Dynamic Diversity: Toward a Contextual Understanding of Critical Mass

Science.gov (United States)

Garces, Liliana M.; Jayakumar, Uma M.

2014-01-01

Through an analysis of relevant social science evidence, this article provides a deeper understanding of critical mass, a concept that has become central in litigation efforts related to affirmative action admissions policies that seek to further the educational benefits of diversity. We demonstrate that the concept of critical mass requires an…

Critical Mass in the Boardroom of Croatian Banks

OpenAIRE

Kramaric Tomislava Pavic; Miletic Marko

2017-01-01

This paper investigates the influence of gender diversity in the boardroom of Croatian banks on their performance. Specifically, we deal with both management and supervisory boards. Moreover, based on critical mass theory, the authors try to find out what constitutes critical mass. Using a static panel analysis on a sample of all commercial banks that operated in the period 2002-2014, three models were estimated with return on assets (ROA), return on equity (ROE) and net interest margin (NIM)...

Fission, critical mass and safety-a historical review

International Nuclear Information System (INIS)

Meggitt, Geoff

2006-01-01

Since the discovery of fission, the notion of a chain reaction in a critical mass releasing massive amounts of energy has haunted physicists. The possibility of a bomb or a reactor prompted much of the early work on determining a critical mass, but the need to avoid an accidental critical excursion during processing or transport of fissile material drove much that took place subsequently. Because of the variety of possible situations that might arise, it took some time to develop adequate theoretical tools for criticality safety and the early assessments were based on direct experiment. Some extension of these experiments to closely similar situations proved possible, but it was not until the 1960s that theoretical methods (and computers to run them) developed enough for them to become reliable assessment tools. Validating such theoretical methods remained a concern, but by the end of the century they formed the backbone of criticality safety assessment. This paper traces the evolution of these methods, principally in the UK and USA, and summarises some related work concerned with the nature of criticality accidents and their radiological consequences. It also indicates how the results have been communicated and used in ensuring nuclear safety. (review)

Critical masses for the even-neutron-numbered transuranium actinides

International Nuclear Information System (INIS)

Westfall, R.M.

1981-01-01

As part of a standards effort of the American Nuclear Society to establish subcritical mass limits for the transuranium actinides, critical masses were calculated for seven actinides, critical masses were calculated for seven actinide elements in bare, water-reflected, and steel-reflected metal systems. For the nuclides /sup 242/Pu and /sup 241/Am, values obtained with ENDF/B-V cross-section data were in much better agreement with values inferred from experimental measurement than were initial values calculated with ENDF/B-IV data. A brief description of the analytical methods employed is followed by a presentation of the results. 10 refs

Neonatal and pediatric regionalized systems in pediatric emergency mass critical care.

Science.gov (United States)

Barfield, Wanda D; Krug, Steven E; Kanter, Robert K; Gausche-Hill, Marianne; Brantley, Mary D; Chung, Sarita; Kissoon, Niranjan

2011-11-01

Improved health outcomes are associated with neonatal and pediatric critical care in well-organized, cohesive, regionalized systems that are prepared to support and rehabilitate critically ill victims of a mass casualty event. However, present systems lack adequate surge capacity for neonatal and pediatric mass critical care. In this document, we outline the present reality and suggest alternative approaches. In May 2008, the Task Force for Mass Critical Care published guidance on provision of mass critical care to adults. Acknowledging that the critical care needs of children during disasters were unaddressed by this effort, a 17-member Steering Committee, assembled by the Oak Ridge Institute for Science and Education with guidance from members of the American Academy of Pediatrics, convened in April 2009 to determine priority topic areas for pediatric emergency mass critical care recommendations.Steering Committee members established subcommittees by topic area and performed literature reviews of MEDLINE and Ovid databases. The Steering Committee produced draft outlines through consensus-based study of the literature and convened October 6-7, 2009, in New York, NY, to review and revise each outline. Eight draft documents were subsequently developed from the revised outlines as well as through searches of MEDLINE updated through March 2010.The Pediatric Emergency Mass Critical Care Task Force, composed of 36 experts from diverse public health, medical, and disaster response fields, convened in Atlanta, GA, on March 29-30, 2010. Feedback on each manuscript was compiled and the Steering Committee revised each document to reflect expert input in addition to the most current medical literature. States and regions (facilitated by federal partners) should review current emergency operations and devise appropriate plans to address the population-based needs of infants and children in large-scale disasters. Action at the state, regional, and federal levels should address

Reaching Hard-to-Reach Individuals: Nonselective Versus Targeted Outbreak Response Vaccination for Measles

Science.gov (United States)

Minetti, Andrea; Hurtado, Northan; Grais, Rebecca F.; Ferrari, Matthew

2014-01-01

Current mass vaccination campaigns in measles outbreak response are nonselective with respect to the immune status of individuals. However, the heterogeneity in immunity, due to previous vaccination coverage or infection, may lead to potential bias of such campaigns toward those with previous high access to vaccination and may result in a lower-than-expected effective impact. During the 2010 measles outbreak in Malawi, only 3 of the 8 districts where vaccination occurred achieved a measureable effective campaign impact (i.e., a reduction in measles cases in the targeted age groups greater than that observed in nonvaccinated districts). Simulation models suggest that selective campaigns targeting hard-to-reach individuals are of greater benefit, particularly in highly vaccinated populations, even for low target coverage and with late implementation. However, the choice between targeted and nonselective campaigns should be context specific, achieving a reasonable balance of feasibility, cost, and expected impact. In addition, it is critical to develop operational strategies to identify and target hard-to-reach individuals. PMID:24131555

U-233 fuelled low critical mass solution reactor experiment PURNIMA II

International Nuclear Information System (INIS)

Srinivasan, M.; Chandramoleshwar, K.; Pasupathy, C.S.; Rasheed, K.K.; Subba Rao, K.

1987-01-01

A homogeneous U-233 uranyl nitrate solution fuelled BeO reflected, low critical mass reactor has been built at the Bhabha Atomic Research Centre, India. Christened PURNIMA II, the reactor was used for the study of the variation of critical mass as a function of fuel solution concentration to determine the minimum critical mass achievable for this geometry. Other experiments performed include the determination of temperature coefficient of reactivity, study of time behaviour of photoneutrons produced due to interaction between decaying U-233 fission product gammas and the beryllium reflector and reactor noise measurements. Besides being the only operational U-233 fuelled reactor at present, PURNIMA II also has the distinction of having attained the lowest critical mass of 397 g of fissile fuel for any operating reactor at the current time. The paper briefly describes the facility and gives an account of the experiments performed and results achieved. (author)

Critical mass calculations for 241Am, 242mAm and 243Am

International Nuclear Information System (INIS)

Dias, Hemanth; Tancock, Nigel; Clayton, Angela

2003-01-01

Criticality mass calculations are reported for 241 Am, 242m Am and 243 Am using the MONK and MCNP computer codes with the UKNDL, JEF-2.2, ENDF/B-VI and JENDL-3.2 nuclear data libraries. Results are reported for spheres of americium metal and dioxide in bare, water reflected and steel reflected systems. Comparison of results led to the identification of a serious inconsistency in the 241 Am ENDF/B-VI DICE library used by MONK - this demonstrates the importance of using different codes to verify critical mass calculations. The 241 Am critical mass estimates obtained using UKNDL and ENDF/B-VI show good agreement with experimentally inferred data, whilst both JEF-2.2 and JENDL-3.2 produce higher estimates of critical mass. The computed critical mass estimates for 242m Am obtained using ENDF/B-VI are lower than the results produced using the other nuclear data libraries - the ENDF/B-VI fission cross-section for 242m Am is significantly higher than the other evaluations in the fast region and is not supported by recent experimental data. There is wide variation in the computed 243 Am critical mass estimates suggesting that there is still considerable uncertainty in the 243 Am nuclear data. (author)

Plutonium Critical Mass Curve Comparison to Mass at Upper Subcritical Limit (USL) Using Whisper

International Nuclear Information System (INIS)

Alwin, Jennifer Louise; Zhang, Ning

2016-01-01

Whisper is computational software designed to assist the nuclear criticality safety analyst with validation studies with the MCNP ® Monte Carlo radiation transport package. Standard approaches to validation rely on the selection of benchmarks based upon expert judgment. Whisper uses sensitivity/uncertainty (S/U) methods to select relevant benchmarks to a particular application or set of applications being analyzed. Using these benchmarks, Whisper computes a calculational margin. Whisper attempts to quantify the margin of subcriticality (MOS) from errors in software and uncertainties in nuclear data. The combination of the Whisper-derived calculational margin and MOS comprise the baseline upper subcritical limit (USL), to which an additional margin may be applied by the nuclear criticality safety analyst as appropriate to ensure subcriticality. A series of critical mass curves for plutonium, similar to those found in Figure 31 of LA-10860-MS, have been generated using MCNP6.1.1 and the iterative parameter study software, WORM S olver. The baseline USL for each of the data points of the curves was then computed using Whisper 1.1. The USL was then used to determine the equivalent mass for plutonium metal-water system. ANSI/ANS-8.1 states that it is acceptable to use handbook data, such as the data directly from the LA-10860-MS, as it is already considered validated (Section 4.3 4) ''Use of subcritical limit data provided in ANSI/ANS standards or accepted reference publications does not require further validation.''). This paper attempts to take a novel approach to visualize traditional critical mass curves and allows comparison with the amount of mass for which the k eff is equal to the USL (calculational margin + margin of subcriticality). However, the intent is to plot the critical mass data along with USL, not to suggest that already accepted handbook data should have new and more rigorous requirements for validation.

Rockwell International's Critical Mass Laboratory Program at the Rocky Flats Plant

International Nuclear Information System (INIS)

McCarthy, J.D.

1984-01-01

The primary mission of the laboratory is to provide data in support of plant operations. To fulfill this task, the facility has unique capabilities for perfoming general purpose critical mass experiment. The critical mass laboratory performed over 1000 critical measurements, primarily with plutonium metal and uranium metal, oxide and solution; it worked also on the NRC program (high-enriched uranium measurements). Presently the laboratory staff prepares for a series of critical measurements on a poisoned tube tank; the laboratory intends to continue to pursue basic plant support programs in the future

Perspectives for tests of neutrino mass generation at the GeV scale. Experimental reach versus theoretical predictions

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, Rasmus W.; Winter, Walter

2016-11-15

We discuss the parameter space reach of future experiments searching for heavy neutral leptons (HNLs) at the GeV scale in terms of neutrino mass models with three HNL generations. We focus on two classes of models: Generic assumptions (such as random mass matrices or the Casas-Ibarra parameterization) and flavor symmetry-generated models. We demonstrate that the generic approaches lead to comparable parameter space predictions, which tend to be at least partially within the reach of future experiments. On the other hand, specific flavor symmetry models yield more refined predictions, some of these can be more clearly excluded. We also highlight the importance to measure the flavor-dependent couplings of the HNLs as a model discriminator, and we clarify the impact of assumptions frequently used in the literature to show the parameter space reach for the active-sterile mixings.

Perspectives for tests of neutrino mass generation at the GeV scale. Experimental reach versus theoretical predictions

International Nuclear Information System (INIS)

Rasmussen, Rasmus W.; Winter, Walter

2016-11-01

We discuss the parameter space reach of future experiments searching for heavy neutral leptons (HNLs) at the GeV scale in terms of neutrino mass models with three HNL generations. We focus on two classes of models: Generic assumptions (such as random mass matrices or the Casas-Ibarra parameterization) and flavor symmetry-generated models. We demonstrate that the generic approaches lead to comparable parameter space predictions, which tend to be at least partially within the reach of future experiments. On the other hand, specific flavor symmetry models yield more refined predictions, some of these can be more clearly excluded. We also highlight the importance to measure the flavor-dependent couplings of the HNLs as a model discriminator, and we clarify the impact of assumptions frequently used in the literature to show the parameter space reach for the active-sterile mixings.

Critical mass of public goods and its coevolution with cooperation

Science.gov (United States)

Shi, Dong-Mei; Wang, Bing-Hong

2017-07-01

In this study, the enhancing parameter represented the value of the public goods to the public in public goods game, and was rescaled to a Fermi-Dirac distribution function of critical mass. Public goods were divided into two categories, consumable and reusable public goods, and their coevolution with cooperative behavior was studied. We observed that for both types of public goods, cooperation was promoted as the enhancing parameter increased when the value of critical mass was not very large. An optimal value of critical mass which led to the best cooperation was identified. We also found that cooperations emerged earlier for reusable public goods, and defections became extinct earlier for the consumable public goods. Moreover, we observed that a moderate depreciation rate for public goods resulted in an optimal cooperation, and this range became wider as the enhancing parameter increased. The noise influence on cooperation was studied, and it was shown that cooperation density varied non-monotonically as noise amplitude increased for reusable public goods, whereas decreased monotonically for consumable public goods. Furthermore, existence of the optimal critical mass was also identified in other three regular networks. Finally, simulation results were utilized to analyze the provision of public goods in detail.

A semilinear parabolic–elliptic chemotaxis system with critical mass in any space dimension

International Nuclear Information System (INIS)

Montaru, Alexandre

2013-01-01

We study radial solutions in a ball of R N of a semilinear, parabolic–elliptic Patlak–Keller–Segel system with a nonlinear sensitivity involving a critical power. For N = 2, the latter reduces to the classical ‘linear’ model, well known for its critical mass 8π. We show that a critical mass phenomenon also occurs for N ⩾ 3, but with a strongly different qualitative behaviour. More precisely, if the total mass of cells is smaller or equal to the critical mass M-bar , then the cell density converges to a regular steady state that is supported strictly inside the ball as time goes to infinity. In the case of the critical mass, this result is nontrivial since there exists a continuum of stationary solutions and is moreover in sharp contrast with the case N = 2 where infinite-time blow-up occurs. If the total mass of cells is larger than M-bar , then all radial solutions blow up in finite time. This actually follows from the existence (unlike for N = 2) of a family of self-similar, blowing-up solutions that are supported strictly inside the ball. (paper)

Actinides critical masses and the Paxton Woodcock rule

International Nuclear Information System (INIS)

Anno, Jacques; Duhamel, Isabelle; Lavarenne, Caroline; Duluc, Matthieu

2003-01-01

This paper presents recent actinides (reflected or not, moderated or not) critical masses calculations performed by the French standard route (APOLLO2 Sn 8 P3, 20 energy groups cross-section collapsed from 172 energy groups CEA 93 library). Comparisons are also presented against more accurate routes of the French criticality package CRISTAL, showing the fair conservatism of the standard values. Checks of the Paxton Woodcock rule for transportation exemption limit were also made. (author)

Actinides critical masses and the Paxton Woodcock rule

Energy Technology Data Exchange (ETDEWEB)

Anno, Jacques; Duhamel, Isabelle; Lavarenne, Caroline [Institut de Radioprotection et de Surete Nucleaire, Fontenay aux Roses (France); Duluc, Matthieu [Institut National des Sciences et Techniques Nucleaires (INSTN) (France)

2003-10-01

This paper presents recent actinides (reflected or not, moderated or not) critical masses calculations performed by the French standard route (APOLLO2 Sn 8 P3, 20 energy groups cross-section collapsed from 172 energy groups CEA 93 library). Comparisons are also presented against more accurate routes of the French criticality package CRISTAL, showing the fair conservatism of the standard values. Checks of the Paxton Woodcock rule for transportation exemption limit were also made. (author)

The effect of virtual mass on the prediction of critical flow

International Nuclear Information System (INIS)

Cheng, L.; Lahey, R.T.; Drew, D.A.

1983-01-01

By observing the results in Fig. 4 and Fig. 5 we can see that virtual mass effects are important in predicting critical flow. However, as seen in Fig. 7a, in which all three flows are predicted to be critical (Δ=0), it is difficult to distinguish one set of conditions from the other by just considering the pressure profile. Clearly more detailed data, such as the throat void fraction, is needed for discrimination between these calculations. Moreover, since the calculated critical flows have been found to be sensitive to initial mass flux, and void fraction, careful measurements of those parameters are needed before accurate virtual mass parameters can be determined from these data. It can be concluded that the existing Moby Dick data is inadequate to allow one to deduce accurate values of the virtual mass parameters C/sub VM/ and λ. Nevertheless, more careful experiments of this type are uniquely suited for the determination of these important parameters. It appears that the use of a nine equation model, such as that discussed herein, coupled with more detailed accurate critical flow data is an effective means of determining the parameters in interfacial momentum transfer models, such as virtual mass effects, which are only important during strong spatial accelerations. Indeed, there are few other methods available which can be used for such determinations

Predictions of the marviken subcooled critical mass flux using the critical flow scaling parameters

Energy Technology Data Exchange (ETDEWEB)

Park, Choon Kyung; Chun, Se Young; Cho, Seok; Yang, Sun Ku; Chung, Moon Ki [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1998-12-31

A total of 386 critical flow data points from 19 runs of 27 runs in the Marviken Test were selected and compared with the predictions by the correlations based on the critical flow scaling parameters. The results show that the critical mass flux in the very large diameter pipe can be also characterized by two scaling parameters such as discharge coefficient and dimensionless subcooling (C{sub d,ref} and {Delta}{Tau}{sup *} {sub sub}). The agreement between the measured data and the predictions are excellent. 8 refs., 8 figs. 1 tab. (Author)

Predictions of the marviken subcooled critical mass flux using the critical flow scaling parameters

Energy Technology Data Exchange (ETDEWEB)

Park, Choon Kyung; Chun, Se Young; Cho, Seok; Yang, Sun Ku; Chung, Moon Ki [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-12-31

A total of 386 critical flow data points from 19 runs of 27 runs in the Marviken Test were selected and compared with the predictions by the correlations based on the critical flow scaling parameters. The results show that the critical mass flux in the very large diameter pipe can be also characterized by two scaling parameters such as discharge coefficient and dimensionless subcooling (C{sub d,ref} and {Delta}{Tau}{sup *} {sub sub}). The agreement between the measured data and the predictions are excellent. 8 refs., 8 figs. 1 tab. (Author)

Measurement of critical mass for an assembly of bare uranium shells

International Nuclear Information System (INIS)

Myers, W.L.; Goulding, C.A.; Hollas, C.L.

1997-01-01

As part of the research into nuclear measurement techniques, a series of measurements was performed that have applications to criticality safety and nuclear material handling. The critical mass of a set of bare, enriched-uranium metal hemispherical shells, known as the Rocky Flats shells, was measured for an assembly having an inside radius of 2.347 cm. The critical mass value was extrapolated from a series of subcritical measurements using three different kinds of sources (AmBe, AmF, and 252 Cf) placed at the center of the shells. Two kinds of neutron detection configurations (a 1% efficiency and a 25% efficiency configuration) were used to make the measurements

Critical mass experiment using U-235 foils and lucite plates

International Nuclear Information System (INIS)

Sanchez, R.; Butterfield, K.; Kimpland, R.; Jaegers, P.

1998-01-01

The main objective of this experiment was to show how the multiplication of the system increases as moderated material is placed between highly enriched uranium foils. In addition, this experiment served to demonstrate the hand-stacking techniques, and approach to criticality by remote operation. This experiment was designed by Tom McLaughlin in the mid seventies as part of the criticality safety course that is taught at Los Alamos Critical Experiment Facility (LACEF). The W-U-235 ratio for this experiment was 215 which is where the minimum critical mass for this configuration occurs

Critical mass experiment using 235U foils and lucite plates

International Nuclear Information System (INIS)

Sanchez, R.; Butterfield, K.; Kimpland, R.; Jaegers, P.

1998-01-01

This experiment demonstrated how the neutron multiplication of a system increases as moderated material is placed between highly enriched uranium foils. In addition, this experiment served to demonstrate the hand-stacking technique and approach to criticality be remote operation. This experiment was designed by McLaughlin in the mid-seventies as part of the criticality safety course that is taught at the Los Alamos Critical Experiments Facility. The H/ 235 U ratio for this experiment was 215, which is the ratio at which the minimum critical mass for this configuration occurs

Uncertainty of solute flux estimation in ungauged small streams: potential implications for input-output nutrient mass balances at stream reach scale

Directory of Open Access Journals (Sweden)

A. Butturini

2005-01-01

Full Text Available Input-output mass balances within stream reaches provide in situ estimates of stream nutrient retention/release under a wide spectrum of hydrological conditions. Providing good estimates of the mass balances for nutrients depends on precise hydrological monitoring and good chemical characterisation of stream water at the input and output ends of the stream reach. There is a need to optimise the hydrological monitoring and the frequencies of water sampling to yield precise annual mass balances, so as to avoid undue cost - high resolution monitoring and subsequent chemical analysis can be labour intensive and costly. In this paper, simulation exercises were performed using a data set created to represent the instantaneous discharge and solute dynamics at the input and output ends of a model stream reach during a one year period. At the output end, stream discharge and water chemistry were monitored continuously, while the input end was assumed to be ungauged; water sampling frequency was changed arbitrarily. Instantaneous discharge at the ungauged sampling point was estimated with an empirical power model linking the discharge to the catchment area (Hooper, 1986. The model thus substitutes for the additional gauge station. Simulations showed that 10 days was the longest chemical sampling interval which could provide reach annual mass balances of acceptable precision. Presently, the relationship between discharge and catchment area is usually assumed to be linear but simulations indicate that small departures from the linearity of this relationship could cause dramatic changes in the mass balance estimations.

Analytical review of minimum critical mass values for selected uranium and plutonium materials

International Nuclear Information System (INIS)

Morman, J.A.; Henrikson, D.J.; Garcia, A.S.

1997-01-01

Current subcritical limits for a number of uranium and plutonium materials (metals and compounds) as given in the ANSI/ANS standards for criticality safety are based on evaluations performed in the late 1970s and early 1980s. This paper presents the results of an analytical study of the minimum critical mass values for a set of materials using current codes and standard cross section sets. This work is meant to produce a consistent set of minimum critical mass values that can form the basis for adding new materials to the single-parameter tables in ANSI/ANS-8.1. Minimum critical mass results are presented for bare and water reflected full-density spheres and for full density moist (1.5 wt-% water) as calculated with KENO-Va, MCNP4A and ONEDANT. Calculations were also performed for both dry and moist materials at one-half density. Some KENO calculations were repeated using several cross section sets to examine potential bias differences. The results of the calculations were compared to the currently accepted subcritical limits. The calculated minimum critical mass values are reasonably consistent for the three codes, and differences most likely reflect differences in the cross section sets. The results are also consistent with values given in ANSI/ANS-8.1. 3 refs., 2 tabs

An approximate method to estimate the minimum critical mass of fissile nuclides

International Nuclear Information System (INIS)

Wright, R.Q.; Jordan, W.C.

1999-01-01

When evaluating systems in criticality safety, it is important to approximate the answer before any analysis is performed. There is currently interest in establishing the minimum critical parameters for fissile actinides. The purpose is to describe the OB-1 method for estimating the minimum critical mass for thermal systems based on one-group calculations and 235 U spheres fully reflected by water. The observation is made that for water-moderated, well-thermalized systems, the transport and leakage from the system are dominated by water. Under these conditions two fissile mixtures will have nearly the same critical volume provided the infinite media multiplication factor (k ∞ ) for the two systems is the same. This observation allows for very simple estimates of critical concentration and mass as a function of the hydrogen-to-fissile (H/X) moderation ratio by comparison to the known 235 U system

Evolving towards a critical point: A possible electromagnetic way in which the critical regime is reached as the rupture approaches

Directory of Open Access Journals (Sweden)

P. G. Kapiris

2003-01-01

Full Text Available In analogy to the study of critical phase transitions in statistical physics, it has been argued recently that the fracture of heterogeneous materials could be viewed as a critical phenomenon, either at laboratory or at geophysical scales. If the picture of the development of the fracture is correct one may guess that the precursors may reveal the critical approach of the main-shock. When a heterogeneous material is stretched, its evolution towards breaking is characterized by the appearance of microcracks before the final  break-up. Microcracks produce both acoustic and electromagnetic(EM emission in the frequency range from VLF to VHF. The microcracks and the associated acoustic and EM activities constitute the so-called precursors of general fracture. These precursors are detectable not only at laboratory but also at geophysical scales. VLF and VHF acoustic and EM emissions have been reported resulting from volcanic and seismic activities in various geologically distinct regions of the world. In the present work we attempt to establish the hypothesis that the evolution of the Earth's crust towards the critical point takes place not only in a mechanical but also in an electromagnetic sense. In other words, we focus on the possible electromagnetic criticality, which is reached while the catastrophic rupture in the Earth's crust approaches. Our main tool is the monitoring of micro-fractures that occur before the final breakup, by recording their radio-electromagnetic emissions. We show that the spectral power law analysis of the electromagnetic precursors reveals distinguishing signatures of underlying critical dynamics, such as: (i the emergence of memory effects; (ii the decrease with time of the anti-persistence behaviour; (iii the presence of persistence properties in the tail of the sequence of the precursors; and (iv the acceleration of the precursory electro-magnetic energy release. Moreover, the statistical analysis of the amplitudes of

Minimum mass of moderator required for criticality of homogeneous low-enriched uranium systems

Energy Technology Data Exchange (ETDEWEB)

Jordan, W.C.; Turner, J.C.

1992-12-01

A parametric calculational analysis has been performed in order to estimate the minimum mass of moderator required for criticality of homogeneous low-enriched uranium systems. The analysis was performed using a version of the SCALE-4.0 code system and the 27-group ENDF/B-IV cross-section library. Water-moderated uranyl fluoride (UO{sub 2}F{sub 2} and H{sub 2}O) and hydrofluoric-acid-moderated uranium hexaflouride (UF{sub 6} and HF) systems were considered in the analysis over enrichments of 1.4 to 5 wt % {sup 235}U. Estimates of the minimum critical volume, minimum critical mass of uranium, and the minimum mass of moderator required for criticality are presented. There was significant disagreement between the values generated in this study when compared with a similar undocumented study performed in 1983 using ANISN and the Knight-modified Hansen-Roach cross sections. An investigation into the cause of the disagreement was made, and the results are presented.

Minimum mass of moderator required for criticality of homogeneous low-enriched uranium systems

Energy Technology Data Exchange (ETDEWEB)

Jordan, W.C.; Turner, J.C.

1992-12-01

A parametric calculational analysis has been performed in order to estimate the minimum mass of moderator required for criticality of homogeneous low-enriched uranium systems. The analysis was performed using a version of the SCALE-4.0 code system and the 27-group ENDF/B-IV cross-section library. Water-moderated uranyl fluoride (UO[sub 2]F[sub 2] and H[sub 2]O) and hydrofluoric-acid-moderated uranium hexaflouride (UF[sub 6] and HF) systems were considered in the analysis over enrichments of 1.4 to 5 wt % [sup 235]U. Estimates of the minimum critical volume, minimum critical mass of uranium, and the minimum mass of moderator required for criticality are presented. There was significant disagreement between the values generated in this study when compared with a similar undocumented study performed in 1983 using ANISN and the Knight-modified Hansen-Roach cross sections. An investigation into the cause of the disagreement was made, and the results are presented.

IMAGE-PLANE ANALYSIS OF n-POINT-MASS LENS CRITICAL CURVES AND CAUSTICS

Energy Technology Data Exchange (ETDEWEB)

Danek, Kamil; Heyrovský, David, E-mail: kamil.danek@utf.mff.cuni.cz, E-mail: heyrovsky@utf.mff.cuni.cz [Institute of Theoretical Physics, Faculty of Mathematics and Physics, Charles University in Prague (Czech Republic)

2015-06-10

The interpretation of gravitational microlensing events caused by planetary systems or multiple stars is based on the n-point-mass lens model. The first planets detected by microlensing were well described by the two-point-mass model of a star with one planet. By the end of 2014, four events involving three-point-mass lenses had been announced. Two of the lenses were stars with two planetary companions each; two were binary stars with a planet orbiting one component. While the two-point-mass model is well understood, the same cannot be said for lenses with three or more components. Even the range of possible critical-curve topologies and caustic geometries of the three-point-mass lens remains unknown. In this paper we provide new tools for mapping the critical-curve topology and caustic cusp number in the parameter space of n-point-mass lenses. We perform our analysis in the image plane of the lens. We show that all contours of the Jacobian are critical curves of re-scaled versions of the lens configuration. Utilizing this property further, we introduce the cusp curve to identify cusp-image positions on all contours simultaneously. In order to track cusp-number changes in caustic metamorphoses, we define the morph curve, which pinpoints the positions of metamorphosis-point images along the cusp curve. We demonstrate the usage of both curves on simple two- and three-point-mass lens examples. For the three simplest caustic metamorphoses we illustrate the local structure of the image and source planes.

Complex hydro- and sediment dynamics survey of two critical reaches on the Hungarian part of river Danube

International Nuclear Information System (INIS)

Baranya, Sandor; Jozsa, Janos; Goda, Laszlo; Rakoczi, Laszlo

2008-01-01

Detailed hydrodynamic survey of two critical river reaches has been performed from hydro- and sediment dynamics points of view, in order to explore the main features, moreover, provide calibration and verification data to related 3D flow and sediment transport modelling. Special attention has been paid to compare moving and fix boat measurement modes for estimating various flow and large-scale bed form features, resulting in recommendations e.g. on the time period needed in stationary mode operation to obtain sufficiently stabilized average velocity profiles and related parameter estimations. As to the study reaches, the first comprises a 5 km long sandy-gravel bed reach of river Danube located in Central-Hungary, presenting problems for navigation. As a conventional remedy, groyne fields have been implemented to make and maintain the reach sufficiently deep, navigable even in low flow periods. As is usually the case, these works resulted in rather complex flow characteristics and related bed topography at places. The second site is another 5 km long reach of river Danube, close to the southern border to Serbia. There the river presents navigational problems similar to the previously mentioned reach, however, having entirely sand bed conditions, abundant in a variety of dunes, especially in the shallower parts. In both study reaches ADCP measurements were done with around 2.5 Hz sampling frequency both in moving boat operation mode providing overall, though locally moderately representative picture, and in fixed boat mode at a considerable number of selected verticals with 10 minutes long measuring time.

Critical masses of bare metal spheres using SCALE/XSDRN

International Nuclear Information System (INIS)

Wright, R.Q.; Jordan, W.C.; Westfall, R.M.

2000-01-01

More than 200 actinide isotopes are known; most of them have very short half-lives (only 45 with T 1/2 > 40 days). Only 41 have been predicted capable of a self-sustaining nuclear chain reaction, some of them with fast neutrons and others with either thermal or fast neutrons. Of these 41 there are 13 nuclides for which the average production is >1 g/tonne for pressurized water reactors or boiling water reactors (35 GWd/tonne--power 35 W/g; cooling time, 90 days). Six actinides, 233 U, 235 U, 238 U, 239 Pu, 240 Pu, and 241 Pu, have cross sections that are relatively well known. Cross sections for the other actinides are not as well known. In the United States, criticality safety guidelines for nuclides other than 233 U, 235 U, and 239 Pu is provided by the American National Standard for Nuclear Criticality Control of Special Actinide Elements, ANSI/ANS-8.15. The standard appeared in 1981 and was reaffirmed in 1987 and 1995. The standard provides guidance for 14 nuclei: 237 Np, 238 Pu, 240 Pu, 241 Pu, 242 Pu, 241 Am, 242m Am, 243 Am, 243 Cm, 244 Cm, 245 Cm, 247 Cm, 249 Cf, and 251 Cf. The ANS-8.15 Standard Work Group is in the process of revising the standard. Five nuclides will be added to the list of nuclides included-- 231 Pa, 234 U, 250 Cf, 252 Cf, and 254 Es--resulting in a total of 19 nuclides in the revised standard. Subcritical mass limits in the current standard are based on calculations by Clark and Westfall. The calculations were based on ENDF/B-IV and preliminary ENDF/B-V evaluations. For several of the actinides, new or revised evaluations are available in ENDF/B-VI. All of the 19 nuclides in the revised standard are included in the current paper with the exception of 231 Pa. In a previous paper, minimum critical mass estimates for metal-water mixtures (spherical geometry), fully reflected by water, for 20 fissile nuclides with values of Z between 92 and 99 were given. A simple exponential fit was developed that gives quite accurate values for the

Critical masses of miniexplosion in fission-fusion hybrid systems

Energy Technology Data Exchange (ETDEWEB)

Kaliski, S [Polska Akademia Nauk, Warsaw. Inst. Podstawowych Problemow Techniki

1976-01-01

The critical mass of the fissionable material subjected to the explosive compression and the action of the neutron stream originating from the process of D-T fusion in the spherical cavity was estimated. High energy recovery from the fissionable material was obtained and the energy of the laser pulse was minimized.

Critical and subcritical mass calculations of fissionable nuclides based on JENDL-3.2+

International Nuclear Information System (INIS)

Okuno, H.

2002-01-01

We calculated critical and subcritical masses of 10 fissionable actinides ( 233 U, 235 U, 238 Pu, 239 Pu, 241 Pu, 242m Am, 243 Cm, 244 Cm, 249 Cf and 251 Cf) in metal and in metal-water mixtures (except 238 Pu and 244 Cm). The calculation was made with a combination of a continuous energy Monte Carlo neutron transport code, MCNP-4B2, and the latest released version of the Japanese Evaluated Nuclear Data Library, JENDL-3.2. Other evaluated nuclear data files, ENDF/B-VI, JEF-2.2, and JENDL-3.3 in its preliminary version were also applied to find differences in results originated from different nuclear data files. For the so-called big three fissiles ( 233 U, 235 U and 239 Pu), analyzing the criticality experiments cited in ICSBEP Handbook validated the code-library combination, and calculation errors were consequently evaluated. Estimated critical and lower limit critical masses of the big three in a sphere with/without a water or SS-304 reflector were supplied, and they were compared with the subcritical mass limits of ANS-8.1. (author)

Effects of various moderators on the critical mass of plutonium

International Nuclear Information System (INIS)

Doherty, A.L.

1986-01-01

The fissile material storage tanks in the Hanford Plutonium Critical Mass Laboratory (CML) in Richland, Washington, are presently being upgraded. During the design and planning phase of this modification, criticality analysis was necessary to compare potential moderator/absorber materials used as isolators between tanks. A parameter study was performed to assist in determining the appropriate moderator material to be used in the plutonium nitrate storage tank system in the mix room at the CML. Four moderator/absorber materials were identified as providing adequate isolation between the tanks

Gamow's calculation of the neutron star's critical mass revised

International Nuclear Information System (INIS)

Ludwig, Hendrik; Ruffini, Remo

2014-01-01

It has at times been indicated that Landau introduced neutron stars in his classic paper of 1932. This is clearly impossible because the discovery of the neutron by Chadwick was submitted more than one month after Landau's work. Therefore, and according to his calculations, what Landau really did was to study white dwarfs, and the critical mass he obtained clearly matched the value derived by Stoner and later by Chandrasekhar. The birth of the concept of a neutron star is still today unclear. Clearly, in 1934, the work of Baade and Zwicky pointed to neutron stars as originating from supernovae. Oppenheimer in 1939 is also well known to have introduced general relativity (GR) in the study of neutron stars. The aim of this note is to point out that the crucial idea for treating the neutron star has been advanced in Newtonian theory by Gamow. However, this pioneering work was plagued by mistakes. The critical mass he should have obtained was 6.9 M, not the one he declared, namely, 1.5 M. Probably, he was taken to this result by the work of Landau on white dwarfs. We revise Gamow's calculation of the critical mass regarding calculational and conceptual aspects and discuss whether it is justified to consider it the first neutron-star critical mass. We compare Gamow's approach to other early and modern approaches to the problem.

Renal mass anatomic characteristics and perioperative outcomes of laparoscopic partial nephrectomy: a critical analysis.

Science.gov (United States)

Tsivian, Matvey; Ulusoy, Said; Abern, Michael; Wandel, Ayelet; Sidi, A Ami; Tsivian, Alexander

2012-10-01

Anatomic parameters determining renal mass complexity have been used in a number of proposed scoring systems despite lack of a critical analysis of their independent contributions. We sought to assess the independent contribution of anatomic parameters on perioperative outcomes of laparoscopic partial nephrectomy (LPN). Preoperative imaging studies were reviewed for 147 consecutive patients undergoing LPN for a single renal mass. Renal mass anatomy was recorded: Size, growth pattern (endo-/meso-/exophytic), centrality (central/hilar/peripheral), anterior/posterior, lateral/medial, polar location. Multivariable models were used to determine associations of anatomic parameters with warm ischemia time (WIT), operative time (OT), estimated blood loss (EBL), intra- and postoperative complications, as well as renal function. All models were adjusted for the learning curve and relevant confounders. Median (range) tumor size was 3.3 cm (1.5-11 cm); 52% were central and 14% hilar. While 44% were exophytic, 23% and 33% were mesophytic and endophytic, respectively. Anatomic parameters did not uniformly predict perioperative outcomes. WIT was associated with tumor size (P=0.068), centrality (central, P=0.016; hilar, P=0.073), and endophytic growth pattern (P=0.017). OT was only associated with tumor size (Panatomic parameter predicted EBL. Tumor centrality increased the odds of overall and intraoperative complications, without reaching statistical significance. Postoperative renal function was not associated with any of the anatomic parameters considered after adjustment for baseline function and WIT. Learning curve, considered as a confounder, was independently associated with reduced WIT and OT as well as reduced odds of intraoperative complications. This study provides a detailed analysis of the independent impact of renal mass anatomic parameters on perioperative outcomes. Our findings suggest diverse independent contributions of the anatomic parameters to the

Examining the Possibility of an E-Resource Collection Maximal Mass: Looking beyond the Critical Mass of E-Journals

Science.gov (United States)

Lamothe, Alain R.

2014-01-01

This article investigates the possibility that e-journal collections can reach a maximum size that satisfies long-term patron needs without further significant expansion. The study included collection and usage data taken from 2000 to 2013. In terms of the e-journal collection, the occurrence of a maximal mass appears to be very real. The…

The measurements of critical mass with uranium fuel elements and thorium rods

International Nuclear Information System (INIS)

Yao Zhiquan; Chen Zhicheng; Yao Zewu; Ji Huaxiang; Bao Borong; Zhang Jiahua

1991-01-01

The critical experiments with uranium elements and Thorium rods have been performed in zero power reactor at Shanghai Institute of Nuclear Research. The critical masses have been measured in various U/Th ratios. The fuels are 3% 235 U-enriched uranium. The Thorium rods are made from power of ThF 4 . Ratios of calculated values to experimental values are nearly constant at 0.995

(Hypo) critical mass: do women make a difference?

Science.gov (United States)

Pandian, H

1997-01-01

The debate about the gender impact of women journalists on society encompass several issues. First of all, there is the question of whether women have influenced and expanded the definition of "news." Surveys reveal that the topics of interest in newspapers differ for women and men, and that this gap is widening in some areas and closing in others. While some researchers find that women's reporting is more humanized, whereas that of men is more objective, feminists decry this distinction because it assumes that gender is a fixed property of individuals instead of part of a continuing process of identity-seeking. Such a rigid construction of "gender" results in relegating women to the "women's page ghetto." Secondly, there is the question of whether a "critical mass" of women in the newsroom is necessary in order for women to change patterns of gender representation. One opinion states that women will be unable to change anything as long as they remain in subordinate positions; others feel that a critical mass of 25-30% women would make a difference. It seems that long-term change will not occur until educational institutions that train journalists develop a journalistic norm that requires use of all human senses, celebrates diversity, and rejects "pre-thought" ideas. Such institutions could train the women and men who may transform the media and create a new gender code by changing existing value systems.

Critical mass theory and women directors’ contribution to board strategic tasks

Directory of Open Access Journals (Sweden)

Mariateresa Torchia

2010-11-01

Full Text Available In this article we offer an empirical test of the critical mass arguments in the discussion of women on corporate boards. The literature in the women on corporate board debate concludes that there must be at least three women on a board before the women really make a difference. These arguments are frequently used in the public debate about the understanding the impact of women on corporate boards, but they have never really been empirically tested on a large sample. In this paper we use a sample of 317 Norwegian firms. Our dependent variable is board strategic involvement. The findings support the critical mass arguments. This study offers useful insights to policy-makers interested in defining legislative measures mandating the presence of women directors in corporate boards by showing that “at least three women” may be particularly beneficial in terms of contribution to board strategic tasks.

Post-critical behavior of Beck`s column with a tip mass

DEFF Research Database (Denmark)

Andersen, S. B.; Thomsen, Jon Juel

2002-01-01

This study examines how a tip mass with rotary inertia affects the stability of a follower-loaded cantilevered column. Using nonlinear modeling and perturbation analysis, expressions are set up for determining the stability of the straight column and the amplitude of post-critical flutter...... oscillations. Bifurcation diagrams are given, showing how the vibration amplitude changes with follower load and other parameters. These results agree closely with numerical simulation. It is found that sufficiently large values of tip mass rotary inertia can change the primary bifurcation from supercritical...

The Effects of Moon’s Uneven Mass Distribution on the Critical Inclinations of a Lunar Orbiter

Directory of Open Access Journals (Sweden)

Walid A. Rahoma

2014-12-01

Full Text Available The uneven mass distribution of the Moon highly perturbs the lunar spacecrafts. This uneven mass distribution leads to peculiar dynamical features of the lunar orbiters. The critical inclination is the value of inclination which keeps the deviation of the argument of pericentre from the initial values to be zero. Considerable investigations have been performed for critical inclination when the gravity field is assumed to be symmetric around the equator, namely for oblate gravity field to which Earth’s satellites are most likely to be subjected. But in the case of a lunar orbiter, the gravity field of mass distribution is rather asymmetric, that is, sectorial, and tesseral, harmonic coefficients are big enough so they can’t be neglected. In the present work, the effects of the first sectorial and tesseral harmonic coefficients in addition to the first zonal harmonic coefficients on the critical inclination of a lunar artificial satellite are investigated. The study is carried out using the Hamiltonian framework. The Hamiltonian of the problem is cconstructed and the short periodic terms are eliminated using Delaunay canonical variables. Considering the above perturbations, numerical simulations for a hypothetical lunar orbiter are presented. Finally, this study reveals that the critical inclination is quite different from the critical inclination of traditional sense and/or even has multiple solutions. Consequently, different families of critical inclination are obtained and analyzed.

Critical discharge of fluids and gases

International Nuclear Information System (INIS)

Seewald, Michael

2012-01-01

The thermal hydraulic relations during discharge of fluids and gases are complex and a closed solution does not seem to be available. For the modeling of leakage accidents in nuclear power plants basic considerations are suitable for statements on the maximum mass flow, and thus the leak rate. The maximum mass flow is reached when the critical velocity is reached in the smallest cross section. This allows the appropriate design of safety systems for one-phase and two-phase flows. For German NPP simulators the hydrodynamics simulation program RELAP5-3D is used. The simulator center operates a 1:10 scale gas model of a two-loop PWR type reactor. The observable phenomena have occurred in nuclear power plants. The characteristics for a visualization of two-phase flows are not available in the simulation software and have to be added by correlations with experimental results. The realization of expectations on digital visualization techniques is discussed.

Critical mass, rod values and reactivity coefficients for Rapsodie; Masse critique, valeur des barres et coefficients de reactivite de rapsodie

Energy Technology Data Exchange (ETDEWEB)

Stevens, L; Gourdon, J [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

1967-07-01

Besides a brief general description, the report contains a description and discussion of the aims, the methods used and the results of critical mass, rod worth and static reactivity coefficient measurements on the Rapsodie reactor. (authors) [French] Apres une breve description generale, le rapport decrit et discute le but, les methodes employees et les resultats des mesures de masse critique, de reactivite des barres et des coefficients de reactivite statiques du reacteur RAPSODIE. (auteurs)

Using Videos To Teach Mass Media and Society from a Critical Perspective.

Science.gov (United States)

King, Donna Lee

2000-01-01

Explores using videos to teach mass media and society from a critical sociological perspective. Discusses the content of the course from focusing on analysis of corporate capitalism and media producers to analyzing popular media texts on gender, race, the working class, and sexuality. Addresses the evaluation of the course. (CMK)

PULSATION-TRIGGERED MASS LOSS FROM AGB STARS: THE 60 DAY CRITICAL PERIOD

International Nuclear Information System (INIS)

McDonald, I.; Zijlstra, A. A.

2016-01-01

Low- and intermediate-mass stars eject much of their mass during the late, red giant branch (RGB) phase of evolution. The physics of their strong stellar winds is still poorly understood. In the standard model, stellar pulsations extend the atmosphere, allowing a wind to be driven through radiation pressure on condensing dust particles. Here, we investigate the onset of the wind, using nearby RGB stars drawn from the Hipparcos catalog. We find a sharp onset of dust production when the star first reaches a pulsation period of 60 days. This approximately coincides with the point where the star transitions to the first overtone pulsation mode. Models of the spectral energy distributions show stellar mass-loss rate suddenly increasing at this point, by a factor of ∼10 over the existing (chromospherically driven) wind. The dust emission is strongly correlated with both pulsation period and amplitude, indicating stellar pulsation is the main trigger for the strong mass loss, and determines the mass-loss rate. Dust emission does not strongly correlate with stellar luminosity, indicating radiation pressure on dust has little effect on the mass-loss rate. RGB stars do not normally appear to produce dust, whereas dust production by asymptotic giant branch stars appears commonplace, and is probably ubiquitous above the RGB-tip luminosity. We conclude that the strong wind begins with a step change in mass-loss rate and is triggered by stellar pulsations. A second rapid mass-loss-rate enhancement is suggested when the star transitions to the fundamental pulsation mode at a period of ∼300 days.

An application of the 'end-point' method to the minimum critical mass problem in two group transport theory

International Nuclear Information System (INIS)

Williams, M.M.R.

2003-01-01

A two group integral equation derived using transport theory, which describes the fuel distribution necessary for a flat thermal flux and minimum critical mass, is solved by the classical end-point method. This method has a number of advantages and in particular highlights the changing behaviour of the fissile mass distribution function in the neighbourhood of the core-reflector interface. We also show how the reflector thermal flux behaves and explain the origin of the maximum which arises when the critical size is less than that corresponding to minimum critical mass. A comparison is made with diffusion theory and the necessary and somewhat artificial presence of surface delta functions in the fuel distribution is shown to be analogous to the edge transients that arise naturally in transport theory

[Variation of muscle mass and weight in critical patient].

Science.gov (United States)

Valls-Matarín, J; del Cotillo-Fuente, M; Grané-Mascarell, N; Quintana, S

2015-01-01

Quantify the muscle mass and body weight variation in critically ill patients and to identify associated factors. A descriptive follow-up study. Data for demographic variables, body weight, fluid balance, daily kilocalories, the amount of sedation and muscle relaxants received and motor physiotherapy applied were collected. Three consecutive measurements were performed in the brachial biceps and quadriceps rectus by using ultrasound, upon admission and every 5 days until discharge. 68 patients were included. Average age was of 73.5 [57-78,5] years. The median length of stay was 9.5 [5.5 -15] days. The median 16 (SD=5.7) daily kilocalories per kg/weight, 91.2% received sedation, 44.1% received muscle relaxants and 20% received physiotherapy. The patients presented a muscle wasting of 4.9 (SD=3.9)mm, p <.001 in the brachial biceps and 5.6 (SD=4.8)mm, p <.001 in the quadriceps rectus. Regression analysis selected the length of stay and the muscle relaxants are the most influential variables in the brachial biceps muscle wasting (R2=0.4), and length of stay as the most influential in the quadriceps rectus muscle wasting (R2=0.3). Patient's mean body weight on admission was of 81.1 (SD=15)kg and 81.2 (SD=14.2)kg on discharge, p=.95. The critically ill patient presents a significant muscle waste related with the length of stay and the treatment received with muscle relaxants. Patients are being discharged with a similar body weight to which they were admitted but with a significant reduction of muscle mass. Copyright © 2014 Elsevier España, S.L.U. y SEEIUC. All rights reserved.

Inactivation of Parietal Reach Region Affects Reaching But Not Saccade Choices in Internally Guided Decisions.

Science.gov (United States)

Christopoulos, Vassilios N; Bonaiuto, James; Kagan, Igor; Andersen, Richard A

2015-08-19

The posterior parietal cortex (PPC) has traditionally been considered important for awareness, spatial perception, and attention. However, recent findings provide evidence that the PPC also encodes information important for making decisions. These findings have initiated a running argument of whether the PPC is critically involved in decision making. To examine this issue, we reversibly inactivated the parietal reach region (PRR), the area of the PPC that is specialized for reaching movements, while two monkeys performed a memory-guided reaching or saccade task. The task included choices between two equally rewarded targets presented simultaneously in opposite visual fields. Free-choice trials were interleaved with instructed trials, in which a single cue presented in the peripheral visual field defined the reach and saccade target unequivocally. We found that PRR inactivation led to a strong reduction of contralesional choices, but only for reaches. On the other hand, saccade choices were not affected by PRR inactivation. Importantly, reaching and saccade movements to single instructed targets remained largely intact. These results cannot be explained as an effector-nonspecific deficit in spatial attention or awareness, since the temporary "lesion" had an impact only on reach choices. Hence, the PPR is a part of a network for reach decisions and not just reach planning. There has been an ongoing debate on whether the posterior parietal cortex (PPC) represents only spatial awareness, perception, and attention or whether it is also involved in decision making for actions. In this study we explore whether the parietal reach region (PRR), the region of the PPC that is specialized for reaches, is involved in the decision process. We inactivated the PRR while two monkeys performed reach and saccade choices between two targets presented simultaneously in both hemifields. We found that inactivation affected only the reach choices, while leaving saccade choices intact

Nuclear criticality safety calculations for a K-25 site vacuum cleaner

International Nuclear Information System (INIS)

Shor, J.T.; Haire, M.J.

1997-02-01

A modified Nilfisk model GSJ dry vacuum cleaner is used throughout the K-25 Site to collect dry forms of highly enriched uranium (HEU). When vacuuming, solids are collected in a cyclone-type separator vacuum cleaner body. Calculations were done with the SCALE (KENO V.a) computer code to establish conditions at which a nuclear criticality event might occur if the vacuum cleaner was filled with fissile solution. Conditions evaluated included full (12-in. water) reflection and nominal (1-in. water) reflection, and full (100%) and 20% 235 U enrichment. Validation analyses of SCALE/KENO and the SCALE 27-group cross sections for nuclear criticality safety applications indicate that a calculated k eff + 2σ eff + 2σ ≥ 0.9605 is considered unsafe and may be critical. Critical conditions were calculated to be 70 g U/L for 100% 235 U and full 12-in. water reflection. This corresponds to a minimum critical mass of approximately 1,400 g 235 U for the approximate 20.0-L volume of the vacuum cleaner. The actual volume of the vacuum cleaner is smaller than the modeled volume because some internal materials of construction were assumed to be fissile solution. The model was an overestimate, for conservatism, of fissile solution occupancy. At nominal reflection conditions, the critical concentration in a vacuum cleaner full of UO 2 F 2 solution was calculated to be 100 g 235 U/L, or 2,000 g mass of 100% 235 U. At 20% 235 U for the 20.0-L volume of the vacuum cleaner. At 15% 235 U enrichment and full reflection, critical conditions were not reached at any possible concentration of uranium as a uranyl fluoride solution. At 17.5% 235 U enrichment, criticality was reached at approximately 1,300 g U/L which is beyond saturation at 25 C

Study on expansion power recovery in CO2 trans-critical cycle

International Nuclear Information System (INIS)

Tian Hua; Ma Yitai; Li Minxia; Wang Wei

2010-01-01

Due to the ozone depletion potential and global warming potential of CFCs and HCFCs, CO 2 is considered as most potential alternative refrigerant. However, there are serious throttle losses and low system efficiency to CO 2 trans-critical cycle because of its low critical temperature and high operating pressure. The aim of this paper is to design an expander to recover expansion power in CO 2 trans-critical cycle. The theoretical analysis and calculation show that 14-23% of input power of compressor can be recovered. A prototype of rolling piston expander is designed and manufactured and its test facility is established. The test facility consists of CO 2 trans-critical cycle, the expander, the chilling water system and the cooling water system. The experimental results show that the recovery ratio and expander efficiency are affected by rotational speed, inlet temperature and mass flow of expander. The highest recovery ratio can reach to 0.145, which means 14.5% of input power of compressor can be recovered. The expander efficiency can reach to 45%.

Lawson concepts and criticality in DT fusion reactors

International Nuclear Information System (INIS)

Lartigue, J.G.

1987-01-01

The original Lawson concepts (amplification factor R and parameter nτ) as well as their applications in DT reactors are discussed in two cases: the ignition regime and the subignition regime in a self-sufficient plant. The modified Lawson factor or internal amplification factor R a (a function of alpha power) is proposed as a means to measure the ignition level reached by the plasma, in a more precise way than that given by the collective parameter (nτkT). The self-sufficiency factor (δ) is proposed as a means to measure the plant self-sufficiency, δ being more significant than the traditional Q factor. It is stated that the ignition regime (R a = 1) is equivalent to a critical state (energy equilibrium); then, the corresponding critical mass concept is proposed. The analysis of the R a relationship with temperature (kT), (nτ), and recirculating factor (var-epsilon) gives the conditions for the reactor to reach ignition or for the plant to reach self-sufficiency; it also shows that an approach to ignition is not improved by heating from 50 to 100 KeV

Non-equilibrium effects on the two-phase flow critical phenomenon

International Nuclear Information System (INIS)

Sami, S.M.

1988-01-01

In the present study, the choking criterion for nonhomogeneous nonequilibrium two phase flow is obtained by solving the two-fluid model conservation equations. The method of characteristics is employed to predict the critical flow conditions. Critical flow is established after the magnitude of the characteristic slopes (velocities). Critical flow conditions are reached when the smallest characteristic slope becomes equal to zero. Several expression are developed to determine the nonequilibrium mass and heat exchanges in terms of the system dependent parameters derivatives. In addition, comprehensive transition flow regime maps are employed in the calculation of interfacial heat and momentum transfer rates. Numerical results reveal that the proposed model reliably predicts the critical two-phase flow phenomenon under different inlet conditions and compares well with other existing models

Characterization of neutron leakage probability, k /SUB eff/ , and critical core surface mass density of small reactor assemblies through the Trombay criticality formula

International Nuclear Information System (INIS)

Kumar, A.; Rao, K.S.; Srinivasan, M.

1983-01-01

The Trombay criticality formula (TCF) has been derived by incorporating a number of well-known concepts of criticality physics to enable prediction of changes in critical size or k /SUB eff/ following alterations in geometrical and physical parameters of uniformly reflected small reactor assemblies characterized by large neutron leakage from the core. The variant parameters considered are size, shape, density and diluent concentration of the core, and density and thickness of the reflector. The effect of these changes (except core size) manifests, through sigma /SUB c/ the critical surface mass density of the ''corresponding critical core,'' that sigma, the massto-surface-area ratio of the core,'' is essentially a measure of the product /rho/ extended to nonspherical systems and plays a dominant role in the TCF. The functional dependence of k /SUB eff/ on sigma/sigma /SUB c/ , the system size relative to critical, is expressed in the TCF through two alternative representations, namely the modified Wigner rational form and, an exponential form, which is given

Functional reach and lateral reach tests adapted for aquatic physical therapy

Directory of Open Access Journals (Sweden)

Ana Angélica Ribeiro de Lima

Full Text Available Abstract Introduction: Functional reach (FR and lateral reach (LR tests are widely used in scientific research and clinical practice. Assessment tools are useful in assessing subjects with greater accuracy and are usually adapted according to the limitations of each condition. Objective: To adapt FR and LR tests for use in an aquatic environment and assess the performance of healthy young adults. Methods: We collected anthropometric data and information on whether the participant exercised regularly or not. The FR and LR tests were adapted for use in an aquatic environment and administered to 47 healthy subjects aged 20-30 years. Each test was repeated three times. Results: Forty-one females and six males were assessed. The mean FR test score for men was 24.06 cm, whereas the mean value for right lateral reach (RLR was 10.94 cm and for left lateral reach (LLR was 9.78 cm. For females, the mean FR score was 17.57 cm, while the mean values for RLR was 8.84cm and for LLR was 7.76 cm. Men performed better in the FR (p < 0.001 and RLR tests than women (p = 0.037. Individuals who exercised regularly showed no differences in performance level when compared with their counterparts. Conclusion: The FR and LR tests were adapted for use in an aquatic environment. Males performed better on the FR and RLR tests, when compared to females. There was no correlation between the FR and LR tests and weight, height, Body Mass Index (BMI, foot length or length of the dominant upper limb.

Critical assessment of nuclear mass models

International Nuclear Information System (INIS)

Moeller, P.; Nix, J.R.

1992-01-01

Some of the physical assumptions underlying various nuclear mass models are discussed. The ability of different mass models to predict new masses that were not taken into account when the models were formulated and their parameters determined is analyzed. The models are also compared with respect to their ability to describe nuclear-structure properties in general. The analysis suggests future directions for mass-model development

Study on hydrodynamics and mass transfer of the critically safe multistage mixer-settler

International Nuclear Information System (INIS)

Zhang Weibo; Jiao Rongzhou; Liu Bingren

1992-08-01

The study on structure of critically safe multistage mixer-settler for the extraction process of high enriched uranium and plutonium has been completed. The mixer-settler has simple structure, good critical safety, flexibility in operation (O/A from 0.5 to 5) and high extraction efficiency (E x > 90%). These performances have been proved in the hydrodynamics and mass transfer experiments at a three stages cascade mixer-settler. Based on the others experience, a trapezoidal impeller combined with half-open turbine is developed which has stronger pumping and well mixing function at low rotating speed. The optimal rotating speed is 250 to 280 r/min obtained by experiments

Calculation of the fissile mass of a graphite moderated critical assembly using 93% enriched uranium

International Nuclear Information System (INIS)

Correa, F.; Marzo, M.A.S.; Collussi, I.; Ferreira, A.C.A.

1976-01-01

The critical mass of uranium has been calculated for a graphite moderated set fueled with 93% enriched uranium to be mounted on the Instituto de Energia Atomica split table Zero Power Reactor. The core composition was optimized to permit the maximum number of configurations to be studied. Analysis of three core compositions shows that 8 Kg of uranium enriched to 93% - U-235 (by weight) and 100 Kg of thorium would be sufficient for criticality experiments [pt

Critical Mass als performative Kritik der städtischen Verkehrspolitik? Fahrradfahren mit Judith Butler auf dem Gepäckträger

Directory of Open Access Journals (Sweden)

Anke Strüver

2015-11-01

Full Text Available Obwohl die meisten deutschen Großstädte über eine sehr schlechte Radverkehrsinfrastruktur verfügen, gewinnent innerstädtisches Radfahren und ein Engagement für das Rad als gleichberechtigtes Verkehrsmittel stark an Bedeutung. Als Indiz für dieses Engagement gelten in Hamburg die monatlichen Critical Mass Radfahrten unter dem Motto „We aren’t blocking traffic… we are traffic!“. Der Beitrag fragt vor diesem Hintergrund, inwiefern die Critical Mass als Aktionsform in Hamburg den Diskurs der autogerechten Stadt, die Straßenverkehrspolitik und die dominante räumliche Ordnung in Frage stellen kann und ob die Critical Mass als performative Kritik der normativen Ordnung im Sinne Judith Butlers verstanden werden kann.

Borders amidst power, State and mass media, from a critical theory standpoint

Directory of Open Access Journals (Sweden)

Manuel Ortiz Marín

2006-07-01

Full Text Available A conception of the power, from the glance of the Critical Theory that it allows to understand the woven complex that links the relations of power to most of the human activities. This paper also approaches to the State as a regulating element of the different forces from institutional character, that they operate in its interior like structures of power and the function as that the massive mass media in the complexity of the modern societies act.

Simulation of Columbia River Floods in the Hanford Reach

Energy Technology Data Exchange (ETDEWEB)

Waichler, Scott R.; Serkowski, John A.; Perkins, William A.; Richmond, Marshall C.

2017-01-30

Columbia River water elevations and flows in the Hanford Reach affect the environment and facilities along the shoreline, including movement of contaminants in groundwater, fish habitat, and infrastructure subject to flooding. This report describes the hydraulic simulation of hypothetical flood flows using the best available topographic and bathymetric data for the Hanford Reach and the Modular Aquatic Simulation System in 1 Dimension (MASS1) hydrodynamic model. The MASS1 model of the Hanford Reach was previously calibrated to field measurements of water surface elevations. The current model setup can be used for other studies of flow, water levels, and temperature in the Reach. The existing MASS1 channel geometry and roughness and other model configuration inputs for the Hanford Reach were used for this study, and previous calibration and validation results for the model are reprinted here for reference. The flood flows for this study were simulated by setting constant flow rates obtained from the U.S. Army Corps of Engineers (USACE) for the Columbia, Snake, and Yakima Rivers, and a constant water level at McNary Dam, and then running the model to steady state. The discharge levels simulated were all low-probability events; for example, a 100-year flood is one that would occur on average every 100 years, or put another way, in any given year there is a 1% chance that a discharge of that level or higher will occur. The simulated floods and their corresponding Columbia River discharges were 100-year (445,000 cfs), 500-year (520,000 cfs), and the USACE-defined Standard Project Flood (960,000 cfs). The resulting water levels from the steady-state floods can be viewed as “worst case” outcomes for the respective discharge levels. The MASS1 output for water surface elevations was converted to the North American Vertical Datum of 1988 and projected across the channel and land surface to enable mapping of the floodplain for each scenario. Floodplain maps show that for

Critical heat flux correlation analysis for PWR reactors with low mass flow

International Nuclear Information System (INIS)

Carajilescov, Pedro

1996-01-01

The major limit in the thermalhydraulic design of water cooled reactors consists in the occurrence of critical heat flux, which is verified by correlation of large range of validity. In the present work, the major design correlations were analyzed, through comparisons with experimental data, for utilization in PWR with low mass flux in the core. The results show that the EPRI correlation, with modifications, gives conservative results, from the safety point of view, with lower data spreading, being the most indicated for the reactor thermal design. (author)

Quasiparticle mass enhancement close to the quantum critical point in BaFe2(As(1-x)P(x))2.

Science.gov (United States)

Walmsley, P; Putzke, C; Malone, L; Guillamón, I; Vignolles, D; Proust, C; Badoux, S; Coldea, A I; Watson, M D; Kasahara, S; Mizukami, Y; Shibauchi, T; Matsuda, Y; Carrington, A

2013-06-21

We report a combined study of the specific heat and de Haas-van Alphen effect in the iron-pnictide superconductor BaFe2(As(1-x)P(x))2. Our data when combined with results for the magnetic penetration depth give compelling evidence for the existence of a quantum critical point close to x=0.30 which affects the majority of the Fermi surface by enhancing the quasiparticle mass. The results show that the sharp peak in the inverse superfluid density seen in this system results from a strong increase in the quasiparticle mass at the quantum critical point.

Enhanced mass removal due to phase explosion during high irradiance nanosecond laser ablation of silicon

Energy Technology Data Exchange (ETDEWEB)

Yoo, Jong Hyun [Univ. of California, Berkeley, CA (United States)

2000-05-01

The morphology of craters resulting from high irradiance laser ablation of silicon was measured using a white light interferometry microscope. The craters show a dramatic increase in their depth and volume at a certain irradiance, indicating a change in the primary mechanism for mass removal. Laser shadowgraph imaging was used to characterize and differentiate the mass ejection processes for laser irradiances above and below the threshold value. Time-resolved images show distinct features of the mass ejected at irradiances above the threshold value including the presence of micron-sized particulates; this begins at approximately 300 ~ 400 ns after the start of laser heating. The analysis of the phenomena was carried out by using two models: a thermal evaporation model and a phase explosion model. Estimation of the crater depth due to the thermally evaporated mass led to a large underestimation of the crater depth for irradiances above the threshold. Above the threshold irradiance, the possibility of phase explosion was analyzed. Two important results are the thickness of the superheated liquid layer that is close to the critical temperature and the time for vapor bubbles that are generated in the superheated liquid to achieve a critical size. After reaching the critical size, vapor bubbles can grow spontaneously resulting in a violent ejection of liquid droplets from the superheated volume. The effects of an induced transparency, i.e. of liquid silicon turning into an optically transparent liquid dielectric medium, are also introduced. The estimated time for a bubble to reach the critical size is in agreement with the delay time measured for the initiation of large mass ejection. Also, the thickness of the superheated liquid layer that is close to the critical temperature at the time of the beginning of the large mass ejection is representative of the crater depth at the threshold irradiance. These results suggest that phase explosion is a plausible thermal

arXiv Initial Conditions for Critical Higgs Inflation

CERN Document Server

Salvio, Alberto

2018-05-10

It has been pointed out that a large non-minimal coupling ξ between the Higgs and the Ricci scalar can source higher derivative operators, which may change the predictions of Higgs inflation. A variant, called critical Higgs inflation, employs the near-criticality of the top mass to introduce an inflection point in the potential and lower drastically the value of ξ . We here study whether critical Higgs inflation can occur even if the pre-inflationary initial conditions do not satisfy the slow-roll behavior (retaining translation and rotation symmetries). A positive answer is found: inflation turns out to be an attractor and therefore no fine-tuning of the initial conditions is necessary. A very large initial Higgs time-derivative (as compared to the potential energy density) is compensated by a moderate increase in the initial field value. These conclusions are reached by solving the exact Higgs equation without using the slow-roll approximation. This also allows us to consistently treat the inflection poi...

Reaching the Unreached - Special Emphasis on the Communication ...

African Journals Online (AJOL)

This paper provides an overview of the existing communication component in the Expanded Program on Immunisation (EPI) training in Zambia and critically analyses the need for a humane touch in the communication process so as to reach the target audience effectively. Interpersonal Communication (IPC) in Zambia has ...

Critical masses of bare homogeneous spherical UO2-water mixtures at intermediate enrichments

International Nuclear Information System (INIS)

Rendon, G.L.; Stratton, W.

1999-01-01

Critical masses of bare homogeneous spherical UO 2 -water mixtures at various intermediate fissile enrichments determined by multigroup, transport theory is presented. This work was performed to provide support for particular issues encountered by the nuclear industry when operating in the intermediate enrichment regime, namely, the validation of codes used to set criticality safety limits. Validation is normally performed with a comparison of computational results and applicable experiments. However, this may be difficult in some cases because of the lack of sufficient applicable experiments in the intermediate enrichment range. If a large extension of the area of applicability from an experiment to the desired application exists, then an alternative means for validation must be employed. Ideal interpretations of standard ANSI/ANS 8.1 Section 4.3 (1983) implies that perhaps an independent code and data system may be employed for validation purposes

Age-related effects of body mass on fertility and litter size in roe deer.

Science.gov (United States)

Flajšman, Katarina; Jerina, Klemen; Pokorny, Boštjan

2017-01-01

We analysed effects of females' body mass and age on reproductive capacity of European roe deer (Capreolus capreolus) in a large sample set of 1312 females (305 yearlings and 1007 adults), hunted throughout Slovenia, central Europe, in the period 2013-2015. Body mass positively affected probability of ovulation and potential litter size (number of corpora lutea), although its effect was more pronounced in yearlings than in adults. Between age groups, we found clear differences in responses of both reproductive parameters to body mass which influences primarily reproductive performance of younger, and in particular, lighter individuals: at the same body mass yearlings would at average have smaller litters than adults, and at lower body mass also young to middle-aged adults would have smaller litters than old ones. In addition, while yearlings have to reach a critical threshold body mass to attain reproductive maturity, adult females are fertile (produce ova) even at low body mass. However, at higher body mass also younger individuals shift their efforts into the reproduction, and after reaching an age-specific threshold the body mass does not have any further effects on the reproductive output of roe deer females. Increased reproductive capacity at more advanced age, combined with declining body mass suggests that old does allocate more of their resources in reproduction than in body condition.

Age-related effects of body mass on fertility and litter size in roe deer.

Directory of Open Access Journals (Sweden)

Katarina Flajšman

Full Text Available We analysed effects of females' body mass and age on reproductive capacity of European roe deer (Capreolus capreolus in a large sample set of 1312 females (305 yearlings and 1007 adults, hunted throughout Slovenia, central Europe, in the period 2013-2015. Body mass positively affected probability of ovulation and potential litter size (number of corpora lutea, although its effect was more pronounced in yearlings than in adults. Between age groups, we found clear differences in responses of both reproductive parameters to body mass which influences primarily reproductive performance of younger, and in particular, lighter individuals: at the same body mass yearlings would at average have smaller litters than adults, and at lower body mass also young to middle-aged adults would have smaller litters than old ones. In addition, while yearlings have to reach a critical threshold body mass to attain reproductive maturity, adult females are fertile (produce ova even at low body mass. However, at higher body mass also younger individuals shift their efforts into the reproduction, and after reaching an age-specific threshold the body mass does not have any further effects on the reproductive output of roe deer females. Increased reproductive capacity at more advanced age, combined with declining body mass suggests that old does allocate more of their resources in reproduction than in body condition.

Criticality safety

International Nuclear Information System (INIS)

Walker, G.

1983-01-01

When a sufficient quantity of fissile material is brought together a self-sustaining neutron chain reaction will be started in it and will continue until some change occurs in the fissile material to stop the chain reaction. The quantity of fissile material required is the 'Critical Mass'. This is not a fixed quantity even for a given type of fissile material but varies between quite wide limits depending on a number of factors. In a nuclear reactor the critical mass of fissile material is assembled under well-defined condition to produce a controllable chain reaction. The same materials have to be handled outside the reactor in all stages of fuel element manufacture, storage, transport and irradiated fuel reprocessing. At any stage it is possible (at least in principle) to assemble a critical mass and thus initiate an accidental and uncontrollable chain reaction. Avoiding this is what criticality safety is all about. A system is just critical when the rate of production of neutrons balances the rate of loss either by escape or by absorption. The factors affecting criticality are, therefore, those which effect neutron production and loss. The principal ones are:- type of nuclide and enrichment (or isotopic composition), moderation, reflection, concentration (density), shape and interaction. Each factor is considered in detail. (author)

Initial conditions for critical Higgs inflation

Science.gov (United States)

Salvio, Alberto

2018-05-01

It has been pointed out that a large non-minimal coupling ξ between the Higgs and the Ricci scalar can source higher derivative operators, which may change the predictions of Higgs inflation. A variant, called critical Higgs inflation, employs the near-criticality of the top mass to introduce an inflection point in the potential and lower drastically the value of ξ. We here study whether critical Higgs inflation can occur even if the pre-inflationary initial conditions do not satisfy the slow-roll behavior (retaining translation and rotation symmetries). A positive answer is found: inflation turns out to be an attractor and therefore no fine-tuning of the initial conditions is necessary. A very large initial Higgs time-derivative (as compared to the potential energy density) is compensated by a moderate increase in the initial field value. These conclusions are reached by solving the exact Higgs equation without using the slow-roll approximation. This also allows us to consistently treat the inflection point, where the standard slow-roll approximation breaks down. Here we make use of an approach that is independent of the UV completion of gravity, by taking initial conditions that always involve sub-planckian energies.

Reaching Agreement: The Structure & Pragmatics of Critical Care Nurses' Informal Argument

Science.gov (United States)

Hagler, Debra A.; Brem, Sarah K.

2008-01-01

The hospital critical care unit provides an authentic, high-stakes setting for studying reasoning, argumentation, and discourse. In particular, it allows examination of structural and pragmatic features of informal collaborative argument created while participants are engaged in familiar, meaningful activities central to their work. The nursing…

CORRELATION OF LOW BACK PAIN WITH BODY MASS INDEX, FUNCTIONAL REACH TEST AMONG FEMALE NURSING PROFESSIONALS

Directory of Open Access Journals (Sweden)

Shameela .T .V

2015-12-01

Full Text Available Background: Among health care workers the highest level of work related back injuries are more affected in nurses. There were many studies done to assess low back pain by using different tools. So this study aimed to identify the prevalence low back pain disability among female nursing professionals and the association between BMI, functional reach test and low back pain, so that a better tool can be used during the clinical examination for the betterment of the patient. The objective of the study is to identify the prevalence of low back pain disability, the association of Low Back Pain(LBP with BMI and functional reach test among female nursing professionals. Methods: A total of 256 subjects were assessed for disability due to back pain using OswestryLBP Disability Questionnaire and the prevalence of disability was determined. The sit and reach test, forward reach test and their BMI were calculated for those who had a disability score of 20 and above (n=87. Results: Data was analyzed using Pearson’s correlation.The study result showed a significant correlation (p=0.03 of sit and reach test with low back pain disability scores. There was a negative correlationseen among BMI and LBP disability score forward reach test and LBP disability score, and BMI and no low back pain disability score. Conclusion: The prevalence of LBP disability among nursing professionals was 33.9%. This study suggest that sit and reach test can be used as an indicator of low back pain. Whereas BMI and forward reach test do not indicate low back pain.

Critical Heat Flux Phenomena at HighPressure & Low Mass Fluxes: NEUP Final Report Part I: Experiments

Energy Technology Data Exchange (ETDEWEB)

Corradini, Michael [Univ. of Wisconsin, Madison, WI (United States); Wu, Qiao [Oregon State Univ., Corvallis, OR (United States)

2015-04-30

This report is a preliminary document presenting an overview of the Critical Heat Flux (CHF) phenomenon, the High Pressure Critical Heat Flux facility (HPCHF), preliminary CHF data acquired, and the future direction of the research. The HPCHF facility has been designed and built to study CHF at high pressure and low mass flux ranges in a rod bundle prototypical of conceptual Small Modular Reactor (SMR) designs. The rod bundle is comprised of four electrically heated rods in a 2x2 square rod bundle with a prototypic chopped-cosine axial power profile and equipped with thermocouples at various axial and circumferential positions embedded in each rod for CHF detection. Experimental test parameters for CHF detection range from pressures of ~80 – 160 bar, mass fluxes of ~400 – 1500 kg/m2s, and inlet water subcooling from ~30 – 70°C. The preliminary data base established will be further extended in the future along with comparisons to existing CHF correlations, models, etc. whose application ranges may be applicable to the conditions of SMRs.

Critical Participatory Looping: An Agencing Process for Mass Customization in Language Education

Directory of Open Access Journals (Sweden)

Tim Murphey

2012-01-01

Full Text Available Critical Participatory Looping (CPL (cf. Falout and Murphey 2010; Murphey and Falout 2010 involves returning processed data from surveys or assignments back to students for further reflection and analysis in small groups. CPL affords dialogical interaction among class members (including the teacher, which can encourage them all as agents developing their own self-determination through action—otherwise known as agencing (cf. Murphey 2010, Nelson and Murphey, 2011. In this paper we first describe the kinds of customization that invite agency, then for CPL provide three examples of teaching and researching with it, theorize on its processes and potential, and discuss its correlates with other domains and mass customization.

Critical mass analysis for 235U and 239Pu systems moderated and reflected by D2O

International Nuclear Information System (INIS)

Loaiza, D.; Stratton, W.

1998-01-01

Criticality dimensions for highly enriched 235 U (93.5) and 239 Pu (95.5) systems mixed with D 2 O were studied. The objective of this work is to investigate the minimum critical mass and concentration of uranium and plutonium systems in a reflector-moderated arrangement. The present work demonstrates the critical instability of some of these systems that are reflected by D 2 O and expands from previously published and unpublished work. These calculations were performed in a spherical geometry with the DANTSYS codes using the Hansen-Roach cross-section library. Densities examined ranged from normal to very small and are assumed to be uniform throughout the core. These spherical systems are reflected by 100 cm of D 2 O

Long-term modelling of nitrogen turnover and critical loads in a forested catchment using the INCA model

Directory of Open Access Journals (Sweden)

J.-J. Langusch

2002-01-01

Full Text Available Many forest ecosystems in Central Europe have reached the status of N saturation due to chronically high N deposition. In consequence, the NO3 leaching into ground- and surface waters is often substantial. Critical loads have been defined to abate the negative consequences of the NO3 leaching such as soil acidification and nutrient losses. The steady state mass balance method is normally used to calculate critical loads for N deposition in forest ecosystems. However, the steady state mass balance approach is limited because it does not take into account hydrology and the time until the steady state is reached. The aim of this study was to test the suitability of another approach: the dynamic model INCA (Integrated Nitrogen Model for European Catchments. Long-term effects of changing N deposition and critical loads for N were simulated using INCA for the Lehstenbach spruce catchment (Fichtelgebirge, NE Bavaria, Germany under different hydrological conditions. Long-term scenarios of either increasing or decreasing N deposition indicated that, in this catchment, the response of nitrate concentrations in runoff to changing N deposition is buffered by a large groundwater reservoir. The critical load simulated by the INCA model with respect to a nitrate concentration of 0.4 mg N l–1 as threshold value in runoff was 9.7 kg N ha–1yr–1 compared to 10 kg ha–1yr–1 for the steady state model. Under conditions of lower precipitation (520 mm the resulting critical load was 7.7 kg N ha–1yr–1 , suggesting the necessity to account for different hydrological conditions when calculating critical loads. The INCA model seems to be suitable to calculate critical loads for N in forested catchments under varying hydrological conditions e.g. as a consequence of climate change. Keywords: forest ecosystem, N saturation, critical load, modelling, long-term scenario, nitrate leaching, critical loads reduction, INCA

Critical behavior of the Higgs- and Goldstone-mass gaps for the two-dimensional S=1 XY model

Directory of Open Access Journals (Sweden)

Yoshihiro Nishiyama

2015-08-01

Full Text Available Spectral properties for the two-dimensional quantum S=1 XY model were investigated with the exact diagonalization method. In the symmetry-broken phase, there appear the massive Higgs and massless Goldstone excitations, which correspond to the longitudinal and transverse modes of the spontaneous magnetic moment, respectively. The former excitation branch is embedded in the continuum of the latter, and little attention has been paid to the details, particularly, in proximity to the critical point. The finite-size-scaling behavior is improved by extending the interaction parameters. An analysis of the critical amplitude ratio for these mass gaps is made.

Analysis on the Multiplication Factor with the Change of Corium Mass and Void Fraction

Energy Technology Data Exchange (ETDEWEB)

Jeong, Hae Sun; Park, Chang Je; Song, Jin Ho; Ha, Kwang Soon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-05-15

The neutron absorbing materials and fuel rods would be separately arranged and relocated, since the control materials in metallic structures have lower melting points than that of the oxide fuel (UO{sub 2}) rod materials. In addition, core reflood for a BWR is normally accomplished by supplying unborated water unlikely for a PWR. Therefore, a potential for a recriticality event to occur may exist, if unborated coolant injection is initiated with this configuration in the reactor core. The re-criticality in this system, however, brings into question what the uranium mass is required to achieve a critical level. Furthermore, the additional decay heat from molten fuel (corium) will produce an increase of void and eventually results in under-moderation of neutrons. The prior verification of these consequential physical variations in criticality eigenvalue (effective multiplication factor, k{sub eff}) should be greatly contributed to control and termination of re-criticality. Therefore, this study addresses what uranium mass of corium could achieve re-criticality of an accident core, and how effect the coolant void fraction has on eigenvalue (k{sub eff}) and its reactivity. To analyze the critical mass and the effect on criticality upon changing coolant density, k{sub eff} values were calculated using the MCNPX 2.5.0 code, and the reactivity change was also investigated. As a result, a large change in corium mass leads to a little change in k{sub eff} value, nevertheless, only about 60 kg of uranium is necessary to achieve a critical level. Thus, the amounts to reach a re-criticality are not fairly large, considering the actual uranium quantities loaded in the reactor core. Based on the condition with k{sub eff} greater than unity, the absolute values of k{sub eff} decrease rate and the coolant density coefficient were gradually increased due to the steady increments of coolant void (i.e., decrease in coolant density). In addition, the k{sub eff} value approaches the

Criticality of a 237Np sphere

International Nuclear Information System (INIS)

Sanchez, Rene G.; Loaiza, David J.; Kimpland, Robert H.; Hayes, David K.; Cappiello, Charlene C.; Myers, William L.; Jaegers, Peter J.; Clement, Steven D.; Butterfield, Kenneth B.

2003-01-01

A critical mass experiment using a 6-kg 237 Np sphere has been performed. The purpose of the experiment is to get a better estimate of the critical mass of 237 Np. To attain criticality, the 237 Np sphere was surrounded with 93 wt% 235 U shells. A 1/M as a function of uranium mass was performed. An MCNP neutron transport code was used to model the experiment. The MCNP code yielded a k eff of 0.99089 ± 0.0003 compared with a k eff 1.0026 for the experiment. Based on these results, it is estimated that the critical mass of 237 Np ranges from kilogram weights in the high fifties to low sixties. (author)

Critical Thresholds in Earth-System Dynamics

Science.gov (United States)

Rothman, D.

2017-12-01

The history of the Earth system is a story of change. Some changesare gradual and benign, but others, especially those associated withcatastrophic mass extinction, are relatively abrupt and destructive.What sets one group apart from the other? Here I hypothesize thatperturbations of Earth's carbon cycle lead to mass extinction if theyexceed either a critical rate at long time scales or a critical sizeat short time scales. By analyzing 31 carbon-isotopic events duringthe last 542 million years, I identify the critical rate with a limitimposed by mass conservation. Further analysis identifies thecrossover timescale separating fast from slow events with thetimescale of the ocean's homeostatic response to a change in pH. Theproduct of the critical rate and the crossover timescale then yieldsthe critical size. The modern critical size for the marine carboncycle is roughly similar to the mass of carbon that human activitieswill likely have added to the oceans by the year 2100.

Peak bone mineral density, lean body mass and fractures

NARCIS (Netherlands)

Boot, Annemieke M.; de Ridder, Maria A. J.; van der Sluis, Inge M.; van Slobbe, Ingrid; Krenning, Eric P.; Keizer-Schrama, Sabine M. P. F. de Muinck

Background: During childhood and adolescence, bone mass and lean body mass (LBM) increase till a plateau is reached. In this longitudinal and cross-sectional study, the age of reaching the plateau was evaluated for lumbar spine and total body bone mass measurements and lean body mass. The

Critical Mass has become a tradition for the Bike2Work campaign at CERN

CERN Multimedia

2018-01-01

Critical Mass is a cycling event typically held on the last Friday of every month; its purpose is not usually formalized beyond the direct action of meeting at a set location and time and traveling as a group through city or town streets on bikes. The event originated in 1992 in San Francisco; by the end of 2003, the event was being held in over 300 cities around the world. At CERN it is held once a year in conjunction with the national Swiss campaing "Bike to work".

Effect of viewing angle on arm reaching while standing in a virtual environment: potential for virtual rehabilitation.

Science.gov (United States)

Ustinova, K I; Perkins, J; Szostakowski, L; Tamkei, L S; Leonard, W A

2010-02-01

Functional arm movements, such as reaching while standing, are planned and executed according to our perception of body position in space and are relative to environmental objects. The angle under which the environment is observed is one component used in creating this perception. This suggests that manipulation of viewing angle may modulate whole body movement to affect performance. We tested this by comparing its effect on reaching in a virtually generated environment. Eleven young healthy individuals performed forward and lateral reaches in the virtual environment, presented on a flat screen in third-person perspective. Participants saw a computer-generated model (avatar) of themselves standing in a courtyard facing a semi-circular hedge with flowers. The image was presented in five different viewing angles ranging from seeing the avatar from behind (0 degrees), to viewing from overhead (90 degrees). Participants attempted to touch the furthest flower possible without losing balance or stepping. Kinematic data were collected to analyze endpoint displacement, arm-postural coordination and center of mass (COM) displacement. Results showed that reach distance was greatest with angular perspectives of approximately 45-77.5 degrees , which are larger than those used in analogous real world situations. Larger reaches were characterized by increased involvement of leg and trunk body segments, altered inter-segmental coordination, and decreased inter-segmental movement time lag. Thus a viewing angle can be a critical visuomotor variable modulating motor coordination of the whole body and related functional performance. These results can be used in designing virtual reality games, in ergonomic design, teleoperation training, and in designing virtual rehabilitation programs that re-train functional movement in vulnerable individuals. Copyright 2009 Elsevier B.V. All rights reserved.

Reaching the hard-to-reach.

Science.gov (United States)

Valdes, C

1992-01-01

Guatemala's family planning (FP) programs are innovative but contraceptive use is only 23%. Total fertility is 5.3 children/woman, and the 9.5 million population will double in 23 years. The problem is poverty and illiteracy among rural residents removed from health services. 80% live in poverty and 80% are illiterate. Government effort is devoted to combating diseases such as diarrhea so there are few funds for implementing a comprehensive population policy. There is support within the national government but FP lacks priority status. APROFAM's goals are to use innovative marketing methods to inform the rural population who lack access to and knowledge about FP. Service delivery is constrained by the difficulty in reaching remote areas where 4 out of 10 indigenous Guatemalans live. Infant mortality can reach as high as 200/1000 live births. Population growth has slowed, and APROFAM plans to reach 16,000 more in the future. Promotions are conducted in several languages and aired on radio, television, and in the print media. It has been found that market research is the most effective strategy in reaching indigenous families. APROFAM has also been effective in upgrading service facilities through training, client surveys, and setting improved clinic standards. Breastfeeding, training, and voluntary sterilization programs contribute to the primary care effort. The example is given of Paulina Lebron from a very poor area who has learned how to space her children and thus improve the standard of living for her family. Eventually, she convinced herself and her family that sterilization was necessary, and now the couple enjoy the bliss of newlyweds without fear of pregnancy.

Nitrogen critical loads using biodiversity-related critical limits

International Nuclear Information System (INIS)

Posch, Maximilian; Aherne, Julian; Hettelingh, Jean-Paul

2011-01-01

Critical loads are widely used in the effects-based assessment of emission reduction policies. While the impacts of acidification have diminished, there is increasing concern regarding the effects of nitrogen deposition on terrestrial ecosystems. In this context much attention has been focussed on empirical critical loads as well as simulations with linked geochemistry-vegetation models. Surprisingly little attention has been paid to adapt the widely used simple mass balance approach. This approach has the well-established benefit of easy regional applicability, while incorporating specified critical chemical criteria to protect specified receptors. As plant occurrence/biodiversity is related to both the nutrient and acidity status of an ecosystem, a single abiotic factor (chemical criterion) is not sufficient. Rather than an upper limit for deposition (i.e., critical load), linked nutrient nitrogen and acidity chemical criteria for plant occurrence result in an 'optimal' nitrogen and sulphur deposition envelope. - Highlights: → Mass balance critical load approaches for nutrient nitrogen remain useful. → Biodiversity-related limits are related to nutrient and acidity status. → Nutrient and acidity chemical criteria lead to optimal deposition envelopes. → Optimal loads support effects-based emission reduction policies. - Biodiversity-related critical limits lead to optimal nitrogen and sulphur deposition envelopes for plant species or species compositions.

Control of criticality; Kawalan kegentingan

Energy Technology Data Exchange (ETDEWEB)

NONE

1988-12-31

The chapter briefly discussed the following subjects: basic and the principle of criticality, natural uranium, neutron utilization, criticality data for systems, criticality accidents, criticality control i.e. mass, volume and geometry control .

Critical incidents and critical incident stress management (CISM) - an employee assistance programme (EAP) perspective

OpenAIRE

Terblanche, Lourie; van Wyk, André

2014-01-01

Employees are increasingly becoming victims of critical incidents. From a systems theory point of view, it is necessary to acknowledge the impact of critical incidents not only on the personal life of the employee, but on the workplace itself. Employees respond differently to critical incidents, which makes it even more complicated when this reaches the point of requiring therapeutic intervention. The most common response to critical incidents may be the risk of developing post-traumatic s...

Limit behavior of mass critical Hartree minimization problems with steep potential wells

Science.gov (United States)

Guo, Yujin; Luo, Yong; Wang, Zhi-Qiang

2018-06-01

We consider minimizers of the following mass critical Hartree minimization problem: eλ(N ) ≔inf {u ∈H1(Rd ) , ‖u‖2 2=N } Eλ(u ) , where d ≥ 3, λ > 0, and the Hartree energy functional Eλ(u) is defined by Eλ(u ) ≔∫Rd|∇u (x ) |2d x +λ ∫Rdg (x ) u2(x ) d x -1/2 ∫Rd∫Rdu/2(x ) u2(y ) |x -y |2 d x d y . Here the steep potential g(x) satisfies 0 =g (0 ) =infRdg (x ) ≤g (x ) ≤1 and 1 -g (x ) ∈Ld/2(Rd ) . We prove that there exists a constant N* > 0, independent of λg(x), such that if N ≥ N*, then eλ(N) does not admit minimizers for any λ > 0; if 0 N N*, then there exists a constant λ*(N) > 0 such that eλ(N) admits minimizers for any λ > λ*(N) and eλ(N) does not admit minimizers for 0 N). For any given 0 N N*, the limit behavior of positive minimizers for eλ(N) is also studied as λ → ∞, where the mass concentrates at the bottom of g(x).

Effects of turbulent hyporheic mixing on reach-scale solute transport

Science.gov (United States)

Roche, K. R.; Li, A.; Packman, A. I.

2017-12-01

Turbulence rapidly mixes solutes and fine particles into coarse-grained streambeds. Both hyporheic exchange rates and spatial variability of hyporheic mixing are known to be controlled by turbulence, but it is unclear how turbulent mixing influences mass transport at the scale of stream reaches. We used a process-based particle-tracking model to simulate local- and reach-scale solute transport for a coarse-bed stream. Two vertical mixing profiles, one with a smooth transition from in-stream to hyporheic transport conditions and a second with enhanced turbulent transport at the sediment-water interface, were fit to steady-state subsurface concentration profiles observed in laboratory experiments. The mixing profile with enhanced interfacial transport better matched the observed concentration profiles and overall mass retention in the streambed. The best-fit mixing profiles were then used to simulate upscaled solute transport in a stream. Enhanced mixing coupled in-stream and hyporheic solute transport, causing solutes exchanged into the shallow subsurface to have travel times similar to the water column. This extended the exponential region of the in-stream solute breakthrough curve, and delayed the onset of the heavy power-law tailing induced by deeper and slower hyporheic porewater velocities. Slopes of observed power-law tails were greater than those predicted from stochastic transport theory, and also changed in time. In addition, rapid hyporheic transport velocities truncated the hyporheic residence time distribution by causing mass to exit the stream reach via subsurface advection, yielding strong exponential tempering in the in-stream breakthrough curves at the timescale of advective hyporheic transport through the reach. These results show that strong turbulent mixing across the sediment-water interface violates the conventional separation of surface and subsurface flows used in current models for solute transport in rivers. Instead, the full distribution of

Simulating at realistic quark masses. Light quark masses

International Nuclear Information System (INIS)

Goeckeler, M.; Streuer, T.

2006-11-01

We present new results for light quark masses. The calculations are performed using two flavours of O(a) improved Wilson fermions. We have reached lattice spacings as small as a ∝0.07 fm and pion masses down to m π ∝340 MeV in our simulations. This gives us significantly better control on the chiral and continuum extrapolations. (orig.)

Gluino reach and mass extraction at the LHC in radiatively-driven natural SUSY

Energy Technology Data Exchange (ETDEWEB)

Baer, Howard; Savoy, Michael; Sengupta, Dibyashree [University of Oklahoma, Department of Physics and Astronomy, Norman, OK (United States); Barger, Vernon [University of Wisconsin, Department of Physics, Madison, WI (United States); Gainer, James S.; Tata, Xerxes [University of Hawaii, Department of Physics and Astronomy, Honolulu, HI (United States); Huang, Peisi [University of Chicago, Enrico Fermi Institute, Chicago, IL (United States); HEP Division, Argonne National Laboratory, Argonne, IL (United States); Texas A and M University, Mitchell Institute for Fundamental Physics and Astronomy, College Station, TX (United States)

2017-07-15

Radiatively-driven natural SUSY (RNS) models enjoy electroweak naturalness at the 10% level while respecting LHC sparticle and Higgs mass constraints. Gluino and top-squark masses can range up to several TeV (with other squarks even heavier) but a set of light Higgsinos are required with mass not too far above m{sub h} ∝ 125 GeV. Within the RNS framework, gluinos dominantly decay via g → tt{sub 1}{sup *}, anti tt{sub 1} → t anti tZ{sub 1,2} or t anti bW{sub 1}{sup -} + c.c., where the decay products of the higgsino-like W{sub 1} and Z{sub 2} are very soft. Gluino pair production is, therefore, signaled by events with up to four hard b-jets and large E{sub T}. We devise a set of cuts to isolate a relatively pure gluino sample at the (high-luminosity) LHC and show that in the RNS model with very heavy squarks, the gluino signal will be accessible for m{sub g} < 2400 (2800) GeV for an integrated luminosity of 300 (3000) fb{sup -1}. We also show that the measurement of the rate of gluino events in the clean sample mentioned above allows for a determination of m{sub g} with a statistical precision of 2-5% (depending on the integrated luminosity and the gluino mass) over the range of gluino masses where a 5σ discovery is possible at the LHC. (orig.)

Reach-to-grasp movement as a minimization process.

Science.gov (United States)

Yang, Fang; Feldman, Anatol G

2010-02-01

It is known that hand transport and grasping are functionally different but spatially coordinated components of reach-to-grasp (RTG) movements. As an extension of this notion, we suggested that body segments involved in RTG movements are controlled as a coherent ensemble by a global minimization process associated with the necessity for the hand to reach the motor goal. Different RTG components emerge following this process without pre-programming. Specifically, the minimization process may result from the tendency of neuromuscular elements to diminish the spatial gap between the actual arm-hand configuration and its virtual (referent) configuration specified by the brain. The referent configuration is specified depending on the object shape, localization, and orientation. Since the minimization process is gradual, it can be interrupted and resumed following mechanical perturbations, at any phase during RTG movements, including hand closure. To test this prediction of the minimization hypothesis, we asked subjects to reach and grasp a cube placed within the reach of the arm. Vision was prevented during movement until the hand returned to its initial position. As predicted, by arresting wrist motion at different points of hand transport in randomly selected trials, it was possible to halt changes in hand aperture at any phase, not only during hand opening but also during hand closure. Aperture changes resumed soon after the wrist was released. Another test of the minimization hypothesis was made in RTG movements to an object placed beyond the reach of the arm. It has previously been shown (Rossi et al. in J Physiol 538:659-671, 2002) that in such movements, the trunk motion begins to contribute to hand transport only after a critical phase when the shifts in the referent arm configuration have finished (at about the time when hand velocity is maximal). The minimization rule suggests that when the virtual contribution of the arm to hand transport is completed

Simulating at realistic quark masses. Light quark masses

Energy Technology Data Exchange (ETDEWEB)

Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik; Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics; Nakamura, Y.; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Streuer, T. [Kentucky Univ., Lexington, KY (United States). Dept. of Physics and Astronomy; Stueben, H. [Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB) (Germany)

2006-11-15

We present new results for light quark masses. The calculations are performed using two flavours of O(a) improved Wilson fermions. We have reached lattice spacings as small as a {proportional_to}0.07 fm and pion masses down to m{sub {pi}} {proportional_to}340 MeV in our simulations. This gives us significantly better control on the chiral and continuum extrapolations. (orig.)

Body mass index during adolescence, rather than childhood, is critical in determining MS risk.

Science.gov (United States)

Hedström, A K; Olsson, T; Alfredsson, L

2016-06-01

Obesity in childhood and during adolescence has repeatedly been associated with increased risk of developing multiple sclerosis (MS). We aimed to investigate whether the most critical period occurs during childhood or later, during adolescence. Using a population-based case-control study (1586 cases and 2800 controls), individuals with different body sizes at age 10 and different body mass indices at age 20 were compared regarding MS risk, by calculating odds ratios with 95% confidence intervals. Potential interactions between HLA-DRB1*15 and absence of HLA-A*02, respectively, and both childhood and adolescent obesity were evaluated by calculating the attributable proportion due to interaction. Regardless of body size at age 10, individuals with adolescent obesity had a 90% increased risk of MS. Among participants who were not obese at age 20, no association was observed between body size at age 10 and subsequent MS risk. An interaction was observed between the HLA MS risk genes and adolescent, but not childhood, obesity. Our results suggest that BMI during adolescence, rather than childhood, is critical in determining MS risk. © The Author(s), 2015.

Criticality safety (prospect of study in NUCEF)

International Nuclear Information System (INIS)

Itagaki, Masafumi

1996-01-01

Experimental studies of criticality safety are under way using STACY and TRACY in NUCEF. Collection of fundamental data on criticality in a solution system is undergoing with STACY to confirm that the likelihood of criticality safety in the system constructed on the assumption of apparatuses in a reprocessing plant is enough large. Whereas some experiments simulating criticality accidents in a reprocessing plant using TRACY were designed to investigate the behaviors of fuel solution and radioactive matters in order to clarify whether it is possible to safely shut them in the facility even if a critical accident occurs. Both STACY and TRACY reached the criticality in 1995. Up to now a series of criticality experiments have been done using STACY with a core tank φ60 cm and the first periodical examination is now under way. On the other hand, we have a plan using TRACY to investigate the behaviors of nuclear heat solution at a criticality accident, and the releasing, transfer and deposition of radioactive materials. After reaching the criticality for the first, the performance verification test has been conducted. The full-scale study using TRACY is planned to begin in the second half of 1996. (M.N.)

Criticality Analysis of SAMOP Subcritical Assembly

International Nuclear Information System (INIS)

Tegas-Sutondo; Syarip; Triwulan-Tjiptono

2005-01-01

A critically analysis has been performed for homogenous system of uranyl nitrate solution, as part of a preliminary design assessment on neutronic aspect of SAMOP sub-critical assembly. The analysis is intended to determine some critical parameters such as the minimum of critical dimension and critical mass for the desired concentration. As the basis of this analysis, it has been defined a fuel system with an enrichment of 20% for cylindrical geometry of both bare and graphite reflected of 30 cm thickness. The MCNP code has been utilized for this purpose, for variation of concentrations ranging from 150 g/l to 500 g/l. It is found that the best concentration giving the minimum geometrical dimension is around 400 g/l, for both the bare and reflected systems. Whilst the best one, of minimum critical mass is corresponding to the concentration of around 200 g/l with critical mass around 14.1 kg and 4.2 kg for the bare and reflected systems respectively. Based on the result of calculations, it is concluded that by taking into consideration of the critical limit, the SAMOP subcritical assembly is neutronically can be made. (author)

Critical and subcritical mass calculations of curium-243 to -247 based on JENDL-3.2 for revision of ANSI/ANS-8.15

International Nuclear Information System (INIS)

Okuno, Hiroshi

2002-01-01

Critical and subcritical masses were calculated for a sphere of five curium isotopes from 243 Cm to 247 Cm in metal and in metal-water mixtures considering three reflector conditions: bare, with a water reflector or a stainless steel reflector. The calculation were made mainly with a combination of a continuous energy Monte Carlo neutron transport calculation code, MCNP, and the Japanese Evaluated Nuclear Data Library, JENDL-3.2. Other evaluated nuclear data files, ENDF/B-VI and JEF-2.2, were also applied to find differences in calculation results of the neutron multiplication factor originated from different nuclear data files. A large dependence on the evaluated nuclear data files was found in the calculation results: more than 10%Δk/k relative differences in the neutron multiplication factor for a homogeneous mixture of 243 Cm metal and water when JENDL-3.2 was replaced with ENDF/B-VI and JEF-2.2, respectively; and a 44% reduction in the critical mass by changing from JENDL-3.2 to ENDF/B-VI for 246 Cm metal. The present study supplied basic information to the ANSI/ANS-8.15 Working Group for revision of the standard for nuclear criticality control of special actinide elements. The new or revised values of the subcritical mass limits for curium isotopes accepted by the ANSI/ANS-8.15 Working Group were finally summarized. (author)

Storage of plutonium and nuclear power plant actinide waste in the form of critical-mass-free ceramics containing neutron poisons

Energy Technology Data Exchange (ETDEWEB)

Nadykto, B.A. [RFNC-VNIIEF, Nizhni Novgorod Region (Russian Federation)

2001-07-01

The nuclear weapons production has resulted in accumulation of a large quantity of plutonium and uranium highly enriched with uranium-235 isotope (many tons). The work under ISTC Project 332B-97 treated the issues of safe plutonium storage through making critical-mass-free plutonium oxide compositions with neutron poisons. This completely excludes immediate utilization (without chemical reprocessing) of retained plutonium in nuclear devices. It is therewith possible to locate plutonium most compactly in the storage facility, which would allow reduction in required storage areas and costs. The issues of the surplus weapon-grade plutonium management and utilization have been comprehensively studied in the recent decade. The issues are treated in multiple scientific publications, conferences, and seminars. At the same time, issues of nuclear power engineering actinide waste storage are studied no less extensively. The general issues are material radioactivity and energy release and nuclear accident hazards due to critical mass generation. Plutonium accumulated in nuclear power plant spent fuel is more accessible than weapon-grade plutonium and can become of higher and higher interest with time as its activity reduces, including as material for nuclear devices. The urgency of plutonium management is presently related not only to accumulation of surplus weapon-grade plutonium, but also to the fact that it is high time to decide what has to be done regarding reactor plutonium. Presently, the possibility of actinide separation from NPP spent nuclear fuel and compact underground burial separately from other (mainly fragment) activity is being considered. Actinide and neutron poison base critical-mass-free ceramic materials (similar to plutonium ceramics) may be useful for this burial method. (author)

Storage of plutonium and nuclear power plant actinide waste in the form of critical-mass-free ceramics containing neutron poisons

International Nuclear Information System (INIS)

Nadykto, B.A.

2001-01-01

The nuclear weapons production has resulted in accumulation of a large quantity of plutonium and uranium highly enriched with uranium-235 isotope (many tons). The work under ISTC Project 332B-97 treated the issues of safe plutonium storage through making critical-mass-free plutonium oxide compositions with neutron poisons. This completely excludes immediate utilization (without chemical reprocessing) of retained plutonium in nuclear devices. It is therewith possible to locate plutonium most compactly in the storage facility, which would allow reduction in required storage areas and costs. The issues of the surplus weapon-grade plutonium management and utilization have been comprehensively studied in the recent decade. The issues are treated in multiple scientific publications, conferences, and seminars. At the same time, issues of nuclear power engineering actinide waste storage are studied no less extensively. The general issues are material radioactivity and energy release and nuclear accident hazards due to critical mass generation. Plutonium accumulated in nuclear power plant spent fuel is more accessible than weapon-grade plutonium and can become of higher and higher interest with time as its activity reduces, including as material for nuclear devices. The urgency of plutonium management is presently related not only to accumulation of surplus weapon-grade plutonium, but also to the fact that it is high time to decide what has to be done regarding reactor plutonium. Presently, the possibility of actinide separation from NPP spent nuclear fuel and compact underground burial separately from other (mainly fragment) activity is being considered. Actinide and neutron poison base critical-mass-free ceramic materials (similar to plutonium ceramics) may be useful for this burial method. (author)

Criticality alarm device

International Nuclear Information System (INIS)

Kasai, Kenji.

1994-01-01

The device of the present invention is utilized, for example, to a reprocessing facility for storing and processing nuclear fuels and measures and controls the nuclear fuel assembly system so as not to exceed criticality. That is, a conventional criticality alarm device applies a predetermined processing to neutron fluxes generated from a nuclear fuel assembly system containing nuclear fuels and outputs an alarm. The device of the present invention comprises (1) a neutron flux supply source for increasing and decreasing neutron fluxes periodically and supplying them to nuclear fuel assemblies, (2) a detector for detecting neutron fluxes in the nuclear fuel assemblies, (3) a critical state judging section for judging the critical state of the nuclear fuel assemblies based on the periodically changing signals obtained from the detector (2) and (4) an alarm section for outputting criticality alarms depending on the result of the judgement. The device of the present invention can accurately recognize the critical state of the nuclear fuel assembly system and can forecast reaching of the nuclear fuel assembly to criticality or prompt neutron critical state. (I.S.)

Optimizing EDELWEISS detectors for low-mass WIMP searches

Science.gov (United States)

Arnaud, Q.; Armengaud, E.; Augier, C.; Benoît, A.; Bergé, L.; Billard, J.; Broniatowski, A.; Camus, P.; Cazes, A.; Chapellier, M.; Charlieux, F.; de Jésus, M.; Dumoulin, L.; Eitel, K.; Foerster, N.; Gascon, J.; Giuliani, A.; Gros, M.; Hehn, L.; Jin, Y.; Juillard, A.; Kleifges, M.; Kozlov, V.; Kraus, H.; Kudryavtsev, V. A.; Le-Sueur, H.; Maisonobe, R.; Marnieros, S.; Navick, X.-F.; Nones, C.; Olivieri, E.; Pari, P.; Paul, B.; Poda, D.; Queguiner, E.; Rozov, S.; Sanglard, V.; Scorza, S.; Siebenborn, B.; Vagneron, L.; Weber, M.; Yakushev, E.; EDELWEISS Collaboration

2018-01-01

The physics potential of EDELWEISS detectors for the search of low-mass weakly interacting massive particles (WIMPs) is studied. Using a data-driven background model, projected exclusion limits are computed using frequentist and multivariate analysis approaches, namely, profile likelihood and boosted decision tree. Both current and achievable experimental performances are considered. The optimal strategy for detector optimization depends critically on whether the emphasis is put on WIMP masses below or above ˜5 GeV /c2 . The projected sensitivity for the next phase of the EDELWEISS-III experiment at the Modane Underground Laboratory (LSM) for low-mass WIMP search is presented. By 2018 an upper limit on the spin-independent WIMP-nucleon cross section of σSI=7 ×10-42 cm2 is expected for a WIMP mass in the range 2 - 5 GeV /c2 . The requirements for a future hundred-kilogram-scale experiment designed to reach the bounds imposed by the coherent scattering of solar neutrinos are also described. By improving the ionization resolution down to 50 eVe e , we show that such an experiment installed in an even lower background environment (e.g., at SNOLAB) together with an exposure of 1 000 kg .yr , should allow us to observe about 80 B 8 neutrino events after discrimination.

QCD and the chiral critical point

International Nuclear Information System (INIS)

Gavin, S.; Gocksch, A.; Pisarski, R.D.

1994-01-01

As an extension of QCD, consider a theory with ''2+1'' flavors, where the current quark masses are held in a fixed ratio as the overall scale of the quark masses is varied. At nonzero temperature and baryon density it is expected that in the chiral limit the chiral phase transition is of first order. Increasing the quark mass from zero, the chiral transition becomes more weakly first order, and can end in a chiral critical point. We show that the only massless field at the chiral critical point is a σ meson, with the universality class that of the Ising model. Present day lattice simulations indicate that QCD is (relatively) near to the chiral critical point

Critical and subcritical mass calculations of curium-243 to -247 based on JENDL-3.2 for revision of ANSI/ANS-8.15

Energy Technology Data Exchange (ETDEWEB)

Okuno, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kawasaki, Hiromitsu [CRC Solutions Corporation, Hitachinaka, Ibaraki (Japan)

2002-10-01

Critical and subcritical masses were calculated for a sphere of five curium isotopes from {sup 243}Cm to {sup 247}Cm in metal and in metal-water mixtures considering three reflector conditions: bare, with a water reflector or a stainless steel reflector. The calculation were made mainly with a combination of a continuous energy Monte Carlo neutron transport calculation code, MCNP, and the Japanese Evaluated Nuclear Data Library, JENDL-3.2. Other evaluated nuclear data files, ENDF/B-VI and JEF-2.2, were also applied to find differences in calculation results of the neutron multiplication factor originated from different nuclear data files. A large dependence on the evaluated nuclear data files was found in the calculation results: more than 10%{delta}k/k relative differences in the neutron multiplication factor for a homogeneous mixture of {sup 243}Cm metal and water when JENDL-3.2 was replaced with ENDF/B-VI and JEF-2.2, respectively; and a 44% reduction in the critical mass by changing from JENDL-3.2 to ENDF/B-VI for {sup 246}Cm metal. The present study supplied basic information to the ANSI/ANS-8.15 Working Group for revision of the standard for nuclear criticality control of special actinide elements. The new or revised values of the subcritical mass limits for curium isotopes accepted by the ANSI/ANS-8.15 Working Group were finally summarized. (author)

Extending Particle Swarm Optimisers with Self-Organized Criticality

DEFF Research Database (Denmark)

Løvbjerg, Morten; Krink, Thiemo

2002-01-01

Particle swarm optimisers (PSOs) show potential in function optimisation, but still have room for improvement. Self-organized criticality (SOC) can help control the PSO and add diversity. Extending the PSO with SOC seems promising reaching faster convergence and better solutions.......Particle swarm optimisers (PSOs) show potential in function optimisation, but still have room for improvement. Self-organized criticality (SOC) can help control the PSO and add diversity. Extending the PSO with SOC seems promising reaching faster convergence and better solutions....

Safety analysis report for the Hanford Critical Mass Laboratory: Supplement No. 2. Experiments with heterogeneous assemblies

International Nuclear Information System (INIS)

Gore, B.F.; Davenport, L.C.

1981-04-01

Factors affecting the safety of criticality experiments using heterogeneous assemblies are described and assessed. It is concluded that there is no substantial change in safety from experiments already being routinely performed at the Critical Mass Laboratory (CML), and that laboratory and personnel safety are adequately provided by the combination of engineered and administrative safety limits enforced at the CML. This conclusion is based on the analysis of operational controls, potential hazards, and the consequences of accidents. Contingencies considered that could affect nuclear criticality include manual changes in fuel loadings, water flooding, fire, explosion, loss of services, earthquake, windstorm, and flood. Other potential hazards considered include radiation exposure to personnel, and potential releases within the Assembly Room and outside to the environment. It is concluded that the Maximum Credible Nuclear Burst of 3 x 10 18 fissions (which served as the design basis for the CML) is valid for heterogeneous assemblies as well as homogeneous assemblies. This is based upon examination of the results of reactor destructive tests and the results of the SL-1 reactor destructive accident. The production of blast effects which might jeopardize the CML critical assembly room (of thick reinforced concrete) is not considered credible due to the extreme circumstances required to produce blast effects in reactor destructive tests. Consequently, it is concluded that, for experiments with heterogeneous assemblies, the consequences of the Maximum Credible Burst are unchanged from those previously estimated for experiments with homogeneous systems

CRITICAL INCIDENTS AND CRITICAL INCIDENT STRESS MANAGEMENT (CISM – AN EMPLOYEE ASSISTANCE PROGRAMME (EAP PERSPECTIVE

Directory of Open Access Journals (Sweden)

Terblanche, Lourie

2014-04-01

Full Text Available Employees are increasingly becoming victims of critical incidents. From a systems theory point of view, it is necessary to acknowledge the impact of critical incidents not only on the personal life of the employee, but on the workplace itself. Employees respond differently to critical incidents, which makes it even more complicated when this reaches the point of requiring therapeutic intervention. The most common response to critical incidents may be the risk of developing post-traumatic stress disorder (PTSD and/or depression. This reality requires management – through the Employee Assistance Programme (EAP – to be able to effectively deal with such critical incidents.

Cosmological and astrophysical neutrino mass measurements

DEFF Research Database (Denmark)

Abazajian, K.N.; Calabrese, E.; Cooray, A.

2011-01-01

Cosmological and astrophysical measurements provide powerful constraints on neutrino masses complementary to those from accelerators and reactors. Here we provide a guide to these different probes, for each explaining its physical basis, underlying assumptions, current and future reach.......Cosmological and astrophysical measurements provide powerful constraints on neutrino masses complementary to those from accelerators and reactors. Here we provide a guide to these different probes, for each explaining its physical basis, underlying assumptions, current and future reach....

Usefulness of the jump-and-reach test in assessment of vertical jump performance.

Science.gov (United States)

Menzel, Hans-Joachim; Chagas, Mauro H; Szmuchrowski, Leszek A; Araujo, Silvia R; Campos, Carlos E; Giannetti, Marcus R

2010-02-01

The objective was to estimate the reliability and criterion-related validity of the Jump-and-Reach Test for the assessment of squat, countermovement, and drop jump performance of 32 male Brazilian professional volleyball players. Performance of squat, countermovement, and drop jumps with different dropping heights was assessed on the Jump-and-Reach Test and the measurement of flight time, then compared across different jump trials. The very high reliability coefficients of both assessment methods and the lower correlation coefficients between scores on the assessments indicate a very high consistency of each method but only moderate covariation, which means that they measure partly different items. As a consequence, the Jump-and-Reach Test has good ecological validity in situations when reaching height during the flight phase is critical for performance (e.g., basketball and volleyball) but only limited accuracy for the assessment of vertical impulse production with different jump techniques and conditions.

Basin Visual Estimation Technique (BVET) and Representative Reach Approaches to Wadeable Stream Surveys: Methodological Limitations and Future Directions

Science.gov (United States)

Lance R. Williams; Melvin L. Warren; Susan B. Adams; Joseph L. Arvai; Christopher M. Taylor

2004-01-01

Basin Visual Estimation Techniques (BVET) are used to estimate abundance for fish populations in small streams. With BVET, independent samples are drawn from natural habitat units in the stream rather than sampling "representative reaches." This sampling protocol provides an alternative to traditional reach-level surveys, which are criticized for their lack...

Critical Foundations: Protecting America's Infrastructures. The Report of the President's Commission on Critical Infrastructure Protection

National Research Council Canada - National Science Library

1997-01-01

There is no doubt that our critical infrastructures are the best in the world-largely the result of the tremendous efficiency and global reach made possible by incorporation of our rapidly advancing...

UBVRc Ic ANALYSIS OF THE RECENTLY DISCOVERED TOTALLY ECLIPSING EXTREME MASS RATIO BINARY V1853 ORIONIS, AND A STATISTICAL LOOK AT 25 OTHER EXTREME MASS RATIO SOLAR-TYPE CONTACT BINARIES

International Nuclear Information System (INIS)

Samec, R. G.; Labadorf, C. M.; Hawkins, N. C.; Faulkner, D. R.; Van Hamme, W.

2011-01-01

We present precision CCD light curves, a period study, photometrically derived standard magnitudes, and a five-color simultaneous Wilson code solution of the totally eclipsing, yet shallow amplitude (A v ∼ 0.4 mag) eclipsing, binary V1853 Orionis. It is determined to be an extreme mass ratio, q = 0.20, W-type W UMa overcontact binary. From our standard star observations, we find that the variable is a late-type F spectral-type dwarf, with a secondary component of about 0.24 solar masses (stellar type M5V). Its long eclipse duration (41 minutes) as compared to its period, 0.383 days, attests to the small relative size of the secondary. Furthermore, it has reached a Roche lobe fill-out of ∼50% of its outer critical lobe as it approaches its final stages of binary star evolution, that of a fast spinning single star. Finally, a summary of about 25 extreme mass ratio solar-type binaries is given.

Acceleration and increased control of convergence in criticality calculations

International Nuclear Information System (INIS)

Jinaphanh, Alexis

2014-01-01

IRSN is developing a numerical simulation code called Moret to assess the nuclear criticality risk. This tool is designed to perform 3D simulations of neutron transport in a given system. It achieves this by adopting a probabilistic approach known as Monte Carlo, in which the transport of several successive generations of neutrons is calculated from an initial neutron distribution in the system under study. These generations are simulated until it is considered that convergence of the effective neutron multiplication coefficient (or K eff ) - which characterizes the gap before reaching the critical state - has been reached. Insufficient convergence can lead to underestimation of both K eff and the criticality risk. During this thesis work, A. Jinaphanh sought to improve the reliability of values by developing a new method for initializing calculations, together with a criterion used to reliably determine whether or not convergence has been reached. (author)

Systematics of criticality data of special actinide nuclides deduced through the Trombay criticality formula

International Nuclear Information System (INIS)

Srinivasan, M.; SubbaRao, K.; Garg, S.B.; Acharya, G.V.

1989-01-01

The authors describe a number of interesting systematics and correlations deduced by analyzing the criticality data of special actinide nuclides using concepts embodied in the Trombay critically formula (TCF). The κ ∞ of fast metal actinide nuclides gives a remarkable linear correlation with the fissility parameter Z 2 /A. The neutron leakage probability of all fast metal cores characterized using a constant parameter σ std enables computation of the critical mass value of any unknown fissile nuclide knowing only its Z 2 /A value. Since the neutron leakage probability from dilute fissile solutions is primarily governed by the scattering/slowing down properties of the hydrogen present in water, critical masses and subcritical limits can be predicted for any water-reflected system at any specified hydrogen-to-actinide atomic ratio knowing only the κ ∞ value of the given fissile solution

The German REACH Congress 2016: a workshop report.

Science.gov (United States)

Reihlen, Antonia; Jepsen, Dirk; Broschinski, Lutz; Luch, Andreas; Schulte, Agnes

2018-03-01

In October 2016, the German REACH Congress was held at the German Federal Institute for Risk Assessment (BfR) in Berlin. Here, the associated improvement made in the fields of consumer protection and the progress in and experiences gained from the implementation of the authorisation procedure were discussed. Several speakers from EU institutions, German authorities, industry, and civil society organisations were invited to present their views. There was a shared consensus that REACH contributes to the advancement of consumer protection against chemical risks, mainly because more and higher quality information on substance-related hazards and potential exposures becomes available. In addition, risk management measures, particularly regarding restrictions on uses, scale down consumer exposures to chemicals. Opportunities for improvements identified at the congress include the quality of registration dossiers and the management of and communication on substances of very high concern (SVHC) that may be present in consumer articles. Although regarded as being in an early implementation phase, the authorisation process was generally found to be operational and progressing well. Criticism was expressed with regard to the consistency of authorisation decisions and the costs and uncertainties related to authorisation applications. Consumer protection legislation consists of several legal provisions which are interlinked. The congress participants agreed that REACH is an important element of this legal framework as it enhances and complements other legal provisions.

The evolution of low-mass close binary systems. IV. 0.80 M/sub sun/+0.40 M/sub sun/: Catastrophic mass loss

International Nuclear Information System (INIS)

Webbink, R.F.

1977-01-01

The evolution of both components of a 0.80 M/sub sun/+0.40 M/sub sun/ binary with initial separation 1.60 R/sub sun/ is presented. This system reaches mass transfer during core hydrogen burning in the primary. The primary has such a deep convective envelope that mass transfer proceeds on a dynamical time scale. Mass exchange is followed through the first 6.25 x 10 -3 M/sub sun/, by which time the transfer rate has reached 8.33 x 10 -4 M/sub sun/ yr -1 .It is shown that mass transfer on a dynamical time scale leads to supercritical accretion by the secondary component, and hence is presumably accompanied by extensive mass and angular momentum losses. Stability against such rapid mass transfer may impose severe limitations on the masses and mass ratios of cataclysmic variables

Mechanical energy expenditures and movement efficiency in full body reaching movements.

Science.gov (United States)

Sha, Daohang; France, Christopher R; Thomas, James S

2010-02-01

The effect of target location, speed, and handedness on the average total mechanical energy and movement efficiency is studied in 15 healthy subjects (7 males and 8 females with age 22.9 +/- 1.79 years old) performing full body reaching movements. The average total mechanical energy is measured as the time average of integration of joint power, potential energy, and kinetic energy respectively. Movement efficiency is calculated as the ratio of total kinetic energy to the total joint power and potential energy. Results show that speed and target location have significant effects on total mechanical energy and movement efficiency, but reaching hand only effects kinetic energy. From our findings we conclude that (1) efficiency in whole body reaching is dependent on whether the height of the body center of mass is raised or lowered during the task; (2) efficiency is increased as movement speed is increased, in part because of greater changes in potential energy; and (3) the CNS does not appear to use movement efficiency as a primary planning variable in full body reaching. It may be dependent on a combination of other factors or constraints.

Taking OSCE examiner training on the road: reaching the masses.

Science.gov (United States)

Reid, Katharine; Smallwood, David; Collins, Margo; Sutherland, Ruth; Dodds, Agnes

To ensure the rigour of objective structured clinical examinations (OSCEs) in assessing medical students, medical school educators must educate examiners with a view to standardising examiner assessment behaviour. Delivering OSCE examiner training is a necessary yet challenging part of the OSCE process. A novel approach to implementing training for current and potential OSCE examiners was trialled by delivering large-group education sessions at major teaching hospitals. The 'OSCE Roadshow' comprised a short training session delivered in the context of teaching hospital 'Grand Rounds' to current and potential OSCE examiners. The training was developed to educate clinicians about OSCE processes, clarify the examiners' role and required behaviours, and to review marking guides and mark allocation in an effort to standardise OSCE processes and encourage consistency in examiner marking behaviour. A short exercise allowed participants to practise marking a mock OSCE to investigate examiner marking behaviour after the training. OSCE Roadshows at four metropolitan and one rural teaching hospital were well received and well attended by 171 clinicians across six sessions. Unexpectedly, medical students also attended in large numbers ( n= 220). After training, participants' average scores for the mock OSCE clustered closely around the ideal score of 28 (out of 40), and the average scores did not differ according to the levels of clinical experience. The OSCE Roadshow demonstrated the potential of brief familiarisation training in reaching large numbers of current and potential OSCE examiners in a time and cost-effective manner to promote standardisation of OSCE processes.

Partnerships: The Key to Sustainability and Reach for E/PO

Science.gov (United States)

Eisenhamer, Bonnie; McCallister, D.; Ryer, H.

2013-06-01

The Space Telescope Science Institute (STScI) is the home institution for the E/PO activities of the Hubble and future James Webb space telescopes. Over time, STScI’s Office of Public Outreach has established the infrastructure needed for an E/PO program that reaches various audiences at the local, regional, and national levels. Partnerships are a critical element of this infrastructure, and sustainability of our E/PO program is ensured through our ongoing partnerships with organizations and institutions with staying power and reach. We have learned from past efforts that strategic partnerships can foster innovation, support diversity initiatives, and increase impact in a cost-effective way while providing target audiences with greater access to NASA SMD science and resources. Partnerships are utilized to field-test educational products and programs, disseminate materials and initiatives, and support professional development activities. Partners are selected based upon specific criteria such as potential for reach, the percentage of underrepresented educators and students served, complementary program goals, and willingness to collect and share evaluation data and results with us. This poster will highlight examples and benefits of strategic partnerships over time.

Case management and quality: have we reached a tipping point?

Science.gov (United States)

Dulworth, Sherrie

2006-01-01

In The Tipping Point, Malcolm Gladwell describes a phenomenon in which a niche market or fad undergoes transformation into mainstream acceptability, resulting in widespread social change. He concludes that a "tipping point" occurs when a series of small events results in a critical mass of acceptance that produces sudden major changes.

Critical number of flavors in QED

International Nuclear Information System (INIS)

Bashir, A.; Gutierrez-Guerrero, L. X.; Calcaneo-Roldan, C.; Tejeda-Yeomans, M. E.

2011-01-01

We demonstrate that in unquenched quantum electrodynamics (QED), chiral symmetry breaking ceases to exist above a critical number of fermion flavors N f . This is a necessary and sufficient consequence of the fact that there exists a critical value of electromagnetic coupling α beyond which dynamical mass generation gets triggered. We employ a multiplicatively renormalizable photon propagator involving leading logarithms to all orders in α to illustrate this. We study the flavor and coupling dependence of the dynamically generated mass analytically as well as numerically. We also derive the scaling laws for the dynamical mass as a function of α and N f . Up to a multiplicative constant, these scaling laws are related through (α,α c )↔(1/N f ,1/N f c ). Calculation of the mass anomalous dimension γ m shows that it is always greater than its value in the quenched case. We also evaluate the β function. The criticality plane is drawn in the (α,N f ) phase space which clearly depicts how larger N f is required to restore chiral symmetry for an increasing interaction strength.

Probing the critical behavior in the evolution of GDR width at very low temperatures in A∼100 mass region

Energy Technology Data Exchange (ETDEWEB)

Dey, Balaram; Mondal, Debasish; Pandit, Deepak; Mukhopadhyay, S.; Pal, Surajit [Variable Energy Cyclotron Centre, 1/AF-Bidhannagar, Kolkata 700064 (India); Bhattacharya, Srijit [Department of Physics, Barasat Govt. College, Barasat, N 24 Pgs, Kolkata 700124 (India); De, A. [Department of Physics, Raniganj Girls' College, Raniganj 713358 (India); Banerjee, K. [Variable Energy Cyclotron Centre, 1/AF-Bidhannagar, Kolkata 700064 (India); Dinh Dang, N. [Theoretical Nuclear Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako city, Saitama 351-0198 (Japan); Quang Hung, N. [School of Engineering, Tan Tao University, Tan Tao University Avenue, Tan Duc Ecity, Duc Hoa, Long An Province (Viet Nam); Banerjee, S.R., E-mail: srb@vecc.gov.in [Variable Energy Cyclotron Centre, 1/AF-Bidhannagar, Kolkata 700064 (India)

2014-04-04

The influence of giant dipole resonance (GDR) induced quadrupole moment on GDR width at low temperatures is investigated experimentally by measuring GDR width systematically in the unexplored temperature range T=0.8–1.5 MeV, for the first time, in A∼100 mass region. The measured GDR widths, using alpha induced fusion reaction, for {sup 97}Tc confirm that the GDR width remains constant at the ground state value up to a critical temperature and increases sharply thereafter with increase in T. The data have been compared with the adiabatic Thermal Shape Fluctuation Model (TSFM), phenomenological Critical Temperature Fluctuation Model (CTFM) and microscopic Phonon Damping Model (PDM). Interestingly, CTFM and PDM give similar results and agree with the data, whereas the TSFM differs significantly even after incorporating the shell effects.

Probing the critical behavior in the evolution of GDR width at very low temperatures in A∼100 mass region

International Nuclear Information System (INIS)

Dey, Balaram; Mondal, Debasish; Pandit, Deepak; Mukhopadhyay, S.; Pal, Surajit; Bhattacharya, Srijit; De, A.; Banerjee, K.; Dinh Dang, N.; Quang Hung, N.; Banerjee, S.R.

2014-01-01

The influence of giant dipole resonance (GDR) induced quadrupole moment on GDR width at low temperatures is investigated experimentally by measuring GDR width systematically in the unexplored temperature range T=0.8–1.5 MeV, for the first time, in A∼100 mass region. The measured GDR widths, using alpha induced fusion reaction, for 97 Tc confirm that the GDR width remains constant at the ground state value up to a critical temperature and increases sharply thereafter with increase in T. The data have been compared with the adiabatic Thermal Shape Fluctuation Model (TSFM), phenomenological Critical Temperature Fluctuation Model (CTFM) and microscopic Phonon Damping Model (PDM). Interestingly, CTFM and PDM give similar results and agree with the data, whereas the TSFM differs significantly even after incorporating the shell effects.

Criticality of a 237Np sphere

International Nuclear Information System (INIS)

Sanchez, Rene; Loaiza, David; Kimpland, Robert; Hayes, David; Cappiello, Charlene; Chadwick, Mark

2006-01-01

For the past five years, scientists at Los Alamos National Laboratory have mounted an unprecedented effort to get a better estimate of the critical mass of 237 Np. To accomplish this task, a 6-kg neptunium sphere was recently cast at the Chemical and Metallurgy Research (CMR) facility, which is part of the Los Alamos National Laboratory. The neptunium sphere was clad with tungsten and nickel to reduce the dose rates from the 310 keV gamma rays from the first daughter of neptunium, namely, 233 Pa. 237 Np is a byproduct of power production in nuclear reactors. It is primarily produced by successive neutron captures in 235 U or through the (n,2n) reaction in 238 U. These nuclear reactions lead to the production of 237 U, which decays by beta emission into 237 Np, namely, 235 U(n,γ) 236 U, 236 U(n,γ) 237 U→β→ 237 Np, 238 U (n,2n) 237 U→β→ 237 Np. It is estimated that a typical 1000 MW(e) produces on the order of 12 to 13 kg of neptunium in a year. Some of this neptunium in irradiated fuel elements has been separated and is presently stored in containers in a liquid form. This method of storage is quite adequate because the fission cross section for 237 Np at thermal energies is quite low and any moderation of the neutron population by diluting the configurations with water would increase the critical mass to infinity. However, for long term storage, the neptunium liquid solutions must be converted into oxides and metals because these form are less movable and less likely to leak out of containers. Metals and oxides made out of neptunium have finite critical masses but there is a great uncertainty about these values because of the lack of experimental criticality data. Knowing precisely the critical mass of neptunium not only will help to validate mass storage limits or optimize storage configurations for safe disposition of these materials, but will also save thousands of dollars in transportation and disposition costs. The experimental results presented in

Self-organized criticality in developing neuronal networks.

Directory of Open Access Journals (Sweden)

Christian Tetzlaff

Full Text Available Recently evidence has accumulated that many neural networks exhibit self-organized criticality. In this state, activity is similar across temporal scales and this is beneficial with respect to information flow. If subcritical, activity can die out, if supercritical epileptiform patterns may occur. Little is known about how developing networks will reach and stabilize criticality. Here we monitor the development between 13 and 95 days in vitro (DIV of cortical cell cultures (n = 20 and find four different phases, related to their morphological maturation: An initial low-activity state (≈19 DIV is followed by a supercritical (≈20 DIV and then a subcritical one (≈36 DIV until the network finally reaches stable criticality (≈58 DIV. Using network modeling and mathematical analysis we describe the dynamics of the emergent connectivity in such developing systems. Based on physiological observations, the synaptic development in the model is determined by the drive of the neurons to adjust their connectivity for reaching on average firing rate homeostasis. We predict a specific time course for the maturation of inhibition, with strong onset and delayed pruning, and that total synaptic connectivity should be strongly linked to the relative levels of excitation and inhibition. These results demonstrate that the interplay between activity and connectivity guides developing networks into criticality suggesting that this may be a generic and stable state of many networks in vivo and in vitro.

Taking OSCE examiner training on the road: reaching the masses

Directory of Open Access Journals (Sweden)

Katharine Reid

2016-09-01

Full Text Available Background: To ensure the rigour of objective structured clinical examinations (OSCEs in assessing medical students, medical school educators must educate examiners with a view to standardising examiner assessment behaviour. Delivering OSCE examiner training is a necessary yet challenging part of the OSCE process. A novel approach to implementing training for current and potential OSCE examiners was trialled by delivering large-group education sessions at major teaching hospitals. Methods: The ‘OSCE Roadshow’ comprised a short training session delivered in the context of teaching hospital ‘Grand Rounds’ to current and potential OSCE examiners. The training was developed to educate clinicians about OSCE processes, clarify the examiners’ role and required behaviours, and to review marking guides and mark allocation in an effort to standardise OSCE processes and encourage consistency in examiner marking behaviour. A short exercise allowed participants to practise marking a mock OSCE to investigate examiner marking behaviour after the training. Results: OSCE Roadshows at four metropolitan and one rural teaching hospital were well received and well attended by 171 clinicians across six sessions. Unexpectedly, medical students also attended in large numbers (n=220. After training, participants’ average scores for the mock OSCE clustered closely around the ideal score of 28 (out of 40, and the average scores did not differ according to the levels of clinical experience. Conclusion: The OSCE Roadshow demonstrated the potential of brief familiarisation training in reaching large numbers of current and potential OSCE examiners in a time and cost-effective manner to promote standardisation of OSCE processes.

SRTC criticality safety technical review: Phase 1 criticality analysis for the 9972-9975 family of shipping casks: (SRT-CMA-940003)

International Nuclear Information System (INIS)

Rathbun, R.

1994-01-01

Review of SRT-CMA-940003, ''Phase I Criticality Analysis For The 9972-9975 Family Of Shipping Casks (U). (SRT-CMA-940003).'' January 22, 1994, has been performed by the SRTC Applied Physics Group. The NCSE is a criticality assessment of the 9972-9975 family of shipping casks. This work is a follow-on of a previous criticality safety evaluation, with the differences between this and the previous evaluation are that now wall tolerances are modeled and more sophisticated analytical methods are applied. The NCSE under review concludes that, with one exception, the previously specified plutonium and uranium mass limits for 9972-9975 family of shipping casks do ensure that WSRC Nuclear Criticality Safety Manual requirements (ref. 1) are satisfied. The one exception is that the plutonium mass limit for the 9974 cask had to be reduced from 4.4 to 4.3 kg. In contrast, the 7.5 kg uranium mass limit for the 9974 cask was raised to 14.5 kg, making the uranium mass identical for all casks in this family. This technical review consisted of an independent check of the methods and models employed, application of ANSI/ANS 8.1 and 8.15, and verification of WSRC Nuclear Criticality Safety Manual procedures

Mass Society

DEFF Research Database (Denmark)

Borch, Christian

2017-01-01

the negative features usually ascribed by late nineteenth-century crowd psychology to spontaneous crowds, and attributes these to the entire social fabric. However, in contrast to crowd psychology, theorists of mass society often place greater emphasis on how capitalism, technological advances, or demographic......Mass society is a societal diagnosis that emphasizes – usually in a pejorative, modernity critical manner – a series of traits allegedly associated with modern society, such as the leveling of individuality, moral decay, alienation, and isolation. As such, the notion of mass society generalizes...... developments condition such negative features, and some theorists argue that mass society produces a propensity to totalitarianism. Discussions of mass society culminated in the early and mid-twentieth century....

Jezebel: Reconstructing a Critical Experiment from 60 Years Ago

Energy Technology Data Exchange (ETDEWEB)

Favorite, Jeffrey A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-02-15

The Jezebel experiment of 1954-1955 was a very small, nearly-spherical, nearly-bare (unreflected), nearly-homogeneous assembly of plutonium alloyed with gallium. This experiment was used to determine the critical mass of spherical, bare, homogeneous Pu-alloy. In 1956, the critical mass of Pu-alloy was determined to be 16.45 ± 0.05 kg. The experiment was reevaluated in 1969 using logbooks from the 1950s and updated nuclear cross sections. The critical mass of Pu-alloy was determined to be 16.57 ± 0.10 kg. In 2013, the ²³⁹Pu Jezebel experiment was again reevaluated, this time using detailed geometry and materials models and modern nuclear cross sections in high-fidelity Monte Carlo neutron transport calculations. Documentation from the 1950s was often inconsistent or missing altogether, and assumptions had to be made. The critical mass of Pu-alloy was determined to be 16.624 ± 0.075 kg. Historic documents were subsequently found that validated some of the 2013 assumptions and invalidated others. In 2016, the newly found information was used to once again reevaluate the ²³⁹Pu Jezebel experiment. The critical mass of Pu-alloy was determined to be 16.624 ± 0.065 kg. This talk will discuss each of these evaluations, focusing on the calculation of the uncertainty as well as the critical mass. We call attention to the ambiguity, consternation, despair, and euphoria involved in reconstructing the historic Jezebel experiment. This talk is quite accessible for undergraduate students as well as non-majors.

Social marketing strategies for reaching older people with disabilities: findings from a survey of centers for independent living participants.

Science.gov (United States)

Moone, Rajean Paul; Lightfoot, Elizabeth

2009-01-01

Centers for independent living (CILs) provide critical supports, services, and advocacy for assisting people with disabilities in living independently. As there is a rapidly increasing population of older people with disabilities, many CILs are now considering how to actively engage older adults in their organizations. This study utilized a survey of older people with disabilities to help identify social marketing techniques that community organizations like CILs can use to effectively reach older people with disabilities. Utilizing the components of the social marketing mix in designing outreach efforts, including a critical examination of product, place, price, participants, and partnering, CILs and other community agencies can better reach older adults with disabilities.

Self-Organized Criticality and Mass Extinction in Evolutionary Algorithms

DEFF Research Database (Denmark)

Krink, Thiemo; Thomsen, Rene

2001-01-01

The gaps in the fossil record gave rise to the hypothesis that evolution proceeded in long periods of stasis, which alternated with occasional, rapid changes that yielded evolutionary progress. One mechanism that could cause these punctuated bursts is the re-colonbation of changing and deserted...... at a critical state between chaos and order, known as self-organized criticality (SOC). Based on this background, we used SOC to control the size of spatial extinction zones in a diffusion model. The SOC selection process was easy to implement and implied only negligible computational costs. Our results show...

The geomechanical characterization of the rocky mass foundation of the Tijuco Alto hydroelectric power plant, Ribeira River, Sao Paulo/Parana States, Brazil; Caracterizacao geomecanica do Macico de Fundacao da UHE Tijuco Alto (Rio Ribeira - SP/PR)

Energy Technology Data Exchange (ETDEWEB)

Figueiredo, Amarilis Lucia Casteli de

1996-07-01

This work has as its main objective the geomechanical characterization on the future rocky mass foundation of the Tijuco Alto dam, sited at the Ribeira river, in the cities of Ribeirao, Sao Paulo state and Adrianopolis, Parana state, Brazil, owned by the Companhia Brasileira de Aluminio (Brazilian company of Aluminium). To reach that target, field studies were made to qualify the geotechnical parameters of the rocky mass, in the axis area open galleries. It was also used in situ deformability and stress test results performed in those galleries, that were reinterpreted for a better adaptation of the mass values. The knowledge of the mass inherent characteristics together with the laboratories test results, allowed for the geomechanical classification applications in several different gallery sectors. The geomechanical data obtained allowed through mathematical expressions, to reach the rocky mass values correlations of interest to the work (deformability and strength), that could be compared to the in situ test results. That analysis permitted, besides the classification critical system evaluation, the geomechanical characterization of the rocky mass, focusing its ability to the dam arch construction. (author)

The Challenge of Reaching Transparency: 'T-readiness' of Enterprises and Sector Networks

Directory of Open Access Journals (Sweden)

Melanie Fritz

2010-10-01

Full Text Available  Discussions on the safety and quality of food as well as growing interest in the sustainability of the production, distribution and consumption of food have contributed to the emergence of ‘transparency’ as a critical success factor for the food sector. However, reaching transparency for different stakeholders from different backgrounds and cultural identities is a dynamic process which depends on certain capabilities of enterprises and organizations along the food value chain but also on the realization of a fitting communication scheme within the sector. This discussion asks for the identification and utilization of an indicator that could identify deficiencies and support enterprises and the sector in reaching a level of transparency that could serve specified transparency needs.

The initial mass function for very low mass stars in the Hyades

International Nuclear Information System (INIS)

Hubbard, W.B.; Burrows, A.; Lunine, J.I.

1990-01-01

Theoretical luminosity functions at various evolutionary ages for stars and substellar objects (brown dwarfs), spanning the mass range from 0.03 to 0.2 solar mass is computed. These functions constrain the distribution of very low mass objects in a star cluster of known age. Calculations with a 1988-1989 survey of faint members of the Hyades cluster by Leggett and Hawkins (1988, 1989), a cluster whose age is 6 x 10 to the 8th yr are compared. The comparison shows that the survey does not reach sufficiently low luminosities to reveal brown dwarfs. A strong constraint on the initial mass function (IMF) for very low mass stars in the Hyades is obtained and it is inferred that its IMF does not increase with decreasing mass for the mass interval investigated here. Results imply at most a moderate contribution from brown dwarfs to the cluster mass, and to the Galaxy's mass if the Hyades are representative of the Galaxy as a whole. 10 refs

Precise mass measurements of astrophysical interest made with the Canadian Penning trap mass spectrometer

International Nuclear Information System (INIS)

Clark, J.A.; Barber, R.C.; Blank, B.; Boudreau, C.; Buchinger, F.; Crawford, J.E.; Gulick, S.; Hardy, J.C.; Heinz, A.; Lee, J.K.P.; Levand, A.F.; Moore, R.B.; Savard, G.; Seweryniak, D.; Sharma, K.S.; Sprouse, G.D.; Trimble, W.; Vaz, J.; Wang, J.C.; Zhou, Z.

2004-01-01

The processes responsible for the creation of elements more massive than iron are not well understood. Possible production mechanisms involve the rapid capture of protons (rp-process) or the rapid capture of neutrons (r-process), which are thought to occur in explosive astrophysical events such as novae, x-ray bursts, and supernovae. Mass measurements of the nuclides involved with uncertainties on the order of 100 keV or better are critical to determine the process 'paths', the energy output of the events, and the resulting nuclide abundances. Particularly important are the masses of 'waiting-point' nuclides along the rp-process path where the process stalls until the subsequent β decay of the nuclides. This paper will discuss the precise mass measurements made of isotopes along the rp-process and r-process paths using the Canadian Penning Trap mass spectrometer, including the mass of the critical waiting-point nuclide 68 Se

Why are there race/ethnic differences in adult body mass index–adiposity relationships? A quantitative critical review

Science.gov (United States)

Heymsfield, S. B.; Peterson, C. M.; Thomas, D. M.; Heo, M.; Schuna, J. M.

2016-01-01

Summary Body mass index (BMI) is now the most widely used measure of adiposity on a global scale. Nevertheless, intense discussion centers on the appropriateness of BMI as a phenotypic marker of adiposity across populations differing in race and ethnicity. BMI-adiposity relations appear to vary significantly across race/ethnic groups, but a collective critical analysis of these effects establishing their magnitude and underlying body shape/composition basis is lacking. Accordingly, we systematically review the magnitude of these race-ethnic differences across non-Hispanic (NH) white, NH black and Mexican American adults, their anatomic body composition basis and potential biologically linked mechanisms, using both earlier publications and new analyses from the US National Health and Nutrition Examination Survey. Our collective observations provide a new framework for critically evaluating the quantitative relations between BMI and adiposity across groups differing in race and ethnicity; reveal new insights into BMI as a measure of adiposity across the adult age-span; identify knowledge gaps that can form the basis of future research and create a quantitative foundation for developing BMI-related public health recommendations. PMID:26663309

Why are there race/ethnic differences in adult body mass index-adiposity relationships? A quantitative critical review.

Science.gov (United States)

Heymsfield, S B; Peterson, C M; Thomas, D M; Heo, M; Schuna, J M

2016-03-01

Body mass index (BMI) is now the most widely used measure of adiposity on a global scale. Nevertheless, intense discussion centers on the appropriateness of BMI as a phenotypic marker of adiposity across populations differing in race and ethnicity. BMI-adiposity relations appear to vary significantly across race/ethnic groups, but a collective critical analysis of these effects establishing their magnitude and underlying body shape/composition basis is lacking. Accordingly, we systematically review the magnitude of these race-ethnic differences across non-Hispanic (NH) white, NH black and Mexican American adults, their anatomic body composition basis and potential biologically linked mechanisms, using both earlier publications and new analyses from the US National Health and Nutrition Examination Survey. Our collective observations provide a new framework for critically evaluating the quantitative relations between BMI and adiposity across groups differing in race and ethnicity; reveal new insights into BMI as a measure of adiposity across the adult age-span; identify knowledge gaps that can form the basis of future research and create a quantitative foundation for developing BMI-related public health recommendations. © 2015 World Obesity.

Critical thinking in physics education

Science.gov (United States)

Sadidi, Farahnaz

2016-07-01

We agree that training the next generation of leaders of the society, who have the ability to think critically and form a better judgment is an important goal. It is a long-standing concern of Educators and a long-term desire of teachers to establish a method in order to teach to think critically. To this end, many questions arise on three central aspects: the definition, the evaluation and the design of the course: What is Critical Thinking? How can we define Critical Thinking? How can we evaluate Critical Thinking? Therefore, we want to implement Critical Thinking in physics education. How can we teach for Critical Thinking in physics? What should the course syllabus and materials be? We present examples from classical physics and give perspectives for astro-particle physics. The main aim of this paper is to answer the questions and provide teachers with the opportunity to change their classroom to an active one, in which students are encouraged to ask questions and learn to reach a good judgment. Key words: Critical Thinking, evaluation, judgment, design of the course.

Hydrodynamic Simulation of the Columbia River, Hanford Reach, 1940--2004

Energy Technology Data Exchange (ETDEWEB)

Waichler, Scott R.; Perkins, William A.; Richmond, Marshall C.

2005-06-15

Many hydrological and biological problems in the Columbia River corridor through the Hanford Site require estimates of river stage (water surface elevation) or river flow and velocity. Systematic collection of river stage data at locations in the Hanford Reach began in 1991, but many environmental projects need river stage information at unmeasured locations or over longer time periods. The Modular Aquatic Simulation System 1D (MASS1), a one-dimensional, unsteady hydrodynamic and water quality model, was used to simulate the Columbia River from Priest Rapids Dam to McNary Dam from 1940 to 2004, providing estimates of water surface elevation, volumetric flow rate, and flow velocity at 161 locations on the Hanford Reach. The primary input data were bathymetric/topographic cross sections of the Columbia River channel, flow rates at Priest Rapids Dam, and stage at McNary Dam. Other inputs included Yakima River and Snake River inflows. Available flow data at a gaging station just below Priest Rapids Dam was mean daily flow from 1940 to 1986 and hourly thereafter. McNary dam was completed in 1957, and hourly stage data are available beginning in 1975. MASS1 was run at an hourly timestep and calibrated and tested using 1991--2004 river stage data from six Hanford Reach locations (areas 100B, 100N, 100D, 100H, 100F, and 300). Manning's roughness coefficient in the Reach above each river recorder location was adjusted using an automated genetic algorithm and gradient search technique in three separate calibrations, corresponding to different data subsets, with minimization of mean absolute error as the objective. The primary calibration was based on 1999, a representative year, and included all locations. The first alternative calibration also used all locations but was limited in time to a high-flow period during spring and early summer of 1997. The second alternative calibration was based on 1999 and included only 300 Area stage data. Model goodness-of-fit for all

Comment on critical instability

International Nuclear Information System (INIS)

King, S.F.; Suzuki, Mahiko

1992-01-01

We discuss the problem of the mass splitting between top and bottom quarks, within the context of Nambu-Jona-Lasinio type models involving top and bottom quark condensates. We interpret the phenomenon of 'critical instability' recently proposed to account for such a mass splitting as the fine-tuning of two vacuum expectation values in a composite two-Higgs doublet model. (orig.)

CRITICALITY CONTROL DURING THE DISMANTLING OF A URANIUM CONVERSION PLANT

International Nuclear Information System (INIS)

LADURELLE, Laurent; LISBONNE, Pierre

2003-01-01

Within the Commissariat a l'Energie Atomique, in the Cadarache Research Center in southern France, the production at the Enriched Uranium Treatment Workshops started in 1965 and ended in 1995. The dismantling is in progress and will last until 2006. The decommissioning is planned in 2007. Since the authorized enrichment in 235U was 10% in some parts of the plant, and unlimited in others, the equipment and procedures were designed for criticality control during the operating period. Despite the best previous removing of the uranium in the inner parts of the equipment, evaluation of the mass of remaining fissile material by in site gamma spectrometry measurement shows that the safety of the ''clean up'' operations requires specific criticality control procedures, this mass being higher than the safe mass. The chosen method is therefore based on the mapping of fissile material in the contaminated parts of the equipment and on the respect of particular rules set for meeting the criticality control standards through mass control. The process equipment is partitioned in separated campaign, and for each campaign the equipment dismantling is conducted with a precise traceability of the pieces, from the equipment to the drum of waste, and the best final evaluation of the mass of fissile material in the drum. The first results show that the mass of uranium found in the dismantled equipment is less than the previous evaluation, and they enable us to confirm that the criticality was safely controlled during the operations. The mass of fissile material remaining in the equipment can be then carefully calculated, when it is lower than the minimal critical mass, and on the basis of a safety analysis, we will be free of any constraints regarding criticality control, this allowing to make procedures easier, and to speed up the operations

For the criticality of water reflected homogeneous arrays and heterogeneous reactor fuel elements

Energy Technology Data Exchange (ETDEWEB)

Mueller, Hj; Rabitsch, H; Schuerrer, F [Technische Univ., Graz (Austria). Inst. fuer Theoretische Physik und Reaktorphysik

1980-01-01

The smallest critical masses for fuel elements of research reactors having a medium and high enrichment are calculated. The results fit close on the known critical masses of power reactors with low enrichment. The comparison of the critical masses of reactor fuel elements and homogenized uranium dioxide water systems yields the influence of the homogeneity and of the cladding on the criticality. A coefficient for heterogeneity is suggested which takes into consideration these influences.

Reach Address Database (RAD)

Data.gov (United States)

U.S. Environmental Protection Agency — The Reach Address Database (RAD) stores the reach address of each Water Program feature that has been linked to the underlying surface water features (streams,...

Chapter 7. Critical care triage. Recommendations and standard operating procedures for intensive care unit and hospital preparations for an influenza epidemic or mass disaster

NARCIS (Netherlands)

Christian, Michael D.; Joynt, Gavin M.; Hick, John L.; Colvin, John; Danis, Marion; Sprung, Charles L.; Christian, Micahel D.; Camargo, Ruben; Ceraso, Daniel; Azoulay, Elie; Duguet, Alexandre; Guery, Benoit; Reinhart, Konrad; Adini, Bruria; Barlavie, Yaron; Benin-Goren, Odeda; Cohen, Robert; Klein, Motti; Leoniv, Yuval; Margalit, Gila; Rubinovitch, Bina; Sonnenblick, Moshe; Steinberg, Avraham; Weissman, Charles; Wolff, Donna; Kesecioglu, Jozef; de Jong, Menno; Moreno, Rui; An, Youzhong; Du, Bin; Loo, Shi; Richards, Guy; Artigas, Antonio; Pugin, Jerome; Amundson, Dennis; Devereaux, Asha; Beigel, John; Farmer, Chris; Maki, Dennis; Masur, Henry; Rubinson, Lewis; Sandrock, Christian; Talmor, Daniel; Truog, Robert; Zimmerman, Janice; Brett, Steve; Montgomery, Hugh; Rhodes, Andrew; Sanderson, Frances; Taylor, Bruce

2010-01-01

To provide recommendations and standard operating procedures for intensive care unit (ICU) and hospital preparations for an influenza pandemic or mass disaster with a specific focus on critical care triage. Based on a literature review and expert opinion, a Delphi process was used to define the

Mass size and occurrence of necrosis as discerning values to distinguish between a malignant mass and a bening one by CT. Adrenal mass as the only clinicoradiologic finding

International Nuclear Information System (INIS)

Rodriguez Gonzalez, R.

1991-01-01

We have studied 123 adult patients with 137 adrenal masses, analyzing mass size and ocurrence of necrosis. We have proved that necrosis depends, although not perfectly, on the mass size. Though 81-83% of masses lasser than 3-4 cm are bening, size alone has no a great discerning value to distinguish between a malignant mass and a bening one, other clinical and radiologic data being more decisive. In 37 patients, with 38 adrenal masses, there was no other findings which could information on the type of treatment to choose. From the adrenal masses of these last patients we carried out a diagnostic efficiency curve (DEC) which showed that the critical size in order to distinguish between a bening mass and a malignant one could be 5 cm. After an evaluation of the results obtained in the 137 adrenal masses, we think that is wiser to choose a critical size of 4 cm to establish an acting strategy in the patients with an adrenal mass as the only clinicoradiologic finding. (Author)

Criticality experiment for No.2 core of DF-VI fast neutron criticality facility

International Nuclear Information System (INIS)

Yang Lijun; Liu Zhenhua; Yan Fengwen; Luo Zhiwen; Chu Chun; Liang Shuhong

2007-01-01

At the completion of the DF-VI fast neutron criticality facility, its core changed, and it was restarted and a series of experiments and measurements were made. According to the data from 29 criticality experiments, the criticality element number and mass were calculated, the control rod reactivity worth were measured by period method and rod compensate method, reactivity worth of safety rod and safety block were measured using reactivity instrument; the reactivity worth of outer elements and radial distribution of elements were measured too. Based on all the measurements mentioned above, safety operation parameters for core 2 in DF-VI fast neutron criticality facility were conformed. (authors)

Critical mass flux for flaming ignition of dead, dry wood as a function of external radiant heat flux and oxidizer flow velocity

Science.gov (United States)

Sara McAllister; Mark Finney; Jack Cohen

2010-01-01

Extreme weather often contributes to crown fires, where the fire spreads from one tree crown to the next as a series of piloted ignitions. An important aspect in predicting crown fires is understanding the ignition of fuel particles. The ignition criterion considered in this work is the critical mass flux criterion – that a sufficient amount of pyrolysis gases must be...

Phantom black holes and critical phenomena

Energy Technology Data Exchange (ETDEWEB)

Azreg-Aïnou, Mustapha [Engineering Faculty, Başkent University, Bağlıca Campus, Ankara (Turkey); Marques, Glauber T. [Universidade Federal Rural da Amazônia ICIBE-LASIC, Av. Presidente Tancredo Neves 2501, CEP 66077-901—Belém/PA (Brazil); Rodrigues, Manuel E., E-mail: azreg@baskent.edu.tr, E-mail: gtadaiesky@hotmail.com, E-mail: esialg@gmail.com [Faculdade de Ciências Exatas e Tecnologia, Universidade Federal do Pará, Campus Universitário de Abaetetuba, CEP 68440-000, Abaetetuba, Pará (Brazil)

2014-07-01

We consider the two classes cosh and sinh of normal and phantom black holes of Einstein-Maxwell-dilaton theory. The thermodynamics of these holes is characterized by heat capacities that may have both signs depending on the parameters of the theory. Leaving aside the normal Reissner-Nordström black hole, it is shown that only some phantom black holes of both classes exhibit critical phenomena. The two classes share a nonextremality, but special, critical point where the transition is continuous and the heat capacity, at constant charge, changes sign with an infinite discontinuity. This point yields a classification scheme for critical points. It is concluded that the two unstable and stable phases coexist on one side of the criticality state and disappear on the other side, that is, there is no configuration where only one phase exists. The sinh class has an extremality critical point where the entropy diverges. The transition from extremality to nonextremality with the charge held constant is accompanied by a loss of mass and an increase in the temperature. A special case of this transition is when the hole is isolated (microcanonical ensemble), it will evolve by emission of energy, which results in a decrease of its mass, to the final state of minimum mass and vanishing heat capacity. The Ehrenfest scheme of classification is inaccurate in this case but the generalized one due to Hilfer leads to conclude that the transition is of order less than unity. Fluctuations near criticality are also investigated.

Using a thermalhydraulics system code to estimate heat transfer coefficients for a critical heat flux experiment

International Nuclear Information System (INIS)

Statham, B.A.

2009-01-01

RELAP5/SCDAPSIM MOD 3.4 is used to predict wall temperature before and after critical heat flux (CHF) is reached in a vertical, uniformly heated tube using light water as the working fluid. The heated test section is modeled as a 1 m long Inconel 600 tube having an OD of 6.35 mm and ID of 4.57 mm with a 0.5 m long unheated development length at the inlet. Simulations are performed at pressures of 0.5 to 2.0 MPa with mass fluxes from 500 to 2000 kg m -2 s -1 and inlet qualities ranging from -0.2 to 0. Loss of flow simulations are performed with flow reduction rates of 10, 20, 50, and 100 kg m -2 s -2 . Inlet mass flux at CHF was nominally independent of rate in the model; this may or may not be realistic. (author)

Real-time software use in nuclear materials handling criticality safety control

International Nuclear Information System (INIS)

Huang, S.; Lappa, D.; Chiao, T.; Parrish, C.; Carlson, R.; Lewis, J.; Shikany, D.; Woo, H.

1997-01-01

This paper addresses the use of real-time software to assist handlers of fissionable nuclear material. We focus specifically on the issue of workstation mass limits, and the need for handlers to be aware of, and check against, those mass limits during material transfers. Here ''mass limits'' generally refer to criticality safety mass limits; however, in some instances, workstation mass limits for some materials may be governed by considerations other than criticality, e.g., fire or release consequence limitation. As a case study, we provide a simplified reliability comparison of the use of a manual two handler system with a software-assisted two handler system. We identify the interface points between software and handlers that are relevant to criticality safety

Overcooled haloes at z ≥ 10: a route to form low-mass first stars

CERN Document Server

Prieto, Joaquin; Verde, Licia

2014-01-01

It has been shown by Shchekinov & Vasiliev2006 (SV06) that HD molecules can be an important cooling agent in high redshift z >10 haloes if they undergo mergers under specific conditions so suitable shocks are created. Here we build upon Prieto et al. (2012) who studied in detail the merger-generated shocks, and show that the conditions for HD cooling can be studied by combining these results with a suite of dark-matter only simulations. We have performed a number of dark matter only simulations from cosmological initial conditions inside boxes with sizes from 1 to 4 Mpc. We look for haloes with at least two progenitors of which at least one has mass M > M_cr (z), where M_cr (z) is the SV06 critical mass for HD over-cooling. We find that the fraction of over-cooled haloes with mass between M_cr (z) and 10^{0.2} M_cr (z), roughly below the atomic cooling limit, can be as high as ~ 0.6 at z ~ 10 depending on the merger mass ratio. This fraction decreases at higher redshift reaching a value ~0.2 at z ~ 15. Fo...

Critical dynamics in associative memory networks

Directory of Open Access Journals (Sweden)

Maximilian eUhlig

2013-07-01

Full Text Available Critical behavior in neural networks is characterized by scale-free avalanche size distributions and can be explained by self-regulatory mechanisms. Theoretical and experimental evidence indicates that information storage capacity reaches its maximum in the critical regime. We study the effect of structural connectivity formed by Hebbian learning on the criticality of network dynamics. The network endowed with Hebbian learning only does not allow for simultaneous information storage and criticality. However, the critical regime is can be stabilized by short-term synaptic dynamics in the form of synaptic depression and facilitation or, alternatively, by homeostatic adaptation of the synaptic weights. We show that a heterogeneous distribution of maximal synaptic strengths does not preclude criticality if the Hebbian learning is alternated with periods of critical dynamics recovery. We discuss the relevance of these findings for the flexibility of memory in aging and with respect to the recent theory of synaptic plasticity.

Consideration of Nuclear Criticality When Directly Disposing Highly Enriched Spent Nuclear Fuel in Unsaturated Tuff - I: Nuclear Criticality Constraints

International Nuclear Information System (INIS)

Rechard, Rob P.; Sanchez, Lawrence C.; Trellue, Holly R.

2003-01-01

This paper presents the mass, concentration, and volume required for a critical event to occur in homogeneous mixtures of fissile material and various other geologic materials. The fissile material considered is primarily highly enriched uranium spent fuel; however, 239 Pu is considered in some cases. The non-fissile materials examined are those found in the proposed repository area at Yucca Mountain, Nevada: volcanic tuff, iron rust, concrete, and naturally occurring water. For 235 U, the minimum critical solid concentration for tuff was 5 kg/m 3 (similar to sandstone), and in goethite, 45 kg/m 3 . The critical mass of uranium was sensitive to a number of factors, such as moisture content and fissile enrichment, but had a minimum, assuming almost 100% saturation and >20% enrichment, of 18 kg in tuff as Soddyite (or 9.5 kg as UO 2 ) and 7 kg in goethite. For 239 Pu, the minimum critical solid concentration for tuff was 3 kg/m 3 (similar to sandstone); in goethite, 20 kg/m 3 . The critical mass of plutonium was also sensitive to a number of factors, but had a minimum, assuming 100% saturation and 80-90% enrichment, of 5 kg in tuff and 6 kg in goethite

Control issues related to bilateral teleoperation of long-reach, flexible manipulators

International Nuclear Information System (INIS)

Love, L.J.

1997-01-01

A challenging problem presently being addressed by the Department of Energy (DOE) is the extraction of large volumes of hazardous waste from underground waste storage facilities. The nature of the material requires the use of robotic and teleoperated systems. Furthermore, the constraints of the storage tanks require the use of long reach manipulators. These robots are characterized by their large workspace and reduced mass. Unfortunately, this reduction in mass increases structural compliance, making these robots susceptible to vibration. Until recently, no attempt has been made to provide the operator any type of force reflection due to the compliance of the slave robot. This paper addresses the control of bilateral teleoperation systems that use long-reach, flexible manipulators. Analysis and experiments show that the compliance of the slave robot directly affects the stability of the teleoperation system. This study suggests that this may be controlled by increasing the damping on the master robot. However, this increase in target damping increases the energy an operator must exert during the execution of a task. A new teleoperation strategy adapts the target impedance of the master robot to variations in the identified impedance of the remote environment coupled to the slave robot. Experiments show increased performance due to a decrease in the energy the operator must provide during task execution

Analytic Models of Brown Dwarfs and the Substellar Mass Limit

Directory of Open Access Journals (Sweden)

Sayantan Auddy

2016-01-01

Full Text Available We present the analytic theory of brown dwarf evolution and the lower mass limit of the hydrogen burning main-sequence stars and introduce some modifications to the existing models. We give an exact expression for the pressure of an ideal nonrelativistic Fermi gas at a finite temperature, therefore allowing for nonzero values of the degeneracy parameter. We review the derivation of surface luminosity using an entropy matching condition and the first-order phase transition between the molecular hydrogen in the outer envelope and the partially ionized hydrogen in the inner region. We also discuss the results of modern simulations of the plasma phase transition, which illustrate the uncertainties in determining its critical temperature. Based on the existing models and with some simple modification, we find the maximum mass for a brown dwarf to be in the range 0.064M⊙–0.087M⊙. An analytic formula for the luminosity evolution allows us to estimate the time period of the nonsteady state (i.e., non-main-sequence nuclear burning for substellar objects. We also calculate the evolution of very low mass stars. We estimate that ≃11% of stars take longer than 107 yr to reach the main sequence, and ≃5% of stars take longer than 108 yr.

Prader-Willi Critical Region, a Non-Translated, Imprinted Central Regulator of Bone Mass: Possible Role in Skeletal Abnormalities in Prader-Willi Syndrome.

Directory of Open Access Journals (Sweden)

Ee-Cheng Khor

Full Text Available Prader-Willi Syndrome (PWS, a maternally imprinted disorder and leading cause of obesity, is characterised by insatiable appetite, poor muscle development, cognitive impairment, endocrine disturbance, short stature and osteoporosis. A number of causative loci have been located within the imprinted Prader-Willi Critical Region (PWCR, including a set of small non-translated nucleolar RNA's (snoRNA. Recently, micro-deletions in humans identified the snoRNA Snord116 as a critical contributor to the development of PWS exhibiting many of the classical symptoms of PWS. Here we show that loss of the PWCR which includes Snord116 in mice leads to a reduced bone mass phenotype, similar to that observed in humans. Consistent with reduced stature in PWS, PWCR KO mice showed delayed skeletal development, with shorter femurs and vertebrae, reduced bone size and mass in both sexes. The reduction in bone mass in PWCR KO mice was associated with deficiencies in cortical bone volume and cortical mineral apposition rate, with no change in cancellous bone. Importantly, while the length difference was corrected in aged mice, consistent with continued growth in rodents, reduced cortical bone formation was still evident, indicating continued osteoblastic suppression by loss of PWCR expression in skeletally mature mice. Interestingly, deletion of this region included deletion of the exclusively brain expressed Snord116 cluster and resulted in an upregulation in expression of both NPY and POMC mRNA in the arcuate nucleus. Importantly, the selective deletion of the PWCR only in NPY expressing neurons replicated the bone phenotype of PWCR KO mice. Taken together, PWCR deletion in mice, and specifically in NPY neurons, recapitulates the short stature and low BMD and aspects of the hormonal imbalance of PWS individuals. Moreover, it demonstrates for the first time, that a region encoding non-translated RNAs, expressed solely within the brain, can regulate bone mass in health

Furthering critical institutionalism

Directory of Open Access Journals (Sweden)

Frances Dalton Cleaver

2015-03-01

Full Text Available This special issue furthers the study of natural resource management from a critical institutional perspective. Critical institutionalism (CI is a contemporary body of thought that explores how institutions dynamically mediate relationships between people, natural resources and society. It focuses on the complexity of institutions entwined in everyday social life, their historical formation, the interplay between formal and informal, traditional and modern arrangements, and the power relations that animate them. In such perspectives a social justice lens is often used to scrutinise the outcomes of institutional processes. We argue here that critical institutional approaches have potentially much to offer commons scholarship, particularly through the explanatory power of the concept of bricolage for better understanding institutional change.  Critical institutional approaches, gathering momentum over the past 15 years or so, have excited considerable interest but the insights generated from different disciplinary perspectives remain insufficiently synthesised. Analyses emphasising complexity can be relatively illegible to policy-makers, a fact which lessens their reach. This special issue therefore aims to synthesise critical institutional ideas and so to lay the foundation for moving beyond the emergent stage to make meaningful academic and policy impact. In bringing together papers here we define and synthesise key themes of critical institutionalism, outline the concept of institutional bricolage and identity some key challenges facing this school of thought.

A computation method for mass flowrate predictions in critical flows of initially subcooled liquid in long channels

International Nuclear Information System (INIS)

Celata, G.P.; D'Annibale, F.; Farello, G.E.

1985-01-01

It is suggested a fast and accurate computation method for the prediction of mass flowrate in critical flows initially subcooled liquid from ''long'' discharge channels (high LID values). Starting from a previous very simple correlation proposed by the authors, further improvements in the model enable to widen the method reliability up to initial saturation conditions. A comparison of computed values with 145 experimental data regarding several investigations carried out at the Heat Transfer Laboratory (TERM/ISP, ENEA Casaccia) shows an excellent agreement. The computed data shifting from experimental ones is within ±10% for almost all data, with a slight increase towards low inlet subcoolings. The average error, for all the considered data, is 4,6%

Critical Factors Affecting the Success of Cloning, Expression, and Mass Production of Enzymes by Recombinant E. coli.

Science.gov (United States)

Fakruddin, Md; Mohammad Mazumdar, Reaz; Bin Mannan, Khanjada Shahnewaj; Chowdhury, Abhijit; Hossain, Md Nur

2013-01-01

E. coli is the most frequently used host for production of enzymes and other proteins by recombinant DNA technology. E. coli is preferable for its relative simplicity, inexpensive and fast high-density cultivation, well-known genetics, and large number of compatible molecular tools available. Despite all these advantages, expression and production of recombinant enzymes are not always successful and often result in insoluble and nonfunctional proteins. There are many factors that affect the success of cloning, expression, and mass production of enzymes by recombinant E. coli. In this paper, these critical factors and approaches to overcome these obstacles are summarized focusing controlled expression of target protein/enzyme in an unmodified form at industrial level.

Restoring Maximum Vertical Browsing Reach in Sauropod Dinosaurs.

Science.gov (United States)

Paul, Gregory S

2017-10-01

The ongoing controversy centered on neck posture and function in sauropod dinosaurs is misplaced for a number of reasons. Because of an absence of pertinent data it is not possible to accurately restore the posture and range of motion in long necked fossil animals, only gross approximations are possible. The existence of a single "neutral posture" in animals with long, slender necks may not exist, and its relationship to feeding habits is weak. Restorations of neutral osteological neck posture based on seemingly detailed diagrams of cervical articulations are not reliable because the pictures are not sufficiently accurate due to a combination of illustration errors, and distortion of the fossil cervicals. This is all the more true because fossil cervical series lack the critical inter-centra cartilage. Maximum vertical reach is more readily restorable and biologically informative for long necked herbivores. Modest extension of 10° between each caudal cervical allowed high shouldered sauropods to raise the cranial portion of their necks to vertical postures that allowed them to reach floral resources far higher than seen in the tallest mammals. This hypothesis is supported by the dorsally extended articulation of the only known co-fused sauropod cervicals. Many sauropods appear to have been well adapted for rearing in order to boost vertical reach, some possessed retroverted pelves that may have allowed them to walk slowly while bipedal. A combination of improved high browsing abilities and sexual selection probably explains the unusually long necks of tall ungulates and super tall sauropods. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:1802-1825, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Critical percolation in the slow cooling of the bi-dimensional ferromagnetic Ising model

Science.gov (United States)

Ricateau, Hugo; Cugliandolo, Leticia F.; Picco, Marco

2018-01-01

We study, with numerical methods, the fractal properties of the domain walls found in slow quenches of the kinetic Ising model to its critical temperature. We show that the equilibrium interfaces in the disordered phase have critical percolation fractal dimension over a wide range of length scales. We confirm that the system falls out of equilibrium at a temperature that depends on the cooling rate as predicted by the Kibble-Zurek argument and we prove that the dynamic growing length once the cooling reaches the critical point satisfies the same scaling. We determine the dynamic scaling properties of the interface winding angle variance and we show that the crossover between critical Ising and critical percolation properties is determined by the growing length reached when the system fell out of equilibrium.

Naturalness reach of the large hadron collider in minimal supergravity

International Nuclear Information System (INIS)

Allanach, B.C.; Hetherington, J.P.J.; Parker, M.A.; Webber, B.R.

2000-01-01

We re-analyse the prospects of discovering supersymmetry at the LHC, in order to re-express coverage in terms of a fine-tuning parameter and to extend the analysis to scalar masses (m 0 ) above 2 TeV. We use minimal supergravity (mSUGRA) unification assumptions for the SUSY breaking parameters. Such high values of m 0 have recently been found to have a focus point, leading to relatively low fine-tuning. In addition, improvements in the simulations since the last study mean that this region no longer lacks radiative electroweak symmetry breaking. The best fine tuning reach is found in a mono-leptonic channel, where for μ>0, A 0 =0 and tan β=10 (corresponding to the focus point), all points in mSUGRA with m 0 0 , mSUGRA does not evade detection provided the gaugino mass parameter M 1/2 < 460 GeV. (author)

An Appraisal of Mass Media Role in Consolidating Democracy in ...

African Journals Online (AJOL)

This study therefore critically assessed the performance of Nigerian mass media in consolidating democracy. The study is of the view that the mass contributed immensely to the return of democracy in Nigeria. This the media did through their critical criticism of the military juntas, mobilization of the citizens to participate in ...

MMAPS: Missing-Mass A-Prime Search

OpenAIRE

Alexander Jim

2017-01-01

An experiment is proposed to search for dark photons via electron-positron annihilation into photon plus dark photon. The dark photon would be reconstructed in a missing-mass technique, thus ensuring complete model independent. The Cornell University synchrotron can provide a positron beam suitable to probe the interesting mass range for dark photons. A detector based on CsI calorimetry is proposed, and the potential experimental reach in coupling constant and dark photon mass is shown.

The critical oxide thickness for Pb-free reflow soldering on Cu substrate

Energy Technology Data Exchange (ETDEWEB)

Chung, C. Key [Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan (China); Assembly Test Global Materials, Intel Microelectronics Asia Ltd, B1, No. 205, Tun-Hwa North Road, 10595 Taipei, Taiwan (China); Chen, Y.J.; Li, C.C. [Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan (China); Kao, C.R., E-mail: crkao@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan (China)

2012-06-01

Oxidation is an undesirable effect of reflow soldering. Non-wetting occurs when the oxide layer grows above the critical thickness. Characterizing the critical oxide thickness for soldering is challenging due to oxide's nano-scale thickness and irregular topographic surface. In this paper, the critical copper oxide thickness was characterized by Time-of-Flight Secondary Ion Mass Spectrometry, Scanning Electron Microscopy, Energy-Dispersive X-ray spectroscopy, and Transmission Electron Microscopy. Copper substrates were coated with an Organic-Solderable-Preservative (OSP) layer and baked at 150 Degree-Sign C and 85% Relative Humidity for different amounts of time. The onset of the non-wetting phenomenon occurred when the oxide thickness reached 18 {+-} 5 nm. As the oxide grew beyond this critical thickness, the percentage of non-wetting solder joint increased exponentially. The growth of the oxide thickness followed a parabolic rate law. The rate constant of oxidation was 0.6 Multiplication-Sign 10{sup -15} cm{sup 2} min{sup -1}. Oxidation resulted from interdiffusion of copper and oxygen atoms through the OSP and oxide layers. The oxidation mechanism will be presented and discussed. - Highlights: Black-Right-Pointing-Pointer Critical oxide thickness for Pb free solder on Cu substrate is 18 {+-} 5 nm. Black-Right-Pointing-Pointer Above the critical oxide, non-wet solder joint increases exponentially. Black-Right-Pointing-Pointer A maximum 13-nm oxide thickness is suggested for good solder joint. Black-Right-Pointing-Pointer Initial growth of oxide thickness is logarithmic and then parabolic after 12 nm. Black-Right-Pointing-Pointer Thick oxide (360-560 nm) is formed as pores shorten the oxidation path.

Development of microgravity, full body functional reach envelope using 3-D computer graphic models and virtual reality technology

Science.gov (United States)

Lindsey, Patricia F.

1994-01-01

In microgravity conditions mobility is greatly enhanced and body stability is difficult to achieve. Because of these difficulties, optimum placement and accessibility of objects and controls can be critical to required tasks on board shuttle flights or on the proposed space station. Anthropometric measurement of the maximum reach of occupants of a microgravity environment provide knowledge about maximum functional placement for tasking situations. Calculations for a full body, functional reach envelope for microgravity environments are imperative. To this end, three dimensional computer modeled human figures, providing a method of anthropometric measurement, were used to locate the data points that define the full body, functional reach envelope. Virtual reality technology was utilized to enable an occupant of the microgravity environment to experience movement within the reach envelope while immersed in a simulated microgravity environment.

Estimation of unknown nuclear masses by means of the generalized mass relations. Pt. 3

International Nuclear Information System (INIS)

Popa, S.M.

1980-01-01

A survey of the estimations of the unknown nuclear masses by means of the generalized mass relations is presented. One discusses the new hypotheses supplementing the original general Garvey-Kelson scheme, reviewing the generalized mass relations and formulae, according to the present status of this new formalism. A critical discussions is given of the reliability of these new Garvey-Kelson type extrapolation procedures. (author)

Critical and subcritical parameters of the system simulating plutonium metal dissolution

International Nuclear Information System (INIS)

Vasilev, Yury Yu.; Ryazanov, Boris G.; Sviridov, Victor I.; Mozhayeva, Lubov I.

2003-01-01

Dissolution of plutonium metal was simulated using the Monte Carlo computer code to calculate criticality safety limits for the process. Calculations were made for the constant masses of plutonium charged to the dissolving vessel considering distribution of plutonium in metal and solution phases. Critical parameters and limits were calculated as a function of dissolving vessel volume and plutonium metal mass. 240 Pu content was assumed to be from 0% to 10% (mass). Critical parameters were evaluated for the system with a water reflector. Results of this paper may be used in the designing process equipment for plutonium metal dissolution. (author)

Reach of the Fermilab Tevatron and CERN LHC for gaugino mediated SUSY breaking models

International Nuclear Information System (INIS)

Baer, Howard; Belyaev, Alexander; Krupovnickas, Tadas; Tata, Xerxes

2002-01-01

In supersymmetric models with gaugino mediated SUSY breaking (gMSB), it is assumed that SUSY breaking on a hidden brane is communicated to the visible brane via gauge superfields which propagate in the bulk. This leads to GUT models where the common gaugino mass m 1/2 is the only soft SUSY breaking term to receive contributions at the tree level. To obtain a viable phenomenology, it is assumed that the gaugino mass is induced at some scale M c beyond the GUT scale, and that additional renormalization group running takes place between M c and M GUT as in a SUSY GUT. We assume an SU(5) SUSY GUT above the GUT scale, and compute the SUSY particle spectrum expected in models with gMSB. We use the Monte Carlo program ISAJET to simulate signals within the gMSB model, and compute the SUSY reach including cuts and triggers appropriate to Fermilab Tevatron and CERN LHC experiments. We find no reach for SUSY by the Tevatron collider in the trilepton channel. At the CERN LHC, values of m 1/2 =1000 (1160) GeV can be probed with 10 (100) fb -1 of integrated luminosity, corresponding to a reach in terms of m g-tilde of 2150 (2500) GeV. The gMSB model and MSUGRA can likely only be differentiated at a linear e + e - collider with sufficient energy to produce sleptons and charginos

Hierarchical modular structure enhances the robustness of self-organized criticality in neural networks

International Nuclear Information System (INIS)

Wang Shengjun; Zhou Changsong

2012-01-01

One of the most prominent architecture properties of neural networks in the brain is the hierarchical modular structure. How does the structure property constrain or improve brain function? It is thought that operating near criticality can be beneficial for brain function. Here, we find that networks with modular structure can extend the parameter region of coupling strength over which critical states are reached compared to non-modular networks. Moreover, we find that one aspect of network function—dynamical range—is highest for the same parameter region. Thus, hierarchical modularity enhances robustness of criticality as well as function. However, too much modularity constrains function by preventing the neural networks from reaching critical states, because the modular structure limits the spreading of avalanches. Our results suggest that the brain may take advantage of the hierarchical modular structure to attain criticality and enhanced function. (paper)

Lecture notes for criticality safety

International Nuclear Information System (INIS)

Fullwood, R.

1992-03-01

These lecture notes for criticality safety are prepared for the training of Department of Energy supervisory, project management, and administrative staff. Technical training and basic mathematics are assumed. The notes are designed for a two-day course, taught by two lecturers. Video tapes may be used at the options of the instructors. The notes provide all the materials that are necessary but outside reading will assist in the fullest understanding. The course begins with a nuclear physics overview. The reader is led from the macroscopic world into the microscopic world of atoms and the elementary particles that constitute atoms. The particles, their masses and sizes and properties associated with radioactive decay and fission are introduced along with Einstein's mass-energy equivalence. Radioactive decay, nuclear reactions, radiation penetration, shielding and health-effects are discussed to understand protection in case of a criticality accident. Fission, the fission products, particles and energy released are presented to appreciate the dangers of criticality. Nuclear cross sections are introduced to understand the effectiveness of slow neutrons to produce fission. Chain reactors are presented as an economy; effective use of the neutrons from fission leads to more fission resulting in a power reactor or a criticality excursion. The six-factor formula is presented for managing the neutron budget. This leads to concepts of material and geometric buckling which are used in simple calculations to assure safety from criticality. Experimental measurements and computer code calculations of criticality are discussed. To emphasize the reality, historical criticality accidents are presented in a table with major ones discussed to provide lessons-learned. Finally, standards, NRC guides and regulations, and DOE orders relating to criticality protection are presented

K-effective as a measure of criticality safety

International Nuclear Information System (INIS)

Venner, J.; Haley, R.M.; Bowden, R.L.

2003-01-01

This paper considers the relation between the neutron multiplication of a system, k-effective, and critical parameters. It aims to investigate whether k-effective is always the most appropriate measure of safety. For simple systems handbook data can be effectively utilized, applying a safety factor to critical masses. In such situations, the criticality safety margin is readily apparent. However, more complex systems may use the calculated value of neutron multiplication to assess the criticality safety of the system under investigation. A problem arises because there is no exact consistency between k-effective and the physical margin of subcriticality, in terms of parameters such as mass. In the UK, commonly accepted safety criteria are applied to limit the k-effective of the system being assessed. These margins of subcriticality have no definitive justification to support the values chosen and might be considered rather arbitrary in nature. This paper aims to answer this question of suitability by investigating the relation between k-effective and the physical critical parameters for a wide range of systems. It concludes that the safety criteria currently applied in the UK are valid, but some difference exists between safety factors applied to the mass of fissile material present and the corresponding value of k-effective. (author)

Oral cholera vaccine coverage in hard-to-reach fishermen communities after two mass Campaigns, Malawi, 2016.

Science.gov (United States)

Sauvageot, Delphine; Saussier, Christel; Gobeze, Abebe; Chipeta, Sikhona; Mhango, Innocent; Kawalazira, Gift; Mengel, Martin A; Legros, Dominique; Cavailler, Philippe; M'bang'ombe, Maurice

2017-09-12

From December 2015 to August 2016, a large epidemic of cholera affected the fishermen of Lake Chilwa in Malawi. A first reactive Oral Cholera Vaccines (OCV) campaign was organized, in February, in a 2km radius of the lake followed by a preemptive one, conducted in November, in a 25km radius. We present the vaccine coverage reached in hard-to-reach population using simplified delivery strategies. We conducted two-stage random-sampling cross-sectional surveys among individuals living in a 2km and 25km radius of Lake Chilwa (islands and floating homes included). Individuals aged 12months and older from Machinga and Zomba districts were sampled: 43 clusters of 14 households were surveyed. Simplified strategies were used for those living in islands and floating homes: self- delivery and community-supervised delivery of the second dose. Vaccine coverage (VC) for at-least-two-doses was estimated taking into account sampling weights and design effects. A total of 1176 households were surveyed (2.7% of non-response). Among the 2833 individuals living in the 2km radius of Lake and the 2915 in the 25km radius: 457 (16.1%) and 239 (8.2%) lived in floating homes or on islands at some point in the year, respectively. For the overall population, VC was 75.6% and 54.2%, respectively. In the 2km radius, VC was 92.2% for those living on the lake at some point of the year: 271 (64.8%) used the simplified strategies. The main reasons for non-vaccination were absence during the campaign and vaccine shortage. Few adverse events occurring in the 24h following vaccination was reported. We reached a high two-dose coverage of the most at-risk population using simplified delivery strategies. Because of the high fishermen mobility, regular catch-up campaigns or another strategy specifically targeting fishermen need to be assessed for more efficient vaccines use. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Can donated media placements reach intended audiences?

Science.gov (United States)

Cooper, Crystale Purvis; Gelb, Cynthia A; Chu, Jennifer; Polonec, Lindsey

2013-09-01

Donated media placements for public service announcements (PSAs) can be difficult to secure, and may not always reach intended audiences. Strategies used by the Centers for Disease Control and Prevention's (CDC) Screen for Life: National Colorectal Cancer Action Campaign (SFL) to obtain donated media placements include producing a diverse mix of high-quality PSAs, co-branding with state and tribal health agencies, securing celebrity involvement, monitoring media trends to identify new distribution opportunities, and strategically timing the release of PSAs. To investigate open-ended recall of PSAs promoting colorectal cancer screening, CDC conducted 12 focus groups in three U.S. cities with men and women either nearing age 50 years, when screening is recommended to begin, or aged 50-75 years who were not in compliance with screening guidelines. In most focus groups, multiple participants recalled exposure to PSAs promoting colorectal cancer screening, and most of these individuals reported having seen SFL PSAs on television, in transit stations, or on the sides of public buses. Some participants reported exposure to SFL PSAs without prompting from the moderator, as they explained how they learned about the disease. Several participants reported learning key campaign messages from PSAs, including that colorectal cancer screening should begin at age 50 years and screening can find polyps so they can be removed before becoming cancerous. Donated media placements can reach and educate mass audiences, including millions of U.S. adults who have not been screened appropriately for colorectal cancer.

Stellar-Mass Black Holes and their Progenitors

NARCIS (Netherlands)

Miller, J.; Uttley, [No Value; Nandra, [No Value; Barret, [No Value; Matt, [No Value; Paerels, [No Value; Mendez, [No Value; Diaz-Trigo, [No Value; Cappi, [No Value; Kitamoto, [No Value; Nowak, [No Value; Wilms, [No Value; Rothschild, [No Value; Smith, [No Value; Weisskopf, [No Value; Terashima, [No Value; Ueda, [No Value

2009-01-01

If a black hole has a low spin value, it must double its mass to reach a high spin parameter (Volonteri et al. 2005). Although this is easily accomplished through mergers or accretion in the case of supermassive black holes in galactic centers, it is impossible for stellar-mass black holes in X-ray

Theoretical modeling of critical temperature increase in metamaterial superconductors

Science.gov (United States)

Smolyaninov, Igor; Smolyaninova, Vera

Recent experiments have demonstrated that the metamaterial approach is capable of drastic increase of the critical temperature Tc of epsilon near zero (ENZ) metamaterial superconductors. For example, tripling of the critical temperature has been observed in Al-Al2O3 ENZ core-shell metamaterials. Here, we perform theoretical modelling of Tc increase in metamaterial superconductors based on the Maxwell-Garnett approximation of their dielectric response function. Good agreement is demonstrated between theoretical modelling and experimental results in both aluminum and tin-based metamaterials. Taking advantage of the demonstrated success of this model, the critical temperature of hypothetic niobium, MgB2 and H2S-based metamaterial superconductors is evaluated. The MgB2-based metamaterial superconductors are projected to reach the liquid nitrogen temperature range. In the case of an H2S-based metamaterial Tc appears to reach 250 K. This work was supported in part by NSF Grant DMR-1104676 and the School of Emerging Technologies at Towson University.

Alternate measurements of benefit to criticality issues at Hanford

Energy Technology Data Exchange (ETDEWEB)

Toffer, H.; Cabrilla, D.E.

1997-06-01

Measurements in a critical mass facility, such as the Los Alamos Critical Experiments Facility, could be performed on simulated nuclear waste materials that would provide important critical mass information and concurrently provide a calibration of alternate measurement techniques. In addition to criticality information, the measurements could also provide a better assessment of diluent material/neutron interaction cross sections. An Hanford, large quantities of fissionable materials are dispersed in tanks, fuel storage pools, and in solid waste. Although the fissionable materials are well diluted by a variety of neutron-moderating and -absorbing substances, it is difficult to assess the margin of subcriticality. A number of measurement approaches are proposed that will either help determine fissionable material concentrations, distributions, or provide a direct measure of subcriticality. The methods under consideration involve passive neutron counting, active neutron measurements, pulse neutron applications, neutron noise analyses, and cover gas evaluations. Active neutron measurements can also provide insight into the determination of neutron absorber concentrations. Efforts are underway to test some of the methods in actual waste tank environments and geometries. It is important that these methods be tested and calibrated in a critical mass facility.

Alternate measurements of benefit to criticality issues at Hanford

International Nuclear Information System (INIS)

Toffer, H.; Cabrilla, D.E.

1997-01-01

Measurements in a critical mass facility, such as the Los Alamos Critical Experiments Facility, could be performed on simulated nuclear waste materials that would provide important critical mass information and concurrently provide a calibration of alternate measurement techniques. In addition to criticality information, the measurements could also provide a better assessment of diluent material/neutron interaction cross sections. An Hanford, large quantities of fissionable materials are dispersed in tanks, fuel storage pools, and in solid waste. Although the fissionable materials are well diluted by a variety of neutron-moderating and -absorbing substances, it is difficult to assess the margin of subcriticality. A number of measurement approaches are proposed that will either help determine fissionable material concentrations, distributions, or provide a direct measure of subcriticality. The methods under consideration involve passive neutron counting, active neutron measurements, pulse neutron applications, neutron noise analyses, and cover gas evaluations. Active neutron measurements can also provide insight into the determination of neutron absorber concentrations. Efforts are underway to test some of the methods in actual waste tank environments and geometries. It is important that these methods be tested and calibrated in a critical mass facility

Critical point measurement of some polycyclic aromatic hydrocarbons

International Nuclear Information System (INIS)

Nikitin, Eugene D.; Popov, Alexander P.

2015-01-01

Highlights: • Critical properties of five polycyclic aromatic hydrocarbons were measured. • These hydrocarbons decompose at near-critical temperatures. • Pulse-heating method with short residence times was used. - Abstract: The critical temperatures and the critical pressures of five polycyclic aromatic compounds, namely, acenaphthene, fluorene, anthracene, phenanthrene, and pyrene have been measured. All the compounds studied decompose at near-critical temperatures. A pulse-heating technique applicable to measuring the critical properties of thermally unstable compounds has been used. The times from the beginning of a heating pulse to the moment of reaching the critical temperature were from (0.06 to 0.85) ms. The short residence times provide little degradation of the substances in the course of the experiments. The experimental critical parameters of the polycyclic aromatic compounds have been compared with those estimated by five predictive methods. The acentric factors of polycyclic aromatic compounds studied have been calculated

Evolution of a 30 solar mass star: the interplay of nuclear burning and mass loss

International Nuclear Information System (INIS)

Falk, H.J.; Mitalas, R.

1981-01-01

Evolutionary tracks for a 30 solar mass star with various mass loss rates (MLR) were evolved to core He exhaustion. The 'overluminosity' of mass losing (ML) stars is explained in terms of the well known mass-luminosity (M-L) law. A critical ZAMS MLR above which mass loss leads to evolution to fainter luminosities is derived. Two tracks showed reversals in their direction of evolution across the HR diagram. These have been shown to be a consequence of mass loss dominating over the effects of the shell source. An analytic criterion for this condition has been derived. (Auth.)

Critical experiments of JMTRC MEU cores

International Nuclear Information System (INIS)

Nagaoka, Y.; Takeda, K.; Shimakawa, S.; Koike, S.; Oyamada, R.

1984-01-01

The JMTRC, the critical facility of the Japan Materials Testing Reactor (JMTR), went critical on August 29, 1983, with 14 medium enriched uranium (MEU, 45%) fuel elements. Experiments are now being carried out to measure the change in various reactor characteristics between the previous HEU core and the new MEU fueled core. This paper describes the results obtained thus far on critical mass, excess reactivity, control rod worths and flux distribution, including preliminary neutronics calculations for the experiments using the SRAC code. (author)

The assessment of two-fluid models using critical flow data

International Nuclear Information System (INIS)

Shome, B.; Lahey, R.T. Jr.

1992-01-01

The behavior of two-phase flow is governed by the thermal-hydraulic transfers occurring across phasic interfaces. If correctly formulated, two-fluid models should yield all conceivable evolutions. Moreover, some experiments may be uniquely qualified for model assessment if they can isolate important closure models. This paper is primarily concerned with the possible assessment of the virtual mass force using air-water critical flow data, in which phase-change effects do not take place. The following conclusions can be drawn from this study: (1) The closure parameters, other than those for cirtual mass, were found to have an insignificant effect on critical flow. In contrast, the void fraction profile and the slip ratio were observed to be sensitive to the virtual mass model. (2) It appears that air-water critical flow experiments may be effectively used for the assessment of the virtual mass force used in two-fluid models. In fact, such experiments are unique in their ability to isolate the spatial gradients in a vm models. It is hoped that this study will help stimulate the conduct of further critical flow experiments for the assessment of two fluid models

Guide for the preparation of applications for special nuclear material licenses of less than critical mass quantities - July 1976

International Nuclear Information System (INIS)

Anon.

1977-01-01

This guide describes the type of information needed to evaluate an application for a specific license for receipt, possession, use, and transfer of special nuclear material. It is intended for applicants requesting authorization to possess and use up to 2000 grams of plutonium, total, in the form of sealed plutonium-beryllium neutron sources, and any special nuclear material in quantities and forms not sufficient to form a critical mass. The latter quantities are considered to be 350 grams of contained uranium-235, 200 grams of uranium-233, 200 grams of plutonium (in any form other than plutonium-beryllium neutron sources) or any combination of them

Comprehensive and critical review of the predictive properties of the various mass models

International Nuclear Information System (INIS)

Haustein, P.E.

1984-01-01

Since the publication of the 1975 Mass Predictions approximately 300 new atomic masses have been reported. These data come from a variety of experimental studies using diverse techniques and they span a mass range from the lightest isotopes to the very heaviest. It is instructive to compare these data with the 1975 predictions and several others (Moeller and Nix, Monahan, Serduke, Uno and Yamada which appeared latter. Extensive numerical and graphical analyses have been performed to examine the quality of the mass predictions from the various models and to identify features in these models that require correction. In general, there is only rough correlation between the ability of a particular model to reproduce the measured mass surface which had been used to refine its adjustable parameters and that model's ability to predict correctly the new masses. For some models distinct systematic features appear when the new mass data are plotted as functions of relevant physical variables. Global intercomparisons of all the models are made first, followed by several examples of types of analysis performed with individual mass models

Measurements of Critical Heat Flux using Mass Transfer System

Energy Technology Data Exchange (ETDEWEB)

Hong, Seung Hyun; Chung Bum Jin [Kyunghee University, Yongin (Korea, Republic of)

2016-05-15

In a severe accident, the reactor vessel is heated by the decay heat from core melts and the outer surface of reactor vessel is cooled by the natural convection of water pool. When the heat flux increases, boiling will start. Further increase of the heat flux may result in the CHF, which is generated by the bubble combinations. The CHF means that the reactor vessel was separated with coolant and wall temperature is raised rapidly. It may damage the reactor vessel. Also the CHF indicates the maximum cooling capability of the system. Therefore, the CHF has been used as a criterion for the regulatory and licensing. Mechanism of hydrogen vapor bubbles generated and combined can be simulated water bubbles mechanism. And also the both heat and mass transfer mechanism of CHF can be identified in the same methods. Therefore, the CHF phenomena can be simulated enough by mass transfer.

Criticality calculations for a critical assembly, graphite moderate, using 20% enriched uranium

International Nuclear Information System (INIS)

Almeida Ferreira, A.C. de; Hukai, R.Y.

1975-01-01

The construction of a Zero Power Reactor (ZPR) at the Instituto de Energia Atomica in order to measure the neutron characteristics (parameters) of HTGR reactors is proposed. The necessary quantity fissile uranium for these measurements has been calculed. Criticality studies of graphite moderated critical assemblies containing thorium have been made and the critical mass of each of several typical commercial HTGR compositions has been calculated using computer codes HAMMER and CITATION. Assemblies investigated contained a central cylindrical core region, simulating a typical commercial HTGR composition, a uranium-graphite driver region and a outer pure graphite reflector region. It is concluded that a 10Kg inventory of fissile uranium will be required for a program of measurements utilizing each of the several calculated assemblies

Critical-Cultural Studies in Research and Instruction.

Science.gov (United States)

Switzer, Les; McNamara, John; Ryan, Michael

1999-01-01

Outlines two paradigms in critical-cultural analysis that seek to identify and explain the meaning of phenomena that make a culture, focusing on their relevance to research and teaching in journalism and mass communication. Identifies key issues and implications for mass communication research and teaching. Suggests ways educators can apply…

A fundamental study of a variable critical nozzle flow

International Nuclear Information System (INIS)

Kim, Jea Hyung; Kim, Heuy Dong; Park, Kyung Am

2003-01-01

The mass flow rate of gas flow through critical nozzle depends on the nozzle supply conditions and the cross-sectional area at the nozzle throat. In order that the critical nozzle can be operated at a wide range of supply conditions, the nozzle throat diameter should be controlled to change the flow passage area. This can be achieved by means of a variable critical nozzle. In the present study, both experimental and computational works are performed to develop variable critical nozzle. A cone-cylinder with a diameter of d is inserted into conventional critical nozzle. It can move both upstream and downstream, thereby changing the cross-sectional area of the nozzle throat. Computational work using the axisymmetric, compressible Navier-Stokes equations is carried out to simulate the variable critical nozzle flow. An experiment is performed to measure the mass flow rate through variable critical nozzle. The present computational results are in close agreement with measured ones. The boundary layer displacement and momentum thickness are given as a function of Reynolds number. An empirical equation is obtained to predict the discharge coefficient of variable critical nozzle

Effects of accuracy constraints on reach-to-grasp movements in cerebellar patients.

Science.gov (United States)

Rand, M K; Shimansky, Y; Stelmach, G E; Bracha, V; Bloedel, J R

2000-11-01

Reach-to-grasp movements of patients with pathology restricted to the cerebellum were compared with those of normal controls. Two types of paradigms with different accuracy constraints were used to examine whether cerebellar impairment disrupts the stereotypic relationship between arm transport and grip aperture and whether the variability of this relationship is altered when greater accuracy is required. The movements were made to either a vertical dowel or to a cross bar of a small cross. All subjects were asked to reach for either target at a fast but comfortable speed, grasp the object between the index finger and thumb, and lift it a short distance off the table. In terms of the relationship between arm transport and grip aperture, the control subjects showed a high consistency in grip aperture and wrist velocity profiles from trial to trial for movements to both the dowel and the cross. The relationship between the maximum velocity of the wrist and the time at which grip aperture was maximal during the reach was highly consistent throughout the experiment. In contrast, the time of maximum grip aperture and maximum wrist velocity of the cerebellar patients was quite variable from trial to trial, and the relationship of these measurements also varied considerably. These abnormalities were present regardless of the accuracy requirement. In addition, the cerebellar patients required a significantly longer time to grasp and lift the objects than the control subjects. Furthermore, the patients exhibited a greater grip aperture during reach than the controls. These data indicate that the cerebellum contributes substantially to the coordination of movements required to perform reach-to-grasp movements. Specifically, the cerebellum is critical for executing this behavior with a consistent, well-timed relationship between the transport and grasp components. This contribution is apparent even when accuracy demands are minimal.

Matter fields near quantum critical point in (2+1)-dimensional U(1) gauge theory

International Nuclear Information System (INIS)

Liu Guozhu; Li Wei; Cheng Geng

2010-01-01

We study chiral phase transition and confinement of matter fields in (2+1)-dimensional U(1) gauge theory of massless Dirac fermions and scalar bosons. The vanishing scalar boson mass, r=0, defines a quantum critical point between the Higgs phase and the Coulomb phase. We consider only the critical point r=0 and the Coulomb phase with r>0. The Dirac fermion acquires a dynamical mass when its flavor is less than certain critical value N f c , which depends quantitatively on the flavor N b and the scalar boson mass r. When N f f c , the matter fields carrying internal gauge charge are all confined if r≠0 but are deconfined at the quantum critical point r=0. The system has distinct low-energy elementary excitations at the critical point r=0 and in the Coulomb phase with r≠0. We calculate the specific heat and susceptibility of the system at r=0 and r≠0, which can help to detect the quantum critical point and to judge whether dynamical fermion mass generation takes place.

Naturalness Reach of the Large Hadron Collider in Minimal Supergravity

CERN Document Server

Allanach, B.C.; Parker, Michael Andrew; Webber, B.R.

2000-01-01

We re-analyse the prospects of discovering supersymmetry at the LHC, in order to re-express coverage in terms of a fine-tuning parameter and to extend the analysis to scalar masses (m_0) above 2 TeV. We use minimal supergravity (mSUGRA) unification assumptions for the SUSY breaking parameters. Such high values of m_0 have recently been found to have a focus point, leading to relatively low fine-tuning. In addition, improvements in the simulations since the last study mean that this region no longer lacks radiative electroweak symmetry breaking. The best fine tuning reach is found in a mono-leptonic channel, where for mu>0, A_0=0 and tan beta=10 (corresponding to the focus point), all points in mSUGRA with m_0 < 4000 GeV, with a fine tuning measure up to 300 (570) are covered by the search, where the definition of fine-tuning excludes (includes) the contribution from the top Yukawa coupling. Even for arbitrarily high m_0, mSUGRA does not evade detection provided the gaugino mass parameter M_{1/2} < 460 G...

An investigation of the neural circuits underlying reaching and reach-to-grasp movements: from planning to execution.

Directory of Open Access Journals (Sweden)

Chiara eBegliomini

2014-09-01

Full Text Available Experimental evidence suggests the existence of a sophisticated brain circuit specifically dedicated to reach-to-grasp planning and execution, both in human and non human primates (Castiello, 2005. Studies accomplished by means of neuroimaging techniques suggest the hypothesis of a dichotomy between a reach-to-grasp circuit, involving the intraparietal area (AIP, the dorsal and ventral premotor cortices (PMd and PMv - Castiello and Begliomini, 2008; Filimon, 2010 and a reaching circuit involving the medial intraparietal area (mIP and the Superior Parieto-Occipital Cortex (SPOC (Culham et al., 2006. However, the time course characterizing the involvement of these regions during the planning and execution of these two types of movements has yet to be delineated. A functional magnetic resonance imaging (fMRI study has been conducted, including reach-to grasp and reaching only movements, performed towards either a small or a large stimulus, and Finite Impulse Response model (FIR - Henson, 2003 was adopted to monitor activation patterns from stimulus onset for a time window of 10 seconds duration. Data analysis focused on brain regions belonging either to the reaching or to the grasping network, as suggested by Castiello & Begliomini (2008.Results suggest that reaching and grasping movements planning and execution might share a common brain network, providing further confirmation to the idea that the neural underpinnings of reaching and grasping may overlap in both spatial and temporal terms (Verhagen et al., 2013.

Physics reach of MoEDAL at LHC: magnetic monopoles, supersymmetry and beyond

Directory of Open Access Journals (Sweden)

Mavromatos Nick E.

2017-01-01

Full Text Available MoEDAL is a pioneering experiment designed to search for highly ionising messengers of new physics such as magnetic monopoles or massive (pseudo-stable charged particles, that are predicted to exist in a plethora of models beyond the Standard Model. Its ground-breaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as, are there extra dimensions or new symmetries, what is the mechanism for the generation of mass, does magnetic charge exist, what is the nature of dark matter, and, how did the big-bang develop at the earliest times. MoEDAL’s purpose is to meet such far-reaching challenges at the frontier of the field. The physics reach of the existing MoEDAL detector is discussed, giving emphasis on searches for magnetic monopoles, supersymmetric (semistable partners, doubly charged Higgs bosons, and exotic structures such as black-hole remnants in models with large extra spatial dimensions and D-matter in some brane theories.

Physics reach of MoEDAL at LHC: magnetic monopoles, supersymmetry and beyond

Science.gov (United States)

Mavromatos, Nick E.; Mitsou, Vasiliki A.

2017-12-01

MoEDAL is a pioneering experiment designed to search for highly ionising messengers of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles, that are predicted to exist in a plethora of models beyond the Standard Model. Its ground-breaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as, are there extra dimensions or new symmetries, what is the mechanism for the generation of mass, does magnetic charge exist, what is the nature of dark matter, and, how did the big-bang develop at the earliest times. MoEDAL's purpose is to meet such far-reaching challenges at the frontier of the field. The physics reach of the existing MoEDAL detector is discussed, giving emphasis on searches for magnetic monopoles, supersymmetric (semi)stable partners, doubly charged Higgs bosons, and exotic structures such as black-hole remnants in models with large extra spatial dimensions and D-matter in some brane theories.

Researches on nuclear criticality safety evaluation

Energy Technology Data Exchange (ETDEWEB)

Okuno, Hiroshi; Suyama, Kenya; Nomura, Yasushi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2003-10-01

For criticality safety evaluation of burnup fuel, the general-purpose burnup calculation code, SWAT, was revised, and its precision was confirmed through comparison with other results from OECD/NEA's burnup credit benchmarks. Effect by replacing the evaluated nuclear data from JENDL-3.2 to ENDF/B-VI and JEF-2.2 was also studied. Correction factors were derived for conservative evaluation of nuclide concentrations obtained with the simplified burnup code ORIGEN2.1. The critical masses of curium were calculated and evaluated for nuclear criticality safety management of minor actinides. (author)

Researches on nuclear criticality safety evaluation

International Nuclear Information System (INIS)

Okuno, Hiroshi; Suyama, Kenya; Nomura, Yasushi

2003-01-01

For criticality safety evaluation of burnup fuel, the general-purpose burnup calculation code, SWAT, was revised, and its precision was confirmed through comparison with other results from OECD/NEA's burnup credit benchmarks. Effect by replacing the evaluated nuclear data from JENDL-3.2 to ENDF/B-VI and JEF-2.2 was also studied. Correction factors were derived for conservative evaluation of nuclide concentrations obtained with the simplified burnup code ORIGEN2.1. The critical masses of curium were calculated and evaluated for nuclear criticality safety management of minor actinides. (author)

Leptogenesis. Theory and neutrino masses

Energy Technology Data Exchange (ETDEWEB)

Buchmueller, W.

2012-12-15

After a brief discussion of baryon and lepton number nonconservation, we review the status of thermal leptogenesis with GUT scale neutrino masses, as well as low scale alternatives with keV neutrinos as dark matter and heavy neutrino masses within the reach of the LHC. Recent progress towards a full quantum mechanical description of leptogenesis is described with resonant leptogenesis as an application. Finally, cosmological B-L breaking after inflation is considered as origin of the hot early universe, generating entropy, baryon asymmetry and dark matter.

Expanding the reach of heavy neutrino searches at the LHC

Science.gov (United States)

Flórez, Andrés; Gui, Kaiwen; Gurrola, Alfredo; Patiño, Carlos; Restrepo, Diego

2018-03-01

The observation of neutrino oscillations establishes that neutrinos have non-zero mass and provides one of the more compelling arguments for physics beyond the standard model (SM) of particle physics. We present a feasibility study to search for hypothetical Majorana neutrinos (N) with TeV scale masses, predicted by extensions of the SM to explain the small but non-zero SM neutrino mass, using vector boson fusion (VBF) processes at the 13 TeV LHC. In the context of the minimal Type-I seesaw mechanism (mTISM), the VBF production cross-section of a lepton (ℓ) and associated heavy Majorana neutrino (Nℓ) surpasses that of the Drell-Yan process at approximately mNℓ = 1.4TeV. We consider second and third-generation heavy neutrino (Nμ or Nτ, where ℓ= muon (μ) or tau (τ) leptons) production through VBF processes, with subsequent Nμ and Nτ decays to a lepton and two jets, as benchmark cases to show the effectiveness of the VBF topology for Nℓ searches at the 13 TeV LHC. The requirement of a dilepton pair combined with four jets, two of which are identified as VBF jets with large separation in pseudorapidity and a TeV scale dijet mass, is effective at reducing the SM background. These criteria may provide expected exclusion bounds, at 95% confidence level, of mNℓ < 1.7 (2.4) TeV, assuming 100 (1000) fb-1 of 13 TeV data from the LHC and mixing |VℓNℓ|2 = 1. The use of the VBF topology to search for mNℓ increases the discovery reach at the LHC, with expected significances greater than 5σ (3σ) for Nℓ masses up to 1.7 (2.05) TeV using 1000fb-1 of 13 TeV data from the LHC.

Expanding the reach of heavy neutrino searches at the LHC

Directory of Open Access Journals (Sweden)

Andrés Flórez

2018-03-01

Full Text Available The observation of neutrino oscillations establishes that neutrinos have non-zero mass and provides one of the more compelling arguments for physics beyond the standard model (SM of particle physics. We present a feasibility study to search for hypothetical Majorana neutrinos (N with TeV scale masses, predicted by extensions of the SM to explain the small but non-zero SM neutrino mass, using vector boson fusion (VBF processes at the 13 TeV LHC. In the context of the minimal Type-I seesaw mechanism (mTISM, the VBF production cross-section of a lepton (ℓ and associated heavy Majorana neutrino (Nℓ surpasses that of the Drell–Yan process at approximately mNℓ=1.4TeV. We consider second and third-generation heavy neutrino (Nμ or Nτ, where ℓ= muon (μ or tau (τ leptons production through VBF processes, with subsequent Nμ and Nτ decays to a lepton and two jets, as benchmark cases to show the effectiveness of the VBF topology for Nℓ searches at the 13 TeV LHC. The requirement of a dilepton pair combined with four jets, two of which are identified as VBF jets with large separation in pseudorapidity and a TeV scale dijet mass, is effective at reducing the SM background. These criteria may provide expected exclusion bounds, at 95% confidence level, of mNℓ<1.7 (2.4 TeV, assuming 100 (1000 fb−1 of 13 TeV data from the LHC and mixing |VℓNℓ|2=1. The use of the VBF topology to search for mNℓ increases the discovery reach at the LHC, with expected significances greater than 5σ (3σ for Nℓ masses up to 1.7 (2.05 TeV using 1000fb−1 of 13 TeV data from the LHC.

Antithrombin III for critically ill patients

DEFF Research Database (Denmark)

Allingstrup, Mikkel; Wetterslev, Jørn; Ravn, Frederikke B

2016-01-01

PURPOSE: Antithrombin III (AT III) is an anticoagulant with anti-inflammatory properties. We assessed the benefits and harms of AT III in critically ill patients. METHODS: We searched from inception to 27 August 2015 in CENTRAL, MEDLINE, EMBASE, CAB, BIOSIS and CINAHL. We included randomized...... participants). However, for all other outcome measures and analyses, the results did not reach statistical significance. CONCLUSIONS: There is insufficient evidence to support AT III substitution in any category of critically ill participants including those with sepsis and DIC. AT III did not show an impact...

Higgs inflation at the critical point

CERN Document Server

Bezrukov, Fedor

2014-01-01

Higgs inflation can occur if the Standard Model (SM) is a self-consistent effective field theory up to inflationary scale. This leads to a lower bound on the Higgs boson mass, $M_h \\geq M_{\\text{crit}}$. If $M_h$ is more than a few hundreds of MeV above the critical value, the Higgs inflation predicts the universal values of inflationary indexes, $r\\simeq 0.003$ and $n_s\\simeq 0.97$, independently on the Standard Model parameters. We show that in the vicinity of the critical point $M_{\\text{crit}}$ the inflationary indexes acquire an essential dependence on the mass of the top quark $m_t$ and $M_h$. In particular, the amplitude of the gravitational waves can exceed considerably the universal value.

Theoretical resolving power of a radiofrequency mass spectrometer

International Nuclear Information System (INIS)

Coc, A.; Le Gac, R.; Saint Simon, M. de; Thibault, C.; Touchard, F.

1988-01-01

Radiofrequency mass spectrometers of L.G. Smith's type can reach a resolving power of 10 6 -10 7 and a precision of 10 -9 -10 -10 . The resolving power, shape of peaks and limitations are described. As an example, the spectrometer to be used in an experiment aimed at measuring the anti p/p mass ratio is considered. (orig.)

Space weather and coronal mass ejections

CERN Document Server

Howard, Tim

2013-01-01

Space weather has attracted a lot of attention in recent times. Severe space weather can disrupt spacecraft, and on Earth can be the cause of power outages and power station failure. It also presents a radiation hazard for airline passengers and astronauts. These ""magnetic storms"" are most commonly caused by coronal mass ejections, or CMES, which are large eruptions of plasma and magnetic field from the Sun that can reach speeds of several thousand km/s. In this SpringerBrief, Space Weather and Coronal Mass Ejections, author Timothy Howard briefly introduces the coronal mass ejection, its sc

REACH: impact on the US cosmetics industry?

Science.gov (United States)

Pouillot, Anne; Polla, Barbara; Polla, Ada

2009-03-01

The Registration, Evaluation, Authorization and restriction of Chemicals (REACH) is a recent European regulation on chemical substances meant to protect human health and the environment. REACH imposes the "precautionary principle" where additional data and definitive action are required when uncertainty is identified. The cosmetics industry is only partially concerned by REACH: while the stages of registration and evaluation apply to cosmetics, those of authorization and restriction most likely will not, as cosmetic ingredients are already subject to regulation by various agencies and directives. REACH has potential benefits to the industry including the possibility of reassuring consumers and improving their image of chemicals and cosmetics. However, REACH also has potential disadvantages, mainly with regard to impeding innovation. The American cosmetics industry will be affected by REACH, because all US manufacturers who export substances to Europe will have to fully comply with REACH.

Critical pressure of non-equilibrium two-phase critical flow

Energy Technology Data Exchange (ETDEWEB)

Minzer, U [Israel Electric Corp. Ltd., Haifa (Israel)

1996-12-01

Critical pressure is defined as the pressure existing at the exit edge of the piping, when it remains constant despite a decrease in the back. According to this definition the critical pressure is larger than the back pressure and for two-phase conditions below saturation pressure. The two-phase critical pressure has a major influence on the two-phase critical flow characteristics. Therefore it is of High significance in calculations of critical mass flux and critical depressurization rate, which are important in the fields of Nuclear Reactor Safety and Industrial Safety. At the Nuclear Reactor Safety field is useful for estimations of the Reactor Cooling System depressurization, the core coolant level, and the pressure build-up in the containment. In the Industrial Safety field it is helpful for estimating the leakage rate of toxic gases Tom liquefied gas pressure vessels, depressurization of pressure vessels, and explosion conditions due to liquefied gas release. For physical description of non-equilibrium two-phase critical flow it would be convenient to divide the flow into two stages. The first stage is the flow of subcooled liquid at constant temperature and uniform pressure drop (i.e., the case of incompressible fluid and uniform piping cross section). The rapid flow of the liquid causes a delay in the boiling of the liquid, which begins to boil below saturation pressure, at thermal non-equilibrium. The boiling is the beginning of the second stage, characterized by a sharp increase of the pressure drop. The liquid temperature on the second stage is almost constant because most of the energy for vaporization is supplied from the large pressure drop The present work will focus on the two-phase critical pressure of water, since water serves as coolant in the vast majority of nuclear power reactors throughout the world. (author).

Critical pressure of non-equilibrium two-phase critical flow

International Nuclear Information System (INIS)

Minzer, U.

1996-01-01

Critical pressure is defined as the pressure existing at the exit edge of the piping, when it remains constant despite a decrease in the back. According to this definition the critical pressure is larger than the back pressure and for two-phase conditions below saturation pressure. The two-phase critical pressure has a major influence on the two-phase critical flow characteristics. Therefore it is of High significance in calculations of critical mass flux and critical depressurization rate, which are important in the fields of Nuclear Reactor Safety and Industrial Safety. At the Nuclear Reactor Safety field is useful for estimations of the Reactor Cooling System depressurization, the core coolant level, and the pressure build-up in the containment. In the Industrial Safety field it is helpful for estimating the leakage rate of toxic gases Tom liquefied gas pressure vessels, depressurization of pressure vessels, and explosion conditions due to liquefied gas release. For physical description of non-equilibrium two-phase critical flow it would be convenient to divide the flow into two stages. The first stage is the flow of subcooled liquid at constant temperature and uniform pressure drop (i.e., the case of incompressible fluid and uniform piping cross section). The rapid flow of the liquid causes a delay in the boiling of the liquid, which begins to boil below saturation pressure, at thermal non-equilibrium. The boiling is the beginning of the second stage, characterized by a sharp increase of the pressure drop. The liquid temperature on the second stage is almost constant because most of the energy for vaporization is supplied from the large pressure drop The present work will focus on the two-phase critical pressure of water, since water serves as coolant in the vast majority of nuclear power reactors throughout the world. (author)

Rural Embedded Assistants for Community Health (REACH) network: first-person accounts in a community-university partnership.

Science.gov (United States)

Brown, Louis D; Alter, Theodore R; Brown, Leigh Gordon; Corbin, Marilyn A; Flaherty-Craig, Claire; McPhail, Lindsay G; Nevel, Pauline; Shoop, Kimbra; Sterner, Glenn; Terndrup, Thomas E; Weaver, M Ellen

2013-03-01

Community research and action projects undertaken by community-university partnerships can lead to contextually appropriate and sustainable community improvements in rural and urban localities. However, effective implementation is challenging and prone to failure when poorly executed. The current paper seeks to inform rural community-university partnership practice through consideration of first-person accounts from five stakeholders in the Rural Embedded Assistants for Community Health (REACH) Network. The REACH Network is a unique community-university partnership aimed at improving rural health services by identifying, implementing, and evaluating innovative health interventions delivered by local caregivers. The first-person accounts provide an insider's perspective on the nature of collaboration. The unique perspectives identify three critical challenges facing the REACH Network: trust, coordination, and sustainability. Through consideration of the challenges, we identified several strategies for success. We hope readers can learn their own lessons when considering the details of our partnership's efforts to improve the delivery infrastructure for rural healthcare.

Naturalness and superpartner masses or when to give up on weak scale supersymmetry

International Nuclear Information System (INIS)

Anderson, G.W.; Castano, D.J.

1995-01-01

Superpartner masses cannot be arbitrarily heavy if supersymmetric extensions of the standard model explain the stability of the gauge hierarchy. This ancient and hallowed motivation for weak scale supersymmetry is often quoted, yet no reliable determination of this upper limit on superpartner masses exists. In this paper we compute upper bounds on superpartner masses in the minimal supersymmetric model, and we identify which values of the superpartner masses correspond to the most natural explanation of the hierarchy stability. We compare the most natural value of these masses and their upper limits to the physics reach of current and future colliders. As a result, we find that supersymmetry could explain weak scale stability naturally even if no superpartners are discovered at the CERN LEP II or the Fermilab Tevatron (even with the Main Injector upgrade). However, we find that supersymmetry cannot provide a complete explanation of weak scale stability, if squarks and gluinos have masses beyond the physics reach of the CERN LHC. Moreover, in the most natural scenarios, many sparticles, for example, charginos, squarks, and gluinos, lie within the physics reach of either LEP II or the Tevatron. Our analysis determines the most natural value of the chargino (squark) [(gluino)] mass consistent with current experimental constraints is ∼50 (250) [(250)] GeV and the corresponding theoretical upper bound is ∼250 (700) [(800)] GeV

Nuclear fission, chain reaction and criticality

International Nuclear Information System (INIS)

Reuss, Paul

2016-01-01

Criticality is, notably for nuclear reactors, the status which separates the case of a fission chain reaction which inexorably decays, from that of a reaction which grows faster and faster until a counter-reaction occurs. If this status is an objective in nuclear reactors, it must not be reached or exceeded in any case in other types of installations in which fissile materials are handled (fabrication, transports, nuclear fuel processing). The author proposes an insight into this notion of criticality, discusses elements of neutron science which allow the multiplication factor to be assessed, analyses accidental scenarios which may happen, and presents associated experiments and computation codes

Development of evaluation methods for impact of earthquake-induced slope failure on nearby critical structures. Analysis of behavior of collapsed rock masses using 3-D distinct element method

International Nuclear Information System (INIS)

Ishimaru, Makoto; Tochigi, Hitoshi; Nakajima, Masato; Shirai, Koji

2012-01-01

Recently, importance of evaluation for impact of earthquake-induced slope failure on nearby critical structures is increasing in order to evaluate seismic stability of the slope, in addition to evaluating the possibilities of slope failure. In this study, we presented an examination flow chart to evaluate the impact on structures after slope failure. In the examination flow chart, we assumed the following four considerations; (1) evaluation of the collapse region of the slope, (2) evaluation of behavior of the collapsed rock masses, (3) evaluation of the impact on the structures, (4) examination of the countermeasures. And, for the purpose of using three dimensional distinct element method (DEM) for evaluation of behavior of the collapsed rock masses, we firstly confirmed applicability of DEM to behavior of a mass hurtling down the slope by means of comparing with the model test results. Moreover, we clarified influence of initial position or restitution coefficient of rock masses on final traveling distance of collapsed rock masses. (author)

The Point Mass Concept

Directory of Open Access Journals (Sweden)

Lehnert B.

2011-04-01

Full Text Available A point-mass concept has been elaborated from the equations of the gravitational field. One application of these deductions results in a black hole configuration of the Schwarzschild type, having no electric charge and no angular momentum. The critical mass of a gravitational collapse with respect to the nuclear binding energy is found to be in the range of 0.4 to 90 solar masses. A second application is connected with the spec- ulation about an extended symmetric law of gravitation, based on the options of positive and negative mass for a particle at given positive energy. This would make masses of equal polarity attract each other, while masses of opposite polarity repel each other. Matter and antimatter are further proposed to be associated with the states of positive and negative mass. Under fully symmetric conditions this could provide a mechanism for the separation of antimatter from matter at an early stage of the universe.

The Point Mass Concept

Directory of Open Access Journals (Sweden)

Lehnert B.

2011-04-01

Full Text Available A point-mass concept has been elaborated from the equations of the gravitational field. One application of these deductions results in a black hole configuration of the Schwarzschild type, having no electric charge and no angular momentum. The critical mass of a gravitational collapse with respect to the nuclear binding energy is found to be in the range of 0.4 to 90 solar masses. A second application is connected with the speculation about an extended symmetric law of gravitation, based on the options of positive and negative mass for a particle at given positive energy. This would make masses of equal polarity attract each other, while masses of opposite polarity repel each other. Matter and antimatter are further proposed to be associated with the states of positive and negative mass. Under fully symmetric conditions this could provide a mechanism for the separation of antimatter from matter at an early stage of the universe.

Dynamical mass generation in QED with weak magnetic fields

International Nuclear Information System (INIS)

Ayala, A.; Rojas, E.; Bashir, A.; Raya, A.

2006-01-01

We study the dynamical generation of masses for fundamental fermions in quenched quantum electrodynamics in the presence of magnetic fields using Schwinger-Dyson equations. We show that, contrary to the case where the magnetic field is strong, in the weak field limit eB << m(0)2, where m(0) is the value of the dynamically generated mass in the absence of the magnetic field, masses are generated above a critical value of the coupling and that this value is the same as in the case with no magnetic field. We carry out a numerical analysis to study the magnetic field dependence of the mass function above critical coupling and show that in this regime the dynamically generated mass and the chiral condensate for the lowest Landau level increase proportionally to (eB)2

Competition and critical periods in spring sugar beet cultivation

Directory of Open Access Journals (Sweden)

Mansilla Martínez José

2015-12-01

Full Text Available High yields with low costs require that sugar beets be kept free of weeds, during critical periods, using labor or chemical treatments. Since the critical periods for this crop in Castilla - La Mancha (Spain are unknown, the first goal of this study was to determine the effect of early and late competition on yield. The second goal was to determine the critical periods, while taking into consideration the semiarid climatic conditions of this region. Two irrigation farms located in the province of Albacete are dedicated to sugar beet cultivation. These two farms were chosen to carry out the tests March (140,000-150,000 seeds ∙ ha-1 and harvested in October. Two simultaneous and complementary experiments were carried out in each year and farm. Two scenarios were considered with eight different treatments each. In the first one (With Weeds Until - WWU, plots were infested by weeds up to a certain date. In the second one (Free of Weeds Until - FWU, plots were kept free of weeds up to a certain date. For each test, a randomised experimental blocked field was designed and there were four repetitions, each of them containing eight elemental plots (12 m2. Each plot was weeded by hand or weeds were left to grow till a definite date.The results indicated that a 1% loss of yield was reached in the early competition after 14 days, while a loss of 5% was reached after a period of 41 days after it was infested. The results also indicated that in late competition, if a crop is kept clean for 124 days and it is infested afterwards, a 1% loss is reached. However, the loss increases to 5% if the plot is kept clean for 111 days. For a 1% loss the critical period is 110 days and 70 days for a 5% loss.

Legal Education: Critical of Contemporaneity

Directory of Open Access Journals (Sweden)

Patrícia Verônica Nunes Carvalho Sobral

2016-10-01

Full Text Available This study reflects on the Legal Education, considering the criticism of contemporaneity. To reach the goal, the text is divided into: Critical, idealization and reality of legal education; Professor  of  law  schools;  The  educational  legislation  Questions  of  legal  education methodology; Pedagogy and the law. The reading of the sources referred the thought inferences  about  the  teaching  of  law,  the  methodological  approach  and  the  didactic- pedagogic preparation, according to Associação Latino Americana de Metodologia do Ensino do Direito. Contributes to the continuity of academic debate in progress, it is a problem that concerns the professional higher education.

Contribution of Soil Fauna to Foliar Litter-Mass Loss in Winter in an Ecotone between Dry Valley and Montane Forest in the Upper Reaches of the Minjiang River.

Science.gov (United States)

Peng, Yan; Yang, Wanqin; Li, Jun; Wang, Bin; Zhang, Chuan; Yue, Kai; Wu, Fuzhong

2015-01-01

Litter decomposition during winter can provide essential nutrients for plant growth in the subsequent growing season, which plays important role in preventing the expansion of dry areas and maintaining the stability of ecotone ecosystems. However, limited information is currently available on the contributions of soil fauna to litter decomposition during winter in such ecosystems. Therefore, a field experiment that included litterbags with two different mesh sizes (0.04 mm and 3 mm) was conducted to investigate the contribution of soil fauna to the loss of foliar litter mass in winter from November 2013 to April 2014 along the upper reaches of the Minjiang River. Two litter types of the dominant species were selected in each ecosystem: cypress (Cupressus chengiana) and oak (Quercus baronii) in ecotone; cypress (Cupressus chengiana) and clovershrub (Campylotropis macrocarpa) in dry valley; and fir (Abies faxoniana) and birch (Betula albosinensis) in montane forest. Over one winter incubation, foliar litter lost 6.0%-16.1%, 11.4%-26.0%, and 6.4%-8.5% of initial mass in the ecotone, dry valley and montane forest, respectively. Soil fauna showed obvious contributions to the loss of foliar litter mass in all of the ecosystems. The highest contribution (48.5%-56.8%) was observed in the ecotone, and the lowest contribution (0.4%-25.8%) was observed in the montane forest. Compared with other winter periods, thawing period exhibited higher soil fauna contributions to litter mass loss in ecotone and dry valley, but both thawing period and freezing period displayed higher soil fauna contributions in montane forest. Statistical analysis demonstrated that the contribution of soil fauna was significantly correlated with temperature and soil moisture during the winter-long incubation. These results suggest that temperature might be the primary control factor in foliar litter decomposition, but more active soil fauna in the ecotone could contribute more in litter decomposition and

Contribution of Soil Fauna to Foliar Litter-Mass Loss in Winter in an Ecotone between Dry Valley and Montane Forest in the Upper Reaches of the Minjiang River.

Directory of Open Access Journals (Sweden)

Yan Peng

Full Text Available Litter decomposition during winter can provide essential nutrients for plant growth in the subsequent growing season, which plays important role in preventing the expansion of dry areas and maintaining the stability of ecotone ecosystems. However, limited information is currently available on the contributions of soil fauna to litter decomposition during winter in such ecosystems. Therefore, a field experiment that included litterbags with two different mesh sizes (0.04 mm and 3 mm was conducted to investigate the contribution of soil fauna to the loss of foliar litter mass in winter from November 2013 to April 2014 along the upper reaches of the Minjiang River. Two litter types of the dominant species were selected in each ecosystem: cypress (Cupressus chengiana and oak (Quercus baronii in ecotone; cypress (Cupressus chengiana and clovershrub (Campylotropis macrocarpa in dry valley; and fir (Abies faxoniana and birch (Betula albosinensis in montane forest. Over one winter incubation, foliar litter lost 6.0%-16.1%, 11.4%-26.0%, and 6.4%-8.5% of initial mass in the ecotone, dry valley and montane forest, respectively. Soil fauna showed obvious contributions to the loss of foliar litter mass in all of the ecosystems. The highest contribution (48.5%-56.8% was observed in the ecotone, and the lowest contribution (0.4%-25.8% was observed in the montane forest. Compared with other winter periods, thawing period exhibited higher soil fauna contributions to litter mass loss in ecotone and dry valley, but both thawing period and freezing period displayed higher soil fauna contributions in montane forest. Statistical analysis demonstrated that the contribution of soil fauna was significantly correlated with temperature and soil moisture during the winter-long incubation. These results suggest that temperature might be the primary control factor in foliar litter decomposition, but more active soil fauna in the ecotone could contribute more in litter

Self-organized criticality in fragmenting

DEFF Research Database (Denmark)

Oddershede, L.; Dimon, P.; Bohr, J.

1993-01-01

The measured mass distributions of fragments from 26 fractured objects of gypsum, soap, stearic paraffin, and potato show evidence of obeying scaling laws; this suggests the possibility of self-organized criticality in fragmenting. The probability of finding a fragment scales inversely to a power...

Testing the white dwarf mass-radius relationship with eclipsing binaries

Science.gov (United States)

Parsons, S. G.; Gänsicke, B. T.; Marsh, T. R.; Ashley, R. P.; Bours, M. C. P.; Breedt, E.; Burleigh, M. R.; Copperwheat, C. M.; Dhillon, V. S.; Green, M.; Hardy, L. K.; Hermes, J. J.; Irawati, P.; Kerry, P.; Littlefair, S. P.; McAllister, M. J.; Rattanasoon, S.; Rebassa-Mansergas, A.; Sahman, D. I.; Schreiber, M. R.

2017-10-01

We present high-precision, model-independent, mass and radius measurements for 16 white dwarfs in detached eclipsing binaries and combine these with previously published data to test the theoretical white dwarf mass-radius relationship. We reach a mean precision of 2.4 per cent in mass and 2.7 per cent in radius, with our best measurements reaching a precision of 0.3 per cent in mass and 0.5 per cent in radius. We find excellent agreement between the measured and predicted radii across a wide range of masses and temperatures. We also find the radii of all white dwarfs with masses less than 0.48 M⊙ to be fully consistent with helium core models, but they are on average 9 per cent larger than those of carbon-oxygen core models. In contrast, white dwarfs with masses larger than 0.52 M⊙ all have radii consistent with carbon-oxygen core models. Moreover, we find that all but one of the white dwarfs in our sample have radii consistent with possessing thick surface hydrogen envelopes (10-5 ≥ MH/MWD ≥ 10-4), implying that the surface hydrogen layers of these white dwarfs are not obviously affected by common envelope evolution.

Consistency assessment of rating curve data in various locations using Bidirectional Reach (BReach)

Science.gov (United States)

Van Eerdenbrugh, Katrien; Van Hoey, Stijn; Coxon, Gemma; Freer, Jim; Verhoest, Niko E. C.

2017-10-01

When estimating discharges through rating curves, temporal data consistency is a critical issue. In this research, consistency in stage-discharge data is investigated using a methodology called Bidirectional Reach (BReach), which departs from a (in operational hydrology) commonly used definition of consistency. A period is considered to be consistent if no consecutive and systematic deviations from a current situation occur that exceed observational uncertainty. Therefore, the capability of a rating curve model to describe a subset of the (chronologically sorted) data is assessed in each observation by indicating the outermost data points for which the rating curve model behaves satisfactorily. These points are called the maximum left or right reach, depending on the direction of the investigation. This temporal reach should not be confused with a spatial reach (indicating a part of a river). Changes in these reaches throughout the data series indicate possible changes in data consistency and if not resolved could introduce additional errors and biases. In this research, various measurement stations in the UK, New Zealand and Belgium are selected based on their significant historical ratings information and their specific characteristics related to data consistency. For each country, regional information is maximally used to estimate observational uncertainty. Based on this uncertainty, a BReach analysis is performed and, subsequently, results are validated against available knowledge about the history and behavior of the site. For all investigated cases, the methodology provides results that appear to be consistent with this knowledge of historical changes and thus facilitates a reliable assessment of (in)consistent periods in stage-discharge measurements. This assessment is not only useful for the analysis and determination of discharge time series, but also to enhance applications based on these data (e.g., by informing hydrological and hydraulic model

Particle acceleration in near critical density plasma

International Nuclear Information System (INIS)

Gu, Y.J.; Kong, Q.; Kawata, S.; Izumiyama, T.; Nagashima, T.

2013-01-01

Charged particle acceleration schemes driven by ultra intense laser and near critical density plasma interactions are presented. They include electron acceleration in a plasma channel, ion acceleration by the Coulomb explosion and high energy electron beam driven ion acceleration. It is found that under the near critical density plasma both ions and electrons are accelerated with a high acceleration gradient. The electron beam containing a large charge quantity is accelerated well with 23 GeV/cm. The collimated ion bunch reaches 1 GeV. The investigations and discussions are based on 2.5D PIC (particle-in-cell) simulations. (author)

Results of the critical experiments concerning OTTO loading at the critical HTR-test facility KAHTER

International Nuclear Information System (INIS)

Drueke, V.; Litzow, W.; Paul, N.

1982-12-01

Critical experiments concerning OTTO loading are described. In the KAHTER facility an OTTO loading has been simulated, therefore the original KAHTER assembly was reconstructed. The determination of critical masses and reactivity worths of control rods and of additional absorber rods in the top reflector and in the upper cavity was of main interest for comparison with reactor following calculations. Besides this, reaction rates in different energy regions were measured in the upper part of the core, in the cavity and top reflector. (orig.) [de

Mass formula for quasi-black holes

International Nuclear Information System (INIS)

Lemos, Jose P. S.; Zaslavskii, Oleg B.

2008-01-01

A quasi-black hole, either nonextremal or extremal, can be broadly defined as the limiting configuration of a body when its boundary approaches the body's quasihorizon. We consider the mass contributions and the mass formula for a static quasi-black hole. The analysis involves careful scrutiny of the surface stresses when the limiting configuration is reached. It is shown that there exists a strict correspondence between the mass formulas for quasi-black holes and pure black holes. This perfect parallelism exists in spite of the difference in derivation and meaning of the formulas in both cases. For extremal quasi-black holes the finite surface stresses give zero contribution to the total mass. This leads to a very special version of Abraham-Lorentz electron in general relativity in which the total mass has pure electromagnetic origin in spite of the presence of bare stresses.

Autoclave nuclear criticality safety analysis

Energy Technology Data Exchange (ETDEWEB)

D`Aquila, D.M. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States); Tayloe, R.W. Jr. [Battelle, Columbus, OH (United States)

1991-12-31

Steam-heated autoclaves are used in gaseous diffusion uranium enrichment plants to heat large cylinders of UF{sub 6}. Nuclear criticality safety for these autoclaves is evaluated. To enhance criticality safety, systems are incorporated into the design of autoclaves to limit the amount of water present. These safety systems also increase the likelihood that any UF{sub 6} inadvertently released from a cylinder into an autoclave is not released to the environment. Up to 140 pounds of water can be held up in large autoclaves. This mass of water is sufficient to support a nuclear criticality when optimally combined with 125 pounds of UF{sub 6} enriched to 5 percent U{sup 235}. However, water in autoclaves is widely dispersed as condensed droplets and vapor, and is extremely unlikely to form a critical configuration with released UF{sub 6}.

Existing equations to estimate lean body mass are not accurate in the critically ill: Results of a multicenter observational study.

Science.gov (United States)

Moisey, Lesley L; Mourtzakis, Marina; Kozar, Rosemary A; Compher, Charlene; Heyland, Daren K

2017-12-01

Lean body mass (LBM), quantified using computed tomography (CT), is a significant predictor of clinical outcomes in the critically ill. While CT analysis is precise and accurate in measuring body composition, it may not be practical or readily accessible to all patients in the intensive care unit (ICU). Here, we assessed the agreement between LBM measured by CT and four previously developed equations that predict LBM using variables (i.e. age, sex, weight, height) commonly recorded in the ICU. LBM was calculated in 327 critically ill adults using CT scans, taken at ICU admission, and 4 predictive equations (E1-4) that were derived from non-critically adults since there are no ICU-specific equations. Agreement was assessed using paired t-tests, Pearson's correlation coefficients and Bland-Altman plots. Median LBM calculated by CT was 45 kg (IQR 37-53 kg) and was significantly different (p LBM (error ranged from 7.5 to 9.9 kg), compared with LBM calculated by CT, suggesting insufficient agreement. Our data indicates a large bias is present between the calculation of LBM by CT imaging and the predictive equations that have been compared here. This underscores the need for future research toward the development of ICU-specific equations that reliably estimate LBM in a practical and cost-effective manner. Copyright © 2016 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

CAST reaches milestone but keeps on searching

CERN Multimedia

CERN Courier (september 2011 issue)

2011-01-01

After eight years of searching for the emission of a dark matter candidate particle, the axion, from the Sun, the CERN Axion Solar Telescope (CAST) has fulfilled its original physics programme.   Members of the CAST collaboration in July, together with dipole-based helioscope. CAST, the world’s most sensitive axion helioscope, points a recycled prototype LHC dipole magnet at the Sun at dawn and dusk, looking for the conversion of axions to X-rays. It incorporates four state-of-the-art X-ray detectors: three Micromegas detectors and a pn-CCD imaging camera attached to a focusing X-ray telescope that was recovered from the German space programme (see CERN Courier April 2010).  Over the years, CAST has operated with the magnet bores - the location of the axion conversion - in different conditions: first in vacuum, covering axion masses up to 20 meV/c2, and then with a buffer gas (4He and later 3He) at various densities, finally reaching the goal of 1.17 eV/c2 on 22 ...

Identification of Pathways Critical to Quorum Sensing and Virulence Induction

Energy Technology Data Exchange (ETDEWEB)

Ognibene, Ted J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Young, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Holtz-Morris, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Daley, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2009-02-27

Quorum sensing is a mode of intercellular communication between bacteria that allows them to collectively regulate behavior such as virulence, sporulation, motility and biofilm formation. It is mediated by bacterially synthesized, diffusible, signaling molecules (autoinducers) that increase in concentration as a bacterial population expands until a critical threshold concentration is reached. However, in most bacterial species that produce autoinducer molecules, the physiologic concentration of these molecules is unknown. Moreover, many bacterial species, including Y. pestis, produce an array of quorum sensing molecules and the physiologic concentration of each individual type of autoinducer molecule is not known. There is a need to accurately and precisely quantitate these molecules, as it may be that different types of autoinducer molecules have different effects on virulence in the bacterium. We focused our efforts on the construction of a platform to identify and quantitate autoinducer molecules using FTICR, ¹⁴C isotope labeling and accelerator mass spectrometry (AMS). Specifically, we focused on autoinducer-1 type molecules, acylhomoserine lactone (HSL), derived from S-adenosylmethionine (SAM).

Four critical facilities: their capabilities and programs

International Nuclear Information System (INIS)

Whitesides, G.E.

1980-01-01

Information is presented on the critical experiments facilities at Babcock and Wilcox, Lynchburg, Virginia; at Battelle Pacific Northwest Laboratory in Hanford, Washington; at Rockwell-International in Rocky Flats, Colorado; and at Los Alamos Scientific Laboratory in New Mexico. It is noted that the critical mass facilities which still exist in this country represent a bare minimum for maintaining a measurement program sufficient for meeting data requirements

The database for reaching experiments and models.

Directory of Open Access Journals (Sweden)

Ben Walker

Full Text Available Reaching is one of the central experimental paradigms in the field of motor control, and many computational models of reaching have been published. While most of these models try to explain subject data (such as movement kinematics, reaching performance, forces, etc. from only a single experiment, distinct experiments often share experimental conditions and record similar kinematics. This suggests that reaching models could be applied to (and falsified by multiple experiments. However, using multiple datasets is difficult because experimental data formats vary widely. Standardizing data formats promises to enable scientists to test model predictions against many experiments and to compare experimental results across labs. Here we report on the development of a new resource available to scientists: a database of reaching called the Database for Reaching Experiments And Models (DREAM. DREAM collects both experimental datasets and models and facilitates their comparison by standardizing formats. The DREAM project promises to be useful for experimentalists who want to understand how their data relates to models, for modelers who want to test their theories, and for educators who want to help students better understand reaching experiments, models, and data analysis.

Reach and get capability in a computing environment

Science.gov (United States)

Bouchard, Ann M [Albuquerque, NM; Osbourn, Gordon C [Albuquerque, NM

2012-06-05

A reach and get technique includes invoking a reach command from a reach location within a computing environment. A user can then navigate to an object within the computing environment and invoke a get command on the object. In response to invoking the get command, the computing environment is automatically navigated back to the reach location and the object copied into the reach location.

The Dependence of CNT Aerogel Synthesis on Sulfur-driven Catalyst Nucleation Processes and a Critical Catalyst Particle Mass Concentration.

Science.gov (United States)

Hoecker, Christian; Smail, Fiona; Pick, Martin; Weller, Lee; Boies, Adam M

2017-11-06

The floating catalyst chemical vapor deposition (FC-CVD) process permits macro-scale assembly of nanoscale materials, enabling continuous production of carbon nanotube (CNT) aerogels. Despite the intensive research in the field, fundamental uncertainties remain regarding how catalyst particle dynamics within the system influence the CNT aerogel formation, thus limiting effective scale-up. While aerogel formation in FC-CVD reactors requires a catalyst (typically iron, Fe) and a promotor (typically sulfur, S), their synergistic roles are not fully understood. This paper presents a paradigm shift in the understanding of the role of S in the process with new experimental studies identifying that S lowers the nucleation barrier of the catalyst nanoparticles. Furthermore, CNT aerogel formation requires a critical threshold of Fe x C y  > 160 mg/m 3 , but is surprisingly independent of the initial catalyst diameter or number concentration. The robustness of the critical catalyst mass concentration principle is proved further by producing CNTs using alternative catalyst systems; Fe nanoparticles from a plasma spark generator and cobaltocene and nickelocene precursors. This finding provides evidence that low-cost and high throughput CNT aerogel routes may be achieved by decoupled and enhanced catalyst production and control, opening up new possibilities for large-scale CNT synthesis.

Proximal versus distal control of two-joint planar reaching movements in the presence of neuromuscular noise.

Science.gov (United States)

Nguyen, Hung P; Dingwell, Jonathan B

2012-06-01

Determining how the human nervous system contends with neuro-motor noise is vital to understanding how humans achieve accurate goal-directed movements. Experimentally, people learning skilled tasks tend to reduce variability in distal joint movements more than in proximal joint movements. This suggests that they might be imposing greater control over distal joints than proximal joints. However, the reasons for this remain unclear, largely because it is not experimentally possible to directly manipulate either the noise or the control at each joint independently. Therefore, this study used a 2 degree-of-freedom torque driven arm model to determine how different combinations of noise and/or control independently applied at each joint affected the reaching accuracy and the total work required to make the movement. Signal-dependent noise was simultaneously and independently added to the shoulder and elbow torques to induce endpoint errors during planar reaching. Feedback control was then applied, independently and jointly, at each joint to reduce endpoint error due to the added neuromuscular noise. Movement direction and the inertia distribution along the arm were varied to quantify how these biomechanical variations affected the system performance. Endpoint error and total net work were computed as dependent measures. When each joint was independently subjected to noise in the absence of control, endpoint errors were more sensitive to distal (elbow) noise than to proximal (shoulder) noise for nearly all combinations of reaching direction and inertia ratio. The effects of distal noise on endpoint errors were more pronounced when inertia was distributed more toward the forearm. In contrast, the total net work decreased as mass was shifted to the upper arm for reaching movements in all directions. When noise was present at both joints and joint control was implemented, controlling the distal joint alone reduced endpoint errors more than controlling the proximal joint

Did public health travel advice reach EURO 2012 football fans? A social network survey.

Science.gov (United States)

Janiec, J; Zielicka-Hardy, A; Polkowska, A; Rogalska, J; Sadkowska-Todys, M

2012-08-02

We posted a survey on the Union of European Football Associations (UEFA)’s EURO 2012 Facebook profile to evaluate whether public health travel advice, specifically on the importance of measles vaccination,reached fans attending EURO 2012. Responses suggested that these messages were missed by 77% of fans. Social networks could serve as innovative platforms to conduct surveys, enabling rapid access to target populations at low cost and could be of use during upcoming mass gatherings such as the Olympics.

RA-8 brief description. Critical set for CAREM project

International Nuclear Information System (INIS)

Boado, H.; Girardi, A.

1990-01-01

A RA-8 critical set, intended to study the core's neutronic characteristics for the CAREM project, is described. The description is a design criteria synthesis of the plant's main systems, its use in the project and the experimental purposes to be reached. (Author) [es

Audience reach of science on television in 10 European countries: An analysis of people-meter data.

Science.gov (United States)

Lehmkuhl, Markus; Boyadjieva, Pepka; Cunningham, Yvonne; Karamanidou, Christina; Mörä, Tuomo

2016-02-01

Beginning with a differentiation of science programmes into five different editorial concepts, this article explores the audience reach of science on television in 10 European countries with a special emphasis on young audiences aged between 14 and 29 years. In relation to the share of this age group in the entire population, science programmes in all countries reach a considerably smaller proportion of younger viewers. Specific preferences for science content on television do not seem to be relevant in explaining aggregated viewing behaviours especially of young audiences. Unlike all other segments, the young science viewer segment is almost intangible as an aggregated group, as a definable segment of a mass audience that can be targeted by science programme makers. © The Author(s) 2014.

Open Source Software Tool Skyline Reaches Key Agreement with Mass Spectrometer Vendors | Office of Cancer Clinical Proteomics Research

Science.gov (United States)

The full proteomics analysis of a small tumor sample (similar in mass to a few grains of rice) produces well over 500 megabytes of unprocessed "raw" data when analyzed on a mass spectrometer (MS). Thus, for every proteomics experiment there is a vast amount of raw data that must be analyzed and interrogated in order to extract biological information. Moreover, the raw data output from different MS vendors are generally in different formats inhibiting the ability of labs to productively work together.

Mass deformed ABJM theory on three sphere in large N limit

Energy Technology Data Exchange (ETDEWEB)

Nosaka, Tomoki [Korea Institute for Advanced Study,Seoul 02455 (Korea, Republic of); Shimizu, Kazuma; Terashima, Seiji [Yukawa Institute for Theoretical Physics, Kyoto University,Kyoto 606-8502 (Japan)

2017-03-23

In this paper the free energy of the mass deformed ABJM theory on S{sup 3} in the large N limit is studied. We find a new solution of the large N saddle point equation which exists for an arbitrary value of the mass parameter, and compute the free energies for these solutions. We also show that the solution corresponding to an asymptotically AdS{sub 4} geometry is singular at a certain value of the mass parameter and does not exist over this critical value. It is not clear that what is the gravity dual of the mass deformed ABJM theory on S{sup 3} for the mass parameter larger than the critical value.

Reaching the unreached.

Science.gov (United States)

Ariyaratne, A T

1989-01-01

Embodied in the child survival revolution are ideological, methodological, and organizational innovations aimed at radical change in the condition of the world's children as rapidly as possible. In countries such as Sri Lanka, child survival and health for all by the year 2000 often seem to be impossible goals, given the tumultuous socioeconomic and political conditions. In Sri Lanka, the quality of life has been eroded, not enhanced, by the importation of Western technology and managerial capitalism and the destruction of indigenous processes. The chaos and violence that have been brought into the country have made it difficult to reach the poor children, women, and refugees in rural areas with primary health care interventions. Sri Lanka's unreachable--the decision making elites--have blocked access to the unreached--the urban and rural poor. If governments are to reach the unreached, they must remove the obstacles to a people-centered, community development process. It is the people themselves, and the institutions of their creation, that can reach the children amidst them in greatest need. To achieve this task, local communities must be provided with basic human rights, the power to make decisions that affect their lives, necessary resources, and appropriate technologies. Nongovernmental organizations can play a crucial role as bridges between the unreached and the unreachable by promoting community empowerment, aiding in the formation of networks of community organizations, and establishing linkages with government programs. If the ruling elites in developing countries can be persuaded to accommodate the needs and aspirations of those who, to date, have been excluded from the development process, the child survival revolution can be a nonviolent one.

Probing grand unification with fermion masses, neutrino oscillations ...

Indian Academy of Sciences (India)

owing to the contributions from both the standard and the neutrino mass-relatedd =5 op- ..... framework emerges, which successfully accounts for a host of observed phenomena per- ...... conclusion reached by other authors (see especially ref.

SRTC criticality safety technical review: Nuclear Criticality Safety Evaluation 93-04 enriched uranium receipt

International Nuclear Information System (INIS)

Rathbun, R.

1993-01-01

Review of NMP-NCS-930087, open-quotes Nuclear Criticality Safety Evaluation 93-04 Enriched Uranium Receipt (U), July 30, 1993, close quotes was requested of SRTC (Savannah River Technology Center) Applied Physics Group. The NCSE is a criticality assessment to determine the mass limit for Engineered Low Level Trench (ELLT) waste uranium burial. The intent is to bury uranium in pits that would be separated by a specified amount of undisturbed soil. The scope of the technical review, documented in this report, consisted of (1) an independent check of the methods and models employed, (2) independent HRXN/KENO-V.a calculations of alternate configurations, (3) application of ANSI/ANS 8.1, and (4) verification of WSRC Nuclear Criticality Safety Manual procedures. The NCSE under review concludes that a 500 gram limit per burial position is acceptable to ensure the burial site remains in a critically safe configuration for all normal and single credible abnormal conditions. This reviewer agrees with that conclusion

Probabilistic Mass Growth Uncertainties

Science.gov (United States)

Plumer, Eric; Elliott, Darren

2013-01-01

Mass has been widely used as a variable input parameter for Cost Estimating Relationships (CER) for space systems. As these space systems progress from early concept studies and drawing boards to the launch pad, their masses tend to grow substantially, hence adversely affecting a primary input to most modeling CERs. Modeling and predicting mass uncertainty, based on historical and analogous data, is therefore critical and is an integral part of modeling cost risk. This paper presents the results of a NASA on-going effort to publish mass growth datasheet for adjusting single-point Technical Baseline Estimates (TBE) of masses of space instruments as well as spacecraft, for both earth orbiting and deep space missions at various stages of a project's lifecycle. This paper will also discusses the long term strategy of NASA Headquarters in publishing similar results, using a variety of cost driving metrics, on an annual basis. This paper provides quantitative results that show decreasing mass growth uncertainties as mass estimate maturity increases. This paper's analysis is based on historical data obtained from the NASA Cost Analysis Data Requirements (CADRe) database.

Video Games as Mass Art

Directory of Open Access Journals (Sweden)

Grant Tavinor

2011-01-01

Full Text Available Videogames are one of the most significant developments in the mass arts of recent times. In commercial terms, they are now among the most prominent of the mass arts worldwide. This commercial and cultural success does not exhaust the interest in videogames as a mass art phenomenon because games such as Grand Theft Auto IV and Fallout 3 are structurally radically different from previous forms of mass art. In particular, the ontology of videogames, the nature and identity of their works, and how they are instanced and evaluated is a departure from the familiar mass arts of film and popular music. This paper explores these differences in an attempt to fit videogames into a theory of mass art, but also to provide guidance on the issues of criticism and evaluation that surely follow from their ontological distinctiveness.

The influence of the entrance channel mass asymmetry on the reaction mechanism

International Nuclear Information System (INIS)

Agarwal, S.; Galin, J.; Gatty, B.; Guerreau, D.; Lefort, M.; Tarrago, X.; Babinet, R.; Girard, J.

1980-01-01

We have tried to investigate the influence of the entrance channel mass asymmetry on the reaction mechanisms associated with heavy ion collisions. Two systems, one very much asymmetric (O + Mo) and the other one almost symmetric (Cr + Fe), were studied in detail by measuring evaporation residues, deep inelastic collision products and fission fragments. An important fraction of the fragments observed in the Cr + Fe system exhibits all the characteristics of fission fragments. The analysis of these data seems to indicate that these fission like products are most likely emitted by a long lived composite system having not reached full statistical equilibrium for all the degrees of freedom. As a consequence, the fusion cross section for this symmetric system is too low as compared to predictions based on a critical distance approach for fusion, whereas the asymmetric system (O + Mo) is well understood in terms of the same model. (orig.)

Dynamic data-driven integrated flare model based on self-organized criticality

Science.gov (United States)

Dimitropoulou, M.; Isliker, H.; Vlahos, L.; Georgoulis, M. K.

2013-05-01

Context. We interpret solar flares as events originating in active regions that have reached the self-organized critical state. We describe them with a dynamic integrated flare model whose initial conditions and driving mechanism are derived from observations. Aims: We investigate whether well-known scaling laws observed in the distribution functions of characteristic flare parameters are reproduced after the self-organized critical state has been reached. Methods: To investigate whether the distribution functions of total energy, peak energy, and event duration follow the expected scaling laws, we first applied the previously reported static cellular automaton model to a time series of seven solar vector magnetograms of the NOAA active region 8210 recorded by the Imaging Vector Magnetograph on May 1 1998 between 18:59 UT and 23:16 UT until the self-organized critical state was reached. We then evolved the magnetic field between these processed snapshots through spline interpolation, mimicking a natural driver in our dynamic model. We identified magnetic discontinuities that exceeded a threshold in the Laplacian of the magnetic field after each interpolation step. These discontinuities were relaxed in local diffusion events, implemented in the form of cellular automaton evolution rules. Subsequent interpolation and relaxation steps covered all transitions until the end of the processed magnetograms' sequence. We additionally advanced each magnetic configuration that has reached the self-organized critical state (SOC configuration) by the static model until 50 more flares were triggered, applied the dynamic model again to the new sequence, and repeated the same process sufficiently often to generate adequate statistics. Physical requirements, such as the divergence-free condition for the magnetic field, were approximately imposed. Results: We obtain robust power laws in the distribution functions of the modeled flaring events with scaling indices that agree well

Criticality calculations for homogeneous mixtures of uranium and plutonium

International Nuclear Information System (INIS)

Spiegelberg, R. de S.H.

1981-05-01

Critical parameters were calculated using the one-dimensional multigroup transport theory. Calculations have been performed for water mixture of uranium metal and uranium oxides and plutonium nitrates to determine the dimensions of simple critical geometries (sphere and cylinder). The results of the calculations were plotted showing critical parameters (volume, radius or critical mass). The critical values obtained in Handbuch zur Kritikalitat were used to compare with critical parameters. A sensitivity study for the influences of mesh space size, multigroup structure and order of the S sub(n) approximation on the critical radius was carried out. The GAMTEC-II code was used to generate multigroup cross sections data. Critical radius were calculated using the one-dimensional multigroup transport code DTF-IV. (Author) [pt

A COMPARISON OF THE SIT-AND-REACH TEST AND THE BACK-SAVER SIT-AND-REACH TEST IN UNIVERSITY STUDENTS

Directory of Open Access Journals (Sweden)

Pedro A. López-Miñarro

2009-03-01

Full Text Available This study compares the forward reach score, spine and pelvis postures, and hamstring criterion-related validity (concurrent validity between the sit-and-reach test (SR and the back-saver sit-and-reach test (BS. Seventy-six men (mean age ± SD: 23.45 ± 3.96 years and 67 women (mean age ± SD: 23.85 ± 5.36 years were asked to perform three trials of SR, BS left (BSl, right (BSr, and passive straight leg raise (PSLR right and left (hamstring criterion measure in a randomized order. The thoracic, lumbar, and pelvis angles (measured with a Uni-level inclinometer and forward reach scores were recorded once the subjects reached forward as far as possible without flexing the knees. A repeated measure ANOVA was performed followed by Bonferroni´s post hoc test. Pearson correlation coefficients were used to define the relationships between SR and BS scores with respect to PSLR. In both men and women, the thoracic angle in BS was significantly greater than in SR (p<0.016. However, no significant differences were found between the tests in lumbar angle, pelvic angle, and forward reach scores. The concurrent validity of the forward reach score as a measure of hamstring extensibility was moderate in women (0.66 0. 76 and weak to moderate in men (0.51 0.59. The concurrent validity was slightly higher in SR than in BS, although no significant differences between the correlation values were observed. There were significant differences in the thoracic angle between the SR and BS, but not in the forward reach score. There was no difference in concurrent validity between the two tests. However, the traditional SR was preferred because it reached better concurrent validity than the BS

Measurements of saturation densities in critical region and critical loci for binary R-32/125 and R-125/143a systems

Energy Technology Data Exchange (ETDEWEB)

Kishizawa, G.; Sato, H.; Watanabe, K.

1999-05-01

R-32/125 (difluoromethane/pentafluoroethane) and R-125/143a (pentafluoroethane/1,1,1-trifluoroethane) binary systems are promising alternative refrigerants to replace conventional refrigerants, i.e., R-22 and R-502. The saturated vapor- and liquid-density data in the critical region of these mixtures were measured using the visual observation of the miniscus disappearance in an optical cell. For the R-32/125 system, 35 saturation density data were measured at three compositions, 10, 35, and 50 mass % R-32. Nineteen saturation density data were also measured for R-125/143a (50/50 mass %). The critical temperatures and densities for these binary refrigerants were determined by taking into consideration the level and location of the meniscus disappearance as well as the intensity of the critical opalescence. Correlations to represent the critical loci of these binary refrigerants for an entire range of compositions have been developed. The experimental uncertainties of the saturation density data are estimated to be within 9 mK in temperature and 0.5 to 5.0 kg{center{underscore}dot}m{sup {minus}3} in density. The uncertainties of the critical temperature and density are estimated to be within 12 to 14 mK and 4 to 8 kg{center{underscore}dot}m{sup {minus}3}, respectively.

Quark mass correction to the string potential

International Nuclear Information System (INIS)

Lambiase, G.; Nesterenko, V.V.

1995-01-01

A consistent method for calculating the interquark potential generated by the relativistic string with massive ends is proposed. In this approach the interquark potential in the model of the Nambu-Goto string with point-like masses at its ends is calculated. At first the calculation is done in the one-loop approximation and then the variational estimation is performed. The quark mass correction results in decreasing the critical distance (deconfinement radius). When quark mass decreases the critical distance also decreases. For obtaining a finite result under summation over eigenfrequencies of the Nambu-Goto string with massive ends a suitable mode-by-mode subtraction is proposed. This renormalization procedure proves to be completely unique. In the framework of the developed approach the one-loop interquark potential in the model of the relativistic string with rigidity is also calculated. 34 refs., 2 figs

CRITICALITY CURVES FOR PLUTONIUM HYDRAULIC FLUID MIXTURES

International Nuclear Information System (INIS)

WITTEKIND WD

2007-01-01

This Calculation Note performs and documents MCNP criticality calculations for plutonium (100% 239 Pu) hydraulic fluid mixtures. Spherical geometry was used for these generalized criticality safety calculations and three geometries of neutron reflection are: (sm b ullet)bare, (sm b ullet)1 inch of hydraulic fluid, or (sm b ullet)12 inches of hydraulic fluid. This document shows the critical volume and critical mass for various concentrations of plutonium in hydraulic fluid. Between 1 and 2 gallons of hydraulic fluid were discovered in the bottom of HA-23S. This HA-23S hydraulic fluid was reported by engineering to be Fyrquel 220. The hydraulic fluid in GLovebox HA-23S is Fyrquel 220 which contains phosphorus. Critical spherical geometry in air is calculated with 0 in., 1 in., or 12 inches hydraulic fluid reflection

Quantifying hyporheic exchange dynamics in a highly regulated large river reach.

Energy Technology Data Exchange (ETDEWEB)

Hammond, Glenn Edward; Zhou, T; Huang, M; Hou, Z; Bao, J; Arntzen, E; Mackley, R; Harding, S; Titzler, S; Murray, C; Perkins, W; Chen, X; Stegen, J; Thorne, P; Zachara, J

2017-03-01

Hyporheic exchange is an important mechanism taking place in riverbanks and riverbed sediments, where river water and shallow groundwater mix and interact with each other. The direction, magnitude, and residence time of the hyporheic flux that penetrates the river bed are critical for biogeochemical processes such as carbon and nitrogen cycling, and biodegradation of organic contaminants. Many approaches including field measurements and numerical methods have been developed to quantify the hyporheic exchanges in relatively small rivers. However, the spatial and temporal distributions of hyporheic exchanges in a large, regulated river reach remain less explored due to the large spatial domains, complexity of geomorphologic features and subsurface properties, and the great pressure gradient variations at the riverbed created by dam operations.

Sedimentation under variable shear stress at lower reach of the Rupnarayan River, West Bengal, India

Directory of Open Access Journals (Sweden)

Swapan Kumar Maity

2017-04-01

Full Text Available The lower reach of the Rupnarayan River has been deteriorated and incapacitated due to continuous sedimentation (26.57 million m3 shoaling in last 25 years. Attempts have been made to explain the causes and mechanisms of sedimentation in connection to the seasonal fluctuation of shear stress. River depth and water velocity was measured by echo-sounder and current meter respectively. Textural analysis of grains was done by sieving technique. Available and critical shear stress (N/m2 have been calculated following Du Boys (1879, Shield (1936 and Van Ledden (2003 formula. The lack of available energy to transport a particular grain size during low tide (in dry season is the main reason behind the rapid sedimentation in this area. Most of the places (>75% having negative deviation of shear stress (available shear stress lesser than critical shear stress, during low tide are characterized by deposition of sediments. The presence of mud (silt and clay above the critical limit (15% in some of the sediment samples generates the cohesive property, restricts sediments entrainment and invites sedimentation.

Correlation of superconductor strand, cable, and dipole critical currents in CBA magnets

International Nuclear Information System (INIS)

Tannenbaum, M.J.; Garber, M.; Sampson, W.B.

1982-01-01

A calibration between vendor critical current data for 0.0268'' diameter superconductor strand supplied to Fermilab, and the BNL 10 -12 Ωcm critical current specification is presented. Vendor critical current data for over 400 Fermilab type billets are shown, both as supplied by the vendor and converted to BNL units. Predictions of cable critical current are made using the sum of the critical currents of the 23 strands, where all strands from the same half billet are assigned the same critical current. The measured critical current shows excellent correlation to the predicted value and is approximately 14 +- 2 percent below it. Colliding Beam Accelerator (CBA) full length dipoles reach the conductor critical current limit, essentially without training. Magnet performance is predictable from the measured critical current of a short sample of cable to within 2%

Nuclear data for criticality safety

International Nuclear Information System (INIS)

Westfall, R.M.

1994-01-01

A brief overview is presented on emerging requirements for new criticality safety analyses arising from applications involving nuclear waste management, facility remediation, and the storage of nuclear weapons components. A derivation of criticality analyses from the specifications of national consensus standards is given. These analyses, both static and dynamic, define the needs for nuclear data. Integral data, used primarily for analytical validation, and differential data, used in performing the analyses, are listed, along with desirable margins of uncertainty. Examples are given of needs for additional data to address systems having intermediate neutron energy spectra and/or containing nuclides of intermediate mass number

Critical Amounts of Uranium Compounds

Science.gov (United States)

Konopinski, E.; Metropolis, N.; Teller, E.; Woods, L.

1943-03-19

The method of calculation of critical masses of oxides and fluorides of U is given. The geometry assumed is a sphere and the calculations hold only in the absence of hydrogenous materials. Calculations are carried out which are applicable to materials containing form 20 to 100% U{sup 235}. (T.R.H.)

Methodology to estimate variations in solar radiation reaching densely forested slopes in mountainous terrain.

Science.gov (United States)

Sypka, Przemysław; Starzak, Rafał; Owsiak, Krzysztof

2016-12-01

Solar radiation reaching densely forested slopes is one of the main factors influencing the water balance between the atmosphere, tree stands and the soil. It also has a major impact on site productivity, spatial arrangement of vegetation structure as well as forest succession. This paper presents a methodology to estimate variations in solar radiation reaching tree stands in a small mountain valley. Measurements taken in three inter-forest meadows unambiguously showed the relationship between the amount of solar insolation and the shading effect caused mainly by the contour of surrounding tree stands. Therefore, appropriate knowledge of elevation, aspect and tilt angles of the analysed planes had to be taken into consideration during modelling. At critical times, especially in winter, the diffuse and reflected components of solar radiation only reached some of the sites studied as the beam component of solar radiation was totally blocked by the densely forested mountain slopes in the neighbourhood. The cross-section contours and elevation angles of all obstructions are estimated from a digital surface model including both digital elevation model and the height of tree stands. All the parameters in a simplified, empirical model of the solar insolation reaching a given horizontal surface within the research valley are dependent on the sky view factor (SVF). The presented simplified, empirical model and its parameterisation scheme should be easily adaptable to different complex terrains or mountain valleys characterised by diverse geometry or spatial orientation. The model was developed and validated (R 2  = 0.92 , σ = 0.54) based on measurements taken at research sites located in the Silesian Beskid Mountain Range. A thorough understanding of the factors determining the amount of solar radiation reaching woodlands ought to considerably expand the knowledge of the water exchange balance within forest complexes as well as the estimation of site

Critical experiment study on uranyl nitrate solution experiment facility

International Nuclear Information System (INIS)

Zhu Qingfu; Shi Yongqian; Wang Jinrong

2005-01-01

The Uranyl Nitrate Solution Experiment Facility was constructed for the research on nuclear criticality safety. In this paper, the configuration of the facility is introduced; a series of critical experiments on uranyl nitrate solution is described later, which were performed for various uranium concentrations under different conditions, i.e. with or without neutron absorbers in the core and with or without water-reflector outside the core. Critical volume and the minimum 235U critical mass for different uranium concentrations are presented. Finally, theoretical analysis is made on the experimental results. (authors)

Social percolation and the influence of mass media

Science.gov (United States)

Proykova, Ana; Stauffer, Dietrich

2002-09-01

In the marketing model of Solomon and Weisbuch, people buy a product only if their neighbours tell them of its quality, and if this quality is higher than their own quality expectations. Now we introduce additional information from the mass media, which is analogous to the ghost field in percolation theory. The mass media shift the percolative phase transition observed in the model, and decrease the time after which the stationary state is reached.

Trends in James Baldwin Criticism 2010–13

Directory of Open Access Journals (Sweden)

D.Quentin Miller

2017-10-01

Full Text Available The acceleration of interest in Baldwin’s work and impact since 2010 shows no signs of diminishing. This resurgence has much to do with Baldwin—the richness and passionate intensity of his vision—and also something to do with the dedicated scholars who have pursued a variety of publication platforms to generate further interest in his work. The reach of Baldwin studies has grown outside the academy as well: Black Lives Matter demonstrations routinely feature quotations from Baldwin; Twitter includes a “Son of Baldwin” site; and Raoul Peck’s 2016 documentary, I Am Not Your Negro, has received considerable critical and popular interest. The years 2010–13 were a key period in moving past the tired old formula—that praised his early career and denigrated the works he wrote after 1963—into the new formula—positing Baldwin as a misunderstood visionary, a wide-reaching artist, and a social critic whose value we are only now beginning to appreciate. I would highlight four additional prominent trends that emerged between 2010 and 2013: a consideration of Baldwin in the contexts of film, drama, and music; understandings of Baldwin globally; Baldwin’s criticism of American institutions; and analyses of Baldwin’s work in conversation with other authors.

Criticality management of Tokai reprocessing facility

Energy Technology Data Exchange (ETDEWEB)

Nojiri, Ichiro [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan)

2001-01-01

In fuel cycle centers a number of equipment and vessels of various types and of complex design are used in several processes, i.e. dissolution of spent fuels, separation and storage of uranium and plutonium from fission products and transuranium elements. For each processes, Monte Carlo codes are frequently applied to manage the fuel criticality. Safety design depends largely on specific features of each facilities. The present report describes status of criticality management for main processes in Tokai Reprocessing Facility, JNC, and the criticality conditions specifically existing there. The guiding principle throughout consists of mass control, volume control, design (form) control, concentration control, and control due to employment of neutron poisons. (S. Ohno)

Consideration of criticality in a nuclear waste repository

International Nuclear Information System (INIS)

Rechard, R.P.; Sanchez, L.C.; Stockman, C.T.; Ramsey, J.L. Jr.; Martell, M.

1995-01-01

The preliminary criticality analysis that was done suggests that the possibility of achieving critical conditions cannot be easily ruled out without looking at the geochemical process of assembly or the dynamics of the operation of a critical assembly. The evaluation of a critical assembly requires an integrated, consistent approach that includes evaluating the following: (1) the alteration rates of the layers of the container and spent fuel, (2) the transport of fissile material or neutron absorbers, and (3) the assembly mechanisms that can achieve critical conditions. The above is a non-trivial analysis and preliminary work suggests that with the loading assumed, enough fissile mass will leach from the HEU multi-purpose canisters to support a criticality. In addition, the consequences of an unpressurized Oklo type criticality would be insignificant to the performance of an unsaturated, tuff repository

Planning of the Extended Reach well Dieksand 2; Planung der Extended Reach Bohrung Dieksand 2

Energy Technology Data Exchange (ETDEWEB)

Frank, U.; Berners, H. [RWE-DEA AG, Hamburg (Germany). Drilling Team Mittelplate und Dieksand; Hadow, A.; Klop, G.; Sickinger, W. [Wintershall AG Erdoelwerke, Barnstdorf (Germany); Sudron, K.

1998-12-31

The Mittelplate oil field is located 7 km offshore the town of Friedrichskoog. Reserves are estimated at 30 million tonnes of oil. At a production rate of 2,500 t/d, it will last about 33 years. The transport capacity of the offshore platform is limited, so that attempts were made to enhance production by constructing the extended reach borehole Dieksand 2. Details are presented. (orig.) [Deutsch] Das Erdoelfeld Mittelplate liegt am suedlichen Rand des Nationalparks Schleswig Holsteinisches Wattenmeer, ca. 7000 m westlich der Ortschaft Friedrichskoog. Die gewinnbaren Reserven betragen ca. 30 Millionen t Oel. Bei einer Foerderkapazitaet von 2.500 t/Tag betraegt die Foerderdauer ca. 33 Jahre. Aufgrund der begrenzten Transportkapazitaeten von der Insel, laesst sich durch zusaetzliche Bohrungen von der kuenstlichen Insel Mittelplate keine entscheidende Erhoehung der Foerderkapazitaet erzielen. Ab Sommer 1996 wurde erstmals die Moeglichkeit der Lagerstaettenerschliessung von Land untersucht. Ein im Mai 1997 in Hamburg etabliertes Drilling Team wurde mit der Aufgabe betraut, die Extended Reach Bohrung Dieksand 2 zu planen und abzuteufen. Die Planungsphasen fuer die Extended Reach Bohrung Dieksand 2 wurden aufgezeigt. Die fuer den Erfolg einer Extended Reach Bohrung wichtigen Planungsparameter wurden erlaeutert. Es wurden Wege gezeigt, wie bei diesem Projekt technische und geologische Risiken in der Planung mit beruecksichtigt und nach Beginn der Bohrung weiter bearbeitet werden koennen. (orig.)

The Critical Periphery in the Growth of Social Protests.

Science.gov (United States)

Barberá, Pablo; Wang, Ning; Bonneau, Richard; Jost, John T; Nagler, Jonathan; Tucker, Joshua; González-Bailón, Sandra

2015-01-01

Social media have provided instrumental means of communication in many recent political protests. The efficiency of online networks in disseminating timely information has been praised by many commentators; at the same time, users are often derided as "slacktivists" because of the shallow commitment involved in clicking a forwarding button. Here we consider the role of these peripheral online participants, the immense majority of users who surround the small epicenter of protests, representing layers of diminishing online activity around the committed minority. We analyze three datasets tracking protest communication in different languages and political contexts through the social media platform Twitter and employ a network decomposition technique to examine their hierarchical structure. We provide consistent evidence that peripheral participants are critical in increasing the reach of protest messages and generating online content at levels that are comparable to core participants. Although committed minorities may constitute the heart of protest movements, our results suggest that their success in maximizing the number of online citizens exposed to protest messages depends, at least in part, on activating the critical periphery. Peripheral users are less active on a per capita basis, but their power lies in their numbers: their aggregate contribution to the spread of protest messages is comparable in magnitude to that of core participants. An analysis of two other datasets unrelated to mass protests strengthens our interpretation that core-periphery dynamics are characteristically important in the context of collective action events. Theoretical models of diffusion in social networks would benefit from increased attention to the role of peripheral nodes in the propagation of information and behavior.

Teratology testing under REACH.

Science.gov (United States)

Barton, Steve

2013-01-01

REACH guidelines may require teratology testing for new and existing chemicals. This chapter discusses procedures to assess the need for teratology testing and the conduct and interpretation of teratology tests where required.

Detection of quantum critical points by a probe qubit.

Science.gov (United States)

Zhang, Jingfu; Peng, Xinhua; Rajendran, Nageswaran; Suter, Dieter

2008-03-14

Quantum phase transitions occur when the ground state of a quantum system undergoes a qualitative change when an external control parameter reaches a critical value. Here, we demonstrate a technique for studying quantum systems undergoing a phase transition by coupling the system to a probe qubit. It uses directly the increased sensibility of the quantum system to perturbations when it is close to a critical point. Using an NMR quantum simulator, we demonstrate this measurement technique for two different types of quantum phase transitions in an Ising spin chain.

Acute kidney injury in critically ill child.

Science.gov (United States)

Al-Jboor, Wejdan; Almardini, Reham; Al Bderat, Jwaher; Frehat, Mahdi; Al Masri, Hazem; Alajloni, Mohammad Saleh

2016-01-01

Acute kidney injury (AKI) is a common and serious complication in patients in the Pediatric Intensive Care Unit (PICU). We conducted this study to estimate the incidence and the mortality rate of AKI in critically ill children as well as to describe some other related factors. A retrospective study was conducted at PICU of Queen Rania Abdulla Children Hospital, Amman, Jordan for the period extending from May 2011 to June 2013. The medical records of all patients admitted during this period, and their demographic data were reviewed. Patients with AKI were identified, and management and outcomes were reviewed and analyzed. AKI was evaluated according to modified RIFLE criteria. Of the 372 patients admitted to PICU, 64 (17.2%) patients developed AKI. Of these 64 patients who had AKI, 28 (43.7%) patients reached RIFLE max of risk, 21 (32.8%) patients reached injury, and 15 (23.4%) reached failure. Mean Pediatric Risk of Mortality II score at admission was significantly higher in patients with AKI than those without P <0.001. The age ranged between one month and 14 years with the median age as 5.4 year. Thirty-five (54.7%) were males. Sepsis was the most common cause of AKI. The mortality rate in critically ill children without AKI was 58.7%, whereas increased in children with AKI to 73.4%. The mortality rate in patients who received renal replacement therapy was 71.4% and was higher (81.5%) in patients who received mechanical ventilation (95%, [confidence interval (CI)] 79.3-83.4%) and was significantly higher in patients with multi-organ system dysfunction 90.3% (95%, [CI] 88.7-92.5%). The incidence of AKI in critically ill children is high and increased their mortality rate and higher mortality seen in the younger age group, especially those below one year. High mortality rate was associated with multi-organ system dysfunction and the need for mechanical ventilation.

Criticality accident in uranium fuel processing plant. The estimation of the total number of fissions with related reactor physics parameters

International Nuclear Information System (INIS)

Nishina, Kojiro; Oyamatsu, Kazuhiro; Kondo, Shunsuke; Sekimoto, Hiroshi; Ishitani, Kazuki; Yamane, Yoshihiro; Miyoshi, Yoshinori

2000-01-01

This accident occurred when workers were pouring a uranium solution into a precipitation tank with handy operation against the established procedure and both the cylindrical diameter and the total mass exceeded the limited values. As a result, nuclear fission chain reactor in the solution reached not only a 'criticality' state continuing it independently but also an instantly forming criticality state exceed the criticality and increasing further nuclear fission number. The place occurring the accident at this time was not reactor but a place having not to form 'criticality' called by a processing process of uranium fuel. In such place, as because of relating to mechanism of chain reaction, it is required naturally for knowledge on the reactor physics, it is also necessary to understand chemical reaction in chemical process, and functions of tanks, valves and pumps mounted at the processes. For this purpose, some information on uranium concentration ratio, atomic density of nuclides largely affecting to chain reaction such as uranium, hydrogen, and so forth in the solution, shape, inner structure and size of container for the solution, and its temperature and total volume, were necessary for determining criticality volume of the accident uranium solution by using nuclear physics procedures. Here were described on estimation of energy emission in the JCO accident, estimation from analytical results on neutron and solution, calculation of various nuclear physics property estimation on the JCO precipitation tank at JAERI. (G.K.)

Application of the mass-based UNIQUAC model to membrane systems: A critical revision

International Nuclear Information System (INIS)

Chovau, S.; Van der Bruggen, B.; Luis, P.

2012-01-01

Highlights: ► UNIQUAC model in mass-based terms is considered for the description of sorption equilibria in membrane systems. ► Model validation of molar and mass-based model is performed on simple (vapor + liquid) equilibrium. ► Discrepancy is found between molar and mass-based model, which is attributed to an incorrect conversion. ► Novel model based on correct thermodynamics is provided for future research. - Abstract: The UNIQUAC model is very suitable in describing (liquid + liquid) as well as (vapor + liquid) equilibrium for a wide range of systems. It can be extended to (solvent + polymer) systems for describing sorption equilibria. The original model is expressed in molar-based terms, but requires knowledge of structural parameters and molar masses of all components. Since these cannot always be easily determined for membranes, a conversion to mass-based terms is often performed, which eliminates this issue. Many studies use this model to calculate sorption equilibria in (solvent + polymer) systems. Nevertheless, in this work the conversion from molar to mass-based parameters is postulated to be erroneous. This even leads to an incorrect description of simple (vapor + liquid) equilibrium of pure liquid mixtures and hence it is advised not to use this model for further modeling of sorption equilibrium in (solvent + polymer) systems. In this paper, the errors in the conversion are pinpointed, and the effects it can have on the description of (vapor + liquid) equilibrium, if used improvident, are demonstrated. Furthermore, it is shown that in fact a simple and straightforward conversion can be performed. Finally, in the case when polymers are involved, an adaption and simplification to the model was successfully applied.

Knudsen effusion mass spectrometry. Chapter 20

International Nuclear Information System (INIS)

Sai Baba, M.

1997-01-01

The Knudsen effusion mass spectrometric method for the determination of vapour pressures and thermodynamic properties is described. The aim of the article is to give a general introduction to the method rather than to give a critical review of the technique. The latest developments in this area of research are reviewed by the peers in the field during the triennial international mass spectrometric conferences. The Knudsen effusion mass spectrometric method is being applied for thermodynamic measurements. In recent times, laser vaporisation mass spectrometric methods have emerged as a source of determination of vapour pressures at very high temperatures and beyond the pressure regime far exceeding Knudsen effusion range

REACH: Evaluation Report and Executive Summary

Science.gov (United States)

Sibieta, Luke

2016-01-01

REACH is a targeted reading support programme designed to improve reading accuracy and comprehension in pupils with reading difficulties in Years 7 and 8. It is based on research by the Centre for Reading and Language at York and is delivered by specially trained teaching assistants (TAs). This evaluation tested two REACH interventions, one based…

Global reach and engagement

Science.gov (United States)

2016-09-01

Popular culture reflects both the interests of and the issues affecting the general public. As concerns regarding climate change and its impacts grow, is it permeating into popular culture and reaching that global audience?

Droplet size and velocity at the exit of a nozzle with two-component near critical and critical flow

International Nuclear Information System (INIS)

Lemonnier, H.; Camelo-Cavalcanti, E.S.

1993-01-01

Two-component critical flow modelling is an important issue for safety studies of various hazardous industrial activities. When the flow quality is high, the critical flow rate prediction is sensitive to the modelling of gas droplet mixture interfacial area. In order to improve the description of these flows, experiments were conducted with air-water flows in converging nozzles. The pressure was 2 and 4 bar and the gas mass quality ranged between 100% and 20%. The droplets size and velocity have been measured close to the outlet section of a nozzle with a 10 mm diameter throat. Subcritical and critical conditions were observed. These data are compared with the predictions of a critical flow model which includes an interfacial area model based on the classical ideas of Hinze and Kolmogorov. (authors). 9 figs., 12 refs

A Data-Driven, Integrated Flare Model Based on Self-Organized Criticality

Science.gov (United States)

Dimitropoulou, M.; Isliker, H.; Vlahos, L.; Georgoulis, M.

2013-09-01

We interpret solar flares as events originating in solar active regions having reached the self-organized critical state, by alternatively using two versions of an "integrated flare model" - one static and one dynamic. In both versions the initial conditions are derived from observations aiming to investigate whether well-known scaling laws observed in the distribution functions of characteristic flare parameters are reproduced after the self-organized critical state has been reached. In the static model, we first apply a nonlinear force-free extrapolation that reconstructs the three-dimensional magnetic fields from two-dimensional vector magnetograms. We then locate magnetic discontinuities exceeding a threshold in the Laplacian of the magnetic field. These discontinuities are relaxed in local diffusion events, implemented in the form of cellular-automaton evolution rules. Subsequent loading and relaxation steps lead the system to self-organized criticality, after which the statistical properties of the simulated events are examined. In the dynamic version we deploy an enhanced driving mechanism, which utilizes the observed evolution of active regions, making use of sequential vector magnetograms. We first apply the static cellular automaton model to consecutive solar vector magnetograms until the self-organized critical state is reached. We then evolve the magnetic field inbetween these processed snapshots through spline interpolation, acting as a natural driver in the dynamic model. The identification of magnetically unstable sites as well as their relaxation follow the same rules as in the static model after each interpolation step. Subsequent interpolation/driving and relaxation steps cover all transitions until the end of the sequence. Physical requirements, such as the divergence-free condition for the magnetic field vector, are approximately satisfied in both versions of the model. We obtain robust power laws in the distribution functions of the modelled

Why and how to make a REACH registration of combustion ash; Moejligheter vid REACH-registrering av energiaskor

Energy Technology Data Exchange (ETDEWEB)

Loevgren, Linnea; Wik, Ola

2009-10-15

The new chemical regulation, REACH (1997/2006/EC), Registration, Evaluation, Authorization and restriction of Chemicals, took effect the 1st of June 2007. The background to this report was the introduction of REACH and the difficulties to understand the implications for ash. The most important consequence of REACH is that all chemical substances that are manufactured, handled and used above one tonne per annum per legal entity shall be registered according to this regulation. The registration includes specifying the chemical, physical, toxicity and ecotoxicity properties of the substance and risk assessing the identified areas of use. The report describes the use of ash in connection to the waste legislation and its planned end-of-waste-criteria, the chemical legislation and the Construction Products Directive. The target audience of this report is companies producing ashes and having a use or seeing a use for its ash. The report describes how to make a REACH registration of ash independent if a company did or did not pre-register ash during 2008. It describes how to change from one ash registration into another if the pre-registration was done for one type of ash but the company changes opinion during the sameness check, i.e. changing SIEF (Appendix A). Taking part in REACH registration projects during 2009-2010 can be advantageous since knowledge and financing are shared. Ash can be REACH registered also in the future but it is important to know that the registration have to be done prior the production and marketing starts. If ash is consider to be a waste the handling is covered by the community and national waste legislation. In Sweden ashes are by and large being regarded as waste, and recycling is risk assessed and permits are given case by case. End-of-waste criteria for different waste material are being elaborated within the EU. Such criteria will among other details cover chemical safety. When a material fulfils the end-of-waste criteria such material

Critical indices for the Yukawa2 quantum field theory

International Nuclear Information System (INIS)

Bonetto, F.

1997-01-01

The understanding of the Yukawa 2 quantum field theory is still incomplete if the fermionic mass is much smaller than the coupling. We analyze the Schwinger functions for small coupling uniformly in the mass and we find that the asymptotic behavior of the two-point Schwinger function is anomalous and described by two critical indices, related to the renormalization of the mass and of the wave function. The indices are explicitly computed by convergent series in the coupling. (orig.)

Emerging role of HPV self-sampling in cervical cancer screening for hard-to-reach women: Focused literature review.

Science.gov (United States)

Madzima, Tina R; Vahabi, Mandana; Lofters, Aisha

2017-08-01

To provide a focused critical review of the literature on the acceptability, feasibility, and uptake of human papillomavirus (HPV) self-sampling among hard-to-reach women. A focused search to obtain relevant literature published in English between 1997 and 2015 was done using PubMed and EMBASE using search terms including HPV self-test or HPV self-sample or HPV kit in combination with acceptability or feasibility . Only studies that focused on never-screened or underscreened populations were included in this review. Human papillomavirus self-sampling was found to be highly acceptable and feasible among these hard-to-reach women across most studies. Mailing of self-sampling kits has been shown to increase participation among hard-to reach women. Some concerns remain regarding adherence to further follow-up among high-risk women with positive test results for HPV after screening. There is a strong body of evidence to support the usefulness of HPV self-sampling in increasing participation of hard-to-reach women in screening programs (level I evidence). Convenience, privacy, ease of use, and, likely, cost-effectiveness of HPV self-sampling are driving forces in its emerging role in cervical cancer screening among hard-to-reach women. Key barriers to participation could be addressed by overcoming disparities in HPV-related knowledge and perceptions about cervical cancer screening. Copyright© the College of Family Physicians of Canada.

Investigation of the proton-neutron interaction by high-precision nuclear mass measurements

CERN Multimedia

Savreux, R P; Akkus, B

2007-01-01

We propose to measure the atomic masses of a series of short-lived nuclides, including $^{70}$Ni, $^{122-130}$Cd, $^{134}$Sn, $^{138,140}$Xe, $^{207-210}$Hg, and $^{223-225}$Rn, that contribute to the investigation of the proton-neutron interaction and its role in nuclear structure. The high-precision mass measurements are planned for the Penning trap mass spectrometer ISOLTRAP that reaches the required precision of 10 keV in the nuclear mass determination.

Imagery in visual arts: Managing the temperament of art criticism ...

African Journals Online (AJOL)

Works of art can be described as narratives in shorthand where tangled mass of meaning and relationships are woven 'seemingly' inseparably by the instrumentality of a medium. The interpretation of this shorthand and the undoing of the 'tangled mass of meaning, constitute the great area known as 'art criticism'.

Monte Carlo criticality analysis of simple geometries containing tungsten-rhenium alloys engrained with uranium dioxide and uranium mononitride

International Nuclear Information System (INIS)

Webb, Jonathan A.; Charit, Indrajit

2011-01-01

Highlights: → The addition of rhenium to the tungsten matrix within W-UO 2 and W-UN CERMET materials can help reduce the risk of submersion criticality accidents while increasing the strength and ductility of tungsten based nuclear fuel elements. → The addition of rhenium up to 30 at.% to simple geometries containing W-UO 2 mixtures can increase the critical mass by 65 kg. → The addition of rhenium up to 30 at.% to simple geometries containing W-UN mixtures can increase the critical mass by 22 kg. → The addition of rhenium by up to 30 at.% to simple geometries containing W-UO 2 mixtures can reduce the change in reactivity change due to water submersion by $5.07. → The addition of rhenium by up to 30 at.% to simple geometries containing W-UN mixtures can reduce the change in reactivity due to water submersion by $3.24. - Abstract: The critical mass and dimensions of simple geometries containing highly enriched uranium dioxide (UO 2 ) and uranium mononitride (UN) encapsulated in tungsten-rhenium alloys are determined using MCNP5 criticality calculations. Spheres as well as cylinders with length to radius ratios of 1.82 are computationally built to consist of 60 vol.% fuel and 40 vol.% metal matrix. Within the geometries, the uranium is enriched to 93 wt.% uranium-235 and the rhenium content within the metal alloy was modeled over the range of 0-30 at.%. The spheres containing UO 2 were determined to have a critical radius of 18.29-19.11 cm and a critical mass ranging from 366 kg to 424 kg. The cylinders containing UO 2 were found to have a critical radius ranging from 17.07 cm to 17.84 cm with a corresponding critical mass of 406-471 kg. Spheres engrained with UN were determined to have a critical radius ranging from 14.82 cm to 15.19 cm and a critical mass between 222 kg and 242 kg. Cylinders which were engrained with UN were determined to have a critical radius ranging from 13.81 cm to 14.15 cm and a corresponding critical mass of 245-267 kg. The critical

Think Tank Critics Plant a Stake in Policy World

Science.gov (United States)

Sparks, Sarah D.

2010-01-01

After five years of providing critical reviews of education-related reports by nonacademic think tanks, education professors Alex Molnar and Kevin G. Welner hope to expand their own reach with a new, broader research center. The new National Education Policy Center, based at Welner's academic home, the University of Colorado at Boulder, will…

Ozone mass transfer and kinetics experiments

International Nuclear Information System (INIS)

Bollyky, L.J.; Beary, M.M.

1981-12-01

Experiments were conducted at the Hanford Site to determine the most efficient pH and temperature levels for the destruction of complexants in Hanford high-level defense waste. These complexants enhance migration of radionuclides in the soil and inhibit the growth of crystals in the evaporator-crystallizer. Ozone mass transfer and kinetics tests have been outlined for the determination of critical mass transfer and kinetics parameters of the ozone-complexant reaction

Stream Habitat Reach Summary - NCWAP [ds158

Data.gov (United States)

California Natural Resource Agency — The Stream Habitat - NCWAP - Reach Summary [ds158] shapefile contains in-stream habitat survey data summarized to the stream reach level. It is a derivative of the...

Filling Critical Gaps Through Innovative Cradle-to-Grave Training Final Report

Energy Technology Data Exchange (ETDEWEB)

Burns, Pamela [North Central Texas Council of Governments; Dallas-Fort Worth Clean Cities; To, Kimberlin [North Central Texas Council of Governments; Dallas-Fort Worth Clean Cities

2018-01-30

This project seeks to enhance and provide training on alternative fuels and alternative fuel vehicles to reach mechanics/technicians, first responders, public safety officials, and other critical service providers across the multi-state region of Arkansas, Louisiana, Oklahoma, and Texas

Operational Reach: Is Current Army Doctrine Adequate?

National Research Council Canada - National Science Library

Heintzelman, Scott

2003-01-01

The term operational reach, an element of operational design, is new to U.S. Army doctrine. Operational reach is not found in the previous edition of the Army's basic operational doctrine, Field Manual...

Potential Reach of mHealth Versus Traditional Mass Media for Prevention of Chronic Diseases: Evidence From a Nationally Representative Survey in a Middle-Income Country in Africa.

Science.gov (United States)

Yepes, Maryam; Maurer, Jürgen; Viswanathan, Barathi; Gedeon, Jude; Bovet, Pascal

2016-05-20

Public radio and television announcements have a long tradition in public health education. With the global rise of computer and mobile device ownership, short message service (SMS) and email-based health services (mHealth) are promising new tools for health promotion. Our objectives were to examine 1) self-reported exposure to programs related to noncommunicable diseases (NCDs) on national public television and radio during the 12 months preceding the survey (2013-2014), 2) current ownership of a mobile phone, smartphone, computer, or tablet, and use of the Internet, and 3) willingness of individuals to receive SMS or emails with information on health, with a focus on distribution of these variables across different demographic, socioeconomic status (SES), and NCD risk groups. We obtained data in a population survey of 1240 participants aged 25-64 years conducted in 2013-2014 in the Seychelles, a rapidly developing small island state in the African region. We administered a structured questionnaire and measured NCD risk factors. Univariate and multivariate analyses explored the relationships between outcomes and sociodemographic variables. Of 1240 participants, 1037 (83.62%) reported exposure to NCD-related programs on public television, while a lower proportion of 740 adults (59.67%), reported exposure via public radio (Pphone and ownership was positively associated with female sex (Pphones and willingness to receive health-related SMS, mHealth presents an opportunity for health programs, especially when targeted SMS messages are intended for younger adults and those in higher socioeconomic groups. By contrast, due to reduced Internet access, email-based programs had a more limited reach for health promotion programs. These findings emphasize the different reach of interventions using SMS or email versus traditional mass media, according to demographic and socioeconomic categories, for health education programs in a developing country.

The chiral critical line of $N_{f}=2+1$ QCD at ero and non-zero baryon density

CERN Document Server

De Forcrand, Philippe; Forcrand, Philippe de; Philipsen, Owe

2007-01-01

We present numerical results for the location of the chiral critical line at finite temperature and zero and non-zero baryon density for QCD with N_f=2+1 flavours of staggered fermions on lattices with temporal extent N_t=4. For degenerate quark masses, we compare our results obtained with the exact RHMC algorithm with earlier, inexact R-algorithm results and find a reduction of 25% in the critical quark mass, for which the first order phase transition changes to a smooth crossover. Extending our analysis to non-degenerate quark masses, we map out the chiral critical line up to the neighbourhood of the physical point, which we confirm to be in the crossover region. Our data are consistent with a tricritical point at a strange quark mass of ~500 MeV. Finally, we investigate the shift of the critical line with finite baryon density, by simulating with an imaginary chemical potential for which there is no sign problem. We observe this shift to be very small or, conversely, the critical endpoint \\mu^c(m_{u,d},m_s...

Old Romanian pluralized mass and abstract nouns

Directory of Open Access Journals (Sweden)

Gabriela Pană Dindelegan

2017-09-01

Full Text Available The analysis of a rich old Romanian corpus shows that the ‘pluralization’ of mass and abstract nouns is extremely frequent in old Romanian. The semantic effects of pluralization are similar for mass and abstract nouns, consisting in the creation of denotative and/or connotative semantic variants. Of the plural endings, –uri is specialized for the pluralization of mass nouns in Daco-Romanian. The evolution of the ending –uri illustrates the specific process by which a grammatical (plural morpheme is converted into a lexical morpheme (the so-called ‘lexical plurals’. ‘Lexical plurals’ have isolated occurrences in other Romance languages, but they have not reached the spread and regularity they display in Romanian.

Modeling of Plutonium Ionization Probabilities for Use in Nuclear Forensic Analysis by Resonance Ionization Mass Spectrometry

Science.gov (United States)

2016-12-01

masses collide, they form a supercritical mass . Criticality refers to the neutron population within the system. A critical system is one that can...Spectrometry, no. 242, pp. 161–168, 2005. [9] S. Raeder, “Trace analysis of actinides in the environment by means of resonance ionization mass ...first ionization potential of actinide elements by resonance ionization mass spectrometry.” Spectrochimica Acta part B: Atomic Spectroscopy. vol. 52

SDSS-IV MaNGA: Star Formation Cessation in Low-redshift Galaxies. I. Dependence on Stellar Mass and Structural Properties

Science.gov (United States)

Wang, Enci; Li, Cheng; Xiao, Ting; Lin, Lin; Bershady, Matthew; Law, David R.; Merrifield, Michael; Sanchez, Sebastian F.; Riffel, Rogemar A.; Riffel, Rogerio; Yan, Renbin

2018-04-01

We investigate radial gradients in the recent star formation history (SFH) of 1917 galaxies with 0.01 < z < 0.14 from the Mapping Nearby Galaxies at Apache Point Observatory project. For each galaxy, we obtain two-dimensional maps and radial profiles for three spectroscopically measured parameters that are sensitive to the recent SFH: D n (4000) (the 4000 Å break), EW(Hδ A ), and EW(Hα) (the equivalent width of the Hδ absorption and the Hα emission line). The majority of the spaxels are consistent with models of a continuously declining star formation rate, indicating that starbursts occur rarely in local galaxies with regular morphologies. We classify the galaxies into three classes: fully star-forming (SF), partly quenched (PQ), and totally quenched (TQ). The galaxies that are less massive than 1010 M ⊙ present at most weak radial gradients in the diagnostic parameters. In contrast, massive galaxies with a stellar mass above 1010 M ⊙ present significant gradients in the three diagnostic parameters if they are classified as SF or PQ but show weak gradients in D n (4000) and EW(Hδ A ) and no gradients in EW(Hα) if they are in the TQ class. This implies the existence of a critical stellar mass (∼1010 M ⊙) above which the star formation in a galaxy is shut down from the inside out. Galaxies tend to evolve synchronously from the inner to the outer regions before their mass reaches the critical value. We have further divided the sample at a fixed mass by both bulge-to-total luminosity ratio and morphological type, finding that our conclusions hold regardless of these factors; it appears that the presence of a central dense object is not a driving parameter but rather a by-product of the star formation cessation process.

Criticality of Parasitic Disease Transmission in a Diffusive Population

International Nuclear Information System (INIS)

He Minhua; Zhang Duanming; Yin Yanping; Chen Zhiyuan; Pan Guijun

2008-01-01

Through using the methods of finite-size effect and short time dynamic scaling, we study the critical behavior of parasitic disease spreading process in a diffusive population mediated by a static vector environment. Through comprehensive analysis of parasitic disease spreading we find that this model presents a dynamical phase transition from disease-free state to endemic state with a finite population density. We determine the critical population density, above which the system reaches an epidemic spreading stationary state. We also perform a scaling analysis to determine the order parameter and critical relaxation exponents. The results show that the model does not belong to the usual directed percolation universality class and is compatible with the class of directed percolation with diffusive and conserved fields

Critical properties of some aliphatic symmetrical ethers

International Nuclear Information System (INIS)

Nikitin, Eugene D.; Popov, Alexander P.; Bogatishcheva, Nataliya S.

2014-01-01

Highlights: • Critical properties of simple aliphatic ethers were measured. • The ethers decompose at near-critical temperatures. • Pulse-heating method with short residence times was used. -- Abstract: The critical temperatures T c and the critical pressures p c of dihexyl, dioctyl, and didecyl ethers have been measured. According to the measurements, the coordinates of the critical points are T c = (665 ± 7) K, p c = (1.44 ± 0.04) MPa for dihexyl ether, T c = (723 ± 7) K, p c = (1.19 ± 0.04) MPa for dioctyl ether, and T c = (768 ± 8) K, p c = (1.03 ± 0.03) MPa for didecyl ether. All the ethers studied degrade chemically at near-critical temperatures. A pulse-heating method applicable to measuring the critical properties of thermally unstable compounds has been used. The times from the beginning of a heating pulse to the moment of reaching the critical temperature were from 0.06 to 0.46 ms. The short residence times provide little decomposition of the substances in the course of the experiments. The critical properties of the ethers investigated in this work have been discussed together with those of methyl to butyl ethers. The experimental critical constants of the ethers have been compared with those estimated by the group-contribution methods of Wilson and Jasperson and Marrero and Gani. The Wilson/Jasperson method provides a better estimation of the critical temperatures and pressures of simple aliphatic ethers in comparison with the Marrero/Gani method if reliable normal boiling temperatures are used in the method of Wilson and Jasperson

Disk Masses around Solar-mass Stars are Underestimated by CO Observations

Energy Technology Data Exchange (ETDEWEB)

Yu, Mo; Evans II, Neal J. [Astronomy Department, University of Texas, 2515 Speedway, Stop C1400, Austin, TX 78712 (United States); Dodson-Robinson, Sarah E. [University of Delaware, Department of Physics and Astronomy, 217 Sharp Lab, Newark, DE 19716 (United States); Willacy, Karen; Turner, Neal J. [Mail Stop 169-506, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

2017-05-20

Gas in protostellar disks provides the raw material for giant planet formation and controls the dynamics of the planetesimal-building dust grains. Accurate gas mass measurements help map the observed properties of planet-forming disks onto the formation environments of known exoplanets. Rare isotopologues of carbon monoxide (CO) have been used as gas mass tracers for disks in the Lupus star-forming region, with an assumed interstellar CO/H{sub 2} abundance ratio. Unfortunately, observations of T-Tauri disks show that CO abundance is not interstellar, a finding reproduced by models that show CO abundance decreasing both with distance from the star and as a function of time. Here, we present radiative transfer simulations that assess the accuracy of CO-based disk mass measurements. We find that the combination of CO chemical depletion in the outer disk and optically thick emission from the inner disk leads observers to underestimate gas mass by more than an order of magnitude if they use the standard assumptions of interstellar CO/H{sub 2} ratio and optically thin emission. Furthermore, CO abundance changes on million-year timescales, introducing an age/mass degeneracy into observations. To reach a factor of a few accuracy for CO-based disk mass measurements, we suggest that observers and modelers adopt the following strategies: (1) select low- J transitions; (2) observe multiple CO isotopologues and use either intensity ratios or normalized line profiles to diagnose CO chemical depletion; and (3) use spatially resolved observations to measure the CO-abundance distribution.

Criticality management organization in the alpha incinerator

International Nuclear Information System (INIS)

Devillard, D.; Thiebaut, C.; Poinso, J.Y.; Huin, M.

2004-01-01

The Valduc Research Center, which reports to the CEA's Military applications Division, generates solid wastes contaminated with alpha emitters in the operation of its installations. An incineration plant has been built to treat these contaminated wastes. Criticality risk prevention is based on limiting the mass of active material undergoing treatment in the facility. A balance is compiled continuously by calculating the difference between the mass of active material entering the facility and the mass leaving it. Due to measurement uncertainties, the balance must be zeroed periodically by cleaning and drainage of all the equipment and the absence of holdup in the components must be checked. (authors)

Influence of patient related factors on number of mesenchymal stromal cells reached after in vitro culture expansion for clinical treatment

DEFF Research Database (Denmark)

Qayyum, Abbas Ali; Kaur, Kamal Preet; Mathiasen, Anders Bruun

2017-01-01

of autologous stromal cells reached after in vitro culture expansion for clinical therapy. METHODS: Culture expansion data from 111 patients with IHD treated with autologous stromal cells in three clinical trials were used. We correlated the final cell count after two passages of cultivation with different...... correlation between left ventricular ejection fraction and number of MSCs was found (r = -0.287, p = .017). CONCLUSIONS: Patient related factors such as BMI, hypertension and gender may influence the number of MSCs reached after in vitro culture expansion....... patient factors. RESULTS: There was a significant relation between body mass index (BMI) and the number of adipose derived stromal cells (ASCs) reached after culture expansion and for all patients included into the three studies (r = 0.375, p = .019 and r = 0.200, p = .036, respectively). Moreover...

Critical parameters of Quark-Hadron phase transition with interacting and massive quarks

International Nuclear Information System (INIS)

Singh, C.P.; Patra, B.K.

1994-06-01

Current techniques to simulate the dynamical behaviour of Quark-Gluon Plasma (QGP) reveal that the order of the phase transition as well as the values of the critical parameters depend on the number of quark flavours as well as on the quark-masses included in the simulation. We attempt to show here the effects of the number of quark flavours and quark-masses on critical parameters by using the perturbative, finite temperature field theory to g 3 s order in the strong coupling g s . We treat the hadrons as particles with finite size and its implications on the equation of state for hadron gas are studied. We find that the critical temperature T c is lowered by 9 MeV as we move from two to three quark flavours. The nature of the phase transition always remains as first order. However, the inclusion of quark-masses in our calculation does not affect the result much. (author). 14 refs, 3 figs

Influence of high range of mass transfer coefficient and convection heat transfer on direct contact membrane distillation performance

KAUST Repository

Lee, Jung Gil

2017-11-03

In order to improve water production of membrane distillation (MD), the development of high performance membrane having better mass transfer and enhancement of convection heat transfer in MD module have been continuously investigated. This paper presents the relationship between the heat and mass transfer resistance across the membrane and the performance improvement. Various ranges of mass transfer coefficient (MTC) from normal (0.3×10−6 to 2.1×10−6kg/m2sPa: currently available membranes) to high (>2.1×10−6kg/m2sPa: membranes under development) were simulated using an experimentally validated model at different ranges of convection heat transfer by varying the inlet flow rates and spacer enhancement factor. The effect of mass transfer and convection heat transfer on the MD performance parameters including temperature polarization coefficient (TPC), mean permeate flux, and specific energy consumption were investigated in a direct contact MD (DCMD) configuration. Results showed that improving the MTC at the low ranges is more important than that at the high ranges where the heat transfer resistance becomes dominant and hence the convection heat transfer coefficient must be increased. Therefore, an effort on designing MD modules using feed and permeate spacers and controlling the membrane surface roughness to increase the convection heat transfer and TPC in the channel aiming to enhance the flux is required because the currently developed mass transfer has almost reached the critical point.

Critical success factors for competitiveness of construction companies: A critical review

Science.gov (United States)

Hanafi, Abdul Ghafur; Nawi, Mohd Nasrun Mohd

2016-08-01

Making progress basically, a fundamental issue for the construction companies to get by in a highly competitive industry. From time to time, industry players are facing stiff and tough competition due to large number of players, whether existing or new players involved from various background and track record. Furthermore, the large numbers of component deciding the competitiveness of contractors, whose organization structures and governance have turned out to be more muddled. Different construction companies have their own unique criteria which may differ from one to another. The enormous amount of issues needs to bring down to manageable numbers so that measures can be identified and scrutinized to enhance competitiveness. This paper discusses the result from the critical investigation from past studies in the Asian countries, namely China, India, Thailand, Singapore and Malaysia. Several fundamental factors have been identified as CSFs in construction companies in respective country. Also highlighted a critical survey based upon various literatures written on this subject where critical success factors (CSFs) as a yardstick to gauge the relationship among CSFs in various construction companies in the Asian region. Far reaching estimation of an organization's performance and resulting input to its supervision is crucial for business change. Estimation additionally empowers organizations to be contrasted from one another on the premise of institutionalized data, permitting best practices to be distinguished and connected more widely. Different countries have their own set of critical success factors (CSFs) which may differ in term of priority and at the same time share common elements of success factor in accomplishment as a construction companies. The study, which is exploratory in nature, embraced the content investigation and inductive technique to accomplish its objectives.

CRITICAL MASS

Institute of Scientific and Technical Information of China (English)

DAVID; DAWSON

2015-01-01

The Middle Kingdom’s booming Christian community celebrates Christmas教会里的圣诞节并不是购物与狂欢Worldwide,there are two kinds of Christmas.While both are a time of joy,one is relatively secular;its trappings are Christmas trees,gifts,reindeer,and the jolly,red,fat version of Saint Nick(going by圣诞老人,or Christmas Elderly Person in China).

Criticality issues with highly enriched fuels in a repository environment

International Nuclear Information System (INIS)

Taylor, L.L.; Sanchez, L.C.; Rath, J.S.

1998-03-01

This paper presents preliminary analysis of a volcanic tuff repository containing a combination of low enrichment commercial spent nuclear fuels (SNF) and DOE-owned SNF packages. These SNFs were analyzed with respect to their criticality risks. Disposal of SNF packages containing significant fissile mass within a geologic repository must comply with current regulations relative to criticality safety during transportation and handling within operational facilities. However, once the repository is closed, the double contingency credits for criticality safety are subject to unremediable degradation, (e.g., water intrusion, continued presence of neutron absorbers in proximity to fissile material, and fissile material reconfiguration). The work presented in this paper focused on two attributes of criticality in a volcanic tuff repository for near-field and far-field scenarios: (1) scenario conditions necessary to have a criticality, and (2) consequences of a nuclear excursion that are components of risk. All criticality consequences are dependent upon eventual water intrusion into the repository and subsequent breach of the disposal package. Key criticality parameters necessary for a critical assembly are: (1) adequate thermal fissile mass, (2) adequate concentration of fissile material, (3) separation of neutron poison from fissile materials, and (4) sufficient neutron moderation (expressed in units of moderator to fissile atom ratios). Key results from this study indicated that the total energies released during a single excursion are minimal (comparable to those released in previous solution accidents), and the maximum frequency of occurrence is bounded by the saturation and temperature recycle times, thus resulting in small criticality risks

Construction of new critical experiment facilities in JAERI

International Nuclear Information System (INIS)

Takeshita, Isao; Itahashi, Takayuki; Ogawa, Kazuhiko; Tonoike, Kotaro; Matsumura, Tatsuro; Miyoshi, Yoshinori; Nakajima, Ken; Izawa, Naoki

1995-01-01

Japan Atomic Energy Research Institute (JAERI) has promoted the experiment research program on criticality safety since early in 1980s and two types of new critical facilities, Static Experiment Critical Facility (STACY) and Transient Experiment Critical Facility (TRACY) were completed on 1994 in Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) of JAERI Tokai Research Establishment. STACY was designed so as to obtain critical mass data of low enriched uranium and plutonium solution which is extensively handled in LWR fuel reprocessing plant. TRACY is the critical facility where critical accident phenomenon is demonstrated with low enriched uranium nitrate solution. For criticality safety experiments with both facilities, the Fuel Treatment System is attached to them, where composition and concentration of uranium and plutonium nitrate solutions are widely varied so as to obtain experiments data covering fuel solution conditions in reprocessing plant. Design performances of both critical facilities were confirmed through mock-up tests of important components and cold function tests. Hot function test has started since January of 1995 and some of the results on STACY are to be reported. (author)

Pulsation, Mass Loss and the Upper Mass Limit

Science.gov (United States)

Klapp, J.; Corona-Galindo, M. G.

1990-11-01

RESUMEN. La existencia de estrellas con masas en exceso de 100 M0 ha sido cuestionada por mucho tiempo. Lfmites superiores para la masa de 100 M0 han sido obtenidos de teorfas de pulsaci6n y formaci6n estelar. En este trabajo nosotros primero investigamos la estabilidad radial de estrellas masivas utilizando la aproximaci6n clasica cuasiadiabatica de Ledoux, la aproximaci6n cuasiadiabatica de Castor y un calculo completamente no-adiabatico. Hemos encontrado que los tres metodos de calculo dan resultados similares siempre y cuando una pequefia regi6n de las capas externas de la estrella sea despreciada para la aproximaci6n clasica. La masa crftica para estabilidad de estrellas masivas ha sido encontrada en acuerdo a trabajos anteriores. Explicamos Ia discrepancia entre este y trabajos anteriores por uno de los autores. Discunmos calculos no-lineales y perdida de masa con respecto a) lfmite superior de masa. The existence of stars with masses in excess of 100 M0 has been questioned for a very long time. Upper mass limits of 100 Me have been obtained from pulsation and star formation theories. In this work we first investigate the radial stability of massive stars using the classical Ledoux's quasiadiabatic approximation. the Castor quasiadiabatic approximation and a fully nonadiabatic calculation. We have found that the three methods of calculation give similar results provided that a small region in outer layers of the star be neglected for the classical approximation. The critical mass for stability of massive stars is found to be in agreement with previous work. We explain the reason for the discrepancy between this and previous work by one of the authors. We discuss non-linear calculations and mass loss with regard to the upper mass limit. Key words: STARS-MASS FUNCTION - STARS-MASS LOSS - STARS-PULSATION

The coral reef crisis: the critical importance of<350 ppm CO2.

Science.gov (United States)

Veron, J E N; Hoegh-Guldberg, O; Lenton, T M; Lough, J M; Obura, D O; Pearce-Kelly, P; Sheppard, C R C; Spalding, M; Stafford-Smith, M G; Rogers, A D

2009-10-01

Temperature-induced mass coral bleaching causing mortality on a wide geographic scale started when atmospheric CO(2) levels exceeded approximately 320 ppm. When CO(2) levels reached approximately 340 ppm, sporadic but highly destructive mass bleaching occurred in most reefs world-wide, often associated with El Niño events. Recovery was dependent on the vulnerability of individual reef areas and on the reef's previous history and resilience. At today's level of approximately 387 ppm, allowing a lag-time of 10 years for sea temperatures to respond, most reefs world-wide are committed to an irreversible decline. Mass bleaching will in future become annual, departing from the 4 to 7 years return-time of El Niño events. Bleaching will be exacerbated by the effects of degraded water-quality and increased severe weather events. In addition, the progressive onset of ocean acidification will cause reduction of coral growth and retardation of the growth of high magnesium calcite-secreting coralline algae. If CO(2) levels are allowed to reach 450 ppm (due to occur by 2030-2040 at the current rates), reefs will be in rapid and terminal decline world-wide from multiple synergies arising from mass bleaching, ocean acidification, and other environmental impacts. Damage to shallow reef communities will become extensive with consequent reduction of biodiversity followed by extinctions. Reefs will cease to be large-scale nursery grounds for fish and will cease to have most of their current value to humanity. There will be knock-on effects to ecosystems associated with reefs, and to other pelagic and benthic ecosystems. Should CO(2) levels reach 600 ppm reefs will be eroding geological structures with populations of surviving biota restricted to refuges. Domino effects will follow, affecting many other marine ecosystems. This is likely to have been the path of great mass extinctions of the past, adding to the case that anthropogenic CO(2) emissions could trigger the Earth's sixth

Adaptive mixed reality rehabilitation improves quality of reaching movements more than traditional reaching therapy following stroke.

Science.gov (United States)

Duff, Margaret; Chen, Yinpeng; Cheng, Long; Liu, Sheng-Min; Blake, Paul; Wolf, Steven L; Rikakis, Thanassis

2013-05-01

Adaptive mixed reality rehabilitation (AMRR) is a novel integration of motion capture technology and high-level media computing that provides precise kinematic measurements and engaging multimodal feedback for self-assessment during a therapeutic task. We describe the first proof-of-concept study to compare outcomes of AMRR and traditional upper-extremity physical therapy. Two groups of participants with chronic stroke received either a month of AMRR therapy (n = 11) or matched dosing of traditional repetitive task therapy (n = 10). Participants were right handed, between 35 and 85 years old, and could independently reach to and at least partially grasp an object in front of them. Upper-extremity clinical scale scores and kinematic performances were measured before and after treatment. Both groups showed increased function after therapy, demonstrated by statistically significant improvements in Wolf Motor Function Test and upper-extremity Fugl-Meyer Assessment (FMA) scores, with the traditional therapy group improving significantly more on the FMA. However, only participants who received AMRR therapy showed a consistent improvement in kinematic measurements, both for the trained task of reaching to grasp a cone and the untrained task of reaching to push a lighted button. AMRR may be useful in improving both functionality and the kinematics of reaching. Further study is needed to determine if AMRR therapy induces long-term changes in movement quality that foster better functional recovery.

Observations of enhanced thinning in the upper reaches of Svalbard glaciers

Directory of Open Access Journals (Sweden)

T. D. James

2012-11-01

Full Text Available Changes in the volume and extent of land ice of the Svalbard archipelago have been the subject of considerable research since their sensitivity to changes in climate was first noted. However, the measurement of these changes is often necessarily based on point or profile measurements which may not be representative if extrapolated to a whole catchment or region. Combining high-resolution elevation data from contemporary laser-altimetry surveys and archived aerial photography makes it possible to measure historical changes across a glacier's surface without the need for extrapolation. Here we present a high spatial resolution time-series for six Arctic glaciers in the Svalbard archipelago spanning 1961 to 2005. We find high variability in thinning rates between sites with prevalent elevation changes at all sites averaging −0.59 ± 0.04 m a⁻¹ between 1961–2005. Prior to 1990, ice surface elevation was changing at an average rate of −0.52 ± 0.09 m a⁻¹ which decreased to −0.76 ± 0.10 m a⁻¹ after 1990. Setting the elevation changes against the glaciers' altitude distribution reveals that significant increases in thinning rates are occurring most notably in the glaciers' upper reaches. We find that these changes are coincident with a decrease in winter precipitation at the Longyearbyen meteorological station and could reflect a decrease in albedo or dynamic response to lower accumulation. Further work is required to understand fully the causes of this increase in thinning rates in the glaciers' upper reaches. If on-going and occurring elsewhere in the archipelago, these changes will have a significant effect on the region's future mass balance. Our results highlight the importance of understanding the climatological context of geodetic mass balance measurements and demonstrate the difficulty of using index glaciers to represent regional changes in areas of strong climatological gradients.

Mass generation in composite models

International Nuclear Information System (INIS)

Peccei, R.D.

1985-10-01

I discuss aspects of composite models of quarks and leptons connected with the dynamics of how these fermions acquire mass. Several issues related to the protection mechanisms necessary to keep quarks and leptons light are illustrated by means of concrete examples and a critical overview of suggestions for family replications is given. Some old and new ideas of how one may actually be able to generate small quark and lepton masses are examined, along with some of the difficulties they encounter in practice. (orig.)

Evaluation of criticality criteria for fissile class II packages in transportation

International Nuclear Information System (INIS)

Thomas, J.T.

1976-01-01

The nuclear criticality safety of packages in transportation is explored systematically by a surface density representation of reflected array criticality of air-spaced units. Typical perturbations to arrays are shown to be related analytically to the corresponding reactivity changes they produce. The reactivity change associated with the removal of three reflecting surfaces from a totally water reflected array is shown to depend upon the fissile material loading of the packages. For U(93.2) metal, the expected reactivity loss can range from 2 to 21%. Replacement of a three-sided reflector of water on a critical array by one of concrete results in a reactivity increase ranging from 0 to 6%. Mass limits established by criticality data for reflected arrays of air-spaced units can provide a minimum, uniform margin of safety, expressible in terms of reactivity, to more reliably specify subcriticality in transport. Mass limits less than those defined by air-spaced units in water-reflected arrays are unnecessary for Fissile Class II packages. (author)

Two Balls' Collision of Mass Ratio 3:1

Science.gov (United States)

Ogawara, Yasuo; Hull, Michael M.

2018-04-01

Students will sometimes ask why momentum and kinetic energy concepts are both necessary. When physics teachers demonstrate situations that require both an understanding of kinetic energy and momentum, a favorite is Newton's cradle, or a comparable demonstration of two balls of equal mass hitting each other. However, in addition to the case of two balls of equal mass, if a ball hits another ball of three times the mass with equal speed, the results are also interesting, and, like the equal-mass demonstration, both kinetic energy and momentum are critical for understanding the motion.

NORMAL VALUES AND FACTORS AFFECTING FUNCTIONAL REACH TEST IN SAUDI ARABIA SCHOOL CHILDREN WITH TYPICAL DEVELOPMENT

Directory of Open Access Journals (Sweden)

Hatem A. Emara

2015-10-01

Full Text Available Background: The most critical feature of motor development is the ability to balance the body in sitting or standing. Impaired balance limits a child’s ability to recover from unexpected threats to stability. The functional reach test (FRT defines the maximal distance an individual is able to reach forward beyond arm’s length in a standing position without loss of balance, taking a step, or touching the wall. The Purpose of this study was to establish the normal values for FRT in Saudi Arabia school children with typical development and to study the correlation of anthropometric measures with FRT values. Methods: This cross-sectional study was conducted in Almadinah Almonawarah, Kingdom of Saudi Arabia. A total of 280 children without disabilities aged 6 to 12 years were randomly selected. Functional reach was assessed by having subjects extend their arms to 90 degrees and reach as far forward as they could without taking a step. Reach distance was recorded by noting the beginning and final position of the subject's extended arm parallel to a yard stick attached to the wall. Three successive trials of FRT were performed and the mean of the three trials was calculated. Pearson product moment correlation was used to examine the association of FR to age, and anthropometric measures. Results: Normal mean values of FR ranged from 24.2cm to 33.95cm. Age, height and weight significantly correlate with FRT. Conclusion: The FRT is a feasible test to examine the balance of 6-12 year-old children. FRT may be useful for detecting balance impairment, change in balance performance over time.

Outcomes of senior reach gatekeeper referrals: comparison of the Spokane gatekeeper program, Colorado Senior Reach, and Mid-Kansas Senior Outreach.

Science.gov (United States)

Bartsch, David A; Rodgers, Vicki K; Strong, Don

2013-01-01

Outcomes of older adults referred for care management and mental health services through the senior reach gatekeeper model of case finding were examined in this study and compared with the Spokane gatekeeper model Colorado Senior Reach and the Mid-Kansas Senior Outreach (MKSO) programs are the two Senior Reach Gatekeeper programs modeled after the Spokane program, employing the same community education and gatekeeper model and with mental health treatment for elderly adults in need of support. The three mature programs were compared on seniors served isolation, and depression ratings. Nontraditional community gatekeepers were trained and referred seniors in need. Findings indicate that individuals served by the two Senior Reach Gatekeeper programs demonstrated significant improvements. Isolation indicators such as social isolation decreased and depression symptoms and suicide ideation also decreased. These findings for two Senior Reach Gatekeeper programs demonstrate that the gatekeeper approach to training community partners worked in referring at-risk seniors in need in meeting their needs, and in having a positive impact on their lives.

Critical power experiment with a tight-lattice 37-rod bundle

International Nuclear Information System (INIS)

Kureta, Masatoshi; Tamai, Hidesada; Ohnuki, Akira; Sato, Takashi; Liu, Wei; Akimoto, Hajime

2006-01-01

Since most of critical power or CHF data have been collected in tube, annulus, or BWR geometries under BWR flow conditions, critical power data for highly tight and triangular lattice bundles under low mass velocity are indispensable for thermal-hydraulic design of Reduced-Moderation Water Reactor. Large-scale thermal-hydraulic experiments which use a basic 37-rod bundle test section (rod diameter: 13.0 mm, gap width between rods: 1.3 mm) were therefore carried out in this study within range of 2-9 MPa in pressure and 150-1,000 kg/(m 2 ·s) in mass velocity. Fundamental characteristics of boiling transition were investigated through effects of flow parameter on critical power and those of rod number. It was confirmed that the fundamental characteristics in 37-rod bundle are similar to those in 7-rod bundle and in case of the BWR geometry. The results of the transverse non-uniform power distribution test and subchannel analysis suggest that the critical power becomes higher when the transverse local quality distribution closes to uniform. (author)

Anisotropic critical fields in superconducting superlattices

International Nuclear Information System (INIS)

Banerjee, I.; Yang, Q.S.; Falco, C.M.; Schuller, I.K.

1983-01-01

The temperature and angular dependence of critical fields (H/sub c/) have been studied as a function of layer thickness for superconducting Nb/Cu superlattices. For layer thicknesses between 100 and 300 A, dimensional crossover has been observed in the temperature dependence of H/sub c/. Associated with the crossover we find a change in the angular dependence of H/sub c/ to that given by the effective-mass theory. This is the first time that a relationship has been found between dimensional crossover observed in the temperature dependence and that in the angular dependence of critical fields

Analysis of Critical Thinking Skills on The Topic of Static Fluid

Science.gov (United States)

Puspita, I.; Kaniawati, I.; Suwarma, I. R.

2017-09-01

This study aimed to know the critical thinking skills profil of senior high school students. This research using a descriptive study to analysis student test results of critical thinking skill of 40 students XI grade in one of the senior high school in Bogor District. The method used is survey research with sample determined by purposive sampling technique. The instrument used is test of critical thinking skill by 5 indicators on static fluid topics. Questions consist of 11 set. It is has been developed by researcher and validated by experts. The results showed students critical thinking skills are still low. Is almost every indicator of critical thinking skills only reaches less than 30%. 28% for elementary clarification, 10% for the basic for decisions/basic support, 6% for inference, 6% for advanced clarification, 4% for strategies and tactics.

Seismic Barrier Protection of Critical Infrastructure from Earthquakes

Science.gov (United States)

2017-05-01

We observe that such barrier structures reduce seismic wave powers by 10 – 40 dB that would otherwise reach the foundation location. Moreover, the... structure composed of opposing boreholes or trenches to mitigate seismic waves from diffracting and traveling in the vertical plane. Computational...seismic wave propagation models suggest that air or fluid filled subsurface V- shaped muffler structures are critical to the redirection and self

Search for the QCD critical point at SPS energies

CERN Document Server

Anticic, T.; Barna, D.; Bartke, J.; Betev, L.; Bialkowska, H.; Blume, C.; Boimska, B.; Botje, M.; Bracinik, J.; Buncic, P.; Cerny, V.; Christakoglou, P.; Chung, P.; Chvala, O.; Cramer, J.G.; Csato, P.; Dinkelaker, P.; Eckardt, V.; Fodor, Z.; Foka, P.; Friese, V.; Gal, J.; Gazdzicki, M.; Genchev, V.; Gladysz, E.; Grebieszkow, K.; Hegyi, S.; Hohne, C.; Kadija, K.; Karev, A.; Kikola, D.; Kolesnikov, V.I.; Kornas, E.; Korus, R.; Kowalski, M.; Kreps, M.; Laszlo, A.; Lacey, R.; van Leeuwen, M.; Levai, P.; Litov, L.; Lungwitz, B.; Makariev, M.; Malakhov, A.I.; Mateev, M.; Melkumov, G.L.; Mischke, A.; Mitrovski, M.; Mrowczynski, St.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Peryt, W.; Pikna, M.; Pluta, J.; Prindle, D.; Puhlhofer, F.; Renfordt, R.; Roland, C.; Roland, G.; Rybczynski, M.; Rybicki, A.; Sandoval, A.; Schmitz, N.; Schuster, T.; Seyboth, P.; Sikler, F.; Sitar, B.; Skrzypczak, E.; Slodkowski, M.; Stefanek, G.; Stock, R.; Strabel, C.; Strobele, H.; Susa, T.; Szentpetery, I.; Sziklai, J.; Szuba, M.; Szymanski, P.; Trubnikov, V.; Utvic, M.; Varga, D.; Vassiliou, M.; Veres, G.I.; Vesztergombi, G.; Vranic, D.; Wlodarczyk, Z.; Wojtaszek-Szwarc, A.; Yoo, I.K.; Abgrall, N.; Aduszkiewicz, A.; Andrieu, B.; Anticic, T.; Antoniou, N.; Argyriades, J.; Asryan, A.G.; Blondel, A.; Blumer, J.; Boldizsar, L.; Bravar, A.; Brzychczyk, J.; Bubak, A.; Bunyatov, S.A.; Choi, K.-U.; Chung, P.; Cleymans, J.; Derkach, D.A.; Diakonos, F.; Dominik, W.; Dumarchez, J.; Engel, R.; Ereditato, A.; Feofilov, G.A.; Ferrero, A.; Gazdzicki, M.; Golubeva, M.; Grzeszczuk, A.; Guber, F.; Hasegawa, T.; Haungs, A.; Igolkin, S.; Ivanov, A.S.; Ivashkin, A.; Katrynska, N.; Kielczewska, D.; Kisiel, J.; Kobayashi, T.; Kolev, D.; Kolevatov, R.S.; Kondratiev, V.P.; Kowalski, S.; Kurepin, A.; Lacey, R.; Lyubushkin, V.V.; Majka, Z.; Marchionni, A.; Marcinek, A.; Maris, I.; Matveev, V.; Meregaglia, A.; Messina, M.; Mijakowski, P.; Montaruli, T.; Murphy, S.; Nakadaira, T.; Naumenko, P.A.; Nikolic, V.; Nishikawa, K.; Palczewski, T.; Planeta, R.; Popov, B.A.; Posiadala, M.; Przewlocki, P.; Rauch, W.; Ravonel, M.; Rohrich, D.; Rondio, E.; Rossi, B.; Roth, M.; Rubbia, A.; Sadovsky, A.; Sakashita, K.; Sekiguchi, T.; Seyboth, P.; Shibata, M.; Sissakian, A.N.; Sorin, A.S.; Staszel, P.; Stepaniak, J.; Strabel, C.; Stroebele, H.; Tada, M.; Taranenko, A.; Tsenov, R.; Ulrich, R.; Unger, M.; Vechernin, V.V.; Zipper, W.

2009-01-01

Lattice QCD calculations locate the QCD critical point at energies accessible at the CERN Super Proton Synchrotron (SPS). We present average transverse momentum and multiplicity fluctuations, as well as baryon and anti-baryon transverse mass spectra which are expected to be sensitive to effects of the critical point. The future CP search strategy of the NA61/SHINE experiment at the SPS is also discussed.

Thoughts on Film: Critically Engaging with Both Adorno and Benjamin

Science.gov (United States)

D'Olimpio, Laura

2015-01-01

There is a traditional debate in analytic aesthetics that surrounds the classification of film as Art. While much philosophy devoted to considering film has now moved beyond this debate and accepts film as a mass art, a subcategory of Art proper, it is worth reconsidering the criticism of film pre-Deleuze. Much of the criticism of film as…

Configuring Product Modularity and Service Modularity for Mass Customization Strategies

DEFF Research Database (Denmark)

Bask, Anu; Hsuan, Juliana; Rajahonka, Mervi

, and how such configurations become the foundations for mass customization strategies. As a result we identify critical characteristics that are relevant for both product and services, and suggest a conceptual framework consisting of twelve dynamic mass customization strategies with paired product...

Psychosocial considerations for mass decontamination

International Nuclear Information System (INIS)

Lemyre, L.; Johnson, C.; Corneil, W.

2010-01-01

Mass exposure to explosions, infectious agents, food-borne illnesses, chemicals or radiological materials may require mass decontamination that have critical psychosocial implications for the public and for both traditional and non-traditional responders in terms of impact and of response. Five main issues are common to mass decontamination events: (i) perception, (ii) somatisation, (iii) media role and communication, (iv) information sharing, (v) behavioural guidance and (vi) organisational issues. Empirical evidence is drawn from a number of cases, including Chernobyl; Goiania, Brazil; the sarin gas attack in Tokyo; the anthrax attacks in the USA; Three Mile Island; and by features of the 2003 severe acute respiratory syndrome pandemic. In this paper, a common platform for mass casualty management is explored and suggestions for mass interventions are proposed across the complete event timeline, from pre-event threat and warning stages through to the impact and reconstruction phases. Implication for responders, health care and emergency infrastructure, public behaviour, screening processes, risk communication and media management are described. (authors)

Perceiver as polar planimeter: Direct perception of jumping, reaching, and jump-reaching affordances for the self and others.

Science.gov (United States)

Thomas, Brandon J; Hawkins, Matthew M; Nalepka, Patrick

2017-03-30

Runeson (Scandanavian Journal of Psychology 18:172-179, 1977) suggested that the polar planimeter might serve as an informative model system of perceptual mechanism. The key aspect of the polar planimeter is that it registers a higher order property of the environment without computational mediation on the basis of lower order properties, detecting task-specific information only. This aspect was posited as a hypothesis for the perception of jumping and reaching affordances for the self and another person. The findings supported this hypothesis. The perception of reaching while jumping significantly differed from an additive combination of jump-without-reaching and reach-without-jumping perception. The results are consistent with Gibson's (The senses considered as perceptual systems, Houghton Mifflin, Boston, MA; Gibson, The senses considered as perceptual systems, Houghton Mifflin, Boston, MA, 1966; The ecological approach to visual perception, Houghton Mifflin, Boston, MA; Gibson, The ecological approach to visual perception, Houghton Mifflin, Boston, MA, 1979) theory of information-that aspects of the environment are specified by patterns in energetic media.

Soil processes and functions in critical zone observatories: hypotheses and experimental design

NARCIS (Netherlands)

Banwart, S.; Bernasconi, S.M.; Bloem, J.; Blum, W.; Ruiter, de P.C.; Gaans, van P.; Riemsdijk, van W.H.

2011-01-01

European Union policy on soil threats and soil protection has prioritized new research to address global soil threats. This research draws on the methodology of Critical Zone Observatories (CZOs) to focus a critical mass of international, multidisciplinary expertise at specific field sites. These

Technical criteria for the prevention of criticality

Energy Technology Data Exchange (ETDEWEB)

Tomlinson, R E

1971-04-15

Atlantic Richfield Hanford Company (ARHCO) Policy Guide 1.6.6, 'Criticality Prevention' and Operating Instruction 1.6.6.2, 'Criticality Prevention in Process Facilities', present the policy of the Chemical Processing Division with respect to the control of criticality hazards, and delegate the responsibility for specifying safe limits for the design and operation of process facilities to the Manager, Research and Development Department. The purpose of this document is to define the technical criteria to be used in developing the limits within which CPD facilities are to be designed and operated. These criteria are based on the operating experience accumulated from the processing of fissile materials since the year 1944. The mere existence of a fissile material in quantities greater than a minimum critical mass creates some finite risk that criticality will occur. This risk of criticality can be held to a very low value by imposing restrictions on the manner in which the fissile material is stored or handled. Such controls are to be imposed as needed.

Technical criteria for the prevention of criticality

International Nuclear Information System (INIS)

Tomlinson, R.E.

1971-01-01

Atlantic Richfield Hanford Company (ARHCO) Policy Guide 1.6.6, 'Criticality Prevention' and Operating Instruction 1.6.6.2, 'Criticality Prevention in Process Facilities', present the policy of the Chemical Processing Division with respect to the control of criticality hazards, and delegate the responsibility for specifying safe limits for the design and operation of process facilities to the Manager, Research and Development Department. The purpose of this document is to define the technical criteria to be used in developing the limits within which CPD facilities are to be designed and operated. These criteria are based on the operating experience accumulated from the processing of fissile materials since the year 1944. The mere existence of a fissile material in quantities greater than a minimum critical mass creates some finite risk that criticality will occur. This risk of criticality can be held to a very low value by imposing restrictions on the manner in which the fissile material is stored or handled. Such controls are to be imposed as needed

Radiocarbon mass spectrometry for drug development

International Nuclear Information System (INIS)

Ulrich, Schulze-Konig Tim

2011-01-01

Full text: Radiocarbon has a huge potential as a tracer for metabolism studies in humans. By using Accelerator Mass Spectrometry (AMS) for its detection, a unique sensitivity is reached reducing required radiation doses to a negligible level. Until recently, a widespread use of AMS in biomedical research was impeded by the high complexity of the instrument, time-consuming sample preparation, and a limited availability of measurement capacity. Over the last few years, tremendous progress has been achieved in the reduction of size and complexity of AMS instruments. It allowed designing a compact AMS system, dubbed BioMICADAS to address the needs of biomedical users. For more than two years, this system is in successful operation at a commercial service provider for the pharmaceutical industry. A further drastic simplification of radiocarbon mass spectrometers seems possible and could establish a regular usage of this technology in drug development. However, to reach this goal a better integration of AMS into the workflow of bioanalytical laboratories will be necessary. For this purpose, CO 2 accepting ion sources may be a key, since they enable an almost automated sample preparation. The status of radiocarbon AMS in biomedical research and its perspective will be discussed

Critical potentials, leptons, and weak currents

International Nuclear Information System (INIS)

Smith, P.F.; Lewin, J.D.

1977-12-01

A theoretical study is made of the interaction of very strong localised electromagnetic potentials with charged leptons, and with the vacuum state. The principal objective is to investigate the phenomena which occur when the potential reaches or exceeds the critical value at which bound levels are drawn into the lower continuum. The behaviour of bound and continuum solutions of the Dirac equation for the specific model of a short range potential well in an arbitrarily large bounded volume is examined in detail. Vacuum polarisation effects are computed by summation over the infinite set of single particle levels, and special attention is given to the behaviour of the overall charge distribution as the potential strength increases through the critical value. The most significant features of the results are (a) the formation of highly localised electron or muon bound states, (b) similar critical potential strengths for electrons and muons, and (c) redefinition of the vacuum by one charge unit at the critical potential. These features are analogous to some properties of leptonic and hadronic weak currents, and the hypothesis is proposed that strong short range potentials may provide a possible mediating mechanism for the weak interaction and also a lepton confinement mechanism within the structure of hadrons. (author)

Tank 241-AZ-101 criticality assessment resulting from pump jet mixing: Sludge mixing simulation

Energy Technology Data Exchange (ETDEWEB)

Onishi, Y.; Recknagle, K.

1997-04-01

Tank 241-AZ-101 (AZ-101) is one of 28 double-shell tanks located in the AZ farm in the Hanford Site`s 200 East Area. The tank contains a significant quantity of fissile materials, including an estimated 9.782 kg of plutonium. Before beginning jet pump mixing for mitigative purposes, the operations must be evaluated to demonstrate that they will be subcritical under both normal and credible abnormal conditions. The main objective of this study was to address a concern about whether two 300-hp pumps with four rotating 18.3-m/s (60-ft/s) jets can concentrate plutonium in their pump housings during mixer pump operation and cause a criticality. The three-dimensional simulation was performed with the time-varying TEMPEST code to determine how much the pump jet mixing of Tank AZ-101 will concentrate plutonium in the pump housing. The AZ-101 model predicted that the total amount of plutonium within the pump housing peaks at 75 g at 10 simulation seconds and decreases to less than 10 g at four minutes. The plutonium concentration in the entire pump housing peaks at 0.60 g/L at 10 simulation seconds and is reduced to below 0.1 g/L after four minutes. Since the minimum critical concentration of plutonium is 2.6 g/L, and the minimum critical plutonium mass under idealized plutonium-water conditions is 520 g, these predicted maximums in the pump housing are much lower than the minimum plutonium conditions needed to reach a criticality level. The initial plutonium maximum of 1.88 g/L still results in safety factor of 4.3 in the pump housing during the pump jet mixing operation.

Tank 241-AZ-101 criticality assessment resulting from pump jet mixing: Sludge mixing simulation

International Nuclear Information System (INIS)

Onishi, Y.; Recknagle, K.

1997-04-01

Tank 241-AZ-101 (AZ-101) is one of 28 double-shell tanks located in the AZ farm in the Hanford Site's 200 East Area. The tank contains a significant quantity of fissile materials, including an estimated 9.782 kg of plutonium. Before beginning jet pump mixing for mitigative purposes, the operations must be evaluated to demonstrate that they will be subcritical under both normal and credible abnormal conditions. The main objective of this study was to address a concern about whether two 300-hp pumps with four rotating 18.3-m/s (60-ft/s) jets can concentrate plutonium in their pump housings during mixer pump operation and cause a criticality. The three-dimensional simulation was performed with the time-varying TEMPEST code to determine how much the pump jet mixing of Tank AZ-101 will concentrate plutonium in the pump housing. The AZ-101 model predicted that the total amount of plutonium within the pump housing peaks at 75 g at 10 simulation seconds and decreases to less than 10 g at four minutes. The plutonium concentration in the entire pump housing peaks at 0.60 g/L at 10 simulation seconds and is reduced to below 0.1 g/L after four minutes. Since the minimum critical concentration of plutonium is 2.6 g/L, and the minimum critical plutonium mass under idealized plutonium-water conditions is 520 g, these predicted maximums in the pump housing are much lower than the minimum plutonium conditions needed to reach a criticality level. The initial plutonium maximum of 1.88 g/L still results in safety factor of 4.3 in the pump housing during the pump jet mixing operation

Steady-state and transient studies on critical heat flux of a PWR 5 x 5 fuel element bundle with complex spacer wire geometry

International Nuclear Information System (INIS)

Fulfs, H.; Katsaounis, A.; Kreubig, M.; Minden, C. von; Orlowski, R.

1980-01-01

The results will be described in exemplary presentations completely and concluding. The experimental examination of the steady state simularity of critical heat flux (CHF) in freon 12 and water at identical PWR-5 x 15-rod bundles will show that hot rod/hot channels position as well as CHF can be transformed from model to original fluid with good accuracy. The investigated mass flow and power transients (only in freon 12) point out a definite influence of initial and boundary conditions on CHF and CHF time delay at changing rates higher than 10 to 20%/s. On the contrary simulation of primary pump failure (LOFA) shows no or only small improvement in CHF behaviour while a coupled Scram prevents from reaching the boiling crisis. (orig.) [de

Critical current of pure SNS junctions

International Nuclear Information System (INIS)

Golub, A.A.; Bezzub, O.P.

1982-01-01

Boundary conditions at the superconductor-normal metal interface are determined, taking into account the differences in the effective masses and the density of states of the metals constituting the transition and assumed to be pure. The potential barrier of the interface is chosen to be zero. The critical current of the junction is calculated [ru

Critical currents and flux-pinning properties in PbMo6S8 superconductors

International Nuclear Information System (INIS)

Noto, K.; Hamasaki, K.; Komata, T.; Saito, T.; Watanabe, K.; Yamashita, T.

1986-01-01

We report on recent investigations of the fabrication of PbMo 6 S 8 tapes prepared using an electro-plating and diffusion technique. Measurement of critical currents was carried out in either 16.5 T superconducting magnet, or 20.5 T (HM-3) and 23 T (HM-2) hybrid magnets in High Field Laboratory for Superconducting Materials RIISOM, Tohoku University in Japan. After optimal reaction the critical temperature measured by a resistive method reaches about 14.5 K, and a transition width was less than 0.5 K. Critical current densities are relatively high in a low magnetic field, and reached 1X10 4 A/cm 2 in a 15 T magnetic field at 4.2 K. However, J /SUB c/ 's in a strong magnetic field above 15 T are still insufficient for practical applications. In some of these samples pinning force densities were found to obey a simple scaling law, and in most cases the scaling is not obey. Poor J /SUB c/ -B characteristics in a strong magnetic field may be due to inhomogeneities of this compound

RECORDS REACHING RECORDING DATA TECHNOLOGIES

Directory of Open Access Journals (Sweden)

G. W. L. Gresik

2013-07-01

Full Text Available The goal of RECORDS (Reaching Recording Data Technologies is the digital capturing of buildings and cultural heritage objects in hard-to-reach areas and the combination of data. It is achieved by using a modified crane from film industry, which is able to carry different measuring systems. The low-vibration measurement should be guaranteed by a gyroscopic controlled advice that has been , developed for the project. The data were achieved by using digital photography, UV-fluorescence photography, infrared reflectography, infrared thermography and shearography. Also a terrestrial 3D laser scanner and a light stripe topography scanner have been used The combination of the recorded data should ensure a complementary analysis of monuments and buildings.

Records Reaching Recording Data Technologies

Science.gov (United States)

Gresik, G. W. L.; Siebe, S.; Drewello, R.

2013-07-01

The goal of RECORDS (Reaching Recording Data Technologies) is the digital capturing of buildings and cultural heritage objects in hard-to-reach areas and the combination of data. It is achieved by using a modified crane from film industry, which is able to carry different measuring systems. The low-vibration measurement should be guaranteed by a gyroscopic controlled advice that has been , developed for the project. The data were achieved by using digital photography, UV-fluorescence photography, infrared reflectography, infrared thermography and shearography. Also a terrestrial 3D laser scanner and a light stripe topography scanner have been used The combination of the recorded data should ensure a complementary analysis of monuments and buildings.

Critical and post-critical behaviour of two-degree-of-freedom flutter-based generators

Science.gov (United States)

Pigolotti, Luca; Mannini, Claudio; Bartoli, Gianni; Thiele, Klaus

2017-09-01

Energy harvesting from flow-induced vibrations is a recent research field, which considers a diverse range of systems, among which two-degree-of-freedom flutter-based solutions were individuated as good candidates to obtain high energy performance. In the present work, numerical linear analyses and wind-tunnel tests were conducted on a flat-plate sectional model. The aim is to identify some design guidelines for generators exploiting the classical-flutter instability, through the investigation of the critical condition and the response during the post-critical regime. Many sets of governing parameters of interest from the energy-harvesting point of view were considered, including high levels of heaving damping to simulate the operation of a conversion apparatus. In particular, eccentricity of the elastic centre and small downstream mass unbalance can be introduced as solutions aiming at optimal operative ranges. The collected results suggest the high potentiality of flutter-based generators, and a significant enhancement of performance can be envisaged. Moreover, they contribute to improve the knowledge of the flutter excitation mechanism and to widen the dataset of measurements in the post-critical regime.

Imagining Critical Cosmic Pedagogy nested within Critical Pedagogy

Directory of Open Access Journals (Sweden)

Isaacs Tracey I.

2015-02-01

Full Text Available The infinite problems attendant with mass public schooling requires evermore resilient and innovative theories to buttress an account of education that is socially defensible. While educational inequality could previously be attributed to developing nations due to their economic underdevelopment, developed nations too, with growing rapidity have to confront their internal burgeoning crises in education. It is against this backdrop that I focus on the possibility of expanding a notion of critical pedagogy by nesting the concept of cosmic pedagogy therein. As such, I draw on the Montessorian theory of cosmic education;Bazalukan theory of the formation of a planetary and cosmic personality; and Freireian critical pedagogy to discover the resonance and disharmony between these conceptual positions. Of the three theoretical frames, each can in their own right be considered a methodological approach to address particular problems in education and society at large. So it is with these theories and methods in mind that I suggest and reflect upon the ways that education might nudge us along in our attempt to be fully human and to occupy the space of intelligent matter in an ever expanding universe.

First mass measurements at LHCb

CERN Multimedia

Bressieux, J

2011-01-01

The LHC opens new frontiers in heavy flavour physics through an unprecedented statistical reach for a variety of interesting states produced in pp collisions. The LHCb spectrometer provides a good mass resolution and is suitable for spectroscopy studies. We present first preliminary mass measurements of several $b$ hadrons and of the exotic $X(3872)$ meson, reconstructed in final states containing a $J/\\psi$ using the data collected in 2010 by the LHCb experiment. An important aspect of the analysis is the calibration of the momentum scale using $J/\\psi \\to \\mu^+ \\mu^-$ decays, as well as the control of systematic uncertainties. While the already very competitive mass measurements for the $B^+$, $B^0$ and $B^0_s$ mesons receive similar contributions from systematic and statistical uncertainties, those of the $\\Lambda_b$, $B^+_c$ and $X(3872)$ particles are dominated by statistical uncertainties, and will therefore substantially improve with more data in the future.

Experimental study and technique for calculation of critical heat fluxes in helium boiling in tubes

International Nuclear Information System (INIS)

Arkhipov, V.V.; Kvasnyuk, S.V.; Deev, V.I.; Andreev, V.K.

1979-01-01

Studied is the effect of regime parameters on critical heat loads in helium boiling in a vertical tube in the range of mass rates of 80 2 xc) and pressures of 100<=p<=200 kPa for the vapor content range corresponding to the heat exchange crisis of the first kind. The method for calculating critical heat fluxes describing experimental data with the error less than +-15% is proposed. The critical heat loads in helium boiling in tubes reduce with the growth of pressure and vapor content in the regime parameter ranges under investigation. Both positive and negative effects of the mass rate on the critical heat flux are observed. The calculation method proposed satisfactorily describes the experimental data

Critical heat flux near the critical pressure in heater rod bundle cooled by R-134A fluid: Effects of unheated rods and spacer grid

International Nuclear Information System (INIS)

Chun, Se-Y.; Shin, C.W.; Hong, S. D.; Moon, S. K.

2007-01-01

A supercritical-pressure light water reactor (SCWR) is currently investigated as the next generation nuclear reactors. The SCWR, which is operated above the thermodynamic critical point of water (647 K, 22.1 MPa), have advantages over conventional light water reactors in terms of thermal efficiency as well as in compactness and simplicity. Many experimental studies have been performed on heat transfer in the boiler tubes of supercritical fossil fire power plants (FPPs). However, the thermal-hydraulic conditions of the SCWR core are different from those of the FPP boiler. In the SCWR core, the heat transfer to the cooling water occurs on the outside surface of fuel rods in rod bundle with spacers. In addition, the experimental studies in which the critical heat flux (CHF) has been carefully measured near the critical pressure have never yet been carried out, as far as we know. Therefore, we have recently conducted the CHF experiments with a vertical 5x5 heater rod bundle cooled by R- 134a fluid. The purpose of this work is to find out some novel knowledge for the CHF near the critical pressure, based on more careful experiments. The outer diameter, heated length and rod pitch of the heater rods are 9.5, 2000 and 12.85 mm, respectively. The critical power has been measured in a range of the pressure of 2.474.03 MPa (the critical pressure of R-134a is 4.059 MPa), the mass flux 502000 kg/m 2 s, and the inlet subcooling 4084 kJ/kg. For the mass fluxes of not less than 550 kg/m 2 s, the critical power decreases monotonously up to the pressure of about 3.63.8 MPa with increasing pressure, and then fall sharply at about 3.83.9 MPa as if the values of the critical power converge on zero at the critical pressure. For the low mass fluxes of 50 to 250 kg/m 2 , the sharp decreasing trend of the critical power near the critical pressure is not observed. The CHF phenomenon near the critical pressure no longer leads to an inordinate increase in the heated wall temperature such as

Critical Care Organizations: Building and Integrating Academic Programs.

Science.gov (United States)

Moore, Jason E; Oropello, John M; Stoltzfus, Daniel; Masur, Henry; Coopersmith, Craig M; Nates, Joseph; Doig, Christopher; Christman, John; Hite, R Duncan; Angus, Derek C; Pastores, Stephen M; Kvetan, Vladimir

2018-04-01

Academic medical centers in North America are expanding their missions from the traditional triad of patient care, research, and education to include the broader issue of healthcare delivery improvement. In recent years, integrated Critical Care Organizations have developed within academic centers to better meet the challenges of this broadening mission. The goal of this article was to provide interested administrators and intensivists with the proper resources, lines of communication, and organizational approach to accomplish integration and Critical Care Organization formation effectively. The Academic Critical Care Organization Building section workgroup of the taskforce established regular monthly conference calls to reach consensus on the development of a toolkit utilizing methods proven to advance the development of their own academic Critical Care Organizations. Relevant medical literature was reviewed by literature search. Materials from federal agencies and other national organizations were accessed through the Internet. The Society of Critical Care Medicine convened a taskforce entitled "Academic Leaders in Critical Care Medicine" on February 22, 2016 at the 45th Critical Care Congress using the expertise of successful leaders of advanced governance Critical Care Organizations in North America to develop a toolkit for advancing Critical Care Organizations. Key elements of an academic Critical Care Organization are outlined. The vital missions of multidisciplinary patient care, safety, and quality are linked to the research, education, and professional development missions that enhance the value of such organizations. Core features, benefits, barriers, and recommendations for integration of academic programs within Critical Care Organizations are described. Selected readings and resources to successfully implement the recommendations are provided. Communication with medical school and hospital leadership is discussed. We present the rationale for critical

Critical experiments on low-enriched uranium oxide system with H/U=1.25

International Nuclear Information System (INIS)

Oh, I.; Rothe, R.E.; Tuck, G.

1982-01-01

Fifteen (15) critical experiments were performed on a horizontal split table machine using 4.48%-enriched sup(235)U uranium oxide(U 3 O 8 ). The oxide was compacted to a density of 4.68g/cm 3 and placed in 152 mm cubical aluminum cans. Water was added to achive an H/U of 1.25. Various arrays of oxide cans were distributed on each half of the split table, and the separation between halves reduced until criticality occurred. The critical table separation varied from 3.59 mm to 18.40 mm. Twelve (12) experiments required the addition of a high-enriched(-93 %sup(235)U) metal or solution driver to achieve criticality. These experiments were performed in a plastic, concrete, or thin steel reflector. Three additional experiments in the plastic reflector contained either 9.3-mm- or 24.3-mm-thick plastic moderator material between the oxide cans and did not require a driver to achieve criticality. Critical uranium driver masses ranged from 9.999 kg to 14.000 kg (solution driver), and from 25.378 kg to 29.278 kg (metal driver) for 5X5X5 arrays of uranium oxide cans. Always, one or four of these 125 cans had to be removed to make room for the drivers. Therefore, the uranium oxide masses used were 1823.8 kg and 1863.5 kg. For the moderated experiments, the uranium oxide mass ranged between 574.4 kg and 1210.0 kg. (Author)

Continuous phase transition and critical behaviors of 3D black hole with torsion

International Nuclear Information System (INIS)

Ma, Meng-Sen; Liu, Fang; Zhao, Ren

2014-01-01

We study the phase transition and the critical behavior of the BTZ black hole with torsion obtained in (1 + 2)-dimensional Poincaré gauge theory. According to Ehrenfest’s classification, when the parameters in the theory are arranged properly, the BTZ black hole with torsion may possess the second-order phase transition which is also a smaller mass/larger mass black hole phase transition. Nevertheless, the critical behavior is different from the one in the van der Waals liquid/gas system. We also calculated the critical exponents of the relevant thermodynamic quantities, which are the same as the ones obtained in the Hořava-Lifshitz black hole and the Born–Infeld black hole. (paper)

A detailed reassessment of the criticality property of pure 241Am

International Nuclear Information System (INIS)

Ganesan, Srinivasan; Wienke, Harm

2002-01-01

We present results of new calculations of criticality of pure 241 Am using several basic evaluated neutron-nuclear cross section databases. The re-assessment of the criticality property of 241 Am presented in this paper is relevant to studies of criticality safety, nuclear waste incineration and non-proliferation. Our calculations start from the basic evaluated nuclear data files and use the NJOY-MCNP code system. This paper invalidates the earlier conclusion and belief in a section of the national and international literature that the minor actinide 241 Am is better than 235 U or 239 Pu as a nuclear fuel. Further our calculated critical mass is larger by 28% than the 197 kg reported in 1997 by Nojiri and Fukasaku who used the SCALE-4.3 system using the same ENDF/B-VI data, showing that there is large discrepancy due to the use of different computational codes and/or QA in nuclear data processing. Our calculated value of critical mass using JENDL-3.2 is 75 kg. This result is essentially in agreement with Nojiri and Fukasaku who used the same JENDL-3.2 data and the then available version of the NJOY-MCNP systems. (author)

Critical thinking: Its relevance for education in a shifting society

Directory of Open Access Journals (Sweden)

Leandro da Silva Almeida

2011-06-01

Full Text Available The amount of information and variety of situations tackled on a daily basis call for new cognitive functions, namely combining knowledge, experience and intellectual abilities. Critical thinking is valued as a higher-order type of reasoning and a skill transversal to the educational organisms. We introduce some definitions suggested in the literature, and describe the cognitive functions responsible for critical thinking used in learning and problem solving situations. We then present the most used assessment procedures, illustrating with instruments as well as programs and curricular planning implemented in the classroom to teach and develop critical thinking. Finally, we highlight the importance of further investigation, in order to reach a convergence of theoretical and practical elements needed to define critical thinking.

A survey of benthic sediment contaminants in reaches of the Columbia River Estuary based on channel sedimentation characteristics.

Science.gov (United States)

Counihan, Timothy D; Waite, Ian R; Nilsen, Elena B; Hardiman, Jill M; Elias, Edwin; Gelfenbaum, Guy; Zaugg, Steven D

2014-06-15

While previous studies have documented contaminants in fish, sediments, water, and wildlife, few specifics are known about the spatial distribution of contaminants in the Columbia River Estuary (CRE). Our study goal was to characterize sediment contaminant detections and concentrations in reaches of the CRE that were concurrently being sampled to assess contaminants in water, invertebrates, fish, and osprey (Pandion haliaetus) eggs. Our objectives were to develop a survey design based on sedimentation characteristics and then assess whether sediment grain size, total organic carbon (TOC), and contaminant concentrations and detections varied between areas with different sedimentation characteristics. We used a sediment transport model to predict sedimentation characteristics of three 16km river reaches in the CRE. We then compartmentalized the modeled change in bed mass after a two week simulation to define sampling strata with depositional, stable, or erosional conditions. We collected and analyzed bottom sediments to assess whether substrate composition, organic matter composition, and contaminant concentrations and detections varied among strata within and between the reaches. We observed differences in grain size fractions between strata within and between reaches. We found that the fine sediment fraction was positively correlated with TOC. Contaminant concentrations were statistically different between depositional vs. erosional strata for the industrial compounds, personal care products and polycyclic aromatic hydrocarbons class (Indus-PCP-PAH). We also observed significant differences between strata in the number of detections of Indus-PCP-PAH (depositional vs. erosional; stable vs. erosional) and for the flame retardants, polychlorinated biphenyls, and pesticides class (depositional vs. erosional, depositional vs. stable). When we estimated mean contaminant concentrations by reach, we observed higher contaminant concentrations in the furthest downstream

A survey of benthic sediment contaminants in reaches of the Columbia River Estuary based on channel sedimentation characteristics

Science.gov (United States)

Counihan, Timothy D.; Waite, Ian R.; Nilsen, Elena B.; Hardiman, Jill M.; Elias, Edwin; Gelfenbaum, Guy; Zaugg, Steven D.

2014-01-01

While previous studies have documented contaminants in fish, sediments, water, and wildlife, few specifics are known about the spatial distribution of contaminants in the Columbia River Estuary (CRE). Our study goal was to characterize sediment contaminant detections and concentrations in reaches of the CRE that were concurrently being sampled to assess contaminants in water, invertebrates, fish, and osprey (Pandion haliaetus) eggs. Our objectives were to develop a survey design based on sedimentation characteristics and then assess whether sediment grain size, total organic carbon (TOC), and contaminant concentrations and detections varied between areas with different sedimentation characteristics. We used a sediment transport model to predict sedimentation characteristics of three 16 km river reaches in the CRE. We then compartmentalized the modeled change in bed mass after a two week simulation to define sampling strata with depositional, stable, or erosional conditions. We collected and analyzed bottom sediments to assess whether substrate composition, organic matter composition, and contaminant concentrations and detections varied among strata within and between the reaches. We observed differences in grain size fractions between strata within and between reaches. We found that the fine sediment fraction was positively correlated with TOC. Contaminant concentrations were statistically different between depositional vs. erosional strata for the industrial compounds, personal care products and polycyclic aromatic hydrocarbons class (Indus–PCP–PAH). We also observed significant differences between strata in the number of detections of Indus–PCP–PAH (depositional vs. erosional; stable vs. erosional) and for the flame retardants, polychlorinated biphenyls, and pesticides class (depositional vs. erosional, depositional vs. stable). When we estimated mean contaminant concentrations by reach, we observed higher contaminant concentrations in the furthest

Seventh meeting of the Global Alliance to Eliminate Lymphatic Filariasis: reaching the vision by scaling up, scaling down, and reaching out

Science.gov (United States)

2014-01-01

This report summarizes the 7th meeting of the Global Alliance to Eliminate Lymphatic Filariasis (GAELF), Washington DC, November 18–19, 2012. The theme, “A Future Free of Lymphatic Filariasis: Reaching the Vision by Scaling Up, Scaling Down and Reaching Out”, emphasized new strategies and partnerships necessary to reach the 2020 goal of elimination of lymphatic filariasis (LF) as a public-health problem. PMID:24450283

Gravity-induced rock mass damage related to large en masse rockslides: Evidence from Vajont

Science.gov (United States)

Paronuzzi, Paolo; Bolla, Alberto

2015-04-01

The Vajont landslide is a well-known, reservoir-induced slope failure that occurred on 9 October 1963 and was characterized by an 'en masse' sliding motion that triggered various large waves, determining catastrophic consequences for the nearby territory and adjacent villages. During the Vajont dam construction, and especially after the disaster, some researchers identified widespread field evidence of heavy rock mass damage involving the presumed prehistoric rockslide and/or the 1963 failed mass. This paper describes evidence of heavy gravitational damage, including (i) folding, (ii) fracturing, (iii) faulting, and (iv) intact rock disintegration. The gravity-induced rock mass damage (GRMD) characterizes the remnants of the basal shear zone, still resting on the large detachment surface, and the 1963 failed rock mass. The comprehensive geological study of the 1963 Vajont landslide, based on the recently performed geomechanical survey (2006-present) and on the critical analysis of the past photographic documentation (1959-1964), allows us to recognize that most GRMD evidence is related to the prehistoric multistage Mt. Toc rockslide. The 1963 catastrophic en masse remobilization induced an increase to the prehistoric damage, reworking preexisting structures and creating additional gravity-driven features (folds, fractures, faults, and rock fragmentation). The gravity-induced damage was formed during the slope instability phases that preceded the collapse (static or quasi-static GRMD) and also as a consequence of the sliding motion and of the devastating impact between the failed blocks (dynamic GRMD). Gravitational damage originated various types of small drag folds such as flexures, concentric folds, chevron, and kink-box folds, all having a radius of 1-5 m. Large buckle folds (radius of 10-50 m) are related to the dynamic damage and were formed during the en masse motion as a consequence of deceleration and impact processes that involved the sliding mass. Prior

THE OVERDENSITY AND MASSES OF THE FRIENDS-OF-FRIENDS HALOS AND UNIVERSALITY OF HALO MASS FUNCTION

International Nuclear Information System (INIS)

More, Surhud; Kravtsov, Andrey V.; Dalal, Neal; Gottloeber, Stefan

2011-01-01

The friends-of-friends algorithm (hereafter FOF) is a percolation algorithm which is routinely used to identify dark matter halos from N-body simulations. We use results from percolation theory to show that the boundary of FOF halos does not correspond to a single density threshold but to a range of densities close to a critical value that depends upon the linking length parameter, b. We show that for the commonly used choice of b = 0.2, this critical density is equal to 81.62 times the mean matter density. Consequently, halos identified by the FOF algorithm enclose an average overdensity which depends on their density profile (concentration) and therefore changes with halo mass, contrary to the popular belief that the average overdensity is ∼180. We derive an analytical expression for the overdensity as a function of the linking length parameter b and the concentration of the halo. Results of tests carried out using simulated and actual FOF halos identified in cosmological simulations show excellent agreement with our analytical prediction. We also find that the mass of the halo that the FOF algorithm selects crucially depends upon mass resolution. We find a percolation-theory-motivated formula that is able to accurately correct for the dependence on number of particles for the mock realizations of spherical and triaxial Navarro-Frenk-White halos. However, we show that this correction breaks down when applied to the real cosmological FOF halos due to the presence of substructures. Given that abundance of substructure depends on redshift and cosmology, we expect that the resolution effects due to substructure on the FOF mass and halo mass function will also depend on redshift and cosmology and will be difficult to correct for in general. Finally, we discuss the implications of our results for the universality of the mass function.

REACH: next step to a sound chemicals management.

Science.gov (United States)

Van der Wielen, Arnold

2007-12-01

REACH is the new European Regulation for Registration, Evaluation, Authorisation and Restriction of Chemicals. It entered into force on 1st June 2007 to streamline and improve the former legislative framework on new and on existing chemical substances of the European Union. Companies which manufacture or import more than 1 tonne of a substance per year will be required to register the substance at the new EU Chemicals Agency located in Helsinki. REACH places greater responsibility on industry to manage the risks that chemicals may pose to the health and the environment and to provide safety information that will be passed down the supply chain. In principle, REACH applies to all chemicals as such, as components in preparations and as used in articles. REACH is a radical step forward in the EU chemicals management. The onus will move from the authorities to industry. In addition, REACH will allow the further evaluation of substances where there are grounds for concern, foresees an authorisation system for the use of substances of very high concern and a system of restrictions, where applicable, for substances of concern. The Authorisation system will require companies to switch progressively to safer alternatives where a suitable alternative exists. Current use restrictions will remain under REACH system.

Thermal power blocks with ultra-super-critical steam parameters

Directory of Open Access Journals (Sweden)

Aličić Merim M.

2016-01-01

Full Text Available New generation of thermal power plants are required to have increased utilization rates, in addition to reduced emissions of pollutants, in order to reach optimal solutions, from both technical and economic point of view. One way to achieve greater utilization efficiency is operation of the plant at super critical (SC or ultra super critical steam parameters (USC. However, achieving high parameters depends on use of new materials, which have better properties at high temperatures and pressures, use of new welding technologies and by solving the problem of corrosion. The paper gives an overview of some of the plants with these parameters.

Mapping the feel of the arm with the sight of the object: On the embodied origins of infant reaching

Directory of Open Access Journals (Sweden)

Daniela eCorbetta

2014-06-01

Full Text Available For decades, the emergence and progression of infant reaching was assumed to be largely under the control of vision. More recently, however, the guiding role of vision in the emergence of reaching has been downplayed. Studies found that young infants can reach in the dark without seeing their hand and that corrections in infants’ initial hand trajectories are not the result of visual guidance of the hand, but rather the product of poor movement speed calibration to the goal. As a result, it has been proposed that learning to reach is an embodied process requiring infants to explore proprioceptively different movement solutions, before they can accurately map their actions onto the intended goal. Such an account, however, could still assume a preponderant (or prospective role of vision, where the movement is being monitored with the scope of approximating a future goal-location defined visually. At reach onset, it is unknown if infants map their action onto their vision, vision onto their action, or both. To examine how infants learn to map the feel of their hand with the sight of the object, we tracked the object-directed looking behavior (via eye-tracking of three infants followed weekly over an 11-week period throughout the transition to reaching. We also examined where they contacted the object. We find that with some objects, infants do not learn to align their reach to where they look, but rather learn to align their look to where they reach. We propose that the emergence of reaching is the product of a deeply embodied process, in which infants first learn how to direct their movement in space using proprioceptive and haptic feedback from self-produced movement contingencies with the environment. As they do so, they learn to map visual attention onto these bodily centered experiences, not the reverse. We suggest that this early visuo-motor mapping is critical for the formation of visually-elicited, prospective movement control.

Peer Support for the Hardly Reached: A Systematic Review.

Science.gov (United States)

Sokol, Rebeccah; Fisher, Edwin

2016-07-01

Health disparities are aggravated when prevention and care initiatives fail to reach those they are intended to help. Groups can be classified as hardly reached according to a variety of circumstances that fall into 3 domains: individual (e.g., psychological factors), demographic (e.g., socioeconomic status), and cultural-environmental (e.g., social network). Several reports have indicated that peer support is an effective means of reaching hardly reached individuals. However, no review has explored peer support effectiveness in relation to the circumstances associated with being hardly reached or across diverse health problems. To conduct a systematic review assessing the reach and effectiveness of peer support among hardly reached individuals, as well as peer support strategies used. Three systematic searches conducted in PubMed identified studies that evaluated peer support programs among hardly reached individuals. In aggregate, the searches covered articles published from 2000 to 2015. Eligible interventions provided ongoing support for complex health behaviors, including prioritization of hardly reached populations, assistance in applying behavior change plans, and social-emotional support directed toward disease management or quality of life. Studies were excluded if they addressed temporally isolated behaviors, were limited to protocol group classes, included peer support as the dependent variable, did not include statistical tests of significance, or incorporated comparison conditions that provided appreciable social support. We abstracted data regarding the primary health topic, categorizations of hardly reached groups, program reach, outcomes, and strategies employed. We conducted a 2-sample t test to determine whether reported strategies were related to reach. Forty-seven studies met our inclusion criteria, and these studies represented each of the 3 domains of circumstances assessed (individual, demographic, and cultural-environmental). Interventions

Hydromechanical Rock Mass Fatigue in Deep-Seated Landslides Accompanying Seasonal Variations in Pore Pressures

Science.gov (United States)

Preisig, Giona; Eberhardt, Erik; Smithyman, Megan; Preh, Alexander; Bonzanigo, Luca

2016-06-01

The episodic movement of deep-seated landslides is often governed by the presence of high pore pressures and reduced effective stresses along active shear surfaces. Pore pressures are subject to cyclic fluctuation under seasonal variations of groundwater recharge, resulting in an intermittent movement characterized by acceleration-deceleration phases. However, it is not always clear why certain acceleration phases reach alarming levels without a clear trigger (i.e., in the absence of an exceptional pore pressure event). This paper presents a conceptual framework linking hydromechanical cycling, progressive failure and fatigue to investigate and explain the episodic behavior of deep-seated landslides using the Campo Vallemaggia landslide in Switzerland as a case study. A combination of monitoring data and advanced numerical modeling is used. The principal processes forcing the slope into a critical disequilibrium state are analyzed as a function of rock mass damage and fatigue. Modeling results suggest that during periods of slope acceleration, the rock slope experiences localized fatigue and gradual weakening through slip along pre-existing natural fractures and yield of critically stressed intact rock bridges. At certain intervals, pockets of critically weakened rock may produce a period of enhanced slope movement in response to a small pore pressure increase similar to those routinely experienced each year. Accordingly, the distribution and connectivity of pre-existing permeable planes of weakness play a central role. These structures are often related to the rock mass's tectonic history or initiate (and dilate) in response to stress changes that disturb the entire slope, such as glacial unloading or seismic loading via large earthquakes. The latter is discussed in detail in a companion paper to this (Gischig et al., Rock Mech Rock Eng, 2015). The results and framework presented further demonstrate that episodic movement and progressive failure of deep

Using mass-media communications to increase population usage of Australia’s Get Healthy Information and Coaching Service®

Directory of Open Access Journals (Sweden)

O’Hara Blythe J

2012-09-01

Full Text Available Abstract Background Global obesity prevalence is increasing and population health programs are required to support changes to modifiable lifestyle risk factors. Such interventions benefit from mass-communications to promote their use. The Get Healthy Information and Coaching Service ® (GHS utilised mass-reach media advertising to recruit participants to an Australian state-wide program. Methods A stand alone population survey collected awareness, knowledge and behavioural variables before the first advertising phase, (n = 1,544; August -September 2010, during (n = 1,500; February - March 2011 and after the advertising period (n = 1,500; June-July 2011. GHS usage data (n = 6,375 was collated during July 2010 – June 2011. Results The results showed that television-lead mass-media significantly increased unprompted awareness (0% to 31.8%, p  Conclusions GHS mass-communications campaigns are effective at increasing awareness and usage of the GHS, especially among hard-to-reach population groups. Television advertising provides universal reach, but should be supplemented by health professional referrals and targeted mail-out information to recruit participants to the intensive GHS coaching program.

Criticality assessment of LLRWDF closure

International Nuclear Information System (INIS)

Sarrack, A.G.; Weber, J.H.; Woody, N.D.

1992-01-01

During the operation of the Low Level Radioactive Waste Disposal Facility (LLRWDF), large amounts (greater than 100 kg) of enriched uranium (EU) were buried. This EU came primarily from the closing and decontamination of the Naval Fuels Facility in the time period from 1987--1989. Waste Management Operations (WMO) procedures were used to keep the EU boxes separated to prevent possible criticality during normal operation. Closure of the LLRWDF is currently being planned, and waste stabilization by Dynamic Compaction (DC) is proposed. Dynamic compaction will crush the containers in the LLRWDF and result in changes in their geometry. Research of the LLRWDF operations and record keeping practices have shown that the EU contents of trenches are known, but details of the arrangement of the contents cannot be proven. Reviews of the trench contents, combined with analysis of potential critical configurations, revealed that some portions of the LLRWDF can be expected to be free of criticality concerns while other sections have credible probabilities for the assembly of a critical mass, even in the uncompacted configuration. This will have an impact on the closure options and which trenches can be compacted

Can impurities from soil-contaminated coffees reach the cup?

International Nuclear Information System (INIS)

Tagliaferro, F.S.; De Nadai Fernandes, E.A.; Bacchi, M.A.; Joacir De Franca, E.; Bode, P.

2007-01-01

Depending on the harvest conditions, coffee beans can be contaminated by soil when dropped to the ground. It is well known that agricultural soils act as sinks for agrochemicals applied to the crops. While coffee is brewed, substances present in the roasted and ground coffee beans are extracted by hot water, emphasizing the need to assess the possible transfer of impurities from the soil to the beverage. Soil-contaminated samples of roasted coffee beans were split into 2 groups according to the treatments: (a) washed and ground and (b) only ground. Brewing was performed in a household espresso machine for both coffees. The resulting beverage was freeze-dried and the elemental composition determined by instrumental neutron activation analysis (INAA). The mass fractions of the terrigenous elements Fe, La, Sc, Sm and Th in the freeze-dried non-washed coffee beverages were, at least, 2 times higher than in the washed samples. These elements are tracers of the soil, indicating that the impurities from the soil reached the beverage. (author)

Critical behavior from Schrodinger representation

International Nuclear Information System (INIS)

Suranyi, P.

1992-01-01

In this paper, the Schrodinger equation for φ 4 field theory is reduced to an infinite set of integral equations. A systematic truncation scheme is proposed and it is solved in second order to obtain the approximate critical behavior of the renormalized mass. The correlation exponent is given as a solution of a transcendental equation. It is in good agreement with the Ising model in all physical dimensions

Nuclear criticality safety: 300 Area

International Nuclear Information System (INIS)

1991-01-01

This Standard applies to the receipt, processing, storage, and shipment of fissionable material in the 300 Area and in any other facility under the control of the Reactor Materials Project Management Team (PMT). The objective is to establish practices and process conditions for the storage and handling of fissionable material that prevent the accidental assembly of a critical mass and that comply with DOE Orders as well as accepted industry practice

On systematic and statistic errors in radionuclide mass activity estimation procedure

International Nuclear Information System (INIS)

Smelcerovic, M.; Djuric, G.; Popovic, D.

1989-01-01

One of the most important requirements during nuclear accidents is the fast estimation of the mass activity of the radionuclides that suddenly and without control reach the environment. The paper points to systematic errors in the procedures of sampling, sample preparation and measurement itself, that in high degree contribute to total mass activity evaluation error. Statistic errors in gamma spectrometry as well as in total mass alpha and beta activity evaluation are also discussed. Beside, some of the possible sources of errors in the partial mass activity evaluation for some of the radionuclides are presented. The contribution of the errors in the total mass activity evaluation error is estimated and procedures that could possibly reduce it are discussed (author)

Newer methods for the characterization of higher molecular mass coal derivatives

International Nuclear Information System (INIS)

Bartle, K.D.

1983-01-01

Recent developments in a number of areas in the analytical chemistry of higher molecular mass coal derivatives are critically reviewed, viz. supercritical fluid chromatography, size-exclusion chromatography, charge-transfer fractionation, nmr spectroscopy, mass spectrometry and electrochemical analysis. (orig.) [de

Reaching ignition in the tokamak

International Nuclear Information System (INIS)

Furth, H.P.

1985-06-01

This review covers the following areas: (1) the physics of burning plasmas, (2) plasma physics requirements for reaching ignition, (3) design studies for ignition devices, and (4) prospects for an ignition project

Reporting the methodology of height and weight acquisition in studies of body mass index-based prognosis in critically ill patients.

Science.gov (United States)

Oud, Lavi

2013-10-01

Conflicting findings were reported on the body mass index (BMI)-based prognosis of critically patients. Errors in source weight and height data can confound BMI group allocation. The aim of the present work was to examine investigators' reporting on the methods of height and weight acquisition (HWA). PubMed and Embase databases were searched for studies describing BMI group-based risk of death in critically ill patients. Eligible studies were examined for reporting on (1) the use of measured and/or estimated HWA, (2) details of measuring devices, (3) device accuracy, and (4) methods of adjustment for acute and chronic fluid-related weight changes. Thirty studies met the eligibility criteria, including 159,565 patients. No data were provided in 13 studies (52% of reported patients) on whether estimates or measurements were used for HWA. Measured HWA was used exclusively in 6 studies (3% of patients), and an unspecified combination of estimated and/or measured HWA was reported for the remainder. Only 1 study reported the specific devices used. None of the studies provided data on the bias and precision of measuring devices. Adjustment for chronic and/or acute fluid-related weight changes was addressed in 2 studies for each. These findings demonstrate the prevalent risk for BMI group misallocation in the reviewed studies, which may confound BMI-based prognosis, raising concerns about the validity of reported BMI-related prognostic impact. Copyright © 2013 Elsevier Inc. All rights reserved.

Do working environment interventions reach shift workers?

Science.gov (United States)

Nabe-Nielsen, Kirsten; Jørgensen, Marie Birk; Garde, Anne Helene; Clausen, Thomas

2016-01-01

Shift workers are exposed to more physical and psychosocial stressors in the working environment as compared to day workers. Despite the need for targeted prevention, it is likely that workplace interventions less frequently reach shift workers. The aim was therefore to investigate whether the reach of workplace interventions varied between shift workers and day workers and whether such differences could be explained by the quality of leadership exhibited at different times of the day. We used questionnaire data from 5361 female care workers in the Danish eldercare sector. The questions concerned usual working hours, quality of leadership, and self-reported implementation of workplace activities aimed at stress reduction, reorganization of the working hours, and participation in improvements of working procedures or qualifications. Compared with day workers, shift workers were less likely to be reached by workplace interventions. For example, night workers less frequently reported that they had got more flexibility (OR 0.5; 95 % CI 0.3-0.7) or that they had participated in improvements of the working procedures (OR 0.6; 95 % CI 0.5-0.8). Quality of leadership to some extent explained the lack of reach of interventions especially among fixed evening workers. In the light of the evidence of shift workers' stressful working conditions, we suggest that future studies focus on the generalizability of results of the present study and on how to reach this group and meet their needs when designing and implementing workplace interventions.

The use of spatio-temporal correlation to forecast critical transitions

Science.gov (United States)

Karssenberg, Derek; Bierkens, Marc F. P.

2010-05-01

Complex dynamical systems may have critical thresholds at which the system shifts abruptly from one state to another. Such critical transitions have been observed in systems ranging from the human body system to financial markets and the Earth system. Forecasting the timing of critical transitions before they are reached is of paramount importance because critical transitions are associated with a large shift in dynamical regime of the system under consideration. However, it is hard to forecast critical transitions, because the state of the system shows relatively little change before the threshold is reached. Recently, it was shown that increased spatio-temporal autocorrelation and variance can serve as alternative early warning signal for critical transitions. However, thus far these second order statistics have not been used for forecasting in a data assimilation framework. Here we show that the use of spatio-temporal autocorrelation and variance in the state of the system reduces the uncertainty in the predicted timing of critical transitions compared to classical approaches that use the value of the system state only. This is shown by assimilating observed spatio-temporal autocorrelation and variance into a dynamical system model using a Particle Filter. We adapt a well-studied distributed model of a logistically growing resource with a fixed grazing rate. The model describes the transition from an underexploited system with high resource biomass to overexploitation as grazing pressure crosses the critical threshold, which is a fold bifurcation. To represent limited prior information, we use a large variance in the prior probability distributions of model parameters and the system driver (grazing rate). First, we show that the rate of increase in spatio-temporal autocorrelation and variance prior to reaching the critical threshold is relatively consistent across the uncertainty range of the driver and parameter values used. This indicates that an increase in

The nature of Λ and the mass of the graviton: A critical view

International Nuclear Information System (INIS)

Gazeau, J.P.; Novello, M.

2006-10-01

The existence of a non-zero cosmological constant Λ gives rise to controversial interpretations. Is Λ a universal constant fixing the geometry of an empty universe, as fundamental as the Planck constant or the speed of light in the vacuum? Its natural place is then on the left-hand side of the Einstein equation. Is it instead something emerging from a perturbative calculus performed on the metric g μν solution of the Einstein equation and to which it might be given a material status of (dark or bright) 'energy'? It should then be part of the content of the right-hand side of the Einstein equations. The purpose of this paper is not to elucidate the fundamental nature of Λ, but instead we aim to present and discuss some of the arguments in favor of both interpretations of the cosmological constant. We will analyse the question of a Λ-dependent graviton mass, more precisely the possibility that between the Compton wavelength of the graviton and the cosmological constant there is the relation l g Λ 1/ 2 ≅ 1. Since a physical quantity like mass originates in a Minkowski conservation law, we proceed to a group theoretical interpretation of this relation in terms of the two possible Λ-deformations of the Poincare group, namely the de Sitter and anti de Sitter groups. We use a very suitable formula, the so-called Garidi mass, and the typically dS/AdS dimensionless parameter ℎH/mc 2 in order to make clear the asymptotic relations between Minkowski masses m and their possible dS/AdS counterparts. We conclude that if the fundamental of the geometry of space-time is Minkowskian, then the square of the mass of the graviton is proportional to Λ; otherwise, if the fundamental state is deSitter/AdS, then the graviton is massless in the deSitterian sense. (authors)

Kaon mass by critical absorption of kaonic atom x rays

International Nuclear Information System (INIS)

Lum, G.K.

1979-10-01

The energy of the kaonic 6h → 5g transition has been determined using the calculated μ/rho curve. Because the detectors used could not resolve the noncircular transitions, the predictions from a calculated cascade program were used. According to the cascade results for potassium, the number of noncircular x-rays was about 10% of all the transitions between n = 6 to n = 5. Based on the available information, the mass of the kaon was measured to be 493.576/sub -0.069//sup +0.044/ MeV

Functional impacts of ocean acidification in an ecologically critical foundation species.

Science.gov (United States)

Gaylord, Brian; Hill, Tessa M; Sanford, Eric; Lenz, Elizabeth A; Jacobs, Lisa A; Sato, Kirk N; Russell, Ann D; Hettinger, Annaliese

2011-08-01

Anthropogenic CO(2) is reducing the pH and altering the carbonate chemistry of seawater, with repercussions for marine organisms and ecosystems. Current research suggests that calcification will decrease in many species, but compelling evidence of impaired functional performance of calcium carbonate structures is sparse, particularly in key species. Here we demonstrate that ocean acidification markedly degrades the mechanical integrity of larval shells in the mussel Mytilus californianus, a critical community member on rocky shores throughout the northeastern Pacific. Larvae cultured in seawater containing CO(2) concentrations expected by the year 2100 (540 or 970 ppm) precipitated weaker, thinner and smaller shells than individuals raised under present-day seawater conditions (380 ppm), and also exhibited lower tissue mass. Under a scenario where mussel larvae exposed to different CO(2) levels develop at similar rates, these trends suggest a suite of potential consequences, including an exacerbated vulnerability of new settlers to crushing and drilling attacks by predators; poorer larval condition, causing increased energetic stress during metamorphosis; and greater risks from desiccation at low tide due to shifts in shell area to body mass ratios. Under an alternative scenario where responses derive exclusively from slowed development, with impacted individuals reaching identical milestones in shell strength and size by settlement, a lengthened larval phase could increase exposure to high planktonic mortality rates. In either case, because early life stages operate as population bottlenecks, driving general patterns of distribution and abundance, the ecological success of this vital species may be tied to how ocean acidification proceeds in coming decades.

Alecto - results obtained with homogeneous critical experiments on plutonium 239, uranium 235 and uranium 233

International Nuclear Information System (INIS)

Bruna, J.G.; Brunet, J.P.; Caizegues, R.; Clouet d'Orval, Ch.; Kremser, J.; Tellier, H.; Verriere, Ph.

1965-01-01

In this report are given the results of the homogeneous critical experiments ALECTO, made on plutonium 239, uranium 235 and uranium 233. After a brief description of the equipment, the critical masses for cylinders of diameters varying from 25 to 42 cm, are given and compared with other values (foreign results, criticality guide). With respect to the specific conditions of neutron reflection in the ALECTO experiments the minimal values of critical masses are: Pu239 M c = 910 ± 10 g, U235 M c = 1180 ± 12 g and U233 M c = 960 ± 10 g. Experiments relating to cross sections and constants to be used on these materials are presented. Lastly, kinetic experiments allow to compare pulsed neutron methods to fluctuation methods [fr

Evolvement of nuclear criticality safety programs

International Nuclear Information System (INIS)

Ketzlach, N.

1992-01-01

Nuclear criticality safety (NCS) has developed from a discipline requiring the services of personnel with only a background in reactor physics to that involving reactor physics, process engineering, and design as well as administration of the program to ensure all its requirements are implemented. When Oak Ridge National Laboratory (ORNL) was designed and constructed, the physicists at Los Alamos National Laboratory (LANL) were performing the criticality analyses. A physicist who had no chemical process or engineering experience was brought in from LANL to determine whether the facility would be safe. It was only because of his understanding of the reactor physics principles, scientific intuition, and some luck that the design and construction of the facility led to a safe plant. It took a number of years of experience with facility operations and the dedication of personnel for NCS to reach its present status as a recognized discipline

Handbook on Securing Cyber-Physical Critical Infrastructure

CERN Document Server

Das, Sajal K; Zhang, Nan

2012-01-01

The worldwide reach of the Internet allows malicious cyber criminals to coordinate and launch attacks on both cyber and cyber-physical infrastructure from anywhere in the world. This purpose of this handbook is to introduce the theoretical foundations and practical solution techniques for securing critical cyber and physical infrastructures as well as their underlying computing and communication architectures and systems. Examples of such infrastructures include utility networks (e.g., electrical power grids), ground transportation systems (automotives, roads, bridges and tunnels), airports a

"More Complicated than a Numbers Game": A Critical Race Theory Examination of Asian Americans and Campus Racial Climate

Science.gov (United States)

Poon, Oi Yan Anita

2010-01-01

In the Grutter and Gratz Supreme Court decision, proponents of affirmative action claimed that a critical mass of minority students could effectively counter racial marginalization often experienced by students of color due to their racial status. On some campuses, Asian Americans as a pan-ethnic population enjoy a critical mass in undergraduate…

Guaranteed performance in reaching mode of sliding mode ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

addresses the design of constant plus proportional rate reaching law-based SMC for second-order ... Reaching mode; sliding mode controlled systems; output tracking ... The uncertainty in the input distribution function g is expressed as.

Requirements on waste forms for the planned Konrad repository based on criticality calculations

International Nuclear Information System (INIS)

Berg, H.P.

1988-02-01

In the framework of the safety analyses for the planned Konrad repository it has been investigated whether a criticality incident may be possible during the operational phase or in the post-operational phase. The analysis has shown that the criticality safety is ensured by limitation of a mass concentration of the fissile material in the waste form group and by determination of a maximum permissible mass of fissile material per waste package. The resulting requirements of the waste packages, including a mixture in the cross-section of an emplacement room, are explained. (orig.) [de

Visuo-proprioceptive interactions during adaptation of the human reach.

Science.gov (United States)

Judkins, Timothy; Scheidt, Robert A

2014-02-01

We examined whether visual and proprioceptive estimates of transient (midreach) target capture errors contribute to motor adaptation according to the probabilistic rules of information integration used for perception. Healthy adult humans grasped and moved a robotic handle between targets in the horizontal plane while the robot generated springlike loads that varied unpredictably from trial to trial. For some trials, a visual cursor faithfully tracked hand motion. In others, the handle's position was locked and subjects viewed motion of a point-mass cursor driven by hand forces. In yet other trials, cursor feedback was dissociated from hand motion or altogether eliminated. We used time- and frequency-domain analyses to characterize how sensorimotor memories influence performance on subsequent reaches. When the senses were used separately, subjects were better at rejecting physical disturbances applied to the hand than virtual disturbances applied to the cursor. In part, this observation reflected differences in how participants used sensorimotor memories to adapt to perturbations when performance feedback was limited to only proprioceptive or visual information channels. When both vision and proprioception were available to guide movement, subjects processed memories in a manner indistinguishable from the vision-only condition, regardless of whether the cursor tracked the hand faithfully or whether we experimentally dissociated motions of the hand and cursor. This was true even though, on average, perceptual uncertainty in the proprioceptive estimation of movement extent exceeded that of visual estimation by just 47%. In contrast to perceptual tasks wherein vision and proprioception both contribute to an optimal estimate of limb state, our findings support a switched-input, multisensory model of predictive load compensation wherein visual feedback of transient performance errors overwhelmingly dominates proprioception in determining adaptive reach performance.

Reflections on imaging diagnosis of sella masses

International Nuclear Information System (INIS)

Hernandez Yero, Jose Arturo; Jorge Gonzalez, Raquel

2005-01-01

Some reflections were made on imaging diagnosis of sella masses, specifying some characteristics of the main sella masses and their appearance in magnetic resonance imaging. The purpose was to call the attention on this important issue on the basis that modern imaging advances offer very useful distinctive elements in the diagnosis of a group of masses located in the sella turcica region. The paper underlined details of signal intensity in pituitary adenomas, craniopharyngiomas, Rathkes pouch cysts, hypophyseal hyperplasia and the so-called empty sella syndrome, among other causes of anatomical changes in sella region. It was concluded that magnetic resonance imaging would be the ideal method for a better diagnosis of sella masses, but if this technique was not available, then contrast-enhanced tomography would be useful in under 2 mm views. The importance of a multidisciplinary team of clinicians, endocrinologists, imaging specialists, neurosurgeons and anatomy pathologists to reach more accurate diagnosis and better therapeutic results was stressed

Initial conceptual design study of self-critical nuclear pumped laser systems

Science.gov (United States)

Rodgers, R. J.

1979-01-01

An analytical study of self-critical nuclear pumped laser system concepts was performed. Primary emphasis was placed on reactor concepts employing gaseous uranium hexafluoride (UF6) as the fissionable material. Relationships were developed between the key reactor design parameters including reactor power level, critical mass, neutron flux level, reactor size, operating pressure, and UF6 optical properties. The results were used to select a reference conceptual laser system configuration. In the reference configuration, the 3.2 m cubed lasing volume is surrounded by a graphite internal moderator and a region of heavy water. Results of neutronics calculations yield a critical mass of 4.9 U(235) in the form (235)UF6. The configuration appears capable of operating in a continuous steady-state mode. The average gas temperature in the core is 600 K and the UF6 partial pressure within the lasing volume is 0.34 atm.

A RE-INTRODUCTION TO ANOMALIES OF CRITICALITY

International Nuclear Information System (INIS)

Puigh, R.J.

2009-01-01

In 1974, a small innocuous document was submitted to the American Nuclear Society's Criticality Safety Division for publication that would have lasting impacts on this nuclear field The author was Duane Clayton, manager of the Battelle Pacific Northwest National Laboratory's Critical Mass Lab, the world's preeminent reactor critical experimenter with plutonium solutions. The document was entitled, 'Anomalies of Criticality'. 'Anomalies...' was a compilation of more than thirty separate and distinct examples of departures from what might be commonly expected in the field of nuclear criticality. Mr. Clayton's publication was the derivative of more than ten thousand experiments and countless analytical studies conducted world-wide on every conceivable reactor system imaginable: from fissile bearing solutions to solids, blocks to arrays of fuel rods, low-enriched uranium oxide systems to pure plutonium and highly enriched uranium systems. After publication, the document was commonly used within the nuclear fuel cycle and reactor community to train potential criticality/reactor analysts, experimenters and fuel handlers on important things for consideration when designing systems with critically 'safe' parameters in mind The purpose of this paper is to re-introduce 'Anomalies of Criticality' to the current Criticality Safety community and to add new 'anomalies' to the existing compendium. By so doing, it is the authors' hope that a new generation of nuclear workers and criticality engineers will benefit from its content and might continue to build upon this work in support of the nuclear renaissance that is about to occur

Chain length dependence of the critical density of organic homologous series

DEFF Research Database (Denmark)

Kontogeorgis, Georgios M.; Fredenslund, Aage; Tassios, Dimitrios P.

1995-01-01

Whether the critical density of organic compounds belonging to a certain homologous series increases or decreases with (increasing) molecular weight has been a challenging question over the years. Two sets of experimental data have recently appeared in the literature for the critical density of n......-alkanes: Steele's data (up to n-decane) suggest that critical density increases with carbon number and reaches a limiting value. On the other hand, the data of Teja et al., 1990 which cover a broader range of n-alkanes (up to n-octadecane), reveal a decreasing trend of the critical density after a maximum at n......-heptane. Teja et al. have also presented critical density measurements for 1-alkenes (up to 1-decene) and 1-alkanols (up to 1-undecanol). These data follow the same decreasing trend with the molecular weight as n-alkanes. This trend is not in agreement with the predictions of most group-contribution methods...

Self-organised criticality via retro-synaptic signals

Science.gov (United States)

Hernandez-Urbina, Victor; Herrmann, J. Michael

2016-12-01

The brain is a complex system par excellence. In the last decade the observation of neuronal avalanches in neocortical circuits suggested the presence of self-organised criticality in brain networks. The occurrence of this type of dynamics implies several benefits to neural computation. However, the mechanisms that give rise to critical behaviour in these systems, and how they interact with other neuronal processes such as synaptic plasticity are not fully understood. In this paper, we present a long-term plasticity rule based on retro-synaptic signals that allows the system to reach a critical state in which clusters of activity are distributed as a power-law, among other observables. Our synaptic plasticity rule coexists with other synaptic mechanisms such as spike-timing-dependent plasticity, which implies that the resulting synaptic modulation captures not only the temporal correlations between spiking times of pre- and post-synaptic units, which has been suggested as requirement for learning and memory in neural systems, but also drives the system to a state of optimal neural information processing.

Basic criticality relations for gas core design

International Nuclear Information System (INIS)

Tanner, J.E.

1992-01-01

Minimum critical fissile concentrations are calculated for U-233, U-235, Pu-239, and Am-242m mixed homogeneously with hydrogen at temperatures to 15,000K. Minimum critical masses of the same mixtures in a 1000 liter sphere are also calculated. It is shown that propellent efficiencies of a gas core fizzler engine using Am-242m as fuel would exceed those in a solid core engine as small as 1000L operating at 100 atmospheres pressure. The same would be true for Pu-239 and possibly U-233 at pressures of 1000 atm. or at larger volumes

Action plans can interact to hinder or facilitate reach performance.

Science.gov (United States)

Fournier, Lisa R; Wiediger, Matthew D; Taddese, Ezana F

2015-11-01

Executing a reach action can be delayed while retaining another action in working memory (WM) if the two action plans partly overlap rather than do not overlap. This delay (partial repetition cost) occurs when reach responses are under cognitive control. In this study, we investigated whether facilitation (a partial repetition benefit) occurs when reach responses are automatic. We also examined whether the hemisphere controlling the limb or selection of the preferred limb (based on a free-reach task) influences reach performance when the actions partly overlap. Left- and right-handers reached to different stimulus locations to the left and right of body midline with their ipsilateral hand while maintaining an action plan in WM that required the same or the different hand. The results showed a partial repetition benefit for spatially compatible reaches to left and right stimulus locations far from the body midline, but not for those near the body midline. Also, no partial repetition cost was found at any of the stimulus-reach locations. This indicates that automatic reach responses that partly overlap with an action plan maintained in WM are not delayed, but instead can be facilitated (partial repetition benefit). The roles of hemisphere and reach-hand preference in action control and the importance of the degree of feature overlap in obtaining a partial repetition benefit (and cost) are discussed.

Body girth as an alternative to body mass for establishing condition indexes in field studies: a validation in the king penguin.

Science.gov (United States)

Viblanc, Vincent A; Bize, Pierre; Criscuolo, François; Le Vaillant, Maryline; Saraux, Claire; Pardonnet, Sylvia; Gineste, Benoit; Kauffmann, Marion; Prud'homme, Onésime; Handrich, Yves; Massemin, Sylvie; Groscolas, René; Robin, Jean-Patrice

2012-01-01

Body mass and body condition are often tightly linked to animal health and fitness in the wild and thus are key measures for ecophysiologists and behavioral ecologists. In some animals, such as large seabird species, obtaining indexes of structural size is relatively easy, whereas measuring body mass under specific field circumstances may be more of a challenge. Here, we suggest an alternative, easily measurable, and reliable surrogate of body mass in field studies, that is, body girth. Using 234 free-living king penguins (Aptenodytes patagonicus) at various stages of molt and breeding, we measured body girth under the flippers, body mass, and bill and flipper length. We found that body girth was strongly and positively related to body mass in both molting (R(2) = 0.91) and breeding (R(2) = 0.73) birds, with the mean error around our predictions being 6.4%. Body girth appeared to be a reliable proxy measure of body mass because the relationship did not vary according to year and experimenter, bird sex, or stage within breeding groups. Body girth was, however, a weak proxy of body mass in birds at the end of molt, probably because most of those birds had reached a critical depletion of energy stores. Body condition indexes established from ordinary least squares regressions of either body girth or body mass on structural size were highly correlated (r(s) = 0.91), suggesting that body girth was as good as body mass in establishing body condition indexes in king penguins. Body girth may prove a useful proxy to body mass for estimating body condition in field investigations and could likely provide similar information in other penguins and large animals that may be complicated to weigh in the wild.

Criticality experiments with fast flux test facility fuel pins

International Nuclear Information System (INIS)

Bierman, S.R.

1990-11-01

A United States Department of Energy program was initiated during the early seventies at the Hanford Critical Mass Laboratory to obtain experimental criticality data in support of the Liquid Metal Fast Breeder Reactor Program. The criticality experiments program was to provide basic physics data for clean well defined conditions expected to be encountered in the handling of plutonium-uranium fuel mixtures outside reactors. One task of this criticality experiments program was concerned with obtaining data on PuO 2 -UO 2 fuel rods containing 20--30 wt % plutonium. To obtain this data a series of experiments were performed over a period of about twelve years. The experimental data obtained during this time are summarized and the associated experimental assemblies are described. 8 refs., 7 figs

Calculational study for criticality safety data of fissionable actinides

International Nuclear Information System (INIS)

Nojiri, Ichiro; Fukasaku, Yasuhiro.

1997-01-01

This study has been carried out to obtain basic criticality safety characteristics of minor actinides nuclides. Criticality safety data of minor actinides nuclides have been surveyed through public literatures. Critical mass of seven nuclides, Np-237, Am-241, Am-242m, Am-243, Cm-243, Cm-244 and Cm-245, have been calculated by using two code systems of criticality safety analysis, SCALE-4 and MCNP4A, under some material and reflector conditions. Some applicable cross-section libraries have been used for each code systems. Calculated data have been compared with each other and with published data. The results of this comparison shows that there is no discrepancy within the computational codes and the calculated data is strongly depend on the cross-section library. (author)

Criticality parameters for uranyl nitrate or plutonium nitrate systems in tributyl phosphate/kerosine and water

International Nuclear Information System (INIS)

Weber, W.

1985-01-01

This report presents the calculated values of smallest critical masses and volumina and neutron physical parameters for uranyl nitrate (3, 4, 5% U-235) or plutonium nitrate (5% Pu-240), each in a 30 per cent solution of tributyl phosphate (TBP)/kerosine. For the corresponding nitrate-water solutions, newly calculated results are presented together with a revised solution density model. A comparison of the data shows to what extent the criticality of nitrate-TBP/kerosine systems can be assessed on the basis of nitrate-water parameters, revealing that such data can be applied to uranyl nitrate/water systems, taking into account that the smallest critical mass of uranyl nitrate-TBP/kerosine systems, up to a 5 p.c. U-235 enrichment, is by 4.5 p.c. at the most smaller than that of UNH-water solutions. Plutonium nitrate (5% Pu-240) in the TBP/kerosine solution will have a smallest critical mass of up to 7 p.c. smaller, as compared with the water data. The suitability of the computing methods and cross-sections used is verified by recalculating experiments carried out to determine the lowest critical enrichment of uranyl nitrate. The calculated results are well in agreement with experimental data. The lowest critical enrichment is calculated to be 2.10 p.c. in the isotope U-235. (orig.) [de

Task-dependent vestibular feedback responses in reaching.

Science.gov (United States)

Keyser, Johannes; Medendorp, W Pieter; Selen, Luc P J

2017-07-01

When reaching for an earth-fixed object during self-rotation, the motor system should appropriately integrate vestibular signals and sensory predictions to compensate for the intervening motion and its induced inertial forces. While it is well established that this integration occurs rapidly, it is unknown whether vestibular feedback is specifically processed dependent on the behavioral goal. Here, we studied whether vestibular signals evoke fixed responses with the aim to preserve the hand trajectory in space or are processed more flexibly, correcting trajectories only in task-relevant spatial dimensions. We used galvanic vestibular stimulation to perturb reaching movements toward a narrow or a wide target. Results show that the same vestibular stimulation led to smaller trajectory corrections to the wide than the narrow target. We interpret this reduced compensation as a task-dependent modulation of vestibular feedback responses, tuned to minimally intervene with the task-irrelevant dimension of the reach. These task-dependent vestibular feedback corrections are in accordance with a central prediction of optimal feedback control theory and mirror the sophistication seen in feedback responses to mechanical and visual perturbations of the upper limb. NEW & NOTEWORTHY Correcting limb movements for external perturbations is a hallmark of flexible sensorimotor behavior. While visual and mechanical perturbations are corrected in a task-dependent manner, it is unclear whether a vestibular perturbation, naturally arising when the body moves, is selectively processed in reach control. We show, using galvanic vestibular stimulation, that reach corrections to vestibular perturbations are task dependent, consistent with a prediction of optimal feedback control theory. Copyright © 2017 the American Physiological Society.

A Dual Power Law Distribution for the Stellar Initial Mass Function

Science.gov (United States)

Hoffmann, Karl Heinz; Essex, Christopher; Basu, Shantanu; Prehl, Janett

2018-05-01

We introduce a new dual power law (DPL) probability distribution function for the mass distribution of stellar and substellar objects at birth, otherwise known as the initial mass function (IMF). The model contains both deterministic and stochastic elements, and provides a unified framework within which to view the formation of brown dwarfs and stars resulting from an accretion process that starts from extremely low mass seeds. It does not depend upon a top down scenario of collapsing (Jeans) masses or an initial lognormal or otherwise IMF-like distribution of seed masses. Like the modified lognormal power law (MLP) distribution, the DPL distribution has a power law at the high mass end, as a result of exponential growth of mass coupled with equally likely stopping of accretion at any time interval. Unlike the MLP, a power law decay also appears at the low mass end of the IMF. This feature is closely connected to the accretion stopping probability rising from an initially low value up to a high value. This might be associated with physical effects of ejections sometimes (i.e., rarely) stopping accretion at early times followed by outflow driven accretion stopping at later times, with the transition happening at a critical time (therefore mass). Comparing the DPL to empirical data, the critical mass is close to the substellar mass limit, suggesting that the onset of nuclear fusion plays an important role in the subsequent accretion history of a young stellar object.

Using Consumer Preference Information to Increase the Reach and Impact of Media-Based Parenting Interventions in a Public Health Approach to Parenting Support

Science.gov (United States)

Metzler, Carol W.; Sanders, Matthew R.; Rusby, Julie C.; Crowley, Ryann N.

2012-01-01

Within a public health approach to improving parenting, the mass media offer a potentially more efficient and affordable format for directly reaching a large number of parents with evidence-based parenting information than do traditional approaches to parenting interventions that require delivery by a practitioner. Little is known, however, about…

Guiding Warfare to Reach Sustainable Peace

DEFF Research Database (Denmark)

Vestenskov, David; Drewes, Line

The conference report Guiding Warfare to Reach Sustainable Peace constitutes the primary outcome of the conference It is based on excerpts from the conference presenters and workshop discussions. Furthermore, the report contains policy recommendations and key findings, with the ambition of develo......The conference report Guiding Warfare to Reach Sustainable Peace constitutes the primary outcome of the conference It is based on excerpts from the conference presenters and workshop discussions. Furthermore, the report contains policy recommendations and key findings, with the ambition...... of developing best practices in the education and implementation of IHL in capacity building of security forces....

The different baryonic Tully-Fisher relations at low masses.

Science.gov (United States)

Brook, Chris B; Santos-Santos, Isabel; Stinson, Greg

2016-06-11

We compare the Baryonic Tully-Fisher relation (BTFR) of simulations and observations of galaxies ranging from dwarfs to spirals, using various measures of rotational velocity V rot . We explore the BTFR when measuring V rot at the flat part of the rotation curve, V flat , at the extent of H i gas, V last , and using 20 per cent ( W 20 ) and 50 per cent ( W 50 ) of the width of H i line profiles. We also compare with the maximum circular velocity of the parent halo, [Formula: see text], within dark matter only simulations. The different BTFRs increasingly diverge as galaxy mass decreases. Using V last  one obtains a power law over four orders of magnitude in baryonic mass, with slope similar to the observed BTFR. Measuring V flat gives similar results as V last when galaxies with rising rotation curves are excluded. However, higher rotation velocities would be found for low-mass galaxies if the cold gas extended far enough for V rot to reach a maximum. W 20 gives a similar slope as V last but with slightly lower values of V rot for low-mass galaxies, although this may depend on the extent of the gas in your galaxy sample. W 50 bends away from these other relations towards low velocities at low masses. By contrast, [Formula: see text] bends towards high velocities for low-mass galaxies, as cold gas does not extend out to the radius at which haloes reach [Formula: see text]. Our study highlights the need for careful comparisons between observations and models: one needs to be consistent about the particular method of measuring V rot , and precise about the radius at which velocities are measured.

Assessment of critical flow models of RELAP5-MOD2 and CATHARE codes

International Nuclear Information System (INIS)

Hao Laomi; Zhu Zhanchuan

1992-01-01

The critical flow tests for the long and short nozzles conducted on the SUPER MOBY-DICK facility were analyzed using the RELAP5-MOD2 and CATHARE 1.3 codes to assess the critical flow models of two codes. The critical mass flux calculated for two nozzles are given. The CATHARE code has used the thermodynamic nonequilibrium sound velocity of the two-phase fluid as the critical flow criterion, and has the better interphase transfer models and calculates the critical flow velocities with the completely implicit solution. Therefore, it can well calculate the critical flowrate and can describe the effect of the geometry L/D on the critical flowrate

Radiative corrections to the masses of supersymmetric Higgs bosons

International Nuclear Information System (INIS)

Ellis, J.; Zwirner, F.

1991-01-01

The lightest neutral Higgs boson in the minimal supersymmetric extension of the standard model has a tree-level mass less than that of the Z 0 . We calculate radiative corrections to its mass and to that of the heavier CP-even neutral Higgs boson. We find large corrections that increase with the top quark and squark masses, and vary with the ratio of vacuum expectation values v 2 /v 1 . These radiative corrections can be as large as O(100) GeV, and have the effect of (i) invalidating lower bounds on v 2 /v 1 inferred from unsuccessful Higgs searches at LEP I, (ii) in many cases, increasing the mass of the lighter CP-even Higgs boson beyond m z , (iii) often, increasing the mass of the heavier CP-even Higgs boson beyond the LEP reach, into a range more accessible to the LHC or SSC. (orig.)

Nanomaterials under REACH. Nanosilver as a case study

NARCIS (Netherlands)

Pronk MEJ; Wijnhoven SWP; Bleeker EAJ; Heugens EHW; Peijnenburg WJGM; Luttik R; Hakkert BC; SEC; SIR; LER

2009-01-01

Om de risico's van nanomaterialen te kunnen inschatten en beheersen, zijn enkele aanpassingen nodig in de Europese chemicalienwetgeving REACH. De gegevens over stoffen waar REACH standaard om vraagt, zijn namelijk onvoldoende om de specifieke eigenschappen van nanomaterialen te bepalen. Hetzelfde

Critical experiments on single-unit spherical plutonium geometries reflected and moderated by oil

International Nuclear Information System (INIS)

Rothe, R.E.

1997-05-01

Experimental critical configurations are reported for several dozen spherical and hemispherical single-unit assemblies of plutonium metal. Most were solid but many were hollow-centered, thick, shell-like geometries. All were constructed of nested plutonium (mostly 2139 Pu) metal hemispherical shells. Three kinds of critical configurations are reported. Two required interpolation and/or extrapolation of data to obtain the critical mass because reflector conditions were essentially infinite. The first finds the plutonium essentially fully reflected by a hydrogen-rich oil; the second is essentially unreflected. The third kind reports the critical oil reflector height above a large plutonium metal assembly of accurately known mass (no interpolation required) when that mass was too great to permit full oil reflection. Some configurations had thicknesses of mild steel just outside the plutonium metal, separating it from the oil. These experiments were performed at the Rocky Flats Critical Mass Laboratory in the late 1960s. They have not been published in a form suitable for benchmark-quality comparisons against state-of-the-art computational techniques until this paper. The age of the data and other factors lead to some difficulty in reconstructing aspects of the program and may, in turn, decrease confidence in certain details. Whenever this is true, the point is acknowledged. The plutonium metal was alpha-phase 239 Pu containing 5.9 wt-% 240 Pu. All assemblies were formed by nesting 1.667-mm-thick (nominal) bare plutonium metal hemispherical shells, also called hemishells, until the desired configuration was achieved. Very small tolerance gaps machined into radial dimensions reduced the effective density a small amount in all cases. Steel components were also nested hemispherical shells; but these were nominally 3.333-mm thick. Oil was used as the reflector because of its chemical compatibility with plutonium metal

On Mass, Spacetime Curvature, and Gravity

Science.gov (United States)

Janis, Allen I.

2018-01-01

The frequently used analogy of a massive ball distorting an elastic sheet, which is used to illustrate why mass causes spacetime curvature and gravitational attraction, is criticized in this article. A different analogy that draws on the students' previous knowledge of spacetime diagrams in special relativity is suggested.

Lack of Critical Slowing Down Suggests that Financial Meltdowns Are Not Critical Transitions, yet Rising Variability Could Signal Systemic Risk

Science.gov (United States)

Hoarau, Quentin

2016-01-01

Complex systems inspired analysis suggests a hypothesis that financial meltdowns are abrupt critical transitions that occur when the system reaches a tipping point. Theoretical and empirical studies on climatic and ecological dynamical systems have shown that approach to tipping points is preceded by a generic phenomenon called critical slowing down, i.e. an increasingly slow response of the system to perturbations. Therefore, it has been suggested that critical slowing down may be used as an early warning signal of imminent critical transitions. Whether financial markets exhibit critical slowing down prior to meltdowns remains unclear. Here, our analysis reveals that three major US (Dow Jones Index, S&P 500 and NASDAQ) and two European markets (DAX and FTSE) did not exhibit critical slowing down prior to major financial crashes over the last century. However, all markets showed strong trends of rising variability, quantified by time series variance and spectral function at low frequencies, prior to crashes. These results suggest that financial crashes are not critical transitions that occur in the vicinity of a tipping point. Using a simple model, we argue that financial crashes are likely to be stochastic transitions which can occur even when the system is far away from the tipping point. Specifically, we show that a gradually increasing strength of stochastic perturbations may have caused to abrupt transitions in the financial markets. Broadly, our results highlight the importance of stochastically driven abrupt transitions in real world scenarios. Our study offers rising variability as a precursor of financial meltdowns albeit with a limitation that they may signal false alarms. PMID:26761792

Towards a Discourse for Criticism in Language Teaching: Analysis of Sociocultural Representations in Mass Media (Hacia un discurso para la crítica en la enseñanza de la lengua: análisis de representaciones socioculturales en medios de comunicación)

Science.gov (United States)

Vargas Torres, Margarita Rosa

2010-01-01

This article states that in order to exercise citizenship with responsibility, language teachers need to popularize a discourse for criticism in which students and teachers transcend tacit knowledge and common sense due to meta-cognition and argumentation and reach systematic knowledge and procedures posed by experts in the different disciplines.…

Cosmology and the neutrino mass ordering

DEFF Research Database (Denmark)

Hannestad, Steen; Schwetz, Thomas

2016-01-01

We propose a simple method to quantify a possible exclusion of the inverted neutrino mass ordering from cosmological bounds on the sum of the neutrino masses. The method is based on Bayesian inference and allows for a calculation of the posterior odds of normal versus inverted ordering. We apply...... the method for a specific set of current data from Planck CMB data and large-scale structure surveys, providing an upper bound on the sum of neutrino masses of 0.14 eV at 95% CL. With this analysis we obtain posterior odds for normal versus inverted ordering of about 2:1. If cosmological data is combined...... with data from oscillation experiments the odds reduce to about 3:2. For an exclusion of the inverted ordering from cosmology at more than 95% CL, an accuracy of better than 0.02 eV is needed for the sum. We demonstrate that such a value could be reached with planned observations of large scale structure...

Analysis of Nitro-aromatic and Nitramine Explosives by Atmospheric Pressure Chemical Ionization / High Performance Liquid Chromatography / Mass Spectrometry / Mass Spectrometry

International Nuclear Information System (INIS)

Hicks, B.J.; Han, W.; Robben, J.R.

2009-01-01

This procedure is capable of separating and quantifying twenty-nine high explosives and internal surrogates with a single injection. After the initial preparation step, the sample is introduced to the high performance liquid chromatograph for target separation, ionized by atmospheric pressure chemical ionization and the explosives of interest are isolated / quantified by mass spectrometry / mass spectrometry. Concentrations of the target explosives are measured relative to the response of both internal and external standard concentrations. A C-18 reverse phase high performance liquid chromatograph column is used for separation. Ionization is performed using both positive and negative atmospheric pressure chemical ionization resulting in a molecular ion with little fragmentation. These ions are isolated at the first quadrupole of the mass spectrometer, dissociated by collision with argon in the collision cell and the resulting daughter ions are isolated at the second quadrupole. These daughter ions then reach the detector where they are quantified. To date this procedure represents the most thorough high performance liquid chromatography / mass spectrometry / mass spectrometry explosives analysis available in the environmental chemistry market. (authors)

Factors influencing drug uptake during mass drug administration for control of lymphatic filariasis in rural and urban Tanzania

DEFF Research Database (Denmark)

Kisoka, William J.; Simonsen, Paul Erik; Malecela, Mwelecele N.

2014-01-01

BACKGROUND: In most countries of Sub-Saharan Africa, control of lymphatic filariasis (LF) is based on annual mass drug administration (MDA) with a combination of ivermectin and albendazole. Treatment coverages are however often suboptimal for programmes to reach the goal of transmission interrupt......BACKGROUND: In most countries of Sub-Saharan Africa, control of lymphatic filariasis (LF) is based on annual mass drug administration (MDA) with a combination of ivermectin and albendazole. Treatment coverages are however often suboptimal for programmes to reach the goal of transmission...

Critical success factors simplified implementing the powerful drivers of dramatic business improvement

CERN Document Server

Howell, Marvin T

2010-01-01

Critical-to-success factors (CSFs) have become essential elements to strategic planning and no business can achieve consistent success without effectively adopting them. To take full advantage of CSFs, however, an organization must first understand what they are and how they can be used to drive organizational initiatives and processes. Critical Success Factors Simplified: Implementing the Powerful Drivers of Dramatic Business Improvement provides a concise manual on CSFs that will teach you how to identify and select the right CSFs, measure their impact, and adjust them as needed to reach your goals.

[Residues and potential ecological risk assessment of metal in sediments from lower reaches and estuary of Pearl River].

Science.gov (United States)

Xie, Wen-Ping; Wang, Shao-Bing; Zhu, Xin-Ping; Chen, Kun-Ci; Pan, De-Bo; Hong, Xiao-You; Yin, Yi

2012-06-01

In order to investigate the heavy metal concentrations and their potential ecological risks in surface sediments of lower reaches and estuary of Pearl River, 21 bottom sediment samples were collected from lower reaches and estuary of Pearl River. Total contents of Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Sb, Pb and Hg in these samples were measured by the inductively coupled plasma mass spectrometry (ICP-MS) and the atomic fluorescence spectrometry (AFS) and using the index of geoaccumulation and the potential ecological risk index to evaluate the pollution degree of heavy metals in the sediments. Results indicated that the concentration of total Fe and total Mn were 41658.73 and 1104.73 mg x kg(-1) respectively and toxic trace metals, such as Cr, Co, Ni, Cu, Zn, As, Se, Cd, Sb, Pb and Hg were 86.62, 18.18, 54.10, 80.20, 543.60, 119.55, 4.28, 10.60, 20.26, 104.58 and 0.520 mg x kg(-1). The descending order of pollution degree of various metals is: Cd > As approximately Zn > Hg > Pb approximately Cu approximately Cr, while the single potential ecological risk followed the order: Cd > Hg > As > Cu > Pb > Zn > Cr. The pollution extent and potential ecological risk of Cd were the most serious among all heavy metals. The distribution pattern of Cd individual potential ecological risk indices is exactly the same as that of general potential ecological risk indices for all heavy metals. Clustering analysis indicates that the sampling stations may be classified into five groups which basically reflected the characteristics of the heavy metal contamination and sedimentation environments along the different river reaches in lower reaches and estuary of Pearl Rive. In general, the serious heavy metal pollution and the high potential ecological risk existed in three river reaches: Chengcun-Shawan, Chengcun-Shundegang and Waihai-Hutiaomen. The pollution degree and potential ecological risk are higher in related river reaches of Beijiang than that in other lower reaches and

Mass Communication as a Perspective on Human Communication: The Quandary of a Discipline.

Science.gov (United States)

Trapp, Mary E.; McLuskie, Ed

The empirical and critical traditions in mass communication inquiry are examined in this paper to determine if mass communication inquiry can provide a useful perspective on human communication. The paper first describes the development of interest in mass communication in the nineteenth century, then explains the empirical research tradition in…

The neutron star mass distribution

Energy Technology Data Exchange (ETDEWEB)

Kiziltan, Bülent [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kottas, Athanasios; De Yoreo, Maria [Department of Applied Mathematics and Statistics, University of California, Santa Cruz, CA 95064 (United States); Thorsett, Stephen E., E-mail: bkiziltan@cfa.harvard.edu [Department of Astronomy and Astrophysics, University of California and UCO/Lick Observatory, Santa Cruz, CA 95064 (United States)

2013-11-20

In recent years, the number of pulsars with secure mass measurements has increased to a level that allows us to probe the underlying neutron star (NS) mass distribution in detail. We critically review the radio pulsar mass measurements. For the first time, we are able to analyze a sizable population of NSs with a flexible modeling approach that can effectively accommodate a skewed underlying distribution and asymmetric measurement errors. We find that NSs that have evolved through different evolutionary paths reflect distinctive signatures through dissimilar distribution peak and mass cutoff values. NSs in double NS and NS-white dwarf (WD) systems show consistent respective peaks at 1.33 M {sub ☉} and 1.55 M {sub ☉}, suggesting significant mass accretion (Δm ≈ 0.22 M {sub ☉}) has occurred during the spin-up phase. The width of the mass distribution implied by double NS systems is indicative of a tight initial mass function while the inferred mass range is significantly wider for NSs that have gone through recycling. We find a mass cutoff at ∼2.1 M {sub ☉} for NSs with WD companions, which establishes a firm lower bound for the maximum NS mass. This rules out the majority of strange quark and soft equation of state models as viable configurations for NS matter. The lack of truncation close to the maximum mass cutoff along with the skewed nature of the inferred mass distribution both enforce the suggestion that the 2.1 M {sub ☉} limit is set by evolutionary constraints rather than nuclear physics or general relativity, and the existence of rare supermassive NSs is possible.

Reaching the hard to reach.

Science.gov (United States)

Bhiwandi, P; Campbell, M; Potts, M

1994-01-01

The 1994 International Conference on Population and Development proposed increasing contraceptive couple protection from 550 million in 1995 to 880 million in 2015. The task for family planning (FP) programs is to provide access to services for, sometimes, inaccessible rural populations. FP need based on desire for no more children has ranged from under 20% in Senegal to almost 80% in Peru. Socioeconomic development was found not to be a prerequisite for fertility change. Gender inequalities in education and social autonomy must be changed. FP access is very important among women with a disadvantaged background or among women unsure about FP. Bangladesh is a good example of a country with increased contraceptive prevalence despite low income. The rule of thumb is that contraception increases of 15% contribute to a drop in family size of about one child. Program effectiveness is related to a variety of factors: contraceptive availability at many locations, acceptable price of contraception, delivery of the oral contraceptives without prescriptions, and other strategies. FP is a service not a medical treatment. A range of methods must be promoted and available from a range of facilities. Contraceptive use is dependent on the woman's stage in her lifecycle and is dependent on informed choice. Community-based distribution systems are effective, whereas free distribution by poorly-trained field workers is not always very effective because patient payment of all or part of the cost assures quality and freedom of choice. Effective programs for underprivileged groups involve aggressive, easy to manage programs that can be replicated rapidly. FP serves a useful function in depressing maternal mortality among the poor in Africa, who have no access to quality health services. Social marketing is an effective strategy for reaching remote areas. Political will and robust management are necessary commodities.

Criticality of mixtures of plutonium and high enriched uranium

International Nuclear Information System (INIS)

Grolleau, E.; Lein, M.; Leka, G.; Maidou, B.; Klenov, P.

2003-01-01

This paper presents a criticality evaluation of moderated homogeneous plutonium-uranium mixtures. The fissile media studied are homogeneous mixtures of plutonium and high enriched uranium in two chemical forms: aqueous mixtures of metal and mixtures of nitrate solutions. The enrichment of uranium considered are 93.2wt.% 235 U and 100wt.% 235 U. The 240 Pu content in plutonium varies from 0wt.% 240 Pu to 12wt.% 240 Pu. The critical parameters (radii and masses of a 20 cm water reflected sphere) are calculated with the French criticality safety package CRISTAL V0. The comparison of the calculated critical parameters as a function of the moderator-to-fuel atomic ratio shows significant ranges in which high enriched uranium systems, as well as plutonium-uranium mixtures, are more reactive than plutonium systems. (author)

Calling behavior of mass-reared and wild Anastrepha serpentina (Diptera: Tephritidae).

Science.gov (United States)

Castrejón-Gómez, Victor R; Lascares, Shaila; Malo, Edi A; Toledo, Jorge; Rojas, Julio C

2007-08-01

The calling behavior of mass-reared and wild males of Anastrepha serpentina (Wiedemann) (Diptera: Tephritidae) was studied both in the laboratory and in field cage tests. In the laboratory, density (1, 5, and 10 males per container), age, and hour of day significantly affected calling behavior. Mass-reared males called independently of density, whereas wild males only called at densities of 5 and 10 individuals. Males of both strains started calling when they were 5-7 d old. The daily pattern of male calling was similar in both strains, starting at 0730 hours, and reaching a peak at 1330-1630 hours. Field cage tests showed that mass-reared males started calling when they were 5d old; the period of peak calling was when males were 8-9 d old. In contrast, wild males began calling when they were 10 d old, reaching peaks when males were 13, 15, and 18 d old. Wild males tended to form leks to call during each day of the experiment, whereas mass-reared males only formed leks during 2 d, both strains displaying very low levels. During field cage tests, males, independently of strain, displayed two calling peaks, one peak in the morning and one peak in the afternoon, whereas males observed in the laboratory only showed a single calling peak. The results are discussed in view of the effects of mass rearing A. serpentina males in relation to potential use of the sterile insect technique.

Sensorimotor Reorganizations of Arm Kinematics and Postural Strategy for Functional Whole-Body Reaching Movements in Microgravity

Directory of Open Access Journals (Sweden)

Thomas Macaluso

2017-10-01

Full Text Available Understanding the impact of weightlessness on human behavior during the forthcoming long-term space missions is of critical importance, especially when considering the efficiency of goal-directed movements in these unusual environments. Several studies provided a large set of evidence that gravity is taken into account during the planning stage of arm reaching movements to optimally anticipate its consequence upon the moving limbs. However, less is known about sensorimotor changes required to face weightless environments when individuals have to perform fast and accurate goal-directed actions with whole-body displacement. We thus aimed at characterizing kinematic features of whole-body reaching movements in microgravity, involving high spatiotemporal constraints of execution, to question whether and how humans are able to maintain the performance of a functional behavior in the standards of normogravity execution. Seven participants were asked to reach as fast and as accurately as possible visual targets while standing during microgravity episodes in parabolic flight. Small and large targets were presented either close or far from the participants (requiring, in the latter case, additional whole-body displacement. Results reported that participants successfully performed the reaching task with general temporal features of movement (e.g., movement speed close to land observations. However, our analyses also demonstrated substantial kinematic changes related to the temporal structure of focal movement and the postural strategy to successfully perform -constrained- whole-body reaching movements in microgravity. These immediate reorganizations are likely achieved by rapidly taking into account the absence of gravity in motor preparation and execution (presumably from cues about body limbs unweighting. Specifically, when compared to normogravity, the arm deceleration phase substantially increased. Furthermore, greater whole-body forward displacements

The X-ray signature of solar coronal mass

Science.gov (United States)

Harrison, R. A.; Waggett, P. W.; Bentley, R. D.; Phillips, K. J. H.; Bruner, M.

1985-01-01

The coronal response to six solar X-ray flares has been investigated. At a time coincident with the projected onset of the white-light coronal mass ejection associated with each flare, there is a small, discrete soft X-ray enhancement. These enhancements (precursors) precede by typically about 20 m the impulsive phase of the solar flare which is dominant by the time the coronal mass ejection has reached an altitude above 0.5 solar radii. Motions of hot X-ray emitting plasma, during the precursors, which may well be a signature of the mass ejection onsets, are identified. Further investigations have also revealed a second class of X-ray coronal transient, during the main phase of the flare. These appear to be associated with magnetic reconnection above post-flare loop systems.

Two-phase flow model with nonequilibrium and critical flow

International Nuclear Information System (INIS)

Sureau, H.; Houdayer, G.

1976-01-01

The model proposed includes the three conservation equations (mass, momentum, energy) applied to the two phase flows and a fourth partial derivative equation which takes into account the nonequilibriums and describes the mass transfer process. With this model, the two phase critical flow tests performed on the Moby-Dick loop (CENG) with several geometries, are interpreted by a unique law. Extrapolations to industrial dimension problems show that geometry and size effects are different from those obtained with earlier models (Zaloudek, Moody, Fauske) [fr

Cerebellar inactivation impairs memory of learned prism gaze-reach calibrations.

Science.gov (United States)

Norris, Scott A; Hathaway, Emily N; Taylor, Jordan A; Thach, W Thomas

2011-05-01

Three monkeys performed a visually guided reach-touch task with and without laterally displacing prisms. The prisms offset the normally aligned gaze/reach and subsequent touch. Naive monkeys showed adaptation, such that on repeated prism trials the gaze-reach angle widened and touches hit nearer the target. On the first subsequent no-prism trial the monkeys exhibited an aftereffect, such that the widened gaze-reach angle persisted and touches missed the target in the direction opposite that of initial prism-induced error. After 20-30 days of training, monkeys showed long-term learning and storage of the prism gaze-reach calibration: they switched between prism and no-prism and touched the target on the first trials without adaptation or aftereffect. Injections of lidocaine into posterolateral cerebellar cortex or muscimol or lidocaine into dentate nucleus temporarily inactivated these structures. Immediately after injections into cortex or dentate, reaches were displaced in the direction of prism-displaced gaze, but no-prism reaches were relatively unimpaired. There was little or no adaptation on the day of injection. On days after injection, there was no adaptation and both prism and no-prism reaches were horizontally, and often vertically, displaced. A single permanent lesion (kainic acid) in the lateral dentate nucleus of one monkey immediately impaired only the learned prism gaze-reach calibration and in subsequent days disrupted both learning and performance. This effect persisted for the 18 days of observation, with little or no adaptation.

Effect of warming rate on the critical thermal maxima of crabs, shrimp and fish

OpenAIRE

Vinagre, Catarina; Leal, Inês; Mendonça, Vanessa; Flores, Augusto Alberto Valero

2015-01-01

he threat of global warming has prompted numerous recent studies on the thermal tolerance of marine species. A widely used method to determine the upper thermal limit has been the Critical Thermal Maximum (CTMax), a dynamic method, meaning that temperature is increased gradually until a critical point is reached. This method presents several advantages over static methods, however, there is one main issue that hinders interpretation and comparison of CTMax results: the rate at which the tempe...

Prediction of Mass Flow Rate in Supersonic Natural Gas Processing

Directory of Open Access Journals (Sweden)

Wen Chuang

2015-11-01

Full Text Available The mass flow rate of natural gas through the supersonic separator was numerically calculated by various cubic equations of state. The numerical results show that the compressibility factor and specific heat ratio for ideal gas law diverge remarkably from real gas models at a high inlet pressure. Simultaneously, the deviation of mass flow calculated by the ideal and real gas models reaches over 10 %. The difference increases with the lower of the inlet temperature regardless of the inlet pressure. A higher back pressure results in an earlier location of the shock wave. The pressure ratio of 0.72 is the first threshold to get the separator work normally. The second threshold is 0.95, in which case the whole flow is subsonic and cannot reach the choked state. The shock position moves upstream with the real gas model compared to the ideal gas law in the cyclonic separation section.

Decoding natural reach-and-grasp actions from human EEG

Science.gov (United States)

Schwarz, Andreas; Ofner, Patrick; Pereira, Joana; Ioana Sburlea, Andreea; Müller-Putz, Gernot R.

2018-02-01

Objective. Despite the high number of degrees of freedom of the human hand, most actions of daily life can be executed incorporating only palmar, pincer and lateral grasp. In this study we attempt to discriminate these three different executed reach-and-grasp actions utilizing their EEG neural correlates. Approach. In a cue-guided experiment, 15 healthy individuals were asked to perform these actions using daily life objects. We recorded 72 trials for each reach-and-grasp condition and from a no-movement condition. Main results. Using low-frequency time domain features from 0.3 to 3 Hz, we achieved binary classification accuracies of 72.4%, STD  ±  5.8% between grasp types, for grasps versus no-movement condition peak performances of 93.5%, STD  ±  4.6% could be reached. In an offline multiclass classification scenario which incorporated not only all reach-and-grasp actions but also the no-movement condition, the highest performance could be reached using a window of 1000 ms for feature extraction. Classification performance peaked at 65.9%, STD  ±  8.1%. Underlying neural correlates of the reach-and-grasp actions, investigated over the primary motor cortex, showed significant differences starting from approximately 800 ms to 1200 ms after the movement onset which is also the same time frame where classification performance reached its maximum. Significance. We could show that it is possible to discriminate three executed reach-and-grasp actions prominent in people’s everyday use from non-invasive EEG. Underlying neural correlates showed significant differences between all tested conditions. These findings will eventually contribute to our attempt of controlling a neuroprosthesis in a natural and intuitive way, which could ultimately benefit motor impaired end users in their daily life actions.

The mass-hierarchy and CP-violation discovery reach of the LBNO long-baseline neutrino experiment

CERN Document Server

Agarwalla, S.K.; Aittola, M.; Alekou, A.; Andrieu, B.; Angus, D.; Antoniou, F.; Ariga, A.; Ariga, T.; Asfandiyarov, R.; Autiero, D.; Ballett, P.; Bandac, I.; Banerjee, D.; Barker, G.J.; Barr, G.; Bartmann, W.; Bay, F.; Berardi, V.; Bertram, I.; Bésida, O.; Blebea-Apostu, A.M.; Blondel, A.; Bogomilov, M.; Borriello, E.; Boyd, S.; Brancus, I.; Bravar, A.; Buizza-Avanzini, M.; Cafagna, F.; Calin, M.; Calviani, M.; Campanelli, M.; Cantini, C.; Caretta, O.; Cata-Danil, G.; Catanesi, M.G.; Cervera, A.; Chakraborty, S.; Chaussard, L.; Chesneanu, D.; Chipesiu, F.; Christodoulou, G.; Coleman, J.; Crivelli, P.; Davenne, T.; Dawson, J.; De Bonis, I.; De Jong, J.; Déclais, Y.; del Amo Sanchez, P.; Delbart, A.; Densham, C.; Di Lodovico, F.; Di Luise, S.; Duchesneau, D.; Dumarchez, J.; Efthymiopoulos, I.; Eliseev, A.; Emery, S.; Enqvist, K.; Enqvist, T.; Epprecht, L.; Ereditato, A.; Erykalov, A.N.; Esanu, T.; Finch, A.J.; Fitton, M.D.; Franco, D.; Galymov, V.; Gavrilov, G.; Gendotti, A.; Giganti, C.; Goddard, B.; Gomez, J.J.; Gomoiu, C.M.; Gornushkin, Y.A.; Gorodetzky, P.; Grant, N.; Haesler, A.; Haigh, M.D.; Hasegawa, T.; Haug, S.; Hierholzer, M.; Hissa, J.; Horikawa, S.; Huitu, K.; Ilic, J.; Ioannisian, A.N.; Izmaylov, A.; Jipa, A.; Kainulainen, K.; Kalliokoski, T.; Karadzhov, Y.; Kawada, J.; Khabibullin, M.; Khotjantsev, A.; Kokko, E.; Kopylov, A.N.; Kormos, L.L.; Korzenev, A.; Kosyanenko, S.; Kreslo, I.; Kryn, D.; Kudryavtsev, V.A.; Kudenko, Y.; Kumpulainen, J.; Kuusiniemi, P.; Lagoda, J.; Lazanu, I.; Levy, J. -M.; Litchfield, R.P.; Loo, K.; Loveridge, P.; Maalampi, J.; Magaletti, L.; Margineanu, R.M.; Marteau, J.; Martin-Mari, C.; Matveev, V.; Mavrokoridis, K.; Mazzucato, E.; McCauley, N.; Mercadante, A.; Mineev, O.; Mirizzi, A.; Mitrica, B.; Morgan, B.; Murdoch, M.; Murphy, S.; Narita, S.; Nesterenko, D.A.; Nguyen, K.; Nikolics, K.; Noah, E.; Novikov, Yu.; O'Keeffe, H.; Odell, J.; Oprima, A.; Palladino, V.; Pascoli, S.; Patzak, T.; Payne, D.; Pectu, M.; Pennacchio, E.; Papaphilippou, Y.; Periale, L.; Pessard, H.; Pistillo, C.; Popov, B.; Przewlocki, P.; Quinto, M.; Radicioni, E.; Ramachers, Y.; Ratoff, P.N.; Ravonel, M.; Rayner, M.; Resnati, F.; Ristea, O.; Robert, A.; Rondio, E.; Rubbia, A.; Rummukainen, K.; Sacco, R.; Saftoiu, A.; Sakashita, K.; Sarkamo, J.; Sato, F.; Saviano, N.; Scantamburlo, E.; Sergiampietri, F.; Sgalaberna, D.; Shaposhnikova, E.; Slupecki, M.; Sorel, M.; Spooner, N.J.C.; Stahl, A.; Stanca, D.; Steerenberg, R.; Sterian, A.R.; Sterian, P.; Still, B.; Stoica, S.; Strauss, T.; Suhonen, J.; Suvorov, V.; Szeptycka, M.; Terri, R.; Thompson, L.F.; Toma, G.; Tonazzo, A.; Touramanis, C.; Trzaska, W.H.; Tsenov, R.; Tuominen, K.; Vacheret, A.; Valram, M.; Vankova-Kirilova, G.; Vanucci, F.; Vasseur, G.; Velotti, F.; Velten, P.; Viant, T.; Vincke, H.; Virtanen, A.; Vorobyev, A.; Wark, D.; Weber, A.; Weber, M.; Wiebusch, C.; Wilson, J.R.; Wu, S.; Yershov, N.; Zalipska, J.; Zito, M.

2014-01-01

The next generation neutrino observatory proposed by the LBNO collaboration will address fundamental questions in particle and astroparticle physics. The experiment consists of a far detector, in its first stage a 20 kt LAr double phase TPC and a magnetised iron calorimeter, situated at 2300 km from CERN and a near detector based on a high-pressure argon gas TPC. The long baseline provides a unique opportunity to study neutrino flavour oscillations over their 1st and 2nd oscillation maxima exploring the $L/E$ behaviour, and distinguishing effects arising from $\\delta_{CP}$ and matter. In this paper we have reevaluated the physics potential of this setup for determining the mass hierarchy (MH) and discovering CP-violation (CPV), using a conventional neutrino beam from the CERN SPS with a power of 750 kW. We use conservative assumptions on the knowledge of oscillation parameter priors and systematic uncertainties. The impact of each systematic error and the precision of oscillation prior is shown. We demonstrat...

Review of the CRAC and SILENE Criticality Accident Studies

International Nuclear Information System (INIS)

Barbry, F.; Fouillaud, P.; Grivot, P.; Reverdy, L.

2009-01-01

In 1967, the Commissariat et l'Energie Atomique (French Atomic Energy Agency) performed its first research on criticality accidents for the purpose of limiting their impact on people, the environment, and nuclear facilities themselves. A criticality accident is accompanied by intense neutron and gamma emissions and release of radioactive fission products-gases and aerosols-gene rating risk of irradiation and contamination. This work has supplemented earlier work in criticality safety, which concentrated on critical mass measurements and computations. Understanding of the consequences of criticality accidents was limited. Emergency planning was hampered by lack of data. Information became available from pulsed reactor experiments, but the experiments were restricted to the established reactor configurations. The objectives of research performed at the Valduc criticality laboratory, mainly on aqueous fissile media, using the CRAC and SILENE facilities, by multidisciplinary teams of physicists, dosimetry specialists, and radio-biologists, were to model criticality accident physics, estimate irradiation risks and radioactive releases, detect excursions, and organize emergency response. The results of the Valduc experiments have contributed toward improved understanding of criticality accident phenomenology and better evaluation of the risks associated with such accidents. (authors)

Review of the CRAC and SILENE Criticality Accident Studies

Energy Technology Data Exchange (ETDEWEB)

Barbry, F.; Fouillaud, P.; Grivot, P.; Reverdy, L. [CEA Valduc, Serv Rech Neutron and Critcite, 21 - Is-sur-Tille (France)

2009-02-15

In 1967, the Commissariat et l'Energie Atomique (French Atomic Energy Agency) performed its first research on criticality accidents for the purpose of limiting their impact on people, the environment, and nuclear facilities themselves. A criticality accident is accompanied by intense neutron and gamma emissions and release of radioactive fission products-gases and aerosols-gene rating risk of irradiation and contamination. This work has supplemented earlier work in criticality safety, which concentrated on critical mass measurements and computations. Understanding of the consequences of criticality accidents was limited. Emergency planning was hampered by lack of data. Information became available from pulsed reactor experiments, but the experiments were restricted to the established reactor configurations. The objectives of research performed at the Valduc criticality laboratory, mainly on aqueous fissile media, using the CRAC and SILENE facilities, by multidisciplinary teams of physicists, dosimetry specialists, and radio-biologists, were to model criticality accident physics, estimate irradiation risks and radioactive releases, detect excursions, and organize emergency response. The results of the Valduc experiments have contributed toward improved understanding of criticality accident phenomenology and better evaluation of the risks associated with such accidents. (authors)

Applying attachment theory to effective practice with hard-to-reach youth: the AMBIT approach.

Science.gov (United States)

Bevington, Dickon; Fuggle, Peter; Fonagy, Peter

2015-01-01

Adolescent Mentalization-Based Integrative Treatment (AMBIT) is a developing approach to working with "hard-to-reach" youth burdened with multiple co-occurring morbidities. This article reviews the core features of AMBIT, exploring applications of attachment theory to understand what makes young people "hard to reach," and provide routes toward increased security in their attachment to a worker. Using the theory of the pedagogical stance and epistemic ("pertaining to knowledge") trust, we show how it is the therapeutic worker's accurate mentalizing of the adolescent that creates conditions for new learning, including the establishment of alternative (more secure) internal working models of helping relationships. This justifies an individual keyworker model focused on maintaining a mentalizing stance toward the adolescent, but simultaneously emphasizing the critical need for such keyworkers to remain well connected to their wider team, avoiding activation of their own attachment behaviors. We consider the role of AMBIT in developing a shared team culture (shared experiences, shared language, shared meanings), toward creating systemic contexts supportive of such relationships. We describe how team training may enhance the team's ability to serve as a secure base for keyworkers, and describe an innovative approach to treatment manualization, using a wiki format as one way of supporting this process.

Development of likelihood estimation method for criticality accidents of mixed oxide fuel fabrication facilities

International Nuclear Information System (INIS)

Tamaki, Hitoshi; Yoshida, Kazuo; Kimoto, Tatsuya; Hamaguchi, Yoshikane

2010-01-01

A criticality accident in a MOX fuel fabrication facility may occur depending on several parameters, such as mass inventory and plutonium enrichment. MOX handling units in the facility are designed and operated based on the double contingency principle to prevent criticality accidents. Control failures of at least two parameters are needed for the occurrence of criticality accident. To evaluate the probability of such control failures, the criticality conditions of each parameter for a specific handling unit are necessary for accident scenario analysis to be clarified quantitatively with a criticality analysis computer code. In addition to this issue, a computer-based control system for mass inventory is planned to be installed into MOX handling equipment in a commercial MOX fuel fabrication plant. The reliability analysis is another important issue in evaluating the likelihood of control failure caused by software malfunction. A likelihood estimation method for criticality accident has been developed with these issues been taken into consideration. In this paper, an example of analysis with the proposed method and the applicability of the method are also shown through a trial application to a model MOX fabrication facility. (author)

Damage Evaluation of Critical Components of Tilted Support Spring Nonlinear System under a Rectangular Pulse

Directory of Open Access Journals (Sweden)

Ningning Duan

2015-01-01

Full Text Available Dimensionless nonlinear dynamical equations of a tilted support spring nonlinear packaging system with critical components were obtained under a rectangular pulse. To evaluate the damage characteristics of shocks to packaged products with critical components, a concept of the damage boundary surface was presented and applied to a titled support spring system, with the dimensionless critical acceleration of the system, the dimensionless critical velocity, and the frequency parameter ratio of the system taken as the three basic parameters. Based on the numerical results, the effects of the frequency parameter ratio, the mass ratio, the dimensionless peak pulse acceleration, the angle of the system, and the damping ratio on the damage boundary surface of critical components were discussed. It was demonstrated that with the increase of the frequency parameter ratio, the decrease of the angle, and/or the increase of the mass ratio, the safety zone of critical components can be broadened, and increasing the dimensionless peak pulse acceleration or the damping ratio may lead to a decrease of the damage zone for critical components. The results may lead to a thorough understanding of the design principles for the tilted support spring nonlinear system.

Probing the reaching-grasping network in humans through multivoxel pattern decoding.

Science.gov (United States)

Di Bono, Maria Grazia; Begliomini, Chiara; Castiello, Umberto; Zorzi, Marco

2015-11-01

The quest for a putative human homolog of the reaching-grasping network identified in monkeys has been the focus of many neuropsychological and neuroimaging studies in recent years. These studies have shown that the network underlying reaching-only and reach-to-grasp movements includes the superior parieto-occipital cortex (SPOC), the anterior part of the human intraparietal sulcus (hAIP), the ventral and the dorsal portion of the premotor cortex, and the primary motor cortex (M1). Recent evidence for a wider frontoparietal network coding for different aspects of reaching-only and reach-to-grasp actions calls for a more fine-grained assessment of the reaching-grasping network in humans by exploiting pattern decoding methods (multivoxel pattern analysis--MVPA). Here, we used MPVA on functional magnetic resonance imaging (fMRI) data to assess whether regions of the frontoparietal network discriminate between reaching-only and reach-to-grasp actions, natural and constrained grasping, different grasp types, and object sizes. Participants were required to perform either reaching-only movements or two reach-to-grasp types (precision or whole hand grasp) upon spherical objects of different sizes. Multivoxel pattern analysis highlighted that, independently from the object size, all the selected regions of both hemispheres contribute in coding for grasp type, with the exception of SPOC and the right hAIP. Consistent with recent neurophysiological findings on monkeys, there was no evidence for a clear-cut distinction between a dorsomedial and a dorsolateral pathway that would be specialized for reaching-only and reach-to-grasp actions, respectively. Nevertheless, the comparison of decoding accuracy across brain areas highlighted their different contributions to reaching-only and grasping actions. Altogether, our findings enrich the current knowledge regarding the functional role of key brain areas involved in the cortical control of reaching-only and reach-to-grasp actions

Electroplating method for producing ultralow-mass fissionable deposits

International Nuclear Information System (INIS)

Ruddy, F.H.

1989-01-01

A method for producing ultralow-mass fissionable deposits for nuclear reactor dosimetry is described, including the steps of holding a radioactive parent until the radioactive parent reaches secular equilibrium with a daughter isotope, chemically separating the daughter from the parent, electroplating the daughter on a suitable substrate, and holding the electroplated daughter until the daughter decays to the fissionable deposit

Interest Convergence or Divergence? A Critical Race Analysis of Asian Americans, Meritocracy, and Critical Mass in the Affirmative Action Debate

Science.gov (United States)

Park, Julie J.; Liu, Amy

2014-01-01

We use the Critical Race Theory frameworks of interest convergence and divergence to critique the anti-affirmative action movement's co-option of Asian Americans. Past discussions of affirmative action and Asian Americans mainly concentrate on how Asian Americans are affected by affirmative action, whether positively or negatively. We demonstrate…

Comparative Analysis of Mass Spectral Similarity Measures on Peak Alignment for Comprehensive Two-Dimensional Gas Chromatography Mass Spectrometry

Science.gov (United States)

2013-01-01

Peak alignment is a critical procedure in mass spectrometry-based biomarker discovery in metabolomics. One of peak alignment approaches to comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS) data is peak matching-based alignment. A key to the peak matching-based alignment is the calculation of mass spectral similarity scores. Various mass spectral similarity measures have been developed mainly for compound identification, but the effect of these spectral similarity measures on the performance of peak matching-based alignment still remains unknown. Therefore, we selected five mass spectral similarity measures, cosine correlation, Pearson's correlation, Spearman's correlation, partial correlation, and part correlation, and examined their effects on peak alignment using two sets of experimental GC×GC-MS data. The results show that the spectral similarity measure does not affect the alignment accuracy significantly in analysis of data from less complex samples, while the partial correlation performs much better than other spectral similarity measures when analyzing experimental data acquired from complex biological samples. PMID:24151524

Accelerated modern human?induced species losses: Entering the sixth mass extinction

OpenAIRE

Ceballos, Gerardo; Ehrlich, Paul R.; Barnosky, Anthony D.; Garc?a, Andr?s; Pringle, Robert M.; Palmer, Todd M.

2015-01-01

The oft-repeated claim that Earth?s biota is entering a sixth ?mass extinction? depends on clearly demonstrating that current extinction rates are far above the ?background? rates prevailing between the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we...

The mass media exposure and disordered eating behaviours in Spanish secondary students.

Science.gov (United States)

Calado, María; Lameiras, María; Sepulveda, Ana R; Rodríguez, Yolanda; Carrera, María V

2010-01-01

The aim of this study was to investigate the association between disordered eating behaviours/attitudes and mass media exposure in a cross-sectional national survey of 1165 Spanish secondary students (age between 14 and 16 years). A battery of questionnaires were used to investigate mass media influence, body dissatisfaction, physical appearance, sociocultural attitudes and self-esteem. Likewise, the EAT-26 questionnaire was used to assess disordered eating behaviours/attitudes, identifying that 6.6% (n = 32) of the male and 13.6% (n = 68) of the female students reached a cut-off point of 20 or above. The main finding was that female and male adolescents with disordered eating showed an increased exposure to TV and magazine sections related to body image, specifically regarding music video channels, in comparison with those without eating disordered, gender-matched counterparts. However, findings indicate that media exposure was different to some degree between males and females with disordered eating behaviour. Males with disordered eating behaviours and attitudes were associated with higher TV and magazine exposure to health sections and also greater body dissatisfaction, internalisation of the thin-ideal and social and appearance comparison. In females, disordered eating was associated with higher TV and magazine exposure to dieting, fashion and sport sections, greater body dissatisfaction, internalisation and awareness of the thin-ideal and lower self-esteem. Understanding the mechanism involved in the media exposure's influence on adolescents is critical in preventing disordered eating.