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1

The geyser effect in a two-phase thermosyphon  

Microsoft Academic Search

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

C. Casarosa; E. Latrofa; A. Shelginskii

1983-01-01

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

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 30nm. 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 1.0wt% 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 7.45kPa 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

4

Effectively design and simulate thermosyphon reboiler systems: Part 2  

SciTech Connect

Thermosyphon reboilers provide a simple, low-maintenance design for distillation tower reboiler systems. With an understanding of all the factors involved, thermosyphon designs should be more reliable than most other reboiler systems due to an absence of moving parts (pumps) in the process circulation loop. Design of true thermosyphon exchangers requires an intimate knowledge of a distillation tower`s heat balance, temperature levels and pressure balance in the reboiler loop. Temperature levels vary strongly with composition gradients depending on the system`s relative volatilities. Case studies of two industrial units demonstrate implications on exchanger design of the correct and incorrect simulation configuration. The two cases compare a low relative-volatility ({alpha}) system (ethylene-ethane splitter) and a high {alpha} system (FCCU deethanizer). Part 1 covered basic thermosyphon design, advantages and disadvantages. Also, simulation requirements, {alpha} impacts and one-heat-source configurations were discussed. Part 2 continues with configurations of two heat sources at the same and difference temperatures. In addition, comparisons are made between the different designs to show an optimum for each case.

Martin, G.R. [Process Consulting Services, Grapevine, TX (United States); Sloley, A.W. [Process Consulting Services Inc., Houston, TX (United States)

1995-07-01

5

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

NASA Astrophysics Data System (ADS)

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 of the design. Heat pipes are used as highly efficient heat pipe-lines that, being parts of construction elements, permit to equalize the its temperature . As a result of the experiments, it was possible to prove the possibility of using heat pipes as the means for thermostabilization process of the space vehicle. The extension of the areas of application of heat pipes and thermosyphons has resulted in operating in conditions of vibration effects. It is explained to that vibrations are inherent in some units by its nature. Such installations are the space structures, space station, rockets, air and rocket engines, vessels, other transportation facilities. It is considered, that the vibrations improve the heat and mass transfer processes. Therefore it is customary to neglect of vibration actions goes in margin of safety of action of thermal systems. Actually, in accordance with experiences, the vibrations not only improve the heat change, but also degrade it. Therefore knowledge of the impact of vibrations, intrinsic to the installation, on operational modes of used heat pipes and thermosyphons is necessary for preventing breakdown first of all. One of the way of intensification of heat and mass transfer of processes with phase transitions of working fluid is connected with synthetically created vibration actions. In this case also it is necessary to know frequency bands and amplitudes, which one improve or degrade heat and mass transfer. The research of influencing of vibrations on thermal modes with phase changes of working fluids with reference to heat pipes and thermosyphons goes by two paths. One way of research of operational modes is model of heat pipes or thermosyphons in a different variation of frequencies and amplitudes, designs, heat power, working fluid, types of capillary porous structure and so on. Another one is analysis of influencing of vibrations on processes of vaporization, boiling, condensation, flow of two-phase flows in a general formulation regardless to the particular type of a heat pipes. In the report the outcomes of researches of thermal modes of a water thermosyphons in conditions of vibration effects of different frequencies and amplitudes are presented. The boundary frequency bands and amplitude are determined, at which one heat and mass transfer in thermosyphons is improved and is degraded. For an investigated heat pipes of boundary values of frequencies are equal 60 Hz, and amplitudes are equal approximately 3 or 5 mm. The data of other authors are affirmed for another type heat pipes (they received for boundary frequencies 60 and 120-140 Hz). The outcomes of research of influencing of orientation of a heat pipes and thermosyphons on operating of vibrations are submitted. The idealised substantiation's vibration actions on heat and mass transfer of all three zones of thermal tubes - zone of vaporization, condensation and transport are given.

Prisniakov, K.

2002-01-01

6

Type of condensers and their cooling effect in the loop thermosyphon  

NASA Astrophysics Data System (ADS)

This work investigates the cooling effect of three condensers in the loop thermosyphon in horizontal position. The cooling liquid flows in 1-tube condenser circuit. The work compares cooling effect of different types of condensers (flat condenser and ribbed tube condenser) at different thermal load. Cooling effect of condenser is connected with thermal changes in the evaporator. We have found out that the higher the thermal resistance is, the lower the condenser output is. Measurements and calculated values have proved different outputs of condensers.

Hrabovský, Peter; Nemec, Patrik; Malcho, Milan

2014-08-01

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

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

9

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

10

The Effect of Wind Speed at the Top of the Tower on the Performance and Energy Generated from _THERMOSYPHON Solar Turbine  

NASA Astrophysics Data System (ADS)

Energy generated from wind turbine depends to a great extent on the wind speed at its inlet. The use of thermosyphon solar tower is an attempt to increase the air velocity at inlet of the wind turbine and of course to increase its power. The wind speed in a certain location changes always with time and with the height above ground surface. In this work, the effect of wind speed at the top of the tower on the performance as well as on the energy generated from thermosyphon solar turbine was studied theoretically. One location in Egypt was chosen for this study. The calculations were achieved mainly with the solar turbine located at tower bottom. For the purpose of comparison, the energy generated from the solar turbine was compared with that generated from free wind turbine at tower height with the absence of solar tower. It was found that, the wind speed at the top of the tower results in a pressure drop which affects the performance of the thermosyphon solar turbine. This pressure drop increases with the rise in wind speed and will be zero only when the wind speed at the top of the tower reaches zero. It was found also that, there is an increase in friction losses through the tower and a decrease in both temperature difference between inlet and outlet of the tower and in heat losses from tower walls with the rise in wind speed in location. The inlet air velocity to the solar turbine and consequently its specific power were found to be increased with the increase in wind speed at the top of the tower. Therefore, the effect of wind speed at the top of the tower must be taken into account during thermosyphon solar tower calculations. By comparing the performance of solar turbine and the free wind turbine located at tower height with the absence of thermosyphon solar tower, it was found that the mean inlet air velocity to the solar turbine located at tower bottom and consequently its specific power are higher than these values for free wind turbine. The mean inlet air velocity to the solar turbine is found to be 117% of its value for a free wind turbine. The yearly specific energy generated from solar turbine is expected to be 157% of its value for free wind turbine.

El-Haroun, A. A.

2002-01-01

11

Studies on condensation heat transfer in two-phase closed thermosyphons  

NASA Astrophysics Data System (ADS)

The effects of shear stress acting on liquid vapor interface at the condenser of two phase closed thermosyphons were studied. An analysis based on Nusselt's theory of filmwise condensation and heat transfer experiments was conducted. The analysis shows that interfacial shear stress caused by rising vapor makes condensate film thicker and condensation heat transfer coefficient and heat transfer rate decreased. Heat transfer rates increase and became large than analytical results. Flow situations inside the thermosyphon are observed using a glass thermosyphon.

Takuma, M.; Maezawa, S.; Tsuchida, A.

1983-03-01

12

Operating characteristics of two-phase nitrogen thermosyphons  

NASA Astrophysics Data System (ADS)

Heat transfer characteristics of a two-phase nitrogen thermosyphon are experimentally investigated. The thermosyphon made of stainless steel has a length of 0.368 m and an inner diameter of 0.009 m. The thermal resistance of the thermosyphon is obtained as a function of heat transfer rate at various filling ratios in the vapor pressure range from 0.5 x 10 exp 5 to 2.0 x 10 exp 5 Pa. The effective thermal conductivity determined from the experimental results is found to be about 24 times as large as that of copper. The maximum heat transfer rate, which is 94 W, is almost the same as that of the freon thermosyphon in the moderate temperature range.

Ichikawa, Naoki; Shiraishi, Masao; Murakami, Masahide

13

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

14

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

15

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

16

Thermosyphon Flooding Limits in Reduced Gravity Environments  

NASA Technical Reports Server (NTRS)

Fission Power Systems have long been recognized as potential multi-kilowatt power solutions for lunar, Martian, and extended planetary surface missions. Current heat rejection technology associated with fission surface power systems has focused on titanium water thermosyphons embedded in carbon composite radiator panels. The thermosyphons, or wickless heat pipes, are used as a redundant and efficient way to spread the waste heat from the power conversion unit(s) over the radiator surface area where it can be rejected to space. It is well known that thermosyphon performance is reliant on gravitational forces to keep the evaporator wetted with the working fluid. One of the performance limits that can be encountered, if not understood, is the phenomenon of condenser flooding, otherwise known as evaporator dry out. This occurs when the gravity forces acting on the condensed fluid cannot overcome the shear forces created by the vapor escaping the evaporator throat. When this occurs, the heat transfer process is stalled and may not re-stabilize to effective levels without corrective control actions. The flooding limit in earth's gravity environment is well understood as experimentation is readily accessible, but when the environment and gravity change relative to other planetary bodies, experimentation becomes difficult. An innovative experiment was designed and flown on a parabolic flight campaign to achieve the Reduced Gravity Environments (RGE) needed to obtain empirical data for analysis. The test data is compared to current correlation models for validation and accuracy.

Gibson, Marc A.; Jaworske, Donald A.; Sanzi, James L.; Ljubanovic, Damir

2012-01-01

17

Reflux condensation heat transfer inside a closed thermosyphon  

NASA Astrophysics Data System (ADS)

The paper presents a survey on condensation heat transfer inside a two-phase thermosyphon with a detailed description of fluid flow as well as a review of published experimental and theoretical investigations. An evaluation is given of a total of 2889 data points derived from 18 research works covering a wide range of thermal and geometrical parameters: 10 different working fluids, saturation temperature (14-340 C), pressure (0.04-39.5 bar), inside tube diameter (14-66 mm), length of cooling zone (102-2450 mm), and inclination angle (0-85 deg). Correlations for condensation heat transfer inside a two-phase thermosyphon are proposed. The remaining deviations are found to be due to the effects of shear stress at the liquid-vapor interface, the effects of noncondensable gases, and the effects of a partial flooding of the cooling zone in the case of superfilling the thermosyphon.

Gross, U.

1992-02-01

18

Thermosyphon-cooled bellow liquid heat sink  

Microsoft Academic Search

A self contained thermosyphon-cooled flexible bellow liquid heat sink was developed for cooling electronic circuit boards. The prototype system combines the benefits of both flexible bellows and thermosyphon technology. A finned flat-plate thermosyphon was designed and tested for natural convection application under various heat source temperatures. Extensive measurements were made on the combined heat sink system comprising the flat-plate thermosyphon

C. Y. R. Ng; Y. W. Wong; C. Y. Liu; K. F. Choo

1998-01-01

19

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

20

A test bed for thermosyphon solar air collectors  

Microsoft Academic Search

A description of solar 'thermosyphon' air heating systems (those with no active circulating devices) is presented. Utilizing similar water system analyses, a model is developed to predict mass flow rates and mean system temperatures. Studies indicate the effects of various system geometries, glazing configurations, and frictional head losses. A test bed design is presented to provide experimental verification of these

W. Lowry; D. Pearson

1979-01-01

21

Condensation heat transfer in two-phase co-current closed thermosyphon  

NASA Astrophysics Data System (ADS)

This paper presents a theoretical analysis and experimental results of condensation heat transfer in the vertical two-phase cocurrent closed thermosyphon. The effects of the relative importance of two kinds of shear stresses are considered in the theoretical prediction.

Wei, Hong; Ma, Tongze

1991-05-01

22

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

23

Thermosyphon circulation in solar collectors  

NASA Astrophysics Data System (ADS)

Theoretical predictions of flow rate in thermosyphon solar collectors are compared with experimental measurements obtained using a laser Doppler anemometer. Modifications to the usual method of analysis are proposed to improve the accuracy of the predictions, and the results are compared with flow rate predictions and measurements in other investigations.

Morrison, G. L.; Ranatunga, D. B. J.

1980-01-01

24

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. PMID:21846362

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

The Effect of Wind Speed at the Top of the Tower on the Performance and Energy Generated from _THERMOSYPHON Solar Turbine  

Microsoft Academic Search

Energy generated from wind turbine depends to a great extent on the wind speed at its inlet. The use of thermosyphon solar tower is an attempt to increase the air velocity at inlet of the wind turbine and of course to increase its power. The wind speed in a certain location changes always with time and with the height above

A. A. El-Haroun

2002-01-01

27

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

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

Complete transient two-dimensional analysis of two-phase closed thermosyphons including the falling condensate film  

NASA Astrophysics Data System (ADS)

A transient two-dimensional thermosyphon model is presented that accounts for conjugate heat transfer through the wall and the falling condensate film. The complete transient two-dimensional conservation equations are solved for the vapor flow and pipe wall, and the liquid film is modeled using a quasi-steady Nusselt-type solution. The model is verified by comparison with existing experimental data for a low-temperature thermosyphon with good agreement. A typical high-temperature thermosyphon was then simulated to examine the effects of vapor compressibility and conjugate heat transfer.

Harley, C.; Faghri, A.

1994-05-01

30

Natural convection in C-shaped thermosyphon  

SciTech Connect

The present work is concerned with the numerical analysis of natural convection from a C-shaped thermosyphon. The system can be considered as a model for a Trombe wall in passive solar collectors as well as electronic cooling arrangements and it has geophysical applications. The effect of Rayleigh number (1 {times} 10{sup 3} to 1 {times} 10{sup 7}) and aspect ratios of 2.0, 4.0, 6.0, and 10.0 is investigated for a fixed Prandtl number (0.7). Local and average Nusselt numbers for heated and cold walls are discussed. Mass advected by the buoyancy force is calculated and presented for the range of investigated parameters. The flow pattern and isotherm distribution in the gap between the wall and cover plate are presented and discussed.

Mohamad, A.A.; Sezai, I. [Eastern Mediterranean Univ., North Cyprus (Turkey). Mechanical Engineering Dept.

1997-08-29

31

Enhancement of CHF in open thermosyphon with bottom heated chamber  

SciTech Connect

An experiment has been carried out to elucidate critical heat flux (CHF) of an open thermosyphon with a bottom heated chamber in which heat is absorbed by evaporation. The CHF is enhanced by a concentric-tube where counter-current flow of liquid and vapor in the throat of the chamber can be controlled well in the inner tube and annulus passages. A concentric tube is mounted to connect the heated part to upper plenum. The CHF data are measured for the saturated liquid of R113 at a different pressure and different configuration of concentric tubes. The dimension of inner tube diameters d{sub o} = 4 to 10 mm depending on outer tube diameter D{sub i} = 9 and 12 mm. The corresponding annular space varies from 2 to 7 mm. The CHF is first measured for the thermosyphon without the inner tube in order to compare the CHF in conventional one and then for several combinations of inner and outer tubes. Figure A2 shows the CHF data of D{sub i} = 12 mm plotted against d{sub o}. from Fig. A2, the CHF values without the inner tubes are in good agreement with the Imura correlation and Monde's analytical prediction without regard of its different configuration from the conventional one. Therefore, the CHF characteristic in this configuration can be considered to be the same as that in the ordinary thermosyphon. The CHF for the thermosyphon with inner tube increases up to a certain diameter of the inner tube and then decreases as the inner tube diameter approaches the outer tube diameter. The CHF becomes the maximum at the optimum inner tube diameter. The outer tube diameter has significant effects on the optimum diameter but the length of the outer tube seems to have weak effect on the CHF. In addition, the CHF characteristics can be categorized into two regions by the optimum diameter.

Monde, M.; Mitsutake, Y.; Itoyama, T.

1999-07-01

32

Thermosyphon Flooding in Reduced Gravity Environments  

NASA Technical Reports Server (NTRS)

An innovative experiment to study the thermosyphon flooding limits was designed and flown on aparabolic flight campaign to achieve the Reduced Gravity Environments (RGE) needed to obtainempirical data for analysis. Current correlation models of Faghri and Tien and Chung do not agreewith the data. A new model is presented that predicts the flooding limits for thermosyphons inearths gravity and lunar gravity with a 95 confidence level of +- 5W.

Gibson, Marc Andrew

2013-01-01

33

Heat transfer characteristics in two-phase closed conventional and concentric annular thermosyphons  

NASA Astrophysics Data System (ADS)

The heat transfer in the condenser sections of conventional and annular two-phase closed thermosyphon tubes has been studied experimentally and analytically. In addition, the results of a series of experiments on the flooding phenomena of the same thermosyphons are reported. Freon 113 and acetone were used as working fluids. An improved correlation was developed to predict the performance limits of conventional thermosyphons using the present and previously existing experimental data for flooding with different working fluids. The prediction of the theoretical Nusselt number for the situations associated with measured heat transfer coefficients in the condenser section indicated that the effect of interfacial shear on the film flow is small. The increase of the experimental reflux condensation heat transfer coefficients over theoretical predictions is attributed to waves at the vapor-liquid interface.

Faghri, A.; Chen, M.-M.; Morgan, M.

1989-08-01

34

Investigation of heat transfer characteristics of a two-phase closed thermosyphon  

NASA Astrophysics Data System (ADS)

An experimental study of the heat transfer mechanism of a two-phase closed thermosyphon is conducted in order to develop a mathematical model for predicting the heat transfer characteristics of the thermosyphon. The effects of the working fluid (water, ethanol, and Freon 113), the amount of the working fluid, the operating temperature, and the heat flux are determined, and the heat transfer coefficients at the condenser and evaporator are estimated. The mathematical model is found to accurately predict the heat transfer characteristics and the agreement with experimental results is good. It is shown that the overall thermal resistance of the thermosyphon is very sensitive to the operating pressure, the heat flux, and the quantity of the working fluid.

Shiraishi, M.; Kikuchi, K.; Yamanishi, T.

35

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

36

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

37

Thermosyphon reboiler piping designed by computer  

SciTech Connect

Designing or checking natural circulation for a horizontal thermosyphon reboiler circuit and determining the heat pressures required to assure circulation, although not difficult, is time consuming. In this paper, a program written for a Texas Instrument programmable TI 59 calculator is presented to help reduce the time required for this type of calculation. 5 refs.

Abbott, W.F.

1982-03-01

38

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

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

Cryogenic Nitrogen Thermosyphon Developed and Characterized  

NASA Technical Reports Server (NTRS)

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 Flight Center's (MSFC) Advanced Space Transportation Program supported this test to improve the performance of in-space propulsion system concepts. Recent studies (ref. 1) have shown significant mass reductions and other advantages when incorporating active cooling in a ZBO configuration, enabling consideration of high-performing cryogenic propellants for long-duration applications in space. Active cooling was integrated via a thermosyphon, made of copper, 42 in. (1070 mm) long with an inner diameter of 0.436 in. (11 mm). It was charged with nitrogen to 225 psia at 300 K, which provided a fill ratio of 15 percent. The temperatures and heat flows through the thermosyphon were monitored during the startup phase of the ZBO test, and steady-state tests were conducted over a range of increasing and decreasing heat flows. The results also were compared with the initial design calculations and with results for a similar thermosyphon. They show that the thermal resistance of the thermosyphon was one-half of that expected--0.2 K/W at a heat flow of 8.0 W. The design calculations also showed that this resistance can be made relatively constant over a wider range of heat flows by making the ratio of evaporator area to condenser area 3:1. The better-than-expected results will translate into reduced integration loss for the ZBO concept.

Plachta, David W.; Christie, Robert

2004-01-01

41

The Design of an Ultra-Low Background Thermosyphon for the Majorana Demonstrator  

SciTech Connect

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 R&D results of a cryogenic system capable of meeting the requirements of low background and the cooling capacity required to successfully operate such a detector system. The MJD germanium detector modules will operate at liquid nitrogen temperature to provide adequate cooling for a full range of HPGe impurity concentrations. This paper shows the experimental results obtained using a two-phase horizontal thermosyphon using liquid nitrogen as the MJD’s cooling system. The cold test shows 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. The thermosyphon will be bolted to a cold plate from which detector strings will hang. The thermal conductivity of a mockup of the MJD bolted thermal joint is experimentally determined to be below 0.1 K/W.

Aguayo Navarrete, Estanislao; Busch, Matthew; Daniels, Randy; Fast, James E.; Green, Matthew P.; Reid, Douglas J.

2013-05-01

42

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

43

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

44

Gas-concentration measurements and analysis for gas-loaded thermosyphons  

Microsoft Academic Search

Using a miniature wet-bulb\\/dry-bulb probe, detailed measurements of noncondensable-gas-concentration profiles were made in a gas-loaded two-phase reflux thermosyphon to investigate the effects of orientation and gas\\/vapor molecular weight combinations. Natural convection and radial diffusion were found to have a large influence on the noncondensable-gas distribution, even when the gas and vapor molecular weights are equal. An axisymmetric two-dimensional diffusion model

P. F. Peterson; C. L. Tien

1988-01-01

45

Gas-concentration measurements and analysis for gas-loaded thermosyphons  

Microsoft Academic Search

Using a miniature wet-bulb\\/dry-bulb probe, detailed measurements of noncondensable-gas concentration profiles were made in a gas-loaded two-phase relfux thermosyphon to investigate the effects of orientation and gas\\/vapor molecular weight combination. Natural convection andd radial diffusion were found to have a large influence on the noncondensable-gas distribution, even when the gas and vapor molecular weights are equal. An axisymmeteric two-dimensional diffusion

P. F. Peterson; C. L. Tien

1988-01-01

46

Experimental investigation on thermal performance of thermosyphon flat-plate solar water heater with a mantle heat exchanger  

Microsoft Academic Search

The thermal performance of thermosyphon flat-plate solar water heater with a mantle heat exchanger was investigated to show its applicability in China. The effect on the performance of the collector of using a heat exchanger between the collector and the tank was analyzed. A “heat exchanger penalty factor” for the system was determined and energy balance equation in the system

Jinbao Huang; Shaoxuan Pu; Wenfeng Gao; Yi Que

2010-01-01

47

Performance of a two-phase closed thermosyphon solar collector with a shell and tube heat exchanger  

Microsoft Academic Search

In the present study, a two-phase closed thermosyphon flat-plate solar collector with a shell and tube heat exchanger was investigated experimentally under the field conditions of Cairo, Egypt. The collector was designed, constructed, and tested at transient conditions to study its performance for different cooling water mass flow rates at different inlet cooling water temperatures. Also the effect of the

S. A Nada; H. H El-Ghetany; H. M. S Hussein

2004-01-01

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

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

50

Gas-concentration measurements and analysis for gas-loaded thermosyphons  

NASA Astrophysics Data System (ADS)

Using a miniature wet-bulb/dry-bulb probe, detailed measurements of noncondensable-gas-concentration profiles were made in a gas-loaded two-phase reflux thermosyphon to investigate the effects of orientation and gas/vapor molecular weight combinations. Natural convection and radial diffusion were found to have a large influence on the noncondensable-gas distribution, even when the gas and vapor molecular weights are equal. An axisymmetric two-dimensional diffusion model is presented to allow evaluation of the relative effects of natural convection versus diffusion. Gas recirculation, axial stratification, regions of unstable flow, and their effects on performance are discussed.

Peterson, P. F.; Tien, C. L.

1988-08-01

51

Gas-concentration measurements and analysis for gas-loaded thermosyphons  

SciTech Connect

Using a miniature wet-bulb/dry-bulb probe, detailed measurements of noncondensable-gas concentration profiles were made in a gas-loaded two-phase relfux thermosyphon to investigate the effects of orientation and gas/vapor molecular weight combination. Natural convection andd radial diffusion were found to have a large influence on the noncondensable-gas distribution, even when the gas and vapor molecular weights are equal. An axisymmeteric two-dimensional diffusion model is presented to allow evaluation of the relative effects of natural convection versus diffusion. Gas recirculation, axial stratification, regions of unstable flow, and their effects on performance are discussed.

Peterson, P.F.; Tien, C.L. (Univ. of California, Berkeley (USA))

1988-08-01

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

Development of a naturally aspired thermosyphon for power amplifier cooling  

NASA Astrophysics Data System (ADS)

This paper details the early development steps of a two-phase thermosyphon thermal management solution for power amplifiers (PA) in the telecommunication industry. These components, attached to a vertical PCB within an enclosure between the RF filter and a natural or forced convection heat sink, dissipate a large amount of heat with a high heat flux density. Currently cooled by direct contact to a shared heat sink, they tend to spread heat towards other components of their board, affecting their reliability. A thermosyphon thus appear as an ideal thermal management solution to transport the heat from the power amplifiers in order to dissipate it to a remote and dedicated natural convection heat sink. In the present study, the performance and the heat spreading of a forced convection unit is measured. A thermosyphon solution is then designed with a flat vertical evaporator and a radial natural convection heat sink and condenser. The performance of the thermosyphon thermal management solution is measured and compared to the initial solution. The limits and improvement needs of the thermosyphon solution are then discussed.

Siedel, S.; Robinson, A. J.; Kempers, R.; Kerslake, S.

2014-07-01

54

Convective heat transfer in a closed two-phase thermosyphon  

NASA Astrophysics Data System (ADS)

A numerical analysis of heat transfer processes and hydrodynamics in a two-phase closed thermosyphon in a fairly wide range of variation of governing parameters has been investigated. A mathematical model is formulated based on the laws of mass conservation, momentum and energy in dimensionless variables "stream function - vorticity vector velocity - temperature". The analysis of the modes of forced and mixed convection for different values of Reynolds number and heat flows in the evaporation zone, the possibility of using two-phase thermosyphon for cooling gas turbine blades, when the heat is coming from the turbine blades to the thermosyphon is recycled a secondary refrigerant has been studied with different values of the centrifugal velocity. Nusselet Number, streamlines, velocity, temperature fields and temperature profile has been calculated during the investigation.

Al-Ani, M. A.

2014-08-01

55

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

56

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

57

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. PMID:21711856

2011-01-01

58

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

59

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

60

The onset of motion in a toroidal thermosyphon  

Microsoft Academic Search

The instability associated with the onset of motion in a toroidal natural-circulation loop has been studied theoretically. A one-dimensional model is used to investigate the problem of global flow initiation from a rest state. It is shown that a thermosyphonic flow is established when the modified Rayleigh number exceeds a critical value, R

Y. Zvirin

1986-01-01

61

Theoretical Design of a Thermosyphon for Efficient Process Heat Removal from Next Generation Nuclear Plant (NGNP) for Production of Hydrogen  

SciTech Connect

The work reported here is the preliminary analysis of two-phase Thermosyphon heat transfer performance with various alkali metals. Thermosyphon is a device for transporting heat from one point to another with quite extraordinary properties. Heat transport occurs via evaporation and condensation, and the heat transport fluid is re-circulated by gravitational force. 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. For process heat, intermediate heat exchangers (IHX) are required 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 1000oC) and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. The purpose for 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 (900oC, based on the current capabilities of NGNP), and the temperatures in the hydrogen production plant. Spiral Heat Exchangers (SHE’s) 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.

Piyush Sabharwall; Fred Gunnerson; Akira Tokuhiro; Vivek Utgiker; Kevan Weaver; Steven Sherman

2007-10-01

62

The influence of the inclination angle on the performance of a closed two-phase thermosyphon  

NASA Astrophysics Data System (ADS)

The effect of the inclination angle on the transport behavior of a closed two-phase thermosyphon is studied in a steel pipe containing the refrigerant R 115 as the working fluid. The pipe is electrically heated at the lower part ('heating zone') and cooled by water at a constant temperature along the upper part ('cooling zone'), while between these two zones there is a well insulated transport zone. The amount of fluid in the tube is chosen so that the critical specific volume is obtained. Results show that the maximum heat flow rate in the tube depends on the inclination, with the largest value of the heat flow rate being 2850 W at an inclination angle of 40 degrees. The effective thermal conductivity of the thermosyphon depends strongly on the inclination angle and the heat flow rate, so that the steeper the tube and the larger the heat flow rate, the higher is the effective conductivity. In addition, the condensation in the cooling zone exhibits the largest transport resistance, while the heat transfer with boiling in the heating zone shows large local differences and depends strongly on the inclination of the tube.

Hahne, E.; Gross, U.

63

Investigation of thermal performance of an air-to-air thermosyphon heat exchanger using ?-NTU method  

Microsoft Academic Search

Experimental and theoretical research has been carried out to investigate the thermal performance of an air-to-air thermosyphon heat exchanger. Many factors affect the thermal performance of thermosyphon heat exchangers including velocity and temperature of input air, type and filling ratio of the working fluid, and pipe material. The air-to-air thermosyphon heat exchanger has been designed, constructed and tested in a

S. H. Noie

2006-01-01

64

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

65

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

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 there for which is such that in the heating mode of operation of the heat pump they operate in a thermosyphon fashion. The coil has a feed portion and an exit portion leading to a separator drum from which liquid refrigerant is returned through downcomer line 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. 9 figs.

Draper, R.

1984-05-22

67

Dynamic heat transfer mechanism of two-phase closed thermosyphon  

NASA Astrophysics Data System (ADS)

The heat transfer mechanism of a two phase closed thermosyphon was dynamically analysed in the periodically motive behavior of working fluid with boiling. It is an important problem in order to obtain high heat transfer performance, how the liquid film of the working fluid can be held for longer time on the wider area of the evaporator heating wall, and how the active evaporation can be kept there.

Negishi, K.; Kaneko, K. I.; Kusumoto, F.

68

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

69

Mathematical modeling of heat transfer in closed two-phase thermosyphon  

NASA Astrophysics Data System (ADS)

There was conducted a numerical analysis of heat-transfer in close two-phase thermosyphon of cylindrical form in the condition of admission of warmth on a lower lid and taking from the high bound of lid. For description of the researched process was offered the simplified mathematical model, which describes only processes of heat conductivity in system "a corps of thermosyphon - a steam channel - a condensate membrane". This formulated task with boundary conditions was decided by the method of eventual differences using an implicit difference scheme. As a result have got fields of temperatures in thermosyphon for typical thermal loads and methods of working. Was conducted a comparative analysis of fields of temperature in a thermosyphon at different thermal streams on a lower lid. Was studied an Influence of coefficient of heat emission and basic geometrical descriptions on forming of the field of temperature in the crossrunner of thermosyphon.

Nurpeiis, Atlant

2014-08-01

70

The influence of wall roughness on the maximum performance of closed two-phase thermosyphons  

NASA Astrophysics Data System (ADS)

The performance of six thermosyphons using water as the working fluid has been experimentally investigated. Four thermosyphons have chemically roughened inner surfaces, and two have mechanically roughened inner surfaces. The influence of liquid fill charge, tilt angle, evaporator and condenser lengths on the maximum performance has been studied. Despite great differences in the surface roughnesses the maximum heat transport capabilities do not differ much. The maximum performance and the axial temperature difference of the thermosyphons have been compared with respective data obtained from thermosyphons with smooth inner surface and screen-wick heat pipes. Start-up experiments have also been carried out to determine the influence of the magnitude of the initial heat input on the maximum thermosyphon performance

Nguyen-Chi, H.; Groll, M.

1980-07-01

71

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

72

Heat transfer characteristics of the two-phase closed thermosyphon (wickless heat pipe)  

NASA Astrophysics Data System (ADS)

Steady-state heat transfer characteristics and heat transfer limits (dry-out) for a vertical stainless steel tubular two-phase closed thermosyphon with Freon-113 working fluid are reported as a function of certain geometric parameters and liquid fill quantity. Condenser section heat transfer characteristics agreed reasonably well with existing laminar film condensation correlations and were found to be independent of the evaporator section, except for larger liquid fills. Evaporator characteristics were quite complex and appeared, under some conditions, to be coupled to condenser characteristics through effects of system pressure and/or surface wave as present on the descending condensate film. A laminar thin film evaporation model was found to give reasonable agreement with local evaporator temperature measurements in those regions of the evaporator where a continuous film apparently persisted. The measured heat transfer characteristics are interpreted relative to an earlier investigation by the authors in which flow characteristics in a similar device were visually and photographically observed.

Andros, F. E.; Florschuetz, L. W.

73

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

74

Diffusion Induced Chaos in a Closed Loop Thermosyphon  

E-print Network

DIFFUSION INDUCED CHAOS IN A CLOSED LOOP THERMOSYPHON #3; AN #19; IBAL RODR #19; IGUEZ-BERNAL y AND ERIK S. VAN VLECK z SIAM J. APPL. MATH. c © 1998 Society for Industrial and Applied Mathematics Vol. 58, No. 4, pp. 1072{1093, August 1998 003...-0438, Spain, and EEC grant SC1-CT91-0732. z Department of Mathematical and Computer Sciences, Colorado School of Mines, Golden, CO 80401 (erikvv@poincare.mines.edu). The research of this author was partially supported by NSF grant DMS-9505049. 1072 D ow nl oa...

Rodriguez-Bernal, Anibal; Van Vleck, Erik

1998-08-05

75

Study of the vapor-gas front of a variable conductance thermosyphon using advanced optical techniques  

E-print Network

The influence of noncondensable gases on the operation of a thermosyphon was studied experimentally. The operating characteristics were studied while varying the power input, gas quantity, and gas type. The results were compared with existing...

Doerksen, Glenn Robert

1993-01-01

76

Experimental study on transient behavior of semi-open two-phase thermosyphon.  

PubMed

An experimental system was set up to measure the temperature, pressure, heat transfer rate and mass flow rate in a semi-open two-phase thermosyphon. The behaviors of a semi-open two-phase thermosyphon during startup, shutdown and lack of water were studied to get complete understanding of its thermal characteristics. The variation of wall temperature, heat-exchange condition and pressure fluctuations of semi-open two-phase thermosyphons showed that the startup of SOTPT needs about 60-70 min; the startup speed of SOTPT is determined by the startup speed of the condensation section; the average pressure in the heat pipe is equal to the environmental pressure usually; the shutdown of SOTPT needs about 30-50 min; a semi-open two-phase thermosyphon has good response to lack of water accident. PMID:15547965

Zhu, Hua; Wang, Jian-Xin; Zhang, Qiao-Hui; Tu, Chuan-Jing

2004-12-01

77

Experimental analysis of natural convection within a thermosyphon  

SciTech Connect

The heat transfer characteristics of a thermosyphon designed to passively cool cylindrical heat sources are experimentally studied. The analysis is based on recognizing the physics of the flow within different regions of the thermosyphon to develop empirical heat transfer correlations. The basic system consists of three concentric cylinders, with an outer channel between the outer two cylinders, and an inner channel between the inner two cylinders. Tests were conducted. with two different process material container diameters, representing the inner cylinder, and several different power levels. The experimentally determined local and average Nu numbers for the inner channel are in good agreement with previous work for natural convection between vertical parallel plates, one uniformly heated and the other thermally insulated. The implication is that the heat transfer off of each surface is independent of the adjacent surface for sufficiently high Ra numbers. The heat transfer is independent because of limited interaction between the boundary layers at sufficiently high Ra numbers. As a result of the limited interaction, the maximum temperature within the system remained constant, or decreased slightly when the radii of the inner cylinders increased for the same amount of heat removal.

Clarksean, R.

1993-09-01

78

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

79

A blowup phenomenon of the working fluid in a two-phase closed thermosyphon  

NASA Astrophysics Data System (ADS)

A periodic blowup phenomenon of the working fluid is often observed in a two phase closed thermosyphon at rather low heat load operation. The phenomenon is a blowing movement of a large amount of the liquid from the evaporator to the condenser by an explosive expansion and development of a boiling bubble in the liquid pool. The fluctuating temperature distributions on the container wall of the thermosyphon are reasonably explained when compared with the visual observation of the movement of the working fluid.

Negishi, K.

1984-03-01

80

Heat transfer characteristics of the two-phase closed thermosyphon (wickless heat pipe) including direct flow observation  

NASA Astrophysics Data System (ADS)

The two phase closed thermosyphon is a heat transfer device capable of transferring large quantities of heat from a source to a sink by taking advantage of the high heat transfer rates associated with the evaporation and condensation of a working fluid within the device. For small and intermediate fill quantities, four basic flow regimes were observed in the evaporator section of the thermosyphon during steady state operation with Freon 113 and ethanol: (1) a smooth continuous film with surface evaporation; (2) the breakdown of the smooth continuous film into a series of rivulets; (3) a wavy film with unstable rivulets; and (4) a wavy film with bubble nucleation occurring in the unstable rivulets. A fifth condition which was observed with all fluids was a dry out (heat transfer limit) where some portion of the evaporator ceases to be cooled effectively by the falling film and rivulets, resulting in a wall temperature excursion or critical condition. Three types of dry out were observed. In addition to the visual device used, a stainless steel tubular opaque device was fabricated and is heat transfer characteristics evaluated using Freon 113 as a working fluid.

Andros, F. E.

1980-12-01

81

*Corresponding Author: E-mail: jent@uwm.edu; Tel: 414-229-2307; Fax: 414-229-6958 Investigation of Thermosyphon Cooling for  

E-print Network

case, the drill tip temperature was only 16% higher. Keywords: Dry Drilling, Thermosyphon Cooling, Tool of Thermosyphon Cooling for Drilling Operation: An Experimental Study TIEN-CHIEN JEN* , FERN TUCHOWSKI AND YAU Wear Reduction INTRODUCTION This paper investigates the feasibility of using a thermosyphon to cool

Jen, Tien-Chien

82

Observations on an evaporative, elbow thermosyphon  

SciTech Connect

The performance of the evaporative elbow system was found to be superior to that of the nonevaporative system, but comparable to the performance of the linear system. The parametric role of the evaporator wall temperature, the condenser wall temperature, and the vapor saturation temperature was demonstrated, each revealing a similar monotonic effect. With the evaporator upright, the data were found to be similar to, but displaced from, the upright condenser data. The upright evaporator gave the better performance, but not overwhelmingly so. The limit of performance with the condenser upright was found to be dictated by evaporator dryout. In the upright evaporator configuration, the limit may be attributed to flooding in the poorly draining condenser; this limit was indistinguishable from geyser behavior at low vapor pressures. 16 refs., 3 figs.

Lock, G.S.H.; Fu, J. (Univ. of Alberta, Edmonton (Canada))

1993-05-01

83

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

NASA Astrophysics Data System (ADS)

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 for three tube-in-shell heat exchangers (four, seven, and nine tube). Thermosyphon flow is on the shell side. Correlations are obtained with uniform heat flux on the tube walls and with a mixture of glycol and water circulating inside the tubes. Ranges of Reynolds, Prandtl, and Grashof numbers are 50 to 1800, 2.5 and 6.0, and 4×105 to 1×108, respectively. Nusselt number correlations are presented in a form that combines the contributions of forced and natural convection, Nu4Mixed=Nu4Forced+Nu4Natural. The Nusselt number is influenced by natural convection when the term Raq0.25/(Re0.5Pr0.33) is greater than unity. Pressure drop through these three designs is not significantly affected by mixed convection because most pressure drop losses are at the heat exchanger inlet and outlet. A comparison and discussion of the performance of several other heat exchanger designs (tube-in-shell and coil-in- shell designs) are presented. Generally, the coil-in- shell heat exchangers perform better than the tube-in- shell heat exchangers. Data from all heat exchanger designs is used to develop a new one-dimensional model for thermosyphon heat exchangers in solar water heating systems. The model requires two empirically determined relationships, pressure drop as a function of water mass flow rate and the overall heat transfer coefficient-area product (UA) as a function of Reynolds, Prandtl, and Grashof number. A testing protocol is presented that describes the procedure to obtain the data for the correlations. Two new TRNSYS component models are presented, for the thermosyphon heat exchanger and thermosyphon loop. Unlike previous models, which are based on forced flow relationships, the new heat exchanger model accounts for mixed convection heat transfer and accurately predicts pressure drop in the connecting piping around the thermosyphon loop. Comparison between the model and experimental data shows excellent agreement. Daily and annual ratings for a sample thermosyphon system are presented.

Dahl, Scott David

1998-11-01

84

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

85

Thermosyphon Cooler Hybrid System Providing Water Resiliency in a typical Chemical Plant  

E-print Network

-05-20 Proceedings of the Thrity-Sixth Industrial Energy Technology Conference New Orleans, LA. May 20-23, 2014 Process Heat Rejection Device Q 85°F 95°F Process Loop Process Pump QWet 85°F 90°F Cooling Tower Thermosyphon Cooler TSC Pump QDry 95°F 90°F 95°F 90°F... Evaporative HR LoopDry HR Loop “Wet” when it’s Hot, “Dry” when it’s Not Thermosyphon Cooler Hybrid System (TCHS) 4 ESL-IE-14-05-20 Proceedings of the Thrity-Sixth Industrial Energy Technology Conference New Orleans, LA. May 20-23, 2014 Process Water In Out...

Carter, T. P.

2014-01-01

86

Heat transfer performance of an inclined two-phase closed thermosyphon  

NASA Astrophysics Data System (ADS)

An experimental study on the heat transfer performance of an inclined two-phase closed thermosyphon is described. Water and ethanol have been used as the working fluids. The amount of working fluid and the inclination angle have been used as the experimental parameters. A visualization of the movement of liquid with boiling, the scattering of liquid drops and the condensation of vapor has made clear the heat transfer mechanism in the thermosyphon. In addition, the overall heat transfer coefficients and the thermal diode characteristics have been obtained.

Negishi, K.; Sawada, T.

1983-08-01

87

Experimental study of flow rates through inclined open thermosyphons  

SciTech Connect

An experimental set-up has been developed for the investigation of flow inside an inclined cylindrical open thermosyphon. A glass cylinder, whose bottom is sealed and whole top is open to a reservoir, is heated from the sides, generating natural convection currents between itself and the reservoir. The set-up simulates the flow inside evacuated tubular solar absorbers. The cylinder walls are heated in two different ways: (1) uniform wall temperatures; and (2) differential wall heating, in which one temperature is applied on the upper surface of the cylinder wall, and another temperature on the lower surface. The second scheme of heating attempts to approximate the manner in which absorbers are usually heated under exposure to solar radiation, with the upper surface normally getting more heat that the lower. Axial velocity measurements are done with a laser Doppler anemometer at the central vertical plane of the orifice. Correlations between the velocity and the independent control parameters (Rayleigh number, aspect ratio and mode of heating) are performed. 5 refs., 11 figs.

Gaa, F.O.; Behnia, M.; Morrison, G.L. [Univ. of New South Wales, Sydney (Australia)] [Univ. of New South Wales, Sydney (Australia)

1996-11-01

88

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

89

Design, construction and testing of a thermosyphon heat exchanger for medium temperature heat recovery in bakeries  

Microsoft Academic Search

Using water as the working fluid, air-to-air heat exchangers using thermosyphon heat pipes were designed, constructed and tested under medium temperature (below 300°C) operating conditions. A heat exchanger test rig has been constructed and developed wherein the heated air is recycled to the counterflow heat exchanger. The lengths of both the evaporator section and the condenser section of the heat

A. R. Lukitobudi; A. Akbarzadeh; P. W. Johnson; P. Hendy

1995-01-01

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

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

93

A flow boiling microchannel thermosyphon for fuel cell thermal management  

NASA Astrophysics Data System (ADS)

To provide a high power density thermal management system for proton exchange membrane (PEM) fuel cell applications, a passively driven thermal management system was assembled to operate in a closed loop two-phase thermosyphon. The system has two major components; a microchannel evaporator plate and a condenser. The microchannel evaporator plate was fabricated with 56 square channels that have a 1 mm x 1 mm cross section and are 115 mm long. Experiments were conducted with a liquid cooled condenser with heat flux as the control variable. Measurements of mass flow rate, temperature field, and pressure drop have been made for the thermosyphon loop. A model is developed to predict the system characteristics such as the temperature and pressure fields, flow rate, flow regime, heat transfer coefficient, and maximum heat flux. When the system is subjected to a heat load that exceeds the maximum heat flux, an unstable flow regime is observed that causes flow reversal and eventual dryout near the evaporator plate wall. This undesirable phenomenon is modeled based on a quasi-steady state assumption, and the model is capable of predicting the heat flux at the onset of instability for quasi-steady two-phase flow. Another focus of this work is the performance of the condenser portion of the loop, which will be air cooled in practice. The aim is to reduce air side thermal resistance and increase the condenser performance, which is accomplished with extended surfaces. A testing facility is assembled to observe the air side heat transfer performance of three aluminum foam samples and three modified carbon foam samples, used as extended surfaces. The aluminum foam samples have a bulk density of 216 kilograms per cubic meter with pore sizes of 0.5, 1, and 2 mm. The modified carbon foam samples have bulk densities of 284, 317, and 400 kilograms per cubic meter and machined flow passages of 3.2 mm. in diameter. Each sample is observed under forced convection with air velocity as the control variable. Thermocouples and pressure taps are distributed axially along the test section and measurements of pressure and temperature are recorded for air velocities ranging from 1-6 meters per second. Using the Darcy-Forcheimer equation, the porosity is determined for each sample. The volumetric heat transfer coefficient is extracted by means of solving the coupled energy equations of both the solid and fluid respectively. Nusselt number is correlated with Reynolds number. The optimal foam configuration is explored based on a Coefficient of Performance, (COP), Compactness Factor (CF) and Power Density (PD). The COP is the ratio of total heat removed to electrical heat consumption of the blower, CF is the total heat removed per unit volume, and PD is the total heat removed per unit mass. These performance parameters are computed for a hypothetical heat exchanger using each foam sample at various fluid velocities. They are also compared against those for the hypothetical heat exchanger fitted with conventional louvered fins. Given a proper weighting function based on the importance of CF, COP, and PD in the condenser design, an optimal configuration for an air cooled condenser can be obtained for various operating conditions.

Garrity, Patrick Thomas

94

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

95

Long-term thermal performance of a two-phase thermosyphon solar water heater  

Microsoft Academic Search

This article investigates experimentally the long-term thermal performance of a two-phase thermosyphon solar water heater and compares the results with the conventional systems. Experimental investigations are conducted to obtain the system thermal efficiencies from the hourly, daily and long-term performance tests. Different heat transfer mechanisms, including natural convection, geyser boiling, nucleate boiling and film-wise condensation, are observed in the two-phase

Bo-Ren Chen; Yu-Wei Chang; Wen-Shing Lee; Sih-Li Chen

2009-01-01

96

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

97

Thermosyphon Cooling System for the Siemens 400kW HTS Synchronous Machine  

NASA Astrophysics Data System (ADS)

A commercial GM cryocooler is employed to cool the rotor of the first Siemens 400 kW HTS machine. Excellent thermal connection between cold head and rotor is achieved using a thermosyphon. At the rotor's inner surface the required cooling power is provided by evaporating fluid, that is recondensed at the coldhead. Our configuration allows an easy mechanical decoupling of the stationary cold head and the rotor, using a magnetic liquid rotary seal. In order to shorten cool-down time, a precool to 70 K is done with a thermosyphon filling of nitrogen, while a motor operating temperature of 25 K is reached using neon. Temperature difference between the thermosyphon's cold and warm ends is below 1 K for a heat transfer of 40 W. During operation, a temperature controller stabilizes condenser temperature and hence rotor temperature. The self-regulating cooling system has been operated continuously and without problems since Spring 2001. The machine was also operated with newly developed pulse-tube cryocoolers, that are in development to take benefit of their expected prolonged service intervals.

Frank, M.; Frauenhofer, J.; Gromoll, B.; van Haßelt, P.; Nick, W.; Nerowski, G.; Neumüller, H.-W.; Häfner, H.-U.; Thummes, G.

2004-06-01

98

Upward and downward heat and mass transfer with miniature periodically operating loop thermosyphons  

NASA Astrophysics Data System (ADS)

Upward and downward two-phase heat and mass transfer has been considered in the present paper. The heat and mass transfer with the condenser located below the evaporator has been obtained by inserting an accumulator tank in the liquid line of a loop thermosyphon and enforcing a pressure pulsation. In previous papers these heat transfer devices have been called pulsated two phase thermosyphons (PTPT). A mini PTPT has been experimentally investigated. It has shown a stable periodic heat transfer regime weakly influenced by the position of the condenser with respect to the evaporator. In contrast a classical loop mini thermosyphon (diameter of connecting pipes 4 mm) did not achieve a stable functioning for the investigated level differences between evaporator and condenser lower than 0.37 m. The present study shows that the functioning of a PTPT device does not directly depend on the level difference or the presence of noncondensable gas. In order to obtain a natural circulation in mini or micro loops, a periodically operating heat transfer regime should therefore be considered.

Fantozzi, Fabio; Filippeschi, Sauro; Latrofa, Enrico Maria

2004-03-01

99

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

100

RELAP5 Model of a Two-phase ThermoSyphon Experimental Facility for Fuels and Materials Irradiation  

SciTech Connect

The High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) does not have a separate materials-irradiation flow loop and requires most materials and all fuel experiments to be placed inside a containment. This is necessary to ensure that internal contaminants such as fission products cannot be released into the primary coolant. As part of the safety basis justification, HFIR also requires that all experiments be able to withstand various accident conditions (e.g., loss of coolant) without generating vapor bubbles on the surface of the experiment in the primary coolant. As with any parallel flow system, HFIR is vulnerable to flow excursion events when vapor is generated in one of those flow paths. The effects of these requirements are to artificially increase experiment temperatures by introducing a barrier between the experimental materials and the HFIR coolant and to reduce experiment heat loads to ensure boiling doesn t occur. A new experimental facility for materials irradiation and testing in the HFIR is currently being developed to overcome these limitations. The new facility is unique in that it will have its own internal cooling flow totally independent of the reactor primary coolant and boiling is permitted. The reactor primary coolant will cool the outside of this facility without contacting the materials inside. The ThermoSyphon Test Loop (TSTL), a full scale prototype of the proposed irradiation facility to be tested outside the reactor, is being designed and fabricated (Ref. 1). The TSTL is a closed system working as a two-phase thermosyphon. A schematic is shown in Fig. 1. The bottom central part is the boiler/evaporator and contains three electric heaters. The vapor generated by the heaters will rise and be condensed in the upper condenser, the condensate will drain down the side walls and be circulated via a downcomer back into the bottom of the boiler. An external flow system provides coolant that simulates the HFIR primary coolant. The two-phase flow code RELAP5-3D (Ref. 2) is the main tool employed in this design. The model has multiple challenges: boiling, condensation and natural convection flows need to be modeled accurately.

Carbajo, Juan J [ORNL] [ORNL; McDuffee, Joel Lee [ORNL] [ORNL

2013-01-01

101

Experimental investigation of natural convection heat exchange within a physical model of the manifold chamber of a thermosyphon heat-pipe evacuated tube solar water heater  

Microsoft Academic Search

The high capital costs associated with heat-pipe evacuated tube solar water heating systems can be reduced by replacing forced circulation with thermosyphon circulation. Currently research on thermosyphon heat-pipe evacuated tube solar water heaters is limited. An experimental investigation of the natural convective heat exchange regime that exists within the manifold chamber of a proprietary heat-pipe evacuated tube solar water was

David A. G. Redpath; Philip C. Eames; Steve N. G. Lo; Phillip W. Griffiths

2009-01-01

102

Experimental study on the performance characteristics of an enhanced two-phase loop thermosyphon  

NASA Astrophysics Data System (ADS)

A two-phase loop thermosyphon (TPLT) is an apparatus for heat transmission from the hot section of system (evaporator) to the cold part (condenser), with relatively small temperature differences. The setup used in this study consists of a TPLT, including evaporator, riser, an advanced condenser and downcomer. The condenser inlet has a nozzle. The steam rises from evaporator, flows through the nozzle and sprays on a vertical copper surface inside the condenser. To cool the copper sheet, then a cooler system was installed rear of it. The experimental tests were performed for presence of the nozzle and without it. The results showed that the TPLT efficiency increases for the modified condenser using nozzle. Also, the overall heat transfer coefficient of TPLT is enhanced by the nozzle. In the case of the nozzle with distance of 13 mm from copper sheet, and T e,sat > 55 °C, the value of bar{h}c suddenly increased.

Ziapour, Behrooz M.; Baygan, Majid; Mohammadnia, Ali

2015-02-01

103

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

104

A Thermosyphon Titanium-Water Heat Pipe Design for a Lunar Surface Power System  

NASA Astrophysics Data System (ADS)

A long titanium-water thermosyphon heat pipe was designed and tested in support of NASA's lunar surface power system. With a ?T of 11.6 C, a prototype has been shown to meet the temperature drop specification of 15 C at 400 W and 400 K. The heat pipe is designed to be embedded in a composite radiator panel to spread waste heat delivered by a circulating pumped loop. The major challenge was managing the fluid inventory to balance the conflicting requirements of power capacity and freeze-thaw tolerance. A unique hybrid wick was designed to achieve the required thermal performance and yet store all the working fluid during idle periods in a freeze-thaw tolerant fashion. A non-condensable gas charge was used to boost power capacity at lower operating temperatures. Eighteen prototypes will be built and tested.

Thayer, John; Semenov, Sergey

2009-03-01

105

Heat transfer in a two-phase thermosyphon operating with a fluid in the near critical state  

NASA Astrophysics Data System (ADS)

The heat transfer in the heating and cooling zones of a closed thermosyphon tube has been studied experimentally. Fluid pressure p/p(c) = 0.8-1.0 heat flow rate 175-1975 W and the inclination angle phi = 0-60 deg of the tube were varied. Refrigerant R 115 was used as a working fluid. According to the critical specific volume, the quantity of the fluid was determined. Boiling occurs in the heating zone, and condensation appears in the cooling zone. Depending on pressure, there are three regimes of boiling: nucleate boiling, nucleate boiling in a transition regime, and film boiling. In the thermosyphon, there exist laminar and turbulent film condensation, respectively. Combined heat transfer in the heating and cooling zones renders an overall performance with optimal conditions at phi = about 40 deg, a small heat flow rate, and p/p(c) = 0.9-1.0 as long as no film boiling occurs.

Gross, U.; Hahne, E.

1985-03-01

106

Mixed convection heat transfer and pressure drop correlations for tube-in-shell thermosyphon heat exchangers with uniform heat flux  

SciTech Connect

An important issue arising from prior studies of thermosyphon heat exchangers for use in solar water heaters is the need for heat transfer and pressure drop correlations for the laminar, mixed-convection regime in which these many of these heat exchangers operate. In this paper, the authors present empirical correlations for tube-in-shell heat exchangers with the thermosyphon flow on the shell side. The correlations are determined for uniform heat flux on the tube walls. Ranges of Reynolds and Grashof numbers are 130 to 2,000 and 4 {times} 10{sup 5} to 8 {times} 10{sup 7}, respectively. Nusselt number correlations are presented in a form that combines the contributions of forced and natural convection. Mixed convection dominates forced convection heat transfer in these geometries. Pressure drop is not significantly affected by mixed convection.

Dahl, S.D.; Davidson, J.H. [Univ. of Minnesota, Minneapolis, MN (United States). Mechanical Engineering Dept.

1998-11-01

107

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

108

Interfacial Force Field Characterization in a Constrained Vapor Bubble Thermosyphon  

NASA Technical Reports Server (NTRS)

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. These profiles are a function of the stress field. Experimentally, the augmented Young-Laplace equation is an excellent model for the force field at the solid-liquid-vapor interfaces for heptane and pentane menisci on quartz and tetradecane on SFL6. The effects of refractive indices of the solid and liquid on the measurement techniques were demonstrated. Experimentally obtained values of the disjoining pressure and dispersion constants were compared to those predicted from the Dzyaloshinskii - Lifshitz - Pilaevskii theory for an ideal surface and reasonable agreements were obtained. A parameter introduced gives a quantitative measurement of the closeness of the system to equilibrium. The nonequilibrium behavior of this parameter is also presented

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

1995-01-01

109

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

110

Laminar film flow phenomena-theory and application to the two-phase closed thermosyphon  

NASA Astrophysics Data System (ADS)

The hydrodynamic and thermal characteristics of thin, laminar wavy-film flow are considered. A theoretical model is developed to predict the hydrodynamic features of asymptotic wavy-flow states. The mathematical closure question arising in asymptotic-state analysis satisfactorily resolved. The model accurately predicts published experimental data for mean film thickness, trough-to-crest dimension, wave clarity, and wavelength. The Nusselt theory for laminar film condensation is shown to significantly underpredict existing experimental data due to the presence of waves on the condensate film surface. Consequently, a heat transfer model is developed incorporating the wave-film hydrodynamic model results. The subsequent predictions agree well with experimental data and, in addition, indicate the appropriate data trend with flow length. Other thin-film phenomena are described, including continuous-film breakdown, rivulet flow, and sputtering. All of these phenomena are present in the operation of a heat-transfer device known as the two-phase closed thermosyphon. Accordingly, this device is experimentally investigated.

Hirshburg, R. I.

1980-12-01

111

Improving thermosyphon solar domestic hot water system model performance. Final report, March 1994--February 1995  

SciTech Connect

Data from an indoor solar simulator experimental performance test is used to develop a systematic calibration procedure for a computer model of a thermosyphoning, solar domestic hot water heating system with a tank-in-tank heat exchanger. Calibration is performed using an indoor test with a simulated solar collector to adjust heat transfer in the heat exchanger and heat transfer between adjacent layers of water in the storage tank. An outdoor test is used to calibrate the calculation of the friction drop in the closed collector loop. Additional indoor data with forced flow in the annulus of the heat exchanger leads to improved heat transfer correlations for the inside and outside regions of the tank-in-tank heat exchanger. The calibrated simulation model is compared to several additional outdoor tests both with and without auxiliary heating. Integrated draw energies are predicted with greater accuracy and draw temperature profiles match experimental results to a better degree. Auxiliary energy input predictions improve significantly. 63 figs., 29 tabs.

Swift, T.N.

1996-09-01

112

Determination of the dispersion constant in a constrained vapor bubble thermosyphon  

NASA Technical Reports Server (NTRS)

The isothermal profiles of the extended meniscus in a quartz cuvette were measured in a gravitational field using an 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-siru at the start of the heat transfer experiments by quantifying the dispersion constant, which is a function of the liquid-solid system and cleaning procedures. The experimentally obtained values of the disjoining pressure and the dispersion constants were compared to that predicted from the DLP theory and good agreements were obtained. The measurements are critical to the subsequent non-isothermal experiments because one of the major variables in the heat sink capability of the Constrained Vapor Bubble Thermosyphon, CVBT, is the dispersion constant. In all previous studies of micro heat pipes the value of the dispersion constant has been 'estimated'. One of 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 the force field at the solid-liquid-vapor interfaces.

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

1995-01-01

113

A 100-W grade closed-cycle thermosyphon cooling system used in HTS rotating machines  

NASA Astrophysics Data System (ADS)

The cooling systems used for rotating High-Temperature Superconducting (HTS) machines need a cooling power high enough to ensure a low temperature during various utilization states. Radiation, torque tube or current leads represent hundreds of watts of invasive heat. The architecture also has to allow the rotation of the refrigerant. In this paper, a free-convection thermosyphon using two Gifford-McMahon (GM) cryocoolers is presented. The cryogen is mainly neon but helium can be added for an increase of the heat transfer coefficient. The design of the heat exchangers was first optimized with FEM thermal analysis. After manufacture, they were assembled for preliminary experiments and the necessity of annealing was studied for the copper parts. A single evaporator was installed to evaluate the thermal properties of such a heat syphon. The maximum bearable static heat load was also investigated, but was not reached even at 150 W of load. Finally, this cooling system was tested in the cooling down of a 100-kW range HTS rotating machine containing 12 Bi-2223 double-pancake coils (DPC).

Felder, Brice; Miki, Motohiro; Tsuzuki, Keita; Shinohara, Nobuyuki; Hayakawa, Hironao; Izumi, Mitsuru

2012-06-01

114

Experimental investigation and optimisation study of a direct thermosyphon heat-pipe evacuated tube solar water heater subjected to a northern maritime climate  

Microsoft Academic Search

A proprietary heat-pipe Evacuated Tube Solar Water Heater (ETSWH) originally designed for collection of solar energy using forced fluid circulation was operated using thermosyphon fluid circulation. The thermal performance of this solar water heating system was monitored from October 2006 to June 2007. The ETSWH array was inclined with the expected collector outlet at a higher datum level than the

D. A. G. Redpath; S. N. G. Lo; P. C. Eames

2010-01-01

115

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

116

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

117

Heat transfer performances of a thermosyphon contained non-condensible gas (1)  

NASA Astrophysics Data System (ADS)

The heat transfer performances of the thermosiphon contained non-condensible gas with the working fluid were obtained by an experimental study. The relations among the heat transfer rate, the effectively working length of condenser, the temperature difference between the evaporator and the condenser, and the over-all heat transfer coefficient are described.

Kaneko, K.; Negishi, K.

1985-03-01

118

Comparison of performance and cost effectiveness of solar water heaters at different collector tracking modes in Cyprus and Greece  

Microsoft Academic Search

The present study is concerned with investigation of the thermal performance and cost effectiveness of thermosyphon solar water heaters with different solar collector tracking modes under the weather and socioeconomic conditions of Nicosia–Cyprus and Athens–Greece. The tracking modes are the traditional configuration with the collector surface fixed to 40 degrees from the horizontal, the single-axis tracking with vertical axis, fixed

I. M. Michaelides; S. A. Kalogirou; I. Chrysis; G. Roditis; A. Hadjiyianni; H. D. Kambezidis; M. Petrakis; S. Lykoudis; A. D. Adamopoulos

1999-01-01

119

Heat-transfer characteristics of the R113 annular two-phase closed thermosyphon - Heat transfer in the condenser  

NASA Astrophysics Data System (ADS)

Visual observation of flow patterns in the condenser and heat transfer measurements were conducted for heat transfer rate ranges of 18-800 W using a vertical annular device with various quantities of R113 as a working fluid. As a result of visual observations, it was shown that ripples (interfacial waves) were generated on the condensate film surface when the condensate film Reynolds number exceeded approximately 20, and the condensation heat transfer was prompted. A simple theoretical analysis was presented in which the effects of interfacial waves and vapor drag were both considered. This analysis agreed very well with experimental results when the working fluid quantity was small enough so that the two-phase mixture generated by boiling the working fluid did not reach the condenser. The effects of interfacial waves and vapor drag on condensation heat transfer were also investigated theoretically.

Maezawa, Saburo; Tsuchida, Akira; Takuma, Masao

1988-08-01

120

Secondary flow effects in high tip speed free convection  

SciTech Connect

Experimental analyses of the effects of secondary flows on heat transfer in high tip speed rotating apparatus are not readily available. This paper provides data on the heat transfer within two different test modules which were rotated at high speed with the heat transfer surfaces perpendicular and parallel to the Coriolis acceleration. One module contained a heated wall and another a parallel plate free convection experiment. Uniform heat fluxes were maintained. Rayeigh numbers in excess of 10{sup 15} were achieved with liquid helium as the transfer medium. Some of the findings are that secondary flows can reduce heat transfer by as much as 60% in single-phase heat transfer, the transitions to fully turbulent flow are in agreement with existing prediction methods, the critical heat flux in two-phase flow boiling is significantly increased, forced convection correlations underpredict single-phase thermosyphon performance, and the usual nondimensional parameters of free convection establish similitude between various fluids and speeds. These results suggest that techniques used to enhance heat transfer in the rotating frame should be verified by tests in the rotating frame.

Eckels, P.W.; Parker, J.H. Jr.; Patterson, A. (Westinghouse Research Labs., Pittsburgh, PA (USA))

1987-02-01

121

Effect of non-condensable gas on vapor flow in the condenser of VCHP  

NASA Astrophysics Data System (ADS)

A fundamental study of the effect of noncondensable gas on a vapor flow in the condenser region of VCHP (variable conductance heat pipe) was conducted experimentally and analytically. In the experiment, a specific thermosyphon or a wickless VCHP model was fabricated which has a condenser of rectangular cross sectional area to realize two-dimensional flow field. Detailed flow field surveys conducted are measurements of temperature distributions by thermocouples, heat transfer rates in the condenser by film gauge and hot-wire, and flow field visualization by laser holographic interferometer. In order to investigate the dominant physical parameters in the flow field observed in the experiment a numerical simulation was performed by adopting a binary mixture model. An important finding in this study is a fact that the gravity force has a strong effect on the location and profile of an interfacial layer between vapor and noncondensable gas. The idea of formation of a clear diffusion front layer in the condenser would mislead to an erroneous interpretation of thermofluid dynamic behavior of VCHPs for terrestrial use.

Kobayashi, Yasunori; Okumura, Akira; Matsue, Toshihisa

1989-06-01

122

Reflux condensation characteristics of a two-phase closed thermosyphon  

NASA Astrophysics Data System (ADS)

This paper investigates the feasibility of the application of the heat pipe concept to the study of reflux condensation. An experiment is carried out whereby the condensation heat transfer coefficients are obtained for a turbulent vapor flow and a laminar condensate flow. Corresponding Nusselt's laminar film condensation heat transfer coefficients are calculated and compared. A discussion on the applicability of the heat pipe concept to the study of reflux condensation is also presented.

Ho, W. K.; Tien, C. L.

123

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

124

Effect of non-condensable gas on the vapor flow in thermosiphons  

NASA Astrophysics Data System (ADS)

A detailed flow field survey was conducted to get a better insight into condensation mechanism of vapor flow onto the cooled plate in the enclosure. A two-dimensional thermosyphon was used as an experimental apparatus and special attention was paid to the effect of non-condensable gas in the thermosiphon. Generally it is understood that the non-condensable gas in the thermosiphon in its steady state operation occupies an upper region of the condensation section, and that there exists an interfacial layer separating vapor flow from non-condensable gas which will move vertically according to the heat input rate applied to the thermosiphon. However the structural properties of this interfacial layer and the boundary layer on the wall of condensation section, such as location of layers, thickness, temperature or density variation across them, have not been thoroughly investigated. A real time laser holographic interferometer was used to visualize a flow field in the thermosiphon. Temperature distribution was measured to evaluate the total heat transfer coefficient in the condensation section.

Matsumoto, T.; Kobayashi, Y.

1985-03-01

125

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

126

Pulsating Heat Pipes: Thermo-fluidic Characteristics and Comparative Study with Single Phase Thermosyphon  

E-print Network

in microelectronics thermal management [1]. The PHP is made of 10 parallel glass tubes (ID: 2 mm, OD: 4.2 mm, 100mm SXOVDWLQJ KHDW SLSHV A closed loop pulsating or oscillating heat pipe consists of a metallic tube of capillary dimensions wound in a serpentine manner and joined end to end as shown in Fig. 1. It is first

Khandekar, Sameer

127

Laminar film flow phenomena: Theory and application to the two phase closed thermosyphon  

NASA Astrophysics Data System (ADS)

A theoretical model is developed to predict the hydrodynamic features of asymptotic wavy flow states. The model accurately predicts published experimental data for mean film thickness, trough-to-crest dimension, wave celerity, and wavelength. The Nusselt theory for laminar film condensation is shown to significantly under-predict existing experimental data due to the presence of waves on the condensate film surface. A heat transfer model is developed incorporating the wavy film hydrodynamic model results. Other thin film phenomena are described, including continuous film breakdown, rivulet flow, and sputtering. All of these phenomena are present in the operation of a heat transfer device.

Hirshburg, R. T.; Florschuetz, L. W.

1980-05-01

128

A proposed regenerative thermosyphon blade cooling system for high efficiency gas turbines  

NASA Astrophysics Data System (ADS)

A novel scheme for cooling high-efficiency gas turbine engines is proposed, briefly analyzed, and evaluated. The scheme consists of a self-pumping thermosiphon loop for the rotors and a closed forced-convection loop for the stators. With a suitable coolant, such as liquid metal, the rotating thermosiphon loop is self-pumping. The circulation rates can be large enough that the loop acts as a heat pipe of large conductance between the turbine and the compressor. The flow stability and distribution in the multiple parallel rotating loops are examined, and stable configurations are identified. A simple thermodynamic model for cycle cooling losses is developed and used to evaluate the potential efficiency advantage of using this scheme compared to current air-cooling technology. A gain of five to eight percent is found possible.

El-Masri, M. A.

129

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

130

Determination of the dispersion constant in a constrained vapor bubble thermosyphon  

NASA Technical Reports Server (NTRS)

The isothermal profiles of the extended meniscus in a quartz cuvette were measured in a gravitational field using an 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, which is a function of the liquid-solid system and cleaning procedures. The experimentally obtained values of the disjoining pressure and the dispersion constants were compared to that predicted from the DLP theory and good agreements were obtained. The measurements are critical 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'. One of 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 the force field at the solid-liquid-vapor interfaces.

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

1993-01-01

131

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

132

Advertising Effects and Effectiveness  

Microsoft Academic Search

The results of the application of an integrated econometric time-series model for advertising effectiveness is presented. The model form gives rise to three possible advertising effects: brand loyalty, current effects (both simple and compound) and carryover effects. The inherent nature of these effects is related to the degree of involvement and the affective or cognitive aspects of the purchase decision.

Mike T. Bendixen

1993-01-01

133

Engineering Design Elements of a Two-Phase Thermosyphon to Trannsfer NGNP Nuclear Thermal Energy to a Hydrogen Plant  

SciTech Connect

Two hydrogen production processes, both powered by a Next Generation Nuclear Plant (NGNP), are currently under investigation at Idaho National Laboratory. The first is high-temperature steam electrolysis, which uses both heat and electricity; the second is thermo-chemical production through the sulfur iodine process primarily using heat. Both processes require a high temperature (>850°C) for enhanced efficiency; temperatures indicative of the NGNP. Safety and licensing mandates prudently dictate that the NGNP and the hydrogen production facility be physically isolated, perhaps requiring separation of over 100 m.

Piyush Sabharwal

2009-07-01

134

The threshold value of heat flux for thermosyphon microfilm heat transfer with the testing sample partially immersed in liquid nitrogen  

NASA Astrophysics Data System (ADS)

To simulate the performance of condenser-boiler in an air separation plant, the boiling section formed by 1m long plate-fin narrow channel is only partially immersed in liquid nitrogen. When the heating power supplied to whole section of the testing sample is maintained constant the boiling temperature difference is increased by 0.19K only with reduction in immersion depth of 40cm. It is concluded that the condenser-boiler will be operated in a safe condition even when the immersion reduced by 40% as long as the heat flux is maintained above a threshold value.

Yuyuan, Wu; Shouyun, Peng; Liufang, Chen; Hongqi, Xie

135

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

136

Simulation of natural convection in a rectangular loop using finite elements  

SciTech Connect

A two-dimensional finite-element analysis of natural convection in a rectangular loop is presented. A psi-omega formulation of the Boussinesque approximation to the Navier-Stokes equation is solved by the false transient technique. Streamlines and isotherms at Ra = 10/sup 4/ are shown for three different modes of heating. The results indicate that corner effects should be considered when modeling flow patterns in thermosyphons.

Pepper, D W; Hamm, L L; Kehoe, A B

1984-01-01

137

Heat Pipe Applications in Sorption Refrigerators  

Microsoft Academic Search

\\u000a Some sorption refrigeration machines (sorption technologies) developed in Belarus are presented in this paper with emphasises\\u000a on different heat pipes application: conventional heat pipes, heat pipe panels, loop heat pipes, vapour-dynamic thermosyphons,\\u000a etc. Heat pipes are very flexible systems with regards to the effective thermal control. They can easily be implemented inside\\u000a sorption refrigerators and other types of refrigerators [1].

L. L. Vasiliev; A. G. Kulakov

138

Natural convection heat exchangers for solar water heating systems. Technical progress report, September 15, 1996--November 14, 1996  

SciTech Connect

The goals of this project are: (1) to develop guidelines for the design and use of thermosyphon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger. The tasks for the project are as follows: (1) Develop a model of the thermal performance of thermosyphon heat exchangers in solar water heating applications. A test protocol will be developed which minimizes the number of tests required to adequately account for mixed convection effects. The TRNSYS component model will be fully integrated in a system component model and will use data acquired with the specified test protocol. (2) Conduct a fundamental study to establish friction and heat transfer correlations for conditions and geometries typical of thermosyphon heat exchangers in solar systems. Data will be obtained as a function of a buoyancy parameter based on Grashof and Reynolds numbers. The experimental domain will encompass the ranges expected in solar water heating systems.

Davidson, J.H.

1998-06-01

139

Natural convection heat exchangers for solar water heating systems. Technical progress report, August 1, 1995--September 30, 1995  

SciTech Connect

The goals of this project are: (1) to develop guidelines for the design and use of thermosyphon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger. The tasks for the project are as follows: (1) Develop a model of the thermal performance of thermosyphon heat exchangers in solar water heating applications. A test protocol will be developed which minimizes the number of tests required to adequately account for mixed convection effects. The TRNSYS component model will be fully integrated in a system component model and will use data acquired with the specified test protocol. (2) Conduct a fundamental study to establish friction and heat transfer correlations for conditions and geometries typical of thermosyphon heat exchangers in solar systems. Data will be obtained as a function of a buoyancy parameter based on Grashof and Reynolds numbers. The experimental domain will encompass the ranges expected in solar water heating systems.

Davidson, J.H.

1998-06-01

140

Natural convection heat exchangers for solar water heating systems. Technical progress report, December 31, 1995--January 31, 1996  

SciTech Connect

The goals of this project are: (1) to develop guidelines for the design and use of thermosyphon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger. The tasks for the project are as follows: (1) Develop a model of the thermal performance of thermosyphon heat exchangers in solar water heating applications. A test protocol will be developed which minimizes the number of tests required to adequately account for mixed convection effects. The TRNSYS component model will be fully integrated in a system component model and will use data acquired with the specified test protocol. (2) Conduct a fundamental study to establish friction and heat transfer correlations for conditions and geometries typical of thermosyphon heat exchangers in solar systems. Data will be obtained as a function of a buoyancy parameter based on Grashof and Reynolds numbers. The experimental domain will encompass the ranges expected in solar water heating systems.

Davidson, J.H.

1998-06-01

141

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.

142

Doppler Effect  

NSDL National Science Digital Library

Doppler effect followed from water waves to sound waves to light waves. Red shift of the universe is also explored. What is doppler effect? It is the change in frequency of a wave for an observer moving relative to the source of the wave. What does that mean? Watch this: moving doppler effect video What does the doppler effect look like in a stationary and moving object? dooppler effect views What does doppler effect have to do with stars and galaxies??? View the following ...

Mrs. Clemons

2010-11-10

143

Doppler Effect  

NSDL National Science Digital Library

Doppler effect followed from water waves to sound waves to light waves. Red shift of the universe is also explored. What is doppler effect? It is the change in frequency of a wave for an observer moving relative to the source of the wave. What does that mean? Watch this: moving doppler effect video What does the doppler effect look like in a stationary and moving object? dooppler effect views What does doppler effect have to do with stars and galaxies??? View the following ...

Mrs. Brown

2010-10-26

144

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.

Connecticut Energy Education

145

School Effectiveness and Effectiveness Indicators.  

ERIC Educational Resources Information Center

Examines connections between Alberta practitioners' perceptions of current school effectiveness in elementary and junior high schools and the relative importance of various effectiveness indicators. Because of differences in practioners' perceptions, schools and school systems need to continually probe the dimensions of school-effectiveness

Holdaway, Edward A.; Johnson, Neil A.

1993-01-01

146

Health Effects  

MedlinePLUS

... Possible Health Effects Short-term Strong hallucinations including perceptions of otherworldly imagery, altered visual and auditory perceptions; increased blood pressure, vomiting. Long-term Unknown. Other ...

147

Gauging Effectiveness  

ERIC Educational Resources Information Center

Books by education experts and speakers at national professional conferences have inspired many school leaders to initiate professional learning communities (PLCs). Sustaining them effectively to raise student achievement is another matter. How can one know whether a PLC is moving toward a desired outcome? Measuring effectiveness requires an…

Foord, Kathleen A.; Haar, Jean M.

2012-01-01

148

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

149

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.

2014-02-03

150

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. ...

Mr. Leet

2008-03-16

151

Doppler Effect  

NSDL National Science Digital Library

Control the velocity of two sound sources in which the wave crests are visually represented. As the sound sources move, interference patterns and evidence of the Doppler effect can be observed and measured.

2007-12-12

152

Chemotherapy Effects  

MedlinePLUS

... Basics Cancer Prevention & Detection Signs & Symptoms of Cancer Treatments & Side Effects Cancer Facts & Statistics News About Cancer Expert Voices Blog Programs & Services Breast Cancer Support TLC Hair Loss & Mastectomy Products Hope ...

153

Health Effects  

MedlinePLUS

... Chapter . Additional information regarding the health effects of climate change and references to supporting literature can be found ... http://nca2014.globalchange.gov/report/sectors/human-health . Climate change, together with other natural and human-made health ...

154

Effects and Effectiveness of Telemedicine  

PubMed Central

The use of telemedicine has recently undergone rapid growth and proliferation. Although the feasibility of many applications has been tested for nearly 30 years, data concerning the costs, effects, and effectiveness of telemedicine are limited. Consequently, the development of a strategy for coverage, payment, and utilization policy has been hindered. Telemedicine continues to expand, and pressure for policy development increases in the context of Federal budget cuts and major changes in health service financing. This article reviews the literature on the effects and medical effectiveness of telemedicine. It concludes with several recommendations for research, followed by a discussion of several specific questions, the answers to which might have a bearing on policy development. PMID:10153466

Grigsby, Jim; Kaehny, Margaret M.; Sandberg, Elliot J.; Schlenker, Robert E.; Shaughnessy, Peter W.

1995-01-01

155

Research and development of long heat pipes and their applications  

NASA Astrophysics Data System (ADS)

A 40 m thermosyphon type flexible corrugated heat pipe was constructed and its heat transfer characteristics were measured. The flooding phenomenon was quantitatively observed using electronic stethoscopes, and its influence to the heat transfer characteristics was determined. The particular features of the road heating system using long heat pipes are: (1) there is no possibility of water leaking and their maintenance is easy; (2) they endure heavy loads, thermal stresses, vibrations and ground subsidence; (3) the heat transfering surface area of the heat pipes is so large that it is particularly effective for heating through small temperature difference; and (4) the installation is easy and inexpensive.

Takaoka, M.; Mohtai, T.; Mochizuki, M.; Mashiko, K.

1984-03-01

156

Flow field visualization of vapor condensation in the enclosure  

NASA Astrophysics Data System (ADS)

Thermofluid dynamics and phase changes of fluid in enclosures were studied for the practical requirement of developing effective heat transfer systems and devices. The incompleteness in understanding the vaporizing and condensation mechanisms of fluid makes it difficult to formulate a sound modeling of the flow field for obtaining an optimum design of safety equipments for power plants, cooling systems for building, and various heat exchangers for industrial applications. The flow field undergoing vapor condensation onto the flat plate in a simple thermosyphon was investigated. Flow visualization by lasr holographic interferometry is implemented along with supplimentary temperature and pressure measurements of vapor in the vessel.

Kobayashi, Y.; Kaneko, M.; Matsumoto, T.

1983-03-01

157

Research and Development for Novel Thermal Energy Storage Systems (TES) for Concentrating Solar Power (CSP)  

SciTech Connect

The overall objective was to develop innovative heat transfer devices and methodologies for novel thermal energy storage systems for concentrating solar power generation involving phase change materials (PCMs). Specific objectives included embedding thermosyphons and/or heat pipes (TS/HPs) within appropriate phase change materials to significantly reduce thermal resistances within the thermal energy storage system of a large-scale concentrating solar power plant and, in turn, improve performance of the plant. Experimental, system level and detailed comprehensive modeling approaches were taken to investigate the effect of adding TS/HPs on the performance of latent heat thermal energy storage (LHTES) systems.

Faghri, Amir; Bergman, Theodore L; Pitchumani, Ranga

2013-09-26

158

Email Effects  

NSDL National Science Digital Library

This site caters to those in search of an easier way to create tables, flow charts, maps, chemical structure diagrams, and the like. Email Effects can also add fun pictures to the signatures at the bottom of email messages for Macintosh owners who use Qualcomm's Eudora or Claris Emailer. This $10 shareware offers an easy-to-use interface with a drawing-like toolbar to create or convert the items mentioned above into ASCII based text. To convert an item, just copy and paste it into the Email Effects window. The text can be saved and/or added to an email message with the click of a button. Email Effects is provided by Sig Software. The download comes with text clip art.

159

Plasma Effects  

NASA Technical Reports Server (NTRS)

Radio communication with space probes requires sending signals through the Earth's ionosphere and usually the solar wind. During planetary flybys, the signal may also pass through the ionosphere of another planet. These ionized media can perturb the radio signal in a variety of ways. Examples of these perturbations are variations in the electrical length between the spacecraft and the ground station, Faraday rotation of linearly polarized signals, amplitude and phase scintillations, and spectral and angular broadening. These plasma effects can have undesirable influences on telemetry performance and thus need to be understood from a communications engineering viewpoint. The plasma effects are, however, useful from a scientific viewpoint, since the effects on the communications link can often be inverted to estimate the physical conditions in the plasma.

Armstrong, J. W.

1983-01-01

160

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.

161

Interpersonal Effectiveness  

NSDL National Science Digital Library

Interpersonal Effectiveness provides participants with an opportunity to develop their interpersonal skills through interactive exercises conducted in a team setting. Debriefing these exercises with all members of the class helps ensure that the exercises translate into personal and interpersonal learning for the participants. After completing this module, students should be able to identify the principles of good teamwork and effective communication and demonstrate those skills during a series of interactive exercises. Note: This module is part of a modularized manufacturing technology curriculum created by the PSCME, found at www.pscme.org/educators.html.

Alston, Michele

162

Effects of \\  

Microsoft Academic Search

Recorded the voices of white and black male college students reading instructions and questions for the Peabody Picture Vocabulary Test (PPVT). 124 black and 128 white children from the same school in Grades 1-4 completed the PPVT after listening to 1 of the examiner's voices. Analysis of PPVT scores indicates significant effects for race of voice and race of S,

Kenneth France

1973-01-01

163

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

164

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

165

Blazhko Effect  

NASA Technical Reports Server (NTRS)

The cause of the Blazhko effect, the long-term modulation of the light and radial velocity curves of some RR Lyr stars, is still not understood. The observational characteristics of the Blazhko effect are discussed. Some preliminary results are presented from two recent campaigns to observe RR Lyr, using the International Ultraviolet Explorer along with ground-based spectroscopy and photometry, throughout a pulsation cycle, at a variety of Blazhko phases. A set of ultraviolet light curves have been generated from low dispersion IUE spectra. In addition, the (visual) light curves from IUE's Fine Error Sensor are analyzed using the Fourier decomposition technique. The values of the parameters Psi(sub 21) and R(sub 21) at different Blazhko phases of RR Lyr span the range of values found for non-Blazhko variables of similar period.

Teays, Terry

1996-01-01

166

Ripple Effects  

E-print Network

of water. In another portion of the economics project, Amosson and Extension Associate Bridget Guerrero take the results a step further. Using a socio-economic planning model, they first incorporate economic data for the counties in each sub...-region and in particular crop production costs. Finally, they input the initial effects on farmers? incomes gained from the opti- mization models into the socio-economic modeling program. The results give an idea of what specific policies or technological advances...

Wythe, Kathy

2006-01-01

167

Erosion Effects  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

The impact crater in this THEMIS image is a model illustration to the effects of erosion on Mars. The degraded crater rim and several landslides observed in crater walls is evidence to the mass wasting of materials. Layering in crater walls also suggests the presence of materials that erode at varying rates.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Image information: VIS instrument. Latitude 31.6, Longitude 44.3 East (315.7 West). 19 meter/pixel resolution.

2003-01-01

168

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

169

Design and Performance of a Hybrid PV/T Solar Water Heater  

NASA Astrophysics Data System (ADS)

In this paper we present design considerations and experimental results of a thermosyphonic hybrid PV/T solar system that is investigated at the University of Patras. Hybrid PV/T systems can provide electrical and thermal energy, thus achieving a higher energy conversion rate of the absorbed solar radiation. We tested outdoors PV/T prototypes consisted of pc-Si PV modules and heat exchanger of copper sheet with copper pipes, for two system types (PVT/UNGL and PVT/GL). We used commercial PV modules, which give about 12%-15% efficiency, depending on the operating temperature and the use or not of additional glazing. During the experiments the generated electricity was transmitted to a load, simulating real system operation. Steady state tests of the system were performed outdoors to determine collector thermal efficiency. The glazed PV/T collector presents remarkably higher thermal output than the unglazed PV/T collector, but the electrical output of it is reduced due to additional optical losses. The experimental study of the tested thermosyphonic hybrid PV/T solar device showed that it can perform effectively during all year long, achieving at least 40° C of hot water and producing electricity at a satisfactory level.

Tripanagnostopoulos, Y.; Souliotis, M.; Makris, Th.; Georgostathis, P.; Sarris, M.

2010-01-01

170

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

171

Solar domestic hot water system, a comparative study and storage tank investigation  

NASA Astrophysics Data System (ADS)

A computer program was developed to simulate five typical solar domestic hot water systems which included both thermosyphon and pumped designs that were assembled and tested. Numerical simulations of these systems were verified by comparison to experimental results. Predicted thermal performance, i.e., collector inlet and outlet temperatures, and auxiliary energy requirements were found to be in excellent agreement with experiments. The computer program was then used to predict the long term annual performance of the various systems at 14 different locations throughout California. Load size and load distribution were also varied. Economic analyses were performed on each system with the goal of identifying the most economical system at each location under a prescribed load (gallons/day) size and distribution pattern (time of day for hot water use). It was found that in almost all cases the two tank thermosyphon system was the most cost effective system for all locations, load sizes and distributions and shows promise of being the most widely used solar domestic hot water system.

Young, M. F.

1980-03-01

172

Side Effects of Chemotherapy  

MedlinePLUS

... PCF Spotlight Glossary African American Men Living with Prostate Cancer Side Effects of Chemotherapy Side Effects Urinary Dysfunction ... side effects of docetaxel as used to treat prostate cancer are VERY different and less severe than the ...

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

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

175

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

176

Improving School Effectiveness.  

ERIC Educational Resources Information Center

School effectiveness is an issue that has preoccupied researchers and policymakers for 3 decades. To study how ineffective schools become effective and what constitutes an effective school, the Improving School Effectiveness Project was carried out in Scotland from 1995 to 1997. This project forms the basis of discussion in this book, which has 11…

MacBeath, John, Ed.; Mortimore, Peter, Ed.

177

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 . ...

Ms. Ufomadu

2013-06-13

178

Gravitational Casimir Effect  

NASA Astrophysics Data System (ADS)

We derive the gravitonic Casimir effect with nonidealized boundary conditions. This allows the quantification of the gravitonic contribution to the Casimir effect from real bodies. We quantify the meagerness of the gravitonic Casimir effect in ordinary matter. We also quantify the enhanced effect produced by the speculated Heisenberg-Couloumb (HC) effect in superconductors, thereby providing a test for the validity of the HC theory, and, consequently, the existence of gravitons.

Quach, James Q.

2015-02-01

179

WASC EDUCATIONAL EFFECTIVENESS REVIEW EDUCATIONAL EFFECTIVENESS APPROACH  

E-print Network

to its citizens, articulated in the Master Plan for Higher Education, UC Santa Cruz must continue to doWASC EDUCATIONAL EFFECTIVENESS REVIEW EDUCATIONAL EFFECTIVENESS APPROACH UC Santa Cruz ... ranked sought to maintain the high quality of our undergraduate education. We also seek to continue growth

California at Santa Cruz, University of

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

Open Archive Toulouse Archive Ouverte (OATAO) OATAO is an open access repository that collects the work of Toulouse researchers and  

E-print Network

, 2005). Hydrothermal reactions are also responsible for many ore processing and hydrothermal ( 2010) A thermosyphon-driven hydrothermal flow-through cell for in situ and time-resolved neutron-oatao@inp-toulouse.fr #12;A thermosyphon-driven hydrothermal flow-through cell for in situ and time-resolved neutron

Mailhes, Corinne

182

Managing Physical Effects  

Cancer.gov

Browse a list of common side effects of cancer or cancer treatment with links to practical information for preventing or relieving these effects. Also find information on maintaining proper nutrition during cancer treatment.

183

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 ...

184

Effective College Teaching.  

ERIC Educational Resources Information Center

The author discusses other writings on effective college teaching and then presents his list of necessary characteristics for the effective teacher, stressing the interpersonal dimension of the teaching-learning situation. (MF)

Caraway, James E.

1978-01-01

185

Stormwater BMP Effectiveness Toolkit  

EPA Science Inventory

US EPA has identified the effectiveness of Stormwater Best Management Practices (BMPs) as a priority research need. Effective protection of biotic integrity requires that processes maintaining the diversity of physical habitats be protected. Methods are needed to evaluate the e...

186

Special Effects Activity Guide.  

ERIC Educational Resources Information Center

This guide accompanies "Special Effects," a 40-minute IMAX film and "Special Effects II", a multimedia, interactive traveling exhibit designed by the California Museum of Science and Industry. The exhibit focuses on the underlying scientific and technical processes of special effects from the earliest motion picture to state-of-the-art digital…

Boxer, Jennifer; Valenta, Carol

187

Electrocaloric effect on graphenes  

NASA Astrophysics Data System (ADS)

The present Letter explores the electrocaloric effect of graphene nano-ribbons, with a longitudinal electric field and transversal magnetic field. Special features of the effect can be ruled and tuned by the applied fields as, for instance, the unusual inverse effect, created by the Landau levels. These results open doors to enhance electrocaloric utility of materials.

Reis, M. S.; Soriano, S.

2013-03-01

188

Effects of Nuclear Weapons.  

ERIC Educational Resources Information Center

Fundamental principles governing nuclear explosions and their effects are discussed, including three components of a nuclear explosion (thermal radiation, shock wave, nuclear radiation). Describes how effects of these components depend on the weapon's yield, its height of burst, and distance of detonation point. Includes effects of three…

Sartori, Leo

1983-01-01

189

Side Effects of Hormone Therapy  

MedlinePLUS

... Men Living with Prostate Cancer Side Effects of Hormone Therapy Side Effects Urinary Dysfunction Bowel Dysfunction Erectile Dysfunction Loss of Fertility Side Effects of Hormone Therapy Side Effects of Chemotherapy Side Effects: When ...

190

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

191

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

192

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

193

Enhanced magnetocaloric effect material  

DOEpatents

A magnetocaloric effect heterostructure having a core layer of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, and a constricting material layer coated on at least one surface of the magnetocaloric material core layer. The constricting material layer may enhance the magnetocaloric effect by restriction of volume changes of the core layer during application of a magnetic field to the heterostructure. A magnetocaloric effect heterostructure powder comprising a plurality of core particles of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, wherein each of the core particles is encapsulated within a coating of a constricting material is also disclosed. A method for enhancing the magnetocaloric effect within a giant magnetocaloric material including the step of coating a surface of the magnetocaloric material with a constricting material is disclosed.

Lewis, Laura J. H.

2006-07-18

194

Blowing Ratio Effects on Film Cooling Effectiveness  

E-print Network

The research focuses on testing the film cooling effectiveness on a gas turbine blade suction side surface. The test is performed on a five bladed cascade with a blow down facility. Four different blowing ratios are used in this study, which are 0...

Liu, Kuo-Chun

2010-01-14

195

Effect Identification in Comparative Effectiveness Research  

PubMed Central

The widespread adoption of electronic medical records means there are now vast data resources available for comparative effectiveness research (CER). In concert with conventional randomized controlled trials, CER holds great promise for advancing our understanding of how different therapeutic treatments yield different health outcomes in different settings and with different populations. But in a research culture fixated on estimating correlations and p-values, the threat of misinterpretation of results and improper CER inferences is troubling. Accordingly, this paper aims to shore up the inferential foundations of CER by introducing the fundamentals of effect identification, which is the process of identifying or teasing out empirically defensible causal effects from competing explanations. Three primary requirements of effect identification—positivity, exchangeability, and consistency— are explained and simple exampled are given. The take home message is that so-called big data from medical records may not yield better or more useful results. Advances will come only when the right question is addressed with the appropriate data and methods.

Oakes, J. Michael

2013-01-01

196

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

197

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

198

Atomic lighthouse effect.  

PubMed

We investigate the deflection of light by a cold atomic cloud when the light-matter interaction is locally tuned via the Zeeman effect using magnetic field gradients. This "lighthouse" effect is strongest in the single-scattering regime, where deviation of the incident field is largest. For optically dense samples, the deviation is reduced by collective effects, as the increase in linewidth leads to a decrease in magnetic field efficiency. PMID:25401364

Máximo, C E; Kaiser, R; Courteille, Ph W; Bachelard, R

2014-11-01

199

The Atomic Lighthouse Effect  

E-print Network

We investigate the deflection of light by a cold atomic cloud when the light-matter interaction is locally tuned via the Zeeman effect using magnetic field gradients. This "lighthouse" effect is strongest in the single-scattering regime, where deviation of the incident field is largest. For optically dense samples, the deviation is reduced by collective effects, as the increase in linewidth leads to a decrease of the magnetic field efficiency.

Máximo, C E; Courteille, Ph W; Bachelard, R

2014-01-01

200

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

201

Effects on Insects  

Technology Transfer Automated Retrieval System (TEKTRAN)

The effects of controlled and modified atmospheres on insects is reviewed and summarized in this chapter. Traditionally, controlled and modified atmospheres are used to store and preserve fresh fruits and vegetables. The effects on insects and the potential of these treatments are secondary to the...

202

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.

203

Relativistic effects in chemistry  

Microsoft Academic Search

Relativistic effects become apparent when the velocity of the electron is arbitrarily close to the speed of light (137 au) without actually attaining it (in heavy atoms of elements at the end of Mendeleev's Periodic Table). At the orbital level, the relativistic effect is apparent in the radial contraction of penetrating s and p shells, expansion of nonpenetrating d and

K. B. Yatsimirskii

1995-01-01

204

Legislative Effectiveness in Congress  

Microsoft Academic Search

We argue that congressional scholarship would benefit from an aggressive agenda to incorporate legislative effectiveness more fully into theoretical and empirical examinations of Congress. To facilitate this effort, we advance hypotheses from a foundational theory of lawmaking effectiveness that arises from members' innate abilities, cultivated skills, and institutional positioning. We develop a method for cardinally ranking members of the U.S.

Craig Volden; Alan E. Wiseman

205

effectively tax treaty?  

E-print Network

Is income effectively connected to US trade/ business? Is this exempt under the tax treaty? Does- employee comp? Is income "effectively connected"? Is payment subject to a lower tax rate? Is payment for rent or royalty? Individual completes IRS form 1001. Payment will not be taxed. (Code "N") Taxes

Krovi, Venkat

206

Gastrointestinal effects of aspirin  

Microsoft Academic Search

Aspirin is being used as an effective analgesic and anti-inflammatory agent at doses >325 mg daily. At low doses (75–325 mg daily), aspirin is the key antiplatelet drug in the pharmacological prevention of cardiovascular diseases. Topical and systemic effects of aspirin in the gastrointestinal mucosa are associated with mucosal damage in the upper and lower gastrointestinal tract. The risk of

Carlos Sostres; Angel Lanas

2011-01-01

207

Radiation effects in space  

SciTech Connect

As more people spend more time in space, and the return to the moon and exploratory missions are considered, the risks require continuing examination. The effects of microgravity and radiation are two potential risks in space. These risks increase with increasing mission duration. This document considers the risk of radiation effects in space workers and explorers. 17 refs., 1 fig., 4 tabs.

Fry, R.J.M.

1987-07-01

208

Primacy Effects in Attributions.  

ERIC Educational Resources Information Center

Previous research has suggested the existence of a primacy effect in the attribution of ability. To test if the primacy effect occurs in situations where specific cues about the person and nature of the test materials are lacking or greatly reduced, college students corrected a multiple-choice test in which a phantom stimulus person correctly…

McAndrew, Francis T.

209

Serious video game effectiveness  

Microsoft Academic Search

Given the interactive media characteristics and intrinsically motivating appeal, computer games are often praised for their potential and value in education. However, comprehensive research testing these assumptions is still missing. Preliminary comparative studies on the learning effects of games versus traditional media have shown some promise. In this paper, we describe a comparative study that thoroughly investigates the effects of

Wee Ling Wong; Cuihua Shen; Luciano Nocera; Eduardo Carriazo; Fei Tang; Shiyamvar Bugga; Harishkumar Narayanan; Hua Wang; Ute Ritterfeld

2007-01-01

210

Effective Mentoring Rebecca Vandiver  

E-print Network

Effective Mentoring Rebecca Vandiver 9 October 2006 #12;I. RESPONSIBILITIES OF A MENTOR #12;WHAT DOES IT MEAN TO BE A MENTOR?? · Mentors... ­ offer continuing guidance and support ­ are willing's performance "Effective mentoring can be learned, but not taught. Good mentors discover their own objectives

Lega, Joceline

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

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

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

Aharonov-Bohm Effect  

NSDL National Science Digital Library

This web page illustrates the effect of a magnetic flux on the interference of a quantum double-slit experiment. The time-dependent scattering patterns are shown with and without a magnetic field. In addition, the effects of changing the topology of the system are discussed and displayed. The webpage includes animations which demonstrate the concept.

De Raedt, Hans

215

Concerning Hertz' photoelectric effect  

E-print Network

Experimental evidence of the photoelectric effect goes back to H. Hertz. It occurred during the famous confirmation experiments of the Maxwellian theory. It is commonly held however that it cannot be explained in the framework of that theory. We are calling attention to some aspects linked with the interpretation of that effect on which, in our opinion, it is worthwhile reflecting.

S. L. Vesely; A. A. Vesely

2002-02-23

216

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

217

Teacher Work Group Effectiveness  

ERIC Educational Resources Information Center

Recent research links the development of a collaborative community of educators to enhanced teaching and learning effectiveness. This study contributes to this research by testing a work group effectiveness model with a sample of teachers from middle school teams. The study assesses the interrelationships among the model's antecedent variables…

Conley, Sharon; Fauske, Janice; Pounder, Diana G.

2004-01-01

218

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

219

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

220

The Kaye Effect  

ERIC Educational Resources Information Center

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…

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

2009-01-01

221

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.

222

Branch Effect Reduction Techniques  

Microsoft Academic Search

Branch effects are the biggest obstacle to gaining significant speedups when running general purpose code on instruction level parallel machines. The article presents a survey which compares current branch effect reduction techniques, offering hope for greater gains. We believe this survey is timely because research is bearing much fruit: speedups of 10 or more are being demonstrated in research simulations

Augustus K. Uht; Vijay Sindagi; Sajee Somanathan

1997-01-01

223

Generalized gravitomagnetic clock effect  

E-print Network

In General Relativity, the rotation of a gravitating body like the Earth influences the motion of orbiting test particles or satellites in a non-Newtonian way. This causes, e.g., a precession of the orbital plane known as the Lense-Thirring effect and a precession of the spin of a gyroscope known as the Schiff effect. Here, we discuss a third effect first introduced by Cohen and Mashhoon called the gravitomagnetic clock effect. It describes the difference in proper time of counterrevolving clocks after a revolution of $2\\pi$. For two clocks on counterrotating equatorial circular orbits around the Earth, the effect is about $10^{-7}$ seconds per revolution, which is quite large. We introduce a general relativistic definition of the gravitomagnetic clock effect which is valid for arbitrary pairs of orbits. This includes rotations in the same direction and different initial conditions, which are crucial if the effect can be detected with existing satellites or with payloads on nondedicated missions. We also derive the post-Newtonian expansion of the general relativistic expression and calculate the effect for the example of a satellite of a Global Navigation Satellite System compared to a geostationary satellite.

Eva Hackmann; Claus Lämmerzahl

2014-08-28

224

Generalized gravitomagnetic clock effect  

NASA Astrophysics Data System (ADS)

In general relativity, the rotation of a gravitating body like the Earth influences the motion of orbiting test particles or satellites in a non-Newtonian way. This causes, e.g., a precession of the orbital plane known as the Lense-Thirring effect and a precession of the spin of a gyroscope known as the Schiff effect. Here, we discuss a third effect first introduced by Cohen and Mashhoon called the gravitomagnetic clock effect. It describes the difference in proper time of counterrevolving clocks after a revolution of 2?. For two clocks on counterrotating equatorial circular orbits around the Earth, the effect is about 10-7 s per revolution, which is quite large. We introduce a general relativistic definition of the gravitomagnetic clock effect which is valid for arbitrary pairs of orbits. This includes rotations in the same direction and different initial conditions, which are crucial if the effect can be detected with existing satellites or with payloads on nondedicated missions. We also derive the post-Newtonian expansion of the general relativistic expression and calculate the effect for the example of a satellite of a global navigation satellite system compared to a geostationary satellite.

Hackmann, Eva; Lämmerzahl, Claus

2014-08-01

225

The precedence effect.  

PubMed

When two similar transient sounds are presented binaurally in rapid succession, observers hear a single sound from a location which depends mainly on the properties of the first sound to reach the ears. This phenomenon, known as the precedence effect, was explored using stimuli consisting of 20 mus pulses presented using earphones; experiments were carried out on both the classical precedence effect (in which interaural delays provide the cues to lateralization) and on an amplitude-based precedence effect, where interaural amplitude differences provide the cues. Some experiments on the amplitude-based precedence effect led to unexpected but highly consistent anomalous results. The spectral characteristics of stimuli used in studies of both the classical and amplitude-based precedence effect were considered and, provided the delay between the two pairs of pulses used in the experiments is 600 mus or less, observers' behaviour is simply related to the amplitude and phase spectra of the stimuli. PMID:6668254

Gaskell, H

1983-12-01

226

Greenhouse effect of NOX.  

PubMed

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 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 is estimated as GWP (NOX = 30 - 33 and 7 - 10 for the respective time horizons of 20 and 100 years, and is thereby comparable to that of methane. NOX emissions in rural areas of anthropogenically influenced regions, or those in the vicinity of the txopopause caused by air traffic, cause the greenhouse effectivity to be substantially more intense. We estimate an additional 5-23 % for Germany's contribution to the anthropogenic greenhouse effect as a result of the indirect greenhouse effects stemming from NOX. Furthermore, a small and still inaccurately defined amount of the deposited NOX which has primarily been converted into nitrates is again released from the soil into the atmosphere in the form of the long-lived greenhouse gas nitrous oxide (N2O). Thus, anthropogenically induced NOX emissions contribute to enhanced greenhouse effect and to stratospheric ozone depletion in the time scale of more than a century. PMID:24234471

Lammel, G; Graßl, H

1995-07-01

227

Hall effect in nanowires  

NASA Astrophysics Data System (ADS)

The classical Hall effect in thin semiconductor nanowires with lateral contacts is considered theoretically. Two new phenomena: (i) influence of diffusion currents in nanowires with radius comparable with the screening length of carriers and (ii) eddy currents in non-planar Hall contacts are taken into account. Both effects result in a noticeable reduction of the measured Hall voltage compared with the standard formula for bulk samples and hence the effective carrier concentration determined by using this formula may exceed the real concentration in nanowires in up to two orders of magnitude.

Fernandes, C.; Ruda, H. E.; Shik, A.

2014-06-01

228

Measuring Study Effectiveness  

NSDL National Science Digital Library

This model-eliciting activity challenges students to operationally define a construct (study effectiveness). Students are given a survey to review that rates different aspects of study behaviors. They are then given a set of data for a few students and asked to use their scores to determine an index of study effectiveness. After determining a method, they are then asked to use this index to put five students in rank order according to their scores on study effectiveness. Students write a report explaining the method they used to determine these scores and how they produced their ratings.

This page was authored by the CATALST Group at the University of Minnesota, based on an original activity by Richard Lesh at Purdue University.

229

Bustling argon: biological effect  

PubMed Central

Argon is a noble gas in group 18 of the periodic table. Certificated to exist in air atmosphere merely one century ago, discovery of argon shows interesting stories of researching and exploring. It was assumed to have no chemical activity. However, argon indeed present its biological effect on mammals. Narcotic effect of argon in diving operation and neur-protective function of argon in cerebral injury demonstrate that argon has crucial effect and be concentrated on is necessary. Furthermore, consider to be harmless to human, argon clinical application in therapy would be another option. PMID:24088583

2013-01-01

230

Finite Temperature Effective Actions  

E-print Network

We present, from first principles, a direct method for evaluating the exact fermion propagator in the presence of a general background field at finite temperature, which can be used to determine the finite temperature effective action for the system. As applications, we determine the complete one loop finite temperature effective actions for 0+1 dimensional QED as well as the Schwinger model. These effective actions, which are derived in the real time (closed time path) formalism, generate systematically all the Feynman amplitudes calculated in thermal perturbation theory and also show that the retarded (advanced) amplitudes vanish in these theories.

Ashok Das; J. Frenkel

2009-08-27

231

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

232

Conducting Effective Performance Evaluations  

E-print Network

Conducting Effective Performance Evaluations February 2013 #12;Performance Management v to prove that the employee did know the expectations and standards #12;Performance Evaluation Personnel your most talented employees · Satisfactory participation in the performance evaluation process

Lawrence, Rick L.

233

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

234

[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

235

Matthew: Effect or Fable?  

E-print Network

In a market context, a status effect occurs when actors are accorded differential recognition for their efforts depending on their location in a status ordering, holding constant the quality of these efforts. In practice, ...

Azoulay, Pierre

236

Creating effective character animation  

E-print Network

Several stages are involved in the creation of an graphics. effective, three-dimensional character animation. Before starting any work at the computer, the animator should consider what his characters will look like and how they will move, as well...

Gerwig, Jennifer

1999-01-01

237

Chesapeake Bay Impact Effects  

NSDL National Science Digital Library

This PowerPoint show depicts the effects (blast, heat, etc.) of the Chesapeake Bay impact. To emphasize the human consequences of asteroid and comet impacts, the slides show what would happen to East Coast communities if an identical object hit the same place today. (The impact actually happened roughly 35 million years ago.) Impact effects were estimated with the Earth Impact Effects Program (www.lpl.arizona.edu/impacteffects/). Effects shown on these slides are at best very approximate, and, consequently, these slides should only be used to stimulate discussions about impact hazards. Satellite images were obtained through the NASA Earth Observing System Higher Education Alliance (GeoBrain) which provided funding for this work. Graphics were created with the Environmental Systems Research Institute (ESRI) family of geographic information system (GIS) products.

Mark Abolins

238

Comparative effectiveness research.  

PubMed

The goal of comparative effectiveness research is to improve health care while dealing with the seemingly ever-rising cost. An understanding of comparative effectiveness research as a core topic is important for neuroradiologists. It can be used in a variety of ways. Its goal is to look at alternative methods of interacting with a clinical condition, ideally, while improving delivery of care. While the Patient-Centered Outcome Research initiative is the most mature US-based foray into comparative effectiveness research, it has been used more robustly in decision-making in other countries for quite some time. The National Institute for Health and Clinical Excellence of the United Kingdom is a noteworthy example of comparative effectiveness research in action. PMID:24874531

Hirsch, J A; Schaefer, P W; Romero, J M; Rabinov, J D; Sanelli, P C; Manchikanti, L

2014-09-01

239

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.

Amy Kolenbrander

2004-01-01

240

The Quadratic Zeeman Effect  

Microsoft Academic Search

The Zeeman effects of the principal series lines of sodium and potassium in the range n=10 to 35 are observed in absorption, using the new 60-inch cyclotron magnet. With a field of 27,000 gauss, the lines having n in the neighborhood of ten show a normal triplet representing the complete Paschen-Back effect of the narrow 2P doublet. From about n=12

F. A. Jenkins; E. Segrè

1939-01-01

241

Correlational effect size benchmarks.  

PubMed

Effect size information is essential for the scientific enterprise and plays an increasingly central role in the scientific process. We extracted 147,328 correlations and developed a hierarchical taxonomy of variables reported in Journal of Applied Psychology and Personnel Psychology from 1980 to 2010 to produce empirical effect size benchmarks at the omnibus level, for 20 common research domains, and for an even finer grained level of generality. Results indicate that the usual interpretation and classification of effect sizes as small, medium, and large bear almost no resemblance to findings in the field, because distributions of effect sizes exhibit tertile partitions at values approximately one-half to one-third those intuited by Cohen (1988). Our results offer information that can be used for research planning and design purposes, such as producing better informed non-nil hypotheses and estimating statistical power and planning sample size accordingly. We also offer information useful for understanding the relative importance of the effect sizes found in a particular study in relationship to others and which research domains have advanced more or less, given that larger effect sizes indicate a better understanding of a phenomenon. Also, our study offers information about research domains for which the investigation of moderating effects may be more fruitful and provide information that is likely to facilitate the implementation of Bayesian analysis. Finally, our study offers information that practitioners can use to evaluate the relative effectiveness of various types of interventions. (PsycINFO Database Record (c) 2015 APA, all rights reserved). PMID:25314367

Bosco, Frank A; Aguinis, Herman; Singh, Kulraj; Field, James G; Pierce, Charles A

2015-03-01

242

Gynaecologic effects of tamoxifen  

Microsoft Academic Search

Tamoxifen, an estrogen antagonist, is widely used as adjuvant therapy in patients with breast cancer. Its efficacy in increasing\\u000a survival and reducing recurrence rates has been demonstrated in several European and American studies. However, its effects\\u000a appear to be tissue specific. Tamoxifen exerts an estrogen effect (agonist) on the endometrium, myometrium and vagina. An\\u000a increase in uterine cancer has been

Dennis Yi-Shin Kuo; Carolyn D. Runowicz

1995-01-01

243

The Lisse effect revisited.  

PubMed

The Lisse effect is a rarely noted phenomenon occurring when infiltration caused by intense rain seals the surface soil layer to airflow, trapping air in the unsaturated zone. Compression of air by the advancing front results in a pressure increase that produces a water-level rise in an observation well screened below the water table that is several times as large as the distance penetrated by the wetting front. The effect is triggered by intense rains and results in a very rapid water-level rise, followed by a recession lasting a few days. The Lisse effect was first noted and explained by Thal Larsen in 1932 from water-level observations obtained in a shallow well in the village of Lisse, Holland. The original explanation does not account for the increased air pressure pushing up on the bottom of the wetting front. Analysis of the effect of this upward pressure indicates that a negative pressure head at the base of the wetting front, psi(f), analogous to that postulated by Green and Ampt (1911) to explain initially rapid infiltration rates into unsaturated soils, is involved in producing the Lisse effect. Analysis of recorded observations of the Lisse effect by Larsen and others indicates that the water-level rise, which typically ranges from 0.10 to 0.55 m, should be only slightly larger than psi(f) and that the depth of penetration of the wetting front is no more than several millimeters. PMID:12425353

Weeks, Edwin P

2002-01-01

244

Anomalous Skin Effect Igor Kaganovich  

E-print Network

Anomalous Skin Effect Revisited Igor Kaganovich Princeton Plasma Physics Laboratory #12 to explain "simply" anomalous skin effect without abusing physics. #12;3 Outline Skin effect (Inductively Coupled Plasmas/ Lasers) ­ Normal skin effect ­ Concept of phase-mixing and scale ­ Anomalous skin effect

Kaganovich, Igor

245

CAUSE & EFFECT What Is It?  

E-print Network

effect has Marcel Duchamp's Nude Descending A Staircase had on Western culture's understanding of what questions: Is there really a cause and effect relationship between these two events? If there really is a cause and effect relationship, what is the exact connection between the cause(s) and the effect(s)? What

Boonstra, Rudy

246

Intrauterine position effects.  

PubMed

A review of the literature suggests that individual variability in sex-related traits may be influenced by variations in hormonal exposure during fetal development. In litter-bearing mammals, fetuses develop in utero and may be subjected to differing hormonal environments based upon the sex of neighboring fetuses. Female fetuses developing between two males tend to show masculinized anatomical, physiological and behavioral traits as adults. Female fetuses developing without adjacent males, on the other hand, tend to show more feminized traits as adults. These traits include permanently altered hormone levels, reproductive organs, aggressive behaviors, secondary sex ratios and susceptibility to endocrine disruption. This intrauterine effect is due to the transfer of testosterone from male fetuses to adjacent fetuses. While these effects have been most clearly demonstrated in mice, other rodents and swine also show intrauterine position (IUP) effects. Some of these effects are similar to the influence of prenatal stress on adult phenotypes. A few reports on human twins suggest that variability in some masculine and feminine traits may be due to intrauterine hormonal signals. IUP effects may impact a number of scientific fields of research such as endocrine disruption, toxicology, population biology, animal production and health. PMID:12479841

Ryan, Bryce C; Vandenbergh, John G

2002-10-01

247

The real butterfly effect  

NASA Astrophysics Data System (ADS)

Historical evidence is reviewed to show that what Ed Lorenz meant by the iconic phrase ‘the butterfly effect’ is not at all captured by the notion of sensitive dependence on initial conditions in low-order chaos. Rather, as presented in his 1969 Tellus paper, Lorenz intended the phrase to describe the existence of an absolute finite-time predicability barrier in certain multi-scale fluid systems, implying a breakdown of continuous dependence on initial conditions for large enough forecast lead times. To distinguish from ‘mere’ sensitive dependence, the effect discussed in Lorenz's Tellus paper is referred to as ‘the real butterfly effect’. Theoretical evidence for such a predictability barrier in a fluid described by the three-dimensional Navier-Stokes equations is discussed. Whilst it is still an open question whether the Navier-Stokes equation has this property, evidence from both idealized atmospheric simulators and analysis of operational weather forecasts suggests that the real butterfly effect exists in an asymptotic sense, i.e. for initial-time atmospheric perturbations that are small in scale and amplitude compared with (weather) scales of interest, but still large in scale and amplitude compared with variability in the viscous subrange. Despite this, the real butterfly effect is an intermittent phenomenon in the atmosphere, and its presence can be signalled a priori, and hence mitigated, by ensemble forecast methods.

Palmer, T. N.; Döring, A.; Seregin, G.

2014-09-01

248

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.

249

The Quantum Sweeper Effect  

E-print Network

We show that during stochastic beam attenuation in double slit experiments, there appear unexpected new effects for transmission factors below $a\\lesssim10^{-4}$, which can eventually be observed with the aid of weak measurement techniques. These are denoted as quantum sweeper effects, which are characterized by the bunching together of low counting rate particles within very narrow spatial domains. We employ a "superclassical" modeling procedure which we have previously shown to produce predictions identical with those of standard quantum theory. Thus it is demonstrated that in reaching down to ever weaker channel intensities, the nonlinear nature of the probability density currents becomes ever more important. We finally show that the resulting unexpected effects nevertheless implicitly also exist in standard quantum mechanics.

Gerhard Groessing; Siegfried Fussy; Johannes Mesa Pascasio; Herbert Schwabl

2015-02-13

250

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

251

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

252

The Mozart Effect.  

PubMed

This review deals with the Mozart Effect, an improvement of performance while listening to Mozart music. Previous studies have shown improved spatial temporal reasoning and improved IQ test results and neurophysiological changes, mainly increased coherence among different groups of subjects. This review emphasizes the effect on epileptiform patterns, both generalized and focal; provides an example of a chronic effect over a period of 1-2 days; addresses the distinctive aspects of the music to account for this phenomenon and shows that long-term periodicity in the power of the music is a special quality; and deals with the melodic line and shows that Mozart repeats the melodic line much more frequently than other well-known composers. It is likely that the superorganization of the cerebral cortex resonates with great organization found in Mozart music. PMID:12609277

Hughes, John R.

2001-10-01

253

Stormwater BMP Effectiveness Assessment Toolkit  

EPA Science Inventory

US EPA has identified stormwater BMP effectiveness as a priority research need. Effective protection of biotic integrity requires that processes maintaining the diversity of physical habitats be protected. Methods are needed to evaluate the effectiveness of existing Stormwater ...

254

Nonprofit Organizational Effectiveness: Contrasts Between Especially Effective and Less Effective Organizations  

Microsoft Academic Search

How do key stakeholders of nonprofit organizations (NPOs) judge the effectiveness of their organization? Are the judgments of stake- holders similar, and how are board effectiveness and the use of practitioner-identified correct management procedures related to judgments of effectiveness? This study focuses on a subset of espe- cially effective and less effective NPOs from a larger sample and finds that

Robert D. Herman; David O. Renz

1998-01-01

255

Habituation of reinforcer effectiveness  

PubMed Central

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

256

Effective Temperature of Mutations  

NASA Astrophysics Data System (ADS)

Biological macromolecules experience two seemingly very different types of noise acting on different time scales: (i) point mutations corresponding to changes in molecular sequence and (ii) thermal fluctuations. Examining the secondary structures of a large number of microRNA precursor sequences and model lattice proteins, we show that the effects of single point mutations are statistically indistinguishable from those of an increase in temperature by a few tens of kelvins. The existence of such an effective mutational temperature establishes a quantitative connection between robustness to genetic (mutational) and environmental (thermal) perturbations.

Derényi, Imre; Szöll?si, Gergely J.

2015-02-01

257

Anticancer effects of fucoidan.  

PubMed

Recently, there has been an increased interest in the pharmacologically active natural compounds isolated and used for remedies of various kinds of diseases, including cancer. The great deal of interest has been developed to isolate bioactive compounds from marine resources because of their numerous health beneficial effects. Among marine resources, marine algae are valuable sources of structurally diverse bioactive compounds. Fucoidan is a sulfated polysaccharide derived from brown seaweeds and has been used as an ingredient in some dietary supplement products. Fucoidan has various biological activities including antibacterial, antioxidant, anti-inflammatory, anticoagulant, and antitumor activities. So this chapter deals with anticancer effects of fucoidan. PMID:25081084

Senthilkumar, Kalimuthu; Kim, Se-Kwon

2014-01-01

258

Contamination effects study  

NASA Technical Reports Server (NTRS)

The in-situ optical surface measurement system is a facility designed to study the deleterious effects of particulate materials on the surface reflectivities of optical materials in the vacuum ultraviolet (VUV). This arrangement is designed to simulate the on-orbit effects of contamination and degradation of optical surfaces. This simulation is accomplished through the use of non-coherent VUV sources illuminating optical surfaces located in a high vacuum chamber. Several sources of contamination are employed. The reflectivity is measured both at the specular reflection as well as at two scattered positions, forward and reverse. The system components are described and an operating procedure is given.

1988-01-01

259

Quantum Spin Hall Effect  

SciTech Connect

The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of 2 e/4{pi}. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.

Bernevig, B.Andrei; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

2010-01-15

260

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....

261

Microcircuit radiation effects databank  

NASA Technical Reports Server (NTRS)

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 event upset cross sections, i.e., the probability of a soft error (bit flip) or of a hard error (latchup) are presented.

1983-01-01

262

Conducting Effective Performance Evaluations  

E-print Network

Conducting Effective Performance Evaluations · February 13, 2012 · March 9, 2012 #12 with the ability to prove that the employee did know the expectations and standards #12;Performance Evaluation Practice · An annual performance evaluation is required for classified and contract professional employees

Dyer, Bill

263

Reporting Research Results Effectively  

ERIC Educational Resources Information Center

Assessment research is at its best when it packages research results and data so that they can be digested by multiple audiences. Too many assessment researchers spend all their efforts planning and executing the research project with little attention to closing the loop at the end. If assessment findings are not communicated effectively, the…

Volkwein, J. Fredericks

2010-01-01

264

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. PMID:22701844

Gupta, Vishal

2012-01-01

265

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

266

Effective 4-H Meetings  

E-print Network

are needed and their effects on their health. ? Use a variety of teaching techniques. In a meeting related to pet grooming and hygiene for example, provide several ways of learning by showing the tools to be used, discussing them, demonstrating them...

Howard, Jeff W.

2005-05-10

267

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

268

Effects of Acid Rain  

NSDL National Science Digital Library

This portal provides links to information on the potential damage caused to the environment by acid rain. An introductory paragraph briefly describes the damage to lakes and streams, building materials, and monuments. Each link access additional information on these topics: surface waters and aquatic animals, forests, automotive coatings, soluble building materials such as marble or limestone, atmospheric haze, and human health effects.

269

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

270

Effective management of ARDS.  

PubMed

Acute respiratory distress syndrome is a serious complication of critical illness that is associated with high morbidity and mortality. There are no effective treatment options, so prevention, early recognition, and appropriate supportive care are essential to improve outcomes. This article provides an overview of the disorder, including current treatment considerations. PMID:25299354

Carlucci, Melissa; Graf, Nicole; Simmons, James Q; Corbridge, Susan J

2014-12-13

271

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.

2014-09-18

272

Longitudinal Effects of Kindergarten.  

ERIC Educational Resources Information Center

Examined longitudinal effects of kindergarten attendance on academic achievement through high school with students who attended public or nonpublic kindergarten, or neither one. Found that students with either kind of kindergarten experience had higher ACT scores and grade point averages. Found no significant differences in number of students…

Prince, Debra Lindsey; Hare, R. Dwight; Howard, Esther M.

2001-01-01

273

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.

274

Wood Quality: The Effects  

E-print Network

Particle and Fiber Energy Veneer Lumber Posts & PolesRound wood Heat Chemicals $ $$$ #12;Mix High & Low to considerOther things to consider................ Stability: height/diameter ratios lower through reduced thinning can be expected to effectively lower future ratios Wilson and Oliver 2000 #12;ThinningThinning #12

275

The supergreenhouse effect  

NASA Astrophysics Data System (ADS)

Although the greenhouse effect as it applies to explain the Earth's climate system is understood, there are aspects of the effect that require further study. In particular, the character of change in emission of radiation to space in a warming atmosphere and its relation to surface temperature is a key component of the greenhouse effect and related feedbacks. Over most of the planet, the emission systematically increase with increasing surface temperature indicating the important function of the emission to space in removing heat from the warming Earth. In some regions of the planet, the emission decreases with increasing temperature. These are the so-called super-greenhouse regions of the planet and if left alone, these regions would produce a localized runaway warming. Using global observations extracted from the A-train satellites, the properties of these supergreenhouse regions will be reviewed and the factors that control them explained. A glimpse at how these regions evolve in a warming world based on CMIP5 results will be presented and the broader implication of the supergreenhouse effect will be underlined.

Stephens, G. L.; Kahn, B. H.

2012-12-01

276

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

277

Building Effective Afterschool Programs.  

ERIC Educational Resources Information Center

Through a comprehensive review of various afterschool programs across the United States, this resource provides a practical overview of the research and best practices that can be easily adapted and applied in the development of highly effective afterschool programs. chapters focus on: (1) "Why Afterschool Programs?" (benefits, challenges, and…

Fashola, Olatokunbo S.

278

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

279

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. PMID:2686174

Davidson, D M

1989-01-01

280

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

281

Creating Effective Multimedia Instruction.  

ERIC Educational Resources Information Center

Presents information on several critical themes related to multimedia instruction for those involved in the design, development, or use of computer delivered instruction. Addresses software product life cycle; systematic approach to design; multimedia design and development teams; production values; critical components of effective multimedia;…

Sales, Gregory C.

1999-01-01

282

Effects of Induced Astigmatism.  

ERIC Educational Resources Information Center

The relationship of astigmatism to reading and the possible detrimental effects it might have on reading were investigated. The greatest incidence of astigmatism was for the with-the-rule type ranging from .50 to 1.00 diopter. This type of astigmatism was induced in 35 seniors from the Los Angeles College of Optometry by placing cylindrical lenses…

Schubert, Delwyn G.; Walton, Howard N.

1968-01-01

283

Earth Impacts Effects Program  

NSDL National Science Digital Library

This interactive web site estimates the regional environmental consequences of an impact on Earth. The program will estimate the ejecta distribution, ground shaking, atmospheric blast wave, and thermal effects of an impact as well as the size of the crater produced.

Robert Marcus

284

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

285

Developing Effective Training Programs.  

ERIC Educational Resources Information Center

Focusing on research administrators, discusses how an effective training program improves employee performance by including comprehensive needs assessment, employing appropriate training methodologies, and anticipating factors beyond the actual training event that influence the transfer of skills from the training environment to the work…

Wagonhurst, Carole

2002-01-01

286

Fast and effective?  

PubMed

The 5.2 diet involves two days of fasting each week. It is being promoted as the key to sustained weight loss, as well as wider health benefits, despite the lack of evidence on the long-term effects. Nurses need to support patients who wish to try intermittent fasting. PMID:24345130

Trueland, Jennifer

2013-12-18

287

Effective Staff Development.  

ERIC Educational Resources Information Center

Beginning with the observation that educators are faced with rising public expectations, declining resources, and increased public criticism, this paper describes a six-fold model for determining how staff development is operating and how it can be made to operate more effectively, in a self-renewing manner. The six dimensions consist of the…

Bush, Robert N.

288

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...

289

Effective Online Privacy Policies  

Microsoft Academic Search

Online privacy policies are important mechanisms for informing web site users about the level of information privacy protection afforded when visiting web sites. To date, societal mechanisms and technologies have been the focus of attempts to improve the quality and effectiveness of online privacy policies. Little attention, however, has been given to the development and use of organisational measures for

Sharman Lichtenstein; Paula M C Swatman; Kanchan Babu

290

Class Effects in ATI's.  

ERIC Educational Resources Information Center

Selected results from an aptitude-treatment interaction (ATI) study illustrate the importance of including class analyses in ATI research. The interactive effects of motivational aptitude (including locus of control, academic self confidence, and interests) and cognitive aptitude (as measured by a learning task and the Lorge-Thorndike verbal and…

Greene, Jennifer C.

291

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...

292

The quadratic Zeeman effect  

Microsoft Academic Search

The hydrogen-atom quadratic Zeeman effect is treated by several techniques, and a new perturbation approach is suggested which involves numerical solution of a radial equation based on the s part of the potential. The low-field results appear to be more accurate than those of previous workers.

J. Killingbeck

1979-01-01

293

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

294

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...

295

The Surface Photoelectric Effect  

Microsoft Academic Search

The probability of ejection of an electron in the surface photo-effect is expressed in terms of a function of the potential barrier, the energy of the electron after ejection, and the frequency. This function is dominated, for low energies of ejection, by the transmission coefficient of the surface. It is then assumed that the function can be expanded in a

W. V. Houston

1937-01-01

296

Measuring Teacher Effectiveness  

ERIC Educational Resources Information Center

Prior research has shown that there is a correlation between teacher characteristics (e.g., pedagogical knowledge, teacher preparation/certification) and student achievement. Current political contexts call for the utilization of student achievement data to measure the effectiveness of our education systems. A solid research base of how teacher…

Jacobo, Amber Leann

2012-01-01

297

Designing Effective Posters  

NSDL National Science Digital Library

This website presents an online tutorial about creating effective poster presentations. The site guides users through the basics of poster design, which should free the presenter to focus on discussion of essential elements of the work. Decisions about poster format and design which contribute to efficient and accurate transfer of information using this medium are also discussed.

Jeff Radel

298

test collection retrieval effectiveness  

E-print Network

and provide means, in the form of a large XML test collection and appropriate scoring methodsINEX evaluation test collection retrieval effectiveness The INEX Evaluation Initiative Gabriella increases, so is the need to assess their benefit to users. The benefit to a given user depends largely

Lalmas, Mounia

299

Cutaneous Effects of Smoking  

Microsoft Academic Search

Background: Cigarette smoking is the single biggest preventable cause of death and disability in developed countries and is a significant public health concern. While known to be strongly associated with a number of cardiovascular and pulmonary diseases and cancers, smoking also leads to a variety of cutaneous manifestations. Objective: This article reviews the effects of cigarette smoking on the skin

Anatoli Freiman; Garrett Bird; Andrei I. Metelitsa; Benjamin Barankin; Gilles J. Lauzon

2004-01-01

300

Marijuana: respiratory tract effects.  

PubMed

Marijuana is the most commonly used drug of abuse in the USA. It is commonly abused through inhalation and therefore has effects on the lung that are similar to tobacco smoke, including increased cough, sputum production, hyperinflation, and upper lobe emphysematous changes. However, at this time, it does not appear that marijuana smoke contributes to the development of chronic obstructive pulmonary disease. Marijuana can have multiple physiologic effects such as tachycardia, peripheral vasodilatation, behavioral and emotional changes, and possible prolonged cognitive impairment. The carcinogenic effects of marijuana are unclear at this time. Studies are mixed on the ability of marijuana smoke to increase the risk for head and neck squamous cell carcinoma, lung cancer, prostate cancer, and cervical cancer. Some studies show that marijuana is protective for development of malignancy. Marijuana smoke has been shown to have an inhibitory effect on the immune system. Components of cannabis are under investigation as treatment for autoimmune diseases and malignancy. As marijuana becomes legalized in many states for medical and recreational use, other forms of tetrahydrocannabinol (THC) have been developed, such as food products and beverages. As most research on marijuana at this time has been on whole marijuana smoke, rather than THC, it is difficult to determine if the currently available data is applicable to these newer products. PMID:23715638

Owen, Kelly P; Sutter, Mark E; Albertson, Timothy E

2014-02-01

301

Anticancer effects of phytosterols  

Microsoft Academic Search

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

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

2009-01-01

302

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.

Dr. Michael Cross, Cal Tech

303

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.

304

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

305

Ecotoxicological effects at contaminated sites  

Microsoft Academic Search

Contamination sites pose significant environmental hazards for terrestrial and aquatic ecosystems. They are important sources of pollution and may result in ecotoxicological effects on terrestrial, groundwater and aquatic ecosystems. At severely contaminated sites, acute effects occur, but the core problem lies in long-term chronic effects. Ecotoxicological effects occur at all levels of biological organization, from the molecular to the ecosystem

Karl Fent

2004-01-01

306

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

307

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); Werner, Paul W. (Albuquerque, NM)

2004-08-24

308

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. PMID:21057602

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

2010-01-01

309

Neuroprotective effects of creatine.  

PubMed

There is a substantial body of literature, which has demonstrated that creatine has neuroprotective effects both in vitro and in vivo. Creatine can protect against excitotoxicity as well as against ?-amyloid toxicity in vitro. We carried out studies examining the efficacy of creatine as a neuroprotective agent in vivo. We demonstrated that creatine can protect against excitotoxic lesions produced by N-methyl-D: -aspartate. We also showed that creatine is neuroprotective against lesions produced by the toxins malonate and 3-nitropropionic acid (3-NP) which are reversible and irreversible inhibitors of succinate dehydrogenase, respectively. Creatine produced dose-dependent neuroprotective effects against MPTP toxicity reducing the loss of dopamine within the striatum and the loss of dopaminergic neurons in the substantia nigra. We carried out a number of studies of the neuroprotective effects of creatine in transgenic mouse models of neurodegenerative diseases. We demonstrated that creatine produced an extension of survival, improved motor performance, and a reduction in loss of motor neurons in a transgenic mouse model of amyotrophic lateral sclerosis (ALS). Creatine produced an extension of survival, as well as improved motor function, and a reduction in striatal atrophy in the R6/2 and the N-171-82Q transgenic mouse models of Huntington's disease (HD), even when its administration was delayed until the onset of disease symptoms. We recently examined the neuroprotective effects of a combination of coenzyme Q10 (CoQ10) with creatine against both MPTP and 3-NP toxicity. We found that the combination of CoQ and creatine together produced additive neuroprotective effects in a chronic MPTP model, and it blocked the development of alpha-synuclein aggregates. In the 3-NP model of HD, CoQ and creatine produced additive neuroprotective effects against the size of the striatal lesions. In the R6/2 transgenic mouse model of HD, the combination of CoQ and creatine produced additive effects on improving survival. Creatine may stabilize mitochondrial creatine kinase, and prevent activation of the mitochondrial permeability transition. Creatine, however, was still neuroprotective in mice, which were deficient in mitochondrial creatine kinase. Administration of creatine increases the brain levels of creatine and phosphocreatine. Due to its neuroprotective effects, creatine is now in clinical trials for the treatment of Parkinson's disease (PD) and HD. A phase 2 futility trial in PD showed approximately a 50% improvement in Unified Parkinson's Disease Rating Scale at one year, and the compound was judged to be non futile. Creatine is now in a phase III clinical trial being carried out by the NET PD consortium. Creatine reduced plasma levels of 8-hydroxy-2-deoxyguanosine in HD patients phase II trial and was well-tolerated. Creatine is now being studied in a phase III clinical trial in HD, the CREST trial. Creatine, therefore, shows great promise in the treatment of a variety of neurodegenerative diseases. PMID:21448659

Beal, M Flint

2011-05-01

310

Safety Intervention Effectiveness  

SciTech Connect

Judging safety intervention effectiveness is often left up to the eye of the beholder. Safety and Health Professionals must increase skills and increase their body of knowledge, based on scientific evidence, that can be applied confidently in the workplace. Evidence must be collected and analyzed to separate the interventions of the month with those that stand the test of time. The book Guide to Evaluating the Effectiveness of Strategies for Preventing Work injuries DHHS (NIOSH) Publication No. 2001-119, April 2001, serves as a primary reference. An example study related to biorhythms, popular in the late 1970s, is used to illustrate the separating of scientific evidence and pseudo-science hype. The cited biorhythm study focuses on the relationship of the accident dates and the three biorhythmic cycles (physical, emotional, and intelligence).

ZIMMERMAN, R.O.

2001-10-16

311

Relativistic Hall Effect  

NASA Astrophysics Data System (ADS)

We consider the relativistic deformation of quantum waves and mechanical bodies carrying intrinsic angular momentum (AM). When observed in a moving reference frame, the centroid of the object undergoes an AM-dependent transverse shift. This is the relativistic analogue of the spin-Hall effect, which occurs in free space without any external fields. Remarkably, the shifts of the geometric and energy centroids differ by a factor of 2, and both centroids are crucial for the Lorentz transformations of the AM tensor. We examine manifestations of the relativistic Hall effect in quantum vortices and mechanical flywheels and also discuss various fundamental aspects of this phenomenon. The perfect agreement of quantum and relativistic approaches allows applications at strikingly different scales, from elementary spinning particles, through classical light, to rotating black holes.

Bliokh, Konstantin Y.; Nori, Franco

2012-03-01

312

Lightning Physics and Effects  

NASA Astrophysics Data System (ADS)

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 lightning with a variety of objects and systems as well as the environment. The style of writing is well within the ability of the technical non-expert and anyone interested in lightning and its effects. Potential readers will include physicists; engineers working in the power industry, communications, computer, and aviation industries; atmospheric scientists; geophysicists; meteorologists; atmospheric chemists; foresters; ecologists; physicians working in the area of electrical trauma; and, lastly, architects. This comprehensive reference volume contains over 300 illustrations, 70 tables with quantitative information, and over 6000 reference and bibliography entries.

Orville, Richard E.

2004-03-01

313

Measuring marketing effectiveness.  

PubMed

The most frequent question about the marketing function in hospitals today is, What are we getting for our money? To answer this, marketing directors must convince the board first of the need for marketing, then of marketing's effectiveness. To measure marketing effectiveness, some basic needs are a staff, equipment, cooperation between departments, utilization data, and a research budget. Some steps to be followed include developing a marketing data base--consisting of demographic projections, demand projections, and market share--testing a marketing strategy through experimentation, documenting the expected results and measurement techniques, and calculating the expected return on investments. In dealing with those "impossible-to-measure" cases, such as a physician who is not advertising but finds that a competitor is, a decision tree can help determine whether to advertise and how much to spend by indicating what the return on investment might be. PMID:10312197

Gluckman, J; Michaelis, T

1987-09-01

314

The reverse Stroop effect.  

PubMed

In classic Stroop interference, manual or oral identification of sensory colors presented as incongruent color words is delayed relative to simple color naming. In the experiment reported here, this effect was shown to all but disappear when the response was simply to point to a matching patch of color. Conversely, strong reverse Stroop interference occurred with the pointing task. That is, when the sensory color of a color word was incongruent with that word, responses to color words were delayed by an average of 69 msec relative to a word presented in gray. Thus, incongruently colored words interfere strongly with pointing to a color patch named by the words, but little interference from incongruent color words is found when the goal is to match the color of the word. These results suggest that Stroop effects arise from response compatibility of irrelevant information rather than automatic processing or habit strength. PMID:10780025

Durgin, F H

2000-03-01

315

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

316

Estimating Absolute Site Effects  

SciTech Connect

The authors use previously determined direct-wave attenuation functions as well as stable, coda-derived source excitation spectra to isolate the absolute S-wave site effect for the horizontal and vertical components of weak ground motion. They used selected stations in the seismic network of the eastern Alps, and find the following: (1) all ''hard rock'' sites exhibited deamplification phenomena due to absorption at frequencies ranging between 0.5 and 12 Hz (the available bandwidth), on both the horizontal and vertical components; (2) ''hard rock'' site transfer functions showed large variability at high-frequency; (3) vertical-motion site transfer functions show strong frequency-dependence, and (4) H/V spectral ratios do not reproduce the characteristics of the true horizontal site transfer functions; (5) traditional, relative site terms obtained by using reference ''rock sites'' can be misleading in inferring the behaviors of true site transfer functions, since most rock sites have non-flat responses due to shallow heterogeneities resulting from varying degrees of weathering. They also use their stable source spectra to estimate total radiated seismic energy and compare against previous results. they find that the earthquakes in this region exhibit non-constant dynamic stress drop scaling which gives further support for a fundamental difference in rupture dynamics between small and large earthquakes. To correct the vertical and horizontal S-wave spectra for attenuation, they used detailed regional attenuation functions derived by Malagnini et al. (2002) who determined frequency-dependent geometrical spreading and Q for the region. These corrections account for the gross path effects (i.e., all distance-dependent effects), although the source and site effects are still present in the distance-corrected spectra. The main goal of this study is to isolate the absolute site effect (as a function of frequency) by removing the source spectrum (moment-rate spectrum) from the distance-corrected S-wave spectra. Typically, removing the S-wave source spectrum is difficult because of inadequate corrections for the source radiation pattern, directivity and random interference. In addition to complexities near the source, 2-D and 3-D structure beneath the recording site will result in an azimuth-dependent site effect. Since the direct wave only samples a narrow range in take-off and back-azimuth angles, multi-station averaging is needed to minimize the inherent scatter. To minimize these complicating effects, they apply the coda methodology outlined by Mayeda et al., (2003) to obtain stable moment-rate spectra. This methodology provides source amplitude and derived source spectra that are a factor of 3-to-4 times more stable than those derived from direct waves. Since the coda is commonly thought of as scattered energy that samples all ray parameters and back-azimuths, it is not very sensitive to the source radiation pattern and 3-D structure. This property makes it an excellent choice for use in obtaining average properties of the source, site and path effects in a region. Due to the characteristics of the techniques used in this study, all the inverted quantities are azimuthally averaged, since the aximuthal information is lost in the processing.

Malagnini, L; Mayeda, K M; Akinci, A; Bragato, P L

2004-07-15

317

Ocular effects of adrenomedullin.  

PubMed

The purpose of this study was to determine the expression and effects of adrenomedullin (AM), a novel vasodilator peptide, in the eye. Expression of AM mRNA was examined in the rat iris-ciliary body using reverse transcription-polymerase chain reaction (RT-PCR). In rabbits, intraocular pressure (IOP) was measured periodically after intravitreal injection (20 microl) of AM (10(-7)-10(-4)m) into one eye. In separate groups of rabbits, 30 min after intravitreal injection of either AM-(22-52) (10(-3)m), a specific AM receptor antagonist, or CGRP-(8-37) (10(-3)m), a CGRP1 receptor antagonist, into one eye, AM (10(-6)m) was injected into both eyes, and IOP was measured. Using different rabbits, aqueous protein and cAMP concentrations were determined 6 hr after injection of AM. Expression of AM mRNA was detected in the rat iris-ciliary body. In rabbits, intravitreally administered AM (10(-6)-10(-4)m) profoundly lowered IOP, and the maximum effect was observed at 4-8 h. The ocular hypotensive effect of AM was dose-dependent (10(-7)-10(-4)m). Pretreatment with CGRP-(8-37) did not significantly inhibit the ocular hypotensive effect of AM (10(-6)m), whereas pretreatment with AM-(22-52) completely abolished it. AM (10(-6)m) did not significantly affect aqueous protein concentration. The higher dose of AM (10(-5)m) induced a significant increase in aqueous protein, which was not associated with an increase in the aqueous cAMP content and was significantly inhibited by AM-(22-52) and CGRP-(8-37). These results demonstrate that AM is expressed in the iris-ciliary body and decreases IOP mainly via specific AM receptors, and suggest that AM may play a role in controlling IOP. PMID:10548466

Taniguchi, T; Kawase, K; Gu, Z B; Kimura, M; Okano, Y; Kawakami, H; Tsuji, A; Kitazawa, Y

1999-11-01

318

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

319

Geomorphically effective floods  

NASA Astrophysics Data System (ADS)

Investigations of the hydrology and geomorphology of recent floods from the rapid failure of two small upland dams document the unusually large peak boundary shear stress and peak stream power per unit area for each flood. Downstream consequences to alluvial channels and floodplains, however, were minimal. Lack of geomorphic change is attributed to the short duration of the floods, which lasted about six and sixteen minutes each. Distribution of stream power over hydrographs of eight exceptional floods is constructed from channel geometry, discharge rating curves, and flood hydrographs; the resulting curve is defined as a stream-power graph. A stream-power graph gives a better portrayal of the potential for a flood to be geomorphically effective than simple statements of flow magnitude. From stream-power graphs, total energy expended over a flood hydrograph can be computed. Total flood energy may not be a sensitive measure of geomorphic effectiveness without consideration of channel and floodplain resistance. A conceptual model combining flow duration, peak stream power per unit area, flood energy, and alluvial and bedrock thresholds may represent the effectiveness of floods and can distinguish among such cases as (a) floods of long duration, moderate to large energy expenditure, but low peak stream power per unit area. These floods are ineffective in causing significant landform changes in alluvial or bedrock channels; (b) floods of medium to long duration, with medium to large total energy expenditure, and large peak stream power per unit area. These are believed to be the most effective geomorphic floods in any kind of channel because of the optimal combination of peak flood power, duration, and total energy expenditure; and (c) floods of very short duration, low total energy expenditure, but large peak stream power. These floods are also ineffective agents of geomorphic change in spite of record values of peak stream power per unit area because of their short duration, and resulting low energy expenditures.

Costa, John E.; O'Connor, Jim E.

320

Magnetic effects on thermocouples  

NASA Astrophysics Data System (ADS)

Thermometers in laboratory environment and industrial applications are often subject to extraneous, usually unwanted and uncontrolled magnetic fields. Magnetic field influence can be minimized, but cannot be fully cancelled out. Even more, in most cases, there is no awareness of the existence of magnetic fields, let alone their effect on measurement instrumentation. In the past, sensitivity to high dc magnetic fields has been investigated in cryogenics and at high temperatures. More recently, the magnetic effect on weak dc magnetic fields was presented. The goal of this paper was to analyse and empirically and experimentally prove the magnetic sensitivity of thermocouples exposed to low magnetic fields: both dc and ac. Precision and uniform alternating and direct magnetic flux densities were generated by means of permanent magnets and power amplifiers with air-cored coils. The magnetic effect on ferromagnetic and non-ferromagnetic thermocouples at liquid-nitrogen-boiling point (-196 °C), ice point (0 °C), in water (17 °C) and at melting point of gallium fixed point cell (29.7646 °C) was investigated. Magnetic-field-dependent temperature errors of up to 700 mK (at 5.3 mT: dc) and up to 1 °C (at 10 mT: ac 50 Hz magnetic fields) were detected. From the results, it can be concluded that, ideally for temperature measurements of the highest accuracy in the above-cryogenic temperature range, magnetic sensitivity should be estimated and taken into account either as the correction of an error and/or as an additional source of measurement uncertainty. Special consideration should be given to thermocouple orientation relative to the magnetic field direction, influence of metal enclosures and magnetization effects on ferromagnetic components of thermocouples.

Beguš, Samo; Bojkovski, Jovan; Drnovšek, Janko; Geršak, Gregor

2014-03-01

321

Designing effective instruction  

Microsoft Academic Search

Summary  We have usedDesigning Effective Instruction in introductory ID courses and experienced its use from both the instructors' and the learners' perspective. Our overall\\u000a conclusion is that it is highly usable and accessible to beginning ID students, including those whose first language may not\\u000a be English. The ID model presented is clear and the focus on the learner throughout is appropriate

Gary J. Anglin; Steven M. Ross; Jerrold E. Kemp

2002-01-01

322

Hall Effect Measurements  

NSDL National Science Digital Library

The objective of this Web site is twofold: (1) to describe the Hall measurement technique for determining the carrier density and mobility in semiconductor materials and (2) to initiate an electronic interaction forum where workers interested in the Hall effect can exchange ideas and information. It includes an introductory description of the Hall measurement technique and covers basic principles, equipment, and recommended procedures. Keywords: Conductance, conductivity, resistance, resistivity

323

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.

2014-09-14

324

Effects on Development  

Microsoft Academic Search

This chapter will review the effects produced on neural development by maternal consumption of cannabinoids during gestation\\u000a and lactation, with emphasis in thematuration of several neurotransmitter systems (dopamine, serotonin, opioids, cannabinoids,\\u000a etc.) and possible modifications in their functional expression at the behavioral or neuroendocrine levels. In addition, we\\u000a have analyzed the possible existence of a sexual dimorphism in these ontogenic

J. A. Ramos; M. Gómez; R. de Miguel

325

Dark Matter Effective Theory  

E-print Network

We organize the effective (self)interaction terms for complex scalar dark matter candidates which are either an isosinglet, isodoublet or an isotriplet with respect to the weak interactions. The classification has been performed ordering the operators in inverse powers of the dark matter cutoff scale. We assume Lorentz invariance, color and charge neutrality. We also introduce potentially interesting dark matter induced flavor-changing operators. Our general framework allows for model independent investigations of dark matter properties.

Eugenio Del Nobile; Francesco Sannino

2012-04-18

326

Pulsed DF laser effects  

Microsoft Academic Search

Laser effects caused by pulsed DF laser beams have been investigated under one-dimensional plasma conditions. The high energy pulse from a 50-liter photoinitiated chemical laser was utilized to measure both metal and fiberglass target responses to incident fluences up to 150 J\\/sq cm. In thermal coupling experiments with aluminum, the absorbed fluence showed enhancement just above the plasma threshold, reaching

W. E. Maher; R. B. Hall

1981-01-01

327

Side effects of benoxaprofen  

Microsoft Academic Search

A study was made of adverse dermatological reactions to the non-steroidal anti-inflammatory agent benoxaprofen. Photosensitivity was seen in several patients, confined to wavelengths less than 340 nm. Other cutaneous side effects were erythema multiforme, the Stevens-Johnson syndrome, milia, and onycholysis. One case of pancytopenia and toxic epidermal necrolysis was reported. patients were not rechallenged with the drug, but these reactions

Brian Diffey; Colin Hindson; F Lawlor

1982-01-01

328

[Bactericidal effect of lysozyme].  

PubMed

Isolation of lysozyme from hemolymph of Alveonasus lahorensis (Acari: Parasitiformes, Argasidae) and Hyalomma marginatum (Acari: Parasitiformes, Ixodidae) with using ultrasound is described. It was shown that the bactericidal effect of the ultrasound-extracted lysozyme against Staphylococcus aureus and Micrococcus luteus significantly exceeded that of the chicken egg lysozyme and lysozyme from ticks without ultrasound exposure. Disintegration of the hemolymph cells increased lysozyme production. PMID:24640148

Podborodov, V M; Shchelkanov, M Iu; Smirnova, I P; Burenkova, L A; Novikova, V P; Aristova, V A; Novikova, E L; Moskvitina, G G; Ioffe, A M

2013-01-01

329

Identifying Effective School Principals  

E-print Network

focus on three dimensions: student performance, teacher retention, and financial management. Data is derived from the Texas Education Agency (TEA) to develop a total of seven specific indicators to measure success in these three areas for Texas... tests and school accountability ratings. TEA data is used from 1996-2005 to develop indicators for these two measures. Since our goal was to capture the improvements in student performance attributable to principal effectiveness, we used a value...

Fernandez, Kandyce; Flores, Santa; Huang, Emily; Igwe, Carolyn; McDonald, Leslie; Stroud, Ryan; Willis, Rebecca; Dugat, Amber

2007-01-01

330

Interpersonal effectiveness training  

E-print Network

of the individual 's daily activities and encounters with his or her spouse. The frequency of occurrence of the six behaviors were analyzed by a 6 x 7 x 4 factorial repeated measures ANOVA. This analysis revealed a significant main effect of questions (y&. 01... & Siegel, 1973; Mix, 1972; Navran, 1967; Pearce, 1973; Raush, Barry, Hertel 8 Swaim, 1974; Tubbs 8 Moss, 1974; Watzlawick, Beavin & Jackson, 1967; Wicks, 1973). A person's concept of himself and others partially determines his behavior. Bienvenu (1971...

DeOtte, Dona Lou Lewis

1976-01-01

331

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.

332

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

333

Estimating Absolute Site Effects  

Microsoft Academic Search

The authors use previously determined direct-wave attenuation functions as well as stable, coda-derived source excitation spectra to isolate the absolute S-wave site effect for the horizontal and vertical components of weak ground motion. They used selected stations in the seismic network of the eastern Alps, and find the following: (1) all ''hard rock'' sites exhibited deamplification phenomena due to absorption

L. Malagnini; K M Mayeda; A Akinci; P L Bragato

2004-01-01

334

QCD Effects in Cosmology  

E-print Network

The cosmological evolution in the radiation dominated regimen is usually computed by assuming an ideal relativistic thermal bath. In this note, we discuss the deviation from the non-interaction assumption. In either the standard model (SM) and the minimal supersymmetric standard model (MSSM), the main contribution comes from the strong interaction. An understanding of these effects are important for precision measurements and for the evolution of scalar modes, where the commented corrections constitute the main source of the dynamics.

Cembranos, Jose A R

2009-01-01

335

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

336

Doppler-Effect Omnirange  

Microsoft Academic Search

This paper describes an omnirange of a new design in which the transmitting antenna is caused either to move, or to appear to move along a circular path to produce low-deviation FM by Doppler effect. The FM envelope phase of the transmitted signal is directionally characterized. Deviation-expansion and selective-degeneration in an AFC circuit are used at the receiver to detect

Paul Hansel

1953-01-01

337

Putting Instruction Sequences into Effect  

E-print Network

An attempt is made to define the concept of execution of an instruction sequence. It is found to be a special case of directly putting into effect of an instruction sequence. Directly putting into effect of an instruction sequences comprises interpretation as well as execution. Directly putting into effect is a special case of putting into effect with other special cases classified as indirectly putting into effect.

Bergstra, Jan A

2011-01-01

338

Neuroprotective effects of Asiaticoside.  

PubMed

In the central nervous system, Asiaticoside has been shown to attenuate in vitro neuronal damage caused by exposure to ?-amyloid. In vivo studies demonstrated that Asiaticoside could attenuate neurobehavioral, neurochemical and histological changes in transient focal middle cerebral artery occlusion animals. In addition, Asiaticoside showed anxiolytic effects in acute and chronic stress animals. However, its potential neuroprotective properties in glutamate-induced excitotoxicity have not been fully studied. We investigated the neuroprotective effects of Asiaticoside in primary cultured mouse cortical neurons exposed to glutamate-induced excitotoxicity invoked by N-methyl-D-aspartate. Pretreatment with Asiaticoside decreased neuronal cell loss in a concentration-dependent manner and restored changes in expression of apoptotic-related proteins Bcl-2 and Bax. Asiaticoside pretreatment also attenuated the upregulation of NR2B expression, a subunit of N-methyl-D-aspartate receptors, but did not affect expression of NR2A subunits. Additionally, in cultured neurons, Asiaticoside significantly inhibited Ca(2+) influx induced by N-methyl-D-aspartate. These experimental findings provide preliminary evidence that during excitotoxicity induced by N-methyl-D-aspartate exposure in cultured cortical neurons, the neuroprotective effects of Asiaticoside are mediated through inhibition of calcium influx. Aside from its anti-oxidant activity, down-regulation of NR2B-containing N-methyl-D-aspartate receptors may be one of the underlying mechanisms in Asiaticoside neuroprotection. PMID:25221579

Qi, Feng-Yan; Yang, Le; Tian, Zhen; Zhao, Ming-Gao; Liu, Shui-Bing; An, Jia-Ze

2014-07-01

339

Cascading Effects Following Intervention  

PubMed Central

Four different sources for cascade effects were examined using 9-year process and outcome data from a randomized controlled trial (RCT) of a preventive intervention using Parent Management Training – Oregon Model (PMTO™). The social interaction learning (SIL) model of child antisocial behavior serves as one basis for predicting change. A second source addresses the issue of comorbid relationships among clinical diagnoses. The third source, collateral changes, describes events in which changes in one family member correlate with changes in another. The fourth component is based on the long-term effects of reducing coercion and increasing positive interpersonal processes within the family. New findings from the 9-year follow-up show that mothers experienced benefits as measured by standard of living (i.e., income, occupation, education, and financial stress) and frequency of police arrests. It is assumed that PMTO reduces the level of coercion, which sets the stage for a massive increase in positive social interaction. In effect, PMTO alters the family environment and thereby opens doors to healthy new social environments. PMID:20883592

Patterson, Gerald R.; Forgatch, Marion S.; DeGarmo, David S.

2010-01-01

340

Cardioprotective effects of curcumin.  

PubMed

Curcumin, a major active component of turmeric, is extracted from the powdered dry rhizome of Curcuma longa Linn (Zingiberaceae) and it has been used for centuries in indigenous medicine. We have shown that curcumin has a protective role against myocardial necrosis in rats. The antioxidant activity of curcumin could be attributed to the phenolic and methoxy groups in conjunction with the 1,3-diketone-conjugated diene system, for scavenging of the oxygen radicals. In addition, curcumin is shown to enhance the activities of detoxifying enzymes such as glutathione-S-transferase in vivo. We have also shown that oxygen free radicals exacerbate cardiac damage and curcumin induces cardioprotective effect and it also inhibits free-radical generation in myocardial ischemia in rats. This chapter on the cardioprotective effects of curcumin covers the following aspects: (1) the history of curcumin and its discovery as a potent drug with relevance to cardiovascular diseases; (2) mechanistic role of curcumin in vitro, emphasizing the antiplatelet and anticoagulant effects; (3) cardiovascular properties of curcumin; (4) application of curcumin in different animal models (viz. myocardial ischemia, myocardial infarction, cardiomyopathy, and arrhythmia in vitro and in vivo); (5) curcumin free-radical scavenging activity, particularly against O2 radical and depletion of the oxidative stress. PMID:17569220

Miriyala, Sumitra; Panchatcharam, Manikandan; Rengarajulu, Puvanakrishnan

2007-01-01

341

Stringy effects in scrambling  

E-print Network

In [1] we gave a precise holographic calculation of chaos at the scrambling time scale. We studied the influence of a small perturbation, long in the past, on a two-sided correlation function in the thermofield double state. A similar analysis applies to squared commutators and other out-of-time-order one-sided correlators [2-4]. The essential bulk physics is a high energy scattering problem near the horizon of an AdS black hole. The above papers used Einstein gravity to study this problem; in the present paper we consider stringy and Planckian corrections. Elastic stringy corrections play an important role, effectively weakening and smearing out the development of chaos. We discuss their signature in the boundary field theory, commenting on the extension to weak coupling. Inelastic effects, although important for the evolution of the state, leave a parametrically small imprint on the correlators that we study. We briefly discuss ways to diagnose these small corrections, and we propose another correlator where inelastic effects are order one.

Stephen H. Shenker; Douglas Stanford

2015-03-20

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

Causal diagrams, the placebo effect, and the expectation effect  

PubMed Central

Using causal diagrams, a formal research methodology, we analyzed several definitions of placebo and the placebo effect. We conclude that placebo is an ambiguous, redundant term and that the so-called placebo effect conceals far more interesting effects that are attributed to the patient’s expectation. Biomedical research will benefit from abandoning the term placebo effect and focusing instead on a deeper understanding of the expectation variable, including its causes, effects, and effect modifiers. This avenue of research should be pursued by observational cohorts that are nested within clinical trials. PMID:24101881

Shahar, Eyal; Shahar, Doron J

2013-01-01

344

Effectiveness Review Analysis (Insert Effectiveness Review Name) Root Cause  

E-print Network

Effectiveness Review Analysis ­ (Insert Effectiveness Review Name) 1 of 1 Root Cause: Corrective action address the root cause? 2. Does the corrective action prevent recurrence of similar conditions due

345

'The Kesterson effect'  

USGS Publications Warehouse

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, T.S.

1994-01-01

346

Asteroids without opposition effect  

NASA Astrophysics Data System (ADS)

Most of the observed asteroids show a nonlinear increase of brightness at small phase angles, typically less than 7°, known as the opposition effect. Its amplitude, relative to the extrapolation of the linear part of the phase curve, depends on an asteroid's albedo, decreasing for low-albedo asteroids (e.g., Belskaya and Shevchenko 2000). Recently, low-albedo asteroids without the nonlinear increase of brightness down to subdegree phase angles were observed among outer-belt asteroids and Jupiter Trojans (Shevchenko et al. 2012, 2013). These asteroids belong mainly to the P and D spectral classes that have featureless spectra with moderate to high slopes in the visual and near-infrared wavelengths (DeMeo et al. 2009, 2013). Their spectra are similar to the spectra of carbonaceous chondrite meteorites, in particular, to those of some CI meteorites (Alais, Tagish Lake) and some CM meteorites after thermal heating (Cloutis et al. 2011, 2012, Fornazier et al. 2011). We analyze possible relationships between surface composition of asteroids and their opposition effect behavior. Asteroids which do not show nonlinear opposition effect in their magnitude--phase angle dependencies tend to have very low surface albedos. However, the correlation is not very strong due to errors in asteroid albedo determinations. We note that the absolute magnitudes of these asteroids determined using the H, G function are systematically overestimated (Slyusarev et al. 2012, Shevchenko et al. 2014). An overestimate of the absolute brightness results in systematic overestimation of their albedos from the infrared data (Usui et al., 2011, Masiero et al., 2011). Advantages of using the new H, G_1, G_2 function (Muinonen et al. 2010) for the determination of asteroid absolute magnitudes are discussed.

Shevchenko, V.; Belskaya, I.; Slyusarev, I.

2014-07-01

347

Quantum Effects in Biology  

NASA Astrophysics Data System (ADS)

List of contributors; Preface; Part I. Introduction: 1. Quantum biology: introduction Graham R. Fleming and Gregory D. Scholes; 2. Open quantum system approaches to biological systems Alireza Shabani, Masoud Mohseni, Seogjoo Jang, Akihito Ishizaki, Martin Plenio, Patrick Rebentrost, Alàn Aspuru-Guzik, Jianshu Cao, Seth Lloyd and Robert Silbey; 3. Generalized Förster resonance energy transfer Seogjoo Jang, Hoda Hossein-Nejad and Gregory D. Scholes; 4. Multidimensional electronic spectroscopy Tomáš Man?al; Part II. Quantum Effects in Bacterial Photosynthetic Energy Transfer: 5. Structure, function, and quantum dynamics of pigment protein complexes Ioan Kosztin and Klaus Schulten; 6. Direct observation of quantum coherence Gregory S. Engel; 7. Environment-assisted quantum transport Masoud Mohseni, Alàn Aspuru-Guzik, Patrick Rebentrost, Alireza Shabani, Seth Lloyd, Susana F. Huelga and Martin B. Plenio; Part III. Quantum Effects in Higher Organisms and Applications: 8. Excitation energy transfer in higher plants Elisabet Romero, Vladimir I. Novoderezhkin and Rienk van Grondelle; 9. Electron transfer in proteins Spiros S. Skourtis; 10. A chemical compass for bird navigation Ilia A. Solov'yov, Thorsten Ritz, Klaus Schulten and Peter J. Hore; 11. Quantum biology of retinal Klaus Schulten and Shigehiko Hayashi; 12. Quantum vibrational effects on sense of smell A. M. Stoneham, L. Turin, J. C. Brookes and A. P. Horsfield; 13. A perspective on possible manifestations of entanglement in biological systems Hans J. Briegel and Sandu Popescu; 14. Design and applications of bio-inspired quantum materials Mohan Sarovar, Dörthe M. Eisele and K. Birgitta Whaley; 15. Coherent excitons in carbon nanotubes Leonas Valkunas and Darius Abramavicius; Glossary; References; Index.

Mohseni, Masoud; Omar, Yasser; Engel, Gregory S.; Plenio, Martin B.

2014-08-01

348

Transistors: The Field Effect  

NSDL National Science Digital Library

Transistors are the building blocks of modern electronic devices. Your cell phones, iPods, and computers all depend on them to operate. Thanks to today's microfabrication technology, transistors can be made very tiny and be massively produced. You are probably using billions of them while working with this activity now--as of 2006, a dual-core Intel microprocessor contains 1.7 billion transistors. The field effect transistor is the most common type of transistor. So we will focus on it in this activity.

The Concord Consortium

2011-12-11

349

Vibration by relativistic effects  

E-print Network

Relativity, time reversal invariance in mechanics and principle of causality can be in the bases of a type of vibration of the extensive objects. It is because, the detailed analysis of the relativistic movement of an extensive body entail that all the objects must have inherent a vibratory movement to their own size. Such effect does not happen when it works with point particles thus is not stranger who happens unnoticed in the traditional studies. Also we can find relation between the form of vibration of the extensive objects and the energy that calculates by quantum considerations.

Enrique Oradaz Romay

2005-12-27

350

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

351

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

352

Hepatoprotective effects of mushrooms.  

PubMed

The particular characteristics of growth and development of mushrooms in nature result in the accumulation of a variety of secondary metabolites such as phenolic compounds, terpenes and steroids and essential cell wall components such as polysaccharides, b-glucans and proteins, several of them with biological activities. The present article outlines and discusses the available information about the protective effects of mushroom extracts against liver damage induced by exogenous compounds. Among mushrooms, Ganoderma lucidum is indubitably the most widely studied species. In this review, however, emphasis was given to studies using other mushrooms, especially those presenting efforts of attributing hepatoprotective activities to specific chemical components usually present in the mushroom extracts. PMID:23884116

Soares, Andréia Assunço; de Sá-Nakanishi, Anacharis Babeto; Bracht, Adelar; da Costa, Sandra Maria Gomes; Koehnlein, Eloá Angélica; de Souza, Cristina Giatti Marques; Peralta, Rosane Marina

2013-01-01

353

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

354

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.

Krista Larsen

355

The Greenhouse Effect  

NSDL National Science Digital Library

This site provides an overview of the Earth's atmospheric greenhouse effect by briefly exploring the atmospheres of nearby planets and discussing the greenhouse gases of our atmosphere, such as, water vapor, carbon dioxide, methane, ozone, and nitrous oxide. Students will learn that the heat-trapping ability of a greenhouse is influenced by a number of factors, including the transparency of the greenhouse cover, and color and texture of the planet's surfaces. This site serves as a resource for and includes links to two classroom activities.

Carol McLaren

2000-01-01

356

Genotoxic effect of alkaloids.  

PubMed

Because of the increased use of alkaloids in general medical practice in recent years, it is of interest to determine genotoxic, mutagenic and recombinogenic response to different groups of alkaloids in prokaryotic and eucaryotic organisms. Reserpine, boldine and chelerythrine did not show genotoxicity response in the SOS-Chromotest whereas skimmianine showed genotoxicity in the presence of a metabolic activation mixture. Voacristine isolated from the leaves of Ervatamia coronaria shows in vivo cytostatic and mutagenic effects in Saccharomyces cerevisiae hapioids cells. The Rauwolfia alkaloid (reserpine) was not able to induce reverse mutation and recombinational mitotic events (crossing-over and gene conversion) in yeast diploid strain XS2316. PMID:1842017

Henriques, J A; Moreno, P R; Von Poser, G L; Querol, C C; Henriques, A T

1991-01-01

357

Intrinsic Transverse Size Effect  

E-print Network

Two recently proposed concepts to improve the perturbative calculation of exclusive amplitudes, gluonic radiative corrections (Sudakov factor) and confinement size effects (intrinsic transverse momentum) are combined to study the neutron magnetic form factor in the space-like region. We find that nucleon distribution amplitudes modelled on the basis of current QCD sum rules indicate overlap with the existing data at the highest measured values of momentum transfer. However, sizeable higher-order perturbative corrections (K-factor) and/or higher-twist contributions cannot be excluded, although they may be weaker than in the proton case.

J. Bolz; R. Jakob; P. Kroll; M. Bergmann; N. G. Stefanis

1994-07-11

358

Shock effects in meteorites  

NASA Technical Reports Server (NTRS)

The impacts that can occur between objects on intersecting solar system orbits can generate shock-induced deformations and transformations, creating new mineral phases or melting old ones. These shock-metamorphic effects affect not only the petrography but the chemical and isotopic properties and the ages of primordial meteoritic materials. A fuller understanding of shock metamorphism and breccia formation in meteorites will be essential not only in the study of early accretion, differentiation, and regolith-evolution processes, but in the characterization of the primordial composition of the accreted material itself.

Stoeffler, D.; Bischoff, A.; Buchwald, V.; Rubin, A. E.

1988-01-01

359

Key to effective video retrieval: effective cataloging and browsing  

Microsoft Academic Search

-—— ——— — : 1. ABSTRACT Mukirnedia data is an increasingly important information medium today. Providing intelligent access for effective use of this information continues to offer challenges in digital Iibrary research. As computer vision, image processing and speech recognition research continue to progress, we examine the effectiveness of these fully automated techniques in architecting effective video retrieval systems. We

Dulce B. Ponceleon; Savitha Srinivasan; Arnon Amir; Dragutin Petkovic; Dan Diklic

1998-01-01

360

Effect Sizes, Confidence Intervals, and Confidence Intervals for Effect Sizes  

ERIC Educational Resources Information Center

The present article provides a primer on (a) effect sizes, (b) confidence intervals, and (c) confidence intervals for effect sizes. Additionally, various admonitions for reformed statistical practice are presented. For example, a very important implication of the realization that there are dozens of effect size statistics is that "authors must…

Thompson, Bruce

2007-01-01

361

Effects of Vendor-Managed Inventory on the Bullwhip Effect  

Microsoft Academic Search

The bullwhip effect means that demand variability increases as one moves up the supply chain. In the following article the bullwhip effect is quantified for each part of the supply chain which is presupposed to consist of a producer, a wholesaler, a retailer, and a consumer. After considering the causes of the bullwhip effect, it will be shown with the

Susanne Hohmann; Stephan Zelewski

2011-01-01

362

The Manhattan Effect 1 Running Head: THE MANHATTAN EFFECT  

E-print Network

and dismisses her relationship worries. After breaking up with Tracy for another woman, however, Isaac hasThe Manhattan Effect 1 Running Head: THE MANHATTAN EFFECT The Manhattan Effect: When Relationship on close relationships has frequently contrasted one's own interests with the interests of the partner

Reber, Paul J.

363

Ecotoxicological effects extrapolation models  

SciTech Connect

One of the central problems of ecological risk assessment is modeling the relationship between test endpoints (numerical summaries of the results of toxicity tests) and assessment endpoints (formal expressions of the properties of the environment that are to be protected). For example, one may wish to estimate the reduction in species richness of fishes in a stream reach exposed to an effluent and have only a fathead minnow 96 hr LC50 as an effects metric. The problem is to extrapolate from what is known (the fathead minnow LC50) to what matters to the decision maker, the loss of fish species. Models used for this purpose may be termed Effects Extrapolation Models (EEMs) or Activity-Activity Relationships (AARs), by analogy to Structure-Activity Relationships (SARs). These models have been previously reviewed in Ch. 7 and 9 of and by an OECD workshop. This paper updates those reviews and attempts to further clarify the issues involved in the development and use of EEMs. Although there is some overlap, this paper does not repeat those reviews and the reader is referred to the previous reviews for a more complete historical perspective, and for treatment of additional extrapolation issues.

Suter, G.W. II

1996-09-01

364

NEUROPROTECTIVE EFFECTS OF CURCUMIN  

PubMed Central

Neurodegenerative diseases result in the loss of functional neurons and synapses. Although future stem cell therapies offer some hope, current treatments for most of these diseases are less than adequate and our best hope is to prevent these devastating diseases. Neuroprotective approaches work best prior to the initiation of damage, suggesting that some safe and effective prophylaxis would be highly desirable. Curcumin has an outstanding safety profile and a number of pleiotropic actions with potential for neuroprotective efficacy, including anti-inflammatory, antioxidant, and anti-protein-aggregate activities. These can be achieved at sub-micromolar levels. Curcumin’s dose–response curves are strongly dose dependent and often biphasic so that in vitro data need to be cautiously interpreted; many effects might not be achievable in target tissues in vivo with oral dosing. However, despite concerns about poor oral bioavailability, curcumin has at least 10 known neuroprotective actions and many of these might be realized in vivo. Indeed, accumulating cell culture and animal model data show that dietary curcumin is a strong candidate for use in the prevention or treatment of major disabling age-related neurodegenerative diseases like Alzheimer’s, Parkinson’s, and stroke. Promising results have already led to ongoing pilot clinical trials. PMID:17569212

Cole, Greg M.; Teter, Bruce; Frautschy, Sally A.

2008-01-01

365

Predicting Earthquake Effects  

NASA Astrophysics Data System (ADS)

Advances in the earth sciences and information technology have lead to dramatic improvements in our ability to respond to, as well as anticipate and mitigate, earthquake effects in our communities. The development of Geographic Information System (GIS) based tools such as ShakeMap and HAZUS have ushered in a new era of risk and emergency management. Real-time maps of strong ground motion, coupled with engineering-based descriptions of building and infrastructure inventory and vulnerability enable more accurate determinations of the location and severity of earthquake damage and the socio-economic consequences for emergency managers and officials following significant earthquakes. The ability to map the distribution and growth of seismic risk in the United States has long-term benefits for public policy as well. Long-term forecasts of seismic risk based on varying mitigation strategies can provide guidance for developing national and local earthquake policy. The successful performance of the Trans-Alaska pipeline during the 2002 Denali earthquake illustrates the dependence of performance-based engineering on the ability to predict earthquake effects (e.g., levels of strong ground motion, amounts of fault displacement or ground deformation). Being able to reduce the uncertainty in predicting these parameters has significant economic consequences and enables decision makers to more efficiently prioritize risk management strategies.

Nishenko, S.

2005-12-01

366

Quantum Zeno Effect  

E-print Network

We present the physics of the quantum Zeno effect, whose gist is often expressed by invoking the adage "a watched pot never boils". We review aspects of the theoretical and experimental work done on the effect since its inception in 1977, and mention some applications. We dedicate the article - with our very best wishes - to Rudolf Zahradnik at the occasion of his great jubilee. Perhaps Rudolf's lasting youthfulness and freshness are due to that he himself had been frequently observed throughout his life: until the political turn-around in 1989 by those who wished, by their surveillance, to prevent Rudolf from spoiling the youth by his personal culture and his passion for science and things beautiful and useful in general. This attempt had failed. Out of gratitude, the youth has infected Rudolf with its youthfulness. Chronically. Since 1989, Rudolf has been closely watched by the public at large. For the same traits of his as before, but with the opposite goal and for the benefit of all generations. We relish keeping him in sight ...

Mikhail Lemeshko; Bretislav Friedrich

2009-03-26

367

Quantum Zeno Effect  

E-print Network

We present the physics of the quantum Zeno effect, whose gist is often expressed by invoking the adage "a watched pot never boils". We review aspects of the theoretical and experimental work done on the effect since its inception in 1977, and mention some applications. We dedicate the article - with our very best wishes - to Rudolf Zahradnik at the occasion of his great jubilee. Perhaps Rudolf's lasting youthfulness and freshness are due to that he himself had been frequently observed throughout his life: until the political turn-around in 1989 by those who wished, by their surveillance, to prevent Rudolf from spoiling the youth by his personal culture and his passion for science and things beautiful and useful in general. This attempt had failed. Out of gratitude, the youth has infected Rudolf with its youthfulness. Chronically. Since 1989, Rudolf has been closely watched by the public at large. For the same traits of his as before, but with the opposite goal and for the benefit of all generations. We relish...

Lemeshko, Mikhail

2009-01-01

368

Lake Effect Clouds  

NASA Technical Reports Server (NTRS)

The lake effect is particularly clear in this Sea-viewing Wide field-of-view Sensor (SeaWiFS) true-color image of the North American Great Lakes region, acquired December 5, 2000. Lakes Nipigon, Superior, and Michigan show striking contrasts between clear and cloudy air as the wind blows from the northwest across the lakes. As it flows across the relatively warm lakes, the cold dry air gathers heat and moisture from the surface. The warm moist air rises into the atmosphere and mixes vigorously with the cold dry air above. The layer of warm moist air deepens as it travels across the lake. Some of the evaporated water from the lake condenses into streamers of fog rising from the surface, while much of the moisture condenses to form a stratocumulus cloud in the upper half of the mixed layer. The cloud-forming water droplets may freeze into ice crystals and, due to accumulated water deposition over time, grow into snowflakes. This process can generate snowstorms that produce significant amounts of snowfall downwind. It is not uncommon for lake effect snowstorms to produce as much as two feet of snow within a 24-hour period in northwestern parts of New York and Pennsylvania. Image provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

2002-01-01

369

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.

370

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

371

Effect of Ventilation Strategies on  

E-print Network

1 Effect of Ventilation Strategies on Residential Ozone Levels Iain S. Walker ventilation used to reduce concentrations of indoor-generated pollutants. When assessing the effect of deliberate ventilation on occupant health one should consider not only

372

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 ...

373

Hall Effect in a Plasma.  

ERIC Educational Resources Information Center

Describes an apparatus and procedure for conducting an undergraduate laboratory experiment to quantitatively study the Hall effect in a plasma. Includes background information on the Hall effect and rationale for conducting the experiment. (JN)

Kunkel, W. B.

1981-01-01

374

IMPROVED LABORATORY DISPERSANT EFFECTIVENESS TEST  

EPA Science Inventory

The U.S. Environmental Protection Agency (EPA) initiated a program to evaluate an Improved Laboratory Dispersant Effectiveness Test (ILDET) which was developed to replace EPA's Revised Standard Dispersant Effectiveness Test (RSDET). The report summarizes the development of the IL...

375

Further considerations of spallation effects  

NASA Technical Reports Server (NTRS)

Trapped photon and cosmic ray effects on spallation in the UK-5 (hard X ray telescope) central crystal were measured. Both low dose and high dose effects were considered. Decay results are presented in tables.

Dyer, C.

1973-01-01

376

Managing Chemotherapy Side Effects: Infection  

MedlinePLUS

... effects Managing Chemotherapy Side Effects: Infection Take these steps to lower your chances of getting an infection: Try not to get cuts. ? Use an electric shaver, not a razor. ? Clean yourself well and ...

377

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

378

A Semi-Passive Containment Cooling System Conceptual Design  

E-print Network

The objective of this project was to investigate a passive containment cooling system (PCCS) for the double concrete containment of the Korean Next Generation Reactor (KNGR). Two conceptual PCCS designs: the thermosyphon ...

Liu, H.

379

Euler - Heisenberg effective action and magnetoelectric effect in multilayer graphene  

E-print Network

The low energy effective field model for the multilayer graphene (at ABC stacking) is considered. We calculate the effective action in the presence of constant external magnetic field $B$ (normal to the graphene sheet). We also calculate the first two corrections to this effective action caused by the in-plane electric field $E$ at $E/B \\ll 1$ and discuss the magnetoelectric effect. In addition, we calculate the imaginary part of the effective action in the presence of constant electric field $E$ and the lowest order correction to it due to the magnetic field ($B/E \\ll 1$).

M. I. Katsnelson; G. E. Volovik; M. A. Zubkov

2013-01-24

380

[Mechanism of warburg effect and its effect on tumor metastasis].  

PubMed

Cancer cells exhibit altered glucose metabolism characterized by a preference for aerobic glycolysis even when the oxygen content is normal, a phenomenon termed "Warburg effect". However the definite molecular mechanisms of Warburg effect remains unclear, recent works indicated that it might be related to the abnormal activity of the oncogene and tumor suppressor genes, also the change of tumor microenvironment, the abnormal expression of glucose metabolic enzyme and so on. Warburg effect has a relationship with tumor progression and provide suitable conditions for tumor metastasis. This review will summarizes the mechanism of Warburg effect and its effect on tumor metastasis. PMID:25800576

Wei, Huijun; Guo, Lili; Li, Lin; Zhou, Qinghua; Wu, Zhihao

2015-03-20

381

Effective medium in dispersed systems  

Microsoft Academic Search

A structural analysis of effective medium formed by dispersed systems from the viewpoint of flux modification at large dispersions\\u000a is presented. The effective medium coefficient is investigated for its parametric dependence and the effective properties\\u000a are estimated through this dependence. This estimation covers all highly dispersed two-phase systems including the effect\\u000a of container.

R N Pande; D R Chaudhary; F Gori

1987-01-01

382

Inverse Gibbs-Thomson effect  

NASA Astrophysics Data System (ADS)

We prove the existence of an effect inverse to the Gibbs-Thomson effect for mass transfer in systems consisting of a solid phase and the solution of the solid phase material in a certain solvent. The effect involves a change in the shape of the interface due to a variation of the equilibrium concentrations under it, which is induced by external conditions, and exists in the presence of a negative feedback for mass transfer associated with capillary effects.

Gershanov, V. Yu.; Garmashov, S. I.

2015-01-01

383

Anisotropic effective medium theories  

NASA Astrophysics Data System (ADS)

The optical properties of anisotropic inhomogeneous media are studied within the framework of the classical 3D effective medium theories of Maxwell Garnett and Bruggeman, and the 2D theory of Yamaguchi et al. The origin of the anisotropy is either the nonspherical shape of the metallic inclusions in the 3D systems, or the distribution of the inclusions (even if spherical) on a substrate in the 2D configuration. In both cases, it leads to an anisotropic effective medium. In this paper, it is shown that this surrounding anisotropic medium induces a fictitious deformation of the inclusions which reduces the anisotropy and shifts the resonance wavelengths toward the sphere plasmon resonance. In the case of the mean field theory of Bruggeman, it also affects the percolation threshold value. Although some of these theories are now quite old, they are still extensively used, especially for the predictions of the absorption of the composite media. Therefore the effect presented here for the first time should be taken into account. Les propriétés optiques des milieux inhomogènes anisotropes sont étudiées dans le cadre des théories du milieu effectif, tant à trois dimensions (3D) (théories de Maxwell Garnett et de Bruggeman) qu'à deux dimensions (2D) (théorie de Yamaguchi et al.). L'anisotropie du milieu effectif peut provenir soit de l'alignement d'inclusions non sphériques dans un système à deux ou trois dimensions, soit de la distribution plane du système 2D, même pour des particules sphériques. Nous montrons ici que ce milieu effectif anisotrope induit une déformation fictive des inclusions qui va dans le sens d'une réduction de l'anisotropie et rapproche les fréquences de résonance de plasmon de surface vers celle de la sphère. Par ailleurs, dans le cas de la théorie de Bruggeman, cela modifie la valeur du seuil de percolation optique. Ces théories, bien qu'anciennes, sont toujours très utilisées, en particulier pour prédire l'absorption optique des composites. L'effet présenté ici doit donc impérativement être pris en compte.

Berthier, Serge

1994-02-01

384

Longitudinal Spin Seebeck Effect  

NASA Astrophysics Data System (ADS)

The spin Seebeck effect (SSE) refers to the generation of a spin voltage as a result of a temperature gradient in magnetic materials [1-7]. Here, a spin voltage is a potential for electron spins to drive a nonequilibrium spin current; when a conductor is attached to a magnet with a finite spin voltage, it induces a spin injection into the conductor. The SSE is of crucial importance in spintronics and spin caloritronics, since it enables simple and versatile generation of a spin current from heat. The simplest and most straightforward setup of the SSE is the longitudinal configuration [4], in which a spin current flowing parallel to a temperature gradient is measured via the inverse spin Hall effect (ISHE). The longitudinal SSE device consists of a ferromagnetic or ferrimagnetic insulator (FI, e.g. YIG) covered with a paramagnetic metal (PM, e.g. Pt) film. When a temperature gradient is applied perpendicular to the FI/PM interface, an ISHE-induced voltage is generated in the PM layer. In this talk, we report the observation of the longitudinal SSE in various FI/PM systems and provide evidence that the longitudinal SSE is free from thermoelectric artefact [7], i.e., the anomalous Nernst effect caused by extrinsic magnetic proximity [8]. Then, we discuss the longitudinal SSE from an application point of view [6]. We thank E. Saitoh, S. Maekawa, G. E. W. Bauer, X.-F. Jin, H. Adachi, D. Hou, D. Tian, T. Kikkawa, A. Kirihara, and M. Ishida for their support and valuable discussions. [4pt] [1] K. Uchida et al., Nature 455, 778 (2008).[0pt] [2] K. Uchida et al., Nature Mater. 9, 894 (2010).[0pt] [3] C. M. Jaworski et al., Nature Mater. 9, 898 (2010).[0pt] [4] K. Uchida et al., Appl. Phys. Lett. 97, 172505 (2010).[0pt] [5] K. Uchida et al., Nature Mater. 10, 737 (2011).[0pt] [6] A. Kirihara et al., Nature Mater. 11, 686 (2012).[0pt] [7] T. Kikkawa et al., arXiv:1211.0139 (2012). [0pt] [8] S. Y. Huang et al., Phys. Rev. Lett. 109, 107204 (2012).

Uchida, Ken-Ichi

2013-03-01

385

Radiation effect on implanted pacemakers  

SciTech Connect

It was previously thought that diagnostic or therapeutic ionizing radiation did not have an adverse effect on the function of cardiac pacemakers. Recently, however, some authors have reported damaging effect of therapeutic radiation on cardiac pulse generators. An analysis of a recently-extracted pacemaker documented the effect of radiation on the pacemaker pulse generator.

Pourhamidi, A.H.

1983-10-01

386

The Greenhouse Effect without Feedbacks  

E-print Network

The Greenhouse Effect without Feedbacks #12;Three Pillars Behind Climate Change! #12;1. Global. Greenhouse Gases have been on the increase. #12;3. The Greenhouse effect is a powerful theory that explains! natural greenhouse effect! · an empirical introduction #12;Moral of the story: The doubling of CO2 causes

387

Effectiveness of Family Planning Methods  

MedlinePLUS

Effectiveness of Family Planning Methods Most Effective Less than 1 pregnancy per 100 women in a year Reversible Implant 0.05 %* Intrauterine Device (IUD) LNG - ... Laparoscopic, Hysteroscopic) 0.5 % How to make your method most effective After procedure, little or nothing to ...

388

"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

389

Partner effects in social interaction  

Microsoft Academic Search

A person's behavior during social interaction is due not only to the person's dispositional characteristics but is also determined by his or her social partner. If a person consistently elicits the same behavior from others, the person has apartner effect. Partner effects in affect, cognition, and behavior are examined. Partner effects in behavior are presumed to be caused by partner

David A. Kenny; Thomas E. Malloy

1988-01-01

390

2, 289337, 2002 Greenhouse effect  

E-print Network

effect dependence on atmospheric concentrations of greenhouse substances and the nature of climate water vapour concentration, dependence of the planetary greenhouse effect on atmospheric water content by the values and temperature-dependent behaviour of the planetary albedo and atmospheric greenhouse effect

Paris-Sud XI, Université de

391

Space Science : Atmosphere Greenhouse Effect  

E-print Network

Space Science : Atmosphere Greenhouse Effect Part-5a Solar + Earth Spectrum IR Absorbers Grey Atmosphere Greenhouse Effect #12;Radiation: Solar and Earth Surface B"(T) Planck Ideal Emission Integrate at the carbon cycle #12;However, #12;Greenhouse Effect is Complex #12;PLANETARY ENERGY BALANCE G+W fig 3-5

Johnson, Robert E.

392

Solar Neutrino Matter Effects Redux  

E-print Network

Following recent low-threshold analysis of the Sudbury Neutrino Observatory and asymmetry measurements of the BOREXINO Collaboration of the solar neutrino flux, we revisit the analysis of the matter effects in the Sun. We show that solar neutrino data constrains the mixing angle $\\theta_{13}$ poorly and that subdominant Standard Model effects can mimic the effects of the physics beyond the Standard Model.

A. B. Balantekin; A. Malkus

2011-12-19

393

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.

394

HIV and AIDS: Oral Effects  

MedlinePLUS

HIV and AIDS Oral Effects At the Dentist Oral Effects The oral effects of HIV and AIDS occur because of your weakened immune system and ... of medicines that you may take for HIV/AIDS. Dry mouth can make you more prone to ...

395

Effective operators in atomic physics  

Microsoft Academic Search

The correlation effect of inter-electronic interactions between atomic configurations can be reproduced by effective orthogonal operators acting within a single configuration of interest. These operators which act on N electrons at a time can be resolved through the use of continuous Lie groups. This thesis details the development of these effective operators for a number of configurations. Complete sets of

1989-01-01

396

Effective Operators in Atomic Physics  

Microsoft Academic Search

The correlation effects of inter-electronic interactions between atomic configurations can be reproduced by effective orthogonal operators acting within a single configuration of interest. These operators which act on N electrons at a time can be resolved through the use of continuous Lie groups. This thesis details the development of these effective operators for a number of configurations. Complete sets of

Richard Carlson Leavitt

1989-01-01

397

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

398

Acting intentionally and the side-effect effect.  

PubMed

The concept of acting intentionally is an important nexus where theory of mind and moral judgment meet. Preschool children's judgments of intentional action show a valence-driven asymmetry. Children say that a foreseen but disavowed side effect is brought about "on purpose" when the side effect itself is morally bad, but not when it is morally good. This is the first demonstration in preschoolers that moral judgment influences judgments of whether something was done on purpose (as opposed to judgments of purpose influencing moral judgment). Judgments of intentionality are usually assumed to be purely factual. That these judgments are sometimes partly normative-even in preschoolers-challenges current understanding. Young children's judgments regarding foreseen side effects depend on whether the children process the idea that the character does not care about the side effect. As soon as preschoolers effectively process the theory-of-mind concept "not care that P," children show the side-effect effect. PMID:16683930

Leslie, Alan M; Knobe, Joshua; Cohen, Adam

2006-05-01

399

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

400

Hypersonic jet control effectiveness  

NASA Astrophysics Data System (ADS)

The present study aims to identify some of the parameters which determine the upstream extent and the lateral spreading of the separation front around an under-expanded transverse jet on a slender blunted cone. The tests were conducted in the Cranfield hypersonic facility at M? = 8.2, Re? /cm = 4.5 to 9.0 × 104 and at M? = 12.3, Re? /cm = 3.3 × 104. Air was used as the working gas for both the freestream and the jet. Schlieren pictures were used for the visualisation of the three-dimensional structures around the jet. Pressure, normal force and pitching moment measurements were conducted to quantitatively study the interaction region and its effects on the vehicle. An analytical algorithm has been developed to predict the shape of the separation front around the body.

Kumar, D.; Stollery, J. L.; Smith, A. J.

401

Effective leadership in competition  

E-print Network

Among natural biological flocks/swarms or even mass social activities, when the collective behaviors of the followers has been dominated by the moving direction or opinion of one leader group, it seems very difficult for later-coming leaders to reverse the orientation of the mass followers, especially when they are in quantitative minority. This Letter reports a counter-intuitive phenomenon, Following the Later-coming Minority, provided that the late-comers obey a favorable distribution pattern which enables them to spread their influence to as many followers as possible in a given time and to accumulate enough power to govern these followers. We introduce a discriminant index to quantify the whole group's orientation under competing leadership, which helps to design an economic way for the minority later-coming leaders to defeat the dominating majority leaders solely by optimizing their distribution pattern. Our investigation provides new insights into the effective leadership in biological systems, with mea...

Zhang, Hai-Tao; Chen, Michael Z Q; Zhou, Tao; Zhou, Changsong

2009-01-01

402

Asphericity Effects in Supernovae  

E-print Network

We present a brief summary of asphericity effects in thermonuclear and core collapse supernovae (SN), and how to distinguish the underlying physics by their observable signatures. Electron scattering is the dominant process to produce polarization which is one of the main diagnostical tools. Asphericities result in a directional dependence of the luminosity which has direct implications for the use of SNe in cosmology. For core collapse SNe, the current observations and their interpretations suggest that the explosion mechanism itself is highly aspherical with a well defined axis and, typically, axis ratios of 2 to 3. Asymmetric density/chemical distributions and off-center energy depositions have been identified as crucial for the interpretation of the polarization $P$. For thermonuclear SNe, polarization turned out to be an order of magnitude smaller strongly supporting rather spherical, radially stratified envelopes. Nevertheless, asymmetries have been recognized as important signatures to probe A) for the...

Höflich, P; Quimby, R

2003-01-01

403

Axio-electric effect  

E-print Network

Using the relativistic Hartree-Fock approximation, we calculate the rates of atomic ionization by absorption of axions of the energies up to 100 keV and for an arbitrary value of the axion mass. We present numerical results for atoms used in the low radioactive background searches of dark matter (\\em{e.g.} Ar, Ge and Xe), as well as the analytical formula which fits numerical calculations for the absorption cross sections and can be applied for other atoms, molecules and condensed matter systems. Using the cross-sections for the axio-electric effect, we derive the counting rates induced by solar axions and set limits on the axion coupling constants.

Derevianko, A; Flambaum, V V; Pospelov, M

2010-01-01

404

Axio-electric effect  

E-print Network

Using the relativistic Hartree-Fock approximation, we calculate the rates of atomic ionization by absorption of axions of the energies up to 100 keV and for an arbitrary value of the axion mass. We present numerical results for atoms used in the low radioactive background searches of dark matter (e.g. Ar, Ge and Xe), as well as the analytical formula which fits numerical calculations for the absorption cross sections and can be applied for other atoms, molecules and condensed matter systems. Using the cross-sections for the axio-electric effect, we derive the counting rates induced by solar axions and set limits on the axion coupling constants.

A. Derevianko; V. A. Dzuba; V. V. Flambaum; M. Pospelov

2010-07-12

405

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

406

Superhydrophobicity — The Lotus Effect  

NSDL National Science Digital Library

Students are introduced to superhydrophobic surfaces and the "lotus effect." Water spilled on a superhydrophobic surface does not wet the surface, but simply rolls off. Additionally, as water moves across the superhydrophobic surface, it picks up and carries away any foreign material, such as dust or dirt. Students learn how plants create and use superhydrophobic surfaces in nature and how engineers have created human-made products that mimic the properties of these natural surfaces. They also learn about the tendency of all superhydrophobic surfaces to develop water droplets that do not roll off the surface but become "pinned" under certain conditions, such as water droplets formed from condensation. They see how the introduction of mechanical energy can "unpin" these water droplets and restore the desirable properties of the superhydrophobic surface.

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

407

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.

408

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.

409

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

Karen Gran

410

Unruh effect and Holography  

E-print Network

We study the Unruh effect on the dynamics of quarks and mesons in the context of AdS/CFT correspondence. We adopt an AdS metric with the boundary Rindler edge extending into a bulk Rindler-like horizon, which yields the thermodynamics with Unruh temperature verified by computing the boundary stress tensor. We then embed in it the probe fundamental string and D7 brane which are dual to the quark and meson in the Unruh vacuum, respectively. Using the standard procedure of holographic renormalization, we calculate the chiral condensate, and also the spectral functions for both quarks and mesons. From these, we extract the corresponding strength of random force of the Langevin dynamics and observe that it can characterize the phase transition of meson melting. We find most of the dynamical features are qualitatively similar to the ones in the thermal bath dual to the AdS black hole background, though could be quite different quantitatively.

Hirayama, Takayuki; Kawamoto, Shoichi; Lin, Feng-Li

2010-01-01

411

The Energy Diameter Effect  

SciTech Connect

Various relations for the detonation energy and velocity as they relate to the inverse radius of the cylinder are explored. The 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 and sphere 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.

Souers, P; Vitello, P; Garza, R; Hernandez, A

2007-04-20

412

The Energy Diameter Effect  

SciTech Connect

We explore various relations for the detonation energy and velocity as they relate to the inverse radius of the cylinder. The 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, P; Garza, R; Hernandez, A; Souers, P C

2007-07-10

413

[Immunomodulatory effects of lenalidomide].  

PubMed

Immunomodulatory drugs (IMiDs) including lenalidomide, a single compound shows various pharmacological action such as the stimulation of T cells and natural killer (NK) cells, the suppression hematopoietic tumor proliferation, suppression of neo-vascularisation, and anti-inflammatory action. It has been thought that IMiDs stimulates CD8+ cytotoxic T cells primarily, it is recently shown that they also stimulate CD4+ helper-T cells similarly. Lenalidomide stimulates T cells and NK-cell through production of Th1 type cytokines IL-2 and IFN-? from CD4+ helper-T cells. Lenalidomide also activate T cells indirectly by inhibiting regulatory T cells and myeloid derived suppressor cells (MDSC) which inhibit the activation of T cells, but controversy still exist about effects on regulatory T cells. PMID:25626322

Handa, Hiroshi; Saitoh, Takayuki; Murakami, Hirokazu

2015-01-01

414

Radiation Effects In Space  

SciTech Connect

Protecting space missions from severe exposures from radiation, in general, and long duration/deep space human missions, in particular, is a critical design driver, and could be a limiting factor. The space radiation environment consists of galactic cosmic rays (GCR), solar particle events (SPE), trapped radiation, and includes ions of all the known elements over a very broad energy range. These ions penetrate spacecraft materials producing nuclear fragments and secondary particles that damage biological tissues and microelectronic devices. One is required to know how every element (and all isotopes of each element) in the periodic table interacts and fragments on every other element in the same table as a function of kinetic energy ranging over many decades. In addition, the accuracy of the input information and database, in general and nuclear data in particular, impacts radiation exposure health assessments and payload penalty. After a brief review of effects of space radiation on materials and electronics, human space missions to Mars is discussed.

Tripathi, Ram K. [NASA Langley Research Center, MS - 188 E, Hampton VA 23681 (United States)

2011-06-01

415

THE 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 ten percent accuracy of the experiments.

Crawford, Frank S.

1980-12-01

416

Antimutagenic effects in humans  

SciTech Connect

The application of antimutagenicity studies to human somatic mutation is discussed, with emphasis on the potential for future studies. Five assay-gene combinations are now available for measuring human somatic mutation in lymphocytes and erythrocytes. Results with these combinations have defined the human background levels, and show clear responses of mutant frequency to a variety of mutagens. The testing of antimutagenic effects of background frequencies is feasible, but has not yet been done. The major uncertainty in such studies is the unknown age of mutant cells in the background, since only the newly forming mutants are potentially susceptible to most antimutagenic treatments. Intervention studies in the face of active mutagenicity and the use of other genotoxicity endpoints, such as chromosome aberrations, micronuclei and DNA adducts, are considered briefly. 42 refs.

Mendelsohn, M.L.

1991-06-10

417

Radiolytic effects of plutonium.  

SciTech Connect

Plutonium isotopes, most of them a-emitters, cause radiolytic changes in the matrix, in whic h they are embedded. The internal irradiation of Pu metal or its alloys results in physical changes, largel y as a result of the formation of helium bubbles, well-known to material scientists and weapons specialists . In all other media where plutonium occurs, usually as Pu'+ in an ionic form, the results of irradiation ar e chemical in nature. Homogenous media containing Pu, are often aqueous or non-aqueous solutions o f plutonium compounds, mostly originating during processing of spent nuclear fuel or from Pu processing . Heterogenous matrices containing plutonium are more complex from the point of view of radiolysis; they usually contain a variety of combinations of common materials contaminated with radionuclides . This class of radioactive materials represents a challenge for the management of plutonium waste . One has to consider a range of time scales for radiolytic effects (and consequently a several orders o f magnitude range of the cumulative dose) beginning with waste generation, through packaging, transportation, to the period of final storage . Final storage could be for thousands of years in deep geologic repositories . At every ' stage of that time scale, radiolysis proceeds continuously an d cumulative effects c an complicate operating procedures and final disposition . The results presented here have been obtained from experiments that have irradiated of model materials, which are typically the objects of contamination with plutonium . They were irradiated with linearly accelerated electrons up to very high dose rates, adjusted to simulate any contamination at any point on the time scale .

Zagorski, Z. (Zbigniew); Dziewinski, J. J. (Jacek J.); Conca, James L.

2003-01-01

418

Effective monitoring of agriculture.  

PubMed

An opinion piece published in Nature proposed a global network for agricultural monitoring [J. Sachs, R. Remans, S. Smukler, L. Winowiecki, S. J. Andelman, K. G. Cassman, D. Castle, R. DeFries, G. Denning, J. Fanzo, L. E. Jackson, R. Leemans, J. Leemans, J. C. Milder, S. Naeem, G. Nziguheba, C. A. Palm, J. P. Reganold, D. D. Richter, S. J. Scherr, J. Sircely, C. Sullivan, T. P. Tomich and P. A. Sanchez, Nature, 2010, 466, 558-560.]. Whilst we agree with Sachs et al. that monitoring of agricultural systems is a critically important activity of global significance, especially given increasing problems with global food security and the potential impacts of agriculture on the environment [J. Cribb, The Coming Famine. The Global Food Crisis and What We Can Do to Avoid It, CSIRO Publishing and University of California Press, Melbourne and Oakland, 2010.], we argue in this paper that their generic, mandated monitoring framework has a high probability of failure or at best will be highly inefficient. We base this conclusion on our recently published examination of the factors influencing the success or failure of monitoring programs worldwide [D. B. Lindenmayer and G. E. Likens, Effective Ecological Monitoring, CSIRO Publishing and Earthscan, Melbourne and London, 2010.]. We briefly outline what we believe are three serious flaws in the monitoring framework proposed by Sachs et al. We then suggest an alternative approach that we argue would be more effective, more efficient, and have a greater chance of successfully addressing key issues in sustainable agriculture. PMID:21479312

Lindenmayer, David B; Likens, Gene E

2011-06-01

419

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

420

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

421

Public Opinion on Mass Media Effects: Perceived Societal Effects and Perceived Personal Effects.  

ERIC Educational Resources Information Center

The questionnaire in a study of perceived mass media effects included nine statements about the possible negative effects of the mass media, to which respondents could agree, disagree, or indicate "no opinion," and an open-ended question that asked the subjects what effects the mass media had on them personally. Most of the 340 respondents showed…

Tiedge, James T.

422

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

423

Anomalous Hall effect  

NASA Astrophysics Data System (ADS)

The anomalous Hall effect (AHE) occurs in solids with broken time-reversal symmetry, typically in a ferromagnetic phase, as a consequence of spin-orbit coupling. Experimental and theoretical studies of the AHE are reviewed, focusing on recent developments that have provided a more complete framework for understanding this subtle phenomenon and have, in many instances, replaced controversy by clarity. Synergy between experimental and theoretical works, both playing a crucial role, has been at the heart of these advances. On the theoretical front, the adoption of the Berry-phase concepts has established a link between the AHE and the topological nature of the Hall currents. On the experimental front, new experimental studies of the AHE in transition metals, transition-metal oxides, spinels, pyrochlores, and metallic dilute magnetic semiconductors have established systematic trends. These two developments, in concert with first-principles electronic structure calculations, strongly favor the dominance of an intrinsic Berry-phase-related AHE mechanism in metallic ferromagnets with moderate conductivity. The intrinsic AHE can be expressed in terms of the Berry-phase curvatures and it is therefore an intrinsic quantum-mechanical property of a perfect crystal. An extrinsic mechanism, skew scattering from disorder, tends to dominate the AHE in highly conductive ferromagnets. The full modern semiclassical treatment of the AHE is reviewed which incorporates an anomalous contribution to wave-packet group velocity due to momentum-space Berry curvatures and correctly combines the roles of intrinsic and extrinsic (skew-scattering and side-jump) scattering-related mechanisms. In addition, more rigorous quantum-mechanical treatments based on the Kubo and Keldysh formalisms are reviewed, taking into account multiband effects, and demonstrate the equivalence of all three linear response theories in the metallic regime. Building on results from recent experiment and theory, a tentative global view of the AHE is proposed which summarizes the roles played by intrinsic and extrinsic contributions in the disorder strength versus temperature plane. Finally outstanding issues and avenues for future investigation are discussed.

Nagaosa, Naoto; Sinova, Jairo; Onoda, Shigeki; MacDonald, A. H.; Ong, N. P.

2010-04-01

424

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

425

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

426

Asphericity Effects in Supernovae  

E-print Network

We present a brief summary of asphericity effects in thermonuclear and core collapse supernovae (SN), and how to distinguish the underlying physics by their observable signatures. Electron scattering is the dominant process to produce polarization which is one of the main diagnostical tools. Asphericities result in a directional dependence of the luminosity which has direct implications for the use of SNe in cosmology. For core collapse SNe, the current observations and their interpretations suggest that the explosion mechanism itself is highly aspherical with a well defined axis and, typically, axis ratios of 2 to 3. Asymmetric density/chemical distributions and off-center energy depositions have been identified as crucial for the interpretation of the polarization $P$. For thermonuclear SNe, polarization turned out to be an order of magnitude smaller strongly supporting rather spherical, radially stratified envelopes. Nevertheless, asymmetries have been recognized as important signatures to probe A) for the signatures of the progenitor system, B) the global asymmetry with well defined axis, likely to be caused by rotation of an accreting white dwarf or merging WDs, and C) possible remains of the deflagration pattern.

P. Hoeflich; C. Gerardy; R. Quimby

2003-12-22

427

[Effects of traumatic stress].  

PubMed

The diagnosis PTSD does not adequately describe the impact of exposure to childhood trauma of the developing child. The objective of the study was to examine the prevalence of different interpersonal trauma types and to describe the long-term effects of maltreatment and neglect in a clinical sample of 34 adolescents. The majority (62%) of the sample was exposed to two different types of trauma during childhood. Emotional abuse and emotional neglect have been the most common trauma types (59%; 53%). 71% of the traumatized adolescents did not meet the criteria for PTSD. The most common diagnosis in the sample was Borderline Personality Disorder. All average scores at SCL-90-Symptom-Scale were clinical significant. Half of the sample reported suicide attempts and self destructive behavior. One third reported substance abuse and aggressive behavior against others respectively. None of the traumatized adolescents had a positive Self-concept. Altogether the results show that abused children and adolescents have a range of psychological sequelae that are not captured in the PTSD diagnostic criteria. Therefore the results support the necessity for a new and more precise diagnosis for chronically traumatized children and adolescents. PMID:19961125

Herbst, Gesa; Jaeger, Ulrich; Leichsenring, Falk; Streeck-Fischer, Annette

2009-01-01

428

Transvection effects in Drosophila.  

PubMed

An unusual feature of the Diptera is that homologous chromosomes are intimately synapsed in somatic cells. At a number of loci in Drosophila, this pairing can significantly influence gene expression. Such influences were first detected within the bithorax complex (BX-C) by E.B. Lewis, who coined the term transvection to describe them. Most cases of transvection involve the action of enhancers in trans. At several loci deletion of the promoter greatly increases this action in trans, suggesting that enhancers are normally tethered in cis by the promoter region. Transvection can also occur by the action of silencers in trans or by the spreading of position effect variegation from rearrangements having heterochromatic breakpoints to paired unrearranged chromosomes. Although not demonstrated, other cases of transvection may involve the production of joint RNAs by trans-splicing. Several cases of transvection require Zeste, a DNA-binding protein that is thought to facilitate homolog interactions by self-aggregation. Genes showing transvection can differ greatly in their response to pairing disruption. In several cases, transvection appears to require intimate synapsis of homologs. However, in at least one case (transvection of the iab-5,6,7 region of the BX-C), transvection is independent of synapsis within and surrounding the interacting gene. The latter example suggests that transvection could well occur in organisms that lack somatic pairing. In support of this, transvection-like phenomena have been described in a number of different organisms, including plants, fungi, and mammals. PMID:12429702

Duncan, Ian W

2002-01-01

429

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

430

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

431

Harmful effects of nicotine  

PubMed Central

With the advent of nicotine replacement therapy, the consumption of the nicotine is on the rise. Nicotine is considered to be a safer alternative of tobacco. The IARC monograph has not included nicotine as a carcinogen. However there are various studies which show otherwise. We undertook this review to specifically evaluate the effects of nicotine on the various organ systems. A computer aided search of the Medline and PubMed database was done using a combination of the keywords. All the animal and human studies investigating only the role of nicotine were included. Nicotine poses several health hazards. There is an increased risk of cardiovascular, respiratory, gastrointestinal disorders. There is decreased immune response and it also poses ill impacts on the reproductive health. It affects the cell proliferation, oxidative stress, apoptosis, DNA mutation by various mechanisms which leads to cancer. It also affects the tumor proliferation and metastasis and causes resistance to chemo and radio therapeutic agents. The use of nicotine needs regulation. The sale of nicotine should be under supervision of trained medical personnel.

Mishra, Aseem; Chaturvedi, Pankaj; Datta, Sourav; Sinukumar, Snita; Joshi, Poonam; Garg, Apurva

2015-01-01

432

(Limiting the greenhouse effect)  

SciTech Connect

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 CO{sub 2} 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 scientists from developing countries was limited. The conference was divided into four multidisciplinary working groups. Traveler acted as moderator for Group 3 which examined the question What knowledge is required to tackle the principal social and institutional barriers to reducing CO{sub 2} emissions'' The working rapporteur was Jesse Ausubel of Rockefeller University. Other working groups examined the economic costs, benefits, and technical feasibility of options to reduce emissions per unit of energy service; the options for reducing energy use per unit of GNP; and the significant of linkage between strategies to reduce CO{sub 2} emissions and other goals. Draft reports of the working groups are appended. Overall, the conference identified a number of important research needs in all four areas. It may prove particularly important in bringing the social and institutional research needs relevant to climate change closer to the forefront of the scientific and policy communities than hitherto.

Rayner, S.

1991-01-07

433

Effective obesity treatments.  

PubMed

To curb the epidemic of obesity in the United States, revised Medicare policy allows support for efficacious obesity treatments. This review summarizes the evidence from rigorous randomized trials (9 lifestyle trials, 5 drug trials, and 2 surgical trials) on the efficacy and risk- benefit profile of lifestyle, drug, and surgical interventions aimed at promoting sustained (= 2 years) reductions in weight. Both lifestyle and drug interventions consistently produced an approximate 7-lb (3.2-kg) weight loss that was sustained for 2 years and was associated with improvements in diabetes, blood pressure, and/or cardiovascular risk factors. Surgical interventions have a less solid empirical base but offer promise for the promotion of significant and sustained weight reduction posttreatment in the morbidly obese but with possible significant short-term side effects. In summary, there is strong and consistent support from rigorous randomized trials that lifestyle or drug interventions result in modest weight loss with minimal risks but disproportionate clinical benefit. Combinations of lifestyle, drug, and, where appropriate, surgical interventions may be the most efficacious approach to achieving sustained weight loss for the widest diversity of patients. PMID:17469901

Powell, Lynda H; Calvin, James E; Calvin, James E

2007-04-01

434

Phosphorene nanoribbons: Passivation effect on bandgap and effective mass  

NASA Astrophysics Data System (ADS)

The edge passivation effect of phosphorene nanoribbons is systematically investigated using density functional theory. Hydrogen and fluorine atoms passivate the metallic edge states of nanoribbons and can open a bandgap up to 2.25 eV. The two configurations of passivated atoms can exist at two edges and affect the bandgap of narrow nanoribbons. The bandgap of each type of zPNRs decreases as the ribbon's width increases, which can be attributed to the quantum confinement effect. The new configuration, named Cb, can effectively reduce the effective mass of electrons, which benefits the future design of phosphorene-based electronic devices.

Xu, Li-Chun; Song, Xian-Jiang; Yang, Zhi; Cao, Ling; Liu, Rui-Ping; Li, Xiu-Yan

2015-01-01

435

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

436

Electron Effective Mass in Graphene  

E-print Network

The particle effective mass in graphene is a challenging concept because the commonly used theoretical expression is mathematically divergent. In this paper, we use basic principles to present a simple theoretical expression for the effective mass that is suitable for both parabolic and non-parabolic isotropic materials. We demonstrate that this definition is consistent with the definition of the cyclotron effective mass, which is one of the common methods for effective mass measurement in solid state materials. We apply the proposed theoretical definition to graphene and demonstrate linear dependence of the effective mass on momentum, as confirmed by experimental cyclotron resonance measurements. Therefore, the proposed definition of the effective mass can be used for non-parabolic materials such as graphene.

Viktor Ariel; Amir Natan

2012-08-12

437

Neuroendocrine effects of light  

NASA Astrophysics Data System (ADS)

The light/dark cycle to which animals, and possibly humans, are exposed has a major impact on their physiology. The mechanisms whereby specific tissues respond to the light/dark cycle involve the pineal hormone melatonin. The pineal gland, an end organ of the visual system in mammals, produces the hormone melatonin only at night, at which time it is released into the blood. The duration of elevated nightly melatonin provides every tissue with information about the time of day and time of year (in animals that are kept under naturally changing photoperiods). Besides its release in a circadian mode, melatonin is also discharged in a pulsatile manner; the physiological significance, if any, of pulsatile melatonin release remains unknown. The exposure of animals including man to light at night rapidly depresses pineal melatonin synthesis and, therefore, blood melatonin levels drop precipitously. The brightness of light at night required to depress melatonin production is highly species specific. In general, the pineal gland of nocturnally active mammals, which possess rod-dominated retinas, is more sensitive to inhibition by light than is the pineal gland of diurnally active animals (with cone-dominated retinas). Because of the ability of the light/dark cycle to determine melatonin production, the photoperiod is capable of influencing the function of a variety of endocrine and non-endocrine organs. Indeed, melatonin is a ubiquitously acting pineal hormone with its effects on the neuroendocrine system having been most thoroughly investigated. Thus, in nonhuman photoperiodic mammals melatonin regulates seasonal reproduction; in humans also, the indole has been implicated in the control of reproductive physiology.

Reiter, Russel J.

1991-09-01

438

Cataractogenic effects of proton radiation  

E-print Network

CATARACTOGENIC EFFECTS OF PROTON RADIATION A Thesis by James Ronald Kyzar Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1972 Major Subject...: Veterinary Physiology CATARACTOGENIC EFFECTS OF PROTON RADIATION A Thesis by James Ronald Kyzar Approved as to style and content by: (Char of Committee) (Head of Depar ent) (Membei / (Member (Member ) May 1972 ABSTRACT Cataractogenic Effects...

Kyzar, James Ronald

1972-01-01

439

(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

440

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

441

Biomedical effects of laser application  

SciTech Connect

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.

Mester, E.; Mester, A.F.; Mester, A.

1985-01-01

442

Electro-magneto-optical Effects  

Microsoft Academic Search

Electro-magneto-optical effects in stationary materials are observed when the materials are placed in strong, static electric or magnetic fields and an electro- magnetic wave (light) traverses the medium. The Faraday effect is an example of the class of phenomena we have in mind. Clearly, the existence of electro- magneto-optical effects in material media is direct evidence that the equations for

R. A. Toupin; R. S. Rivlin

1961-01-01

443

General Network Effects and Welfare  

E-print Network

involve ‘network effects’ whether direct or indirect. Furthermore, many of the recent models of platform and two-sided markets display reduced form indirect network effects – see e.g. Church et al. (2003).1 Much of this literature has focused, for reasons... of analytical tractability, on the case linear network effects (and heterogeneity).2 It is natural to wonder whether such a restriction is ‘innocent’. In this paper we analyse the case of general network effects. Focusing on the classic case of a Hotelling line...

Pollock, Rufus

444

EFFECTIVE POROSITY IMPLIES EFFECTIVE BULK DENSITY IN SORBING SOLUTE TRANSPORT  

SciTech Connect

The concept of an effective porosity is widely used in solute transport modeling to account for the presence of a fraction of the medium that effectively does not influence solute migration, apart from taking up space. This non-participating volume or ineffective porosity plays the same role as the gas phase in single-phase liquid unsaturated transport: it increases pore velocity, which is useful towards reproducing observed solute travel times. The prevalent use of the effective porosity concept is reflected by its prominent inclusion in popular texts, e.g., de Marsily (1986), Fetter (1988, 1993) and Zheng and Bennett (2002). The purpose of this commentary is to point out that proper application of the concept for sorbing solutes requires more than simply reducing porosity while leaving other material properties unchanged. More specifically, effective porosity implies the corresponding need for an effective bulk density in a conventional single-porosity model. The reason is that the designated non-participating volume is composed of both solid and fluid phases, both of which must be neglected for consistency. Said another way, if solute does not enter the ineffective porosity then it also cannot contact the adjoining solid. Conceptually neglecting the fluid portion of the non-participating volume leads to a lower (effective) porosity. Likewise, discarding the solid portion of the non-participating volume inherently leads to a lower or effective bulk density. In the author's experience, practitioners virtually never adjust bulk density when adopting the effective porosity approach.

Flach, G.

2012-02-27

445

Costs of antibiotic resistance – separating trait effects and selective effects  

PubMed Central

Antibiotic resistance can impair bacterial growth or competitive ability in the absence of antibiotics, frequently referred to as a ‘cost’ of resistance. Theory and experiments emphasize the importance of such effects for the distribution of resistance in pathogenic populations. However, recent work shows that costs of resistance are highly variable depending on environmental factors such as nutrient supply and population structure, as well as genetic factors including the mechanism of resistance and genetic background. Here, we suggest that such variation can be better understood by distinguishing between the effects of resistance mechanisms on individual traits such as growth rate or yield (‘trait effects’) and effects on genotype frequencies over time (‘selective effects’). We first give a brief overview of the biological basis of costs of resistance and how trait effects may translate to selective effects in different environmental conditions. We then review empirical evidence of genetic and environmental variation of both types of effects and how such variation may be understood by combining molecular microbiological information with concepts from evolution and ecology. Ultimately, disentangling different types of costs may permit the identification of interventions that maximize the cost of resistance and therefore accelerate its decline.

Hall, Alex R; Angst, Daniel C; Schiessl, Konstanze T; Ackermann, Martin

2015-01-01

446

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

447

Ecological effects on effective population size in an annual plant.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Nutrient-limited soil can be a strong selective force on plant populations. In addition, ecological factors such as competitive interactions have been shown to have an effect on effective population size (Ne). Both Ne and selection are indicators of population evolutionary processes: selection can...

448

SMITH AND BARGHNONCONSCIOUS EFFECTS OF POWER NONCONSCIOUS EFFECTS OF POWER  

E-print Network

SMITH AND BARGHNONCONSCIOUS EFFECTS OF POWER NONCONSCIOUS EFFECTS OF POWER ON BASIC APPROACH AND AVOIDANCE TENDENCIES Pamela K. Smith Radboud University Nijmegen John A. Bargh Yale University According-24 Address for correspondence: Pamela K. Smith, Department of Social Psychology, Behavioural Science

Bargh, John A.

449

Effective healthcare teams require effective team members: defining teamwork competencies  

Microsoft Academic Search

BACKGROUND: Although effective teamwork has been consistently identified as a requirement for enhanced clinical outcomes in the provision of healthcare, there is limited knowledge of what makes health professionals effective team members, and even less information on how to develop skills for teamwork. This study identified critical teamwork competencies for health service managers. METHODS: Members of a state branch of

Sandra G Leggat

2007-01-01

450

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. PMID:20087340

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

2010-01-01

451

Effects of World War I  

NSDL National Science Digital Library

Determine the effects of World War I on countries involved in the war. In this activity, read the links and use the information given to determine the effects of World War I on the major players in the war. Fill out the graphic organizer with the information you find. Organizer Casualties - Use this site to determine how many soldiers each country lost in ...

Mr. Kilpatrick

2012-04-10

452

Advertisement Takes effect in January  

E-print Network

Advertisement Takes effect in January New law gives seniors more control over their living wills, which takes effect in January, gives Utahns more control over what happens when they experience/29/2007http://www.sltrib.com/news/ci_7537468 #12;Advertisement The new law also lets Utahns choose what action

Tipple, Brett

453

How effective is targeted advertising?  

Microsoft Academic Search

Advertisers are demanding more accurate estimates of the impact of targeted advertisements, yet no study proposes an appropriate methodology to analyze the effectiveness of a targeted advertising campaign, and there is a dearth of empirical evidence on the effectiveness of targeted advertising as a whole. The targeted population is more likely to convert from advertising so the response lift between

Ayman Farahat; Michael C. Bailey

2012-01-01

454

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

455

Counselor Effectiveness Through Radio Communication.  

ERIC Educational Resources Information Center

This study determined the effectiveness of the use of radio as a means of providing immediate feedback on student counselors in a practicum setting. Using a non-equivalent group experimental design, 10 experimental subjects were compared to 10 control subjects with respect to counselor effectiveness. The experimental subjects were given immediate…

Tentoni, Stuart C.

456

Mediating Effects of Social Presence  

Microsoft Academic Search

Networked interactivity is one of the essential factors that differentiate recent online educational games from traditional stand-alone games. However, despite the growing popularity of online educational games, empirical studies about the effects of the networked interactivity are relatively rare. This study tests the effects of networked interactivity on game users' subjective evaluation of learning (sense of competition, satisfaction, and perceived

Kwan Min Lee; Eui Jun Jeong; Seoungho Ryu

457

Teacher Evaluation: Archiving Teaching Effectiveness  

ERIC Educational Resources Information Center

Teacher evaluation is a current hot topic within music education. This article offers strategies for K-12 music educators on how to promote their effectiveness as teachers through archival documentation in a teacher portfolio. Using the Danielson evaluation model (based on four domains of effective teaching practices), examples of music teaching…

Nielsen, Lance D.

2014-01-01

458

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

459

Effects of garlic on atherosclerosis  

Microsoft Academic Search

This review discusses the use of garlic and garlic preparations as agents for prevention and treatment of atherosclerosis and atherosclerosis-related diseases. Garlic indirectly effects atherosclerosis by reduction of hyperlipidemia, hypertension, and probably diabetes mellitus and prevents thrombus formation. In addition, in animal models, garlic causes direct antiatherogenic (preventive) and antiatherosclerotic (causing regression) effects at the level of artery wall. Garlic's

Alexander N. Orekhov; Jörg Grünwald

1997-01-01

460

Effective retrieval with distributed collections  

Microsoft Academic Search

This paper evaluates the retrieval effective- ness of distributed information retrieval systems in re- alistic environments. We find that when a large num- ber of collections are available, the retrieval effectiveness is significantly worse than that of centralized systems, mainly because typical queries are not adequate for the purpose of choosing the right collections. We propose two techniques to address

Jinxi Xu; James P. Callan

1998-01-01

461

The Greenhouse Effect Temperature Equilibrium  

E-print Network

The Greenhouse Effect #12;Temperature Equilibrium The Earth is in equilibrium with the Sun temperature is about 14C, or 287K. The 40K difference is due to the greenhouse effect. Essentially all (Wein's Law). Our atmosphere is not completely transparent at these wavelengths, because the greenhouse

Walter, Frederick M.

462

Switchgrass biochar effects two aridisols  

Technology Transfer Automated Retrieval System (TEKTRAN)

The use of biochar has received growing attention with regards to improving the physico-chemical properties of highly weathered Ultisols and Oxisols, yet very little research has focused on effects in Aridisols. The objective of this study was to investigate the effect of either low or high tempera...

463

Project Title: Prisoner Counselling Effectiveness  

E-print Network

to be evaluated. Based on a review of literature surrounding designing self- assessment survey methods, a review methods and applications of survey methods to evaluate a programmes effectiveness (comparison across review on applications of survey methods to evaluate a programme's effectiveness 12 March ­ 5 April

Hickman, Mark

464

Memory Processes in Media Effects.  

ERIC Educational Resources Information Center

Explores the role of memory in mediating mass communication effects. Examines (1) the nature of memory, (2) issues in retention and recall of media messages, (3) methods of promoting retention and recall of media messages, and (4) implications of memory processes for mass media effects. (PD)

Kellermann, Kathy

1985-01-01

465

Tritrophic Effects in Bt Cotton  

ERIC Educational Resources Information Center

Transgenic insecticidal Bt crops are being increasingly used worldwide, and concern is increasing about resistance and their effects on nontarget organisms. The toxin acts as a weak pesticide and, hence, the effects are subtler than those of chemical biocides. However, the toxin is ever present, but concentrations vary with age of plant and plant…

Gutierrez, Andrew Paul

2005-01-01

466

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

467

7, 39413962, 2007 Volcanic effects  

E-print Network

considered leading to the detection of the so called "continen- tal winter warming" in observations in global circulation mod- 3942 #12;ACPD 7, 3941­3962, 2007 Volcanic effects: climate mechanisms H.-F. GrafACPD 7, 3941­3962, 2007 Volcanic effects: climate mechanisms H.-F. Graf et al. Title Page Abstract

Paris-Sud XI, Université de

468

The Effectiveness of Early Intervention.  

ERIC Educational Resources Information Center

This book reviews research on the effectiveness of early intervention for children with disabilities or who are at risk. Program factors for children at risk and with disabilities, the effects of early intervention on different types of disabilities, and the outcomes of early intervention are explored. Chapters include: "Second-Generation Research…

Guralnick, Michael J., Ed.

469

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

470

Octupole correlation effects in nuclei  

SciTech Connect

Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.

Chasman, R.R.

1992-08-01

471

Octupole correlation effects in nuclei  

SciTech Connect

Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.

Chasman, R.R.

1992-01-01

472

Effects of dance on anxiety  

Microsoft Academic Search

The study investigated the effects of modern dance on anxiety. State anxiety was assessed before and after a 3-mo. education programme, using the Spielberger State-Trait Anxiety Inventory. The target group followed a class in modern dance. Control group were (1) a physical education group to control for the effects of exercise, (2) a music group to control for aesthetic sensitivity

Andre Lesté; John Rust

1990-01-01

473

Immediate Neurocognitive Effects of Concussion  

Microsoft Academic Search

OBJECTIVE: To prospectively measure the immediate neurocognitive effects and early course of recovery from concussion and to examine the effects of loss of consciousness (LOC) and posttraumatic amnesia (PTA) on the severity of neurocognitive impairment immediately after concussion. METHODS: A sports-related concussion research model was used to allow prospective immediate evaluation of concussion. A total of 2385 high school and

Michael McCrea; James P. Kelly; Christopher Randolph; Ron Cisler; Lisa Berger

2002-01-01

474

Teaching the Photoelectric Effect Inductively  

ERIC Educational Resources Information Center

Research has shown that students have difficulty understanding the underlying process of the photoelectric effect. Thus, this study sought to utilize an inductively situated lesson for teaching the photoelectric effect, hypothesizing that this type of enquiry would help learners delve deeper into the principles of the phenomenon and provide a…

Sokolowski, Andrzej

2013-01-01

475

Cumulative effects analysis (CEA) tools  

Technology Transfer Automated Retrieval System (TEKTRAN)

Effective rangeland management requires careful consideration of the possible cumulative effects of different management options prior to making major management decisions. State-and-transition (S/T) models, based on ecological sites, capture our understanding ecosystem functioning and can be used t...

476

Radiation Effects on Spacecraft & Aircraft  

Microsoft Academic Search

Satellite systems are vulnerable to Space Weather through its influence on energetic charged particle and plasma populations, which produce a variety of effects, including total dose, lattice displacement damage, single event effects (SEE), noise in sensors and electrostatic charging. In addition aircraft electronics and aircrew are subjected to atmospheric secondary radiation produced by cosmic rays and solar particle events. European

Clive Dyer

2001-01-01

477

The Participatory Effects of Redistricting  

Microsoft Academic Search

While the effects of legal and institutional arrangements on political participation are well documented, little attention has been given to the potential participatory effects of one of the United States' most important electoral laws: constitutionally mandated reapportionment. By severing the ties between constituents and their incumbents, we argue, redistricting raises information costs, leading to increased levels of nonvoting in U.S.

Danny Hayes; Seth C. McKee

2009-01-01

478

Revisiting the Mysterious Mpemba Effect  

Microsoft Academic Search

The effect of hot water freezing faster than cold water is mentioned in Greek literature. However, it came out as a scientific phenomenon during the last few decades and is known as Mpemba effect since 1969. But there is an inadequacy of explanation which was a challenge to the modern science. Hence, it is an important issue to revisit this

R. P. Gamage; S. R. D. Rosa

2008-01-01

479

How Principals Support Teacher Effectiveness  

ERIC Educational Resources Information Center

The current standards and accountability regime describes effective teaching as the ability to increase student achievement on standardized tests. This narrow definition of effectiveness can lead principals to create school cultures myopically focused on student achievement data. A "laser-like focus on academic achievement," if employed too…

Gallagher, Michael

2012-01-01

480

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

481

THERMOVISCOPLASTICITY WITH SECOND SOUND EFFECTS  

Microsoft Academic Search

Coupled thermoviscoplasticity equations are developed based on the rational theory of thermodynamics. The equations account for the second sound effects and are compatible with the state variable constitutive theories. Second sound effects were considered by adding a new vector, which represents the “elastic” heat flow, to the list of the independent variables required to completely define the state of the

H. Ghoneim; D. N. Dalo

1987-01-01

482

The psychological effects of unemployment  

Microsoft Academic Search

This paper reviews studies dealing with the following: (1) The effects of unemployment upon personality. Unemployment leads to increased instability in the unemployed and lowers their morale. Movie attendance is increased, and personal habits may be somewhat modified. Methodological approaches to a study of the effect on the total personality are discussed, but no data are cited. (2) Socio-political attitudes

P. Eisenberg; Paul F. Lazarsfeld

1938-01-01

483

Casimir effect: Edges and diffraction  

Microsoft Academic Search

The Casimir effect refers to the existence of a macroscopic force between conducting plates in vacuum due to quantum fluctuations of fields. These forces play an important role, among other things, in the design of nano-scale mechanical devices. Accurate experimental observations of this phenomenon have motivated the development of new theoretical approaches in dealing with the effects of different geometries,

Dimitra Karabali

2011-01-01

484

Casimir effect: Edges and diffraction  

Microsoft Academic Search

The Casimir effect refers to the existence of a macroscopic force between conducting plates in vacuum due to quantum fluctuations of fields. These forces play an important role, among other things, in the design of nano-scale mechanical devices. Accurate experimental observations of this phenomenon have motivated the development of new theoretical approaches in dealing with the effects of different geometries,

Dimitra Karabali

2012-01-01

485

Effective doses, guidelines & regulations.  

PubMed

A number of countries have developed regulations or guidelines for cyanotoxins and cyanobacteria in drinking water, and in some cases in water used for recreational activity and agriculture. The main focus internationally has been upon microcystin toxins, produced predominantly by Microcystis aeruginosa. This is because microcystins are widely regarded as the most significant potential source of human injury from cyanobacteria on a world-wide scale. Many international guidelines have taken their lead from the World Health Organization's (WHO) provisional guideline of 1 microg L(-1) for microcystin-LR in drinking-water released in 1998 (WHO 2004). The WHO guideline value is stated as being 'provisional', because it covers only microcystin-LR, for reasons that the toxicology is limited and new data for toxicity of cyanobacterial toxins are being generated. The derivation of this guideline is based upon data that there is reported human injury related to consumption of drinking water containing cyanobacteria, or from limited work with experimental animals. It was also recognised that at present the human evidence for microcystin tumor promotion is inadequate and animal evidence is limited. As a result the guideline is based upon the model of deriving a Tolerable Daily intake (TDI) from an animal study No Observed Adverse Effects Level (NOAEL), with the application of appropriate safety or uncertainty factors. The resultant WHO guideline by definition is the concentration of a toxin that does not result in any significant risk to health of the consumer over a lifetime of consumption. Following the release of this WHO provisional guideline many countries have either adopted it directly (e.g., Czech Republic, France, Japan, Korea, New Zealand, Norway, Poland, Brazil and Spain), or have adopted the same animal studies, TDI and derivation convention to arrive at slight variants based upon local requirements (e.g., Australia, Canada). Brazil currently has the most comprehensive federal legislation which includes a mandatory standard of 1 microg L-(1) for microcystins, and also recommendations for saxitoxins (3 microg L(-1)) and for cylindrospermopsin (15 microg L(-1)). Although guidelines for cyanotoxins and cyanobacterial cell numbers for recreational waters are in place in a number of countries, it is consid ered that there is currently insufficient information to derive sound guidelines for the use of water contaminated by cyanobacteria or toxins for agricultural production, fisheries and ecosystem protection. In relation to the need for specific regulations for toxins for the US, the surveys that have been carried out to date would indicate that the priority compounds for regulation, based upon their incidence and distribution, are microcystins, cylindrospermopsin and Anatoxin-a. Additional research is required to support guideline development, including whole-of-life animal studies with each of the known cyanotoxins. In view of the animal studies that indicate that microcystins may act as tumor promoters, and also some evidence of genotoxicity and carcinogenicity for cylindrospermopsin, it may be appropriate to carry out whole-of-life animal studies with both toxicity and carcinogenicity as end-points. In relation to microcystins, it is known that there a large number of congeners, and the toxico-dynamics and kinetics of these variants are not well understood. Further research is needed to consider the approach to take in formulating health advisories or regulations for toxin mixtures, i.e. multiple microcystins, or mixtures of toxin types. An important requirement for regulation is the availability of robust monitoring and analytical protocols for toxins. Currently rapid and economical screening or quantitative analytical methods are not available to the water industry or natural resource managers, and this is a priority before the release of guidelines and regulations. There is insufficient information available in a range of the categories usually required to satisfy comprehensive risk assessment process for the major tox

Burch, Michael D

2008-01-01

486

Relativistic effect in galaxy clustering  

NASA Astrophysics Data System (ADS)

The general relativistic description of galaxy clustering provides a complete and unified treatment of all the effects in galaxy clustering such as the redshift-space distortion, gravitational lensing, Sachs-Wolfe effects, and their relativistic effects. In particular, the relativistic description resolves the gauge issues in the standard Newtonian description of galaxy clustering by providing the gauge-invariant expression for the observed galaxy number density. The relativistic effect in galaxy clustering is significant on large scales, in which dark energy models or alternative theories of modified gravity deviate from general relativity. In this paper, we review the relativistic effect in galaxy clustering by providing a pedagogical derivation of the relativistic formula and by computing the observed galaxy two-point statistics. The relativistic description of galaxy clustering is an essential tool for testing general relativity and probing the early Universe on large scales in the era of precision cosmology.

Yoo, Jaiyul

2014-12-01

487

Phi-symmetric effect algebras  

NASA Astrophysics Data System (ADS)

The notion of a Sasaki projection on an orthomodular lattice is generalized to a mapping ?: E × E ? E, where E is an effect algebra. If E is lattice ordered and ? is symmetric, then E is called a ?-symmetric effect algebra. This paper launches a study of such effect algebras. In particular, it is shown that every interval effect algebra with a lattice-ordered ambient group is ?-symmetric, and its group is the one constructed by Ravindran in his proof that every effect algebra that has the Riesz decomposition property is an interval algebra. It is shown that the doubling construction introduced in the paper is connected to the conditional event algebras of Goodman, Nguyen, and Walker.

Bennett, M. K.; Foulis, D. J.

1995-12-01

488

Effective 1.0: An Analytic Effective Action Analysis Library  

E-print Network

Effective is a C++ library which provides the user a toolbox to study the effective action of an arbitrary field theory. From the field content, gauge groups and representations an appropriate action is generated symbolically. The effective potential, mass spectrum, field couplings and vacuum expectation values are then obtained automatically; tree level results are obtained analytically while many tools, both numeric and analytic, provide a variety of approaches to deal with the one-loop corrections. This article provides a guide for users to who wish to analyze their own models using Effective. This is done by presenting the code required and describing the physics assumptions behind the code. The library can be extended in many ways and discussion of several such extensions is also provided.

James P. J. Hetherington; Philip Stephens

2006-05-12

489

Effects of therapists nonverbal communication on rated skill and effectiveness.  

PubMed

A therapist's nonverbal behavior may communicate emotion and feelings toward a client. Thus, skilled utilization of appropriate nonverbal cues should facilitate many nonbehavioral therapies. A 2 X 2 X 2 factorial experiment investigated the therapy-facilitating effects of three theoretical dimensions of nonverbal communication: Immediacy, potency or status, and responsivity. A reenacted client-centered therapy session was videotaped. Verbal content was held constant, but all combinations of the three nonverbal dimensions were portrayed. A total of 118 male and female nonparticipant observers rated the therapist's interpersonal skills (empathy, warmth, and genuineness) and effectiveness. The results disclosed that the nonverbal cues of immediacy (close therapist-client distance and eye contact) significantly improved ratings of the therapist's interpersonal skills and effectiveness. Thus, the study demonstrated that a therapist's nonverbal behavior is a basis for interpretations of empathy, warmth, genuiness, and effectiveness. These findings were interpreted in terms of the therapist's nonverbal cues communicating liking and acceptance of the client. PMID:7410567

Sherer, M; Rogers, R W

1980-07-01

490

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 DCA, BDCM, chloral hydrate and DBA. Population-based field studies to identify human male reproductive risks of DBPs require preliminary work to develop specific epidemiologi...

491

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...

492

Aldol Reactions - Isotope Effects, Mechanism and Dynamic Effects  

E-print Network

The mechanism of three important aldol reactions and a biomimetic transamination is investigated using a combination of experimental kinetic isotope effects (KIEs), standard theoretical calculations and dynamics trajectory simulations. This powerful...

Vetticatt, Mathew J.

2011-02-22

493

Cadmium and Its Neurotoxic Effects  

PubMed Central

Cadmium (Cd) is a heavy metal that has received considerable concern environmentally and occupationally. Cd has a long biological half-life mainly due to its low rate of excretion from the body. Thus, prolonged exposure to Cd will cause toxic effect due to its accumulation over time in a variety of tissues, including kidneys, liver, central nervous system (CNS), and peripheral neuronal systems. Cd can be uptaken from the nasal mucosa or olfactory pathways into the peripheral and central neurons; for the latter, Cd can increase the blood brain barrier (BBB) permeability. However, mechanisms underlying Cd neurotoxicity remain not completely understood. Effect of Cd neurotransmitter, oxidative damage, interaction with other metals such as cobalt and zinc, estrogen-like, effect and epigenetic modification may all be the underlying mechanisms. Here, we review the in vitro and in vivo evidence of neurotoxic effects of Cd. The available finding indicates the neurotoxic effects of Cd that was associated with both biochemical changes of the cell and functional changes of central nervous system, suggesting that neurotoxic effects may play a role in the systemic toxic effects of the exposure to Cd, particularly the long-term exposure. PMID:23997854

Wang, Bo; Du, Yanli

2013-01-01

494

Late effects from hadron therapy  

SciTech Connect

Successful cancer patient survival and local tumor control from hadron radiotherapy warrant a discussion of potential secondary late effects from the radiation. The study of late-appearing clinical effects from particle beams of protons, carbon, or heavier ions is a relatively new field with few data. However, new clinical information is available from pioneer hadron radiotherapy programs in the USA, Japan, Germany and Switzerland. This paper will review available data on late tissue effects from particle radiation exposures, and discuss its importance to the future of hadron therapy. Potential late radiation effects are associated with irradiated normal tissue volumes at risk that in many cases can be reduced with hadron therapy. However, normal tissues present within hadron treatment volumes can demonstrate enhanced responses compared to conventional modes of therapy. Late endpoints of concern include induction of secondary cancers, cataract, fibrosis, neurodegeneration, vascular damage, and immunological, endocrine and hereditary effects. Low-dose tissue effects at tumor margins need further study, and there is need for more acute molecular studies underlying late effects of hadron therapy.

Blakely, Eleanor A.; Chang, Polly Y.

2004-06-01

495

Effective-surface-energy approach for size effects in ferroics  

NASA Astrophysics Data System (ADS)

We present a simple approach enabling analytical treatments of size effects in ferroelectric samples of complicated shapes for the cases where long-range depolarizing effects are not involved. The key element of the approach is the presentation of the energy of the system as the sum of the bulk and effective surface energy (like in the classical nucleation problem), while the latter is expressed as a function of the bulk value of the order parameter. The effective surface energy is calculated in terms of the Kretschmer-Binder framework. The size-driven shift of TC in the ferroelectric thin films with in-plane polarization and the nanowires with axial polarization is studied using the proposed approach and the results are compared with those exact. In the limit of large extrapolation length, the approach reproduces the exact results (analytical and numerical). For short extrapolation lengths, it can provide a good approximation to the exact results for the case of second-order phase transitions. For ferroelectrics with the first-order phase transition having the maximal correlation length smaller than the extrapolation length (a common situation in perovskites), the approach provides as well an appropriate description of the size effect on the transition temperature. The proposed approach can be used for the description of the size effect not only in ferroelectrics, but in other ferroics as well.

Wang, Jin; Tagantsev, Alexander K.; Setter, Nava

2015-03-01

496

Rotating structures and Bryan's effect  

NASA Astrophysics Data System (ADS)

In 1890 Bryan observed that when a vibrating structure is rotated the vibrating pattern rotates at a rate proportional to the rate of rotation. During investigations of the effect in various solid and fluid-filled objects of various shapes, an interesting commonality was found in connection with the gyroscopic effects of the rotating object. The effect has also been discussed in connection with a rotating fluid-filled wineglass. A linear theory is developed, assuming that the rotation rate is constant and much smaller than the lowest eigenfrequency of the vibrating system. The associated physics and mathematics are easy enough for undergraduate students to understand.

Joubert, Stephan V.; Shatalov, Michael Y.; Fay, Temple H.

2009-06-01

497

Casimir effect: Edges and diffraction  

E-print Network

The Casimir effect refers to the existence of a macroscopic force between conducting plates in vacuum due to quantum fluctuations of fields. These forces play an important role, among other things, in the design of nano-scale mechanical devices. Accurate experimental observations of this phenomenon have motivated the development of new theoretical approaches in dealing with the effects of different geometries, temperature etc. In this talk, I will focus on a new method we have developed in calculating the contribution to the Casimir effect due to diffraction from edges and holes in different geometries, at zero and at finite temperature.

Dimitra Karabali

2011-11-03

498

Novel effects of nitric oxide  

NASA Technical Reports Server (NTRS)

Nitric oxide (NO), a simple free radical gas, elicits a surprisingly wide range of physiological and pathophysiological effects. NO interacts with soluble guanylate cyclase to evoke many of these effects. However, NO can also interact with molecular oxygen and superoxide radicals to produce reactive nitrogen species that can modify a number of macromolecules including proteins, lipids, and nucleic acids. NO can also interact directly with transition metals. Here, we have reviewed the non--3',5'-cyclic-guanosine-monophosphate-mediated effects of NO including modifications of proteins, lipids, and nucleic acids.

Davis, K. L.; Martin, E.; Turko, I. V.; Murad, F.

2001-01-01

499

Environmental effects on spacecraft materials  

NASA Technical Reports Server (NTRS)

The effects on the natural space environments on materials are presented, which may be used for SDI applications. The current state-of-the-art knowledge of those effects was studied, and a literature search, a questionnaire mailing, and some visits to NASA and Air Force research facilities were performed. Phase 2 will be a study of what materials may be used for SDI applications and to what natural space environments they may be vulnerable. Deficiencies in knowledge of the effects of the natural space environments on these materials are to be identified and recommendations are to be made to eliminate these knowledge deficiencies.

Haffner, J. W.

1989-01-01

500

Pharmacological Effects of Rosa Damascena  

PubMed Central

Rosa damascena mill L., known as Gole Mohammadi in is one of the most important species of Rosaceae family flowers. R. damascena is an ornamental plant and beside perfuming effect, several pharmacological properties including anti-HIV, antibacterial, antioxidant, antitussive, hypnotic, antidiabetic, and relaxant effect on tracheal chains have been reported for this plant. This article is a comprehensive review on pharmacological effects of R. damascena. Online literature searches were performed using Medline, medex, Scopus, and Google Scholar websites backed to 1972 to identify researches about R. damascena. Searches also were done by going through the author's files and the bibliographies of all located papers. PMID:23493250

Boskabady, Mohammad Hossein; Shafei, Mohammad Naser; Saberi, Zahra; Amini, Somayeh

2011-01-01