Pentapeptide-repeat proteins that act as topoisomerase poison resistance factors have a common dimer interface

International Nuclear Information System (INIS)

Vetting, Matthew W.; Hegde, Subray S.; Zhang, Yong; Blanchard, John S.

2011-01-01

The pentapeptide repeat protein AlbG, provides self-resistance to the nonribosomally encoded hybrid polyketide-peptide termed albicidin. Analysis of the AlbG three-dimensional structure and the sequences of other pentapeptide repeat proteins that confer resistance to topiosomerase poisons suggests they have a similar dimer interface which may be critical to their interaction with topoisomerases. The protein AlbG is a self-resistance factor against albicidin, a nonribosomally encoded hybrid polyketide-peptide with antibiotic and phytotoxic properties produced by Xanthomonas albilineans. Primary-sequence analysis indicates that AlbG is a member of the pentapeptide-repeat family of proteins (PRP). The structure of AlbG from X. albilineans was determined at 2.0 Å resolution by SAD phasing using data collected from a single trimethyllead acetate derivative on a home source. AlbG folds into a right-handed quadrilateral β-helix composed of approximately eight semi-regular coils. The regularity of the β-helix is blemished by a large loop/deviation in the β-helix between coils 4 and 5. The C-terminus of the β-helix is capped by a dimerization module, yielding a dimer with a 110 Å semi-collinear β-helical axis. This method of dimer formation appears to be common to all PRP proteins that confer resistance to topoisomerase poisons and contrasts with most PRP proteins, which are typically monomeric

Untitled

Indian Academy of Sciences (India)

Total nitrogen in milligrams at the end of ten days in each fias. - - - - - -. ; Nitrogen after i0 day's : Nitrogen Average of gait as: to begin the three. --------|-- i. ss are : 0.67 0.66 ... Asiy Solution 66 0.66 ( 0.66 f. 2. Ashby solution and rice root le y extract . . 0.76 0.84 0-87 0.82 n : 3. Ashby solution and rice root grana & 8 . . 5.24 6.29 ...

International Space Station Systems Engineering. Case Study

Science.gov (United States)

2010-01-01

negotiators to move beyond an impasse.108  Don’t be so ready to chase revolutionary designs over evolutionary designs. A key lesson from Russian...112 2002 Oct. 7 2002 Oct. 18 9A S1 truss delivery Jeffrey S. Ashby, Pamela A. Melroy, David A. Wolf, Piers J. Sellers, Sandra H. Magnus , Fyodor...2002 Oct. 18 9A S1 truss delivery Jeffrey S. Ashby, Pamela A. Melroy, David A. Wolf, Piers J. Sellers, Sandra H. Magnus , Fyodor N. Yurchikhin

Hip and groin pain in sub-elite South African footballers | Dowson ...

African Journals Online (AJOL)

Background. Groin injuries are common in football. This can be attributed to the nature of the sport involving rapid accelerations, decelerations, abrupt directional changes and kicking. Groin injuries require lengthy rehabilitation times and predispose players to further injuries. Previous groin injury is a risk factor for future ...

Work Loop and Ashby Charts of Active Materials

Science.gov (United States)

2013-10-17

adaptive optics, robotics, etc.   Examples include  aircrafts  with morphing wings to optimize flight conditions, expandable stents  for use in medical...study of  artificial muscles based on carbon nanotube  aerogel  sheets reported actuation strain of up to  220%,  isometric  force of up  to 3.2 MPa and

77 FR 49799 - Medicare and Medicaid Programs; Quarterly Listing of Program Issuances-April Through June 2012

Science.gov (United States)

2012-08-17

... Regarding Lori Ashby (410) 786-6322 National Coverage Provisions. XI National Oncologic Stuart Caplan, RN... Caplan, RN, (410) 786-8564 Positron Emission MAS. Tomography for Dementia Trials. All Other Information...

76 FR 78267 - Medicare and Medicaid Programs; Quarterly Listing of Program Issuances-July Through September 2011

Science.gov (United States)

2011-12-16

... Ashby (410) 786-6322 Coverage Provisions. XI National Oncologic Positron Emission Stuart Caplan, RN, MAS... Tillman, RN, MAS (410) 786-9252 Facilities. XV Fluorodeoxyglucose Positron Emission Stuart Caplan, RN, MAS...

STS-93: Crew Watches the Installation of Chandra's Solar Panel in the VPF

Science.gov (United States)

1999-01-01

The crew (Commander Eileen M. Collins, Pilot Jeffrey S. Ashby, Mission Specialists Steven A. Hawley, Catherine G. Coleman, and Michael Tognini) are dressed in cleanroom suits while overseeing the solar panel installation.

Ammonia in simulated Hanford double-shell tank wastes: Solubility and effects on surface tension

International Nuclear Information System (INIS)

Norton, J.D.; Pederson, L.R.

1994-09-01

Radioactive and wastes left from defense materials production activities are temporarily stored in large underground tanks at the Hanford Site in south central Washington State (Tank Waste Science Panel 1991). Some of these wastes are in the form of a thick slurry (''double-shell slurry'') containing sodium nitrate, sodium nitrite, sodium aluminate, sodium hydroxide, sodium carbonate, organic complexants and buffering agents, complexant fragments and other minor components (Herting et al. 1992a; Herting et al. 1992b; Campbell et al. 1994). As a result of thermal and radiolytic processes, a number of gases are known to be produced by some of these stored wastes, including ammonia, nitrous oxide, nitrogen, hydrogen, and methane (Babad et al. 1991; Ashby et al. 1992; Meisel et al. 1993; Ashby et al. 1993; Ashby et al. 1994; Bryan et al. 1993; US Department of Energy 1994). Before the emplacement of a mixer pump, these gases were retained in and periodically released from Tank 241-SY-101, a double-shell tank at the Hanford Site (Babad et al. 1992; US Department of Energy 1994). Gases are believed to be retained primarily in the form of bubbles attached to solid particles (Bryan, Pederson, and Scheele 1992), with very little actually dissolved in the liquid. Ammonia is an exception. The relation between the concentration of aqueous ammonia in such concentrated, caustic mixtures and the ammonia partial pressure is not well known, however

Sintering diagrams of UO2

International Nuclear Information System (INIS)

Mohan, A.; Soni, N.C.; Moorthy, V.K.

1979-01-01

Ashby's method (see Acta Met., vol. 22, p. 275, 1974) of constructing sintering diagrams has been modified to obtain contribution diagrams directly from the computer. The interplay of sintering variables and mechanisms are studied and the factors that affect the participation of mechanisms in UO 2 are determined. By studying the physical properties, it emerges that the order of inaccuracies is small in most cases and do not affect the diagrams. On the other hand, even a 10% error in activation energies, which is quite plausible, would make a significant difference to the diagram. The main criticism of Ashby's approach is that the numerous properties and equations used, communicate their inaccuracies to the diagrams and make them unreliable. The present study has considerably reduced the number of factors that need to be refined to make the sintering diagrams more meaningful. (Auth.)

75 FR 70067 - Notice of Request for Reinstatement of Previously Approved Information Collection

Science.gov (United States)

2010-11-16

... address for which the public should request further information related to the relevant Information... Request for Reinstatement of Previously Approved Information Collection ACTION: Notice; Correction SUMMARY... INFORMATION CONTACT: Robert C. Ashby, Office of the Secretary, Office of Assistant General Counsel for...

40 CFR 81.142 - Central Massachusetts Intrastate Air Quality Control Region.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Central Massachusetts Intrastate Air Quality Control Region. 81.142 Section 81.142 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...: Township—Ashburnham, Ashby, Athol, Auburn, Barre, Berlin, Blackstone, Boylston, Brookfield, Charlton...

Occurrence of Xanthomonas campestris pv. campestris (Pammel, 1895) Dowson 1939, on brassicas in Montenegro

OpenAIRE

Radunović Dragana; Balaž Jelica

2012-01-01

Brassicas form the most important group of vegetable crops in Montenegro. The cabbage (Brassica oleracea var. capitata) is most commonly grown, although other brassicas, particularly kale, Brussels sprout, cauliflower and broccoli, have been increasingly produced since recently. One of the specialties of vegetable production in Montenegro is growing of collard (Brassica oleracea var. acephala), which is the simplest variety of the Brassica oleracea species ...

Comparative Service Quality Metrics in Regular and Nonregular Undergraduate Marketing Programs: Implications for Marketing Education and Professionalism

Science.gov (United States)

Okpara, Gazie S.; Agu, Agu G.

2017-01-01

Nonregular higher education in Nigeria became an integral part of the university manpower development since 1960, when the Ashby Commission recommended establishing evening degree programs. These ubiquitous programs have contributed to national capacity-building and remain relatively unmonitored by the National Universities Commission. This…

The Pinning by Particles of Low and High Angle Grain Boundaries during Grain Growth

DEFF Research Database (Denmark)

Tweed, C.J.; Ralph, B.; Hansen, Niels

1984-01-01

A study has been made using transmission electron microscopy of the pinning of grain boundaries in aluminium during grain growth by fine dispersions of alumina particles. The boundary parameters have been determined with precision and the pinning effects measured using an approach due to Ashby...

Reviews | Feinauer | Lexikos

African Journals Online (AJOL)

Jonathan Crowther (Editor), Kathryn Kavanagh (Assistant Editor) and. Michael Ashby (Phonetics Editor). Oxford Advanced Learner's Dictionary of Current English, 5th edition· (New International Students' Edition) 1995, x + 1428 pp. ISBN 0-19-431423-5. Oxford: Oxford University Press. Price R54,95.

78 FR 56710 - Agency Information Collection Activities: Submission for OMB Review; Comment Request

Science.gov (United States)

2013-09-13

.... Type of Information Collection Request: Reinstatement without change of a previously approved... Lori Ashby at 410-786-6322.) 2. Type of Information Collection Request: Reinstatement with change of a... provide coverage for carotid artery stenting (CAS) with embolic protection for patients at high risk for...

Influence of ageing, inclusions and voids on ductile fracture ...

Indian Academy of Sciences (India)

Unknown

The strain hardening capacity has a marked effect on void size, and is an indicator of fracture .... a model of ductile failure based on the concept that the critical step in the .... Ashby M F, Gandhi C and Taplin D M R 1979 Acta Metal. 27. 699.

Due Process in Dual Process: Model-Recovery Simulations of Decision-Bound Strategy Analysis in Category Learning

Science.gov (United States)

Edmunds, Charlotte E. R.; Milton, Fraser; Wills, Andy J.

2018-01-01

Behavioral evidence for the COVIS dual-process model of category learning has been widely reported in over a hundred publications (Ashby & Valentin, 2016). It is generally accepted that the validity of such evidence depends on the accurate identification of individual participants' categorization strategies, a task that usually falls to…

75 FR 28492 - Suspension of Community Eligibility

Science.gov (United States)

2010-05-21

... insurance in available in SFHAs community Region I Massachusetts: Acton, Town of, Middlesex 250176 March 24... of, 250177 January 16, 1974, ......*do Do. Middlesex County. Emerg; July 5, 1982, Reg; June 4, 2010, Susp. Ashby, Town of, Middlesex 250178 January 31, 1996, .......do Do. County. Emerg; August 1, 1996...

Induction of mutations in citrus for the development of resistance to Xanthomonas citri (Hasse) Dowson

International Nuclear Information System (INIS)

Zubrzycki, H.M.; Diamante de Zubrzycki, A.

1982-01-01

With the aim of obtaining resistance to Xanthomonas citri in citrus, mutagenic treatment was carried out with X-rays and gamma rays on buds and seedlings. As a prerequisite, attempts were made to determine some physiological and structural differences in leaves in order to evaluate and analyse the reaction to the bacterium in qualitative and quantitative terms. Citrus were found to present 3-4 annual sproutings, each having a different intensity. Grapefruit showed a greater initial increase and final length than orange, but lemon growth was greater than all the others. According to their growth, leaves clustered in three groups. Those in the middle part of the sprout showed the greatest daily increase, followed in decreasing order by those of the base and those of the apex. In orange cultivars with different degrees of reaction to Xanthomonas citri a direct association between daily growth of leaves and susceptibility was found. In fully developed leaves the number of stomata per surface unit presented an inverse ratio with susceptibility. It was observed that in a given genotype the stomata frequency per surface unit was higher in young leaves than in developed ones. Also a direct association between the leaf area and the number of stomata per leaf was found. Natural field infections were measured in leaves of developed plants. Infection in each of the 3-4 annual sproutings depends on environmental factors during the growth period and the predisposition period of the leaves. The available variation for reaction to Xanthomonas citri was higher in oranges than in grapefruit. The abscission of each leaf depends on its degree of infection, but the cultivars classed as more resistant are those requiring a smaller affected area to provoke the leaf abscission. However, abscission of a leaf is independent of the fate of the neighbouring ones. The existence of a continuous grading of infection damage within the orange cultivars suggests a genetic component for resistance to Xanthomonas citri

Individual and Family Perfectionism and Its Relationship to Depression, Anxiety, and Self-Esteem among Latino College Students

Science.gov (United States)

Ortega, Norma E.

2010-01-01

This study examined the relationship between individual and family perfectionism and mental health functioning among two hundred and seven Latino college students. One aim of this study was to test the factor structure of the Almost Perfect Scale-Revised (APS-R; Slaney, Rice, Mobley, Trippi, & Ashby, 2001) with Latino college students by…

Materials selection in micromechanical design: an application of the Ashby approach

OpenAIRE

Srikar, V.T.; Spearing, S.M.

2003-01-01

The set of materials available to microsystems designers is rapidly expanding. Techniques now exist to introduce and integrate a large number of metals, alloys, ceramics, glasses, polymers, and elastomers into microsystems, motivating the need for a rational approach for materials selection in microsystems design. As a step toward such an approach, we focus on the initial stages of materials selection for micromechanical structures with minimum feature sizes greater than 1 /spl mu/m. The vari...

Influence of using nanoobjects as filler on functionality-based energy use of nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Roes, A. L., E-mail: a.l.roes@uu.nl; Tabak, L. B.; Shen, L.; Nieuwlaar, E.; Patel, M. K. [Utrecht University, Copernicus Institute, Department of Science, Technology and Society (Netherlands)

2010-08-15

The goal of our study was to investigate the potential benefits of reinforcing polymer matrices with nanoobjects for structural applications by looking at both the mechanical properties and environmental impacts. For determining the mechanical properties, we applied the material indices defined by Ashby for stiffness and strength. For the calculation of environmental impacts, we applied the life cycle assessment methodology, focusing on non-renewable energy use (NREU). NREU has shown to be a good indicator also for other environmental impacts. We then divided the NREU by the appropriate Ashby index to obtain the 'functionality-based NREU'. We studied 23 different nanocomposites, based on thermoplastic and thermosetting polymer matrices and organophilic montmorillonite, silica, carbon nanotubes (single-walled and multiwalled) and calcium carbonate as filler. For 17 of these, we saw a decrease of the functionality-based NREU with increasing filler content. We draw the conclusion that the use of nanoobjects as filler can have benefits from both an environmental point of view and with respect to mechanical properties.

Chloral hydrate complexing with heteropolyanions of diverse structures

International Nuclear Information System (INIS)

Maksimov, G.M.; Timofeeva, M.N.; Likholobov, V.A.

2001-01-01

Interaction between chloral hydrate and tetrabutylammonium salts of heteropolyacids (HPA) of five structural types: Keggin's (H 3 PW 12 O 40 , H 3 PMo 12 O 40 , H 4 SiW 12 O 40 ), Dowson's (α-H 6 P 2 W 18 O 62 , α-H 6 P 2 Mo 18 O 62 , α-H 4 S 2 Mo 18 O 62 ), H 6 P 2 W 21 O 71 (H 2 O) 3 , H 6 As 2 W 21 O 69 (H 2 O) and H 21 B 3 W 39 O 132 was studied by the method 1 H NMR in deuteronitrobenzene solution. It was ascertained that the surface of HPA anions is heterogeneous in reference to acid-base properties. Dependence general for all HPA was found: decrease in specific charge of anion (per one atom of W or Mo) gives rise to increase in HPA acidity [ru

An Intelligence Collection Management Model.

Science.gov (United States)

1984-06-01

classification of inteligence collection requirements in terms of. the a-.- metnodo"c, .ev--e in Chaster Five. 116 APPgENDIX A A METHOD OF RANKING...of Artificial Intelligence Tools and Technigues to!TN’X n~l is n rs aa~emfft-.3-ufnyva: ’A TZ Ashby W. Ecss. An Introduction to Cybernetics. New York

Homogenization of steady-state creep of porous metals using three-dimensional microstructural reconstructions

DEFF Research Database (Denmark)

Kwok, Kawai; Boccaccini, Dino; Persson, Åsa Helen

2016-01-01

The effective steady-state creep response of porous metals is studied by numerical homogenization and analytical modeling in this paper. The numerical homogenization is based on finite element models of three-dimensional microstructures directly reconstructed from tomographic images. The effects ...... model, and closely matched by the Gibson-Ashby compression and the Ramakrishnan-Arunchalam creep models. [All rights reserved Elsevier]....

The Interrelationships among Coping Resources, Gender Role Stress, Self-Efficacy, and Anxiety in University Women Enrolled in Graduate Counseling Programs

Science.gov (United States)

Kordansky, Jessica B.

2010-01-01

College-age women are affected by anxiety disorders at a significant rate. The data suggest that enhancing a sense of control over the negative effects of life events has a greater positive effect on women than men (Matheny, Ashby, & Cupp, 2005). While there is a literature base for stress coping among undergraduate students (McCarthy,…

Systems Science in Support of Total Quality Management,

Science.gov (United States)

Quality Management (TQM). This paper bridges the gap between these two subjects to illustrate specific means by which systems science can begin to augment TQM. This construction is based upon the consideration of two topics. First, a brief introduction to systems science is provided. Second, systems science is applied through the concept of the Conant-Ashby

Index to FAA Office of Aerospace Medicine Reports: 1961 through 2008

Science.gov (United States)

2009-01-01

ng: A crtcal analyss of the concept and current practces. ADA269397 93-14 Armen a-Cope R, Marcus JH, Gowdy RV, DeWeese RL: An assessment of the...Antuñano MJ ----- 93-3, 01-15, 06-1, 06-1, 07-2 Armen a-Cope R - 93-14 Armstrong R ------ 66-17 Arnell F ------------ 97-22 Ashby FK --------- 67-8

When The Shooting Stops: Recovery From Active Shooter Events For K-12 Schools

Science.gov (United States)

2017-12-01

ems -insider/articles/2014/02/a-new-response.html. 2 Ashby, Cornelia, and William O. Jenkins Jr. Emergency Management: Most School Districts Have...of Emergency Medical Services, March 18, 2014, http://www.jems.com/ ems -insider/ articles/2014/02/a-new-response.html. xviii THIS PAGE...Gang violence  Bomb threats  Domestic violence and abuse  Cyber attacks  Suicide 72

Process and representation in multiple-cue judgment

OpenAIRE

Olsson, Anna-Carin

2002-01-01

This thesis investigates the cognitive processes and representations underlying human judgment in a multiple-cue judgment task. Several recent models assume that people have several qualitatively distinct and competing levels of knowledge representations (Ashby, Alfonso-Reese, Turken, & Waldron, 1998; Erickson & Kruschke, 1998; Nosofsky, Palmeri, & McKinley, 1994; Sloman, 1996). The most successful cognitive models in categorization and multiple-cue judgment are, respectively, exe...

Primer registro de “la mosca negra de los cítricos” Aleurocanthus woglumi (Hemiptera: Aleyrodidae en la Argentina

Directory of Open Access Journals (Sweden)

Silvia N. LÓPEZ

2011-01-01

Full Text Available Aleurocanthus woglumi Ashby es una especie polífaga que ataca principalmente cultivos de Citrus spp. El objetivo de este trabajo es dar a conocer la primera detección de A. woglumi en Argentina. Los especímenes estudiados fueron recolectados en cultivos de pomelo en Tres Lagunas, departamento de Pilagá, Formosa, en febrero de 2011.

Surface temperatures and glassy state investigations in tribology

Science.gov (United States)

Bair, S.; Winer, W. O.

1980-01-01

Measurements were made of the limiting shear stress for two naphthenic oils of differing molecular weight and three blends of the lower molecular weight oil and polymers of differing molecular weight. All reached the same limiting shear stress for the same temperature and pressure; although the polymer solutions reduced the limiting shear stress by about fifteen percent. A falling body viscometer was constructed to operate to 230 C and to 0.6 GPa and another was constructed to extend the pressure range to 1.1 GPa. A concentrated contact simulator was developed which allows recording of the traction force while the slide-roll ratio is continuously varied and the rolling speed is maintained essentially constant. Measurement of lubricant minimum film thickness of elliptical EHD contacts of various aspect ratios were made by optical interferometry. The experimental data were thirty percent greater than that predicted by the Hamrock and Dowson model. Preliminary development of the application of a scanning infrared radiation system to a tribological system was completed.

Bio-tribology.

Science.gov (United States)

Dowson, Duncan

2012-01-01

It is now forty six years since the separate topics of friction, lubrication, wear and bearing design were integrated under the title 'Tribology' [Department of Education and Science, Lubrication (Tribology) Education and Research. A Report on the Present Position and Industry's Needs, HMSO, London, 1966]. Significant developments have been reported in many established and new aspects of tribology during this period. The subject has contributed to improved performance of much familiar equipment, such as reciprocating engines, where there have been vast improvements in engine reliability and efficiency. Nano-tribology has been central to remarkable advances in information processing and digital equipment. Shortly after widespread introduction of the term tribology, integration with biology and medicine prompted rapid and extensive interest in the fascinating sub-field now known as Bio-tribology [D. Dowson and V. Wright, Bio-tribology, in The Rheology of Lubricants, ed. T. C. Davenport, Applied Science Publishers, Barking, 1973, pp. 81-88]. An outline will be given of some of the developments in the latter field.

Open-cellular copper structures fabricated by additive manufacturing using electron beam melting

International Nuclear Information System (INIS)

Ramirez, D.A.; Murr, L.E.; Li, S.J.; Tian, Y.X.; Martinez, E.; Martinez, J.L.; Machado, B.I.; Gaytan, S.M.; Medina, F.; Wicker, R.B.

2011-01-01

Highlights: → Relative stiffness versus relative density measurements for reticulated mesh and stochastic open cellular copper were shown to follow the Gibson-Ashby foam model. → Microstructures for the mesh struts and foam ligaments illustrated a propensity of copper oxide precipitates which provided structural hardness and strength. → These components, fabricated by electron beam melting, exhibit interesting prospects for specialized, complex heat-transfer devices. - Abstract: Cu reticulated mesh and stochastic open cellular foams were fabricated by additive manufacturing using electron beam melting. Fabricated densities ranged from 0.73 g/cm 3 to 6.67 g/cm 3 . The precursor Cu powder contained Cu 2 O precipitates and the fabricated components contained arrays of Cu 2 O precipitates and interconnected dislocation microstructures having average spacings of ∼2 μm, which provide hardness values ∼75% above commercial Cu products. Plots of stiffness (Young's modulus) versus density and relative stiffness versus relative density were in very close agreement with the Gibson-Ashby model for open cellular foams. These open cellular structure components exhibit considerable potential for novel, complex, multi-functional electrical and thermal management systems, especially complex, monolithic heat exchange devices.

Beating the Red Gold Rush: Copper Theft and Homeland Security

Science.gov (United States)

2015-12-01

the overall costs associated with the products they steal. A piece published in the Journal of Research in Crime and Delinquency in 2014 hypothesized...Sidebottom, Matt Ashby, and Shane Johnson, “Copper Cable Theft: Revisiting the Price- Theft Hypothesis,” Journal of Research in Crime and Delinquency 51, no...175 “Telecom Italia Mobile: Company History ,” International Director of Company Histories , 2004, accessed September 4, 2015, http://www.company

The Second Tennessee Cavalry in the American Civil War

Science.gov (United States)

2014-06-13

Hereafter cited as OR. 6Andrew Williams, Andrew Jackson Williams Papers , 1908-1910, Archives of Appalachia, East Tennessee State University...Centennial Commission of Tennessee, Tennesseans, 25-27; OR, series 1, vol. 4, 244. 63Colonel (Ret.) Armando Alfaro, “The Paper Trail of the Civil War in...observer noted that Ashby “served the balance of the war on crutches ” after receiving this wound.141 Colonel John Scott’s Kentucky Raid In July

The Effect of Twins on Critical Currents of High Tc Superconductors

Science.gov (United States)

1989-01-01

particles to stick together due to electrostatic forces. To overcome this we have formed a slurry of the material in liquid nitrogen and flash...can use and the liquid convection tends to counteract the separation process. We have-now designed a magnetic track which particles will slide down with...Currents of High Tc Superconductors" - A.M. Campbell and M.F. Ashby The initial work on levitation forces and separation of superconducting powders has

An Ensemble of Atomic Fountains

Science.gov (United States)

2012-05-01

1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 ph as e (n s) 56000559005580055700 MJD 8 10-16 2 4 6 8 10-15 2 4 ov er la pp in g Al la n de vi at io n 104... Metrologia 49, 49-56 (2012). [3] N. Ashby et al., Phys. Rev. Lett. 98, 070802 (2007). [4] S. J. Ferrell, et al., Phys. Rev. A 76, 062104 (2007). [5] T. M

Cybernetic brain sketches of another future

CERN Document Server

Pickering, Andrew

2014-01-01

Cybernetics is often thought of as a grim military or industrial science of control. But as Andrew Pickering reveals in this beguiling book, a much more lively and experimental strain of cybernetics can be traced from the 1940s to the present.The Cybernetic Brain explores a largely forgotten group of British thinkers, including Grey Walter, Ross Ashby, Gregory Bateson, R. D. Laing, Stafford Beer, and Gordon Pask, and their singular work in a dazzling array of fields. Psychiatry, engineering, management, politics, music, architecture, education, tantric yoga, the Beats, and the sixties counterc

Characterization of free nitrogen fixing bacteria of the genus Azotobacter in organic vegetable-grown Colombian soils

Directory of Open Access Journals (Sweden)

Diego Javier Jiménez

2011-09-01

Full Text Available With the purpose of isolating and characterizing free nitrogen fixing bacteria (FNFB of the genus Azotobacter, soil samples were collected randomly from different vegetable organic cultures with neutral pH in different zones of Boyacá-Colombia. Isolations were done in selective free nitrogen Ashby-Sucrose agar obtaining a recovery of 40%. Twenty four isolates were evaluated for colony and cellular morphology, pigment production and metabolic activities. Molecular characterization was carried out using amplified ribosomal DNA restriction analysis (ARDRA. After digestion of 16S rDNA Y1-Y3 PCR products (1487pb with AluI, HpaII and RsaI endonucleases, a polymorphism of 16% was obtained. Cluster analysis showed three main groups based on DNA fingerprints. Comparison between ribotypes generated by isolates and in silico restriction of 16S rDNA partial sequences with same restriction enzymes was done with Gen Workbench v.2.2.4 software. Nevertheless, Y1-Y2 PCR products were analysed using BLASTn. Isolate C5T from tomato (Lycopersicon esculentum grown soils presented the same in silico restriction patterns with A. chroococcum (AY353708 and 99% of similarity with the same sequence. Isolate C5CO from cauliflower (Brassica oleracea var. botrytis grown soils showed black pigmentation in Ashby-Benzoate agar and high similarity (91% with A. nigricans (AB175651 sequence. In this work we demonstrated the utility of molecular techniques and bioinformatics tools as a support to conventional techniques in characterization of the genus Azotobacter from vegetable-grown soils.

Caracterización de cepas nativas de Azotobacter spp. y su efecto en el desarrollo de Lycopersicon esculentum Mill. “tomate” en Lambayeque

Directory of Open Access Journals (Sweden)

Cynthia Escobar

2011-01-01

Full Text Available El objetivo de la presente investigación fue caracterizar y determinar el efecto de cepas nativas de Azotobacter spp. en el desarrollo vegetativo de Lycopersicon esculentum Mill. “tomate”, como una alternativa al uso indiscriminado de fertilizantes químicos. Se tomaron muestras de raíces y suelo rizosférico de hortalizas con las que se realizaron diluciones (10-4 en caldo Ashby-Sacarosa y se incubaron a 30 ºC hasta observar un color amarillo, turbidez y película superficial. El género Azotobacter se identificó en agar mineral sin nitrógeno y Ashby-Benzoato, obteniéndose 96 cepas con una producción de 7.10 a 57.99 mgL-1 de ácido indolacético, 0.13 a 1.64 mgL-1 de nitrógeno fijado como amonio y hasta 1.61 % de eficiencia en la solubilización de roca fosfórica de Bayóvar. Se obtuvo una suspensión celular (108 de cada una de las cuatro cepas con los mayores valores y se inocularon independientemente y en consorcio, así como una combinación con 50 % de urea-100 % de roca fosfórica, en la rizósfera de tomate cv. Río Grande, en un diseño experimental completamente aleatorio. Todas las cepas nativas incrementaron la altura, volumen radicular, materia seca total, parte aérea y radicular frente al testigo absoluto.

Reply to ‘Comment on Relativistic theory of the falling cube gravimeter’

Science.gov (United States)

Ashby, Neil

2018-04-01

The comment (Křen and Pálinkás 2017 Metrologia 55 314-5) claims that the paper Relativistic theory of the falling cube gravimeter (Ashby 2017 Metrologia 55 1-10) is incorrect. The authors of this comment assert that optical paths in the two interferometer arms of an absolute gravimeter shift only the absolute phase difference between interferometer arms and therefore cannot affect the measured value of g, and that the only needed relativistic correction is the commonly applied ‘speed of light correction’. Neither claim stands up to scrutiny. Work of the U.S. government, not subject to copyright.

Differentiating adaptive and maladaptive perfectionism on the MMPI-2 and MIPS revised.

Science.gov (United States)

Rice, Kenneth G; Stuart, Jennifer

2010-03-01

Although conceptualizations of perfectionism have emphasized adaptive as well as maladaptive expressions of the construct, how these different dimensions or types of perfectionists might be reflected in comprehensive personality assessment instruments is unknown. An initial sample of 267 university students completed the Minnesota Multiphasic Personality Inventory-2 (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 2001), Millon Index of Personality Styles Revised (MIPS-R; Millon, 2004), and Almost Perfect Scale-Revised (Slaney, Mobley, Trippi, Ashby, & Johnson, 1996). Analyses indicated that dimensions and types of perfectionism were associated, in expected directions, with select scores on the MMPI-2 and MIPS-R.

STS-112 Flight Day 7 Highlights

Science.gov (United States)

2002-10-01

On this seventh day of STS-112 mission members of the crew (Commander Jeff Ashby; Pilot Pam Melroy; Mission Specialist Sandy Magnus, Piers Sellers, Dave Wolf, and Fyodor Yurchikhin) along with the Expedition Five crew (Commander Valery Korzun; Flight Engineer Peggy Whitson, and Sergei Treschev) are seen answering questions during the mission's press interview and photo opportunity. They answered various questions regarding the mission's objectives, the onboard science experiments, the extravehicular activities (EVAs) and the effects of living in space. Shots of the test deployment of the S1 truss radiator and Canadarm rotor joint are also shown.

Infestação da mosca-negra-dos-citros (Aleurocanthus woglumi Ashby em pomares de citros, em sistemas de plantio convencional e agroflorestal Infestation of citrus blackfly in citrus (Aleurocanthus woglumi Ashby orchards conventional and agroforestry

Directory of Open Access Journals (Sweden)

Anderson Gonçalves Da Silva

2011-03-01

Full Text Available Objetivou-se com o presente trabalho avaliar a infestação da mosca-negra-dos-citros em pomares de citros, em sistemas de plantio convencional e agroflorestal. A área experimental está localizada no município de Capitão Poço-PA, onde foram realizadas 12 amostragens durante o período de setembro de 2008 a outubro de 2009, avaliando a presença ou a ausência da praga nas laranjeiras, em ambos os sistemas de produção. Pelos resultados obtidos, observou-se que o sistema de plantio agroflorestal apresentou maior incidência de plantas com presença de mosca-negra-dos-citros comparado ao convencional, houve influência da temperatura na regulação da população da praga, e precipitações elevadas reduziram o número de plantas com presença de A. woglumi.The purpose of this study was to evaluate the infestation of citrus blackfly the in a citrus orchard in conventional tillage systems and agroforestry. The experimental area is located in the municipality of Capitão Poço, PA, where 12 samples were taken during the period from September 2008 to October 2009, evaluating the presence or absence of the pest in both production systems. The results showed that the system of agroforestry plantation showed higher incidence of plants with presence of citrus blackfly compared to conventional, there was influence of temperature on the regulation of pest population and heavy rain reduced the number of plants with presence of A.woglumi.

Diagnóstico molecular de enfermedades sistémicas de la caña de azúcar en la Argentina: ajuste metodológico y aplicaciones Molecular diagnosis of sistemic sugarcane diseases in Argentina: methodology adjustment and applications

Directory of Open Access Journals (Sweden)

María P. Filippone

Full Text Available Las enfermedades sistémicas representan uno de los principales factores que afectan la producción de caña de azúcar. El conocimiento del estado fitosanitario del cultivo y la identificación correcta de los fitopatógenos son claves para reducir las pérdidas por enfermedades. En este sentido, es fundamental contar con técnicas de diagnóstico sensibles, rápidas y fáciles de ejecutar, para realizar un diagnóstico preciso y precoz. A partir del año 2005, en la Estación Exper imental Agroindustrial Obispo Colombres se incorporó el diagnóstico molecular basado en la reacción en cadena de la polimerasa, para la detección específica de cuatro enfermedades sistémicas de la caña de azúcar: raquitismo de la caña soca (Leifsonia xyli sp. xyli, escaldadura de la hoja (Xanthomonas albilineans, mosaico de la caña de azúcar (Sugarcane mosaic virus, ScMV y síndrome de la hoja amarilla (Sugarcane yellow leaf virus, ScYLV. En este trabajo, se presenta la optimización metodológica del diagnóstico molecular y se compara su eficiencia con la de la técnica inmunoquímica ELISA. El método molecular mostró mayor sensibilidad para las enfermedades evaluadas, tanto bacterianas como virales. El establecimiento del diagnóstico molecular constituye un avance tecnológico de gran importancia para la industria azucarera regional, ya que no solo ayudará a disminuir la incidencia de dichas enfermedades, sino que también evitará el ingreso de otras nuevas al introducir germoplasma de caña de azúcar desde otras regiones.Systemic diseases represent one of the main factors affecting sugarcane production. The knowledge of crop sanitary conditions and the correct identification of phytopathogens are key factors to reduce losses caused by them. To diagnose diseases as early as possible is crucial, so techniques that are sensitive, fast, accurate and easy to use are essential. Since 2005, molecular diagnosis based on polymerase chain reaction has

Op. No A4495 Columbia, STS-93 Chandra - Breakfast, Suiting, and Walkout

Science.gov (United States)

1999-01-01

The primary objective of the STS-93 mission was to deploy the Advanced X-ray Astrophysical Facility, which had been renamed the Chandra X-ray Observatory in honor of the late Indian-American Nobel Laureate Subrahmanyan Chandrasekhar. The mission was launched at 12:31 on July 23, 1999 onboard the space shuttle Columbia. The mission was led by Commander Eileen Collins. The crew was Pilot Jeff Ashby and Mission Specialists Cady Coleman, Steve Hawley and Michel Tognini from the Centre National d'Etudes Spatiales (CNES). This videotape shows the astronauts after breakfast getting into spacesuits, walking out to board the bus, and boarding the bus prior to launch.

Finite element analysis of mechanical stability of coarsened nanoporous gold

International Nuclear Information System (INIS)

Cho, Hoon-Hwe; Chen-Wiegart, Yu-chen Karen; Dunand, David C.

2016-01-01

The mechanical stability of nanoporous gold (np-Au) at various stages of thermal coarsening is studied via finite element analysis under volumetric compression using np-Au architectures imaged via X-ray nano-tomography. As the np-Au is coarsened thermally over ligament sizes ranging from 185 to 465 nm, the pore volume fraction is determinant for the mechanical stability of the coarsened np-Au, unlike the curvature and surface orientation of the ligaments. The computed Young's modulus and yield strength of the structures are compared with the Gibson–Ashby model. The geometry of the structures determines the locations where stress concentrations occur at the onset of yielding.

The effect of porosity on the mechanical properties of porous titanium scaffolds: comparative study on experimental and analytical values

Science.gov (United States)

Khodaei, Mohammad; Fathi, Mohammadhossein; Meratian, Mahmood; Savabi, Omid

2018-05-01

Reducing the elastic modulus and also improving biological fixation to the bone is possible by using porous scaffolds. In the present study, porous titanium scaffolds containing different porosities were fabricated using the space holder method. Pore distribution, formed phases and mechanical properties of titanium scaffolds were studied by Scanning Electron Microscope (SEM), x-ray diffraction (XRD) and cold compression test. Then the results of compression test were compared to the Gibson-Ashby model. Both experimentally measured and analytically calculated elastic modulus of porous titanium scaffolds decreased by porosity increment. The compliance between experimentally measured and analytically calculated elastic modulus of titanium scaffolds are also increased by porosity increment.

Development of a constitutive model for the plastic deformation and creep of copper and its use in the estimate of the creep life of the copper canister

International Nuclear Information System (INIS)

Pettersson, Kjell

2006-12-01

A previously developed model for the plastic deformation and creep of copper (included as an Appendix to the present report) has been used as the basis for a discussion on the possibility of brittle creep fracture of the copper canister during long term storage of nuclear waste. Reported creep tests on oxygen free (OF) copper have demonstrated that copper can have an extremely low creep ductility. However with the addition of about 50 ppm phosphorus to the copper it appears as if the creep brittleness problem is avoided and that type of copper (OFP) has consequently been chosen as the canister material. It is shown in the report that the experiments performed on OFP copper does not exclude the possibility of creep brittleness of OFP copper in the very long term. The plasticity and creep model has been used to estimate creep life under conditions of intergranular creep cracking according to a model formulated by Cocks and Ashby. The estimated life times widely exceed the design life of the canister. However the observations of creep brittleness in OF copper indicate that the Cocks-Ashby model probably does not apply to the OF copper. Thus additional calculations have been done with the plasticity and creep model in order to estimate stress as a function of time for the probably most severe loading case of the canister with regard to creep failure, an earth quake shear. Despite the fact that the stress in the canister will remain at the 100 MPa level for thousands of years after an earth quake the low temperature, about 50 deg C or less, will make the solid state diffusion process assumed to control the brittle cracking process, too slow to lead to any significant brittle creep cracking in the canister

Some basic properties of environmentally adapted oils

Energy Technology Data Exchange (ETDEWEB)

Hoeglund, E. [Div. of Machine Elements, Luleaa University of Technology (Sweden)

1998-11-01

Environmental concern has led to a development of lubricants that are less harmful to the environmental than traditional mineral based oils. Biodegradability and non-toxicity are desired properties together with a competitive price and if possible they should also be derived from renewable raw materials. In order to have a major breakthrough for the new, environmentally adapted lubricating oils they must perform well in mechanical and hydraulic systems. They must reduce wear, increase efficiency and reduce maintenance costs equally well, or preferably better than mineral based oils. This paper presents primary results from an investigation where four environmentally adapted oils (rape seed, pine tree, diester and TMP-ester) are compared to a conventional naphthenic mineral oil. Viscosity and viscosity-pressure coefficients, limiting shear stress, friction properties and film forming ability have been evaluated under elastohydrodynamic conditions. It was found that the mineral oil had the highest values of pressure-viscosity coefficient, limiting shear stress and coefficient of friction. Rape seed oil had the second highest pressure-viscosity coefficient but the lowest limiting shear stress and coefficient of friction. Pine tree oil, diester and TMP-ester formed an intermediate group with rather similar results. The Hamrock-Dowson equation for central film thickness was found to overestimate film thickness by about 10-20 per cent with the least discrepancy for the mineral oil. (orig.) 8 refs.

On the history of Ludwig von Bertalanffy's "General Systemology", and on its relationship to cybernetics - part III: convergences and divergences

Science.gov (United States)

Drack, Manfred; Pouvreau, David

2015-07-01

Bertalanffy's so-called "general system theory" (GST) and cybernetics were and are often confused: this calls for clarification. In this article, Bertalanffy's conceptions and ideas are compared with those developed in cybernetics in order to investigate the differences and convergences. Bertalanffy was concerned with first order cybernetics. Nonetheless, his perspectivist epistemology is also relevant with regard to developments in second order cybernetics, and the latter is therefore also considered to some extent. W. Ross Ashby's important role as mediator between GST and cybernetics is analysed. The respective basic epistemological approaches, scientific approaches and inherent world views are discussed. We underline the complementarity of cybernetic and "organismic" trends in systems research within the unitary hermeneutical framework of "general systemology".

On the history of Ludwig von Bertalanffy's "General Systemology", and on its relationship to cybernetics - part III: convergences and divergences.

Science.gov (United States)

Drack, Manfred; Pouvreau, David

2015-07-04

Bertalanffy's so-called "general system theory" (GST) and cybernetics were and are often confused: this calls for clarification. In this article, Bertalanffy's conceptions and ideas are compared with those developed in cybernetics in order to investigate the differences and convergences. Bertalanffy was concerned with first order cybernetics. Nonetheless, his perspectivist epistemology is also relevant with regard to developments in second order cybernetics, and the latter is therefore also considered to some extent. W. Ross Ashby's important role as mediator between GST and cybernetics is analysed. The respective basic epistemological approaches, scientific approaches and inherent world views are discussed. We underline the complementarity of cybernetic and "organismic" trends in systems research within the unitary hermeneutical framework of "general systemology".

Comparación de la calidad de semilla de caña de azúcar en el segundo corte según el método de saneamiento Assessment of first ratoon seedcane quality obtained through different methods

Directory of Open Access Journals (Sweden)

Patricia A. Digonzelli

Full Text Available En Semilleros Registrados de caña azúcar de tres cultivares, provenientes de diferentes orígenes de saneamiento, se compararon los componentes de producción de caña semilla para la edad de soca 1 (segundo corte del semillero. La semilla estaba libre de RSD (Leifsonia xyli subsp. xyli y escaldadura de la hoja (Xanthomonas albilineans. El diseño experimental fue completamente aleatorizado, con cuatro repeticiones. Los tratamientos evaluados fueron: dos orígenes de la semilla, micropropagada e hidrotermotratada (50ºC, 2 h, y tres variedades (LCP 85-384, CP 65-357 y CP 48-103. Cada parcela experimental constaba de cinco surcos de 3 m y se evaluó la caña de los tres surcos centrales. En la cosecha del semillero, se contaron todos los tallos por parcela y se midió su altura hasta hoja +1. En una muestra de 36 tallos por parcela se determinó el peso, el diámetro en la parte media y el número de yemas por tallo. A partir de los datos obtenidos, se calculó el número de yemas por surco de 100 metros de longitud y la producción de caña por parcela. La caña semilla micropropagada presentó mayor altura y peso por tallo y una mayor producción de caña que la semilla termotratada. En cuanto al número de tallos, diámetro y número de yemas por tallo y por surco, no hubo diferencias significativas relacionadas al origen de la semilla. La variedad afectó significativamente a todos los componentes de la producción de caña semilla, a excepción de la altura de tallos, que solo dependió del origen de la simiente.Seedcane production components were assessed in first ratoon (cane from second cut from Registered Nurseries obtained through micropropagation and hot water treatment (50ºC, 2 h of LCP 85-384, CP 65-357 and CP 48-103 cultivars. Micropropagated and hot-water-treated seedcane was free from ratoon stunting disease (RSD (Leifsonia xyli subsp. xyli and leaf scald (Xanthomonas albilineans. A completely randomized factorial design (3x3x2

Efecto de la época de plantación en la dinámica de la emergencia de caña semilla de alta calidad (termotratada y micropropagada de las variedades CP 65-357 y LCP 85-384 Effect of planting date on emergence dynamics of high quality CP 65-357 and LCP 85-384 seed cane (hot-water treated and micropropagated

Directory of Open Access Journals (Sweden)

Patricia A. Digonzelli

2005-12-01

Full Text Available Se evalúa el efecto de la época de plantación en la dinámica de la emergencia de caña semilla de alta calidad (micropropagada y termotratada de las variedades CP 65-357 y LCP 85-384, en condiciones de disponibilidad hídrica adecuada. La caña semilla micropropagada y termotratada (50ºC, 2 hs se plantó, con una densidad de 15 yemas/m, en tres épocas contrastantes: otoño, invierno y primavera. El material empleado estaba libre de escaldadura de la hoja (Xanthomonas albilineans y achaparramiento (Leifsonia xyli subsp. xyli. La época de plantación afectó todas las variables de la dinámica de la emergencia en las dos variedades y en ambos orígenes de la semilla. El origen afectó significativamente el inicio y la duración de la emergencia (t e y t50, pero no tuvo efecto en el porcentaje final ni en la tasa media de emergencia. La emergencia (% fue mayor en la plantación de octubre, que en las de mayo y agosto (59%, 35% y 45%, respectivamente. El te y el t50 fueron mayores en mayo que en agosto y octubre. La semilla micropropagada presentó, en general, valores de t e y t50 menores que la termotratada. La época de plantación fue el principal factor que afectó la dinámica de la emergencia de caña semilla de alta calidad de CP 65-357 y LCP 85-384. La variedad y el origen de la semilla afectaron significativamente, aunque en menor magnitud que la época de plantación, el inicio y la duración de la fase de emergencia.Planting date influence on emergence dynamics of high quality CP 65-357 and LCP 85-384 seed cane (hot-water treated and micropropagated, without humidity constraints, was evaluated. Material used was free from leaf scald disease (Xanthomonas albilineans and ratoon stunting disease (Leifsonia xyli subsp. xyli. Seed cane, micropropagated and hot-water treated (50ºC, 2 hours, was planted with a 15 buds/m density in three contrasting dates: autumn, winter and spring. The material was irrigated during the trial. Planting

Conductas y actitudes alimentarias, imagen corporal y perfeccionismo en estudiantes universitarias mujeres Eating behaviors and attitudes, body image and perfectionism in female college students

Directory of Open Access Journals (Sweden)

Guido Salvador Cruz

2011-12-01

Full Text Available Objetivo: comparar estudiantes universitarias mujeres con y sin riesgo de trastorno alimentario, en función de características asociadas a dichas patologías. Muestra: 83 mujeres de 19 a 31 años, estudiantes de una universidad pública de la Ciudad Autónoma de Buenos Aires. Procedimiento: las participantes completaron un Cuestionario de datos, Contour Drawing Rating Scale (Thompson & Gray, 1995, Eating Disorder Inventory-2 (Garner, 1991; adaptación Rutsztein et al., 2006 y la Almost Perfect Scale Revised (Slaney, Rice, Mobley, Trippi & Ashby, 2001; adaptación Arana, Keegan & Rutsztein, 2009. Resultados: las mujeres con riesgo de trastorno alimentario presentan mayor porcentaje de insatisfacción con la imagen corporal y vómitos autoinducidos, además de puntajes superiores en la mayoría de las subescalas del EDI-2 y en la subescala Discrepancia de la APS-R. Conclusiones: las mujeres con riesgo de trastorno alimentario presentan un mayor nivel de perfeccionismo desadaptativo. Estos hallazgos son relevantes para el desarrollo de tratamientos para sintomatología específica de trastorno alimentario.Objective: to compare female university students with and without risk of eating disorders, based on characteristics associated with these disorders. Sample: 83 women aged 19 to 31 years old, students from a public university in the City of Buenos Aires. Procedure: Participants completed a Data questionnaire, Contour Drawing Rating Scale (Thompson & Gray, 1995, Eating Disorder Inventory-2 (Garner, 1991; adaptation Rutsztein et al., 2006 and the Almost Perfect Scale-Revised (Slaney, Rice, Mobley, Trippi & Ashby, 2001; adaptation Arana, Keegan & Rutsztein, 2009. Results: Women presenting risk of eating disorders have a higher percentage of body image dissatisfaction and self-induced vomiting, as well as higher scores in most of the subscales of the EDI-2 and the Discrepancy subscale of the APS-R. Conclusions: Women presenting risk of eating

Perfeccionismo positivo / negativo y calidad de vida percibida en estudiantes de Psicología, Medicina e Ingeniería de la Ciudad de Buenos Aires Positive / negative perfectionism and perceived quality of life in Psychology, Medicine and Engineering students of the city of Buenos Aires

Directory of Open Access Journals (Sweden)

Fernán Guido Arana

2010-12-01

Full Text Available El objetivo del presente estudio es dar cuenta de la relación entre el perfeccionismo en sus tres dimensiones (Altos Estándares -AE-, Orden -O- y Discrepancia-D- y la calidad de vida percibida (CV en tres muestras de estudiantes universitarios de las carreras de Psicología, Medicina e Ingeniería de la Ciudad de Buenos Aires. La muestra estuvo conformada por 476 estudiantes que completaron los siguientes instrumentos: cuestionario sociodemográfico, la almost Perfect Scale-revised (APS-R, Slaney, Rice, Mobley, Trippi, & Ashby, 2001; adaptación: Arana, Keegan, & Rutsztein, 2009 y el Inventario de Calidad de Vida Percibida (ICV, Mikulic, 2006. Los resultados sugieren una asociación signiicativa para un aspecto del perfeccionismo positivo (O y una alta CV percibida, y para el perfeccionismo negativo (D en relación a una baja CV percibida. Diferencias halladas en las diversas carreras para estas dimensiones indican la necesidad de atender a las variables contextuales especíicas para el análisis de este constructo.The aim of this study is to account for the relationship between perfectionism in its three dimensions (High Standards -HS-, Order -O-, and Discrepancy -D- and the perceived quality of life (QL in three samples of university students of Psychology, Medicine and Engineering of the City of Buenos Aires. The sample consisted of 476 students who completed the following in struments: Socio-demographic questionnaire, the Almost Perfect Scale-revised (APS-R, Slaney, Rice, Mobley, Trippi, & Ashby, 2001; adaptation: Arana, Keegan, & Rutsztein, 2009 and the Inventario de Calidad de Vida Percibida (ICV, Mikulic, 2006. Results suggest a signiicant association for one aspect of positive perfectionism (O and a perceived high QL, and for negative perfectionism (D and a perceived low QL. Differences found for these dimensions in the students of each career indicate the need to pay attention to specific contextual variables for the analysis of this

Dinámica de la brotación potencial de caña semilla micropropagada y termotratada de tres cultivares de caña de azúcar Potential germination dynamics of micropropagated and hot-water-treated seedcane of three sugarcane cultivars

Directory of Open Access Journals (Sweden)

Patricia A. Digonzelli

2006-12-01

Full Text Available Se comparó la dinámica de la brotación potencial (brotación en condiciones óptimas de humedad y temperatura de estacas uninodales de caña semilla saneada, obtenida por micropropagación y por termoterapia (inmersión en agua caliente 50ºC durante 2 h de tres cultivares (LCP 85-384, CP 65-357 y CP 48-103 y en tres edades (7, 10 y 12 meses. La semilla micropropagada e hidrotermotratada se encontraba libre de achaparramiento de la caña soca (Ratoon Stunting Disease, RSD (Leifsonia xyli subsp. xyli y escaldadura de la hoja (Xanthomonas albilineans. Las estacas se colocaron en una cámara de cría, en bandejas con arena lavada y esterilizada, a temperatura de 26 ± 2ºC, luz continua y control de humedad. El diseño experimental utilizado fue un factorial completamente aleatorizado (3x3x2, con dos repeticiones. Los factores fueron: edad (tres niveles, cultivar (tres niveles y origen de la semilla (dos niveles. Diariamente se contaron las yemas brotadas (clavo visible hasta la estabilización de la brotación. La dinámica de la brotación potencial se ajustó al modelo exponencial simple, función sigmoide simétrica, con R2 ≥ 0,97 y a partir del modelo se derivaron las variables deducidas: t50 y t90 (días al 50% y 90% de la emergencia máxima, porcentaje máximo de brotación, tasa media y tasa máxima de brotación potencial. La brotación en la semilla micropropagada presentó una mayor velocidad y una menor duración que en la termotratada. El porcentaje final varió entre el 80% y el 100%, en independencia del origen de la semilla.The potential germination dynamics (germination under optimal humidity and temperature conditions of healthy seedcane of three cultivars (LCP 85-384, CP 65-357 and CP 48-103 at three different ages (7, 10 and 12 months were compared, by studying one-joint billets of seedcane obtained through micropropagation and hot water treatment (inmersion into water heated at 50ºC, for 2 h. This micropropagated and hot

Producción de caña semilla en Semilleros Registrados provenientes de micropropagación y de hidrotermoterapia de tres cultivares de caña de azúcar Seedcane production in Registered Nurseries obtained through micropropagation and hot water treatment of three sugarcane cultivars

Directory of Open Access Journals (Sweden)

Patricia A. Digonzelli

2006-12-01

Full Text Available Se evaluaron los componentes de la producción de caña semilla en Semilleros Registrados de caña de azúcar provenientes de micropropagación e hidrotermoterapia (50ºC, 2 h, en tres variedades (LCP 85-384, CP 65-357 y CP 48-103 y tres épocas de plantación (mayo, agosto y octubre. La semilla micropropagada y la hidrotermotratada estaban libres de achaparramiento de la caña soca (Leifsonia xyli subsp. xyli o RSD, por sus siglas en inglés, y escaldadura de la hoja (Xanthomonas albilineans. El diseño experimental fue un factorial completamente aleatorizado 3x3x2, con tres repeticiones. Los factores fueron: época de plantación (tres niveles, variedad (tres niveles y origen de la semilla (dos niveles. Cada parcela constaba de cinco surcos de 3 metros, evaluando los tres surcos centrales. En la cosecha del semillero se contaron todos los tallos por parcela y se midió su altura hasta hoja TVD. En una muestra de 45 tallos por parcela se determinaron el peso y número de yemas por tallo. A partir de los datos obtenidos se calculó el número de yemas por surco de 100 metros de longitud y por hectárea. El origen de la caña semilla (micropropagada o hidrotermotratada afectó el número de tallos y la altura y número de yemas por tallo, por surco y por hectárea. La época de plantación y la variedad afectaron los componentes de la producción de caña semilla. La micropropagada presentó una mayor población, altura y número de yemas por tallo, permitiendo aumentar entre el 8% y 23% el área que es posible plantar a partir de una hectárea de Semillero Registrado. La magnitud de las diferencias entre la caña semilla micropropagada y termotratada varió según cultivares y época de plantación.Seedcane yield components in sugarcane Registered Nurseries obtained through micropropagation and hot water treatment (50ºC, 2 h were evaluated, considering three varieties (LCP 85-384, CP 65-357 and CP 48-103 and three plantation dates (May, August

Identifikasi Dan Uji Antagonisme Jamur Endofit Tanaman Tebu (Saccharum Officinarum L.) Terhadap Perkembangan Xanthomonas Albilineans L. Dengan Metode Sterilisasi Autoklaf Dan Membran Filter

OpenAIRE

Wahyuni, Siti Hardianti

2016-01-01

This research was conducted in a Laboratory of Agricuture Faculty and greenhouse of Agricuture Faculty, North Sumatra University, Medan, from April until December 2014. The research used completely randomized design with three factors and three replications. The first factor were endophytic fungi 1, endophytic fungi 2, endophytic fungi 3, endophytic fungi 4, endophytic fungi 5, endophytic fungi 6, endophytic fungi 7, and endophytic fungi 8. The second factor were dilution 10-1, 10-2, 10-3 da...

Diagnostics of a stationary MPD-type plasma jet with a HCN laser interferometer

International Nuclear Information System (INIS)

Graser, W.; Hoffmann, P.

1975-01-01

A HCN laser interferometer of the Ashby-Jephcott type operating at a wavelength of 337 μm was used to measure spatially resolved electron densities in a stationary MPD-type plasma jet with non-LTE behavior. Experiments were performed with and without superimposed magnetic fields up to 0.1 T at the exit of the plasma accelerator. Electron densities were obtained within the limits of 5times10 12 and 10 15 cm -3 with an accuracy better than 10%. Within the axially symmetric expanding plasma of about 15-cm average diameter and 50-cm length the radial resolving power came to less than 1 cm. So this technique has proved to be suitable to fill a gap in the diagnostics of stationary magnetized plasmas in the mean range of electron densities. (auth)

Liftoff of Space Shuttle Columbia on mission STS-93

Science.gov (United States)

1999-01-01

The fiery launch of Space Shuttle Columbia lights up the night sky on its successful liftoff from Launch Pad 39-B on mission STS-93. Liftoff occurred at 12:31 a.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The crew numbers five: Commander Eileen M. Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Stephen A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a Shuttle mission. The target landing date is July 27, 1999, at 11:20 p.m. EDT.

STS-93 Commander Collins suits up for launch

Science.gov (United States)

1999-01-01

During the third launch preparations in the Operations and Checkout Building, STS-93 Commander Eileen M. Collins waves while having her launch and entry suit checked. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The STS-93 crew numbers five: Commander Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Stephen A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a shuttle mission.

STS-93 Mission Specialist Cady Coleman suits up for launch

Science.gov (United States)

1999-01-01

For the third time, during final launch preparations in the Operations and Checkout Building, STS-93 Mission Specialist Catherine G. Coleman (Ph.D.) dons her launch and entry suit. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The STS-93 crew numbers five: Commander Eileen M. Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Stephen A. Hawley (Ph.D.), Coleman, and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a shuttle mission.

STS-93 Commander Eileen Collins suits up for launch

Science.gov (United States)

1999-01-01

For the third time, in the Operations and Checkout Building, STS- 93 Commander Eileen M. Collins tries on her helmet with her launch and entry suit. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The STS-93 crew numbers five: Commander Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Stephen A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a shuttle mission.

The plastic deformation of copper-beryllium alloy

International Nuclear Information System (INIS)

Gadalla, A.A.

1980-01-01

Copper-2 at. % Be alloy specimens containing coherent and/or incoherent spherical beryllium precipitates have been tested at different temperatures. The precipitation process and dislocation substructure were examined by electron microscopy. The yielding process is consistent with Orwan mechanism, and the work-hardening of the alloy is parabolic in nature for smaller particles but changes to three-stage hardening for larger particles. The extent of stage I deformation is temperature dependent, and the rate of work-hardening is quite steep and may be described by either the Ashby or the Hirsch parabolic models. There is a noticeable softening during this stage which may be attributed to shearing of particles during deformation. The dislocation substructure shows a uniform distribution of fine dislocations as well as propagation of cracks across grains. The precipitates are a mixture of semi-coherent and incoherent particles. (author)

Characterization of 316L Steel Cellular Dodecahedron Structures Produced by Selective Laser Melting

Directory of Open Access Journals (Sweden)

Konda Gokuldoss Prashanth

2016-10-01

Full Text Available The compression behavior of different 316L steel cellular dodecahedron structures with different density values were studied. The 316L steel structures produced using the selective laser melting process has four different geometries: single unit cells with and without the addition of base plates beneath and on top, and sandwich structures with multiple unit cells with different unit cell sizes. The relation between the relative compressive strength and the relative density was compared using different Gibson-Ashby models and with other published reports. The different aspects of the deformation and the mechanical properties were evaluated and the deformation at distinct loading levels was recorded. Finite element method (FEM simulations were carried out with the defined structures and the mechanical testing results were compared. The calculated theory, simulation estimation, and the observed experimental results are in good agreement.

Creep behaviour of porous metal supports for solid oxide fuel cells

DEFF Research Database (Denmark)

Boccaccini, Dino; Frandsen, Henrik Lund; Sudireddy, Bhaskar Reddy

2014-01-01

The creep behaviour of porous ironechromium alloy used as solid oxide fuel cell support was investigated, and the creep parameters are compared with those of dense strips of similar composition under different testing conditions. The creep parameters were determined using a thermo......-mechanical analyser with applied stresses in the range from 1 to 15 MPa and temperatures between 650 and 800 _C. The GibsoneAshby and Mueller models developed for uniaxial creep of open-cell foams were used to analyse the results. The influence of scale formation on creep behaviour was assessed by comparing the creep...... data for the samples tested in reducing and oxidising atmospheres. The influence of preoxidation on creep behaviour was also investigated. In-situ oxidation during creep experiments increases the strain rate while pre-oxidation of samples reduces it. Debonding of scales at high stress regime plays...

Interaction of the phage-xanthomonas campestris (Pammel) Dowson at the eletronic microscopy level, Virazole effect and radioautographic study of the phage action on the host

International Nuclear Information System (INIS)

Sittolin, I.M.

1982-04-01

A bacteriophage from the cabbage tissue infected with Xanthomonas campestris is described. The infection process is studied through a negative staining technique (PTA) and ultrathin section. The effect of Virazole, an antivirus agent, is tested. Radioautography showed that the phage presented a reasonable domain on the bacterial host genome since the beginning of the treatment. Sorological reactions indicated the induction of specific antibodies for the phage. (M.A.C.) [pt

Creep of the Copper Canister. A Critical Review of the Literature

International Nuclear Information System (INIS)

Bowyer, William H.

2003-04-01

Literature relevant to creep of the copper shell of the copper-iron canister has been reviewed. Two classes of copper have been examined, Oxygen Free High Conductivity (OFHC), which is referred to in the relevant literature and this report as OF material, and OF material with 50 ppm of phosphorus added. The second material is referred to as OFP. Creep processes occurring in copper are briefly described and a deformation diagram, after Frost and Ashby is provided. It is concluded that the diagram adequately describes the processes observed for the two materials of interest without necessarily being in exact agreement at a quantitative level. There are two regimes of time, temperature and stress which are important when creep of the copper shell is considered. The first is a holding period between welding of the lid to the canister and placing the canister in the repository and the second is the storage period in the repository. In the holding period, residual stresses arising from the manufacturing processes are important and in the second period stresses arising from repository pressures are important as well as the residual pressures arising from manufacture. The holding period may extend up to one year and the temperature of the copper shell may decline from the immediate post welding temperature to 100 deg C in this interval. Initial peak localised stresses may give rise to strains of up to 14 %. Dynamic recovery immediately after welding reduces the stresses associated with these strains to levels which correspond to stresses for approximately 0.1 % strain at the ruling temperature. This is 75 MPa at 100 deg C and 50 MPa for 150 deg C. A further stress relaxation of up to 30 % occurs in the first 20 days after welding. Localised stresses are therefore unlikely to exceed 50 MPa when the canister is placed into storage. No negative effects have been observed in connection with this stress relaxation process. In the storage period, which is indefinite, the

Resiliencia, tamaño de grano y microestructura generada en la ZAC de los aceros HSLA 450 EMZ soldados bajo un proceso SMAW

Directory of Open Access Journals (Sweden)

González, R.

2001-12-01

Full Text Available In this paper several features of the HAZ between the weld metal and the parent metal, after the heat cycle produced by a SMAW process in 450 N/mm² HSLA steels are analysed, taking into consideration the temperatures reached in the HAZ as from Rosenthal's equation. The aspects under examination are: grain morphology by means of micrographs obtained with the Scannig Electron Microscopy to check the bands that control the grain size due to the microalloyings of the designed steel, taking into account the temperatures reached and the cooling rate in each of the HAZ regions; fracture toughness, checked by means of CTOD testing; hardness grain size determined by the Ashby and Esterling procedure^[1] and based on the values obtained with the Heyn method^[2] , ratio between stable growth and heat input; CTOD values which are found to be satisfactory under the welding conditions with a heat input of 1.6 Kj/mm.

Tras el ciclo térmico producido por un proceso de soldadura manual con electrodo revestido (SMAW, en los aceros HSLA de 450 N/ mm² y, considerando las temperaturas alcanzadas en la ZAC según la ecuación de Rosenthal, se analizan los siguientes aspectos en esta zona (ZAC, entre el metal de soldadura y el metal base: la morfología del grano mediante micrografías obtenidas en el microscopio electrónico de barrido, comprobando las barreras que pinzan el grano debido a los microaleantes de este acero de diseño, teniendo en cuenta las temperaturas alcanzadas y la velocidad de enfriamiento en cada una de las regiones de la ZAC; la tenacidad a la fractura mediante los ensayos de CTOD; la dureza; el tamaño de grano, mediante el procedimiento de Ashby y Esterling^[1] y basado en los valores obtenidos por el método de Heyn^[2]; la proporcionalidad entre el crecimiento estable y la energía calorífica aportada; los valores de CTOD, satisfactorios en las condiciones de soldeo con

STS-93 Commander Eileen Collins waves to her family

Science.gov (United States)

1999-01-01

STS-93 Commander Eileen M. Collins waves to her family nearby, a last meeting before launch of mission STS-93 on July 20. Liftoff is scheduled for 12:36 a.m. EDT. The primary mission of STS-93 is the release of the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The new telescope is 20 to 50 times more sensitive than any previous X- ray telescope and is expected to unlock the secrets of supernovae, quasars and black holes. The STS-93 crew numbers five: Commander Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Steven A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a shuttle mission.

STS-93 M.S. Michel Tognini suits up before launch

Science.gov (United States)

1999-01-01

For the third time, in the Operations and Checkout Building, STS- 93 Mission Specialist Michel Tognini of France, who represents the Centre National d'Etudes Spatiales (CNES), waves after donning his launch and entry suit during final launch preparations. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The STS-93 crew numbers five: Commander Eileen M. Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Stephen A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Tognini. Collins is the first woman to serve as commander of a shuttle mission.

STS-93 Mission Specialist Hawley suits up for launch

Science.gov (United States)

1999-01-01

For the third time, during final launch preparations in the Operations and Checkout Building, STS-93 Mission Specialist Steven A. Hawley (Ph.D.) waves after donning his launch and entry suit. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The STS-93 crew numbers five: Commander Eileen M. Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Hawley, Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a shuttle mission.

The Effect of Grain Size and Strain on the Tensile Flow Stress of Aluminium at Room Temperature

DEFF Research Database (Denmark)

Hansen, Niels

1977-01-01

stress-grain size relationship was analyzed in terms of matrix strengthening and grain boundary strengthening according to the dislocation concept of Ashby. At intermediate strains this approach gives a good description of the effect of strain, grain size and purity on the flow stress.......Tensile-stress-strain data over a strain range from 0.2 to 30% were obtained at room temperature for 99.999 and 99.5% aluminium as a function of grain size. The yield stress-grain size relationship can be expressed by a Petch-Hall relation with approximately the same slope for the two materials....... The flow stress-grain size relationship can adequately be expressed by a modified Petch-Hall relation; for 99.999% aluminium material the slope increases with strain through a maximum around 15–20%, whereas for 99.5% aluminium the slope decreases with the strain to zero at strains about 10%. The flow...

Mechanical Properties of Lightweight Porous Magnesium Processed Through Powder Metallurgy

Science.gov (United States)

Zou, Ning; Li, Qizhen

2018-02-01

Porous magnesium (Mg) samples with various overall porosities (28.4 ± 1.8%, 35.5 ± 2.5%, 45.4 ± 1.9%, and 62.4 ± 2.2%) were processed through powder metallurgy and characterized to study their mechanical properties. Different porosities were obtained by utilizing different mass fractions of space holder camphene. Camphene was removed by sublimation before sintering and contributed to processing porous Mg with high purity and small average pore size. The average pore size increased from 5.2 µm to 15.1 µm with increase of the porosity from 28.4 ± 1.8% to 62.4 ± 2.2%. Compressive strain-stress data showed that the strain hardening rate, yield strength, and ultimate compressive strength decreased with increase of the porosity. The theoretical yield strength of porous Mg obtained using the Gibson-Ashby model agreed with experimental data.

Characterization of Ti-6Al-4V open cellular foams fabricated by additive manufacturing using electron beam melting

International Nuclear Information System (INIS)

Murr, L.E.; Gaytan, S.M.; Medina, F.; Martinez, E.; Martinez, J.L.; Hernandez, D.H.; Machado, B.I.; Ramirez, D.A.; Wicker, R.B.

2010-01-01

Ti-6Al-4V open cellular foams were fabricated by additive manufacturing using electron beam melting (EBM). Foam models were developed from CT-scans of aluminum open cellular foams and embedded in CAD for EBM. These foams were fabricated with solid cell structures as well as hollow cell structures and exhibit tailorable stiffness and strength. The strength in proportion to the measured microindentation hardness is as much as 40% higher for hollow cell (wall) structures in contrast to solid, fully dense EBM fabricated components. Plots of relative stiffness versus relative density were in good agreement with the Gibson-Ashby model for open cellular foam materials. Stiffness or Young's modulus values measured using a resonant frequency-damping analysis technique were found to vary inversely with porosity especially for solid cell wall, open cellular structure foams. These foams exhibit the potential for novel biomedical, aeronautics, and automotive applications.

On the internal representation of numerical magnitude and physical size.

Science.gov (United States)

Fitousi, Daniel

2014-01-01

A nascent idea in the numerical cognition literature--the analogical hypothesis (Pinel, Piazza, Bihan, & Dehaene, 2004)--assumes a common noisy code for the representation of symbolic (e.g., numerals) and nonsymbolic (e.g., numerosity, physical size, luminance) magnitudes. The present work subjected this assumption to various tests from the perspective of General Recognition Theory (GRT; Ashby &Townsend, 1986)--a multidimensional extension of Signal Detection Theory (Green & Swets, 1966). The GRT was applied to the dimensions of numerical magnitude and physical size with the following goals: (a) characterizing the internal representation of these dimensions in the psychological space, and (b) assessing various types of (in)dependence and separability governing the perception of these dimensions. The results revealed various violations of independence and separability with Stroop incongruent, but not with Stroop congruent stimuli. The outcome suggests that there are deep differences in architecture between Stroop congruent and incongruent stimuli that reach well beyond the semantic relationship involved.

Development of ideal solution and validation of stiffness and strength by finite element method for truss-wall corrugated cellular solids

International Nuclear Information System (INIS)

Choi, Jeong Ho; Lee, Jung Hwan; Lee, Je Hyun

2014-01-01

The objective of this study is to find the density, stiffness, and strength of truss-wall unit cell models. The diamond-corrugation, triangular-corrugation, and Navtruss-corrugation models are used for the unit cell. The ideal solutions derived for these are based on solid wall unit cell models and are developed using the Gibson-Ashby theory. To verify the ideal solutions of the models, the density, strength, and stiffness are simulated using ABAQUS software and compared with the ideal solutions on a log-log scale. The material properties of stainless steel 304 are applied. The diameter is 0.5 mm; the opening width is 0.5 mm; and the corrugation angle is 45 .deg. . Consequently, the relative Young's modulus and relative yield strength of the truss-wall unit models are good matches for the ideal expectations. It may be possible to apply a truss-wall model to diverse fields such as transportation or biomedical applications as one of the open-cell cellular solids.

The STS-93 crew pose in front of Columbia

Science.gov (United States)

1999-01-01

The STS-93 crew pose in front of the Space Shuttle orbiter Columbia following their landing on runway 33 at the Shuttle Landing Facility. Main gear touchdown occurred at 11:20:35 p.m. EDT on July 27. From left to right, they are Mission Specialists Catherine G. Coleman (Ph.D.) and Stephen A. Hawley (Ph.D.), Pilot Jeffrey S. Ashby, Commander Eileen Collins, and Mission Specialist Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). The mission's primary objective was to deploy the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. This was the 95th flight in the Space Shuttle program and the 26th for Columbia. The landing was the 19th consecutive Shuttle landing in Florida and the 12th night landing in Shuttle program history. On this mission, Collins became the first woman to serve as a Shuttle commander.

Columbia makes a nighttime landing at KSC following STS-93

Science.gov (United States)

1999-01-01

The Space Shuttle orbiter Columbia swoops out of the darkness onto runway 33 at the Shuttle Landing Facility after a successful mission of nearly five days and 1.8 million miles. Main gear touchdown was at 11:20:35 p.m. EDT on July 27. Aboard are the STS-93 crew members: Commander Eileen M. Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Stephen A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). The mission's primary objective was to deploy the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. This was the 95th flight in the Space Shuttle program and the 26th for Columbia. The landing was the 19th consecutive Shuttle landing in Florida and the 12th night landing in Shuttle program history.

STS-93 crew have breakfast before launch in O&C Building

Science.gov (United States)

1999-01-01

The STS-93 crew gathers a third time for a pre-launch breakfast in the Operations and Checkout Building before suiting up for launch. After Space Shuttle Columbia's July 22 launch attempt was scrubbed due to the weather, the launch was rescheduled for Friday, July 23, at 12:24 a.m. EDT. Seated from left are Mission Specialists Catherine G. Coleman (Ph.D.) and Steven A. Hawley (Ph.D.); Commander Eileen M. Collins; Mission Specialist Michel Tognini, of France, who represents the Centre National d'Etudes Spatiales (CNES); and Pilot Jeffrey S. Ashby. STS-93 is a five- day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. Collins is the first woman to serve as commander of a Shuttle mission. The target landing date is July 27, 1999, at 11:20 p.m. EDT.

STS-93 Commander Collins poses in front of Columbia

Science.gov (United States)

1999-01-01

STS-93 Commander Eileen Collins poses in front of the Space Shuttle orbiter Columbia following her textbook landing on runway 33 at the Shuttle Landing Facility. Main gear touchdown occurred at 11:20:35 p.m. EDT on July 27. On this mission, Collins became the first woman to serve as a Shuttle commander. Also on board were her fellow STS-93 crew members: Pilot Jeffrey S. Ashby and Mission Specialists Stephen A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). The mission's primary objective was to deploy the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. This was the 95th flight in the Space Shuttle program and the 26th for Columbia. The landing was the 19th consecutive Shuttle landing in Florida and the 12th night landing in Shuttle program history.

Development of ideal solution and validation of stiffness and strength by finite element method for truss-wall corrugated cellular solids

Energy Technology Data Exchange (ETDEWEB)

Choi, Jeong Ho [Samjung E and W, Changwon (Korea, Republic of); Lee, Jung Hwan [Korea Institute of Materials Science,Changwon (Korea, Republic of); Lee, Je Hyun [Changwon National University, Changwon (Korea, Republic of)

2014-05-15

The objective of this study is to find the density, stiffness, and strength of truss-wall unit cell models. The diamond-corrugation, triangular-corrugation, and Navtruss-corrugation models are used for the unit cell. The ideal solutions derived for these are based on solid wall unit cell models and are developed using the Gibson-Ashby theory. To verify the ideal solutions of the models, the density, strength, and stiffness are simulated using ABAQUS software and compared with the ideal solutions on a log-log scale. The material properties of stainless steel 304 are applied. The diameter is 0.5 mm; the opening width is 0.5 mm; and the corrugation angle is 45 .deg. . Consequently, the relative Young's modulus and relative yield strength of the truss-wall unit models are good matches for the ideal expectations. It may be possible to apply a truss-wall model to diverse fields such as transportation or biomedical applications as one of the open-cell cellular solids.

Homeostatic Agent for General Environment

Science.gov (United States)

Yoshida, Naoto

2018-03-01

One of the essential aspect in biological agents is dynamic stability. This aspect, called homeostasis, is widely discussed in ethology, neuroscience and during the early stages of artificial intelligence. Ashby's homeostats are general-purpose learning machines for stabilizing essential variables of the agent in the face of general environments. However, despite their generality, the original homeostats couldn't be scaled because they searched their parameters randomly. In this paper, first we re-define the objective of homeostats as the maximization of a multi-step survival probability from the view point of sequential decision theory and probabilistic theory. Then we show that this optimization problem can be treated by using reinforcement learning algorithms with special agent architectures and theoretically-derived intrinsic reward functions. Finally we empirically demonstrate that agents with our architecture automatically learn to survive in a given environment, including environments with visual stimuli. Our survival agents can learn to eat food, avoid poison and stabilize essential variables through theoretically-derived single intrinsic reward formulations.

Mechanical properties and failure behavior of unidirectional porous ceramics

Science.gov (United States)

Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J.

2016-04-01

We show that the honeycomb out-of-plane model derived by Gibson and Ashby can be applied to describe the compressive behavior of unidirectional porous materials. Ice-templating allowed us to process samples with accurate control over pore volume, size, and morphology. These samples allowed us to evaluate the effect of this microstructural variations on the compressive strength in a porosity range of 45-80%. The maximum strength of 286 MPa was achieved in the least porous ice-templated sample (P(%) = 49.9), with the smallest pore size (3 μm). We found that the out-of-plane model only holds when buckling is the dominant failure mode, as should be expected. Furthermore, we controlled total pore volume by adjusting solids loading and sintering temperature. This strategy allows us to independently control macroporosity and densification of walls, and the compressive strength of ice-templated materials is exclusively dependent on total pore volume.

Epicoccum nigrum P16, a Sugarcane Endophyte, Produces Antifungal Compounds and Induces Root Growth

Science.gov (United States)

Fávaro, Léia Cecilia de Lima; Sebastianes, Fernanda Luiza de Souza; Araújo, Welington Luiz

2012-01-01

Background Sugarcane is one of the most important crops in Brazil, mainly because of its use in biofuel production. Recent studies have sought to determine the role of sugarcane endophytic microbial diversity in microorganism-plant interactions, and their biotechnological potential. Epicoccum nigrum is an important sugarcane endophytic fungus that has been associated with the biological control of phytopathogens, and the production of secondary metabolites. In spite of several studies carried out to define the better conditions to use E. nigrum in different crops, little is known about the establishment of an endophytic interaction, and its potential effects on plant physiology. Methodology/Principal Findings We report an approach based on inoculation followed by re-isolation, molecular monitoring, microscopic analysis, plant growth responses to fungal colonization, and antimicrobial activity tests to study the basic aspects of the E. nigrum endophytic interaction with sugarcane, and the effects of colonization on plant physiology. The results indicate that E. nigrum was capable of increasing the root system biomass and producing compounds that inhibit the in vitro growth of sugarcane pathogens Fusarium verticillioides, Colletotrichum falcatum, Ceratocystis paradoxa, and Xanthomomas albilineans. In addition, E. nigrum preferentially colonizes the sugarcane surface and, occasionally, the endophytic environment. Conclusions/Significance Our work demonstrates that E. nigrum has great potential for sugarcane crop application because it is capable of increasing the root system biomass and controlling pathogens. The study of the basic aspects of the interaction of E. nigrum with sugarcane demonstrated the facultative endophytism of E. nigrum and its preference for the phylloplane environment, which should be considered in future studies of biocontrol using this species. In addition, this work contributes to the knowledge of the interaction of this ubiquitous endophyte

Estimation of transfused red cell survival using an enzyme-linked antiglobulin test

International Nuclear Information System (INIS)

Kickler, T.S.; Smith, B.; Bell, W.; Drew, H.; Baldwin, M.; Ness, P.M.

1985-01-01

An enzyme-linked antiglobulin test (ELAT) method was developed to estimate survival of transfused red cells. This procedure is based on a principle analogous to that of the Ashby technique were antigenically distinct red cells are transfused and their survival studied. The authors compared the ELAT survival to the 51 Chromium method ( 51 Cr) in four patients. Three patients with hypoproliferative anemias showed T 1/2 by ELAT of 17.5, 18, and 17 days versus 18.5, 20, and 19 days by the 51 Cr method. A fourth patient with traumatic cardiac hemolysis had two studies performed. In this case, the ELAT showed a T 1/2 of 10 and 8.1 days while 51 Cr T 1/2 values were 11 and 10.5 days. The ELAT method for measuring red cell survival yielded data which agreed closely with the results of the 51 Cr method. Although 51 Cr is the accepted method for red cell survival, the ELAT method can be used to estimate transfused red cell survival

STS-93 Commander Collins suits up before launch

Science.gov (United States)

1999-01-01

In the Operations and Checkout Building, STS-93 Commander Eileen M. Collins gets help donning her launch and entry suit. After Space Shuttle Columbia's July 20 launch attempt was scrubbed at the T-7 second mark in the countdown, the launch was rescheduled for Thursday, July 22, at 12:28 a.m. EDT. The target landing date is July 26, 1999, at 11:24 p.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The new telescope is 20 to 50 times more sensitive than any previous X- ray telescope and is expected unlock the secrets of supernovae, quasars and black holes. The STS-93 crew numbers five: Commander Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Stephen A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a shuttle mission.

STS-93 crew cheers as they near the van for ride to launch pad

Science.gov (United States)

1999-01-01

The STS-93 crew wave and cheer as they head for the 'Astrovan' a third time to take them to Launch Pad 39-B and liftoff of Space Shuttle Columbia. In their orange launch and entry suits, they are (starting at rear, left to right) Mission Specialists Michel Tognini of France, who represents the Centre National d'Etudes Spatiales (CNES), Catherine G. Coleman (Ph.D.), and Stephen A. Hawley (Ph.D.); Pilot Jeffrey S. Ashby; and Commander Eileen M. Collins. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. The target landing date is July 27 at 11:20 p.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. Collins is the first woman to serve as commander of a Shuttle mission.

STS-93 crew heads out of O&C for ride to launch pad

Science.gov (United States)

1999-01-01

The STS-93 crew wave and smile at onlookers as they walk out of the Operations and Checkout Building for the third time enroute to Launch Pad 39-B and liftoff of Space Shuttle Columbia. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. The target landing date is July 27, 1999, at 11:20 p.m. EDT. In their orange launch and entry suits, they are (starting at rear, left to right) Mission Specialists Michel Tognini of France, who represents the Centre National d'Etudes Spatiales (CNES), and Catherine G. Coleman (Ph.D.); Pilot Jeffrey S. Ashby; Mission Specialist Stephen A. Hawley (Ph.D.); and Commander Eileen M. Collins. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. Collins is the first woman to serve as commander of a Shuttle mission.

Unravelling the materials genome: Symmetry relationships in alloy properties

International Nuclear Information System (INIS)

Toda-Caraballo, Isaac; Galindo-Nava, Enrique I.; Rivera-Díaz-del-Castillo, Pedro E.J.

2013-01-01

Highlights: ► Research strategy for Accelerated Metallurgy project is outlined. ► Surprising symmetry among atomic, nanoscale and mechanical properties. ► Generalisation of Ashby diagrams via principal component analysis. ► Atomic-related properties can be described with linear regression. ► Mechanical properties modelled via Kocks–Mecking-type physical method. -- Abstract: Metals and alloys have been indispensable for technological progress, but only a fraction of the possible ternary systems (combinations of three elements) is known. Statistical inference methods combined with physical models are presented to discover new systems of enhanced properties. It is demonstrated that properties originating from atomic-level interactions can be described employing a linear regression analysis, but properties incorporating microstructural and thermal history effects require a balance between physical and statistical modelling. In spite of this, there is a remarkable degree of symmetry among all properties, and by employing a principal components analysis it is shown that ten properties essential to engineering can be described well in a three dimensional space. This will aid in the discovery of novel alloying systems

Self-critical perfectionism, daily stress, and disclosure of daily emotional events.

Science.gov (United States)

Richardson, Clarissa M E; Rice, Kenneth G

2015-10-01

Although disclosure of stressful events can alleviate distress, self-critical perfectionism may pose an especially strong impediment to disclosure during stress, likely contributing to poorer psychological well-being. In the current study, after completing a measure of self-critical perfectionism (the Discrepancy subscale of the Almost Perfect Scale--Revised; Slaney, Rice, Mobley, Trippi, & Ashby, 2001), 396 undergraduates completed measures of stress and disclosure at the end of each day for 1 week. Consistent with hypotheses and previous research, multilevel modeling results indicated significant intraindividual coupling of daily stress and daily disclosure where disclosure was more likely when experiencing high stress than low stress. As hypothesized, Discrepancy moderated the relationship between daily stress and daily disclosure. Individuals higher in self-critical perfectionism (Discrepancy) were less likely to engage in disclosure under high stress, when disclosure is often most beneficial, than those with lower Discrepancy scores. These results have implications for understanding the role of stress and coping in the daily lives of self-critical perfectionists. (c) 2015 APA, all rights reserved).

Selection of materials with potential in sensible thermal energy storage

International Nuclear Information System (INIS)

Fernandez, A.I.; Martinez, M.; Segarra, M.; Martorell, I.; Cabeza, L.F.

2010-01-01

Thermal energy storage is a technology under investigation since the early 1970s. Since then, numerous new applications have been found and much work has been done to bring this technology to the market. Nevertheless, the materials used either for latent or for sensible storage were mostly investigated 30 years ago, and the research has lead to improvement in their performance under different conditions of applications. In those years a significant number of new materials were developed in many fields other than storage and energy, but a great effort to characterize and classify these materials was done. Taking into account the fact that thousands of materials are known and a large number of new materials are developed every year, the authors use the methodology for materials selection developed by Prof. Ashby to give an overview of other materials suitable to be used in thermal energy storage. Sensible heat storage at temperatures between 150 and 200 C is defined as a case study and two different scenarios were considered: long term sensible heat storage and short term sensible heat storage. (author)

Micromechanical models to guide the development of synthetic ‘brick and mortar’ composites

Science.gov (United States)

Begley, Matthew R.; Philips, Noah R.; Compton, Brett G.; Wilbrink, David V.; Ritchie, Robert O.; Utz, Marcel

2012-08-01

This paper describes a micromechanical analysis of the uniaxial response of composites comprising elastic platelets (bricks) bonded together with thin elastic perfectly plastic layers (mortar). The model yields closed-form results for the spatial variation of displacements in the bricks as a function of constituent properties, which can be used to calculate the effective properties of the composite, including elastic modulus, strength and work-to-failure. Regime maps are presented which indicate critical stresses for failure of the bricks and mortar as a function of constituent properties and brick architecture. The solution illustrates trade-offs between elastic modulus, strength and dissipated work that are a result of transitions between various failure mechanisms associated with brick rupture and rupture of the interfaces. Detailed scaling relationships are presented with the goal of providing material developers with a straightforward means to identify synthesis targets that balance competing mechanical behaviors and optimize material response. Ashby maps are presented to compare potential brick and mortar composites with existing materials, and identify future directions for material development.

HISTORY EDUCATION - SOME THOUGHTS FROM THE UK: interviews Peter J. Lee

Directory of Open Access Journals (Sweden)

Cristiani Bereta da Silva

2014-05-01

Peter Lee was, until he very recently retired, a senior lecturer in the History Education Unit at the Institute of Education at the University of London. Having taught History in primary and secondary schools, Professor Lee has coordinated several research projects related to History Teaching and Learning, including CHATA (Concepts of History and Teaching Approaches a project well-known in Brazil. Several of his publications investigate the ideas that children and teenagers have over History in several books, chapters, and articles – many of these with Rosalyn Ashby as co-author.  Some of his articles have been translated to Portuguese, circulating among researchers concerned with understanding how children learn History. The questions in this interview have been elaborated so that Peter Lee’s reflections may collaborate with the development of History Teaching and History Education research in Brazil. All contact has been made via e-mail, a rather useful tool that has shortened the distance between Florianópolis and London for a few long moments between July and October 2012.

Mechanisms of sintering

International Nuclear Information System (INIS)

Mohan, Ashok; Soni, N.C.; Moorthy, V.K.

1980-01-01

The basic mechanisms by which the material moves during sintering have not only held a strange fascination but are also very important in determining the properties of the end product. Kuczynski's exponent method has been subsequently refined by several schools to make it increasingly reliable. There is now a fairly good understanding of mechanisms in some of the materials. However in others the issue is complicated by their basic nature. The problems of ambiguity in criterion and that of more than one mechanism being simultaneously operative have been tackled with dexterity by Ashby for drawing sintering mechanism diagrams. The method has been modified to give Relative Contribution Diagrams (RCD). These yield additional information and have been used for analysis. The main criticism against this is that it uses a very large number of rate equations and material properties, which can communicate their inaccuracies to the diagram. A case study of UO 2 was undertaken and it has been shown quantitatively that inaccuracies in a smaller number of properties only affect the diagrams to any significant extent. (auth.)

Materials selection for a transport packaging of Mo-99

International Nuclear Information System (INIS)

Hara, Debora H.S.; Lucchesi, Raquel F.; Mancini, Victor A.; Rossi, Jesualdo L.; Fiore, Marina

2015-01-01

The radiopharmaceuticals are radioactive isotopes used in nuclear medicine for more accurate diagnosis and treatment of diseases or dysfunctions. Currently, the most important radionuclide for the preparation of radiopharmaceuticals for diagnostic purposes is technetium-99m ( 99m Tc), a product of the radioactive decay of molybdenum-99 (Mo-99). The aim of this work was the materials selection that can enable the manufacture of a package for Mo-99 transport with the aid of CES EduPack program and the methodology developed by Ashby. The ESTAR program was used to check the occurrence of Bremsstrahlung and the XCOM program was used to calculate the attenuation coefficient of gamma radiation from some of the selected materials for the shield; after, the thickness required for radiation shielding was calculated. From the results, the materials selected as potential candidates for the manufacture of the shielding were the tungsten alloys. Related to the thermal insulation and the impact protection, woods, plywoods and particle boards stand out. With regard to internal and external coatings, the selected materials focus on groups of steels and nickel alloys. (author)

Unravelling the materials genome: Symmetry relationships in alloy properties

Energy Technology Data Exchange (ETDEWEB)

Toda-Caraballo, Isaac [Department of Materials Science and Metallurgy, University of Cambridge New Museums Site, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Galindo-Nava, Enrique I. [Department of Materials Science and Metallurgy, University of Cambridge New Museums Site, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Delft University of Technology, Mekelweg 2, Delft 2628 CD (Netherlands); Rivera-Díaz-del-Castillo, Pedro E.J., E-mail: pejr2@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge New Museums Site, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom)

2013-07-25

Highlights: ► Research strategy for Accelerated Metallurgy project is outlined. ► Surprising symmetry among atomic, nanoscale and mechanical properties. ► Generalisation of Ashby diagrams via principal component analysis. ► Atomic-related properties can be described with linear regression. ► Mechanical properties modelled via Kocks–Mecking-type physical method. -- Abstract: Metals and alloys have been indispensable for technological progress, but only a fraction of the possible ternary systems (combinations of three elements) is known. Statistical inference methods combined with physical models are presented to discover new systems of enhanced properties. It is demonstrated that properties originating from atomic-level interactions can be described employing a linear regression analysis, but properties incorporating microstructural and thermal history effects require a balance between physical and statistical modelling. In spite of this, there is a remarkable degree of symmetry among all properties, and by employing a principal components analysis it is shown that ten properties essential to engineering can be described well in a three dimensional space. This will aid in the discovery of novel alloying systems.

Comportamiento productivo y fitosanitario de la nueva variedad de caña de azúcar (Saccharum spp. TUC 95-37 en Tucumán, R. Argentina Productivity and disease tolerance of TUC 95-37, a new sugarcane (Saccharum spp. variety in Tucumán, Argentina

Directory of Open Access Journals (Sweden)

Ernesto R. Chavanne

2012-06-01

Full Text Available En este trabajo se presenta el comportamiento productivo y fitosanitario del nuevo cultivar de caña de azúcar (Saccharum spp. TUC 95-37, obtenido y seleccionado por el Programa de Mejoramiento Genético de la Caña de Azúcar de la Estación Experimental Agroindustrial Obispo Colombres (Tucumán, R. Argentina. La información que se presenta proviene de 24 cosechas realizadas en ensayos con 18 genotipos, implantados de acuerdo a un diseño experimental de bloques completamente aleatorizados con tres repeticiones. Los ensayos se replicaron en seis localidades de Tucumán y fueron evaluados en cuatro edades de corte (caña planta, soca 1, soca 2 y soca 3 entre los años 2002 y 2005. Las variables toneladas de caña/ha y de azúcar/ha y rendimiento fabril porciento se evaluaron en mayo. Para cada variable, edad y localidad se realizaron análisis de la varianza y pruebas de comparación de medias. También se aplicó la metodología de GGE biplot como herramienta gráfica, para identificar genotipos superiores y estables frente a distintos ambientes de expresión. Se evaluó además el comportamiento fitosanitario de TUC 95-37. Los resultados indicaron que la nueva variedad evidenció un comportamiento productivo similar al de LCP 85-384 en la mayoría de las edades de corte y localidades evaluadas. En caña planta, el nuevo cultivar fue el genotipo más productivo, presentando además una amplia adaptación a diferentes ambientes. En soca 1 y 2, TUC 95-37 resultó segunda en orden de mérito, siendo estable en las diferentes localidades. En soca 3, la nueva variedad evidenció una menor estabilidad frente al ambiente. Con respecto al comportamiento fitosanitario, TUC 95-37 se comportó como moderadasmente resistente a roya marrón (Puccinia melanocephala, a escaldadura de la hoja (Xanthomonas albilineans y a carbón (Sporisorium scitamineum. Se mostró moderadamente susceptible al mosaico (Sugarcane mosaic virus y a estría roja (Acidovorax

Influence of cell shape on mechanical properties of Ti-6Al-4V meshes fabricated by electron beam melting method.

Science.gov (United States)

Li, S J; Xu, Q S; Wang, Z; Hou, W T; Hao, Y L; Yang, R; Murr, L E

2014-10-01

Ti-6Al-4V reticulated meshes with different elements (cubic, G7 and rhombic dodecahedron) in Materialise software were fabricated by additive manufacturing using the electron beam melting (EBM) method, and the effects of cell shape on the mechanical properties of these samples were studied. The results showed that these cellular structures with porosities of 88-58% had compressive strength and elastic modulus in the range 10-300MPa and 0.5-15GPa, respectively. The compressive strength and deformation behavior of these meshes were determined by the coupling of the buckling and bending deformation of struts. Meshes that were dominated by buckling deformation showed relatively high collapse strength and were prone to exhibit brittle characteristics in their stress-strain curves. For meshes dominated by bending deformation, the elastic deformation corresponded well to the Gibson-Ashby model. By enhancing the effect of bending deformation, the stress-strain curve characteristics can change from brittle to ductile (the smooth plateau area). Therefore, Ti-6Al-4V cellular solids with high strength, low modulus and desirable deformation behavior could be fabricated through the cell shape design using the EBM technique. Copyright © 2014 Acta Materialia Inc. All rights reserved.

Influence of microstructure on the room temperature flow behaviour of Mod. 9Cr-1Mo steel

International Nuclear Information System (INIS)

Kishore, R.; Singh, R.N.; Kashyap, B.P.

2005-01-01

The normalizing heat treatment conditions of T-91 grade steel were altered in order to get different austenite/martensite packet grain sizes. Tempering of the steel was carried out at (1) peak hardening temperature and (2) at temperature closer to commercial treatment. Tempering of these specimens, austenitized at a chosen temperature, at the two tempering temperatures resulted in the modification of the fine scale structure by the formation of different carbide types and their distribution. Tensile testing of these specimens (under all the three conditions) was conducted at ambient temperature in order to study the influence of the microstructures on the deformation behaviour. The flow stress, hardness and room temperature impact toughness showed an inverse relation with the martensite packet/austenite grain size. The deformation behavior of the specimens under the three heat treatment conditions was analyzed according to Ashby's model was made assuming. The slip length, λ g , was estimated from the σ-ε 1/2 plot and compared with the relevant microstructure parameters. The as-received material was seen to undergo aligatoring damage during cold rolling and a modification in their microstructure could render a defect free product. (author)

STS-93 M.S. Hawley suits up for launch

Science.gov (United States)

1999-01-01

During final launch preparations in the Operations and Checkout Building, STS-93 Mission Specialist Steven A. Hawley (Ph.D.)gets help donning his launch and entry suit from a suit tech. After Space Shuttle Columbia's July 20 launch attempt was scrubbed at the T-7 second mark in the countdown, the launch was rescheduled for Thursday, July 22, at 12:28 a.m. EDT. The target landing date is July 26, 1999, at 11:24 p.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The new telescope is 20 to 50 times more sensitive than any previous X- ray telescope and is expected unlock the secrets of supernovae, quasars and black holes. The STS-93 crew numbers five: Commander Eileen M. Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Hawley, Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a shuttle mission.

STS-93 crew gathers for pre-launch breakfast in O&C Building

Science.gov (United States)

1999-01-01

The STS-93 crew gathers a second time for a pre-launch breakfast in the Operations and Checkout Building before suiting up for launch. After Space Shuttle Columbia's July 20 launch attempt was scrubbed at the T-7 second mark in the countdown, the launch was rescheduled for Thursday, July 22, at 12:28 a.m. EDT. Seated from left are Mission Specialists Michel Tognini, of France, who represents the Centre National d'Etudes Spatiales (CNES), and Steven A. Hawley (Ph.D.), Commander Eileen M. Collins, Pilot Jeffrey S. Ashby, and Mission Specialist Catherine G. Coleman (Ph.D.). STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The new telescope is 20 to 50 times more sensitive than any previous X-ray telescope and is expected unlock the secrets of supernovae, quasars and black holes. Collins is the first woman to serve as commander of a Shuttle mission. The target landing date is July 26, 1999, at 11:24 p.m. EDT.

STS-93 Commander Collins waves after suiting up before launch

Science.gov (United States)

1999-01-01

During final launch preparations in the Operations and Checkout Building, STS-93 Commander Eileen M. Collins waves after donning her launch and entry suit. After Space Shuttle Columbia's July 20 launch attempt was scrubbed at the T-7 second mark in the countdown, the launch was rescheduled for Thursday, July 22, at 12:28 a.m. EDT. The target landing date is July 26, 1999, at 11:24 p.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The new telescope is 20 to 50 times more sensitive than any previous X-ray telescope and is expected unlock the secrets of supernovae, quasars and black holes. The STS-93 crew numbers five: Commander Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Stephen A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a shuttle mission.

Scaling of compression strength in disordered solids: metallic foams

Directory of Open Access Journals (Sweden)

J. Kováčik

2016-03-01

Full Text Available The scaling of compression strength with porosity for aluminium foams was investigated. The Al 99.96, AlMg1Si0.6 and AlSi11Mg0.6 foams of various porosity, sample size with and without surface skin were tested in compression. It was observed that the compression strength of aluminium foams scales near the percolation threshold with Tf ≈ 1.9 - 2.0 almost independently on the matrix alloy, sample size and presence of surface skin. The difference of the obtained values of Tf to the theoretical estimate of Tf = 2.64 ± 0.3 by Arbabi and Sahimi and to Ashby estimate of 1.5 was explained using an analogy with the Daoud and Coniglio approach to the scaling of the free energy of sol-gel transition. It leads to the finding that, there are two different universality classes for the critical exponent Tf: when the stretching forces dominate Tf = f = 2.1, respectively when bending forces prevail Tf = .d = 2.64 seems to be valid. Another possibility is the validity of relation Tf ≤ f which varies only according to the universality class of modulus of elasticity in foam.

Tantalum powder consolidation, modeling and properties

International Nuclear Information System (INIS)

Bingert, S.R.; Vargas, V.D.; Sheinberg, H.C.

1996-01-01

A systematic approach was taken to investigate the consolidation of tantalum powders. The effects of sinter time, temperature and ramp rate; hot isostatic pressing (HIP) temperature and time; and powder oxygen content on consolidation density, kinetics, microstructure, crystallographic texture, and mechanical properties have been evaluated. In general, higher temperatures and longer hold times resulted in higher density compacts with larger grain sizes for both sintering and HIP'ing. HIP'ed compacts were consistently higher in density than sintered products. The higher oxygen content powders resulted in finer grained, higher density HIP'ed products than the low oxygen powders. Texture analysis showed that the isostatically processed powder products demonstrated a near random texture. This resulted in isotropic properties in the final product. Mechanical testing results showed that the HIP'ed powder products had consistently higher flow stresses than conventionally produced plates, and the sintered compacts were comparable to the plate material. A micromechanics model (Ashby HIP model) has been employed to predict the mechanisms active in the consolidation processes of cold isostatic pressing (CIP), HIP and sintering. This model also predicts the density of the end product and whether grain growth should be expected under the applied processing conditions

Mechanical, electrical and micro-structural properties of La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3} perovskite-based ceramic foams

Energy Technology Data Exchange (ETDEWEB)

Gupta, Ravindra K; Kim, Eun Yi; Noh, Ho Sung; Whang, Chin Myung [School of Materials Science and Engineering, Inha University, 253, Yonghyun-dong, Nam-gu, Incheon 402-751 (Korea, Republic of)

2008-02-07

Mechanical, electrical and micro-structural properties of new electronic conducting ceramic foams are reported. Ceramic foams are prepared using the slurry of La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (LSCF) by the polymeric sponge method, which is followed by spray coating for increasing the number of coatings-sinterings on polyurethane foams of 30, 45 and 60 ppi (pores per linear inch). An increase in the number of coatings-sinterings and ppi improved the compressive strength, density and electrical conductivity by decreasing the porosity to {approx}76%, as also observed by the SEM study. The three-times coated-sintered ceramic foams (60 ppi) exhibited optimum values of compressive strength of {approx}1.79 MPa and relative density of {approx}0.24 at 25 deg. C and electrical conductivity of {approx}22 S cm{sup -1} at 600 deg. C with an activation energy of {approx}0.22 eV indicating its suitability as a solid oxide fuel cell current collector. The experimental results are discussed in terms of the Gibson and Ashby theoretical model. (fast track communication)

Understanding the application of knowledge management to the safety critical facilities

International Nuclear Information System (INIS)

Ilina, Elena

2010-01-01

Challenges to the operating nuclear power plants and transport infrastructures are outlined. It is concluded that most aggravating factors are related to knowledge. Thus, of necessity, effective knowledge management is required. Knowledge management theories are reviewed in their historical perspective as a natural extension and unification of information theories and theories about learning. The first line is identified with names as Wiener, Ashby, Shannon, Jaynes, Dretske, Harkevich. The second line - with Vygotsky, Engestroem, Carayannis. The recent developments of knowledge management theorists as Davenport, Prusak, Drew, Wiig, Zack are considered stressing learning, retaining of knowledge, approaching the state awareness of awareness, and alignment of knowledge management with the strategy of the concerned organizations. Further, some of the details and results are presented of what is achieved so far. More specifically, knowledge management tools are applied to the practical work activities as event reporting, data collection, condition assessment, verification of safety functions and incident investigation. Obstacles are identified and improvements are proposed. Finally, it is advised to continue to implement and further develop knowledge management tools in the organizations involved in various aspects of safety critical facilities

Perceived association between diagnostic and non-diagnostic cues of women's sexual interest: General Recognition Theory predictors of risk for sexual coercion.

Science.gov (United States)

Farris, Coreen; Viken, Richard J; Treat, Teresa A

2010-01-01

Young men's errors in sexual perception have been linked to sexual coercion. The current investigation sought to explicate the perceptual and decisional sources of these social perception errors, as well as their link to risk for sexual violence. General Recognition Theory (GRT; [Ashby, F. G., & Townsend, J. T. (1986). Varieties of perceptual independence. Psychological Review, 93, 154-179]) was used to estimate participants' ability to discriminate between affective cues and clothing style cues and to measure illusory correlations between men's perception of women's clothing style and sexual interest. High-risk men were less sensitive to the distinction between women's friendly and sexual interest cues relative to other men. In addition, they were more likely to perceive an illusory correlation between women's diagnostic sexual interest cues (e.g., facial affect) and non-diagnostic cues (e.g., provocative clothing), which increases the probability that high-risk men will misperceive friendly women as intending to communicate sexual interest. The results provide information about the degree of risk conferred by individual differences in perceptual processing of women's interest cues, and also illustrate how translational scientists might adapt GRT to examine research questions about individual differences in social perception.

OPTIMASI KONSENTRASI INOKULUM, RASIO C:N:P DAN pH PADA PROSES BIOREMEDIASI LIMBAH PENGILANGAN MINYAK BUMI MENGGUNAKAN KULTUR CAMPURAN

Directory of Open Access Journals (Sweden)

Syukria Ikhsan Zam

2010-03-01

Full Text Available The purposes of this research were to obtain the best inoculum concentration, C:N:P ratio, and pH, and also to identify the ability of mixed culture of hydrocarbonoclastic bacteria in oil waste degradation. The isolats were used are Acinetobacter baumanni, Alcaligenes eutrophus, Bacillus sp1., Methylococcus capsulatus, Bacillus sp2., Morococcus sp., Pseudomonas diminuta, Xanthomonas albilineans, Bacillus cereus and Flavobacterium branchiophiia. Variation of inoculum concentrations were 10%, 15%, and 20% (v/v, C:N:P ratios were 100:10:1, 100:10:0,5, 100:5:1, and 100:5:0,5, and pH were 6,5, 7,0, 7,5. Observed parameters in optimization were Total Plate Count (TPC the culture every 24 hours, Total Petroleum Hydrocarbon (TPH and Chemical Oxygen Demand (COD examined at the end of the bioremediation period. Best optimization result then analyzed with GC/MS. Optimization result indicated the best inoculum concentration was 10% with TPH degradation 61,79% and COD slope 61,75%. It is assumed that the low value of TPH degradation and COD slope at 15% and 20% inoculum concentration were caused by competition inside the bacterial population at that high inoculum concentration. The competition result in low growth and degradation. C:N:P ratio was 100:5:1 with TPH degradation 66,55% and COD slope 85,18%. It is assumed that the C:N:P ratio is equal, so it can enhance the bioremediation procces. The best pH was 7,5 with TPH degradation 73,24% and COD slope 86,28%. The process at the optimum conditions using inoculum as a mixed culture enhanced the bioremediation process with the result as follows, TPH degradation 93,06%, COD 90,73% for treatment. The chromatogram indicated that total hydrocarbon compound from nC9 – nC32 have been degraded by 43,413% – 63,117%. A good result of bioremediation was obtained from mixed culture inoculum at 10% concentration, C:N:P ratio of 100:5:1, and pH 7,5.

Enzymatic characterization and gene identification of aconitate isomerase, an enzyme involved in assimilation of trans-aconitic acid, from Pseudomonas sp. WU-0701.

Science.gov (United States)

Yuhara, Kahori; Yonehara, Hiromi; Hattori, Takasumi; Kobayashi, Keiichi; Kirimura, Kohtaro

2015-11-01

trans-Aconitic acid is an unsaturated organic acid that is present in some plants such as soybean and wheat; however, it remains unclear how trans-aconitic acid is degraded and/or assimilated by living cells in nature. From soil, we isolated Pseudomonas sp. WU-0701 assimilating trans-aconitic acid as a sole carbon source. In the cell-free extract of Pseudomonas sp. WU-0701, aconitate isomerase (AI; EC 5.3.3.7) activity was detected. Therefore, it seems likely that strain Pseudomonas sp. WU-0701 converts trans-aconitic acid to cis-aconitic acid with AI, and assimilates this via the tricarboxylic acid cycle. For the characterization of AI from Pseudomonas sp. WU-0701, we performed purification, determination of enzymatic properties and gene identification of AI. The molecular mass of AI purified from cell-free extract was estimated to be ~ 25 kDa by both SDS/PAGE and gel filtration analyses, indicating that AI is a monomeric enzyme. The optimal pH and temperature of purified AI for the reaction were 6.0 °C and 37 °C, respectively. The gene ais encoding AI was cloned on the basis of the N-terminal amino acid sequence of the protein, and Southern blot analysis revealed that only one copy of ais is located on the bacterial genome. The gene ais contains an ORF of 786 bp, encoding a polypeptide of 262 amino acids, including the N-terminal 22 amino acids as a putative periplasm-targeting signal peptide. It is noteworthy that the amino acid sequence of AI shows 90% and 74% identity with molybdenum ABC transporter substrate-binding proteins of Pseudomonas psychrotolerans and Xanthomonas albilineans, respectively. This is the first report on purification to homogeneity, characterization and gene identification of AI. The nucleotide sequence of ais described in this article is available in the DDBJ/EMBL/GenBank nucleotide sequence databases under the Accession No. LC010980. © 2015 FEBS.

Study of the compression and wear-resistance properties of freeze-cast Ti and Ti‒5W alloy foams for biomedical applications.

Science.gov (United States)

Choi, Hyelim; Shil'ko, Serge; Gubicza, Jenő; Choe, Heeman

2017-08-01

Ti and Ti‒5wt% W alloy foams were produced by freeze-casting process and their mechanical behaviors were compared. The Ti‒5W alloy foam showed a typical acicular Widmanstätten α/β structure with most of the W dissolved in the β phase. An electron-probe microanalysis revealed that approximately 2wt% W was uniformly dissolved in the Ti matrix of Ti‒5W alloy foam with few partially dissolved W particles. The compressive-yield strength of Ti‒5W alloy foam (~323MPa) was approximately 20% higher than that of the Ti foam (~256MPa) owing to the solid-solution-strengthening effect of W in the Ti matrix, which also resulted in a dramatic improvement in the wear resistance of Ti‒5W alloy foam. The compressive behaviors of the Ti and Ti‒5W alloy foams were predicted by analytical models and compared with the experimental values. Compared with the Gibson-Ashby and cellular-lattice-structure-in-square-orientation models of porous materials, the orientation-averaging method provided prediction results that are much more accurate in terms of both the Young's modulus and the yield strength of the Ti and Ti‒5W alloy foams. Copyright © 2017 Elsevier Ltd. All rights reserved.

Competing Grain Boundary and Interior Deformation Mechanisms with Varying Sizes

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wei [University of Tennessee (UT); Gao, Yanfei [ORNL; Nieh, T. G. [University of Tennessee, Knoxville (UTK)

2018-01-01

In typical coarse-grained alloys, the dominant plastic deformations are dislocation gliding or climbing, and material strengths can be tuned by dislocation interactions with grain boundaries, precipitates, solid solutions, and other defects. With the reduction of grain size, the increase of material strengths follows the classic Hall-Petch relationship up to nano-grained materials. Even at room temperatures, nano-grained materials exhibit strength softening, or called the inverse Hall-Petch effect, as grain boundary processes take over as the dominant deformation mechanisms. On the other hand, at elevated temperatures, grain boundary processes compete with grain interior deformation mechanisms over a wide range of the applied stress and grain sizes. This book chapter reviews and compares the rate equation model and the microstructure-based finite element simulations. The latter explicitly accounts for the grain boundary sliding, grain boundary diffusion and migration, as well as the grain interior dislocation creep. Therefore the explicit finite element method has clear advantages in problems where microstructural heterogeneities play a critical role, such as in the gradient microstructure in shot peening or weldment. Furthermore, combined with the Hall-Petch effect and its breakdown, the above competing processes help construct deformation mechanism maps by extending from the classic Frost-Ashby type to the ones with the dependence of grain size.

Mechanical properties: wood lumber versus plastic lumber and thermoplastic composites

Directory of Open Access Journals (Sweden)

Bernardo Zandomenico Dias

Full Text Available Abstract Plastic lumber and thermoplastic composites are sold as alternatives to wood products. However, many technical standards and scientific studies state that the two materials cannot be considered to have the same structural behaviour and strength. Moreover, there are many compositions of thermoplastic-based products and plenty of wood species. How different are their mechanical properties? This study compares the modulus of elasticity and the flexural, compressive, tensile and shear strengths of such materials, as well as the materials' specific mechanical properties. It analyses the properties of wood from the coniferae and dicotyledon species and those of commercialized and experimental thermoplastic-based product formulations. The data were collected from books, scientific papers and manufacturers' websites and technical data sheets, and subsequently compiled and presented in Ashby plots and bar graphs. The high values of the compressive strength and specific compressive and tensile strengths perpendicular to the grain (width direction shown by the experimental thermoplastic composites compared to wood reveal their great potential for use in compressed elements and in functions where components are compressed or tensioned perpendicularly to the grain. However, the low specific flexural modulus and high density of thermoplastic materials limit their usage in certain civil engineering and building applications.

An experimental search for gamma radiation associated with thunderstorm activity

International Nuclear Information System (INIS)

Fryberger, D.

1992-11-01

This experiment is a repeat of an earlier experiment, but with more sensitive apparatus and in a location with a higher incidence of thunderstorm activity. The earlier experiment was undertaken by Ashby and Whitehead to investigate the theory that ball lightning might be associated with the annihilation of small amounts of antimatter, and it yielded some very interesting but inconclusive results. In the course of about 12 months of data taking, four high rate bursts of gamma radiation were detected. These events lasted a few seconds and had many thousands of counts (16500, 5000, 3700, and > 7700. Unfortunately, the association of these gamma ray bursts with thunderstorms or ball lightning was not clearly established, although one of the bursts did occur during a local thunderstorm in rough coincidence with a lightning bolt striking a flagpole about 100 yards from the gamma ray detection crystals. A pulse height spectrum taken for this burst (no spectrum was taken for the other three) exhibited a significant peak, well above background, the energy of which appeared to be compatible with the 511 keV positron annihilation line. While the peak could not be unambiguously attributed to positron annihilation, this certainly appeared to be the most likely source

Plant growth promotion properties of bacterial strains isolated from the rhizosphere of the Jerusalem artichoke (Helianthus tuberosus L.) adapted to saline-alkaline soils and their effect on wheat growth.

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Liu, Xiaolin; Li, Xiangyue; Li, Yan; Li, Runzhi; Xie, Zhihong

2017-03-01

The Jerusalem artichoke (JA; Helianthus tuberosus), known to be tolerant to saline-alkaline soil conditions, has been cultivated for many years in the Yellow River delta, Shandong Province coastal zone, in China. The aim of our study was to isolate nitrogen-fixing bacteria colonizing the rhizosphere of JA and to characterize other plant growth promotion properties. The ultimate goal was to identify isolates that could be used as inoculants benefiting an economic crop, in particular for improving wheat growth production in the Yellow River delta. Bacterial strains were isolated from the rhizosphere soil of JA on the basis of growth on nitrogen-free Ashby medium. Identification and phylogenetic analysis was performed after nucleotide sequencing of 16S rRNA gene. Plant-growth-promoting traits, such as nitrogen fixation activity, phosphate solubilization activity, indole-3-acetic acid production, were determined using conventional methods. Eleven strains were isolated and 6 of them were further examined for their level of salt tolerance and their effect on plant growth promotion. Inoculation of Enterobacter sp. strain N10 on JA and wheat led to significant increases in both root and shoot dry mass and shoot height. Enterobacter sp. strain N10 appeared to be the best plant-growth-promoting rhizobacteria to increase wheat productivity in future field applications.

Computer modelling of age hardening for cast aluminium alloys

International Nuclear Information System (INIS)

Wu, Linda; Ferguson, W George

2009-01-01

Age hardening, or precipitation hardening, is one of the most widely adopted techniques for strengthening of aluminium alloys. Although various age hardening models have been developed for aluminium alloys, from the large volume of literature reviewed, it appears that the bulk of the research has been concentrated on wrought aluminium alloys, only a few of the established precipitation models have been applied to the casting aluminium alloys. In the present work, there are two modelling methods that have been developed and applied to the casting aluminium alloys A356 and A357. One is based on the Shercliff-Ashby methodology to produce a process model, by which we mean a mathematical relationship between process variables (alloy composition, ageing temperature and time) and material properties (yield strength or hardness) through microstructure evolution (precipitate radius, volume fraction). The other method is based on the Kampmann and Wagner Numerical (KWN) model which deals with concomitant nucleation, growth and coarsening and is thus capable of predicting the full evolution of the particle size distribution and then a strength model is used to evaluate the resulting change in hardness or yield strength at room temperature by taking into account contributions from lattice resistance, solid solution hardening and precipitation hardening.

Mutual information, perceptual independence, and holistic face perception.

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Fitousi, Daniel

2013-07-01

The concept of perceptual independence is ubiquitous in psychology. It addresses the question of whether two (or more) dimensions are perceived independently. Several authors have proposed perceptual independence (or its lack thereof) as a viable measure of holistic face perception (Loftus, Oberg, & Dillon, Psychological Review 111:835-863, 2004; Wenger & Ingvalson, Learning, Memory, and Cognition 28:872-892, 2002). According to this notion, the processing of facial features occurs in an interactive manner. Here, I examine this idea from the perspective of two theories of perceptual independence: the multivariate uncertainty analysis (MUA; Garner & Morton, Definitions, models, and experimental paradigms. Psychological Bulletin 72:233-259, 1969), and the general recognition theory (GRT; Ashby & Townsend, Psychological Review 93:154-179, 1986). The goals of the study were to (1) introduce the MUA, (2) examine various possible relations between MUA and GRT using numerical simulations, and (3) apply the MUA to two consensual markers of holistic face perception(-)recognition of facial features (Farah, Wilson, Drain, & Tanaka, Psychological Review 105:482-498, 1998) and the composite face effect (Young, Hellawell, & Hay, Perception 16:747-759, 1987). The results suggest that facial holism is generated by violations of several types of perceptual independence. They highlight the important theoretical role played by converging operations in the study of holistic face perception.

Nickel–carbon nanocomposites: Synthesis, structural changes and strengthening mechanisms

International Nuclear Information System (INIS)

Nunes, D.; Vilarigues, M.; Correia, J.B.; Carvalho, P.A.

2012-01-01

The present work investigates Ni–nanodiamond and Ni–graphite composites produced by mechanical synthesis and subsequent heat treatments. Processing of nickel–carbon nanocomposites by this powder metallurgy route poses specific challenges, as carbon phases are prone to carbide conversion and amorphization. The processing window for carbide prevention has been established through X-ray diffraction by a systematic variation of the milling parameters. Transmission electron microscopy confirmed the absence of carbide and showed homogeneous particle distributions, as well as intimate bonding between the metallic matrix and the carbon phases. Ring diffraction patterns of chemically extracted carbon phases demonstrated that milled nanodiamond preserved crystallinity, while an essentially amorphous nature could be inferred for milled graphite. Raman spectra confirmed that nanodiamond particles remained largely unaffected by mechanical synthesis, whereas the bands of milled graphite were significantly changed into the typical amorphous carbon fingerprint. The results on the annealed nanocomposites showed that milling with Ni accelerated graphitization of the carbon phases during heat treatments at 973 and 1073 K in both composites. At the finer scales, the nanocomposites exhibited a remarkable microhardness enhancement (∼70%) compared with pure nanostructured nickel. The Hall–Petch relation and the Orowan–Ashby equation are used to discuss strengthening mechanisms and the load transfer ability to the reinforcing particles.

Study on Topology Optimization Design, Manufacturability, and Performance Evaluation of Ti-6Al-4V Porous Structures Fabricated by Selective Laser Melting (SLM).

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Xu, Yangli; Zhang, Dongyun; Zhou, Yan; Wang, Weidong; Cao, Xuanyang

2017-09-07

The combination of topology optimization (TOP) and selective laser melting (SLM) provides the possibility of fabricating the complex, lightweight and high performance geometries overcoming the traditional manufacturing "bottleneck". This paper evaluates the biomechanical properties of porous structures with porosity from 40% to 80% and unit cell size from 2 to 8 mm, which are designed by TOP and manufactured by SLM. During manufacturability exploration, three typical structures including spiral structure, arched bridge structure and structures with thin walls and small holes are abstracted and investigated, analyzing their manufacturing limits and forming reason. The property tests show that dynamic elastic modulus and compressive strength of porous structures decreases with increases of porosity (constant unit cell size) or unit cell size (constant porosity). Based on the Gibson-Ashby model, three failure models are proposed to describe their compressive behavior, and the structural parameter λ is used to evaluate the stability of the porous structure. Finally, a numerical model for the correlation between porous structural parameters (unit cell size and porosity) and elastic modulus is established, which provides a theoretical reference for matching the elastic modulus of human bones from different age, gender and skeletal sites during innovative medical implant design and manufacturing.

Porosity and cell size control in alumina foam preparation by thermo-foaming of powder dispersions in molten sucrose

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Sujith Vijayan

2016-09-01

Full Text Available The foaming characteristics of alumina powder dispersions in molten sucrose have been studied as a function of alumina powder to sucrose weight ratio (WA/S and foaming temperature. The increase in foaming temperature significantly decreases the foaming and foam setting time and increases the foam volume due to an increase in the rate of OH condensation as well as a decrease in the viscosity of the dispersion. Nevertheless, the foam collapses beyond a critical foaming temperature, which depends on the WA/S. The sintering shrinkage depends mainly on the WA/S and marginally on the foaming temperature. The porosity (83.4–94.6 vol.% and cell size (0.55–1.6 mm increase with an increase in foaming temperature (120–170 °C and a decrease in WA/S (0.8–1.6. The drastic decrease in compressive strength and modulus beyond a WA/S of 1.2 is due to the pores generated on the cell walls and struts as a result of particle agglomeration. Gibson and Ashby plots show large deviation with respect to the model constants ‘C’ and ‘n’, especially at higher alumina powder to sucrose weight ratios.

A combined analysis of the Frost Multidimensional Perfectionism Scale (FMPS), Child and Adolescent Perfectionism Scale (CAPS), and Almost Perfect Scale-Revised (APS-R): Different perfectionist profiles in adolescent high school students.

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Sironic, Amanda; Reeve, Robert A

2015-12-01

To investigate differences and similarities in the dimensional constructs of the Frost Multidimensional Perfectionism Scale (FMPS; Frost, Marten, Lahart, & Rosenblate, 1990), Child and Adolescent Perfectionism Scale (CAPS; Flett, Hewitt, Boucher, Davidson, & Munro, 2000), and Almost Perfect Scale-Revised (APS-R; Slaney, Rice, Mobley, Trippi, & Ashby, 2001), 938 high school students completed the 3 perfectionism questionnaires, as well as the Depression Anxiety Stress Scales (DASS; Lovibond & Lovibond, 1995). Preliminary analyses revealed commonly observed factor structures for each perfectionism questionnaire. Exploratory factor analysis of item responses from the questionnaires (combined) yielded a 4-factor solution (factors were labeled High Personal Standards, Concerns, Doubts and Discrepancy, Externally Motivated Perfectionism, and Organization and Order). A latent class analysis of individuals' mean ratings on each of the 4 factors yielded a 6-class solution. Three of the 6 classes represented perfectionist subgroups (labeled adaptive perfectionist, externally motivated maladaptive perfectionist, and mixed maladaptive perfectionist), and 3 represented nonperfectionist subgroups (labeled nonperfectionist A, nonperfectionist B, and order and organization nonperfectionist). Each of the 6 subgroups was meaningfully associated with the DASS. Findings showed that 3 out of 10 students were classified as maladaptive perfectionists, and maladaptive perfectionists were more prevalent than adaptive perfectionists. In sum, it is evident that combined ratings from the FMPS, CAPS, and APS-R offer a meaningful characterization of perfectionism. (c) 2015 APA, all rights reserved).

Detection of material property errors in handbooks and databases using artificial neural networks with hidden correlations

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Zhang, Y. M.; Evans, J. R. G.; Yang, S. F.

2010-11-01

The authors have discovered a systematic, intelligent and potentially automatic method to detect errors in handbooks and stop their transmission using unrecognised relationships between materials properties. The scientific community relies on the veracity of scientific data in handbooks and databases, some of which have a long pedigree covering several decades. Although various outlier-detection procedures are employed to detect and, where appropriate, remove contaminated data, errors, which had not been discovered by established methods, were easily detected by our artificial neural network in tables of properties of the elements. We started using neural networks to discover unrecognised relationships between materials properties and quickly found that they were very good at finding inconsistencies in groups of data. They reveal variations from 10 to 900% in tables of property data for the elements and point out those that are most probably correct. Compared with the statistical method adopted by Ashby and co-workers [Proc. R. Soc. Lond. Ser. A 454 (1998) p. 1301, 1323], this method locates more inconsistencies and could be embedded in database software for automatic self-checking. We anticipate that our suggestion will be a starting point to deal with this basic problem that affects researchers in every field. The authors believe it may eventually moderate the current expectation that data field error rates will persist at between 1 and 5%.

Efecto del uso del suelo sobre rizobacterias fosfatosolubizadoras y diazotroficas en el distrito de riego del río zulia,norte de santander (colombia

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Ronal Fernando-Cañon

2009-07-01

Full Text Available It was quantified the population of diazotrophic and phosphate solubilizer bacteria with the aim of determine the effect of the use of soils during different periods of intervention with culture of rice in three agro-ecological zones of the District of Irrigation of the Zulia river. The results showed that the management of the culture of rice in the different studied zones significantly influenced the population of microorganisms in all the studied culture media, excepting the semi-solid culture media JMV. The populations of the genera Azospirillum spp., Azotobacter spp., Beijerinckia spp., were influenced by the fertility of the soils in the zones of Buena Esperanza and Restauración compared with Limoncito, where the quantities of organic matter and nutritional escential elements were lower. It were obtained 28 isolations of entophytic, associative, free-living diazotrophic and phosphate solubilizer rhizobacteria according with their macroscopic characteristics in the culture media Batata, JMV, Ashby and nutritive, from the analysis of the population in the zones of Buena Esperanza, Restauración and Limoncito. These isolations were purified and preserved in sterilized saline solution (0.85% NaCl at 4°C in the Laboratory of Microbiology of the Colombian Agricultural Institute, ICA, with the purpose to be used in subsequent studies about their potential as biofertilizers in rice cultured soils of the department.

VizieR Online Data Catalog: CANDELS multiwavelength catalog (Galametz+, 2013)

Science.gov (United States)

Galametz, A.; Grazian, A.; Fontana, A.; Ferguson, H. C.; Ashby, M. L. N.; Barro, G.; Castellano, M.; Dahlen, T.; Donley, J. L.; Faber, S. M.; Grogin, N.; Guo, Y.; Huang, K.-H.; Kocevski, D. D.; Koekemoer, A. M.; Lee, K.-S.; McGrath, E. J.; Peth, M.; Willner, S. P.; Almaini, O.; Cooper, M.; Cooray, A.; Conselice, C. J.; Dickinson, M.; Dunlop, J. S.; Fazio, G. G.; Foucaud, S.; Gardner, J. P.; Giavalisco, M.; Hathi, N. P.; Hartley, W. G.; Koo, D. C.; Lai, K.; de Mello, D. F.; McLure, R. J.; Lucas, R. A.; Paris, D.; Pentericci, L.; Santini, P.; Simpson, C.; Sommariva, V.; Targett, T.; Weiner, B. J.; Wuyts, S.; CANDELS Team

2013-06-01

The present multiwavelength catalog is based on public data in the CANDELS UDS field (J2000 position: 02:17:37.5-05:12:00) located within the original UDS field. It includes: * CANDELS HST/ACS (F606W, F814W) and HST/WFC3 (F125W, F160W); Grogin et al. 2011ApJS..197...35G, Koekemoer et al. 2011ApJS..197...36K. * CFHT U-band (UKIDSS; Almaini et al. in prep.), * SUBARU B, V, Rc, i', z' (SXDS; Furusawa et al. 2008, Cat. J/ApJS/176/1) * VLT/HAWK-I Y and Ks bands (HUGS; Fontana et al. in prep.) * UKIRT/WFCam J, H, K (UKIDSS DR8; Almaini et al. in prep.) * Spitzer/IRAC SEDS 3.6 and 4.5um (SEDS; Ashby et al. 2013ApJ...769...80A) * Spitzer/IRAC SpUDS 5.8, 8.0um (PI: J. Dunlop). The catalog is F160W-selected and contains 35932 sources over an area of 201.7 square arcmin and includes radio and X-ray detected sources and spectroscopic redshifts available for 210 sources. The full official CANDELS UDS catalog (which contains some extra columns including additional SExtractor parameters derived from the F160W image) can be found on the CANDELS website at: http://candels.ucolick.org/data_access/UDS.html (1 data file).

Porous Nb-Ti-Ta alloy scaffolds for bone tissue engineering: Fabrication, mechanical properties and in vitro/vivo biocompatibility.

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Liu, Jue; Ruan, Jianming; Chang, Lin; Yang, Hailin; Ruan, Wei

2017-09-01

Porous Nb-Ti-Ta (at.%) alloys with the pore size of 100-600μm and the porosity of 50%-80% were fabricated by the combination of the sponge impregnation technique and sintering method. The results revealed that the pores were well connected with three-dimensional (3D) network structure, which showed morphological similarity to the anisotropic porous structure of human bones. The results also showed that the alloys could provide the compressive Young's modulus of 0.11±0.01GPa to 2.08±0.09GPa and the strength of 17.45±2.76MPa to 121.67±1.76MPa at different level of porosity, indicating that the mechanical properties of the alloys are similar to those of human bones. Pore structure on the compressive properties was also discussed on the basis of the deformation mode. The relationship between compressive properties and porosity was well consistent with the Gibson-Ashby model. The mechanical properties could be tailored to match different requirements of the human bones. Moreover, the alloys had good biocompatibility due to the porous structure with higher surface, which were suitable for apatite formation and cell adhesion. In conclusion, the porous Nb-Ti-Ta alloy is potentially useful in the hard tissue implants for the appropriate mechanical properties as well as the good biocompatible properties. Copyright © 2017. Published by Elsevier B.V.

Comparing the effects of positive and negative feedback in information-integration category learning.

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Freedberg, Michael; Glass, Brian; Filoteo, J Vincent; Hazeltine, Eliot; Maddox, W Todd

2017-01-01

Categorical learning is dependent on feedback. Here, we compare how positive and negative feedback affect information-integration (II) category learning. Ashby and O'Brien (2007) demonstrated that both positive and negative feedback are required to solve II category problems when feedback was not guaranteed on each trial, and reported no differences between positive-only and negative-only feedback in terms of their effectiveness. We followed up on these findings and conducted 3 experiments in which participants completed 2,400 II categorization trials across three days under 1 of 3 conditions: positive feedback only (PFB), negative feedback only (NFB), or both types of feedback (CP; control partial). An adaptive algorithm controlled the amount of feedback given to each group so that feedback was nearly equated. Using different feedback control procedures, Experiments 1 and 2 demonstrated that participants in the NFB and CP group were able to engage II learning strategies, whereas the PFB group was not. Additionally, the NFB group was able to achieve significantly higher accuracy than the PFB group by Day 3. Experiment 3 revealed that these differences remained even when we equated the information received on feedback trials. Thus, negative feedback appears significantly more effective for learning II category structures. This suggests that the human implicit learning system may be capable of learning in the absence of positive feedback.

Mechanical Properties of Shock-Damaged Rocks

Science.gov (United States)

He, Hongliang; Ahrens, T. J.

1994-01-01

Stress-strain tests were performed both on shock-damaged gabbro and limestone. The effective Young's modulus decreases with increasing initial damage parameter value, and an apparent work-softening process occurs prior to failure. To further characterize shock-induced microcracks, the longitudinal elastic wave velocity behavior of shock-damaged gabbro in the direction of compression up to failure was measured using an acoustic transmission technique under uniaxial loading. A dramatic increase in velocity was observed for the static compressive stress range of 0-50 MPa. Above that stress range, the velocity behavior of lightly damaged (D(sub 0) less than 0.1) gabbro is almost equal to unshocked gabbro. The failure strength of heavily-damaged (D(sub 0) greater than 0.1) gabbro is approx. 100-150 MPa, much lower than that of lightly damaged and unshocked gabbros (approx. 230-260 MPa). Following Nur's theory, the crack shape distribution was analyzed. The shock-induced cracks in gabbro appear to be largely thin penny-shaped cracks with c/a values below 5 x 10(exp -4). Moreover, the applicability of Ashby and Sammis's theory relating failure strength and damage parameter of shock-damaged rocks was examined and was found to yield a good estimate of the relation of shock-induced deficit in elastic modulus with the deficit in compressive strength.

Comparing the neural basis of monetary reward and cognitive feedback during information-integration category learning.

Science.gov (United States)

Daniel, Reka; Pollmann, Stefan

2010-01-06

The dopaminergic system is known to play a central role in reward-based learning (Schultz, 2006), yet it was also observed to be involved when only cognitive feedback is given (Aron et al., 2004). Within the domain of information-integration category learning, in which information from several stimulus dimensions has to be integrated predecisionally (Ashby and Maddox, 2005), the importance of contingent feedback is well established (Maddox et al., 2003). We examined the common neural correlates of reward anticipation and prediction error in this task. Sixteen subjects performed two parallel information-integration tasks within a single event-related functional magnetic resonance imaging session but received a monetary reward only for one of them. Similar functional areas including basal ganglia structures were activated in both task versions. In contrast, a single structure, the nucleus accumbens, showed higher activation during monetary reward anticipation compared with the anticipation of cognitive feedback in information-integration learning. Additionally, this activation was predicted by measures of intrinsic motivation in the cognitive feedback task and by measures of extrinsic motivation in the rewarded task. Our results indicate that, although all other structures implicated in category learning are not significantly affected by altering the type of reward, the nucleus accumbens responds to the positive incentive properties of an expected reward depending on the specific type of the reward.

Study on iron metabolism in children using double labelling of 51Cr and 59Fe

International Nuclear Information System (INIS)

Kobayashi, Masatsura

1974-01-01

In the children before and after treatment for iron deficiency anemia and those on ingesting a long-term low caloric and iron diet, life span of Ashby Technique 1/2(AST) red cells, circulatory blood volume (CBV), plasma iron disappearance(PID), red cell-iron utility(RCIU), plasma-iron turnover rate(PITR), and red cell-ironturnover rate(RCITR) were respectively determined using double labeling of 51 Cr and 59 Fe, and the following results and conclusions were obtained: In the patients with iron deficiency anemia, the rate of RCIU was highly increased, and simultaneously the shortening in AST was observed. Among the children with the iron deficiency anemia, five patients were examined immediately after the improvement on the anemia by iron drugs; the serum iron (SFe) averaged 74μg/ml. So the erthropiesis appeared to recover to normal, yet AST has hardly changed, still more has it shortened. In five children with celebral palsy associated with disturbance of physical development, who had ingested a long-term liquid low iron diet no evident increase of RCIU was found except for high calues of RCITR. The shortening in AST was not entirely seen in contrast with that of the simple alimentary iron deficiency anemia. Besides the CBV measured par kg of weight showed the remarkable increase. (Oyama, S.)

Non-symbiotic bacterial diazotrophs from of agricultural crops of San Carlos. Córdoba, Colombia

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Cecilia Lara Mantilla

2007-07-01

Full Text Available Diazotrophic Azotobacter sp and Azospirrillum sp bacteria were isolated from the rhizosphere of plantain, (Musa paradisiaca, corn, wheat and fallow areas (uncultivated, but covered by fallen leaves in the San Carlos region (in the Sinú valley in the Córdoba department, Colombia. Microbial populations were identified by biochemical tests; physiological characters were examined using Gram reaction in different mediums: Burk’s, Ashby and Jensen’s (Azotobacter sp and Burk’s, NFB and Congo-red medium (Azospirillum sp. The study was aimed at determining ion ammonium production from Azotobacter sp and Azospirrillum sp isolates; ion ammonium was quantified according to Berthelot’s colorimetric technique (phenol-hypochlorite. This method was modified and standardised in line with using a Perkin-Elmer Lamba 11 UV-Vis spectrometer. As a result of this study, 14 isolates have been shown to be ammonium-producers at concentrations ranging from 0.9 mg/l to 5.2 mg/l; A16PG (5.1545 mg/l and A26M1P (5.1743 mg/l yielded the highest ammonium concentrations for Azotobacter sp and A5M1G (4.6741 mg/l for Azospirrillum sp. Biological N2 fixation (BNF by associative diazotrophic bacteria has contributed towards increasing harvest yield, thereby reducing the need for nitrogenised fertilisers and the emission of greenhouse gases (such as N2O and obtaining economic and environmental benefits for farming.

Foam behavior of solid glass spheres – Zn22Al2Cu composites under compression stresses

International Nuclear Information System (INIS)

Aragon-Lezama, J.A.; Garcia-Borquez, A.; Torres-Villaseñor, G.

2015-01-01

Solid glass spheres – Zn22Al2Cu composites, having different densities and microstructures, were elaborated and studied under compression. Their elaboration process involves alloy melting, spheres submersion into the liquid alloy and finally air cooling. The achieved composites with densities 2.6884, 2.7936 and 3.1219 g/cm 3 were studied in casting and thermally induced, fine-grain matrix microstructures. Test samples of the composites were compressed at a 10 −3 s −1 strain rate, and their microstructure characterized before and after compression by using optical and scanning electron microscopes. Although they exhibit different compression behavior depending on their density and microstructure, all of them show an elastic region at low strains, reach their maximum stress (σ max ) at hundreds of MPa before the stress fall or collapse up to a lowest yield point (LYP), followed by an important plastic deformation at nearly constant stress (σ p ): beyond this plateau, an extra deformation can be limitedly reached only by a significant stress increase. This behavior under compression stresses is similar to that reported for metal foams, being the composites with fine microstructure which nearest behave to metal foams under this pattern. Nevertheless, the relative values of the elastic modulus, and maximum and plateau stresses do not follow the Ashby equations by changing the relative density. Generally, the studied composites behave as foams under compression, except for their peculiar parameters values (σ max , LYP, and σ p )

Investigation of Macroscopic Brittle Creep Failure Caused by Microcrack Growth Under Step Loading and Unloading in Rocks

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Li, Xiaozhao; Shao, Zhushan

2016-07-01

The growth of subcritical cracks plays an important role in the creep of brittle rock. The stress path has a great influence on creep properties. A micromechanics-based model is presented to study the effect of the stress path on creep properties. The microcrack model of Ashby and Sammis, Charles' Law, and a new micro-macro relation are employed in our model. This new micro-macro relation is proposed by using the correlation between the micromechanical and macroscopic definition of damage. A stress path function is also introduced by the relationship between stress and time. Theoretical expressions of the stress-strain relationship and creep behavior are derived. The effects of confining pressure on the stress-strain relationship are studied. Crack initiation stress and peak stress are achieved under different confining pressures. The applied constant stress that could cause creep behavior is predicted. Creep properties are studied under the step loading of axial stress or the unloading of confining pressure. Rationality of the micromechanics-based model is verified by the experimental results of Jinping marble. Furthermore, the effects of model parameters and the unloading rate of confining pressure on creep behavior are analyzed. The coupling effect of step axial stress and confining pressure on creep failure is also discussed. The results provide implications on the deformation behavior and time-delayed rockburst mechanism caused by microcrack growth on surrounding rocks during deep underground excavations.

Assessing historical empathy through simulation – How do Finnish teacher students achieve contextual historical empathy?

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Jukka Rantala

2011-05-01

Full Text Available There has been a great deal of international debate about introducing historical empathy as the focus in teaching history. However, as it is, the contents of the concept have been included in the curricula in many countries. Nevertheless, practising stepping into the shoes of a person from a previous era is still in its infancy in schools in many locations – Finland included. This article discusses Finnish class teacher students' understanding of historical empathy. The article is based on a study where 360 class teacher students played a game simulating the Cuban Missile Crisis. Their task was to assume the roles of the superpower leaders and make decisions on the basis of these roles. The simulation showed that a majority of the student teachers are able to attain a level of contextual historical empathy. They were able to empathize with the historical context in question and make such decisions that would have been possible for the historical actors. Some of the playing groups on the other hand, referred to their current knowledge and attitudes, which, according to Ashby and Lee's empathy classification, shows lower-level empathy. The study corroborates previous research results concerning great discrepancies in the understanding of empathy prevalent within one age group. Moreover, the study raises the question of how historical empathy should be handled in teaching if many future teachers have difficulties in understanding it.

N2 fixer free-living bacteria in two soils of Cauca Valley

International Nuclear Information System (INIS)

Cardona M, Sigifredo; Sanchez de Prager, Marina

1998-01-01

Several soil samples were taken in two agricultural soils, located in Palmira and Ricaurte, Cauca Valley, with the aim of establishing the presence of free life N 2 fixer bacteria and to identify the predominant species. Such soils were chemical and physically characterized and were collected information about their farmer management. For each one of them were counted the N 2 a symbiotic fixers by the dilution method and culture in N free Ashby media. The main bacteria isolated in each soil were, purified and identified. The physical chemistry conditions in both soils favored the presence of such microorganisms because of the pH, closer to neutral and an adequate nutrient content in Ricaurte, the soils was an inceptisol, moderately deep and growing passion fruit Passiflora edulis sims, in which have had an intensive use of chemicals, similar to palmira's soil; there, the microbial population was 5.5 x 107 U.F.C. N 2 fixer bacteria/g of dry soil. In Palmira, it was a mollisol growing tomato Lycopersicon esculentum mill with a population of 5.1 x 107 U.F.C./g of dry soil; both figures indicated the abundance of such microbiological resource and the potential for being explored in sustainable agricultural systems. In Ricaurte it was isolated Azotobacter is a main strain (probably a. chroococcum, according IMI) and in Palmira, Stenotroghomonas maltophilia (IMI), well known as a growth promoter in wheat and sunflower; referred in some cases as lightly pathogen in humans

Incorporating damage mechanics into explosion simulation models

International Nuclear Information System (INIS)

Sammis, C.G.

1993-01-01

The source region of an underground explosion is commonly modeled as a nested series of shells. In the innermost open-quotes hydrodynamic regimeclose quotes pressures and temperatures are sufficiently high that the rock deforms as a fluid and may be described using a PVT equation of state. Just beyond the hydrodynamic regime, is the open-quotes non-linear regimeclose quotes in which the rock has shear strength but the deformation is nonlinear. This regime extends out to the open-quotes elastic radiusclose quotes beyond which the deformation is linear. In this paper, we develop a model for the non-linear regime in crystalline source rock where the nonlinearity is mostly due to fractures. We divide the non-linear regime into a open-quotes damage regimeclose quotes in which the stresses are sufficiently high to nucleate new fractures from preexisting ones and a open-quotes crack-slidingclose quotes regime where motion on preexisting cracks produces amplitude dependent attenuation and other non-linear effects, but no new cracks are nucleated. The boundary between these two regimes is called the open-quotes damage radius.close quotes The micromechanical damage mechanics recently developed by Ashby and Sammis (1990) is used to write an analytic expression for the damage radius in terms of the initial fracture spectrum of the source rock, and to develop an algorithm which may be used to incorporate damage mechanics into computer source models for the damage regime. Effects of water saturation and loading rate are also discussed

Modeling of contact theories for the manipulation of biological micro/nanoparticles in the form of circular crowned rollers based on the atomic force microscope

International Nuclear Information System (INIS)

Korayem, M. H.; Khaksar, H.; Taheri, M.

2013-01-01

This article has dealt with the development and modeling of various contact theories for biological nanoparticles shaped as cylinders and circular crowned rollers for application in the manipulation of different biological micro/nanoparticles based on Atomic Force Microscope. First, the effective contact forces were simulated, and their impact on contact mechanics simulation was investigated. In the next step, the Hertz contact model was simulated and compared for gold and DNA nanoparticles with the three types of spherical, cylindrical, and circular crowned roller type contact geometries. Then by reducing the length of the cylindrical section in the circular crowned roller geometry, the geometry of the body was made to approach that of a sphere, and the results were compared for DNA nanoparticles. To anticipatory validate the developed theories, the results of the cylindrical and the circular crowned roller contacts were compared with the results of the existing spherical contact simulations. Following the development of these contact models for the manipulation of various biological micro/nanoparticles, the cylindrical and the circular crowned roller type contact theories were modeled based on the theories of Lundberg, Dowson, Nikpur, Heoprich, and Hertz for the manipulation of biological micro/nanoparticles. Then, for a more accurate validation, the results obtained from the simulations were compared with those obtained by the finite element method and with the experimental results available in previous articles. The previous research works on the simulation of nanomanipulation have mainly investigated the contact theories used in the manipulation of spherical micro/nanoparticles. However since in real biomanipulation situations, biological micro/nanoparticles of more complex shapes need to be displaced in biological environments, this article therefore has modeled and compared, for the first time, different contact theories for use in the biomanipulation of

Foam behavior of solid glass spheres – Zn22Al2Cu composites under compression stresses

Energy Technology Data Exchange (ETDEWEB)

Aragon-Lezama, J.A., E-mail: alja@correo.azc.uam.mx [Departamento de Materiales, Universidad Autónoma Metropolitana-A, Avenida San Pablo 180, Colonia Reynosa Tamaulipas, 02200 México, D.F., México (Mexico); Garcia-Borquez, A., E-mail: a.garciaborquez@yahoo.com.mx [Ciencia de Materiales, ESFM – Instituto Politécnico Nacional, Edif. 9, Unid. Prof. A. Lopez Mateos, Colonia Lindavista, 07738 México, D.F., México (Mexico); Torres-Villaseñor, G., E-mail: gtorres@unam.mx [Departamento de Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apdo., P 70-360, México, D.F., México (Mexico)

2015-06-25

Solid glass spheres – Zn22Al2Cu composites, having different densities and microstructures, were elaborated and studied under compression. Their elaboration process involves alloy melting, spheres submersion into the liquid alloy and finally air cooling. The achieved composites with densities 2.6884, 2.7936 and 3.1219 g/cm{sup 3} were studied in casting and thermally induced, fine-grain matrix microstructures. Test samples of the composites were compressed at a 10{sup −3} s{sup −1} strain rate, and their microstructure characterized before and after compression by using optical and scanning electron microscopes. Although they exhibit different compression behavior depending on their density and microstructure, all of them show an elastic region at low strains, reach their maximum stress (σ{sub max}) at hundreds of MPa before the stress fall or collapse up to a lowest yield point (LYP), followed by an important plastic deformation at nearly constant stress (σ{sub p}): beyond this plateau, an extra deformation can be limitedly reached only by a significant stress increase. This behavior under compression stresses is similar to that reported for metal foams, being the composites with fine microstructure which nearest behave to metal foams under this pattern. Nevertheless, the relative values of the elastic modulus, and maximum and plateau stresses do not follow the Ashby equations by changing the relative density. Generally, the studied composites behave as foams under compression, except for their peculiar parameters values (σ{sub max}, LYP, and σ{sub p})

"Self-critical perfectionism, daily stress, and disclosure of daily emotional events": Correction to Richardson and Rice (2015).

Science.gov (United States)

2016-01-01

Reports an error in "Self-critical perfectionism, daily stress, and disclosure of daily emotional events" by Clarissa M. E. Richardson and Kenneth G. Rice (Journal of Counseling Psychology, 2015[Oct], Vol 62[4], 694-702). In the article, the labels of the two lines in Figure 1 were inadvertently transposed. The dotted line should be labeled High SCP and the solid line should be labeled Low SCP. The correct version is present in the erratum. (The following abstract of the original article appeared in record 2015-30890-001.) Although disclosure of stressful events can alleviate distress, self-critical perfectionism may pose an especially strong impediment to disclosure during stress, likely contributing to poorer psychological well-being. In the current study, after completing a measure of self-critical perfectionism (the Discrepancy subscale of the Almost Perfect Scale-Revised; Slaney, Rice, Mobley, Trippi, & Ashby, 2001), 396 undergraduates completed measures of stress and disclosure at the end of each day for 1 week. Consistent with hypotheses and previous research, multilevel modeling results indicated significant intraindividual coupling of daily stress and daily disclosure where disclosure was more likely when experiencing high stress than low stress. As hypothesized, Discrepancy moderated the relationship between daily stress and daily disclosure. Individuals higher in self-critical perfectionism (Discrepancy) were less likely to engage in disclosure under high stress, when disclosure is often most beneficial, than those with lower Discrepancy scores. These results have implications for understanding the role of stress and coping in the daily lives of self-critical perfectionists. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Modeling the anomalous flow behavior of Ni3Al intermetallic single crystals

International Nuclear Information System (INIS)

Choi, Y.S.; Parthasarathy, T.A.; Dimiduk, D.M.; Uchic, M.D.

2004-01-01

In this study we present a new constitutive model for Ni3Al and Ni3(Al, X) alloys that was developed to represent many of the unusual plastic flow behavior found in L12 intermetallics while maintaining consistency with the experimentally-observed evolution of dislocation substructure. In particular, we sought to develop a model that would not only predict the anomalous increase of the yield strength with increasing temperature, but would also capture other important flow characteristics such as extremely high work-hardening rates that change anomalously with temperature, and a flow stress that is partially to fully reversible with temperature. For this model, we have treated work-hardening as arising from two different sources. Thermally-reversible work hardening is accounted for using the description of screw dislocation motion proposed by Caillard, which involves exhaustion of mobile dislocations by cross-slip locking of the dislocation core and athermal unlocking. Thermally-irreversible work hardening is accounted for using an approach consistent with the theoretical framework proposed by Ezz and Hirsch, which involves both the multiplication of Frank-Reed sources and the interaction of edge-dislocation segments with cross-slip locking events and the dislocation forest. Both work-hardening contributions were incorporated into the rate formulation for thermally-activated plastic flow proposed by Kocks, Argon and Ashby. We will show simulation results for the flow response of Ni3(Al, X) crystals over a wide range of temperatures in the anomalous flow regime, and we will compare these findings with experimental data

Analytic processing of distance.

Science.gov (United States)

Dopkins, Stephen; Galyer, Darin

2018-01-01

How does a human observer extract from the distance between two frontal points the component corresponding to an axis of a rectangular reference frame? To find out we had participants classify pairs of small circles, varying on the horizontal and vertical axes of a computer screen, in terms of the horizontal distance between them. A response signal controlled response time. The error rate depended on the irrelevant vertical as well as the relevant horizontal distance between the test circles with the relevant distance effect being larger than the irrelevant distance effect. The results implied that the horizontal distance between the test circles was imperfectly extracted from the overall distance between them. The results supported an account, derived from the Exemplar Based Random Walk model (Nosofsky & Palmieri, 1997), under which distance classification is based on the overall distance between the test circles, with relevant distance being extracted from overall distance to the extent that the relevant and irrelevant axes are differentially weighted so as to reduce the contribution of irrelevant distance to overall distance. The results did not support an account, derived from the General Recognition Theory (Ashby & Maddox, 1994), under which distance classification is based on the relevant distance between the test circles, with the irrelevant distance effect arising because a test circle's perceived location on the relevant axis depends on its location on the irrelevant axis, and with relevant distance being extracted from overall distance to the extent that this dependency is absent. Copyright © 2017 Elsevier B.V. All rights reserved.

Modeling and additive manufacturing of bio-inspired composites with tunable fracture mechanical properties.

Science.gov (United States)

Dimas, Leon S; Buehler, Markus J

2014-07-07

Flaws, imperfections and cracks are ubiquitous in material systems and are commonly the catalysts of catastrophic material failure. As stresses and strains tend to concentrate around cracks and imperfections, structures tend to fail far before large regions of material have ever been subjected to significant loading. Therefore, a major challenge in material design is to engineer systems that perform on par with pristine structures despite the presence of imperfections. In this work we integrate knowledge of biological systems with computational modeling and state of the art additive manufacturing to synthesize advanced composites with tunable fracture mechanical properties. Supported by extensive mesoscale computer simulations, we demonstrate the design and manufacturing of composites that exhibit deformation mechanisms characteristic of pristine systems, featuring flaw-tolerant properties. We analyze the results by directly comparing strain fields for the synthesized composites, obtained through digital image correlation (DIC), and the computationally tested composites. Moreover, we plot Ashby diagrams for the range of simulated and experimental composites. Our findings show good agreement between simulation and experiment, confirming that the proposed mechanisms have a significant potential for vastly improving the fracture response of composite materials. We elucidate the role of stiffness ratio variations of composite constituents as an important feature in determining the composite properties. Moreover, our work validates the predictive ability of our models, presenting them as useful tools for guiding further material design. This work enables the tailored design and manufacturing of composites assembled from inferior building blocks, that obtain optimal combinations of stiffness and toughness.

Range shortening, radiation transport, and Rayleigh-Taylor instability phenomena in ion-beam-driven inertial-fusion-reactor-size targets: Implosion, ignition, and burn phases

International Nuclear Information System (INIS)

Long, K.A.; Tahir, N.A.

1987-01-01

In this paper we present an analysis of the theory of the energy deposition of ions in cold materials and hot dense plasmas together with numerical calculations for heavy and light ions of interest to ion-beam fusion. We have used the gorgon computer code of Long, Moritz, and Tahir (which is an extension of the code originally written for protons by Nardi, Peleg, and Zinamon) to carry out these calculations. The energy-deposition data calculated in this manner has been used in the design of heavy-ion-beam-driven fusion targets suitable for a reactor, by its inclusion in the medusa code of Christiansen, Ashby, and Roberts as extended by Tahir and Long. A number of other improvements have been made in this code and these are also discussed. Various aspects of the theoretical analysis of such targets are discussed including the calculation of the hydrodynamic stability, the hydrodynamic efficiency, and the gain. Various different target designs have been used, some of them new. In general these targets are driven by Bi + ions of energy 8--12 GeV, with an input energy of 4--6.5 MJ, with output energies in the range 600--900 MJ, and with gains in the range 120--180. The peak powers are in the range of 500--750 TW. We present detailed calculations of the ablation, compression, ignition, and burn phases. By the application of a new stability analysis which includes ablation and density-gradient effects we show that these targets appear to implode in a stable manner. Thus the targets designed offer working examples suited for use in a future inertial-confinement fusion reactor

THE MACHINERY OF TIME MOVED TO IMAGINATION: RPG AND EMPATHY IN HISTORIC HISTORY OF EDUCATION

Directory of Open Access Journals (Sweden)

Juliano Pereira da Silva

2014-12-01

Full Text Available This Project arises from a desire to continue the monograph work done in 2010 in the course of Specialization in Teaching History and Social History at the State University of Londrina whose title was "The use RPG as a pedagogical tool in teaching history." The RPG proved to be a good teaching tool in that it aroused in students a love of history and his ability to put yourself in someone else's past, in other words, to establish an empathetic relationship with the past. It is the in-depth study of this relationship we wish to discuss. The historical empathy for Ashby & Lee serve as "a venture where students show the ability to reconstruct the goals, feelings, values and beliefs of others, accepting that they maybe different from your", thus becoming na important element in the teaching-learning process. The objective of this new phase was to verify the occurrence of historical empathic experience among students ofthe 6th year of the elementar school Professor Dr. Heber Soares Vargas of the content of history from a RPG game, watching their relationship in the seizure of historical concepts by students. This empathic experience occurred, helping many students to understand the concepts related to substantive matters studied from a historical perspective created in an RPG game. The project consisted of literature in order to define some concepts like game and the concept of historical empathy and its use in the teaching of history; creation of educational material, analysis of students' ideas and reflection on the experiment performed. Was conducted among the students of the sixth grade of elementary school in State College Professor. Dr. Heber Smith Vargas.

Questions and answers on the Belgian model of integral end-of-life care: experiment? Prototype? : "Eu-euthanasia": the close historical, and evidently synergistic, relationship between palliative care and euthanasia in Belgium: an interview with a doctor involved in the early development of both and two of his successors.

Science.gov (United States)

Bernheim, Jan L; Distelmans, Wim; Mullie, Arsène; Ashby, Michael A

2014-12-01

This article analyses domestic and foreign reactions to a 2008 report in the British Medical Journal on the complementary and, as argued, synergistic relationship between palliative care and euthanasia in Belgium. The earliest initiators of palliative care in Belgium in the late 1970s held the view that access to proper palliative care was a precondition for euthanasia to be acceptable and that euthanasia and palliative care could, and should, develop together. Advocates of euthanasia including author Jan Bernheim, independent from but together with British expatriates, were among the founders of what was probably the first palliative care service in Europe outside of the United Kingdom. In what has become known as the Belgian model of integral end-of-life care, euthanasia is an available option, also at the end of a palliative care pathway. This approach became the majority view among the wider Belgian public, palliative care workers, other health professionals, and legislators. The legal regulation of euthanasia in 2002 was preceded and followed by a considerable expansion of palliative care services. It is argued that this synergistic development was made possible by public confidence in the health care system and widespread progressive social attitudes that gave rise to a high level of community support for both palliative care and euthanasia. The Belgian model of so-called integral end-of-life care is continuing to evolve, with constant scrutiny of practice and improvements to procedures. It still exhibits several imperfections, for which some solutions are being developed. This article analyses this model by way of answers to a series of questions posed by Journal of Bioethical Inquiry consulting editor Michael Ashby to the Belgian authors.

Structure and mechanical behavior of a toucan beak

International Nuclear Information System (INIS)

Seki, Yasuaki; Schneider, Matthew S.; Meyers, Marc A.

2005-01-01

The toucan beak, which comprises one third of the length of the bird and yet only about 1/20th of its mass, has outstanding stiffness. The structure of a Toco toucan (Ramphastos toco) beak was found to be a sandwich composite with an exterior of keratin and a fibrous network of closed cells made of calcium-rich proteins. The keratin layer is comprised of superposed hexagonal scales (50 μm diameter and 1 μm thickness) glued together. Its tensile strength is about 50 MPa and Young's modulus is 1.4 GPa. Micro and nanoindentation hardness measurements corroborate these values. The keratin shell exhibits a strain-rate sensitivity with a transition from slippage of the scales due to release of the organic glue, at a low strain rate (5 x 10 -5 /s) to fracture of the scales at a higher strain rate (1.5 x 10 -3 /s). The closed-cell foam is comprised of fibers having a Young's modulus twice as high as the keratin shells due to their higher calcium content. The compressive response of the foam was modeled by the Gibson-Ashby constitutive equations for open and closed-cell foam. There is a synergistic effect between foam and shell evidenced by experiments and analysis establishing the separate responses of shell, foam, and foam + shell. The stability analysis developed by Karam and Gibson, assuming an idealized circular cross section, was applied to the beak. It shows that the foam stabilizes the deformation of the beak by providing an elastic foundation which increases its Brazier and buckling load under flexure loading

Continuous functionally graded porous titanium scaffolds manufactured by selective laser melting for bone implants.

Science.gov (United States)

Han, Changjun; Li, Yan; Wang, Qian; Wen, Shifeng; Wei, Qingsong; Yan, Chunze; Hao, Liang; Liu, Jie; Shi, Yusheng

2018-04-01

A significant requirement for a bone implant is to replicate the functional gradient across the bone to mimic the localization change in stiffness. In this work, continuous functionally graded porous scaffolds (FGPSs) based on the Schwartz diamond unit cell with a wide range of graded volume fraction were manufactured by selective laser melting (SLM). The micro-topology, strut dimension characterization and effect of graded volume fraction on the mechanical properties of SLM-processed FGPSs were systematically investigated. The micro-topology observations indicate that diamond FGPSs with a wide range of graded volume fraction from 7.97% to 19.99% were fabricated without any defects, showing a good geometric reproduction of the original designs. The dimensional characterization demonstrates the capability of SLM in manufacturing titanium diamond FGPSs with the strut size of 483-905µm. The elastic modulus and yield strength of the titanium diamond FGPSs can be tailored in the range of 0.28-0.59GPa and 3.79-17.75MPa respectively by adjusting the graded volume fraction, which are comparable to those of the cancellous bone. The mathematical relationship between the graded porosity and compression properties of a FGPS was revealed. Furthermore, two equations based on the Gibson and Ashby model have been established to predict the modulus and yield strength of SLM-processed diamond FGPSs. Compared to homogeneous diamond porous scaffolds, FGPSs provide a wide range of mutative pore size and porosity, which are potential to be tailored to optimize the pore space for bone tissue growth. The findings provide a basis of new methodologies to design and manufacture superior graded scaffolds for bone implant applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Selección y caracterización de rizobacterias promotoras de crecimiento vegetal (RPCV asociadas al cultivo de algodón (Gossypium hirsutum

Directory of Open Access Journals (Sweden)

Andrés Guzmán

2012-01-01

Full Text Available Título en ingles: Selection and characterization of plant growth promoting rhizobacteria (PGPR’s associated with cotton crop (Gossypium hirsutum Resumen: Como parte de las estrategias de una agricultura sostenible, se hace necesario disminuir el uso de fertilizantes nitrogenados de síntesis, mediante la utilización de los biofertilizantes. En particular, los géneros Azotobacter y Azospirillum son utilizados como agentes promotores de crecimiento vegetal debido a su capacidad para fijar nitrógeno atmosférico y producir hormonas de tipo indólico. Por tal razón, en este estudio se aislaron bacterias diazotróficas de los géneros Azotobacter y Azospirillum a partir de la rizósfera de cultivos de algodón en el Espinal (Tolima. Las poblaciones microbianas se caracterizaron fenotípicamente en los medios de cultivo semiespecíficos: Ashby y LG (Azotobacter sp. y NFb, LGI y Batata (Azospirillum sp.. La promoción de crecimiento vegetal se determinó mediante la actividad de la enzima nitrogenasa por medio de la técnica de reducción de acetileno y producción de índoles por el método colorimétrico de Salkowsky. Se obtuvieron 9 aislamientos tentativos de Azotobacter sp. y 4 de Azospirillum sp. Se presentaron diferencias significativas en la prueba de reducción de acetileno con las cepas presuntivas de Azotobacter sp.: NAT 9 (206.43 nmol C2H2 mL-1.h-1, NAT 4, (292.77 nmol C2H2 mL-1.h-1, y NAT 6 (460.60 nmol C2H2 mL-1.h-1 y en la producción de índoles de las cepas NAT 19 (19.87 μg.mL-1 y NAT 13 (20.08 μg.mL-1. Por su eficiencia in vitro en la promoción de crecimiento vegetal se seleccionaron las cepas NAT9, NAT4, NAT6, NAT19 y NAT13 para ser evaluadas como principio activo en futuros inoculantes para el algodón en esta zona del departamento del Tolima. Palabras clave: fijación biológica de nitrógeno; producción de índoles; promoción del crecimiento vegetal;  biofertilizantes. Abstract: As part of strategies for sustainable

Biological control of fruit flies (Diptera: Tephritidae) through parasitoid augmentative releases: Current status

International Nuclear Information System (INIS)

Montoya, Pablo; Liedo, Pablo

2000-01-01

Fruit flies are among the main pests affecting the world fruit industry (Aluja 1993). Bait sprays have traditionally been used successfully to control them; however, the side effects on the environment and health hazards commonly associated with pesticides, have resulted in strong public opposition to the use of bait sprays. This is particularly so when sprays are applied in urban areas or in coffee plantations where, although Medflies are present, they do not pose a danger to crops. Alternative methods that are effective and environmental friendly to suppress fruit fly populations are highly desirable. Biological control, the use of natural enemies to suppress pest populations, represents such an alternative. Some of the most successful cases of biological control are the control of Iceria purchasi Maskell (Homoptera: Margarodidae) by Rodolia cardinalis Mulsant (Coleoptera: Coccinellidae) in California (De Bach 1968, van den Bosch et al. 1982), and the control of Aleurocanthus woglumi Ashby (Homoptera: Aleyrodidae) mainly by Encarsia (=Prospaltella) opulenta Silv. (Hymenoptera: Aphelinidae) in Mexico (Jimenez 1961, 1971), both using the classical approach. However, this approach has been limited to certain conditions of environmental stability and biodiversity which are only found in a few ecosystems. Other factors, such as types of pests, the economic threshold and product quality requirements represent additional limitations. The best option in many cases could be augmentative biological control, which could overcome some of the deficiencies of the classical approach (Sivinski 1996). According to Knipling (1992) and Barclay (1987), augmentative biological control can be considered as a formal alternative for suppressing pest populations and even for use in eradication programmes, after integration with the sterile insect technique (SIT). In this approach, mass production of natural enemies is required and this production has to be cost effective

Strength of zirconium--titanium martensites and deformation behaviour

International Nuclear Information System (INIS)

Banerjee, S.; Vijayakar, S.J.; Krishnan, R.

1978-01-01

The deformation behavior of pure zirconium and of zirconium--titanium alloys containing 5, 10, 15 and 20 wt % titanium was studied in two heat treated conditions: furnace cooled and water quenched from the β phase field. By comparing the flow stresses of the furnace cooled α and the water quenched α' (martensite) structures it was possible to isolate the strengthening contributions of the martensitic structure (comprising the contributions due to the small size of the martensite units and to the distributions of defects like dislocations and internal twins) from those arising from the solid solution. The internally twinned plate martensite structure in the Zr--15% Ti and the Zr--20% Ti alloys was responsible for a significant increase in strength, while the strengthening due to the dislocated lath martensite structure in the more dilute alloys was only marginal. Stress relaxation experiments revealed that strengthening associated with the martensite structure was mainly due to an increase in the athermal component of the flow stress. The effectiveness of the lath boundaries and the (10 anti 11) twin boundaries in offering resistance to an approaching deformation front (either slip or twin) was examined. While the lath boundaries were found to be transparent with respect to the propagation of slip dislocations and deformation twins, a majority of plate as well as twin boundaries were effective barriers against their propagation. TEM observations showed an extensive accumulation of geometrically necessary dislocations in the plastically deformed twinned martensites. Enhanced work hardening was related to the geometric slip distances in these structures in accordance with Ashby's one parameter work hardening theory for plastically inhomogeneous materials. The effect of the martensite structure on different components of the flow stress (dependent on or independent of grain size and strain) was discussed

Carbon nanotube-copper exhibiting metal-like thermal conductivity and silicon-like thermal expansion for efficient cooling of electronics.

Science.gov (United States)

Subramaniam, Chandramouli; Yasuda, Yuzuri; Takeya, Satoshi; Ata, Seisuke; Nishizawa, Ayumi; Futaba, Don; Yamada, Takeo; Hata, Kenji

2014-03-07

Increasing functional complexity and dimensional compactness of electronic devices have led to progressively higher power dissipation, mainly in the form of heat. Overheating of semiconductor-based electronics has been the primary reason for their failure. Such failures originate at the interface of the heat sink (commonly Cu and Al) and the substrate (silicon) due to the large mismatch in thermal expansion coefficients (∼300%) of metals and silicon. Therefore, the effective cooling of such electronics demands a material with both high thermal conductivity and a similar coefficient of thermal expansion (CTE) to silicon. Addressing this demand, we have developed a carbon nanotube-copper (CNT-Cu) composite with high metallic thermal conductivity (395 W m(-1) K(-1)) and a low, silicon-like CTE (5.0 ppm K(-1)). The thermal conductivity was identical to that of Cu (400 W m(-1) K(-1)) and higher than those of most metals (Ti, Al, Au). Importantly, the CTE mismatch between CNT-Cu and silicon was only ∼10%, meaning an excellent compatibility. The seamless integration of CNTs and Cu was achieved through a unique two-stage electrodeposition approach to create an extensive and continuous interface between the Cu and CNTs. This allowed for thermal contributions from both Cu and CNTs, resulting in high thermal conductivity. Simultaneously, the high volume fraction of CNTs balanced the thermal expansion of Cu, accounting for the low CTE of the CNT-Cu composite. The experimental observations were in good quantitative concurrence with the theoretically described 'matrix-bubble' model. Further, we demonstrated identical in-situ thermal strain behaviour of the CNT-Cu composite to Si-based dielectrics, thereby generating the least interfacial thermal strain. This unique combination of properties places CNT-Cu as an isolated spot in an Ashby map of thermal conductivity and CTE. Finally, the CNT-Cu composite exhibited the greatest stability to temperature as indicated by its low

Numerical and experimental study of creep of grade 91 steel at high temperature

International Nuclear Information System (INIS)

Lim, R.

2011-01-01

Grade 91 steel is a suitable candidate for structural components of the secondary and the vapour of the generation IV nuclear reactors. Their in-service lifetime will be extended to 60 years. It is necessary to consider the mechanisms involved-term during long creep to propose more reliable predictions of creep lifetimes. Necking is the main failure mechanism for creep lifetimes up to 160 kh at 500 C and 94 kh at 600 C. Necking modelling including the material creep softening leads to two bound laws including experimental lifetimes of a large number of tempered martensitic steels loaded up to 200 kh at temperature 500-700 C. The observed creep intergranular cavities are shown to affect very weekly creep strain rate. The prediction of the cavity evolution will allow estimating creep lifetimes out of experimental data domain. Their nucleation and growth, supposed to be associated to vacancy diffusion, are modelled using two classical models. The first one considers instantaneous nucleation (Raj and Ashby) and the second one continuous nucleation obeying the Dyson law (Riedel). The second one leads to two bound laws, more stable with respect to the parameter values. It allows predicting final sizes of cavities in reasonable agreement with the measured ones. Nevertheless, nucleation rate should be estimated from measured cavity densities. Nucleation of cavities by diffusion is simulated using the Raj model. This model does not allow predicted final cavity densities in agreement with the measured ones, even by considering cavity nucleation at precipitates/Laves interfaces experimentally observed and the maximum local stress concentration of a factor 2 computed using finite element calculation in a 2D plane strain hypothesis based on either simulated or real microstructures containing triple points or precipitates/Laves phases. The use of the Dyson law allows us to propose predictions of long-term creep lifetimes. Lifetime predicted using the diffusion-induced growth

Distribución de bacterias potencialmente fijadoras de nitrógeno y su relación con parámetros fisicoquímicos en suelos con tres coberturas vegetales en el sur de la Amazonia colombiana

Directory of Open Access Journals (Sweden)

Andrea J Mantilla-Paredes

2009-12-01

Full Text Available Se evaluó la abundancia y distribución de bacterias microaerófilas y aerobias potencialmente fijadoras de nitrógeno aisladas a partir de suelos bajo coberturas de bosque, pastizal y chagra en dos paisajes, terraza y llanura inundable, en el sur de trapecio amazónico. Se relacionó el recuento en placa en el medio Ashby de estas bacterias aerobias con las características físicas y químicas del suelo. Se encontró mayor abundancia de bacterias aerobias y microaerofilas en suelos bajo cobertura de pastizal. Se observó influencia directa del paisaje sobre la abundancia de bacterias microaerófilas registrando mayores recuentos los suelos bajo terraza en las coberturas de bosque y pastizal. Los aislamientos aerobios obtenidos (51 se agruparon en 19 morfologías, de las cuales se obtuvo mayor número en suelos bajo bosque y en el paisaje de llanura inundable. A través del análisis multidimensional no métrico (NMDS y análisis de similaridades (ANOSIM (pDistribution of potentially nitrogen-fixing bacteria and its relationship with physicochemical parameters in soils with three vegetation types in the southern Colombian Amazon region. Potentially nitrogen-fixing microaerobic and aerobic bacteria were isolated from several Colombian Amazon soils (forest, pastures and chagras and two landscapes (floodable and non floodable areas. The abundance and distribution of bacteria were evaluated, as well as their relationship with soil physical and chemical characteristics. Landscape had a direct influence on the abundance of the microaerobic bacteria, with higher numbers in forest and pasture soils in non- floodable zones. The aerobic isolates (N=51 were grouped into 19 morphologies, with the highest numbers found in forest soil in floodable zones. A higher number of aerobic morphologies was shared among forest sites (Nonmetric Multidimensional Scaling and Analysis of Similarity p<0.05, and 40% of the distribution was explained by lime percentage and

Isothermal and aniso-thermal creep in the {alpha} phase domain, {beta} phase domain and {alpha}+{beta} two phase domain in a Zr-1%NbO alloy; Fluage isotherme et anisotherme dans les domaines monophases ({alpha} et {beta}) et biphases ({alpha} et {beta}) d'un alliage Zr-1%NbO

Energy Technology Data Exchange (ETDEWEB)

Kaddour, D

2004-12-15

The coupling between phase transformation and mechanical behaviour of a Zr-1%NbO alloy was studied using an original experimental device already used in a previous study devoted to the Zy-4 alloy. The Zr-1%NbO alloy undergoes a phase transformation {alpha} (hc) {r_reversible} (cc) typically between 750 and 1000 C. The transformation temperatures were measured in situ by using the resistivity and dilatometry techniques. The isothermal creep behaviour of fuel cladding tubes was studied, first after heating, in the {alpha} phase domain between 650 and 760 C, in the {beta} phase domain between 960 and 1100 C, as well as in the ({alpha} + {beta}) two phase domain between 800 and 900 C. The results are summarized in Ashby deformation mechanism maps. It is confirmed that the {beta} phase is much more sensitive to creep flow than the {alpha} phase. The effect of microstructure on the isothermal creep flow behaviour was then investigated by first applying a thermal cycle involving either a full or a partial transformation from {alpha} to {beta}. It was investigated both in the {alpha} phase domain, and after direct cooling into the ({alpha} + {beta}) phase domain. The behaviour in aniso-thermal conditions was finally studied at heating and cooling rates of 10 and 200 C/min. In both cases, we showed that there is no significant transformation plasticity in the stress range under investigation ({<=} 5 MPa). A finite element model using Voronoi polyhedra and eventually meshing a film of intergranular {beta} phase was used to describe the behaviour of material in the ({alpha} + {beta}) domain in various microstructural states. The model predictions are in good agreement with the experimental results for the microstructure obtained after cooling, but the model underestimates creep deformation in the as-received state. This difference is probably related to the fact that interface sliding is not taken into account in the model. (author)

Carbon Sequestration on Surface Mine Lands

Energy Technology Data Exchange (ETDEWEB)

Donald Graves; Christopher Barton; Richard Sweigard; Richard Warner; Carmen Agouridis

2006-03-31

Since the implementation of the federal Surface Mining Control and Reclamation Act of 1977 (SMCRA) in May of 1978, many opportunities have been lost for the reforestation of surface mines in the eastern United States. Research has shown that excessive compaction of spoil material in the backfilling and grading process is the biggest impediment to the establishment of productive forests as a post-mining land use (Ashby, 1998, Burger et al., 1994, Graves et al., 2000). Stability of mine sites was a prominent concern among regulators and mine operators in the years immediately following the implementation of SMCRA. These concerns resulted in the highly compacted, flatly graded, and consequently unproductive spoils of the early post-SMCRA era. However, there is nothing in the regulations that requires mine sites to be overly compacted as long as stability is achieved. It has been cultural barriers and not regulatory barriers that have contributed to the failure of reforestation efforts under the federal law over the past 27 years. Efforts to change the perception that the federal law and regulations impede effective reforestation techniques and interfere with bond release must be implemented. Demonstration of techniques that lead to the successful reforestation of surface mines is one such method that can be used to change perceptions and protect the forest ecosystems that were indigenous to these areas prior to mining. The University of Kentucky initiated a large-scale reforestation effort to address regulatory and cultural impediments to forest reclamation in 2003. During the three years of this project 383,000 trees were planted on over 556 acres in different physiographic areas of Kentucky (Table 1, Figure 1). Species used for the project were similar to those that existed on the sites before mining was initiated (Table 2). A monitoring program was undertaken to evaluate growth and survival of the planted species as a function of spoil characteristics and

Adaptive and Rational Anticipations in Risk Management Systems and Economy

Science.gov (United States)

Dubois, Daniel M.; Holmberg, Stig C.

2010-11-01

The global financial crisis of year 2009 is explained as a result of uncoordinated risk management decisions in business firms and economic organisations. The underlying reason for this can be found in the current financial system. As the financial market has lost much of its direct coupling to the concrete economy it provides misleading information to economic decision makers at all levels. Hence, the financial system has moved from a state of moderate and slow cyclical fluctuations into a state of fast and chaotic ones. Those misleading decisions can further be described, but not explained, by help of adaptive and rational expectations from macroeconomic theory. In this context, AE, the Adaptive Expectations are related to weak passive Exo-anticipation, and RE, the Rational expectations can be related to a strong, active and design oriented anticipation. The shortcomings of conventional cures, which builds on a reactive paradigm, have already been demonstrated in economic literature and are here further underlined by help of Ashby's "Law of Requisite Variety", Weaver's distinction between systems of "Disorganized Complexity" and those of "Organized Complexity", and Klir's "Reconstructability Analysis". Anticipatory decision-making is hence here proposed as a replacement to current expectation based and passive risk management. An anticipatory model of the business cycle is presented for supporting that proposition. The model, which is an extension of the Kaldor-Kalecki model, includes both retardation and anticipation. While cybernetics with the feedback process in control system deals with an explicit goal or purpose given to a system, the anticipatory system discussed here deals with a behaviour for which the future state of the system is built by the system itself, without explicit goal. A system with weak anticipation is based on a predictive model of the system, while a system with strong anticipation builds its own future by itself. Numerical simulations on

Work-hardening of dual-phase steel

Energy Technology Data Exchange (ETDEWEB)

Rieger, Florian

2016-07-01

Exhibiting good mechanical properties for cold-sheet forming, low-alloyed dual-phase (DP) steels are nowadays widely used for automotive applications. The composite-like microstructure of DP steels is composed of a low-carbon ductile ferrite-matrix and 10 - 60 vol.% hard martensitic inclusions. A nonlinear mean-field model and full-field finite-element simulations are applied to investigate three major topics: the influence of grain-size distribution, grain-level plasticity and derivation of an original material-model. The plastic behavior of polycrystals is assumed to be grain-size dependent in this work. The distribution of grain-sizes is taken to be lognormal. It is found that grain-size dispersion leads to a decrease of the material strength, in particular for small mean diameters around one micron. The numerical results from the mean-field model are confirmed notably well by means of a simple analytical expression. The micromechanical behavior of DP steels is investigated by full-field RVE simulations with a crystal-plasticity based ferrite-matrix and von Mises-type martensite inclusions. To examine the martensite influence, full-field simulation results of DP steels have been compared to an RVE in which martensite is substituted by ferrite. After quenching, a higher grain-boundary area covered by martensite facilitates an increased average dislocation-density. For uniaxial deformations above ∝10%, however, the grain-size dependent relation reverses. With more surrounding martensite, the local crystal-plasticity material-model exhibits hardening at a slower rate. A nonlinear mean-field model of Hashin-Shtrikman type is employed as framework for the original material-model for DP steels. The model incorporates the interaction of ferrite and martensite via incompatibility-induced long-range stresses in an averaged sense. The proposed model combines works of Ashby (1970) and Brown and Stobbs (1971a) to simulate the ferrite behavior. Based on the composite model

Multigrid Methods for EHL Problems

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Nurgat, Elyas; Berzins, Martin

1996-01-01

the application of such methods is the recent Effective Influence Method of Dowson and Wang. Multigrid methods have also been used with great success by Venner and Venner and Lubrecht with a good summary being given by Venner. As both these finite difference discretization based approaches appear to provide an efficient way of solving EHL problems, it is important to understand their relative merits. This paper is a first attempt at providing such an understanding in the context of EHL point contact problem, (contact of two spheres), in which the contact zone is a point and an ellipse or circle for unloaded and loaded dry contacts respectively. Since the film thickness and the contact width are generally small compared to the local radius of curvature of the two surfaces, the reduced geometry of the surfaces in the contact area can be accurately approximated to the contact between a paraboloid and a flat surface. The layout of the remainder of this paper is as follows. In section 2 we introduce the form of the equations to be solved. The Effective Influence Newton Method is described in Section 3 while Section 4 describes the Multigrid method to be used. Sections 5 and 6 describe the test problems to be used in the comparison between the two methods and compare the performance of the two methods. Section 7 concludes the paper with an argument of the two methods and suggests some future research directions.

METASYSTEMIC TECHNOLOGY OF INSTRUCTION, STUDENT RESEARCH AND INNOVATION

Directory of Open Access Journals (Sweden)

Dumitru BALANEL

2017-07-01

Full Text Available Metasystemic technology of training, student research and innovation (D.Balanel – MTTRI is the development of educational technology J.F. Herbart by cybernetic, metasystem approach, feedbacks, diffusion of knowledges, com­petences in real time, intuition and with application in high education. “Metasystemic technology training, student research and innovation (D.Balanel” is introducing in science by author. Technology is based on metasystem, including pedagogy, psychology, management, cybernetics, mathematics.The paper discusses training, student-centered and competence-centered, the equation of training, equation of training with notes early, appropriate to Bologna Process, ways to educate interest and research capabilities, innovation of students; studying the factors that determine the student make transition to self-knowledge accumulation, learn with satisfaction the research and innovation, transition from apperception to intuition. The author relies on metasystemic training technology, skills to work in real time, using student thesaurus from computer science, informatics and history of cybernetics; learn experience and performance of the most eminent personalities in the development of computer science and cybernetics, Norbert Wiener and Alain Turing, William Ross Ashby and John von Neumann, others personalities, holding the Turing and Neumann and other Awards in cybernetics and informatics . Scientific education of students includes identifying scientific issues, enrollment of students in research. Identifying the scientific problems inherited as millennial problems in mathematics and computer science, current issues and future of science; incentives in applying forces young people to solve them. The enrollment of students in scientific work is done by conducting research with students on issues of university research in the scientific teams, scientific laboratories and simulators, training. The result of "IRI–triangle activity

Refractory metal superalloys: Design of yttrium aluminum garnet passivating niobium alloys

Science.gov (United States)

Bryan, David

A systems-based approach, integrating computational modeling with experimental techniques to approach engineering problems in a time and cost efficient manner, was employed to design a Nb-based refractory superalloy for use at 1300°C. Ashby-type selection criteria for both thermodynamic and kinetic parameters were employed to identify a suitable protective oxide for Nb alloys. Yttrium aluminum garnet (YAG) was selected as the most promising candidate for its excellent combination of desirable properties. The alloy microstructural concept was based upon the gamma - gamma' nickel-based superalloys in which the multifunctional gamma' phase serves as both a creep strengthening dispersion and a source of reactive elements for oxide passivation. Candidate ternary Pd-Y-Al and Pt-Y-Al compounds were fabricated and characterized by XRD and DTA. Of the intermetallics studied, only PtYAl had a high enough melting point (1580°C) for use in an alloy operating at 1300°C. The alloy matrix design was based upon Wahl's extension of Wagner's criterion for protective oxidation, requiring a reduction of the product N ODO/DAl by 5 orders of magnitude relative to binary Nb-Al. A thermodynamic and kinetic analysis identified elements with large oxygen affinities as the most beneficial for reducing the magnitude of the quantity NOD O. Construction of a combined thermodynamic and mobility database identified increased Al solubility as the best approach for increasing D Al. Utilizing the thermodynamic and mobility databases, obtained from a combination of model alloys, oxidation experiments, and first principles calculations, theoretical designs predicted the large changes in solubility and transport parameters were achievable. Several prototype alloys were then fabricated and evaluated via oxidation tests at both 1300°C and 1100°C. YAG formation was demonstrated as part of multicomponent oxide scales in the alloys that exhibited the greatest reduction in oxidation rates. The oxidation

The Time Is Now: Bioethics and LGBT Issues.

Science.gov (United States)

Powell, Tia; Foglia, Mary Beth

2014-09-01

disparities. Stephan Davis and Nancy Berlinger assess the challenges of access to care and health policy for transgender persons. Edward J. Callahan et al. tackle the ways in which diverse aspects of medicine should change to better incorporate the needs of LGBT patients, including through use of the electronic medical record, education of health professionals, and recruitment efforts for LGBT health professionals. Virginia Ashby Sharpe and Uchenna S. Uchendu describe multifaceted efforts within Veterans Administration facilities to create change for LGBT veterans across the largest integrated health care network in the United States. Lance Wahlert and Autumn Fiester find a mixed record in the use of case studies in teaching about LGBT issues. © 2014 by The Hastings Center.

High-Temperature Cast Aluminum for Efficient Engines

Science.gov (United States)

Bobel, Andrew C.

Accurate thermodynamic databases are the foundation of predictive microstructure and property models. An initial assessment of the commercially available Thermo-Calc TCAL2 database and the proprietary aluminum database of QuesTek demonstrated a large degree of deviation with respect to equilibrium precipitate phase prediction in the compositional region of interest when compared to 3-D atom probe tomography (3DAPT) and transmission electron microscopy (TEM) experimental results. New compositional measurements of the Q-phase (Al-Cu-Mg-Si phase) led to a remodeling of the Q-phase thermodynamic description in the CALPHAD databases which has produced significant improvements in the phase prediction capabilities of the thermodynamic model. Due to the unique morphologies of strengthening precipitate phases commonly utilized in high-strength cast aluminum alloys, the development of new microstructural evolution models to describe both rod and plate particle growth was critical for accurate mechanistic strength models which rely heavily on precipitate size and shape. Particle size measurements through both 3DAPT and TEM experiments were used in conjunction with literature results of many alloy compositions to develop a physical growth model for the independent prediction of rod radii and rod length evolution. In addition a machine learning (ML) model was developed for the independent prediction of plate thickness and plate diameter evolution as a function of alloy composition, aging temperature, and aging time. The developed models are then compared with physical growth laws developed for spheres and modified for ellipsoidal morphology effects. Analysis of the effect of particle morphology on strength enhancement has been undertaken by modification of the Orowan-Ashby equation for 〈110〉 alpha-Al oriented finite rods in addition to an appropriate version for similarly oriented plates. A mechanistic strengthening model was developed for cast aluminum alloys containing

The behavior of mineral inclusions during host decomposition. A SEM-STEM study of rutile inclusions at a natural propagating corundum-spinel interface.

Science.gov (United States)

Baldwin, Lisa; Li, Chen; Habler, Gerlinde; Abart, Rainer

2017-04-01

When two neighbor phases are not in chemical equilibrium, they may react and produce a reaction rim at their interface, separating the mutually incompatible phases. At constant P-T-X conditions, such a reaction will continue until one of the reactants is completely consumed. Reaction rim growth involves transfer of chemical components across the growing rim by long-range diffusion and localized interface reactions on either side of the growing rim. Consequently, the thickness of the reaction rim will be a function of time. Yet, in order to quantify and interpret such corona structures and to define a reaction rate law, the kinetics and mechanism of rim formation must be well constrained. In particular, the coupling between long-range diffusion, and interface reaction must be known. In this contribution we focus on potential complexities associated with interface reactions. Many natural minerals contain inclusions of other phases, which in turn may influence the reaction interface propagation kinetics during host phase decomposition (Ashby et al. 1969), as a propagating reaction interface dissipates more free energy when bypassing a mineral inclusion, resulting in a locally decelerated reaction rate. Here, we report results of a SEM-STEM study of the interface between natural rutile-bearing corundum and a polycrystalline ferromagnesio-aluminate spinel that grew topotactically with respect to the corundum precursor as a consequence of its reaction with FeO and MgO from basaltic melt. Electron Backscatter Diffraction (EBSD) crystal orientation imaging revealed that the spinel rim is polycrystalline and exhibits (111) twinning that is parallel to the corundum (0001) plane. The rutile inclusions in corundum are elongated perpendicular to the corundum [0001] axis and are randomly oriented in the (0001) plane. Furthermore, they follow an oscillatory grain size distribution zonation with grain sizes being either a few tens of nanometers, or about 500 to 800 nanometers in

Multilevel stake holder consensus building in radioactive waste management

International Nuclear Information System (INIS)

Dreimanis, Andrejs

2008-01-01

Full text: The increased demand of our society to its quality of life, global security and environmental safety as well as to observing a basic ethical principle of equity have advanced our attitude towards the recent proposals to develop shared multinational projects in the use of nuclear energy technologies, in particular, to: a) Siting of shared deep repositories for high-level radioactive waste (RW) and spent nuclear fuel safe disposal. In turn, arrangement of multinational facilities requires to gain more complex consensus between all involved parties. Method: We propose an interdisciplinary synergetic approach to multilevel consensus building for siting and construction of shared multinational repositories for RW deep disposal, based on self-organization (SO) of various stake holders, chaos and fuzziness concepts as well as Ashby principle of requisite variety. In the siting of a multi-national repository there appears an essential novel component of stake holder consensus building, namely: to reach consent - political, social, economic, ecological - among international partners, in addition to solving the whole set of intra-national consensus building items. An entire partnering country is considered as a national stake holder, represented by the national government, being faced to simultaneous seeking an upward (international) and a downward (intra-national) consensus in a psychologically stressed environment, having possibly diverse political, economic and social interests. Main Results: Following inferences about building of multilevel consensus are developed: 1) The basis of synergetic approach to stake holder interaction - informational SO, by forming a knowledge-creating stake holder community via cooperation and competition among individuals, public bodies/groups, companies, institutions; 2) Building of international stake holder consensus could be promoted by activating and diversifying multilateral interactions between intra- and international stake

Prediction during sentence comprehension in aphasia

Directory of Open Access Journals (Sweden)

Michael Walsh Dickey

2014-04-01

either highly predictable or unpredictable (Before warming the milk/To prevent a mess, the babysitter took out/checked the …. The PWA varied widely in their verbal fluency, as measured by their verbal-fluency scores on the Comprehensive Aphasia Test (Swinburn, et al., 2004; verbal fluency T-score range: 43-71. Reading times at the critical word (bottle/diaper; see Figure 1 showed a large effect of predictability, with both high- and low-frequency words being read faster in constraining sentence contexts (F[1,7]=13.66, p.1. This pattern is different from findings for older and younger unimpaired adults, who show similar-sized effects for predictability and frequency (Rayner, et al., 2004; Ashby, et al., 2005; Rayner, et al., 2006. However, it is consistent with previous results for aphasia, where effects of word frequency are often missing (e.g., DeDe, 2012. There was no relationship between verbal fluency and the size of the predictability effect (r=.06, p>.4. These findings indicate that PWA can show very robust prediction in comprehension, at least for constraining sentence contexts (Federmeier, 2007. However, prediction appears to be dissociated from variation in verbal fluency/language-production impairment. This finding casts doubt on theories which ground prediction in comprehension in the language production system (Federmeier, 2007; Pickering & Garrod, 2013; Dell & Chang, 2014.

Creep Deformation and Fracture Processes in OF and OFP Copper

International Nuclear Information System (INIS)

Bowyer, William H.

2004-10-01

The literature on creep processes in many materials, including copper, has been thoroughly reviewed and complemented by Ashby and co-workers. They have provided physical models which describe the deformation and fracture processes with good qualitative and quantitative agreement with experimental data for many cases. A description of the deformation and fracture models is provided and the relevant equations are included in the appendices. Published data from the canister development programme has been compared with the predictions from the models. The purpose was to improve our understanding of (1) a reported benefit to creep performance which arises from additions of 50 ppm phosphorus to oxygen free (OF) copper, and (2) an observed transition from brittle to ductile failure in OF copper. The models adequately describe the general variations in the observed creep behaviour of the experimental materials. Steady state creep rates for OF copper are observed to be up to one order of magnitude higher than the model predicts for pure copper across a wide range of temperatures and stresses in the power law and power law breakdown regimes. For OF copper with 50ppm of phosphorus added (OFP copper), observed steady state creep rates in the power law breakdown regime are up to one order of magnitude lower than the model predicts for pure copper. Creep lives in the experimental OFP material are also higher than creep lives for OF material under similar conditions. The lower creep deformation rates and the longer creep lives of OFP material are attributed the known effects of phosphorus on recovery in copper. The model predicts that the same mechanism will improve creep lives under repository conditions. It is suggested that the factor of improvement under repository conditions will be less than the factor which is observed in the power law breakdown regime. Predicted creep lives, based on measured steady state creep rates and stress exponents ('n' values) are in good agreement

EDITORIAL: Special issue on applied neurodynamics: from neural dynamics to neural engineering Special issue on applied neurodynamics: from neural dynamics to neural engineering

Science.gov (United States)

Chiel, Hillel J.; Thomas, Peter J.

2011-12-01

Tracing technologies back in time to their scientific and mathematical origins reveals surprising connections between the pure pursuit of knowledge and the opportunities afforded by that pursuit for new and unexpected applications. For example, Einstein's desire to eliminate the disparity between electricity and magnetism in Maxwell's equations impelled him to develop the special theory of relativity (Einstein 1922)Einstein 1922 p 41 'The advance in method arises from the fact that the electric and magnetic fields lose their separate existences through the relativity of motion. A field which appears to be purely an electric field, judged from one system, has also magnetic field components when judged from another inertial system.'. His conviction that there should be no privileged inertial frame of reference Einstein 1922 p 58 'The possibility of explaining the numerical equality of inertia and gravitation by the unity of their nature gives to the general theory of relativity, according to my conviction, such a superiority over the conceptions of classical mechanics, that all the difficulties encountered must be considered as small in comparison with this progress.' further impelled him to utilize the non-Euclidean geometry originally developed by Riemann and others as a purely hypothetical alternative to classical geometry as the foundation for the general theory of relativity. Nowadays, anyone who depends on a global positioning system—which now includes many people who own smart phones—uses a system that would not work effectively without incorporating corrections from both special and general relativity (Ashby 2003). As another example, G H Hardy famously proclaimed his conviction that his work on number theory, which he pursued for the sheer love of exploring the beauty of mathematical structures, was unlikely to find any practical applications (Hardy 1940)Hardy 1940 pp 135-6 'The general conclusion, surely, stands out plainly enough. If useful knowledge