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1

The geyser effect in a two-phase thermosyphon  

NASA Astrophysics Data System (ADS)

The geyser effect in a two-phase thermosyphon using water as the working fluid is investigated experimentally in order to provide a foundation for future theoretical work. It is shown that boiling in a two-phase syphon is a rather complex process and that at low pressures it involves the formation of bubbles of large diameter. The nucleation of individual bubbles occurs at large time intervals which, however, decrease when the specific thermal flux increases. An important conclusion is that the cyclic phenomenon observed in the thermosyphon can be studied in the evaporator using special methods for boiling-related phenomena.

Casarosa, C.; Latrofa, E.; Shelginskii, A.

1983-06-01

2

Titanium-Water Thermosyphon Gamma Radiation Effects and Results  

NASA Technical Reports Server (NTRS)

Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some exposure to gamma irradiation. Non-condensable gas formation from radiation may breakdown water over time and render a portion of the thermosyphon condenser inoperable. A series of developmental thermosyphons were operated at nominal operating temperature with accelerated gamma irradiation exposures on the same order of magnitude that is expected in eight years of heat rejection system operation. Temperature data were obtained during exposure at three locations on each thermosyphon; evaporator, condenser, and condenser end cap. Some non-condensable gas was evident, however thermosyphon performance was not affected because the non-condensable gas was compressed into the fill tube region at the top of the thermosyphon, away from the heat rejecting fin. The trend appeared to be an increasing amount of non-condensable gas formation with increasing gamma irradiation dose. Hydrogen is thought to be the most likely candidate for the non-condensable gas and hydrogen is known to diffuse through grain boundaries. Post-exposure evaluation of selected thermosyphons at temperature and in a vacuum chamber revealed that the non-condensable gas likely diffused out of the thermosyphons over a relatively short period of time. Further research shows a number of experimental and theoretical examples of radiolysis occurring through gamma radiation alone in pure water.

Sanzi, James L.; Jaworske, Donald A.; Goodenow, Debra A.

2012-01-01

3

Titanium-Water Thermosyphon Gamma Radiation Effects and Results.  

National Technical Information Service (NTIS)

Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some exposure to gamma irradiation. Non-condensable gas formation from radiation may break...

D. A. Goodenow D. A. Jaworske J. L. Sanzi

2012-01-01

4

Effect of nanoparticles in nanofluid on thermal performance in a miniature thermosyphon  

NASA Astrophysics Data System (ADS)

An experiment was performed to investigate the effect of nanoparticles in the nanofluid on the thermal performance in a miniature thermosyphon. The nanofluids consisted of de-ionized water and CuO nanoparticles having an average size of 30 nm. The experimental results show that the water-CuO nanofluids can greatly enhance the boiling heat transfer performance of the evaporator in thermosyphon compared with that using water at subatmospheric pressure conditions. A much lower and more uniform wall temperature of the thermosyphon can be obtained by substituting the nanofluids for water. Boiling heat transfer coefficients and the critical heat flux (CHF) of the nanofluids in the evaporator of the thermosyphon have significant increase compared with those of de-ionized water. There was an optimal mass concentration which was estimated to be 1.0 wt % to achieve the maximum heat transfer performance. Operating pressure has very remarkable influences on both the heat transfer coefficients and the CHF of nanofluids, which greatly increase with the decrease of the test pressure. The heat transfer coefficient and the CHF can increase, respectively, about 160% and 120% at the pressure of 7.45 kPa compared with those of water. The experimental study confirmed that the heat transfer performance of the miniature thermosyphon can evidently be strengthened by using water-CuO nanofluids.

Liu, Zhen Hua; Yang, Xue Fei; Guo, Guang Liang

2007-07-01

5

Effect of Inclination Angle and Filling Ratio on Thermal Performance of a Two-Phase Closed Thermosyphon under Normal Operating Conditions  

Microsoft Academic Search

In this paper, the effect of the inclination angle on the thermal performance of a two-phase closed thermosyphon with different filling ratios has been investigated experimentally under normal operating conditions. A series of experiments were carried out for inclination angle range of 5°–90° and filling ratios of 15%, 22%, and 30%. A copper thermosyphon with an outside diameter of 16

S. H. Noie; M. R. Sarmasti Emami; M. Khoshnoodi

2007-01-01

6

Harvesting low grade heat to generate electricity with thermosyphon effect of room temperature liquid metal  

NASA Astrophysics Data System (ADS)

Based on thermosyphon effect of room temperature liquid metal, a technical strategy of harvesting low grade heat to generate electricity was proposed. A conceptual system was constructed and an open circuit voltage of 2.62 V with an electrical output power of 110 mW was yielded when the heating power was 45.6 W. This method resolves the difficulty of installing an electric generator in confined space and significantly enlarges the area for converting heat to electricity. Due to its simplicity, avoidance of moving parts, wide working temperature range, and self powering feature, this electric generation system is extremely reliable, completely silent, and flexible.

Li, Peipei; Liu, Jing

2011-08-01

7

Design Parameters for Cryogenic Thermosyphons  

NASA Astrophysics Data System (ADS)

Cryogenic thermosyphons are the thermal conductors of choice for a variety of applications such as conduction-cooled superconducting devices. They exhibit a small effective thermal resistance at small cross-sections. A careful design, however, is crucial to ensure sufficient heat transport for all possible heatloads. The aim of this work is to obtain experimental results on critical limitations and the effective thermal conductivity dependent on the length, the cross-sectional area, and the working liquid fill level of a thermosyphon for different heatloads. For the experiments, a modular thermosyphon was designed with 5 different adiabatic tubes of length [cm]/cross-sectional diameter [cm] 10/1, 10/2, 30/0.5, 30/1, 30/2, which can be mounted between condenser and evaporator. The thermosyphon was operated with different fill levels of either nitrogen or neon and different heatloads. The effective thermal conductivity between condenser and evaporator was determined, dependent on the design parameters mentioned above. Additionally, the useful temperature range of operation was determined, and limitations were monitored and visualized using a built-in camera. The results can support the proper design of thermosyphons for dedicated applications by providing information about the heat transport capability for different thermosyphon design parameters.

Timinger, H.; David, B.; Eckart, R.; Overweg, J.

2008-03-01

8

The Effect of Subcooling on the Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon  

NASA Astrophysics Data System (ADS)

A two-phase loop thermosyphon is used as a heat transfer device in an energy-saving heat transportation system and so forth, because it transports thermal energy without any external power supply such as a pump under a body force field. We previously performed a fundamental study on the flow and heat transfer characteristics in a two-phase loop thermosyphon installed with a single heated tube evaporator both experimentally and theoretically which was made under the condition of near saturation temperature of liquid in a reservoir. In the present study, the effects of liquid subcooling and the heat input on the circulation mass flow rates, pressure and temperature distributions, and heat transfer coefficients in the evaporator were examined experimentally using water, ethanol, benzene and Freon 113 as the working fluids. On the other hand, the circulation mass flow rates, pressure and temperature distributions were theoretically calculated and compared with the experimental results.

Imura, Hideaki; Takeshita, Kazuhiro; Doi, Kyoji; Noda, Ken-Ichi

9

Investigation on the effect of filling ratio on the steady-state heat transfer performance of a vertical two-phase closed thermosyphon  

Microsoft Academic Search

Filling ratio of the working fluid has a predominant effect on the heat transfer characteristics of a two-phase closed thermosyphon (TPCT). A comprehensive model is developed to investigate the effect of filling ratio on the steady-state heat transfer performance of a vertical TPCT. Three types of flow pattern and two types of transition, according to the distribution of liquid film

B. Jiao; L. M. Qiu; X. B. Zhang; Y. Zhang

2008-01-01

10

Heat transfer characteristics of rotating triangular thermosyphon  

NASA Astrophysics Data System (ADS)

An experimental investigation is carried out to study heat transfer characteristics of a rotating triangular thermosyphon, using R-134a refrigerant as the working fluid. The tested thermosyphon is an equilateral triangular tube made from copper material of 11 mm triangular length, 2 mm thickness, and a total length of 1,500 mm. The length of the evaporator section is 600 mm, adiabatic section is 300 mm, and condenser section is 600 mm. The effects of the rotational speed, filling ratio, and the evaporator heat flux on each of the evaporator heat transfer coefficient, he, condenser heat transfer coefficient, hc, and the overall effective thermal conductance, Ct are studied. Experiments are performed with a vertical position of thermosyphon within heat flux ranges from 11 to 23 W/m2 for the three selected filling ratios of 10, 30 and 50 % of the evaporator section volume. The results indicated that the maximum values of the tested heat transfer parameters of the rotational equilateral triangular thermosyphon are obtained at the filling ratio of 30 %. Also, it is found that the heat transfer coefficient of the condensation is increased with increasing the rotational speed. The tested heat transfer parameters of the thermosyphon are correlated as a function of the evaporator heat flux and angular velocity.

Ibrahim, E.; Moawed, M.; Berbish, N. S.

2012-09-01

11

Majorana Thermosyphon Prototype Experimental Setup.  

National Technical Information Service (NTIS)

This report presents the experimental setup of Pacific Northwest National Laboratory's MAJORANA DEMONSTRATOR thermosyphon prototype cooling system. A nitrogen thermosyphon prototype of such a system has been built and tested at PNNL. This document present...

A. D. Guzman D. J. Reid J. T. Munley

2011-01-01

12

A model of flow in a closed-loop thermosyphon including the Soret effect  

NASA Technical Reports Server (NTRS)

This theoretical study addresses the nature of convective motions in a toroidal loop of binary fluid oriented in the vertical plane and heated from below. The boundaries of the loop are impermeable, but gradients of the solute can be set up by Soret diffusion in the direction around the loop. The existence and stability of steady solutions are discussed over the Rayleigh number-Soret coefficient parameter plane. When the Soret coefficient is negative, periodic and chaotic oscillations analogous to those of thermohaline convection are predicted. When the Soret coefficient is positive, relaxation oscillations and low Rayleigh number chaotic motions are found. Both sets of phenomena are predicted to occur for realistic thermosyphon parameters.

Hart, J. E.

1985-01-01

13

Effects of auxiliary heater on annual performance of thermosyphon solar water heater simulated under variable operating conditions  

Microsoft Academic Search

A thermosyphon solar water heating system with electric auxiliary heater was simulated using the TRNSYS simulation program. Location of the auxiliary heater, inside the storage tank or connected in series between the system and the user, was studied using the TMY meteorological data for Los Angeles, California. Simulations were performed for two different water load temperatures (60 and 80°C) and

A. M. Shariah; G. O. G. Löf

1997-01-01

14

Majorana Thermosyphon Prototype Experimental Setup  

SciTech Connect

This report presents the experimental setup of Pacific Northwest National Laboratory’s MAJORANA DEMONSTRATOR thermosyphon prototype cooling system. A nitrogen thermosyphon prototype of such a system has been built and tested at PNNL. This document presents the experimental setup of the prototype that successfully demonstrated the heat transfer performance of the system.

Reid, Douglas J.; Guzman, Anthony D.; Munley, John T.

2011-08-01

15

The interface effect of carbon nanotube suspension on the thermal performance of a two-phase closed thermosyphon  

NASA Astrophysics Data System (ADS)

An aqueous solution of carbon nanotubes, treated by a concentrated nitric/sulfuric acid mixture to disentangle the nanotubes, was utilized as the working medium in a two-phase closed thermosyphon to investigate its performance. In comparison with the thermosyphon filled with a distilled water medium, the one filled with carbon nanotube suspension has a high evaporation section wall temperature, incipience temperature, and excursion, as well as thermal resistance. The carbon nantotubes' nanofluid deteriorates the performance of the gravity-assisted heat pipe. Measurements employing the maximum bubble pressure method demonstrate that suspending carbon nanotubes in bulk water gives rise to increased surface tension. In addition, the contact angle of suspension obtained with the sessile drop method on a copper plate is much smaller than that of water. Alterations of solid-liquid-vapor interfacial properties, arising from the addition of carbon nanotubes, change the boiling mechanism and thus deteriorate the boiling heat transfer.

Xue, H. S.; Fan, J. R.; Hu, Y. C.; Hong, R. H.; Cen, K. F.

2006-11-01

16

Axi-symmetric simulation of a two phase vertical thermosyphon using Eulerian two-fluid methodology  

NASA Astrophysics Data System (ADS)

Numerical simulation of steady state operation of a vertical two phase closed thermosyphon is performed using the two-fluid methodology within Eulerian multiphase domain. A full scale axi-symmetric model is developed for computational fluid dynamics simulation of thermosyphon using ANSYS/FLUENT 13.0. The effects of evaporation, condensation and interfacial heat and mass transfer are taken into account within the whole domain. Cooling water jacket is also modelled along with the wall of thermosyphon to simulate the effect of conjugate heat transfer between the wall and fluid phase. The results obtained are presented and compared with available experimental investigations for a similar thermosyphon. It is established that two-fluid methodology can be used effectively for the purpose of simulation of two phase system like a typical thermosyphon.

Kafeel, Khurram; Turan, Ali

2013-08-01

17

Flexible cryogenic thermosyphon  

NASA Astrophysics Data System (ADS)

Cryocooler and pulse tubes have been increasingly used in small and large scale cryogenic systems including the superconducting magnet systems as heat sinks to attain and keep the required temperatures. Designing the thermal link between the mechanical refrigerator and the system may present a challenge due to the mechanical stresses developed during the cool-down of the assembled systems. Also, the cross section may be too bulky for metallic conductors for given thermal specifications. In this paper, a thermosysphon with a flexible fluid link between the evaporator and condenser is presented. The working fluid used in preliminary testing is nitrogen. The results of the initial testing of the flexible thermosyphon are presented.

Celik, Dogan; Painter, Thomas

2012-06-01

18

Critical Heat Flux of Concentric-Tube Thermosyphon  

NASA Astrophysics Data System (ADS)

An experimental study has been performed to investigate the critical heat flux in a concentric-tube thermosyphon which has the straight shape of an inner tube. The outer tube was 27.4mm in diameter with 1080mm in height. Visual observations and measurments were carried out under the condition of uniform wall heat flux using R-11 and R-113 as the working liquid. The effects of inner tube diameter, insert length of inner tube into reservoir, and liquid subcooling on critical heat flux were extensively discussed. In addition, same experiments of single-tube thermosyphon were carried out for comparison. It was found that critical heat flux characteristics for concentric-tube thermosyphon were classified two regions. The correlation equations of both regions and transition condition were determined.

Kawabe, Hiromichi; Tanaka, Teimi; Fukusako, Shoichiro

19

Influence of system pressure on the boiling heat transfer coefficient in a closed two-phase thermosyphon loop  

Microsoft Academic Search

In recent years heat generation from electronic components has been rapidly increasing. Natural and forced convection air-cooled heat sinks are not well suited for cooling the components generating the highest heat fluxes. Other methods are therefore sought. Recently the use of thermosyphons has attracted attention as a simple and effective cooling system for high heat flux components. In a thermosyphon

Rahmatollah Khodabandeh; Björn Palm

2002-01-01

20

Critical heat flux in a closed two-phase thermosyphon  

Microsoft Academic Search

An experimental study was made of critical heat flux in a closed two-phase thermosyphon. The effects of inside diameter, heated length, working liquid, fill charge and inside temperature on the critical heat flux were investigated. The present and previously-published experimental data were correlated with expressions already proposed by other investigators but the agreements were not good. Accordingly, a new correlating

H. Imura; K. Sasaguchi; H. Kozai; S. Numata

1983-01-01

21

Wall shape optimization for a thermosyphon loop featuring corrugated pipes  

NASA Astrophysics Data System (ADS)

In the present paper we address the problem of optimal wall-shape design of a single phase laminar thermosyphon loop. The model takes the buoyancy forces into account via the Boussinesq approximation. We focus our study on showing the effects of wall shape on the flow and on the temperature inside the thermosyphon. To this extend we determine the dependency of the flow rate and the increase in temperature, on the geometrical characteristics of the loop. The geometry considered is a set of axially symmetric corrugated pipes described by a set of parameters; namely the pipe inner radius, the period of the corrugation, the amplitude of the corrugation, and the ratio of expansion and contraction regions of a period of the pipe. The governing equations are solved using the Finite Element Method, in combination with an adaptive mesh refinement technique in order to capture the effects of wall shape. We characterize the effects of the amplitude and of the ratio of expansion and contraction. In particular we show that for a given fixed amplitude it is possible to find an optimal ratio of expansion and contraction that minimizes the temperature inside the thermosyphon. The results show that by adequately choosing the design parameters, the performance of the thermosyphon loop can be improved.

Rosen Esquivel, Patricio I.; ten Thije Boonkkamp, Jan H. M.; Dam, Jacques A. M.; Mattheij, Robert M. M.

2012-06-01

22

Application of functionalized nanofluid in thermosyphon  

NASA Astrophysics Data System (ADS)

A water-based functionalized nanofluid was made by surface functionalizing the ordinary silica nanoparticles. The functionalized nanofluid can keep long-term stability. and no sedimentation was observed. The functionalized nanofluid as the working fluid is applied in a thermosyphon to understand the effect of this special nanofluid on the thermal performance of the thermosyphon. The experiment was carried out under steady operating pressures. The same work was also explored for traditional nanofluid (consisting of water and the same silica nanoparticles without functionalization) for comparison. Results indicate that a porous deposition layer exists on the heated surface of the evaporator during the operating process using traditional nanofluid; however, no coating layer exists for functionalized nanofluid. Functionalized nanofluid can enhance the evaporating heat transfer coefficient, while it has generally no effect on the maximum heat flux. Traditional nanofluid deteriorates the evaporating heat transfer coefficient but enhances the maximum heat flux. The existence of the deposition layer affects mainly the thermal performance, and no meaningful nanofluid effect is found in the present study.

Yang, Xue-Fei; Liu, Zhen-Hua

2011-08-01

23

Application of functionalized nanofluid in thermosyphon  

PubMed Central

A water-based functionalized nanofluid was made by surface functionalizing the ordinary silica nanoparticles. The functionalized nanofluid can keep long-term stability. and no sedimentation was observed. The functionalized nanofluid as the working fluid is applied in a thermosyphon to understand the effect of this special nanofluid on the thermal performance of the thermosyphon. The experiment was carried out under steady operating pressures. The same work was also explored for traditional nanofluid (consisting of water and the same silica nanoparticles without functionalization) for comparison. Results indicate that a porous deposition layer exists on the heated surface of the evaporator during the operating process using traditional nanofluid; however, no coating layer exists for functionalized nanofluid. Functionalized nanofluid can enhance the evaporating heat transfer coefficient, while it has generally no effect on the maximum heat flux. Traditional nanofluid deteriorates the evaporating heat transfer coefficient but enhances the maximum heat flux. The existence of the deposition layer affects mainly the thermal performance, and no meaningful nanofluid effect is found in the present study.

2011-01-01

24

Application of functionalized nanofluid in thermosyphon.  

PubMed

A water-based functionalized nanofluid was made by surface functionalizing the ordinary silica nanoparticles. The functionalized nanofluid can keep long-term stability. and no sedimentation was observed. The functionalized nanofluid as the working fluid is applied in a thermosyphon to understand the effect of this special nanofluid on the thermal performance of the thermosyphon. The experiment was carried out under steady operating pressures. The same work was also explored for traditional nanofluid (consisting of water and the same silica nanoparticles without functionalization) for comparison. Results indicate that a porous deposition layer exists on the heated surface of the evaporator during the operating process using traditional nanofluid; however, no coating layer exists for functionalized nanofluid. Functionalized nanofluid can enhance the evaporating heat transfer coefficient, while it has generally no effect on the maximum heat flux. Traditional nanofluid deteriorates the evaporating heat transfer coefficient but enhances the maximum heat flux. The existence of the deposition layer affects mainly the thermal performance, and no meaningful nanofluid effect is found in the present study. PMID:21846362

Yang, Xue-Fei; Liu, Zhen-Hua

2011-01-01

25

Experimental Study of Separate Type Thermosyphon  

NASA Astrophysics Data System (ADS)

The passages of vapor flow and the returning liquid flow are perfectly partitioned in a separate type thermosyphon. Therefore the flooding limit can be eliminated and practicability based on its construction is highly evaluated. The carry-over of the liquid into the condensing section accompanied with the rising vapor flow should be avoided in the separate type thermosyphon, since it causes to decrease the heat transfer coefficient on the heat transfer surface in the condenser. In the present work, the effect of liquid level, the heat input into the evaporating section, the charging rate of the liquid, and the dimension of the adiabatic section supposed on the generation of carry-over were studied experimentally. The frequency of the bumping and the velocity of the vapor in the adiabatic section were examined as the function of the termination of the carry-over. The experimental correlation representing the relation among the elapsed time, the liquid temperature and the charging rate of the liquid were also derived.

Hirashima, Masao; Kawahata, Kenya; Negishi, Kanji

26

Heat Transfer Characteristics in a Two-Phase Crank-Shape Closed Thermosyphon  

NASA Astrophysics Data System (ADS)

This paper describes the heat transfer characteristics in a two-phase crank-shape closed thermosyphon. Usually, the thermosyphon is composed of an evaporator, an adiabatic section and a condenser arranged on a straight tube. However, a bent geometry of the thermosyphon is sometimes needed to use because of the limited space for the straight thermosyphon to be installed. Therefore, in the present study, the crank-shape thermosyphon is investigated on the heat transfer coefficients and the critical heat fluxes. The evaporator and the condenser are positioned vertically and the adiabatic section horizontally. The inside diameter of thermosyphon is 16 mm and each length of the evaporator and condenser is 500 mm. As a working fluid, water is used. The inside temperature (the adiabatic wall temperature) is varied from 40 to 80 °C. The distance between the centers of the vertical evaporator and condenser, i. e. , the offset length is varied from 220 to 620 mm, and the effect of the offset length on the heat transfer characteristics is presented.

Imura, Hideaki; Koito, Yasuhi

27

In-situ study on cooling effect of the two-phase closed thermosyphon and insulation combinational embankment of the Qinghai–Tibet Railway  

Microsoft Academic Search

Based on the observation data of the two-phase closed thermosyphon and insulation combinational test embankment of the Qinghai–Tibet Railway, variations of permafrost table, thermal regime changes, heat budget and heat exchange of the combinational embankment were analyzed. As control groups, natural ground and a traditional soil embankment were also analyzed. Considering thermal asymmetry in the north and the south slopes,

Junjie Wu; Wei Ma; Zhizhong Sun; Zhi Wen

2010-01-01

28

Majorana Thermosyphon Prototype Experimental Results  

SciTech Connect

Objective The Majorana demonstrator will operate at liquid Nitrogen temperatures to ensure optimal spectrometric performance of its High Purity Germanium (HPGe) detector modules. In order to transfer the heat load of the detector module, the Majorana demonstrator requires a cooling system that will maintain a stable liquid nitrogen temperature. This cooling system is required to transport the heat from the detector chamber outside the shield. One approach is to use the two phase liquid-gas equilibrium to ensure constant temperature. This cooling technique is used in a thermosyphon. The thermosyphon can be designed so the vaporization/condensing process transfers heat through the shield while maintaining a stable operating temperature. A prototype of such system has been built at PNNL. This document presents the experimental results of the prototype and evaluates the heat transfer performance of the system. The cool down time, temperature gradient in the thermosyphon, and heat transfer analysis are studied in this document with different heat load applied to the prototype.

Fast, James E.; Reid, Douglas J.; Aguayo Navarrete, Estanislao

2010-12-17

29

Experimental Study on Heat Transfer in an Open Thermosyphon  

NASA Astrophysics Data System (ADS)

Heat transfer coefficient in an open thermosyphon is very small, because the flow in the thermosyphon is confined to a narrow space by the wall of tube with a closed bottom end. Therefore, augmentation of heat transfer due to air injection from the bottom has been suggested. The heat transfer is enhanced by the stirring action of rising bubbles. In response to this, the authors performed an experimental investigation of this subject. Seven test tubes with different diameter and length were employed, and water, ethyl alcohol and ethylene glycol were used as test liquids. The heat transfer coefficients were measured and the effects of air injection rate, tube diameter, tube length and liquid properties were examined. And experimental correlations were presented by using dimensional analysis.

Imura, Hideaki; Kozai, Hiroaki

30

Natural Convection in Annular Duct Forming Thermosyphon.  

National Technical Information Service (NTIS)

The experimental study of the heat transfer for water in an annular duct forming a thermosyphon with a large volume tank, determining correlations for the Nusselt Namber as a function of Rayleigh Number for three diameter ratios is presented. Furthermore,...

S. V. Moeller A. J. Silva Neto

1985-01-01

31

Heat transfer characteristics of a two-phase closed thermosyphon using de ionized water mixed with silver nano  

Microsoft Academic Search

Effect of using silver nanofluid (De Ionize water mixed with silver nano and particles less than 100 nm.) on heat transfer\\u000a characteristics of a two-phase closed thermosyphon at normal operating condition was investigated in this research. The thermosyphon\\u000a made by copper tube with 7.5, 11.1 and 25.4 mm ID. The filling ratios of 30, 50 and 80% by evaporator length and aspect

T. Paramatthanuwat; S. Boothaisong; S. Rittidech; K. Booddachan

2010-01-01

32

Experimental Study of Top Heat Mode Thermosyphon  

NASA Astrophysics Data System (ADS)

The purpose of this study is to develop the top heat mode thermosyphon that is very attractive means, for example, to accumulate directly the summer solar energy into the underground soil for the winter season. In this case, it can exclude the complex piping and mechanical pump to circulate the hot water absorbed the solar energy through the piping system buried in the soil layer. The several ideas concerning the top heat thermosyphon had been proposed, however, there were few reports on the definite experiments. The authors have carried out the experimental study of the top heat mode thermosyphon, with a simple lifting pipe, which could draw the working liquid from the under condenser to the upper evaporator section. The improvement of the main construction parts such as evaporator, lifting pipe, liquid reservoir trap and vapour nozzle have been performed in the present experiment in order to obtain the optimum operation range.

Hirashima, Masao; Kimura, Kenichiro; Utsumi, Yoichi; Kimura, Kenichi; Negishi, Kanji

33

Heat transfer in the evaporator of an advanced two-phase thermosyphon loop  

Microsoft Academic Search

As heat generation from electronic components increase and the limit of air-cooling is reached, the interest for using liquid cooling for high heat flux applications has risen. Thermosyphon cooling is an alternative liquid cooling technique, in which heat is transferred as heat of vaporization from evaporator to condenser with a relatively small temperature difference.The effect of fluid properties, the structure

Rahmatollah Khodabandeh

2005-01-01

34

Aqueous propylene-glycol concentrations for the freeze protection of thermosyphon solar energy water heaters  

Microsoft Academic Search

Using a validated dynamic simulation model, the thermal performance of an indirect thermosyphon solar energy water heater was examined. The heat transfer fluids employed were aqueous solutions of propylene glycol. The effect of varying the glycol concentration on the hot water output and efficacy of freeze protection was determined for a specific pattern of hot water withdrawal and weather for

B. Norton; J. E. J. Edmonds

1991-01-01

35

The optimization of tank-volume-to-collector-area ratio for a thermosyphon solar water heater  

Microsoft Academic Search

Through the use of the TRNSYS simulation program, the performance of a domestic solar water heating system operating with natural circulation (thermosyphon) and a daily hot water load has been analysed. The effect of tank height on the annual solar fraction of the system has been investigated for different hot water load temperatures and storage tank volumes. Optimum values (values

G. O. G. Löf

1996-01-01

36

Cryogenic Nitrogen Thermosyphon Developed and Characterized.  

National Technical Information Service (NTIS)

A two-phase nitrogen thermosyphon was developed at the NASA Glenn Research Center to efficiently integrate a cryocooler into an insulated liquid-nitrogen-filled tank as part of an advanced development zero-boiloff (ZBO) ground test. NASA Marshall Space Fl...

D. W. Plachta R. Christie

2004-01-01

37

Thermosyphon Suspension For Growth Of Crystals  

NASA Technical Reports Server (NTRS)

Thermosyphon provides gentle convective flow of supersaturated solution that both suspends and contributes material to growing crystal. Apparatus includes heating section, cooling section, and expansion-and-growth chamber in closed flow loop. Intended for growth of protein crystals, so fragile they are easily damaged by high-shear flows produced by pumps.

Nyce, Thomas A.

1991-01-01

38

TWO-PHASE CLOSED THERMOSYPHON WITH NANOFLUIDS  

Microsoft Academic Search

Nanofluids, stabilized suspensions of nanoparticles typically < 100 nm in conventional fluids, are evolving as potential enhanced heat transfer fluids due to their better thermal conductivity, increase in single phase heat transfer coefficient and significant increase in critical boiling heat flux. In the present paper, we investigate the overall thermal resistance of a closed two-phase thermosyphon using pure water and

Balkrishna Mehta; Sameer Khandekar

2007-01-01

39

Heat Transfer in a Two-Phase Closed-Loop Thermosyphon  

NASA Astrophysics Data System (ADS)

A two-phase closed-loop thermosyphon is a device which transports heat energy from a heat source to a sink under the body force field and has many practical applications. The critical heat flux of this thermosyphon is larger than that of a non-loop thermosyphon, because the flooding phenomenon occurring in the no-loop one does not occur. In addition, there is another merit that the evaporator and the condencer can be installed in comparatively arbitrary position because these are interconnected by piping. In most previous investigations of the two-phase closed-loop thermosyphons, overall heat resistances were measured. The overall heat resistance, however, consists of three heat resistances; the heat resistances in the evaporator and the condenser, and the transport resistance in the interconnecting pipe. Therefore, we should consider these heat resistances separately. In the present study, we took note of the heat resistances (or heat transfer coefficients) of the evaporator and the condenser. The experiment was performed using two experimental setups and three kinds of test liquid. And, the effects of rotation angle, heat flux, inside temperature (or inside pressure) and liquid charge on the heat transfer coefficients were investigated.

Imura, Hideaki; Saito, Yuji

40

The design of an ultra-low background thermosyphon for the Majorana Demonstrator  

NASA Astrophysics Data System (ADS)

The MAJORANA DEMONSTRATOR (MJD) is an ultra-low background neutrinoless double-beta decay (0???) experiment that will deploy up to 40 kg of high purity germanium detectors (HPGe). The goal of this experiment is to demonstrate the feasibility of building a detector array with less than 1 event/ton year in a 4 keV region of interest around the 0??? signal. HPGe diodes, when used as ionizing radiation detectors, need to be maintained at a temperature close to that of liquid nitrogen (77 K). This work describes the results of research and development toward a cryogenic system capable of meeting the ultra-low background requirements while providing the required cryogenic cooling capacity of 15-30 W. This paper shows the experimental results obtained using a two-phase horizontal thermosyphon using nitrogen as the working fluid. The cold tests show that the proposed thermosyphon has sufficient cooling power to handle the heat load of an MJD module. Results for the temperature gradient across the thermosyphon, cooling capacity, and design considerations demonstrate that the thermosyphon can effectively remove the calculated heat load of each module of the experiment.

Aguayo, E.; Busch, M.; Daniels, R.; Fast, J. E.; Green, M. P.; Reid, D. J.

2013-05-01

41

A correlation to predict heat-transfer rates of a two-phase closed thermosyphon (TPCT) using silver nanofluid at normal operating conditions  

Microsoft Academic Search

The effect of using silver nanofluid (de ionized water mixed with silver nano and particles less than 100nm) on the thermal characteristics of a two-phase closed thermosyphon in an operating state was investigated in this research. The thermosyphon was made with copper tubes with 7.5, 11.1 and 25.4mm ID. The filling ratios of 30%, 50% and 80% by evaporator length

T. Parametthanuwat; S. Rittidech; A. Pattiya

2010-01-01

42

A passive thermosyphon heat exchanger for residential solar installations  

NASA Technical Reports Server (NTRS)

The paper details the development of a thermosyphon water-to-air heat exchanger for residential solar applications. Modeling techniques used in the analysis of thermosyphon performance are included, as well as test results from laboratory-scale experiments. In addition, a description of the initial full-scale prototype is presented, along with experimental test results. Present areas of development are discussed, with an economic comparison of thermosyphon and forced convection heating systems also being included.

Franklin, J. L.; Saaski, E. W.; Hankins, J. D.

1977-01-01

43

Active control of fluid equilibrium in a thermosyphon  

NASA Astrophysics Data System (ADS)

We have theoretically and experimentally studied the problem of automated control over the mechanical equilibrium of an inhomogeneously heated fluid in a rectangular convection loop (thermosyphon), which comprises two coupled vertical channels with rectangular cross sections arranged in a unit made of a heat-conducting material. The equilibrium is maintained using a control feedback subsystem (controller) capable of responding to the onset of a convective motion by introducing small changes in the spatial orientation of the thermosyphon in the gravitational field. The effect of the dynamic stabilization of the equilibrium, which is unstable in the absence of control, is achieved in a broad range of parameters of the system. It is established that excess feedback leads to the excitation of oscillations in the system. An analysis of the theoretical model showed that these oscillations are related to a delay in the correction introduced by the controller into the state of the system under control. The experimental data are in perfect agreement with the results of analysis of the theoretical model.

Bratsun, D. A.; Zyuzgin, A. V.; Polovinkin, K. V.; Putin, G. F.

2008-08-01

44

Titanium-Water Thermosyphon Gamma Radiation Exposure and Results  

NASA Technical Reports Server (NTRS)

Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some gamma irradiation. Noncondensable gas formation from radiation-induced breakdown of water over time may render portions of the thermosyphon condenser inoperable. A series of developmental thermosyphons were operated at nominal operating temperature under accelerated gamma irradiation, with exposures on the same order of magnitude as that expected in 8 years of heat rejection system operation. Temperature data were obtained during exposure at three locations on each thermosyphon: evaporator, condenser, and condenser end cap. Some noncondensable gas was evident; however, thermosyphon performance was not affected because the noncondensable gas was compressed into the fill tube region at the top of the thermosyphon, away from the heat rejecting fin. The trend appeared to be an increasing amount of noncondensable gas formation with increasing gamma irradiation dose. Hydrogen is thought to be the most likely candidate for the noncondensable gas and hydrogen is known to diffuse through grain boundaries. Post-exposure evaluation of one thermosyphon in a vacuum chamber and at temperature revealed that the noncondensable gas diffused out of the thermosyphon over a relatively short period of time. Further research shows a number of experimental and theoretical examples of radiolysis occurring through gamma radiation alone in pure water.

Sanzi, James, L.A; Jaworske, Donald, A.; Goodenow, Debra, A.

2012-01-01

45

Heat Transport Using Top-heat-type Thermosyphons  

NASA Astrophysics Data System (ADS)

Usual thermosyphons can only transport heat, from lower to higher positions because they utilize the gravitational force for condensed liquid to flow down from an upper condenser to a lower evaporator. On the other hand, top-heat-type thermosyphons must employ some means to pump up the condensed liquid from the lower condenser to the upper evaporator without consuming any power from outside. In the present report, we first describe the design points of usual heat pipe and thermosyphon, and secondly, as the main subject of this report, review the studies on the top-heat-type thermosyphons which have been published so far. Especially, we pick up four kinds of the top-heat-type thermosyphons and explain briefly about them, because they seem to have more practical applicability.

Imura, Hideaki; Koito, Yasushi

46

Heat-Transfer Characteristics in a Concentric-Tube Closed Thermosyphon  

NASA Astrophysics Data System (ADS)

An experimental study has been performed to investigate the heat-transfer characteristics in a concentric-tube closed thermosyphon in which boiling and free convection take place. The outer tube of the thermosyphon used in this study was 100mm in diameter with 3420mm in height, which consisted of both some individual electrical heating copper tubes of 330mm in length and lucite tubes of 60mm in length. On the other hand, inner copper tubes of 41.3mm and 66.6mm in diameter with 3270mm in length were adopted. Experiments were carried out under the constant wall surface temperature conditions and refrigerant R-11 was utilized as a testing fluid. Out of a number of possible controlling valiables, the effect of the heat flux, the void fraction, the ratio of heating length to the total test section length, and the diametric ratio of the concentric tube on the heat-transfer performance were determined.

Kawabe, Hiromichi; Tanaka, Teimi; Fukusako, Shoichiro

47

Titanium-Water Thermosyphon Gamma Radiation Exposure and Results.  

National Technical Information Service (NTIS)

Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some gamma irradiation. Noncondensable gas formation from radiation-induced breakdown of w...

D. A. Goodenow D. A. Jaworske J. L. A. Sanzi

2012-01-01

48

Heat Transfer Characteristics in Crank-Shape Thermosyphons  

NASA Astrophysics Data System (ADS)

A two-phase closed thermosyphon is applied to gas-to-gas heat exchangers, the cooling of heat generation devices, the melting of snow, the prevention from icing of water on roads and so on. Generally, straight tubes are used as the thermosyphon. However, because of the limited space for the straight thermosyphon to be installed, it is considered that a bent thermosyphon is enforced to employ. In response to this, fundamental experiments are conducted on the heat transfer characteristics in a two-phase crank shape closed thermosyphon, in which an evaporator and a condenser are vertically positioned, and a connecting adiabatic section is horizontal. Ethylene glycol aqueous solutions which have lower freezing points and hydrofluoroether 7100 and 7200 which do not contain chloride are used as the working fluids Heat transfer coefficients and critical heat fluxes in the thermosyphon are measured by changing the amount of charged working fluid (0.30,0.40,0.50 and 0.60 of the evaporator volume),the temperature of the adiabatic section (40,50,60,70 and 80°C) and heat flux (from 4.0 kW /m2 to critical). The experimental results are shown and compared with those taken using water as the working fluid.

Imura, Hedeaki; Koito, Yasushi

49

Corrosion and fouling of tubes used in a thermosyphon economizer: a case study of paint protection  

Microsoft Academic Search

This paper studies the corrosion of thermosyphon tubes used in an economizer. A total of 54 thermosyphon pieces were tested in an economizer using high temperature. The aluminum, copper and black iron thermosyphons were 900 mm long with outside diameters of 22.23, 22.25 and 21.3 mm respectively. The evaporator and condenser sections were 700 and 200 mm respectively. Each type of thermosyphon was

P Terdtoon; C Coykaen; S Tungkum; K Kraitong

2000-01-01

50

Analysis of thermosyphon heat exchangers for use in solar domestic hot water heating systems  

Microsoft Academic Search

A recent innovation in the solar industry is the use of thermosyphon heat exchangers. Determining the performance of these systems requires knowledge of how thermosyphon flow rate and heat exchanger performance vary with operating conditions. This study demonstrates that several thermosyphon heat exchanger designs operate in the laminar mixed convection regime. Empirical heat transfer and pressure drop correlations are obtained

Scott David Dahl

1998-01-01

51

Deployment, testing and analysis of advanced thermosyphon target systems for production of aqueous fluorine-18 via oxygen-18(p,n)fluorine-18  

NASA Astrophysics Data System (ADS)

Single phase and boiling batch water targets are the most common designs for the cyclotron production of 18F via the 18O(p,n) 18F reaction. Thermosyphon targets have design and operating characteristics which enable higher power operation than conventional boiling targets of like size. Experimental thermosyphon target systems demonstrated the feasibility of high intensity irradiation via bottom pressurized operation. An effective experimental characterization platform was developed and utilized in parallel with computational modeling efforts to further improve designs. A control strategy was also developed to provide a simple and robust means of remote target operation. Clinical production systems were designed and deployed at two facilities.

Stokely, Matthew Hughes

52

Design and Operating Characteristics of a Cryogenic Nitrogen Thermosyphon  

NASA Astrophysics Data System (ADS)

A two-phase nitrogen thermosyphon was developed in order to efficiently integrate a cryocooler into an insulated liquid nitrogen filled tank as part of a Protoflight Zero Boil-Off (ZBO) Development Ground Test. NASA Marshall Space Flight Center's (MSFC) Advanced Space Transportation Program supported this test to improve performance of in-space propulsion system concepts. Active cooling was integrated via a thermosyphon, made of copper, 1070 mm (42'') in length with an inner diameter of 11 mm (0.436''). It was charged with nitrogen to 1.55 MPa (225 PSIA) at 300 K which provided a fill ratio of 15%. The temperatures and heat flows through the thermosyphon were monitored during the start-up phase of the ZBO test and steady-state tests were conducted over a range of increasing and decreasing heat flows. The results showed that the performance of the thermosyphon exceeded expectations and had a thermal resistance of 0.2 K/W at a heat flow of 8.0 W. The design calculations also showed that the thermal resistance of a thermosyphon can be made relatively constant over a wider range of heat flows by making the ratio of evaporator area to condenser area 3:1.

Christie, R.; Robinson, D.; Plachta, D.

2004-06-01

53

Observations of complex oscillations in a closed thermosyphon  

NASA Technical Reports Server (NTRS)

Observations have been made of thermal oscillations in a slightly inclined closed thermosyphon. The thermosyphon is made up of two isothermal tubes, capped at the outer ends, and joined along their axes by an insulating section. The tube assembly is filled with liquid and inclined slightly with respect to the vertical. The lower isothermal section is hotter than the upper one and convection is driven across the insulating region. Between the applied temperature difference at which simple steady convection occurs, and that required for persistent turbulent motions, there is a wide range over which thermal oscillations are observed. These oscillations reflect quasi-periodic flows as well as a type of periodic chaos.

Hart, J. E.

1985-01-01

54

Thermosyphon Flooding in Reduced Gravity Environments Test Results  

NASA Technical Reports Server (NTRS)

The condenser flooding phenomenon associated with gravity aided two-phase thermosyphons was studied using parabolic flights to obtain the desired reduced gravity environment (RGE). The experiment was designed and built to test a total of twelve titanium water thermosyphons in multiple gravity environments with the goal of developing a model that would accurately explain the correlation between gravitational forces and the maximum axial heat transfer limit associated with condenser flooding. Results from laboratory testing and parabolic flights are included in this report as part I of a two part series. The data analysis and correlations are included in a follow on paper.

Gibson, Marc A.; Jaworske, Donald A.; Sanzi, Jim; Ljubanovic, Damir

2013-01-01

55

Application of silver nanofluid containing oleic acid surfactant in a thermosyphon economizer  

NASA Astrophysics Data System (ADS)

This article reports a recent study on the application of a two-phase closed thermosyphon (TPCT) in a thermosyphon for economizer (TPEC). The TPEC had three sections of equal size; the evaporator, the adiabatic section, and the condenser, of 250 mm × 250 mm × 250 mm ( W × L × H). The TPCT was a steel tube of 12.7-mm ID. The filling ratios chosen to study were 30, 50, and 80% with respect to the evaporator length. The volumetric flow rates for the coolant (in the condenser) were 1, 2.5, and 5 l/min. Five working fluids investigated were: water, water-based silver nanofluid with silver concentration 0.5 w/v%, and the nanofluid (NF) mixed with 0.5, 1, and 1.5 w/v% of oleic acid (OA). The operating temperatures were 60, 70, and 80°C. Experimental data showed that the TPEC gave the highest heat flux of about 25 kW/m2 and the highest effectiveness of about 0.3 at a filling ratio of 50%, with the nanofluid containing 1 w/v% of OA. It was further found that the effectiveness of nanofluid and the OA containing nanofluids were superior in effectiveness over water in all experimental conditions came under this study. Moreover, the presence of OA had clearly contributed to raise the effectiveness of the nanofluid.

Parametthanuwat, Thanya; Rittidech, Sampan; Pattiya, Adisak; Ding, Yulong; Witharana, Sanjeeva

2011-12-01

56

Application of silver nanofluid containing oleic acid surfactant in a thermosyphon economizer  

PubMed Central

This article reports a recent study on the application of a two-phase closed thermosyphon (TPCT) in a thermosyphon for economizer (TPEC). The TPEC had three sections of equal size; the evaporator, the adiabatic section, and the condenser, of 250 mm × 250 mm × 250 mm (W × L × H). The TPCT was a steel tube of 12.7-mm ID. The filling ratios chosen to study were 30, 50, and 80% with respect to the evaporator length. The volumetric flow rates for the coolant (in the condenser) were 1, 2.5, and 5 l/min. Five working fluids investigated were: water, water-based silver nanofluid with silver concentration 0.5 w/v%, and the nanofluid (NF) mixed with 0.5, 1, and 1.5 w/v% of oleic acid (OA). The operating temperatures were 60, 70, and 80°C. Experimental data showed that the TPEC gave the highest heat flux of about 25 kW/m2 and the highest effectiveness of about 0.3 at a filling ratio of 50%, with the nanofluid containing 1 w/v% of OA. It was further found that the effectiveness of nanofluid and the OA containing nanofluids were superior in effectiveness over water in all experimental conditions came under this study. Moreover, the presence of OA had clearly contributed to raise the effectiveness of the nanofluid.

2011-01-01

57

Thermal performance of closed two-phase thermosyphon using nanofluids  

Microsoft Academic Search

Nanofluids, stabilized suspensions of nanoparticles typically <100 nm in conventional fluids, are evolving as potential enhanced heat transfer fluids due to their improved thermal conductivity, increase in single phase heat transfer coefficient and significant increase in critical boiling heat flux. In the present paper, we investigate the overall thermal resistance of closed two-phase thermosyphon using pure water and various water

Sameer Khandekar; Yogesh M. Joshi; Balkrishna Mehta

2008-01-01

58

On periodic two-phase thermosyphons operating against gravity  

Microsoft Academic Search

Particular passive wickless two-phase loop devices are able to operate with or against gravity. In the past a lot of devices for miscellaneous applications have been proposed each of them with its characteristics. This paper aims to analyse different kinds of equipment as special versions of a generic thermal device that the author has named periodic two phase thermosyphon (PTPT).An

S. Filippeschi

2006-01-01

59

Farm Shop Thermo-Syphon Collector. Final Report.  

National Technical Information Service (NTIS)

The design and construction of a thermo-syphon solar collector are briefly described. The collector works on the principle of natural convection, and it was built to provide supplementary heat for a farm shop. A constant, above freezing temperature is the...

L. W. Storhaug

1985-01-01

60

Optimal design for a thermosyphon solar water heater  

Microsoft Academic Search

Through the use of TRNSYS, a transient simulation program, optimization of design parameters for a thermosyphon solar water heater was studied for two regions in Jordan represented by two cities, namely Amman and Aqaba. The optimum value of a parameter is defined as the value which maximizes the annual solar fraction of a system. This paper includes a good deal

Adnan Shariah; Bassam Shalabi

1997-01-01

61

Experimental study on thermosyphon solar water heater in Bahrain  

Microsoft Academic Search

The thermal performance of the thermosyphon water heater unit was analyzed to show its applicability in Bahrain, using data of several sunny, cloudy and hazy days in winter. The performance of this unit was studied under various maximum daily solar intensities, ranging from 1, 2 and 3 on a cloudy day, upto 695 W\\/m2 on a sunny day, with the

A. A Karaghouli; W. E Alnaser

2001-01-01

62

Investigation and Construction of a Thermosyphoning Solar Hot Water System  

ERIC Educational Resources Information Center

Describes how a thermosyphoning solar water heater capable of heating 110 kilogram of water to 80 degree Celsius and maintaining this temperature for 24 hours was constructed by four students in the fifth form of Sekolah Date Abdul Razak, Seremban, Malaysia in 1976. (HM)

Johnson, Harvey

1978-01-01

63

Performance and modeling of thermosyphon heat exchangers for solar water heaters  

Microsoft Academic Search

Determining the performance of indirect solar heating systems that use thermosyphon heat exchangers requires knowledge of how thermosyphon flow rate and heat exchanger performance vary with operating conditions. In this paper, measured performance of a two-pass, tube-in-shell, double-wall heat exchanger is discussed in terms of modeling issues. Thermosyphon heat exchangers may operate in the developing, mixed convection regime where natural

S. D. Dahl; J. H. Davidson

1997-01-01

64

Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon  

NASA Astrophysics Data System (ADS)

A two-phase loop thermosyphon transports thermal energy from a heat source to a heat sink by natural convective circulation under a body force field without any external power supply such as a pump. It is, therefore, thought that this could be applied to an energy-saving heat transportation system, and so forth. In practical use, an evaporator has several heated tubes and also the heat supplied to each of the heated tubes is not always equal. Therefore, the present study was performed both experimentally and theoretically on the flow and heat transfer characteristics in the two-phase loop thermosyphon installed with the evaporator with three heated tubes as a comparatively simple multi-tube evaporator in the lower part of the loop. The circulation mass flow rate, pressure and temperature distributions along the loop, as well as the heat transfer coefficients in the heated tubes were measured using water, ethanol and benzene, on which the effects of subcooling at the evaporator inlet and a heat input ratio of the three heated tubes were examined, and the experimental data were compared with the theoretically calculated results.

Imura, Hideaki; Takeshita, Kazuhiro; Horie, Yoshiatsu; Noda, Ken-Ichi

65

Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon  

NASA Astrophysics Data System (ADS)

A two-phase loop thermosyphon transports thermal energy by natural convective circulation without any external power supply. Therefore, it has been paid attention as a heat transfer equipment for saving energy. A basic investigation of flow and heat transfer characteristics in the thermosyphon was performed both experimentally and theoretically. The circulation flow rate, pressure and temperature distributions along the loop, and heat transfer coefficients in the heated section were measured using water, ethanol and Freon 113 as the working liquids. And, the effects of the heat input and liquid physical properties on the flow and heat transfer characteristics were examined. In the theoretical study, the circulation flow rate was calculated from the force balance between the driving force arising from density differences and the pressure drop in the loop. The comparison of the calculated with experimental results was made concerning the circulation flow rate and pressure and temperature distributions. For water and ethanol, the comparison presented the considerably close agreement. But, for Freon 113, the agreement was insufficient and further detailed investigation is needed.

Imura, Hideaki; Saito, Yuji; Katsumata, Yoshikazu

66

Thermosyphon coil arrangement for heat pump outdoor unit  

DOEpatents

For a heat pump, the outdoor unit is provided with a coil and a refrigerant flow arrangement therefor which is such that in the heating mode of operation of the heat pump they operate in a thermosyphon fashion. The coil 32 has a feed portion 30 and an exit portion 34 leading to a separator drum 36 from which liquid refrigerant is returned through downcomer line 42 for recirculation to the feed portion. The coil is tilted upwardly from entry to exit by the angle alpha to enhance the clearance of the two phases of refrigerant from each other in the heating mode of operation. There is no thermosyphon function in the cooling mode of operation.

Draper, Robert (Churchill, PA)

1984-01-01

67

Pressure drop in riser and evaporator in an advanced two-phase thermosyphon loop  

Microsoft Academic Search

This study presents an experimental investigation of pressure drop in the evaporators and the riser of an advanced thermosyphon loop. The thermosyphon was designed for the cooling of three parallel high heat flux electronic components. The tested evaporators were made from small blocks of copper in which 7, 5, 4, 3, 2, 1 vertical channels with the diameters of 1.1,

Rahmatollah Khodabandeh

2005-01-01

68

Two-Phase Closed-Loop Thermosyphon for Electronic Cooling  

Microsoft Academic Search

This study experimentally investigated the thermal performance of a two-phase closed-loop thermosyphon with a thermal resistance model for electronic cooling. The evaporator, rising tube, condenser, and falling tube, which are the four main devices, formed a closed-loop system with water as the working fluid. The experimental parameters were the evaporator surface type, fill ratio of working fluid, and input heating

C.-C. Chang; S.-C. Kuo; M.-T. Ke; S.-L. Chen

2010-01-01

69

Performance rating method of thermosyphon solar water heaters  

Microsoft Academic Search

A rating method for the thermal performance of thermosyphon solar water heaters was developed. Except that the outdoor test procedure still follows the Taiwan Standard CNS B7277, a system characteristic efficiency [eta][sub s]* which is defined as the [alpha][sub o], value corrected at M\\/A[sub c]= 75 kg\\/m[sup 2], was derived so that [eta][sub s]* is independent of the M\\/A, ratio.

B HUANG

1993-01-01

70

Determination of the operation range of a vertical two-phase closed thermosyphon  

NASA Astrophysics Data System (ADS)

A comprehensive model, proposed for a vertical two-phase closed thermosyphon (TPCT) by the present authors, is further developed by utilizing the criteria for dryout, flooding and boiling limits to investigate the effects of filling ratio on them together, while the available models can just consider one or two limits of them. A new concept named dryout ratio is proposed, which can be used for predicting dryout limit. The empirical correlation and the empirical value, provided by other researchers, are used for predicting flooding and boiling limit, respectively. The experiments with nitrogen as working fluid are performed, and compared with the calculations. The maximum filling ratio is introduced, beyond which the liquid could be carried to condenser and the heat transfer performance can be deteriorated. And then the closed operation range of a vertical TPCT is finally determined, which has not been reported before. The effects of operating pressure and geometries on the range are also analyzed.

Jiao, B.; Qiu, L. M.; Gan, Z. H.; Zhang, X. B.

2012-06-01

71

Flow and Heat Transfer Characteristics in a Closed-Type Two-Phase Loop Thermosyphon  

NASA Astrophysics Data System (ADS)

A closed-loop two-phase thermosyphon can transport a large amount of thermal energy with small temperature differences without any external power supply. A fundamental investigation of flow and heat transfer characteristics was performed experimentally and theoretically using water, ethanol and R113 as the working liquids. Heat transfer coefficients in an evaporator and a condenser, and circulation flow rates were measured experimentally. The effects of liquid fill charge, rotation angle, pressure in the loop and heat flux on the heat transfer coefficients were examined. The heat transfer coefficients in the evaporator and the condenser were correlated by the expressions for pool boiling and film condensation respectively. As a result, the heat transfer coefficients in the evaporator were correlated by the Stephan-Abdelsalam equations within a±40% error. Theoretically, the circulation flow rate was predicted by calculating pressure, temperature, quality and void fraction along the loop. And, the comparison between the calculated and experimental results was made.

Imura, Hideaki; Saito, Yuji; Fujimoto, Hiromitsu

72

Analysis of thermosyphoning in a steam generator model  

SciTech Connect

An analysis of thermosyphoning in a stream generator model is presented. The model considers the transient development of buoyancy-driven steam flow in the steam generator tubing, secondary side heat transfer and an inlet plenum mixing model. Numerical solutions are obtained for conditions intended to simulate the natural circulation phenomena in a 3-Loop pressurized water reactor in a loss-of-coolant accident scenario. The relation between the circulation rate and the heating rate is determined. The sensitivity of the model to various key parameters is examined. 16 refs.

Martinez, M.J.; Martinez, G.M.

1991-10-01

73

Laminar flow modelling of a thermosyphon loop at specified wall temperatures  

NASA Astrophysics Data System (ADS)

A thermosyphon loop is analyzed in this study by use of numerical and experimental techniques. A rectangular loop was constructed using copper pipe and the sections which were heated or cooled were designed as concentric tube heat exchangers. Hot or cold water was circulated outside of these sections, and both the surface temperatures and heat transferred to and from the loop were measured. Within the numerical study both the momentum and energy equations were also solved using a SIMPLEX algorithm. Numerical results were obtained for laminar flow within the circuit when there was uniform wall temperature in the vertically heated and cooled sections of the thermosyphon. The two-dimensional numerical model provided results which agree with those found experimentally from the thermosyphon loop. In addition, a simulation model was constructed using a correlation included both the Grashof and Prandtl numbers to evaluate heat transfer through a thermosyphon loop.

Küçüka, Serhan; Ba?aran, Tahsin

2007-10-01

74

A parametric study of heat transfer within a planar thermosyphon  

SciTech Connect

The results of a parametric study for a planar thermosyphon are presented. The thermosyphon consists of a ``U-shaped`` geometry, with the center portion of the ``U`` being a solid. The outer legs of the ``U`` are the flow channels. One of the outer surfaces of a channel was held at a constant temperature. The remaining outer surfaces were considered adiabatic. The configuration described is characteristic of passive systems for radioactive waste storage and reactor safety systems. Parameters which were varied included the channel geometry, the thermal conductivity of the solid, and the Ra number. The average Nu number for the constant temperature surface decreased as the inlet channel width decreased, and as the thermal conductivity of the solid increased. A modified Ra number, defined as the Ra number divided by the length to gap ratio for the outer channel, is used in the paper. At low values of the modified Ra number, there is over an order of magnitude decrease in the average Vu number for a change in the inlet channel width from 1.0 to 0.25. But as the value of the modified Ra number increases for any inlet channel width, the average Vu number results approached those of vertical parallel plates, independent of the inlet channel width and the thermal conductivity of the solid. The vertical parallel plate data is approached because the boundary layer flow near the heated plate is unaffected by the surface of the intervening solid.

Clarksean, R.; Phillips, G.

1993-08-01

75

The liquid helium thermosyphon for the GEM detector magnet  

SciTech Connect

The GEM detector magnet, a horizontal solenoid 19.5 m in diameter and wound with a niobium-titanium cable in conduit, will be located with it`s axis 19.5 m below grade. The conductor is wound on the inside of an aluminum bobbin which is cooled by liquid helium which flows by natural convection in a thermosyphon loop from a large storage dewar located at the ground surface. The function of the thermosyphon system is to absorb the environmental heat load as well as any internally generated heat. In the first category is included that heat which is transfered to the magnet by way of the mechanical supports, the insulation and the current leads. The internally generated heat includes the resistive heating within the normally conducting conductor splices and the inductive heating of the bobbin during current transients. Though similar systems have been employed elsewhere, there are some unique aspects to the present design. By taking advantage of the large vertical head available, the parallel heat exchanger passes within the magnet remain sub-cooled, thus insuring single phase coolant within the magnet. It is believed that this will be the first instance of such a large vertical head being used to this advantage in a helium system.

Warren, R.P.

1993-05-04

76

Influence of volume working fluid and ambient temperature on cooling efficiency of loop thermosyphon  

NASA Astrophysics Data System (ADS)

Article deal with research of device for electrical component cooling used to heat transfer working fluid phase change. Amount of heat flux transferred by thermosyphon loop depend from amount working fluid and from ambient temperature where is heat removal too. In article is described proposal construction of thermosyphon loop, comparisons of his cooling efficiency if is filled 40 % and 50 % volume of working fluid and condenser (ambient) temperature from 20, 30 up to 40 °C at heat load from 40 to 360 W.

Nemec, P.; Malcho, M.; Janda?ka, J.; Matušov, J.

2014-03-01

77

Thermal performance analysis of nanofluids in a thermosyphon heat pipe using CFD modeling  

NASA Astrophysics Data System (ADS)

A computational fluid dynamics model for simulation of a thermosyphon with two-phase flow including phase change heat transfer was developed. De-ionized water and CuO/Water nanofluid were used as working fluids in the thermosyphon. Results show that, maximum heat flux of the nanofluid is about 46 % higher than that of water. Also by increasing the nanofluid concentration, the wall temperature decreases, and the concentration of 1 wt% is the optimum concentration.

Asmaie, L.; Haghshenasfard, M.; Mehrabani-Zeinabad, A.; Nasr Esfahany, M.

2013-05-01

78

Theoretical Design of Thermosyphon for Process Heat Transfer from NGNP to Hydrogen Plant  

SciTech Connect

The Next Generation Nuclear Plant (NGNP) will most likely produce electricity and process heat, with both being considered for hydrogen production. To capture nuclear process heat, and transport it to a distant industrial facility requires a high temperature system of heat exchangers, pumps and/or compressors. The heat transfer system is particularly challenging not only due to the elevated temperatures (up to ~ 1300K) and industrial scale power transport (=50 MW), but also due to a potentially large separation distance between the nuclear and industrial plants (100+m) dictated by safety and licensing mandates. The work reported here is the preliminary analysis of two-phase thermosyphon heat transfer performance with alkali metals. A thermosyphon is a device for transporting heat from one point to another with quite extraordinary properties. In contrast to single-phased forced convective heat transfer via ‘pumping a fluid’, a thermosyphon (also called a wickless heat pipe) transfers heat through the vaporization / condensing process. The condensate is further returned to the hot source by gravity, i.e. without any requirement of pumps or compressors. With this mode of heat transfer, the thermosyphon has the capability to transport heat at high rates over appreciable distances, virtually isothermally and without any requirement for external pumping devices. Two-phase heat transfer by a thermosyphon has the advantage of high enthalpy transport that includes the sensible heat of the liquid, the latent heat of vaporization, and vapor superheat. In contrast, single-phase forced convection transports only the sensible heat of the fluid. Additionally, vapor-phase velocities within a thermosyphon are much greater than single-phase liquid velocities within a forced convective loop. Thermosyphon performance can be limited by the sonic limit (choking) or vapor flow and/or by condensate entrainment. Proper thermosyphon requires analysis of both.

Piyush Sabharwall; Mike Patterson; Fred Gunnerson

2008-09-01

79

Thermosyphon installation for energy thrift in a smoked fish sausage oven (TISO)  

Microsoft Academic Search

This research presents a case study of applying a thermosyphon for energy conservation in a smoked fish sausage oven. An oven with the size of 1.5 m × 1.5 m × 1.7 m (width × length × height) was installed with a thermosyphon made up of 304 stainless steel (AISI 304) tubes with 25.4 mm ID to improve temperature distribution, decrease processing time and reduce LPG consumption. The lengths of the evaporator

T. Parametthanuwat; S. Rittidech; K. Booddachan

2010-01-01

80

Visualization of Flow Pattern in Thermosyphon by ECT  

NASA Astrophysics Data System (ADS)

An investigation on the visualization of the flow of the liquid in a two-phase closed thermosyphon (TPCT) is carried out. Electrical capacitance tomography (ECT) with optimal step lengths for iterative image reconstruction algorithm is applied in the study. Measurements are made under a range of heating rates of the TPCT. As against the common assumption of ``low spatial resolution of ECT'', the experimental results have demonstrated ECT's capability of reconstructing images of thin films on the order of 100 ?m in thickness. Results for film thickness by ECT are compared with the established theory. Agreements and discrepancies are observed among the reconstructed images corresponding to difference thresholds. ECT images of the liquid distributions in the TPCT show clear dependence on the variation of working conditions, which proves the potential of ECT as an advantageous technique for monitoring the operation of TPCT.

Liu, Shi; Li, Jingtao; Chen, Qi

2007-06-01

81

Fuzzy model representation of thermosyphon solar water heating system  

SciTech Connect

The aim of this paper is to focus on improvement in prediction accuracy of model for thermosyphon solar water heating (SWH) system. The work employs grey-box modeling approach based on fuzzy system to predict the outlet water temperature of the said system. The prediction performance results are compared with neural network technique, which has been suggested by various researchers in the last one decade. The outlet water temperature prediction by fuzzy modeling technique is analyzed by using 3 models, one with three inputs (inlet water temperature, ambient temperature, solar irradiance), next with two inputs (inlet water temperature, solar irradiance) and last one with single input (solar irradiance/inlet water temperature). An improved prediction performance is observed with three inputs fuzzy model. (author)

Kishor, Nand; Narain, Anirudha; Prakash Ranjan, Vibhaw [Department of Electrical Engineering, Motilal Nehru National Institute of Technology, Allahabad (India); Das, Mihir Kr. [Indian Institute of Technology Bhubaneswar (India)

2010-06-15

82

Impact of cooling condition and filling ratio on heat transfer limit of cryogenic thermosyphon  

NASA Astrophysics Data System (ADS)

In this study, the heat transfer limits of two cryogenic thermosyphons with different cooling conditions and filling ratios are experimentally studied and discussed. The cryogenic thermosyphons are fabricated with the same inner structures and their heat transfer performances are tested. The heat transfer limit of the cryogenic thermosyphon can reach 180.0 W through improving the cooling condition at moderate filling ratios. Meanwhile, it is found that the dry-out limit occurs not only at low filling ratios, but also at high filling ratios in the case of poor cooling condition. The mechanism behind the dry-out limit at high filling ratios is analyzed and the critical heat flux is predicted by a model that describes the heat and mass balance of the working fluid. A fluctuating period is observed in the vicinity of the boiling limit, and the critical heat flux corresponding to the boiling limit is predicted by an empirical correlation.

Long, Z. Q.; Zhang, P.

2012-01-01

83

Verified accurate performance simulation model of direct thermosyphon solar energy water heaters  

SciTech Connect

A detailed analysis of the heat transfers and fluid flows within direct thermosyphonic solar energy water heaters has been undertaken. The collector energy equations were cast in a two-dimensional form in order that the heat transfer and thermal capacitance effects can be simulated accurately at the small flow rates encountered commonly in these buoyancy-driven systems. The use of an appropriate nonisothermal friction factor correlation when calculating energy losses in the collector's riser pipes, produced predicted flow rates which were corroborated to within 2 percent by the values measured under steady flow conditions. For the laminar flow rates and the store configuration investigated, relaxation of the thermocline was shown to be dominated by axial conduction in the store walls. An indoor test facility, monitored and controlled by a microcomputer, enabled ''real'' operating conditions to be simulated. The predicted responses of the system to identical conditions showed good agreement with the corresponding experimental observations, the predicted heat delivery being within 2.8 percent of that measured.

Hobson, P.A.; Norton, B.

1988-11-01

84

Engineering design elements of a two-phase thermosyphon to transfer nuclear thermal energy to a hydrogen plant  

NASA Astrophysics Data System (ADS)

Two hydrogen production processes, both powered by Next Generation Nuclear Plant (NGNP), are currently under investigation at the Idaho National Laboratory. The first is high-temperature steam electrolysis utilizing both heat and electricity and the second is thermo-chemical production through the sulfur-iodine process primarily utilizing heat. Both processes require high temperature (>850°C) for enhanced efficiency; temperatures indicative of NGNP. Safety and licensing mandates prudently dictate that the NGNP and the hydrogen production facility be physically isolated, perhaps requiring separation of over 100m. There are several options to transferring multi-megawatt thermal power over such a distance. One option is simply to produce only electricity, transfer by wire to the hydrogen plant, and then reconvert the electric energy to heat via Joule or induction heating. Electrical transport, however, suffers energy losses of 60-70% due to the thermal to electric conversion inherent in the Brayton cycle. A second option is thermal energy transport via a single-phase forced convection loop where a fluid is mechanically pumped between heat exchangers at the nuclear and hydrogen plants. High temperatures, however, present unique materials and pumping challenges. Single phase, low pressure helium is an attractive option for NGNP, but is not suitable for a single purpose facility dictated to hydrogen production because low pressure helium requires higher pumping power and makes the process very inefficient. A third option is two-phase heat transfer utilizing a high temperature thermosyphon. Heat transport occurs via evaporation and condensation, and the heat transport fluid is re-circulated by gravitational force. Thermosyphon has the capability to transport heat at high rates over appreciable distances, virtually isothermally and without any requirement for external pumping devices. For process heat, intermediate heat exchangers (IHX) are desired to transfer heat from the NGNP to the hydrogen plant in the most efficient way possible. The production of power at higher efficiency using Brayton Cycle, and hydrogen production requires both heat at higher temperatures (up to 1000°C) and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. The purpose in selecting a compact heat exchanger is to maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. The IHX design requirements are governed by the allowable temperature drop between the outlet of the NGNP (900°C, based on the current capabilities of NGNP), and the temperatures in the hydrogen production plant. Spiral Heat Exchangers (SHEs) have superior heat transfer characteristics, and are less susceptible to fouling. Further, heat losses to surroundings are minimized because of its compact configuration. SHEs have never been examined for phase-change heat transfer applications. The research presented provides useful information for thermosyphon design and Spiral Heat Exchanger. This research provides useful insight in making decisions regarding the thermosyphon heat transfer system between the nuclear reactor and chemical plant. Development of very high-temperature reactor technologies for the production of electricity, hydrogen and other energy products is a high priority for a successful national energy future.

Sabharwall, Piyush

85

Development, testing and certification of the sigma research, maxi-therm-S-101 thermosyphon heat exchanger  

NASA Technical Reports Server (NTRS)

A thermosyphon liquid-to-air heat exchanger developed for use in heating systems in residential single family dwellings and small commercial applications is described. The cabinet design, rationale for the horizontal positioning of the exchanger, and design of the shut-off valve are discussed. The performance of the heating module is given in tabular form.

Hankins, J. D.

1979-01-01

86

Simulation aided design of a two-phase thermosyphon for power electronics cooling  

Microsoft Academic Search

In this paper we present a novel system for power electronics cooling consisting of a thermosyphon loop composed of an evaporator, to which the power modules are attached, and of a condenser, formed by a set of vertically mounted aluminum panels. To facilitate the optimization of the design of the condenser, which is critical for the whole system performance, we

Francesco Agostini; Thomas Gradinger; Carlo de Falco

2011-01-01

87

Experimental Study on Closed-Loop Two-Phase Thermosyphon Devices for Cooling MCMs  

Microsoft Academic Search

Thermosyphon cooling modules, to cool multichip modules (MCMs), were designed and tested. The cooling module consists of a cold plate with microfinned channels and a plate-type integrated condenser. A separate flow model was employed to predict the mass flux and the pressure drop in the channel of the cold plate. The local and average convective boiling heat transfer coefficients and

2001-01-01

88

A simple device for monitoring flow rates in thermosyphon solar water heaters  

Microsoft Academic Search

Direct measurements of fluid flow rates in thermosyphon solar water heaters in the field are difficult. This paper reports on an activity to develop, calibrate, and evaluate a simple device for such measurements. A suitable device should have the following general characteristics: low pressure drop, rugged, inexpensive, simple, nondistruptive, low power requirements, and reasonably accurate. Moderate success has been achieved

Richard B. Bannerot; Yi-Wey Tu; Allen Scott; George Placke; Tom Poche?

1992-01-01

89

Transient investigation of a two phase closed thermosyphon flat plate solar water heater  

Microsoft Academic Search

This work presents an unsteady state theoretical and experimental investigation of natural circulation two phase closed thermosyphon flat plate solar water heaters. The governing equations of the heater storage tank and connecting pipes are presented and generalized in dimensionless form, while the governing equations of the different components of the collector were previously discussed by the author. Also, the author's

H. M. S. Hussein

2002-01-01

90

A design nomogram for direct thermosyphon solar-energy water heaters  

Microsoft Academic Search

A characteristic curve for an individual directly heated thermosyphon solar-energy water heater, when obtained from data of an appropriately chosen test period of 30 days, has been shown to predict the annual solar fraction to within 3% of the corresponding value obtained from a validated numerical simulation model. An extension of this analysis produces two underlying correlations of five dimensionless

P. A. Hobson; B. Norton

1989-01-01

91

Theoretical and experimental investigations of a two-phase thermosyphon solar water heater  

Microsoft Academic Search

This article experimentally and theoretically investigates a two-phase thermosyphon solar water heater. The performance of this innovative solar water heater at different solar radiation intensities and tilt angles are experimentally discussed. The results show the best charge efficiency of the system is 82%, which is higher than the conventional solar water heaters. The theoretical model is also developed using the

C. C. Chien; C. K. Kung; C. C. Chang; W. S. Lee; C. S. Jwo; S. L. Chen

2011-01-01

92

Passively operated spool valve for drain-down freeze protection of thermosyphon water heaters. Final technical report  

SciTech Connect

The work done to extend the existing drain-down valve technology to provide passive drain-down freeze protection for thermosyphon-based solar water heaters is described. The basic design of the existing valve model is that of a spool valve, employing a cylindrical spool which moves axially in a mating cartridge to open and close o-rings at the two operating extremes (drain and operate) to perform the valving function. Three passive actuators to drive the basic valving mechanism were designed, fabricated, and tested. Two piping configurations used to integrate the spool valve with the thermosyphon system are described, as are the passive actuators. The three actuator designs are: photovoltaic driven, refrigerant-based bellows, and heat motor cable-drive designs. Costs are compared for the alternative actuator designs, and operating characteristics were examined for the thermosyphon system, including field tests. The market for the valve for thermosyphon systems is then assessed. (LEW)

None

1982-04-30

93

A reduced-order partial differential equation model for the flow in a thermosyphon  

NASA Astrophysics Data System (ADS)

Flow in a closed-loop thermosyphon heated from below exhibits a sequence of bifurcations with increasing Grashof number. Using the Navier Stokes equations in the Boussinesq approximation we have derived a model where, in the case of a slender circular loop, the first Fourier modes exactly decouple from all other Fourier modes, leaving a system of three coupled nonlinear partial differential equations that completely describes the flow in the thermosyphon. We have characterized the flow through two bifurcations, identifying stable periodic solutions for flows of Prandtl number greater than 18.5, a much lower value than predicted previously. Because of the quadratic nonlinearity in this system of equations, it is possible to find the global stability limit, and we have proved that it is identical to the first bifurcation point.

Burroughs, E. A.; Coutsias, E. A.; Romero, L. A.

2005-10-01

94

Performance evaluation of a refrigerant-charged thermosyphon solar DHW system  

SciTech Connect

Refrigerant-charged passive solar domestic hot water (SDHW) systems, which have recently become commercially available, are generating great interest in the solar community. These systems, which can be installed even in freezing climates, may achieve the high performance and reliability of direct thermosyphon systems. The Solar Energy Research Institute (SERI) is testing and analyzing a promixing prototype refrigerant-charged thermosyphon system; SERI also plans to evaluate a commercially available system. The prototype was installed in a single-family residence using a stabilized R-11 as the heat transfer fluid. A system analysis was performed based on measured data. The analysis method and preliminary results, which indicate that there is reason to be optimistic about this type of system are discussed.

Farrington, R.; DeAngelis, M.; Morrison, L.; Dougherty, D.

1981-04-01

95

A design nomogram for direct thermosyphon solar-energy water heaters  

SciTech Connect

A characteristic curve for an individual directly heated thermosyphon solar-energy water heater, when obtained from data of an appropriately chosen test period of 30 days, has been shown to predict the annual solar fraction to within 3% of the corresponding value obtained from a validated numerical simulation model. An extension of this analysis produces two underlying correlations of five dimensionless groups from which the performances of a wide range of thermosyphon solar-energy water heaters with varying thermal loads can be predicted. The estimated uncertainty of this design technique in predicting an annual solar fraction ranges from 8% for multiple-pass systems to 13% for same level, single-pass systems.

Hobson, P.A. (AFRC Institute of Engineering Research, Silsoe, Bedford (England)); Norton, B. (Univ. of Ulster (Ireland))

1989-01-01

96

Thermal Interface Evaluation of Heat Transfer from a Pumped Loop to Titanium-Water Thermosyphons  

NASA Technical Reports Server (NTRS)

Titanium-water thermosyphons are being considered for use in the heat rejection system for lunar outpost fission surface power. Key to their use is heat transfer between a closed loop heat source and the heat pipe evaporators. This work describes laboratory testing of several interfaces that were evaluated for their thermal performance characteristics, in the temperature range of 350 to 400 K, utilizing a water closed loop heat source and multiple thermosyphon evaporator geometries. A gas gap calorimeter was used to measure heat flow at steady state. Thermocouples in the closed loop heat source and on the evaporator were used to measure thermal conductance. The interfaces were in two generic categories, those immersed in the water closed loop heat source and those clamped to the water closed loop heat source with differing thermal conductive agents. In general, immersed evaporators showed better overall performance than their clamped counterparts. Selected clamped evaporator geometries offered promise.

Jaworske, Donald A.; Sanzi, James L.; Gibson, Marc A.; Sechkar, Edward A.

2009-01-01

97

Modeling analysis of bubble flow regime in a closed two-phase thermosyphon  

NASA Astrophysics Data System (ADS)

Predictions of the operating liquid level in the evaporator of a closed two-phase thermosyphon (gravity heat pipe) are given throughout a simplified analysis which takes the influence of the dimension and condensation heat transfer in the condenser of the heat pipe into account. In order to verify the accuracy of our model comparison of the present study with some published results is made by means of computational examples.

Tang, Zhi-Wei; Han, Ya-Fang; Liu, Ai-Jie; Song, Wei-Gang

2011-12-01

98

Closed Loop Two-Phase Thermosyphon of Small Dimensions: a Review of the Experimental Results  

Microsoft Academic Search

A bibliographical review on the heat and mass transfer in gravity assisted Closed Loop Two Phase Thermosyphons (CLTPT) with\\u000a channels having a hydraulic diameter of the order of some millimetres and input power below 1 kW is proposed. The available\\u000a experimental works in the literature are critically analysed in order to highlight the main results and the correlation between\\u000a mass flow

Alessandro Franco; Sauro Filippeschi

99

Modeling of reflux condensation and countercurrent annular flow in a two-phase closed thermosyphon  

Microsoft Academic Search

Reflux condensation in the steam generator tubes of a PWR is a potentially important heat removal mechanism during the cool-down phase following a small-break LOCA. This work studies reflux condensation using the two-phase closed thermosyphon as a model system. An analytical model based on control-volume formulations of mass, momentum, and energy balances for the liquid and vapor flows in each

J. G. Reed; C. L. Tien

1985-01-01

100

Economic evaluation of latent heat thermal energy storage using embedded thermosyphons for concentrating solar power applications  

Microsoft Academic Search

An economic evaluation of a latent heat thermal energy storage (LHTES) system for large scale concentrating solar power (CSP) applications is conducted. The concept of embedding gravity-assisted wickless heat pipes (thermosyphons) within a commercial-scale LHTES system is explored through use of a thermal network model. A new design is proposed for charging and discharging a large-scale LHTES system. The size

Christopher W. Robak; Theodore L. Bergman; Amir Faghri

2011-01-01

101

Performance of stationary and vibrated thermosyphon working with water and R134a  

Microsoft Academic Search

An experimental apparatus of a two-phase closed thermosyphon has been designed and constructed to predict its performance characteristics under stationary and vibrated conditions. Water and R134a are used as working fluids. Experiments are carried out over wide ranges of liquid fill ratio (0.4, 0.5, 0.6 and 0.8), length of adiabatic section (275, 325 and 350 mm), vibration frequency (0.0–4.33 Hz)

H. Z Abou-Ziyan; A Helali; M Fatouh; M. M. Abo El-Nasr

2001-01-01

102

Performance evaluation of a refrigerant-charged thermosyphon solar DHW system  

NASA Astrophysics Data System (ADS)

Refrigerant-charged passive solar domestic hot water (SDHW) systems, which can be installed even in freezing climates, may achieve the high performance and reliability of direct thermosyphon systems. The prototype was installed in a single-family residence using a stabilized R-11 as the heat transfer fluid. A system analysis was performed based on measured data. The analysis method and preliminary results, which indicate that there is reason to be optimistic about this type of system are discussed.

Farrington, R.; Deangelis, M.; Morrison, L.; Dougherty, D.

1981-04-01

103

Experimental investigation of a two-phase closed thermosyphon solar water heater  

Microsoft Academic Search

In this study, experiments were performed to find out how the thermal performance of a two-phase thermosyphon solar collector was affected by using different refrigerants. Three identical small-scale solar water heating systems, using refrigerants R-134a, R407C, and R410A, were constructed and tested side-by-side under various environmental and load conditions. The performance of the system under clear-sky conditions has been investigated

Mehmet Esen; Hikmet Esen

2005-01-01

104

Experimental study of critical heat flux in open two-phase thermosyphon  

Microsoft Academic Search

Critical heat flux in an open two-phase thermosyphon has been measured employing water, R113 and R22 for a wide range of L\\/D=4.8 to 960 and density ratio of A L\\/A G=6.17 to 1602. The CHF data measured, are found to be in fairly good agreement with those calculated from a criterion that the CHF takes place when reaches a maximum

M. Monde; S. Mihara; Y. Mitsutake

1996-01-01

105

Computer cooling using a two phase minichannel thermosyphon loop heated from horizontal and vertical sides and cooled from vertical side  

NASA Astrophysics Data System (ADS)

In the present paper it is proposed to consider the computer cooling capacity using the thermosyphon loop. A closed thermosyphon loop consists of combined two heaters and a cooler connected to each other by tubes. The first heater may be a CPU processor located on the motherboard of the personal computer. The second heater may be a chip of a graphic card placed perpendicular to the motherboard of personal computer. The cooler can be placed above the heaters on the computer chassis. The thermosyphon cooling system on the use of computer can be modeled using the rectangular thermosyphon loop with minichannels heated at the bottom horizontal side and the bottom vertical side and cooled at the upper vertical side. The riser and a downcomer connect these parts. A one-dimensional model of two-phase flow and heat transfer in a closed thermosyphon loop is based on mass, momentum, and energy balances in the evaporators, rising tube, condenser and the falling tube. The separate two-phase flow model is used in calculations. A numerical investigation for the analysis of the mass flux rate and heat transfer coefficient in the steady state has been accomplished.

Bieli?ski, Henryk; Mikielewicz, Jaros?aw

2010-10-01

106

Passively Operated Spool Valve for Drain-down Freeze Protection of Thermosyphon Water Heaters. Final Technical Report.  

National Technical Information Service (NTIS)

The work done to extend the existing drain-down valve technology to provide passive drain-down freeze protection for thermosyphon-based solar water heaters is described. The basic design of the existing valve model is that of a spool valve, employing a cy...

1982-01-01

107

A DIGITAL COMPUTER ANALYSIS OF CLOSED CYCLE WATER NICLEAR POWER PLANT START UP USING NATURAL CIRCULATION. (THERMOSYPHON CODE). VOLUME II  

Microsoft Academic Search

Input data forms, FORTRAN source program listings, and output data sheet ; samples are presented for the Thermo-Syphon code which analyzes the closed-cycle ; water nuclear power plant startup using natural circulation. The code is ; analyzed on an IBM 7090 digital computer. (N.W.R.);

A. N. Nahavandi; B. H. Axelson; G. B. Killinger; A. H. Killinger

1962-01-01

108

Design and testing of thermosyphon batch targets for production of fluorine-18  

NASA Astrophysics Data System (ADS)

18F is a short-lived radioisotope commonly used in Positron Emission Tomography (PET). This radionuclide is typically produced through the 18O(p,n)18 F reaction by proton bombardment of 18O-enriched water. Thermosyphon batch targets have been proposed as a means to increase 18F production due to their enhanced heat rejection capabilities. These boiling targets have been operated with up to 3.2 kW of beam power with manageable 18O enriched water volumes. The primary purpose of this work has been to develop a fundamental approach to target design from a modeling perspective, and to implement this approach to design new thermosyphon targets with enhanced production capabilities. Computational methods have been developed to predict target thermal performance and have been validated with experimental test data from the Duke University Medical Cyclotron and the Wisconsin Medical Cyclotron. These methods have been used to design a new production target for the Duke cyclotron with enhanced 18F production capabilities. Low volume test targets have been successfully operated at the Wisconsin cyclotron with beam powers in excess of the desired 1.6 kW.

Peeples, Johanna Louise

109

Thermal-Hydraulic Mockup Tests with Two-Phase Thermosyphon for Cold Neutron Source  

SciTech Connect

The improvement and utilization promotion project of the Taiwan Research Reactor (TRR-II) is carrying out at the Institute of Nuclear Energy Research (INER). The Cold Neutron Source (CNS) with a two-phase thermosyphon will be installed in the heavy water reactor of TRR-II. The hydrogen cold loop of TRR-II CNS consists of a cylindrical moderator cell, a single transfer tube, and a condenser. The thermal-hydraulic characteristics of a two-phase thermosyphon are investigated against the variations of mass inventory, tube geometry and heat loads. The thermal-hydraulic experiments have been performed using a full-scale mockup loop and a Freon-11 as a working fluid. The scaling approach is that the mass-fluxes of the liquid and the vapor in the Wallis correlation are identical between hydrogen and Freon-11. So, the same density ratio and a scaling heat load are applied to the loop. The flooding limitations as a function of initial Freon-11 inventory, transfer tube diameter, transfer tube geometry, and heat loads are presented. (authors)

Lee, C.H.; Chan, Y.K.; Lee, D.J.; Chang, C.J. [Institute of Nuclear Energy Research, P. O. Box 3-3, LungTan 32500, Taiwan (China); Hong, W.T. [Gengood Engineering Corporation, No 36, Lane 362, Min-Sheng W. Road, Taipei, Taiwan 104 (China)

2002-07-01

110

Experimental study of complex two-phase instabilities during the start-up of a vertical thermosyphon reboiler operating under vacuum  

Microsoft Academic Search

This paper reports experimental studies of the start-up at reduced pressures (0.105–0.171bar) and low heat fluxes (1.23–1.55kWm?2) of the thermosyphon reboiler research facility in the Morton Laboratory at the University of Manchester. This is a full scale replica of an industrial sized natural circulation thermosyphon reboiler comprising 50 vertically mounted 25mm OD tubes of 3m length with water as the

Abdelmadjid Alane; Peter J. Heggs

2011-01-01

111

Electrical capacitance tomography measurement of flow patterns and film thickness in a thermosyphon  

NASA Astrophysics Data System (ADS)

An experimental study was performed to evaluate the suitability of using an electrical capacitance tomography (ECT) system to visualize the flow patterns, and to measure the film thickness of the annular flow in a two-phase closed thermosyphon (TPCT). The performance of the ECT system was examined over a range of flow conditions. The experimental data were compared with the visual observations and existing correlations. Results indicated that the ECT system, with the linear back projection (LBP) algorithm, could be used to give an on-line qualitative image of the flow patterns. The Landweber iteration algorithm with optimal step length was implemented off-line to reconstruct high-resolution images. Then, the images were analyzed to obtain the film thickness of the annular flow. The experimental data compared well with the Nusselt’s equation in low vapor velocity range, but showed an increasing deficiency with the increase of vapor velocity.

Li, Jingtao; Chen, Qi; Dong, Xiangyuan; Liu, Shi

2005-03-01

112

Non-Isothermal Experimental Study of the Constrained Vapor Bubble Thermosyphon  

NASA Technical Reports Server (NTRS)

Experimental and theoretical techniques to study non-isothermal transport processes in the constrained vapor bubble thermosyphon (CVBT) were developed using a pentane/quartz system. The transport processes can be evaluated by measuring the liquid film profile, which gives the pressure field, and the temperature field. The axial variation in the capillary pressure was measured using an image-analyzing interferometer that is based on computer-enhanced video microscopy of the naturally occurring interference fringes. Thermoelectric coolers were used to control the temperature level in the condensation region and, therefore, the length of the approximately 'adiabatic' surface region which is a function of the temperature difference between the CVBT surface and the surroundings. High values for the axial thermal conductance in the 'adiabatic' surface region were demonstrated under certain conditions.

Karthikeyan, Muthu; Huang, Jianming; Plawsky, Joel; Wayner, Peter, Jr.

1996-01-01

113

Site-specific economic analysis of solar thermosyphon domestic hot water systems  

SciTech Connect

A market analysis and economic assessment has been conducted for solar thermosyphon domestic hot water (STDHW) systems. For the continental United States, a specific procedure was followed using current information in the public domain to select three sites with potentially viable markets for the STDHW systems. Following this, a technique was developed and applied to each of the sites to determine the required cost/performance boundary conditions for economic viability of the solar systems versus available conventional systems. The technique developed allows the user to input any site- and system-specific parameters required and to choose from any or all of the three different economic assessment methods combined into a single nomography. The technique is thus repeatable for any system, any site.

Coleman, G.B.; Ford, K.E.

1982-01-01

114

An experimental study of a two-phase closed loop thermosyphon with dual evaporator in parallel arrangement  

Microsoft Academic Search

A Two-phase Closed Loop Thermosyphon(TCLT) has been applied to many industrial fields as a waste heat recovery system, a telecommunication cooling system and other\\u000a heat transport devices for the last 2 decades. It is common to design aTCL T to consist of one evaporator, one condenser and 2 separated lines of condensate liquid and vapor of working fluid. The present

Chul Ju Kim; Byoung Ok Yoo; Yong Joo Park

2005-01-01

115

A note on the loop thermosyphon with mixed boundary conditions  

NASA Technical Reports Server (NTRS)

This paper presents a one-dimensional model for flow in a toroidal fluid loop in which the wall heat transfer coefficient is constant over one half of the loop, and zero over the other. A mathematically low-dimensional form of the model gives reasonably accurate predictions of the steady state mass flow, stability, and the nature of nonsteady motions. Numerical computations with a high-dimensional model illustrate the effects of mixed boundaries and axial heat conduction on the chaotic solutions. Comparisons are made with previous low-dimensional models that are exact only for a spatially uniform heat transfer coefficient.

Hart, J. E.

1985-01-01

116

A Study of the Constrained Vapor Bubble Thermosyphon  

NASA Technical Reports Server (NTRS)

The objective of this effort is to better understand the physics of evaporation, condensation, and fluid flow as they affect the heat transfer processes in a constrained vapor bubble heat exchanger (CVBHX). This CVBHX consists of a small enclosed container with a square cross section (inside dimensions. 3 x 3 x 40 mm) partially filled with a liquid. The major portion of the liquid is in the corners, which act as arteries. When a temperature difference is applied to the ends of the CVBHX, evaporation occurs at the hot end and condensation at the cold end resulting in a very effective heat transfer device with great potential in space applications. Liquid is returned by capillary flow in the corners. A complete description of the system and the results obtained to date are given in the papers listed.

Wayner, Peter C., Jr.; Plawsky, J. L.

2000-01-01

117

Prediction of temperature performance of a two-phase closed thermosyphon using Artificial Neural Network  

NASA Astrophysics Data System (ADS)

Here, the temperature performance of a two-phase closed thermosyphon (TPCT) was investigated using two synthesized nanofluids, including carbon nano-tube (CNT)/water and CNT-Ag/water. In order to determine the temperature performance of a TPCT, the experiments were performed for various values of weight fraction and input power. To predict the other experimental conditions, a reliable and accurate tool should be applied. Therefore Artificial Neural Network (ANN) was applied to predict the process performance. Using ANN, the operating parameters, including distribution of wall temperature (T) and the temperature difference between the input and the output water streams of condenser section (?T) were determined. To achieve this goal, the multi-layer perceptron network was employed. The Levenberg-Marquardt algorithm was chosen as learning algorithm of this network. The results of simulation showed an excellent agreement with the data resulted from the experiments. Therefore it is possible to say that ANN is a powerful tool to predict the performance of different processes.

Shanbedi, Mehdi; Jafari, Dariush; Amiri, Ahmad; Heris, Saeed Zeinali; Baniadam, Majid

2013-01-01

118

THERMOSYPHON BATCH AND REGENERATIVE TURBINE RECIRCULATING 18 O(P,N) 18 F WATER TARGETS FOR OPERATION AT HIGH BEAM POWER  

Microsoft Academic Search

AIMS: Improved boiling water target designs and body materials for the production of ( 18 F)fluoride ion have evolved steadily over the last two decades (1), and reliable operation at beam power up to one kilowatt has been achieved. Our goal is to extend this beam power limit to two kW for boiling water targets through use of the thermosyphon

BW Wieland; BC Wright; GT Bida; CD Illan; JM Doster; JC Clark; RC Runkle

119

Experimental studies on heat transfer and friction factor characteristics of thermosyphon solar water heater system fitted with spacer at the trailing edge of twisted tapes  

Microsoft Academic Search

Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater system with full- length twist, twist fitted with rod and spacer fitted at the trailing edge for lengths of 100, 200 and 300mm for twist ratio 3 and 5 has been carried out and compared with plain tube collector for the same operating conditions. The experimental

S. Jaisankar; T. K. Radhakrishnan; K. N. Sheeba

2009-01-01

120

One-dimensional analysis of maximum performance in a closed two-phase thermosyphon with a crossover flow separator  

SciTech Connect

A comprehensive model is developed to calculate the maximum performance of a thermosyphon with a built-in crossover separator. Mechanisms limiting performance are considered to be a flow instability in a natural-circulation two-phase flow system at low reduced pressures (e.g., for Freon-11, p{sub r} < 0.126) and at low total mass flux and wave film spalling at moderate reduced pressures, respectively. Which limit becomes dominant depends on the operating conditions, as shown by the experimental data. In systematic experiments, various working fluids are used, viz., water, ethanol, Freon-11, and Freon-113. Operating temperature and liquid fill ratio are varied. The present model for maximum performance agrees well (within {+-} 15%) with experimental data.

Lin, L.; Groll, M.; Roesler, S. [Univ. Stuttgart (Germany). Inst. fuer Kernenergetik and Energiesysteme

1996-07-01

121

Heat transfer, flow regime and instability of a nano- and micro-porous structure evaporator in a two-phase thermosyphon loop  

Microsoft Academic Search

Two-phase flow instabilities which may occur at low and high heat loads were studied for a thermosyphon loop with R134a as refrigerant. The heat transfer surface of the evaporator was enhanced with a copper nano- and micro-porous structure. The heat transfer of the enhanced evaporator was compared to a smooth surface evaporator. Finally, the influence of the liquid level and

Rahmatollah Khodabandeh; Richard Furberg

2010-01-01

122

Investigation of the Vibration Effect on the Closed Two-Phase Thermosyphon Operation  

Microsoft Academic Search

One of the important problems to be solved while designing aircrafts of various purposes is to maintain the necessary temperature inside them. Besides everything it is necessary to equalize the temperature on the surfaces of various aircraft elements for preventing their deformation. The most promising direction when solving the aforementioned problems is the application of heat pipes as an element

K. Prisniakov

2002-01-01

123

Effect of thermal conductivity of absorber plate on the performance of a solar water heater  

Microsoft Academic Search

The effect of thermal conductivity of the absorber plate of a solar collector on the performance of a thermosyphon solar water heater is studied by the use of the transient simulation system (TRNSYS) computer program. The system is assumed to supply hot water at 55° and 80°C representing both domestic and industrial uses respectively. Hot water of volumes 50, 125,

A. M. Shariah; A. Rousan; Kh. K. Rousan; A. A. Ahmad

1999-01-01

124

Thermal hydraulic analysis of two-phase closed thermosyphon cooling system for new cold neutron source moderator of Breazeale research reactor at Penn State  

NASA Astrophysics Data System (ADS)

A cold neutron source cooling system is required for the Penn State's next generation cold neutron source facility that can accommodate a variable heat load up to about ˜10W with operating temperature of about 28K. An existing cold neutron source cooling system operating at the University of Texas Cold Neutron Source (TCNS) facility failed to accommodate heat loads upwards of 4W with the moderator temperature reaching a maximum of 44K, which is the critical temperature for the operating fluid neon. The cooling system that was used in the TCNS cooling system was a two-phase closed thermosyphon with a reservoir (TPCTR). The reservoir containing neon gas is kept at room temperature. In this study a detailed thermal analysis of the fundamental operating principles of a TPCTR were carried out. A detailed parametric study of the various geometric and thermo-physical factors that affect the limits of the operational capacity of the TPCTR investigated. A CFD analysis is carried out in order to further refine the heat transfer analysis and understand the flow structure inside the thermosyphon and the two-phase nucleate boiling in the evaporator section of the thermosyphon. In order to help the new design, a variety of ways of increasing the operating range and heat removal capacity of the TPCTR cooling system were analyzed so that it can accommodate the anticipated heat load of 10W or more. It is found, for example, that doubling the pressure of the system will increase the capacity index zeta by 50% for a system with an initial fill ratio FR of 1. A decrease in cryorefrigeration performance angle increases the capacity index. For example taking the current condition of the TCNS system and reducing the angle from the current value of ˜700 by half (˜350) will increase the cooling power 300%. Finally based on detailed analytic and CFD analysis the best operating condition were proposed.

Habte, Melaku

125

Experimental measurement and mathematical calculation evaporator temperatures of closed loop thermosyphon  

NASA Astrophysics Data System (ADS)

The closed loop thermoshypon is device operate with working fluid phase change principle. It is a simple and reliable device providing heat transfer. This device utilizes the thermodynamic pressure difference and gravitation to circulate working fluid and has extremely high effective thermal conductivity. Usually is used to cooling of electronic components. The paper describes a design and construction of this device. As a working fluid was used fluorinert FC-72. Next the paper deal with dependences measurement of evaporator temperatures on waste heat of the electronic component and their verification by means of a mathematic calculation based on physical phenomena of boiling, condensation and heat transfer.

Nemec, Patrik; Malcho, Milan; Janda?ka, Jozef

2013-10-01

126

Thermosyphon heat exchanger  

NASA Technical Reports Server (NTRS)

Report summarizes final development, testing, and certification of pumpless, liquid-to-air heat exchanger for solar heating. System requires blower but no pump in water loop. Output is 35,000 Btu/hr when water temperature is 49 C.

Hankins, J. D.

1980-01-01

127

Design and testing of a locally made loop-type thermosyphonic heat sink for stove-top thermoelectric generators  

Microsoft Academic Search

The performance of a thermoelectric generator, among other aspects, depends on the use of an effective heat sink. While forced cooling using either air or water (or other coolants) is efficient, it is parasitic on the generated power and\\/or bulky and inconvenient. Heat pipes are known to be highly effective heat transport devices. Coupled to a thermoelectric generator, these can

R. Y. Nuwayhid; R. Hamade

2005-01-01

128

Study of the Constrained Vapor Bubble Thermosyphon.  

National Technical Information Service (NTIS)

The objective of this effort is to better understand the physics of evaporation, condensation, and fluid flow as they affect the heat transfer processes in a constrained vapor bubble heat exchanger (CVBHX). This CVBHX consists of a small enclosed containe...

P. C. Wayner J. L. Plawsky

2000-01-01

129

Capillary Assisted Thermosyphon For Shipboard Electronics Cooling.  

National Technical Information Service (NTIS)

Recent advances in capillary pumped loop technology were incorporated into the design of a vertical flat plate evaporator for cooling high power electronics aboard naval vessels. This investigation included the design, fabrication, and experimentation of ...

E. H. Larsen

2003-01-01

130

Comparison of natural convection heat exchangers for solar water heating systems  

Microsoft Academic Search

Thermosyphon heat exchangers are used in indirect solar water heating systems to avoid using a pump to circulate water from the storage tank to the heat exchanger. In this study, the authors consider the effect of heat exchanger design on system performance. They also compare performance of a system with thermosyphon flow to the same system with a 40W pump

J. Davidson; W. Liu

1998-01-01

131

ANALYTICAL DESCRIPTION OF CHAOTIC OSCILLATIONS IN A TOROIDAL THERMOSYPHON  

Microsoft Academic Search

Multiple time scales and singular perturbation techniques are used to describe the ordinary and the chaotic oscillations due to natural convection in a fluid loop subject to a known external heat flux. The turbulent flow in the loop is modelled using the hydraulic approximation with a quadratic friction law. No steady solutions exist if the heat is added mainly to

A. LINAN

132

Two-Phase Thermosyphon Device for the Large Thyristor Cooling.  

National Technical Information Service (NTIS)

The paper reports on the design of a new advanced air-cooled heat sink device for the cooling of large thyristors, with silicon wafers (75 and 100 mm diameters) and their dissipating auxiliary components, such as snubber resistors. This device, consisting...

P. Bordignon A. Ragni E. Latrofa C. Casarosa

1989-01-01

133

Passive thermosyphon solar heating and cooling module with supplementary heating  

NASA Technical Reports Server (NTRS)

A collection of three quarterly reports from Sigma Research, Inc., covering progress and status from January through September 1977 are presented. Three heat exchangers are developed for use in a solar heating and cooling system for installation into single-family dwellings. Each exchanger consists of one heating and cooling module and one submerged electric water heating element.

1977-01-01

134

Interfacial Force Field Characterization in a Constrained Vapor Bubble Thermosyphon.  

National Technical Information Service (NTIS)

Isothermal profiles of the extended meniscus in a quartz cuvette were measured in the earth's gravitational field using an image-analyzing interferometer that is based on computer-enhanced video microscopy of the naturally occurring interference fringes. ...

S. DasGupta J. L. Plawsky P. C. Wayner

1995-01-01

135

PERFORMANCE OF A THERMOSYPHON DRIVEN BY A NANO-FLUID  

Microsoft Academic Search

The present scenario of high thermal loading coupled with high flux levels demands exploration of new heat transfer augmentation mechanisms. In this context, 'Nanofluids' may emerge as alternative heat transfer fluids. The term 'Nanofluids' is used to indicate a special class of heat transfer fluids that contain stabilized nanoparticles (<~100 nm) of metallic\\/non metallic substances uniformly and stably suspended in

Sameer Khandekar

136

Black Liquid Solar Collector Demonstrator.  

ERIC Educational Resources Information Center

Describes the details of constructing, and use of, a solar collector. Uses a black liquid to absorb the energy, the thermosyphon effect to drive the liquid through the collector, and a floodlamp as a surrogate sun. (GA)

Weichman, F. L.; Austen, D. J.

1979-01-01

137

Comparison of six generic solar domestic hot water systems  

SciTech Connect

The cost effectiveness of residential solar water heating is explored by analyzing six different system types. A figure of merit (that considers both performance and cost) is calculated for each system, providing information for both researchers and industry. Thermosyphon water heaters are determined to be the most cost effective option, and their wider application is recommended once a reliable draindown technique is developed.

Farrington, R.B.; Murphy, L.M.; Noreen, D.L.

1980-04-01

138

Theoretical Design of Thermosyphon for Process Heat Transfer from NGNP to Hydrogen Plant.  

National Technical Information Service (NTIS)

The Next Generation Nuclear Plant (NGNP) will most likely produce electricity and process heat, with both being considered for hydrogen production. To capture nuclear process heat, and transport it to a distant industrial facility requires a high temperat...

F. Gunnerson M. Patterson P. Sabharwall

2008-01-01

139

Interfacial force field characterization of a constrained vapor bubble thermosyphon using IAI  

NASA Technical Reports Server (NTRS)

The isothermal profiles of the extended meniscus in a quartz cuvette were measured in a gravitational field using IAI (image analyzing interferometer) which is based on computer enhanced video microscopy of the naturally occurring interference fringes. The experimental results for heptane and pentane menisci were analyzed using the extended Young-Laplace Equation. These isothermal results characterized the interfacial force field in-situ at the start of the heat transfer experiments by quantifying the dispersion constant for the specific liquid-solid system. The experimentally obtained values of the disjoining pressures and the dispersion constants are compared to the subsequent non-isothermal experiments because one of the major variables in the heat sink capability of the CVBT is the dispersion constant. In all previous studies of micro heat pipes the value of the dispersion constant has been 'guesstimated'. The major advantages of the current glass cell is the ability to view the extended meniscus at all times. Experimentally, we find that the extended Young-Laplace Equation is an excellent model for for the force field at the solid-liquid vapor interfaces.

Dasgupta, Sunando; Plawsky, Joel L.; Wayner, Peter C., Jr.

1994-01-01

140

Analysis of a Natural Convection/Thermosyphon Mechanism for Heat Rejection from Enclosures.  

National Technical Information Service (NTIS)

The problem of electronic component cooling in rectangular tall vertical enclosures heated at the bottom, and cooled from the sides and top is investigated numerically. The investigation considers both 2-D and 3-D enclosures, with emphasis on the 2-D conf...

J. W. Stahl

1999-01-01

141

Alternative approaches to thermosyphon solar-energy water heater performance analysis and characterisation  

Microsoft Academic Search

Simplified models, performance correlations and rigorous simulation models are identified as alternative techniques for the prediction and characterisation of the performance of natural-circulation solar energy water heaters. The features of particular examples of each approach are described. In their different appropriate contexts, each technique is shown to provide good agreement with measured system behaviour. A more general role in practical

B. Norton; P. C. Eames; S. N. G. Lo

2001-01-01

142

A criterion study of solar irradiation patterns for the performance testing of thermosyphon solar water heaters  

Microsoft Academic Search

A Taiwan test standard was established in 1989 using outdoor daily efficiency test methods. This test standard has been implemented for 12 years with satisfactory results. However, it was also found from field applications that the pattern of solar irradiation would affect the result of the performance test. In the present study, we used a distribution factor Ri defined as

J. M Chang; M. C Shen; B. J Huang

2002-01-01

143

Are Effective Properties Effective?  

SciTech Connect

The effective moduli (effective Young's modulus, effective Poisson's ratio, effective shear modulus, and effective bulk modulus) of dispersed-phase-reinforced composite materials are determined at the mesoscopic level using three-dimensional parallel boundary element simulations. By comparing the mesoscopic BEM results and the macroscopic results based on effective properties, limitations in the effective property approach have been examined.

Han, Ru; Ingber, Marc S. [Department of Mechanical Engineering, University of New Mexico, NM 87131 (United States); Hsiao, S.-C. [Department of Hydraulic and Ocean Engineering, National Cheng-Kung University No. 1, Ta-Hsueh Road Tainan 701, Taiwan (China)

2008-02-15

144

Numerical solution of fluid flow and heat tranfer problems with surface radiation  

NASA Technical Reports Server (NTRS)

This paper presents a numerical scheme, based on the finite element method, to solve strongly coupled fluid flow and heat transfer problems. The surface radiation effect for gray, diffuse and isothermal surfaces is considered. A procedure for obtaining the view factors between the radiating surfaces is discussed. The overall solution strategy is verified by comparing the available results with those obtained using this approach. An analysis of a thermosyphon is undertaken and the effect of considering the surface radiation is clearly explained.

Ahuja, S.; Bhatia, K.

1995-01-01

145

An analytical model for the determination of stability boundaries in a natural circulation single-phase thermosyphon loop  

Microsoft Academic Search

In this paper, an extension of previous analyses of natural circulation in a simple single-phase loop is presented. Assuming more general correlations for the friction factor and the heat transfer coefficient, an analytical model describing the system is obtained and a parametric representation of its dynamic behaviour is achieved. On this basis, stability maps can be drawn. A preliminary validation

M. Maiani; W. J. M. de Kruijf; W. Ambrosini

2003-01-01

146

Engineering design elements of a two-phase thermosyphon to transfer nuclear thermal energy to a hydrogen plant  

Microsoft Academic Search

Two hydrogen production processes, both powered by Next Generation Nuclear Plant (NGNP), are currently under investigation at the Idaho National Laboratory. The first is high-temperature steam electrolysis utilizing both heat and electricity and the second is thermo-chemical production through the sulfur-iodine process primarily utilizing heat. Both processes require high temperature (>850°C) for enhanced efficiency; temperatures indicative of NGNP. Safety and

Piyush Sabharwall

2009-01-01

147

A DIGITAL COMPUTER ANALYSIS OF CLOSED CYCLE WATER NUCLEAR POWER PLANT START UP USING NATURAL CIRCULATION (THERMOSYPHON CODE). VOLUME I  

Microsoft Academic Search

An analysis of the natural circulation in the primary system of a closed ; cycle water nuclear power plant during plant start up is presented. The solution ; to the problem is obtained by numerical integratfon of the governing differential ; equations, using an IBM-7090 digital computer. The thermodynamic behavior of the ; primary system coolant during plant startup with

A. N. Nahavandi; B. H. Axelson; G. B. Killinger; A. H. Killinger

1962-01-01

148

Comparison of natural convection heat exchangers for solar water heating systems  

SciTech Connect

Thermosyphon heat exchangers are used in indirect solar water heating systems to avoid using a pump to circulate water from the storage tank to the heat exchanger. In this study, the authors consider the effect of heat exchanger design on system performance. They also compare performance of a system with thermosyphon flow to the same system with a 40W pump in the water loop. In the first part of the study, the authors consider the impact of heat exchanger design on the thermal performance of both one- and two-collector solar water heaters. The comparison is based on Solar Rating and Certification Corporation (SRCC) OG300 simulations. The thermosyphon heat exchangers considered are (1) a one-pass, double wall, 0.22 m{sup 2}, four tube-in-shell heat exchanger manufactured by AAA Service and Supply, Inc., (the Quad-Rod); (2) a two-pass, double wall, 0.2 m{sup 2}, tube-in-shell made by Heliodyne, Inc., but not intended for commercial development; (3) a one-pass, single wall, 0.28 m{sup 2}, 31 tube-in-shell heat exchanger from Young Radiator Company, and (4) a one-pass single-wall, 0.61 m{sup 2}, four coil-in-shell heat exchanger made by ThermoDynamics Ltd. The authors compare performance of the systems with thermosyphon heat exchangers to a system with a 40 W pump used with the Quad-Rod heat exchanger. In the second part of the study, the effects of reducing frictional losses through the heat exchanger and/or the pipes connecting the heat exchanger to the storage tank, and increasing heat transfer area are evaluated in terms of OG300 ratings.

Davidson, J.; Liu, W.

1998-09-15

149

Doppler Effect  

NSDL National Science Digital Library

This site offers information on the classical doppler effect, the relativistic doppler effect, aberration, and the transverse doppler effect. It also discusses wave fronts, first-order and second order effect, light-time correction, Galilean transformation, and parallax.

Calvert, J. B.

2010-08-19

150

Placebo Effect  

MedlinePLUS

... effect This information is current as of August 25, 2008 http://www.neurology.org/content/71/9/ ... effect This information is current as of August 25, 2008 Services Updated Information & http://www.neurology.org/ ...

151

Greenhouse Effect  

NSDL National Science Digital Library

This activity is a greenhouse-effect-in-a-bottle experiment. The lesson includes readings from NEED.org and an inquiry lab measuring the effect of carbon dioxide and temperature change in an enclosed environment.

Education, Connecticut E.

152

Effects of \\  

Microsoft Academic Search

Brainstorming instruction is an effective method for increasing the production of good ideas in a particular type of creative thinking problems, and is even more effective if preceded by extensive training in its use. (5 tables)

Sidney J. Parnes; Arnold Meadow

1959-01-01

153

Doppler Effect  

NSDL National Science Digital Library

In this activity, learners use a tuning fork to explore how the Doppler effect works. They strike the tuning fork to produce a sound, then observe as the tone changes as the fork is swung back and forth. Learners also explore applications of the Doppler effect in technology.

Cosi

2009-01-01

154

Thermal Effects.  

ERIC Educational Resources Information Center

Presents a literature review of the effect of temperature on the biosphere water, covering publications of 1976-77. This review includes the effects of temperature on growth, production, and embryonic and larval development. A list of 401 references is also presented. (HM)

Talmage, Sylvia S.; Coutant, Charles C.

1978-01-01

155

Size effect  

Microsoft Academic Search

This paper surveys the available results on the size effect on the nominal strength of structures — a fundamental problem of considerable importance to concrete structures, geotechnical structures, geomechanics, arctic ice engineering, composite materials, etc., with applications ranging from structural engineering to the design of ships and aircraft. The history of the ideas on the size effect is briefly outlined

Zden?k P. Bažant

2000-01-01

156

Deterministic effects.  

PubMed

Deterministic effects are distinguished from stochastic effects for radiation protection purposes by the following characteristics: both incidence and severity increase as a function of dose after a threshold dose is reached. Cell killing is central to all deterministic effects with the exception of radiation-induced cataracts. The understanding of radiation-induced killing of cells has increased greatly in the last decade with an extraordinarily intense interest in apoptosis. Programmed cell death has long been known to developmental biologists and the importance of cell death has been recognized and quantified by tumor biologists and students of cell kinetics but the coining of a new name and the increase of understanding of the molecular aspects of cell death has stimulated interest. Some cells appear to be very sensitive to radiation and undergo apoptosis, whereas others such as fibroblasts do not with equal frequency. This characteristic, like many others, underlines the genetic differences among cell types. We are reaching a time that there are techniques and the knowledge to apply them to clinical and radiation protection problems. In radiotherapy, success depends on the differential effect between tumor and normal tissues that is obtained. To design the optimum therapy, a profile of both the tumor cells and the cells of the normal tissues that may be at risk would help. The profile would characterize the radiosensitivity and the underlying factors, which could help in the choice of adjunct therapy for tumor and normal tissue. Fibrosis, a common unwanted late effect, appears to be influenced by genetic factors, at least in experimental animals. Techniques are available for treating people as individuals more than ever before, and that must be a good thing to do. Protection against deterministic effects would seem an easy matter but we are uncomfortably ignorant of the precise effect of protracted low-dose irradiation on tissues, such as the bone marrow and the testis, important features of risk in space. Entering the new century, it may be timely to classify radiation effects, as Radiation Effects Research Foundation (RERF) has done, into cancer, genetic effects, and noncancer effects. The recognition in the atomic-bomb survivors of noncancer effects at doses on the order of 0.5 Sv (half the dose level considered a threshold in earlier studies) should stimulate interest in deterministic effects. PMID:11281201

Fry, R J

2001-04-01

157

Effective Schools Require Effective Principals  

ERIC Educational Resources Information Center

At long last, scholars and policy makers have come to realize what most school administrators have known for years--that effective schools require both outstanding teachers and strong leaders. Although there is considerable research about the characteristics of effective school leaders and the strategies principals can use to help manage…

LaPointe, Michelle; Davis, Stephen H.

2006-01-01

158

Doppler Effect  

NSDL National Science Digital Library

- The Doppler Effect explains why we hear a sonic boom when an airplane flies faster than the speed of sound. - Applying the Doppler Effect is how we have Doppler Radar used to track weather. - The Doppler Effect can be applied to outerspace and it evidence that the universe is expanding. Sound is energy traveling through a medium. A medium can be a gas, liquid, or solid. Therefore sound can not travel in outerspace since it is a vacuum which means there is nothing not even air. Energy traveling through a medium or even a vacuum is considered a wave. ...

Leet, Mr.

2008-03-16

159

[Effective delegation].  

PubMed

Ninety-seven percent of middle level managers feel they face work overload. The source of this problem may lie in a failure to delegate tasks effectively. If a manager does not effectively delegate, he/she is more likely to report fatigue, stress and depression. Conversely, effectively delegating tasks will improve overall job quality, professional growth in subordinates and cooperation within the team. While it is necessary for managers to delegate tasks effectively, few can be considered to be good natural 'delegators'. Learning and training is necessary for managers to develop the necessary confidence and maturity. This article describes the definitions, purpose and benefits of delegation; factors related to effective delegation; strategies related to successful delegation and skills related to performing cross-cultural delegations. Such issues have seldom been addressed in previous articles. Moreover, nursing implications and suggested applications in nursing practice, education, management and research are mentioned. This article is intended to provide directions to nursing managers and subordinates to promote delegation knowledge and skills. PMID:19051179

Fang, Li; Hung, Chich-Hsiu

2008-12-01

160

Thermal hydraulic analysis of two-phase closed thermosyphon cooling system for new cold neutron source moderator of Breazeale research reactor at Penn State  

Microsoft Academic Search

A cold neutron source cooling system is required for the Penn State's next generation cold neutron source facility that can accommodate a variable heat load up to about ˜10W with operating temperature of about 28K. An existing cold neutron source cooling system operating at the University of Texas Cold Neutron Source (TCNS) facility failed to accommodate heat loads upwards of

Melaku Habte

2008-01-01

161

Photoelectric Effect  

NSDL National Science Digital Library

This is a series of simulations of aspects of the photoelectric effect. There is an animation of the experiment with four choices of incident radiation - low and high intensity "red", to represent low energy light and low and high intensity "blue" to represent higher energy light. Electron production is animated and there is an ammeter to simulate current flow. Additional simulations show the effect of light frequency and intensity. There is a link to a spreadsheet that allows students to choose a sample from among five metals. The spreadsheet includes several questions to be answered after working through the materials.

162

Teapot Effect  

Microsoft Academic Search

When tea is poured from a teapot it often runs along the under side of the spout rather than falling into the cup. Recent experiments have shown that this ``teapot effect'' is not due to surface tension nor adhesion, as many have supposed. Therefore, a new explanation is presented which is based upon certain exact solutions of the hydrodynamic equations

Joseph B. Keller

1957-01-01

163

Coriolis Effect  

NSDL National Science Digital Library

This set of four animated slides illustrates the Coriolis effect, a manifestation of one of Newton's laws which says that objects move in a straight line, in an "inertial" frame of reference, unless acted upon by a force. The slides use the analogy of a ball thrown on a rotating carousel.

164

Effective Mentoring  

Microsoft Academic Search

Effective mentoring is essential to the growth and success of librarianship in all types of library. This paper considers the possibilities for fostering mentoring activities among early career librarians, mid-career transitional librarians, and non-professional library workers. First, the paper describes existing studies to illuminate the urgency of mentoring activities to address the diminishing number of librarians and changing librarianship in

Shin Freedman

2009-01-01

165

Slingshot Effect  

NSDL National Science Digital Library

This web page demonstrates the slingshot effect through a Flash simulation. The user places an object at some distance from Jupiter, sets up its initial velocity, then choose the appropriate time to lunch it. Once the simulation begins, the path of the projectile and its speed are shown.

Fowler, Michael; Ching, Jacquie H.

2008-09-20

166

System Effectiveness  

SciTech Connect

An effective risk assessment system is needed to address the threat posed by an active or passive insider who, acting alone or in collusion, could attempt diversion or theft of nuclear material. It is critical that a nuclear facility conduct a thorough self-assessment of the material protection, control, and accountability (MPC&A) system to evaluate system effectiveness. Self-assessment involves vulnerability analysis and performance testing of the MPC&A system. The process should lead to confirmation that mitigating features of the system effectively minimize the threat, or it could lead to the conclusion that system improvements or upgrades are necessary to achieve acceptable protection against the threat. Analysis of the MPC&A system is necessary to understand the limits and vulnerabilities of the system to internal threats. Self-assessment helps the facility be prepared to respond to internal threats and reduce the risk of theft or diversion of nuclear material. MSET is a self-assessment or inspection tool utilizing probabilistic risk assessment (PRA) methodology to calculate the system effectiveness of a nuclear facility's MPC&A system. MSET analyzes the effectiveness of an MPC&A system based on defined performance metrics for MPC&A functions based on U.S. and international best practices and regulations. A facility's MC&A system can be evaluated at a point in time and reevaluated after upgrades are implemented or after other system changes occur. The total system or specific subareas within the system can be evaluated. Areas of potential performance improvement or system upgrade can be assessed to determine where the most beneficial and cost-effective improvements should be made. Analyses of risk importance factors show that sustainability is essential for optimal performance. The analyses reveal where performance degradation has the greatest detrimental impact on total system risk and where performance improvements have the greatest reduction in system risk. The risk importance factors show the amount of risk reduction achievable with potential upgrades and the amount of risk reduction actually achieved after upgrades are completed. Applying the risk assessment tool gives support to budget prioritization by showing where budget support levels must be sustained for MC&A functions most important to risk. Results of the risk assessment are also useful in supporting funding justifications for system improvements that significantly reduce system risk.

Powell, Danny H [ORNL] [ORNL; Elwood Jr, Robert H [ORNL] [ORNL

2011-01-01

167

Effective Presentations  

PubMed Central

Where the purpose of presentations is to inform, effective delivery is important to ensure that audiences receive the educational message. We offer six suggestions: introduce the topic in an interesting way; speak loudly enough; do not read; involve the audience actively; respect the attention span of the audience; and limit the amount of content. We conclude that the skills of live public presentation can be learned, but that the art of presentation is innate. Imagesp2063-ap2064-a

Spooner, H. James; Swanson, Richard W.

1990-01-01

168

Compton Effect  

NSDL National Science Digital Library

The Compton Effect model simulates the the scattering of light off of an electron, the Compton effect. Compton used the idea that light behaves like a particle to explain light-electron (photon-electron) scattering. He used the relation for the energy and momentum of the photon and the relativistic expression for the energy of the electron, and applied relativistic energy and momentum conservation for the collision. The wavelength shift of the light depend on the angle of the scattered photon (and the electron). By changing the scattering angle in the simulation, the angle of the scattered photon changes according to Compton's equation. The panel on the left shows the experimental set up, while the panel on the right shows the resulting photon wavelength from the scattering. In a typical Compton experiment, light is scattered off of the electrons in an atom, and there is little scattering due to the more tightly held electrons while there is more scattering due to the less tightly held electrons. This is what is responsible for the two peak distribution shown. The Compton Effect model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_qm_compton.jar file will run the program if Java is installed.

Palop, Jose I.

2010-12-12

169

Microbial effects  

SciTech Connect

The postulated doubling of atmospheric CO/sub 2/ is not likely to have direct effect on soil microbial activity because during the growing season, the concentration of CO/sub 2/ in the soil atmosphere is already ten to fifty times higher than existing atmospheric CO/sub 2/. Based on all available experimental information, it is estimated that a doubling of atmospheric CO/sub 2/ will cause an increase in primary productivity of 10 to 40% depending on locale. The increase in biomass will, in turn, produce a limitation of available soil nutrients, especially nitrogen and phosphorus. Increased organic carbon together with nitrogen and/or phosphorus limitation will result in a preferential increase in nitrogen fixation and mycorrhizal activities as the expedient means for supplying required nutrients to sustain the predicted increase in primary productivity. Therefore, increased emphasis should be placed on fundamental research related to soil microbiology with special reference to nitrogen-fixing, nitrifying and denitrifying bacteria, and to the mycorrhizal fungi. 111 references, 2 figures.

Lamborg, M.R.; Hardy, R.W.F.; Paul, E.A.

1983-01-01

170

Effective Teaching/Effective Urban Teaching  

ERIC Educational Resources Information Center

This article considers the ways in which 17 novice teachers define and describe effective urban teaching and the stark contrasts that these teachers draw between effective urban teaching and effective teaching. The authors find that descriptions of students played a considerable role when participants made distinctions between effective teaching…

Watson, Dyan; Charner-Laird, Megin; Kirkpatrick, Cheryl L.; Szczesiul, Stacy Agee; Gordon, Pamela J.

2006-01-01

171

Gravity Scaling of a Power Reactor Water Shield  

NASA Astrophysics Data System (ADS)

Water based reactor shielding is being considered as an affordable option for potential use on initial lunar surface reactor power systems. Heat dissipation in the shield from nuclear sources must be rejected by an auxillary thermal hydraulic cooling system. The mechanism for transferring heat through the shield is natural convection between the core surface and an array of thermosyphon radiator elements. Natural convection in a 100 kWt lunar surface reactor shield design has been previously evaluated at lower power levels (Pearson, 2006). The current baseline assumes that 5.5 kW are dissipated in the water shield, the preponderance on the core surface, but with some volumetric heating in the naturally circulating water as well. This power is rejected by a radiator located above the shield with a surface temperature of 370 K. A similarity analysis on a water-based reactor shield is presented examining the effect of gravity on free convection between a radiation shield inner vessel and a radiation shield outer vessel boundaries. Two approaches established similarity: 1) direct scaling of Rayleigh number equates gravity-surface heat flux products, 2) temperature difference between the wall and thermal boundary layer held constant on Earth and the Moon. Nussult number for natural convection (laminar and turbulent) is assumed of form Nu = CRan. These combined results estimate similarity conditions under Earth and Lunar gravities. The influence of reduced gravity on the performance of thermosyphon heat pipes is also examined.

Reid, Robert S.; Pearson, J. Boise

2008-01-01

172

Gravity Scaling of a Power Reactor Water Shield  

NASA Technical Reports Server (NTRS)

Water based reactor shielding is being considered as an affordable option for use on initial lunar surface power systems. Heat dissipation in the shield from nuclear sources must be rejected by an auxiliary thermal hydraulic cooling system. The mechanism for transferring heat through the shield is natural convection between the core surface and an array of thermosyphon radiator elements. Natural convection in a 100 kWt lunar surface reactor shield design has been previously evaluated at lower power levels (Pearson, 2007). The current baseline assumes that 5.5 kW are dissipated in the water shield, the preponderance on the core surface, but with some volumetric heating in the naturally circulating water as well. This power is rejected by a radiator located above the shield with a surface temperature of 370 K. A similarity analysis on a water-based reactor shield is presented examining the effect of gravity on free convection between a radiation shield inner vessel and a radiation shield outer vessel boundaries. Two approaches established similarity: 1) direct scaling of Rayleigh number equates gravity-surface heat flux products, 2) temperature difference between the wall and thermal boundary layer held constant on Earth and the Moon. Nussult number for natural convection (laminar and turbulent) is assumed of form Nu = CRa(sup n). These combined results estimate similarity conditions under Earth and Lunar gravities. The influence of reduced gravity on the performance of thermosyphon heat pipes is also examined.

Reid, Robert S.; Pearson, J. Boise

2008-01-01

173

Communicating Effectively PDF  

Cancer.gov

Effective communication is essential for the delivery of quality cancer palliative care. And yet, healthcare providers often lack the skills to communicate effectively with their patients and families.

174

AHSGE Cause and Effect  

NSDL National Science Digital Library

Cause and Effect practice to build skill knowledge for the reading portion of the graduation exam. Complete the Cause and Effect activities at your pace . Cause and Effect Match , Cause and Effect Mini Lesson and Game , What s the Cause?? Quiz . ...

Ufomadu, Ms.

2013-06-13

175

On Effect Size  

Microsoft Academic Search

The call for researchers to report and interpret effect sizes and their corresponding confidence intervals has never been stronger. However, there is confusion in the literature on the definition of effect size, and consequently the term is used inconsistently. We propose a definition for effect size, discuss 3 facets of effect size (dimension, measure\\/index, and value), outline 10 corollaries that

Ken Kelley; Kristopher J. Preacher

2012-01-01

176

On Effect Size  

ERIC Educational Resources Information Center

The call for researchers to report and interpret effect sizes and their corresponding confidence intervals has never been stronger. However, there is confusion in the literature on the definition of effect size, and consequently the term is used inconsistently. We propose a definition for effect size, discuss 3 facets of effect size (dimension,…

Kelley, Ken; Preacher, Kristopher J.

2012-01-01

177

Polymorphic effect systems  

Microsoft Academic Search

We present a new approach to programming languages for parallel computers that uses an effect system to discover expression scheduling constraints. This effect system is part of a 'kinded' type system with three base kinds: types, which describe the value that an expression may return; effects, which describe the side-effects that an expression may have; and regions, which describe the

John M. Lucassen; David K. Gifford

1988-01-01

178

A random effects model for effect sizes  

Microsoft Academic Search

Recent interest in quantitative research synthesis has led to the development of rigorous statistical theory for some of the methods used in meta-analysis. Statistical theory proposed previously has stressed the estimation of fixed but unknown population effect sizes (standardized mean differences). Theoretical considerations often suggest that treatment effects are not fixed but vary across different implementations of a treatment. The

Larry V. Hedges

1983-01-01

179

Natural convection heat exchangers for solar water heating systems. Technical progress report, February 1, 1996--March 31, 1996.  

National Technical Information Service (NTIS)

This progress report describes the thermodynamic testing and modeling of a thermosyphon heat exchanger used in solar water heating systems. Testing of a four tube-in-shell thermosyphon heat exchanger was performed in two parts. The first portion of the te...

J. H. Davidson

1998-01-01

180

Evaluating Heat Pipe Performance in 1/6 g Acceleration: Problems and Prospects  

NASA Technical Reports Server (NTRS)

Heat pipes composed of titanium and water are being considered for use in the heat rejection system of a fission power system option for lunar exploration. Placed vertically on the lunar surface, the heat pipes would operate as thermosyphons in the 1/6 g environment. The design of thermosyphons for such an application is determined, in part, by the flooding limit. Flooding is composed of two components, the thickness of the fluid film on the walls of the thermosyphon and the interaction of the fluid flow with the concurrent vapor counter flow. Both the fluid thickness contribution and interfacial shear contribution are inversely proportional to gravity. Hence, evaluating the performance of a thermosyphon in a 1 g environment on Earth may inadvertently lead to overestimating the performance of the same thermosyphon as experienced in the 1/6 g environment on the moon. Several concepts of varying complexity have been proposed for evaluating thermosyphon performance in reduced gravity, ranging from tilting the thermosyphons on Earth based on a cosine function, to flying heat pipes on a low-g aircraft. This paper summarizes the problems and prospects for evaluating thermosyphon performance in 1/6 g.

Jaworske, Donald A.; McCollum, Timothy A.; Gibson, Marc A.; Sanzi, James L.; Sechkar, Edward A.

2011-01-01

181

The natural circulation solar water heater model with linear temperature distribution  

Microsoft Academic Search

This paper presents an analysis of natural circulation of a compact thermosyphon solar domestic hot water (SDHW) system produced and commercialised locally in Algeria. Calculations and measurements were performed on the mass flow rate, temperature rise fluid and absorber temperatures inside the thermosyphon of parallel tube design. Comparison between experimental and theoretical results is presented.

A. Zerrouki; A. Boumédien; K. Bouhadef

2002-01-01

182

Kite Pseudo Effect Algebras  

NASA Astrophysics Data System (ADS)

We define a new class of pseudo effect algebras, called kite pseudo effect algebras, which is connected with partially ordered groups not necessarily with strong unit. In such a case, starting even with an Abelian po-group, we can obtain a noncommutative pseudo effect algebra. We show how such kite pseudo effect algebras are tied with different types of the Riesz Decomposition Properties. Kites are so-called perfect pseudo effect algebras, and we define conditions when kite pseudo effect algebras have the least non-trivial normal ideal.

Dvure?enskij, Anatolij

2013-11-01

183

Beyond First Stage Effects.  

National Technical Information Service (NTIS)

A first stage effect is something that creates greater efficiency. A Second stage effect impacts how people incorporate technologies into social systems. This incorporation causes changes in traditional organization and thought that result in true revolut...

J. L. Ledoux

2000-01-01

184

Modulational effects in accelerators.  

National Technical Information Service (NTIS)

We discuss effects of field modulations in accelerators, specifically those that can be used for operational beam diagnostics and beam halo control. In transverse beam dynamics, combined effects of nonlinear resonances and tune modulations influence diffu...

T. Satogata

1997-01-01

185

Side Effects (Management)  

MedlinePLUS

... cancer care is relieving side effects, called symptom management, palliative care, or supportive care. It is important ... treat them. To learn about the symptoms and management of the long-term side effects of cancer ...

186

Aeroelastic Thermal Effects.  

National Technical Information Service (NTIS)

The adverse effect of increasing temperature on the stability of turbomachinery airfoils was long recognized but remains today one that is not fully understood. The quantitative effect on the reduced frequency parameter, k = omega c/V, which was experimen...

J. D. Jeffers

1988-01-01

187

Effects of Aging  

MedlinePLUS

... and taking steps to counterbalance the effects of aging can help you maintain a young spirit and ... of many age-related changes. The Effects of Aging Aging Muscles: As muscles age, they begin to ...

188

Medications and Side Effects  

MedlinePLUS

... medication. WHEN & HOW SEVERE (1= NOT VERY/ SIDE EFFECT 5 = EXTREMELY)SUGGESTIONS FOR COPING Lack of energy/ ... doctor. WHEN & HOW SEVERE (1= NOT VERY/ SIDE EFFECT 5 = EXTREMELY)SUGGESTIONS FOR COPING Anxiety I Ask ...

189

Military Effectiveness: A Reappraisal.  

National Technical Information Service (NTIS)

Military effectiveness is a common goal among military forces, but it is an ill-defined concept. Two divergent theories cover the ground of military effectiveness. One looks at the interaction of social structures, whereas the other looks at the effect or...

J. J. Bernasconi

2007-01-01

190

Vectorial Photoelectric Effect  

Microsoft Academic Search

Experimental results and their analysis are presented which indicate that the vectorial photoelectric effect originates neither in excitation at the surface nor in pure volume optical absorption, but is a unique combined surface-volume effect which depends only on optical absorption as influenced by the interface. This effect can be phenomenologically regarded as surface-enhanced optical absorption (SEOA) in which, for certain

R. M. Broudy

1971-01-01

191

Allee effects in ants.  

PubMed

1. Allee effects occur when the aggregation of individuals result in mutually beneficial intraspecific interactions whereby individual fitness, or per capita growth rate, increases with the number of individuals. Allee effects are common in social species due to their cooperative behaviours, such as breeding, feeding or defence. Allee effects have important implications for many aspects of basic and applied ecology. Over the past decades, the study of Allee effects has influenced population dynamics, community ecology, endangered species management and invasion biology. 2. Despite the fact that cooperation is the basis of their social structure, Allee effects have received little attention among eusocial insects. Extreme cooperation is common, and reproductive specialization of individuals occurs due to division of labour. These life-history traits suggest that the potential contribution of each caste to reproduction and survival may be differential and nonadditive. 3. We studied Allee effects in the invasive Argentine ant (Linepithema humile). In this species, many queens and workers are present in colonies, which allowed us to explore the differential effects of castes on the presence of Allee effects. In the laboratory, we measured brood production and individual survival in experimental colonies that differed in the initial numbers of queens and workers.4. Our results highlight the differential effect of queens and workers on survival and productivity. We found three positive density-dependent relationships indicative of component Allee effects at the colony level: both workers and queens had a positive effect on the productivity of the other caste, and queens had a positive effect on worker survivorship. 5. Our experimental results suggest a potential positive feedback between worker and queen abundance, which may have contributed to the evolution of large colony sizes. Our study provides the first evidence of Allee effects in eusocial insects and highlights the need to consider castes separately in population dynamics. Division of labour and differential reproductive rates are factors that should be integrated into the study of Allee effects. PMID:23672650

Luque, Gloria M; Giraud, Tatiana; Courchamp, Franck

2013-09-01

192

How effective are maternal effects at having effects?  

PubMed Central

The well studied trade-off between offspring size and offspring number assumes that offspring fitness increases with increasing per-offspring investment. Where mothers differ genetically or exhibit plastic variation in reproductive effort, there can be variation in per capita investment in offspring, and via this trade-off, variation in fecundity. Variation in per capita investment will affect juvenile performance directly—a classical maternal effect—while variation in fecundity will also affect offspring performance by altering the offsprings' competitive environment. The importance of this trade-off, while a focus of evolutionary research, is not often considered in discussions about population dynamics. Here, we use a factorial experiment to determine what proportion of variation in offspring performance can be ascribed to maternal effects and what proportion to the competitive environment linked to the size–number trade-off. Our results suggest that classical maternal effects are significant, but that in our system, the competitive environment, which is linked to maternal environments by fecundity, can be a far more substantial influence.

Beckerman, Andrew P; Benton, Tim G; Lapsley, Craig T; Koesters, Nils

2005-01-01

193

The butterfly effect of the "butterfly effect".  

PubMed

The "Butterfly Effect" metaphor states with variance that the flap of a butterfly's wings in Brazil can cause a tornado in Texas. This metaphor has become part of the common vernacular of Western culture. In this paper I discuss the origins of the metaphor, examine its current usage within popular culture, and present an argument as to why it is popular. I propose that the metaphor is a type of semantic attractor, a narrative device with invariant meaning but audience-specific contextualization. Finally I address whether the Butterfly Effect metaphor is a good example of itself. PMID:19527619

Dooley, Kevin J

2009-07-01

194

Thermally Driven Josephson Effect  

NASA Technical Reports Server (NTRS)

A concept is proposed of the thermally driven Josephson effect in superfluid helium. Heretofore, the Josephson effect in a superfluid has been recognized as an oscillatory flow that arises in response to a steady pressure difference between two superfluid reservoirs separated by an array of submicron-sized orifices, which act in unison as a single Josephson junction. Analogously, the thermally driven Josephson effect is an oscillatory flow that arises in response to a steady temperature difference. The thermally driven Josephson effect is partly a consequence of a quantum- mechanical effect known as the fountain effect, in which a temperature difference in a superfluid is accompanied by a pressure difference. The thermally driven Josephson effect may have significance for the development of a high-resolution gyroscope based on the Josephson effect in a superfluid: If the pressure-driven Josephson effect were used, then the fluid on the high-pressure side would become depleted, necessitating periodic interruption of operation to reverse the pressure difference. If the thermally driven Josephson effect were used, there would be no net flow and so the oscillatory flow could be maintained indefinitely by maintaining the required slightly different temperatures on both sides of the junction.

Penanen, Konstantin; Chui, Talso

2008-01-01

195

The Hubble effective potential  

SciTech Connect

We generalize the effective potential to scalar field configurations which are proportional to the Hubble parameter of a homogeneous and isotropic background geometry. This may be useful in situations for which curvature effects are significant. We evaluate the one loop contribution to the Hubble Effective Potential for a massless scalar with arbitrary conformal and quartic couplings, on a background for which the deceleration parameter is constant. Among other things, we find that inflationary particle production leads to symmetry restoration at late times.

Janssen, T.M.; Miao, S.P.; Prokopec, T. [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Leuvenlaan 4, Postbus 80.195, 3508 TD Utrecht (Netherlands)] [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Leuvenlaan 4, Postbus 80.195, 3508 TD Utrecht (Netherlands); Woodard, R.P., E-mail: T.M.Janssen@uu.nl, E-mail: S.Miao@uu.nl, E-mail: T.Prokopec@uu.nl, E-mail: woodard@phys.ufl.edu [Department of Physics, University of Florida, Gainesville, FL 32611 (United States)

2009-05-15

196

Dynamic ground effects  

NASA Technical Reports Server (NTRS)

A research program is underway at the NASA Langley Research Center to study the effect of rate of descent on ground effects. A series of powered models were tested in the Vortex Research Facility under conditions with rate of descent and in the 14 x 22 Foot Subsonic Tunnel under identical conditions but without rate of descent. These results indicate that the rate of descent can have a significant impact on ground effects particularly if vectored or reversed thrust is used.

Paulson, John W., Jr.; Kemmerly, Guy T.; Gilbert, William P.

1990-01-01

197

Volcanic effects on climate  

NASA Technical Reports Server (NTRS)

Volcanic eruptions which inject large amounts of sulfur-rich gas into the stratosphere produce dust veils which last years and cool the earth's surface. At the same time, these dust veils absorb enough solar radiation to warm the stratosphere. Since these temperature changes at the earth's surface and in the stratosphere are both in the opposite direction of hypothesized effects from greenhouse gases, they act to delay and mask the detection of greenhouse effects on the climate system. Tantalizing recent research results have suggested regional effects of volcanic eruptions, including effects on El Nino/Southern Oscillation (ENSO). In addition, a large portion of the global climate change of the past 100 years may be due to the effects of volcanoes, but a definite answer is not yet clear. While effects of several years were demonstrated with both data studies and numerical models, long-term effects, while found in climate model calculations, await confirmation with more realistic models. Extremely large explosive prehistoric eruptions may have produced severe weather and climate effects, sometimes called a 'volcanic winter'. Complete understanding of the above effects of volcanoes is hampered by inadequacies of data sets on volcanic dust veils and on climate change. Space observations can play an increasingly important role in an observing program in the future. The effects of volcanoes are not adequately separated from ENSO events, and climate modeling of the effects of volcanoes is in its infancy. Specific suggestions are made for future work to improve the knowledge of this important component of the climate system.

Robock, Alan

1991-01-01

198

Handbook of radiation effects  

Microsoft Academic Search

This book emphasizes radiation effects on solid state devices from exposure to the types of radiation found outside the atmosphere (in space, or in the vicinity of an exploding nuclear device). It contains a basic study of radiation shielding of payload components for payloads in space and specifically covers radiation effects on minority and majority carriers, optical media and organic

A. Holmes-Siedle; L. Adams

1993-01-01

199

Evaluating Effective Management Learning.  

ERIC Educational Resources Information Center

A better way to assess the effectiveness of management development is to measure organizational effectiveness rather than individual improvement. Case studies support the Business Excellence Framework model, which assesses enablers (leadership, personnel management, policy, resources, processes) and results (personnel and customer satisfaction,…

Bramley, Peter

1999-01-01

200

[Providing Effective Behavior Support.  

ERIC Educational Resources Information Center

This theme issue addresses the provision of behavioral support for students with behavior disorders. The first article, "Providing Effective Behavior Support to All Students: Procedures and Processes" (George Sugai), summarizes the literature on the effectiveness of various interventions and offers several models for examining the teaching of…

SAIL: Technical Assistance Journal, 1996

1996-01-01

201

Named Rules and Effects  

NSDL National Science Digital Library

Hans Reich, professor of organic chemistry at the University of Wisconsin Madison, created this online handout on named rules and effects in organic chemistry. Concise descriptions and structures of a number of named effects, rules, stereochemical models and hypothesesâÂÂfrom BaldwinâÂÂs rules to the ZimmermanâÂÂTraxler transition stateâÂÂare given.

Reich, Hans J.

2007-12-21

202

Institutional Effectiveness Report.  

ERIC Educational Resources Information Center

This is the first edition of the College of the Canyon's (California) Institutional Effectiveness Report, which is modeled after the statewide report prepared by the Chancellor's Office. The college is measuring 60 effectiveness indicators in four mission areas: student access, student success, staff composition, and fiscal condition. A brief…

College of the Canyons, Santa Clarita, CA.

203

Comparative Effectiveness Research  

Cancer.gov

Comparative Effectiveness Research (CER) is the conduct and synthesis of systematic research comparing different interventions and strategies to prevent, diagnose, treat and monitor health conditions. The purpose of this research is to inform patients, providers, and decision-makers about which interventions are most effective for which patients under specific circumstances.

204

Earthquake Effects and Experiences  

NSDL National Science Digital Library

This portion of the United States Geological Survey's (USGS) frequently-asked-questions feature on earthquakes addresses what individuals might actually experience during an earthquake. Topics include earthquake motion (rolling or shaking), earthquake effects (ground shaking, surface faulting, ground failure, etc.), earthquake magnitude, what an earthquake feels like, and others. There are also links to additional resources on earthquake effects and experiences.

2010-11-23

205

Effects of Drug Abuse  

MedlinePLUS

Listen to this page Effects of Drug Abuse Drug abuse hurts the people who take drugs AND the people around them, including families , kids , and ... HIV/AIDS Click here to learn more about effects of specific drugs . VIDEO: Why Are Drugs So ...

206

Effects of acid precipitation  

Microsoft Academic Search

A growing body of evidence suggests that acid rain is responsible for substantial adverse effects on the public welfare. Such effects include: the acidification of lakes and rivers, with resultant damage to fish and other components of aquatic ecosystems; acidification and demineralization of soils; and possible reductions in crop and forest productivity. Affected areas include Canada and the northeastern US.

Norman R. Glass; Gary E. Glass; Peter J. Rennie

1979-01-01

207

Hall Effect in Ferromagnetics  

Microsoft Academic Search

Both the unusually large magnitude and strong temperature dependence of the extraordinary Hall effect in ferromagnetic materials can be understood as effects of the spin-orbit interaction of polarized conduction electrons. It is shown that the interband matrix elements of the applied electric potential energy combine with the spin-orbit perturbation to give a current perpendicular to both the field and the

Robert Karplus; J. M. Luttinger

1954-01-01

208

Quantum zeno effect  

Microsoft Academic Search

Misra and Sudarshan pointed out, based on the quantum measurement theory, that repeated measurements lead to a slowing down of the transition, which they called the quantum Zeno effect. Recently, Itano, Heinzen, Bollinger and Wineland have reported that they succeeded in observing that effect. We show that the results of Itano et al. can be recovered through conventional quantum mechanics

T. Petrosky; S. Tasaki; I. Prigogine

1990-01-01

209

A ''Voice Inversion Effect?''  

ERIC Educational Resources Information Center

Voice is the carrier of speech but is also an ''auditory face'' rich in information on the speaker's identity and affective state. Three experiments explored the possibility of a ''voice inversion effect,'' by analogy to the classical ''face inversion effect,'' which could support the hypothesis of a voice-specific module. Experiment 1 consisted…

Bedard, Catherine; Belin, Pascal

2004-01-01

210

The greenhouse effect  

Microsoft Academic Search

The greenhouse effect on the Earth is identified by the difference between the effective radiating temperature of the planet and its surface temperature. The difference between the energy emitted by the surface and that emitted upward to space by the upper atmosphere quantifies it; it can therefore be defined as the long wave energy trapped in the atmosphere. Climate forcing

A. Berger; Ch. Tricot

1992-01-01

211

The Greenhouse Effect  

Microsoft Academic Search

The Greenhouse Effect is getting a lot of publicity as concern grows about trends in weather and pollution. The midwestern states of the US suffered a drought during 1988 coupled with an unsually hot summer throughout the country. Many people attributed this to the Greenhouse Effect. Palmer and Brankovic (Nature, Vol. 338, page 54, March 2, 1989) tied the drought

2009-01-01

212

Effects on aquatic ecosystems  

Microsoft Academic Search

Regarding the effects of UV-B radiation on aquatic ecosystems, recent scientific and public interest has focused on marine primary producers and on the aquatic web, which has resulted in a multitude of studies indicating mostly detrimental effects of UV-B radiation on aquatic organisms. The interest has expanded to include ecologically significant groups and major biomass producers using mesocosm studies, emphasizing

D.-P. Häder; H. D. Kumar; R. C. Smith; R. C. Worrest

1998-01-01

213

Lake Effect Snow  

NSDL National Science Digital Library

This MPEG shows lake effect precipitation resulting when cold air masses pass over the relatively warm Great Lakes, pick up moisture, and then precipitate when again encountering the cold land surface. Note the bands of lake effect snow apparent over Lake Superior and the lack of snow on the western shore of Lake Michigan. The animation can be replayed to stress important points.

Nasa

214

The Chelate Effect Redefined.  

ERIC Educational Resources Information Center

Discusses ambiguities of the accepted definition of the chelate effect, suggesting that it be defined in terms of experimental observation rather than mathematical abstraction. Indicates that the effect depends on free energy change in reaction, ligand basicity, pH of medium, type of chelates formed, and concentration of ligands in solution. (JN)

da Silva, J. J. R. Frausto

1983-01-01

215

JPL Radiation Effects Facilities  

NASA Technical Reports Server (NTRS)

Radiation Effects Group investigates the effects of space radiation on present and future microelectronic and optoelectronic technologies, evaluate the risk of using them in specific space missions, and recommend component and design techniques for JPL and NASA programs to reduce reliability risk from space radiation.

Thorbourn, Dennis

2013-01-01

216

The greenhouse effect  

NASA Astrophysics Data System (ADS)

The greenhouse effect on the Earth is identified by the difference between the effective radiating temperature of the planet and its surface temperature. The difference between the energy emitted by the surface and that emitted upward to space by the upper atmosphere quantifies it; it can therefore be defined as the long wave energy trapped in the atmosphere. Climate forcing and the response of the climate system within which climate feedback mechanisms are contained, will be defined in this review. Quantitative examples will illustrate what could happen if the greenhouse effect is perturbed by the human activities, in particular if atmospheric CO2 concentrations would double in the future. Recent measurements by satellites of the greenhouse effect will be given. The net cooling effect of clouds on the Earth and whether or not there will be less cooling by clouds as the planet warms, are discussed following a series of papers recently published by Ramanathan and his collaborators.

Berger, A.; Tricot, Ch.

1992-11-01

217

Effective Frequency Technique  

NASA Technical Reports Server (NTRS)

An effective monochromatic frequency technique is described to represent the effects of finite spectral bandwidth for active and passive measurements centered on an absorption line, a trough region, or a slowly varying spectral feature. For Gaussian and rectangular laser line shapes, the effective frequency is shown to have a simple form which depends only on the instrumental line shape and bandwidth and not on the absorption line profile. The technique yields accuracies better than 0.1% for bandwidths less than 0.2 times the atmospheric line width.

Kirk, C. Laurence; Weng, Chi Y.

2002-01-01

218

Improving engineering effectiveness  

NASA Technical Reports Server (NTRS)

Methodologies to improve engineering productivity were investigated. The rocky road to improving engineering effectiveness is reviewed utilizing a specific semiconductor engineering organization as a case study. The organization had a performance problem regarding new product introductions. With the help of this consultant as a change agent the engineering team used a systems approach to through variables that were effecting their output significantly. Critical factors for improving this engineering organization's effectiveness and the roles/responsibilities of management, the individual engineers and the internal consultant are discussed.

Fiero, J. D.

1985-01-01

219

[Cholinergic effects of nootropics].  

PubMed

With respect to the enhancing effect of nootropics on learning and memory, the influence of some of these drugs on the high affinity choline uptake has been investigated. Meclofenoxate competes with choline uptake in vitro because of its similar side chain; other nootropics are without in vitro effects. A single dose of pramiracetam enhances the choline uptake in cortex and hippocampus. Application of meclofenoxate decreases the uptake of choline. Other nootropics lack acute effects. Possible increases of uptake after repeated dosage disappear within 24 h. PMID:3149192

Funk, K F; Schmidt, J

1988-01-01

220

From effective interactions to effective operators  

NASA Astrophysics Data System (ADS)

One of the most successful approaches to the nuclear structure of light nuclei is the no-core shell model (NCSM), which describes with very good precision the observed nuclear spectra. In its framework, by means of the Lee Suzuki procedure one derives effective interactions in finite model spaces starting from realistic nucleon-nucleon (NN) potentials; the low-lying energy spectrum is then obtain through the diagonalization of the ab initio effective interactions in large, translationally invariant, many-body basis. In addition to energy levels, one has to obtain good description of the nuclear wave functions; the latter can be tested by computing observables and transition strengths. With a few exceptions, transition strengths and expectation values of observables have been obtained using bare operators restricted to the model space. We have started recently to apply the Lee-Suzuki procedure to general operators and performed tests in restricted model spaces. In this work, we compute expectation values of selected scalar observables and electromagnetic transition strengths using realistic wave functions for nuclei in the p shell. I.S. and B.R.B acknowledge partial support by NFS grants PHY0070858 and PHY0244389. The work was performed in part under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. P.N. received support from LDRD contract 04-ERD-058.

Stetcu, Ionel; Barrett, Bruce R.; Navratil, Petr

2004-10-01

221

Authoring Effective Demonstrations.  

National Technical Information Service (NTIS)

The changing tactics of asymmetric threats present an ongoing need to disseminate lessons learned from the battlefield to a wide audience of personnel. Interactive virtual environments have been shown to be effective for team training, and distributed gam...

D. Fu E. Salas M. A. Rosen R. Jensen S. Ramachandran

2007-01-01

222

Explore Learning: Doppler Effect  

NSDL National Science Digital Library

This site contains a Shockwave interactive animation used to teach students about the wave motion specific to doppler effect. Users can change frequency, wave speed, as well as source and detector speeds.

2004-12-15

223

Vaccine herd effect  

PubMed Central

Vaccination ideally protects susceptible populations at high risk for complications of the infection. However, vaccines for these subgroups do not always provide sufficient effectiveness. The herd effect or herd immunity is an attractive way to extend vaccine benefits beyond the directly targeted population. It refers to the indirect protection of unvaccinated persons, whereby an increase in the prevalence of immunity by the vaccine prevents circulation of infectious agents in susceptible populations. The herd effect has had a major impact in the eradication of smallpox, has reduced transmission of pertussis, and protects against influenza and pneumococcal disease. A high uptake of vaccines is generally needed for success. In this paper we aim to provide an update review on the herd effect, focusing on the clinical benefit, by reviewing data for specific vaccines.

Kim, Tae Hyong; Johnstone, Jennie; Loeb, Mark

2011-01-01

224

UCAR: The Greenhouse Effect  

NSDL National Science Digital Library

This site by the University Corporation for Atmospheric Research (UCAR) provides an overview of the earth's atmospheric "greenhouse effect." Diagrams and one short video help present the key ideas. Two related activities are also provided.

2006-12-03

225

Aviation Noise Effects.  

National Technical Information Service (NTIS)

This report summarizes the effects of aviation noise in many areas, ranging from human annoyance to impact on real estate values. It also synthesizes the findings of literature on several topics. Included in the literature were many original studies carri...

J. S. Newman K. R. Beattie

1985-01-01

226

The Gravitational Edge Effect.  

National Technical Information Service (NTIS)

The knowledge that a gravity anomaly is due to an edge effect is sufficient to resolve the inherent ambiguity of the inverse potential problem. Thus given the gravity field across the contact between two laterally uniform structures, the density differenc...

L. M. Dorman

1974-01-01

227

[Genetic effects of radiation].  

PubMed

This paper is a short review of genetic effect of radiation. This includes methods and results of a large-scale genetic study on specific loci in mice and of various studies in the offspring of atomic-bomb survivors. As for the latter, there is no results obtained which suggest the effect of parental exposure to radiation. Further, in recent years, studies are conducted to the offspring born to parents who were survivors of childhood cancers. In several reports, the mean gonad dose is quite large whereas in most instances, the results do not indicate genetic effect following parental exposure to radiation. Possible reasons for the difficulties in detecting genetic effect of radiation are discussed. PMID:22514926

Nakamura, Nori

2012-03-01

228

Human Health Effects Assays.  

National Technical Information Service (NTIS)

The use of assays to evaluate and assist in predicting potentially adverse human health effects associated with exposure to pollutants in water (that is, municipal wastewater, sewage sludge, ambient water, and drinking water) is the focus of the review.

L. Fradkin C. Sonich-Mullin M. Cerny C. Kruger F. Cavender

1989-01-01

229

Radiation effects in space  

SciTech Connect

The paper discusses the radiation environment in space that astronauts are likely to be exposed to. Emphasis is on proton and HZE particle effects. Recommendations for radiation protection guidelines are presented. (ACR)

Fry, R.J.M.

1986-01-01

230

Substituent Effect in Ketoferrocenes.  

National Technical Information Service (NTIS)

The effect of carbonyl-group on the redox potential and Moessbauer parameters was studied in ketoferrocenes and chalcone analogous ferrocene derivatives. Interaction of electron-donating and electron-withdrawing substituents and the carbonyl-group is disc...

A. G. Nagy

1983-01-01

231

Metabolic Effects of Monomethylhydrazine.  

National Technical Information Service (NTIS)

The metabolic effects of monomethylhydrazine (MMH) were studied in rats using whole body calorimetry and measurements of serum and liver levels of fat and carbohydrate. Biochemical measurements were made in rats sacrificed three hours after injection of n...

H. L. Bitter D. A. Clark W. W. Lackey

1967-01-01

232

Managing for Effective Teaching.  

ERIC Educational Resources Information Center

In 20 schools, surveys of teacher perceptions about management styles and student perceptions of teachers reveals a correlation between effective teaching and "consultative-centralized" management. Consequently, 10 "commandments" for good consultative management are provided. (TE)

Greenblatt, Ruth B.; And Others

1984-01-01

233

Coefficients of Effective Length.  

ERIC Educational Resources Information Center

Under certain conditions, a validity Coefficient of Effective Length (CEL) can produce highly misleading results. A modified coefficent is suggested for use when empirical studies indicate that underlying assumptions have been violated. (Author/BW)

Edwards, Roger H.

1981-01-01

234

Indicators of Administrative Effectiveness.  

ERIC Educational Resources Information Center

Ten personal characteristics and seven administrative skills that differentiated effective from ineffective university leaders were assessed by multiple discriminate analysis. The personal characteristics identified by previous research (Skipper, 1975, 1977) are: responsibility, integrity, self-control, intellectual efficiency, flexibility,…

Skipper, Charles E.; Hofmann, Richard J.

235

Brookhaven Radiation Effects Facility.  

National Technical Information Service (NTIS)

The Neutral Particle Beam (NPB) Radiation Effects Facility (REF), funded by the Strategic Defense Initiative Office (SDIO) through the Defense Nuclear Agency (DNA) and the Air Force Weapons Laboratory (AFWL), has been constructed at Brookhaven National La...

C. L. Snead P. Grand T. Ward

1988-01-01

236

PPP Effectiveness Study.  

National Technical Information Service (NTIS)

This design note presents a study of the Procedures and Performance Program (PPP) effectiveness. The intent of the study is to determine manpower time savings and the improvements in job performance gained through PPP automated techniques. The discussion ...

J. D. Arbet R. L. Benbow

1976-01-01

237

Physiological Effects of Training.  

National Technical Information Service (NTIS)

With the evolution of exercise science a vast amount of information concerning the physiological effects of training has been generated. Understanding the basic training responses and adaptations of various modes of conditioning can give the clinician ins...

W. J. Kraemer W. L. Daniels

1985-01-01

238

Health Effects of Tsunamis  

MedlinePLUS

... for Pet Owners Frequently Asked Questions Additional Information Tornadoes Preparing for a Tornado (Part 1 of 2) ... Severe Weather Earthquakes Extreme Heat Floods Hurricanes Landslides Tornadoes Tsunamis Volcanoes Wildfires Winter Weather Health Effects of ...

239

Effectiveness of Glare Screens.  

National Technical Information Service (NTIS)

Available literature on glare screens was reviewed and selected installations were inspected. It was found that glare screens are effective but that warrants have not been established for their use. Expanded metal meshes are the most satisfactory of the a...

J. T. Capelli

1973-01-01

240

LUX0.1 Prototype Results: Cryogenics and Circulation  

NASA Astrophysics Data System (ADS)

LUX is a new dark matter direct detection experiment to be carried out at the Sanford Lab, the renewed underground facility at the Homestake mine in Lead, SD. The detector's large size supports effective internal shielding from natural radioactivity of the surrounding materials and environment. The LUX detector consists of a cylindrical vessel containing 350 kg of liquid xenon (LXe) cooled down using a novel cryogenic system. We tested a small-scale four PMT prototype utilizing over 300 gm of active xenon, installed in the full-sized cryostat. We report the efficiency of a unique internal heat exchanger with standard gas phase purification using a heated getter, which allows for very high flow purification without requiring large cooling power, as well as the efficiency of a thermosyphon-based cooling system. Such systems are required for multi-ton scale up. )

Bradley, Adam

2010-02-01

241

LUX Cryogenics and Circulation  

NASA Astrophysics Data System (ADS)

LUX is a new dark matter direct detection experiment being carried out at the Sanford Underground Research Facility, at the renewed Homestake mine in Lead, SD. The detector's large size supports effective internal shielding from natural radioactivity of the surrounding materials and environment. The LUX detector consists of a cylindrical vessel containing 350 kg of liquid xenon (LXe) cooled down and maintained at 175-K operating temperature using a novel cryogenic system. We report the efficiency of our thermosyphon-based cooling system, as well as the efficiency of a unique internal heat exchanger with standard gas phase purification using a heated getter, which allows for very high flow purification without requiring large cooling power. Such systems are required for multi-ton scale up.

Bradley, Adam

2012-10-01

242

UNDERGROUND EXPLOSION EFFECTS  

Microsoft Academic Search

Measurements were made of surface and subsurface effects of an ; underground explosion of a 1.2-kt nuclear burst. The measurements included free-; field earth and air-blast effects, as well as loading on underground structural ; devices. From the 76 channels installed on TEAPOT Shot 7, 75 usable records were ; obtained. The free-field quantities measured include air-blast pressure, earth ;

D. C. Sachs; L. M. Swift

1958-01-01

243

Nocturnal aircraft noise effects.  

PubMed

Noise protection associated with the construction and extension of airports in the Federal Republic of Germany has been regulated by the law for protection against aircraft noise since 1971. This legislation is due for revision because of different aspects. One aspect is the growth of air traffic which has led many airports to the limits of their capacity and in search of new ways of adaptation to the increasing demand for flight services. Another aspect is the increasing concern of the population about noise effects which has to be addressed by better protection against the effects of aircraft noise. The framework conditions of policy in terms of society as a whole, its health and economic environment need to be put into effect by political action. Science can contribute to this goal by performing noise effects research and by providing recommendations to the political body. However, it remains controversial, what measures are necessary or adequate to assure effective protection of the population against aircraft noise. This is particularly true for the protection of rest and sleep at night. The problem of finding a common basis for adequate recommendations is associated with (1) the low number of primary studies, which also exhibited highly variable results and assessments, (2) the handling of acoustic or psycho-acoustic dimensions for quantifying psychological or physiological reactions, and (3) the conception of how far preventive measures have to go to prove effective. With this in mind, the DLR Institute for Aerospace Medicine is conducting a large-scale, multi-stage study for investigating the acute effects of nocturnal aircraft noise on human sleep. This enterprise is implemented in the framework of the HGF/DLR project "Quiet Air Traffic" for developing sustainable assessment criteria for human-specific effects of aircraft noise at night. PMID:15070533

Basner, M; Samel, A

2004-01-01

244

Acid Rain Effects  

NSDL National Science Digital Library

Learners conduct a simple experiment to model and explore the harmful effects of acid rain (vinegar) on living (green leaf and eggshell) and non-living (paper clip) objects. Learners observe the effects over a period of days. This activity has links to other activities which can be combined to make a larger lesson. Resource contains vocabulary definitions and suggestions for assessment, extensions, and scaling for different levels of learners.

Kolenbrander, Amy; Yowell, Janet; Mach, Natalie; Zarske, Malinda S.; Carlson, Denise

2004-01-01

245

The Doppler Effect  

NSDL National Science Digital Library

This Flash animation provides a simulation of the Doppler effect. The user can change the speed of the wave source and can move a microphone to detect the wave frequency at different points relative to the moving source. The resulting wave pattern can be both observed and heard. Instructional notes outlining the details of the Doppler effect are provided. This material is part of a web site for a second semester physics course for majors covering gravity, fluids, waves, and thermodynamics.

Fowler, Michael; Welch, Heather

2008-07-31

246

Pleiotropic effects of pitavastatin  

PubMed Central

3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are established first line treatments for hypercholesterolaemia. In addition to the direct effects of statins in reducing concentrations of atherogenic low density lipoprotein cholesterol (LDL-C), several studies have indicated that the beneficial effects of statins may be due to some of their cholesterol-independent, multiple (pleiotropic) effects which may differ between different members of the class. Pitavastatin is a novel synthetic lipophilic statin that has a number of pharmacodynamic and pharmacokinetic properties distinct from those of other statins, which may underlie its potential pleiotropic benefits in reducing cardiovascular risk factors. This review examines the principal pleiotropic effects of pitavastatin on endothelial function, vascular inflammation, oxidative stress and thrombosis. The article is based on a systematic literature search carried out in December 2010, together with more recent relevant publications where appropriate. The available data from clinical trials and in vitro and animal studies suggest that pitavastatin is not only effective in reducing LDL-C and triglycerides, but also has a range of other effects. These include increasing high density lipoprotein cholesterol, decreasing markers of platelet activation, improving cardiac, renal and endothelial function, and reducing endothelial stress, lipoprotein oxidation and, ultimately, improving the signs and symptoms of atherosclerosis. It is concluded that the diverse pleiotropic actions of pitavastatin may contribute to reducing cardiovascular morbidity and mortality beyond that achieved through LDL-C reduction.

Davignon, Jean

2012-01-01

247

High Burnup Effects Program  

SciTech Connect

This is the final report of the High Burnup Effects Program (HBEP). It has been prepared to present a summary, with conclusions, of the HBEP. The HBEP was an international, group-sponsored research program managed by Battelle, Pacific Northwest Laboratories (BNW). The principal objective of the HBEP was to obtain well-characterized data related to fission gas release (FGR) for light water reactor (LWR) fuel irradiated to high burnup levels. The HBEP was organized into three tasks as follows: Task 1 -- high burnup effects evaluations; Task 2 -- fission gas sampling; and Task 3 -- parameter effects study. During the course of the HBEP, a program that extended over 10 years, 82 fuel rods from a variety of sources were characterized, irradiated, and then examined in detail after irradiation. The study of fission gas release at high burnup levels was the principal objective of the program and it may be concluded that no significant enhancement of fission gas release at high burnup levels was observed for the examined rods. The rim effect, an as yet unquantified contributor to athermal fission gas release, was concluded to be the one truly high-burnup effect. Though burnup enhancement of fission gas release was observed to be low, a full understanding of the rim region and rim effect has not yet emerged and this may be a potential area of further research. 25 refs., 23 figs., 4 tabs.

Barner, J.O.; Cunningham, M.E.; Freshley, M.D.; Lanning, D.D.

1990-04-01

248

Effective Transport Properties  

NASA Astrophysics Data System (ADS)

In this chapter we study a particular case of multiphase systems, namely two-phase materials in which one of the phases is randomly dispersed in the other, so that the composite can be viewed on a macroscale as an effective continuum, with well defined properties. In general, the theoretical determination of the parameter for an effective medium requires, as a rule, the solution of a corresponding transport problem at the microscale, which takes into account the morphology of the system and its evolution. As the mathematical problem is well-posed on a microscale, this can be accomplished using, for example, the multiple scale approach shown in Chap. 11 ; however, the task requires massive computations and is therefore difficult to implement from the practical standpoint. Here, instead, we focus on a deterministic approach to the problem, where the geometry and spatial configuration of the particles comprising the included phase are given and the solution to the microscale problem is therefore sought analytically. As examples, we study the effective thermal conductivity of solid reinforced materials (Sect. 10.1), the effective viscosity of non-colloidal suspensions (Sect. 10.2), the effective permeability of porous materials (10.3) and the effective self- and gradient diffusivities of colloidal suspensions (Sect. 10.4). Then, in Sect. 10.5, an alternative dynamic definition of the transport coefficients is considered, which can also serve as a basis to determine the effective properties of complex systems.

Mauri, Roberto

249

Mitochondrial threshold effects.  

PubMed Central

The study of mitochondrial diseases has revealed dramatic variability in the phenotypic presentation of mitochondrial genetic defects. To attempt to understand this variability, different authors have studied energy metabolism in transmitochondrial cell lines carrying different proportions of various pathogenic mutations in their mitochondrial DNA. The same kinds of experiments have been performed on isolated mitochondria and on tissue biopsies taken from patients with mitochondrial diseases. The results have shown that, in most cases, phenotypic manifestation of the genetic defect occurs only when a threshold level is exceeded, and this phenomenon has been named the 'phenotypic threshold effect'. Subsequently, several authors showed that it was possible to inhibit considerably the activity of a respiratory chain complex, up to a critical value, without affecting the rate of mitochondrial respiration or ATP synthesis. This phenomenon was called the 'biochemical threshold effect'. More recently, quantitative analysis of the effects of various mutations in mitochondrial DNA on the rate of mitochondrial protein synthesis has revealed the existence of a 'translational threshold effect'. In this review these different mitochondrial threshold effects are discussed, along with their molecular bases and the roles that they play in the presentation of mitochondrial diseases.

Rossignol, Rodrigue; Faustin, Benjamin; Rocher, Christophe; Malgat, Monique; Mazat, Jean-Pierre; Letellier, Thierry

2003-01-01

250

System Effectiveness Model Formulation  

SciTech Connect

Evaluation of system effectiveness has numerous pitfalls. System objectives may be poorly defined, may shift during the system life or may be hard to quantify. Further, individual perceptions of the quantifications may differ. Whatever the cause, system effectiveness has been an elusive term to quantitatively define. The proposed model presents a quantitative system effectiveness model and establishes a utilitarian approach for its use with the illustrative application to a nuclear safeguards system. The model uses the Type I and Type II statistical error rates as input to the component or subsystem effectiveness calculation which, when combined using a utilitarian methodology, quantify the overall system effectiveness. The methodology will use a survey of expert judgment to determine the relative importance of the individual subsystems through a statistically designed web survey. The web based survey will be available to nuclear material protection, control, and accounting experts attending the 2008 INMM conference. This model and methodology will provide a repeatable quantifiable measure for any system but in this case a simple safeguards system is used as an example.

Coates, Cameron W [ORNL; Jackson, Denise F [ORNL

2008-01-01

251

Liner environment effects study  

NASA Technical Reports Server (NTRS)

The Liner Environment Effects Study Program is aimed at establishing a broad heat transfer data base under controlled experimental conditions by quantifying the effects of the combustion system conditions on the combustor liner thermal loading and on the flame radiation characteristics. Five liner concepts spanning the spectrum of liner design technology from the very simple to the most advanced concepts are investigated. These concepts comprise an uncooled liner, a conventional film cooled liner, an impingement/film cooled liner, a laser drilled liner approaching the concept of a porous wall, and a siliconized silicon carbide ceramic liner. Effect of fuel type is covered by using fuels containing 11.8, 12.8, and 14% hydrogen. Tests at 100, 200, and 300 psia provide a basis for evaluating the effect of pressure on the heat transfer. The effects of the atomization quality and spray characteristics are examined by varying the fuel spray Sauter mean diameter and the spray angle. Additional varied parameters include reference velocity, a wide range of equivalence ratio, cooling flow rate, coolant temperature and the velocity of the coolant stream on the backside of the liner.

Venkataramani, K. S.; Ekstedt, E. E.

1984-01-01

252

Critical effects and exposure limits.  

PubMed

The use of critical effects in the determination of occupational exposure limits (OELs) in Sweden is subjected to a statistical study. Many of the present OELs are high in relation to known no-effect levels and effect levels, and the degree of protection has a surprisingly weak correlation with the seriousness of the adverse effect. Several proposals for improved procedures are put forward. One of these is to supplement the concept of critical effects with that of dominant effects. A dominant effect of a substance is a health effect that is at some concentration the most serious health effect. PMID:9202490

Hansson, S O

1997-04-01

253

Effective Nutritional Supplement Combinations  

NASA Astrophysics Data System (ADS)

Few supplement combinations that are marketed to athletes are supported by scientific evidence of their effectiveness. Quite often, under the rigor of scientific investigation, the patented combination fails to provide any greater benefit than a group given the active (generic) ingredient. The focus of this chapter is supplement combinations and dosing strategies that are effective at promoting an acute physiological response that may improve/enhance exercise performance or influence chronic adaptations desired from training. In recent years, there has been a particular focus on two nutritional ergogenic aids—creatine monohydrate and protein/amino acids—in combination with specific nutrients in an effort to augment or add to their already established independent ergogenic effects. These combinations and others are discussed in this chapter.

Cooke, Matt; Cribb, Paul J.

254

Aviation noise effects  

NASA Astrophysics Data System (ADS)

This report summarizes the effects of aviation noise in many areas, ranging from human annoyance to impact on real estate values. It also synthesizes the findings of literature on several topics. Included in the literature were many original studies carried out under FAA and other Federal funding over the past two decades. Efforts have been made to present the critical findings and conclusions of pertinent research, providing, when possible, a bottom line conclusion, criterion or perspective. Issues related to aviation noise are highlighted, and current policy is presented. Specific topic addressed include: annoyance; Hearing and hearing loss; noise metrics; human response to noise; speech interference; sleep interference; non-auditory health effects of noise; effects of noise on wild and domesticated animals; low frequency acoustical energy; impulsive noise; time of day weightings; noise contours; land use compatibility; and real estate values. This document is designed for a variety of users, from the individual completely unfamiliar with aviation noise to experts in the field.

Newman, J. S.; Beattie, K. R.

1985-03-01

255

Effective Documentation Tools  

NASA Technical Reports Server (NTRS)

Quality assurance programs provide a very effective means to monitor and evaluate medical care. Quality assurance involves: (1) Identify a problem; (2) Determine the source and nature of the problem; (3) Develop policies and methods to effect improvement; (4) Implement those polices; (5) Monitor the methods applied; and (6) Evaluate their effectiveness. Because this definition of quality assurance so closely resembles the Nursing Process, the health unit staff was able to use their knowledge of the nursing process to develop many forms which improve the quality of patient care. These forms include the NASA DFRC Service Report, the occupational injury form (Incident Report), the patient survey (Pre-hospital Evaluation/Care Report), the Laboratory Log Sheet, the 911 Run Sheet, and the Patient Assessment Stamp. Examples and steps which are followed to generate these reports are described.

Sleboda, Claire

1997-01-01

256

Heavy rain effects  

NASA Technical Reports Server (NTRS)

This paper summarizes the current state of knowledge of the effect of heavy rain on airplane performance. Although the effects of heavy rain on airplane systems and engines are generally known, only recently has the potential aerodynamic effect of heavy rain been recognized. In 1977 the United States Federal Aviation Administration (FAA) conducted a study of 25 aircraft accidents and incidents which occurred between 1964 and 1976 in which low-altitude wind shear could have been a contributing factor. Of the 25 cases (23 approach or landing and 2 take-off) in the study, ten cases had occurred in a rain environment, and in five cases these were classified as intense or heavy rain encounters. These results led to the reconsideration of high-intensity, short-duration rainfall as a potential weather-related aircraft safety hazard, particularly in the take-off and/or approach phases of flight.

Dunham, R. Earl, Jr.

1994-01-01

257

Giving effective presentations.  

PubMed

Apprehension about oral communication, or public speaking is rated as the number one fear among most individuals. Developing skill in, and comfort with, public speaking is important whether we are presenting oral reports and proposals, responding to questions, or training co-workers. Effective speakers are able to communicate information in a way that stimulates interest, helps the audience to understand and remember, and influences attitudes and behaviours. Many of us think that effective speakers are born rather than made. In truth most successful speakers work hard and invest a great deal of time and effort in to improving their speaking capabilities. Effective public speaking is a learned skill and activity that requires lots of practice. Like other learned skills, having a strategy with clear action steps can help you achieve your goal. PMID:15116467

Englehart, Nadine

2004-03-01

258

Disentangling the EMC effect  

NASA Astrophysics Data System (ADS)

The deep inelastic scattering cross section for scattering from bound nucleons differs from that of free nucleons. This phenomena, first discovered 30 years ago, is known as the EMC effect and is still not fully understood. Recent analysis of world data showed that the strength of the EMC effect is linearly correlated with the relative amount of Two-Nucleon Short Range Correlated pairs (2N-SRC) in nuclei. The latter are pairs of nucleons whose wave functions overlap, giving them large relative momentum and low center of mass momentum, where high and low is relative to the Fermi momentum of the nucleus. The observed correlation indicates that the EMC effect, like 2N-SRC pairs, is related to high momentum nucleons in the nucleus. This paper reviews previous studies of the EMC-SRC correlation and studies its robustness. It also presents a planned experiment aimed at studying the origin of this EMC-SRC correlation.

Piasetzky, E.; Hen, O.; Weinstein, L. B.

2013-10-01

259

Habituation of reinforcer effectiveness.  

PubMed

In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral- and neural-based explanations of reinforcement. We argue that HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009; Rankin etal., 2009). We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow) normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect "accelerated-HRE." Consideration of HRE is important for the development of effective reinforcement-based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior. PMID:24409128

Lloyd, David R; Medina, Douglas J; Hawk, Larry W; Fosco, Whitney D; Richards, Jerry B

2014-01-01

260

Handbook of radiation effects  

SciTech Connect

This book emphasizes radiation effects on solid state devices from exposure to the types of radiation found outside the atmosphere (in space, or in the vicinity of an exploding nuclear device). It contains a basic study of radiation shielding of payload components for payloads in space and specifically covers radiation effects on minority and majority carriers, optical media and organic materials. It also includes some basic information on radioactivity, monitoring equipment and different types of radiation fields. This book is not oriented toward health physics.

Holmes-Siedle, A.; Adams, L.

1993-12-31

261

Photostimulated even acoustoelectric effect  

NASA Astrophysics Data System (ADS)

Photostimulated photogalvanic (PG) and acoustogalvanic (AG) currents in a semiconductor placed in the field of two linearly polarized electromagnetic waves with frequencies Omega sub 1 = 2Omega sub 2 are analyzed. These currents affect the probability of electron scattering and the HF acoustic flux field. Under specified double laser illumination the system comprising an electron gas and photons becomes noncentrosymmetric, which leads to the PG and AG effects. The AG effect represents a contribution to the acoustoelectric current that is linear according to intensity and even according to the acoustic wave vector.

Shmelev, G. M.; Shon, N. Kh.; Tsurkan, G. I.

1985-02-01

262

Health Effects of Noise Pollution  

MedlinePLUS

... effects of noise pollution Health effects of noise pollution People of all ages, including children, teens, young ... noises around them. The health effects of noise pollution include: Hearing loss. Noise-induced hearing loss usually ...

263

Lightning Physics and Effects  

Microsoft Academic Search

Lightning Physics and Effects is not a lightning book; it is a lightning encyclopedia. Rarely in the history of science has one contribution covered a subject with such depth and thoroughness as to set the enduring standard for years, perhaps even decades, to come. This contribution covers all aspects of lightning, including lightning physics, lightning protection, and the interaction of

Richard E. Orville

2004-01-01

264

Effectively Communicating Qualitative Research  

ERIC Educational Resources Information Center

This article is a guide for counseling researchers wishing to communicate the methods and results of their qualitative research to varied audiences. The authors posit that the first step in effectively communicating qualitative research is the development of strong qualitative research skills. To this end, the authors review a process model for…

Ponterotto, Joseph G.; Grieger, Ingrid

2007-01-01

265

Cardiovascular effects of tadalafil  

Microsoft Academic Search

To determine the effects of tadalafil on the cardiovascular system, safety assessments were performed on a database of >4,000 subjects who received tadalafil in >60 clinical pharmacology, phase 2, phase 3, and open-label studies. In healthy subjects, tadalafil resulted in small changes in blood pressure, which are not believed to be clinically relevant. Daily administration of tadalafil 20 mg for

Robert A Kloner; Malcolm Mitchell; Jeffrey T Emmick

2003-01-01

266

Measuring Institutional Effectiveness.  

ERIC Educational Resources Information Center

The measurement of institutional effectiveness involves a systematic comparison of organizational purpose and performance. For community colleges, organizational purpose can be defined in terms of providing access to education, realizing student achievement, promoting student development, or addressing social needs. If all four purposes are…

Macomb County Community Coll., Warren, MI.

267

High Density Fuel Effects.  

National Technical Information Service (NTIS)

The purpose of this program was to determine, by combustor rig tests and data evaluation, the effects of the high density fuel properties on the performance and durability of the Allison T56-A-15 combustion system. Four high density fuels in addition to b...

H. C. Mongia N. K. Rizk P. T. Ross V. L. Oechsie

1988-01-01

268

Effective Thinking Outdoors.  

ERIC Educational Resources Information Center

Effective Thinking Outdoors (ETO) is an organization that teaches thinking skills and strategies via significant outdoor experiences. Identifies the three elements of thinking as creativity, play, and persistence; presents a graphic depiction of the problem-solving process and aims; and describes an ETO exercise, determining old routes of travel…

Hyde, Rod

1997-01-01

269

Effective View Navigation  

Microsoft Academic Search

In view navigation a user moves about an information structure by selecting something in the current view of the structure. This paper explores the implications of rudimentary requirements for effective view navigation, namely that, despite the vastness of an information structure, the views must be small, moving around must not take too many steps and the route to any target

George W. Furnas

1997-01-01

270

Commentary: Expanding on Effectiveness  

ERIC Educational Resources Information Center

Atkins, Graczyk, Frazier, and Abdul-Adil (2003) make the point that there have been three limitations of mental health services for children and families in low-income, urban settings: (a) accessibility; (b) effectiveness; and (c) sustainability. Their article focuses extensively on improving access and addressing issues of sustainability in…

Pelham, William E., Jr.; Massetti, Greta M.

2003-01-01

271

Interactive Pi Bonding Effects  

NSDL National Science Digital Library

This application demonstrates the effect of pi bonding on the one-electron ligand field splitting in an octahedral. By clicking on the appropriate buttons students can see how D changes when you move from ligands with no pi bonding capability to pi donor and pi acceptor ligands.

272

Camp's "Disneyland" Effect.  

ERIC Educational Resources Information Center

Describes the positive mental, physical, and social growth impacts that the camping experience had on the author, and urges camp program evaluation to plan and implement such changes. Sidebar lists steps of effective evaluation: program goals and objectives, goals of evaluation, implementation of evaluation, data analysis, and findings and…

Renville, Gary

1999-01-01

273

BIOLOGICAL EFFECTS OF MANGANESE  

EPA Science Inventory

The biological effects of manganese were studied in a town on the coast of Dalmatia in which a ferromanganese plant has been operating since before World War II. The study focused on the question of whether the exposure to manganese can cause a higher incidence of respiratory dis...

274

EFFECTS ON SALTWATER ORGANISMS  

EPA Science Inventory

The literature review summarizes current data on the effects of pesticides and metals on marine organisms, aquatic environmental research methods, bioaccumulation of pollutants by estuarine and marine organisms and in water/sediment residues and biota. Results of studies of the e...

275

Angular Talbot effect  

NASA Astrophysics Data System (ADS)

We predict the possibility of observing integer and fractional self-imaging (Talbot) phenomena on the discrete angular spectrum of periodic diffraction gratings illuminated by a suitable spherical wave front. Our predictions are experimentally validated, reporting what we believe to be the first observation of self-imaging effects in the far-field diffraction regime.

Azaña, José; Guillet de Chatellus, Hugues

2014-05-01

276

FIELD DISPERSANT EFFECTIVENESS TEST  

EPA Science Inventory

The EPA's OHMSETT facility has developed a rapid field test that includes some of the theoretical aspects and conditions of dispersion at sea. This Field Dispersant Effectiveness Test (FDET) has been used to evaluate the dispersibility of various commonly-transported oils and mak...

277

Physiological effects of hypnosis  

Microsoft Academic Search

There are many studies indicating that sensory, circulatory, gastrointestinal, and cutaneous functions can be altered by means of hypnosis. There also are many studies indicating that similar physiological effects can be produced by symbolic stimulation without hypnosis. The assumption that hypnotic behavior is a function of the trance state is open to question. From Psyc Abstracts 36:01:3II90B.

Theodore Xenophon Barber

1961-01-01

278

Cost Effective Prototyping  

NASA Technical Reports Server (NTRS)

This laboratory exercise seeks to develop a cost effective prototype development. The exercise has the potential of linking part design, CAD, mold development, quality control, metrology, mold flow, materials testing, fixture design, automation, limited parts production and other issues as related to plastics manufacturing.

Wickman, Jerry L.; Kundu, Nikhil K.

1996-01-01

279

Crossfield effect at fluxgate  

Microsoft Academic Search

The magnetic field transverse to the sensing axis may affect the performance of magnetic sensors. In the case of fluxgates, this effect is not as dramatic as it is for AMR sensors, but it still may cause errors up to 40 nT in the Earth's field. We performed measurements on voltage output fluxgate sensors of various constructions. Ring-cores are the

P Ripka; S. W Billingsley

2000-01-01

280

The offline production effect.  

PubMed

People remember words they say aloud better than ones they do not, a result called the production effect. The standing explanation for the production effect is that producing a word renders it distinctive in memory and thus memorable at test. Whereas it is now clear that motoric production benefits remembering over nonproduction, and that more intense motoric production benefits remembering to a greater extent than less intense motoric production, there has been no comparison of the memorial benefit conferred by motoric versus imagined production. One reason for the gap is that the standard production-by-vocalization procedure confounds the analysis. To make the comparison, we used a production-by-typing procedure and tested memory for words that people typed, imagined typing, and did not type. Whereas participants remembered the words that they typed and imagined typing better than words that they did not, they remembered the words they typed better than the ones they imagined typing; an advantage that was consistent over tests of recognition memory and source discrimination. We conclude that motoric production is a sufficient and facilitative (but not a necessary) condition to observe the production effect. We explain our results by a sensory feedback account of the production effect and sketch a computational framework to implement that approach. PMID:24364810

Jamieson, Randall K; Spear, Jackie

2014-03-01

281

Aviation noise effects  

Microsoft Academic Search

This report summarizes the effects of aviation noise in many areas, ranging from human annoyance to impact on real estate values. It also synthesizes the findings of literature on several topics. Included in the literature were many original studies carried out under FAA and other Federal funding over the past two decades. Efforts have been made to present the critical

J. S. Newman; K. R. Beattie

1985-01-01

282

Learning to Effect.  

ERIC Educational Resources Information Center

This book presents 14 papers which discuss contemporary issues of curriculum change and instructional effectiveness in higher education primarily from a British perspective. Papers address curriculum purpose, curriculum delivery, and curriculum impact on the wider society. In addition, the book covers experiential learning, skills and training,…

Barnett, Ronald, Ed.

283

Surface Effects Skimmer Developments.  

National Technical Information Service (NTIS)

This experimental program investigated the use of a Surface Effects Skimmer in removing thin film oil slicks spread over large water areas by fast currents. This new skimmer uses a directed air jet to separate and lift spilled oil from the surface of the ...

N. P. Trentacoste

1975-01-01

284

Tips for Effective Management  

ERIC Educational Resources Information Center

School business officials' days are filled with numbers and reports--audits, balance sheets, check registers, financial statements, journal entries, vouchers, and warrant reports, just to name a few. Those are all important tools that school business officers use to manage the financial resources of the district effectively. However, they are also…

Supple, Kevin F.

2009-01-01

285

Pleiotropic effects of incretins  

PubMed Central

Drugs that augment the incretin system [glucagon like peptide (GLP) agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors] represent a novel class of anti-hyperglycemic agents that have shown to improve the health and survival of beta-cells (improvement in postprandial hyperglycemia) and suppress glucagon (improvement in fasting hyperglycemia). The incretins represent a large family of molecules referred to as the “glucagon superfamily of peptide hormones” of which more than 90% of the physiological effects of incretins are accomplished by GLP-17-37 and GLP17-36 amide and gastric insulinotropic peptide (GIP). GLP-1 mediates its effects via the GLP-1 receptor, which has a wide tissue distribution [pancreas, lung, heart, vascular smooth muscle cells, endothelial cells, macrophages and monocytes, kidney, gastrointestinal tract (stomach and intestine), central nervous system (neoortex, cerebellum, hypothalamus, hippocampus, brainstem nucleus tractus solitarius) and peripheral nervous system]. This would imply that the incretin system has effects outside the pancreas. Over time data has accumulated to suggest that therapies that augment the incretin system has beneficial pleiotrophic effects. The incretins have shown to possess a cardiac-friendly profile, preserve neuronal cells and safeguard from neuronal degeneration, improve hepatic inflammation and hepatosteatosis, improve insulin resistance, promote weight loss and induce satiety. There is growing evidence that they may also be renoprotective promoting wound healing and bone health.

Gupta, Vishal

2012-01-01

286

Effectiveness of Median Barriers.  

National Technical Information Service (NTIS)

The objective of this study was to ascertain whether the employment of physical barriers within the highway median is effective in promoting highway safety. An uncontrolled before and after study of 54.2 miles of urban freeway in California was conducted ...

R. T. Johnson

1964-01-01

287

Lorenz Attractor -- Butterfly Effect  

NSDL National Science Digital Library

The "Butterfly Effect", or more technically the "sensitive dependence on initial conditions", is the essence of chaos. This is illustrated an applet of the Lorenz Attractor. The demonstration shows a graphical representation of the time variation of three variables X(t),Y(t) and Z(t), coupled by non-linear evolution equations.

Michael Cross, Cal T.

288

Space Environmental Effects Knowledgebase  

NASA Technical Reports Server (NTRS)

This report describes the results of an NRA funded program entitled Space Environmental Effects Knowledgebase that received funding through a NASA NRA (NRA8-31) and was monitored by personnel in the NASA Space Environmental Effects (SEE) Program. The NASA Project number was 02029. The Satellite Contamination and Materials Outgassing Knowledgebase (SCMOK) was created as a part of the earlier NRA8-20. One of the previous tasks and part of the previously developed Knowledgebase was to accumulate data from facilities using QCMs to measure the outgassing data for satellite materials. The main object of this current program was to increase the number of material outgassing datasets from 250 up to approximately 500. As a part of this effort, a round-robin series of materials outgassing measurements program was also executed that allowed comparison of the results for the same materials tested in 10 different test facilities. Other programs tasks included obtaining datasets or information packages for 1) optical effects of contaminants on optical surfaces, thermal radiators, and sensor systems and 2) space environmental effects data and incorporating these data into the already existing NASA/SEE Knowledgebase.

Wood, B. E.

2007-01-01

289

Microcircuit Radiation Effects Databank.  

National Technical Information Service (NTIS)

Radiation test data submitted by many testers is collated to serve as a reference for engineers who are concerned with and have some knowledge of the effects of the natural radiation environment on microcircuits. Total dose damage information and single e...

1983-01-01

290

Cardiovascular effects of melanocortins  

Microsoft Academic Search

Melanocortins (MSH's) are three structurally related peptides derived from proopiomelanocortin. They regulate several physiologic functions including energy metabolism, appetite, and inflammation. Recent work in rodents has also identified important effects of MSH's, particularly ?-MSH, on sodium metabolism and blood pressure regulation. Normal rats and mice respond to a high sodium diet with an increase in the plasma concentration of ?-MSH,

Michael H. Humphreys; Xi-Ping Ni; David Pearce

2011-01-01

291

(Limiting the greenhouse effect)  

Microsoft Academic Search

Traveler attended the Dahlem Research Conference organized by the Freien Universitat, Berlin. The subject of the conference was Limiting the Greenhouse Effect: Options for Controlling Atmospheric COâ Accumulation. Like all Dahlem workshops, this was a meeting of scientific experts, although the disciplines represented were broader than usual, ranging across anthropology, economics, international relations, forestry, engineering, and atmospheric chemistry. Participation by

Rayner

1991-01-01

292

Noise: Effects and Control.  

National Technical Information Service (NTIS)

The type and degree of the effects on man of exposure to high-intensity noise is determined primarily by (1) the type of noise, i.e., continuous or interrupted, (2) the spectrum of the noise, i.e., low or high pitch, (3) intensity (loudness), (4) length o...

K. K. Neely

1965-01-01

293

The Contrail Effect  

NSDL National Science Digital Library

NOVA's The Contrail Effect describes how contrails form and how humidity determines how long they last. The webpage goes on to describe the study during the days of clear skies, without contrails, following 9/11. Three satellite images of contrail patterns are provided.

Foundation, Wgbh E.

2011-09-15

294

Documentation: Effective AND Literate  

Microsoft Academic Search

The purpose of this paper is to show how documentation can be literate, in a stylistic sense, and still be effective. Literate prose is a powerful tool that, when properly used in computer documentation, can take advantage of the full power of the English language. This does not mean that all computer documentation must or can read like a Nobel

Paul S. Burdett Jr.

1985-01-01

295

Effects of acoustic sources  

Microsoft Academic Search

An experiment was conducted to determine the effect of acoustics on the laminar flow on the side of a nacelle. A flight test was designed to meet this goal and a brief review of the purpose is given. A nacelle with a significant length of laminar flow was mounted on the wing of NASA OV-1. Two noise sources are also

James A. Schoenster; Michael G. Jones

1987-01-01

296

Effective resonance levels  

Microsoft Academic Search

A method based on the use of effective resonance integrals or group cross sections with resonance self-shielding factors has come into extensive use in calculations of resonance absorption in homogeneous systems. An attempt is made to extend the subgroup treatment, which was initially formulated for the region of forbidden resonances, to the allowed region as applicable to heterogeneous media. A

B. P. Kochurov

1986-01-01

297

Field effect transistors  

Microsoft Academic Search

A patent is claimed for an invention relating to Metal Insulator Semiconductor Field Effect Transistors (MISFECTs) in which organic polymers are used as the semiconducting component. The FET has a gate electrode deposited on a substrate and separated from a semiconducting layer by an insulating layer, the semiconducting layer being provided with two terminals to allow passage of an electric

Philip Charles Allen; Richard Henry Friend; Jeremy Henly Burroughes

1988-01-01

298

Exploring the Lotus Effect  

NSDL National Science Digital Library

Students test and observe the "self-cleaning" lotus effect using a lotus leaf and cloth treated with a synthetic lotus-like superhydrophobic coating. They also observe the Wenzel and Cassie Baxter wetting states by creating and manipulating condensation droplets on the leaf surface. They consider the real-life engineering applications for these amazing water-repellent and self-cleaning properties.

NSF CAREER Award and RET Program, Mechanical Engineering and Material Science,

299

Cardiovascular effects of alcohol.  

PubMed Central

The effects of alcohol on the heart include modification of the risk of coronary artery disease, the development of alcoholic cardiomyopathy, exacerbation of conduction disorders, atrial and ventricular dysrhythmias, and an increased risk of hypertension, hemorrhagic stroke, infectious endocarditis, and fetal heart abnormalities.

Davidson, D M

1989-01-01

300

DCPS Effective Schools Framework  

ERIC Educational Resources Information Center

DCPS is committed to providing "all" students with the caliber of education they deserve. The goal of the DCPS Effective Schools Framework is to ensure that every child, in every classroom, has access to a high-quality and engaging standards-based instructional program, and that all school supports are aligned to support teaching and learning. The…

District of Columbia Public Schools, 2009

2009-01-01

301

Alexandrite effect spectropyrometer  

NASA Astrophysics Data System (ADS)

Alexandrite crystal is commonly used for making alexandrite laser, and it also has a less-known phenomenon called the alexandrite effect that refers to the color change between different light sources. A novel spectropyrometer for temperature measurement of a radiating body utilizing the alexandrite effect is introduced. The alexandrite effect method for temperature measurement is based on the relationship between the temperature of blackbody and the hue-angle in the CIELAB color space. The alexandrite effect spectropyrometer consists of an optical probe, a spectrometer, a computer, and an alexandrite filter. It measures the spectral power distribution of a radiating body through the alexandrite filter, calculates the hue-angle, and determines the temperature. The spectropyrometer is suitable for temperature measurement of any radiating body with or without spectral lines in its spectral power distribution from 1000 K to 100000 K. The spectropyrometer is particularly useful for high to ultrahigh temperature measurement of any radiating bodies with spectral line emissions, such as electric arcs and discharges, plasmas, and high temperature flames.

Liu, Yan

2006-08-01

302

Confirming Testlet Effects  

ERIC Educational Resources Information Center

A testlet is a cluster of items that share a common passage, scenario, or other context. These items might measure something in common beyond the trait measured by the test as a whole; if so, the model for the item responses should allow for this testlet trait. But modeling testlet effects that are negligible makes the model unnecessarily…

DeMars, Christine E.

2012-01-01

303

Effects of New Technologies.  

ERIC Educational Resources Information Center

This group of articles studies the effects of microelectronics technologies on the world of work and on the social and economic life in general. These studies are related to several industrial nations and are also concerned with the international division of labor. (SSH)

Social and Labour Bulletin, 1983

1983-01-01

304

Effective classical partition functions  

NASA Astrophysics Data System (ADS)

We present a method by which a quantum-mechanical partition function can be approximated from below by an effective classical partition function. The associated potential is obtained by a simple smearing procedure. For a strongly anharmonic oscillator and a double-well potential, the lowest approximation gives a free energy which is accurate to a few percent, even at zero temperature.

Feynman, R. P.; Kleinert, H.

1986-12-01

305

Determinants of Managerial Effectiveness.  

ERIC Educational Resources Information Center

Factors which contribute to managerial effectiveness can be grouped into four major categories: (1) personal characteristics of the individual manager; (2) managerial functions or the managerial process; (3) the various components of the organizational environment; and (4) the outcomes or results of the managerial process. (Author)

Foxley, Cecelia H.

1980-01-01

306

Knowledge Sharing Effectiveness Measurement  

Microsoft Academic Search

Knowledge would be considered as important element in knowledge-based economy and it makes a strong competitive advantage in dynamic business environment. In knowledge management, knowledge sharing is the most critical elements of effective knowledge processing. Several studies have been done to explain why people share knowledge and some of them have been mentioned in this paper. The next issue is

B. Zadjabbari; Pornpit Wongthongtham; Farookh Khadeer Hussain

2010-01-01

307

Stern-Gerlach effect  

NSDL National Science Digital Library

This web page illustrates the Stern-Gerlach effect on spin 1/2 particles. Movies and an illustration show the time-dependent properties of wavepackets in an inhomogeneous magnetic field. Examples are given for silver atoms, ions, and electrons.

De Raedt, Hans; Michielsen, Kristel

2010-03-11

308

Facilitating Online Discussions Effectively  

ERIC Educational Resources Information Center

This article presents a synthesis of the theoretical and research literature on facilitating asynchronous online discussions effectively. Online courses need to be designed so that they provide motivation for students to engage in productive discussions and clearly describe what is expected, perhaps in the form of a discussion rubric.…

Rovai, Alfred P.

2007-01-01

309

Explaining Charter School Effectiveness  

ERIC Educational Resources Information Center

This study uses entrance lotteries to explore heterogeneity in the achievement effects of charter schools across demographic groups and between urban and non-urban areas in Massachusetts. The authors develop a framework for interpreting this heterogeneity using both student- and school-level explanatory variables. (Contains 4 tables.)

Angrist, Joshua D.; Pathak, Parag A.; Walters, Christopher R.

2012-01-01

310

Cuing Effect of \\  

Microsoft Academic Search

It is generally acknowledged that alternatives such as none of the above and all of the above should be used sparingly in multiple-choice (MC) items. But the effect that all of the above has on the reliability and validity of an MC item is unclear This study compared the results of a single-response (SRa) item format that included all of

P. H. Harasym; E. J. Leong; C. Violato; R. Brant; F. L. Lorscheider

1998-01-01

311

Matthew Effects for Whom?  

ERIC Educational Resources Information Center

Which children are most at risk of experiencing a Matthew effect in reading? We investigated this question using population-based methodology. First, we identified children entering kindergarten on socio-demographic factors (i.e., gender, race/ethnicity, and socioeconomic status) known to index the relative risks and resources available to them as…

Morgan, Paul L.; Farkas, George; Hibel, Jacob

2008-01-01

312

Teacher Effectiveness: A Position.  

ERIC Educational Resources Information Center

This document summarizes the highlights of research on teacher effectiveness and concludes with recommendations based on a synthesis of this past work. The various methodologies that have been used are discussed, from rating scales to objective observation techniques, such as OScAR and the ecological studies. The major problems in teacher…

Scott, Myrtle

1969-01-01

313

Brain effects of melanocortins.  

PubMed

The melanocortins (alpha, beta and gamma-melanocyte-stimulating hormones: MSHs; adrenocorticotrophic hormone: ACTH), a family of pro-opiomelanocortin (POMC)-derived peptides having in common the tetrapeptide sequence His-Phe-Arg-Trp, have progressively revealed an incredibly wide range of extra-hormonal effects, so to become one of the most promising source of innovative drugs for many, important and widespread pathological conditions. The discovery of their effects on some brain functions, independently made by William Ferrari and David De Wied about half a century ago, led to the formulation of the term "neuropeptide" at a time when no demonstration of the actual production of peptide molecules by neurons, in the brain, was still available, and there were no receptors characterized for these molecules. In the course of the subsequent decades it came out that melanocortins, besides inducing one of the most complex and bizarre behavioural syndromes (excessive grooming, crises of stretchings and yawnings, repeated episodes of spontaneous penile erection and ejaculation, increased sexual receptivity), play a key role in functions of fundamental physiological importance as well as impressive therapeutic effects in different pathological conditions. If serendipity had been an important determinant in the discovery of the above-mentioned first-noticed extra-hormonal effects of melanocortins, many of the subsequent discoveries in the pharmacology of these peptides (feeding inhibition, shock reversal, role in opiate tolerance/withdrawal, etc.) have been the result of a planned research, aimed at testing the "pro-nociceptive/anti-nociceptive homeostatic system" hypothesis. The discovery of melanocortin receptors, and the ensuing synthesis of selective ligands with agonist or antagonist activity, is generating completely innovative drugs for the treatment of a potentially very long list of important and widespread pathological conditions: sexual impotence, frigidity, overweight/obesity, anorexia, cachexia, haemorrhagic shock, other forms of shock, myocardial infarction, ischemia/reperfusion-induced brain damage, neuropathic pain, rheumathoid arthritis, inflammatory bowel disease, nerve injury, toxic neuropathies, diabetic neuropathy, etc. This review recalls the history of these researches and outlines the pharmacology of the extra-hormonal effects of melanocortins which are produced by an action at the brain level (or mainly at the brain level). In our opinion the picture is still incomplete, in spite of being already so incredibly vast and complex. So, for example, several of their effects and preliminary animal data suggest that melanocortins might be of concrete effectiveness in one of the areas of most increasing concern, i.e., that of neurodegenerative diseases. PMID:18996199

Bertolini, Alfio; Tacchi, Raffaella; Vergoni, Anna Valeria

2009-01-01

314

ENVIRONMENTAL RESIDUE EFFECTS DATABASE (ERED)  

EPA Science Inventory

US Army Corps of Engineers public web site for the "Environmental Residue Effects Database", a searchable database of adverse biological effects associated with tissue concentrations of various contaminants....

315

Latent effects decision analysis  

DOEpatents

Latent effects on a system are broken down into components ranging from those far removed in time from the system under study (latent) to those which closely effect changes in the system. Each component is provided with weighted inputs either by a user or from outputs of other components. A non-linear mathematical process known as `soft aggregation` is performed on the inputs to each component to provide information relating to the component. This information is combined in decreasing order of latency to the system to provide a quantifiable measure of an attribute of a system (e.g., safety) or to test hypotheses (e.g., for forensic deduction or decisions about various system design options).

Cooper, J. Arlin (Albuquerque, NM) [Albuquerque, NM; Werner, Paul W. (Albuquerque, NM) [Albuquerque, NM

2004-08-24

316

Doppler Effect Model  

NSDL National Science Digital Library

The Doppler Effect model demonstrates the shift in frequency of a wave that is produced by the motion of either the wave source or the observer of the wave (or both). In this simulation, you can explore the change in the wave that is produced by source and/or observer motion, and you can even view what the situation looks like from the perspective of the medium (the standard reference frame), the source, or the observer. The Doppler Effect model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_Doppler.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-25

317

Nonequilibrium effects and baryogenesis  

SciTech Connect

Possible effects due to nonequilibrium dynamics in the Affleck-Dine mechanism of baryogenesis are examined. Using the closed-time-path formalism, the quantum fluctuation and the backreaction of the Affleck-Dine scalar field are incorporated self-consistently into the dynamical equations of the system by invoking a nonperturbative Hartree approximation. It is found that such nonequilibrium effects can significantly affect the amount of baryon asymmetry that can be generated. In particular, it is possible to generate the observed baryon asymmetry with suitable initial conditions. The methodology described in this paper as well as some of the results obtained are quite general, and can be applied to any complex scalar field in a cosmological background.

Charng, Y.-Y.; Ng, K.-W. [Institute of Physics, Academia Sinica, Taipei, Taiwan 115 (China); Lee, D.-S. [Department of Physics, National Dong Hwa University, Hua-Lien, Taiwan 974 (China); Theory Group, Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom); Leung, C.N. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States)

2005-12-15

318

Postantifungal effect methods.  

PubMed

Postantifungal effect (PAFE) is the evaluation of antifungal activity after the suppression of fungal growth when the drug is removed from the fungal suspension. In vitro, this effect might simulate the in vivo situation when the concentration of the drug falls to less than the minimum inhibitory concentration values and could be another tool, together with the classic in vitro susceptibility tests, to optimize the interaction of drugs-fungi. In this chapter, two model methods to evaluate the PAFE of yeasts and filamentous fungi are described in which practical advices and tricks are given to help the worker to develop the techniques. The procedures outlined include preparation of stock solutions of the drugs, concentration medium, exposure time colony count determination, and interpretation of the results to quantify the PAFE. PMID:15888941

Vitale, Roxana G

2005-01-01

319

The Energy Diameter Effect  

NASA Astrophysics Data System (ADS)

We explore various relations for the detonation energy and velocity as they relate to the inverse radius of the cylinder. The effective detonation rate-inverse slope relation seen in reactive flow models can be used to derive the familiar Eyring equation. Generalized inverse radii can be shown to fit large quantities of cylinder results. A rough relation between detonation energy and detonation velocity is found from collected JWL values. Cylinder test data for ammonium nitrate mixes down to 6.35 mm radii are presented, and a size energy effect is shown to exist in the Cylinder test data. The relation that detonation energy is roughly proportional to the square of the detonation velocity is shown by data and calculation.

Vitello, Peter; Garza, Raul; Hernandez, Andy; Souers, P. Clark

2007-12-01

320

[Herbs and cardiotoxic effects].  

PubMed

Accidental or deliberate ingestion of poisonous herbs has become an increasingly common phenomenon over the last years. From existing literature data and case reports from emergency room visits or poison control centers, an overview is presented of the potential cardiotoxic manifestations following intoxication by wild herbal plants of the territory. The effects of the consumption of cardiac glycoside-containing plants (e.g., digitalis) are discussed along with tachyarrhythmias induced by Aconitum napellus L., Atropa belladonna L., Mandragora officinarum L. or Ephedra distachya L. herbs, and hypertensive crises associated with licorice abuse. For each plant, a brief historical and botanical background is provided, focusing on pathophysiology of intoxication and cardiotoxic effects on the basis of the most recent literature. Finally, medical management of intoxication, from both a general and cardiological viewpoint, is reviewed. PMID:23748541

Maffè, Stefano; Paffoni, Paola; Laura Colombo, Maria; Davanzo, Franca; Dellavesa, Pierfranco; Cucchi, Lorenzo; Zenone, Franco; Paino, Anna Maria; Franchetti Pardo, Nicolò; Bergamasco, Luca; Signorotti, Fabiana; Parravicini, Umberto

2013-06-01

321

Fire Effects Information System  

NSDL National Science Digital Library

The Fire Effects Information System (FEIS) provides up-to-date information about fire effects on plants and animals. It was developed at the USDA Forest Service Rocky Mountain Research Station's Fire Sciences Laboratory in Missoula, Montana. The FEIS database contains synoptic descriptions, taken from current English-language literature of almost 900 plant species, about 100 animal species, and 16 Kuchler plant communities found on the North American continent. The emphasis of each synopsis is fire and how it affects each species. Background information on taxonomy, distribution, basic biology and ecology of each species is also included. Synopses are thoroughly documented, and each contains a complete bibliography. Personnel from several land management agencies (USDA Forest Service, USDI-BIA, NPS, BLM, F&WS) identified the species to be included in the database. Those agencies funded the original work and continue to support maintenance and updating of the database.

1995-12-12

322

Effective Vaccination Policies  

PubMed Central

We present a framework for modeling the spread of pathogens throughout a population and generating policies that minimize the impact of those pathogens on the population. This framework is used to study the spread of human viruses between cities via airplane travel. It combines agent-based simulation, mathematical analysis, and an Evolutionary Algorithm (EA) optimizer. The goal of this study is to develop tools that determine the optimal distribution of a vaccine supply in the model. Using plausible benchmark vaccine allocation policies of uniform and proportional distribution, we compared their effectiveness to policies found by the EA. We then designed and tested a new, more effective policy which increased the importance of vaccinating smaller cities that are flown to more often. This “importance factor” was validated using U.S. influenza data from the last four years.

Shaw, L.; Spears, W.; Billings, L.; Maxim, P.

2010-01-01

323

Cardiac effects of thyronamines.  

PubMed

3-Iodothyronamine (T(1)AM) is an endogenous compound derived from thyroid hormone through decarboxylation and deiodination, which interacts with a novel G protein-coupled receptor, known as trace amine-associated receptor 1 (TAAR1). TAAR1 and other receptors of this family are expressed in several tissues, including the heart. Functional effects have been observed after administration of exogenous T(1)AM: in the isolated heart, a negative inotropic and chronotropic action was produced, and the resistance to ischemic injury was increased, possibly as a consequence of an action on intracellular calcium homeostasis. Extracardiac effects include reduction of body temperature, increased lipid versus carbohydrate metabolism, and modulation of insulin secretion. T(1)AM might play an important physiological or pathophysiological role, and this signaling system might allow the development of new therapeutical agents. PMID:19016324

Zucchi, Riccardo; Ghelardoni, Sandra; Chiellini, Grazia

2010-03-01

324

The Dufour effect  

Microsoft Academic Search

Equations for the Dufour effect, which is the development of a temperature gradient due to diffusion, have been solved for geometrically well-defined cells which have either all walls adiabatic or adiabatic lateral walls and diathermic ends. Two self-consistent, well-ordered perturbation schemes have been used, and heat of mixing, variability of all properties, and the barycentric velocity are included explicitly. For

Sara E. Ingle; Frederick H. Horne

1973-01-01

325

Power electronics' polluting effects  

Microsoft Academic Search

In use far and wide for improved delivery and control of the electricity supply, power electronics systems are both the cause and remedy of the power system harmonic pollution problem. Here, the authors describe how an insidious side-effect of any solution involving power electronics converters is their generation of high-frequency pollution-namely, conducted and radiated noise in the 100 kHz to

R. Redl; P. Tenti; J. Daan van Wyk

1997-01-01

326

The Kaye effect  

NASA Astrophysics Data System (ADS)

The International Young Physicists' Tournament (IYPT) is a worldwide, annual competition for secondary school students. This is our solution to problem number 10, The Kaye effect, as presented in the final round of the 21st IYPT in Trogir, Croatia. The Kaye effect occurs when a thin stream of shampoo or a different adequate non-Newtonian liquid is poured onto a surface. Suddenly, a jet leaves the heap that is formed by the shampoo and begins to 'dance' around the primary jet like a lasso. The phenomenon ends when the 'dancing' jet hits the primary jet and subsequently collapses. We started our investigations based on available literature (Kaye 1963 Nature 197 1001, Versluis et al 2006 J. Stat. Mech., Collyer and Fischer 1976 Nature 261 682). We made experiments with a similar experimental set-up in which we could determine the velocities of both shampoo streams as well as the angle of the 'dancing' stream. From there on, we developed a theoretical model for the energy loss of the jet in the heap. We discovered that the air layer between the jet and the heap is a necessity for the Kaye effect to occur. At this point, our observations differ from the aforementioned literature. This also accounts for the shampoo beam acting as a light guide. Further experiments concerning the viscoelasticity of the shampoo revealed that the elastic property of the shampoo is necessary for the effect to occur. This article is a written version of the oral contribution of the German team to the 21st IYPT competition, which was awarded first prize by an international jury. The article has been edited by European Journal of Physics.

Binder, J. M.; Landig, A. J.

2009-11-01

327

Temporary Retinal Effects  

Microsoft Academic Search

IN your present week's ``Notes'' you have referred to the curious experiences of MM. Macé de Lepinay and Nicati, in finding the town lights appear green, after five hours among snow-fields. On the Cima di Jazi, some 16,000 feet or more high, I found another effect. On removing my blue snow-glasses, the sky (at about 10 a.m.) appeared of the

J. Rand Capron

1882-01-01

328

SGEMP Geometry Effects  

Microsoft Academic Search

Self-consistent, fully dynamic computer calculations were performed using the recently developed arbitrary body-of-revolution code ABORC for complex geometries in SGEMP environments to test the validity of simplifying geometry assumptions previously made in the solutions of these problems. Assumptions such as simple geometry representations of complex bodies and separability of inside and outside problems are tested. Effects of gaps, interior electrical

A. J. Woods; E. P. Wenaas

1975-01-01

329

The Effects of Outliers  

NSDL National Science Digital Library

Created by Illuminations: Resources for Teaching Mathematics, this lesson is designed to help students understand the significance of outliers. This lesson includes thought questions and an applet to help students visualize the effect of an outlier. The authors divide the lesson into different groups, they include: learning objectives, materials, instructional plans, NCTM standards/expectations, and finally references. This is a great interactive resource for those wanting to learn more about correlation and regression.

2009-01-01

330

Writing Effective TAFs  

NSDL National Science Digital Library

This module provides an overview of some of the applicable TAF Amendment and Conditional Group usage rules, as presented in the latest version of the National Weather Service Instruction 10-813 on TAF directives. It also presents a methodology for TAF writing and development that will lead to an effective and user-friendly product. The focus is on the ceiling and visibility aspects of the TAF. This module is part of the Distance Learning Course 1: Forecasting Fog and Low Stratus

Spangler, Tim

2003-06-28

331

Extra Housepayments Effect  

NSDL National Science Digital Library

How financial institutions use the monthly mortgage payment and mortgage amortization formulas can be a confusing concept to grasp. This lesson asks students to find a current interest mortgage rate for their city and state. This rate is then applied to an Internet based mortgage calculator to discover the effect that paying extra on a monthly house payment has on total interest paid and length of the loan. A student worksheet is included in the document.

2011-01-05

332

Electromechanical Effects in  

Microsoft Academic Search

Electric fields Can induce mechanical vibratiam in plattar aligned sandwich cells of ferroelectric liquid crystals. L.Measurements on a polysiloxane and a polyacy~aie side chain polymer proved that the rlectromechanical effect also exists in frrroelcctric liquid cystallinc polymers. fie main characteristics of the eiectromed~anical res- ponses of fhese polymers are described and compared to the response of low molecu2ur weight fcrroelectric

Ferroelectric Liquid; Crystalline Polymers; Antal Jbklit; Laios Bafa

333

Transgenerational Effects of NMs.  

PubMed

Nanomaterials are present in a number of commercially available products but there are uncertainties as to whether the unique properties that support their commercial use may also pose potential health risks. Information is missing concerning the influence of nanomaterials on the overall reproductive outcome and transgenerational effects in animals and plants. To obtain this information, long-term studies would be required using animal models phylogenetically close to humans and exposure conditions that reflect realistic scenarios with regard to dosages and admission. The nanoreprotoxicology literature published to date is largely descriptive in nature regarding the effects of nanoparticles. The mechanisms, which determine particle reproduction compatibility, are mostly elusive at the moment. Thus, it is recommended that future research explore the interactions between nanomaterials and transgenerational matter on a molecular level. It would, for instance, be of major importance to understand the behaviour of nanoparticles inside the cells but also their genotoxic and epigenetic effects. Recent studies have shown that intravenous and/or intra-abdominal administration of nanoparticles to mice results in their accumulation in the cells of many tissues, including the brain and the testis, suggesting that they easily pass through the blood-brain and blood-testis barriers. In parallel embryo development after exposure to nanoparticles should be comparatively investigated. The majority of studies on embryo toxicology have concentrated on piscine embryos, mostly derived from zebrafish. Plants for human food as an important component of the ecosystem need also to be taken into account when evaluating transgenerational effects of engineered nanomaterials in crops. PMID:24683035

Poma, Anna; Colafarina, Sabrina; Fontecchio, Gabriella; Chichiriccò, Giuseppe

2014-01-01

334

Neuroprotective effects of creatine  

Microsoft Academic Search

There is a substantial body of literature, which has demonstrated that creatine has neuroprotective effects both in vitro\\u000a and in vivo. Creatine can protect against excitotoxicity as well as against ?-amyloid toxicity in vitro. We carried out studies\\u000a examining the efficacy of creatine as a neuroprotective agent in vivo. We demonstrated that creatine can protect against excitotoxic\\u000a lesions produced by

M. Flint Beal

2011-01-01

335

Lightning effects on aircraft  

NASA Technical Reports Server (NTRS)

Direct and indirect effects of lightning on aircraft were examined in relation to aircraft design. Specific trends in design leading to more frequent lightning strikes were individually investigated. These trends included the increasing use of miniaturized, solid state components in aircraft electronics and electric power systems. A second trend studied was the increasing use of reinforced plastics and other nonconducting materials in place of aluminum skins, a practice that reduces the electromagnetic shielding furnished by a conductive skin.

1977-01-01

336

Tasting edge effects  

NASA Astrophysics Data System (ADS)

We show that the baking of potato wedges constitutes a crunchy example of edge effects, which are usually demonstrated in electrostatics. A simple model of the diffusive transport of water vapor around the potato wedges shows that the water vapor flux diverges at the sharp edges in analogy with its electrostatic counterpart. This increased evaporation at the edges leads to the crispy taste of these parts of the potatoes.

Bocquet, Lydéric

2007-02-01

337

Electromagnetic environmental effects compendium  

NASA Astrophysics Data System (ADS)

This report summarizes the electromagnetic environmental effects (E3) program of the U.S. Army Communications-Electronics Command (CECOM). The report includes background information on CECOM's role in the Army E3 program, presents the approach used to identify the electromagnetic environment, summarizes E3 criteria (i.e., the CECOM model electromagnetic environment), and provides a sample E3 assessment. The report also discusses electromagnetic trends and their implications.

Brockel, Kenneth H.; Cofield, David; Deallaume, William; Gorr, Lanny; Major, Paul A.

1993-08-01

338

Quantum effects in biology  

Microsoft Academic Search

The idea that quantum-mechanical phenomena can play nontrivial roles in biology has fascinated researchers for a century. Here we review some examples of such effects, including light-harvesting in photosynthesis, vision, electron- and proton-tunneling, olfactory sensing, and magnetoreception. We examine how experimental tests have aided this field in recent years and discuss the importance of developing new experimental probes for future

Graham R. Fleming; Gregory D. Scholes; Yuan-Chung Cheng

2011-01-01

339

Cost-Effectiveness Analyses  

Microsoft Academic Search

Surgical research has traditionally focused on comparing health outcome measures of a new technique with accepted practice.\\u000a As health care resources become scarcer and options for newer, more expensive diagnostic tests and surgical interventions\\u000a increase, incorporating cost-effectiveness analysis (CEA) into surgical research studies becomes increasingly important. CEA\\u000a provides the information necessary to allow resource allocation decisions to be based on

Lynn Stothers

340

Ejs Doppler Effect Model  

NSDL National Science Digital Library

The Ejs Doppler Effect model displays the detection of sound waves from a moving source and the change in frequency of the detected wave via the Doppler effect. In addition to the wave fronts from the source a graph depicting the time of emission and time of detection of each of the wave fronts is given. The speed of sound, the velocity of the source and the position and velocity of the detector can be changed via text boxes. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Doppler Effect model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ehu_waves_doppler.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for wave optics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Aguirregabiria, Juan

2008-08-20

341

Effective properties of metamaterials  

NASA Astrophysics Data System (ADS)

Properties of metamaterials are usually discussed in terms of biaxial anisotropic material parameters. To consider the underlying constitutive relations as valid, it is required that only weak spatial dispersion occurs. At operational frequencies of optical metamaterials this assumption often ceases to be valid. A description using effective material properties tends to be inadequate and new approaches are required. We outline here our latest achievements along this direction and discuss two approaches. The first one assumes that if it is not possible to introduce useful effective properties, a more primary source of information should be used to quantify metamaterials, leading to a characterization of metamaterials in terms of Jones matrices. We discuss the implications of this description and show that all metamaterials can be categorized into five classes, each with distinct properties. The second approach resorts to an effective description but restricts its considerations to a dispersion relation, characterizing the propagation of light in bulk metamaterials, and an impedance, characterizing the coupling between metamaterials and their surroundings. Definitions of both properties linked to a single Bloch mode are discussed and metamaterials are introduced which can be homogenized while considering only this single mode.

Rockstuhl, C.; Menzel, C.; Paul, T.; Pshenay-Severin, E.; Falkner, M.; Helgert, C.; Chipouline, A.; Pertsch, T.; ?migaj, W.; Yang, J.; Lalanne, P.; Lederer, F.

2011-09-01

342

Planetary Electrochemical Effects  

NASA Astrophysics Data System (ADS)

Lightning on a planet other than the Earth was first discovered by Voyager when it flew past Jupiter in 1979. Since then it has been reported on Saturn by Voyager and Cassini, and on Venus from Pioneer Venus and Venus Express. While lightning involves clouds formed from polar molecules such as water, or vulcanism, dusty environments often create electrostatic fields through triboelectric phenomena. In each instance, changes in local chemistry with profound global impact can occur, such as lightning-induced nitrogen fixation on earth. Perhaps the most dramatic effect occurs on Mars within its global dust storms and dust devils. Enhanced production of oxidants, such as hydrogen peroxide, sulfur and halogen species including perhaps perchlorates from minerals in airborne dust are some of the likely chemical effects. The oxidants may be responsible for the lack of organics on the surface of Mars and rapid destruction of methane in the atmosphere. On Titan, the surface organics may be altered by a different (charged particle) effect, a phenomena that may also operate in the polar regions of Mars and on the Galilean satellites. In this talk, we will discuss possible chemical and astrobiological implications of above electrical processes.

Atreya, S. K.; Mihalka, K. M.; Mahaffy, P. R.; Delory, G. T.; Farrell, W. M.

2008-12-01

343

Photoelectric Effect Model  

NSDL National Science Digital Library

The EJS Photoelectric Effect model simulates the Photoelectric effect discovered by Hertz in 1887 and described theoretically by Einstein in 1905. Light of a given frequency (energy) shines on a metal in a vacuum tube. If the energy of the photons is greater than the work function of the metal, W, electrons are ejected and can form a current in an external circuit. These photoelectrons will have a kinetic energy if the energy of the light is greater than the work function. If subjected to an electric potential between the plates in the tube, the electrons excited from the metal will be accelerated resulting in an increase, decrease, or stopping of the current. This model provides controls for the frequency of the light source and the external potential on the electron tube. An ammeter allows users to take data for the photo-current. The EJS Photoelectric Effect model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_qm_photoelectric.jar file will run the program if Java is installed.

Palop, Jose I.

2010-07-16

344

Metabolic effects of alcohol.  

PubMed

The metabolic effects of ethanol are due to a direct action of ethanol or its metabolites, changes in the redox state occurring during its metabolism, and modifications of the effects of ethanol by nutritional factors. Ethanol causes hyperglycemia or hypoglycemia depending on whether glycogen stores are adequate, inhibits protein synthesis, and results in fatty liver and in elevations in serum triglyceride levels. Increases in high-density lipoprotein cholesterol after ethanol ingestion may explain the lower risk of myocardial infarction and death from coronary disease after moderate drinking. Increases in serum lactate, resulting from the increased NADH/NAD+ ratio, and hyperuricemia, most likely the result of increased turnover of adenine nucleotides, are common transient effects of ethanol ingestion. Causes of vitamin deficiencies in alcoholism are decreased dietary intake, decreased intestinal absorption, and alterations in vitamin metabolism. Ethanol decreases thiamine absorption and decreases the enterohepatic circulation of folate. Acetaldehyde increases the degradation of pyridoxal 5'-phosphate by displacing it from its binding protein and making it susceptible to hydrolysis by membrane-bound alkaline phosphatase. Ethanol decreases hepatic vitamin A concentration and its conversion to active retinal, and modifies renal metabolism of vitamin D. PMID:3881285

Mezey, E

1985-01-01

345

Calculating and Synthesizing Effect Sizes  

Microsoft Academic Search

The effect size is a standardized, scale-free measure of the relative size of the effect of an interven- tion, and it has important and practical implications for clinicians in the speech and hearing field who are interested in estimating the effects of interventions. This article develops a conceptual interpretation of the effect size, makes explicit assumptions for its proper use

Herbert M. Turner; Robert M. Bernard

2006-01-01

346

Evolution of Earth's Greenhouse Effect  

Microsoft Academic Search

The major factors contributing to Earth's greenhouse effect are discussed along with various quantitative methods for determining the greenhouse effect. Earth's greenhouse effect has evolved over geologic time scales and continues to evolve. The magnitude of Earth's greenhouse effect is explored for particular time periods of Earth's evolution from the Neoproterozoic to present. Coupled climate model simulations for these various

J. T. Kiehl

2003-01-01

347

SOLAR EFFECTS ON BUILDING DESIGN.  

ERIC Educational Resources Information Center

A REPORT OF A PROGRAM HELD AS PART OF THE BUILDING RESEARCH INSTITUTE 1962 SPRING CONFERENCE ON THE SOLAR EFFECTS ON BUILDING DESIGN. TOPICS DISCUSSED ARE--(1) SOLAR ENERGY DATA APPLICABLE TO BUILDING DESIGN, (2) THERMAL EFFECTS OF SOLAR RADIATION ON MAN, (3) SOLAR EFFECTS ON ARCHITECTURE, (4) SOLAR EFFECTS ON BUILDING COSTS, (5) SELECTION OF…

Building Research Inst., Inc., Washington, DC.

348

Verbal response-effect compatibility  

Microsoft Academic Search

Ideomotor theory states that motor responses are activated by an anticipation of their sensory effects. We assumed that anticipated\\u000a effects would produce response-effect (R-E) compatibility when there is dimensional overlap of effects and responses. In a\\u000a four-choice task, visual digit stimuli called for verbal responses (color names). Each response produced a written response-effect\\u000a on the screen. In different groups, the

Iring Koch; Wilfried Kunde

2002-01-01

349

40 CFR 1508.8 - Effects.  

Code of Federal Regulations, 2013 CFR

...Effects. Effects include: (a) Direct effects, which are caused by the...foreseeable. Indirect effects may include growth inducing effects and other effects...economic, social, or health, whether direct, indirect, or cumulative....

2013-07-01

350

``The Kesterson effect''  

NASA Astrophysics Data System (ADS)

Hypothesized to be derived from Cretaceous marine sedimentary rocks, selenium contamination of the Kesterson National Wildlife Refuge is traced through irrigation drainage to the source bedrock of the California Coast Ranges. This biogeochemical pathway of selenium is defined here as the “Kesterson effect.” At the refuge ponds, this effect culminated in 1983 in a 64% rate of deformity and death of embryos and hatchlings of wild aquatic birds. From the previous companion paper on irrigation drainage, the Kesterson effect has been implicated in nine of 11 reconnaissance areas studied in the western United States. Deformities have resulted in at least five of these sites. Climatic, geologic, hydrologic, and soil conditions in these reconnaissance areas are similar to those in the area surrounding Kesterson National Wildlife Refuge in the west-central San Joaquin Valley of California. In California, selenium, as selenate, was ultimately found weathered with sulfur from marine sources in soluble sodium and magnesium sulfate salts, which are concentrated by evaporation on farmland soils. The Se, mobilized by irrigation drainage, is bioaccumulated to toxic levels in refuge wetland ponds that are located mainly in hydrologically closed basins and thus act as concentrating disposal points. The depositional environment of the ponds may be similar to that of the nutrient-rich continental shelf edge and slope in which Cretaceous, Eocene, and Miocene sediments found to be seleniferous in the California Coast Ranges were deposited. Bioaccumulation may be therefore a primary mechanism of selenium enrichment in ancient sediments in addition to that of the formerly suggested Cretaceous volcanic pathway.

Presser, Theresa S.

1994-05-01

351

Effective Gauge Theory  

NASA Astrophysics Data System (ADS)

The global iso-spin invariance of the hadronic interaction, which is areflection of the SU(2) × U(1) QFD and QCD, as well as the U(1) invariance related to the charge of the hadrons, is formulated as an effective gauge theory. The pseudo-gauge fields in this theory are the vector mesons, and these composite fields become massive when the Higgs field at the quark-lepton level and the bar{q}q pair states acquire the vacuum expectation value. The formulation gives a theoretical basis for the vector dominance model and gives some insights to the possible composite structure of quarks and leptons.

Ebata, T.

1982-02-01

352

Photochemical Effects of Sunlight  

PubMed Central

The importance of sunlight in bringing about not only photosynthesis in plants, but also other photochemical effects, is reviewed. More effort should be devoted to photochemical storage of the sun's energy without the living plant. There is no theoretical reason to believe that such reactions are impossible. Ground rules for searching for suitable solar photochemical reactions are given, and a few attempts are described, but nothing successful has yet been found. Future possibilities are suggested. Photogalvanic cells which convert sunlight into electricity deserve further research. Eugene Rabinowitch has been an active pioneer in these fields.

Daniels, Farrington

1972-01-01

353

Radiative Effects of Aerosols  

NASA Technical Reports Server (NTRS)

During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size resolved aerosol microphysics and chemistry. Both profiles included pollution haze layer from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core.

Valero, Francisco P. J.

1997-01-01

354

Effect of "terminal explosion"  

NASA Astrophysics Data System (ADS)

We consider the entry into the Earth's atmosphere of a cosmic body at hypersonic speeds. Large aerodynamic charges, the forces of inertia, and heat flow to the body surface lead to mass loss or even destruction of the body. The movement of the fragment cloud caused by the destruction of the body is a separate problem. From observations, we know that the flight of a cosmic body often ends with a terminal flare. We present one possible estimate of the energy in the final stages of the destruction of the body, confirming the possibility of the observed effect of the "terminal explosion" of the meteoroid.

Egorova, L.

2012-01-01

355

Butterfly Effect Fractal  

NASA Astrophysics Data System (ADS)

In this paper, a new concept of integration of fractal and the butterfly effect is proposed and implemented. A new fractal program was designed and developed to perform such integration. Among many existing fractal and chaos software programs, none of them allow us to achieve the resulting patterns demonstrated in this paper. Moreover, it is the first time that a fractal program provides functional concepts of overlapping results in 3D space and sequential transformations, which allow us to generate a wider variety of patterns. Therefore, potentially an artist can use this program to create 2D digital artworks.

Chang, Yin-Wei; Huang, Fay

356

Assessments of astronaut effectiveness  

NASA Technical Reports Server (NTRS)

This study examined the reliability and convergent validity of three methods of peer and supervisory ratings of the effectiveness of individual NASA astronauts and their relationships with flight assignments. These two techniques were found to be reliable and relatively convergent. Seniority and a peer-rated Performance and Competence factor proved to be most closely associated with flight assignments, while supervisor ratings and a peer-rated Group Living and Personality factor were found to be unrelated. Results have implications for the selection and training of astronauts.

Rose, Robert M.; Helmreich, Robert L.; Fogg, Louis; Mcfadden, Terry J.

1993-01-01

357

Greenhouse Effect Lab  

NSDL National Science Digital Library

In this simple lab, students collect data to demonstrate basic atmospheric science concepts. Groups of students measure the effect of carbon dioxide on temperature using soda bottles with thermometers inserted. One bottle is filled with air and capped. The second bottle is filled with carbon dioxide using a specific procedure. To conduct the experiment, both bottles are placed under a lamp while students record the increase in temperature over five minutes. The bottle containing carbon dioxide has a greater increase in temperature than the bottle containing air. This lab demonstrates the fundamental concept that underlies climate change science by providing data that are easy for students to interpret.

Larsen, Krista

358

Microcircuit radiation effects databank  

NASA Technical Reports Server (NTRS)

This databank is the collation of radiation test data submitted by many testers and serves as a reference for engineers who are concerned with and have some knowledge of the effects of the natural radiation environment on microcircuits. It contains radiation sensitivity results from ground tests and is divided into two sections. Section A lists total dose damage information, and section B lists single event upset cross sections, I.E., the probability of a soft error (bit flip) or of a hard error (latchup).

1983-01-01

359

On nature's scaling effects  

NASA Astrophysics Data System (ADS)

This presentation afforded the opportunity to look back in the literature to discover scaling effects in nature that might be relevant to composites. Numerous examples were found in nature's approaches to wood, teeth, horns, leaves, eggs, feathers, etc. Nature transmits tensile forces rigidly with cohesive bonds, while dealing with compression forces usually through noncompressible hydraulics. The optimum design scaling approaches for aircraft were also reviewed for comparison with similitude laws. Finally, some historical evidence for the use of Weibull scaling in composites was reviewed.

Wilkins, Dick J.

1994-07-01

360

Earthquake occurrence and effects.  

PubMed

Although earthquakes are mainly concentrated in zones close to boundaries of tectonic plates of the Earth's lithosphere, infrequent events away from the main seismic regions can cause major disasters. The major cause of damage and injury following earthquakes is elastic vibration, rather than fault displacement. This vibration at a particular site will depend not only on the size and distance of the earthquake but also on the local soil conditions. Earthquake prediction is not yet generally fruitful in avoiding earthquake disasters, but much useful planning to reduce earthquake effects can be done by studying the general earthquake hazard in an area, and taking some simple precautions. PMID:2347628

Adams, R D

1990-01-01

361

Handbook of radiation effects  

SciTech Connect

This handbook is intended to serve as a tool for designers of equipment and scientific instruments in cases where they are required to ensure the survival of the equipment in radiation environments. High-technology materials, especially semiconductors and optics, tend to degrade on exposure to radiation in many different ways. Intense high-energy radiation environments are found in nuclear reactors and accelerators, machines for radiation therapy, industrial sterilization, and space. Some engineers have to build equipment which will survive a nuclear explosion from a hostile source. Proper handling of a disaster with radioactive materials requires equipment which depends utterly on semiconductor microelectronics and imaging devices. Thus the technology of radiation-tolerant electronics is an instrument for good social spheres as diverse as disaster planning and the exploration of Mars. In order to design equipment for intense environments like those described above, then degradation from high-energy irradiation must be seen as a basic design parameter. The aim of this handbook is to assist the engineer or student in that thought; to make it possible to write intelligent specifications; to offer some understanding of the complex variety of effects which occur when high-technology components encounter high-energy radiation; and to go thoroughly into the balance of choices of how to alleviate the effects and hence achieve the design aims of the project. Separate abstracts were prepared for 15 chapters of this book.

Holmes-Siedle, A. (ed.) (Radiation Experiments and Monitors, Oxford (United Kingdom) Univ. of West London (United Kingdom)); Adams, L. (ed.) (European Space Agency-ESTEC, Noordwijk (Netherlands). Radiation Effects and Analysis Techniques Unit)

1993-01-01

362

Medication effects on sleep.  

PubMed

Each person spends one third of his or her life asleep. It is not surprising that such a complex and pervasive cognitive state should be affected by drugs in many different ways. A philosophy that remains cogent for the CNS is that new research almost always shows this system to be more complex than previously thought. Only a few years ago, if patients complained of difficulty sleeping, they were given pills, often dangerous and addictive pills, to induce sleep no matter what the basis of the complaint might be. Sleeping pills may be safer now, and the understanding of the sleep state itself has increased rapidly. Diagnoses are still diffuse, however, and treatments are often poorly directed. Depression is the offspring of the phlegmatic disposition and the melancholia of another era. Clinically, diagnosis is based on a global assessment of symptoms. It is likely that a diagnosis of depression may include a spectrum of underlying diseases that cannot now be clinically differentiated. Medications have multiple effects on sleep and have many side effects. Progress has, however, been made beyond mother's little pills. Insomnia is no longer a diagnosis but a complaint to be addressed--a symptom of 1 of 60 potential sleep disorders. Each of these disorders has specific and appropriate treatments. PMID:11699244

Pagel, J F

2001-10-01

363

Microwave field effect transistor  

NASA Astrophysics Data System (ADS)

Electrodes of a high power, microwave field effect transistor are substantially matched to external input and output networks. The field effect transistor includes a metal ground plane layer, a dielectric layer on the ground plane layer, a gallium arsenide active region on the dielectric layer, and substantially coplanar spaced source, gate, and drain electrodes having active segments covering the active region. The active segment of the gate electrode is located between edges of the active segments of the source and drain electrodes. The gate and drain electrodes include inactive pads remote from the active segments. The pads are connected directly to the input and output networks. The source electrode is connected to the ground plane layer. The space between the electrodes and the geometry of the electrodes extablish parasitic shunt capacitances and series inductances that provide substantial matches between the input network and the gate electrode and between the output network and the drain electrode. Many of the devices are connected in parallel and share a common active region, so that each pair of adjacent devices shares the same source electrodes and each pair of adjacent devices shares the same drain electrodes. The gate electrodes for the parallel devices are formed by a continuous stripe that extends between adjacent devices and is connected at different points to the common gate pad.

Huang, Ho-Chung

1989-06-01

364

The Check Effect Reconsidered  

PubMed Central

Aims The “check effect” refers to the use of disability payments to purchase illegal drugs or alcohol. This article describes subsequent research concerning three interrelated issues: the check effect, whether receipt of disability payments is associated with more overall substance use, and potential policy responses to misuse of disability payments for substances. Methods Review and synthesis of published articles. Results Increased substance use at the beginning of the month has been described in a variety of settings. The tendency to purchase substances at the beginning of the month is impacted by household wealth, the tendency to discount future rewards, and cyclical economic activity. However, in naturalistic observational cohort studies, beneficiaries who receive disability payments had no greater substance use than those without disability payments. Potential policy responses to misspending of disability checks include financial counseling that discourages spending on drugs, and the assignment of a representative payee to prevent misuse of benefits for substances. Assignment of a representative payee per se has not been associated with reduced substance use but payeeship administered by agencies that integrate payee practice into treatment has been. Conclusion Disability payments impact the timing of substance use, but receipt of disability payments is not associated with more overall substance use than unalleviated poverty. Money management-based clinical interventions, which may involve assignment of a representative payee, can minimize the purchase of substances with disability payments.

Rosen, Marc I.

2011-01-01

365

JPL Test Effectiveness Analysis  

NASA Technical Reports Server (NTRS)

1) The pilot study provided meaningful conclusions that are generally consistent with the earlier Test Effectiveness work done between 1992 and 1994: a) Analysis of pre-launch problem/failure reports is consistent with earlier work. b) Analysis of post-launch early mission anomaly reports indicates that there are more software issues in newer missions, and the no-test category for identification of post-launch failures is more significant than in the earlier analysis. 2) Future work includes understanding how differences in Missions effect these analyses: a) There are large variations in the number of problem reports and issues that are documented by the different Projects/Missions. b) Some missions do not have any reported environmental test anomalies, even though environmental tests were performed. 3) Each project/mission has different standards and conventions for filling out the PFR forms, the industry may wish to address this issue: a) Existing problem reporting forms are to document and track problems, failures, and issues (etc.) for the projects, to ensure high quality. b) Existing problem reporting forms are not intended for data mining.

Shreck, Stephanie; Sharratt, Stephen; Smith, Joseph F.; Strong, Edward

2008-01-01

366

Pupillary Stroop effects  

PubMed Central

We recorded the pupil diameters of participants performing the words’ color-naming Stroop task (i.e., naming the color of a word that names a color). Non-color words were used as baseline to firmly establish the effects of semantic relatedness induced by color word distractors. We replicated the classic Stroop effects of color congruency and color incongruency with pupillary diameter recordings: relative to non-color words, pupil diameters increased for color distractors that differed from color responses, while they reduced for color distractors that were identical to color responses. Analyses of the time courses of pupil responses revealed further differences between color-congruent and color-incongruent distractors, with the latter inducing a steep increase of pupil size and the former a relatively lower increase. Consistent with previous findings that have demonstrated that pupil size increases as task demands rise, the present results indicate that pupillometry is a robust measure of Stroop interference, and it represents a valuable addition to the cognitive scientist’s toolbox.

?rbo, Marte; Holmlund, Terje; Miozzo, Michele

2010-01-01

367

Effects of acoustic sources  

NASA Astrophysics Data System (ADS)

An experiment was conducted to determine the effect of acoustics on the laminar flow on the side of a nacelle. A flight test was designed to meet this goal and a brief review of the purpose is given. A nacelle with a significant length of laminar flow was mounted on the wing of NASA OV-1. Two noise sources are also mounted on the wing: one in the center body of the nacelle; the second in a wing mounted pod outboard of the nacelle. These two noise sources allow for a limited study of the effect of source direction in addition to control of the acoustic level and frequency. To determine the range of Tollmien-Schlichting frequencies, a stability analysis using the pressure coefficient distribution along the side of the nacelle was performed. Then by applying these frequencies and varying the acoustic level, a study of the receptivity of the boundary layer to the acoustic signal, as determined by the shortening of the length of laminar flow, was conducted. Results are briefly discussed.

Schoenster, James A.; Jones, Michael G.

1987-12-01

368

Conducting effective tailgate trainings.  

PubMed

The California Department of Health Services' Occupational Health Branch and others have identified the construction industry as being at high risk for injuries, illnesses, and fatalities. Effective tailgate trainings (brief job site safety meetings) can be a powerful tool to promote hazard awareness and safe work practices. The authors found that many contractors and supervisors conducted ineffective tailgate trainings. They developed the BuildSafe California Project to assist contractors to have more effective programs by holding 25 training-of-trainers sessions reaching 1,525 participants. The needs assessment, intervention, and evaluation results from the first 18 trainings are presented. Eighty-six percent of the participants found the program "very helpful." Participants used the materials and made improvements in the quality and frequency of trainings. Supervisors must be skilled at conducting tailgate trainings as part of their responsibilities. There is a serious need to provide more culturally appropriate safety training in a workforce increasingly made up of Latino workers. PMID:18372431

Harrington, David; Materna, Barbara; Vannoy, Jim; Scholz, Peter

2009-07-01

369

Cavitation induced Becquerel effect.  

PubMed

The observation of an electrical current upon the ultraviolet (UV) illumination of one of a pair of identical electrodes in liquid water, called the Becquerel effect, was made over 150 years ago. More recently, an electrical current was found if the water surrounding one electrode was made to cavitate by focused acoustic radiation, the phenomenon called the cavitation induced Becquerel effect. Since cavitation is known to produce UV light, the electrode may simply absorb the UV light and produce the current by the photo-emission theory of photoelectrochemistry. But the current was found to be semi-logarithmic with the standard electrode potential which is characteristic of the oxidation of the electrode surface in the photo-decomposition theory, and not the photo-emission theory. High bubble collapse temperatures may oxidize the electrode, but this is unlikely because melting was not observed on the electrode surfaces. At ambient temperature, oxidation may proceed by chemical reaction provided a source of vacuum ultraviolet (VUV) radiation is available to produce the excited OH* states of water to react with the electrode. The source of VUV radiation is shown to be the spontaneous emission of coherent infrared (IR) radiation from water molecules in particles that form in bubbles because of surface tension, the spontaneous IR emission induced by cavity quantum electrodynamics. The excited OH* states are produced as the IR radiation accumulates to VUV levels in the bubble wall molecules. PMID:12782267

Prevenslik, T V

2003-06-01

370

Astroinfect Effect - Revised Model  

NASA Astrophysics Data System (ADS)

Space activities lead to a lasting pollution of the Solar System. Light pressure, gravitational interaction with the planets, collisions and explosions (similar to spontaneous explosions of Earth satellite) of artefacts in the outer parts of the planetary system can lead to effective, inevitable spontaneous leakage of interplanetary trash into the interstellar medium, even in the absence of interstellar flights. If there are alien artefacts between the stars, some of them are likely to fall down to Earth at times [1,2]. They could be non-sterile, so sporadic interstellar panspermia is possible [3]. The minimum pollution threshold for such panspermia was estimated [2] for 2 m-microartefacts at the level of Galactic cosmic radiation of 4 x 10-7 rad/s [4]. However, C. Mileikowsky showed that, if the X-rays are taken into consideration, the interstellar dose rate is ~3 x 10- 5 rad/s [5]. At this high dose rate the microartefacts must be sterilised at the distances >0.1 pc from the planetary system, hence they cannot be an effective agent of interstellar panspermia. Sufficient protection of microbial spores is possible inside macroartefacts. Therefore, the panspermia model and the corresponding minimum pollution threshold must be re-examined.

Arkhipov, A. V.

371

Health effects of hawthorn.  

PubMed

Hawthorn medicinal extract has long been a favored herbal remedy in Europe. The active components of this slow-acting cardiotonic agent are thought to be flavonoids and oligomeric procyanidins. The most studied hawthorn extracts are WS 1442 and LI 132. Reviews of placebo- controlled trials have reported both subjective and objective improvement in patients with mild forms of heart failure (New York Heart Association classes I through III). Other studies of hawthorn in patients with heart failure have revealed improvement in clinical symptoms, pressure-heart rate product, left ventricular ejection fraction, and patients' subjective sense of well-being. However, there is no evidence of a notable reduction in mortality or sudden death. Hawthorn is well tolerated; the most common adverse effects are vertigo and dizziness. Theoretic interactions exist with antiarrhythmics, antihypertensives, digoxin, and antihyperlipidemic agents. Proven conventional therapies for heart failure are still recommended until the safety and effectiveness of hawthorn has been proven in long-term studies. PMID:20148500

Dahmer, Stephen; Scott, Emilie

2010-02-15

372

Substituent Effects. X. An improved Treatment (FMMF) of Substituent Effects.  

National Technical Information Service (NTIS)

An improved version (FMMF) of the earlier FM(Field-mesomeric method) treatment of substituent effects is described in which explicit allowance is made for the mesomeric-field effect and in which the field effect of neutral substituents is calculated by a ...

J. M. Harris M. J. S. Dewar R. Golden

1970-01-01

373

Magnetoelectric effects in multiferroics  

NASA Astrophysics Data System (ADS)

Magneto-electric phenomena were investigated in two different multiferroic systems: The strong coupling of dielectric and magnetic properties and the simultaneous occurrence of long-range magnetic and ferroelectric order are discussed for rare earth manganites and sulfo spinels. A phase diagram of Eu1-xYxMnO3 is established, which recovers the main features of the well-known magneto-electric phase diagram for the pure rare earth manganites RMnO3. Here a variety of magnetic and electric phases emerge with varying rare earth ions R. As function of temperature and external magnetic field, also Y doped EuMnO3 compounds undergo a sequence of different magnetic and polar phase transitions for varying effective ionic radii of the rare earth ions. Special attention is paid to the occurrence of fundamentally new hybrid spin-electromagnetic excitations, which we name electromagnons and are characterized as spin waves that can be excited by an ac electric field. These excitations are identified in Eu1-xYxMnO3 with x = 0.2, in GdMnO3, and in TbMnO3. Specifically in GdMnO3 the electromagnons can easily be suppressed by external magnetic fields and allow tuning the index of refraction by moderate fields. In the second part we discuss the simultaneous appearance of colossal magneto-resistance (CMR) and colossal magneto-capacitance (CMC) effects in chromium sulfo spinels. In CdCr2S4 ferromagnetism of localized Cr spins evolves at 85 K, while polar order is established below 130 K. The onset of ferroelectric order is neither accompanied by the occurrence of soft modes nor by structural changes which break the inversion symmetry of the high-temperature cubic phase. HgCr2S4 becomes ferroelectric close to 70 K while a complex antiferromagnetic order is found below 25 K. CMR and CMC effects are specifically strong in the mercury compound, as moderate magnetic fields of only 0.1 T induce ferromagnetism at much higher temperatures. We speculate that the occurrence of ferroelectricity in these multiferroic compounds is rather of electronic than of ionic origin.

Loidl, Alois

2006-03-01

374

Low Temperature Effects on TNT.  

National Technical Information Service (NTIS)

The effects of low temperature on TNT were determined by subjecting the explosive material to liquid nitrogen and studying the effects through differential thermal analysis, differential scanning calorimetry, thermomechanical analysis, impact sensitivity,...

L. Avrami H. J. Jackson W. E. Voreck E. W. Dalrymple

1975-01-01

375

Piezoelectricity: Venerable Effect, Modern Thrusts.  

National Technical Information Service (NTIS)

A synopsis of the piezoelectric effect is presented in the context of its history, traditional uses, and relation to crystal symmetry. Associated effects are briefly noted. Future prospects, particularly in the area of microelectromechanical systems/struc...

A. Ballato

1994-01-01

376

Side Effects and Their Management  

MedlinePLUS

... leave this field empty Side Effects and their Management SHARE Share on Facebook Preview your comments Share ... Home > Treatment and Care > Side Effects and their Management Listen Brain tumors and their treatments bring an ...

377

Mechanical effects in cookoff modeling.  

National Technical Information Service (NTIS)

Complete cookoff modeling of energetic material in confined geometries must couple thermal, chemical and mechanical effects. In the past, modeling has focused on the prediction of the onset of combustion behavior based only on thermal-chemistry effects wi...

R. J. Gross M. R. Baer M. L. Hobbs

1994-01-01

378

Evolution of Earth's Greenhouse Effect  

NASA Astrophysics Data System (ADS)

The major factors contributing to Earth's greenhouse effect are discussed along with various quantitative methods for determining the greenhouse effect. Earth's greenhouse effect has evolved over geologic time scales and continues to evolve. The magnitude of Earth's greenhouse effect is explored for particular time periods of Earth's evolution from the Neoproterozoic to present. Coupled climate model simulations for these various time periods are used to estimate the magnitude of the greenhouse effect. A comparison is made between the present greenhouse effect and those of past times. The connection between the greenhouse effect and Earth's hydrologic cycle is also discussed. Finally, a comparison is made of between past greenhouse effects and that predicted for the end of the twenty-first century.

Kiehl, J. T.

2003-12-01

379

Flight effects of fan noise  

NASA Technical Reports Server (NTRS)

Simulation of inflight fan noise and flight effects was discussed. The status of the overall program on the flight effects of fan noise was reviewed, and flight to static noise comparisons with the JT15D engine were displayed.

Chestnutt, D. (editor)

1982-01-01

380

Biologic Effects of Microwave Exposure.  

National Technical Information Service (NTIS)

The exact nature of the biological effects of microwaves is not completely understood. Evidence indicates that microwave energy can act as a 'stressor' agent, and has an effect on regulatory and integrative mechanisms of the body with resultant alteration...

J. W. Howland R. A. E. Thomson S. M. Michaelson

1967-01-01

381

Adult Acne: Effective Treatment Available  

MedlinePLUS

... benzoyl peroxide and a topical antimicrobial such as clindamycin or erythromycin can be effective for adults with mild to moderate acne. Combining topical clindamycin with a retinoid also can be effective. These ...

382

Effective suppressibility of chaos.  

PubMed

Suppression of chaos is a relevant phenomenon that can take place in nonlinear dynamical systems when a parameter is varied. Here, we investigate the possibilities of effectively suppressing the chaotic motion of a dynamical system by a specific time independent variation of a parameter of our system. In realistic situations, we need to be very careful with the experimental conditions and the accuracy of the parameter measurements. We define the suppressibility, a new measure taking values in the parameter space, that allows us to detect which chaotic motions can be suppressed, what possible new choices of the parameter guarantee their suppression, and how small the parameter variations from the initial chaotic state to the final periodic one are. We apply this measure to a Duffing oscillator and a system consisting on ten globally coupled He?non maps. We offer as our main result tool sets that can be used as guides to suppress chaotic dynamics. PMID:23822472

López, Álvaro G; Seoane, Jesús M; Sanjuán, Miguel A F

2013-06-01

383

Effective suppressibility of chaos  

NASA Astrophysics Data System (ADS)

Suppression of chaos is a relevant phenomenon that can take place in nonlinear dynamical systems when a parameter is varied. Here, we investigate the possibilities of effectively suppressing the chaotic motion of a dynamical system by a specific time independent variation of a parameter of our system. In realistic situations, we need to be very careful with the experimental conditions and the accuracy of the parameter measurements. We define the suppressibility, a new measure taking values in the parameter space, that allows us to detect which chaotic motions can be suppressed, what possible new choices of the parameter guarantee their suppression, and how small the parameter variations from the initial chaotic state to the final periodic one are. We apply this measure to a Duffing oscillator and a system consisting on ten globally coupled Hénon maps. We offer as our main result tool sets that can be used as guides to suppress chaotic dynamics.

López, Álvaro G.; Seoane, Jesús M.; Sanjuán, Miguel A. F.

2013-06-01

384

Telestroke: effective networking.  

PubMed

Although stroke units and systemic thrombolysis are effective, use of these two treatment methods is restricted because of a widespread lack of expertise. New telecommunication technologies can help to overcome the lack of emergency-provider support in neurologically underserved areas. The status of "telestroke" as the application of telemedicine for acute stroke is presently passing from feasibility to routine use. Teleneurological examination is reliable and systemic thrombolysis can be extended with telemedical consultation. Telestroke, however, offers even more potential in overall acute stroke management. On the one hand, it provides rapid access to specialised interventions through initiation of interhospital transfers, and on the other hand, it might lead to major improvements in basic on-site stroke therapy. PMID:16488384

Audebert, Heinrich

2006-03-01

385

Hot chocolate effect  

SciTech Connect

The ''hot chocolate effect'' was investigated quantitatively, using water. If a tall glass cylinder is filled nearly completely with water and tapped on the bottom with a softened mallet one can detect the lowest longitudinal mode of the water column, for which the height of the water column is one-quarter wavelength. If the cylinder is rapidly filled with hot tap water containing dissolved air the pitch of that mode may descend by nearly three octaves during the first few seconds as the air comes out of solution and forms bubbles. Then the pitch gradually rises as the bubbles float to the top. A simple theoretical expression for the pitch ratio is derived and compared with experiment. The agreement is good to within the 10% accuracy of the experiments.

Crawford, F.S.

1982-05-01

386

Heat Island Effect  

NSDL National Science Digital Library

For people living in and around cities, heat islands are of growing concern. This phenomenon describes urban and suburban temperatures that are 2 to 10 degrees F (1 to 6 degrees C) hotter than nearby rural areas. Elevated temperatures can impact communities by increasing peak energy demand, air conditioning costs, air pollution levels, and heat-related illness and mortality. The materials available here describe the basic causes of the heat island effect, and what can be done to mitigate some of the impacts. There is also an overview of the Urban Heat Island Pilot Project (UHIPP), an initiative being conducted in five cities in the U.S. to adopt and evaluate heat island reduction strategies and programs.

387

Biological effects of ozone  

SciTech Connect

Tropospheric ozone, a classic anthropogenic air pollutant, is going to remain a troublesome byproduct of contemporary civilization for many decades. We have known for some time that the hydrocarbons and nitrogen oxides from motor vehicles, together with actinic radiation, account for local and regional photochemistry leading to prolonged afternoon ozone peaks. We also now know that agricultural burning and intensive animal husbandry elevate regional and mesoscale concentrations of ozone and its precursors, and that remote background levels of ozone have been rising steadily throughout this century. The changes we will have to make in emission controls to appreciably reduce current tropospheric ozone levels will have profound effects on our transportation systems, consumer products, and lifestyles. As a society, we will have to make difficult choices about the levels of ozone-associated health, welfare, and natural system damage we will tolerate, or conversely, how much we are willing to pay for controls which can minimize the damage.

Lippmann, M. (New York Univ. Medical Center, Tuxedo, NY (USA))

1989-09-01

388

Action languages: Dimensions, effects  

NASA Technical Reports Server (NTRS)

Dimensions of action languages are discussed for communication between humans and machines, and the message handling capabilities of object oriented programming systems are examined. Design of action languages is seen to be very contextual. Economical and effective design will depend on features of situations, the tasks intended to be accomplished, and the nature of the devices themselves. Current object oriented systems turn out to have fairly simple and straightforward message handling facilities, which in themselves do little to buffer action or even in some cases to handle competing messages. Even so, it is possible to program a certain amount of discretion about how they react to messages. Such thoughtfulness and perhaps relative autonomy of program modules seems prerequisite to future systems to handle complex interactions in changing situations.

Hayes, Daniel G.; Streeter, Gordon

1989-01-01

389

Anthropogenic Effects on Erosion  

NSDL National Science Digital Library

This exercise focuses on anthropogenic effects on erosion. It could be run as a single lab or as a series of in-class exercises or problem sets. We discussed an article by Hooke and used it as a launching pad for a discussion of back of the envelope calculations. Students then estimate the volume moved by mountain-top removal and how long it might take a river to mobilize that sediment. They estimate the cost for beach nourishment along Florida beaches. They estimate the contribution of local construction projects and road gravel to stream sediment loads. This activity gives students a chance to formulate a problem, make simple measurements, estimate unknowns, and calculate volumes, rates, and costs of various human earth-moving activities. Designed for a geomorphology course Addresses student fear of quantitative aspect and/or inadequate quantitative skills Uses geomorphology to solve problems in other fields

Gran, Karen

390

Grantmakers for Effective Organizations  

NSDL National Science Digital Library

Grantmakers for Effective Organizations (GEO) makes it their mission to promote the strategies and practices that contribute to grantee success. To this end, the GEO website contains information about its outreach efforts, peer learning opportunities, conferences, and upcoming events. Within GEO Priorities visitors can learn about the organization's own development plan and long-term goals, while the GEO Publications area contains a raft of useful publications for policy types and others. Noteworthy publications, here, include "Many Hands, More Impact: Philanthropy's Role in Supporting Movements" and "Cracking the Network Code: Four Principles for Grantmakers." The Peer Learning Opportunities section is another great installment, containing links to helpful webinars, speaking engagement possibilities, and other useful resources.

391

Dynamic effects of combustion  

NASA Technical Reports Server (NTRS)

The dynamic effects of combustion are due to the evolution of exothermic energy and its deposition in the compressible medium where the process takes place. The paper examines the dynamics of combustion phenomena, including ignition, turbulent flame propagation (inflammation), explosion, and detonation, with emphasis on their exothermic characteristics. Ignition and explosion are treated as problems of nonlinear mechanics, and their dynamic behavior is described in terms of phase space models and cinematographic laser shear interferograms. The results of a numerical random vortex model of turbulent flame propagation are confirmed in a combustion tunnel experiment, where it was observed that a fresh mixture of burnt and unburnt gases can sustain combustion with a relatively small expenditure of overall mass flow, due to the increasing specific volume of burnt gases inside the flame front. An isentropic pressure wave is found to precede the accelerating flame in the process of detonation, and components of this presssure wave are shown to propagate at local sonic velocities.

Oppenheim, A. K.

1982-01-01

392

Effects of Solcoderm.  

PubMed

The effects of treatment and depths of penetration of a 5-fluorouracil and salicylic acid preparation (Solcoderm) were studied in 24 patients treated for basal cell carcinoma with this compound. Two thirds of the patients in our study showed islands of residual tumor in the dermis following treatment, whereas total disappearance of the tumor was observed in one third. The depth of the fibrotic changes induced by the drug varied from 0.34 to 0.40 cm for the morphea type of basal cell carcinoma and from 0.52 to 0.88 cm for the conventional types. It is recommended that treatment with this compound be reserved only for superficial basal cell carcinomas and that it be avoided altogether in basal cell carcinomas of the morphea type. PMID:3539836

Engelberg, I S; Ronnen, M; Suster, S; Schewach-Millet, M; Stempler, D; Schibi-Brilliant, G

1986-11-01

393

Hydrodynamic effects on coalescence.  

SciTech Connect

The goal of this project was to design, build and test novel diagnostics to probe the effect of hydrodynamic forces on coalescence dynamics. Our investigation focused on how a drop coalesces onto a flat surface which is analogous to two drops coalescing, but more amenable to precise experimental measurements. We designed and built a flow cell to create an axisymmetric compression flow which brings a drop onto a flat surface. A computer-controlled system manipulates the flow to steer the drop and maintain a symmetric flow. Particle image velocimetry was performed to confirm that the control system was delivering a well conditioned flow. To examine the dynamics of the coalescence, we implemented an interferometry capability to measure the drainage of the thin film between the drop and the surface during the coalescence process. A semi-automated analysis routine was developed which converts the dynamic interferogram series into drop shape evolution data.

Dimiduk, Thomas G.; Bourdon, Christopher Jay; Grillet, Anne Mary; Baer, Thomas A.; de Boer, Maarten Pieter; Loewenberg, Michael (Yale University, New Haven, CT); Gorby, Allen D.; Brooks, Carlton, F.

2006-10-01

394

Radiative Effects of Aerosols  

NASA Technical Reports Server (NTRS)

During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

Valero, Francisco P. J.

1996-01-01

395

Gravitational effects from earthquakes  

NASA Astrophysics Data System (ADS)

Two types of propagating gravitational effects, from the mass redistribution within the Earth due to a large earthquake, are investigated: (i) the velocity of the change of the Newtonian potential field; and (ii) the gravitational luminosity of the seismic source. The mass redistribution caused by an earthquake and the resulting change in the gravitational potential field is computed through application of geophysical dislocation theory. The global mass redistribution is postulated to be progressive, starting at the instant (and location) of the nucleation of the earthquake fault rupture, and then spreading globally at the velocities of various seismic waves. Information about the changes of the gravitational potential is postulated to travel at the velocity of light. Superconducting gravimeters (SG) can resolve changes of the order of 10 nGal, i.e., (10(-9) cm/s(2)) (1 Gal = 0.001 0197g), sufficient to detect the changes in the potential field. The time difference between observation of the change of the potential field and the arrival of the primary seismic wave from the earthquake would allow a crude estimation of the velocity of the gravitational effect. A preliminary search for the preseismic gravitational signal using an SG has given inconclusive results, primarily due to the limitations of the spline curve fitting methods. Despite this, we suggest that the observation of preseismic gravitational potential changes should be feasible, with the existing array of SGs in the Global Geodynamics Project (GGP) network, and by detectors designed to observe gravitational radiation (e.g., the Laser Interferometer Gravitational-wave Observatory (LIGO)). We have used published values of the changes in the Earth's inertia tensor due to the Alaska earthquake of 1964 to estimate the magnitude of the metric perturbation of the gravitational wave produced by such an earthquake. The gravitational luminosity is estimated at 1.90 x 10(-10)erg/s (1 erg/s = 10(-7) W D 1 J/s).

Hayes, T. J.; Valluri, S. R.; Mansinha, L.

2004-12-01

396

Water-storage-tube systems. Final report  

SciTech Connect

Passive solar collection/storage/distribution systems were surveyed, designed, fabricated, and mechanically and thermally tested. The types studied were clear and opaque fiberglass tubes, metal tubes with plastic liners, and thermosyphoning tubes. (MHR)

Hemker, P.

1981-12-24

397

Dispersant effectiveness: Studies into the causes of effectiveness variations  

SciTech Connect

Effectiveness, a key issue of using dispersants, is affected by many interrelated factors. The principal factors involved are the oil composition, dispersant formulation, sea surface turbulence and dispersant quantity. Oil composition is a very strong determinant. Current dispersant formulation effectiveness correlates strongly with the amount of saturate component in the oil. The other components of the oil, the asphaltenes, resins or polars and aromatic fractions show a negative correlation with the dispersant effectiveness. Viscosity is also a predictor of dispersant effectiveness and may have an effect because it is in turn determined by oil composition. Dispersant composition is significant and interacts with oil composition. Dispersants show high effectiveness at HLB values near 10. Sea turbulence strongly affects dispersant effectiveness.Effectiveness rises with increasing turbulence to a maximum value. Effectiveness for current commercial dispersants is gaussian around a peak salinity value. Peak effectiveness is achieved at very high dispersant quantities--at a ratio of 1:5, dispersant-to-oil volume. Dispersant effectiveness for those oils tested and under the conditions measured, is approximately logarithmic with dispersant quantity and will reach about 50% of its peak value at a dispersant to oil ratio of about 1:20 and near zero at a ratio of about 1:50.

Fingas, M.F.; Kyle, D. [Environment Canada, Ottawa, Ontario (Canada); Tennyson, E. [Minerals Management Service, Herndon, VA (United States)

1995-06-01

398

The effect of seal width on regenerator effectiveness  

SciTech Connect

The effect of axial conduction on regenerator effectiveness has been studied in the past under the assumption of zero seal width. The effect of axial conduction coupled with finite seal width is presented in this paper. A method for calculating effectiveness assuming axial conduction and finite seal width is presented. Results of sample calculations are presented to give the designer a feel for the dependence of seal width effects on system-parameter values. It is shown that for typical regenerator designs, reductions in effectiveness due to axial conduction coupled with finite seal width can be twice as great as those due to axial conduction under the assumption of zero seal width. Also, it is shown that the required regenerator size to achieve a given effectiveness can increase dramatically when finite seal width is considered in design procedures. It is concluded that consideration of axial conduction should include finite seal width.

Beck, D.S. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Mechanical Engineering)

1994-07-01

399

The Estimation of School Effects.  

ERIC Educational Resources Information Center

The specification and estimation of school effects, the variability of effects across schools, and the proportion of variation in student outcomes attributable to differences in school context and practice are considered. A statistical model is presented that defines school effects for parents choosing a school and for agencies evaluating school…

Raudenbush, Stephen W.; Willms, J. Douglas

1995-01-01

400

Cognitive Constraints and Island Effects  

ERIC Educational Resources Information Center

Competence-based theories of island effects play a central role in generative grammar, yet the graded nature of many syntactic islands has never been properly accounted for. Categorical syntactic accounts of island effects have persisted in spite of a wealth of data suggesting that island effects are not categorical in nature and that…

Hofmeister, Philip; Sag, Ivan A.

2010-01-01

401

Emotional intelligence and effective leadership  

Microsoft Academic Search

Emotional intelligence has become increasingly popular as a measure for identifying potentially effective leaders, and as a tool for developing effective leadership skills. Despite this popularity, however, there is little empirical research that substantiates the efficacy of emotional intelligence in these areas. The aim of the present paper was to explore the relationship between emotional intelligence and effective leadership. Emotional

Benjamin Palmer; Melissa Walls; Zena Burgess; Con Stough

2001-01-01

402

Probiotics: mechanisms and established effects  

Microsoft Academic Search

The definition for probiotics has gradually changed with increasing understanding of the mechanisms by which they influence human health. Health effects related to changes in the intestinal microflora also accompany or are related to adhesion and immune system effects, competitive exclusion or metabolic and nutritional effects, with an increasing array of other potential modes of action. Most clinically documented and

Arthur C. Ouwehand; Pirkka V. Kirjavainen; Colette Shortt; Seppo Salminen

1999-01-01

403

"No Effects" Studies Raising Eyebrows  

ERIC Educational Resources Information Center

Like a steady drip from a leaky faucet, the experimental studies being released this school year by the federal Institute of Education Sciences are mostly producing the same results: "No effects," "No effects," "No effects." The disappointing yield is prompting researchers, product developers, and other experts to question the design of the…

Viadero, Debra

2009-01-01

404

Effective Programs for Latino Students.  

ERIC Educational Resources Information Center

This collection of papers presents the current state of research on effective instructional programs for Hispanic American students. The 10 chapters are: (1) "Effective Programs for Latino Students in Elementary and Middle Schools" (Olatokunbo S. Fashola, Robert E. Slavin, Margarita Calderon, and Richard Duran); (2) "Effective Dropout Prevention…

Slavin, Robert E., Ed.; Calderon, Margarita, Ed.

405

Effects of low earth orbit  

Microsoft Academic Search

The effects of low earth orbit on the Long-Duration Exposure Facility (LDEF) spacecraft are reported. The LDEF spacecraft was deployed in low earth orbit in 1984 and was retrieved in 1990. The structure and design of LDEF is described. The dose of ionizing radiation received, data obtained, and its effects on the satellite are discussed. Atomic oxygen surface effects, oxygen

Lawrence E. Murr; William H. Kinard

1993-01-01

406

Safety and effectiveness of vasectomy  

Microsoft Academic Search

Objective: To recommend further research on vasectomy based on a systematic review of the effectiveness and safety of vasectomy. Design: A systematic MEDLINE review of the literature on the safety and effectiveness of vasectomy between 1964 and 1998. Main Outcome Measure(s): Early failure rates are ,1%; however, effectiveness and complications vary with experience of surgeons and surgical technique. Early complications,

Pamela J. Schwingl; Harry A. Guess

2000-01-01

407

The Enigma of Organizational Effectiveness.  

ERIC Educational Resources Information Center

Organizational effectiveness is not a clearly defined concept. The author illustrates how the four most widely used models are not uniformly applicable. He states the evaluator must make explicit certain critical choices when measuring effectiveness. These criteria reveal the definition of effectiveness and what is being measured. (DWH)

Cameron, Kim

1981-01-01

408

Greenhouse effect of NO X  

Microsoft Academic Search

Through various processes the nitrogen oxides (NOX) interact with trace gases in the troposphere and stratosphere which do absorb in the spectral range relevant to the greenhouse\\u000a effect (infrared wavelengths). The net effect is an enhancement of the greenhouse effect. The catalytic role of NOX in the production of tropospheric ozone provides the most prominent contribution. The global waming potential

Gerhard Lammel; Hartmut Grafll

1995-01-01

409

Novel field effects in heterostructures  

Microsoft Academic Search

In this thesis novel electric field effects in thin film heterostructures have been investigated. The heterostructures were grown using the pulsed laser deposition technique and underwent structural, electrical, and in some cases optical characterization before being patterned into field-effect devices. The device properties were explored utilizing a number of standard and newly developed techniques. These field-effect studies reveal information of

Vitaly Talyansky

1998-01-01

410

Faculty Perceptions of Institutional Effectiveness  

ERIC Educational Resources Information Center

This study examined (a) the differences in perceptions of faculty, full-time versus part-time, at a community college in northern Alabama on the importance of institutional effectiveness activities; (b) the factors that affect perceptions of the importance of institutional effectiveness activities; and (c) the effect of academic discipline,…

LoCascio, Susan H.

2010-01-01

411

The Future of Institutional Effectiveness  

ERIC Educational Resources Information Center

Forces inside and outside community colleges are changing the context for performance and mandating new conceptions of effectiveness. This article addresses the future of institutional effectiveness in community colleges. Its emphasis is on what is measured and why, beginning with a retrospective look at early efforts in effectiveness, moving to…

Alfred, Richard L.

2011-01-01

412

Liquid-cooling technology for gas turbines - Review and status  

NASA Technical Reports Server (NTRS)

After a brief review of past efforts involving the forced-convection cooling of gas turbines, the paper surveys the state of the art of the liquid cooling of gas turbines. Emphasis is placed on thermosyphon methods of cooling, including those utilizing closed, open, and closed-loop thermosyphons; other methods, including sweat, spray and stator cooling, are also discussed. The more significant research efforts, design data, correlations, and analytical methods are mentioned and voids in technology are summarized.

Van Fossen, G. J., Jr.; Stepka, F. S.

1978-01-01

413

Adding Heat Pipes and Coolant Loop Models to Finite Element and\\/or Finite difference Thermal\\/Structural Models  

Microsoft Academic Search

Active cooling technologies such as heat pipes, loop heat pipes (LHPs), thermosyphons, loop thermosyphons (LTSs), and pumped single- or two-phase coolant loops require specialized modeling treatment. However, these 1D ducted systems are largely overlooked in 3D thermal mod- eling tools. The increasing popularity of CFD and FEM models and generation of analysis data from 3D CAD data are strong trends

B. Cullimore; D. A. Johnson

414

Gravitomagnetic effects in conformal gravity  

NASA Astrophysics Data System (ADS)

Gravitomagnetic effects are characterized by two phenomena: first, the geodetic effect which describes the precession of the spin of a gyroscope in a free orbit around a massive object, and second the Lense-Thirring effect which describes the precession of the orbital plane about a rotating source mass. We calculate both these effects in the fourth-order theory of conformal Weyl gravity for the test case of circular orbits. We show that for the geodetic effect a linear term arises which may be interesting for high radial orbits, whereas for the Lense-Thirring effect the additional term has a diminishing effect for most orbits. Circular orbits are also considered in general leading up to a generalization of Kepler’s third law.

Said, Jackson Levi; Sultana, Joseph; Adami, Kristian Zarb

2013-10-01

415

Effect sizes in memory research.  

PubMed

Effect sizes are omitted from many research articles and are rarely discussed. To help researchers evaluate effect sizes we collected values for the more commonly reported effect size measures (partial eta squared and d) from papers reporting memory research published in 2010. Cohen's small, medium, and large generic guideline values for d mapped neatly onto the observed distributions, but his values for partial eta squared were considerably lower than those observed in current memory research. We recommend interpreting effect sizes in the context of either domain-specific guideline values agreed for an area of research or the distribution of effect size estimates from published research in the domain. We provide cumulative frequency tables for both partial eta squared and d enabling authors to report and consider not only the absolute size of observed effects but also the percentage of reported effects that are larger or smaller than those observed. PMID:23350788

Morris, Peter E; Fritz, Catherine O

2013-01-01

416

Effective risk management  

SciTech Connect

Most independent power financial proposals contain one or more elements of a non-recourse nature. Traditionally, this means prospective lenders will not have a substantial corporate credit or state guarantee standing behind a project loan, which forces attention to be focused on a single asset as the security and debt repayment source. While this major risk remains present, if properly understood, uncertainty can be mitigated and managed, including financial and development hazards inherent in hydropower projects. The specific risk points that a project developer or sponsor must satisfy from the lender`s purposes are numerous. However, they can be grouped primarily into seven key risk areas: project profile, site securing, power sales agreements, government agreements, in-service management, construction and insurance. While a developer strives for a minimum internal rate of return of at least 20 percent, the lender`s expectations are much more modest. Often, developers need to place themselves in the proverbial shoes of the other entity, namely the independent lender, whose only attraction may be some interest, fee income and placement of capital in a safe investment which provides a return in an orderly and uninterrupted manner. Only then is it possible to objectively view and effectively manage the risks mentioned earlier.

Ball, C.J. [Corpfinance International Ltd., Toronto (Canada)

1997-01-01

417

Paper field effect transistor  

NASA Astrophysics Data System (ADS)

In this paper we report the use of a sheet of cellulose fiber-based paper as the dielectric layer used in oxide based semiconductor thin film field-effect transistors (FETs). In this new approach we are using the cellulose fiber-based paper in an "interstrate" structure since the device is build on both sides of the cellulose sheet. Such hybrid FETs present excellent operating characteristics such as high channel saturation mobility (>30 cm2/Vs), drain-source current on/off modulation ratio of approximately 104, near-zero threshold voltage, enhancement n-type operation and sub-threshold gate voltage swing of 0.8 V/decade. The cellulose fiber-based paper FETs characteristics have been measured in air ambient conditions and present good stability. The obtained results outpace those of amorphous Si TFTs and rival with the same oxide based TFTs produced on either glass or crystalline silicon substrates. The compatibility of these devices with large-scale/large-area deposition techniques and low cost substrates as well as their very low operating bias delineates this as a promising approach to attain high-performance disposable electronics like paper displays, smart labels, smart packaging, RFID and point-of-care systems for self analysis in bio-applications, among others.

Fortunato, E.; Correia, Nuno; Barquinha, Pedro; Costa, Cláudia; Pereira, Luís; Gonçalves, Gonçalo; Martins, Rodrigo

2009-02-01

418

Anticancer effects of phytosterols.  

PubMed

Phytosterol and stanol (or phytosterols) consumption reduces intestinal cholesterol absorption, leading to decreased blood LDL-cholesterol levels and lowered cardiovascular disease risk. However, other biological roles for plant sterols and stanols have also been proposed. The objective of this review is to critically examine results from recent research regarding the potential effects and mechanisms of action of phytosterols on forms of cancer. Considerable emerging evidence supports the inhibitory actions of phytosterols on lung, stomach, as well as ovarian and breast cancer. Phytosterols seem to act through multiple mechanisms of action, including inhibition of carcinogen production, cancer-cell growth, angiogenesis, invasion and metastasis, and through the promotion of apoptosis of cancerous cells. Phytosterol consumption may also increase the activity of antioxidant enzymes and thereby reduce oxidative stress. In addition to altering cell-membrane structure and function, phytosterols probably promote apoptosis by lowering blood cholesterol levels. Moreover, consumption of phytosterols by healthy humans at the recommended level of 2 g per day does not cause any major health risks. In summary, mounting evidence supports a role for phytosterols in protecting against cancer development. Hence, phytosterols could be incorporated in diet not only to lower the cardiovascular disease risk, but also to potentially prevent cancer development. PMID:19491917

Woyengo, T A; Ramprasath, V R; Jones, P J H

2009-07-01

419

Psychological effects of stillbirth.  

PubMed

Despite the high prevalence globally, the death of a baby to stillbirth is an often misunderstood and disenfranchised loss. Mothers, fathers, and families struggle to cope with the immediate and long-lasting effects of a baby's death which can last for years and sometimes decades. In addition, providers can be adversely affected by stillbirth, particularly when met with experiential avoidance and a sense of guilt and failure. There is little evidence on intervention efficacy in acute grief following perinatal death; however, there is a growing body of scientific literature on the efficacy of mindfulness-based interventions in treating anxiety, depression, and other biopsychosocial maladies as well as improving patient satisfaction with psychosocial care. This paper explores one such intervention model, ATTEND (attunement, trust, therapeutic touch, egalitarianism, nuance, and death education), as a means to improve psychosocial care during both acute and chronic states of bereavement. Whereas the death of a baby to stillbirth is the ultimate paradox for providers and patients - the convergence of life and death and the fundamental contradiction it represents - with proper care and compassion, families stand a better chance in the face of such indescribable loss and they need not suffer alone. PMID:23040157

Cacciatore, Joanne

2013-04-01

420

Scale effects in necking  

NASA Astrophysics Data System (ADS)

Geometrically similar specimens spanning a scale range of 100:1 are tested quasi-statically to failure. Images of neck development are acquired using optical means for large specimens, and in-situ scanning electron microscope testing for small specimens, to examine the dependence of neck geometry on a broad range of specimen sizes. Size effects typically arise when the smallest specimen dimension is on the order of a microstructural length (e.g. grain size, dislocation mean free path, etc.), or in the presence of significant plastic strain gradients, which increase the density of geometrically necessary dislocations. This study was carried out for the purpose of investigating scale dependence in models used for predicting dynamic deformation and damage to very high strains for ballistic impact applications, such as the Goldthorpe path-dependent failure model, which includes temperature and strain-rate dependence but does not account for specimen size or a dependence on microstructural lengths. Although the experiments show that neck geometry does not exhibit a clear dependence on specimen size across the range of length scales tested, the statistical variation due to microstructural variations was found to increase monotonically with decreasing size, becoming significant for the smallest (0.35 mm diameter) size, allowing a limit to be identified for reliable model calibration.

Dunnett, T.; Balint, D.; MacGillivray, H.; Church, P.; Gould, P.

2012-08-01

421

Collective effects in ? photodetachment  

NASA Astrophysics Data System (ADS)

A study of the structure and photodetachment of the 0953-4075/30/19/014/img2 negative ion has been performed using many-body theory. An electron affinity for the 0953-4075/30/19/014/img3 of 0.273 eV was calculated within the Dyson equation method. A new approach for concurrent consideration of intrachannel and interchannel interactions and dynamic-core polarization and relaxation (screening) effects has been developed to calculate the total and partial photodetachment cross sections. The 0953-4075/30/19/014/img4 photoabsorption spectrum reveals a complex interference structure due to correlations between the two outer subshells, primarily strong interaction with the 0953-4075/30/19/014/img5 shape resonance. The influence of many-electron dynamic corrections on the photodetachment process is discussed. The resonance and interference profiles have been shown to be very sensitive to the proper account of collective phenomena. Reasonable agreement between the calculations and experimental data has been achieved.

Kashenock, G. Yu; Ivanov, V. K.

1997-10-01

422

The photorefractive effect  

SciTech Connect

When Arthur Ashkin and his colleagues at Bell Laboratories first noticed the photorefractive effect some 25 years ago, they considered the phenomenon a curiosity at best and a complete nuisance at worst. Today photorefractive materials are being shaped into components for a new generation of computers that exploit light instead of electricity. During the past 25 years investigators have discovered a wide variety of photorefractive materials, including insulators, semiconductors and organic compounds. Photorefractive materials, like film emulsions, change rapidly when exposed to bright light, respond slowly when subjected to dim light and capture sharp detail when struck by some intricate pattern of light. Unlike film, photorefractive materials are erasable: images can be stored or obliterated at whim or by design. By virtue of their sensitivity, robustness, and unique optical properties, photorefractive materials have the potential to be fashioned into data-processing elements for optical computers. In theory, these devices would allow optical computers to process information at much faster rates than their electronic counterparts. Employing photorefractive materials, workers have already developed the optical analogue to the transistor: if two laser beams interact within a photorefractive material, one beam can control, switch or amplify the second beam. Photorefractive materials also lie at the heart of devices that trace the edges of images, that connect networks of lasers and that store three-dimensional images.

Pepper, D.M. (Pepperdine Univ., CA (USA)); Kukhtarev, N.V. (Institute of Physics, Kiev (Ukrainian SSR))

1990-10-01

423

Effectively Rebutting Climate Misinformation  

NASA Astrophysics Data System (ADS)

Climate science faces one of the best funded misinformation campaigns in history. The challenge for climate communicators is that misinformation is extremely difficult to dislodge, even after people understand that it's incorrect. Understanding how the human brain processes information is crucial to successful rebuttal. To avoid the danger of reinforcing misinformation (known as the 'backfire effect'), emphasis should be on positive facts, not the myth. Another key to dislodging myths is replacing them with an alternate narrative. In order to provide a narrative about arguments that misrepresent climate science, a broader understanding of how these arguments mislead is required. Movements that deny a scientific consensus have 5 characteristics in common and these also apply to climate denial. The arguments against the scientific consensus involve conspiracy theories, fake experts, cherry picking, logical fallacies and misrepresentation or impossible expectations. Learning to identify these rhetorical techniques is an important tool in the climate communication toolbox. I discuss examples of misrepresentations of climate science and the rhetorical techniques employed. I demonstrate how to respond to these arguments by explaining the facts of climate science while in the process, providing an alternate narrative.

Cook, J.

2011-12-01

424

Woodward Effect Experimental Verifications  

NASA Astrophysics Data System (ADS)

The work of J. F. Woodward (1990 1996a; 1996b; 1998; 2002a; 2002b; 2004) on the existence of ``mass fluctuations'' and their use in exotic propulsion schemes was examined for possible application in improving space flight propulsion and power generation. Woodward examined Einstein's General Relativity Theory (GRT) and assumed that if the strong Machian interpretation of GRT as well as gravitational / inertia like Wheeler-Feynman radiation reaction forces hold, then when an elementary particle is accelerated through a potential gradient, its rest mass should fluctuate around its mean value during its acceleration. Woodward also used GRT to clarify the precise experimental conditions necessary for observing and exploiting these mass fluctuations or ``Woodward effect'' (W-E). Later, in collaboration with his ex-graduate student T. Mahood, they also pushed the experimental verification boundaries of these proposals. If these purported mass fluctuations occur as Woodward claims, and his assumption that gravity and inertia are both byproducts of the same GRT based phenomenon per Mach's Principle is correct, then many innovative applications such as propellantless propulsion and gravitational exotic matter generators may be feasible. This paper examines the reality of mass fluctuations and the feasibility of using the W-E to design propellantless propulsion devices in the near to mid-term future. The latest experimental results, utilizing MHD-like force rectification systems, will also be presented.

March, Paul

2004-02-01

425

Quantum Wipe Effect  

NASA Astrophysics Data System (ADS)

We consider a model of a spin system under the influence of decoherence such that a system coupled with a dissipating environmental system consisting of either spins or bosonic modes. The dissipation of an environment is governed by a certain probability with which an environmental system localized around a principal system dissipates into a larger bath and a thermal environmental system instead migrates into the place. A certain threshold on the probability is found in the growth of decoherence in a principal system. A larger as well as a smaller dissipation probability than the threshold results in smaller decoherence. This finding is utilized to elucidate a spin relaxation theory of a magnetic resonance spectrometer. In particular, a seamless description of transverse relaxation and motional narrowing is possible. We also numerically evaluate the dynamics of coherence useful for quantum information processing. The bang-bang control and anti-Zeno effect in entanglement and the Oppenheim-Horodecki nonclassical correlation are investigated in the model of spin-boson coupling.

Saitoh, Akira; Rahimi, Robabeh; Nakahara, Mikio

2010-11-01

426

The Second Mössbauer Effect  

NASA Astrophysics Data System (ADS)

"The Second Mössbauer Effect" was the headline of the "Spiegel" (a German weekly journal like the "Times") from May 13, 1964 for announcing the foundation of the "Physik-Department" at the Technische Hochschule München (THM), as it was still called at this time. Maier-Leibnitz was irritated by this headline because the article did not mention at all his contribution to the consolidation of the structure of the three physics institutes (Experimental, Technical, and Theoretical Physics) in the beginning of the sixties. Already in the late fifties ML's Institute for Technical Physics was overloaded with students working on their diploma or doctoral theses, because research in the new field of applied nuclear physics was very attractive and ML had for each student who applied an interesting research project. In the average, ML had to supervise between 150-200 diploma students, an impossible task. So, young postdoctoral students had to help him out by taking over the duties of professors. In a letter to the Bavarian Ministry of Education and Arts in 1957 he complained: "The directors of the institutes are hopelessly surcharged and the institutes are overcrowded, the resources for research projects are totally insufficient and lots of time and energy is wasted for finding additional resources."

Kienle, Paul

427

Perceptual Repetition Blindness Effects  

NASA Technical Reports Server (NTRS)

The phenomenon of repetition blindness (RB) may reveal a new limitation on human perceptual processing. Recently, however, researchers have attributed RB to post-perceptual processes such as memory retrieval and/or reporting biases. The standard rapid serial visual presentation (RSVP) paradigm used in most RB studies is, indeed, open to such objections. Here we investigate RB using a "single-frame" paradigm introduced by Johnston and Hale (1984) in which memory demands are minimal. Subjects made only a single judgement about whether one masked target word was the same or different than a post-target probe. Confidence ratings permitted use of signal detection methods to assess sensitivity and bias effects. In the critical condition for RB a precue of the post-target word was provided prior to the target stimulus (identity precue), so that the required judgement amounted to whether the target did or did not repeat the precue word. In control treatments, the precue was either an unrelated word or a dummy (XXXX). Results of five experiments show that perceptual sensitivity is strikingly and significantly reduced in the RB condition relative to both baseline control conditions. The data show RB can be obtained under conditions in which memory problems are minimal and where perceptual sensitivity is assessed independently of biases.

Hochhaus, Larry; Johnston, James C.; Null, Cynthia H. (Technical Monitor)

1994-01-01

428

Melatonin anticancer effects: review.  

PubMed

Melatonin (N-acetyl-5-methoxytryptamine, MLT), the main hormone produced by the pineal gland, not only regulates circadian rhythm, but also has antioxidant, anti-ageing and immunomodulatory properties. MLT plays an important role in blood composition, medullary dynamics, platelet genesis, vessel endothelia, and in platelet aggregation, leukocyte formula regulation and hemoglobin synthesis. Its significant atoxic, apoptotic, oncostatic, angiogenetic, differentiating and antiproliferative properties against all solid and liquid tumors have also been documented. Thanks, in fact, to its considerable functional versatility, MLT can exert both direct and indirect anticancer effects in factorial synergy with other differentiating, antiproliferative, immunomodulating and trophic molecules that form part of the anticancer treatment formulated by Luigi Di Bella (Di Bella Method, DBM: somatostatin, retinoids, ascorbic acid, vitamin D3, prolactin inhibitors, chondroitin-sulfate). The interaction between MLT and the DBM molecules counters the multiple processes that characterize the neoplastic phenotype (induction, promotion, progression and/or dissemination, tumoral mutation). All these particular characteristics suggest the use of MLT in oncological diseases. PMID:23348932

Di Bella, Giuseppe; Mascia, Fabrizio; Gualano, Luciano; Di Bella, Luigi

2013-01-01

429

Effective sizes for subdivided populations  

SciTech Connect

Many derivations of effective population sizes have been suggested in the literature; however, few account for the breeding structure and none can readily be expanded to subdivided populations. Breeding structures influence gene correlations through their effects on the number of breeding individuals of each sex, the mean number of progeny per female, and the variance in the number of progeny produced by males and females. Additionally, hierarchical structuring in a population is determined by the number of breeding groups and the migration rates of males and females among such groups. This study derives analytical solutions for effective sizes that can be applied to subdivided populations. Parameters that encapsulate breeding structure and subdivision are utilized to derive the traditional inbreeding and variance effective sizes. Also, it is shown that effective sizes can be determined for any hierarchical level of population structure for which gene correlations can accrue. Derivations of effective sizes for the accumulation of gene correlations within breeding groups (coancestral effective size) and among breeding groups (intergroup effective size) are given. The results converge to traditional single population measures when similar assumptions are applied. In particular, inbreeding and intergroup effective sizes are shown to be special cases of the coancestral effective size, and intergroup and variance effective sizes will be equal if the population census remains constant. Instantaneous solutions for effective size, at any time after gene correlation begins to accrue, are given in terms of traditional F statistics or transition equations. All effective sizes are shown to converge upon a common asymptotic value when breeding tactics and migration rates are constant. The asymptotic effective size can be expressed in terms of the fixation indices and the number of breeding groups; however, the rate of approach to the asymptote is dependent upon dispersal rates.

Chesser, R.K. (Savannah River Ecology Lab., Aiken, SC (United States) Univ. of Georgia, Athens, GA (United States)); Rhodes, O.E. Jr.; Sugg, D.W.; Schnabel, A. (Univ. of Georgia, Athens, GA (United States))

1993-12-01

430

The effect of academic inbreeding on scientific effectiveness  

Microsoft Academic Search

In academia, the term “inbreeding” refers to a situation wherein PhDs are employed in the very same institution that trained\\u000a them during their doctoral studies. Academic inbreeding has a negative perception on the account that it damages both scientific\\u000a effectiveness and productivity. In this article, the effect of inbreeding on scientific effectiveness is investigated through\\u000a a case study. This problem

Ozlem Inanc; Onur Tuncer

431

The effect of dipolar interaction on the magnetic isotope effect  

NASA Astrophysics Data System (ADS)

A multi-channel kinetic description is used to study the magnetic isotope effect (MIE) in zero magnetic field. The maximal isotope effect is equal to the number of channels, two for the hyperfine interaction but four for the electron spin dipole-dipole interaction of the intermediate radical pair. Quantum mechanical calculations agree with these conclusion and show that large MIE may be obtained even in the presence of a strong exchange interaction. The observed magnesium isotope effect on the rate of enzymatic synthesis of adenosine triphosphate (ATP) is approximately 3 implying that the dipolar interaction is responsible for the effect. Our calculations provide support for the proposed mechanism.

Pedersen, J. Boiden; Mojaza, Matin; Lukzen, Nikita N.

2010-08-01

432

Surface plasmon effects on carbon nanotube field effect transistors  

NASA Astrophysics Data System (ADS)

Herein, we experimentally demonstrate surface plasmon polariton (SPP) induced changes in the conductivity of a carbon nanotube field effect transistor (CNT FET). SPP excitation is done via Kretschmann configuration while the measured CNT FET is situated on the opposite side of the metal layer away from the laser, but within reach of the launched SPPs. We observe a shift of ~0.4 V in effective gate voltage. SPP-intermediated desorption of physisorbed oxygen from the device is discussed as a likely explanation of the observed effect. This effect is visible even at low SPP intensities and within a near-infrared range.

Isoniemi, T.; Johansson, A.; Hakala, T. K.; Rinkiö, M.; Törmä, P.; Toppari, J. J.; Kunttu, H.

2011-07-01

433

Health effects of phytoestrogens.  

PubMed

Phytoestrogens are naturally occurring plant-derived phytochemicals, whose common biological roles are to protect plants from stress or to act as part of a plant's defense mechanism. Although composed of a wide group of nonsteroidal compounds of diverse structure, phytoestrogens have been shown to bind estrogen receptors and to behave as weak agonist/antagonist in both animals and humans. Phytoestrogens include mainly isoflavones (IF), coumestans, and lignans. These compounds are known to be present in fruits, vegetables, and whole grains commonly consumed by humans. IF are found in legumes--mainly soybeans--whereas flaxseed is a major source of lignans, and coumestans are significantly present in clover, alfalfa and soybean sprouts. 8-Prenyl flavonoids are common in vegetables. Bioavailability of IF requires an initial hydrolysis of the sugar moiety by intestinal beta-glucosidases to allow the following uptake by enterocytes and the flow through the peripheral circulation. Following absorption, IF are then reconjugated mainly to glucuronic acid and to a lesser degree to sulphuric acid. Gut metabolism seems key to the determination of the potency of action. Several epidemiological studies correlated high dose consumptions of soy IF with multiple beneficial effects on breast and prostate cancers, menopausal symptoms, osteoporosis, atherosclerosis and stroke, and neurodegeneration. For the relief of menopausal symptoms a consumption of 60 mg aglycones/day has been suggested; for cancer prevention a consumption between 50 and 110 mg aglycones/day is considered beneficial to reduce risks of breast, colon and prostate cancer; to decrease cardiovascular risk a minimum intake of 40-60 mg aglycones/day, together with about 25 g of soy protein has been suggested. For improvement in bone mineral density, 60-100 mg aglycones/day for a period of at least 6-12 months could be beneficial. PMID:15702593

Branca, Francesco; Lorenzetti, Stefano

2005-01-01

434

[Cardiac effects of GH].  

PubMed

To investigate cardiac effects of excess and deficiency of growth hormone (GH) we studied twenty acromegalic subjects and eleven adult patients with GH deficiency by means of a non invasive method, the Doppler echocardiography. The results obtained in the group of patients were compared with those of two groups of twenty and eleven normal subjects, respectively, age and sex matched. The age of the acromegalic patients ranged from 20 to 62 years. Nineteen patients were considered to have active acromegaly at the time of the study. Mean duration of disease since treatment was 12 +/- 5 years (range 5 to 24 years). The age of GH deficient adults ranged from 21 to 33 years. All these patients have been treated with extractive GH over nine years and the therapy withdrawal was performed at least three years before entering the study. In the group of acromegalic patients, a subgroup including nine patients with mild to moderate hypertension was considered. All subjects gave informed consent and the study protocol was approved by the Ethical Committee of the Medical School of Naples. Right ventricular free wall thickness resulted significantly increased in acromegalic patients (8 +/- 2 vs 4 +/- 1 mm; p < 0.001). Left ventricular mass index was augmented both in the whole group and in the subgroups of normotensive and hypertensive acromegalics as compared with normals (134 +/- 33 p < 0.001, 115 +/- 20 p < 0.01 and 156 +/- 31 p < 0.001 vs 80 +/- 18 g.m-2). Ejection phase indices were normal in patient group, while impaired left and right ventricular diastolic filling was found.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8190051

Fazio, S; Sabatini, D; Cittadini, A; Santomauro, M; Merola, B; Biondi, B; Colao, A; Lombardi, G; Saccà, L

1993-09-01

435

Cardiovascular effects of melanocortins.  

PubMed

Melanocortins (MSH's) are three structurally related peptides derived from proopiomelanocortin. They regulate several physiologic functions including energy metabolism, appetite, and inflammation. Recent work in rodents has also identified important effects of MSH's, particularly ?-MSH, on sodium metabolism and blood pressure regulation. Normal rats and mice respond to a high sodium diet with an increase in the plasma concentration of ?-MSH, and remain normotensive, while those with genetic or pharmacologic ?-MSH deficiency become hypertensive on a high sodium diet. This hypertension is corrected by exogenous administration of the peptide. Mice lacking the ?-MSH receptor (the melanocortin 3 receptor, Mc3r) also become hypertensive on a high sodium diet but remain so when administered ?-MSH, and infusions of physiologic levels of the peptide stimulate urinary sodium excretion in normal rats and mice, but not in mice with deletion of Mc3r. The salt-sensitive hypertension in rodents with impaired ?-MSH signaling appears due to stimulation of noradrenergic activity, since plasma noradrenaline is increased and the hypertension is rapidly corrected with infusion of the ?-adrenoceptor antagonist phentolamine. In contrast to the antihypertensive property of physiologic levels of ?-MSH, intravenous or intracerebroventricular injections of high levels of the peptide raise blood pressure. This occurs in mice lacking Mc3r, indicating an interaction with some other central receptor. Finally, the salt-sensitive hypertension in rodents with disruption of ?-MSH signaling is accompanied by insulin resistance, an observation which offers a new window into the study of the association of salt-sensitive hypertension with insulin resistance and type II diabetes. PMID:21199648

Humphreys, Michael H; Ni, Xi-Ping; Pearce, David

2011-06-11

436

Cardiovascular effects of melanocortins  

PubMed Central

Melanocortins (MSH’s) are three structurally related peptides derived from proopiomelanocortin. They regulate several physiologic functions including energy metabolism, appetite, and inflammation. Recent work in rodents has also identified important effects of MSH’s, particularly ?-MSH, on sodium metabolism and blood pressure regulation. Normal rats and mice respond to a high sodium diet with an increase in the plasma concentration of ?-MSH, and remain normotensive, while those with genetic or pharmacologic ?-MSH deficiency become hypertensive on a high sodium diet. This hypertension is corrected by exogenous administration of the peptide. Mice lacking the ?-MSH receptor (the melanocortin 3 receptor, Mc3r) also become hypertensive on a high sodium diet but remain so when administered ?-MSH, and infusions of physiologic levels of the peptide stimulate urinary sodium excretion in normal rats and mice, but not in mice with deletion of Mc3r. The salt-sensitive hypertension in rodents with impaired ?-MSH signaling appears due to stimulation of noradrenergic activity, since plasma noradrenaline is increased and the hypertension is rapidly corrected with infusion of the ?-adrenoceptor antagonist phentolamine. In contrast to the antihypertensive property of physiologic levels of ?-MSH, intravenous or intracerebroventircular injections of high levels of the peptide raise blood pressure. This occurs in mice lacking Mc3r, indicating an interaction with some other central receptor. Finally, the salt-sensitive hypertension in rodents with disruption of ?-MSH signaling is accompanied by insulin resistance, an observation which offers a new window into the study of the association of salt-sensitive hypertension with insulin resistance and type II diabetes.

Humphreys, Michael H.; Ni, Xi-Ping; Pearce, David

2011-01-01

437

Paradoxical and bidirectional drug effects.  

PubMed

A paradoxical drug reaction constitutes an outcome that is opposite from the outcome that would be expected from the drug's known actions. There are three types: 1. A paradoxical response in a condition for which the drug is being explicitly prescribed. 2. Paradoxical precipitation of a condition for which the drug is indicated, when the drug is being used for an alternative indication. 3. Effects that are paradoxical in relation to an aspect of the pharmacology of the drug but unrelated to the usual indication. In bidirectional drug reactions, a drug may produce opposite effects, either in the same or different individuals, the effects usually being different from the expected beneficial effect. Paradoxical and bidirectional drug effects can sometimes be harnessed for benefit; some may be adverse. Such reactions arise in a wide variety of drug classes. Some are common; others are reported in single case reports. Paradoxical effects are often adverse, since they are opposite the direction of the expected effect. They may complicate the assessment of adverse drug reactions, pharmacovigilance, and clinical management. Bidirectional effects may be clinically useful or adverse. From a clinical toxicological perspective, altered pharmacokinetics or pharmacodynamics in overdose may exacerbate paradoxical and bidirectional effects. Certain antidotes have paradoxical attributes, complicating management. Apparent clinical paradoxical or bidirectional effects and reactions ensue when conflicts arise at different levels in self-regulating biological systems, as complexity increases from subcellular components, such as receptors, to cells, tissues, organs, and the whole individual. These may be incompletely understood. Mechanisms of such effects include different actions at the same receptor, owing to changes with time and downstream effects; stereochemical effects; multiple receptor targets with or without associated temporal effects; antibody-mediated reactions; three-dimensional architectural constraints; pharmacokinetic competing compartment effects; disruption and non-linear effects in oscillating systems, systemic overcompensation, and other higher-level feedback mechanisms and feedback response loops at multiple levels. Here we review and provide a compendium of multiple class effects and individual reactions, relevant mechanisms, and specific clinical toxicological considerations of antibiotics, immune modulators, antineoplastic drugs, and cardiovascular, CNS, dermal, endocrine, musculoskeletal, gastrointestinal, haematological, respiratory, and psychotropic agents. PMID:22272687

Smith, Silas W; Hauben, Manfred; Aronson, Jeffrey K

2012-03-01

438

Reverse coffee-ring effect  

NASA Astrophysics Data System (ADS)

When a coffee drop dries on a solid surface, it commonly leaves a ring-like deposit along the edge, known as the coffee-ring effect. We present a reverse motion of particles in drying droplets, opposite to the coffee-ring effect. We reveal that the particle motion, initially toward the edge by the typical coffee-ring effect, is reversed to the droplet center owing to the capillary interaction generated by the droplet surface. The reverse coffee-ring effect always occurs whenever the capillary interaction prevails over the net outward force by the coffee- ring effect. The interaction predicts an inverse power-law time growth of moving distance from the edge, depending mostly on particle size and contact angle. The reverse coffee-ring effect may contribute to multiple ring formation by sweeping particles toward the center. We prove the mechanism with real-time optical, confocal, and X-ray microscopic observations of colloidal fluids.

Mook Weon, Byung; Xu, Lei; Je, Jung Ho; Hwu, Yeukuang; Margaritondo, Giorgio; Weitz, David A.

2009-03-01

439

Effects of sea spray geoengineering  

NASA Astrophysics Data System (ADS)

Anthropogenic climate warming is leading to consideration of options for geoengineering to offset rising carbon dioxide levels. One potential technique involves injecting artificial sea spray into the atmosphere. The sea salt particles would affect Earth's radiation budget directly, by scattering incoming solar radiation, and indirectly, by acting as cloud condensation nuclei, which could lead to whiter clouds that reflect more radiation. However, the potential effects of this method, especially the direct effects, are not fully known. Partanen et al. studied the effects of artificial sea spray using climate model simulations. They found that outside of the most heavily clouded regions the direct effect of scattering of radiation was an important part of the total effect. They also examined the effect of particle size and found that decreasing the size of injected particles could improve the efficiency of the geoengineering technique.

Balcerak, Ernie

2012-03-01

440

Genetic Effects of Electromagnetic Waves  

NASA Astrophysics Data System (ADS)

The genetic effects of electromagnetic waves can be detected by different test-systems. The mutagenic effect of ionizing radiation can be developed on the levels of DNA and/or chromosomes. In numerous researches efficiency of micronucleus assay, alkaline single-cell gel electrophoresis, chromosomal aberrations test and FISH-technique and their different combinations for the detection of ionizing radiation-induced genotoxic effects are discussed. Also some molecular-biological approaches developed in the last years are presented.

Aroutiounian, Rouben; Hovhannisyan, Galina; Gasparian, Gennady

441

Thermoelectric effects in magnetic nanostructures  

Microsoft Academic Search

We model and evaluate the Peltier and Seebeck effects in magnetic multilayer nanostructures by a finite-element theory of thermoelectric properties. We present analytical expressions for the thermopower and the current-induced temperature changes due to Peltier cooling\\/heating. The thermopower of a magnetic element is in general spin polarized, leading to spin-heat coupling effects. Thermoelectric effects in spin valves depend on the

Moosa Hatami; Gerrit E. W. Bauer; Qinfang Zhang; Paul J. Kelly

2009-01-01

442

Gravitational Effect on Internal Conversion  

Microsoft Academic Search

A simple model to estimate the effect of gravitational field produced by an ultracentrifuge on internal-conversion process of radioactive nuclide is presented. The calculation has been made for the 2.17-keV E3 transition of ssmTc. The possibility for experimental detection of this effect is discussed. It is well known that the extranuclear fields produced by environmental effects, such as chemical bonding

Takeshi MUKOYAMA; Rintaro KATANO

443

Microstructural effects in shock ignition  

SciTech Connect

The dynamic response of explosive microstructures has been explicitly modeled, with the intention of gaining insight into initiation processes from hotspot formation to transition to detonation. In this paper, the authors focus attention upon the inert material response leading to hotspot ignition. Of interest are particle size and shape effects, constitutive effects of both binder and explosive, and their importance to hotspot formation. Effects of chemical reaction are considered elsewhere.

Conley, P.; Benson, D. [Univ. of California, San Diego, CA (United States); Howe, P.M. [Los Alamos National Lab., NM (United States)

1998-07-01

444

(Theory of relative biological effectiveness)  

SciTech Connect

Research continued on relative biological effectiveness, in the following areas: radial distribution of dose about the path of an energetic heavy ion; the response of E. Coli mutants to ionizing radiations; the application of a fragmentation model to to the calculation of cell survival and mutation with heavy ion beams; biological radiation effects from gamma radiation and heavy ion beams on organisms; cancer induction in the Harderian Gland by HZE particles; and effects of low dose radiations. (CBS)

Katz, R.

1992-06-15

445

Biomedical effects of laser application  

Microsoft Academic Search

This paper briefly reviews the authors experimental and clinical use of lasers over a 20-year period, during which laser effects on 15 biological systems were studied. Low-energy laser radiation was found to have a stimulating effect on cells, and high-energy radiation had an inhibiting effect. The application of lasers to stimulate wound healing in cases of nonhealing ulcers is recommended.

Endre Mester; Andrew F. Mester; Adam Mester

1985-01-01

446

Twisted mass finite volume effects  

SciTech Connect

We calculate finite-volume effects on the pion masses and decay constant in twisted mass lattice QCD at finite lattice spacing. We show that the lighter neutral pion in twisted mass lattice QCD gives rise to finite-volume effects that are exponentially enhanced when compared to those arising from the heavier charged pions. We demonstrate that the recent two flavor twisted mass lattice data can be better fitted when twisted mass effects in finite-volume corrections are taken into account.

Colangelo, Gilberto; Wenger, Urs; Wu, Jackson M. S. [Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, 3012 Bern (Switzerland)

2010-08-01

447

Semiotics and the placebo effect.  

PubMed

Despite substantial progress in elucidating its neurobiological mechanisms, theoretical understanding of the placebo effect is poorly developed. Application of the semiotic theory developed by the American philosopher Charles Peirce offers a promising account of placebo effects as involving the apprehension and response to signs. The semiotic approach dovetails with the various psychological mechanisms invoked to account for placebo effects, such as conditioning and expectation, and bridges the biological and cultural dimensions of this fascinating phenomenon. PMID:21037405

Miller, Franklin G; Colloca, Luana

2010-01-01

448

Safety and effectiveness of vasectomy  

Microsoft Academic Search

Objective: To recommend further research on vasectomy based on a systematic review of the effectiveness and safety of vasectomy.Design: A systematic MEDLINE review of the literature on the safety and effectiveness of vasectomy between 1964 and 1998.Main Outcome Measure(s): Early failure rates are Conclusion(s): Publications to date continue to support the conclusion that vasectomy is a highly effective form of

Pamela J Schwingl; Harry A Guess

2000-01-01

449

The Thirring-Lense Effect  

NASA Astrophysics Data System (ADS)

The Thirring-Lense effect is the phenomenon that an observer near a rotating mass, being in a state which is non-rotating with respect to the rest of the universe, experiences extra inertial forces, i.e. becomes dizzy. The first anticipation of the effect goes back to Ernst Mach; its first quantitative prediction on the basis of general relativity was given by Hans Thirring and Joseph Lense. Almost ninety years later, the effect seems to be experimentally verified.

Embacher, Franz

450

Radiation Effects: Core Project  

NASA Technical Reports Server (NTRS)

The risks to personnel in space from the naturally occurring radiations are generally considered to be one of the most serious limitations to human space missions, as noted in two recent reports of the National Research Council/National Academy of Sciences. The Core Project of the Radiation Effects Team for the National Space Biomedical Research Institute is the consequences of radiations in space in order to develop countermeasure, both physical and pharmaceutical, to reduce the risks of cancer and other diseases associated with such exposures. During interplanetary missions, personnel in space will be exposed to galactic cosmic rays, including high-energy protons and energetic ions with atomic masses of iron or higher. In addition, solar events will produce radiation fields of high intensity for short but irregular durations. The level of intensity of these radiations is considerably higher than that on Earth's surface, and the biological risks to astronauts is consequently increased, including increased risks of carcinogenesis and other diseases. This group is examining the risk of cancers resulting from low-dose, low-dose rate exposures of model systems to photons, protons, and iron by using ground-based accelerators which are capable of producing beams of protons, iron, and other heavy ions at energies comparable to those encountered in space. They have begun the first series of experiments using a 1-GeV iron beam at the Brookhaven National Laboratory and 250-MeV protons at Loma Linda University Medical Center's proton synchrotron facility. As part of these studies, this group will be investigating the potential for the pharmaceutical, Tamoxifen, to reduce the risk of breast cancer in astronauts exposed to the level of doses and particle types expected in space. Theoretical studies are being carried out in a collaboration between scientists at NASA's Johnson Space Center and Johns Hopkins University in parallel with the experimental program have provided methods and predictions which are being used to assess the levels of risks to be encountered and to evaluate appropriate strategies for countermeasures. Although the work in this project is primarily directed toward problems associated with space travel, the problem of protracted exposures to low-levels of radiation is one of national interest in our energy and defense programs, and the results may suggest new paradigms for addressing such risks.

Dicello, John F.

1999-01-01

451

Magnetocaloric effect in manganites  

SciTech Connect

The magnetocaloric effect (MCE) in La{sub 1-x}Sr{sub x}MnO{sub 3}, Sm{sub 0.55}Sr{sub 0.45}MnO{sub 3}, and PrBaMn{sub 2}O{sub 6} compounds is studied. The maximum values of MCE ({Delta}T{sub max}) determined by a direct method in the second and third compositions and in La{sub 0.9}Sr{sub 0.1}MnO{sub 3} are found to be much lower than those calculated from the change of the magnetic part of entropy in the Curie temperature (T{sub C}) and the Neel temperature (T{sub N}) range. The negative contribution of the antiferromagnetic (AFM) part of a sample in the La{sub 1-x}Sr{sub x}MnO{sub 3} system at 0.1 {<=} x {<=} 0.3 decreases {Delta}T{sub max} and changes the {Delta}T(T) curve shape, shifting its maximum 20-40 K above T{sub C}. Lower values of {Delta}T{sub max} are detected in the range T{sub C} = 130-142 K in polycrystalline and single-crystal Sm{sub 0.55}Sr{sub 0.45}MnO{sub 3} samples cooled in air. If such samples were cooled in an oxygen atmosphere (which restores broken Mn-O-Mn bonds and, thus, increases the volume of CE-type AFM clusters), the maximum in the temperature dependence of MCE is located at T{sub N} (243 K) for CE-type AFM clusters. A magnetic field applied to a sample during the MCE measurements transforms these clusters into a ferromagnetic (FM) state, and both types of clusters decompose at T = T{sub N}. The PrBaMn{sub 2}O{sub 6} composition undergoes an AFM-FM transition at 231 K, and the temperature dependence of its MCE has a sharp minimum at T = 234 K, where MCE is negative, and a broad maximum covering T{sub C}. The absolute values of MCE at both extrema are several times lower than those calculated from the change in the magnetic entropy. These phenomena are explained by the presence of a magnetically heterogeneous FM-AFM state in these manganites.

Koroleva, L. I., E-mail: koroleva@phys.msu.ru; Zashchirinskii, D. M.; Morozov, A. S. [Moscow State University (Russian Federation); Szymczak, R. [Polish Academy of Sciences, Institute of Physics (Poland)

2012-10-15

452

Massive high density effective theory  

SciTech Connect

I derive an effective theory for dense, cold, and massive quark matter. To this end, I employ a general effective action formalism where antiquarks and quarks far from the Fermi surface, as well as hard gluons, are integrated out explicitly. I show that the resulting effective action depends crucially on the projectors used to separate quarks from antiquarks. If one neglects the quark masses in these projectors, the Feynman rules of the effective theory involve quark mass insertions which connect quark with antiquark propagators. Including the quark masses into these projectors, mass insertions do not appear and the Feynman rules are identical to those found in the zero-mass limit.

Reuter, Philipp T. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada)

2007-12-15

453

Features which separate least effective from most effective science teachers  

Microsoft Academic Search

Sixty-one science supervisors identified 321 teachers, 162 most effective and 159 least effective, in their respective districts. Information was then sought concerning age, gender, teaching field(s), number of preparations, amount of preparation, time, semester hours of undergraduate science preparation, quantity of graduate science preparation, type of teacher education programs, number of weeks of NSF workshop experience, and number of workshops

Robert E. Yager; Eddy M. Hidayat; John E. Penick

1988-01-01

454

TOLUENE DOSE-EFFECT META ANALYSIS AND IMPORTANCE OF EFFECTS  

EPA Science Inventory

TOLUENE DOSE-EFFECT META ANALYSES AND IMPORTANCE OF EFFECTS Benignus, V.A., Research Psychologist, ORD, NHEERL, Human Studies Division, 919-966-6242, benignus.vernon@epa.gov Boyes, W.K., Supervisory Health Scientist, ORD, NHEERL, Neurotoxicology Division 919-541-...

455

The Effect of Information Overlap on Communication Effectiveness  

ERIC Educational Resources Information Center

It makes sense that the more information people share, the better they communicate. To evaluate the effect of knowledge overlap on the effectiveness of communication, participants played a communication game where the "director" identified objects to the "addressee". Pairs either shared information about most objects' names (high overlap), or…

Wu, Shali; Keysar, Boaz

2007-01-01

456

Effects beyond Effectiveness: Teaching as a Performative Act  

ERIC Educational Resources Information Center

This article develops the familiar metaphor of teaching as performance towards a definition of "teaching as performative act," where words and actions aim to effect cognitive, affective, and behavioral changes in learners. To what extent, however, are the consequences of pedagogical actions commensurate with their intended effects? Can a science…

Liew, Warren Mark

2013-01-01

457

The Effect of Homework on Students' Perceptions of Teaching Effectiveness.  

ERIC Educational Resources Information Center

A comparison was made of student evaluations of teacher effectiveness following two approaches: classes with no homework (n=110) and classes with daily homework (n=170). Grades were higher and student evaluations of teacher effectiveness were greater in classes with daily homework assignments. (JOW)

Dudley, Sid; Shawver, Donald L.

1991-01-01

458

Extracting contact effects in organic field-effect transistors  

Microsoft Academic Search

Contact resistances between organic semiconductors and metal electrodes have been shown to play a dominant role in electronic charge injection properties of organic field-effect transistors. These effects are more prevalent in short channel length devices and therefore should not be ignored when examining intrinsic properties such as the mobility and its dependence on temperature or gate voltage. Here we outline

B. H. Hamadani; Douglas Natelson

2005-01-01

459

Effective Potential and Effective Hamiltonian in Quantum Statistical Mechanics.  

National Technical Information Service (NTIS)

An overview on the theoretic formalism and up to date applications in quantum condensed matter physics of the effective potential and effective hamiltonian methods is given. The main steps of their unified derivation by the so-called pure-quantum self-con...

A. Cuccoli R. Giachetti V. Tognetti R. Vaia P. Verrucchi

1995-01-01

460

Radiation effects on livestock: physiological effects, dose response  

Microsoft Academic Search

Farm livestock show no measurable effects from being exposed to ionizing radiation unless the level is greatly in excess of the natural background radiation. Possible sources of ionizing radiation which might affect livestock or contribute to radioactivity in the food chain to humans are reactor accidents, fuel reprocessing plant accidents and thermonuclear explosions. Most data on ionizing radiation effects on

Bell

1985-01-01

461

Space charge effect and mirror charge effect in photoemission spectroscopy  

SciTech Connect

We report the observation and systematic investigation of the space charge effect and mirror charge effect in photoemission spectroscopy. When pulsed light is incident on a sample, the photoemitted electrons experience energy redistribution after escaping from the surface because of the Coulomb interaction between them (space charge effect) and between photoemitted electrons and the distribution of mirror charges in the sample (mirror charge effect). These combined Coulomb interaction effects give rise to an energy shift and a broadening which can be on the order of 10 meV for a typical third-generation synchrotron light source. This value is comparable to many fundamental physical parameters actively studied by photoemission spectroscopy and should be taken seriously in interpreting photoemission data and in designing next generation experiments.

Zhou, X.J.; Wannberg, B.; Yang, W.L.; Brouet, V.; Sun, S.; Douglas, J.F.; Dessau, D.; Hussain, Z.; Shen, Z.-X.

2004-08-17

462

A side effect resource to capture phenotypic effects of drugs  

PubMed Central

The molecular understanding of phenotypes caused by drugs in humans is essential for elucidating mechanisms of action and for developing personalized medicines. Side effects of drugs (also known as adverse drug reactions) are an important source of human phenotypic information, but so far research on this topic has been hampered by insufficient accessibility of data. Consequently, we have developed a public, computer-readable side effect resource (SIDER) that connects 888 drugs to 1450 side effect terms. It contains information on frequency in patients for one-third of the drug–side effect pairs. For 199 drugs, the side effect frequency of placebo administration could also be extracted. We illustrate the potential of SIDER with a number of analyses. The resource is freely available for academic research at http://sideeffects.embl.de.

Kuhn, Michael; Campillos, Monica; Letunic, Ivica; Jensen, Lars Juhl; Bork, Peer

2010-01-01

463

Effect of orientation anisotropy on calculating effective electrical conductivities  

NASA Astrophysics Data System (ADS)

This paper develops an analytical effective medium theory (EMT) equation for calculating the effective conductivity of a mixture based on Maxwell's and Maxwell-Garnett's theories, extended to higher volume fractions using Bruggeman's unsymmetrical treatment (BUT), with a long term goal of extending the treatment to mixtures more representative of real materials in order to calculate their effective electrical conductivity. The development accounts for spheroid shaped inclusions of varying degrees of anisotropic orientation. The orientation is described by the introduction of a distribution function. Two methodologies valid for the inclusion dilute limit were used to evaluate the effective conductivity: one based on Maxwell's far field approach, and the other based on the Maxwell-Garnett in the matrix approach. It was found that while the dilute limit equations for the effective conductivity were different, the final EMT equations derived by applying BUT collapsed to the same formula which was generalized for anisotropic orientation based on the distribution function presented.

Myles, Timothy D.; Peracchio, Aldo A.; Chiu, Wilson K. S.

2014-05-01

464

ENVIRONMENTAL EFFECTS OF EXTREME FLOODS  

Microsoft Academic Search

Analyzing short- and long-term environmental effects of extreme flood events is a young science. Complicated by the obvious difficulties associated with predicting extreme events and the hazards of gathering environmental data during and in the aftermath of these often short-lived and violent events, the accumulation of good field data remains an obstacle to a better understanding of quantitative effects. This

John T. Hickey; Jose D. Salas

465

The Effective Teacher of Reading.  

ERIC Educational Resources Information Center

The improvement of teaching characteristics and teacher behavior are important issues when discussing reading programs. Therefore, the following six major questions and conclusions about the effective reading teacher comprise the emphasis of this discussion. (1) What criteria can be used to measure teacher effectiveness? The main criterion used is…

Harris, Albert J.

466

Age Effects in Information Processing.  

ERIC Educational Resources Information Center

Attempts to modify or ameliorate the effects of declining cognitive abilities of the elderly have met with limited success. To focus on the effects of age in cognitive processing capacity (CPC), Furukawa's (1977) CPC test was administered individually to 3 age groups (16-30, 31-45, and 45-60) of 15 subjects each. Speed of processing old and new…

Furukawa, James M.; And Others

467

Ecosystem effects of marine fisheries  

Microsoft Academic Search

Most fisheries literature avoids speaking about ecosystem impacts of fishing, either because impacts are not demonstrated or because a causal relationship between impacts and fishing cannot be formally established with the available information. However, there is mounting evidence that fishing has undesired effects in the marine ecosystems. This overview examines the wide ecosystem effects of fishing, describing and illustrating the

R Goñi

1998-01-01

468

The Effective Elementary School Principal.  

ERIC Educational Resources Information Center

Aimed at both practicing administrators and university education professors, this book discriminates among certain "E-words" ("effective,""efficient,""excellent," and "empowerment") in the educational reform lexicon. According to the introductory chapter, levels of effectiveness, efficiency, and excellence operate as interrelated factors within…

Pankake, Anita M.; Burnett, I. Emett, Jr.

469

Effective Evaluation through Appreciative Inquiry  

ERIC Educational Resources Information Center

Evaluators in the HPI field can improve their performance program results with effective evaluation through appreciative inquiry. Appreciative inquiry and evaluation have many similarities, and when combined they add value and effectiveness to the measurement of intervention results. Appreciative inquiry is beneficial in many evaluation contexts:…

Dunlap, Cheryl A.

2008-01-01

470

Surface Effect Ships for Commerce.  

National Technical Information Service (NTIS)

Ships using the surface effect principle have been suggested as a means of improving the transport of U.S. international commerce. The functional principles of the surface effect ships (SES) appear to offer an avenue for developing transoceanic vehicles p...

1966-01-01

471

Polarization effect of electroactive cellulose  

Microsoft Academic Search

The piezoelectric effect of electroactive cellulose has been studied. Hardwood and softwood papers were selected to estimate a bending actuation performance in connection with electromechanical coupling factors. The cantilever unimorph actuators are considered. The results show that the coupling is highly non-linear particularly at high k31 for both papers but not at low k31. The effect of the thickness ratio

Chung-Hwan Je; Kwang J. Kim

2003-01-01

472

Single and Multiple Touschek Effects.  

National Technical Information Service (NTIS)

The Touschek effect, where the change in the direction of a particle's momentum can lead to a strong variation of its energy due to a relativistic effect, leading to the loss of the particle if the relative energy variation exceeds the energy acceptance o...

J. Le Duff

1988-01-01

473

Cell cycle effects of drugs  

SciTech Connect

This book contains 11 chapters. Some of the chapter titles are: Cell Growth and Division Cycle; Cell Cycle Effects of Alkylating Agents; Biological Effects of Folic Acid Antagonists with Antineoplastic Activity; and Bleomycin-Mode of Action with Particular Reference to the Cell Cycle.

Dethlefsen, L.A.

1986-01-01

474

Fuels research: Combustion effects overview  

NASA Technical Reports Server (NTRS)

The effects of broadened property fuels on gas turbine combustors were assessed. Those physical and chemical properties of fuels that affect aviation gas turbine combustion were isolated and identified. Combustion sensitivity to variations in particular fuel properties were determined. Advanced combustion concepts and subcomponents that could lessen the effect of using broadened property fuels were also identified.

Haggard, J. B., Jr.

1980-01-01

475

Neighbourhood effects and housing demand  

Microsoft Academic Search

In this paper, we estimate a model of housing demand with neighbourhood effects. We exploit special features of the national sample of the American Housing Survey and properties of housing markets that allow us to create 'natural' instruments and therefore identify the impact of social interactions. We find evidence of both endogenous and contextual neighbourhood effects. We report two alternative

Yannis M. Ioannides; Jeffrey E. Zabel

2003-01-01

476

Importance of Effective Listening Infomercial  

ERIC Educational Resources Information Center

This article details an activity intended for use in a course with a unit on effective listening, including listening courses, public speaking, and interpersonal communication. Students will explain the importance of effective and active listening for a target audience by producing an infomercial for a product or service which they design.

Johnson-Curiskis, Nanette

2009-01-01

477

Mechanical effects in cookoff modeling  

Microsoft Academic Search

Complete cookoff modeling of energetic material in confined geometries must couple thermal, chemical and mechanical effects. In the past, modeling has focused on the prediction of the onset of combustion behavior based only on thermal-chemistry effects with little or no regard to the mechanical behavior of the energetic material. In this paper, an analysis tool is outlined which couples thermal,

R. J. Gross; M. R. Baer; M. L. Hobbs

1994-01-01

478

Passive cooling effects of courtyards  

Microsoft Academic Search

The passive cooling effects of a courtyard of a small building were determined numerically, employing an energy-analysis software developed for that purpose. The passive cooling features considered were the shading effects of courtyard walls and two large trees (of various shapes) planted immediately next to the south wall of the building, the presence of a pool, a lawn and flowers

H. Safarzadeh; M. N. Bahadori

2005-01-01

479

Effects of Ritalin on Reading.  

ERIC Educational Resources Information Center

This article describes the use of "Ritalin" to calm overactive children. The drug's side effects are reported, and research on the effect of "Ritalin" on reading performance in the classroom is reviewed. It is concluded that use of stimulant drugs to help reading underachievers is not supported by research. (Author/JDD)

Cooter, Robert B., Jr.

1988-01-01

480

Space environment effects (M0006)  

NASA Technical Reports Server (NTRS)

The effects of long term exposure to the near Earth space environment on advanced electrooptical and radiation sensor components were examined. The effect of long duration spaceflight on the germination rate of selected terrestrial plant seeds is observed in exobiological experiments.

Angelo, J. A., Jr.; Madonna, R. G.; Altadonna, L. P.; Dagostino, M. D.; Chang, J. Y.; Alfano, R. R.; Caplan, V. L.

1984-01-01

481

Effect Size in Clinical Phonology  

ERIC Educational Resources Information Center

The purpose of this article is to motivate the use of effect size (ES) for single-subject research in clinical phonology, with an eye towards meta-analyses of treatment effects for children with phonological disorders. Standard mean difference (SMD) is introduced and illustrated as one ES well suited to the multiple baseline (MBL) design and…

Gierut, Judith A.; Morrisette, Michele L.

2011-01-01

482

Health effects of diesel emissions  

Microsoft Academic Search

f-We have reviewed the literature relating to the health effects of diesel emissions with particular reference to acute and chronic morbidity and to carcinogenici ty. It is apparent that exposure to diesel fumes in sufficient concentrations may lead to eye and nasal irritation but there is no evidence of any permanent effect. A transient decline of ventilatory capacity has been

W. K. C. Morgan; R. B. Regerf; D. M. Tucker

1997-01-01

483

Unemployment effects of climate policy  

Microsoft Academic Search

This paper models the unemployment effects of restrictions on greenhouse gas emissions, embodying two of the most significant types of short-term economic imperfections that generate unemployment: sectoral rigidities in labor mobility and sectoral rigidities in wage adjustments. A labor policy is also analyzed that would reduce the direct negative economic effects of the emissions restrictions.The politics of limiting greenhouse gas

Mustafa H. Babiker; Richard S. Eckaus

2007-01-01

484

Effective Advocacy for Staff Development.  

ERIC Educational Resources Information Center

Effective advocacy for staff development requires actions to develop support from in- and outside the school district. Advocacy involves vision, commitment, outreach, good planning, proof of program quality and effectiveness, alignment of staff development and school district goals, and understanding of client concerns. (SM)

Asayesh, Gelareh

1994-01-01

485

Evaluating Effectiveness in Computing Centers.  

ERIC Educational Resources Information Center

The goal model is appropriate for evaluating effectiveness in complex service organizations because there are measurable outputs. An empirical method is provided for the identification and measurement of organizational goals. Perception of effectiveness could be improved if goals were made to coincide with the desires of user groups. (DWH)

Varanelli, Andrew

1981-01-01

486

Health Effects of Air Pollution  

MedlinePLUS

Health effects of air pollution Breathing air that is not clean can hurt your health. Sometimes you have control over how clean the air ... important to know about the health effects that air pollution can have on you and others. Once you ...

487

Hiring Effective Secondary School Counselors  

ERIC Educational Resources Information Center

Today's effective school counselors are integral in education reform, school leadership, and student achievement. It is typically the responsibility of building principals to hire effective school counselors. This article builds on previous literature and provides principals with questions to ask and information to gather that may be helpful in…

McGlothlin, Jason M.; Miller, Lynne Guillot

2008-01-01

488

Effect of topiramate on attention  

Microsoft Academic Search

Impaired attention is a frequently reported side effect of anti-epileptic medication, as well as a frequent general complaint of epilepsy. It is thus important to evaluate the effect of new medications on attention processes. Attention was assessed weekly in ten subjects receiving topiramate over a 3 month period. Attention was evaluated with digit span, a widely used index of attention.

Leslie A Burton; Cynthia Harden

1997-01-01

489

Correlation effects and bound states  

SciTech Connect

Bound states in a simple quark model that are due to correlation effects are analyzed. The confining properties of this model in meson (quark-antiquark and diquark) channels manifest themselves at any quark momenta, and an extra potential field may only enhance the confining effect.

Zinovjev, G. M. [National Academy of Sciences of Ukraine, Bogolyubov Institute for Theoretical Physics (Ukraine); Molodtsov, S. V., E-mail: molodtsov@itep.ru [Joint Institute for Nuclear Research (Russian Federation)

2012-11-15

490

Measuring the Effects of Schooling.  

ERIC Educational Resources Information Center

A simple statistical model to measure the effects of innovation and schooling is proposed. Synthesis of 134 meta-analyses revealed that educational innovations can be expected to change average achievement by 0.4 standards deviations and affective outcomes by 0.2 standard deviations. Innovation and feedback appear to enhance effects;…

Hattie, John

1992-01-01

491

The Greenhouse Effect Does Exist!  

Microsoft Academic Search

In particular, without the greenhouse effect, essential features of the atmospheric temperature profile as a function of height cannot be described, i.e., the existence of the tropopause above which we see an almost isothermal temperature curve, whereas beneath it the temperature curve is nearly adiabatic. The relationship between the greenhouse effect and observed temperature curve is explained and the paper

Jochen Ebel

2009-01-01

492

Superconducting Field-Effect Transistors  

NASA Technical Reports Server (NTRS)

Devices offer switching speeds greater than semiconducting counterparts. High-Tc superconducting field-effect transistors (SUPEFETs) investigated for use as electronic switches in delay-line-type microwave phase shifters. Resemble semiconductor field-effect transistors in some respects, but their operation based on different principle; namely, electric-field control of transition between superconductivity and normal conductivity.

Bhasin, Kul; Romanofsky, Robert R.; Tabib-Azar, Massood

1995-01-01

493

Side effects of generic competition?  

Microsoft Academic Search

This study examined the relationship between generic drug market shares and the number of reported side effects. Yearly time-series data for the number of reported side effects and information on market shares, prices, and quantities from 1972 to 1996 were used in this study. Poisson and negative binomial regression models were used in the statistical analysis. The results show that

Jörgen Hellström; Niklas Rudholm

2004-01-01

494

Ablation Effects on Vehicle Dynamics.  

National Technical Information Service (NTIS)

The effects of ablation on re-entry body dynamics is a problem that during recent years has advanced from one of general interest to one of general concern. An exploratory analysis shows that ablation will have opposite effects on static and dynamic stabi...

L. E. Ericsson J. P. Reding

1966-01-01

495

Animation About the Greenhouse Effect  

NSDL National Science Digital Library

This is a basic animation/simulation with background information about the greenhouse effect by DAMOCLES. The animation has several layers to it that allow users to drill into more detail about the natural greenhouse effect and different aspects of it, including volcanic aerosols and human impacts from burning fossil fuels.

Damocles

496

Stereoelectronic effects in mass spectrometry  

NASA Astrophysics Data System (ADS)

Simple bond dissociations and hydrogen rearrangements in gaseous cation radicals and even-electron cations can be governed by stereoelectronic effects imposed by control elements. Stereoelectronic effects facilitate dissociations of bonds that are aligned with the control orbital of n- or [pi]-type to allow efficient orbital overlap in the transition state. Ions with unfavorably large dihedral angles between the bond to be broken and the control orbital undergo conformational transformations in order to achieve a stereoelectronically assisted transition state. Stereoelectronic effects are likely to be encountered with rigid polycyclic ions in which fixed dihedral angles are imposed by bond connectivity. Nevertheless, striking stereoelectronic effects have been observed in a few conformationally mobile systems. Several examples of stereo- chemical ion dissociation due to stereoelectronic effects are discussed in this review with the help of experimental energy data, and ab initio, semi-empirical, and empirical-potential (MM2) calculations.

Turec[Combining Breve]Ek, Frantis[Combining Breve]Ek

1991-10-01

497

Fetal effects of psychoactive drugs.  

PubMed

Psychoactive drug use by pregnant women has the potential to effect fetal development; the effects are often thought to be drug-specific and gestational age dependent. This article describes the effects of three drugs with similar molecular targets that involve monoaminergic transmitter systems: cocaine, methamphetamine, and selective serotonin re-uptake inhibitors (SSRIs) used to treat maternal depression during pregnancy. We propose a possible common epigenetic mechanism for their potential effects on the developing child. We suggest that exposure to these substances acts as a stressor that affects fetal programming, disrupts fetal placental monoamine transporter expression and alters neuroendocrine and neurotransmitter system development. We also discuss neurobehavioral techniques that may be useful in the early detection of the effects of in utero drug exposure. PMID:19732616

Salisbury, Amy L; Ponder, Kathryn L; Padbury, James F; Lester, Barry M

2009-09-01

498

Peltier effects in Andreev interferometers  

NASA Astrophysics Data System (ADS)

The superconducting proximity effect is known to modify transport properties of hybrid normal-superconducting structures. In addition to changing electrical and thermal transport separately, it alters the thermoelectric effects. Changes to one off-diagonal element L12 of the thermoelectric matrix L have previously been studied via the thermopower, but the remaining coefficient L21 , which is responsible for the Peltier effect, has received less attention. We discuss symmetry relations between L21 and L12 in addition to the Onsager reciprocity, and calculate Peltier coefficients for a specific structure. Similar to the thermopower, for finite phase differences of the superconducting order parameter, the proximity effect creates a Peltier effect significantly larger than the one present in purely normal-metal structures. This results from the fact that a nonequilibrium supercurrent carries energy.

Virtanen, Pauli; Heikkilä, Tero T.

2007-03-01

499

Bayesian cost-effectiveness analysis with two measures of effectiveness: the cost-effectiveness acceptability plane  

Microsoft Academic Search

Cost-effectiveness analysis (CEA) compares the costs and outcomes of two or more technologies. However, there is no consensus about which measure of effectiveness should be used in each analysis. Clinical researchers have to select an appropriate outcome for their purpose, and this choice can have dramatic consequences on the conclusions of their analysis. In this paper we present a Bayesian

Miguel A. Negrín; Francisco J. Vázquez-Polo

2006-01-01

500

IMPROVING MEASURES OF BIOLOGIC EFFECT: MEASURING EFFECTS IN HUMAN MALES  

EPA Science Inventory

Animal toxicology studies have demonstrated spermatogenesis and sperm quality effects after exposure to several drinking water disinfection byproducts (DBPs), including DCA, BDCM, chloral hydrate and DBA. Population-based field studies to identify human male reproductive risks o...