive particles. We show that the Cukrowski approximation has limited applicability for the large class of reactive systems studied in this paper. The explicit time dependent solutions of the Boltzmann equation demonstrate that the CE approach is valid only for very slow reactions for which the corrections to the equilibrium rate coefficient are very small.

Instabilities of coupled Cu2O5 ladders

NASA Astrophysics Data System (ADS)

Schuetz, Florian; Marston, Brad

2008-03-01

The spin-ladder compound Sr14-xCaxCu24O41 has a complex phase diagram including charge-density-wave order as well as unconventional superconductivity under high pressure. Due to its quasi-one-dimensional natureootnotetextS. Lee, J. B. Marston, J. O. Fjaerestad, Phys. Rev. B 72, 075126. fundamental questions about the high-Tc cuprates might be more easily addressed in this context. However, due to the spatial proximity of neighboring ladders inter-ladder Coulomb repulsion as well as hopping between ladders might still be important. Using the functional renormalization groupootnotetextM. Salmhofer and C. Honerkamp, Prog. Theor. Physics 105, 1 (2001). and an analysis of generalized susceptibilities ootnotetextD. Zanchi and H. J. Schulz, Phys. Rev. B 61, 13609 (2000); C. J. Halboth and W. Metzner, Phys. Rev. Lett. 85, 5162 (2000)., we study a model of coupled Cu2O5 ladders ootnotetextK. Wohlfeld, A. M. Oles, and G. A. Sawatzky, Phys. Rev. B 75, 180501(R) (2007).. We investigate instabilities towards charge, spin, and pairing order as a function of hole doping, inter-ladder hopping, and interaction strength starting from experimentally relevant hopping parametersootnotetextT. F. A. Müller, et al., Phys. Rev. B 57, R12655 (1998)..

Surface phonons in the topological insulators Bi2Se3 and Bi2Te3

NASA Astrophysics Data System (ADS)

Boulares, Ibrahim; Shi, Guangsha; Kioupakis, Emmanouil; Lošťák, Petr; Uher, Ctirad; Merlin, Roberto

2018-03-01

Raman scattering [K. M. F. Shahil et al., Appl. Phys. Lett. 96, 153103 (2010), V. Gnezdilov et al., Phys. Rev. B 84, 195118 (2011) and H. -H. Kung et al., Phys. Rev. B 95, 245406 (2017)], inelastic helium scattering [X. Zhu et al., Phys. Rev. Lett. 107, 186102 (2011)] and photoemission experiments [J. A. Sobota et al., Phys. Rev. Lett. 113, 157401 (2014)] on the topological insulators Bi2Se3 and Bi2Te3 show features in the range ∼ 50-160 cm-1, which have been assigned alternatively to Raman-forbidden, bulk infrared modes arising from symmetry breaking at the surface or to surface phonons, which couple to the topologically protected electronic states. Here, we present temperature- and wavelength- dependent Raman studies showing additional modes we ascribe to surface phonons in both Bi2Se3 and Bi2Te3. Our assignment is supported by density functional theory calculations revealing surface phonons at frequencies close to those of the extra peaks in the Raman data. The theoretical results also indicate that these modes are not a consequence of spin-orbit coupling and, thus, that their occurrence is unrelated to the topological properties of these materials.

Defects, Tunneling, and EPR Spectra of Single-Molecule Magnets

DTIC Science & Technology

2003-01-01

Caranin, Phys. Rev. Lett. 87, 187203 (2001); Phys. Rev. B 65, 094423 (2002). 19. A. Cornia, R. Sessoli, L. Sorace, D. Gatteschi , A. L. Barra, and C...Phys. Rev. B 64, 184426 (2001). 25. A. Mukhin, B. Gorshunov, M. Dressel, C. Sangregorio. and D. Gatteschi , Phys. Rev. B 63, 214411 (2001). 26. W

Non-Abelian gauge fields

NASA Astrophysics Data System (ADS)

Gerbier, Fabrice; Goldman, Nathan; Lewenstein, Maciej; Sengstock, Klaus

2013-07-01

Building a universal quantum computer is a central goal of emerging quantum technologies, which has the potential to revolutionize science and technology. Unfortunately, this future does not seem to be very close at hand. However, quantum computers built for a special purpose, i.e. quantum simulators , are currently developed in many leading laboratories. Many schemes for quantum simulation have been proposed and realized using, e.g., ultracold atoms in optical lattices, ultracold trapped ions, atoms in arrays of cavities, atoms/ions in arrays of traps, quantum dots, photonic networks, or superconducting circuits. The progress in experimental implementations is more than spectacular. Particularly interesting are those systems that simulate quantum matter evolving in the presence of gauge fields. In the quantum simulation framework, the generated (synthetic) gauge fields may be Abelian, in which case they are the direct analogues of the vector potentials commonly associated with magnetic fields. In condensed matter physics, strong magnetic fields lead to a plethora of fascinating phenomena, among which the most paradigmatic is perhaps the quantum Hall effect. The standard Hall effect consists in the appearance of a transverse current, when a longitudinal voltage difference is applied to a conducting sample. For quasi-two-dimensional semiconductors at low temperatures placed in very strong magnetic fields, the transverse conductivity, the ratio between the transverse current and the applied voltage, exhibits perfect and robust quantization, independent for instance of the material or of its geometry. Such an integer quantum Hall effect, is now understood as a deep consequence of underlying topological order. Although such a system is an insulator in the bulk, it supports topologically robust edge excitations which carry the Hall current. The robustness of these chiral excitations against backscattering explains the universality of the quantum Hall effect. Another interesting and related effect, which arises from the interplay between strong magnetic field and lattice potentials, is the famous Hofstadter butterfly: the energy spectrum of a single particle moving on a lattice and subjected to a strong magnetic field displays a beautiful fractal structure as a function of the magnetic flux penetrating each elementary plaquette of the lattice. When the effects of interparticle interactions become dominant, two-dimensional gases of electrons exhibit even more exotic behaviour leading to the fractional quantum Hall effect. In certain conditions such a strongly interacting electron gas may form a highly correlated state of matter, the prototypical example being the celebrated Laughlin quantum liquid. Even more fascinating is the behaviour of bulk excitations (quasi-hole and quasi-particles): they are neither fermionic nor bosonic, but rather behave as anyons with fractional statistics intermediate between the two. Moreover, for some specific filling factors (ratio between the electronic density and the flux density), these anyons are proven to have an internal structure (several components) and non-Abelian braiding properties. Many of the above statements concern theoretical predictions—they have never been observed in condensed matter systems. For instance, the fractional values of the Hall conductance is seen as a direct consequence of the fractional statistics, but to date direct observation of anyons has not been possible in two-dimensional semiconductors. Realizing these predictions in experiments with atoms, ions, photons etc, which potentially allow the experimentalist to perform measurements complementary to those made in condensed matter systems, is thus highly desirable! Non-Abelian gauge fields couple the motional states of the particles to their internal degrees of freedom (such as hyperfine states for atoms or ions, electronic spins for electrons, etc). In this sense external non-Abelian fields extend the concept of spin-orbit coupling (Rashba and Dresselhaus couplings), familiar from AMO and condensed matter physics. They lead to yet another variety of fascinating phenomena such as the quantum spin Hall effect, three-dimensional topological insulators, topological superconductors and superfluids of various kinds. One also expects here the appearance of excitations in a form of topological edge states that can support robust transport, or entangled Majorana fermions in the case of topological superconductors or superfluids. Again, while many kinds of topological insulators have been realized in condensed matter systems, a controlled way of creating them in AMO systems and studying quantum phase transitions between various kinds of them is obviously very appealing and challenging. The various systems listed so far correspond to static gauge fields, which are externally imposed by the experimentalists. Even more fascinating is the possibility of generating synthetically dynamical gauge fields, i.e. gauge fields that evolve in time according to an interacting gauge theory, e.g., a full lattice gauge theory (LGT). These dynamical gauge fields can also couple to matter fields, allowing the quantum simulation of such complex systems (notoriously hard to simulate using 'traditional' computers), which are particularly relevant for modern high-energy physics. So far, most of the theoretical proposals concern the simulation of Abelian gauge theories, however, several groups have recently proposed extensions to the non-Abelian scenarios. The scope of the present focused issue of Journal of Physics B is to cover all of these developments, with particular emphasis on the non-Abelian gauge fields. The 14 papers in this issue include contributions from the leading theory groups working in this field; we believe that this collection will provide the reference set for quantum simulations of gauge fields. Although the special issue contains exclusively theoretical proposals and studies, it should be stressed that the progress in experimental studies of artificial Abelian and non-Abelian gauge fields in recent years has been simply spectacular. Multiple leading groups are working on this subject and have already obtained a lot of seminal results. The papers in the special issue are ordered according to the date of acceptance. The issue opens with a review article by Zhou et al [1] on unconventional states of bosons with synthetic spin-orbit coupling. Next, the paper by Maldonado-Mundo et al [2] studies ultracold Fermi gases with artificial Rashba spin-orbit coupling in a 2D gas. Anderson and Charles [3], in contrast, discuss a three-dimensional spin-orbit coupling in a trap. Orth et al [4] investigate correlated topological phases and exotic magnetism with ultracold fermions, again in the presence of artificial gauge fields. The paper of Nascimbène [5] does not address the synthetic gauge fields directly, but describes an experimental proposal for realizing one-dimensional topological superfluids with ultracold atomic gases; obviously, this problem is well situated in the general and growing field of topological superfluids, in particular those realized in the presence of non-Abelian gauge fields/spin-orbit coupling. Graß et al [6] consider in their paper fractional quantum Hall states of a Bose gas with spin-orbit coupling induced by a laser. Particular attention is drawn here to the possibility of realizing states with non-Abelian anyonic excitations. Zheng et al [7] study properties of Bose gases with Raman-induced spin-orbit coupling. Kiffner et al [8] in their paper touch on another kind of system, namely ultracold Rydberg atoms. In particular they study the generation of Abelian and non-Abelian gauge fields in dipole-dipole interacting Rydberg atoms. The behaviour of fermions in synthetic non-Abelian gauge potentials is discussed by Shenoy and Vyasanakere [9]. The paper starts with the study of Rashbon condensates (i.e. Bose condensates in the presence of Rashba coupling) and also introduces novel kinds of exotic Hamiltonians. Goldman et al [10] propose a concrete setup for realizing arbitrary non-Abelian gauge potentials in optical square lattices; they discuss how such synthetic gauge fields can be exploited to generate Chern insulators. Zygelman [11], similarly as Kiffner et al [8], discusses in his paper non-Abelian gauge fields in Rydberg systems. Marchukov et al [12] return to the subject of spin-orbit coupling, and investigate spectral gaps of spin-orbit coupled particles in the realistic situations of deformed traps. The last two papers, in contrast, are devoted to different subjects. Edmonds et al [13] consider a 'dynamical' density-dependent gauge potential, and study the Josephson effect in a Bose-Einstein condensate subject to such a potential. Last, but not least, Mazzucchi et al [14] study the properties of semimetal-superfluid quantum phase transitions in 3D lattices with Dirac points. References [1] Zhou X, Li Y, Cai Z and Wu C 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134001 [2] Maldonado-Mundo D, Öhberg P and Valiente M 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134002 [3] Anderson B M and Clark C W 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134003 [4] Orth P P, Cocks D, Rachel S, Buchhold M, Le Hur K and Hofstetter W 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134004 [5] Nascimbène S 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134005 [6] Graß T, Juliá-Díaz B, Burrello M and Lewenstein M 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134006 [7] Zheng W, Yu Z-Q, Cui X and Zhai H 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134007 [8] Kiffner M, Li W and Jaksch D 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134008 [9] Shenoy V B and Vyasanakere J P 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134009 [10] Goldman N, Gerbier F and Lewenstein M 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134010 [11] Zygelman B 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134011 [12] Marchukov O V, Volosniev A G, Fedorov D V, Jensen A S and Zinner N T 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134012 [13] Edmonds M J, Valiente M and Öhberg P 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134013 [14] Mazzucchi G, Lepori L and Trombettoni A 2013 J. Phys. B: At. Mol. Opt. Phys. 46 134014

Assessment of stretched vortex subgrid-scale models for LES of incompressible inhomogeneous turbulent flow

PubMed Central

Shetty, Dinesh A.; Frankel, Steven H.

2013-01-01

Summary The physical space version of the stretched vortex subgrid scale model [Phys. Fluids 12, 1810 (2000)] is tested in large eddy simulations (LES) of the turbulent lid driven cubic cavity flow. LES is carried out using a higher order finite-difference method [J. Comput. Phys. 229, 8802 (2010)]. The effects of different vortex orientation models and subgrid turbulence spectrums are assessed through comparisons of the LES predictions against direct numerical simulations (DNS) [Phys. Fluids 12, 1363 (2000)]. Three Reynolds numbers 12000, 18000, and 22000 are studied. Good agreement with the DNS data for the mean and fluctuating quantities is observed. PMID:24187423

Dosimetric impacts of microgravity: an analysis of 5th, 50th and 95th percentile male and female astronauts

NASA Astrophysics Data System (ADS)

Bahadori, Amir A.; Van Baalen, Mary; Shavers, Mark R.; Semones, Edward J.; Bolch, Wesley E.

2012-02-01

Computational phantoms serve an important role in organ dosimetry and risk assessment performed at the National Aeronautics and Space Administration (NASA). A previous study investigated the impact on organ dose equivalents and effective doses from the use of the University of Florida hybrid adult male (UFHADM) and adult female (UFHADF) phantoms at differing height and weight percentiles versus those given by the two existing NASA phantoms, the computerized anatomical man (CAM) and female (CAF) (Bahadori et al 2011 Phys. Med. Biol. 56 1671-94). In the present study, the UFHADM and UFHADF phantoms of different body sizes were further altered to incorporate the effects of microgravity. Body self-shielding distributions are generated using the voxel-based ray tracer (VoBRaT), and the results are combined with depth dose data from the NASA codes BRYNTRN and HZETRN to yield organ dose equivalents and their rates for a variety of space radiation environments. It is found that while organ dose equivalents are indeed altered by the physiological effects of microgravity, the magnitude of the change in overall risk (indicated by the effective dose) is minimal for the spectra and simplified shielding configurations considered. The results also indicate, however, that UFHADM and UFHADF could be useful in designing dose reduction strategies through optimized positioning of an astronaut during encounters with solar particle events.

Computation of mass-density images from x-ray refraction-angle images.

PubMed

Wernick, Miles N; Yang, Yongyi; Mondal, Indrasis; Chapman, Dean; Hasnah, Moumen; Parham, Christopher; Pisano, Etta; Zhong, Zhong

2006-04-07

In this paper, we investigate the possibility of computing quantitatively accurate images of mass density variations in soft tissue. This is a challenging task, because density variations in soft tissue, such as the breast, can be very subtle. Beginning from an image of refraction angle created by either diffraction-enhanced imaging (DEI) or multiple-image radiography (MIR), we estimate the mass-density image using a constrained least squares (CLS) method. The CLS algorithm yields accurate density estimates while effectively suppressing noise. Our method improves on an analytical method proposed by Hasnah et al (2005 Med. Phys. 32 549-52), which can produce significant artefacts when even a modest level of noise is present. We present a quantitative evaluation study to determine the accuracy with which mass density can be determined in the presence of noise. Based on computer simulations, we find that the mass-density estimation error can be as low as a few per cent for typical density variations found in the breast. Example images computed from less-noisy real data are also shown to illustrate the feasibility of the technique. We anticipate that density imaging may have application in assessment of water content of cartilage resulting from osteoarthritis, in evaluation of bone density, and in mammographic interpretation.

Biological Modeling Based Outcome Analysis (BMOA) in 3D Conformal Radiation Therapy (3DCRT) Treatments for Lung and Breast Cancers

NASA Astrophysics Data System (ADS)

Pyakuryal, Anil; Chen, Chiu-Hao; Dhungana, Sudarshan

2010-03-01

3DCRT treatments are the most commonly used techniques in the treatment of lung and breast cancers. The purpose of this study was to perform the BMOA of the 3DCRT plans designed for the treatment of breast and lung cancers utilizing HART program (Med. Phys. 36, p.2547(2009)). The BMOA parameters include normal tissue complication probability (NTCP), tumor control probability (TCP), and the complication-free tumor control probability (P+). The 3DCRT plans were designed for (i) the palliative treatment of 8 left lung cancer patients (CPs) at early stage (m=8), (ii) the curative treatment of 8 left lung CPs at stages II and III (k=8), and (iii) the curative treatment of 8 left breast CPs (n=8). The NTCPs were noticeably small (<2%) for heart, lungs and cord in both types of treatments except for the esophagus in lung CPs (k=8). Assessments of the TCPs and P+s also indicated good improvements in local tumor control in all plans. Homogeneous target coverage and improved dose conformality were the major advantages of such techniques in the treatment of breast cancer. These achievements support the efficacy of the 3DCRT techniques for the efficient treatment of various types of cancer.

Second quantization of a covariant relativistic spacetime string in Steuckelberg-Horwitz-Piron theory

NASA Astrophysics Data System (ADS)

Suleymanov, Michael; Horwitz, Lawrence; Yahalom, Asher

2017-06-01

A relativistic 4D string is described in the framework of the covariant quantum theory first introduced by Stueckelberg [ Helv. Phys. Acta 14, 588 (1941)], and further developed by Horwitz and Piron [ Helv. Phys. Acta 46, 316 (1973)], and discussed at length in the book of Horwitz [Relativistic Quantum Mechanics, Springer (2015)]. We describe the space-time string using the solutions of relativistic harmonic oscillator [ J. Math. Phys. 30, 66 (1989)]. We first study the problem of the discrete string, both classically and quantum mechanically, and then turn to a study of the continuum limit, which contains a basically new formalism for the quantization of an extended system. The mass and energy spectrum are derived. Some comparison is made with known string models.

Kinetic water-bag model of global collisional drift waves and ion temperature gradient instabilities in cylindrical geometry

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

Gravier, E.; Plaut, E.

2013-04-15

Collisional drift waves and ion temperature gradient (ITG) instabilities are studied using a linear water-bag kinetic model [P. Morel et al., Phys. Plasmas 14, 112109 (2007)]. An efficient spectral method, already validated in the case of drift waves instabilities [E. Gravier et al., Eur. Phys. J. D 67, 7 (2013)], allows a fast solving of the global linear problem in cylindrical geometry. The comparison between the linear ITG instability properties thus computed and the ones given by the COLUMBIA experiment [R. G. Greaves et al., Plasma Phys. Controlled Fusion 34, 1253 (1992)] shows a qualitative agreement. Moreover, the transition betweenmore » collisional drift waves and ITG instabilities is studied theoretically as a function of the ion temperature profile.« less

The influence of energy standardisation on the alternate Mediterranean diet score and its association with mortality in the Multiethnic Cohort.

PubMed

Shvetsov, Yurii B; Harmon, Brook E; Ettienne, Reynolette; Wilkens, Lynne R; Le Marchand, Loic; Kolonel, Laurence N; Boushey, Carol J

2016-11-01

The alternate Mediterranean diet (aMED) score is an adaptation of the original Mediterranean diet score. Raw (aMED) and energy-standardised (aMED-e) versions have been used. How the diet scores and their association with health outcomes differ between the two versions is unclear. We examined differences in participants' total and component scores and compared the association of aMED and aMED-e with all-cause, CVD and cancer mortality. As part of the Multiethnic Cohort, 193 527 men and women aged 45-75 years from Hawaii and Los Angeles completed a baseline FFQ and were followed up for 13-18 years. The association of aMED and aMED-e with mortality was examined using Cox's regression, with adjustment for total energy intake. The correlation between aMED and aMED-e total scores was lower among people with higher BMI. Participants who were older, leaner, more educated and consumed less energy scored higher on aMED-e components compared with aMED, except for the red and processed meat and alcohol components. Men reporting more physical activity scored lower on most aMED-e components compared with aMED, whereas the opposite was observed for the meat component. Higher scores of both aMED and aMED-e were associated with lower risk of all-cause, CVD and cancer mortality. Although individuals may score differently with aMED and aMED-e, both scores show similar reductions in mortality risk for persons scoring high on the index scale. Either version can be used in studies of diet and mortality. Comparisons can be performed across studies using different versions of the score.

Equilibrium Structure and Vibrational Spectra of Sila-Adamantane

DTIC Science & Technology

2006-10-27

42, 3276 (1990); M. R. Pederson, K. A. Jackson, Phys. Rev. B. 43, 7312 ( 1991 ); M. R. Pederson, D. V. Porezag, J. Kortus, and D. C. Patton, Phys... Pankratov , Phys. Rev. B 68, 085310 (2003); P. H. Han, W. G. Schmidt, and F. Becstedt, Phys. Rev. B 72, 245425 (2005). [13] T. Yamada, T. Inoue, K. Yamada, N

Magnetotransport in Two Dimensional Electron Systems Under Microwave Excitation and in Highly Oriented Pyrolytic Graphite

DTIC Science & Technology

2012-01-01

Phys. Rev. Lett. 82, 2147 (1999). [89] Y. Zhang, Y. Tan, H. L. Stormer and P. Kim, Nature 438, 10 (2005). [90] J. W. McClure, Phys. Rev. 108, 612 (1957...Phys. 2, 595 (2006). [97] H. L. Stormer , J. P. Eisenstein, A. C. Gossard, W. Wiegmann, and K. Baldwin, Phys. Rev. Lett. 56, 85 (1985). [98] B. A...Sadowski, J. M. Schneider, and M. Potemski, J. Phys.: Cond. Matter 20, 454223 (2008). [108] W. Pan, J. S. Xia, H. L. Stormer , D. C. Tsui, C. L

Summer Study Program in Geophysical Fluid Dynamics, Woods Hole Oceanographic Institution: Chaos.

DTIC Science & Technology

1985-11-01

Cleopatra, periodic solutions to Galileo and perhaps chaos to Poincar. Today we often think about dynamical systems in terms o- oincae surfaces of section...P. Berge, 1983. Phys. Rev. Lett. L51, 1446 and 2345. Nadal, J.P., B. Derrida and J. Vannimenus, 1982. J. de Phys. 43, , 1561 and V. Hakim and J.P

Comment on ``A proposal for in vitro/GFR molecular erythema action spectrum'' [J. Appl. Phys. 104, 034701 (2008)

NASA Astrophysics Data System (ADS)

Björn, Lars Olof; de Gruijl, Frank R.; Diffey, Brian; Norval, Mary

2009-06-01

The recent article by de Souza, Lorenzini and Rizzatti [J. A. V. de Souza, F. Lorenzini, and M. R. Rizatti, J. Appl. Phys. 104, 034701 (2008)] in this journal needs corrections and clarifications on several points. The model used by them is not suitable for the study of erythema.

Hydrogen Pumped Iodine Laser Study.

DTIC Science & Technology

1980-07-01

D.W. Naegeli , and i. Glassman, Comb. Sci. Tech.. 8. 231 (1974), 5. L.H. Hall, Appi. Phys. Lett., 27 (6), 335 (1975). 6. R.C. Oldenbor, J.L. Gole, and...4693 �). 3. P. Cadman and J.C. Polanyi, J. Phys. Chem., 72. 3715 (1968). 4. M.L. Zwillengerg, D.W. Naegeli , and 1. Glassman, Comb. Sci. Tech., 8

Low-Energy Mutual Neutralization Studies for Early Universe Hydrogen Chemistry

NASA Astrophysics Data System (ADS)

Urbain, Xavier

2010-03-01

Low-energy interactions between light ions, as they occur in low density plasmas, are ideally studied under merged-beam conditions. This was the motivation for building the dual-source setup in operation at UCL, Louvain-la-Neuve, since the early eighties. Although initially developed for the study of charge exchange [1], mutual neutralization and transfer ionization, this machine has produced a host of total cross section measurements for a wide variety of associative ionization and other reactive processes involving charged reactants, from H^+ to CO^+, in collision with H^-, D^-, C^- and O^- [2]. A recent paper by Glover et al. [3] has revived the interest for mutual neutralization studies, by stressing the need of the astrophysical community for a precise determination of the low-energy cross section of the H^+/H^- reaction. The mutual neutralization acts as a sink for negative ions which otherwise dominate the primordial formation of H2 by associative detachment with ground state H. Absolute measurements in the range 5 meV to 5 eV are needed to rule out earlier experimental work [4] contradicting the most recent theoretical predictions [5]. Our setup is currently modified to incorporate coincident imaging techniques, giving access to differential cross sections besides the branching among accessible neutral channels. Mutual neutralization reactions of H^- with H2^+ and H3^+ will also be investigated, for the role they play in laboratory plasmas [6].[4pt] [1] S. Sz"ucs, M. Karemera, M. Terao, and F. Brouillard, J. Phys. B 17, 1613 (1983).[0pt] [2] E. A. Naji et al., J. Phys. B 31, 4887 (1998), A. Le Padellec et al., J. Chem. Phys., 124, 154304 (2006) and references therein.[0pt] [3] S. C. Glover, D. W. Savin, and A.-K. Jappsen , Astrophys. J. 640, 553 (2006). [0pt] [4] J. Moseley, W. Aberth, and J. R. Peterson, Phys. Rev. Lett. 24, 435 (1970).[0pt] [5] M. Stenrup, å. Larson, and N. Elander, Phys. Rev. A 79, 012713 (2009).[0pt] [6] M. J. J. Eerden et al., Phys. Rev. A 51, 3362 (1995).

EDITORIAL: Cluster issue on Heusler compounds and devices Cluster issue on Heusler compounds and devices

NASA Astrophysics Data System (ADS)

Felser, Claudia; Hillebrands, Burkard

2009-04-01

This is the third cluster issue of Journal Physics D: Applied Physics devoted to half-metallic Heusler compounds and devices utilizing this class of materials. Heusler compounds are named after Fritz Heusler, the owner of a German copper mine, the Isabellenhütte, who discovered this class of materials in 1903 [1]. He synthesized mixtures of Cu2Mn alloys with various main group metals Z = Al, Si, Sn, Sb, which became ferromagnetic despite all constituents being non-magnetic. The recent success story of Heusler compounds began in 1983 with the discovery of the half-metallic electronic structure in NiMnSb [2] and Co2MnZ [3], making these and similar materials, in particular PtMnSb, also useful for magneto-optical data storage media applications due to their high Kerr rotation. The real breakthrough, however, came in 2000 with the observation of a large magnetoresistance effect in Co2Cr0.6Fe0.4Al [4]. The Co2YZ (Y = Ti, Cr, Mn, Fe) compounds are a special class of materials, which follow the Slater-Pauling rule [5], and most of them are half-metallic bulk materials. The electronic structure of Heusler compounds is well understood [6] and Curie temperatures up to 1100 K have been observed [7]. In their contribution to this cluster issue, Thoene et al predict that still higher Curie temperatures can be achieved. A breakthrough from the viewpoint of materials design is the synthesis of nanoparticles of Heusler compounds as reported in the contribution by Basit et al. Nano-sized half- metallic ferromagnets will open new directions for spintronic applications. The challenge, however, is still to produce spintronic devices with well defined interfaces to take advantage of the half-metallicity of the electrodes. Several groups have succeeded in producing excellent tunnel junctions with high magnetoresistance effects at low temperatures and decent values at room temperature [8-11]. Spin-dependent tunnelling characteristics of fully epitaxial magnetic tunnel junctions with a Heusler alloy can be used to obtain information about the half-metallicity and the magnons as reported by Taira et al in this issue. An improvement of the tunnel magnetoresistance effect (TMR) at room temperature could be achieved by shifting the Fermi energy from the edges of the valence or the conduction band into the middle of the gap [12]. In the case of Co2FeSi0.5Al0.5 (CFAS), TMR values higher than 200% can be achieved [13]. The improvement of the interface seems to be important as has been shown by XMCD (x-ray magnetic circular dichroism) [14] and photoemission spectroscopy [15]. The interface magnetization is very often reduced [14]; however, the interface and the surface electron spin polarization can be improved by post annealing as reported by Wüstenberg et al in this issue. High energy photoemission spectroscopy is a new tool for investigating bulk properties of Heusler compounds [16]. In this issue we report on the investigation of a whole device structure by this technique due to the high escape depth inherent to this method in the contribution of Herbort et al. Dynamic correlations might be a reason for the formation of non-quasi-particles such as magnons in the gap [17], which destroy the half-metallicity and thus can be considered as another cause for the reduced TMR at room temperature. Thus correlations have to be taken into account. This is demonstrated for the Heusler compound Co2Mn1 - xFexSi as reported by Chadov et al in this issue. Magneto-optic methods are powerful instruments for investigating magnetic properties of Heusler compounds. The determination of the huge quadratic Kerr effect in the Co2FeSi Heusler compound is a good example [18]. In this issue Hamrle et al and Gaier et al report on the determination of the exchange constant by measuring the magnon dispersion properties using Brillouin light scattering spectroscopy. The magnon dispersion was calculated by Thoene et al. New developments in the field of spintronics go into the direction of the spin-Hall effect, spin-torque investigations and CPP GMR (current perpendicular plane giant magnetoresistance). Schneider et al have studied the Hall effect of laser ablated Co2(MnFe)Si thin films. Recently Inomata's group has reported on a high CPP GMR effect based on CFSA [19]. In this issue a theoretical study by Dai et al reports on the interfaces between CCFA and very thin chromium layers. Here the interface stays half-metallic which is a promising result regarding the realization of potential GMR devices. For spin-torque applications special requirements concerning the materials are necessary. Low damping constants, low magnetic moments and a perpendicular anisotropy are favourable properties. Ferrimagnetic Heusler compounds are candidates for low magnetic moments despite a high spin polarization and a high Curie temperature [20, 21]. Mn3Ga shows additionally a tetragonal distortion, which is favourable for perpendicular anisotropy [21]. The stability of Heusler compounds versus structural distortion is a well known phenomenon in shape memory alloys [22]. We hope this cluster of papers will inspire many researchers in the field of spintronics and motivate some of them to use these advanced materials for new devices. References [1] Heusler F 1903 Verh. Dtsch. Phys. Ges. 12 219 [2] de Groot R A, Müller F M, van Engen P G and Buschow K H J 1983 Phys. Rev. Lett. 50 2024 [3] Kübler J, Williams A R, Sommers C B 1983 Phys. Rev. B 28 1745 [4] Block T, Felser C and Jakob G 2003 J. Solid State Chem. 176 646 [5] Galanakis I, Mavropoulos Ph and Dederichs P H 2006 J. Phys. D: Appl. Phys. 39 765 [6] Kandpal H C, Fecher G H and Felser C 2007 J. Phys. D: Appl. Phys. 40 1507 [7] Wurmehl S, Fecher G H, Kandpal H C, Ksenofontov V, Felser C and Lin H J 2006 Appl. Phys. Lett. 86 032503 [8] Kämmerer S, Thomas A, Hütten A and Reiss G 2004 Appl. Phys. Lett. 85 79 [9] Yamato M, Marukame T, Ishikawa T, Matsuda K, Uemura T and Arita M 2006 J. Phys. D: Appl. Phys. 39 824 [10] Sakuraba Y, Hattori M, Oogane M, Ando Y, Kato H, Sakuma A, Miyazaki T and Kubota H 2006 Appl. Phys. Lett. 88 192508 [11] Inomata K, Okamura S, Miyazaki A, Kikuchi M, Tezuka N, Wojcik M and Jedryka E 2006 J. Phys. D: Appl. Phys. 39 816 [12] Fecher G H and Felser C 2007 J. Phys. D: Appl. Phys. 40 1582 [13] Tezuka N, Ikeda N, Miyazaki A, Sugimoto S, Kikuchi M and Inomata K 2006 Appl. Phys. Lett. 89 112514 [14] Kallmayer M, Schneider H, Jakob G, Elmers H J, Balke B and Cramm S 2007 J. Phys. D: Appl. Phys. 40 1552 [15] Cinchetti M, Wüstenberg J P, Sánchez Albaneda M, Steeb F, Conca A, Jourdan M and Aeschlimann M 2007 J. Phys. D: Appl. Phys. 40 1544 [16] Fecher G H, Balke B, Ouardi S, Felser C, Schonhense G, Ikenaga E, Kim J J, Ueda S and Kobayashi K 2007 J. Phys. D: Appl. Phys. 40 1576 [17] Chioncel L, Sakuraba Y, Arrigoni E, Katsnelson M I, Oogane M, Ando Y, Miyazaki T, Burzo E and Lichtenstein A I 2008 Phys. Rev. Lett. 100 086402 [18] Hamrle J, Blomeier S, Gaier O, Hillebrands B, Schneider H, Jakob G, Postava K and Felser C 2007 J. Phys. D: Appl. Phys. 40 1563 [19] Furubayashi T, Kodama K, Sukegawa H, Takahashi Y K, Inomata K and Hono K 2008 Appl. Phys. Lett. 93 122507 [20] Balke B, Fecher G H, Winterlik J and Felser C 2007 Appl. Phys. Lett. 90 152504 [21] Wurmehl S, Kandpal H C, Fecher G H and Felser C 2006 J. Phys.: Cond. Mat. 18 6171 [22] Entel P, Bucheinikov V D, Khovailo V V, Zayak A T, Adeagbo W A, Gruner M E, Herper H C and Wassermann E F 2006 J. Phys. D: Appl. Phys. 39 865

Isotonic similarities in isotope shifts from Hg to Ra.

NASA Astrophysics Data System (ADS)

Stroke, H. H.

2003-04-01

Isotope shifts (IS) in atomic spectra of heavy elements reflect largely the variation in of the nuclear charge distribution. Our early systematic measurements of IS for an extended range of stable and radioactive isotopes and nuclear isomers in Tl and Hg^1 showed that by displaying the relative IS, normalized to a chosen pair of isotopes, there was a striking similarity for the IS of isotones. This essentially divides out the electronic factor in the IS and allows the comparison of Δ for neighboring Z as N is varied. Following our further studies on Pb and Bi^2 and those on Fr at ISOLDE by the Orsay spectroscopy group^3, we found that the isotonic similarity extended to these elements. Since then, many additional measurements were made, principally at ISOLDE^4, extending to Ra the elements studied. The isotonic shift similarities persist from Z=80 to 88. We noted that the relative isotope and isomer shifts can be used to investigate the polarization of the nucleus by the added neutrons, a model used in a calculation by Barrett.^5 . The new data may serve further in this direction. ^1W,J.Tomlinson, H.H. Stroke, Nucl.Phys. 60, 614 (1964). ^2M. Barboza-Flores et al., Z.Phys. A 321, 85 (1985), ^3S. Liberman et al., Phys .Rev. A 22, 2732 (1980). ^4E,g. M.R. Pearson et al., J.Phys. G 26, 1829 (2000). ^5R.C. Barrett, Nucl. Phys. 88, 128 (1966).

Chemical Reactions at the in vacuo Au/InP Interface.

DTIC Science & Technology

1987-07-25

Phys. C: Solid State Phys. 10, 4545 (1977). 2 A. Hiraki, K. Shuto, S. Kim, W. Kanmnura, and M. Iwami, Appl.Phys. Letts. 31, 611 (1977). 3. P.W. Chye ...Pelous, and P. Henoc, J.Appl.Phys. 52, 5112 (1981). 13. 1. Camlibel, A.K. Chin , F. Ermanis, M.A. DiGiuseppe, J.A. Lourenco and W.A. Bonner

Vanishing Hall conductance in the phase-glass Bose metal at zero temperature

NASA Astrophysics Data System (ADS)

May-Mann, Julian; Phillips, Philip W.

2018-01-01

Motivated in part by numerical simulations [H. G. Katzgraber and A. P. Young, Phys. Rev. B 66, 224507 (2002), 10.1103/PhysRevB.66.224507; J. M. Kosterlitz and N. Akino, Phys. Rev. Lett. 81, 4672 (1998), 10.1103/PhysRevLett.81.4672; Phys. Rev. Lett. 81, 4672 (1998), 10.1103/PhysRevLett.81.4672] that reveal that the energy to create a defect in a gauge or phase glass scales as Lθ with θ <0 for two dimensions, thereby implying a vanishing stiffness, we reexamine the relevance of these kinds of models to the Bose metal in light of the new experiments [N. P. Breznay and Kapitulnik (unpublished); Y. Wang, I. Tamir, D. Shahar, and N. P. Armitage, arXiv:1708.01908 [cond-mat.supr-con

DPEMC: A Monte Carlo for double diffraction

NASA Astrophysics Data System (ADS)

Boonekamp, M.; Kúcs, T.

2005-05-01

We extend the POMWIG Monte Carlo generator developed by B. Cox and J. Forshaw, to include new models of central production through inclusive and exclusive double Pomeron exchange in proton-proton collisions. Double photon exchange processes are described as well, both in proton-proton and heavy-ion collisions. In all contexts, various models have been implemented, allowing for comparisons and uncertainty evaluation and enabling detailed experimental simulations. Program summaryTitle of the program:DPEMC, version 2.4 Catalogue identifier: ADVF Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVF Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer: any computer with the FORTRAN 77 compiler under the UNIX or Linux operating systems Operating system: UNIX; Linux Programming language used: FORTRAN 77 High speed storage required:<25 MB No. of lines in distributed program, including test data, etc.: 71 399 No. of bytes in distributed program, including test data, etc.: 639 950 Distribution format: tar.gz Nature of the physical problem: Proton diffraction at hadron colliders can manifest itself in many forms, and a variety of models exist that attempt to describe it [A. Bialas, P.V. Landshoff, Phys. Lett. B 256 (1991) 540; A. Bialas, W. Szeremeta, Phys. Lett. B 296 (1992) 191; A. Bialas, R.A. Janik, Z. Phys. C 62 (1994) 487; M. Boonekamp, R. Peschanski, C. Royon, Phys. Rev. Lett. 87 (2001) 251806; Nucl. Phys. B 669 (2003) 277; R. Enberg, G. Ingelman, A. Kissavos, N. Timneanu, Phys. Rev. Lett. 89 (2002) 081801; R. Enberg, G. Ingelman, L. Motyka, Phys. Lett. B 524 (2002) 273; R. Enberg, G. Ingelman, N. Timneanu, Phys. Rev. D 67 (2003) 011301; B. Cox, J. Forshaw, Comput. Phys. Comm. 144 (2002) 104; B. Cox, J. Forshaw, B. Heinemann, Phys. Lett. B 540 (2002) 26; V. Khoze, A. Martin, M. Ryskin, Phys. Lett. B 401 (1997) 330; Eur. Phys. J. C 14 (2000) 525; Eur. Phys. J. C 19 (2001) 477; Erratum, Eur. Phys. J. C 20 (2001) 599; Eur. Phys. J. C 23 (2002) 311]. This program implements some of the more significant ones, enabling the simulation of central particle production through color singlet exchange between interacting protons or antiprotons. Method of solution: The Monte Carlo method is used to simulate all elementary 2→2 and 2→1 processes available in HERWIG. The color singlet exchanges implemented in DPEMC are implemented as functions reweighting the photon flux already present in HERWIG. Restriction on the complexity of the problem: The program relying extensively on HERWIG, the limitations are the same as in [G. Marchesini, B.R. Webber, G. Abbiendi, I.G. Knowles, M.H. Seymour, L. Stanco, Comput. Phys. Comm. 67 (1992) 465; G. Corcella, I.G. Knowles, G. Marchesini, S. Moretti, K. Odagiri, P. Richardson, M. Seymour, B. Webber, JHEP 0101 (2001) 010]. Typical running time: Approximate times on a 800 MHz Pentium III: 5-20 min per 10 000 unweighted events, depending on the process under consideration.

Voltage and Pressure Scaling of Streamer Dynamics in a Helium Plasma Jet With N2 CO-Flow (Postprint)

DTIC Science & Technology

2014-08-14

de Wetering, R. Blanc, E. M. van Veldhuizen , and U. Ebert, J. Phys. D: Appl. Phys. 43, 145204 (2010). 26T. M. P. Briels, J. Kos, G. J. J. Winands, E. M... van Veldhuizen , and U. Ebert, J. Phys. D: Appl. Phys. 41, 234004 (2008). 27See http://physics.nist.gov/PhysRefData/ASD for National Institute of...T. Briels, and E. van Velduizen, J. Geophys. Res. 115, A00E43, doi:10.1029/2009JA014867 (2010) and references therein. 25S. Nijdam, F. M. J. H. van

Chaotic and Bifurcating Nonlinear Systems Driven by Noise with Applications to Laser Dynamics

DTIC Science & Technology

1988-12-30

W. o. leich and M. 0. Scully, Phys. Rev. A . 37, 3010 (1988) and ibid, 1261 (1988), and references therein. 14. A . K. Dhara and S. V . G. Menon, J...Fronzoni, F. Moss, R. Mannella and P. V . E. McClintock. Phys. Rev. A 36. 834 (1987) 35. L. Fronzoni, F. Moss and P. V . E. McClintock, Phys. Rev. A . 36...1492 (1987). 36. V . Altares and G. Nicolis, Phys. Rev. A 37. 3630 (1988) 37. R. Lefever and JI Win. Turner. Phys. Rev. Lett. 56, 1631 (1986) 38. K

Relativistically induced transparency acceleration of light ions by an ultrashort laser pulse interacting with a heavy-ion-plasma density gradient

NASA Astrophysics Data System (ADS)

Sahai, Aakash A.; Tsung, Frank S.; Tableman, Adam R.; Mori, Warren B.; Katsouleas, Thomas C.

2013-10-01

The relativistically induced transparency acceleration (RITA) scheme of proton and ion acceleration using laser-plasma interactions is introduced, modeled, and compared to the existing schemes. Protons are accelerated with femtosecond relativistic pulses to produce quasimonoenergetic bunches with controllable peak energy. The RITA scheme works by a relativistic laser inducing transparency [Akhiezer and Polovin, Zh. Eksp. Teor. Fiz 30, 915 (1956); Kaw and Dawson, Phys. FluidsPFLDAS0031-917110.1063/1.1692942 13, 472 (1970); Max and Perkins, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.27.1342 27, 1342 (1971)] to densities higher than the cold-electron critical density, while the background heavy ions are stationary. The rising laser pulse creates a traveling acceleration structure at the relativistic critical density by ponderomotively [Lindl and Kaw, Phys. FluidsPFLDAS0031-917110.1063/1.1693437 14, 371 (1971); Silva , Phys. Rev. E1063-651X10.1103/PhysRevE.59.2273 59, 2273 (1999)] driving a local electron density inflation, creating an electron snowplow and a co-propagating electrostatic potential. The snowplow advances with a velocity determined by the rate of the rise of the laser's intensity envelope and the heavy-ion-plasma density gradient scale length. The rising laser is incrementally rendered transparent to higher densities such that the relativistic-electron plasma frequency is resonant with the laser frequency. In the snowplow frame, trace density protons reflect off the electrostatic potential and get snowplowed, while the heavier background ions are relatively unperturbed. Quasimonoenergetic bunches of velocity equal to twice the snowplow velocity can be obtained and tuned by controlling the snowplow velocity using laser-plasma parameters. An analytical model for the proton energy as a function of laser intensity, rise time, and plasma density gradient is developed and compared to 1D and 2D PIC OSIRIS [Fonseca , Lect. Note Comput. Sci.9783-540410.1007/3-540-47789-6_36 2331, 342 (2002)] simulations. We model the acceleration of protons to GeV energies with tens-of-femtoseconds laser pulses of a few petawatts. The scaling of proton energy with laser power compares favorably to other mechanisms for ultrashort pulses [Schreiber , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.97.045005 97, 045005 (2006); Esirkepov , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.92.175003 92, 175003 (2004); Silva , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.92.015002 92, 015002 (2004); Fiuza , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.109.215001 109, 215001 (2012)].

Efficient excitation of nonlinear phonons via chirped pulses: Induced structural phase transitions

NASA Astrophysics Data System (ADS)

Itin, A. P.; Katsnelson, M. I.

2018-05-01

Nonlinear phononics play important role in strong laser-solid interactions. We discuss a dynamical protocol for efficient phonon excitation, considering recent inspiring proposals: inducing ferroelectricity in paraelectric perovskites, and inducing structural deformations in cuprates [Subedi et al., Phys. Rev. B 89, 220301(R) (2014), 10.1103/PhysRevB.89.220301; Phys. Rev. B 95, 134113 (2017), 10.1103/PhysRevB.95.134113]. High-frequency phonon modes are driven by midinfrared pulses, and coupled to lower-frequency modes those indirect excitations cause structural deformations. We study in more detail the case of KTaO3 without strain, where it was not possible to excite the needed low-frequency phonon mode by resonant driving of the higher frequency one. Behavior of the system is explained using a reduced model of coupled driven nonlinear oscillators. We find a dynamical mechanism which prevents effective excitation at resonance driving. To induce ferroelectricity, we employ driving with sweeping frequency, realizing so-called capture into resonance. The method can be applied to many other related systems.

Two-Dimensional Anisotropic Random Walks: Fixed Versus Random Column Configurations for Transport Phenomena

NASA Astrophysics Data System (ADS)

Csáki, Endre; Csörgő, Miklós; Földes, Antónia; Révész, Pál

2018-04-01

We consider random walks on the square lattice of the plane along the lines of Heyde (J Stat Phys 27:721-730, 1982, Stochastic processes, Springer, New York, 1993) and den Hollander (J Stat Phys 75:891-918, 1994), whose studies have in part been inspired by the so-called transport phenomena of statistical physics. Two-dimensional anisotropic random walks with anisotropic density conditions á la Heyde (J Stat Phys 27:721-730, 1982, Stochastic processes, Springer, New York, 1993) yield fixed column configurations and nearest-neighbour random walks in a random environment on the square lattice of the plane as in den Hollander (J Stat Phys 75:891-918, 1994) result in random column configurations. In both cases we conclude simultaneous weak Donsker and strong Strassen type invariance principles in terms of appropriately constructed anisotropic Brownian motions on the plane, with self-contained proofs in both cases. The style of presentation throughout will be that of a semi-expository survey of related results in a historical context.

Reply to "Comment on `Flow of wet granular materials: A numerical study' "

NASA Astrophysics Data System (ADS)

Khamseh, Saeed; Roux, Jean-Noël; Chevoir, François

2017-07-01

In his Comment on our paper [Phys. Rev. E 92, 022201 (2015), 10.1103/PhysRevE.92.022201], Chareyre criticizes, as inaccurate, the simple approach we adopted to explain the strong enhancement of the quasistatic shear strength of the material caused by capillary cohesion. He also observes that a similar form of the "effective stress" approach, accounting for the capillary shear stress, which we neglected, results in a quantitatively correct prediction of this yield stress. We agree with these remarks, which we deem quite relevant and valuable. We nevertheless point out that the initial approximation, despite ˜25 % errors on shear strength in the worst cases, provides a convenient estimate of the Mohr-Coulomb cohesion of the material, which is directly related to the coordination number. We argue that the effective stress assumption, despite its surprising success in the range of states explored in Khamseh et al. [Phys. Rev. E 92, 022201 (2015), 10.1103/PhysRevE.92.022201], is bound to fail in strongly cohesion-dominated material states.

Interfacial growth as a model of tube-width heterogeneities in concentrated solutions of stiff polymers

NASA Astrophysics Data System (ADS)

Sharma, Rati; Cherayil, Binny J.

2013-06-01

Recent experimental measurements of the distribution P(w) of transverse chain fluctuations w in concentrated solutions of F-actin filaments [B. Wang, J Guan, S. M. Anthony, S. C. Bae, K. S. Schweizer, and S. Granick, Phys. Rev. Lett. 104, 118301 (2010), 10.1103/PhysRevLett.104.118301; J. Glaser, D. Chakraborty, K. Kroy, I. Lauter, M. Degawa, N. Kirchgessner, B. Hoffmann, R. Merkel, and M. Giesen, Phys. Rev. Lett. 105, 037801 (2010)], 10.1103/PhysRevLett.105.037801 are shown to be well-fit to an expression derived from a model of the conformations of a single harmonically confined weakly bendable rod. The calculation of P(w) is carried out essentially exactly within a path integral approach that was originally applied to the study of one-dimensional randomly growing interfaces. Our results are generally as successful in reproducing experimental trends as earlier approximate results obtained from more elaborate many-chain treatments of the confining tube potential.

Statically screened ion potential and Bohm potential in a quantum plasma

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

Moldabekov, Zhandos; Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, 71 Al-Farabi Str., 050040 Almaty; Schoof, Tim

2015-10-15

The effective potential Φ of a classical ion in a weakly correlated quantum plasma in thermodynamic equilibrium at finite temperature is well described by the random phase approximation screened Coulomb potential. Additionally, collision effects can be included via a relaxation time ansatz (Mermin dielectric function). These potentials are used to study the quality of various statically screened potentials that were recently proposed by Shukla and Eliasson (SE) [Phys. Rev. Lett. 108, 165007 (2012)], Akbari-Moghanjoughi (AM) [Phys. Plasmas 22, 022103 (2015)], and Stanton and Murillo (SM) [Phys. Rev. E 91, 033104 (2015)] starting from quantum hydrodynamic (QHD) theory. Our analysis revealsmore » that the SE potential is qualitatively different from the full potential, whereas the SM potential (at any temperature) and the AM potential (at zero temperature) are significantly more accurate. This confirms the correctness of the recently derived [Michta et al., Contrib. Plasma Phys. 55, 437 (2015)] pre-factor 1/9 in front of the Bohm term of QHD for fermions.« less

Two-Dimensional Anisotropic Random Walks: Fixed Versus Random Column Configurations for Transport Phenomena

NASA Astrophysics Data System (ADS)

Csáki, Endre; Csörgő, Miklós; Földes, Antónia; Révész, Pál

2018-06-01

We consider random walks on the square lattice of the plane along the lines of Heyde (J Stat Phys 27:721-730, 1982, Stochastic processes, Springer, New York, 1993) and den Hollander (J Stat Phys 75:891-918, 1994), whose studies have in part been inspired by the so-called transport phenomena of statistical physics. Two-dimensional anisotropic random walks with anisotropic density conditions á la Heyde (J Stat Phys 27:721-730, 1982, Stochastic processes, Springer, New York, 1993) yield fixed column configurations and nearest-neighbour random walks in a random environment on the square lattice of the plane as in den Hollander (J Stat Phys 75:891-918, 1994) result in random column configurations. In both cases we conclude simultaneous weak Donsker and strong Strassen type invariance principles in terms of appropriately constructed anisotropic Brownian motions on the plane, with self-contained proofs in both cases. The style of presentation throughout will be that of a semi-expository survey of related results in a historical context.

Self-correcting quantum memory with a boundary

NASA Astrophysics Data System (ADS)

Hutter, Adrian; Wootton, James R.; Röthlisberger, Beat; Loss, Daniel

2012-11-01

We study the two-dimensional toric-code Hamiltonian with effective long-range interactions between its anyonic excitations induced by coupling the toric code to external fields. It has been shown that such interactions allow an arbitrary increase in the lifetime of the stored quantum information by making L, the linear size of the memory, larger [Chesi , Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.82.022305 82, 022305 (2010)]. We show that for these systems the choice of boundary conditions (open boundaries as opposed to periodic boundary conditions) is not a mere technicality; the influence of anyons produced at the boundaries becomes in fact dominant for large enough L. This influence can be either beneficial or detrimental. In particular, we study an effective Hamiltonian proposed by Pedrocchi [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.83.115415 83, 115415 (2011)] that describes repulsion between anyons and anyon holes. For this system, we find a lifetime of the stored quantum information that grows exponentially in L2 for both periodic and open boundary conditions, although the exponent in the latter case is found to be less favorable. However, L is upper bounded through the breakdown of the perturbative treatment of the underlying Hamiltonian.

Transport and Dynamics in Toroidal Fusion Systems

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

Sovinec, Carl

The study entitled, "Transport and Dynamics in Toroidal Fusion Systems," (TDTFS) applied analytical theory and numerical computation to investigate topics of importance to confining plasma, the fourth state of matter, with magnetic fields. A central focus of the work is how non-thermal components of the ion particle distribution affect the "sawtooth" collective oscillation in the core of the tokamak magnetic configuration. Previous experimental and analytical research had shown and described how the oscillation frequency decreases and amplitude increases, leading to "monster" or "giant" sawteeth, when the non-thermal component is increased by injecting particle beams or by exciting ions with imposedmore » electromagnetic waves. The TDTFS study applied numerical computation to self-consistently simulate the interaction between macroscopic collective plasma dynamics and the non-thermal particles. The modeling used the NIMROD code [Sovinec, Glasser, Gianakon, et al., J. Comput. Phys. 195, 355 (2004)] with the energetic component represented by simulation particles [Kim, Parker, Sovinec, and the NIMROD Team, Comput. Phys. Commun. 164, 448 (2004)]. The computations found decreasing growth rates for the instability that drives the oscillations, but they were ultimately limited from achieving experimentally relevant parameters due to computational practicalities. Nonetheless, this effort provided valuable lessons for integrated simulation of macroscopic plasma dynamics. It also motivated an investigation of the applicability of fluid-based modeling to the ion temperature gradient instability, leading to the journal publication [Schnack, Cheng, Barnes, and Parker, Phys. Plasmas 20, 062106 (2013)]. Apart from the tokamak-specific topics, the TDTFS study also addressed topics in the basic physics of magnetized plasma and in the dynamics of the reversed-field pinch (RFP) configuration. The basic physics work contributed to a study of two-fluid effects on interchange dynamics, where "two-fluid" refers to modeling independent dynamics of electron and ion species without full kinetic effects. In collaboration with scientist Ping Zhu, who received separate support, it was found that the rule-of-thumb criteria on stabilizing interchange has caveats that depend on the plasma density and temperature profiles. This work was published in [Zhu, Schnack, Ebrahimi, et al., Phys. Rev. Lett. 101, 085005 (2008)]. An investigation of general nonlinear relaxation with fluid models was partially supported by the TDTFS study and led to the publication [Khalzov, Ebrahimi, Schnack, and Mirnov, Phys. Plasmas 19, 012111 (2012)]. Work specific to the RFP included an investigation of interchange at large plasma pressure and support for applications [for example, Scheffel, Schnack, and Mirza, Nucl. Fusion 53, 113007 (2013)] of the DEBS code [Schnack, Barnes, Mikic, Harned, and Caramana, J. Comput. Phys. 70, 330 (1987)]. Finally, the principal investigator over most of the award period, Dalton Schnack, supervised a numerical study of modeling magnetic island suppression [Jenkins, Kruger, Hegna, Schnack, and Sovinec, Phys. Plasmas 17, 12502 (2010)].« less

Reply to 'Comment on 'Heavy element production in inhomogeneous big bang nucleosynthesis''

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

Matsuura, Shunji; Fujimoto, Shin-ichirou; Hashimoto, Masa-aki

2007-03-15

This is a reply to Rauscher [Phys. Rev. D 75, 068301 (2007)]. We studied heavy element production in the high baryon density region in the early universe [Phys. Rev. D 72, 123505 (2005)]. However, it is claimed by Rauscher [Phys. Rev. D 75, 068301 (2007)] that a small scale but high baryon density region contradicts observations for the light element abundance or, in order not to contradict the observations, the high density region must be so small that it cannot affect the present heavy element abundance. In this paper, we study big bang nucleosynthesis in the high baryon density regionmore » and show that in certain parameter spaces it is possible to produce enough of the heavy element without contradiction to cosmic microwave background and light element observations.« less

Impact of Duality Violations on Spectral Sum Rule analyses

NASA Astrophysics Data System (ADS)

Catà, Oscar

2007-02-01

Recent sum rule analyses on the two-point correlator have led to significant discrepancies in the values found for the OPE condensates, most dramatically in the dimension eight condensate and to a lesser extent in the dimension six one [R. Barate et al., ALEPH Collaboration, Eur. Phys. J. C 4 (1998) 409; K. Ackerstaff et al., OPAL Collaboration, Eur. Phys. J. C 7 (1999) 571, arXiv:hep-ex/9808019; S. Peris, B. Phily and E. de Rafael, Phys. Rev. Lett. 86 (2001) 14, arXiv:hep-ph/0007338; S. Friot, D. Greynat and E. de Rafael, JHEP 0410 (2004) 043, arXiv:hep-ph/0408281; M. Davier, L. Girlanda, A. Hocker and J. Stern, Phys. Rev. D 58 (1998) 096014, arXiv:hep-ph/9802447; B.L. Ioffe and K.N. Zyablyuk, Nucl. Phys. A 687 (2001) 437, arXiv:hep-ph/0010089. K.N. Zyablyuk, Eur. Phys. J. C 38 (2004) 215, arXiv:hep-ph/0404230; J. Bijnens, E. Gamiz and J. Prades, JHEP 0110 (2001) 009, arXiv:hep-ph/0108240; C.A. Dominguez and K. Schilcher, Phys. Lett. B 581 (2004) 193, arXiv:hep-ph/0309285; J. Rojo and J. I. Latorre, JHEP 0401 (2004) 055, arXiv:hep-ph/0401047; V. Cirigliano, E. Golowich and K. Maltman, Phys. Rev. D 68 (2003) 054013, arXiv:hep-ph/0305118; S. Ciulli, C. Sebu, K. Schilcher and H. Spiesberger, Phys. Lett. B 595 (2004) 359, arXiv:hep-ph/0312212. S. Narison, arXiv:hep-ph/0412152]. Precise knowledge of these condensates is of relevance in kaon decays [M. Knecht, S. Peris and E. de Rafael, Phys. Lett. B 457 (1999) 227, arXiv:hep-ph/9812471; J.F. Donoghue and E. Golowich, Phys. Lett. B 478 (2000) 172, arXiv:hep-ph/9911309; M. Knecht, S. Peris and E. de Rafael, Phys. Lett. B 508 (2001) 117, arXiv:hep-ph/0102017] and therefore it seems mandatory to assess the actual impact of what is commonly neglected in spectral sum rules, most prominently the issue of duality violations. We will explicitly compute them in a toy model and show that they are a priori non-negligible.

Exploring the High-Pressure Behavior of PETN: A Combined Quantum Mechanical and Experimental Study

DTIC Science & Technology

2006-11-01

calculations to explore the hypothesized compression-induced polymorphic phase transition [Gruzdkov 2004]. The initial crystal in these Figure 4...Scuseria, G.E., and Chabalowski, C.F. 2004: An ab Initio Study of Solid Nitromethane, HMX , RDX , and CL20: Successes and Failures of DFT. J. Phys. Chem... RDX , HMX , HNIW, and PETN Crystals. J. Phys. Chem. B, 103, 6783. Trotter, J., 1963: Bond lengths and angles in Pentaerythritol Tetranitrate. Acta

``Ideal glassformers'' vs ``ideal glasses'': Studies of crystal-free routes to the glassy state by ``potential tuning'' molecular dynamics, and laboratory calorimetry

NASA Astrophysics Data System (ADS)

Kapko, Vitaliy; Zhao, Zuofeng; Matyushov, Dmitry V.; Austen Angell, C.

2013-03-01

The ability of some liquids to vitrify during supercooling is usually seen as a consequence of the rates of crystal nucleation (and/or crystal growth) becoming small [D. R. Uhlmann, J. Non-Cryst. Solids 7, 337 (1972), 10.1016/0022-3093(72)90269-4] - and thus a matter of kinetics. However, there is evidence dating back to the empirics of coal briquetting for maximum trucking efficiency [D. Frenkel, Physics 3, 37 (2010), 10.1103/Physics.3.37] that some object shapes find little advantage in self-assembly to ordered structures - meaning random packings prevail. Noting that key studies of non-spherical object packing have never been followed from hard ellipsoids [A. Donev, F. H. Stillinger, P. M. Chaikin, and S. Torquato, Phys. Rev. Lett. 92, 255506 (2004), 10.1103/PhysRevLett.92.255506; A. Donev, I. Cisse, D. Sachs, E. A. Variano, F. H. Stillinger, R. Connelly, S. Torquato, and P. M. Chaikin, Science 303, 990 (2004), 10.1126/science.1093010] or spherocylinders [S. R. Williams and A. P. Philipse, Phys. Rev. E 67, 051301 (2003), 10.1103/PhysRevE.67.051301] (diatomics excepted [S.-H. Chong, A. J. Moreno, F. Sciortino, and W. Kob, Phys. Rev. Lett. 94, 215701 (2005), 10.1103/PhysRevLett.94.215701] into the world of molecules with attractive forces, we have made a molecular dynamics study of crystal melting and glass formation on the Gay-Berne (G-B) model of ellipsoidal objects [J. G. Gay and B. J. Berne, J. Chem. Phys. 74, 3316 (1981), 10.1063/1.441483] across the aspect ratio range of the hard ellipsoid studies. Here, we report that in the aspect ratio range of maximum ellipsoid packing efficiency, various G-B crystalline states that cannot be obtained directly from the liquid, disorder spontaneously near 0 K and transform to liquids without any detectable enthalpy of fusion. Without claiming to have proved the existence of single component examples, we use the present observations, together with our knowledge of non-ideal mixing effects, to discuss the probable existence of "ideal glassformers" - single or multicomponent liquids that vitrify before ever becoming metastable with respect to crystals. We find evidence that "ideal glassformer" systems might also be highly fragile systems, approaching the "ideal glass" condition. We link this to the high "volume fragility" behavior observed in recent hard dumbbell studies at similar length/diameter ratios [R. Zhang and K. S. Schweitzer, J. Chem. Phys. 133, 104902 (2010), 10.1063/1.3483601]. The discussion suggests some unusual systems for laboratory study. Using differential scanning calorimetry detection of fusion points Tm, liquidus temperatures Tl, and glass transition temperatures Tg, we describe a system that would seem incapable of crystallizing before glass transition, i.e., an "ideal glassformer." The existence of crystal-free routes to the glassy state will eliminate precrystalline fluctuations as a source of the dynamic heterogeneities that are generally considered important in the discussion of the "glassy state problem [P. W. Anderson, Science 267, 1615 (1995), 10.1126/science.267.5204.1615-e]."

Prevalence and clinical significance of mediator complex subunit 12 mutations in 362 Han Chinese samples with uterine leiomyoma.

PubMed

Wu, Juan; Zou, Yang; Luo, Yong; Guo, Jiu-Bai; Liu, Fa-Ying; Zhou, Jiang-Yan; Zhang, Zi-Yu; Wan, Lei; Huang, Ou-Ping

2017-07-01

Uterine leiomyomas (ULs) are the most common gynecological benign tumors originating from the myometrium. Prevalent mutations in the mediator complex subunit 12 (MED12) gene have been identified in ULs, and functional evidence has revealed that these mutations may promote the development of ULs. However, whether MED12 mutations are associated with certain clinical characteristics in ULs remains largely unknown. In the present study, the potential mutations of MED12 and its paralogous gene, mediator complex subunit 12-like (MED12L), were screened in 362 UL tumors from Han Chinese patients. A total of 158 out of 362 UL tumors (43.6%) were identified as harboring MED12 somatic mutations, and the majority of these mutations were restricted to the 44th residue. MED12 mutations were also observed in 2 out of 145 (1.4%) adjacent control myometrium. Furthermore, the mutation spectrum of MED12 in the concurrent leiomyomas was noticeably different. Correlation analysis of MED12 mutations with the available clinical features indicated that patients with mutated MED12 tended to have smaller cervical diameters. By contrast, no MED12L mutation was identified in the present samples. In summary, the present study demonstrated the presence of prevalent MED12 somatic mutations in UL samples, and the MED12 mutation was associated with smaller cervical diameters. The low mutation frequency of MED12 in adjacent control myometrium indicated that MED12 mutation may be an early event in the pathogenesis of ULs. Furthermore, MED12 mutation status in concurrent tumors from multiple leiomyomas supported several prior observations that the majority of these tumors arose independently.

Physics of the Cosmos Program Analysis Group (PhysPAG) Report

NASA Astrophysics Data System (ADS)

Nousek, John A.

2015-01-01

The Physics of the Cosmos Program Analysis Group (PhysPAG) serves as a forum for soliciting and coordinating input and analysis from the scientific community in support of the PCOS program objectives. I will outline the activities of the PhysPAG over the past year, since the last meeting during the AAS meeting in National Harbor, and mention the activities of the PhysPAG related Scientific Interest Groups.

Nonequilibrium Plasma Research

DTIC Science & Technology

2010-05-01

Kulikovsky, IEEE Trans. Plasma Sci. 25, 439 (1997). 61. W. Yi and P. Williams, J. Phys. D: Appl. Phys. 35, 205 (2002). 62. E. van Veldhuizen and W...Rutgers, J. Phys. D: Appl. Phys. 35, 2169 (2002). 63. E. van Veldhuizen , A. Baede, D. Hayashi, and W. Rutgers, APP Spring Meeting (Bad Honnef...Nonequilibrium Air Plasmas at Atmosphere Pressure, (Institute of Physics, Bristol, UK 2005) Review Article: P. Bletzinger, B. N. Ganguly, D. Van Wie and

Impurity and Defect Characterization in Epitaxial GaAs, InP and the Ternary and Quaternary Compound Semiconductors.

DTIC Science & Technology

1982-11-02

Wolfe, Phys. Rev. Lett. 27, 988 (1971). 5. H.R. Fetterman , D.M. Larsen, G.E. Stillman, P.E. Tannenwald, and J. Waldman, Phys.Rev. Lett. 26. 975(1971). 6...Kirkman, P.E. Simmonds, and R.A. Stradling, J. Phys. C., Solid State Phys. 8, 530 (1975). 18. H.R. Fetterman , J. Waldman and C.M. Wolfe, Solid State Commun

Summary of PhysPAG Activity

NASA Astrophysics Data System (ADS)

Nousek, John A.

2014-01-01

The Physics of the Cosmos Program Analysis Group (PhysPAG) is responsible for solicitiing and coordinating community input for the development and execution of NASA's Physics of the Cosmos (PCOS) program. In this session I will report on the activity of the PhysPAG, and solicit community involvement in the process of defining PCOS objectives, planning SMD architecture, and prioritizing PCOS activities. I will also report on the activities of the PhysPAG Executive Committee, which include the chairs of the Science Analysis Groups/ Science Interest Groups which fall under the PhysPAG sphere of interest. Time at the end of the presentation willl be reserved for questions and discussion from the community.

Fixed node diffusion Monte Carlo using a genetic algorithm: a study of the CO-(4)He(N) complex, N = 1…10.

PubMed

Ramilowski, Jordan A; Farrelly, David

2012-06-14

The diffusion Monte Carlo (DMC) method is a widely used algorithm for computing both ground and excited states of many-particle systems; for states without nodes the algorithm is numerically exact. In the presence of nodes approximations must be introduced, for example, the fixed-node approximation. Recently we have developed a genetic algorithm (GA) based approach which allows the computation of nodal surfaces on-the-fly [Ramilowski and Farrelly, Phys. Chem. Chem. Phys., 2010, 12, 12450]. Here GA-DMC is applied to the computation of rovibrational states of CO-(4)He(N) complexes with N≤ 10. These complexes have been the subject of recent high resolution microwave and millimeter-wave studies which traced the onset of microscopic superfluidity in a doped (4)He droplet, one atom at a time, up to N = 10 [Surin et al., Phys. Rev. Lett., 2008, 101, 233401; Raston et al., Phys. Chem. Chem. Phys., 2010, 12, 8260]. The frequencies of the a-type (microwave) series, which correlate with end-over-end rotation in the CO-(4)He dimer, decrease from N = 1 to 3 and then smoothly increase. This signifies the transition from a molecular complex to a quantum solvated system. The frequencies of the b-type (millimeter-wave) series, which evolves from free rotation of the rigid CO molecule, initially increase from N = 0 to N∼ 6 before starting to decrease with increasing N. An interesting feature of the b-type series, originally observed in the high resolution infra-red (IR) experiments of Tang and McKellar [J. Chem. Phys., 2003, 119, 754] is that, for N = 7, two lines are observed. The GA-DMC algorithm is found to be in good agreement with experimental results and possibly detects the small (∼0.7 cm(-1)) splitting in the b-series line at N = 7. Advantages and disadvantages of GA-DMC are discussed.

Supplementary searches of PubMed to improve currency of MEDLINE and MEDLINE In-Process searches via Ovid.

PubMed

Duffy, Steven; de Kock, Shelley; Misso, Kate; Noake, Caro; Ross, Janine; Stirk, Lisa

2016-10-01

The research investigated whether conducting a supplementary search of PubMed in addition to the main MEDLINE (Ovid) search for a systematic review is worthwhile and to ascertain whether this PubMed search can be conducted quickly and if it retrieves unique, recently published, and ahead-of-print studies that are subsequently considered for inclusion in the final systematic review. Searches of PubMed were conducted after MEDLINE (Ovid) and MEDLINE In-Process (Ovid) searches had been completed for seven recent reviews. The searches were limited to records not in MEDLINE or MEDLINE In-Process (Ovid). Additional unique records were identified for all of the investigated reviews. Search strategies were adapted quickly to run in PubMed, and reviewer screening of the results was not time consuming. For each of the investigated reviews, studies were ordered for full screening; in six cases, studies retrieved from the supplementary PubMed searches were included in the final systematic review. Supplementary searching of PubMed for studies unavailable elsewhere is worthwhile and improves the currency of the systematic reviews.

Supplementary searches of PubMed to improve currency of MEDLINE and MEDLINE In-Process searches via Ovid

PubMed Central

Duffy, Steven; de Kock, Shelley; Misso, Kate; Noake, Caro; Ross, Janine; Stirk, Lisa

2016-01-01

Objective The research investigated whether conducting a supplementary search of PubMed in addition to the main MEDLINE (Ovid) search for a systematic review is worthwhile and to ascertain whether this PubMed search can be conducted quickly and if it retrieves unique, recently published, and ahead-of-print studies that are subsequently considered for inclusion in the final systematic review. Methods Searches of PubMed were conducted after MEDLINE (Ovid) and MEDLINE In-Process (Ovid) searches had been completed for seven recent reviews. The searches were limited to records not in MEDLINE or MEDLINE In-Process (Ovid). Results Additional unique records were identified for all of the investigated reviews. Search strategies were adapted quickly to run in PubMed, and reviewer screening of the results was not time consuming. For each of the investigated reviews, studies were ordered for full screening; in six cases, studies retrieved from the supplementary PubMed searches were included in the final systematic review. Conclusion Supplementary searching of PubMed for studies unavailable elsewhere is worthwhile and improves the currency of the systematic reviews. PMID:27822154

Quantum-Critical Dynamics of the Skyrmion Lattice.

NASA Astrophysics Data System (ADS)

Green, Andrew G.

2002-03-01

Slightly away from exact filling of the lowest Landau level, the quantum Hall ferromagnet contains a finite density of magnetic vortices or Skyrmions[1,2]. These Skyrmions are expected to form a square lattice[3], the low energy excitations of which (translation/phonon modes and rotation/breathing modes) lead to dramatically enhanced nuclear relaxation[4,5]. Upon changing the filling fraction, the rotational modes undergo a quantum phase transition where zero-point fluctuations destroy the orientational order of the Skyrmions[4,6]. I will discuss the effect of this quantum critical point upon nuclear spin relaxation[7]. [1]S. L. Sondhi et al., Phys. Rev. B47, 16419 (1993). [2]S. E. Barrett et al., Phys. Rev. Lett. 74, 5112 (1995), A. Schmeller et al., Phys. Rev. Lett. 75, 4290 (1995). [3]L. Brey et al, Phys. Rev. Lett. 75, 2562 (1995). [4]R. Côté et al., Phys. Rev. Lett. 78, 4825 (1997). [5]R. Tycko et al., Science 268, 1460 (1995). [6]Yu V. Nazarov and A. V. Khaetskii, Phys. Rev. Lett. 80, 576 (1998). [7]A. G. Green, Phys. Rev. B61, R16 299 (2000).

Reynolds number effects on the single-mode Richtmyer-Meshkov instability

NASA Astrophysics Data System (ADS)

Walchli, B.; Thornber, B.

2017-01-01

The Reynolds number effects on the nonlinear growth rates of the Richtmyer-Meshkov instability are investigated using two-dimensional numerical simulations. A decrease in Reynolds number gives an increased time to reach nonlinear saturation, with Reynolds number effects only significant in the range Re<256 . Within this range there is a sharp change in instability properties. The bubble and spike amplitudes move towards equal size at lower Reynolds numbers and the bubble velocities decay faster than predicted by Sohn's model [S.-I. Sohn, Phys. Rev. E 80, 055302 (2009), 10.1103/PhysRevE.80.055302]. Predicted amplitudes show reasonable agreement with the existing theory of Carles and Popinet [P. Carles and S. Popinet, Phys. Fluids Lett. 13, 1833 (2001), 10.1063/1.1377863; Eur. J. Mech. B 21, 511 (2002), 10.1016/S0997-7546(02)01199-8] and Mikaelian [K. O. Mikaelian, Phys. Rev. E 47, 375 (1993), 10.1103/PhysRevE.47.375; K. O. Mikaelian, Phys. Rev. E 87, 031003 (2013), 10.1103/PhysRevE.87.031003], with the former being the closest match to the current computations.

PERSPECTIVE: Physical aspects of cancer invasion

NASA Astrophysics Data System (ADS)

Guiot, Caterina; Pugno, Nicola; Delsanto, Pier Paolo; Deisboeck, Thomas S.

2007-12-01

Invasiveness, one of the hallmarks of tumor progression, represents the tumor's ability to expand into the host tissue by means of several complex biochemical and biomechanical processes. Since certain aspects of the problem present a striking resemblance with well-known physical mechanisms, such as the mechanical insertion of a solid inclusion in an elastic material specimen (G Eaves 1973 The invasive growth of malignant tumours as a purely mechanical process J. Pathol. 109 233; C Guiot, N Pugno and P P Delsanto 2006 Elastomechanical model of tumor invasion Appl. Phys. Lett. 89 233901) or a water drop impinging on a surface (C Guiot, P P Delsanto and T S Deisboeck 2007 Morphological instability and cancer invasion: a 'splashing water drop' analogy Theor. Biol. Med. Model 4 4), we propose here an analogy between these physical processes and a cancer system's invasive branching into the surrounding tissue. Accounting for its solid and viscous properties, we then arrive, as a unifying model, to an analogy with a granular solid. While our model has been explicitly formulated for multicellular tumor spheroids in vitro, it should also contribute to a better understanding of tumor invasion in vivo.

SpekCalc: a program to calculate photon spectra from tungsten anode x-ray tubes.

PubMed

Poludniowski, G; Landry, G; DeBlois, F; Evans, P M; Verhaegen, F

2009-10-07

A software program, SpekCalc, is presented for the calculation of x-ray spectra from tungsten anode x-ray tubes. SpekCalc was designed primarily for use in a medical physics context, for both research and education purposes, but may also be of interest to those working with x-ray tubes in industry. Noteworthy is the particularly wide range of tube potentials (40-300 kVp) and anode angles (recommended: 6-30 degrees) that can be modelled: the program is therefore potentially of use to those working in superficial/orthovoltage radiotherapy, as well as diagnostic radiology. The utility is free to download and is based on a deterministic model of x-ray spectrum generation (Poludniowski 2007 Med. Phys. 34 2175). Filtration can be applied for seven materials (air, water, Be, Al, Cu, Sn and W). In this note SpekCalc is described and illustrative examples are shown. Predictions are compared to those of a state-of-the-art Monte Carlo code (BEAMnrc) and, where possible, to an alternative, widely-used, spectrum calculation program (IPEM78).

Thermoluminescent dosimetry in electron beams: energy dependence.

PubMed

Robar, V; Zankowski, C; Olivares Pla, M; Podgorsak, E B

1996-05-01

The response of thermoluminescent dosimeters to electron irradiations depends on the radiation dose, mean electron energy at the position of the dosimeter in phantom, and the size of the dosimeter. In this paper the semi-empirical expression proposed by Holt et al. [Phys. Med. Biol. 20, 559-570 (1975)] is combined with the calculated electron dose fraction to determine the thermoluminescent dosimetry (TLD) response as a function of the mean electron energy and the dosimeter size. The electron and photon dose fractions, defined as the relative contributions of electrons and bremsstrahlung photons to the total dose for a clinical electron beam, are calculated with Monte Carlo techniques using EGS4. Agreement between the calculated and measured TLD response is very good. We show that the considerable reduction in TLD response per unit dose at low electron energies, i.e., at large depths in phantom, is offset by an ever-increasing relative contribution of bremsstrahlung photons to the total dose of clinical electron beams. This renders the TLD sufficiently reliable for dose measurements over the entire electron depth dose distribution despite the dependence of the TLD response on electron beam energy.

Evaluation of the sensitivity and fading characteristics of an image plate system for x-ray diagnostics

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

Meadowcroft, A. L.; Bentley, C. D.; Stott, E. N.

2008-11-15

Image plates (IPs) are a reusable recording media capable of detecting ionizing radiation, used to diagnose x-ray emission from laser-plasma experiments. Due to their superior performance characteristics in x-ray applications [C. C. Bradford, W. W. Peppler, and J. T. Dobbins III, Med. Phys. 26, 27 (1999) and J. Digit. Imaging. 12, 54 (1999)], the Fuji Biological Analysis System (BAS) IPs are fielded on x-ray diagnostics for the HELEN laser by the Plasma Physics Department at AWE. The sensitivities of the Fuji BAS IPs have been absolutely calibrated for absolute measurements of x-ray intensity in the energy range of 0-100 keV.more » In addition, the Fuji BAS IP fading as a function of time was investigated. We report on the characterization of three Fuji BAS IP responses to x-rays using a radioactive source, and discrete x-ray line energies generated by the Excalibur soft x-ray facility and the Defense Radiological Standards Centre filter-fluorescer hard x-ray system at AWE.« less

Intrinsic Mechanisms of Multi-Layer Ceramic Capacitor Failure.

DTIC Science & Technology

1984-04-01

Properties on the Electric Transport in ABO Perovskites ", Phys. 3Stat. Sol. (a) 75, 143 (1983). [10] S. A. Long and R. N. Blumenthal, "Ti-Rich...Bauerle, "Influence Ed.), John Wiley and Sons (1981). of Bulk and Interface Properties on the Electric Transport in ABO Perovskites ", Phys. Stat. Sol...48 4. THERMOELECTRIC MEASUREMENTS ..... .............. .. 51 5. OTHER STUDIES ........ .................... 60 5.1 Impedance Dispersion

Low Energy Electron Diffraction (LEED)-Auger-Thin-Layer Electrochemical Studies of the Underpotential Deposition of Lead onto Gold Single Crystals.

DTIC Science & Technology

1979-12-15

i’attcns for Clean Au. SinlY \\’ td Fim aroid 107. f-set ting: Q.’ fxposurL INC t ir...12, 1975, pp. 107-124 IFF -169- 103. G. E. Rhead, J. Phys. F:- Metal Phys., 3, L53 (1973). 104. C. S. McKee, M. W. Robaerts and M. L. Williams

Elasticity of fluorite at high temperatures

NASA Astrophysics Data System (ADS)

Eke, J.; Tennakoon, S.; Mookherjee, M.

2017-12-01

Fluorite (CaF2) is a simple halide with cubic space group symmetry (Fm-3m) and is often used as an internal pressure calibrant in moderate high-pressure/high-temperature experiments [1]. In order to gain insight into the elastic behavior of fluorite, we have conducted Resonant Ultrasound Spectroscopy (RUS) on a single crystal of fluorite with rectangular parallelepiped geometry. Using single crystal X-ray diffraction, we aligned the edges of the rectangular parallelepiped with [-1 1 1], [-1 1 -2], and [-1 -1 0] crystallographic directions. We conducted the RUS measurements up to 620 K. RUS spectra are influenced by the geometry, density, and the full elastic moduli tensor of the material. In our high-temperature RUS experiments, the geometry and density were constrained using thermal expansion from previous studies [2]. We determined the elasticity by minimizing the difference between observed resonance and calculated Eigen frequency using Rayleigh-Ritz method [3]. We found that at room temperature, the single crystal elastic moduli for fluorite are 170, 49, and 33 GPa for C11, C12, and C44 respectively. At room temperatures, the aggregate bulk modulus (K) is 90 GPa and the shear modulus (G) is 43 GPa. We note that the elastic moduli and sound wave velocities decrease linearly as a function of temperature with dVP /dT and dVS /dT being -9.6 ×10-4 and -5.0 ×10-4 km/s/K respectively. Our high-temperature RUS results are in good agreement with previous studies on fluorite using both Ultrasonic methods and Brillouin scattering [4,5]. Acknowledgement: This study is supported by US NSF awards EAR-1639552 and EAR-1634422. References: [1] Speziale, S., Duffy, T. S. 2002, Phys. Chem. Miner., 29, 465-472; [2] Roberts, R. B., White, G. K., 1986, J. Phys. C: Solid State Phys., 19, 7167-7172. [3] Migliori, A., Maynard, J. D., 2005, Rev. Sci. Instrum., 76, 121301. [4] Catlow, C. R. A., Comins, J. D., Germano, F. A., Harley, R. T., Hayes, W., 1978, J. Phys. C Solid State Phys., 11, 3197; [5] Jones, L. E. A., 1977, Phys. Earth Planet. Inter., 15(1), 77-89.

Reply to "Comment on `Particle path through a nested Mach-Zehnder interferometer' "

NASA Astrophysics Data System (ADS)

Griffiths, Robert B.

2018-02-01

While much of the technical analysis in the preceding Comment is correct, in the end it confirms the conclusion reached in my previous work [Phys. Rev. A 94, 032115 (2016), 10.1103/PhysRevA.94.032115]: A consistent histories analysis provides no support for the claim of counterfactual quantum communication put forward by Salih et al. [Phys. Rev. Lett. 110, 170502 (2013), 10.1103/PhysRevLett.110.170502].

One-loop light-cone QCD, effective action for reggeized gluons and QCD RFT calculus

NASA Astrophysics Data System (ADS)

Bondarenko, S.; Lipatov, L.; Pozdnyakov, S.; Prygarin, A.

2017-09-01

The effective action for reggeized gluons is based on the gluodynamic Yang-Mills Lagrangian with external current for longitudinal gluons added, see Lipatov (Nucl Phys B 452:369, 1995; Phys Rep 286:131, 1997; Subnucl Ser 49:131, 2013; Int J Mod Phys Conf Ser 39:1560082, 2015; Int J Mod Phys A 31(28/29):1645011, 2016; EPJ Web Conf 125:01010, 2016). On the base of classical solutions, obtained in Bondarenko et al. (Eur Phys J C 77(8):527, 2017), the one-loop corrections to this effective action in light-cone gauge are calculated. The RFT calculus for reggeized gluons similarly to the RFT introduced in Gribov (Sov Phys JETP 26:414, 1968) is proposed and discussed. The correctness of the results is verified by calculation of the propagators of A+ and A- reggeized gluons fields and application of the obtained results is discussed as well.

Entanglement spectrum and boundary theories with projected entangled-pair states

NASA Astrophysics Data System (ADS)

Cirac, J. Ignacio; Poilblanc, Didier; Schuch, Norbert; Verstraete, Frank

2011-06-01

In many physical scenarios, close relations between the bulk properties of quantum systems and theories associated with their boundaries have been observed. In this work, we provide an exact duality mapping between the bulk of a quantum spin system and its boundary using projected entangled-pair states. This duality associates to every region a Hamiltonian on its boundary, in such a way that the entanglement spectrum of the bulk corresponds to the excitation spectrum of the boundary Hamiltonian. We study various specific models: a deformed AKLT model [I. Affleck, T. Kennedy, E. H. Lieb, and H. Tasaki, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.59.799 59, 799 (1987)], an Ising-type model [F. Verstraete, M. M. Wolf, D. Perez-Garcia, and J. I. Cirac, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.96.220601 96, 220601 (2006)], and Kitaev’s toric code [A. Kitaev, Ann. Phys.APNYA60003-491610.1016/S0003-4916(02)00018-0 303, 2 (2003)], both in finite ladders and in infinite square lattices. In the second case, some of those models display quantum phase transitions. We find that a gapped bulk phase with local order corresponds to a boundary Hamiltonian with local interactions, whereas critical behavior in the bulk is reflected on a diverging interaction length of the boundary Hamiltonian. Furthermore, topologically ordered states yield nonlocal Hamiltonians. Because our duality also associates a boundary operator to any operator in the bulk, it in fact provides a full holographic framework for the study of quantum many-body systems via their boundary.

Surrogacy of progression free survival for overall survival in metastatic breast cancer studies: Meta-analyses of published studies.

PubMed

Kundu, Madan G; Acharyya, Suddhasatta

2017-02-01

PFS is often used as a surrogate endpoint for OS in metastatic breast cancer studies. We have evaluated the association of treatment effect on PFS with significant HR OS (and how this association is affected by other factors) in published prospective metastatic breast cancer studies. A systematic literature search in PubMed identified prospective metastatic breast cancer studies. Treatment effects on PFS were determined using hazard ratio (HR PFS ), increase in median PFS (ΔMED PFS ) and % increase in median PFS (%ΔMED PFS ). Diagnostic accuracy of PFS measures (HR PFS , ΔMED PFS and %ΔMED PFS ) in predicting significant HR OS was assessed using receiver operating characteristic (ROC) curves and classification tree approach (CART). Seventy-four cases (i.e., treatment to control comparisons) from 65 individual publications were identified for the analyses. Of these, 16 cases reported significant treatment effect on HR OS at 5% level of significance. Median number of deaths reported in these cases were 153. Area under the ROC curve (AUC) for diagnostic measures as HR PFS , ΔMED PFS and %ΔMED PFS were 0.69, 0.70 and 0.75, respectively. Classification tree results identified %ΔMED PFS and number of deaths as diagnostic measure for significant HR OS . Only 7.9% (3/39) cases with ΔMED PFS shorter than 48.27% reported significant HR OS . There were 7 cases with ΔMED PFS of 48.27% or more and number of deaths reported as 227 or more - of these 5 cases reported significant HR OS . %ΔMED PFS was found to be a better diagnostic measure for predicting significant HR OS . Our analysis results also suggest that consideration of total number of deaths may further improve its diagnostic performance. Based on our study results, the studies with 50% improvement in median PFS are more likely to produce significant HR OS if the total number of OS events at the time of analysis is 227 or more. Copyright © 2016 Elsevier Inc. All rights reserved.

Comment on ``The application of the thermodynamic perturbation theory to study the hydrophobic hydration'' [J. Chem. Phys. 139, 024101 (2013)

NASA Astrophysics Data System (ADS)

Graziano, Giuseppe

2013-09-01

It is shown that the behaviour of the hydration thermodynamic functions obtained in the 3D Mercedes-Benz model of water by Mohoric et al. [J. Chem. Phys. 139, 024101 (2013)] is not qualitatively correct with respect to experimental data for a solute whose diameter is 1.5-fold larger than that of a water molecule. It is also pointed out that the failure is due to the fact that the used 3D Mercedes-Benz model of water [A. Bizjak, T. Urbic, V. Vlachy, and K. A. Dill, J. Chem. Phys. 131, 194504 (2009)] does not reproduce in a quantitatively correct manner the peculiar temperature dependence of water density.

What were the advantages of microendoscopic discectomy for lumbar disc herniation comparing with open discectomy: a meta-analysis?

PubMed Central

Mu, Xiaoping; Wei, Jianxun; Li, Peifeng

2015-01-01

The purpose of this study was to compare the safety and efficacy of micro-endoscopic discectomy (MED) and open discectomy (OD) for lubmar disc herniation (LDH). Randomised controlled trials (RCTs) comparing MED with OD for LDH were searched comprehensively in PubMed, EMBASE, the Cochrane Library. Relevant studies retrieved, data extracted and the quality of included studies were independently performed by two authors. RevMan software (Version 5.2.0) was used to analyse and synthesis relevant data of the included studies. Nine RCTs involving 774 patients were obtained and reported the relevant outcome measures. Compared with OD group, there were significant difference in the general operation indicators including operation time, blood loss, site of incision, hospital stay and time of return to work, biochemical indexes including C-reactive protein (CRP) and interleukin-6 (IL-6) in MED group. Meanwhile, there were no difference in effective rate, complication including total complications, dural leaks occurred and recurrence of the disc herniation, compared MED group with OD group. MED had slighter trauma, milder blood loss and shorter healing time than OD. The results demonstrated MED has great efficacy and safety comparable to OD. So we think that MED can be used routinely for LDH patients, especially the patients of old and intolerable major surgery. Meanwhile, it is necessary for surgeon to master indication and contraindication of MED and improve the operative technique. PMID:26770340

[Limiting a Medline/PubMed query to the "best" articles using the JCR relative impact factor].

PubMed

Avillach, P; Kerdelhué, G; Devos, P; Maisonneuve, H; Darmoni, S J

2014-12-01

Medline/PubMed is the most frequently used medical bibliographic research database. The aim of this study was to propose a new generic method to limit any Medline/PubMed query based on the relative impact factor and the A & B categories of the SIGAPS score. The entire PubMed corpus was used for the feasibility study, then ten frequent diseases in terms of PubMed indexing and the citations of four Nobel prize winners. The relative impact factor (RIF) was calculated by medical specialty defined in Journal Citation Reports. The two queries, which included all the journals in category A (or A OR B), were added to any Medline/PubMed query as a central point of the feasibility study. Limitation using the SIGAPS category A was larger than the when using the Core Clinical Journals (CCJ): 15.65% of PubMed corpus vs 8.64% for CCJ. The response time of this limit applied to the entire PubMed corpus was less than two seconds. For five diseases out of ten, limiting the citations with the RIF was more effective than with the CCJ. For the four Nobel prize winners, limiting the citations with the RIF was more effective than the CCJ. The feasibility study to apply a new filter based on the relative impact factor on any Medline/PubMed query was positive. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Reply to "Comment on `Protecting bipartite entanglement by quantum interferences' "

NASA Astrophysics Data System (ADS)

Das, Sumanta; Agarwal, G. S.

2018-03-01

In a recent Comment Nair and Arun, Phys. Rev. A 97, 036301 (2018), 10.1103/PhysRevA.97.036301, it was concluded that the two-qubit entanglement protection reported in our work [Das and Agarwal, Phys. Rev. A 81, 052341 (2010), 10.1103/PhysRevA.81.052341] is erroneous. While we acknowledge the error in analytical results on concurrence when dipole matrix elements were unequal, the essential conclusions on entanglement protection are not affected.

ERRATUM: Papers published in incorrect sections

NASA Astrophysics Data System (ADS)

2004-04-01

A number of J. Phys. A: Math. Gen. articles have mistakenly been placed in the wrong subject section in recent issues of the journal. We would like to apologize to the authors of these articles for publishing their papers in the Fluid and Plasma Theory section. The correct section for each article is given below. Statistical Physics Issue 4: Microcanonical entropy for small magnetizations Behringer H 2004 J. Phys. A: Math. Gen. 37 1443 Mathematical Physics Issue 9: On the solution of fractional evolution equations Kilbas A A, Pierantozzi T, Trujillo J J and Vázquez L 2004 J. Phys. A: Math. Gen. 37 3271 Quantum Mechanics and Quantum Information Theory Issue 6: New exactly solvable isospectral partners for PT-symmetric potentials Sinha A and Roy P 2004 J. Phys. A: Math. Gen. 37 2509 Issue 9: Symplectically entangled states and their applications to coding Vourdas A 2004 J. Phys. A: Math. Gen. 37 3305 Classical and Quantum Field Theory Issue 6: Pairing of parafermions of order 2: seniority model Nelson C A 2004 J. Phys. A: Math. Gen. 37 2497 Issue 7: Jordan-Schwinger map, 3D harmonic oscillator constants of motion, and classical and quantum parameters characterizing electromagnetic wave polarization Mota R D, Xicoténcatl M A and Granados V D 2004 J. Phys. A: Math. Gen. 37 2835 Issue 9: Could only fermions be elementary? Lev F M 2004 J. Phys. A: Math. Gen. 37 3285

Linear lateral vibration of axisymmetric liquid briges

NASA Astrophysics Data System (ADS)

Ferrera, C.; Montanero, J. M.; Cabezas, M. G.

A liquid bridge is a mass of liquid sustained by the action of the surface tension force between two parallel supporting disks Apart from their basic scientific interest a liquid bridge can be considered as the simplest idealization of the configuration appearing in the floating zone technique used for crystal growth and purification of high melting point materials footnote Messeguer et al emph Crystal Growth Res bf 5 27 1999 This has conferred considerable interest on the study of liquid bridges not only in fluid mechanics but also in the field of material engineering The axisymmetric dynamics of an isothermal liquid bridge has been frequently analysed over the past years The studies have considered different phenomena such as free oscillations footnote Montanero emph E J Mech B Fluids bf 22 169 2003 footnote Acero and Montanero emph Phys Fluids bf 17 078105 2005 forced vibrations footnote Perales and Messeguer emph Phys Fluids A bf 4 1110 1992 g-jitter effects footnote Messeguer and Perales emph Phys Fluids A bf 3 2332 1991 extensional deformation footnote Zhang et al emph J Fluid Mech bf 329 207 1996 and breakup process footnote Espino et al emph Phys Fluids bf 14 3710 2002 among others Works considering the nonaxisymmetric dynamical behaviour of a liquid bridge has been far less common footnote Sanz and Diez emph J Fluid Mech bf 205 503 1989 In the present study the linear vibration of an axisymmetric liquid

The gap equation for spin-polarized fermions

NASA Astrophysics Data System (ADS)

Freiji, Abraham; Hainzl, Christian; Seiringer, Robert

2012-01-01

We study the BCS gap equation for a Fermi gas with unequal population of spin-up and spin-down states. For cosh (δμ/T) ⩽ 2, with T the temperature and δμ the chemical potential difference, the question of existence of non-trivial solutions can be reduced to spectral properties of a linear operator, similar to the unpolarized case studied previously in [Frank, R. L., Hainzl, C., Naboko, S., and Seiringer, R., J., Geom. Anal. 17, 559-567 (2007), 10.1007/BF02937429; Hainzl, C., Hamza, E., Seiringer, R., and Solovej, J. P., Commun., Math. Phys. 281, 349-367 (2008), 10.1007/s00220-008-0489-2; and Hainzl, C. and Seiringer, R., Phys. Rev. B 77, 184517-110 435 (2008)], 10.1103/PhysRevB.77.184517. For cosh (δμ/T) > 2 the phase diagram is more complicated, however. We derive upper and lower bounds for the critical temperature, and study their behavior in the small coupling limit.

Chiral Odd Structure Functions in The Nambu--Jona--Lasinio Soliton Model

NASA Astrophysics Data System (ADS)

Gamberg, Leonard; Reinhardt, Hugo; Weigel, Herbert

1998-10-01

We study unpolarized and polarized nucleon structure functions(H. Weigel, L. Gamberg, and H. Reinhardt, Mod. Phys. Lett. A11) (1996) 3021; Phys. Lett. B399 (1997) 287;Phys. Rev. D55(1997) 6910. within the bosonized Nambu--Jona--Lasinio (NJL) model where the nucleon emerges as a chiral soliton(R. Alkofer, H. Reinhardt and H. Weigel, Phys. Rep. 265) (1996) 139.. These considerations attempt to merge the parton model description of deep inelastic scattering with the phenomenologically successful picture of baryons as chiral solitons. In addition we report on the calculation of the chiral odd quark distributions(L. Gamberg, H. Reinhardt and H. Weigel, "Chiral odd structure functions from a chiral soliton", hep-ph/9801379, Phys. Rev. D. in press.) and the corresponding structure functions h_T(x,Q^2) and h_L(x,Q^2). At the low model scale, Q_0^2, we find that the leading twist effective quark distributions, f_1^(q)(x,Q_0^2), g_1^(q)(x,Q_0^2) and h_T^(q)(x,Q_0^2) satisfy Soffer's inequality for both quark flavors q=u,d. The Q^2 evolution of the twist--2 contributions is performed according to the standard GLAP formalism while the twist--three pieces, \\overlineg_2(x) and \\overlineh_L(x), are evolved according to the large NC scheme.

Full Configuration Interaction Quantum Monte Carlo and Diffusion Monte Carlo: A Comparative Study of the 3D Homogeneous Electron Gas

NASA Astrophysics Data System (ADS)

Shepherd, James J.; López Ríos, Pablo; Needs, Richard J.; Drummond, Neil D.; Mohr, Jennifer A.-F.; Booth, George H.; Grüneis, Andreas; Kresse, Georg; Alavi, Ali

2013-03-01

Full configuration interaction quantum Monte Carlo1 (FCIQMC) and its initiator adaptation2 allow for exact solutions to the Schrödinger equation to be obtained within a finite-basis wavefunction ansatz. In this talk, we explore an application of FCIQMC to the homogeneous electron gas (HEG). In particular we use these exact finite-basis energies to compare with approximate quantum chemical calculations from the VASP code3. After removing the basis set incompleteness error by extrapolation4,5, we compare our energies with state-of-the-art diffusion Monte Carlo calculations from the CASINO package6. Using a combined approach of the two quantum Monte Carlo methods, we present the highest-accuracy thermodynamic (infinite-particle) limit energies for the HEG achieved to date. 1 G. H. Booth, A. Thom, and A. Alavi, J. Chem. Phys. 131, 054106 (2009). 2 D. Cleland, G. H. Booth, and A. Alavi, J. Chem. Phys. 132, 041103 (2010). 3 www.vasp.at (2012). 4 J. J. Shepherd, A. Grüneis, G. H. Booth, G. Kresse, and A. Alavi, Phys. Rev. B. 86, 035111 (2012). 5 J. J. Shepherd, G. H. Booth, and A. Alavi, J. Chem. Phys. 136, 244101 (2012). 6 R. Needs, M. Towler, N. Drummond, and P. L. Ríos, J. Phys.: Condensed Matter 22, 023201 (2010).

Response to ``Comment on `Slow Debye-type peak observed in the dielectric response of polyalcohols' '' [J. Chem. Phys. 134, 037101 (2011)

NASA Astrophysics Data System (ADS)

Bergman, R.; Jansson, H.; Swenson, J.

2011-01-01

In our recent article [R. Bergman et al., J. Chem. Phys. 132, 044504 (2010)] we investigated some polyalcohols, i.e., glycerol, xylitol, and sorbitol by dielectric spectroscopy. In the study, a low-frequency peak of Debye character that normally is hidden by the large low-frequency dispersion due to conductivity was revealed by analyzing the real part of the permittivity and by using a thin Teflon film to suppress the low-frequency dispersion. We agree with the comment by Paluch et al. [J. Chem. Phys. 134, 037101 (2011)] that the Teflon film setup will indeed create a peak due to the dc conductivity. However, due to the fact that the location of the peak was almost identical in measurement with and without Teflon, we unfortunately mainly showed the data measured with Teflon, despite that it could also be observed in the real part of the permittivity without using the Teflon setup, as shown in our original article [R. Bergman et al., J. Chem. Phys. 132, 044504 (2010)]. Here, we show that the low-frequency peak of Debye character can also be observed by subtracting the dc conductivity. Furthermore, we show that the modulus representation used in Paluch et al. [J. Chem. Phys. 134, 037101 (2011).] is also not suitable for detecting processes hidden by the conductivity.

Persistence Probabilities of Two-Sided (Integrated) Sums of Correlated Stationary Gaussian Sequences

NASA Astrophysics Data System (ADS)

Aurzada, Frank; Buck, Micha

2018-02-01

We study the persistence probability for some two-sided, discrete-time Gaussian sequences that are discrete-time analogues of fractional Brownian motion and integrated fractional Brownian motion, respectively. Our results extend the corresponding ones in continuous time in Molchan (Commun Math Phys 205(1):97-111, 1999) and Molchan (J Stat Phys 167(6):1546-1554, 2017) to a wide class of discrete-time processes.

A comparison of three radiation models for the calculation of nozzle arcs

NASA Astrophysics Data System (ADS)

Dixon, C. M.; Yan, J. D.; Fang, M. T. C.

2004-12-01

Three radiation models, the semi-empirical model based on net emission coefficients (Zhang et al 1987 J. Phys. D: Appl. Phys. 20 386-79), the five-band P1 model (Eby et al 1998 J. Phys. D: Appl. Phys. 31 1578-88), and the method of partial characteristics (Aubrecht and Lowke 1994 J. Phys. D: Appl.Phys. 27 2066-73, Sevast'yanenko 1979 J. Eng. Phys. 36 138-48), are used to calculate the radiation transfer in an SF6 nozzle arc. The temperature distributions computed by the three models are compared with the measurements of Leseberg and Pietsch (1981 Proc. 4th Int. Symp. on Switching Arc Phenomena (Lodz, Poland) pp 236-40) and Leseberg (1982 PhD Thesis RWTH Aachen, Germany). It has been found that all three models give similar distributions of radiation loss per unit time and volume. For arcs burning in axially dominated flow, such as arcs in nozzle flow, the semi-empirical model and the P1 model give accurate predictions when compared with experimental results. The prediction by the method of partial characteristics is poorest. The computational cost is the lowest for the semi-empirical model.

Reynolds number effects on the single-mode Richtmyer-Meshkov instability.

PubMed

Walchli, B; Thornber, B

2017-01-01

The Reynolds number effects on the nonlinear growth rates of the Richtmyer-Meshkov instability are investigated using two-dimensional numerical simulations. A decrease in Reynolds number gives an increased time to reach nonlinear saturation, with Reynolds number effects only significant in the range Re<256. Within this range there is a sharp change in instability properties. The bubble and spike amplitudes move towards equal size at lower Reynolds numbers and the bubble velocities decay faster than predicted by Sohn's model [S.-I. Sohn, Phys. Rev. E 80, 055302 (2009)PLEEE81539-375510.1103/PhysRevE.80.055302]. Predicted amplitudes show reasonable agreement with the existing theory of Carles and Popinet [P. Carles and S. Popinet, Phys. Fluids Lett. 13, 1833 (2001)10.1063/1.1377863; Eur. J. Mech. B 21, 511 (2002)EJBFEV0997-754610.1016/S0997-7546(02)01199-8] and Mikaelian [K. O. Mikaelian, Phys. Rev. E 47, 375 (1993)1063-651X10.1103/PhysRevE.47.375; K. O. Mikaelian, Phys. Rev. E 87, 031003 (2013)PLEEE81539-375510.1103/PhysRevE.87.031003], with the former being the closest match to the current computations.

Fully relativistic B-spline R-matrix calculations for electron collisions with xenon

NASA Astrophysics Data System (ADS)

Bartschat, Klaus; Zatsarinny, Oleg

2009-05-01

We have applied our recently developed fully relativistic Dirac B-spline R-matrix (DBSR) code [1] to calculate electron scattering from xenon atoms. Results from a 31-state close-coupling model for the excitation function of the metastable (5p^5 6s) J=0,2 states show excellent agreement with experiment [2], thereby presenting a significant improvement over the most sophisticated previous Breit-Pauli calculations [3,4]. This allows for a detailed and reliable analysis of the resonance structure. The same model is currently being used to calculate electron-impact excitation from the metastable J=2 state. The results will be compared with recent experimental data [5] and predictions from other theoretical models [6,7]. [1] O. Zatsarinny and K. Bartschat, Phys. Rev. A 77 (2008) 062701. [2] S. J. Buckman et al., J. Phys. B 16 (1983) 4219. [3] A. N. Grum-Grzhimailo and K. Bartschat, J. Phys. B 35 (2002) 3479. [4] M. Allan et al., Phys. Rev. A 74 (2006) 030701(R). [5] R. O. Jung et al., Phys. Rev. A 72 (2005) 022723. [6] R. Srivastava et al., Phys. Rev. A 74 (2006) 012715. [7] J. Jiang et al., J. Phys. B 41 (2008) 245204.

Analysis of PubMed User Sessions Using a Full-Day PubMed Query Log: A Comparison of Experienced and Nonexperienced PubMed Users

PubMed Central

2015-01-01

Background PubMed is the largest biomedical bibliographic information source on the Internet. PubMed has been considered one of the most important and reliable sources of up-to-date health care evidence. Previous studies examined the effects of domain expertise/knowledge on search performance using PubMed. However, very little is known about PubMed users’ knowledge of information retrieval (IR) functions and their usage in query formulation. Objective The purpose of this study was to shed light on how experienced/nonexperienced PubMed users perform their search queries by analyzing a full-day query log. Our hypotheses were that (1) experienced PubMed users who use system functions quickly retrieve relevant documents and (2) nonexperienced PubMed users who do not use them have longer search sessions than experienced users. Methods To test these hypotheses, we analyzed PubMed query log data containing nearly 3 million queries. User sessions were divided into two categories: experienced and nonexperienced. We compared experienced and nonexperienced users per number of sessions, and experienced and nonexperienced user sessions per session length, with a focus on how fast they completed their sessions. Results To test our hypotheses, we measured how successful information retrieval was (at retrieving relevant documents), represented as the decrease rates of experienced and nonexperienced users from a session length of 1 to 2, 3, 4, and 5. The decrease rate (from a session length of 1 to 2) of the experienced users was significantly larger than that of the nonexperienced groups. Conclusions Experienced PubMed users retrieve relevant documents more quickly than nonexperienced PubMed users in terms of session length. PMID:26139516

Systematic study of α decay of nuclei around the Z =82 , N =126 shell closures within the cluster-formation model and proximity potential 1977 formalism

NASA Astrophysics Data System (ADS)

Deng, Jun-Gang; Zhao, Jie-Cheng; Chu, Peng-Cheng; Li, Xiao-Hua

2018-04-01

In the present work, we systematically study the α decay preformation factors Pα within the cluster-formation model and α decay half-lives by the proximity potential 1977 formalism for nuclei around Z =82 ,N =126 closed shells. The calculations show that the realistic Pα is linearly dependent on the product of valance protons (holes) and valance neutrons (holes) NpNn . It is consistent with our previous works [Sun et al., Phys. Rev. C 94, 024338 (2016), 10.1103/PhysRevC.94.024338; Deng et al., Phys. Rev. C 96, 024318 (2017), 10.1103/PhysRevC.96.024318], in which Pα are model dependent and extracted from the ratios of calculated α half-lives to experimental data. Combining with our previous works, we confirm that the valance proton-neutron interaction plays a key role in the α preformation for nuclei around Z =82 ,N =126 shell closures whether the Pα is model dependent or microcosmic. In addition, our calculated α decay half-lives by using the proximity potential 1977 formalism taking Pα evaluated by the cluster-formation model can well reproduce the experimental data and significantly reduce the errors.

Stochastic and equilibrium pictures of the ultracold Fano-Feshbach-resonance molecular conversion rate

NASA Astrophysics Data System (ADS)

Yamakoshi, Tomotake; Watanabe, Shinichi; Zhang, Chen; Greene, Chris H.

2013-05-01

The ultracold molecular conversion rate occurring in an adiabatic ramp through a Fano-Feshbach resonance is studied and compared in two statistical models. One model, the so-called stochastic phase-space sampling (SPSS) [Hodby , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.94.120402 94, 120402 (2005)] evaluates the overlap of two atomic distributions in phase space by sampling atomic pairs according to a phase-space criterion. The other model, the chemical equilibrium theory (ChET) [Watabe and Nikuni, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.77.013616 77, 013616 (2008)] considers atomic and molecular distributions in the limit of the chemical and thermal equilibrium. The present study applies SPSS and ChET to a prototypical system of K+K→ K2 in all the symmetry combinations, namely Fermi-Fermi, Bose-Bose, and Bose-Fermi cases. To examine implications of the phase-space criterion for SPSS, the behavior of molecular conversion is analyzed using four distinct geometrical constraints. Our comparison of the results of SPSS with those of ChET shows that while they appear similar in most situations, the two models give rise to rather dissimilar behaviors when the presence of a Bose-Einstein condensate strongly affects the molecule formation.

Exploratory study of fission product yields of neutron-induced fission of 235U , 238U , and 239Pu at 8.9 MeV

NASA Astrophysics Data System (ADS)

Bhatia, C.; Fallin, B. F.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.; Arnold, C. W.; Bond, E.; Bredeweg, T. A.; Fowler, M. M.; Moody, W.; Rundberg, R. S.; Rusev, G. Y.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Macri, R.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.

2015-06-01

Using dual-fission chambers each loaded with a thick (200 -400 -mg /c m2) actinide target of 235 ,238U or 239Pu and two thin (˜10 -100 -μ g /c m2) reference foils of the same actinide, the cumulative yields of fission products ranging from 92Sr to 147Nd have been measured at En= 8.9 MeV . The 2H(d ,n ) 3He reaction provided the quasimonoenergetic neutron beam. The experimental setup and methods used to determine the fission product yield (FPY) are described, and results for typically eight high-yield fission products are presented. Our FPYs for 235U(n ,f ) , 238U(n ,f ) , and 239Pu(n ,f ) at 8.9 MeV are compared with the existing data below 8 MeV from Glendenin et al. [Phys. Rev. C 24, 2600 (1981), 10.1103/PhysRevC.24.2600], Nagy et al. [Phys. Rev. C 17, 163 (1978), 10.1103/PhysRevC.17.163], Gindler et al. [Phys. Rev. C 27, 2058 (1983), 10.1103/PhysRevC.27.2058], and those of Mac Innes et al. [Nucl. Data Sheets 112, 3135 (2011), 10.1016/j.nds.2011.11.009] and Laurec et al. [Nucl. Data Sheets 111, 2965 (2010), 10.1016/j.nds.2010.11.004] at 14.5 and 14.7 MeV, respectively. This comparison indicates a negative slope for the energy dependence of most fission product yields obtained from 235U and 239Pu , whereas for 238U the slope issue remains unsettled.

Vortex formation in a complex plasma

NASA Astrophysics Data System (ADS)

Ishihara, Osamu

Complex plasma experiments in ground-based laboratories as well as in microgravity conditions have shown the formation of vortex structures in various conditions (e.g., 1,2,3,4). The vortex structures formed in a complex plasma are visible by naked eyes with the help of irradiating laser and the individual dust particles in the structure give us the opportunity to study detailed physics of the commonly observed natural phenomena known such as tornadoes, typhoons, hurricanes and dust devils. Based on the Navier-Stokes equation with proper complex plasma conditions we analyze as much as possible in a universal way the vortex structure and clarifies the role of the controlling parameters like flow velocity and external magnetic field. 1. G. E. Morfill,H. M. Thomas, U. Konopka,H. Rothermel, M. Zuzic, A. Ivlev, and J. Goree, Phys,. Rev. Lett. 83, 1598 (1999). 2. E. Nebbat and R. Annou, Phys. Plasmas 17, 093702 (2010). 3. Y. Saitou and O. Ishihara, Phys. Rev. Lett. 111, 185003 (2013). 4. V. N. Tsytovich and N. G. Gusein-zade, Plasma Phys. Rep. 39, 515 (2013).

Device-independent secret-key-rate analysis for quantum repeaters

NASA Astrophysics Data System (ADS)

Holz, Timo; Kampermann, Hermann; Bruß, Dagmar

2018-01-01

The device-independent approach to quantum key distribution (QKD) aims to establish a secret key between two or more parties with untrusted devices, potentially under full control of a quantum adversary. The performance of a QKD protocol can be quantified by the secret key rate, which can be lower bounded via the violation of an appropriate Bell inequality in a setup with untrusted devices. We study secret key rates in the device-independent scenario for different quantum repeater setups and compare them to their device-dependent analogon. The quantum repeater setups under consideration are the original protocol by Briegel et al. [Phys. Rev. Lett. 81, 5932 (1998), 10.1103/PhysRevLett.81.5932] and the hybrid quantum repeater protocol by van Loock et al. [Phys. Rev. Lett. 96, 240501 (2006), 10.1103/PhysRevLett.96.240501]. For a given repeater scheme and a given QKD protocol, the secret key rate depends on a variety of parameters, such as the gate quality or the detector efficiency. We systematically analyze the impact of these parameters and suggest optimized strategies.

Multiplicity-dependent and nonbinomial efficiency corrections for particle number cumulants

NASA Astrophysics Data System (ADS)

Bzdak, Adam; Holzmann, Romain; Koch, Volker

2016-12-01

In this article we extend previous work on efficiency corrections for cumulant measurements [Bzdak and Koch, Phys. Rev. C 86, 044904 (2012), 10.1103/PhysRevC.86.044904; Phys. Rev. C 91, 027901 (2015), 10.1103/PhysRevC.91.027901]. We will discuss the limitations of the methods presented in these papers. Specifically we will consider multiplicity dependent efficiencies as well as nonbinomial efficiency distributions. We will discuss the most simple and straightforward methods to implement those corrections.

ERRATUM: High-resolution electron spectroscopy of the 1s23lnl' Be-like series in oxygen and neon. Test of theoretical data: I. Experimental method and theoretical background

NASA Astrophysics Data System (ADS)

Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Bordenave-Montesquieu, D.

2003-02-01

The J. Phys. B publishing team would like to apologize to the authors of the above paper. In this paper, references [42] and [43] were printed incorrectly. The correct references are: [42] Bordenave-Montesquieu A, Gleizes A and Benoit-Cattin P 1982 Phys. Rev. A 25 245-67 [43] Bordenave-Montesquieu A et al 1987 J. Phys. B: At. Mol. Phys. 20 L695-703.

Calculation of the Gibbs Free Energy of Solvation and Dissociation of HCl in Water via Monte Carlo Simulations and Continuum Solvation Models

DTIC Science & Technology

2013-01-01

Narten, J. Chem. Phys., 1975, 63, 3624–3631. 10 A. Botti, F. Bruni, S. Imberti, M. A. Ricci and A. K. Soper , J. Chem. Phys., 2004, 121, 7840–7848. 11 D...10478. 48 I. Harsányi and L. Pusztai, J. Phys.: Condens. Matter, 2005, 17, S59–S65. 49 A. Botti, F. Bruni, M. A. Ricci and A. K. Soper , J. Chem. Phys

Multiplicity-dependent and nonbinomial efficiency corrections for particle number cumulants

DOE PAGES

Bzdak, Adam; Holzmann, Romain; Koch, Volker

2016-12-19

Here, we extend previous work on efficiency corrections for cumulant measurements [Bzdak and Koch, Phys. Rev. C 86, 044904 (2012)PRVCAN0556-281310.1103/PhysRevC.86.044904; Phys. Rev. C 91, 027901 (2015)PRVCAN0556-281310.1103/PhysRevC.91.027901]. We will then discuss the limitations of the methods presented in these papers. Specifically we will consider multiplicity dependent efficiencies as well as nonbinomial efficiency distributions. We will discuss the most simple and straightforward methods to implement those corrections.

On the Runge-Lenz-Pauli vector operator as an aid to the calculation of atomic processes in laboratory and astrophysical plasmas

NASA Astrophysics Data System (ADS)

Hey, J. D.

2015-09-01

On the basis of the original definition and analysis of the vector operator by Pauli (1926 Z. Phys. 36 336-63), and further developments by Flamand (1966 J. Math. Phys. 7 1924-31), and by Becker and Bleuler (1976 Z. Naturforsch. 31a 517-23), we consider the action of the operator on both spherical polar and parabolic basis state wave functions, both with and without direct use of Pauli’s identity (Valent 2003 Am. J. Phys. 71 171-75). Comparison of the results, with the aid of two earlier papers (Hey 2006 J. Phys. B: At. Mol. Opt. Phys. 39 2641-64, Hey 2007 J. Phys. B: At. Mol. Opt. Phys. 40 4077-96), yields a convenient ladder technique in the form of a recurrence relation for calculating the transformation coefficients between the two sets of basis states, without explicit use of generalized hypergeometric functions. This result is therefore very useful for application to Stark effect and impact broadening calculations applied to high-n radio recombination lines from tenuous space plasmas. We also demonstrate the versatility of the Runge-Lenz-Pauli vector operator as a means of obtaining recurrence relations between expectation values of successive powers of quantum mechanical operators, by using it to provide, as an example, a derivation of the Kramers-Pasternack relation. It is suggested that this operator, whose potential use in Stark- and Zeeman-effect calculations for magnetically confined fusion edge plasmas (Rosato, Marandet and Stamm 2014 J. Phys. B: At. Mol. Opt. Phys. 47 105702) and tenuous space plasmas ( H II regions) has not been fully explored and exploited, may yet be found to yield a number of valuable results for applications to plasma diagnostic techniques based upon rate calculations of atomic processes.

Response to "Comment on `Solitonic and chaotic behaviors for the nonlinear dust-acoustic waves in a magnetized dusty plasma'" [Phys. Plasmas 24, 094701 (2017)

NASA Astrophysics Data System (ADS)

Zhen, Hui-Ling; Tian, Bo; Xie, Xi-Yang; Wu, Xiao-Yu; Wen, Xiao-Yong

2018-02-01

On our previous construction [H. L. Zhen et al., Phys. Plasmas 23, 052301 (2016)] of the soliton solutions of a model describing the dynamics of the dust particles in a weakly ionized, collisional dusty plasma comprised of the negatively charged cold dust particles, hot ions, hot electrons, and stationary neutrals in the presence of an external static magnetic field, Ali et al. [Phys. Plasmas 24, 094701 (2017)] have commented that there exists a different form of Eq. (4) from that shown in Zhen et al. [Phys. Plasmas 23, 052301 (2016)] and that certain interesting phenomena with the dust neutral collision frequency ν0>0 are ignored in Zhen et al. [Phys. Plasmas 23, 052301 (2016)]. In this Reply, according to the transformation given by the Ali et al. [Phys. Plasmas 24, 094701 (2017)] comment, we present some one-, two-, and N-soliton solutions which have not been obtained in the Ali et al. [Phys. Plasmas 24, 094701 (2017)] comment. We point out that our previous solutions in Zhen et al. [Phys. Plasmas 23, 052301 (2016)] are still valid because of the similarity between the two dispersion relations of previous solutions in Zhen et al. [Phys. Plasmas 23, 052301 (2016)] and the solutions presented in this Reply. Based on our soliton solutions in this Reply, it is found that the soliton amplitude is inversely related to Zd and B0, but positively related to md and α, where α refers to the coefficient of the nonlinear term, Zd and md are the charge number and mass of a dust particle, respectively, B0 represents the strength of the external static magnetic field. We also find that the two solitons are always in parallel during the propagation.

Differences in dietary intakes, food sources and determinants of total flavonoids between Mediterranean and non-Mediterranean countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

PubMed

Zamora-Ros, Raul; Knaze, Viktoria; Luján-Barroso, Leila; Romieu, Isabelle; Scalbert, Augustin; Slimani, Nadia; Hjartåker, Anette; Engeset, Dagrun; Skeie, Guri; Overvad, Kim; Bredsdorff, Lea; Tjønneland, Anne; Halkjær, Jytte; Key, Timothy J; Khaw, Kay-Tee; Mulligan, Angela A; Winkvist, Anna; Johansson, Ingegerd; Bueno-de-Mesquita, H Bas; Peeters, Petra H M; Wallström, Peter; Ericson, Ulrika; Pala, Valeria; de Magistris, Maria Santucci; Polidoro, Silvia; Tumino, Rosario; Trichopoulou, Antonia; Dilis, Vardis; Katsoulis, Michael; Huerta, José María; Martínez, Virginia; Sánchez, María-José; Ardanaz, Eva; Amiano, Pilar; Teucher, Birgit; Grote, Verena; Bendinelli, Benedetta; Boeing, Heiner; Förster, Jana; Touillaud, Marina; Perquier, Florence; Fagherazzi, Guy; Gallo, Valentina; Riboli, Elio; González, Carlos A

2013-04-28

A greater adherence to the traditional Mediterranean (MED) diet is associated with a reduced risk of developing chronic diseases. This dietary pattern is based on higher consumption of plant products that are rich in flavonoids. We compared the total flavonoid dietary intakes, their food sources and various lifestyle factors between MED and non-MED countries participating in the EPIC study. Flavonoid intakes and their food sources for 35,628 subjects, aged 35-74 years and recruited between 1992 and 2000, in twenty-six study centres were estimated using standardised 24 h dietary recall software (EPIC-Soft®). An ad hoc food composition database on flavonoids was compiled using analytical data from the United States Department of Agriculture and Phenol-Explorer databases. Moreover, it was expanded to include using recipes, estimations of missing values and flavonoid retention factors. No significant differences in total flavonoid mean intake between non-MED countries (373·7 mg/d) and MED countries (370·2 mg/d) were observed. In the non-MED region, the main contributors were proanthocyanidins (48·2%) and flavan-3-ol monomers (24·9%) and the principal food sources were tea (25·7%) and fruits (32·8%). In the MED region, proanthocyanidins (59·0%) were by far the most abundant contributor and fruits (55·1%), wines (16·7%) and tea (6·8%) were the main food sources. The present study shows similar results for total dietary flavonoid intakes, but significant differences in flavonoid class intakes, food sources and some characteristics between MED and non-MED countries. These differences should be considered in studies about the relationships between flavonoid intake and chronic diseases.

Poster - 19: Investigation of Electron Reference Dosimetry Based on Optimal Chamber Shift

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

Zhan, Lixin; Jiang, Runqing; Liu, Baochang

An addendum/revision to AAPM TG-51 electron reference dosimetry is highly expected to meet the clinical requirement with the increasing usage of new ion chambers not covered in TG-51. A recent study, Med. Phys. 41, 111701, proposed a new fitting equation for the beam quality conversion factor k’{sub Q} to a wide spectrum of chambers. In the study, an optimal Effective Point of Measurement (EPOM) from Monte Carlo calculations was recommended and the fitting parameters to k’{sub Q} was based on it. We investigated the absolute dose obtained based on the optimal EPOM method and the original TG-51 method with k’{submore » R50} determined differently. The results showed that using the Markus curve is a better choice than the well-guarded chamber fitting for an IBA PPC-05 parallel plate chamber if we need to strictly follow the AAPM TG-51 protocol. We also examined the usage of the new fitting equation with measurement performed at the physical EPOM, instead of the optimal EPOM. The former is more readily determined and more practical in clinics. Our study indicated that the k’{sub Q} fitting based on the optimal EPOM can be used to measurement at the physical EPOM with no significant clinical impact. The inclusion of Farmer chamber gradient correction P{sub gr} in k’{sub Q}, as in the mentioned study, asks for the precise positioning of chamber center at dref. It is not recommended in clinics to avoid over-correction for low electron energies, especially for an institute having matching Linacs implemented.« less

Protective Effects of the Mediterranean Diet on Type 2 Diabetes and Metabolic Syndrome123

PubMed Central

Lee, Chih-Hao; Estruch, Ramón

2016-01-01

Several studies provide evidence supporting a beneficial effect from the traditional Mediterranean diet (MedDiet) on the risk of type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS). This review summarizes the current scientific evidence from epidemiologic studies and clinical trials on the relation between the MedDiet and T2DM and MetS and the possible mechanisms underlying the reported associations. A recent meta-analysis of prospective cohort studies showed that greater adherence to the MedDiet was associated with a significant reduction in the risk of diabetes. The MedDiet has also been found to be beneficial in the prevention of gestational diabetes. Four large prospective studies have observed inverse associations between the MedDiet and MetS or its components. Few randomized controlled trials (RCTs) have evaluated the effect of the MedDiet on T2DM and MetS. Results from the landmark PREvención con DIeta MEDiterránea (PREDIMED) nutrition intervention trial showed that participants assigned to the MedDiet had a significant 30% reduction in the risk of T2DM and that it also promoted the reversion of MetS and its components, hyperglycemia and central obesity. In addition, 5 RCTs showed the beneficial effects of the MedDiet compared with other dietary patterns on glycemic control in patients with T2DM. A recent meta-analysis of RCTs revealed that, compared with a variety of control diets, the MedDiet was associated with beneficial effects on all MetS components. Bioactive components of the MedDiet synergize to affect various metabolic pathways, leading to a reduced cardiometabolic disease risk. The abundance of healthy, nutrient-dense foods that make up the plant-based MedDiet predicts its bioactivity and potential to beneficially influence metabolic pathways that lead to MetS and T2DM, as well as other chronic conditions. Abundant epidemiologic and clinical trial evidence supports the role of the MedDiet on the prevention and management of T2DM and MetS. PMID:26962178

Protective Effects of the Mediterranean Diet on Type 2 Diabetes and Metabolic Syndrome.

PubMed

Salas-Salvadó, Jordi; Guasch-Ferré, Marta; Lee, Chih-Hao; Estruch, Ramón; Clish, Clary B; Ros, Emilio

2016-03-09

Several studies provide evidence supporting a beneficial effect from the traditional Mediterranean diet (MedDiet) on the risk of type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS). This review summarizes the current scientific evidence from epidemiologic studies and clinical trials on the relation between the MedDiet and T2DM and MetS and the possible mechanisms underlying the reported associations. A recent meta-analysis of prospective cohort studies showed that greater adherence to the MedDiet was associated with a significant reduction in the risk of diabetes. The MedDiet has also been found to be beneficial in the prevention of gestational diabetes. Four large prospective studies have observed inverse associations between the MedDiet and MetS or its components. Few randomized controlled trials (RCTs) have evaluated the effect of the MedDiet on T2DM and MetS. Results from the landmark PREvención con DIeta MEDiterránea (PREDIMED) nutrition intervention trial showed that participants assigned to the MedDiet had a significant 30% reduction in the risk of T2DM and that it also promoted the reversion of MetS and its components, hyperglycemia and central obesity. In addition, 5 RCTs showed the beneficial effects of the MedDiet compared with other dietary patterns on glycemic control in patients with T2DM. A recent meta-analysis of RCTs revealed that, compared with a variety of control diets, the MedDiet was associated with beneficial effects on all MetS components. Bioactive components of the MedDiet synergize to affect various metabolic pathways, leading to a reduced cardiometabolic disease risk. The abundance of healthy, nutrient-dense foods that make up the plant-based MedDiet predicts its bioactivity and potential to beneficially influence metabolic pathways that lead to MetS and T2DM, as well as other chronic conditions. Abundant epidemiologic and clinical trial evidence supports the role of the MedDiet on the prevention and management of T2DM and MetS. © 2016 American Society for Nutrition.

Photodissociation of OCS: deviations between theory and experiment, and the importance of higher order correlation effects.

PubMed

Schmidt, J A; Olsen, J M H

2014-11-14

The photodissociation of carbonyl sulfide (OCS) was investigated theoretically in a series of studies by Schmidt and co-workers. Initial studies [J. A. Schmidt, M. S. Johnson, G. C. McBane, and R. Schinke, J. Chem. Phys. 136, 131101 (2012); J. A. Schmidt, M. S. Johnson, G. C. McBane, and R. Schinke, J. Chem. Phys. 137, 054313 (2012)] found photodissociation in the first UV-band to occur mainly by excitation of the 2(1)A' (A) excited state. However, in a later study [G. C. McBane, J. A. Schmidt, M. S. Johnson, and R. Schinke, J. Chem. Phys. 138, 094314 (2013)] it was found that a significant fraction of photodissociation must occur by excitation of 1(1)A″ (B) excited state to explain the product angular distribution. The branching between excitation of the A and B excited states is determined by the magnitude of the transition dipole moment vectors in the Franck-Condon region. This study examines the sensitivity of these quantities to changes in the employed electronic structure methodology. This study benchmarks the methodology employed in previous studies against highly correlated electronic structure methods (CC3 and MRAQCC) and provide evidence in support of the picture of the OCS photodissociation process presented in [G. C. McBane, J. A. Schmidt, M. S. Johnson, and R. Schinke, J. Chem. Phys. 138, 094314 (2013)] showing that excitation of A and B electronic states both contribute significantly to the first UV absorption band of OCS. In addition, this study presents evidence in support of the assertion that the A state potential energy surface employed in previous studies underestimates the energy at highly bent geometries (γ ∼ 70°) leading to overestimated rotational energy in the product CO.

Mediator Med23 deficiency enhances neural differentiation of murine embryonic stem cells through modulating BMP signaling.

PubMed

Zhu, Wanqu; Yao, Xiao; Liang, Yan; Liang, Dan; Song, Lu; Jing, Naihe; Li, Jinsong; Wang, Gang

2015-02-01

Unraveling the mechanisms underlying early neural differentiation of embryonic stem cells (ESCs) is crucial to developing cell-based therapies of neurodegenerative diseases. Neural fate acquisition is proposed to be controlled by a 'default' mechanism, for which the molecular regulation is not well understood. In this study, we investigated the functional roles of Mediator Med23 in pluripotency and lineage commitment of murine ESCs. Unexpectedly, we found that, despite the largely unchanged pluripotency and self-renewal of ESCs, Med23 depletion rendered the cells prone to neural differentiation in different differentiation assays. Knockdown of two other Mediator subunits, Med1 and Med15, did not alter the neural differentiation of ESCs. Med15 knockdown selectively inhibited endoderm differentiation, suggesting the specificity of cell fate control by distinctive Mediator subunits. Gene profiling revealed that Med23 depletion attenuated BMP signaling in ESCs. Mechanistically, MED23 modulated Bmp4 expression by controlling the activity of ETS1, which is involved in Bmp4 promoter-enhancer communication. Interestingly, med23 knockdown in zebrafish embryos also enhanced neural development at early embryogenesis, which could be reversed by co-injection of bmp4 mRNA. Taken together, our study reveals an intrinsic, restrictive role of MED23 in early neural development, thus providing new molecular insights for neural fate determination. © 2015. Published by The Company of Biologists Ltd.

The energy dependence of the lateral dose response functions of detectors with various densities in photon-beam dosimetry.

PubMed

Looe, Hui Khee; Harder, Dietrich; Poppe, Björn

2017-02-07

The lateral dose response function is a general characteristic of the volume effect of a detector used for photon dosimetry in a water phantom. It serves as the convolution kernel transforming the true absorbed dose to water profile, which would be produced within the undisturbed water phantom, into the detector-measured signal profile. The shape of the lateral dose response function characterizes (i) the volume averaging attributable to the detector's size and (ii) the disturbance of the secondary electron field associated with the deviation of the electron density of the detector material from the surrounding water. In previous work, the characteristic dependence of the shape of the lateral dose response function upon the electron density of the detector material was studied for 6 MV photons by Monte Carlo simulation of a wall-less voxel-sized detector (Looe et al 2015 Phys. Med. Biol. 60 6585-07). This study is here continued for 60 Co gamma rays and 15 MV photons in comparison with 6 MV photons. It is found (1) that throughout these photon spectra the shapes of the lateral dose response functions are retaining their characteristic dependence on the detector's electron density, and (2) that their energy-dependent changes are only moderate. This appears as a practical advantage because the lateral dose response function can then be treated as practically invariant across a clinical photon beam in spite of the known changes of the photon spectrum with increasing distance from the beam axis.

Effects of multiple scattering in cold nuclear matter on J / ψ suppression and in heavy ion collisions

NASA Astrophysics Data System (ADS)

Glenn, A. M.; Nagle, J. L.; Molnar, Denes

2007-01-01

Coherent multiple scatterings of ccbar quark pairs in the environment of heavy ion collisions have been used in a previous work by Qiu et al. [J. Qiu, J.P. Vary, X. Zhang, Phys. Rev. Lett. 88 (2002) 232301; J. Qiu, J.P. Vary, X. Zhang, Nucl. Phys. A 698 (2002) 571, nucl-th/0106040] to study J / ψ suppression. That model suggests that heavy quark re-scatterings in a cold nuclear medium can completely explain the centrality dependence of the observed J / ψ suppression in Pb + Pb collisions at the SPS [M.C. Abreu, et al., NA50 Collaboration, Phys. Lett. B 521 (2001) 195]. Their calculations also revealed significant differences under the assumptions of a color singlet or color octet production mechanism. A more recent analytic calculation [H. Fujii, Phys. Rev. C 67 (2003) 031901], which includes incoherent final-state re-scatterings with explicit momentum transfer fluctuations in three dimensions, indicates much less suppression and little sensitivity to the production mechanism. In this Letter, we study simultaneously both the J / ψ suppression and pT modifications, at SPS and RHIC energies. We mainly focus on incoherent momentum transfer fluctuations in two dimensions, which is more appropriate for the heavy-ion collision kinematics. Our analytic and Monte Carlo calculations reinforce the analytic results in [H. Fujii, Phys. Rev. C 67 (2003) 031901]. Additionally, we find that the experimental J / ψ suppression and from nucleus-nucleus collisions at the SPS or RHIC cannot simultaneously be described in this incoherent multiple scattering framework for any value of the fluctuation strength parameter .

Bulk modulus of two-dimensional liquid dusty plasmas and its application

NASA Astrophysics Data System (ADS)

Li, Wei; Lin, Wei; Feng, Yan

2017-04-01

From the recently obtained equation of state [Feng et al., J. Phys. D: Appl. Phys. 49, 235203 (2016) and Feng et al., Phys. Plasmas 23, 093705 (2016); Erratum 23, 119904 (2016)], the bulk modulus of elasticity K of 2D liquid dusty plasmas is analytically derived as the expression of the temperature and the screening parameter. Exact values of the obtained bulk modulus of elasticity K are reported and also plotted in the 2D plane of the temperature and the screening parameter. As the temperature and the screening parameter change, the variation trend of K is reported and the corresponding interpretation is suggested. It has been demonstrated that the obtained bulk modulus of elasticity K can be used to predict the longitudinal sound speed, which agrees well with previous studies.

Normal Modes of Magnetized Finite Two-Dimensional Yukawa Crystals

NASA Astrophysics Data System (ADS)

Marleau, Gabriel-Dominique; Kaehlert, Hanno; Bonitz, Michael

2009-11-01

The normal modes of a finite two-dimensional dusty plasma in an isotropic parabolic confinement, including the simultaneous effects of friction and an external magnetic field, are studied. The ground states are found from molecular dynamics simulations with simulated annealing, and the influence of screening, friction, and magnetic field on the mode frequencies is investigated in detail. The two-particle problem is solved analytically and the limiting cases of weak and strong magnetic fields are discussed.[4pt] [1] C. Henning, H. K"ahlert, P. Ludwig, A. Melzer, and M.Bonitz. J. Phys. A 42, 214023 (2009)[2] B. Farokhi, M. Shahmansouri, and P. K. Shukla. Phys.Plasmas 16, 063703 (2009)[3] L. Cândido, J.-P. Rino, N. Studart, and F. M. Peeters. J. Phys.: Condens. Matter 10, 11627--11644 (1998)

Quantum tunneling with friction

NASA Astrophysics Data System (ADS)

Tokieda, M.; Hagino, K.

2017-05-01

Using the phenomenological quantum friction models introduced by P. Caldirola [Nuovo Cimento 18, 393 (1941), 10.1007/BF02960144] and E. Kanai [Prog. Theor. Phys. 3, 440 (1948), 10.1143/ptp/3.4.440], M. D. Kostin [J. Chem. Phys. 57, 3589 (1972), 10.1063/1.1678812], and K. Albrecht [Phys. Lett. B 56, 127 (1975), 10.1016/0370-2693(75)90283-X], we study quantum tunneling of a one-dimensional potential in the presence of energy dissipation. To this end, we calculate the tunneling probability using a time-dependent wave-packet method. The friction reduces the tunneling probability. We show that the three models provide similar penetrabilities to each other, among which the Caldirola-Kanai model requires the least numerical effort. We also discuss the effect of energy dissipation on quantum tunneling in terms of barrier distributions.

Euler polynomials and identities for non-commutative operators

NASA Astrophysics Data System (ADS)

De Angelis, Valerio; Vignat, Christophe

2015-12-01

Three kinds of identities involving non-commutating operators and Euler and Bernoulli polynomials are studied. The first identity, as given by Bender and Bettencourt [Phys. Rev. D 54(12), 7710-7723 (1996)], expresses the nested commutator of the Hamiltonian and momentum operators as the commutator of the momentum and the shifted Euler polynomial of the Hamiltonian. The second one, by Pain [J. Phys. A: Math. Theor. 46, 035304 (2013)], links the commutators and anti-commutators of the monomials of the position and momentum operators. The third appears in a work by Figuieira de Morisson and Fring [J. Phys. A: Math. Gen. 39, 9269 (2006)] in the context of non-Hermitian Hamiltonian systems. In each case, we provide several proofs and extensions of these identities that highlight the role of Euler and Bernoulli polynomials.

Nonlocal and nonlinear electrostatics of a dipolar Coulomb fluid.

PubMed

Sahin, Buyukdagli; Ralf, Blossey

2014-07-16

We study a model Coulomb fluid consisting of dipolar solvent molecules of finite extent which generalizes the point-like dipolar Poisson-Boltzmann model (DPB) previously introduced by Coalson and Duncan (1996 J. Phys. Chem. 100 2612) and Abrashkin et al (2007 Phys. Rev. Lett. 99 077801). We formulate a nonlocal Poisson-Boltzmann equation (NLPB) and study both linear and nonlinear dielectric response in this model for the case of a single plane geometry. Our results shed light on the relevance of nonlocal versus nonlinear effects in continuum models of material electrostatics.

Study of Spin Splitting in GaN/AlGaN Quantum Wells

DTIC Science & Technology

2009-05-11

plasma-assisted molecular - beam epitaxy ”, Jap. J. Appl. Phys. 47, 891 (2008), we have grown M-plane GaN films with self-assembled C-plane GaN nanopillars...on a γ-LiAlO2 substrate by plasma-assisted molecular - beam epitaxy . The diameters of the basal plane of the nanopillars are about 200 to 900 nm and...Line defects of M-plane GaN grown on γ-LiAlO2 by plasma-assisted molecular beam epitaxy ”, Appl. Phys. Lett. 92 pp.202106 (2008), we studied the

Citations Prize 2011 Citations Prize 2011

NASA Astrophysics Data System (ADS)

Webb, Steve; Harris, Simon

2011-12-01

Physics in Medicine & Biology (PMB) awards its 'Citations Prize' to the authors of the original research paper that has received the most citations in the preceding five years (according to the Institute for Scientific Information (ISI)). The lead author of the winning paper is presented with the Rotblat Medal (named in honour of Professor Sir Joseph Rotblat who was the second—and longest serving—Editor of PMB, from 1961-1972). The winning co-authors each receive a certificate. Susan Hagness (left) receiving the Rotblat Medal from Robert Jeraj of PMB's Editorial Board (right) on behalf of Mariya Lazebnik. The winner of the 2011 Citations Prize for the paper which has received the most citations in the previous 5 years (2006-2010) is A large-scale study of the ultrawideband microwave dielectric properties of normal, benign and malignant breast tissues obtained from cancer surgeries Authors: Mariya Lazebnik, Dijana Popovic, Leah McCartney, Cynthia B Watkins, Mary J Lindstrom, Josephine Harter, Sarah Sewall, Travis Ogilvie, Anthony Magliocco, Tara M Breslin, Walley Temple, Daphne Mew, John H Booske, Michal Okoniewski and Susan C Hagness Reference: Mariya Lazebnik et al 2007 Phys. Med. Biol. 52 6093-115 Discussion of the significance of the winning paper can be found on medicalphysicsweb (medicalphysicsweb.org/cws/article/research/47814). Our congratulations go to the winning authors. Steve Webb Editor-in-Chief Simon Harris Publisher

Technical developments at the NASA Space Radiation Laboratory.

PubMed

Lowenstein, D I; Rusek, A

2007-06-01

The NASA Space Radiation Laboratory (NSRL) located at Brookhaven National Laboratory (BNL) is a center for space radiation research in both the life and physical sciences. BNL is a multidisciplinary research facility operated for the Office of Science of the US Department of Energy (DOE). The BNL scientific research portfolio supports a large and diverse science and technology program including research in nuclear and high-energy physics, material science, chemistry, biology, medial science, and nuclear safeguards and security. NSRL, in operation since July 2003, is an accelerator-based facility which provides particle beams for radiobiology and physics studies (Lowenstein in Phys Med 17(supplement 1):26-29 2001). The program focus is to measure the risks and to ameliorate the effects of radiation encountered in space, both in low earth orbit and extended missions beyond the earth. The particle beams are produced by the Booster synchrotron, an accelerator that makes up part of the injector sequence of the DOE nuclear physics program's Relativistic Heavy Ion Collider. Ion species from protons to gold are presently available, at energies ranging from <100 to >1,000 MeV/n. The NSRL facility has recently brought into operation the ability to rapidly switch species and beam energy to supply a varied spectrum onto a given specimen. A summary of past operation performance, plans for future operations and recent and planned hardware upgrades will be described.

Assessments of Sequential Intensity Modulated Radiation Therapy Boost (SqIB) Treatments Using HART

NASA Astrophysics Data System (ADS)

Pyakuryal, Anil

2009-05-01

A retrospective study was pursued to evaluate the SqIB treatments performed on ten head and neck cancer patients(n=10).Average prescription doses (PDs) of 39 Gy,15Gy and 17.8Gy were delivered consecutively from larger to smaller planning target volumes(ptvs) in three different treatment plans using 6 MV X-ray photon beams from a Linear accelerator (SLA Linac, Elekta) on BID weak on-weak off schedules. These plans were statistically evaluated on basis of plan indices (PIs),dose response of targets and critical structures, and dose tolerance(DT) of various organs utilizing the DVH analysis automated software known as Histogram Analysis in Radiation Therapy-HART(S.Jang et al., 2008, Med Phys 35, p.2812). Mean SqIB PIs were found consistent with the reported values for varying radio-surgical systems.The 95.5%(n=10)of each ptvs and the gross tumor volume also received 95% (n=10)of PDs in treatments. The average volume of ten organs (N=10) affected by each PDs shrank with decreasing size of ptvs in above plans.A largest volume of Oropharynx (79%,n=10,N=10) irradiated at PD, but the largest volume of Larynx (98%, n=10, N=10) was vulnerable to DT of structure (TD50).Thus, we have demonstrated the efficiency and accuracy of HART in the assessment of Linac based plans in radiation therapy treatments of cancer.

Track structure simulation for positron emitters of physical interest. Part II: The case of the radiometals

NASA Astrophysics Data System (ADS)

Le Loirec, C.; Champion, C.

2007-11-01

The development of radiochemical services in hospitals, due to the wide use of Positron Emission Tomography (PET) in nuclear medicine, has led to the synthesis of new radiotracers among them radiometals which present a large panel of advantages in terms of half-life times and emission spectra. The most encouraging are the copper isotopes 62Cu and 64Cu as well as 60Cu and 61Cu and the technetium isotope 94mTc used for diagnosis and pharmacokinetic studies. The manganese isotopes 52mMn, 52Mn and 51Mn also present some interesting characteristics, especially 52mMn produced during the decay of 52Fe. Finally, the less known isotopes 89Zr, 45Ti, and 86Y can also be used as surrogates of some therapeutic agents, whereas 38K, 55Co and 66Ga may be used as PET imaging tracers. In this work, we propose an intercomparison of these PET radiometal isotopes. To do that, we have used the home-made Monte Carlo simulation previously described in Champion and Le Loirec [Phys. Med. Biol. 51 (2006) 1707] to simulate the complete decay of β + tracers in biological matter. Under these conditions, we access to a complete description of the positronic irradiation during PET exams using metallic isotopes. The results obtained are also compared with existing theoretical and experimental data and good agreement is generally observed.

Basic Studies in Plasma Physics

DTIC Science & Technology

1998-01-31

Process in One Dimension, (with B. Derrida and E. Speer), Jour. Stat. Phys., 1997, to appear. [16] Comment on "Phase Separation in Two-Dimensional Fluids...Short version to appear in January 1997 in Physics Today ; the long version is to appear in Jour. Stat. Phys., 87, 463-468, 1997. [25] Microscopic...SIAM J. Math. Anal. 27, 110-134, 1996. [31] Microscopic-Shock Profiles: Exact Solution of a Non-Equilibrium System, (with B. Derrida , S. Janowsky and

Transformative Pulsed Power Science and Technology

DTIC Science & Technology

2014-12-16

Lin, D. Singleton, J. Sanders, A. Kuthi and M.A. Gundersen, “Experimental study of pulsed corona discharge in air at high pressures”, 65th Annual...Kastner, E. Gutmark, and M. A. Gundersen. “Surface Streamer Discharge for Plasma Flow Control Using Nanosecond Pulsed Power.” Plasma Sciences, IEEE... discharge in atmospheric pressure fuel/air mixtures”, J. Phys. D: Appl. Phys. 45 495401 (2012). 28. S. J. Pendleton, S. Bowman, C. Carter, M. A. Gundersen

Assessment of the Sustainability of the Mediterranean Diet Combined with Organic Food Consumption: An Individual Behaviour Approach.

PubMed

Seconda, Louise; Baudry, Julia; Allès, Benjamin; Hamza, Oualid; Boizot-Szantai, Christine; Soler, Louis-Georges; Galan, Pilar; Hercberg, Serge; Lairon, Denis; Kesse-Guyot, Emmanuelle

2017-01-12

Mediterranean diets are promising sustainable food models and the organic food system may provide health and environmental benefits. Combining the two models could therefore be a favourable approach for food sustainability. The aim of this study was to draw up a comparative description of four diets differing in the level of organic foods consumption and the adherence to the Mediterranean diet, using multidisciplinary indicators to assess the sustainability of these diets. Four groups of participants were defined and compared, combining the proportion of organic food in their diet (Org versus Conv) and the adherence to the Mediterranean diet (Med versus NoMed). Conv-NoMed: Conventional consumers and non-Mediterranean diet followers; Conv-Med: Conventional consumers and Mediterranean diet followers; Org-NoMed: Organic consumers and non-Mediterranean diet followers; Org-Med: Organic consumers and Mediterranean diet followers. The adherence to nutritional recommendations was higher among the Org-Med and Conv-Med groups compared to the Conv-NoMed group (using the mPNNS-GS (modified-Programme National nutrition santé guidelines score/13.5 points): 9.29 (95% confidence intervals (CI) = 9.23-9.36) and 9.30 (95% CI = 9.24-9.35) versus 8.19 (95% CI = 8.17-8.22)) respectively. The mean plant/animal protein intake ratio was 1.38 (95% CI = 1.01-1.74) for the Org-Med group versus 0.44 (95% CI = 0.28-0.60) for the Conv-NoMed group. The average cost of the diet of Org-Med participants was the highest: 11.43 €/day (95% CI = 11.34-11.52). This study highlighted the importance of promoting the Mediterranean diet combined with organic food consumption for individual health and environmental aspects but challenges with regard to the cost remain.

Direct Methanol Fuel Cell Battery Replacement Program

DTIC Science & Technology

2011-04-11

Matthey PtRu in operating direct methanol fuel cells” Phys. Chem. Chem. Phys., 10, 6430-6437 (2008) 2. Harry Rivera, Jamie S. Lawton , David E. Budil and...Phys. Chem. B, 112, (29) 8542-8548 (2008) 3. Jamie S. Lawton , Eugene S. Smotkin and David E. Budil, “ESR Investigation of Microviscosity, Microscopic

Pulsed Photolytic Density Scaling Experiment for BiF

DTIC Science & Technology

1989-05-01

on Lasers 86, ed. W. B. Lacina, Soc. for Opt. and Quantum Electronics, STS Press. 281 (1987). 9a. R. F. Heidner, H . Helvajian , J. S. Holloway, and J. B...Koffend, J. Chem. Phys. 84, 2137 (1986). 9b. H . Helvajian , J. S. Holloway, and J. B. Koffend, J. Chem. Phys. (in press). 10. J. B. Koffend and R. F...C. E. Gardner, and R. F. Heidner, J. Chem. Phys. 83, 2904 (1985). 13. R. F. Heidner, H . Helvajian , and J. B. Koffend, J. Chem. Phys. 87, 520 (1987

Reactive Removal of BiF Ground State

DTIC Science & Technology

1990-09-28

1978). 3. W E. Jones and T D. McLean, J. Mol. Spectrosc. 90, 481 (1981). 4. R. E Heidner, H . Helvajian , J. S. Holloway, and J. B. Koffend, J. Chem...Phys. 84, 2137 (1986). 5. C. R. Jones and H . P. Broida, J. Chem. Phys. 60, 4369 (1974). 6. H . Helvajian , J. S. Holloway, and J. B. Koffend, J. Chem...Phys. Rev. A6, 631 (1972). 27. H . Hotop and W C. Lineberger, J. Phys. Chem. Ref. Data 4, 539 (1985). 28. J.M. Herbelin, Conf. Proc., Intl. Gonf. on

Heats of Vaporization of Room Temperature Ionic Liquids by Tunable Vacuum Ultraviolet Photoionization

DTIC Science & Technology

2009-12-07

18) Emel’yanenko, V. N.; Verevkin, S. P.; Heintz, A.; Corfield, J.-A.; deyko, A.; Lovelock , K. R. J.; Licence, P.; Jones, R. G. J. Phys. Chem. B 2008...112, 11734. (19) Armstrong, J. P.; Hurst, C.; Jones, R. G.; Licence, P.; Lovelock , K. R. J.; Satterly, C. J.; Villar-Garcia, I. J. Phys. Chem. Chem...Phys. 2007, 9, 982. (20) Lovelock , K. R. J.; Deyko, A.; Corfield, J.-A.; Gooden, P. N.; Licence, P.; Jones, R. G. ChemPhysChem 2009, 10, 337. (21

Electrostatic Plugging of Multidipole Cusps.

DTIC Science & Technology

1982-05-01

8217, -) V0 100 I-’ 60 00 0> :oc 0 \\0H U 0 0- 0- -L 0 0- P4 A- 602- 179 MASS SPECTROMETER CIRCUIT CHME P OGA- SWOT Figue 1. Shemaic f eteralXly...2R. L. Hirsch, J. Appl . Phys. 38, 4522 (1967). 3N. Hershkowitz K. N. Leung, and T. Romesser, Phys. Rev. Lett. 5. 277 (1975 1. 4A. Kitsunezaki, M...R. T. Carpenter, submitted to J. Appl . Phys. 1OD. Rapp and P. Englander-Golden, J. Chem. Phys. 3, 1464 (1965). "A. Lang and N. Hershkowitz, J. Appl

Upper bound on three-tangles of reduced states of four-qubit pure states

NASA Astrophysics Data System (ADS)

Sharma, S. Shelly; Sharma, N. K.

2017-06-01

Closed formulas for upper bounds on three-tangles of three-qubit reduced states in terms of three-qubit-invariant polynomials of pure four-qubit states are obtained. Our results offer tighter constraints on total three-way entanglement of a given qubit with the rest of the system than those used by Regula et al. [Phys. Rev. Lett. 113, 110501 (2014), 10.1103/PhysRevLett.113.110501 and Phys. Rev. Lett. 116, 049902(E) (2016)], 10.1103/PhysRevLett.116.049902 to verify monogamy of four-qubit quantum entanglement.

Mental Health and Academic Achievement among M.Ed. Students in Kerala

ERIC Educational Resources Information Center

Moradi Sheykhjan, Tohid; K., Rajeswari; Jabari, Kamran

2017-01-01

The present research endeavor was aimed to assess relationship between Mental Health and Academic Achievement among M.Ed. students in Kerala. The sample of the study consisted of 314 M.Ed. students in Kerala. The method used for the present study was survey method. Mental Health Status Scale (M.H.S. Scale) was used and the study used the total…

B80 and B101-103 clusters: Remarkable stability of the core-shell structures established by validated density functionalsa)

NASA Astrophysics Data System (ADS)

Li, Fengyu; Jin, Peng; Jiang, De-en; Wang, Lu; Zhang, Shengbai B.; Zhao, Jijun; Chen, Zhongfang

2012-02-01

Prompted by the very recent claim that the volleyball-shaped B80 fullerene [X. Wang, Phys. Rev. B 82, 153409 (2010), 10.1103/PhysRevB.82.153409] is lower in energy than the B80 buckyball [N. G. Szwacki, A. Sadrzadeh, and B. I. Yakobson, Phys. Rev. Lett. 98, 166804 (2007), 10.1103/PhysRevLett.98.166804] and core-shell structure [J. Zhao, L. Wang, F. Li, and Z. Chen, J. Phys. Chem. A 114, 9969 (2010), 10.1021/jp1018873], and inspired by the most recent finding of another core-shell isomer as the lowest energy B80 isomer [S. De, A. Willand, M. Amsler, P. Pochet, L. Genovese, and S. Goedecher, Phys. Rev. Lett. 106, 225502 (2011), 10.1103/PhysRevLett.106.225502], we carefully evaluated the performance of the density functional methods in the energetics of boron clusters and confirmed that the core-shell construction (stuffed fullerene) is thermodynamically the most favorable structural pattern for B80. Our global minimum search showed that both B101 and B103 also prefer a core-shell structure and that B103 can reach the complete core-shell configuration. We called for great attention to the theoretical community when using density functionals to investigate boron-related nanomaterials.

Adaptive clustering procedure for continuous gravitational wave searches

NASA Astrophysics Data System (ADS)

Singh, Avneet; Papa, Maria Alessandra; Eggenstein, Heinz-Bernd; Walsh, Sinéad

2017-10-01

In hierarchical searches for continuous gravitational waves, clustering of candidates is an important post-processing step because it reduces the number of noise candidates that are followed up at successive stages [J. Aasi et al., Phys. Rev. Lett. 88, 102002 (2013), 10.1103/PhysRevD.88.102002; B. Behnke, M. A. Papa, and R. Prix, Phys. Rev. D 91, 064007 (2015), 10.1103/PhysRevD.91.064007; M. A. Papa et al., Phys. Rev. D 94, 122006 (2016), 10.1103/PhysRevD.94.122006]. Previous clustering procedures bundled together nearby candidates ascribing them to the same root cause (be it a signal or a disturbance), based on a predefined cluster volume. In this paper, we present a procedure that adapts the cluster volume to the data itself and checks for consistency of such volume with what is expected from a signal. This significantly improves the noise rejection capabilities at fixed detection threshold, and at fixed computing resources for the follow-up stages, this results in an overall more sensitive search. This new procedure was employed in the first Einstein@Home search on data from the first science run of the advanced LIGO detectors (O1) [LIGO Scientific Collaboration and Virgo Collaboration, arXiv:1707.02669 [Phys. Rev. D (to be published)

Precision measurements with atom interferometry

NASA Astrophysics Data System (ADS)

Schubert, Christian; Abend, Sven; Schlippert, Dennis; Ertmer, Wolfgang; Rasel, Ernst M.

2017-04-01

Interferometry with matter waves enables precise measurements of rotations, accelerations, and differential accelerations [1-5]. This is exploited for determining fundamental constants [2], in fundamental science as e.g. testing the universality of free fall [3], and is applied for gravimetry [4], and gravity gradiometry [2,5]. At the Institut für Quantenoptik in Hannover, different approaches are pursued. A large scale device is designed and currently being set up to investigate the gain in precision for gravimetry, gradiometry, and fundamental tests on large baselines [6]. For field applications, a compact and transportable device is being developed. Its key feature is an atom chip source providing a collimated high flux of atoms which is expected to mitigate systematic uncertainties [7,8]. The atom chip technology and miniaturization benefits from microgravity experiments in the drop tower in Bremen and sounding rocket experiments [8,9] which act as pathfinders for space borne operation [10]. This contribution will report about our recent results. The presented work is supported by the CRC 1227 DQ-mat, the CRC 1128 geo-Q, the RTG 1729, the QUEST-LFS, and by the German Space Agency (DLR) with funds provided by the Federal Ministry of Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under Grant No. DLR 50WM1552-1557. [1] P. Berg et al., Phys. Rev. Lett., 114, 063002, 2015; I. Dutta et al., Phys. Rev. Lett., 116, 183003, 2016. [2] J. B. Fixler et al., Science 315, 74 (2007); G. Rosi et al., Nature 510, 518, 2014. [3] D. Schlippert et al., Phys. Rev. Lett., 112, 203002, 2014. [4] A. Peters et al., Nature 400, 849, 1999; A. Louchet-Chauvet et al., New J. Phys. 13, 065026, 2011; C. Freier et al., J. of Phys.: Conf. Series 723, 012050, 2016. [5] J. M. McGuirk et al., Phys. Rev. A 65, 033608, 2002; P. Asenbaum et al., arXiv:1610.03832. [6] J. Hartwig et al., New J. Phys. 17, 035011, 2015. [7] H. Ahlers et al., Phys. Rev. Lett. 116, 173601, 2016; S. Abend et al., Phys. Rev. Lett. 117, 203003, 2016. [8] J. Rudolph et al., New J. Phys. 17, 065001, 2015. [9] H. Müntinga et al., Phys. Rev. Lett., 110, 093602, 2013. [10] O. Carraz et al., Microgravity Sci. Technol. 26, 139, 2014; D. Aguilera et al., Class. Quantum Grav. 31, 115010, 2014.

PREFACE: Magnonics Magnonics

NASA Astrophysics Data System (ADS)

Kruglyak, V. V.; Demokritov, S. O.; Grundler, D.

2010-07-01

The study of collective spin excitations in magnetically ordered materials (so-called spin waves and the associated quasi-particles—magnons) has a successful history of more than 60 years. Recently, it has re-emerged in a new aspect under the name of magnonics, although the exact definition of its scope is still a subject for debate. However, it is widely accepted that the recent renaissance of interest in spin waves has been driven by three major factors: the rapid advance of nanotechnology, the development of new experimental techniques for studying high-frequency magnetization dynamics and the promise of a new generation of functional magnetic field controlled devices in which spin waves (magnons) would be employed, in particular to carry and process information. Furthermore, the growing interest in man-made 'crystals', such as those already realized in photonics, electronics and plasmonics, has served as a further strong catalyst for the development of so-called magnonic crystals. Magnonics as a research field is currently gaining momentum, attracting more and more researchers from various sub-fields of magnetism, materials science, microwave engineering, and beyond. Hence, it is timely to define the state of the art of this exciting research field emerging at the interface between magnetism and nanoscience. The first magnonics conference, entitled 'Magnonics: From Fundamentals to Applications' was held in Dresden in August 2009, sponsored by the visitor programme of the Max Planck Institute for the Physics of Complex Systems (MPIPKS). The event was a great success, having achieved its main aim of forming a community of magnonics researchers. It brought together both experts who held worldwide leading positions in nanomagnetism and spin wave research, and younger researchers just entering the field. The research results presented ranged from fundamental magnonic properties to their application in information technologies. The main scientific result of the conference in the broader sense was the emergence of magnonics as a sister field in the family of functional nanomaterials that also includes electronics, photonics, phononics, plasmonics etc. The presentations helped to define the state of the art and to highlight perspectives of the field. The conference led to the idea of publishing this cluster of papers aimed at reviewing the history of and the recent progress in magnonics. The cluster begins with a contribution from Kruglyak et al who aim to define the general scope and concepts of magnonics as a research field [1]. Serga et al review the state of the art in studies of spin waves in yttrium iron garnet (YIG) samples, which—due to the exceptionally low magnetic losses—have been the most popular and extensively investigated so far [2]. Gubbiotti et al review their recent experiments in which the magnonic band gap spectrum was observed in planar metallic magnonic crystals with submicrometre periods [3]. Kim demonstrates how numerical simulations can be used to investigate a wide range of magnonic phenomena in truly magnetic nanostructures, which still remains a challenge for modern experiments [4]. Finally, Khitun et al discuss the prospects and challenges for the creation of magnonic logic devices [5]. As with any dynamic research field, the reviews are inevitably incomplete. Nonetheless, we hope that the cluster of papers will stimulate further progress in magnonics and will provide a useful starting point for researchers newly entering this challenging and exciting research field. References [1] Kruglyak V V, Demokritov S O and Grundler J 2010 J. Phys. D: Appl. Phys.43 264001 [2] Serga A A, Chumak A V and Hillebrands B 2010 J. Phys. D: Appl. Phys. 43 264002 [3] Gubbiotti G, Tacchi S, Madami M, Carlotti G, Adeyeye A O and Kostylev M 2010 J. Phys. D: Appl. Phys. 43 264003 [4] Kim S-K 2010 J. Phys. D: Appl. Phys. 43 264004 [5] Khitun A, Bao M and Wang K L 2010 J. Phys. D: Appl. Phys. 43 264005

Evaluation of intestinal absorption of amtolmetin guacyl in rats: breast cancer resistant protein as a primary barrier of oral bioavailability.

PubMed

Rong, Zhihui; Xu, Yanjiao; Zhang, Chengliang; Xiang, Daochun; Li, Xiping; Liu, Dong

2013-02-27

The purpose of the present study was to investigate the role of efflux transporters on the intestinal absorption of amtolmetin guacyl (MED-15). The effects of P-glycoprotein (P-gp), multiple resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP) inhibitors on intestinal absorption amount of MED-5 (tolmetin-glycine amide derivative), the metabolite formed from MED-15 in the intestinal epithelial cells were studied in the in vitro everted gut sac experiments. Moreover, the in situ single-pass intestine perfusion was adopted to clarify the role of efflux transporters in excreting MED-5 in knockout mice. The plasma concentration of MED-5 and tolmetin, the metabolite formed from MED-5 was determined in Bcrp1 knockout mice and wild-type mice. BCRP inhibitor Ko143 (50 μM and 100 μM) significantly increased the intestinal absorption amount in jejunum, ileum and colon (p<0.05). However, no effect was observed in the presence of P-gp inhibitor verapamil and MRP2 inhibitor MK571 in each intestinal segment. Furthermore, the plasma concentration MED-5 and tolmetin, metabolites of MED-15, increased 2-fold and 4-fold, respectively, in Bcrp1 knockout mice compared with wild-type mice after the single-pass perfusion of small intestine with MED-15. It may be concluded that BCRP plays an important role in the intestinal efflux of MED-5 and limits the bioavailability after oral administration of MED-15. Copyright © 2013. Published by Elsevier Inc.

PubMed had a higher sensitivity than Ovid-MEDLINE in the search for systematic reviews.

PubMed

Katchamart, Wanruchada; Faulkner, Amy; Feldman, Brian; Tomlinson, George; Bombardier, Claire

2011-07-01

To compare the performance of Ovid-MEDLINE vs. PubMed for identifying randomized controlled trials of methotrexate (MTX) in patients with rheumatoid arthritis (RA). We created search strategies for Ovid-MEDLINE and PubMed for a systematic review of MTX in RA. Their performance was evaluated using sensitivity, precision, and number needed to read (NNR). Comparing searches in Ovid-MEDLINE vs. PubMed, PubMed retrieved more citations overall than Ovid-MEDLINE; however, of the 20 citations that met eligibility criteria for the review, Ovid-MEDLINE retrieved 17 and PubMed 18. The sensitivity was 85% for Ovid-MEDLINE vs. 90% for PubMed, whereas the precision and NNR were comparable (precision: 0.881% for Ovid-MEDLINE vs. 0.884% for PubMed and NNR: 114 for Ovid-MEDLINE vs. 113 for PubMed). In systematic reviews of RA, PubMed has higher sensitivity than Ovid-MEDLINE with comparable precision and NNR. This study highlights the importance of well-designed database-specific search strategies. Copyright © 2010 Elsevier Inc. All rights reserved.

Development and calibration of a concept inventory to measure introductory college astronomy and physics students' understanding of Newtonian gravity

NASA Astrophysics Data System (ADS)

Williamson, Kathryn Elizabeth

The topic of Newtonian gravity offers a unique vantage point from which to investigate and encourage conceptual change because it is something with which everyone has daily experience, and because it is taught in two courses that reach a wide variety of students - introductory-level college astronomy ("Astro 101") and physics ("Phys 101"). Informed by the constructivist theory of learning, this study characterizes and measures Astro 101 and Phys 101 students' understanding of Newtonian gravity within four conceptual domains - Directionality, Force Law, Independence of Other Forces, and Threshold. A phenomenographic analysis of Astro 101 student-supplied responses to open-ended questions about gravity results in the characterization of students' alternative mental models and misapplications of the scientific model. These student difficulties inform the development of a multiple-choice assessment instrument, the Newtonian Gravity Concept Inventory (NGCI). Classical Test Theory (CTT) statistics, student interviews, and expert review show that the NGCI is a reliable and valid tool for assessing both Astro 101 and Phys 101 students' understanding of gravity. Furthermore, the NGCI can provide extensive and robust information about differences between Astro 101 and Phys 101 students and curricula. Comparing and contrasting the Astro 101 and Phys 101 CTT values and student response patterns shows qualitative differences in each of the four conceptual domains. Additionally, performing an Item Response Theory (IRT) analysis of NGCI student response data calibrates item parameters for all Astro 101 and Phys 101 courses and provides Newtonian gravity ability estimates for each student. Physics students show significantly higher pre-instruction and post-instruction IRT abilities than astronomy students, but they show approximately equal gains. To investigate the differential effect of Astro 101 compared to Phys 101 curricula on students' overall post-instruction Newtonian gravity ability, linear regression models control for student characteristics and classroom dynamics. Results show that differences in post-instruction abilities are most influenced by students' pre-instruction abilities and the level of interactivity in the classroom, rather than the astronomy curriculum compared to the physics curriculum. These analyses show that the NGCI has broad capabilities.

The Localized Scleroderma Skin Severity Index and Physician Global Assessment of Disease Activity: A Work in Progress Toward Development of Localized Scleroderma Outcome Measures

PubMed Central

ARKACHAISRI, THASCHAWEE; VILAIYUK, SOAMARAT; LI, SUZANNE; O’NEIL, KATHLEEN M.; POPE, ELENA; HIGGINS, GLORIA C.; PUNARO, MARILYNN; RABINOVICH, EGLA C.; ROSENKRANZ, MARGALIT; KIETZ, DANIEL A.; ROSEN, PAUL; SPALDING, STEVEN J.; HENNON, TERESA R.; TOROK, KATHRYN S.; CASSIDY, ELAINE; MEDSGER, THOMAS A.

2013-01-01

Objective To develop and evaluate a Localized Scleroderma (LS) Skin Severity Index (LoSSI) and global assessments’ clinimetric property and effect on quality of life (QOL). Methods A 3-phase study was conducted. The first phase involved 15 patients with LS and 14 examiners who assessed LoSSI [surface area (SA), erythema (ER), skin thickness (ST), and new lesion/extension (N/E)] twice for inter/intrarater reliability. Patient global assessment of disease severity (PtGA-S) and Children’s Dermatology Life Quality Index (CDLQI) were collected for intrarater reliability evaluation. The second phase was aimed to develop clinical determinants for physician global assessment of disease activity (PhysGA-A) and to assess its content validity. The third phase involved 2 examiners assessing LoSSI and PhysGA-A on 27 patients. Effect of training on improving reliability/validity and sensitivity to change of the LoSSI and PhysGA-A was determined. Results Interrater reliability was excellent for ER [intraclass correlation coefficient (ICC) 0.71], ST (ICC 0.70), LoSSI (ICC 0.80), and PhysGA-A (ICC 0.90) but poor for SA (ICC 0.35); thus, LoSSI was modified to mLoSSI. Examiners’ experience did not affect the scores, but training/practice improved reliability. Intrarater reliability was excellent for ER, ST, and LoSSI (Spearman’s rho = 0.71–0.89) and moderate for SA. PtGA-S and CDLQI showed good intrarater agreement (ICC 0.63 and 0.80). mLoSSI correlated moderately with PhysGA-A and PtGA-S. Both mLoSSI and PhysGA-A were sensitive to change following therapy. Conclusion mLoSSI and PhysGA-A are reliable and valid tools for assessing LS disease severity and show high sensitivity to detect change over time. These tools are feasible for use in routine clinical practice. They should be considered for inclusion in a core set of LS outcome measures for clinical trials. PMID:19833758

Knockdown of Mediator Complex Subunit 19 Suppresses the Growth and Invasion of Prostate Cancer Cells

PubMed Central

Zhao, Hongwei; Lv, Wei; Chen, Jian; Wan, Fengchun; Liu, Dongfu; Gao, Zhenli; Wu, Jitao

2017-01-01

Prostate cancer (PCa) is one of the most common cancers in elderly men. Mediator Complex Subunit 19 (Med19) is overexpressed and plays promotional roles in many cancers. However, the roles of Med19 in PCa are still obscure. In this study, by using immunohistochemical staining, we found higher expression level of Med19 in PCa tissues than in adjacent benign prostate tissues. We then knocked down the Med19 expression in PCa cell lines LNCaP and PC3 by using lentivirus siRNA. Cell proliferation, anchor-independent growth, migration, and invasion were suppressed in Med19 knockdown PCa cells. In nude mice xenograft model, we found that Med19 knockdown PCa cells formed smaller tumors with lower proliferation index than did control cells. In the mechanism study, we found that Med19 could regulate genes involved in cell proliferation, cell cycle, and epithelial-mesenchymal transition, including P27, pAKT, pPI3K, IGF1R, E-Cadherin, N-Cadherin, Vimentin, ZEB2, Snail-1 and Snail-2. Targeting Med19 in PCa cells could inhibit the PCa growth and metastasis, and might be a therapeutic option for PCa in the future. PMID:28125713

Oscillator-field model of moving mirrors in quantum optomechanics

NASA Astrophysics Data System (ADS)

Galley, Chad R.; Behunin, Ryan O.; Hu, B. L.

2013-04-01

We present a microphysics model for the kinematics and dynamics of optomechanics describing the coupling between an optical field, modeled here by a massless scalar field, and the internal and mechanical degrees of freedom of a movable mirror. Instead of implementing boundary conditions on the field, we introduce an internal degree of freedom and its dynamics to describe the mirror's reflectivity. Depending on parameter values, the internal degrees of freedom of the mirror in this model capture a range of its optical activities, from those exhibiting broadband reflective properties to those reflecting only in a narrow band. After establishing the model we show how appropriate parameter choices lead to other well-known optomechanical models, including those of Barton and Calogeracos [Ann. Phys. (NY)0003-491610.1006/aphy.1995.1021 238, 227 (1995)], Calogeracos and Barton, Ann. Phys. (NY)10.1006/aphy.1995.1022 238, 268 (1995), Law [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.51.2537 51, 2537 (1995)], and Golestanian and Kardar [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.78.3421 78, 3421 (1997); Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.58.1713 58, 1713 (1998)]. As a simple illustrative application we derive classical radiation pressure cooling from this model. We then connect our microphysics model to the common descriptions of a moving mirror coupled to radiation pressure (e.g., with Nx coupling, where N is the photon number and x is the mirror displacement), making explicit the underlying assumptions made in these phenomenological models. Our model is also applicable to the lesser explored case of small N, which existing models based on sideband approximations [Kimble , Phys. Rev. DPRVDAQ1550-799810.1103/PhysRevD.65.022002 65, 022002 (2001)] have not addressed. Interestingly, we also find that slow-moving mirrors in our model can be described by the ubiquitous Brownian motion model of quantum open systems. The scope of applications of this model ranges from a full quantum-mechanical treatment of radiation pressure cooling and quantum entanglement between macroscopic mirrors to the back reaction of Hawking radiation on black-hole evaporation in a moving mirror analog.

Watching Conformations of Biomolecules: a Microwave Spectroscopy Approach

NASA Astrophysics Data System (ADS)

Lopez, J. C.

2011-06-01

The combination of laser ablation with Fourier transform microwave spectroscopy in supersonic jets (LA-MB-FTMW) has made possible the gas-phase study of solid biomolecules with high melting points. In the experiment, solids are efficiently vaporized by a high-energy laser pulse, supersonically expanded into a evacuated Fabry-Perot cavity and characterised by their rotational spectra. Recent improvements such as the use of picosecond pulse lasers, new ablation nozzles and the extension of the range of the spectrometers to low frequecy have notably increased the sensitivity of our experimental setup. To date different α-, β- and γ-amino acids have been studied using this technique, making possible the characterization of their preferred conformations and gaining insight in the role of intramolecular interactions. Even in conformationally challenging systems the different rotamers of such biomolecules can be identified by rotational spectroscopy as can be illustrated by the assignment of six low-energy conformers in cysteine and aspartic acid, seven in serine and threonine,^a and nine in γ-amino butyric acid (GABA). In all cases the low-energy conformers have been conclusive identified from their experimental rotational and 14N quadrupole coupling constants. The spectra of neurotransmitters and of the nucleic acid bases uracil, thymine, cytosine and guanine have also been studied and their preferred conformers or tautomeric forms determined. The complexes between amino acids and nucleic acid bases with water have also been investigated to obtain information on the possible changes induced in the conformational or tautomeric preferences by the addition of solvent molecules. J. L. Alonso, C. Pérez, M. E. Sanz, J. C. López, S. Blanco, Phys. Chem. Chem. Phys. 11, 617-627 (2009) and references therein M. E. Sanz, J. C. López, J. L. Alonso, Phys. Chem. Chem. Phys., 12, 3573-3578 (2010) S. Blanco, J. C. López, S. Mata and J. L. Alonso, Angew. Chem. Int. Ed. 49, 9187 (2010) J. L. Alonso, M. E. Sanz, J. C. López, V. Cortijo, J. Am. Chem. Soc. 131, 4320 (2009) J. L. Alonso, I. Peña, J. C. López, V. Vaquero, Angew. Chem. Int. Ed. 49, 6141 (2009) J. C. López, J. L. Alonso, I. Peña, V. Vaquero, Phys. Chem. Chem. Phys., 12, 3573-3578 (2010)

Measured and Monte Carlo calculated k{sub Q} factors: Accuracy and comparison

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

Muir, B. R.; McEwen, M. R.; Rogers, D. W. O.

2011-08-15

Purpose: The journal Medical Physics recently published two papers that determine beam quality conversion factors, k{sub Q}, for large sets of ion chambers. In the first paper [McEwen Med. Phys. 37, 2179-2193 (2010)], k{sub Q} was determined experimentally, while the second paper [Muir and Rogers Med. Phys. 37, 5939-5950 (2010)] provides k{sub Q} factors calculated using Monte Carlo simulations. This work investigates a variety of additional consistency checks to verify the accuracy of the k{sub Q} factors determined in each publication and a comparison of the two data sets. Uncertainty introduced in calculated k{sub Q} factors by possible variation ofmore » W/e with beam energy is investigated further. Methods: The validity of the experimental set of k{sub Q} factors relies on the accuracy of the NE2571 reference chamber measurements to which k{sub Q} factors for all other ion chambers are correlated. The stability of NE2571 absorbed dose to water calibration coefficients is determined and comparison to other experimental k{sub Q} factors is analyzed. Reliability of Monte Carlo calculated k{sub Q} factors is assessed through comparison to other publications that provide Monte Carlo calculations of k{sub Q} as well as an analysis of the sleeve effect, the effect of cavity length and self-consistencies between graphite-walled Farmer-chambers. Comparison between the two data sets is given in terms of the percent difference between the k{sub Q} factors presented in both publications. Results: Monitoring of the absorbed dose calibration coefficients for the NE2571 chambers over a period of more than 15 yrs exhibit consistency at a level better than 0.1%. Agreement of the NE2571 k{sub Q} factors with a quadratic fit to all other experimental data from standards labs for the same chamber is observed within 0.3%. Monte Carlo calculated k{sub Q} factors are in good agreement with most other Monte Carlo calculated k{sub Q} factors. Expected results are observed for the sleeve effect and the effect of cavity length on k{sub Q}. The mean percent differences between experimental and Monte Carlo calculated k{sub Q} factors are -0.08, -0.07, and -0.23% for the Elekta 6, 10, and 25 MV nominal beam energies, respectively. An upper limit on the variation of W/e in photon beams from cobalt-60 to 25 MV is determined as 0.4% with 95% confidence. The combined uncertainty on Monte Carlo calculated k{sub Q} factors is reassessed and amounts to between 0.40 and 0.49% depending on the wall material of the chamber. Conclusions: Excellent agreement (mean percent difference of only 0.13% for the entire data set) between experimental and calculated k{sub Q} factors is observed. For some chambers, k{sub Q} is measured for only one chamber of each type--the level of agreement observed in this study would suggest that for those chambers the measured k{sub Q} values are generally representative of the chamber type.« less

Induced magnetic structure in exchange-coupled ferro-/antiferromagnet thin films

NASA Astrophysics Data System (ADS)

Morales, Rafael

2007-03-01

The most prominent feature observed in exchange-coupled ferromagnetic/ antiferromagnetic (FM/AF) bilayers is the so-called exchange bias field (HEB), i.e. the shift of the hysteresis loop along the magnetic field axis. However the exchange bias phenomenon can induce other interesting effects on the FM. In this talk we show two methods to establish a bi-domain state in the FM, due to the coexistence of domains with opposite sign of HEB [1-3]. Magneto-optical, polarized neutron and soft X-ray measurements show that this lateral structure becomes more complex for low magnetocrystalline anisotropy materials where a spin depth profile is created in the FM due to the exchange coupling with the AF [4-6]. The internal magnetic structure in the AF and its role on exchange bias has also been investigated using FM/AF/FM trilayers. These studies demonstrate that the bulk spin configuration in the AF plays a crucial role in the pinning of uncompensated spins at the interface thus determining the HEB . Supported by the US-DOE, European Marie-Curie-OIF and the Alfred P. Sloan Foundation. [1] O. Petracic et al. Appl. Phys. Lett. 87, 222509 (2005) [2] I. V. Roshchin et al. Europhys. Lett. 71, 297 (2005) [3] J. Olamit et al. Phys. Rev. B 72, 012408 (2005) [4] R. Morales et al. Appl. Phys. Lett. 89, 072504 (2006) [5] S. Roy et al. Phys. Rev. Lett. 95, 047201 (2005) [6] Z-P. Li et al. Phys. Rev. Lett. 96, 217205 (2006)

Simultaneous noncontact AFM and STM of Ag:Si(111)-(3×3)R30∘

NASA Astrophysics Data System (ADS)

Sweetman, Adam; Stannard, Andrew; Sugimoto, Yoshiaki; Abe, Masayuki; Morita, Seizo; Moriarty, Philip

2013-02-01

The Ag:Si(111)-(3×3)R30∘ surface structure has attracted considerable debate concerning interpretation of scanning tunneling microscope (STM) and noncontact atomic force microscope (NC-AFM) images. In particular, the accepted interpretation of atomic resolution images in NC-AFM has been questioned by theoretical and STM studies. In this paper, we use combined NC-AFM and STM to conclusively show that the inequivalent trimer (IET) configuration best describes the surface ground state. Thermal-averaging effects result in a honeycomb-chained-trimer (HCT) appearance at room temperature, in contrast to studies suggesting that the IET configuration remains stable at higher temperatures [Zhang, Gustafsson, and Johansson, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.74.201304 74, 201304(R) (2006) and J. Phys.: Conf. Ser.1742-658810.1088/1742-6596/61/1/264 61, 1336 (2007)]. We also comment on results obtained at an intermediate temperature that suggest an intriguing difference between the imaging mechanisms of NC-AFM and STM on structurally fluctuating samples.

Study of methods to increase cluster/dislocation loop densities in electrodes

NASA Astrophysics Data System (ADS)

Yang, Xiaoling; Miley, George H.

2009-03-01

Recent research has developed a technique for imbedding ultra-high density deuterium ``clusters'' (50 to 100 atoms per cluster) in various metals such as Palladium (Pd), Beryllium (Be) and Lithium (Li). It was found the thermally dehydrogenated PdHx retained the clusters and exhibited up to 12 percent lower resistance compared to the virginal Pd samplesootnotetextA. G. Lipson, et al. Phys. Solid State. 39 (1997) 1891. SQUID measurements showed that in Pd these condensed matter clusters approach metallic conditions, exhibiting superconducting propertiesootnotetextA. Lipson, et al. Phys. Rev. B 72, 212507 (2005ootnotetextA. G. Lipson, et al. Phys. Lett. A 339, (2005) 414-423. If the fabrication methods under study are successful, a large packing fraction of nuclear reactive clusters can be developed in the electrodes by electrolyte or high pressure gas loading. This will provide a much higher low-energy-nuclear- reaction (LENR) rate than achieved with earlier electrodeootnotetextCastano, C.H., et al. Proc. ICCF-9, Beijing, China 19-24 May, 2002..

Scaling of Guide-Field Magnetic Reconnection using Anisotropic Fluid Closure

NASA Astrophysics Data System (ADS)

Ohia, O.; Egedal, J.; Lukin, V. S.; Daughton, W.; Le, A.

2012-10-01

Collisionless magnetic reconnection, a process linked to solar flares, coronal mass ejections, and magnetic substorms, has been widely studied through fluid models and fully kinetic simulations. While fluid models often reproduce the fast reconnection rate of fully kinetic simulations, significant differences are observed in the structure of the reconnection regions [1]. However, guide-field fluid simulations implementing new equations of state that accurately account for the anisotropic electron pressure [2] reproduce the detailed reconnection region observed in kinetic simulations [3]. Implementing this two-fluid simulation using the HiFi framework [4], we study the force balance of the electron layers in guide-field reconnection and derive scaling laws for their characteristics.[1ex] [1] Daughton W et al., Phys. Plasmas 13, 072101 (2006).[0ex] [2] Le A et al., Phys. Rev. Lett. 102, 085001 (2009). [0ex] [3] Ohia O, et al., Phys. Rev. Lett. In Press (2012).[0ex] [4] Lukin VS, Linton MG, Nonlinear Proc. Geoph. 18, 871 (2011)

Quantum-tunneling isotope-exchange reaction H2+D-→HD +H-

NASA Astrophysics Data System (ADS)

Yuen, Chi Hong; Ayouz, Mehdi; Endres, Eric S.; Lakhamanskaya, Olga; Wester, Roland; Kokoouline, Viatcheslav

2018-02-01

The tunneling reaction H2+D-→HD +H- was studied in a recent experimental work at low temperatures (10, 19, and 23 K) by Endres et al. [Phys. Rev. A 95, 022706 (2017), 10.1103/PhysRevA.95.022706]. An upper limit of the rate coefficient was found to be about 10-18cm3 /s. In the present study, reaction probabilities are determined using the ABC program developed by Skouteris et al. [Comput. Phys. Commun. 133, 128 (2000), 10.1016/S0010-4655(00)00167-3]. The probabilities for ortho-H2 and para-H2 in their ground rovibrational states are obtained numerically at collision energies above 50 meV with the total angular momentum J =0 -15 and extrapolated below 50 meV using a WKB approach. Thermally averaged rate coefficients for ortho- and para-H2 are obtained; the largest one, for ortho-H2, is about 3.1 ×10-20cm3 /s, which agrees with the experimental results.

Mapping Nanoscale Absorption of Femtosecond Laser Pulses Using Plasma Explosion Imaging

DTIC Science & Technology

2014-08-06

Libby, S. B.; et al. Observation and Control of Shock Waves in Indivi- dual Nanoplasmas . Phys. Rev. Lett. 2014, 112, 115004. 17. Zhang, X.; Smith, K. a...Laser Light. Phys. Plasmas 2005, 12, 056703. 24. Lezius, M.; Dobosz, S. Hot Nanoplasmas from Intense Laser Irradiation of Argon Clusters. J. Phys. B

Asymptotics of the monomer-dimer model on two-dimensional semi-infinite lattices

NASA Astrophysics Data System (ADS)

Kong, Yong

2007-05-01

By using the asymptotic theory of Pemantle and Wilson [R. Pemantle and M. C. Wilson, J. Comb. Theory, Ser. AJCBTA70097-316510.1006/jcta.2001.3201 97, 129 (2002)], asymptotic expansions of the free energy of the monomer-dimer model on two-dimensional semi-infinite ∞×n lattices in terms of dimer density are obtained for small values of n , at both high- and low-dimer-density limits. In the high-dimer-density limit, the theoretical results confirm the dependence of the free energy on the parity of n , a result obtained previously by computational methods by Y. Kong [Y. Kong, Phys. Rev. EPLEEE81063-651X10.1103/PhysRevE.74.061102 74, 061102 (2006); Phys. Rev. EPLEEE81063-651X10.1103/PhysRevE.73.016106 73, 016106 (2006);Phys. Rev. EPLEEE81063-651X10.1103/PhysRevE.74.011102 74, 011102 (2006)]. In the low-dimer-density limit, the free energy on a cylinder ∞×n lattice strip has exactly the same first n terms in the series expansion as that of an infinite ∞×∞ lattice.

Reply to "Comment on `Conductance scaling in Kondo-correlated quantum dots: Role of level asymmetry and charging energy'"

NASA Astrophysics Data System (ADS)

Merker, L.; Kirchner, S.; Muñoz, E.; Costi, T. A.

2014-08-01

The Comment of A. A. Aligia claims that the superperturbation theory (SPT) approach [E. Muñoz, C. J. Bolech, and S. Kirchner, Phys. Rev. Lett. 110, 016601 (2013), 10.1103/PhysRevLett.110.016601] formulated using dual fermions [A. N. Rubtsov, M. I. Katsnelson, and A. I. Lichtenstein, Phys. Rev. B 77, 033101 (2008), 10.1103/PhysRevB.77.033101] and used by us to compare with numerical renormalization group (NRG) results for the conductance [L. Merker, S. Kirchner, E. Muñoz, and T. A. Costi, Phys. Rev. B 87, 165132 (2013), 10.1103/PhysRevB.87.165132], fails to correctly extend the results of the symmetric Anderson impurity model (SIAM) for general values of the local level Ed in the Kondo regime. We answer this criticism. We also compare new NRG results for cB, with cB calculated directly from the low-field conductance, with new higher-order SPT calculations for this quantity, finding excellent agreement for all Ed and for U /πΔ extending into the strong coupling regime.

Study of Water Absorption Lines in the Near Infrared

DTIC Science & Technology

1975-02-17

the absorption coefficient is better approximated by the sum of Matcha -N«. oec short range contribution and W-BB dispersion contribution. The...and W. Byers Brown, Molecular Physics 2S, 1105 (1973). 5. R. L. Matcha and R. K. Nesbet, Phys. Rev. 1_6_0, 72 (1967). I H. B. Levine, Phys. Rev...reasurcrents of Ouren, ^eltqen Gaide, Helbing and Pauly. The dipole moment function is taken from ab initio 9 calculations of Matcha and Nesbet. With

Comment on "Spontaneous liquid-liquid phase separation of water"

NASA Astrophysics Data System (ADS)

Limmer, David T.; Chandler, David

2015-01-01

Yagasaki et al. [Phys. Rev. E 89, 020301 (2014), 10.1103/PhysRevE.89.020301] present results from a molecular dynamics trajectory illustrating coarsening of ice, which they interpret as evidence of transient coexistence between two distinct supercooled phases of liquid water. We point out that neither two distinct liquids nor criticality are demonstrated in this simulation study. Instead, the illustrated trajectory is consistent with coarsening behaviors analyzed and predicted in earlier work by others.

Surface Structure of Aerobically Oxidized Diamond Nanocrystals

DTIC Science & Technology

2014-10-27

Diamond. Phys. Rev. Lett. 2000, 84, 5160−5163. (31) Ownby, P. D.; Yang, X.; Liu, J. Calculated X-Ray-Diffraction Data for Diamond Polytypes. J. Am. Ceram...Surfaces from Ab-Initio Calculations . Phys. Rev. B 1995, 51, 14669−14685. (39) Ferrari, A. C.; Robertson, J. Raman Spectroscopy of Amorphous, Nanostructured...Y.; Takami, S.; Kubo , M.; Belosludov, R. V.; Miyamoto, A.; Imamura, A.; Gamo, M. N.; Ando, T. First-Principle Study on Reactions of Diamond (100

Intercomparison of methods for image quality characterization. I. Modulation transfer function

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

Samei, Ehsan; Ranger, Nicole T.; Dobbins, James T. III

The modulation transfer function (MTF) and the noise power spectrum (NPS) are widely recognized as the most relevant metrics of resolution and noise performance in radiographic imaging. These quantities have commonly been measured using various techniques, the specifics of which can have a bearing on the accuracy of the results. As a part of a study aimed at comparing the relative performance of different techniques, in this paper we report on a comparison of two established MTF measurement techniques: one using a slit test device [Dobbins et al., Med. Phys. 22, 1581-1593 (1995)] and another using a translucent edge testmore » device [Samei et al., Med. Phys. 25, 102-113 (1998)], with one another and with a third technique using an opaque edge test device recommended by a new international standard (IEC 62220-1, 2003). The study further aimed to substantiate the influence of various acquisition and processing parameters on the estimated MTF. The slit test device was made of 2 mm thick Pb slabs with a 12.5 {mu}m opening. The translucent edge test device was made of a laminated and polished Pt{sub 0.9}Ir{sub 0.1} alloy foil of 0.1 mm thickness. The opaque edge test device was made of a 2 mm thick W slab. All test devices were imaged on a representative indirect flat-panel digital radiographic system using three published beam qualities: 70 kV with 0.5 mm Cu filtration, 70 kV with 19 mm Al filtration, and 74 kV with 21 mm Al filtration (IEC-RQA5). The latter technique was also evaluated in conjunction with two external beam-limiting apertures (per IEC 62220-1), and with the tube collimator limiting the beam to the same area achieved with the apertures. The presampled MTFs were deduced from the acquired images by Fourier analysis techniques, and the results analyzed for relative values and the influence of impacting parameters. The findings indicated that the measurement technique has a notable impact on the resulting MTF estimate, with estimates from the overall IEC method 4.0%{+-}0.2% lower than that of Dobbins et al. and 0.7%{+-}0.4% higher than that of Samei et al. averaged over the zero to cutoff frequency range. Over the same frequency range, keeping beam quality and limitation constant, the average MTF estimate obtained with the edge techniques differed by up to 5.2%{+-}0.2% from that of the slit, with the opaque edge providing lower MTF estimates at lower frequencies than those obtained with the translucent edge or slit. The beam quality impacted the average estimated MTF by as much as 3.7%{+-}0.9% while the use of beam limiting devices alone increased the average estimated MTF by as much as 7.0%{+-}0.9%. While the slit method is inherently very sensitive to misalignment, both edge techniques were found to tolerate misalignments by as much as 6 cm. The results suggest the use of the opaque edge test device and the tube internal collimator for beam limitation in order to achieve an MTF result most reflective of the overall performance of the imaging system and least susceptible to misalignment and scattered radiation. Careful attention to influencing factors is warranted to achieve accurate results.« less

Intercomparison of methods for image quality characterization. I. Modulation transfer function.

PubMed

Samei, Ehsan; Ranger, Nicole T; Dobbins, James T; Chen, Ying

2006-05-01

The modulation transfer function (MTF) and the noise power spectrum (NPS) are widely recognized as the most relevant metrics of resolution and noise performance in radiographic imaging. These quantities have commonly been measured using various techniques, the specifics of which can have a bearing on the accuracy of the results. As a part of a study aimed at comparing the relative performance of different techniques, in this paper we report on a comparison of two established MTF measurement techniques: one using a slit test device [Dobbins et al., Med. Phys. 22, 1581-1593 (1995)] and another using a translucent edge test device [Samei et al., Med. Phys. 25, 102-113 (1998)], with one another and with a third technique using an opaque edge test device recommended by a new international standard (IEC 62220-1, 2003). The study further aimed to substantiate the influence of various acquisition and processing parameters on the estimated MTF. The slit test device was made of 2 mm thick Pb slabs with a 12.5 microm opening. The translucent edge test device was made of a laminated and polished Pt(0.9)Ir(0.1). alloy foil of 0.1 mm thickness. The opaque edge test device was made of a 2 mm thick W slab. All test devices were imaged on a representative indirect flat-panel digital radiographic system using three published beam qualities: 70 kV with 0.5 mm Cu filtration, 70 kV with 19 mm Al filtration, and 74 kV with 21 mm Al filtration (IEC-RQA5). The latter technique was also evaluated in conjunction with two external beam-limiting apertures (per IEC 62220-1), and with the tube collimator limiting the beam to the same area achieved with the apertures. The presampled MTFs were deduced from the acquired images by Fourier analysis techniques, and the results analyzed for relative values and the influence of impacting parameters. The findings indicated that the measurement technique has a notable impact on the resulting MTF estimate, with estimates from the overall IEC method 4.0% +/- 0.2% lower than that of Dobbins et al. and 0.7% +/- 0.4% higher than that of Samei et al. averaged over the zero to cutoff frequency range. Over the same frequency range, keeping beam quality and limitation constant, the average MTF estimate obtained with the edge techniques differed by up to 5.2% +/- 0.2% from that of the slit, with the opaque edge providing lower MTF estimates at lower frequencies than those obtained with the translucent edge or slit. The beam quality impacted the average estimated MTF by as much as 3.7% +/- 0.9% while the use of beam limiting devices alone increased the average estimated MTF by as much as 7.0% +/- 0.9%. While the slit method is inherently very sensitive to misalignment, both edge techniques were found to tolerate misalignments by as much as 6 cm. The results suggest the use of the opaque edge test device and the tube internal collimator for beam limitation in order to achieve an MTF result most reflective of the overall performance of the imaging system and least susceptible to misalignment and scattered radiation. Careful attention to influencing factors is warranted to achieve accurate results.

Quantum correlations in a family of bipartite separable qubit states

NASA Astrophysics Data System (ADS)

Xie, Chuanmei; Liu, Yimin; Chen, Jianlan; Zhang, Zhanjun

2017-03-01

Quantum correlations (QCs) in some separable states have been proposed as a key resource for certain quantum communication tasks and quantum computational models without entanglement. In this paper, a family of nine-parameter separable states, obtained from arbitrary mixture of two sets of bi-qubit product pure states, is considered. QCs in these separable states are studied analytically or numerically using four QC quantifiers, i.e., measurement-induced disturbance (Luo in Phys Rev A77:022301, 2008), ameliorated MID (Girolami et al. in J Phys A Math Theor 44:352002, 2011),quantum dissonance (DN) (Modi et al. in Phys Rev Lett 104:080501, 2010), and new quantum dissonance (Rulli in Phys Rev A 84:042109, 2011), respectively. First, an inherent symmetry in the concerned separable states is revealed, that is, any nine-parameter separable states concerned in this paper can be transformed to a three-parameter kernel state via some certain local unitary operation. Then, four different QC expressions are concretely derived with the four QC quantifiers. Furthermore, some comparative studies of the QCs are presented, discussed and analyzed, and some distinct features about them are exposed. We find that, in the framework of all the four QC quantifiers, the more mixed the original two pure product states, the bigger QCs the separable states own. Our results reveal some intrinsic features of QCs in separable systems in quantum information.

Numerical studies of nonlocal effects of the low mode numbers tearing modes and their mitigation in the DIII-D

NASA Astrophysics Data System (ADS)

Punjabi, Alkesh; Ali, Halima; Evans, Todd

2006-10-01

In this work, the method of maps [1-4] is used to study the trajectories of magnetic field lines in the DIII-D tokamak. Data from the DIII-D shot 115467 is used to determine the parameters in the maps. Effects of the m=1, n=±1 tearing modes and the dipole perturbation from the C-coils on the motion of field lines are calculated. Internal tearing modes produce non-local effects on the magnetic footprints, and destroy their symmetry. Dipole perturbations mitigate the effects of the tearing modes, spread the heat-flux on the plates over a wider area, reduce the peak heat-flux, and reorganize the phase space structure in a new pattern that has the same symmetry as that of the external perturbation. The low dimensionality of the system and its symplecticity impose severe restrictions on the motion of the system in phase space forcing it to take on the symmetry properties of the perturbations. This work is done under the DOE grant number DE-FG02-01ER54624. 1. A. Punjabi, A. Boozer, and A. Verma, Phys. Rev. lett., 69, 3322 (1992). 2. H. Ali, A. Punjabi, and A. Boozer, Phys. Plasmas 11, 4527 (2004). 3. A. Punjabi, H. Ali, and A. Boozer, Phys. Plasmas 10, 3992 (2003). 4. A. Punjabi, H. Ali, and A. Boozer, Phys. Plasmas 4, 337 (1997).

Summary of PhysPAG Activities

NASA Astrophysics Data System (ADS)

Ritz, Steven M.

2013-01-01

The Physics of the Cosmos (PCOS) Program Analysis Group (PhysPAG) provides an important interface between the scientific community and NASA in matters related to PCOS objectives, and also provides opportunities for community discussions. An Executive Committee facilitates the work of several subgroups, including an Inflation Probe Science Analysis Group (IPSAG), an X-ray group (XRSAG) , a gamma-ray,group (GRSAG), a gravitational wave group (GWSAG), and a cosmic-ray group (CRSAG). In addition to identifying opportunities and issues, these groups also help articulate technology needs. Membership in all the SAGs is completely open, with information and newsletter signups available on the PhysPAG pages at the PCOS program website. The PhysPAG reports to the Astrophysics Subcommittee of the NASA Advisory Council. A summary of PhysPAG activities will be given, along with time for questions and discussion.

Mediterranean diet adherence in individuals with prediabetes and unknown diabetes: the Di@bet.es Study.

PubMed

Ortega, E; Franch, J; Castell, C; Goday, A; Ribas-Barba, L; Soriguer, F; Vendrell, J; Casamitjana, R; Bosch-Comas, A; Bordiú, E; Calle-Pascual, A; Carmena, R; Castaño, L; Catalá, M; Delgado, E; Gaztambide, S; Girbés, J; López-Alba, A; Martínez-Larrad, M T; Menéndez, E; Mora-Peces, I; Pascual-Manich, G; Rojo-Martínez, G; Serrano-Rios, M; Urrutía, I; Valdés, S; Vázquez, J A; Gomis, R

2013-01-01

Mediterranean diet (MedDiet) is causally related to diabetes and is a dietary pattern recommended to individuals with diabetes. We investigated MedDiet adherence in individuals with prediabetes and unknown (PREDM/UKDM) or known diabetes (KDM) compared to those with normal glucose metabolism (NORMAL). This was a national, population-based, cross-sectional, cluster-sampling study. MedDiet adherence was scored (MedScore, mean ± SD 24 ± 5) using a qualitative food frequency questionnaire. Logistic regression was used to examine the association between MedScore and PREDM/UKDM or KDM versus control subjects. We evaluated 5,076 individuals. Mean age was 50 years, 57% were female, 826 (582/244) were PREDM/UKDM, 478 were KDM and 3,772 were NORMAL. Mean age increased across MedScore tertiles (46, 51 and 56 years, p < 0.0001). Higher age-adjusted adherence to MedDiet (5-unit increment in the MedScore) was associated with lower and nondifferent odds (OR, 95% CI) of prevalent PREDM/UKDM (0.88, 0.81-0.96, p = 0.001) and KDM (0.97, 0.87-1.07, p = 0.279), respectively, compared to individuals in the NORMAL group. In a representative sample of the whole Spanish population, MedDiet adherence is independently associated with PREDM/UKDM. Therapeutic intervention may be, in part, responsible for the lack of differences in adherence observed between the KDM and NORMAL groups. However, reverse causation bias cannot be ruled out in cross-sectional studies. Copyright © 2013 S. Karger AG, Basel.

Hydrodynamic description of spin Calogero-Sutherland model

NASA Astrophysics Data System (ADS)

Abanov, Alexander; Kulkarni, Manas; Franchini, Fabio

2009-03-01

We study a non-linear collective field theory for an integrable spin-Calogero-Sutherland model. The hydrodynamic description of this SU(2) model in terms of charge density, charge velocity and spin currents is used to study non-perturbative solutions (solitons) and examine their correspondence with known quantum numbers of elementary excitations [1]. A conventional linear bosonization or harmonic approximation is not sufficient to describe, for example, the physics of spin-charge (non)separation. Therefore, we need this new collective bosonic field description that captures the effects of the band curvature. In the strong coupling limit [2] this model reduces to integrable SU(2) Haldane-Shastry model. We study a non-linear coupling of left and right spin currents which form a Kac-Moody algebra. Our quantum hydrodynamic description for the spin case is an extension for the one found in the spinless version in [3].[3pt] [1] Y. Kato,T. Yamamoto, and M. Arikawa, J. Phys. Soc. Jpn. 66, 1954-1961 (1997).[0pt] [2] A. Polychronakos, Phys Rev Lett. 70,2329-2331(1993).[0pt] [3] A.G.Abanov and P.B. Wiegmann, Phys Rev Lett 95, 076402(2005)

How accurate are the parametrized correlation energies of the uniform electron gas?

NASA Astrophysics Data System (ADS)

Bhattarai, Puskar; Patra, Abhirup; Shahi, Chandra; Perdew, John P.

2018-05-01

Density functional approximations to the exchange-correlation energy are designed to be exact for an electron gas of uniform density parameter rs and relative spin polarization ζ , requiring a parametrization of the correlation energy per electron ɛc(rs,ζ ) . We consider three widely used parametrizations [J. P. Perdew and A. Zunger, Phys. Rev. B 23, 5048 (1981), 10.1103/PhysRevB.23.5048 or PZ81, S. H. Vosko, L. Wilk, and M. Nusair, Can. J. Phys. 58, 1200 (1980), 10.1139/p80-159 or VWN80, and J. P. Perdew and Y. Wang, Phys. Rev. B 45, 13244 (1992), 10.1103/PhysRevB.45.13244 or PW92] that interpolate the quantum Monte Carlo (QMC) correlation energies of Ceperley-Alder [Phys. Rev. Lett. 45, 566 (1980), 10.1103/PhysRevLett.45.566], while extrapolating them to known high-(rs→0 ) and low- (rs→∞ ) density limits. For the physically important range 0.5 ≤rs≤20 , they agree closely with one another, with differences of 0.01 eV (0.5%) or less between the latter two. The density parameter interpolation (DPI), designed to predict these energies by interpolation between the known high- and low-density limits, with almost no other input (and none for ζ =0 ), is also reasonably close, both in its original version and with corrections for ζ ≠0 . Moreover, the DPI and PW92 at rs=0.5 are very close to the high-density expansion. The larger discrepancies with the QMC of Spink et al. [Phys. Rev. B 88, 085121 (2013), 10.1103/PhysRevB.88.085121], of order 0.1 eV (5%) at rs=0.5 , are thus surprising, suggesting that the constraint-based PW92 and VWN80 parametrizations are more accurate than the QMC for rs<2 . For rs>2 , however, the QMC of Spink et al. confirms the dependence upon relative spin polarization predicted by the parametrizations.

Thermodynamics of Supercooled and Glassy Water

NASA Astrophysics Data System (ADS)

Debenedetti, Pablo G.

1998-03-01

The behavior of metastable water at low temperatures is unusual. The isothermal compressibility, the isobaric heat capacity, and the magnitude of the thermal expansion coefficient increase sharply upon supercooling, and structural relaxation becomes extremely sluggish at temperatures far above the glass transition(Angell, C.A., Annu. Rev. Phys. Chem., 34, 593, 1983)(Debenedetti, P.G., Metastable Liquids. Concepts and Principles, Princeton University Press, 1996). Water has two distinct glassy phases, low- and high-density amorphous ice (LDA, HDA). The transition between LDA and HDA is accompanied by sharp volume and enthalpy changes, and appears to be first-order(Mishima, O., L.D.Calvert, and E. Whalley, Nature, 314, 76, 1985)(Mishima, O., J. Chem. Phys., 100, 5910, 1994). The understanding of these observations in terms of an underlying global phase behavior remains incomplete(Speedy, R.J., J. Phys. Chem., 86, 982, 1982)(Poole, P.H., F. Sciortino, U. Essman, and H.E. Stanley, Nature, 360, 324, 1992)(Sastry, S., P.G. Debenedetti, F. Sciortino, and H.E. Stanley, Phys. Rev. E, 53, 6144, 1996)(Tanaka, H., Nature, 380, 328, 1996)(Xie, Y., K.F. Ludwig, G. Morales, D.E. Hare, and C.M. Sorensen, Phys. Rev. Lett., 71, 2050, 1993). Microscopic theories and computer simulations suggest several scenarios that can reproduce some experimental observations. Interesting and novel ideas have resulted from this body of theoretical work, such as the possibility of liquid-liquid immiscibility in a pure substance(Poole, P.H., F.Sciortino, T.Grande, H.E. Stanley, and C.A. Angell, Phys. Rev. Lett., 73, 1632, 1994)(Roberts, C.J., and P.G. Debenedetti, J. Chem. Phys., 105, 658, 1996)(Roberts, C.J., P.G. Debenedetti, and A.Z. Panagiotopoulos, Phys. Rev. Lett., 77, 4386, 1996)(Harrington, S., R. Zhang, P.H. Poole, F. Sciortino, and H.E. Stanley, Phys. Rev. Lett., 78, 2409, 1997). In this talk I will review the experimental facts, discuss their theoretical interpretation, and identify key unanswered questions.

Collisionless damping of flows in the TJ-II stellarator

NASA Astrophysics Data System (ADS)

Sánchez, E.; Kleiber, R.; Hatzky, R.; Borchardt, M.; Monreal, P.; Castejón, F.; López-Fraguas, A.; Sáez, X.; Velasco, J. L.; Calvo, I.; Alonso, A.; López-Bruna, D.

2013-01-01

The results of global linear gyrokinetic simulations of residual flows carried out with the code EUTERPE in the TJ-II three-dimensional geometry are reported. The linear response of the plasma to potential perturbations homogeneous in a magnetic surface shows several oscillation frequencies: a Geodesic-acoustic-mode-like frequency, in qualitative agreement with the formula given by Sugama and Watanabe (2006 Plasma Phys. 72 825), and a much lower frequency oscillation in agreement with the predictions of Mishchenko et al (2008 Phys. Plasmas 15 072309) and Helander et al (2011 Plasma Phys. Control. Fusion 53 054006) for stellarators. The dependence of both oscillations on ion and electron temperatures and the magnetic configuration is studied. The low-frequency oscillations are in the frequency range supporting the long-range correlations between potential signals experimentally observed in TJ-II.

The E(2) particle

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

Ghosh, Subir; Pal, Probir; Physics Department, Uluberia College, Uluberia, Howrah 711315

2009-12-15

Recently it has been advocated [A. G. Cohen and S. L. Glashow, Phys. Rev. Lett. 97, 021601 (2006)] that for describing nature within the minimal symmetry requirement, certain subgroups of the Lorentz group may play a fundamental role. One such group is E(2) which induces a Lie algebraic noncommutative spacetime [M. M. Sheikh-Jabbari and A. Tureanu, Phys. Rev. Lett. 101, 261601 (2008); arXiv:0811.3670] where translation invariance is not fully maintained. We have constructed a consistent structure of noncommutative phase space for this system, and furthermore we have studied an appropriate point particle action on it. Interestingly, the Einstein dispersion relationmore » p{sup 2}=m{sup 2} remains intact. The model is constructed by exploiting a dual canonical phase space following the scheme developed by us earlier [S. Ghosh and P. Pal, Phys. Rev. D 75, 105021 (2007)].« less

Left-handed materials and negative refraction: Transfer matrix and FDTD calculations

NASA Astrophysics Data System (ADS)

Soukoulis, Costas M.

2004-03-01

We will present transfer matrix calculations of metallic wires, split ring resonators (SRR) and left-handed materials (LHM). Our results [1] show that the transfer matrix method can capture all the details characteristics of the metamaterials. In particular the dependence of the resonance frequency and its width on the structural parameters of the SRR and the size of the unit cell is studied. Also the dependence of the imaginary part of effective permittivity of arrays of metallic wires is studied in detail. It is found [2,3] that the imaginary part of effective permittivity has small values even for wires as small as 20 micron in diameter. The transfer matrix is very useful in calculating both the amplitude and the phase of the transmission and reflection coefficient. These numerical data was used [4] in the determination of the effective parameters of the metamaterials. It was indeed found that the refractive index was unambiguously negative in the frequency region where both ɛ and μ were negative. Finally, we will show that SRR have a strong electric response, equivalent to that of cut wires [5], which dominates the response of LHM. A new criterion is introduced to clearly identify if an experimental expression peak is left- or right handed. Finite difference time domain (FDTD) simulations will be presented for the transmission of the EM wave through the interface of the positive and negative refraction index. It is found [6] that the wave is trapped temporarily at the interface and after a long time the wave front moves eventually in the direction of negative refraction. The differences between negative refraction in photonic crystals and left-handed materials will be also discussed. Work supported by US-DOE, DARPA, NSF and EU (DALHM project). References: [1] P. Markos and C. M. Soukoulis, Phys. Rev. B 65, 033401 (2002); Phys. Rev. E 65, 036622 (2002). [2] P. Markos, I. Rousochatzakis and C. M. Soukoulis, Phys. Rev. B 66, 045601 (2002). [3] P. Markos and C. M. Soukoulis, Optics Letters 28, 846 (2003); Optics Express 11, 649 (2003). [4] D. R. Smith, S. Schultz, P. Markos and C. M. Soukoulis, Phys. Rev. B 65, 195104 (2002). [5] Th. Koschny, P. Markos, D. R. Smith and C. M. Soukoulis, Phys. Rev. E 67, xxxx (2003) [6] S. Foteinopoulou, E. N. Economou and C. M. Soukoulis, Phys. Rev. Lett. 90, 107402 (2003); S. Foteinopoulou and C. M. Soukoulis, Phys. Rev. B 67, 235107 (2003)

Optical Measurement and Modeling of Interactions between Two Hole Spins or Two Electron Spins in Coupled InAs Quantum Dots

DTIC Science & Technology

2013-03-12

Loss, Phys. Rev. B 62, 2581 (2000). [10] R. I. Dzhioev, K.V. Kavokin, V. L. Korenev , M.V. Lazarev, B.Y. Meltser, M.N. Stepanova, B. P. Zakharchenya... Korenev , T. L. Reinecke, and D. Gammon, Phys. Rev. B 75, 245318 (2007). [12] D. Kim, S. G. Carter, A. Greilich, A. S. Bracker, and D. Gammon, Nat. Phys. 7...I. V. Ponomarev, E. A. Stinaff, A. S. Bracker, V. L. Korenev , T. L. Reinecke, and D. Gammon, Phys. Rev. Lett. 97, 197202 (2006). [30] W. Liu, S

Universal formulation of excitonic linear absorption spectra in all semiconductor microstructures

NASA Astrophysics Data System (ADS)

Lefebvre, Pierre; Christol, Philippe; Mathieu, Henry

1995-01-01

We present a generalization of the well-known exciton absorption calculations of Elliott [Phys. Rev. 108, 1384 (1957)], in the 3-dimensional case, and of Shinada and Sugano [J. Phys. Soc. Japan 21, 1936 (1966)], for 2-dimensional media: We calculate the optical absorption spectra of bound and unbound exciton states, by using a metric space with a noninteger dimension α (1 < α), obtaining almost exactly the same theoretical lineshapes as those resulting from accurate but costly numerical approaches [Chuang et al. Phys. Rev. B, 43, 1500 (1991); Benner and Haug, Phys. Rev. B 47, 15750 (1993)].

Resonance Fluorescence of a Two-Level Atom Near a Metal Surface. II. Case of a Strong Driving Field,

DTIC Science & Technology

1984-02-01

XYH thanks Prof. M. G. Raymer for a useful discussion. REFERENCES 1. X. Y. Huang, J. Lin and T. F. George, J. Chem. Phys., 80, 893 (1984). 2. X. Y...Mollow, Phys. Rev. A, 15, 1023 (1977). 12. J. L. Carlsten, A. Sz6ke and M. G. Raymer , Phys. Rev. A, 15, 1029 (1977). 13. H. Kuhn, J. Chem. Phys. 53, 101...Evanston, Illinois 60201 Austin, Texas 78712 Dr. Robert M. Hexter Dr. R. P. Van Duyne Department of Chemistry Chemistry Department University of Minnesota

Comment on “Stationary self-focusing of Gaussian laser beam in relativistic thermal quantum plasma” [Phys. Plasmas 20, 072703 (2013)

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

Habibi, M., E-mail: habibi.physics@gmail.com; Ghamari, F.

2014-06-15

Patil and Takale in their recent article [Phys. Plasmas 20, 072703 (2013)], by evaluating the quantum dielectric response in thermal quantum plasma, have modeled the relativistic self-focusing of Gaussian laser beam in a plasma. We have found that there are some important shortcomings and fundamental mistakes in Patil and Takale [Phys. Plasmas 20, 072703 (2013)] that we give a brief description about them and refer readers to important misconception about the use of the Fermi temperature in quantum plasmas, appearing in Patil and Takale [Phys. Plasmas 20, 072703 (2013)].

Does atomic polarizability play a role in hydrogen radio recombination spectra from Galactic H II regions?

NASA Astrophysics Data System (ADS)

Hey, J. D.

2013-09-01

Since highly excited atoms, which contribute to the radio recombination spectra from Galactic H II regions, possess large polarizabilities, their lifetimes are influenced by ion (proton)-induced dipole collisions. It is shown that, while these ion-radiator collisional processes, if acting alone, would effectively limit the upper principal quantum number attainable for given plasma parameters, their influence is small relative to that of electron impacts within the framework of line broadening theory. The present work suggests that ion-permanent dipole interactions (Hey et al 2004 J. Phys. B: At. Mol. Opt. Phys. 37 2543) would also be of minor importance in limiting the occupation of highly excited states. On the other hand, the ion-induced dipole collisions are essential for ensuring equipartition of energy between atomic and electron kinetic distributions (Hey et al 1999 J. Phys. B: At. Mol. Opt. Phys. 32 3555; 2005 J. Phys. B: At. Mol. Opt. Phys. 38 3517), without which Voigt profile analysis to extract impact broadening widths would not be possible. Electron densities deduced from electron impact broadening of individual lines (Griem 1967 Astrophys. J. 148 547; Watson 2006 J. Phys. B: At. Mol. Opt. Phys. 39 1889) may be used to check the significance of the constraints arising from the present analysis. The spectra of Bell et al (2000 Publ. Astron. Soc. Pac. 112 1236; 2011 Astrophys. Space Sci. 333 377; 2011 Astrophys. Space Sci. 335 451) for Orion A and W51 in the vicinity of 6.0 and 17.6 GHz are examined in this context, and also in terms of a possible role of the background ion microfield in reducing the near-elastic contributions to the electron impact broadening below the predictions of theory (Hey 2012 J. Phys. B: At. Mol. Opt. Phys. 45 065701). These spectra are analysed, subject to the constraint that calculated relative intensities of lines, arising from upper states in collisional-radiative equilibrium, should be consistent with those obtained from Voigt profile analysis. It is shown that the experimental technique yields an excellent temperature diagnostic for the H II regions. On the other hand, strong evidence is not obtained, from those spectra which satisfy the above constraint on intensity, to indicate that the electron impact broadening theory requires substantial correction. The main grounds for attempting a revision of theory to allow for the influence of the ion microfield during the scattering processes on the upper and lower states of each line thus still appear to have a stronger theoretical (Hey 2007 J. Phys. B: At. Mol. Opt. Phys. 40 4077) than experimental basis.

Partial coherence with application to the monotonicity problem of coherence involving skew information

NASA Astrophysics Data System (ADS)

Luo, Shunlong; Sun, Yuan

2017-08-01

Quantifications of coherence are intensively studied in the context of completely decoherent operations (i.e., von Neuamnn measurements, or equivalently, orthonormal bases) in recent years. Here we investigate partial coherence (i.e., coherence in the context of partially decoherent operations such as Lüders measurements). A bona fide measure of partial coherence is introduced. As an application, we address the monotonicity problem of K -coherence (a quantifier for coherence in terms of Wigner-Yanase skew information) [Girolami, Phys. Rev. Lett. 113, 170401 (2014), 10.1103/PhysRevLett.113.170401], which is introduced to realize a measure of coherence as axiomatized by Baumgratz, Cramer, and Plenio [Phys. Rev. Lett. 113, 140401 (2014), 10.1103/PhysRevLett.113.140401]. Since K -coherence fails to meet the necessary requirement of monotonicity under incoherent operations, it is desirable to remedy this monotonicity problem. We show that if we modify the original measure by taking skew information with respect to the spectral decomposition of an observable, rather than the observable itself, as a measure of coherence, then the problem disappears, and the resultant coherence measure satisfies the monotonicity. Some concrete examples are discussed and related open issues are indicated.

Near-field deformation of a liquid interface by atomic force microscopy.

PubMed

Mortagne, C; Chireux, V; Ledesma-Alonso, R; Ogier, M; Risso, F; Ondarçuhu, T; Legendre, D; Tordjeman, Ph

2017-07-01

We experiment the interaction between a liquid puddle and a spherical probe by Atomic Force Microscopy (AFM) for a probe radius R ranging from 10 nm to 30 μm. We have developed a new experimental setup by coupling an AFM with a high-speed camera and an inverted optical microscope. Interaction force-distance curves (in contact mode) and frequency shift-distance curves (in frequency modulation mode) are measured for different bulk model liquids for which the probe-liquid Hamaker constant H_{pl} is known. The experimental results, analyzed in the frame of the theoretical model developed in Phys. Rev. Lett. 108, 106104 (2012)PRLTAO0031-900710.1103/PhysRevLett.108.106104 and Phys. Rev. E 85, 061602 (2012)PLEEE81539-375510.1103/PhysRevE.85.061602, allow to determine the "jump-to-contact" critical distance d_{min} below which the liquid jumps and wets the probe. Comparison between theory and experiments shows that the probe-liquid interaction at nanoscale is controlled by the liquid interface deformation. This work shows a very good agreement between the theoretical model and the experiments and paves the way to experimental studies of liquids at the nanoscale.

Finite Forward Acceptance Angles for Single Electron Capture by ^3He^2+ Ions in He and H_2

NASA Astrophysics Data System (ADS)

Mawhorter, Rj; Greenwood, J.; Smith; Chutjian, A.

2004-05-01

Perhaps surprisingly, electron capture scattering angles of a few degrees or more are observed for slow ions impacting light targets. Gas cells must be designed with this in mind. Indeed the difference between small acceptance angle results(W.L. Nutt, et al., J. Phys. B 8), 1457 (1978) and the larger acceptance-angle studies of both Kusakabe, et al.(T. Kusakabe, et al., J. Phys. Soc. Japan 59), 1218 (1990) and our group at JPL (presented here; energy range 0.33-4.67 keV/amu) for ^3He^2+ in H2 can be ascribed to this effect. Olson and Kimura(R. E. Olson and M. Kimura, J. Phys. B 15), 4231 (1982) have modeled the problem theoretically. We use existing differential cross section data(D. Bordenave-Montesquieu and R. Dagnac, J. Phys. B 27), 543 1994) for both H_2/ D2 and ^4He targets to calculate realistic acceptance angles. The resulting small total cross section corrections provide reliable absolute results for these benchmark systems. This work was carried out at JPL/Caltech, and was supported through agreement with NASA.

Absolute Charge Exchange Cross Sections for ^3He^2+ Collisions with ^4He and H_2

NASA Astrophysics Data System (ADS)

Mawhorter, R. J.; Greenwood, J.; Smith, S. J.; Chutjian, A.

2002-05-01

The JPL charge exchange beam-line(J.B. Greenwood, et al., Phys. Rev A 63), 062707 (2001) was modified to increase the forward acceptance angle and enable the measurement of total charge-exchange cross sections for slow, light, highly-charged ion collisions with neutral targets(R. E. Olson and M. Kimura, J. Phys. B 15), 4231 (1982). Data are presented for single charge exchange cross sections for ^3He^2+ nuclei scattered by ^4He and H2 in the energy range 0.33-4.67 keV/amu. For both targets there is good agreement with Kusakabe, et al.(T. Kusakabe, et al., J. Phys. Soc. Japan 59), 1218 (1990). Angular collection is studied by a comparison with differential measurements(D. Bordenave-Montesquieu and R. Dagnac, J. Phys. B 27), 543 (1994), as well as with earlier JPL results(J.B. Greenwood, et al., Ap. J. 533), L175 (2000), ibid. 529, 605 (2000) using heavier projectiles and targets. This work was carried out at JPL/Caltech, and was supported through contract with NASA. RJM thanks the NRC for a Senior Associateship at JPL.

Exploring the free energy surface using ab initio molecular dynamics

NASA Astrophysics Data System (ADS)

Samanta, Amit; Morales, Miguel A.; Schwegler, Eric

2016-04-01

Efficient exploration of configuration space and identification of metastable structures in condensed phase systems are challenging from both computational and algorithmic perspectives. In this regard, schemes that utilize a set of pre-defined order parameters to sample the relevant parts of the configuration space [L. Maragliano and E. Vanden-Eijnden, Chem. Phys. Lett. 426, 168 (2006); J. B. Abrams and M. E. Tuckerman, J. Phys. Chem. B 112, 15742 (2008)] have proved useful. Here, we demonstrate how these order-parameter aided temperature accelerated sampling schemes can be used within the Born-Oppenheimer and the Car-Parrinello frameworks of ab initio molecular dynamics to efficiently and systematically explore free energy surfaces, and search for metastable states and reaction pathways. We have used these methods to identify the metastable structures and reaction pathways in SiO2 and Ti. In addition, we have used the string method [W. E, W. Ren, and E. Vanden-Eijnden, Phys. Rev. B 66, 052301 (2002); L. Maragliano et al., J. Chem. Phys. 125, 024106 (2006)] within the density functional theory to study the melting pathways in the high pressure cotunnite phase of SiO2 and the hexagonal closed packed to face centered cubic phase transition in Ti.

Near-field deformation of a liquid interface by atomic force microscopy

NASA Astrophysics Data System (ADS)

Mortagne, C.; Chireux, V.; Ledesma-Alonso, R.; Ogier, M.; Risso, F.; Ondarçuhu, T.; Legendre, D.; Tordjeman, Ph.

2017-07-01

We experiment the interaction between a liquid puddle and a spherical probe by Atomic Force Microscopy (AFM) for a probe radius R ranging from 10 nm to 30 μ m . We have developed a new experimental setup by coupling an AFM with a high-speed camera and an inverted optical microscope. Interaction force-distance curves (in contact mode) and frequency shift-distance curves (in frequency modulation mode) are measured for different bulk model liquids for which the probe-liquid Hamaker constant Hp l is known. The experimental results, analyzed in the frame of the theoretical model developed in Phys. Rev. Lett. 108, 106104 (2012), 10.1103/PhysRevLett.108.106104 and Phys. Rev. E 85, 061602 (2012), 10.1103/PhysRevE.85.061602, allow to determine the "jump-to-contact" critical distance dmin below which the liquid jumps and wets the probe. Comparison between theory and experiments shows that the probe-liquid interaction at nanoscale is controlled by the liquid interface deformation. This work shows a very good agreement between the theoretical model and the experiments and paves the way to experimental studies of liquids at the nanoscale.

Surface Layering Near Room Temperature in a Nonmetallic Liquid

NASA Astrophysics Data System (ADS)

Chattopadhyay, Sudeshna; Stripe, Benjamin; Shively, Patrick; Evmenenko, Geunnadi; Dutta, Pulak; Ehrlich, Steven; Mo, Haiding

2009-03-01

Oscillatory density profiles (layers) have been observed at the free surfaces of many liquid metals at and above room temperature [1]. A surface-layered state has been previously reported only in one dielectric liquid, tetrakis(2-ethylhexoxy)silane (TEHOS), and only at lower temperatures [2]. We have used x-ray reflectivity to study a molecular liquid, pentaphenyl trimethyl trisiloxane. Below T˜ 267K (well above the freezing point for this liquid), density oscillations appear at the surface. This liquid has a higher Tc (˜1200K) than TEHOS (˜950K), so that layers appear at T/Tc 0.2 in both cases. Our results indicate that surface order is a universal phenomenon in both metallic and dielectric liquids, and that the underlying physics is likely to be the same since layers always appear at T<˜0.2Tc as theoretically predicted [3] [3pt] REFERENCES: [0pt] [1]. e.g. O. M. Magnussen et al., Phys. Rev. Lett. 74, 4444 (1995) [0pt] [2]. H. Mo et al. Phys. Rev. Lett. 96, 096107 (2006); Phys. Rev. B 76, 024206 (2007) [0pt] [3]. e.g. E. Chac'on et al., Phys. Rev. Lett. 87, 166101 (2001)

Scaled experimental investigation of the moderation of auroral cyclotron emissions by background plasma

NASA Astrophysics Data System (ADS)

McConville, S. L.; Speirs, D. C.; Gillespie, K. M.; Phelps, A. D. R.; Cross, A. W.; Koepke, M. E.; Whyte, C. G.; Matheson, K.; Robertson, C. W.; Cairns, R. A.; Vorgul, I.; Bingham, R.; Kellett, B. J.; Ronald, K.

2012-04-01

Scaled laboratory experiments have been conducted at Strathclyde University [1,2] to further the understanding of the naturally occurring generation of Auroral Kilometric Radiation (AKR) in the Earth's polar magnetosphere. At an altitude of around 3200km there exists a region of partial plasma depletion (the auroral density cavity), through which electrons descend towards the Earth's atmosphere and are subject to magnetic compression. Due to conservation of the magnetic moment these electrons sacrifice parallel velocity for perpendicular velocity resulting in a horseshoe shaped distribution in velocity space which is unstable to the cyclotron maser instability [3,4]. The radiation is emitted at frequencies extending down to the local electron cyclotron frequency with a peak in emission at ~300kHz. The wave propagation is in the X-mode with powers ~109W corresponding to radiation efficiencies of 1% of the precipitated electron kinetic energy [5]. The background plasma frequency within the auroral density cavity is approximately 9kHz corresponding to an electron plasma density ~106m-3. Previous laboratory experiments at Strathclyde have studied cyclotron radiation emission from electron beams which have horseshoe shaped velocity distributions. Radiation measurements showed emissions in X-like modes with powers ~20kW and efficiencies ~1-2%, coinciding with both theoretical and numerical predictions [6-9] and magnetospheric studies. To enhance the experimental reproduction of the magnetospheric environment a Penning trap was designed and incorporated into the existing apparatus [10]. The trap was placed in the wave generation region where the magnetic field would be maintained at ~0.21T. The trap allowed a background plasma to be generated and its characteristics were studied using a plasma probe. The plasma had a significant impact on the radiation generated, introducing increasingly sporadic behaviour with increasing density. The power and efficiency of the radiation generated was lower than with no plasma present. Plasma diagnostics established the plasma frequency on the order of 150-300MHz and electron density ranging from ~1014-1015m-3, whilst the cyclotron frequency of the electrons within the Penning trap was 5.87GHz giving fce/fpe ~19-40, comparable to the auroral density cavity. Numerical simulations coinciding with this part of the experimental research program are currently being carried out using the VORPAL code. Details of these simulations will be presented in a separate paper [Speirs et al] at this meeting. McConville SL et al 2008, Plasma Phys. Control. Fusion, 50, 074010 Ronald et al 2011, Plasma Phys. Control. Fusion, 53, 074015 Bingham R and Cairns RA, 2002, Phys. Scr., T98, 160-162 Ergun RE et al, 1998, Geophys. Res. Lett., 25, 2061 Gurnett DA et al, 1974, J. Geophys. Res., 79, 4227-4238 Cairns RA et al, 2011, Phys. Plasmas, 18, 022902 Gillespie KM et al, 2008, Plasma Phys. Control. Fusion, 50, 124038 Speirs et al 2010, Phys. Plasmas, 17, 056501 Vorgul et al 2011, Phys. Plasmas, 18, 056501 McConville SL et al 2011, Plasma Phys. Control. Fusion, 53, 124020

Accurate atomic data for xenon: energy levels, oscillator strengths, and electron collision cross sections

NASA Astrophysics Data System (ADS)

Bartschat, Klaus; Zatsarinny, Oleg

2009-10-01

We have applied our recently developed fully relativistic Dirac B-spline R-matrix (DBSR) code [1] to calculate the atomic structure (energy levels and oscillator strengths) as well as electron scattering from xenon atoms. Results from a 31-state close-coupling model for the excitation function of the metastable (5p^5 6s) J=0,2 states show excellent agreement with experiment [2], thereby presenting a significant improvement over the most sophisticated previous Breit-Pauli calculations [3,4]. The same model is currently being used to calculate electron-impact excitation from the metastable J=2 state. The results will be compared with recent experimental data [5] and predictions from other theoretical models [6,7]. Our dataset is an excellent basis for modeling plasma discharges containing xenon.[0pt] [1] O. Zatsarinny and K. Bartschat, Phys. Rev. A 77 (2008) 062701.[0pt] [2] S. J. Buckman et al., J. Phys. B 16 (1983) 4219.[0pt] [3] A. N. Grum-Grzhimailo and K. Bartschat, J. Phys. B 35 (2002) 3479.[0pt] [4] M. Allan et al., Phys. Rev. A 74 (2006) 030701(R).[0pt] [5] R. O. Jung et al., Phys. Rev. A 72 (2005) 022723.[0pt] [6] R. Srivastava et al., Phys. Rev. A 74 (2006) 012715.[0pt] [7] J. Jiang et al., J. Phys. B 41 (2008) 245204.

Response to “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’” [Phys. Fluids 26, 119101 (2014)

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

Van Gorder, Robert A., E-mail: rav@knights.ucf.edu

2014-11-15

In R. A. Van Gorder, “General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation,” Phys. Fluids 26, 065105 (2014) I discussed properties of generalized vortex filaments exhibiting purely rotational motion under the low-temperature Svistunov model of the local induction approximation. Such solutions are stationary in terms of translational motion. In the Comment [N. Hietala, “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’ [Phys. Fluids 26, 065105 (2014)],” Phys. Fluids 26, 119101 (2014)], the author criticizes my paper for not including translational motion (although it wasmore » clearly stated that the filament motion was assumed rotational). As it turns out, if one is interested in studying the geometric structure of solutions (which was the point of my paper), one obtains the needed qualitative results on the structure of such solutions by studying the purely rotational case. Nevertheless, in this Response I shall discuss the vortex filaments that have both rotational and translational motions. I then briefly discuss why one might want to study such generalized rotating filament solutions, in contrast to simple the standard helical or planar examples (which are really special cases). I also discuss how one can study the time evolution of filaments which exhibit more complicated dynamics than pure translation and rotation. Doing this, one can study non-stationary solutions which initially appear purely rotational and gradually display other dynamics as the filaments evolve.« less

Findings in Ps-H scattering

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

Ray, Hasi

2006-06-15

The best three-channel projectile-inelastic close-coupling approximation (CCA) is used to study the resonances in positronium (Ps) and hydrogen (H) scattering at the energy region below the inelastic threshold. The s-wave elastic phase shifts and s-wave elastic cross sections are studied using the static-exchange, two- and three-channel projectile-inelastic CCA for both the singlet (+) and triplet (-) channels. The singlet resonances detected using different CCA schemes confirm previous predictions [Drachman and Houston, Phys. Rev. A 12, 885 (1975); Page, J. Phys. B. 9, 1111 (1976)]. We report a resonance in the triplet channel too using the present three-channel CCA scheme.

Scaling analyses of the spectral dimension in 3-dimensional causal dynamical triangulations

NASA Astrophysics Data System (ADS)

Cooperman, Joshua H.

2018-05-01

The spectral dimension measures the dimensionality of a space as witnessed by a diffusing random walker. Within the causal dynamical triangulations approach to the quantization of gravity (Ambjørn et al 2000 Phys. Rev. Lett. 85 347, 2001 Nucl. Phys. B 610 347, 1998 Nucl. Phys. B 536 407), the spectral dimension exhibits novel scale-dependent dynamics: reducing towards a value near 2 on sufficiently small scales, matching closely the topological dimension on intermediate scales, and decaying in the presence of positive curvature on sufficiently large scales (Ambjørn et al 2005 Phys. Rev. Lett. 95 171301, Ambjørn et al 2005 Phys. Rev. D 72 064014, Benedetti and Henson 2009 Phys. Rev. D 80 124036, Cooperman 2014 Phys. Rev. D 90 124053, Cooperman et al 2017 Class. Quantum Grav. 34 115008, Coumbe and Jurkiewicz 2015 J. High Energy Phys. JHEP03(2015)151, Kommu 2012 Class. Quantum Grav. 29 105003). I report the first comprehensive scaling analysis of the small-to-intermediate scale spectral dimension for the test case of the causal dynamical triangulations of 3-dimensional Einstein gravity. I find that the spectral dimension scales trivially with the diffusion constant. I find that the spectral dimension is completely finite in the infinite volume limit, and I argue that its maximal value is exactly consistent with the topological dimension of 3 in this limit. I find that the spectral dimension reduces further towards a value near 2 as this case’s bare coupling approaches its phase transition, and I present evidence against the conjecture that the bare coupling simply sets the overall scale of the quantum geometry (Ambjørn et al 2001 Phys. Rev. D 64 044011). On the basis of these findings, I advance a tentative physical explanation for the dynamical reduction of the spectral dimension observed within causal dynamical triangulations: branched polymeric quantum geometry on sufficiently small scales. My analyses should facilitate attempts to employ the spectral dimension as a physical observable with which to delineate renormalization group trajectories in the hope of taking a continuum limit of causal dynamical triangulations at a nontrivial ultraviolet fixed point (Ambjørn et al 2016 Phys. Rev. D 93 104032, 2014 Class. Quantum Grav. 31 165003, Cooperman 2016 Gen. Relativ. Gravit. 48 1, Cooperman 2016 arXiv:1604.01798, Coumbe and Jurkiewicz 2015 J. High Energy Phys. JHEP03(2015)151).

Travelling-wave amplitudes as solutions of the phase-field crystal equation

NASA Astrophysics Data System (ADS)

Nizovtseva, I. G.; Galenko, P. K.

2018-01-01

The dynamics of the diffuse interface between liquid and solid states is analysed. The diffuse interface is considered as an envelope of atomic density amplitudes as predicted by the phase-field crystal model (Elder et al. 2004 Phys. Rev. E 70, 051605 (doi:10.1103/PhysRevE.70.051605); Elder et al. 2007 Phys. Rev. B 75, 064107 (doi:10.1103/PhysRevB.75.064107)). The propagation of crystalline amplitudes into metastable liquid is described by the hyperbolic equation of an extended Allen-Cahn type (Galenko & Jou 2005 Phys. Rev. E 71, 046125 (doi:10.1103/PhysRevE.71.046125)) for which the complete set of analytical travelling-wave solutions is obtained by the method (Malfliet & Hereman 1996 Phys. Scr. 15, 563-568 (doi:10.1088/0031-8949/54/6/003); Wazwaz 2004 Appl. Math. Comput. 154, 713-723 (doi:10.1016/S0096-3003(03)00745-8)). The general solution of travelling waves is based on the function of hyperbolic tangent. Together with its set of particular solutions, the general solution is analysed within an example of specific task about the crystal front invading metastable liquid (Galenko et al. 2015 Phys. D 308, 1-10 (doi:10.1016/j.physd.2015.06.002)). The influence of the driving force on the phase-field profile, amplitude velocity and correlation length is investigated for various relaxation times of the gradient flow. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'.

Comment on ``Dynamic Peierls-Nabarro equations for elastically isotropic crystals''

NASA Astrophysics Data System (ADS)

Markenscoff, Xanthippi

2011-02-01

The paper by Pellegrini [Phys. Rev. BPRBMDO0031-899X10.1103/PhysRevB.81.024101 81, 024101 (2010)] introduces additional “distributional terms” to the displacement of the static field of a dislocation and claims that they are needed so that Weertman's equation for the steady-state motion of the Peierls-Nabarro dislocation be recovered. He also claims that the [Eshelby, Phys. Rev.PHRVAO0031-899X10.1103/PhysRev.90.248 90, 248 (1953)] solution for a moving screw is wrong, a statement with which I disagree. The same [Eshelby, Phys. Rev.PHRVAO0031-899X10.1103/PhysRev.90.248 90, 248 (1953)] solution is also obtained and used by the eminent dislocation scientists Al’shitz and Indenbom in Al’shitz [Sov. Phys. JETP 33, 1240 (1971)] that the author ignores. A key reference in the formulation of the problem as a 3D inclusion with eigenstrain is Willis [J. Mech. Phys. SolidsJMPSA80022-509610.1016/0022-5096(65)90038-4 13, 377 (1965)] who showed that, in the transient fields, the static Eshelby equivalence of dislocations to inclusions (with eigenstrain) does not hold, but only at long times when they tend to the static ones. In this Comment the author provides the fundamental physics of the behavior of a moving Volterra dislocation in nonuniform motion by showing how the singular fields near the moving core are obtained from “first principles” (without solving for the full fields). The limit to the steady-state motion of a Peierls-Nabarro dislocation is also shown how to be obtained from first principles from the Volterra one by taking the appropriate limit, without the need of the additional distributional terms that Pellegrini introduces.

Fit Point-Wise AB Initio Calculation Potential Energies to a Multi-Dimension Long-Range Model

NASA Astrophysics Data System (ADS)

Zhai, Yu; Li, Hui; Le Roy, Robert J.

2016-06-01

A potential energy surface (PES) is a fundamental tool and source of understanding for theoretical spectroscopy and for dynamical simulations. Making correct assignments for high-resolution rovibrational spectra of floppy polyatomic and van der Waals molecules often relies heavily on predictions generated from a high quality ab initio potential energy surface. Moreover, having an effective analytic model to represent such surfaces can be as important as the ab initio results themselves. For the one-dimensional potentials of diatomic molecules, the most successful such model to date is arguably the ``Morse/Long-Range'' (MLR) function developed by R. J. Le Roy and coworkers. It is very flexible, is everywhere differentiable to all orders. It incorporates correct predicted long-range behaviour, extrapolates sensibly at both large and small distances, and two of its defining parameters are always the physically meaningful well depth {D}_e and equilibrium distance r_e. Extensions of this model, called the Multi-Dimension Morse/Long-Range (MD-MLR) function, linear molecule-linear molecule systems and atom-non-linear molecule system. have been applied successfully to atom-plus-linear molecule, linear molecule-linear molecule and atom-non-linear molecule systems. However, there are several technical challenges faced in modelling the interactions of general molecule-molecule systems, such as the absence of radial minima for some relative alignments, difficulties in fitting short-range potential energies, and challenges in determining relative-orientation dependent long-range coefficients. This talk will illustrate some of these challenges and describe our ongoing work in addressing them. Mol. Phys. 105, 663 (2007); J. Chem. Phys. 131, 204309 (2009); Mol. Phys. 109, 435 (2011). Phys. Chem. Chem. Phys. 10, 4128 (2008); J. Chem. Phys. 130, 144305 (2009) J. Chem. Phys. 132, 214309 (2010) J. Chem. Phys. 140, 214309 (2010)

Efficacy and Safety of MED2005, a Topical Glyceryl Trinitrate Formulation, in the Treatment of Erectile Dysfunction: A Randomized Crossover Study.

PubMed

Ralph, David J; Eardley, Ian; Taubel, Jorg; Terrill, Paul; Holland, Tim

2018-02-01

Current treatments for erectile dysfunction (ED) have some limitations. This study evaluated the efficacy and tolerability of MED2005, a 0.2% glyceryl trinitrate topical gel, formulated into an enhanced absorption topical delivery system (DermaSys), administered on demand, in the treatment of ED. This randomized, double-blinded, placebo-controlled, phase II crossover trial involved 232 men with ED (231 treated, 230 assessed for efficacy) and their partners. After a 4-week run-in period, patients were randomized to 1 of 2 treatment sequences, MED2005-placebo or placebo-MED2005. Each treatment was given for 4 weeks, separated by a 1-week washout interval. Efficacy was assessed by the International Index of Erectile Function (IIEF), the Sexual Encounter Profile, a Global Assessment Questionnaire (GAQ), and specific questions about the onset and offset of action and treatment preferences (patients and partners). The primary outcome measure was the IIEF erectile function domain (IIEF-EF) score. Other efficacy assessments were secondary outcomes. The mean baseline IIEF-EF score was 17.1 (SD = 5.7), and this increased to 19.6 (SD = 7.5) after MED2005 treatment and 18.5 (SD = 6.7) after placebo (P = .0132). Overall, 23.1% of patients showed a clinically relevant (≥4-point) increase in IIEF-EF scores after treatment with MED2005 only compared with 14.5% who responded after MED2005 and placebo, 14.0% who responded after placebo only, and 48.4% who did not respond after either treatment (P = .0272). MED2005 also was associated with significant improvements compared with placebo in the other IIEF domains, and this was consistent with patients' and partners' responses to the GAQ. For all assessments, significant effects of MED2005 were seen primarily in patients with mild ED. The start of erection was noticed within 5 and 10 minutes in 44.2% and 69.5%, respectively, of all intercourse attempts with MED2005. Patients and partners showed significant preferences for MED2005 over placebo. The most commonly reported adverse events during MED2005 treatment were headache (patients, n = 18 [7.9%]; partners, n = 3 [1.3%]) and nasopharyngitis (patients, n = 13 [5.7%]; partners, n = 2 [0.9%]). These findings suggest that topical glyceryl trinitrate could be a useful treatment option in ED. Strengths of this study include the use of a validated outcome measure. Limitations include the use of only 1 dosage. Further studies are warranted to investigate the efficacy of topical glyceryl trinitrate to include higher doses, thereby improving clinical significance, especially in cases of moderate and severe ED. Ralph DJ, Eardley I, Taubel J, et al. Efficacy and Safety of MED2005, a Topical Glyceryl Trinitrate Formulation, in the Treatment of Erectile Dysfunction: A Randomized Crossover Study. J Sex Med 2018;15:167-175. Copyright © 2017 Futura Medical. Published by Elsevier Inc. All rights reserved.

Comprehensive analysis of the transcriptional profile of the Mediator complex across human cancer types.

PubMed

Syring, Isabella; Klümper, Niklas; Offermann, Anne; Braun, Martin; Deng, Mario; Boehm, Diana; Queisser, Angela; von Mässenhausen, Anne; Brägelmann, Johannes; Vogel, Wenzel; Schmidt, Doris; Majores, Michael; Schindler, Anne; Kristiansen, Glen; Müller, Stefan C; Ellinger, Jörg; Shaikhibrahim, Zaki; Perner, Sven

2016-04-26

The Mediator complex is a key regulator of gene transcription and several studies demonstrated altered expressions of particular subunits in diverse human diseases, especially cancer. However a systematic study deciphering the transcriptional expression of the Mediator across different cancer entities is still lacking.We therefore performed a comprehensive in silico cancer vs. benign analysis of the Mediator complex subunits (MEDs) for 20 tumor entities using Oncomine datasets. The transcriptional expression profiles across almost all cancer entities showed differentially expressed MEDs as compared to benign tissue. Differential expression of MED8 in renal cell carcinoma (RCC) and MED12 in lung cancer (LCa) were validated and further investigated by immunohistochemical staining on tissue microarrays containing large numbers of specimen. MED8 in clear cell RCC (ccRCC) associated with shorter survival and advanced TNM stage and showed higher expression in metastatic than primary tumors. In vitro, siRNA mediated MED8 knockdown significantly impaired proliferation and motility in ccRCC cell lines, hinting at a role for MED8 to serve as a novel therapeutic target in ccRCC. Taken together, our Mediator complex transcriptome proved to be a valid tool for identifying cancer-related shifts in Mediator complex composition, revealing that MEDs do exhibit cancer specific transcriptional expression profiles.

Statistical mechanical theory for steady state systems. VI. Variational principles

NASA Astrophysics Data System (ADS)

Attard, Phil

2006-12-01

Several variational principles that have been proposed for nonequilibrium systems are analyzed. These include the principle of minimum rate of entropy production due to Prigogine [Introduction to Thermodynamics of Irreversible Processes (Interscience, New York, 1967)], the principle of maximum rate of entropy production, which is common on the internet and in the natural sciences, two principles of minimum dissipation due to Onsager [Phys. Rev. 37, 405 (1931)] and to Onsager and Machlup [Phys. Rev. 91, 1505 (1953)], and the principle of maximum second entropy due to Attard [J. Chem.. Phys. 122, 154101 (2005); Phys. Chem. Chem. Phys. 8, 3585 (2006)]. The approaches of Onsager and Attard are argued to be the only viable theories. These two are related, although their physical interpretation and mathematical approximations differ. A numerical comparison with computer simulation results indicates that Attard's expression is the only accurate theory. The implications for the Langevin and other stochastic differential equations are discussed.

Assessment of the Sustainability of the Mediterranean Diet Combined with Organic Food Consumption: An Individual Behaviour Approach

PubMed Central

Seconda, Louise; Baudry, Julia; Allès, Benjamin; Hamza, Oualid; Boizot-Szantai, Christine; Soler, Louis-Georges; Galan, Pilar; Hercberg, Serge; Lairon, Denis; Kesse-Guyot, Emmanuelle

2017-01-01

Mediterranean diets are promising sustainable food models and the organic food system may provide health and environmental benefits. Combining the two models could therefore be a favourable approach for food sustainability. The aim of this study was to draw up a comparative description of four diets differing in the level of organic foods consumption and the adherence to the Mediterranean diet, using multidisciplinary indicators to assess the sustainability of these diets. Four groups of participants were defined and compared, combining the proportion of organic food in their diet (Org versus Conv) and the adherence to the Mediterranean diet (Med versus NoMed). Conv–NoMed: Conventional consumers and non-Mediterranean diet followers; Conv–Med: Conventional consumers and Mediterranean diet followers; Org–NoMed: Organic consumers and non-Mediterranean diet followers; Org–Med: Organic consumers and Mediterranean diet followers. The adherence to nutritional recommendations was higher among the Org–Med and Conv–Med groups compared to the Conv–NoMed group (using the mPNNS-GS (modified-Programme National nutrition santé guidelines score/13.5 points): 9.29 (95% confidence intervals (CI) = 9.23–9.36) and 9.30 (95% CI = 9.24–9.35) versus 8.19 (95% CI = 8.17–8.22)) respectively. The mean plant/animal protein intake ratio was 1.38 (95% CI = 1.01–1.74) for the Org–Med group versus 0.44 (95% CI = 0.28–0.60) for the Conv–NoMed group. The average cost of the diet of Org–Med participants was the highest: 11.43 €/day (95% CI = 11.34–11.52). This study highlighted the importance of promoting the Mediterranean diet combined with organic food consumption for individual health and environmental aspects but challenges with regard to the cost remain. PMID:28085096

The Mediterranean diet improves the systemic lipid and DNA oxidative damage in metabolic syndrome individuals. A randomized, controlled, trial.

PubMed

Mitjavila, Maria Teresa; Fandos, Marta; Salas-Salvadó, Jordi; Covas, María-Isabel; Borrego, Silvia; Estruch, Ramón; Lamuela-Raventós, Rosa; Corella, Dolores; Martínez-Gonzalez, Miguel Ángel; Sánchez, Julia M; Bulló, Mónica; Fitó, Montserrat; Tormos, Carmen; Cerdá, Concha; Casillas, Rosario; Moreno, Juan José; Iradi, Antonio; Zaragoza, Cristóbal; Chaves, Javier; Sáez, Guillermo T

2013-04-01

Metabolic syndrome (MetS), in which a non-classic feature is an increase in systemic oxidative biomarkers, presents a high risk of diabetes and cardiovascular disease (CVD). Adherence to the Mediterranean Diet (MedDiet) is associated with a reduced risk of MetS. However, the effect of the MedDiet on biomarkers for oxidative damage has not been assessed in MetS individuals. We have investigated the effect of the MedDiet on systemic oxidative biomarkers in MetS individuals. Randomized, controlled, parallel clinical trial in which 110 female with MetS, aged 55-80, were recruited into a large trial (PREDIMED Study) to test the efficacy of the traditional MedDiet on the primary prevention of CVD. Participants were assigned to a low-fat diet or two traditional MedDiets (MedDiet + virgin olive oil or MedDiet + nuts). Both MedDiet group participants received nutritional education and either free extra virgin olive oil for all the family (1 L/week), or free nuts (30 g/day). Diets were ad libitum. Changes in urine levels of F2-Isoprostane (F2-IP) and the DNA damage base 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) were evaluated at 1-year trial. After 1-year urinary F2-IP decreased in all groups, the decrease in MedDiet groups reaching a borderline significance versus that of the Control group. Urinary 8-oxo-dG was also reduced in all groups, with a higher decrease in both MedDiet groups versus the Control one (P < 0.001). MedDiet reduces oxidative damage to lipids and DNA in MetS individuals. Data from this study provide evidence to recommend the traditional MedDiet as a useful tool in the MetS management. Copyright © 2012 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Power of an optical Maxwell's demon in the presence of photon-number correlations

NASA Astrophysics Data System (ADS)

Shu, Angeline; Dai, Jibo; Scarani, Valerio

2017-02-01

We study how correlations affect the performance of the simulator of a Maxwell's demon demonstrated in a recent optical experiment [M. D. Vidrighin, O. Dahlsten, M. Barbieri, M. S. Kim, V. Vedral, and I. A. Walmsley, Phys. Rev. Lett. 116, 050401 (2016), 10.1103/PhysRevLett.116.050401]. The power of the demon is found to be enhanced or hindered, depending on the nature of the correlation, in close analogy to the situation faced by a thermal demon.

Effects of Solvation on One- and Two-Photon Spectra of Coumarin Derivatives: A Time-Dependent Density Functional Theory Study (Postprint)

DTIC Science & Technology

2007-01-01

2003. 15 A. Barik , S. Nath, and H. Pal, J . Chem. Phys. 119, 10202 2003. 16 A. Fisher, C. Cremer, and E. H. K. Stelzer, Appl. Opt. 34, 1989 1995...Hardened Materials Branch //Signature// TIM J . SCHUMACHER, Chief Survivability and Sensor Materials Division This...coumarin 152, 152A, 522, 153, 307, and 151. 094303-2 Nguyen, Day, and Pachter J . Chem. Phys. 126, 094303 2007 Downloaded 06 Nov 2007 to 134.131.125.49

Metastable Polymeric Nitrogen: The Ultimate Green High-Energy-Density Material

DTIC Science & Technology

2008-06-01

S. Polynitrogen. Chem. Eng. 2004, 82, 10. 2. Cromer, D. T.; Mills, R. L.; Schiferl , D.; Schwalbe, L. A. The Structure of N2 at 49 kbar and 299K...and Shock-Induced Cooling in Fluid Nitrogen at High Densities and Temperatures. Phys. Rev. Lett. 1986, 57, 2419. 10. Schiferl , D.; Buchsbaum, S...R.; Schiferl , D.; Martin, S.; Vanderborgh, C.; Mills, R. L. Optical Studies of Nitrogen to 130 GPa. Phys. Rev. Lett. 1985, 55, 1464. 12. Olijnyk, H

On boundaries of ping-pong modes in multipacting

NASA Astrophysics Data System (ADS)

Shemelin, Valery

2018-05-01

Multipactor is an avalanche multiplication of the number of electrons in radio-frequency devices due to secondary electron emission. One of the possible modes of this kind of discharge was studied in detail and was named "a ping-pong mode" in a publication by R. A. Kishek [Phys. Rev. Lett. 108, 035003 (2012) and Phys. Plasmas 20, 056702 (2013)]. In the present paper, I show that conditions of stability and cutoff limits are quite different from those derived in the cited papers.

Evidence of Nervous System Sensitization in Commonly Presenting and Persistent Painful Tendinopathies: A Systematic Review.

PubMed

Plinsinga, Melanie L; Brink, Michel S; Vicenzino, Bill; van Wilgen, C Paul

2015-11-01

Study Design Systematic review. Objectives To elucidate if there is sensitization of the nervous system in those with persistent rotator cuff (shoulder), lateral elbow, patellar, and Achilles tendinopathies. Background Tendinopathy can be difficult to treat, and persistent intractable pain and dysfunction are frequent. It is hypothesized that induction or maintenance of persistent pain in tendinopathy may be, at least in part, based on changes in the nervous system. Methods The PRISMA guidelines were followed. Relevant articles were identified through a computerized search in Embase, PubMed, and Web of Science, followed by a manual search of reference lists of retained articles. To be eligible, studies had to include quantitative sensory testing and evaluate individuals diagnosed with a persistent tendinopathy of the rotator cuff (shoulder), lateral elbow, patella, or Achilles tendon. Methodological quality assessment was evaluated with the Newcastle-Ottawa Scale. Results In total, 16 full-text articles met the criteria for inclusion, of which the majority were case-control studies with heterogeneous methodological quality. No studies on Achilles tendinopathy were found. Mechanical algometry was the predominant quantitative sensory testing used. Lowered pressure pain threshold was observed across different tendinopathies at the site of tendinopathy, as well as at other sites, the latter being suggestive of central sensitization. Conclusion Although more research on sensory abnormalities is warranted, it appears likely that there is an association between persistent tendon pain and sensitization of the nervous system. This evidence is primarily from studies of upper-limb tendinopathy, and caution should be exercised with inference to lower-limb tendinopathy. J Orthop Sports Phys Ther 2015;45(11):864-875. Epub 21 Sep 2015. doi:10.2519/jospt.2015.5895.

A Systematic Review of Electromyography Studies in Normal Shoulders to Inform Postoperative Rehabilitation Following Rotator Cuff Repair.

PubMed

Edwards, Peter K; Ebert, Jay R; Littlewood, Chris; Ackland, Tim; Wang, Allan

2017-12-01

Study Design Systematic review. Background Electromyography (EMG) has previously been used to guide postoperative rehabilitation progression following rotator cuff repair to prevent deleterious loading of early surgical repair. Objective To review the current literature investigating EMG during rehabilitation exercises in normal shoulders, and to identify exercises that meet a cut point of 15% maximal voluntary isometric contraction (MVIC) or less and are unlikely to result in excessive loading in the early postoperative stages. Methods An electronic search of MEDLINE via Ovid, Embase, CINAHL, SPORTDiscus, PubMed, and the Cochrane Library for all years up to June 2016 was performed. Studies were selected in relation to predefined selection criteria. Pooled mean MVICs were reported and classified as low (0%-15% MVIC), low to moderate (16%-20% MVIC), moderate (21%-40% MVIC), high (41%-60% MVIC), and very high (greater than 60% MVIC). Results A search identified 2159 studies. After applying the selection criteria, 20 studies were included for quality assessment, data extraction, and data synthesis. In total, 43 exercises spanning passive range of motion, active-assisted range of motion, and strengthening exercises were evaluated. Out of 13 active-assisted exercises, 9 were identified as suitable (15% MVIC or less) to load the supraspinatus and 10 as suitable to load the infraspinatus early after surgery. All exercises were placed in a theoretical-continuum model, by which general recommendations could be made for prescription in patients post rotator cuff repair. Conclusion This review identified passive and active-assisted exercises that may be appropriate in the early stages after rotator cuff repair. J Orthop Sports Phys Ther 2017;47(12):931-944. Epub 13 Jul 2017. doi:10.2519/jospt.2017.7271.

Dispersion interactions in room-temperature ionic liquids: Results from a non-empirical density functional

NASA Astrophysics Data System (ADS)

Kohanoff, Jorge; Pinilla, Carlos; Youngs, Tristan G. A.; Artacho, Emilio; Soler, José M.

2011-10-01

The role of dispersion or van de Waals (VDW) interactions in imidazolium-based room-temperature ionic liquids is studied within the framework of density functional theory, using a recently developed non-empirical functional [M. Dion, H. Rydberg, E. Schröder, D. C. Langreth, and B. I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004), 10.1103/PhysRevLett.92.246401], as efficiently implemented in the SIESTA code [G. Román-Pérez and J. M. Soler, Phys. Rev. Lett. 103, 096102 (2009), 10.1103/PhysRevLett.103.096102]. We present results for the equilibrium structure and lattice parameters of several crystalline phases, finding a general improvement with respect to both the local density (LDA) and the generalized gradient approximations (GGA). Similar to other systems characterized by VDW bonding, such as rare gas and benzene dimers as well as solid argon, equilibrium distances and volumes are consistently overestimated by ≈7%, compared to -11% within LDA and 11% within GGA. The intramolecular geometries are retained, while the intermolecular distances and orientations are significantly improved relative to LDA and GGA. The quality is superior to that achieved with tailor-made empirical VDW corrections ad hoc [M. G. Del Pópolo, C. Pinilla, and P. Ballone, J. Chem. Phys. 126, 144705 (2007), 10.1063/1.2715571]. We also analyse the performance of an optimized version of this non-empirical functional, where the screening properties of the exchange have been tuned to reproduce high-level quantum chemical calculations [J. Klimes, D. Bowler, and A. Michaelides, J. Phys.: Condens. Matter 22, 074203 (2010), 10.1088/0953-8984/22/7/074203]. The results for solids are even better with volumes and geometries reproduced within 2% of experimental data. We provide some insight into the issue of polymorphism of [bmim][Cl] crystals, and we present results for the geometry and energetics of [bmim][Tf] and [mmim][Cl] neutral and charged clusters, which validate the use of empirical force fields.

TwiMed: Twitter and PubMed Comparable Corpus of Drugs, Diseases, Symptoms, and Their Relations

PubMed Central

Miyao, Yusuke; Collier, Nigel

2017-01-01

Background Work on pharmacovigilance systems using texts from PubMed and Twitter typically target at different elements and use different annotation guidelines resulting in a scenario where there is no comparable set of documents from both Twitter and PubMed annotated in the same manner. Objective This study aimed to provide a comparable corpus of texts from PubMed and Twitter that can be used to study drug reports from these two sources of information, allowing researchers in the area of pharmacovigilance using natural language processing (NLP) to perform experiments to better understand the similarities and differences between drug reports in Twitter and PubMed. Methods We produced a corpus comprising 1000 tweets and 1000 PubMed sentences selected using the same strategy and annotated at entity level by the same experts (pharmacists) using the same set of guidelines. Results The resulting corpus, annotated by two pharmacists, comprises semantically correct annotations for a set of drugs, diseases, and symptoms. This corpus contains the annotations for 3144 entities, 2749 relations, and 5003 attributes. Conclusions We present a corpus that is unique in its characteristics as this is the first corpus for pharmacovigilance curated from Twitter messages and PubMed sentences using the same data selection and annotation strategies. We believe this corpus will be of particular interest for researchers willing to compare results from pharmacovigilance systems (eg, classifiers and named entity recognition systems) when using data from Twitter and from PubMed. We hope that given the comprehensive set of drug names and the annotated entities and relations, this corpus becomes a standard resource to compare results from different pharmacovigilance studies in the area of NLP. PMID:28468748

TwiMed: Twitter and PubMed Comparable Corpus of Drugs, Diseases, Symptoms, and Their Relations.

PubMed

Alvaro, Nestor; Miyao, Yusuke; Collier, Nigel

2017-05-03

Work on pharmacovigilance systems using texts from PubMed and Twitter typically target at different elements and use different annotation guidelines resulting in a scenario where there is no comparable set of documents from both Twitter and PubMed annotated in the same manner. This study aimed to provide a comparable corpus of texts from PubMed and Twitter that can be used to study drug reports from these two sources of information, allowing researchers in the area of pharmacovigilance using natural language processing (NLP) to perform experiments to better understand the similarities and differences between drug reports in Twitter and PubMed. We produced a corpus comprising 1000 tweets and 1000 PubMed sentences selected using the same strategy and annotated at entity level by the same experts (pharmacists) using the same set of guidelines. The resulting corpus, annotated by two pharmacists, comprises semantically correct annotations for a set of drugs, diseases, and symptoms. This corpus contains the annotations for 3144 entities, 2749 relations, and 5003 attributes. We present a corpus that is unique in its characteristics as this is the first corpus for pharmacovigilance curated from Twitter messages and PubMed sentences using the same data selection and annotation strategies. We believe this corpus will be of particular interest for researchers willing to compare results from pharmacovigilance systems (eg, classifiers and named entity recognition systems) when using data from Twitter and from PubMed. We hope that given the comprehensive set of drug names and the annotated entities and relations, this corpus becomes a standard resource to compare results from different pharmacovigilance studies in the area of NLP. ©Nestor Alvaro, Yusuke Miyao, Nigel Collier. Originally published in JMIR Public Health and Surveillance (http://publichealth.jmir.org), 03.05.2017.

Application of Four-Wave Mixing Spectroscopy in the Excitonic Region of Semiconductors.

DTIC Science & Technology

1984-03-01

dence. our data imply that the linear absorption as well as "E. Panizza , Appl. Phys. Lett. 10. 265 119671. 618 J. Appl. Phys., Vol. 53, No. 1...20, 413 (1969). 6. E. W. Van Stryland and M. A. Woodall, J. Opt. Soc. Am. 70,1612 22. E. Panizza , Appl. Phys. Left. 10, 265 (1967). (1980). 23. J. H

Experimental Test of Nonlocal Realism Using a Fiber-Based Source of Polarization-Entangled Photon Paris

DTIC Science & Technology

2008-03-25

J. F. Clauser and M. A. Horne, Phys. Rev. D 10, 526 1974. 6 A. Zeilinger , Rev. Mod. Phys. 71, S288 1999; A. Aspect, Nature London 398, 189...Jennewein, M. Zukowski, M. Aspelmeyer, and A. Zeilinger , Phys. Rev. Lett. 99, 210406 2007; C. Branciard, A. Ling, N. Gisin, C. Kurt- siefer, A. Lamas

Resolved Sideband Spectroscopy for the Detection of Weak Optical Transitions

DTIC Science & Technology

2013-08-01

Lett. 81, 317 (1998). [12] T. Baba and I. Waki , “Cooling and Mass-Analysis of Molecules Using Laser-Cooled Atoms,” Jpn. J. Appl. Phys 35, L1134 (1996...fermions,” Phys. Rev. A: At. Mol. Opt. Phys. 65, 043601 (2002). [26] T. Baba and I. Waki , “Spectral shape of in situ mass spectra of sympathetically cooled

Spatially and Spectrally Resolved Cathodoluminescence of Hot-Filament Chemical-Vapor-Deposited Diamond Particles

DTIC Science & Technology

1991-04-24

Knight, J. Appl. Phys. 67, 7019 (1990) 12. H. Kawarada, K. Nishimura, T. Ito, J. Suzuki, K. Mar, Y. Yokota and A. Hiraki , Jpn. J. Appl. Phys. 27...L683 (1988) 21 13. H. Kawarada, Y. Yokota, Y. Mori, K. Nishimura and A. Hiraki . J. Appi. Phys. 67, 983 (1990) 14. E. N. Farabaugh, A. Feldman, L. H

Weak measurement combined with quantum delayed-choice experiment and implementation in optomechanical system

NASA Astrophysics Data System (ADS)

Li, Gang; Wang, Tao; Ye, Ming-Yong; Song, He-Shan

2015-12-01

Weak measurement [Y. Aharonov, D.Z. Albert, L. Vaidman, Phys. Rev. Lett. 60, 1351 (1988); C. Simon, E.S. Polzik, Phys. Rev. A 83, 040101(R) (2011)] combined with quantum delayed-choice experiment that use Controlled Hadamard gate instead of Hadamard gate in quantum networks give rise to a surprising amplification effect, i.e., counterintuitive negative amplification effect. We show that this effect is caused by the wave and particle behaviours of the system, and it can't be explained by a semiclassical wave theory [D. Suter, Phys. Rev. A 51, 45 (1995); J.C. Howell, D.J. Starling, P.B. Dixon, P.K. Vudyasetu, A.N. Jordan, Phys. Rev. A 81, 033813 (2010); N. Brunner, A. Acín, D. Collins, N. Gisin, V. Scarani, Phys. Rev. Lett. 91, 180402 (2003)] and by the statistical feature of preselection and postselection with disturbance [C. Ferrie, J. Combes, Phys. Rev. Lett. 113, 120404 (2014)], due to the entanglement of the system and the ancilla in Controlled Hadamard gate. The generation mechanism with wave-particle duality in quantum mechanics lead us to a scheme for implementation of weak measurement in optomechanical system.

e-Phys: a suite of intracellular neurophysiology programs integrating COM (component object model) technologies.

PubMed

Nguyen, Quoc-Thang; Miledi, Ricardo

2003-09-30

Current computer programs for intracellular recordings often lack advanced data management, are usually incompatible with other applications and are also difficult to adapt to new experiments. We have addressed these shortcomings in e-Phys, a suite of electrophysiology applications for intracellular recordings. The programs in e-Phys use Component Object Model (COM) technologies available in the Microsoft Windows operating system to provide enhanced data storage, increased interoperability between e-Phys and other COM-aware applications, and easy customization of data acquisition and analysis thanks to a script-based integrated programming environment. Data files are extensible, hierarchically organized and integrated in the Windows shell by using the Structured Storage technology. Data transfers to and from other programs are facilitated by implementing the ActiveX Automation standard and distributed COM (DCOM). ActiveX Scripting allows experimenters to write their own event-driven acquisition and analysis programs in the VBScript language from within e-Phys. Scripts can reuse components available from other programs on other machines to create distributed meta-applications. This paper describes the main features of e-Phys and how this package was used to determine the effect of the atypical antipsychotic drug clozapine on synaptic transmission at the neuromuscular junction.

A revision of the gamma-evaluation concept for the comparison of dose distributions.

PubMed

Bakai, Annemarie; Alber, Markus; Nüsslin, Fridtjof

2003-11-07

A method for the quantitative four-dimensional (4D) evaluation of discrete dose data based on gradient-dependent local acceptance thresholds is presented. The method takes into account the local dose gradients of a reference distribution for critical appraisal of misalignment and collimation errors. These contribute to the maximum tolerable dose error at each evaluation point to which the local dose differences between comparison and reference data are compared. As shown, the presented concept is analogous to the gamma-concept of Low et al (1998a Med. Phys. 25 656-61) if extended to (3+1) dimensions. The pointwise dose comparisons of the reformulated concept are easier to perform and speed up the evaluation process considerably, especially for fine-grid evaluations of 3D dose distributions. The occurrences of false negative indications due to the discrete nature of the data are reduced with the method. The presented method was applied to film-measured, clinical data and compared with gamma-evaluations. 4D and 3D evaluations were performed. Comparisons prove that 4D evaluations have to be given priority, especially if complex treatment situations are verified, e.g., non-coplanar beam configurations.

GPU implementation of prior image constrained compressed sensing (PICCS)

NASA Astrophysics Data System (ADS)

Nett, Brian E.; Tang, Jie; Chen, Guang-Hong

2010-04-01

The Prior Image Constrained Compressed Sensing (PICCS) algorithm (Med. Phys. 35, pg. 660, 2008) has been applied to several computed tomography applications with both standard CT systems and flat-panel based systems designed for guiding interventional procedures and radiation therapy treatment delivery. The PICCS algorithm typically utilizes a prior image which is reconstructed via the standard Filtered Backprojection (FBP) reconstruction algorithm. The algorithm then iteratively solves for the image volume that matches the measured data, while simultaneously assuring the image is similar to the prior image. The PICCS algorithm has demonstrated utility in several applications including: improved temporal resolution reconstruction, 4D respiratory phase specific reconstructions for radiation therapy, and cardiac reconstruction from data acquired on an interventional C-arm. One disadvantage of the PICCS algorithm, just as other iterative algorithms, is the long computation times typically associated with reconstruction. In order for an algorithm to gain clinical acceptance reconstruction must be achievable in minutes rather than hours. In this work the PICCS algorithm has been implemented on the GPU in order to significantly reduce the reconstruction time of the PICCS algorithm. The Compute Unified Device Architecture (CUDA) was used in this implementation.

Anisotropic mechanical properties of zircon and the effect of radiation damage

NASA Astrophysics Data System (ADS)

Beirau, Tobias; Nix, William D.; Bismayer, Ulrich; Boatner, Lynn A.; Isaacson, Scott G.; Ewing, Rodney C.

2016-10-01

This study provides new insights into the relationship between radiation-dose-dependent structural damage due to natural U and Th impurities and the anisotropic mechanical properties (Poisson's ratio, elastic modulus and hardness) of zircon. Natural zircon samples from Sri Lanka (see Muarakami et al. in Am Mineral 76:1510-1532, 1991) and synthetic samples, covering a dose range of zero up to 6.8 × 1018 α-decays/g, have been studied by nanoindentation. Measurements along the [100] crystallographic direction and calculations, based on elastic stiffness constants determined by Özkan (J Appl Phys 47:4772-4779, 1976), revealed a general radiation-induced decrease in stiffness (~54 %) and hardness (~48 %) and an increase in the Poisson's ratio (~54 %) with increasing dose. Additional indentations on selected samples along the [001] allowed one to follow the amorphization process to the point that the mechanical properties are isotropic. This work shows that the radiation-dose-dependent changes of the mechanical properties of zircon can be directly correlated with the amorphous fraction as determined by previous investigations with local and global probes (Ríos et al. in J Phys Condens Matter 12:2401-2412, 2000a; Farnan and Salje in J Appl Phys 89:2084-2090, 2001; Zhang and Salje in J Phys Condens Matter 13:3057-3071, 2001). The excellent agreement, revealed by the different methods, indicates a large influence of structural and even local phenomena on the macroscopic mechanical properties. Therefore, this study indicates the importance of acquiring better knowledge about the mechanical long-term stability of radiation-damaged materials.

Apker Award Recipient: Renormalization-Group Study of Helium Mixtures Immersed in a Porous Medium

NASA Astrophysics Data System (ADS)

Lopatnikova, Anna

1998-03-01

Superfluidity and phase separation in ^3He-^4He mixtures immersed in aerogel are studied by renormalization-group theory. Firstly, the theory is applied to jungle-gym (non-random) aerogel.(A. Lopatnikova and A.N. Berker, Phys. Rev. B 55, 3798 (1997).) This calculation is conducted via the coupled renormalization-group mappings of interactions near and away from aerogel. Superfluidity at very low ^4He concentrations and a depressed tricritical temperature are found at the onset of superfludity. A superfluid-superfluid phase separation, terminating at an isolated critical point, is found entirely within the superfluid phase. Secondly, the theory is applied to true aerogel, which has quenched disorder at both atomic and geometric levels.(A. Lopatnikova and A.N. Berker, Phys. Rev. B 56, 11865 (1997).) This calculation is conducted via the coupled renormalization-group mappings, near and away from aerogel, of quenched probability distributions of random interactions. Random-bond effects on superfluidity onset and random-field effects on superfluid phase separation are seen. The quenched randomness causes the λ line of second-order phase transitions of superfluidity onset to reach zero temperature, in agreement with general prediction and experiments. Based on these studies, the experimentally observed(S.B. Kim, J. Ma, and M.H.W. Chan, Phys. Rev. Lett. 71, 2268 (1993); N. Mulders and M.H.W. Chan, Phys. Rev. Lett. 75, 3705 (1995).) distinctive characteristics of ^3He-^4He mixtures in aerogel are related to the aerogel properties of connectivity, tenuousness, and atomic and geometric randomness.

Investigation on the kurtosis filter and the derivation of convolutional sparse filter for impulsive signature enhancement

NASA Astrophysics Data System (ADS)

Jia, Xiaodong; Zhao, Ming; Di, Yuan; Jin, Chao; Lee, Jay

2017-01-01

Minimum Entropy Deconvolution (MED) filter, which is a non-parametric approach for impulsive signature detection, has been widely studied recently. Although the merits of the MED filter are manifold, this method tends to over highlight the dominant peaks and its performance becomes less stable when strong noise exists. In order to better understand the behavior of the MED filter, this study first investigated the mathematical fundamentals of the MED filter and then explained the reason why the MED filter tends to over highlight the dominant peaks. In order to pursue finer solutions for weak impulsive signature enhancement, the Convolutional Sparse Filter (CSF) is originally proposed in this work and the derivation of the CSF is presented in details. The superiority of the proposed CSF over the MED filter is validated by both simulated data and experimental data. The results demonstrate that CSF is an effective method for impulsive signature enhancement that could be applied in rotating machines for incipient fault detection.

Exploring one-particle orbitals in large many-body localized systems

NASA Astrophysics Data System (ADS)

Villalonga, Benjamin; Yu, Xiongjie; Luitz, David J.; Clark, Bryan K.

2018-03-01

Strong disorder in interacting quantum systems can give rise to the phenomenon of many-body localization (MBL), which defies thermalization due to the formation of an extensive number of quasilocal integrals of motion. The one-particle operator content of these integrals of motion is related to the one-particle orbitals (OPOs) of the one-particle density matrix and shows a strong signature across the MBL transition as recently pointed out by Bera et al. [Phys. Rev. Lett. 115, 046603 (2015), 10.1103/PhysRevLett.115.046603; Ann. Phys. 529, 1600356 (2017), 10.1002/andp.201600356]. We study the properties of the OPOs of many-body eigenstates of an MBL system in one dimension. Using shift-and-invert MPS, a matrix product state method to target highly excited many-body eigenstates introduced previously [Phys. Rev. Lett. 118, 017201 (2017), 10.1103/PhysRevLett.118.017201], we are able to obtain accurate results for large systems of sizes up to L =64 . We find that the OPOs drawn from eigenstates at different energy densities have high overlap and their occupations are correlated with the energy of the eigenstates. Moreover, the standard deviation of the inverse participation ratio of these orbitals is maximal at the nose of the mobility edge. Also, the OPOs decay exponentially in real space, with a correlation length that increases at low disorder. In addition, we find that the probability distribution of the strength of the large-range coupling constants of the number operators generated by the OPOs approach a log-uniform distribution at strong disorder.

Noble-metal intercalation process leading to a protected adatom in a graphene hollow site

NASA Astrophysics Data System (ADS)

Narayanan Nair, M.; Cranney, M.; Jiang, T.; Hajjar-Garreau, S.; Aubel, D.; Vonau, F.; Florentin, A.; Denys, E.; Bocquet, M.-L.; Simon, L.

2016-08-01

In previous studies, we have shown that gold deposited on a monolayer (ML) of graphene on SiC(0001) is intercalated below the ML after an annealing procedure and affects the band structure of graphene. Here we prove experimentally and theoretically that some of the gold forms a dispersed phase composed of single adatoms, being intercalated between the ML and the buffer layer and in a hollow position with respect to C atoms of the ML on top. They are freestanding and negatively charged, due to the partial screening of the electron transfer between SiC and the ML, without changing the intrinsic n-type doping of the ML. As these single atoms decouple the ML from the buffer layer, the quasiparticles of graphene are less perturbed, thus increasing their Fermi velocity. Moreover, the hollow position of the intercalated single Au atoms might lead to spin-orbit coupling in the graphene layer covering IC domains. This effect of spin-orbit coupling has been recently observed experimentally in Au-intercalated graphene on SiC(0001) [D. Marchenko, A. Varykhalov, J. Sánchez-Barriga, Th. Seyller, and O. Rader, Appl. Phys. Lett. 108, 172405 (2016), 10.1063/1.4947286] and has been theoretically predicted for heavy atoms, like thallium, in a hollow position on graphene [C. Weeks, J. Hu, J. Alicea, M. Franz, and R. Wu, Phys. Rev. X 1, 021001 (2011), 10.1103/PhysRevX.1.021001; A. Cresti, D. V. Tuan, D. Soriano, A. W. Cummings, and S. Roche, Phys. Rev. Lett. 113, 246603 (2014), 10.1103/PhysRevLett.113.246603].

Dynamics in dense hard-sphere colloidal suspensions

NASA Astrophysics Data System (ADS)

Orsi, Davide; Fluerasu, Andrei; Moussaïd, Abdellatif; Zontone, Federico; Cristofolini, Luigi; Madsen, Anders

2012-01-01

The dynamic behavior of a hard-sphere colloidal suspension was studied by x-ray photon correlation spectroscopy and small-angle x-ray scattering over a wide range of particle volume fractions. The short-time mobility of the particles was found to be smaller than that of free particles even at relatively low concentrations, showing the importance of indirect hydrodynamic interactions. Hydrodynamic functions were derived from the data, and for moderate particle volume fractions (Φ≤ 0.40) there is good agreement with earlier many-body theory calculations by Beenakker and Mazur [Physica A0378-437110.1016/0378-4371(84)90206-1 120, 349 (1984)]. Important discrepancies appear at higher concentrations, above Φ≈ 0.40, where the hydrodynamic effects are overestimated by the Beenakker-Mazur theory, but predicted accurately by an accelerated Stokesian dynamics algorithm developed by Banchio and Brady [J. Chem. Phys.0021-960610.1063/1.1571819 118, 10323 (2003)]. For the relaxation rates, good agreement was also found between the experimental data and a scaling form predicted by the mode coupling theory. In the high concentration range, with the fluid suspensions approaching the glass transition, the long-time diffusion coefficient was compared with the short-time collective diffusion coefficient to verify a scaling relation previously proposed by Segrè and Pusey [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.77.771 77, 771 (1996)]. We discuss our results in view of previous experimental attempts to validate this scaling law [L. Lurio , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.84.785 84, 785 (2000)].

Isolation of Coherent Synchrotron Emission During Relativistic Laser Plasma Interactions

NASA Astrophysics Data System (ADS)

Dromey, B.; Rykovanov, S. G.; Lewis, C. L. S.; Zepf, M.

Coherent Synchrotron Emission (CSE) from relativistic laser plasmas (Pukhov et al., Plas Phys Control Fusion 52:124039, 2010; Dromey et al., Nat Phys 8:804-808, 2012; Dromey et al., New J Phys 15:015025, 2013) has recently been identified as a unique platform for the generation of coherent extreme ultraviolet (XUV) and X-Ray radiation with clear potential for bright attosecond pulse production. Exploiting this potential requires careful selection of interaction geometry, spectral wavelength range and target characteristics to allow the generation of high fidelity single attosecond pulses. In the laboratory the first step on this road is to study the individual mechanisms driving the emission of coherent extreme ultraviolet and X-Ray radiation during laser solid interactions in isolation. Here we show how interactions can be tailored to permit the unambiguous observation of coherent synchrotron emission (CSE) and the implications of this geometry for the resulting harmonic spectrum over the duration of the interaction.

Ferromagnets without inversion symmetry - room for superconductivity?

NASA Astrophysics Data System (ADS)

Nevidomskyy, Andriy; Linder, Jacob; Sudbø, Asle

2009-03-01

Motivated by the recent discoveries of ferromagnetic and non-centrosymmetric superconductors, we present a mean-field theory [1] for a superconductor that both lacks inversion symmetry and displays ferromagnetism, a scenario which is believed to be realized in UIr under applied pressure [2]. We study the interplay between the order parameters to clarify how superconductivity is affected by the presence of ferromagnetism and spin-orbit coupling. We find that the spin-orbit coupling seems to enhance both ferromagnetism and superconductivity in both singlet and triplet channels. We discuss our results in the context of the heavy fermion superconductor UIr and analyze possible symmetries of the order parameter. [3pt] [1] J. Linder, A. H. Nevidomskyy, and A. Sudbø, Phys. Rev. B 78, 172502 (2008). [0pt] [2] T. Akazawa et al., J. Phys. Cond. Mat. 16, L29 (2004); J. Phys. Soc. Jpn. 73, 3129 (2004).

Gauge invariant perturbations of the Schwarzschild spacetime

NASA Astrophysics Data System (ADS)

Thompson, Jonathan E.; Chen, Hector; Whiting, Bernard F.

2017-09-01

Beginning with the pioneering work of Regge and Wheeler (1957 Phys. Rev. 108 1063), there have been many studies of perturbations away from the Schwarzschild spacetime background. In particular several authors Moncrief (1974 Ann. Phys. 88 323), Sachs (1964 Relativity, Groups and Topology (New York: Gordon and Breach)) and Brizuela et al (2007 Phys. Rev. D 76 024004) have investigated gauge invariant quantities of the Regge-Wheeler (RW) formalism. Steven Detweiler also investigated perturbations of Schwarzschild in his own formalism, introducing his own gauge choice which he denoted the ‘easy (EZ) gauge’, and which he was in the process of adapting for use in the second-order self-force problem. We present here a compilation of some of his working results, arising from notes for which there seems to have been no manuscript in preparation. In particular, we outline Detweiler’s formalism, list the gauge invariant quantities he used, and explain the process by which he found them.

High-informative version of nonlinear transformation of Langmuir waves to electromagnetic waves

NASA Astrophysics Data System (ADS)

Erofeev, Vasily I.; Erofeev

2014-04-01

The concept of informativeness of nonlinear plasma physical scenario is discussed. Basic principles for heightening the informativeness of plasma kinetic models are explained. Former high-informative correlation analysis of plasma kinetics (Erofeev, V. 2011 High-Informative Plasma Theory, Saarbrücken: LAP) is generalized for studies of weakly turbulent plasmas that contain fields of solenoidal plasma waves apart from former potential ones. Respective machinery of plasma kinetic modeling is applied to an analysis of fusion of Langmuir waves with transformation to electromagnetic waves. It is shown that the customary version of this phenomenon (Terashima, Y. and Yajima, N. 1963 Prog. Theor. Phys. 30, 443; Akhiezer, I. A., Danelia, I. A. and Tsintsadze, N. L. 1964 Sov. Phys. JETP 19, 208; Al'tshul', L. M. and Karpman, V. I. 1965 Sov. Phys. JETP 20, 1043) substantially distorts the picture of merging of Langmuir waves with long wavelengths (λ >~ c/ωpe ).

Parton distribution functions with QED corrections in the valon model

NASA Astrophysics Data System (ADS)

Mottaghizadeh, Marzieh; Taghavi Shahri, Fatemeh; Eslami, Parvin

2017-10-01

The parton distribution functions (PDFs) with QED corrections are obtained by solving the QCD ⊗QED DGLAP evolution equations in the framework of the "valon" model at the next-to-leading-order QCD and the leading-order QED approximations. Our results for the PDFs with QED corrections in this phenomenological model are in good agreement with the newly related CT14QED global fits code [Phys. Rev. D 93, 114015 (2016), 10.1103/PhysRevD.93.114015] and APFEL (NNPDF2.3QED) program [Comput. Phys. Commun. 185, 1647 (2014), 10.1016/j.cpc.2014.03.007] in a wide range of x =[10-5,1 ] and Q2=[0.283 ,108] GeV2 . The model calculations agree rather well with those codes. In the latter, we proposed a new method for studying the symmetry breaking of the sea quark distribution functions inside the proton.

Ab Initio Calculation of Photoionization and Inelastic Photon Scattering Spectra of He below the N=2 Threshold in a dc Electric Field

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

Mihelic, Andrej; Zitnik, Matjaz

2007-06-15

We study the Stark effect on doubly excited states of the helium atom below N=2. We present the ab initio photoionization and total inelastic photon scattering cross sections calculated with the method of complex scaling for field strengths F{<=}100 kV/cm. The calculations are compared to the measurements of the ion [Phys. Rev. Lett. 90, 133002 (2003)] and vacuum ultraviolet fluorescence yields [Phys. Rev. Lett. 96, 093001 (2006)]. For the case of photoionization and for incident photons with polarization vector P parallel to the electric field F, we confirm the propensity rule proposed by Tong and Lin [Phys. Rev. Lett. 92,more » 223003 (2004)]. Furthermore, the rule is also shown to apply for F perpendicular P and for the case of the inelastic scattering in both experimental geometries.« less

Critical points of the O(n) loop model on the martini and the 3-12 lattices

NASA Astrophysics Data System (ADS)

Ding, Chengxiang; Fu, Zhe; Guo, Wenan

2012-06-01

We derive the critical line of the O(n) loop model on the martini lattice as a function of the loop weight n basing on the critical points on the honeycomb lattice conjectured by Nienhuis [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.49.1062 49, 1062 (1982)]. In the limit n→0 we prove the connective constant μ=1.7505645579⋯ of self-avoiding walks on the martini lattice. A finite-size scaling analysis based on transfer matrix calculations is also performed. The numerical results coincide with the theoretical predictions with a very high accuracy. Using similar numerical methods, we also study the O(n) loop model on the 3-12 lattice. We obtain similarly precise agreement with the critical points given by Batchelor [J. Stat. Phys.JSTPBS0022-471510.1023/A:1023065215233 92, 1203 (1998)].

Exploring magnetized liner inertial fusion with a semi-analytic model

DOE PAGES

McBride, Ryan D.; Slutz, Stephen A.; Vesey, Roger A.; ...

2016-01-01

In this study, we explore magnetized liner inertial fusion (MagLIF) [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)] using a semi-analytic model [R. D. McBride and S. A. Slutz, Phys. Plasmas 22, 052708 (2015)]. Specifically, we present simulation results from this model that: (a) illustrate the parameter space, energetics, and overall system efficiencies of MagLIF; (b) demonstrate the dependence of radiative loss rates on the radial fraction of the fuel that is preheated; (c) explore some of the recent experimental results of the MagLIF program at Sandia National Laboratories [M. R. Gomez et al., Phys. Rev. Lett. 113,more » 155003 (2014)]; (d) highlight the experimental challenges presently facing the MagLIF program; and (e) demonstrate how increases to the preheat energy, fuel density, axial magnetic field, and drive current could affect future MagLIF performance.« less

Effect of finite container size on granular jet formation

NASA Astrophysics Data System (ADS)

von Kann, Stefan; Joubaud, Sylvain; Caballero-Robledo, Gabriel A.; Lohse, Detlef; van der Meer, Devaraj

2010-04-01

When an object is dropped into a bed of fine, loosely packed sand, a surprisingly energetic jet shoots out of the bed. In this work we study the effect that boundaries have on the granular jet formation. We did this by (i) decreasing the depth of the sand bed and (ii) reducing the container diameter to only a few ball diameters. These confinements change the behavior of the ball inside the bed, the void collapse, and the resulting jet height and shape. We map the parameter space of impact with Froude number, ambient pressure, and container dimensions as parameters. From these results we propose an explanation for the thick-thin structure of the jet reported by several groups ([J. R. Royer , Nat. Phys. 1, 164 (2005)], [G. Caballero , Phys. Rev. Lett. 99, 018001 (2007)], and [J. O. Marston , Phys. Fluids 20, 023301 (2008)]).

Exploring magnetized liner inertial fusion with a semi-analytic model

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

McBride, Ryan D.; Slutz, Stephen A.; Vesey, Roger A.

In this study, we explore magnetized liner inertial fusion (MagLIF) [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)] using a semi-analytic model [R. D. McBride and S. A. Slutz, Phys. Plasmas 22, 052708 (2015)]. Specifically, we present simulation results from this model that: (a) illustrate the parameter space, energetics, and overall system efficiencies of MagLIF; (b) demonstrate the dependence of radiative loss rates on the radial fraction of the fuel that is preheated; (c) explore some of the recent experimental results of the MagLIF program at Sandia National Laboratories [M. R. Gomez et al., Phys. Rev. Lett. 113,more » 155003 (2014)]; (d) highlight the experimental challenges presently facing the MagLIF program; and (e) demonstrate how increases to the preheat energy, fuel density, axial magnetic field, and drive current could affect future MagLIF performance.« less

Effects of polarization direction on laser-assisted free-free scattering

NASA Astrophysics Data System (ADS)

deHarak, B. A.; Kim, B. N.; Weaver, C. M.; Martin, N. L. S.; Siavashpouri, Mahsa; Nosarzewski, Benjamin

2016-06-01

This work will detail the effects of laser polarization direction (relative to the momentum transfer direction) on laser-assisted free-free scattering. Such processes play a role in the gas breakdown that occurs in electric discharges as well as providing a method for the laser heating of a plasma (Musa et al 2010 J. Phys. B: At. Mol. Opt. Phys. 43 175201, Mason 1993 Rep. Prog. Phys. 56 1275). Experimental results will be presented for electron-helium scattering in the presence of an Nd:YAG laser field (hν =1.17 eV) where the polarization direction was varied in a plane that is perpendicular to the scattering plane. To date, all of our experimental results are well described by the Kroll-Watson approximation (KWA) (Kroll and Watson 1973 Phys. Rev. A 8 804). The good agreement between our experiments and calculations using the KWA includes the case where the polarization is perpendicular to the momentum transfer direction, for which the KWA predicts vanishing cross section; other workers have found that the KWA tends to be inaccurate for cases where it predicts small cross sections (e.g. Musa et al 2010 J. Phys. B: At. Mol. Opt. Phys. 43 175201). We also present simulations of the effects that multiple scattering might have on experimental measurements. In particular, we examine conditions that are expected to be similar to those of the experiments reported by Wallbank and Holmes (Wallbank and Holmes 1993 Phys. Rev. A 48 R2515).

Orbital nodal surfaces: Topological challenges for density functionals

NASA Astrophysics Data System (ADS)

Aschebrock, Thilo; Armiento, Rickard; Kümmel, Stephan

2017-06-01

Nodal surfaces of orbitals, in particular of the highest occupied one, play a special role in Kohn-Sham density-functional theory. The exact Kohn-Sham exchange potential, for example, shows a protruding ridge along such nodal surfaces, leading to the counterintuitive feature of a potential that goes to different asymptotic limits in different directions. We show here that nodal surfaces can heavily affect the potential of semilocal density-functional approximations. For the functional derivatives of the Armiento-Kümmel (AK13) [Phys. Rev. Lett. 111, 036402 (2013), 10.1103/PhysRevLett.111.036402] and Becke88 [Phys. Rev. A 38, 3098 (1988), 10.1103/PhysRevA.38.3098] energy functionals, i.e., the corresponding semilocal exchange potentials, as well as the Becke-Johnson [J. Chem. Phys. 124, 221101 (2006), 10.1063/1.2213970] and van Leeuwen-Baerends (LB94) [Phys. Rev. A 49, 2421 (1994), 10.1103/PhysRevA.49.2421] model potentials, we explicitly demonstrate exponential divergences in the vicinity of nodal surfaces. We further point out that many other semilocal potentials have similar features. Such divergences pose a challenge for the convergence of numerical solutions of the Kohn-Sham equations. We prove that for exchange functionals of the generalized gradient approximation (GGA) form, enforcing correct asymptotic behavior of the potential or energy density necessarily leads to irregular behavior on or near orbital nodal surfaces. We formulate constraints on the GGA exchange enhancement factor for avoiding such divergences.

A study on PubMed search tag usage pattern: association rule mining of a full-day PubMed query log.

PubMed

Mosa, Abu Saleh Mohammad; Yoo, Illhoi

2013-01-09

The practice of evidence-based medicine requires efficient biomedical literature search such as PubMed/MEDLINE. Retrieval performance relies highly on the efficient use of search field tags. The purpose of this study was to analyze PubMed log data in order to understand the usage pattern of search tags by the end user in PubMed/MEDLINE search. A PubMed query log file was obtained from the National Library of Medicine containing anonymous user identification, timestamp, and query text. Inconsistent records were removed from the dataset and the search tags were extracted from the query texts. A total of 2,917,159 queries were selected for this study issued by a total of 613,061 users. The analysis of frequent co-occurrences and usage patterns of the search tags was conducted using an association mining algorithm. The percentage of search tag usage was low (11.38% of the total queries) and only 2.95% of queries contained two or more tags. Three out of four users used no search tag and about two-third of them issued less than four queries. Among the queries containing at least one tagged search term, the average number of search tags was almost half of the number of total search terms. Navigational search tags are more frequently used than informational search tags. While no strong association was observed between informational and navigational tags, six (out of 19) informational tags and six (out of 29) navigational tags showed strong associations in PubMed searches. The low percentage of search tag usage implies that PubMed/MEDLINE users do not utilize the features of PubMed/MEDLINE widely or they are not aware of such features or solely depend on the high recall focused query translation by the PubMed's Automatic Term Mapping. The users need further education and interactive search application for effective use of the search tags in order to fulfill their biomedical information needs from PubMed/MEDLINE.

Long-Term Outcomes of Patients with Lumbar Disc Herniation Treated with Percutaneous Discectomy: Comparative Study with Microendoscopic Discectomy

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

Liu Wengui; Wu Xiaotao; Guo Jinhe

We assessed the long-term outcomes of patients with lumbar disc herniation treated with percutaneous lumbar discectomy (PLD) or microendoscopic discectomy (MED). A retrospective study was performed in consecutive patients with lumbar disc herniation treated with PLD (n = 129) or MED (n = 101) in a single hospital from January 2000 to March 2002. All patients were followed up with MacNab criteria and self-evaluation questionnaires comprising the Oswestry Disability Index and Medical Outcomes Study 36-Item Short-Form Health Survey. Several statistical methods were used for analyses of the data, and a p value of <0.05 was considered to be statistically significant.more » A total of 104 patients (80.62%) with PLD and 82 patients (81.19%) with MED were eligible for analyses, with a mean follow-up period of 6.64 {+-} 0.67 years and 6.42 {+-} 0.51 years, respectively. There were no significant differences between the two groups in age, number of lesions, major symptoms and physical signs, and radiological findings. According to the MacNab criteria, 75.96% in the PLD group and 84.15% in the MED group achieved excellent or good results, respectively, this was statistically significant (p = 0.0402). With the Oswestry Disability Index questionnaires, the average scores and minimal disability, respectively, were 6.97 and 71.15% in the PLD group and 4.89 and 79.27% in the MED group. Total average scores of Medical Outcomes Study 36-Item Short-Form Health Survey were 75.88 vs. 81.86 in PLD group vs. MED group (p = 0.0582). The cost and length of hospitalization were higher or longer in MED group, a statistically significant difference (both p < 0.0001). Long-term complications were observed in two patients (2.44%) in the MED group, no such complications were observed in the PLD group. Both PLD and MED show an acceptable long-term efficacy for treatment of lumbar disc herniation. Compared with MED patients, long-term satisfaction is slightly lower in the PLD patients; complications, hospitalization duration, and costs in PLD group are also lower.« less

Integrated and implicit: how residents learn CanMEDS roles by participating in practice.

PubMed

Renting, Nienke; Raat, A N Janet; Dornan, Tim; Wenger-Trayner, Etienne; van der Wal, Martha A; Borleffs, Jan C C; Gans, Rijk O B; Jaarsma, A Debbie C

2017-09-01

Learning outcomes for residency training are defined in competency frameworks such as the CanMEDS framework, which ultimately aim to better prepare residents for their future tasks. Although residents' training relies heavily on learning through participation in the workplace under the supervision of a specialist, it remains unclear how the CanMEDS framework informs practice-based learning and daily interactions between residents and supervisors. This study aimed to explore how the CanMEDS framework informs residents' practice-based training and interactions with supervisors. Constructivist grounded theory guided iterative data collection and analyses. Data were collected by direct observations of residents and supervisors, combined with formal and field interviews. We progressively arrived at an explanatory theory by coding and interpreting the data, building provisional theories and through continuous conversations. Data analysis drew on sensitising insights from communities of practice theory, which provided this study with a social learning perspective. CanMEDS roles occurred in an integrated fashion and usually remained implicit during interactions. The language of CanMEDS was not adopted in clinical practice, which seemed to impede explicit learning interactions. The CanMEDS framework seemed only one of many factors of influence in practice-based training: patient records and other documents were highly influential in daily activities and did not always correspond with CanMEDS roles. Additionally, the position of residents seemed too peripheral to allow them to learn certain aspects of the Health Advocate and Leader roles. The CanMEDS framework did not really guide supervisors' and residents' practice or interactions. It was not explicitly used as a common language in which to talk about resident performance and roles. Therefore, the extent to which CanMEDS actually helps improve residents' learning trajectories and conversations between residents and supervisors about residents' progress remains questionable. This study highlights the fact that the reification of competency frameworks into the complexity of practice-based learning is not a straightforward exercise. © 2017 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

PREFACE: Time-resolved scanning tunnelling microscopy Time-resolved scanning tunnelling microscopy

NASA Astrophysics Data System (ADS)

Zandvliet, Harold J. W.; Lin, Nian

2010-07-01

Scanning tunnelling microscopy has revolutionized our ability to image, manipulate, and investigate solid surfaces on the length scale of individual atoms and molecules. The strength of this technique lies in its imaging capabilities, since for many scientists 'seeing is believing'. However, scanning tunnelling microscopy also suffers from a severe limitation, namely its poor time resolution. Recording a scanning tunnelling microscopy image typically requires a few tens of seconds for a conventional scanning tunnelling microscope to a fraction of a second for a specially designed fast scanning tunnelling microscope. Designing and building such a fast scanning tunnelling microscope is a formidable task in itself and therefore, only a limited number of these microscopes have been built [1]. There is, however, another alternative route to significantly enhance the time resolution of a scanning tunnelling microscope. In this alternative method, the tunnelling current is measured as a function of time with the feedback loop switched off. The time resolution is determined by the bandwidth of the IV converter rather than the cut-off frequency of the feedback electronics. Such an approach requires a stable microscope and goes, of course, at the expense of spatial information. In this issue, we have collected a set of papers that gives an impression of the current status of this rapidly emerging field [2]. One of the very first attempts to extract information from tunnel current fluctuations was reported by Tringides' group in the mid-1990s [3]. They showed that the collective diffusion coefficient can be extracted from the autocorrelation of the time-dependent tunnelling current fluctuations produced by atom motion in and out of the tunnelling junction. In general, current-time traces provide direct information on switching/conformation rates and distributions of residence times. In the case where these processes are thermally induced it is rather straightforward to map out the potential landscape of the system (often a molecule or an atom) under study [4, 5]. However, the dynamical processes might also be induced by the tunnelling process itself [6, 7]. In the field of molecular science, excited single molecule experiments have been especially performed [8]. As a nice example, we refer to the work of Sykes' group [9] on thioether molecular rotors. In addition, several groups explore the possibility of combining time-resolved scanning tunnelling microscopy with optical techniques [10, 11]. Although the majority of studies that have been performed so far focus on rather simple systems under nearly ideal and well-defined conditions, we anticipate that time-resolved scanning tunnelling microscopy can also be applied in other research areas, such as biology and soft condensed matter, where the experimental conditions are often less ideal. We hope that readers will enjoy this collection of papers and that it will trigger them to further explore the possibilities of this simple, but powerful technique. References [1] Besenbacher F, Laegsgaard E and Stengaard I 2005 Mater. Today 8 26 [2] van Houselt A and Zandvliet H J W 2010 Rev. Mod. Phys. 82 1593 [3] Tringides M C and Hupalo M 2010 J. Phys.: Condens. Matter 22 264002 [4] Ronci F, Colonna S, Cricenti A and Le Lay G 2010 J. Phys.: Condens. Matter 22 264003 [5] van Houselt A, Poelsema B and Zandvliet H J W 2010 J. Phys.: Condens. Matter 22 264004 [6] Sprodowski C, Mehlhorn M and Morgenstern K 2010 J. Phys.: Condens. Matter 22 264005 [7] Saedi A, Poelsema B and Zandvliet H J W 2010 J. Phys.: Condens. Matter 22 264007 [8] Sloan P A 2010 J. Phys.: Condens. Matter 22 264001 [9] Jewell A D, Tierney H L, Baber A E, Iski E V, Laha M M and Sykes E C H 2010 J. Phys.: Condens. Matter 22 264006 [10] Riedel D 2010 J. Phys.: Condens. Matter 22 264009 [11] Terada Y, Yoshida S, Takeuchi O and Shigekawa H 2010 J. Phys.: Condens. Matter 22 264008

Linear and nonlinear regimes of the 2-D Kelvin-Helmholtz/Tearing instability in Hall MHD.

NASA Astrophysics Data System (ADS)

Chacon, L.; Knoll, D. A.; Finn, J. M.

2002-11-01

The study to date of the magnetic field effects on the Kelvin-Helmholtz instability (KHI) within the framework of Hall MHD has been limited to configurations with uniform magnetic fields and/or with the magnetic field perpendicular to the sheared ion flow (( B_0⊥ v0 )).(E. N. Opp et al., Phys. Fluids B), 3, 885 (1990)^,(M. Fujimoto et al., J. Geophys. Res.), 96, 15725 (1991)^,(J. D. Huba, Phys. Rev. Lett.), 72, 2033 (1994) Here, we are concerned with the effects of Hall physics in configurations in which (B_0allel v0 ) and both are sheared.(L. Chacon et al, Phys. Lett. A), submitted (2002) In resistive MHD, and for this configuration, either the tearing mode instability (TMI) or the KHI instability dominates depending upon their relative strength.( R. B. Dahlburg et al., Phys. Plasmas), 4, 1213 (1997) In Hall MHD, however, Hall physics decouples the ion and electron flows in a boundary layer of thickness (d_i=c/ω_pi) (ion skin depth), within which electrons are the only magnetized species. Hence, while KHI essentially remains an ion instability, TMI becomes an electron instability. As a result, both KHI and TMI can be unstable simultaneously and interact, creating a very rich linear and nonlinear behavior. This is confirmed by a linear study of the Hall MHD equations. Nonlinearly, both saturated regimes and highly dynamic regimes (with vortex and magnetic island merging) are observed.

Study of hydrogen-molecule guests in type II clathrate hydrates using a force-matched potential model parameterised from ab initio molecular dynamics

NASA Astrophysics Data System (ADS)

Burnham, Christian J.; Futera, Zdenek; English, Niall J.

2018-03-01

The force-matching method has been applied to parameterise an empirical potential model for water-water and water-hydrogen intermolecular interactions for use in clathrate-hydrate simulations containing hydrogen guest molecules. The underlying reference simulations constituted ab initio molecular dynamics (AIMD) of clathrate hydrates with various occupations of hydrogen-molecule guests. It is shown that the resultant model is able to reproduce AIMD-derived free-energy curves for the movement of a tagged hydrogen molecule between the water cages that make up the clathrate, thus giving us confidence in the model. Furthermore, with the aid of an umbrella-sampling algorithm, we calculate barrier heights for the force-matched model, yielding the free-energy barrier for a tagged molecule to move between cages. The barrier heights are reasonably large, being on the order of 30 kJ/mol, and are consistent with our previous studies with empirical models [C. J. Burnham and N. J. English, J. Phys. Chem. C 120, 16561 (2016) and C. J. Burnham et al., Phys. Chem. Chem. Phys. 19, 717 (2017)]. Our results are in opposition to the literature, which claims that this system may have very low barrier heights. We also compare results to that using the more ad hoc empirical model of Alavi et al. [J. Chem. Phys. 123, 024507 (2005)] and find that this model does very well when judged against the force-matched and ab initio simulation data.

Review of high pressure phases of calcium by first-principles calculations

NASA Astrophysics Data System (ADS)

Ishikawa, T.; Nagara, H.; Suzuki, N.; Tsuchiya, J.; Tsuchiya, T.

2010-03-01

We review high pressure phases of calcium which have obtained by recent experimental and first-principles studies. In this study, we investigated the face-centered cubic (fcc) structure, the body-centered cubic (bcc) structure, the simple cubic (sc) structure, a tetragonal P43212 [Ishikawa T et al. 2008 Phys. Rev. B 77 020101(R)], an orthorhombic Cmca [Ishikawa T et al. 2008 Phys. Rev. B 77 020101(R)], an orthorhombic Cmcm [Teweldeberhan A M and Bonev S A 2008 Phys. Rev. B 78 140101(R)], an orthorhombic Pnma [Yao Y et al. 2008 Phys. Rev. B 78 054506] and a tetragonal I4/mcm(00) [Arapan S et al. 2008 Proc. Natl. Acad. Sci. USA 105 20627]. We compared the enthalpies among the structures up to 200 GPa and theoretically determined the phase diagram of calcium. The sequence of the structural transitions is fcc (0- 3.5 GPa) → bcc (3.5 - 35.7 GPa) → Cmcm (35.7- 52GPa) → P43212 (52-109 GPa) → Cmca (109-117.4GPa) → Pnma (117.4-134.6GPa) → I4/mcm(00) (134.6 GPa -). The sc phase is experimentally observed in the pressure range from 32 to 113 GPa but, in our calculation, there is no pressure region where the sc phase is the most stable. In addition, we found that the enthalpy of the hexagonal close-packed (hcp) structure is lower than that of I4/mcm(00) above 495 GPa.

Direct Observation of Zitterbewegung in a Bose Einstein Condensate

DTIC Science & Technology

2013-07-03

Cremer S 1970 Physica 50 224–40 [3] Schliemann J, Loss D and Westervelt R M 2005 Phys. Rev. Lett. 94 206801 [4] Zawadzki W and Rusin T M 2011 J. Phys...Condens. Matter 23 143201 [5] Katsnelson M I, Novoselov K S and Geim A K 2006 Nature Phys. 2 620–5 [6] Ruostekoski J, Dunne G V and Javanainen J 2002

Extraction of Radiative and Nonradiative Rates in Sb Based Midwave Infrared Lasers Using a Novel Approach

DTIC Science & Technology

2008-03-18

Dawson,2 Sanjay Krishna ,2 and L. A. Vern Schlie3 1Boeing LTS, Albuquerque, New Mexico 87117, USA 2Center for High Technology Materials, University of...Vengurlekar, Phys. Rev. B 65, 045312 2002. 16 A. Lobad and L. A. Vern Schlie, J. Appl. Phys. 95, 97 2004. 17 A. Lobad and L. A. Vern Schlie, J. Appl. Phys

An Examination of Models of Relaxation in Complex Systems. I. Continuous Time Random Walk (CTRW) Models.

DTIC Science & Technology

1986-02-04

Laberge , Phys. Chem. Glasses 14, 122 (1973); F.S. Howell, R. Bose, P.B. Macedo and C.T. Moynihan, J. Phys. Chem. 78, 639 (1974). 30. K.L. Ngai, R.W...J.R. Stevens , J. Polym. Sci.: Polym. Phys. Ed. 17, 1547 (1979); 21, 605 (1983). 41. For Polyethyl acrylate (PEA) see G. Williams and D.C. Watts in

Optical Excitation Effects on Spin-Noise Spectroscopy in Semiconductors

DTIC Science & Technology

2011-04-01

Phys. JETP 33, 1053 (1971). 28G. L. Bir, A. G. Aronov, and G. E. Pikus, Sov. Phys. JETP 42, 705 (1976). 29R. I. Dzhioev, K. V. Kavokin, V. L. Korenev , M...W. Kim, Phys. Rev. B 66, 035207 (2002). 31R. I. Dzhioev, B. P. Zakharchenya, V. L. Korenev , D. Gammon, and D. S. Katzer, JETP Lett. 74, 182 (2001). 155204-7

Annual Gaseous Electronics Conference (44TH) Held in Albuquerque, New Mexico on 22-25 October 1991

DTIC Science & Technology

1992-05-01

Phys. Rev. A 38, 2471 (1988); J. E. Lawler et al., Phys. Rev. A 43, 4427 1991). T. J. Sommerer et al., Phys. Rev. A39, 6356 (1989). EA-2 Diagnostics and...Charged Ions with a Metal Surface.* F.W. MEYER, S.H. OVERBURY, CC. HAVENER, PA. ZEULMANS VAN EMMICHOVEN, and D.M. ZEHNER, ORNL -- Projectile K-Auger

Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum

DTIC Science & Technology

1988-12-31

W. Holber, D. Gaines, C. F. Yu, R. M. Osgood, "Laser Desorption of Polymer in a Plasma Reactor," Appl. Phys. Lett. 52, 11 (1988). vii G. V. Treyz, R...and C. Wittig, Chem. Phys. Lett. 67, 48 (1979). 5 P.B. Beeken , E.A. Hanson, and G.W. Flynn, J. Chem. Phys. 78, 5892 (1983). 6 M.C. Heaven, AFOSR Report

Differential diagnostic perspectives provided by en face microscopic examination of articular surface defects.

PubMed

Rothschild, Bruce M

2018-03-01

Surface defects have a central position in diagnosis of articular pathology. Recognizing the limitations of standard radiologic techniques and those imposed by positioning and averaging artifacts on CT evaluation, direct visualization of surface defects was pursued to identify disease characteristics that would facilitate interpretation of radiologic findings. Epi-illumination surface microscopy was utilized to examine macroscopically recognized articular surface defects in individuals in the Hamann-Todd, Terry, and Huntington human skeletal collections with previously verified diagnoses of rheumatoid arthritis, spondyloarthropathy, juvenile inflammatory arthritis (JIA), calcium pyrophosphate deposition disease (CPPD), gout, metastatic cancer, multiple myeloma, septic arthritis, tuberculosis, fungal arthritis, histiocytosis and sickle cell anemia (Rothschild and Rothschild Clin Infect Dis 20(5):1402-1408, 1995; Rothschild et al. Amer J Phys Anthropol 82(4):441-449, 1990; Rothschild and Rothschild Amer J Phys Anthropol 96(4):357-563, 1995; Rothschild and Woods Clin Exp Rheumatol 10(2):117-122, 1992; Barrett and Keat Radiographics 24(6):1679-1691, 2004; Rothschild and Heathcote Amer J Phys Anthropol 98(4):519-525, 1995; Rothschild and Woods Am J Phys Anthropol 85:25-34, 1991; Hershkovitz et al. Amer J Phys Anthropol 106(1):47-60, 1998; Winland et al. Amer J Phys Anthropol 24:S243, 1997; Rothschild et al. Clin Exp Rheumatol 10(6):557-564, 1992; Rothschild and Martin , 2006; Rothschild et al. Amer J Phys Anthropol 102(2):249-264, 1997). Observed alterations were compared with standard radiographs. Fronts of resorption distinguished inflammatory arthritis from those caused by the other disorders studied. Multiple myeloma, fungal disease, and gout are expansile character; the latter accompanied by reactive new bone formation more prominent than that noted with spondyloarthropathy and JIA. Those were clearly distinguished from the crumbling alterations found with CPPD. Histiocytosis had a unique crenulated appearance, while nodules were prominent with syphilis. Defects in sickle cell anemia had ivory fragments at their base. These findings provided explanation for radiologic observations. Direct surface microscopy revealed characteristics apparently pathognomonic for specific disorders and facilitated distinguishing among them. The technique provides visualization an order of magnitude greater than that available with clinical radiologic techniques and identifies new characteristics which should facilitate clinical diagnoses. This demonstrates that there would be value to the development of higher resolution, clinically applicable imaging techniques.

Combining tissue-phantom ratios to provide a beam-quality specifier for flattening filter free photon beams

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

Dalaryd, Mårten, E-mail: Marten.Dalaryd@med.lu.se; Knöös, Tommy; Ceberg, Crister

Purpose: There are currently several commercially available radiotherapy treatment units without a flattening filter in the beam line. Unflattened photon beams have an energy and lateral fluence distribution that is different from conventional beams and, thus, their attenuation properties differ. As a consequence, for flattening filter free (FFF) beams, the relationship between the beam-quality specifier TPR{sub 20,10} and the Spencer–Attix restricted water-to-air mass collision stopping-power ratios, (L{sup -}/ρ){sub air}{sup water}, may have to be refined in order to be used with equivalent accuracy as for beams with a flattening filter. The purpose of this work was twofold. First, to studymore » the relationship between TPR{sub 20,10} and (L{sup -}/ρ){sub air}{sup water} for FFF beams, where the flattening filter has been replaced by a metal plate as in most clinical FFF beams. Second, to investigate the potential of increasing the accuracy in determining (L{sup -}/ρ){sub air}{sup water} by adding another beam-quality metric, TPR{sub 10,5}. The relationship between (L{sup -}/ρ){sub air}{sup water} and %dd(10){sub x} for beams with and without a flattening filter was also included in this study. Methods: A total of 24 realistic photon beams (10 with and 14 without a flattening filter) from three different treatment units have been used to calculate (L{sup -}/ρ){sub air}{sup water}, TPR{sub 20,10}, and TPR{sub 10,5} using the EGSnrc Monte Carlo package. The relationship between (L{sup -}/ρ){sub air}{sup water} and the dual beam-quality specifier TPR{sub 20,10} and TPR{sub 10,5} was described by a simple bilinear equation. The relationship between the photon beam-quality specifier %dd(10){sub x} used in the AAPM’s TG-51 dosimetry protocol and (L{sup -}/ρ){sub air}{sup water} was also investigated for the beams used in this study, by calculating the photon component of the percentage depth dose at 10 cm depth with SSD 100 cm. Results: The calculated (L{sup -}/ρ){sub air}{sup water} for beams without a flattening filter was 0.3% lower, on average, than for beams with a flattening filter and comparable TPR{sub 20,10}. Using the relationship in IAEA, TRS-398 resulted in a root mean square deviation (RMSD) of 0.0028 with a maximum deviation of 0.0043 (0.39%) from Monte Carlo calculated values. For all beams in this study, the RMSD between the proposed model and the Monte Carlo calculated values was 0.0006 with a maximum deviation of 0.0013 (0.1%). Using an earlier proposed relationship [Xiong and Rogers, Med. Phys. 35, 2104–2109 (2008)] between %dd(10){sub x} and (L{sup -}/ρ){sub air}{sup water} gave a RMSD of 0.0018 with a maximum deviation of 0.0029 (0.26%) for all beams in this study (compared to RMSD 0.0015 and a maximum deviation of 0.0048 (0.47%) for the relationship used in AAPM TG-51 published by Almond et al. [Med. Phys. 26, 1847–1870 (1999)]). Conclusions: Using TPR{sub 20,10} as a beam-quality specifier, for the flattening filter free beams used in this study, gave a maximum difference of 0.39% between (L{sup -}/ρ){sub air}{sup water} predicted using IAEA TRS-398 and Monte Carlo calculations. An additional parameter for determining (L{sup -}/ρ){sub air}{sup water} has been presented. This parameter is easy to measure; it requires only an additional dose measurement at 5 cm depth with SSD 95 cm, and provides information for accurate determination of the (L{sup -}/ρ){sub air}{sup water} ratio for beams both with and without a flattening filter at the investigated energies.« less

Subtype-Specific Tumor-Associated Fibroblasts Contribute to the Pathogenesis of Uterine Leiomyoma.

PubMed

Wu, Xin; Serna, Vanida A; Thomas, Justin; Qiang, Wenan; Blumenfeld, Michael L; Kurita, Takeshi

2017-12-15

Recent genomic studies have identified subtypes of uterine leiomyoma (LM) with distinctive genetic alterations. Here, we report the elucidation of the biological characteristics of the two most prevalent uterine leiomyoma subtypes, MED12-mutant (MED12-LM) and HMGA2-overexpressing (HMGA2-LM) uterine leiomyomas. Because each tumor carries only one genetic alteration, both subtypes are considered to be monoclonal. Approximately 90% of cells in HMGA2-uterine leiomyoma were smooth muscle cells (SMC) with HMGA2 overexpression. In contrast, MED12-LM consisted of similar numbers of SMC and non-SMC, which were mostly tumor-associated fibroblasts (TAF). Paradoxically, TAF carried no mutations in MED12, suggesting an interaction between SMC and TAF to coordinate their growth. The higher amount of extracellular matrix in MED12-LM than HMGA2-LM was partially due to the high concentration of collagen-producing TAF. SMC growth in a xenograft assay was driven by progesterone in both uterine leiomyoma subtypes. In contrast, TAF in MED12-LM proliferated in response to estradiol, whereas progesterone had no effect. The high concentration of estrogen-responsive TAF in MED12-LM explains the inconsistent discoveries between in vivo and in vitro studies on the mitogenic effect of estrogen and raises questions regarding the accuracy of previous studies utilizing MED12-LM cell culture. In addition, the differential effects of estradiol and progesterone on these uterine leiomyoma subtypes emphasize the importance of subtypes and genotypes in designing nonsurgical therapeutic strategies for uterine leiomyoma. Cancer Res; 77(24); 6891-901. ©2017 AACR . ©2017 American Association for Cancer Research.

Automated diagnosis of prostate cancer in multi-parametric MRI based on multimodal convolutional neural networks

NASA Astrophysics Data System (ADS)

Le, Minh Hung; Chen, Jingyu; Wang, Liang; Wang, Zhiwei; Liu, Wenyu; (Tim Cheng, Kwang-Ting; Yang, Xin

2017-08-01

Automated methods for prostate cancer (PCa) diagnosis in multi-parametric magnetic resonance imaging (MP-MRIs) are critical for alleviating requirements for interpretation of radiographs while helping to improve diagnostic accuracy (Artan et al 2010 IEEE Trans. Image Process. 19 2444-55, Litjens et al 2014 IEEE Trans. Med. Imaging 33 1083-92, Liu et al 2013 SPIE Medical Imaging (International Society for Optics and Photonics) p 86701G, Moradi et al 2012 J. Magn. Reson. Imaging 35 1403-13, Niaf et al 2014 IEEE Trans. Image Process. 23 979-91, Niaf et al 2012 Phys. Med. Biol. 57 3833, Peng et al 2013a SPIE Medical Imaging (International Society for Optics and Photonics) p 86701H, Peng et al 2013b Radiology 267 787-96, Wang et al 2014 BioMed. Res. Int. 2014). This paper presents an automated method based on multimodal convolutional neural networks (CNNs) for two PCa diagnostic tasks: (1) distinguishing between cancerous and noncancerous tissues and (2) distinguishing between clinically significant (CS) and indolent PCa. Specifically, our multimodal CNNs effectively fuse apparent diffusion coefficients (ADCs) and T2-weighted MP-MRI images (T2WIs). To effectively fuse ADCs and T2WIs we design a new similarity loss function to enforce consistent features being extracted from both ADCs and T2WIs. The similarity loss is combined with the conventional classification loss functions and integrated into the back-propagation procedure of CNN training. The similarity loss enables better fusion results than existing methods as the feature learning processes of both modalities are mutually guided, jointly facilitating CNN to ‘see’ the true visual patterns of PCa. The classification results of multimodal CNNs are further combined with the results based on handcrafted features using a support vector machine classifier. To achieve a satisfactory accuracy for clinical use, we comprehensively investigate three critical factors which could greatly affect the performance of our multimodal CNNs but have not been carefully studied previously. (1) Given limited training data, how can these be augmented in sufficient numbers and variety for fine-tuning deep CNN networks for PCa diagnosis? (2) How can multimodal MP-MRI information be effectively combined in CNNs? (3) What is the impact of different CNN architectures on the accuracy of PCa diagnosis? Experimental results on extensive clinical data from 364 patients with a total of 463 PCa lesions and 450 identified noncancerous image patches demonstrate that our system can achieve a sensitivity of 89.85% and a specificity of 95.83% for distinguishing cancer from noncancerous tissues and a sensitivity of 100% and a specificity of 76.92% for distinguishing indolent PCa from CS PCa. This result is significantly superior to the state-of-the-art method relying on handcrafted features.

Coherent neutrinoproduction of photons and pions in a chiral effective field theory for nuclei

NASA Astrophysics Data System (ADS)

Zhang, Xilin; Serot, Brian D.

2012-09-01

Background: The neutrinoproduction of photons and pions from nucleons and nuclei is relevant to the background analysis in neutrino-oscillation experiments [for example, the MiniBooNE; MiniBooNE Collaboration, A. A. Aquilar-Arevalo , Phys. Rev. Lett.0031-900710.1103/PhysRevLett.100.032301 100, 032301 (2008)]. The production from nucleons and incoherent production with Eν⩽0.5GeV have been studied in B. D. Serot and X. Zhang, Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.86.015501 86, 015501 (2012); and X. Zhang and B. D. Serot, Phys. Rev. C1110-865710.1103/PhysRevC.86.035502 86, 035502 (2012).Purpose: Study coherent productions with Eν⩽0.5GeV. Also address the contributions of two contact terms in neutral current (NC) photon production that are partially related to the proposed anomalous ω(ρ), Z boson, and photon interactions.Methods: We work in the framework of a Lorentz-covariant effective field theory (EFT), which contains nucleons, pions, the Δ (1232) (Δs), isoscalar scalar (σ) and vector (ω) fields, and isovector vector (ρ) fields, and incorporates a nonlinear realization of (approximate) SU(2)L⊗SU(2)R chiral symmetry. A revised version of the so-called “optimal approximation” is applied, where one-nucleon interaction amplitude is factorized out and the medium-modifications and pion wave function distortion are included. The calculation is tested against the coherent pion photoproduction data.Results: The computation shows an agreement with the pion photoproduction data, although precisely determining the Δ modification is entangled with one mentioned contact term. The uncertainty in the Δ modification leads to uncertainties in both pion and photon neutrinoproductions. In addition, the contact term plays a significant role in NC photon production.Conclusions: First, the contact term increases NC photon production by ˜10% assuming a reasonable range of the contact coupling, which however seems not significant enough to explain the MiniBooNE excess. A high energy computation is needed to gain a firm conclusion and will be presented elsewhere. Second, the behavior of coherent neutrinoproductions computed here is significantly different from the expectation at high energy by ignoring the vector current contribution.

Comment on "Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices"

NASA Astrophysics Data System (ADS)

Piris, Mario; Pernal, Katarzyna

2017-10-01

van Dam [Phys. Rev. A 93, 052512 (2016), 10.1103/PhysRevA.93.052512] claims that the one-particle reduced density matrix (1RDM) of an interacting system can be represented by means of a single-determinant wave function of fictitious noninteracting particles. van Dam [Phys. Rev. A 93, 052512 (2016), 10.1103/PhysRevA.93.052512] introduced orbitals within a mean-field framework that produce energy levels similar to Hartree-Fock orbital energies, therefore he also claims that conventional analyses based on Koopmans' theorem are possible in 1RDM functional theory. In this Comment, we demonstrate that both claims are unfounded.

Devil's staircases and continued fractions in Josephson junctions

NASA Astrophysics Data System (ADS)

Shukrinov, Yu. M.; Medvedeva, S. Yu.; Botha, A. E.; Kolahchi, M. R.; Irie, A.

2013-12-01

Detailed numerical simulations of the IV characteristics of a Josephson junction under external electromagnetic radiation show the devil's staircase within different bias current intervals. We have found that the observed steps form very precisely continued fractions. Increase of the amplitude of the radiation shifts the devil's staircase to higher Shapiro steps. An algorithm for the appearance and detection of subharmonics with increasing radiation amplitude is proposed. We demonstrate that the subharmonic steps registered in the well-known experiments by Dayem and Wiegand [Phys. Rev. 155, 419 (1967), 10.1103/PhysRev.155.419] and Clarke [Phys. Rev. B 4, 2963 (1971), 10.1103/PhysRevB.4.2963] also form continued fractions.

Classical capacity of Gaussian thermal memory channels

NASA Astrophysics Data System (ADS)

De Palma, G.; Mari, A.; Giovannetti, V.

2014-10-01

The classical capacity of phase-invariant Gaussian channels has been recently determined under the assumption that such channels are memoryless. In this work we generalize this result by deriving the classical capacity of a model of quantum memory channel, in which the output states depend on the previous input states. In particular we extend the analysis of Lupo et al. [Phys. Rev. Lett. 104, 030501 (2010), 10.1103/PhysRevLett.104.030501 and Phys. Rev. A 82, 032312 (2010), 10.1103/PhysRevA.82.032312] from quantum limited channels to thermal attenuators and thermal amplifiers. Our result applies in many situations in which the physical communication channel is affected by nonzero memory and by thermal noise.

Comment on "Modified quantum-speed-limit bounds for open quantum dynamics in quantum channels"

NASA Astrophysics Data System (ADS)

Mirkin, Nicolás; Toscano, Fabricio; Wisniacki, Diego A.

2018-04-01

In a recent paper [Phys. Rev. A 95, 052118 (2017), 10.1103/PhysRevA.95.052118], the authors claim that our criticism, in Phys. Rev. A 94, 052125 (2016), 10.1103/PhysRevA.94.052125, to some quantum speed limit bounds for open quantum dynamics that appeared recently in literature are invalid. According to the authors, the problem with our analysis would be generated by an artifact of the finite-precision numerical calculations. We analytically show here that it is not possible to have any inconsistency associated with the numerical precision of calculations. Therefore, our criticism of the quantum speed limit bounds continues to be valid.

Enhancing search efficiency by means of a search filter for finding all studies on animal experimentation in PubMed

PubMed Central

Hooijmans, Carlijn R; Tillema, Alice; Leenaars, Marlies; Ritskes-Hoitinga, Merel

2010-01-01

Collecting and analysing all available literature before starting an animal experiment is important and it is indispensable when writing a systematic review (SR) of animal research. Writing such review prevents unnecessary duplication of animal studies and thus unnecessary animal use (Reduction). One of the factors currently impeding the production of ‘high-quality’ SRs in laboratory animal science is the fact that searching for all available literature concerning animal experimentation is rather difficult. In order to diminish these difficulties, we developed a search filter for PubMed to detect all publications concerning animal studies. This filter was compared with the method most frequently used, the PubMed Limit: Animals, and validated further by performing two PubMed topic searches. Our filter performs much better than the PubMed limit: it retrieves, on average, 7% more records. Other important advantages of our filter are that it also finds the most recent records and that it is easy to use. All in all, by using our search filter in PubMed, all available literature concerning animal studies on a specific topic can easily be found and assessed, which will help in increasing the scientific quality and thereby the ethical validity of animal experiments. PMID:20551243

Enhancing search efficiency by means of a search filter for finding all studies on animal experimentation in PubMed.

PubMed

Hooijmans, Carlijn R; Tillema, Alice; Leenaars, Marlies; Ritskes-Hoitinga, Merel

2010-07-01

Collecting and analysing all available literature before starting an animal experiment is important and it is indispensable when writing a systematic review (SR) of animal research. Writing such review prevents unnecessary duplication of animal studies and thus unnecessary animal use (Reduction). One of the factors currently impeding the production of 'high-quality' SRs in laboratory animal science is the fact that searching for all available literature concerning animal experimentation is rather difficult. In order to diminish these difficulties, we developed a search filter for PubMed to detect all publications concerning animal studies. This filter was compared with the method most frequently used, the PubMed Limit: Animals, and validated further by performing two PubMed topic searches. Our filter performs much better than the PubMed limit: it retrieves, on average, 7% more records. Other important advantages of our filter are that it also finds the most recent records and that it is easy to use. All in all, by using our search filter in PubMed, all available literature concerning animal studies on a specific topic can easily be found and assessed, which will help in increasing the scientific quality and thereby the ethical validity of animal experiments.

The Rovibronic Spectra of the Cyclopentadienyl Radical

NASA Astrophysics Data System (ADS)

Sharma, Ketan; Miller, Terry A.; Stanton, John F.; Nesbitt, David

2017-06-01

Cyclopentadienyl (Cp) radical has been subject to numerous studies for the greater part of half a century. Experimental work has involved photo-electron spectroscopy, laser induced fluorescence excitation and emission, infrared absorption spectroscopy, and recently rotationally resolved spectra in the CH stretch region taken at JILA. Even more theoretical works appear in the literature, but substantial advances in computation have occurred since their completion. Cp's highly symmetric (D_{5h}) structure and doubly degenerate electronic ground (˜{X}^2E_1^{''}), which is subject to linear Jahn-Teller distortion, have been a great motivation for work on it. We have commenced new computational work to obtain a broad understanding of the electronic, vibrational, and rotational, i.e. rovibronic, structure of the Cp radical as revealed by its spectra, with particular emphasis on the new infrared spectra. The goal is to guide experiments and their analyses and reconcile results from spectroscopy and quantum chemistry calculations. T. Ichino, et al. J. Chem. Phys. 129, 084310 (2008) L. Yu, S. C. Foster, J. M. Williamson, M. C. Heaven and T. A. Miller J. Phys. Chem. 92, 4263 (1988) B. E. Applegate, A. J. Bezant and T. A. Miller J. Chem. Phys 114, 4869 (2001) D. Leicht, M. Kaufmann, G. Schwaab, and M. Havenith J. Chem. Phys. 145, 7 (2016), 074304.

Response to "Comment on `Water-processed carbon nanotube/graphene hybrids with enhanced field emission properties'" [AIP Advances 8, 039101 (2018)

NASA Astrophysics Data System (ADS)

Song, Meng; Xu, Peng; Song, Yenan; Wang, Xu; Li, Zhenhua; Shang, Xuefu; Wu, Huizhen; Zhao, Pei; Wang, Miao

2018-03-01

In this response, we explain the points mentioned by R. Rani and R. Bhatia in their Comment for our previous paper [AIP Advances 5, 097130 (2015)], that the high value of β obtained in Song et al. [AIP Advances 5, 097130 (2015)] is misleading because it does not corroborate with the obtained Jmax, and the obtained value of Jmax is "low" in the mentioned study as compared to the reported values [J. Appl. Phys. 111, 044307 (2012) & Appl. Phys. Lett. 102, 033102 (2013)]. For the high value of β, the obtained current Jmax is corroborated but such high value is mainly due to the multistage effect when CNTs are deposited on the rough surface of reduced graphene. For the "low" Jmax, although this is true when compared with Sameera et al. [J. Appl. Phys. 111, 044307 (2012) and Appl. Phys. Lett. 102, 033102 (2013)], but we believe that our value is a generally common value when compared with other reports [Diam. Relat. Mater. 47, 1 (2014); J. Alloys Compd. 610, 659 (2014); J. Nanomater. 2013, 5239 (2013)] using the similar method as described in our paper. Therefore, the conclusions from the experimental results on field emission performance of CNT/graphene composite materials in our paper are reliable.

Minimizing stellarator turbulent transport by geometric optimization

NASA Astrophysics Data System (ADS)

Mynick, H. E.

2010-11-01

Up to now, a transport optimized stellarator has meant one optimized to minimize neoclassical transport,ootnotetextH.E. Mynick, Phys. Plasmas 13, 058102 (2006). while the task of also mitigating turbulent transport, usually the dominant transport channel in such designs, has not been addressed, due to the complexity of plasma turbulence in stellarators. However, with the advent of gyrokinetic codes valid for 3D geometries such as GENE,ootnotetextF. Jenko, W. Dorland, M. Kotschenreuther, B.N. Rogers, Phys. Plasmas 7, 1904 (2000). and stellarator optimization codes such as STELLOPT,ootnotetextA. Reiman, G. Fu, S. Hirshman, L. Ku, et al, Plasma Phys. Control. Fusion 41 B273 (1999). designing stellarators to also reduce turbulent transport has become a realistic possibility. We have been using GENE to characterize the dependence of turbulent transport on stellarator geometry,ootnotetextH.E Mynick, P.A. Xanthopoulos, A.H. Boozer, Phys.Plasmas 16 110702 (2009). and to identify key geometric quantities which control the transport level. From the information obtained from these GENE studies, we are developing proxy functions which approximate the level of turbulent transport one may expect in a machine of a given geometry, and have extended STELLOPT to use these in its cost function, obtaining stellarator configurations with turbulent transport levels substantially lower than those in the original designs.

Lifshitz transition with interactions in high magnetic fields: Application to CeIn3

NASA Astrophysics Data System (ADS)

Schlottmann, Pedro

2012-02-01

The N'eel ordered state of CeIn3 is suppressed by a magnetic field of 61 T at ambient pressure. There is a second transition at ˜45 T, which has been associated with a Lifshitz transition [1,2]. Skin depth measurements [2] indicate that the transition is discontinuous as T ->0. Motivated by this transition we study the effects of Landau quantization and interaction among carriers on a Lifshitz transition. The Landau quantization leads to quasi-one-dimensional behavior for the direction parallel to the field. Repulsive Coulomb interactions give rise to a gas of strongly coupled carriers [3]. The density correlation function is calculated for a special long-ranged potential [4]. It is concluded that in CeIn3 a pocket is being emptied as a function of field in a discontinuous fashion in the ground state. This discontinuity is gradually smeared by the temperature [4] in agreement with the skin depth experiments [2]. 0.05in [1] S.E. Sebastian et al, PNAS 106, 7741 (2009). [2] K.M. Purcell et al, Phys. Rev. B 79, 214428 (2009). [3] P. Schlottmann and R. Gerhardts, Z. Phys. B 34, 363 (1979). [4] P. Schlottmann, Phys. Rev. B 83, 115133 (2011); J. Appl. Phys., in print.

On fast reconnection in pair plasmas

NASA Astrophysics Data System (ADS)

Zocco, A.; Chacon, L.; Simakov, A.; Lukin, V.

2008-11-01

The relevance of two-fluid effects to fast magnetic reconnection in standard electron-proton plasmas is well-known. The currently accepted view is that such fast reconnection is enabled by fast dispersive waves, which originate in the ion-electron mass difference. However, electron-positron (pair) plasmas do not feature such mass difference, and thus do not support fast dispersive waves. Nevertheless, recent kinetic and fluid pair-plasmas simulations have demonstrated that fast magnetic reconnection is indeed possible, thus casting doubt on the accepted view. In this study, we develop an analytical fluid model for 2D reconnection in non-relativistic, large-guide-field, low-β pair plasmas, including inertia, resistivity, and parallel viscosity.^4 We conclude that fast reconnection is possible in the collisionless (viscosity-dominated) regime, but not in the collisional (resistivity-dominated) one. J. Birn et al., J. Geophys. Res. 106 (A3), pp. 3715--3719 (2001) M. A. Shay et al., Geophys. Res. Lett. 26, 2163 (1999); B. N. Rogers et al., Phys. Rev. Lett. 87, 195004 (2001) See e.g. S. Zenitani and M. Hoshino, Astrophys. J. 562, L63 (2001); N. Bessho and A. Bhattacharjee, Phys. Rev. Lett. 95, 245001 (2005); W. Daughton and H. Karimabadi, Phys. Plasmas 14, 72303 (2007). L. Chac'on, A. N. Simakov, V. S. Lukin, A. Zocco, Phys. Rev. Lett., 025003 (2008)

Kinetic studies of divertor heat fluxes in Alcator C-Mod

NASA Astrophysics Data System (ADS)

Pankin, A. Y.; Bateman, G.; Kritz, A. H.; Rafiq, T.; Park, G. Y.; Chang, C. S.; Brunner, D.; Hughes, J. W.; Labombard, B.; Terry, J.

2010-11-01

The kinetic XGC0 code [C.S. Chang et al, Phys. Plasmas 11 (2004) 2649] is used to model the H- mode pedestal and SOL regions in Alcator C-Mod discharges. The self-consistent simulations in this study include kinetic neoclassical physics and anomalous transport models along with the ExB flow shear effects. The heat fluxes on the divertor plates are computed and the fluxes to the outer plate are compared with experimental observations. The dynamics of the radial electric field near the separatrix and in the SOL region are computed with the XGC0 code, and the effect of the anomalous transport on the heat fluxes in the SOL region is investigated. In particular, the particle and thermal diffusivities obtained in the analysis mode are compared with predictions from the theory-based anomalous transport models such as MMM95 [G. Bateman et al, Phys. Plasmas 5 (1998) 1793] and DRIBM [T. Rafiq et al, to appear in Phys. Plasmas (2010)]. It is found that there is a notable pinch effect in the inner separatrix region. Possible physical mechanisms for the particle and thermal pinches are discussed.

Sensitivity Studies in Gyro-fluid Simulation

NASA Astrophysics Data System (ADS)

Ross, D. W.; Dorland, W.; Beer, M. A.; Hammett, G. W.

1998-11-01

Transport models [1] derived from gyrofluid simulation [2] have been successful in predicting general confinement scalings. Specific fluxes and turbulent spectra, however, can depend sensitively on the plasma configuration and profiles, particularly in experiments with transients. Here, we step back from initial studies on Alcator C-Mod [3] and DIII-D [4] to investigate the sensitivity of simulations to variations in density, temperature (and their gradients) of each plasma species. We discuss the role of electric field shear, and the construction of local transport models for experimental comparison. In accompanying papers [5] we investigate comparisons with the experiments. *Supported by USDOE Grants DE-FG03-95ER54296, and DE-AC02-76CHO3073. [1] M. Kotschenreuther et al., Phys. Plasmas 2, 2381 (1995). [2] M. A. Beer et al, Phys. Plasmas 2, 2687 (1995). [3] D. W. Ross et al., Transport Task Force, Atlanta, 1998. [4] R. V. Bravenec et al., in Proc. 25th EPS Conf. on Contr. Fusion and Plasma Phys., Prague (1998). [5] R. V. Bravenec et al. and W. L. Rowan et al., these proceedings.

Systematic parameter study of hadron spectra and elliptic flow from viscous hydrodynamic simulations of Au+Au collisions at sNN=200 GeV

NASA Astrophysics Data System (ADS)

Shen, Chun; Heinz, Ulrich; Huovinen, Pasi; Song, Huichao

2010-11-01

Using the (2+1)-dimensional viscous hydrodynamic code vish2+1 [H. Song and U. Heinz, Phys. Lett. BPYLBAJ0370-269310.1016/j.physletb.2007.11.019 658, 279 (2008); H. Song and U. Heinz, Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.77.064901 77, 064901 (2008); H. Song, Ph. D. thesis, The Ohio State University, 2009], we present systematic studies of the dependence of pion and proton transverse-momentum spectra and their elliptic flow in 200A GeV Au+Au collisions on the parameters of the hydrodynamic model (thermalization time, initial entropy density distribution, decoupling temperature, equation of state, and specific shear viscosity η/s). We identify a tension between the slope of the proton spectra, which (within hydrodynamic simulations that assume a constant shear viscosity to entropy density ratio) prefer larger η/s values, and the slope of the pT dependence of charged hadron elliptic flow, which prefers smaller values of η/s. Changing other model parameters does not appear to permit dissolution of this tension.

Aging and crystallization in a lattice glass model

NASA Astrophysics Data System (ADS)

Seif, Alejandro; Loscar, Ernesto S.; Grigera, Tomás S.

2015-04-01

We have studied the three-dimensional lattice glass of Pica Ciamarra et al. [Phys. Rev. E 67, 057105 (2003), 10.1103/PhysRevE.67.057105], which has been shown to reproduce several features of the structural glass phenomenology, such as the cage effect, exponential increase of relaxation times, and aging. We show, using short-time dynamics, that the metastability limit is above the estimated Kauzmann temperature. We also find that in the region where the metastable liquid exists the aging exponent is lower than 0.5, indicating that equilibrium is reached relatively quickly. We conclude that the usefulness of this model to study the deeply supercooled regime is rather limited.

Electron transport parameters in NF3

NASA Astrophysics Data System (ADS)

Lisovskiy, V.; Yegorenkov, V.; Ogloblina, P.; Booth, J.-P.; Martins, S.; Landry, K.; Douai, D.; Cassagne, V.

2014-03-01

We present electron transport parameters (the first Townsend coefficient, the dissociative attachment coefficient, the fraction of electron energy lost by collisions with NF3 molecules, the average and characteristic electron energy, the electron mobility and the drift velocity) in NF3 gas calculated from published elastic and inelastic electron-NF3 collision cross-sections using the BOLSIG+ code. Calculations were performed for the combined RB (Rescigno 1995 Phys. Rev. E 52 329, Boesten et al 1996 J. Phys. B: At. Mol. Opt. Phys. 29 5475) momentum-transfer cross-section, as well as for the JB (Joucoski and Bettega 2002 J. Phys. B: At. Mol. Opt. Phys. 35 783) momentum-transfer cross-section. In addition, we have measured the radio frequency (rf) breakdown curves for various inter-electrode gaps and rfs, and from these we have determined the electron drift velocity in NF3 from the location of the turning point in these curves. These drift velocity values are in satisfactory agreement with those calculated by the BOLSIG+ code employing the JB momentum-transfer cross-section.

Density profile and breathing mode of strongly correlated spherical Yukawa plasmas

NASA Astrophysics Data System (ADS)

Henning, Christian; Fujioka, Kenji; Ludwig, Patrick; Bonitz, Michael

2007-11-01

The structure of ``Yukawa balls,'' i.e. spherical 3D dust crystals, which recently have been produced [1], is well explained by computer simulations of charged Yukawa interacting particles within an external parabolic confinement [2]. Dynamical properties (e.g. breathing mode) of these systems were investigated by experiment, simulations as well as theoretically by using the ansatz of a uniform ground state density [3]. Here we show analytically that screening has a dramatic effect on the density profile which decreases away from the center [4,5] and which is in excellent agreement with MD simulations of Yukawa balls. This result is used to improve former calculations of the breathing mode [6].References[1] O. Arp et al. Phys. Rev. Lett. 93, 165004 (2004)[2] M. Bonitz et al., Phys. Rev. Lett. 96, 075001 (2006)[3] T. E. Sheridan, Phys. Plasmas 13, 022106 (2006)[4] C. Henning et al., Phys. Rev. E 74, 056403 (2006)[5] C. Henning at al., Phys. Rev. E (2007)[6] C. Henning at al., submitted for publication

Improved Shell models for screened Coulomb balls

NASA Astrophysics Data System (ADS)

Bonitz, M.; Kaehlert, H.; Henning, C.; Baumgartner, H.; Filinov, A.

2006-10-01

Spherical Coulomb crystals in dusty plasmas [1] are well described by an isotropic Yukawa-type pair interaction and an external parabolic confinement as was shown by extensive molecular dynamics simulations [2]. A much simpler description is possible with analytical shell models which have been derived for Yukawas plasmas in [3,4]. Here we analyze improved Yukawa shell models which include correlations along the lines proposed for Coulomb crystals in [5]. The shell configurations are efficiently evaluated using a Monte Carlo procedure. [1] O. Arp, A. Piel and A. Melzer, Phys. Rev. Lett. 93, 165004 (2004). [2] M. Bonitz, D. Block, O. Arp, V. Golunychiy, H. Baumgartner, P. Ludwig, A. Piel and A. Filinov, Phys. Rev. Lett. 96, 075001 (2006). [3] H. Totsuji, C. Totsuji, T. Ogawa, and K. Tsuruta, Phys. Rev. E 71, 045401 (2005). [4] C. Henning, M. Bonitz, A. Piel, P. Ludwig, H. Baumgartner, V. Golubnichiy, and D. Block, submitted to Phys. Rev. E [5] W.D. Kraeft and M. Bonitz, J. Phys. Conf. Ser. 35, 94 (2006).

Controlling the optical bistability in a multi-level atomic system via similar parameters of quantum well nanostructure

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

Jafarzadeh, H., E-mail: h-jafarzadeh56@yahoo.com

2015-04-28

The spontaneously generated coherence (SGC) effects on optical bistability (OB) are investigated in a five-level K-type system. It is found that SGC makes the system phase dependent. Thus, the OB and the absorption behavior of the system can be controlled by the relation phase of applied fields. In addition, the pump field intensity effect on the OB behavior is discussed. The experimental viability of the model in semiconductor quantum well system is also discussed [A. V. Germanenko et al., J. Phys.: Conf. Ser. 376, 012024 (2012); D. S. Chemla et al., IEEE J. Quantum Electron. 20(3), 265 (1984); L. V.more » Butov et al., J. Exp. Theor. Phys. 88(5), 1036 (1999); J. F. Dynes et al., Phys. Rev. Lett. 94, 157403 (2005); S. Schmitt-Rinka et al., Adv. Phys. 38(2), 89 (1989); and H. W. Liu et al., Appl. Phys. Lett. 54, 2082 (1989)].« less

PUBLISHER'S ANNOUNCEMENT: Important changes for 2008

NASA Astrophysics Data System (ADS)

2008-01-01

This issue, the first of 2008, sees a new innovation for Journal of Physics G: Nuclear and Particle Physics (J. Phys. G). J. Phys. G has moved from page numbering to an article numbering system, which offers important advantages to our authors. It increases flexibility and speeds up the publication process as papers in different issues or subject sections can now be published online as soon as they are ready, without having to wait for a whole issue or section to be allocated page numbers. The bibliographic citation style will therefore change for articles published from now on. Articles should be referenced using the six-digit article number in place of a page number. Please note that this number must include any leading zeros. For example: Smith J et al 2008 J. Phys. G: Nucl. Part. Phys. 35 015045 If you have any questions or comments about our new scheme, please contact us at http://jphysg@iop.org J. Phys. G Publishing Team

Proceedings of the High Energy Density Matter (HEDM) Conference Held in New Orleans, Louisiana on 12-15 March 1989

DTIC Science & Technology

1989-07-01

distance in a planar arrangement of ArH3 , with the argon directly above the apical hydrogen. Matcha and 3, Milleur’ confined their calculations for...Phys. .11, 27 (1976). 7. W. J. Stevens, H-. Basch, and M. Krauss, J. Chem. Phys. il 6026 (1984). 8. R. L. Matcha , and Mac B. Milleur, J. Chem. Phys. f2

Generalized statistical complexity measures: Geometrical and analytical properties

NASA Astrophysics Data System (ADS)

Martin, M. T.; Plastino, A.; Rosso, O. A.

2006-09-01

We discuss bounds on the values adopted by the generalized statistical complexity measures [M.T. Martin et al., Phys. Lett. A 311 (2003) 126; P.W. Lamberti et al., Physica A 334 (2004) 119] introduced by López Ruiz et al. [Phys. Lett. A 209 (1995) 321] and Shiner et al. [Phys. Rev. E 59 (1999) 1459]. Several new theorems are proved and illustrated with reference to the celebrated logistic map.

Silicide Formation and Schottky Barrier of Rare-Earth Metals on SI

DTIC Science & Technology

1983-09-30

1981). 4. K. N. Tu, R. D. Thompson and B. Y. Tsaur, App]. Phys. Lett. 38, 626 (1981). 5. H. Norde, J. de Sousa Pires, F. d’Heurle, F. Pesavento , S...Phys. Lett. 38, 626 (1981). 7. H. Plarde, J. de ’’uis Pires, F. dI’Heurle, F. Pesavento , S. Petersson and P. A. Tove, ;!.Phys. L.ett. 38, 865 (1981

Analytical results for a conditional phase shift between single-photon pulses in a nonlocal nonlinear medium

NASA Astrophysics Data System (ADS)

Viswanathan, Balakrishnan; Gea-Banacloche, Julio

2018-03-01

It has been suggested that second-order nonlinearities could be used for quantum logic at the single-photon level. Specifically, successive two-photon processes in principle could accomplish the phase shift (conditioned on the presence of two photons in the low-frequency modes) |011 〉→i |100 〉→-|011 〉 . We have analyzed a recent scheme proposed by Xia et al. [Phys. Rev. Lett. 116, 023601 (2016)], 10.1103/PhysRevLett.116.023601 to induce such a conditional phase shift between two single-photon pulses propagating at different speeds through a nonlinear medium with a nonlocal response. We present here an analytical solution for the most general case, i.e., for an arbitrary response function, initial state, and pulse velocity, which supports their numerical observation that a π phase shift with unit fidelity is possible, in principle, in an appropriate limit. We also discuss why this is possible in this system, despite the theoretical objections to the possibility of conditional phase shifts on single photons that were raised some time ago by Shapiro [Phys. Rev. A 73, 062305 (2006)], 10.1103/PhysRevA.73.062305 and by Gea-Banacloche [Phys. Rev. A 81, 043823 (2010)], 10.1103/PhysRevA.81.043823 one of us.

Retrieving clinical evidence: a comparison of PubMed and Google Scholar for quick clinical searches.

PubMed

Shariff, Salimah Z; Bejaimal, Shayna Ad; Sontrop, Jessica M; Iansavichus, Arthur V; Haynes, R Brian; Weir, Matthew A; Garg, Amit X

2013-08-15

Physicians frequently search PubMed for information to guide patient care. More recently, Google Scholar has gained popularity as another freely accessible bibliographic database. To compare the performance of searches in PubMed and Google Scholar. We surveyed nephrologists (kidney specialists) and provided each with a unique clinical question derived from 100 renal therapy systematic reviews. Each physician provided the search terms they would type into a bibliographic database to locate evidence to answer the clinical question. We executed each of these searches in PubMed and Google Scholar and compared results for the first 40 records retrieved (equivalent to 2 default search pages in PubMed). We evaluated the recall (proportion of relevant articles found) and precision (ratio of relevant to nonrelevant articles) of the searches performed in PubMed and Google Scholar. Primary studies included in the systematic reviews served as the reference standard for relevant articles. We further documented whether relevant articles were available as free full-texts. Compared with PubMed, the average search in Google Scholar retrieved twice as many relevant articles (PubMed: 11%; Google Scholar: 22%; P<.001). Precision was similar in both databases (PubMed: 6%; Google Scholar: 8%; P=.07). Google Scholar provided significantly greater access to free full-text publications (PubMed: 5%; Google Scholar: 14%; P<.001). For quick clinical searches, Google Scholar returns twice as many relevant articles as PubMed and provides greater access to free full-text articles.

Study for Nuclear Structures of 22-35Na Isotopes via Measurements of Reaction Cross Sections

NASA Astrophysics Data System (ADS)

Suzuki, Shinji

2014-09-01

T. Ohtsubo, M. Nagashima, T. Ogura, Y. Shimbara (Grad. Sch. of Sc., Niigata Univ.), M.Takechi, H. Geissel, M. Winkler (GSI), D. Nishimura, T. Sumikama (Dept. of Phys., Tokyo Univ. of Sc.), M. Fukuda, M. Mihara, H. Uenishi (Dept. of Phys., Osaka Univ.), T. Kuboki, T. Suzuki, T. Yamaguchi, H. Furuki, C. S. Lee, K. Sato (Dept. of Phys., Saitama Univ.), A. Ozawa, H. Ohnishi, T. Moriguchi, S. Fukuda, Y. Ishibashi, D. Nagae, R. Nishikiori, T. Niwa (Inst. of Phys., Univ. of Tsukuba), N. Aoi (RCNP), Rui-Jiu Chen, N. Inabe, D. Kameda, T. Kubo, M. Lantz, T. Ohnishi, K. Okumura, H. Sakurai, H. Suzuki, H. Takeda, S. Takeuchi, K. Tanaka, Y. Yanagisawa (RIKEN), De-Qing Fang, Yu-Gang Ma (SINAP), T. Izumikawa (RI Ctr., Niigata Univ.), and S. Momota (Fac. of Engn., Kochi Univ. of Tech.) Reaction cross sections (σR) for 22-35Na isotopes have been measured at around 240 MeV/nucleon. The σR for 22-35Na were measured for the first time. Enhancement in cross sections is clearly observed from the systematics for stable nuclei, for isotopes with large mass numbers. These enhancement can be mainly ascribed to the nuclear deformation. We will discuss the nuclear structure (neutron skin, nuclear shell structure) for neutron-excess Na isotopes. T. Ohtsubo, M. Nagashima, T. Ogura, Y. Shimbara (Grad. Sch. of Sc., Niigata Univ.), M.Takechi, H. Geissel, M. Winkler (GSI), D. Nishimura, T. Sumikama (Dept. of Phys., Tokyo Univ. of Sc.), M. Fukuda, M. Mihara, H. Uenishi (Dept. of Phys., Osaka Univ.), T. Kuboki, T. Suzuki, T. Yamaguchi, H. Furuki, C. S. Lee, K. Sato (Dept. of Phys., Saitama Univ.), A. Ozawa, H. Ohnishi, T. Moriguchi, S. Fukuda, Y. Ishibashi, D. Nagae, R. Nishikiori, T. Niwa (Inst. of Phys., Univ. of Tsukuba), N. Aoi (RCNP), Rui-Jiu Chen, N. Inabe, D. Kameda, T. Kubo, M. Lantz, T. Ohnishi, K. Okumura, H. Sakurai, H. Suzuki, H. Takeda, S. Takeuchi, K. Tanaka, Y. Yanagisawa (RIKEN), De-Qing Fang, Yu-Gang Ma (SINAP), T. Izumikawa (RI Ctr., Niigata Univ.), and S. Momota (Fac. of Engn., Kochi Univ. of Tech.) Reaction cross sections (σR) for 22-35Na isotopes have been measured at around 240 MeV/nucleon. The σR for 22-35Na were measured for the first time. Enhancement in cross sections is clearly observed from the systematics for stable nuclei, for isotopes with large mass numbers. These enhancement can be mainly ascribed to the nuclear deformation. We will discuss the nuclear structure (neutron skin, nuclear shell structure) for neutron-excess Na isotopes. JSPS KAKENHI Grant Number 24244024.

Families of quantum fingerprinting protocols

NASA Astrophysics Data System (ADS)

Lovitz, Benjamin; Lütkenhaus, Norbert

2018-03-01

We introduce several families of quantum fingerprinting protocols to evaluate the equality function on two n -bit strings in the simultaneous message passing model. The original quantum fingerprinting protocol uses a tensor product of a small number of O (logn ) -qubit high-dimensional signals [H. Buhrman et al., Phys. Rev. Lett. 87, 167902 (2001), 10.1103/PhysRevLett.87.167902], whereas a recently proposed optical protocol uses a tensor product of O (n ) single-qubit signals, while maintaining the O (logn ) information leakage of the original protocol [J. M. Arazola and N. Lütkenhaus, Phys. Rev. A 89, 062305 (2014), 10.1103/PhysRevA.89.062305]. We find a family of protocols which interpolate between the original and optical protocols while maintaining the O (logn ) information leakage, thus demonstrating a tradeoff between the number of signals sent and the dimension of each signal. There has been interest in experimental realization of the recently proposed optical protocol using coherent states [F. Xu et al., Nat. Commun. 6, 8735 (2015), 10.1038/ncomms9735; J.-Y. Guan et al., Phys. Rev. Lett. 116, 240502 (2016), 10.1103/PhysRevLett.116.240502], but as the required number of laser pulses grows linearly with the input size n , eventual challenges for the long-time stability of experimental setups arise. We find a coherent state protocol which reduces the number of signals by a factor 1/2 while also reducing the information leakage. Our reduction makes use of a simple modulation scheme in optical phase space, and we find that more complex modulation schemes are not advantageous. Using a similar technique, we improve a recently proposed coherent state protocol for evaluating the Euclidean distance between two real unit vectors [N. Kumar et al., Phys. Rev. A 95, 032337 (2017), 10.1103/PhysRevA.95.032337] by reducing the number of signals by a factor 1/2 and also reducing the information leakage.

EDITORIAL: Colloidal dispersions in external fields Colloidal dispersions in external fields

NASA Astrophysics Data System (ADS)

Löwen, Hartmut

2012-11-01

Colloidal dispersions have long been proven as pivotal model systems for equilibrium phase transition such as crystallization, melting and liquid-gas phase transition. The last decades have revealed that this is also true for nonequilibrium phenomena. In fact, the fascinating possibility to track the individual trajectories of colloidal particles has greatly advanced our understanding of collective behaviour in classical many-body systems and has helped to reveal the underlying physical principles of glass transition, crystal nucleation, and interfacial dynamics (to name just a few typical nonequilibrium effects). External fields can be used to bring colloids out of equilibrium in a controlled way. Different kinds of external fields can be applied to colloidal dispersions, namely shear flow, electric, magnetic and laser-optical fields, and confinement. Typical research areas can be sketched with the by now traditional complexity diagram (figure 1). The complexity of the colloidal system itself as embodied in statistical degrees of freedom is shown on the x-axis while the complexity of the problem posed, namely bulk, an inhomogeneity in equilibrium, steady state nonequilibrium and full time-dependent nonequilibrium are shown on the y-axis. The different external fields which can be imposed are indicated by the different hatched areas. figure1 Figure 1. Diagram of complexity for colloidal dispersions in external fields: while the x-axis shows the complexity of the system, the y-axis shows the complexity of the problem. Regions which can be accessed by different kinds of external fields are indicated. The arrows indicate recent research directions. Active particles are also indicated with a special complexity of internal degrees of freedom [1]. This collection of papers reflects the scientific programme of the International Conference on Colloidal Dispersions in External Fields III (CODEF III) which took place in Bonn-Bad Godesberg from 20-23 March 2012. This was the third conference in a series that began in 2004 [2] and was continued in 2008 [3]. The CODEF meeting series is held in conjunction with the German Dutch Transregional Collaborative Research Centre SFB TR6 with the title Physics of Colloidal Dispersions in External Fields. Papers from scientists working within this network as well as those from further invited contributors are summarized in this issue. They are organized according to the type of field applied, namely: shear flow electric field laser-optical and magnetic field confinement other fields and active particles To summarize the highlights of this special issue as regards shear fields, the response of depletion-induced colloidal clusters to shear is explored in [4]. Soft particles deform under shear and their structural and dynamical behaviour is studied both by experiment [5] and theory [6]. Transient dynamics after switching on shear is described by a joint venture of theory, simulation and experiment in [7]. Colloids provide the fascinating possibility to drag single particles through the suspension, which gives access to microrheology (as opposed to macrorheology, where macroscopic boundaries are moved). Several theoretical aspects of microrheology are discussed in this issue [8-10]. Moreover, a microscopic theory for shear viscosity is presented [11]. Various aspects of colloids in electric fields are also included in this issue. Electrokinetic phenomena for charged suspensions couple flow and electric phenomena in an intricate way and are intensely discussed both by experiment and simulation in contributions [12-14]. Dielectric phenomena are also influenced by electric fields [15]. Electric fields can induce effective dipolar forces between colloids leading to string formation [16]. Finally, binary mixtures in an electric driving field exhibit laning [17]. Simulation [18] and theoretical [19] studies of this nonequilibrium phenomenon are also discussed in this issue. Laser-optical fields can be used to tailor a random substrate potential for colloids [20] or to bind colloids optically [21]. External magnetic fields are typically used to create dipolar repulsions of colloids pending at an air-water interface. This provides an avenue to two-dimensional systems, where the freezing transition [22] and various transport phenomena through channels are the focus of recent research [23, 24]. Confinement typically leads to interfaces. The classical problem of the Tolman length for a fluid-fluid interface is reviewed in detail in [25]. In fact, colloid-polymer mixtures constitute ideal model systems for liquid-gas interfaces in various geometries [26] and are also suitable for measuring the Tolman length experimentally. Crystalline phases in confinement [27] and crystal-fluid interfaces [28] are even more complex due to the inhomogeneity of the solid phase. Also in the confined fluid phase, there are still open issues in slit-pore geometry. These include how to scale the interparticle distance [29] and how to measure hydrodynamic interactions between colloidal particles [30]. Other external fields which can be applied to colloids are gravity [31] and temperature [32]. An important field of recently emerging research is active colloidal particles (so-called microswimmers) which possess fascinating nonequilibrium properties; for recent reviews see [33-35]. Two examples are also included in this issue: an active deformable particle [36] moving in gravity and the collective turbulent swarming behaviour of dense self-propelled colloidal rod suspensions [37]. References [1]Löwen H 2001 J. Phys. Condens. Matter 13 R415 [2]Löwen H and Likos C N (ed) 2004 J. Phys. Condens. Matter 16 (special issue) [3]Löwen H 1976 J. Phys. Condens. Matter 20 404201 [4]Guu D, Dhont J K G, Vliegenthart G A and Lettinga M P 2012 J. Phys. Condens. Matter 24 464101 [5]Gupta S, Kundu S, Stellbrink J, Willner L, Allgaier J and Richter D 2012 J. Phys. Condens. Matter 24 464102 [6]Singh S P, Fedosov D A, Chatterji A, Winkler R G, Gompper G 2012 J. Phys. Condens. Matter 24 464103 [7]Laurati M et al 2012 J. Phys. Condens. Matter 24 464104 [8]Harrer C J, Winter D, Horbach J, Fuchs M and Voigtmann T 2012 J. Phys. Condens. Matter 24 464105 [9]De Puit R J and Squires T M 2012 J. Phys. Condens. Matter 24 464106 [10]De Puit R J and Squires T M 2012 J. Phys. Condens. Matter 24 464107 [11]Contreras-Aburto C and Nägele G 2012 J. Phys. Condens. Matter 24 464108 [12]Palberg T, Köller T, Sieber B, Schweinfurth H, Reiber H and Nägele G 2012 J. Phys. Condens. Matter 24 464109 [13]Papadopoulos P, Deng X and Vollmer D 2012 J. Phys. Condens. Matter 24 464110 [14]Schmitz R and Dünweg B 2012 J. Phys. Condens. Matter 24 464111 [15]Zhou J and Schmid F 2012 J. Phys. Condens. Matter 24 464112 [16]Smallenburg F, Vutukuri H R, Imhof A, van Blaaderen A and Dijkstra M 2012 J. Phys. Condens. Matter 24 464113 [17]Vissers T, Wysocki A, Rex M, Löwen H, Royall C P, Imhof A and van Blaaderen A 2011 Soft Matter 7 2352 [18]Glanz T and Löwen H 2012 J. Phys. Condens. Matter 24 464114 [19]Kohl M, Ivlev A, Brand P, Morfill G E and Löwen H 2012 J. Phys. Condens. Matter 24 464115 [20]Hanes R D L and Egelhaaf S U 2012 J. Phys. Condens. Matter 24 464116 [21]Mazilu M, Rudhall A, Wright E M and Dholakia K 2012 J. Phys. Condens. Matter 24 464117 [22]Dillmann P, Maret G and Keim P 2012 J. Phys. Condens. Matter 24 464118 [23]Wilms D et al 2012 J. Phys. Condens. Matter 24 464119 [24]Kreuter C, Siems U, Henseler P, Nielaba P, Leiderer P and Erbe A 2012 J. Phys. Condens. Matter 24 464120 [25]Malijevsky A and Jackson G 2012 J. Phys. Condens. Matter 24 464121 [26]Statt A, Winkler A, Virnau P and Binder K 2012 J. Phys. Condens. Matter 24 464122 [27]Oğuz E C, Löwen H, Reinmüller A, Schöpe H J, Palberg T and Messina R 2012 J. Phys. Condens. Matter 24 464123 [28]Oettel M 2012 J. Phys. Condens. Matter 24 464124 [29]Zeng Y and van Klitzing R 2012 J. Phys. Condens. Matter 24 464125 [30]Bonilla-Capilla B, Ramirez-Saito A, Ojeda-Lopez M A and Arauz-Lara J L 2012 J. Phys. Condens. Matter 24 464126 [31]Leferink op Reinink A B G M, van den Pol E, Byelov D V, Petukhov A V and Vroege G J 2012 J. Phys. Condens. Matter 24 464127 [32]Taylor S L, Evans R and Royall C P 2012 J. Phys. Condens. Matter 24 464128 [33]Toner J, Tu Y H and Ramaswamy S 2012 J. Phys. Condens. Matter 24 464110 [34]Schmitz R and Dünweg B 2005 J. Phys. Condens. Matter 318 170 [35]Cates M E 2012 Rep. Prog. Phys. 75 042601 [36]Tarama M and Ohta T 2012 J. Phys. Condens. Matter 24 464129 [37]Wensink H H and Löwen H 2012 J. Phys. Condens. Matter 24 464130 Colloidal dispersions in external fields contents Colloidal dispersions in external fieldsHartmut Löwen Depletion induced clustering in mixtures of colloidal spheres and fd-virusD Guu, J K G Dhont, G A Vliegenthart and M P Lettinga Advanced rheological characterization of soft colloidal model systemsS Gupta, S K Kundu, J Stellbrink, L Willner, J Allgaier and D Richter Conformational and dynamical properties of ultra-soft colloids in semi-dilute solutions under shear flowSunil P Singh, Dmitry A Fedosov, Apratim Chatterji, Roland G Winkler and Gerhard Gompper Transient dynamics in dense colloidal suspensions under shear: shear rate dependenceM Laurati, K J Mutch, N Koumakis, J Zausch, C P Amann, A B Schofield, G Petekidis, J F Brady, J Horbach, M Fuchs and S U Egelhaaf Force-induced diffusion in microrheologyCh J Harrer, D Winter, J Horbach, M Fuchs and Th Voigtmann Micro-macro-discrepancies in nonlinear microrheology: I. Quantifying mechanisms in a suspension of Brownian ellipsoidsRyan J DePuit and Todd M Squires Micro-macro discrepancies in nonlinear microrheology: II. Effect of probe shapeRyan J DePuit and Todd M Squires Viscosity of electrolyte solutions: a mode-coupling theoryClaudio Contreras-Aburto and Gerhard Nägele Electro-kinetics of charged-sphere suspensions explored by integral low-angle super-heterodyne laser Doppler velocimetryThomas Palberg, Tetyana Köller, Bastian Sieber, Holger Schweinfurth, Holger Reiber and Gerhard Nägele Electrokinetics on superhydrophobic surfacesPeriklis Papadopoulos, Xu Deng, Doris Vollmer and Hans-Jürgen Butt Numerical electrokineticsR Schmitz and B Dünweg Dielectric response of nanoscopic spherical colloids in alternating electric fields: a dissipative particle dynamics simulationJiajia Zhou and Friederike Schmid Self-assembly of colloidal particles into strings in a homogeneous external electric or magnetic fieldFrank Smallenburg, Hanumantha Rao Vutukuri, Arnout Imhof, Alfons van Blaaderen and Marjolein Dijkstra The nature of the laning transition in two dimensionsT Glanz and H Löwen Microscopic theory for anisotropic pair correlations in driven binary mixturesMatthias Kohl, Alexei V Ivlev, Philip Brandt, Gregor E Morfill and Hartmut Löwen Dynamics of individual colloidal particles in one-dimensional random potentials: a simulation studyRichard D L Hanes and Stefan U Egelhaaf An interacting dipole model to explore broadband transverse optical bindingMichael Mazilu, Andrew Rudhall, Ewan M Wright and Kishan Dholakia Comparison of 2D melting criteria in a colloidal systemPatrick Dillmann, Georg Maret and Peter Keim Effects of confinement and external fields on structure and transport in colloidal dispersions in reduced dimensionalityD Wilms, S Deutschländer, U Siems, K Franzrahe, P Henseler, P Keim, N Schwierz, P Virnau, K Binder, G Maret and P Nielaba Stochastic transport of particles across single barriersChristian Kreuter, Ullrich Siems, Peter Henseler, Peter Nielaba, Paul Leiderer and Artur Erbe A perspective on the interfacial properties of nanoscopic liquid dropsAlexandr Malijevský and George Jackson Controlling the wetting properties of the Asakura-Oosawa model and applications to spherical confinementA Statt, A Winkler, P Virnau and K Binder Crystalline multilayers of charged colloids in soft confinement: experiment versus theoryE C Oğuz, A Reinmüller, H J Schöpe, T Palberg, R Messina and H Löwen Mode expansion for the density profiles of crystal-fluid interfaces: hard spheres as a test caseM Oettel Scaling of layer spacing of charged particles under slit-pore confinement: an effect of concentration or of effective particle diameter?Yan Zeng and Regine von Klitzing Hydrodynamic interactions between colloidal particles in a planar poreB Bonilla-Capilla, A Ramírez-Saito, M A Ojeda-López and J L Arauz-Lara Ageing in a system of polydisperse goethite boardlike particles showing rich phase behaviourA B G M Leferink op Reinink, E van den Pol, D V Byelov, A V Petukhov and G J Vroege Temperature as an external field for colloid-polymer mixtures: 'quenching' by heating and 'melting' by coolingShelley L Taylor, Robert Evans and C Patrick Royall Spinning motion of a deformable self-propelled particle in two dimensionsMitsusuke Tarama and Takao Ohta Emergent states in dense systems of active rods: from swarming to turbulenceH H Wensink and H Löwen

Smoothing of Gaussian quantum dynamics for force detection

NASA Astrophysics Data System (ADS)

Huang, Zhishen; Sarovar, Mohan

2018-04-01

Building on recent work by Gammelmark et al. [Phys. Rev. Lett. 111, 160401 (2013), 10.1103/PhysRevLett.111.160401] we develop a formalism for prediction and retrodiction of Gaussian quantum systems undergoing continuous measurements. We apply the resulting formalism to study the advantage of incorporating a full measurement record and retrodiction for impulselike force detection and accelerometry. We find that using retrodiction can only increase accuracy in a limited parameter regime, but that the reduction in estimation noise that it yields results in better detection of impulselike forces.

Comment on ``Anisotropy studies of molecular-beam-epitaxy-grown Co(111) thin films by ferromagnetic resonance'' [J. Appl. Phys. 75, 6492 (1994)

NASA Astrophysics Data System (ADS)

Artman, J. O.

1995-05-01

The magnetic free energy expression E used to calculate ferromagnetic resonance frequencies by F. Schreiber et al., J. Appl. Phys. 75, 6492 (1994) is examined. The expression is correct for hexagonal site symmetry films but not for any type of cubic symmetry film. The correct expression, including both K1c and K2c anisotropy contributions, for E with H in the basal plane of a (111) film is given in the text.

The Production and Study of Cold Antiprotons and Antihydrogen

DTIC Science & Technology

2015-08-03

Grafström, R. Hagel- berg, G. Kessler, and et al ., Phys. Lett. B 237, 303 (1990). [8] C. Zimmermann and T. Hänsch, Hyperfine Interact. 76, 47 (1993). [9...C. Parthey, A. Matveev, J. Alnis, B. Bernhardt, A. Beyer, R. Holzwarth, A. Maistrou, R. Pohl, K. Pre- dehl, T. Udem, T. Wilken, N. Kolachevsky, et al ...D. Lett, R. N. Watts, C. I. Westbrook, W. D. Phillips, P. L. Gould , and H. J. Metcalf, Phys. Rev. Lett. 61, 169 ( 1988 ). [15] J. Walz and T. Hänsch

Structure and Dynamics of Cu3Au(001) Studied by Elastic and Inelastic Helium Atom Scattering

DTIC Science & Technology

1990-01-01

longitudinal] decouple from the shear horizontal (SH) modes. Selection rules dictate that our experiment was sensitive only to sagittal modes...Hoffmann, E. Preu3, R. Franchy , H. lbach, Y. Chen, M. L. Xu, and S Y. Tong, preprint. 4. A. i. Taub, and R. L. Fleisher, Science 243, 616 (1989).: B. H. Kear... Franchy , and H. Ibach, Z. Phys. B-Condensed Matter 65, 71 (1986). 19. E. D. Hallman, Can. J. Phys. 52, 2235 (1974). 20. E. C. Svensson, E. D. Hallman

A TBA approach to thermal transport in the XXZ Heisenberg model

NASA Astrophysics Data System (ADS)

Zotos, X.

2017-10-01

We show that the thermal Drude weight and magnetothermal coefficient of the 1D easy-plane Heisenberg model can be evaluated by an extension of the Bethe ansatz thermodynamics formulation by Takahashi and Suzuki (1972 Prog. Theor. Phys. 48 2187). They have earlier been obtained by the quantum transfer matrix method (Klümper 1999 Z. Phys. B 91 507). Furthermore, this approach can be applied to the study of the far-out of equilibrium energy current generated at the interface between two semi-infinite chains held at different temperatures.

Effects of Solvation On One- and Two-Photon Spectra of Coumarin Derivatives: A TDDFT Study (Preprint)

DTIC Science & Technology

2006-10-01

1999,103,9614. (14) Pal, H.; Nad, S.; Kumbhakar, M. J Chern. Phys. 2003, 119,443. (15) Barik , A.; Nath, S.; Pal, H. J Chern. Phys. 2003, 119, 10202...Signature// TIM J . SCHUMACHER, Chief Survivability and Sensor Materials Division This report is published in the interest of...6-311 ++G(d,p) and the aug-cc-pVTZ basis sets. Theory Expt System/Method E(S])f Jlo]Energy (JlO]) [ j ]Solvent C120 CAMB3LYP 4.29 (4.24)0.373 (0.368

Rydberg dressing of atoms in optical lattices

NASA Astrophysics Data System (ADS)

Macrı, T.; Pohl, T.

2014-01-01

We study atoms in optical lattices whose electronic ground state is off-resonantly coupled to a highly excited state with strong binary interactions. We present a time-dependent treatment of the resulting quantum dynamics, which—contrary to recent predictions [36 Li, Ates, and Lesanovsky, Phys. Rev. Lett. 110, 213005 (2013), 10.1103/PhysRevLett.110.213005]—proves that the strong repulsion between the weakly admixed Rydberg states does not lead to atomic trap loss. This finding provides an important basis for creating and manipulating coherent long-range interactions in optical lattice experiments.

Study of the Physics of Insulating Films as Related to the Reliability of Metal-Oxide Semiconductor Devices

DTIC Science & Technology

1981-07-01

and Berglund (13,5). Pulsed electron flow is induced through the SiO 2 film by rf avalanche in the p-silicon surface depletion layer, and the rf voltage...were then evaporated through a shadow mask from an rf heated crucible in a vacuum chamber under 10 - 6 Torr pressure. Finally, a post-metallization...12.) P. Williams and J.E. Baker, Appl. Phys. Lett. 36, 842 (1980). 13.) H.H. Anderson, Appl. Phys. 18, 131 (1979). 14.) D.R. Young, D.J. DiMaria, W.R

A Neutron and X-Ray Diffraction Study of Ca-Mg-Cu Metallic Glasses (Postprint)

DTIC Science & Technology

2014-04-01

North DM. Phys Chem Liq 1968;1:1. [25] Wright AC. J Non-Cryst Solids 1989;112:33. [26] Patterson AL. Z Kristallogr 1935;90:517. [27] Soper AK. J Phys...PJ, Cundall JA. Acta Cryst 1965;19:807. [31] Hannon AC. Nucl Instrum Meth A 2005;551:88. [32] Soper AK. Gudrun software, http://www.isis.stfc.ac.uk...instruments/sandals/ data-analysis/gudrun8864.html. [33] Hannon AC, Howells WS, Soper AK. IOP Conf Ser 1990;107:193. [34] Soper AK. GudrunX software

A Neutron and X-ray Diffraction Study of Ca-Mg-Cu Metallic Glasses (Preprint)

DTIC Science & Technology

2011-07-01

A.L. Patterson, Z Kristallogr 90(1935)517. 29. A.K. Soper , J. Phys.: Condens. Matter 19(2007)335206. 30. P.G. Mikolaj and C.J. Pings, Phys. Chem...Liq. 1(1968)93. 31. P.J. Black and J.A. Cundall, Acta Cryst. 19(1965)807. 32. A.C. Hannon, Nucl. Instrum. Meth. A 551(2005)88. 33. A.K. Soper ...Gudrun software: http://www.isis.stfc.ac.uk/instruments/sandals/data- analysis/gudrun8864.html. 34. A.C. Hannon, W.S. Howells and A.K. Soper , IOP Conf

PREFACE: Introductory remarks Introductory remarks

NASA Astrophysics Data System (ADS)

Bowler, D. R.; Alfe, D.

2010-02-01

This special issue contains papers related to the 2009 Thomas Young Centre Workshop at University College London 'Accessing large length and time scales with accurate quantum methods', in celebration of Professor Michael Gillan's 65th birthday. Mike Gillan won the 2006 Institute of Physics Dirac Medal and Prize, the citation reading: 'For his contributions to the development of atomic-scale computer simulations, which have greatly extended their power and effectiveness over an immense range of applications'. This rightly highlights Mike's seminal work on materials modelling, but misses out some of the many other areas he has enriched. After taking his PhD at the Department of Theoretical Physics, Oxford University, Mike went as a post-doc to Minneapolis. He then joined the Statistical Physics Group in the Theoretical Physics Division, Harwell, where he stayed for over 20 years, with a brief interlude in Saclay. In the late 1980s, Mike made a transition to become Professor of Physics at the University of Keele, where he stayed for a decade until University College London was fortunate in being able to tempt him to join the Condensed Matter and Material Physics Group, where there was already a significant materials modelling initiative. Over the years, Mike has made many important contributions, some with impact on other areas of science, others with significance in technology areas such as nuclear safety. Thus, he developed a form of quantum transition-state theory, generalizing Eyring's well-known classical transition-state theory to the case of quantum particles, such as hydrogen, diffusing in condensed matter. He pioneered quantum methods for calculating defect energetics in solids, and then molecular processes on surfaces. He synthesised these approaches into very general ways to calculate thermodynamic free energies of condensed matter from first principles, drawing on his early experience of statistical physics. These methods led to rapid advances in the study of matter under extreme conditions, as in the Earth's core. A further powerful development has been his input to linear-scaling quantum techniques for the properties of very large complex systems. In recent years, his attention has shifted towards increasing accuracy, touching areas such as quantum Monte Carlo and hierarchical quantum chemical techniques. In this journal issue, we have papers which both reflect topics from the workshop and address a number of areas which are directly in Mike's interests or which have been influenced by his work or assistance. There are papers addressing accuracy in quantum simulations [1-5], methods for applying quantum techniques to large systems [6, 7] and applications of quantum simulations to important problems [8-10]. We also have a viewpoint on magnetism in oxides and carbon [11], prompted by Mike's innovative work on oxides. References [1] Nolan S J, Bygrave P J, Allan N L and Manby F R 2010 J. Phys.: Condens. Matter 22 074201 [2] Badinski A, Haynes P D, Trail J R and Needs R J 2010 J. Phys.: Condens. Matter 22 074202 [3] Klimeš J, Bowler D R and Michaelides A 2010 J. Phys.: Condens. Matter 22 074203 [4] Baroni S, Gebauer R, Malcιoğlu O B, Saad Y, Umari P and Xian J 2010 J. Phys.: Condens. Matter 22 074204 [5] Toton D, Lorenz C D, Rompotis N, Martsinovich N and Kantorovich L 2010 J. Phys.: Condens. Matter 22 074205 [6] Fujiwara T, Hoshi T, Yamamoto S, Sogabe T and Zhang S-L 2010 J. Phys.: Condens. Matter 22 074206 [7] Bowler D R and Miyazari T 2010 J. Phys.: Condens. Matter 22 074207 [8] Er S, van Setten M J, de Wijs G A and Brocks G 2010 J. Phys.: Condens. Matter 22 074208 [9] Pan D, Liu L-M, Tribello G A, Slater B, Michaelides A and Wang E 2010 J. Phys.: Condens. Matter 22 074209 [10] Choudhury R, Gattinoni C, Makov G and De Vita A 2010 J. Phys.: Condens. Matter 22 074210 [11] Stoneham M 2010 J. Phys.: Condens. Matter 22 074211

PubMedMiner: Mining and Visualizing MeSH-based Associations in PubMed.

PubMed

Zhang, Yucan; Sarkar, Indra Neil; Chen, Elizabeth S

2014-01-01

The exponential growth of biomedical literature provides the opportunity to develop approaches for facilitating the identification of possible relationships between biomedical concepts. Indexing by Medical Subject Headings (MeSH) represent high-quality summaries of much of this literature that can be used to support hypothesis generation and knowledge discovery tasks using techniques such as association rule mining. Based on a survey of literature mining tools, a tool implemented using Ruby and R - PubMedMiner - was developed in this study for mining and visualizing MeSH-based associations for a set of MEDLINE articles. To demonstrate PubMedMiner's functionality, a case study was conducted that focused on identifying and comparing comorbidities for asthma in children and adults. Relative to the tools surveyed, the initial results suggest that PubMedMiner provides complementary functionality for summarizing and comparing topics as well as identifying potentially new knowledge.

Some properties of Stark states of hydrogenic atoms and ions

NASA Astrophysics Data System (ADS)

Hey, J. D.

2007-10-01

The motivation for this work is the problem of providing accurate values of the atomic transition matrix elements for the Stark components of Rydberg Rydberg transitions in atomic hydrogen and hydrogenic ions, for use in spectral line broadening calculations applicable to cool, low-density plasmas, such as those found in H II regions. Since conventional methods of calculating these transition matrix elements cannot be used for the high principal quantum numbers now easily attained in radio astronomical spectra, we attempt to show that the recurrence relation (ladder operator) method recently employed by Watson (2006 J. Phys. B: At. Mol. Opt. Phys. 39 1889 97) and Hey (2006 J. Phys. B: At. Mol. Opt. Phys. 39 2641 64) can be taken over into the parabolic coordinate system used to describe the Stark states of the atomic (ionic) radiators. The present method is therefore suggested as potentially useful for extending the work of Griem (1967 Astrophys. J. 148 547 58, 2005 Astrophys. J. 620 L133 4), Watson (2006), Stambulchik et al (2007 Phys. Rev. E 75 016401(9 pp) on Stark broadening in transitions between states of high principal quantum number, to physical conditions where the binary, impact approximation is no longer strictly applicable to both electron and ion perturbers. Another possible field of application is the study of Stark mixing transitions in 'ultracold' Rydberg atoms perturbed by long-range interactions with slow atoms and ions. Preparatory to the derivation of recurrence relations for states of different principal quantum number, a number of properties and recurrence relations are also found for states of identical principal quantum number, including the analogue in parabolic coordinates to the relations of Pasternack (1937 Proc. Natl Acad. Sci. USA 23 91 4, 250) in spherical polar coordinates.

The Relation Between Use of Mobile Electronic Devices and Bedtime Resistance, Sleep Duration, and Daytime Sleepiness Among Preschoolers.

PubMed

Nathanson, Amy I; Beyens, Ine

2018-01-01

This study investigated the relation between preschoolers' mobile electronic device (MED) use and sleep disturbances. A national sample of 402 predominantly college-educated and Caucasian mothers of 3-5-year-olds completed a survey assessing their preschoolers' MED use, bedtime resistance, sleep duration, and daytime sleepiness. Heavier evening and daily tablet use (and to some extent, smartphone use) were related to sleep disturbances. Other forms of MED use were not consistently related to sleep disturbances. In addition, playing games on MEDs at bedtime was related to compromised sleep duration, although other forms of MED use at bedtime were not related to sleep outcomes. Although the relations between MED use and sleep disturbances were small in size, they were larger than the relations between sleep and other predictors in the models. Continued work should investigate how MED exposure is related to children's cognitive, psychological, emotional, and physiological development, particularly given the popularity and widespread use of these devices.

Comparison of PIRO, SOFA, and MEDS scores for predicting mortality in emergency department patients with severe sepsis and septic shock.

PubMed

Macdonald, Stephen P J; Arendts, Glenn; Fatovich, Daniel M; Brown, Simon G A

2014-11-01

The Predisposition Insult Response and Organ failure (PIRO) scoring system has been developed for use in the emergency department (ED) to risk stratify sepsis cases, but has not been well studied among high-risk patients with severe sepsis and septic shock. The PIRO score was compared with the Sequential Organ Failure Assessment (SOFA) and Mortality in ED Sepsis (MEDS) scores to predict mortality in ED patients with features suggesting severe sepsis or septic shock in the ED. This was an analysis of sepsis patients enrolled in a prospective observational ED study of patients presenting with evidence of shock, hypoxemia, or other organ failure. PIRO, MEDS, and SOFA scores were calculated from ED data. Analysis compared areas under the receiver operator characteristic (ROC) curves for 30-day mortality. Of 240 enrolled patients, final diagnoses were septic shock in 128 (53%), severe sepsis without shock in 70 (29%), and infection with no organ dysfunction in 42 (18%). Forty-eight (20%) patients died within 30 days of presentation. Area under the ROC curve (AUC) for mortality was 0.86 (95% confidence interval [CI] = 0.80 to 0.92) for PIRO, 0.81 (95% CI = 0.74 to 0.88) for MEDS, and 0.78 (95% CI = 0.71 to 0.87) for SOFA scores. Pairwise comparisons of the AUC were as follows: PIRO versus SOFA, p = 0.01; PIRO versus MEDS, p = 0.064; and MEDS versus SOFA; p = 0.37. Mortality increased with increasing PIRO scores: PIRO < 5, 0%; PIRO 5 to 9, 5%; PIRO 10 to 14, 5%; PIRO 15 to 19, 37%; and PIRO ≥ 20, 80% (p < 0.001). The MEDS score also showed increasing mortality with higher scores: MEDS < 5, 0%; MEDS 5 to 7, 12%; MEDS 8 to 11, 15%; MEDS 12 to 14, 48%; and MEDS > 15, 65% (p < 0.001). The PIRO model, taking into account comorbidities and septic source as well as physiologic status, performed better than the SOFA score and similarly to the MEDS score for predicting mortality in ED patients with severe sepsis and septic shock. These findings have implications for identifying and managing high-risk patients and for the design of clinical trials in sepsis. © 2014 by the Society for Academic Emergency Medicine.

Definition of the Mediterranean Diet; a Literature Review.

PubMed

Davis, Courtney; Bryan, Janet; Hodgson, Jonathan; Murphy, Karen

2015-11-05

Numerous studies over several decades suggest that following the Mediterranean diet (MedDiet) can reduce the risk of cardiovascular disease and cancer, and improve cognitive health. However, there are inconsistencies among methods used for evaluating and defining the MedDiet. Through a review of the literature, we aimed to quantitatively define the MedDiet by food groups and nutrients. Databases PubMed, MEDLINE, Science Direct, Academic Search Premier and the University of South Australia Library Catalogue were searched. Articles were included if they defined the MedDiet in at least two of the following ways: (1) general descriptive definitions; (2) diet pyramids/numbers of servings of key foods; (3) grams of key foods/food groups; and (4) nutrient and flavonoid content. Quantity of key foods and nutrient content was recorded and the mean was calculated. The MedDiet contained three to nine serves of vegetables, half to two serves of fruit, one to 13 serves of cereals and up to eight serves of olive oil daily. It contained approximately 9300 kJ, 37% as total fat, 18% as monounsaturated and 9% as saturated, and 33 g of fibre per day. Our results provide a defined nutrient content and range of servings for the MedDiet based on past and current literature. More detailed reporting amongst studies could refine the definition further.

Exact mean-energy expansion of Ginibre's gas for coupling constants Γ =2 ×(oddinteger)

NASA Astrophysics Data System (ADS)

Salazar, R.; Téllez, G.

2017-12-01

Using the approach of a Vandermonde determinant to the power Γ =Q2/kBT expansion on monomial functions, a way to find the excess energy Uexc of the two-dimensional one-component plasma (2DOCP) on hard and soft disks (or a Dyson gas) for odd values of Γ /2 is provided. At Γ =2 , the present study not only corroborates the result for the particle-particle energy contribution of the Dyson gas found by Shakirov [Shakirov, Phys. Lett. A 375, 984 (2011), 10.1016/j.physleta.2011.01.004] by using an alternative approach, but also provides the exact N -finite expansion of the excess energy of the 2DOCP on the hard disk. The excess energy is fitted to the ansatz of the form Uexc=K1N +K2√{N }+K3+K4/N +O (1 /N2) to study the finite-size correction, with Ki coefficients and N the number of particles. In particular, the bulk term of the excess energy is in agreement with the well known result of Jancovici for the hard disk in the thermodynamic limit [Jancovici, Phys. Rev. Lett. 46, 386 (1981), 10.1103/PhysRevLett.46.386]. Finally, an expression is found for the pair correlation function which still keeps a link with the random matrix theory via the kernel in the Ginibre ensemble [Ginibre, J. Math. Phys. 6, 440 (1965), 10.1063/1.1704292] for odd values of Γ /2 . A comparison between the analytical two-body density function and histograms obtained with Monte Carlo simulations for small systems and Γ =2 ,6 ,10 ,... shows that the approach described in this paper may be used to study analytically the crossover behavior from systems in the fluid phase to small crystals.

The validation and preference among different EAM potentials to describe the solid-liquid transition of aluminum

NASA Astrophysics Data System (ADS)

Jiang, Yewei; Luo, Jie; Wu, Yongquan

2017-06-01

Empirical potential is vital to the classic atomic simulation, especially for the study of phase transitions, as well as the solid-interface. In this paper, we attempt to set up a uniform procedure for the validation among different potentials before the formal simulation study of phase transitions of metals. Two main steps are involved: (1) the prediction of the structures of both solid and liquid phases and their mutual transitions, i.e. melting and crystallization; (2) the prediction of vital thermodynamic (the equilibrium melting point at ambient pressure) and dynamic properties (the degrees of superheating and undercooling). We applied this procedure to the testing of seven published embedded-atom potentials (MKBA (Mendelev et al 2008 Philos. Mag. 88 1723), MFMP (Mishin et al 1999 Phys. Rev. B 59 3393), MDSL (Sturgeon and Laird 2000 Phys. Rev. B 62 14720), ZM (Zope and Mishin 2003 Phys. Rev. B 68 024102), LEA (Liu et al 2004 Model. Simul. Mater. Sci. Eng. 12 665), WKG (Winey et al 2009 Model. Simul. Mater. Sci. Eng. 17 055004) and ZJW (Zhou et al 2004 Phys. Rev. B 69 144113)) for the description of the solid-liquid transition of Al. All the predictions of structure, melting point and superheating/undercooling degrees were compared with the experiments or theoretical calculations. Then, two of them, MKBA and MDSL, were proven suitable for the study of the solid-liquid transition of Al while the residuals were unqualified. However, potential MKBA is more accurate to predict the structures of solid and liquid, while MDSL works a little better in the thermodynamic and dynamic predictions of solid-liquid transitions.

In-medium jet evolution: interplay between broadening and decoherence effects. The XXVth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions

NASA Astrophysics Data System (ADS)

Apolinário, Liliana; Armesto, Néstor; Milhano, Guilherme; Salgado, Carlos A.

2016-12-01

The description of the modifications of the coherence pattern in a parton shower, in the presence of a QGP, has been actively addressed in recent studies. Among the several achievements, finite energy corrections, transverse momentum broadening due to medium interactions and interference effects between successive emissions have been extensively improved as they seem to be essential features for a correct description of the results obtained in heavy-ion collisions. In this work, based on the insights of our previous work [L. Apolinário, N. Armesto, J. G. Milhano, C. A. Salgado, Medium-induced gluon radiation and colour decoherence beyond the soft approximation, JHEP 1502 (2015) 119. arxiv:arXiv:1407.0599], we explore the physical interplay between broadening and decoherence, by generalising previous studies of medium-modifications of the antenna spectrum [Y. Mehtar-Tani, C. A. Salgado, K. Tywoniuk, Antiangular Ordering of Gluon Radiation in QCD Media, Phys. Rev. Lett. 106 (2011) 122002. arxiv:arXiv:1009.2965, J. Casalderrey-Solana, E. Iancu, Interference effects in medium-induced gluon radiation, JHEP 08 (2011) 015. arxiv:arXiv:1105.1760, Y. Mehtar-Tani, C. A. Salgado, K. Tywoniuk, The Radiation pattern of a QCD antenna in a dense medium, JHEP 10 (2012) 197. arxiv:arXiv:1205.5739] - so far restricted to the case where transverse motion is neglected. The result allow us to identify two quantities controlling the decoherence of a medium modified shower that can be used as building blocks for a successful future generation of jet quenching Monte Carlo simulators: a generalisation of the Δmed parameter of the works of [Y. Mehtar-Tani, C. A. Salgado, K. Tywoniuk, Antiangular Ordering of Gluon Radiation in QCD Media, Phys. Rev. Lett. 106 (2011) 122002. arxiv:arXiv:1009.2965, Y. Mehtar-Tani, C. A. Salgado, K. Tywoniuk, The Radiation pattern of a QCD antenna in a dense medium, JHEP 10 (2012) 197. arxiv:arXiv:1205.5739] - that controls the interplay between the transverse scale of the hard probe and the transverse resolution of the medium - and of the Δcoh in [L. Apolinário, N. Armesto, J. G. Milhano, C. A. Salgado, Medium-induced gluon radiation and colour decoherence beyond the soft approximation, JHEP 1502 (2015) 119. arxiv:arXiv:1407.0599] - that dictates the interferences between two emitters as a function of the transverse momentum broadening acquired by multiple scatterings with the medium.

Quantum Phases of Matter in Optical Lattices

DTIC Science & Technology

2015-06-30

doi: 10.1103/PhysRevA.89.013625 Hyungwon Kim, David A. Huse. Ballistic Spreading of Entanglement in a Diffusive Nonintegrable System, Physical...Review B, (07 2013): 0. doi: 10.1103/PhysRevB.88.014206 Lin Dong, Lei Jiang, Han Pu. Fulde–Ferrell pairing instability in spin–orbit coupled Fermi...PhysRevA.87.051603 Kuei Sun, C. J. Bolech. Pair tunneling, phase separation, and dimensional crossover in imbalanced fermionic superfluids in a coupled

Proposed Experiment in Two-Qubit Linear Optical Photonic Gates for Maximal Success Rates

DTIC Science & Technology

2012-01-01

Phys. Rev. A 72 032307 [10] Kwiat P G, Waks E White A G, Applebaum I and Eberhaard P E 1999 Phys. Rev. A 60 R773–6 [11] Barz S, Cronenberg G, Zeilinger ...17] Reck M, Zeilinger A, Bernstein H J and Bertani P 1994 Phys. Rev. Lett. 73 58 [18] Thompson M G, Politi A, Matthews J C F and O’Brien J L 2011 IET

Ultraviolet Photoionization Efficiency of the Vaporized Ionic Liquid 1-Butyl-3-Methylimidazolium Tricyanomethanide: Direct Detection of the Intact Ion Pair (Post Print)

DTIC Science & Technology

2012-09-21

Lovelock , K. R. J.; Satterly, C. J.; Villar-Garcia, I. J. Phys. Chem. Chem. Phys. 2007, 9, 982−990. (11) Strasser, D.; Goulay, F.; Kelkar, M. S.; Maginn, E...J.; Leone, S. R. J. Phys. Chem. A 2007, 111, 3191−3915. (12) Lovelock , K. R. J.; Deyko, A.; Corfield, J.-A.; Gooden, P. N.; Licence, P.; Jones, R. G

Addendum: New approach to the resummation of logarithms in Higgs-boson decays to a vector quarkonium plus a photon [Phys. Rev. D 95, 054018 (2017)

DOE PAGES

Bodwin, Geoffrey T.; Chung, Hee Sok; Ee, June-Haak; ...

2017-12-20

In this addendum to Phys. Rev. D 95, 054018 (2017) we recompute the rates for the decays of the Higgs boson to a vector quarkonium plus a photon, where the vector quarkonium is J/psi, Upsilon(1S) Upsilon(2S). We correct an error in the Abel-Pad'e summation formula that was used to carry out the evolution of the quarkonium light-cone distribution amplitude in Phys. Rev. D 95, 054018 (2017). We also correct an error in the scale of quarkonium wave function at the origin in Phys. Rev. D 95, 054018 (2017) and introduce several additional refinements in the calculation.

Analysis of photon count data from single-molecule fluorescence experiments

NASA Astrophysics Data System (ADS)

Burzykowski, T.; Szubiakowski, J.; Rydén, T.

2003-03-01

We consider single-molecule fluorescence experiments with data in the form of counts of photons registered over multiple time-intervals. Based on the observation schemes, linking back to works by Dehmelt [Bull. Am. Phys. Soc. 20 (1975) 60] and Cook and Kimble [Phys. Rev. Lett. 54 (1985) 1023], we propose an analytical approach to the data based on the theory of Markov-modulated Poisson processes (MMPP). In particular, we consider maximum-likelihood estimation. The method is illustrated using a real-life dataset. Additionally, the properties of the proposed method are investigated through simulations and compared to two other approaches developed by Yip et al. [J. Phys. Chem. A 102 (1998) 7564] and Molski [Chem. Phys. Lett. 324 (2000) 301].

Addendum: New approach to the resummation of logarithms in Higgs-boson decays to a vector quarkonium plus a photon [Phys. Rev. D 95, 054018 (2017)

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

Bodwin, Geoffrey T.; Chung, Hee Sok; Ee, June-Haak

In this addendum to Phys. Rev. D 95, 054018 (2017) we recompute the rates for the decays of the Higgs boson to a vector quarkonium plus a photon, where the vector quarkonium is J/psi, Upsilon(1S) Upsilon(2S). We correct an error in the Abel-Pad'e summation formula that was used to carry out the evolution of the quarkonium light-cone distribution amplitude in Phys. Rev. D 95, 054018 (2017). We also correct an error in the scale of quarkonium wave function at the origin in Phys. Rev. D 95, 054018 (2017) and introduce several additional refinements in the calculation.

Information sources for obesity prevention policy research: a review of systematic reviews.

PubMed

Hanneke, Rosie; Young, Sabrina K

2017-08-08

Systematic identification of evidence in health policy can be time-consuming and challenging. This study examines three questions pertaining to systematic reviews on obesity prevention policy, in order to identify the most efficient search methods: (1) What percentage of the primary studies selected for inclusion in the reviews originated in scholarly as opposed to gray literature? (2) How much of the primary scholarly literature in this topic area is indexed in PubMed/MEDLINE? (3) Which databases index the greatest number of primary studies not indexed in PubMed, and are these databases searched consistently across systematic reviews? We identified systematic reviews on obesity prevention policy and explored their search methods and citations. We determined the percentage of scholarly vs. gray literature cited, the most frequently cited journals, and whether each primary study was indexed in PubMed. We searched 21 databases for all primary study articles not indexed in PubMed to determine which database(s) indexed the highest number of these relevant articles. In total, 21 systematic reviews were identified. Ten of the 21 systematic reviews reported searching gray literature, and 12 reviews ultimately included gray literature in their analyses. Scholarly articles accounted for 577 of the 649 total primary study papers. Of these, 495 (76%) were indexed in PubMed. Google Scholar retrieved the highest number of the remaining 82 non-PubMed scholarly articles, followed by Scopus and EconLit. The Journal of the American Dietetic Association was the most-cited journal. Researchers can maximize search efficiency by searching a small yet targeted selection of both scholarly and gray literature resources. A highly sensitive search of PubMed and those databases that index the greatest number of relevant articles not indexed in PubMed, namely multidisciplinary and economics databases, could save considerable time and effort. When combined with a gray literature search and additional search methods, including cited reference searching and consulting with experts, this approach could help maintain broad retrieval of relevant studies while improving search efficiency. Findings also have implications for designing specialized databases for public health research.

Medicarpin, a Natural Pterocarpan, Heals Cortical Bone Defect by Activation of Notch and Wnt Canonical Signaling Pathways

PubMed Central

Gupta, Chandra Prakash; Kureel, Jyoti; Mansoori, Mohd Nizam; Shukla, Priyanka; John, Aijaz A.; Singh, Kavita; Purohit, Dipak; Awasthi, Pallavi; Singh, Divya; Goel, Atul

2015-01-01

We evaluated the bone regeneration and healing effect of Medicarpin (med) in cortical bone defect model that heals by intramembranous ossification. For the study, female Sprague–Dawley rats were ovariectomized and rendered osteopenic. A drill hole injury was generated in mid femoral bones of all the animals. Med treatment was commenced the day after and continued for 15 days. PTH was taken as a reference standard. Fifteen days post-treatment, animals were sacrificed. Bones were collected for histomorphometry studies at the injury site by micro-computed tomography (μCT) and confocal microscopy. RNA and protein was harvested from newly generated bone. For immunohistochemistry, 5μm sections of decalcified femur bone adjoining the drill hole site were cut. By μCT analysis and calcein labeling of newly generated bone it was found that med promotes bone healing and new bone formation at the injury site and was comparable to PTH in many aspects. Med treatment led to increase in the Runx-2 and osteocalcin signals indicating expansion of osteoprogenitors at the injury site as evaluated by qPCR and immunohistochemical localization. It was observed that med promoted bone regeneration by activating canonical Wnt and notch signaling pathway. This was evident by increased transcript and protein levels of Wnt and notch signaling components in the defect region. Finally, we confirmed that med treatment leads to elevated bone healing in pre-osteoblasts by co localization of beta catenin with osteoblast marker alkaline phosphatase. In conclusion, med treatment promotes new bone regeneration and healing at the injury site by activating Wnt/canonical and notch signaling pathways. This study also forms a strong case for evaluation of med in delayed union and non-union fracture cases. PMID:26657206

Medicarpin, a Natural Pterocarpan, Heals Cortical Bone Defect by Activation of Notch and Wnt Canonical Signaling Pathways.

PubMed

Dixit, Manisha; Raghuvanshi, Ashutosh; Gupta, Chandra Prakash; Kureel, Jyoti; Mansoori, Mohd Nizam; Shukla, Priyanka; John, Aijaz A; Singh, Kavita; Purohit, Dipak; Awasthi, Pallavi; Singh, Divya; Goel, Atul

2015-01-01

We evaluated the bone regeneration and healing effect of Medicarpin (med) in cortical bone defect model that heals by intramembranous ossification. For the study, female Sprague-Dawley rats were ovariectomized and rendered osteopenic. A drill hole injury was generated in mid femoral bones of all the animals. Med treatment was commenced the day after and continued for 15 days. PTH was taken as a reference standard. Fifteen days post-treatment, animals were sacrificed. Bones were collected for histomorphometry studies at the injury site by micro-computed tomography (μCT) and confocal microscopy. RNA and protein was harvested from newly generated bone. For immunohistochemistry, 5μm sections of decalcified femur bone adjoining the drill hole site were cut. By μCT analysis and calcein labeling of newly generated bone it was found that med promotes bone healing and new bone formation at the injury site and was comparable to PTH in many aspects. Med treatment led to increase in the Runx-2 and osteocalcin signals indicating expansion of osteoprogenitors at the injury site as evaluated by qPCR and immunohistochemical localization. It was observed that med promoted bone regeneration by activating canonical Wnt and notch signaling pathway. This was evident by increased transcript and protein levels of Wnt and notch signaling components in the defect region. Finally, we confirmed that med treatment leads to elevated bone healing in pre-osteoblasts by co localization of beta catenin with osteoblast marker alkaline phosphatase. In conclusion, med treatment promotes new bone regeneration and healing at the injury site by activating Wnt/canonical and notch signaling pathways. This study also forms a strong case for evaluation of med in delayed union and non-union fracture cases.

Mediterranean diet and metabolic syndrome in an urban population: the Athens Study.

PubMed

Gouveri, Evanthia T; Tzavara, Chara; Drakopanagiotakis, Fotios; Tsaoussoglou, Marina; Marakomichelakis, Georgios E; Tountas, Yannis; Diamantopoulos, Emmanuel J

2011-10-01

Previous studies demonstrated the beneficial impact of the Mediterranean diet (MedDiet) on metabolic syndrome (MetS). The aim of this study was to retrospectively investigate the association between MedDiet and MetS in a representative sample of the Athenian population in the early 1980s, when MetS had not been established as an entity yet. In a cross-sectional epidemiologic survey of cardiovascular disease (CVD), 2,074 randomly selected adults were examined: 900 men and 1,174 women (age, 46.9 ± 14.9 years). MetS was defined according to criteria of the National Cholesterol Education Program-Adult Treatment Panel III. A validated questionnaire concerning nutrition habits was administered, and MedDiet was assessed according to guidelines of the Division of Nutrition/Epidemiology, Athens University Medical School. Overall, 1,023 participants (49.3%) followed MedDiet (47.3% men, 52.0% women, P = .033) with similar rates across age groups (P = .337). MetS was diagnosed in 24.0% of those following MedDiet, compared with 27.9% of those not following it (P = .041). Participants with CVD or diabetes mellitus were less likely to follow MedDiet (43% vs 50%, P = .009). Multivariate analysis revealed that MedDiet is associated with a 20% reduction in MetS (odds ratio = 0.80, 95% confidence interval = 0.65-0.98), after adjustment for age, gender, smoking, light physical activity, serum levels of low-density lipoprotein cholesterol and γ-glutamyl transferase, diabetes mellitus, CVD, family history of hypertension, and/or hyperlipidemia. Results indicate that adherence to MedDiet may attenuate the prevalence of MetS and, consequently, the increasing burden of diabetes mellitus and CVD, especially in urban populations.

The Contrasting Role of the Mediator Subunit MED30 in the Progression of Bladder Cancer.

PubMed

Syring, Isabella; Weiten, Richard; Müller, Tim; Schmidt, Doris; Steiner, Susanne; Kristiansen, Glen; Müller, Stefan C; Ellinger, Jörg

2017-12-01

The Mediator complex is a key regulator of gene transcription, and several studies have demonstrated altered expression of particular subunits in diverse human diseases, especially cancer. To date, nothing is known about the role of MED30 in bladder cancer. We, therefore, performed an RNA expression and survival analysis of the subunit MED30 in 537 samples of bladder cancer by using the database cBioPortal. To validate these data on the protein level, we practiced immunohistochemical staining against MED30 on a tissue microarray containing 210 samples of all tumour stages and performed survival analyses. For functional analysis, the siRNA-mediated knockdown of MED30 was performed in the cell lines T24 and TCCSUP followed by proliferation, migration, and invasion assays. On the mRNA and protein levels, higher expression of MED30 is associated with better patient survival. In accordance with this, advanced T- and N-stages showed lower expression of MED30. In contrast, knockdown of MED30 led to reduction of the tumour parameters proliferation, migration, and invasion in the BCa cell lines. MED30 appears to be integrated in the progression of the urothelial tumour in the bladder. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Mediator MED23 regulates basal transcription in vivo via an interaction with P-TEFb.

PubMed

Wang, Wei; Yao, Xiao; Huang, Yan; Hu, Xiangming; Liu, Runzhong; Hou, Dongming; Chen, Ruichuan; Wang, Gang

2013-01-01

The Mediator is a multi-subunit complex that transduces regulatory information from transcription regulators to the RNA polymerase II apparatus. Growing evidence suggests that Mediator plays roles in multiple stages of eukaryotic transcription, including elongation. However, the detailed mechanism by which Mediator regulates elongation remains elusive. In this study, we demonstrate that Mediator MED23 subunit controls a basal level of transcription by recruiting elongation factor P-TEFb, via an interaction with its CDK9 subunit. The mRNA level of Egr1, a MED23-controlled model gene, is reduced 4-5 fold in Med23 (-/-) ES cells under an unstimulated condition, but Med23-deficiency does not alter the occupancies of RNAP II, GTFs, Mediator complex, or activator ELK1 at the Egr1 promoter. Instead, Med23 depletion results in a significant decrease in P-TEFb and RNAP II (Ser2P) binding at the coding region, but no changes for several other elongation regulators, such as DSIF and NELF. ChIP-seq revealed that Med23-deficiency partially reduced the P-TEFb occupancy at a set of MED23-regulated gene promoters. Further, we demonstrate that MED23 interacts with CDK9 in vivo and in vitro. Collectively, these results provide the mechanistic insight into how Mediator promotes RNAP II into transcription elongation.

Making and Executing Decisions for Safe and Independent Living (MED-SAIL): development and validation of a brief screening tool.

PubMed

Mills, Whitney L; Regev, Tziona; Kunik, Mark E; Wilson, Nancy L; Moye, Jennifer; McCullough, Laurence B; Naik, Aanand D

2014-03-01

Older adults prefer to remain in their own homes for as long as possible. The purpose of this article is to describe the development and preliminary validation of Making and Executing Decisions for Safe and Independent Living (MED-SAIL), a brief screening tool for capacity to live safely and independently in the community. Prospective preliminary validation study. Outpatient geriatrics clinic located in a community-based hospital. Forty-nine community-dwelling older adults referred to the clinic for a comprehensive capacity assessment. We examined internal consistency, criterion-based validity, concurrent validity, and accuracy of classification for MED-SAIL. The items included in MED-SAIL demonstrated internal consistency (5 items; α = 0.85). MED-SAIL was significantly correlated with the Independent Living Scales (r = 0.573, p ≤0.001) and instrumental activities of daily living (r = 0.440, p ≤0.01). The Mann-Whitney U test revealed significant differences between the no capacity and partial/full capacity classifications on MED-SAIL (U(48) = 60.5, Z = -0.38, p <0.0001). The area under the curve was 0.864 (95% confidence interval: 0.84-0.99). This study demonstrated the validity of MED-SAIL as a brief screening tool to identify older adults with impaired capacity for remaining safe and independent in their current living environment. MED-SAIL is useful tool for health and social service providers in the community for the purpose of referral for definitive capacity evaluation. Published by Elsevier Inc.

Dynamics of Turbulence-generated E × B Flows: Simulation and Theory

NASA Astrophysics Data System (ADS)

Hahm, T. S.

1998-11-01

Many magnetic confinement experiments have indicated that E × B shear can suppress turbulence and consequently lead to significant reduction of plasma transport.^1 It has been observed in flux-tube gyrofluid^2,3 and gyrokinetic^4 simulations that small radial scale fluctuating E × B flows driven by turbulence (often called radial modes,^3 or zonal flows) play a dominant role in regulating toroidal ITG (ion temperature gradient) turbulence. Furthermore, the radial modes with similar characteristics and significant impact on transport have been also observed in the recent global gyrokinetic simulations with improved numerical capabilities^5 as well as in edge turbulence simulations with a collisional poloidal flow damping.^6 In this work, we analyze turbulence and flow statistics from gyrofluid and gyrokinetic simulations and compare to various theoretical predictions. The observed radial modes contain significant components with radial scales and frequencies comparable to those of turbulence. While the fast time varying components (including Geodesic Acoustic Modes) contribute the most to the instantaneous E × B shearing rate, they are less influential in suppressing turbulence. The effective E × B shearing rate capturing this important physics is analytically derived and evaluated from the recent nonlinear simulation results. Its magnitude is much smaller than the instantaneous E × B shearing rate, but typically of the order of the decorrelation rate of the ambient turbulence. This is consistent with the reduced, not completely stabilized level of turbulence with broadened kr spectrum observed in simulations. Zonal flows are linearly stable, but can be generated either by incoherent emission of turbulence or by inverse cascade of spectrum yielding negative turbulent viscosity which is related to the Reynolds' stress.^7 Various analytical calculations and proposed mechanisms for zonal flow generation and saturation^7,8 will be tested numerically. Finally, the collisional damping of flows and its effect on transport will be studied via gyrokinetic simulations with momentum and energy conserving Fokker-Planck operator.^5 renewcommandthempfootnotefnsymbolmpfootnote footnotetext[1]This work supported by DOE contract DE-AC02-76-CHO-3073. footnotetext[2]In collaboration with M. A. BEER, Z. LIN, G. W. HAMMETT, W. W. LEE, and W. M. TANG. renewcommandthempfootnotearabicmpfootnote setcountermpfootnote0 footnotetext[1]K. H. Burrell, Phys. Plasmas 4, 1499 (1997); E. J. Synakowski, Plasma Phys. Control. Fusion, 40, 581 (1998). footnotetext[2]M. A. Beer, Ph.D. Thesis, Princeton University, 1995; G. W. Hammett et al., Plasma Phys. Control. Fusion, 35, 973 (1993) footnotetext[3]R. E. Waltz, G. D. Kerbel, and J. Milovich, Phys. Plasmas 1, 2229 (1994). footnotetext[4]A. M. Dimits et al., Phys. Rev. Lett. 77, 71 (1996). footnotetext[5]Z. Lin et al., To be submitted to Phys. Plasmas (1998). footnotetext[6]B. N. Rogers, J. F. Drake, and A. Zeiler, Submitted to Phys. Rev. Lett.(1998). footnotetext[7]P. H. Diamond and Y. B. Kim, Phys. Fluids B 3, 1626 (1991); P. H. Diamond, J. Fleischer, and F. L. Hinton, Presented at Transport Task Force Meeting (1998). footnotetext[8]M. N. Rosenbluth and F.L. Hinton, Phys. Rev. Lett. 80, 724 (1998).

Optimal Adherence to a Mediterranean Diet and High Muscular Fitness Are Associated with a Healthier Cardiometabolic Profile in Collegiate Students

PubMed Central

Correa-Bautista, Jorge Enrique; Ojeda-Pardo, Mónica Liliana; Sandoval-Cuellar, Carolina; González-Ruíz, Katherine; Prieto-Benavides, Daniel Humberto; Tordecilla-Sanders, Alejandra; Martinkėnas, Arvydas

2018-01-01

The aim of the study was to investigate the combined association of adherence to a Mediterranean diet (MedDiet) and muscular fitness (MF) with cardiometabolic health in collegiate students. The present cross-sectional analysis consisted of 1248 (714 females) healthy collegiate students (20.1 ± 2.7 years old). Adherence to a MedDiet was assessed by a KIDMED (Mediterranean Diet Quality Index) questionnaire. Standing broad jump, standing vertical jump, and isometric handgrip dynamometry were used as indicators of MF. The cardiometabolic profile was assessed using the following components: triglycerides, blood pressure, triglycerides, high-density lipoprotein (HDL)-cholesterol, glucose, and waist circumference. Analysis of covariance shows a significant difference in the cardiometabolic profile of both genders between the high MF/low MedDiet and high MF/optimal MedDiet groups, and the low MF/low MedDiet and low MF/optimal MedDiet groups (p < 0.001). No difference was found on cardiometabolic profile between high MF/optimal MedDiet and high MF/low MedDiet, both in males and females. Additionally, logistic regression shows that both female (odds ratio (OR) = 2.01; 95% confidence interval (CI): (1.8–3.7); p = 0.02) and male (OR = 3.38; 95% CI: (1.9–5.8); p < 0.001) participants in the optimal MedDiet/high MF group had the highest odds of expressing a healthier cardiometabolic profile as compared to those in the low MF/low MedDiet group. In conclusion, a combination of high MF levels and optimal adherence to a MedDiet is associated with a healthier cardiometabolic profile; however, high MF levels seem to circumvent the deleterious effects of having a low adherence to a MedDiet. PMID:29677099

Optimal Adherence to a Mediterranean Diet and High Muscular Fitness Are Associated with a Healthier Cardiometabolic Profile in Collegiate Students.

PubMed

Ramírez-Vélez, Robinson; Correa-Bautista, Jorge Enrique; Ojeda-Pardo, Mónica Liliana; Sandoval-Cuellar, Carolina; García-Hermoso, Antonio; Carrillo, Hugo Alejandro; González-Ruíz, Katherine; Prieto-Benavides, Daniel Humberto; Tordecilla-Sanders, Alejandra; Martinkėnas, Arvydas; Agostinis-Sobrinho, César

2018-04-20

The aim of the study was to investigate the combined association of adherence to a Mediterranean diet (MedDiet) and muscular fitness (MF) with cardiometabolic health in collegiate students. The present cross-sectional analysis consisted of 1248 (714 females) healthy collegiate students (20.1 ± 2.7 years old). Adherence to a MedDiet was assessed by a KIDMED (Mediterranean Diet Quality Index) questionnaire. Standing broad jump, standing vertical jump, and isometric handgrip dynamometry were used as indicators of MF. The cardiometabolic profile was assessed using the following components: triglycerides, blood pressure, triglycerides, high-density lipoprotein (HDL)-cholesterol, glucose, and waist circumference. Analysis of covariance shows a significant difference in the cardiometabolic profile of both genders between the high MF/low MedDiet and high MF/optimal MedDiet groups, and the low MF/low MedDiet and low MF/optimal MedDiet groups ( p < 0.001). No difference was found on cardiometabolic profile between high MF/optimal MedDiet and high MF/low MedDiet, both in males and females. Additionally, logistic regression shows that both female (odds ratio (OR) = 2.01; 95% confidence interval (CI): (1.8⁻3.7); p = 0.02) and male (OR = 3.38; 95% CI: (1.9⁻5.8); p < 0.001) participants in the optimal MedDiet/high MF group had the highest odds of expressing a healthier cardiometabolic profile as compared to those in the low MF/low MedDiet group. In conclusion, a combination of high MF levels and optimal adherence to a MedDiet is associated with a healthier cardiometabolic profile; however, high MF levels seem to circumvent the deleterious effects of having a low adherence to a MedDiet.

Effects of the Mediterranean Diet before and after Weight Loss on Eating Behavioral Traits in Men with Metabolic Syndrome.

PubMed

Carbonneau, Élise; Royer, Marie-Michelle; Richard, Caroline; Couture, Patrick; Desroches, Sophie; Lemieux, Simone; Lamarche, Benoît

2017-03-19

The objective of this study was to investigate the impact of the Mediterranean diet (MedDiet) consumed before and after weight loss on eating behavioral traits as measured by the Three-Factor Eating Questionnaire (TFEQ) in men with metabolic syndrome (MetS). In this fixed sequence study, 19 men with MetS (National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATPIII) criteria), aged between 24 and 62 years, first consumed a five-week standardized North American control diet followed by a five-week MedDiet, both under weight-maintaining controlled-feeding conditions. This was followed by a 20-week caloric restriction weight loss period in free-living conditions, without specific recommendations towards adhering to the principles of the MedDiet. Participants were finally subjected to a final five-week MedDiet phase under isoenergetic controlled-feeding conditions. The MedDiet before weight loss had no impact on eating behavioral traits. Body weight reduction by caloric restriction (-10.2% of initial weight) was associated with increased cognitive restraint ( p < 0.0001) and with reduced disinhibition ( p = 0.02) and susceptibility to hunger ( p = 0.01). Feeding the MedDiet for five weeks under isoenergetic conditions after the weight loss phase had no further impact on eating behavioral traits. Results of this controlled-feeding study suggest that consumption of the MedDiet per se has no effect on eating behavioral traits as measured by TFEQ, unless it is combined with significant weight loss.

The Mediator Complex Subunits MED14, MED15, and MED16 Are Involved in Defense Signaling Crosstalk in Arabidopsis.

PubMed

Wang, Chenggang; Du, Xuezhu; Mou, Zhonglin

2016-01-01

Mediator is a highly conserved protein complex that functions as a transcriptional coactivator in RNA polymerase II (RNAPII)-mediated transcription. The Arabidopsis Mediator complex has recently been implicated in plant immune responses. Here, we compared salicylic acid (SA)-, methyl jasmonate (MeJA)-, and the ethylene (ET) precursor 1-aminocyclopropane-1-carboxylic acid (ACC)-induced defense and/or wound-responsive gene expression in 14 Arabidopsis Mediator subunit mutants. Our results show that MED14, MED15, and MED16 are required for SA-activated expression of the defense marker gene PATHOEGNESIS-RELATED GENE1 , MED25 is required for MeJA-induced expression of the wound-responsive marker gene VEGATATIVE STORAGE PROTEIN1 ( VSP1 ), MED8, MED14, MED15, MED16, MED18, MED20a, MED25, MED31, and MED33A/B (MED33a and MED33B) are required for MeJA-induced expression of the defense maker gene PLANT DEFENSIN1.2 ( PDF1.2 ), and MED8, MED14, MED15, MED16, MED25, and MED33A/B are also required for ACC-triggered expression of PDF1.2 . Furthermore, we investigated the involvement of MED14, MED15, and MED16 in plant defense signaling crosstalk and found that MED14, MED15, and MED16 are required for SA- and ET-mediated suppression of MeJA-induced VSP1 expression. This result suggests that MED14, MED15, and MED16 not only relay defense signaling from the SA and JA/ET defense pathways to the RNAPII transcription machinery, but also fine-tune defense signaling crosstalk. Finally, we show that MED33A/B contributes to the necrotrophic fungal pathogen Botrytis cinerea- induced expression of the defense genes PDF1.2, HEVEIN-LIKE , and BASIC CHITINASE and is required for full-scale basal resistance to B. cinerea , demonstrating a positive role for MED33 in plant immunity against necrotrophic fungal pathogens.

The performances of standard and ResMed masks during bag-valve-mask ventilation.

PubMed

Lee, Hyoung Youn; Jeung, Kyung Woon; Lee, Byung Kook; Lee, Seung Joon; Jung, Yong Hun; Lee, Geo Sung; Min, Yong Il; Heo, Tag

2013-01-01

A tight mask seal is frequently difficult to obtain and maintain during single-rescuer bag-valve-mask (BVM) ventilation. The ResMed mask (Bella Vista, NSW, Australia) is a continuous-positive-airway-pressure mask (CM) designed for noninvasive ventilation. In this study, we compared the ventilation performances of a standard mask (SM) and a ResMed CM using a simulation manikin in an out-of-hospital single-rescuer BVM ventilation scenario. Thirty emergency medical technicians (EMTs) performed two 2-minute attempts to ventilate a simulation manikin using BVM ventilation, alternatively, with the SM or the ResMed CM in a randomized order. Ventilation parameters including tidal volume and peak airway pressure were measured using computer analysis software connected to the simulation manikin. Successful volume delivery was defined as delivery of 440-540 mL of tidal volume in accord with present cardiopulmonary resuscitation guidelines. BVM ventilation using the ResMed CM produced higher mean (± standard deviation) tidal volumes (452 ± 50 mL vs. 394 ± 113 mL, p = 0.014) and had a higher proportion of successful volume deliveries (65.3% vs. 26.7%, p < 0.001) than that using the SM. Peak airway pressure was higher in BVM ventilation using the ResMed CM (p = 0.035). Stomach insufflation did not occur during either method. Twenty-nine of the participants (96.7%) preferred BVM ventilation using the ResMed CM. BVM ventilations using ResMed CM resulted in a significantly higher proportion of successful volume deliveries meeting the currently recommended range of tidal volume. Clinical studies are needed to determine the value of the ResMed CM for BVM ventilation.

Finding the right doctoral thesis - an innovative research fair for medical students.

PubMed

Steffen, Julius; Grabbert, Markus; Pander, Tanja; Gradel, Maximilian; Köhler, Lisa-Maria; Fischer, Martin R; von der Borch, Philip; Dimitriadis, Konstantinos

2015-01-01

The importance of research, as promoted by the CanMEDS framework, is widely acknowledged. Many medical students in Germany work on a research project as part of their doctoral thesis whilst still going to medical school. However, a significant amount of projects are abandoned unfinished, which leads to substantial wastage of resources. One reason for this is an information deficit concerning undergraduate research projects. To counteract this, we introduced an annual event at LMU Munich called DoktaMed with more than 600 visitors each year. It combines medical convention and research fair including keynote lectures, workshops and poster sessions as well as an exhibition of research groups and institutes. DoktaMed is a peer-to-peer event organized by a team of 40 students. A needs analysis before its implementation underlined the information deficit as a possible cause for the high rate of abandoned projects. In the annual evaluation, visitors of DoktaMed rate the event with an average grade of 2.1 on a six-level Likert scale (n=558, SD=1.06, with "1=very good", "6=poor"). They stated to now feel better informed about the topic and regarded visiting DoktaMed as a worthwhile investment of time. Students are generally satisfied with the event and feel better informed after visiting DoktaMed. However, many students never visit DoktaMed for various reasons. A possible improvement would be to present a greater number of clinical studies in addition to the laboratory work that DoktaMed focuses on now. Evaluation after six years of DoktaMed is very promising. Visitors seem to be better informed. Nevertheless there is space for improvement in order to get more students and more faculty members involved. More studies are needed to assess long-term effects.

Distributed learning or medical tourism? A Canadian residency program's experience in global health.

PubMed

Kelly, Kate; McCarthy, Anne; McLean, Laurie

2015-01-01

Global health experiences (GHEs) are becoming increasingly prevalent in surgical residency education. Although it may seem intuitive that participation in GHEs develops CanMEDS competencies, this has not been studied in depth in surgery. The purpose of this study is (1) to explore if and how otolaryngology-head and neck surgery (OHNS) resident participation in GHEs facilitates the development of CanMEDS competencies and (2) to develop an OHNS GHE tool to facilitate the integration of CanMEDS into GHE participation and evaluation. An online survey explored the GHEs of current and past OHNS residents in Canada. Based on the data collected and a literature review, a foundational tool was then created to (1) enable OHNS residents to structure their GHEs into CanMEDS-related learning objectives and (2) enable OHNS program directors to more effectively evaluate residents' GHEs with respect to CanMEDS competencies. Participants' GHEs varied widely. These experiences often contributed informally to the development of several CanMEDS competencies. However, few residents had concrete objectives, rarely were CanMEDS roles clearly incorporated, and most residents were not formally evaluated during their experience. Residents felt they achieved greater learning when predeparture objectives and postexperience reflections were integrated into their GHEs. Although GHEs vary widely, they can serve as valuable forums for developing CanMEDS competencies among participating residents. Without clear objectives that adhere to the CanMEDS framework or formal assessment methods however, residents in GHEs risk becoming medical tourists. The use of an objective and evaluation tool may facilitate the creation of predeparture learning objectives, encourage self-reflection on their GHE, and better enable program directors to evaluate residents participating in GHEs. Copyright © 2015 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Retrieving Clinical Evidence: A Comparison of PubMed and Google Scholar for Quick Clinical Searches

PubMed Central

Bejaimal, Shayna AD; Sontrop, Jessica M; Iansavichus, Arthur V; Haynes, R Brian; Weir, Matthew A; Garg, Amit X

2013-01-01

Background Physicians frequently search PubMed for information to guide patient care. More recently, Google Scholar has gained popularity as another freely accessible bibliographic database. Objective To compare the performance of searches in PubMed and Google Scholar. Methods We surveyed nephrologists (kidney specialists) and provided each with a unique clinical question derived from 100 renal therapy systematic reviews. Each physician provided the search terms they would type into a bibliographic database to locate evidence to answer the clinical question. We executed each of these searches in PubMed and Google Scholar and compared results for the first 40 records retrieved (equivalent to 2 default search pages in PubMed). We evaluated the recall (proportion of relevant articles found) and precision (ratio of relevant to nonrelevant articles) of the searches performed in PubMed and Google Scholar. Primary studies included in the systematic reviews served as the reference standard for relevant articles. We further documented whether relevant articles were available as free full-texts. Results Compared with PubMed, the average search in Google Scholar retrieved twice as many relevant articles (PubMed: 11%; Google Scholar: 22%; P<.001). Precision was similar in both databases (PubMed: 6%; Google Scholar: 8%; P=.07). Google Scholar provided significantly greater access to free full-text publications (PubMed: 5%; Google Scholar: 14%; P<.001). Conclusions For quick clinical searches, Google Scholar returns twice as many relevant articles as PubMed and provides greater access to free full-text articles. PMID:23948488

Alignment and pulse-duration effects in two-photon double ionization of H2 by femtosecond XUV laser pulses

NASA Astrophysics Data System (ADS)

Guan, Xiaoxu; Bartschat, Klaus; Schneider, Barry I.; Koesterke, Lars

2014-10-01

We present calculations for the dependence of the two-photon double ionization (DI) of H2 on the relative orientation of the linear laser polarization to the internuclear axis and the length of the pulse. We use the fixed-nuclei approximation at the equilibrium distance of 1.4 a0, where a0=0.529 ×10-10m is the Bohr radius. Central photon energies cover the entire direct DI domain from 26.5 to 34.0 eV. In contrast to the parallel geometry studied earlier [X. Guan, K. Bartschat, B. I. Schneider, and L. Koesterke, Phys. Rev. A 83, 043403 (2011), 10.1103/PhysRevA.83.043403], the effect of the pulse duration is almost negligible for the case when the two axes are perpendicular to each other. This is a consequence of the symmetry rules for dipole excitation in the two cases. In the parallel geometry, doubly excited states of 1Σu+ symmetry affect the cross section, while in the perpendicular geometry only much longer-lived 1Πu states are present. This accounts for the different convergence patterns observed in the calculated cross sections as a function of the pulse length. When the photon energy approaches the threshold of sequential DI, a sharp increase of the generalized total cross section (GTCS) with increasing pulse duration is also observed in the perpendicular geometry, very similar to the case of the molecular axis being oriented along the laser polarization direction. Our results differ from those of Colgan et al. [J. Colgan, M. S. Pindzola, and F. Robicheaux, J. Phys. B 41, 121002 (2008), 10.1088/0953-4075/41/12/121002] and Morales et al. [F. Morales, F. Martín, D. A. Horner, T. N. Rescigno, and C. W. McCurdy, J. Phys. B 42, 134013 (2009), 10.1088/0953-4075/42/13/134013], but are in excellent agreement with the GTCSs of Simonsen et al. [A. S. Simonsen, S. A. Sørngård, R. Nepstad, and M. Førre, Phys. Rev. A 85, 063404 (2012), 10.1103/PhysRevA.85.063404] over the entire domain of direct DI.

Comparing conditions for macrorealism: Leggett-Garg inequalities versus no-signaling in time

NASA Astrophysics Data System (ADS)

Halliwell, J. J.

2017-07-01

We consider two different types of conditions which were proposed to test macrorealism in the context of a system described by a single dichotomic variable Q . This is the view that a macroscopic system evolving in time possesses definite properties which can be determined without disturbing the future or past state. The Leggett-Garg (LG) inequalities, the most commonly studied test, are only necessary conditions for macrorealism, but, building on earlier work J. J. Halliwell, Phys. Rev. A 93, 022123 (2016), 10.1103/PhysRevA.93.022123, it is shown that when the four three-time LG inequalities are augmented with a certain set of two-time inequalities also of the LG form, Fine's theorem applies and these augmented conditions are then both necessary and sufficient. A comparison is carried out with a very different set of necessary and sufficient conditions for macrorealism, namely the no-signaling in time (NSIT) conditions proposed by J. Kofler and C. Brukner, Phys. Rev. A 87, 052115 (2013), 10.1103/PhysRevA.87.052115 and L. Clemente and J. Kofler, Phys. Rev. A 91, 062103 (2015), 10.1103/PhysRevA.91.062103, which ensure that all probabilities for Q at one and two times are independent of whether earlier or intermediate measurements are made in a given run, and do not require (but imply) the LG inequalities. We argue that tests based on the LG inequalities have the form of very weak classicality conditions and can be satisfied in the face of moderate interference effects, but those based on NSIT conditions have the form of much stronger coherence witness conditions, satisfied only for zero interference. The two tests differ in their implementation of noninvasive measurability and so are testing different notions of macrorealism: the augmented LG tests are indirect, entailing a combination of the results of different experiments with only compatible quantities measured in each experimental run, in close analogy with Bell tests, and are primarily tests for macrorealism per se; in contrast, the NSIT tests entail sequential measurements of incompatible quantities and are primarily tests for noninvasiveness.

Physics of the spin gap in the S=1/2 Heisenberg antiferromagnet on kagome

NASA Astrophysics Data System (ADS)

Tchernyshyov, Oleg

2009-03-01

A combination of low spin and strong frustration makes the S=1/2 Heisenberg antiferromagnet on kagome a likely candidate for an unusual ground state and elementary excitations. Exact-diagonalization studies [1] on finite clusters point to a lack of magnetic order in the ground state and to an energy gap of order J/20 for S=1 excitations. The exact nature of the ground state and elementary excitations remains a subject of vigorous debate. Among the proposed ground states are chiral [2] and non-chiral [3] spin liquids and a valence-bond crystal (VBC) [4-5]; spin excitations range from deconfined spinons with a Bose [6] or Fermi statistics [2-3] to magnons [7]. We show that the system behaves as a collection of spinons, quasiparticles with S=1/2 and Fermi statistics, whose motion disturbs valence-bond order. Attraction between spinons, mediated by exchange, binds them into small, massive pairs of S=0 with a binding energy of 0.06 J [8]. The pair formation strongly suppresses the motion of individual spinons and makes the survival of the Singh-Huse VBC plausible. A spin excitation amounts to breaking up a pair into two (nearly) free spinons with S=1. The survival of the VBC is expected to lead to spinon confinement; however, small energy differences between various valence-bond configurations would make the confinement length large. [4pt] [1] Ch. Waldtmann et al., Eur. Phys. J. B 2, 510 (1998).[0pt] [2] J. B. Marston and C. Zeng, J. Appl. Phys. 69, 5962 (1991).[0pt] [3] M. B. Hastings, Phys. Rev. B 63, 014413 (2000).[0pt] [4] P. Nikolic and T. Senthil, Phys. Rev. B 68, 214415 (2003).[0pt] [5] R. R. P. Singh and D. A. Huse, Phys. Rev. B 76, 180407 (2007).[0pt] [6] S. Sachdev, Phys. Rev. B 45, 12377 (1992).[0pt] [7] R. R. P. Singh and D. A. Huse, arXiv:0801.2735. [0pt] [8] Z. Hao and O. Tchernyshyov, the subsequent talk.

Sign Changes in the Electric Dipole Moment of Excited States in Rubidium-Alkaline Earth Diatomic Molecules

NASA Astrophysics Data System (ADS)

Pototschnig, Johann V.; Lackner, Florian; Hauser, Andreas W.; Ernst, Wolfgang E.

2015-06-01

In a recent series of combined experimental and theoretical studies we investigated the ground state and several excited states of the Rb-alkaline earth molecules RbSr and RbCa. The group of alkali-alkaline earth (AK-AKE) molecules has drawn attention for applications in ultracold molecular physics and the measurement of fundamental constants due to their large permanent electric and magnetic dipole moments in the ground state. These properties should allow for an easy manipulation of the molecules and simulations of spin models in optical lattices. In our studies we found that the permanent electric dipole moment points in different directions for certain electronically excited states, and changes the sign in some cases as a function of bond length. We summarize our results, give possible causes for the measured trends in terms of molecular orbital theory and extrapolate the tendencies to other combinations of AK and AKE - elements. F. Lackner, G. Krois, T. Buchsteiner, J. V. Pototschnig, and W. E. Ernst, Phys. Rev. Lett., 2014, 113, 153001; G. Krois, F. Lackner, J. V. Pototschnig, T. Buchsteiner, and W. E. Ernst, Phys. Chem. Chem. Phys., 2014, 16, 22373; J. V. Pototschnig, G. Krois, F. Lackner, and W. E. Ernst, J. Chem. Phys., 2014, 141, 234309 J. V. Pototschnig, G. Krois, F. Lackner, and W. E. Ernst, J. Mol. Spectrosc., in Press (2015), doi:10.1016/j.jms.2015.01.006 M. Kajita, G. Gopakumar, M. Abe, and M. Hada, J. Mol. Spectrosc., 2014, 300, 99-107 A. Micheli, G. K. Brennen, and P. Zoller, Nature Physics, 2006, 2, 341-347