Tuning the electrocaloric enhancement near the morphotropic phase boundary in lead-free ceramics

PubMed Central

Le Goupil, Florian; McKinnon, Ruth; Koval, Vladimir; Viola, Giuseppe; Dunn, Steve; Berenov, Andrey; Yan, Haixue; Alford, Neil McN.

2016-01-01

The need for more energy-efficient and environmentally-friendly alternatives in the refrigeration industry to meet global emission targets has driven efforts towards materials with a potential for solid state cooling. Adiabatic depolarisation cooling, based on the electrocaloric effect (ECE), is a significant contender for efficient new solid state refrigeration techniques. Some of the highest ECE performances reported are found in compounds close to the morphotropic phase boundary (MPB). This relationship between performance and the MPB makes the ability to tune the position of the MPB an important challenge in electrocaloric research. Here, we report direct ECE measurements performed on MPB tuned NBT-06BT bulk ceramics with a combination of A-site substitutions. We successfully shift the MPB of these lead-free ceramics closer to room temperature, as required for solid state refrigeration, without loss of the criticality of the system and the associated ECE enhancement. PMID:27312287

Tuning the electrocaloric enhancement near the morphotropic phase boundary in lead-free ceramics.

PubMed

Le Goupil, Florian; McKinnon, Ruth; Koval, Vladimir; Viola, Giuseppe; Dunn, Steve; Berenov, Andrey; Yan, Haixue; Alford, Neil McN

2016-06-17

The need for more energy-efficient and environmentally-friendly alternatives in the refrigeration industry to meet global emission targets has driven efforts towards materials with a potential for solid state cooling. Adiabatic depolarisation cooling, based on the electrocaloric effect (ECE), is a significant contender for efficient new solid state refrigeration techniques. Some of the highest ECE performances reported are found in compounds close to the morphotropic phase boundary (MPB). This relationship between performance and the MPB makes the ability to tune the position of the MPB an important challenge in electrocaloric research. Here, we report direct ECE measurements performed on MPB tuned NBT-06BT bulk ceramics with a combination of A-site substitutions. We successfully shift the MPB of these lead-free ceramics closer to room temperature, as required for solid state refrigeration, without loss of the criticality of the system and the associated ECE enhancement.

Giant electrocaloric and energy storage performance of [(K0.5Na0.5)NbO3](1-x)-[LiSbO3] x nanocrystalline ceramics.

PubMed

Kumar, Raju; Singh, Satyendra

2018-02-16

Electrocaloric (EC) refrigeration, an EC effect based technology has been accepted as an auspicious way in the development of next generation refrigeration due to high efficiency and compact size. Here, we report the results of our experimental investigations on electrocaloric response and electrical energy storage properties in lead-free nanocrystalline (1 - x)K 0.5 Na 0.5 NbO 3 -xLiSbO 3 (KNN-xLS) ceramics in the range of 0.015 ≤ x ≤ 0.06 by the indirect EC measurements. Doping of LiSbO 3 has lowered both the transitions (T C and T O-T ) of KNN to the room temperature side effectively. A maximal value of EC temperature change, ΔT = 3.33 K was obtained for the composition with x = 0.03 at 345 K under an external electric field of 40 kV/cm. The higher value of EC responsivity, ζ = 8.32 × 10 -7  K.m/V is found with COP of 8.14 and recoverable energy storage of 0.128 J/cm 3 with 46% efficiency for the composition of x = 0.03. Our investigations show that this material is a very promising candidate for electrocaloric refrigeration and energy storage near room temperature.

Why is the electrocaloric effect so small in ferroelectrics?

DOE PAGES

Guzmán-Verri, G. G.; Littlewood, P. B.

2016-05-19

Ferroelectrics are attractive candidate materials for environmentally friendly solid state refrigeration free of greenhouse gases. Their thermal response upon variations of external electric fields is largest in the vicinity of their phase transitions, which may occur near room temperature. The magnitude of the effect, however, is too small for useful cooling applications even when they are driven close to dielectric breakdown. Insight from microscopic theory is therefore needed to characterize materials and provide guiding principles to search for new ones with enhanced electrocaloric performance. Here, we derive from well-known microscopic models of ferroelectricity meaningful figures of merit for a widemore » class of ferroelectric materials. Such figures of merit provide insight into the relation between the strength of the effect and the characteristic interactions of ferroelectrics such as dipolar forces. We find that the long range nature of these interactions results in a small effect. A strategy is proposed to make it larger by shortening the correlation lengths of fluctuations of polarization. In addition, we bring into question other widely used but empirical figures of merit and facilitate understanding of the recently observed secondary broad peak in the electrocalorics of relaxor ferroelectrics.« less

Colossal Room-Temperature Electrocaloric Effect in Ferroelectric Polymer Nanocomposites Using Nanostructured Barium Strontium Titanates.

PubMed

Zhang, Guangzu; Zhang, Xiaoshan; Yang, Tiannan; Li, Qi; Chen, Long-Qing; Jiang, Shenglin; Wang, Qing

2015-07-28

The electrocaloric effect (ECE) refers to conversion of thermal to electrical energy of polarizable materials and could form the basis for the next-generation refrigeration and power technologies that are highly efficient and environmentally friendly. Ferroelectric materials such as ceramic and polymer films exhibit large ECEs, but each of these monolithic materials has its own limitations for practical cooling applications. In this work, nanosized barium strontium titanates with systematically varied morphologies have been prepared to form polymer nanocomposites with the ferroelectric polymer matrix. The solution-processed polymer nanocomposites exhibit an extraordinary room-temperature ECE via the synergistic combination of the high breakdown strength of a ferroelectric polymer matrix and the large change of polarization with temperature of ceramic nanofillers. It is found that a sizable ECE can be generated under both modest and high electric fields, and further enhanced greatly by tailoring the morphology of the ferroelectric nanofillers such as increasing the aspect ratio of the nanoinclusions. The effect of the geometry of the nanofillers on the dielectric permittivity, polarization, breakdown strength, ECE and crystallinity of the ferroelectric polymer has been systematically investigated. Simulations based on the phase-field model have been carried out to substantiate the experimental results. With the remarkable cooling energy density and refrigerant capacity, the polymer nanocomposites are promising for solid-state cooling applications.

Temperature dependences of the electromechanical and electrocaloric properties of Ba(Zr,Ti)O3 and (Ba,Sr)TiO3 ceramics

NASA Astrophysics Data System (ADS)

Maiwa, Hiroshi

2017-10-01

The electrocaloric properties of Ba(Zr,Ti)O3 and (Ba,Sr)TiO3 ceramics (BZT and BST, respectively) were investigated by the indirect estimation and direct measurement of temperature-electric field (T-E) hysteresis loops. The measured T-E loops had shapes similar to those of the strain-electric field (s-E) loops. The measured temperature changes (ΔTs) at around 30 °C of the BZT ceramics sintered at 1450 °C and BST ceramics sintered at 1600 °C upon the release of the electric field from 30 kV/cm to 0 were 0.34 and 0.57 K, respectively. The temperature dependences of the electromechanical and electrocaloric properties were investigated. The BZT ceramics sintered at 1450 °C exhibited the largest electromechanical and electrocaloric properties at around 30 °C, which corresponds to the phase transition temperature. BST is more temperature dependent than BZT. BST ceramics sintered at 1600 °C exhibited the largest electromechanical and electrocaloric properties at around 29 °C, which is about 10 °C higher than the phase transition temperature.

Energy-storage properties and electrocaloric effect of Pb(1-3x/2)LaxZr0.85Ti0.15O3 antiferroelectric thick films.

PubMed

Zhao, Ye; Hao, Xihong; Zhang, Qi

2014-07-23

Antiferroelectric (AFE) thick (1 μm) films of Pb(1-3x/2)LaxZr0.85Ti0.15O3 (PLZT) with x = 0.08, 0.10, 0.12, and 0.14 were deposited on LaNiO3/Si (100) substrates by a sol-gel method. The dielectric properties, energy-storage performance, electrocaloric effect, and leakage current behavior were investigated in detail. With increasing La content, dielectric constant and saturated polarizations of the thick films were gradually decreased. A maximum recoverable energy-storage density of 38 J/cm(3) and efficiency of 71% were achieved in the thick films with x = 0.12 at room temperature. A large reversible adiabatic temperature change of ΔT = 25.0 °C was presented in the thick films with x = 0.08 at 127 °C at 990 kV/cm. Moreover, all the samples had a lower leakage current density below 10(-6) A/cm(2) at room temperature. These results indicated that the PLZT AFE thick films could be a potential candidate for applications in high energy-storage density capacitors and cooling devices.

Detecting giant electrocaloric properties of ferroelectric SbSI at room temperature

NASA Astrophysics Data System (ADS)

Hamad, Mahmoud A.

2013-05-01

In this work, ferroelectric SbSI shows a giant electrocaloric effect at room temperature under very low electric field shift of 0.37 kV cm-1. It is shown that the cooling ΔT per unit field MVm-1 is 2.97. This value is significantly larger, and is comparable with the value of 0.254 for PbZr0.95Ti0.05O3 thin film under electric field shift of 30 kV cm-1. Moreover, the reduction in operating temperature opens up many more possibilities and widens the potential for applications in cooling systems.

Unification of the negative electrocaloric effect in Bi{sub 1/2}Na{sub 1/2}TiO{sub 3}-BaTiO{sub 3} solid solutions by Ba{sub 1/2}Sr{sub 1/2}TiO{sub 3} doping

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

Uddin, Sarir; Materials Research Laboratory, Institute of Physics and Electronics, University of Peshawar, Peshawar 25120; Zheng, Guang-Ping, E-mail: mmzheng@polyu.edu.hk

2013-12-07

The microscopic mechanisms of the negative electrocaloric effect (ECE) of the single-phase (1−x)(0.94Bi{sub 1/2}Na{sub 1/2}TiO{sub 3}-0.06BaTiO{sub 3})-xBa{sub 1/2}Sr{sub 1/2}TiO{sub 3} (BNT-BT-BST) perovskite solid solutions fabricated via the sol-gel technique are explored in this study. Dielectric and mechanical relaxation analyses are employed to investigate the ferroelectric and structural transitions of the samples. The electrocaloric properties of the samples were measured by thermodynamics Maxwell relations. The difference between the depolarization temperature (T{sub d}) and the maximum dielectric constant temperature (T{sub m}) was found to decrease with increasing BST content. Doping with BST stabilized the ferroelectric phase along with unifying the EC temperaturemore » changes (ΔT) to only negative values. The origin of the uniform negative ECE of BNT-BT-BST is discussed.« less

Electrocaloric effects in the lead-free Ba (Zr ,Ti )O3 relaxor ferroelectric from atomistic simulations

NASA Astrophysics Data System (ADS)

Jiang, Zhijun; Prokhorenko, Sergei; Prosandeev, Sergey; Nahas, Y.; Wang, D.; Íñiguez, Jorge; Defay, E.; Bellaiche, L.

2017-07-01

Atomistic effective Hamiltonian simulations are used to investigate electrocaloric (EC) effects in the lead-free Ba (Zr0.5Ti0.5)O3 (BZT) relaxor ferroelectric. We find that the EC coefficient varies nonmonotonically with the field at any temperature, presenting a maximum that can be traced back to the behavior of BZT's polar nanoregions. We also introduce a simple Landau-based model that reproduces the EC behavior of BZT as a function of field and temperature, and which is directly applicable to other compounds. Finally, we confirm that, for low temperatures (i.e., in nonergodic conditions), the usual indirect approach to measure the EC response provides an estimate that differs quantitatively from a direct evaluation of the field-induced temperature change.

Giant electrocaloric response in the prototypical Pb(Mg,Nb)O3 relaxor ferroelectric from atomistic simulations

NASA Astrophysics Data System (ADS)

Jiang, Zhijun; Nahas, Y.; Prokhorenko, S.; Prosandeev, S.; Wang, D.; Íñiguez, Jorge; Bellaiche, L.

2018-03-01

An atomistic effective Hamiltonian is used to investigate electrocaloric (EC) effects of Pb (Mg1 /3Nb2 /3) O3 relaxor ferroelectrics in its ergodic regime, and subject to electric fields applied along the pseudocubic [111] direction. Such a Hamiltonian qualitatively reproduces (i) the electric field-versus-temperature phase diagram, including the existence of a critical point where first-order and second-order transitions meet each other; and (ii) a giant EC response near such a critical point. It also reveals that such giant response around this critical point is microscopically induced by field-induced percolation of polar nanoregions. Moreover, it is also found that, for any temperature above the critical point, the EC coefficient-versus-electric-field curve adopts a maximum (and thus larger electrocaloric response too), that can be well described by the general Landau-like model proposed by Jiang et al., [Phys. Rev. B 96, 014114 (2017)], 10.1103/PhysRevB.96.014114, and that is further correlated with specific microscopic features related to dipoles lying along different rhombohedral directions. Furthermore, for temperatures being at least 40 K higher than the critical temperature, the (electric field, temperature) line associated with this maximal EC coefficient is below both the Widom line and the line representing percolation of polar nanoregions.

Large heat flux in electrocaloric multilayer capacitors

NASA Astrophysics Data System (ADS)

Faye, Romain; Strozyk, Hervé; Dkhil, Brahim; Defay, Emmanuel

2017-11-01

Multi layer capacitors (MLCs) are considered the most promising refrigerant elements for the design and development of electrocaloric cooling devices. Recently, the heat transfer of these MLCs has been considered. However, the heat exchange with the surrounding environment has been poorly addressed. In this work, we measure by infrared thermography the temperature change versus time in four different heat exchange configurations. Depending on the configurations, Newtonian and non-Newtonian regimes with their corresponding Biot number are determined, providing useful thermal characteristics. Indeed, in the case of large area thermal pad contacts, heat transfer coefficients up to 3400 W · m-2 · K-1 were obtained, showing that the standard (non-optimised) MLCs already reach the needs for designing efficient prototypes. We also determined the ideal Brayton cooling power in case of thick wires contact that varied between 3.4 mW and 9.8 mW for operating frequencies varying from 0.25 Hz to 1 Hz. While only heat conduction was considered here, our work provides some design rules for improving heat exchanges in future devices.

High-frequency intrinsic dynamics of the electrocaloric effect from direct atomistic simulations

NASA Astrophysics Data System (ADS)

Lisenkov, S.; Ponomareva, I.

2018-05-01

We propose a computational methodology capable of harvesting isothermal heat and entropy change in molecular dynamics simulations. The methodology is applied to study high-frequency dynamics of the electrocaloric effect (ECE) in ferroelectric PbTiO3. ECE is associated with a reversible change in temperature under adiabatic application of electric field or with a reversible change in entropy under isothermal application of the electric field. Accurate assessment of electrocaloric performance requires the knowledge of three quantities: isothermal heat, isothermal entropy change, and adiabatic temperature change. Our methodology allows computations of all these quantities directly, that is, without restoring to the reversible thermodynamical models. Consequently, it captures both reversible and irreversible effects, which is critical for ECE simulations. The approach is well suited to address the dynamics of the ECE, which so far remains underexplored. We report the following basic features of the intrinsic dynamics of ECE: (i) the ECE is independent of the electric field frequency, rate of application, or field profile; (ii) the effect persists up to the frequencies associated with the onset of dielectric losses and deteriorates from there due to the creation of irreversible entropy; and (iii) in the vicinity of the phase transition and in the paraelectric phase the onset of irreversible dynamics occurs at lower frequency as compared to the ferroelectric phase. The latter is attributed to lower intrinsic soft-mode frequencies and and larger losses in the paraelectric phase.

Dynamic temperature response of electrocaloric multilayer capacitors

NASA Astrophysics Data System (ADS)

Kwon, Beomjin; Roh, Im-Jun; Baek, Seung-Hyub; Keun Kim, Seong; Kim, Jin-Sang; Kang, Chong-Yun

2014-05-01

We measure and model the dynamic temperature response of electrocaloric (EC) multilayer capacitors (MLCs) which have been recently highlighted as novel solid-state refrigerators. The MLC temperature responses depend on the operation voltage waveform, thus we consider three types of voltage waveforms, which include square, triangular, and trapezoidal. Further, to implement an effective refrigeration cycle, the waveform frequency and duty cycle should be carefully chosen. First, our model is fitted to the measurements to evaluate an effective EC power and thermal properties, and calculates an effective cooling power for an EC MLC. The prediction shows that for a MLC with a thermal relaxation time for cooling, trc, a square voltage waveform with a duty cycle of 0 < d ≤ 0.3 and a period of trc < P ≤ 1.4trc provides the maximum cooling power. This work will help to improve the implementing methods for EC refrigeration cycles.

Direct measurement of the electrocaloric effect in poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymer films

NASA Astrophysics Data System (ADS)

Basso, Vittorio; Russo, Florence; Gerard, Jean-François; Pruvost, Sébastien

2013-11-01

We investigated the entropy change in poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) films in the temperature range between -5 ∘C and 60 ∘C by direct heat flux calorimetry using Peltier cell heat flux sensors. At the electric field E = 50 MVm-1 the isothermal entropy change attains a maximum of |Δs|=4.2 Jkg-1K-1 at 31∘C with an adiabatic temperature change ΔTad=1.1 K. At temperatures below the maximum, in the range from 25 ∘C to -5 ∘C, the entropy change |Δs | rapidly decreases and the unipolar P vs E relationship becomes hysteretic. This phenomenon is interpreted as the fact that the fluctuations of the polar segments of the polymer chain, responsible for the electrocaloric effect ECE in the polymer, becomes progressively frozen below the relaxor transition.

Phase transformations, anisotropic pyroelectric energy harvesting and electrocaloric properties of (Pb,La)(Zr,Sn,Ti)O3 single crystals.

PubMed

Zhuo, Fangping; Li, Qiang; Gao, Jinghan; Yan, Qingfeng; Zhang, Yiling; Xi, Xiaoqing; Chu, Xiangcheng

2017-05-31

(Pb,La)(Zr,Sn,Ti)O 3 (PLZST) single crystals with their chemical composition located at the tetragonal antiferroelectric region are grown via the flux method in a PbO-PbF 2 -B 2 O 3 mixture. Segregation of the Ti 4+ component in the as-grown crystals is observed due to the strong affinity between the oxygen anion and Ti 4+ ions. The critical electric field of the antiferroelectric to ferroelectric phase transition is determined to be about 0.5 kV mm -1 . The electric field induced ferroelectric phase transforms back into the antiferroelectric phase at a depolarization temperature of 125 °C. Anisotropy of the harvested energy density and electrocaloric behaviors are achieved for the [100], [110] and [111]-oriented PLZST crystals. Based on the thermodynamic theory approach, all the abovementioned behaviors originate from the anisotropic total entropy change. Enhanced electrocaloric strength (0.3 K mm kV -1 ) and the harvested energy density of 0.62 J cm -3 are obtained in the [111]-oriented PLZST crystals. Our results demonstrate the competence of PLZST single crystals for cooling devices and pyroelectric energy harvesting and provide new opportunities to improve energy harvesting density and electrocaloric properties via the anisotropic structural layout, which make the PLZST crystals attractive for solid state cooling devices and energy conversion technologies.

Giant negative electrocaloric effect in PbZrO3/0.88BaTiO3-0.12Bi(Mg1/2,Ti1/2)O3 multilayered composite ferroelectric thin film for solid-state refrigeration

NASA Astrophysics Data System (ADS)

Huang, D.; Wang, J. B.; Zhong, X. L.; Li, B.; Zhang, Y.; Jin, C.; Zheng, D. F.; Meng, X. J.

2017-11-01

A giant negative electrocaloric (EC) effect in a PbZrO3/(0.88BaTiO3-0.12 Bi(Mg1/2,Ti1/2)O3) (PZ/(BT-BMT)) multilayered composite ferroelectric (MCFE) thin film which is grown on Pt(111)/Ti/SiO2/Si(100) substrates by the sol-gel method is investigated in this work. The negative EC effect in the PZ/(BMT-BT) MCFE thin film is greatly higher than that in the PZ AFE thin film with an adiabatic temperature change (ATC) ΔT = 1.5 K. The ATC ΔT of the PZ/(BMT-BT) MCFE thin film is -32 K under the applied electric field change ΔE = 1151 kV/cm. The result is conducive to enhance the EC refrigeration efficiency greatly.

Why is the electrocaloric effect so small in ferroelectrics?

NASA Astrophysics Data System (ADS)

Guzman-Verri, Gian G.; Littlewood, Peter B.

2015-03-01

Ferroelectrics are attractive candidate materials for environmentally friendly solid state refrigeration free of greenhouse gases. Their thermal response upon variations of external electric fields is largest in the vicinity of their phase transitions, which may occur near room temperature. The magnitude of the effect, however, is too small for useful cooling applications even when they are driven close to dielectric breakdown. Insight from microscopic theory is therefore needed to characterize materials and provide guiding principles to search for new ones with enhanced electrocaloric performance. Here, we present meaningful figures of merit derived from well-known microscopic models of ferroelectricity which provide insight into the relation between the strength of the effect and the characteristic interactions of ferroelectrics such as dipole forces. We find that the long range nature of these interactions results in a small effect. A strategy is proposed to make it larger by shortening the correlation lengths of fluctuations of polarization. Work at Argonne is supported by the U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.

Oriented polyvinylidene fluoride–trifluoroethylene (P(VDF–TrFE)) films by Langmuir–Blodgett deposition: A synchrotron X-ray diffraction study

DOE PAGES

Lindemann, W. R.; Philiph, R. L.; Chan, D. W. W.; ...

2015-10-07

Langmuir–Blodgett films of polyvinylidene fluoride trifluoroethylene – P(VDF–TrFE)-copolymers possess substantially improved electrocaloric and pyroelectric properties, when compared with conventionally spin-cast films. In order to rationalize this, we prepared single-layered films of P(VDF–TrFE) (70:30) using both deposition techniques. Grazing incidence wide-angle X-ray scattering (GIWAXS), reveals that Langmuir–Blodgett deposited films have a higher concentration of the ferroelectric β-phase crystals, and that these films are highly oriented with respect to the substrate. Based on these observations, we suggest alternative means of deposition, which may substantially enhance the electrocaloric effect in P(VDF–TrFE) films. As a result, this development has significant implications for the potentialmore » use of P(VDF–TrFE) in solid-state refrigeration.« less

Towards multicaloric effect with ferroelectrics

NASA Astrophysics Data System (ADS)

Liu, Yang; Zhang, Guangzu; Li, Qi; Bellaiche, Laurent; Scott, James F.; Dkhil, Brahim; Wang, Qing

2016-12-01

Utilizing thermal changes in solid-state materials strategically offers caloric-based alternatives to replace current vapor-compression technology. To make full use of multiple forms of the entropy and achieve higher efficiency for designs of cooling devices, the multicaloric effect appears as a cutting-edge concept encouraging researchers to search for multicaloric materials with outstanding caloric properties. Here we report the multicaloric effect in BaTi O3 single crystals driven simultaneously by mechanical and electric fields and described via a thermodynamic phenomenological model. It is found that the multicaloric behavior is mainly dominated by the mechanical field rather than the electric field, since the paraelectric-to-ferroelectric transition is more sensitive to mechanical field than to electric field. The use of uniaxial stress competes favorably with pressure due to its much higher caloric strength and negligible elastic thermal change. It is revealed that multicaloric response can be significantly larger than just the sum of mechanocaloric and electrocaloric effects in temperature regions far above the Curie temperature but cannot exceed this limit near the Curie temperature. Our results also show the advantage of the multicaloric effect over the mechanically mediated electrocaloric effect or electrically mediated mechanocaloric effect. Our findings therefore highlight the importance of ferroelectric materials to develop multicaloric cooling.

Direct measurement of electrocaloric effect in lead-free Ba(SnxTi1-x)O3 ceramics

NASA Astrophysics Data System (ADS)

Sanlialp, Mehmet; Luo, Zhengdong; Shvartsman, Vladimir V.; Wei, Xianzhu; Liu, Yang; Dkhil, Brahim; Lupascu, Doru C.

2017-10-01

In this study, we report on investigation of the electrocaloric (EC) effect in lead-free Ba(SnxTi1-x)O3 (BSnT) ceramics with compositions in the range of 0.08 ≤ x ≤ 0.15 by the direct measurement method using a differential scanning calorimeter. The maximum EC temperature change, ΔTEC-max = 0.63 K under an electric field of 2 kV/mm, was observed for the composition with x = 0.11 at ˜44 °C around the multiphase coexistence region. We observed that the EC effect also peaks at transitions between ferroelectric phases of different symmetries. Comparison with the results of indirect EC measurements from our previous work shows that the indirect approach provides reasonable estimations of the magnitude of the largest EC temperature changes and EC strength. However, it fails to describe correctly temperature dependences of the EC effect for the compositions showing relaxor-like behaviour (x = 0.14 and 0.15) because of their non-ergodic nature. Our study provides strong evidence supporting that looking for multiphase ferroelectric materials can be very useful to optimize EC performance.

Enhanced electrocaloric effect in displacive-type organic ferroelectrics

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

Ding, L. J., E-mail: dinglinjie82@126.com; Zhong, Y.; Fan, S. W.

2015-08-07

We explore the intrinsic feature of electrocaloric effect (ECE) accompanied by ferroelectric (FE)-paraelectric (PE) transition for displacive-type organic ferroelectrics using Green's function theory. It is demonstrated that decreasing elastic constant K or increasing spin-lattice coupling λ can enhance the ECE, as well as polarization P and transition temperature T{sub C}. Indeed, one expects that the optimal operating temperature for solid-state refrigeration is around room temperature, at which the ECE achieves its maximum. As T{sub C} is tuned to ∼310 K, it presents larger ECE response and remanent polarization with lower coercive field for smaller K value, suggesting that well flexible displacive-typemore » organic ferroelectrics are excellent candidates both for electric cooling and data storage in the design of nonvolatile FE random-access memories. Furthermore, in an electric field, it provides a bridge between a Widom line that denotes FE-PE crossover above T{sub C} and a metaelectric transition line below T{sub C} that demonstrates an FE switching behavior with an antiparallel field.« less

Quasi-adiabatic calorimeter for direct electrocaloric measurements

NASA Astrophysics Data System (ADS)

Sanlialp, Mehmet; Shvartsman, Vladimir V.; Faye, Romain; Karabasov, Maksim O.; Molin, Christian; Gebhardt, Sylvia; Defay, Emmanuel; Lupascu, Doru C.

2018-03-01

The electrocaloric effect (ECE) in ferroelectric materials is a promising candidate for small, effective, low cost, and environmentally friendly solid state cooling applications. Instead of the commonly used indirect estimates based on Maxwell's relations, direct measurements of the ECE are required to obtain reliable values. In this work, we report on a custom-made quasi-adiabatic calorimeter for direct ECE measurements. The ECE is measured for two promising lead-free materials: Ba(Zr0.12Ti0.88)O3 and Ba(Zr0.2Ti0.8)O3 bulk ceramics. Adiabatic temperature changes of ΔTEC = 0.5 K at 355 K and ΔTEC = 0.3 K at 314 K were achieved under the application of an electric field of 2 kV/mm for the Ba(Zr0.12Ti0.88)O3 and Ba(Zr0.2Ti0.8)O3 samples, respectively. The quasi-adiabatic ECE measurements reliably match other direct EC measurements using a differential scanning calorimeter or an infrared camera. The data are compared to indirect EC estimations based on Maxwell's relations and show that the indirect measurements typically underestimate the effect to a certain degree.

Electro-caloric effect in lead-free Sn doped BaTiO{sub 3} ceramics at room temperature and low applied fields

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

Upadhyay, Sanjay Kumar; Reddy, V. Raghavendra, E-mail: varimalla@yahoo.com, E-mail: vrreddy@csr.res.in; Bag, Pallab

2014-09-15

Structural, dielectric, ferroelectric (FE), {sup 119}Sn Mössbauer, and specific heat measurements of polycrystalline BaTi{sub 1–x}Sn{sub x}O{sub 3} (x = 0% to 15%) ceramics are reported. Phase purity and homogeneous phase formation with Sn doping is confirmed from x-ray diffraction and {sup 119}Sn Mössbauer measurements. With Sn doping, the microstructure is found to change significantly. Better ferroelectric properties at room temperature, i.e., increased remnant polarization (38% more) and very low field switchability (225% less) are observed for x = 5% sample as compared to other samples and the results are explained in terms of grain size effects. With Sn doping, merging of all the phasemore » transitions into a single one is observed for x ≥ 10% and for x = 5%, the tetragonal to orthorhombic transition temperature is found close to room temperature. As a consequence better electro-caloric effects are observed for x = 5% sample and therefore is expected to satisfy the requirements for non-toxic, low energy (field) and room temperature based applications.« less

Electrocaloric effect in BaTiO3 at all three ferroelectric transitions: Anisotropy and inverse caloric effects

NASA Astrophysics Data System (ADS)

Marathe, Madhura; Renggli, Damian; Sanlialp, Mehmet; Karabasov, Maksim O.; Shvartsman, Vladimir V.; Lupascu, Doru C.; Grünebohm, Anna; Ederer, Claude

2017-07-01

We study the electrocaloric (EC) effect in bulk BaTiO3 (BTO) using molecular dynamics simulations of a first principles-based effective Hamiltonian, combined with direct measurements of the adiabatic EC temperature change in BTO single crystals. We examine in particular the dependence of the EC effect on the direction of the applied electric field at all three ferroelectric transitions, and we show that the EC response is strongly anisotropic. Most strikingly, an inverse caloric effect, i.e., a temperature increase under field removal, can be observed at both ferroelectric-ferroelectric transitions for certain orientations of the applied field. Using the generalized Clausius-Clapeyron equation, we show that the inverse effect occurs exactly for those cases where the field orientation favors the higher temperature/higher entropy phase. Our simulations show that temperature changes of around 1 K can, in principle, be obtained at the tetragonal-orthorhombic transition close to room temperature, even for small applied fields, provided that the applied field is strong enough to drive the system across the first-order transition line. Our direct EC measurements for BTO single crystals at the cubic-tetragonal and at the tetragonal-orthorhombic transitions are in good qualitative agreement with our theoretical predictions, and in particular confirm the occurrence of an inverse EC effect at the tetragonal-orthorhombic transition for electric fields applied along the [001] pseudocubic direction.

Thickness-dependent electrocaloric effect in mixed-phase Pb0.87Ba0.1 La0.02(Zr0.6Sn0.33Ti0.07)O3 thin films

PubMed Central

Correia, T. M.

2016-01-01

Full-perovskite Pb0.87Ba0.1La0.02(Zr0.6Sn0.33Ti0.07)O3 (PBLZST) thin films were fabricated by a sol–gel method. These revealed both rhombohedral and tetragonal phases, as opposed to the full-tetragonal phase previously reported in ceramics. The fractions of tetragonal and rhombohedral phases are found to be strongly dependent on film thickness. The fraction of tetragonal grains increases with increasing film thickness, as the substrate constraint throughout the film decreases with film thickness. The maximum of the dielectric constant (εm) and the corresponding temperature (Tm) are thickness-dependent and dictated by the fraction of rhombohedral and tetragonal phase, with εm reaching a minimum at 400 nm and Tm shifting to higher temperature with increasing thickness. With the thickness increase, the breakdown field decreases, but field-induced antiferroelectric–ferroelectric (EAFE−FE) and ferroelectric–antiferroelectric (EFE−AFE) switch fields increase. The electrocaloric effect increases with increasing film thickness. This article is part of the themed issue ‘Taking the temperature of phase transitions in cool materials’. PMID:27402937

Direct electrocaloric measurement of 0.9Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.1PbTiO{sub 3} films using scanning thermal microscopy

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

Crossley, S.; Nair, B.; Kar-Narayan, S.

2016-01-18

We show that scanning thermal microscopy can measure reversible electrocaloric (EC) effects in <40 μm-thick ceramic films of the relaxor ferroelectric 0.9Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.1PbTiO{sub 3}, with the substrate present. We recorded roughly the same non-adiabatic temperature change (±0.23 K) for a thinner film that was driven harder than a thicker film (±31 V μm{sup −1} across 13 μm versus ±11 V μm{sup −1} across 38 μm), because the thicker film lay relatively closer to the substantially larger adiabatic values that we predicted by thermodynamic analysis of electrical data. Film preparation was compatible with the fabrication of EC multilayer capacitors, and therefore our measurement method maymore » be exploited for rapid characterisation of candidate films for cooling applications.« less

Material System Engineering for Advanced Electrocaloric Cooling Technology

NASA Astrophysics Data System (ADS)

Qian, Xiaoshi

Electrocaloric effect refers to the entropy change and/or temperature change in dielectrics caused by the electric field induced polarization change. Recent discovery of giant ECE provides an opportunity to realize highly efficient cooling devices for a broad range of applications ranging from household appliances to industrial applications, from large-scale building thermal management to micro-scale cooling devices. The advances of electrocaloric (EC) based cooling device prototypes suggest that highly efficient cooling devices with compact size are achievable, which could lead to revolution in next generation refrigeration technology. This dissertation focuses on both EC based materials and cooling devices with their recent advances that address practical issues. Based on better understandings in designing an EC device, several EC material systems are studied and improved to promote the performances of EC based cooling devices. In principle, applying an electric field to a dielectric would cause change of dipolar ordering states and thus a change of dipolar entropy. Giant ECE observed in ferroelectrics near ferroelectric-paraelectric (FE-PE) transition temperature is owing to the large dipolar orientation change, between random-oriented dipolar states in paraelectric phase and spontaneous-ordered dipolar states in ferroelectric phases, which is induced by external electric fields. Besides pursuing large ECE, studies on EC cooling devices indicated that EC materials are required to possess wide operational temperature window, in which large ECE can be maintained for efficient operations. Although giant ECE was first predicted in ferroelectric polymers, where the large effect exhibits near FEPE phase transition, the narrow operation temperature window poses obstacles for these normal ferroelectrics to be conveniently perform in wide range of applications. In this dissertation, we demonstrated that the normal ferroelectric polymers can be converted to relaxor ferroelectric polymers which possess both giant ECE (27 Kelvin temperature drop) and much wider operating temperature window (over 50 kelvin covering RT) by proper defect modification which delicately tailors ferroelectrics in meso-, micro- and molecular scales. In addition, in order to be practical, EC device requires EC material can be driven at low electric fields upon achieve the large ECE. It is demonstrated in this dissertation that by facially modifying materials structure in meso-, micro- and molecular scale, lowfield ECE can be greatly improved. Large ECE, induced by low electric fields and existing in wide temperature window, is a major improvement in EC materials for practical applications. Besides EC polymers, this thesis also investigated EC ceramics. Due to several unique opportunities offered by the EC ceramics, Ba(ZrxTi 1-x)O3 (BZT), that is studied. (i) This class of EC ceramics offers a possibility to explore the invariant critical point (ICP), which maximizes the number of coexistent phase and provides a nearly vanishing energy barrier for switching among different phases. As demonstrated in this thesis, the BZT bulk ceramics at x˜ 0.2 exhibits a large adiabatic temperature drop DeltaTc=4.5 K, a large isothermal entropy change DeltaS = 8 Jkg-1K-1, a large EC coefficient (|DeltaT c/DeltaE| = 0.52x10-6 KmV-1 and DeltaS/DeltaE=0.93x10 -6 Jmkg-1K-1V-1) over a wide operating temperature range Tspan>30K. (ii) The thermal conductivity of EC ceramics is in general, much higher than that of EC polymers, and consequently they will allow EC cooling configurations which are not accessible by the EC polymers. Moreover, in the same device configuration, the high thermal conductivity of EC ceramics (kappa> 5 W/mK, compared with EC polymer, ˜ 0.25 W/mK) allows higher operation frequency and therefore a higher cooling power. (iii) Well-established fabrication processes of multilayer ceramic capacitor (MLCC) provide a foundation for the EC ceramic toward mass production. In this thesis, BZT thick film double layers have been fabricated and large ECE has been directly measured. EC induced temperature drop (DeltaT) around 6.3 °C and entropy change (DeltaS) of 11.0 Jkg-1K -1 are observed under an electric field of DeltaE=14.6 MV/m at 40 °C was observed in BZT thick film double layers. The result encourages further investigations on ECE in MLCC for practical applications. (Abstract shortened by ProQuest.).

A regenerative elastocaloric heat pump

NASA Astrophysics Data System (ADS)

Tušek, Jaka; Engelbrecht, Kurt; Eriksen, Dan; Dall'Olio, Stefano; Tušek, Janez; Pryds, Nini

2016-10-01

A large fraction of global energy use is for refrigeration and air-conditioning, which could be decarbonized if efficient renewable energy technologies could be found. Vapour-compression technology remains the most widely used system to move heat up the temperature scale after more than 100 years; however, caloric-based technologies (those using the magnetocaloric, electrocaloric, barocaloric or elastocaloric effect) have recently shown a significant potential as alternatives to replace this technology due to high efficiency and the use of green solid-state refrigerants. Here, we report a regenerative elastocaloric heat pump that exhibits a temperature span of 15.3 K on the water side with a corresponding specific heating power up to 800 W kg-1 and maximum COP (coefficient-of-performance) values of up to 7. The efficiency and specific heating power of this device exceeds those of other devices based on caloric effects. These results open up the possibility of using the elastocaloric effect in various cooling and heat-pumping applications.

Understanding the Scientific Basis of Electrocaloric Effect in Defects Modified Ferroelectric Polymers

DTIC Science & Technology

2014-12-19

0.2), but is higher than that of BZT(x=0.25). The directly recorded ECE signal from BZT(x=0.2) (at 35 oC under a E = 9.5 MVm -1) is presented in Fig...the sample as the field is removed are presented in Fig. 7(b) for the BZT(x=0.2) at 35 oC under different E. The data reveals that at E = 14 MVm -1...samples in the ECE study, the highest field that can be applied was 14 MVm -1. To make a comparison with the results on BT thick films, we extrapolate the

Electro-Caloric Properties of BT/PZT Multilayer Thin Films Prepared by Sol-Gel Method.

PubMed

Kwon, Min-Su; Lee, Sung-Gap; Kim, Kyeong-Min

2018-09-01

In this study, Barium Titanate (BT)/Lead Zirconate Titanate (PZT) multilayer thin films were fabricated by the spin-coating method on Pt (200 nm)/Ti (10 nm) SiO2 (100 nm)/P-Si (100) substrates using BaTiO3 and Pb(Zr0.90Ti0.10)O3 metal alkoxide solutions. The coating and heating procedure was repeated several times to form the multilayer thin films. All of BT/PZT multilayer thin films show X-ray diffraction patterns typical to a polycrystalline perovskite structure and a uniform and void free grain microstructure. The thickness of the BT and PZT film by one-cycle of drying/sintering was approximately 50 nm and all of the films consisted of fine grains with a flat surface morphology. The electrocaloric properties of BT/PZT thin films were investigated by indirect estimation. The results showed that the temperature change ΔT can be calculated as a function of temperature using Maxwell's relation; the temperature change reaches a maximum value of ~1.85 °C at 135 °C under an applied electric field of 260 kV/cm.

Electrocaloric Refrigeration for Superconductors

DTIC Science & Technology

1977-02-01

Dielectric properties 40 3.3.2. Relation to capacitance thermometer manufacturing . . 42 3.4. SrTiO, Glass-Ceramic Multilayer Samples 42 3.4.1...Experimental Methods 66 3.6.1. Dielectric properties 66 3.6.2. Thermodynamic properties 7 0 3.6.3. Thermal conductivity. .... 80 3.7...Discussion of Experimental Results 143 3.8.1. Dielectric Troperties 143 3.8.2. Thermal Properties 150 3.8.3. Recommendations for further work

Multiple caloric effects in (Ba0.865Ca0.135Zr0.1089Ti0.8811Fe0.01)O3 ferroelectric ceramic

NASA Astrophysics Data System (ADS)

Patel, Satyanarayan; Chauhan, Aditya; Vaish, Rahul

2015-07-01

Multiple caloric effects have been investigated for Fe-doped bulk (Ba0.865Ca0.135Zr0.1089Ti0.8811Fe0.01)O3 (BCZTO-Fe) ferroelectric ceramic. Indirect predictions were made using Maxwell's relations in conjunction with data from experimental observations. It was revealed that bulk BCZTO-Fe has huge untapped potential for solid-state refrigeration. A peak electrocaloric effect of 0.45 K (347 K) was predicted for 0-3 kV.mm-1 electric field, significantly higher than other BCZTO based materials. A maximum elastocaloric cooling of 1.4 K (298 K) was achieved for applied stress of 0-200 MPa. Finally, an unforeseen component of electric field driven caloric effect has been reported as inverse piezocaloric effect, with a maximum temperature change of 0.28 K (298 K).

Flow-synchronous field motion refrigeration

DOEpatents

Hassen, Charles N.

2017-08-22

An improved method to manage the flow of heat in an active regenerator in a magnetocaloric or an electrocaloric heat-pump refrigeration system, in which heat exchange fluid moves synchronously with the motion of a magnetic or electric field. Only a portion of the length of the active regenerator bed is introduced to or removed from the field at one time, and the heat exchange fluid flows from the cold side toward the hot side while the magnetic or electric field moves along the active regenerator bed.

A scaling law for distinct electrocaloric cooling performance in low-dimensional organic, relaxor and anti-ferroelectrics.

PubMed

Shi, Yuping; Huang, Limin; Soh, Ai Kah; Weng, George J; Liu, Shuangyi; Redfern, Simon A T

2017-09-11

Electrocaloric (EC) materials show promise in eco-friendly solid-state refrigeration and integrable on-chip thermal management. While direct measurement of EC thin-films still remains challenging, a generic theoretical framework for quantifying the cooling properties of rich EC materials including normal-, relaxor-, organic- and anti-ferroelectrics is imperative for exploiting new flexible and room-temperature cooling alternatives. Here, we present a versatile theory that combines Master equation with Maxwell relations and analytically relates the macroscopic cooling responses in EC materials with the intrinsic diffuseness of phase transitions and correlation characteristics. Under increased electric fields, both EC entropy and adiabatic temperature changes increase quadratically initially, followed by further linear growth and eventual gradual saturation. The upper bound of entropy change (∆S max ) is limited by distinct correlation volumes (V cr ) and transition diffuseness. The linearity between V cr and the transition diffuseness is emphasized, while ∆S max  = 300 kJ/(K.m 3 ) is obtained for Pb 0.8 Ba 0.2 ZrO 3 . The ∆S max in antiferroelectric Pb 0.95 Zr 0.05 TiO 3 , Pb 0.8 Ba 0.2 ZrO 3 and polymeric ferroelectrics scales proportionally with V cr -2.2 , owing to the one-dimensional structural constraint on lattice-scale depolarization dynamics; whereas ∆S max in relaxor and normal ferroelectrics scales as ∆S max ~ V cr -0.37 , which tallies with a dipolar interaction exponent of 2/3 in EC materials and the well-proven fractional dimensionality of 2.5 for ferroelectric domain walls.

Fabrication of ferroelectric polymer nanostructures on flexible substrates by soft-mold reverse nanoimprint lithography

NASA Astrophysics Data System (ADS)

Song, Jingfeng; Lu, Haidong; Li, Shumin; Tan, Li; Gruverman, Alexei; Ducharme, Stephen

2016-01-01

Conventional nanoimprint lithography with expensive rigid molds is used to pattern ferroelectric polymer nanostructures on hard substrate for use in, e.g., organic electronics. The main innovation here is the use of inexpensive soft polycarbonate molds derived from recordable DVDs and reverse nanoimprint lithography at low pressure, which is compatible with flexible substrates. This approach was implemented to produce regular stripe arrays with a spacing of 700 nm from vinylidene fluoride co trifluoroethylene ferroelectric copolymer on flexible polyethylene terephthalate substrates. The nanostructures have very stable and switchable piezoelectric response and good crystallinity, and are highly promising for use in organic electronics enhanced or complemented by the unique properties of the ferroelectric polymer, such as bistable polarization, piezoelectric response, pyroelectric response, or electrocaloric function. The soft-mold reverse nanoimprint lithography also leaves little or no residual layer, affording good isolation of the nanostructures. This approach reduces the cost and facilitates large-area, high-throughput production of isolated functional polymer nanostructures on flexible substrates for the increasing application of ferroelectric polymers in flexible electronics.

Fabrication of ferroelectric polymer nanostructures on flexible substrates by soft-mold reverse nanoimprint lithography.

PubMed

Song, Jingfeng; Lu, Haidong; Li, Shumin; Tan, Li; Gruverman, Alexei; Ducharme, Stephen

2016-01-08

Conventional nanoimprint lithography with expensive rigid molds is used to pattern ferroelectric polymer nanostructures on hard substrate for use in, e.g., organic electronics. The main innovation here is the use of inexpensive soft polycarbonate molds derived from recordable DVDs and reverse nanoimprint lithography at low pressure, which is compatible with flexible substrates. This approach was implemented to produce regular stripe arrays with a spacing of 700 nm from vinylidene fluoride co trifluoroethylene ferroelectric copolymer on flexible polyethylene terephthalate substrates. The nanostructures have very stable and switchable piezoelectric response and good crystallinity, and are highly promising for use in organic electronics enhanced or complemented by the unique properties of the ferroelectric polymer, such as bistable polarization, piezoelectric response, pyroelectric response, or electrocaloric function. The soft-mold reverse nanoimprint lithography also leaves little or no residual layer, affording good isolation of the nanostructures. This approach reduces the cost and facilitates large-area, high-throughput production of isolated functional polymer nanostructures on flexible substrates for the increasing application of ferroelectric polymers in flexible electronics.

Material-based figure of merit for caloric materials

DOE PAGES

Griffith, L. D.; Mudryk, Y.; Slaughter, J.; ...

2018-01-21

Efficient use of reversible thermal effects in magnetocaloric, electrocaloric, and elastocaloric materials is a promising avenue that can lead to a substantially increased efficiency of refrigeration and heat pumping devices, most importantly those used in household and commercial cooling applications near ambient temperature. A proliferation in caloric materials research has resulted in a wide array of materials where only the isothermal change in entropy in response to a handful of different field strengths over a limited range of temperatures has been evaluated and reported. Given the abundance of such data, there is a clear need for a simple and reliablemore » figure of merit enabling fast screening and down-selection to justify further detailed characterization of those materials systems that hold the greatest promise. Based on the analysis of several well-known materials that exhibit vastly different magnetocaloric effects, the Temperature averaged Entropy Change (TEC) is introduced as a suitable early indicator of the material’s utility for magnetocaloric cooling applications, and its adoption by the caloric community is recommended.« less

Material-based figure of merit for caloric materials

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

Griffith, L. D.; Mudryk, Y.; Slaughter, J.

Efficient use of reversible thermal effects in magnetocaloric, electrocaloric, and elastocaloric materials is a promising avenue that can lead to a substantially increased efficiency of refrigeration and heat pumping devices, most importantly those used in household and commercial cooling applications near ambient temperature. A proliferation in caloric materials research has resulted in a wide array of materials where only the isothermal change in entropy in response to a handful of different field strengths over a limited range of temperatures has been evaluated and reported. Given the abundance of such data, there is a clear need for a simple and reliablemore » figure of merit enabling fast screening and down-selection to justify further detailed characterization of those materials systems that hold the greatest promise. Based on the analysis of several well-known materials that exhibit vastly different magnetocaloric effects, the Temperature averaged Entropy Change (TEC) is introduced as a suitable early indicator of the material’s utility for magnetocaloric cooling applications, and its adoption by the caloric community is recommended.« less

Nanoscale solid-state cooling: a review.

PubMed

Ziabari, Amirkoushyar; Zebarjadi, Mona; Vashaee, Daryoosh; Shakouri, Ali

2016-09-01

The recent developments in nanoscale solid-state cooling are reviewed. This includes both theoretical and experimental studies of different physical concepts, as well as nanostructured material design and device configurations. We primarily focus on thermoelectric, thermionic and thermo-magnetic coolers. Particular emphasis is given to the concepts based on metal-semiconductor superlattices, graded materials, non-equilibrium thermoelectric devices, Thomson coolers, and photon assisted Peltier coolers as promising methods for efficient solid-state cooling. Thermomagnetic effects such as magneto-Peltier and Nernst-Ettingshausen cooling are briefly described and recent advances and future trends in these areas are reviewed. The ongoing progress in solid-state cooling concepts such as spin-calorimetrics, electrocalorics, non-equilibrium/nonlinear Peltier devices, superconducting junctions and two-dimensional materials are also elucidated and practical achievements are reviewed. We explain the thermoreflectance thermal imaging microscopy and the transient Harman method as two unique techniques developed for characterization of thermoelectric microrefrigerators. The future prospects for solid-state cooling are briefly summarized.

Critical scaling analysis for displacive-type organic ferroelectrics around ferroelectric transition

NASA Astrophysics Data System (ADS)

Ding, L. J.

2017-04-01

The critical scaling properties of displacive-type organic ferroelectrics, in which the ferroelectric-paraelectric transition is induced by spin-Peierls instability, are investigated by Green's function theory through the modified Arrott plot, critical isothermal and electrocaloric effect (ECE) analysis around the transition temperature TC. It is shown that the electric entropy change - ΔS follows a power-law dependence of electric field E : - ΔS ∼En with n satisfying the Franco equation n(TC) = 1 +(β - 1) /(β + γ) = 0.618, wherein the obtained critical exponents β = 0.440 and γ = 1.030 are not only corroborated by Kouvel-Fisher method, but also confirm the Widom critical relation δ = 1 + γ / β. The self-consistency and reliability of the obtained critical exponents are further verified by the scaling equations. Additionally, a universal curve of - ΔS is constructed with rescaling temperature and electric field, so that one can extrapolate the ECE in a certain temperature and electric field range, which would be helpful in designing controlled electric refrigeration devices.

Giant Electrocaloric Effect in Ferroelectrics with Tailored Polaw-Nanostructures

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

Zhang, Qiming

2015-06-24

Electrocaloric effect (ECE) is the temperature and/or entropy change in a dielectric material caused by an electric field induced polarization change. Although ECE has been studied since 1930s, the very small ECE observed in earlier studies in bulk materials before 2007 makes it not attractive for practical cooling applications. The objectives of this DOE program are to carry out a systematical scientific research on the entropy change and ECE in polar-dielectrics, especially ferroelectrics based on several fundamental hypotheses and to search for answers on a few scientific questions. Especially, this research program developed a series of polar-dielectric materials with controlledmore » nano- and meso-structures and carried out studies on how these structures affect the polar-ordering, correlations, energy landscapes, and consequently the entropy states at different phases and ECE. The key hypotheses of the program include: (i) Whether a large ECE can be obtained near the ferroelectric-paraelectric (FE-PE) transition in properly designed ferroelectrics which possess large polarization P and large ß (the coefficient in the thermodynamic Landau theory where the Gibbs free energy G = G = G 0+ ½ a P 2 +1/4 b P 4 + 1/6 c P 6 – EP, and a = ß (T-T c), where b,c,ß and Tc are constants)? (ii) What determines/determine ß? Whether a ferroelectric material with built-in disorders, which disrupt the polar-correlations and enabling a large number of local polar-states, such as a properly designed ferroelectric relaxor, can achieve a large ECE? (iii) How to design a ferroelectric material which has flat energy landscape so that the energy barriers for switching among different phases are vanishingly small? What are the necessary conditions to maximize the number of coexisting phases? (iv) How to design ferroelectric materials with a large tunable dielectric response? That is, at zero electric field, the material possesses very low polar-correlation and hence a very small dielectric constant, under the application of electric field, the material develops long range polar-correlation and hence a high dielectric response. Studying and developing these materials will deepen our understanding on the polarization responses in strongly coupled materials and the roles of molecular and nano, meso-, and micro-scale defects and structures on the polarization responses. On the application front, besides ECE, these dielectrics will also have great impact on micro-electronics and communications. (v) The multi-field effect, besides the electric, elastic and even magnetic effects, could be made use of to tune the energy landscape of polar-materials and hence enhance the ECE. Hence the question is what are the suitable material systems to develop and maximize the multi-field effects? (vi) Besides solid dielectric, liquid dielectrics with properly designed molecular structures and dipolar coupling can also exhibit a large ECE near the dipolar order-disorder transition. The study of order-disorder transition and their influence on entropy change and ECE will provide additional avenue to study dielectrics and understand relationship between the polar-ordering and dipolar entropy in dielectrics. (vii) Besides the regular ECE in which applying an electric field will induce dipolar ordering, there are dielectric material systems which can exhibit negative ECE in which the applied field will reduce the dipolar ordering and anomalous ECE in which applying an electric field pulse will generate cooling only. The question is how to control and balance the nano- and meso-scale polar coupling in dielectrics to achieve such effects? ECE in dielectrics provides an interesting and effective avenue to probe the polar-correlation in dielectrics. Thus the study of ECE in polar-dielectrics, besides the application values, will also deepen our understanding of strongly coupled materials systems, phase transitions, and materials systems with nano- and meso-scale disorders. Through the efforts of this DoE program, we have developed understandings for many questions and materials approaches for many hypotheses listed above. The major accomplishments include: (i) The first one to show that a giant ECE can be obtained in bulk materials of ferroelectric P(VDF-TrFE) copolymer, which has a large ß coefficient and high polarization, near FE-PE transition.[1,3,12] (ii) The first who developed the theoretical analyses on the upper bound of dipolar entropy change in polar-materials and the general approach to maximize the coexisting phases with vanishingly small switching fields among the coexisting phases[10,23] Experimental results confirm these theoretical predictions.[24] (iii) The first to show that the relaxor ferroelectrics, due to built-in defects structures at nano- and meso scale, exhibit a giant ECE over a broad temperature range.[1,3,7,14] (iv) The first to show that a large ECE can be obtained near order-disorder transition in dielectric fluids such as liquid crystals with large dielectric anisotropy. Also the study developed a general approach for developing dielectric fluids to achieve a large electric field induced entropy change.[26] (v) We are starting to explore the multi-field effect (multiferroic effect) in nanocomposites in which there exist large dielectric contrasts between the matrix and nanofilelrs and showed that a significantly enhanced ECE compared with polymer matrix.[36] (vi) By facially tuning the nano- and meso-scale dipolar coupling, we are the first to show that an anomalous ECE can be obtained in a relaxor/normal ferroelectric blend.[39] (vii) Introduced and demonstrated that the internal bias field approach can be effective in enhancing the EC response at low electric field. The result is significant since for practical applications, a low applied field is highly desired. (viii) A high sensitivity ECE characterization system has been developed. This program has made major contributions to the advancement of the EC materials and understandings of EC phenomena. To reflect the advancement in the EC materials development and scientific understandings on ECE through in this time period (from Sept. 1, 2007 to May 2015), this final report is written based on the reports complied each year through the program. Some early works on the ECE which were obtained using the indirect method are not included in this report.« less

Ultrafast Electric Field Pulse Control of Giant Temperature Change in Ferroelectrics

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

Qi, Y.; Liu, S.; Lindenberg, A. M.

There is a surge of interest in developing environmentally friendly solid-state-based cooling technology. Here, we point out that a fast cooling rate (≈ 10 11 K/s) can be achieved by driving solid crystals to a high-temperature phase with a properly designed electric field pulse. Specifically, we predict that an ultrafast electric field pulse can cause a giant temperature decrease up to 32 K in PbTiO 3 occurring on few picosecond time scales. Here, we explain the underlying physics of this giant electric field pulse-induced temperature change with the concept of internal energy redistribution: the electric field does work on amore » ferroelectric crystal and redistributes its internal energy, and the way the kinetic energy is redistributed determines the temperature change and strongly depends on the electric field temporal profile. This concept is supported by our all-atom molecular dynamics simulations of PbTiO 3 and BaTiO 3. Moreover, this internal energy redistribution concept can also be applied to understand electrocaloric effect. We further propose new strategies for inducing giant cooling effect with ultrafast electric field pulse. This Letter offers a general framework to understand electric-field-induced temperature change and highlights the opportunities of electric field engineering for controlled design of fast and efficient cooling technology.« less

Ultrafast Electric Field Pulse Control of Giant Temperature Change in Ferroelectrics

DOE PAGES

Qi, Y.; Liu, S.; Lindenberg, A. M.; ...

2018-01-30

There is a surge of interest in developing environmentally friendly solid-state-based cooling technology. Here, we point out that a fast cooling rate (≈ 10 11 K/s) can be achieved by driving solid crystals to a high-temperature phase with a properly designed electric field pulse. Specifically, we predict that an ultrafast electric field pulse can cause a giant temperature decrease up to 32 K in PbTiO 3 occurring on few picosecond time scales. Here, we explain the underlying physics of this giant electric field pulse-induced temperature change with the concept of internal energy redistribution: the electric field does work on amore » ferroelectric crystal and redistributes its internal energy, and the way the kinetic energy is redistributed determines the temperature change and strongly depends on the electric field temporal profile. This concept is supported by our all-atom molecular dynamics simulations of PbTiO 3 and BaTiO 3. Moreover, this internal energy redistribution concept can also be applied to understand electrocaloric effect. We further propose new strategies for inducing giant cooling effect with ultrafast electric field pulse. This Letter offers a general framework to understand electric-field-induced temperature change and highlights the opportunities of electric field engineering for controlled design of fast and efficient cooling technology.« less

Ultrafast Electric Field Pulse Control of Giant Temperature Change in Ferroelectrics

NASA Astrophysics Data System (ADS)

Qi, Y.; Liu, S.; Lindenberg, A. M.; Rappe, A. M.

2018-01-01

There is a surge of interest in developing environmentally friendly solid-state-based cooling technology. Here, we point out that a fast cooling rate (≈1011 K /s ) can be achieved by driving solid crystals to a high-temperature phase with a properly designed electric field pulse. Specifically, we predict that an ultrafast electric field pulse can cause a giant temperature decrease up to 32 K in PbTiO3 occurring on few picosecond time scales. We explain the underlying physics of this giant electric field pulse-induced temperature change with the concept of internal energy redistribution: the electric field does work on a ferroelectric crystal and redistributes its internal energy, and the way the kinetic energy is redistributed determines the temperature change and strongly depends on the electric field temporal profile. This concept is supported by our all-atom molecular dynamics simulations of PbTiO3 and BaTiO3 . Moreover, this internal energy redistribution concept can also be applied to understand electrocaloric effect. We further propose new strategies for inducing giant cooling effect with ultrafast electric field pulse. This Letter offers a general framework to understand electric-field-induced temperature change and highlights the opportunities of electric field engineering for controlled design of fast and efficient cooling technology.

Enhanced performance of ferroelectric materials under hydrostatic pressure

NASA Astrophysics Data System (ADS)

Chauhan, Aditya; Patel, Satyanarayan; Wang, Shuai; Novak, Nikola; Xu, Bai-Xiang; Lv, Peng; Vaish, Rahul; Lynch, Christopher S.

2017-12-01

Mechanical confinement or restricted degrees of freedom have been explored for its potential to enhance the performance of ferroelectric devices. It presents an easy and reversible method to tune the response for specific applications. However, such studies have been mainly limited to uni- or bi-axial stress. This study investigates the effect of hydrostatic pressure on the ferroelectric behavior of bulk polycrystalline Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3. Polarization versus electric field hysteresis plots were generated as a function of hydrostatic pressure for a range of operating temperatures (298-398 K). The application of hydrostatic pressure was observed to induce anti-ferroelectric like double hysteresis loops. This in turn enhances the piezoelectric, energy storage, energy harvesting, and electrocaloric effects. The hydrostatic piezoelectric coefficient (dh) was increased from 50 pCN-1 (0 MPa) to ˜900 pC N-1 (265 MPa) and ˜3200 pCN-1 (330 MPa) at 298 K. Energy storage density was observed to improve by more than 4 times under pressure, in the whole temperature range. The relative change in entropy was also observed to shift from ˜0 to 4.8 J kg-1 K-1 under an applied pressure of 325 MPa. This behavior can be attributed to the evolution of pinched hysteresis loops that have been explained using a phenomenological model. All values represent an improvement of several hundred percent compared to unbiased performance, indicating the potential benefits of the proposed methodology.

Thermal expansion anomaly regulated by entropy.

PubMed

Liu, Zi-Kui; Wang, Yi; Shang, ShunLi

2014-11-13

Thermal expansion, defined as the temperature dependence of volume under constant pressure, is a common phenomenon in nature and originates from anharmonic lattice dynamics. However, it has been poorly understood how thermal expansion can show anomalies such as colossal positive, zero, or negative thermal expansion (CPTE, ZTE, or NTE), especially in quantitative terms. Here we show that changes in configurational entropy due to metastable micro(scopic)states can lead to quantitative prediction of these anomalies. We integrate the Maxwell relation, statistic mechanics, and first-principles calculations to demonstrate that when the entropy is increased by pressure, NTE occurs such as in Invar alloy (Fe3Pt, for example), silicon, ice, and water, and when the entropy is decreased dramatically by pressure, CPTE is expected such as in anti-Invar cerium, ice and water. Our findings provide a theoretic framework to understand and predict a broad range of anomalies in nature in addition to thermal expansion, which may include gigantic electrocaloric and electromechanical responses, anomalously reduced thermal conductivity, and spin distributions.

Thermal Expansion Anomaly Regulated by Entropy

NASA Astrophysics Data System (ADS)

Liu, Zi-Kui; Wang, Yi; Shang, Shunli

2014-11-01

Thermal expansion, defined as the temperature dependence of volume under constant pressure, is a common phenomenon in nature and originates from anharmonic lattice dynamics. However, it has been poorly understood how thermal expansion can show anomalies such as colossal positive, zero, or negative thermal expansion (CPTE, ZTE, or NTE), especially in quantitative terms. Here we show that changes in configurational entropy due to metastable micro(scopic)states can lead to quantitative prediction of these anomalies. We integrate the Maxwell relation, statistic mechanics, and first-principles calculations to demonstrate that when the entropy is increased by pressure, NTE occurs such as in Invar alloy (Fe3Pt, for example), silicon, ice, and water, and when the entropy is decreased dramatically by pressure, CPTE is expected such as in anti-Invar cerium, ice and water. Our findings provide a theoretic framework to understand and predict a broad range of anomalies in nature in addition to thermal expansion, which may include gigantic electrocaloric and electromechanical responses, anomalously reduced thermal conductivity, and spin distributions.

Prospects and applications near ferroelectric quantum phase transitions: a key issues review.

PubMed

Chandra, P; Lonzarich, G G; Rowley, S E; Scott, J F

2017-11-01

The emergence of complex and fascinating states of quantum matter in the neighborhood of zero temperature phase transitions suggests that such quantum phenomena should be studied in a variety of settings. Advanced technologies of the future may be fabricated from materials where the cooperative behavior of charge, spin and current can be manipulated at cryogenic temperatures. The progagating lattice dynamics of displacive ferroelectrics make them appealing for the study of quantum critical phenomena that is characterized by both space- and time-dependent quantities. In this key issues article we aim to provide a self-contained overview of ferroelectrics near quantum phase transitions. Unlike most magnetic cases, the ferroelectric quantum critical point can be tuned experimentally to reside at, above or below its upper critical dimension; this feature allows for detailed interplay between experiment and theory using both scaling and self-consistent field models. Empirically the sensitivity of the ferroelectric T c 's to external and to chemical pressure gives practical access to a broad range of temperature behavior over several hundreds of Kelvin. Additional degrees of freedom like charge and spin can be added and characterized systematically. Satellite memories, electrocaloric cooling and low-loss phased-array radar are among possible applications of low-temperature ferroelectrics. We end with open questions for future research that include textured polarization states and unusual forms of superconductivity that remain to be understood theoretically.

Prospects and applications near ferroelectric quantum phase transitions: a key issues review

NASA Astrophysics Data System (ADS)

Chandra, P.; Lonzarich, G. G.; Rowley, S. E.; Scott, J. F.

2017-11-01

The emergence of complex and fascinating states of quantum matter in the neighborhood of zero temperature phase transitions suggests that such quantum phenomena should be studied in a variety of settings. Advanced technologies of the future may be fabricated from materials where the cooperative behavior of charge, spin and current can be manipulated at cryogenic temperatures. The progagating lattice dynamics of displacive ferroelectrics make them appealing for the study of quantum critical phenomena that is characterized by both space- and time-dependent quantities. In this key issues article we aim to provide a self-contained overview of ferroelectrics near quantum phase transitions. Unlike most magnetic cases, the ferroelectric quantum critical point can be tuned experimentally to reside at, above or below its upper critical dimension; this feature allows for detailed interplay between experiment and theory using both scaling and self-consistent field models. Empirically the sensitivity of the ferroelectric T c’s to external and to chemical pressure gives practical access to a broad range of temperature behavior over several hundreds of Kelvin. Additional degrees of freedom like charge and spin can be added and characterized systematically. Satellite memories, electrocaloric cooling and low-loss phased-array radar are among possible applications of low-temperature ferroelectrics. We end with open questions for future research that include textured polarization states and unusual forms of superconductivity that remain to be understood theoretically.

PREFACE: Proceedings Symposium G of E-MRS Spring Meeting on Fundamentals and Technology of Multifunctional Oxide Thin Films

NASA Astrophysics Data System (ADS)

2010-07-01

Oxide materials exhibit a large variety of functional properties that are useful in a plethora of applications. Symposium G focused on oxide thin films that include dielectric or switching properties. Its program mirrored very well the strong worldwide search for high-K thin films for gate, memory, and on-chip capacitors, as well as the emerging field of functional thin films for MEMS. A complete session was devoted to the colossal effect of dielectric response in (Ca,Cu)TiO3, representing the major European research groups in this field. A comprehensive overview on this phenomenon was given by D Sinclair J Wolfman presented the latest results on CCTO thin films obtained by wafer scale pulsed laser deposition. A Loidl showed the analytical power of dielectric spectroscopy when covering the complete frequency range from 1-1012 Hz, i.e. from space charge to phonon contributions at the example of CCTO. Another session was devoted to applications in non-volatile memories, covering various effects including ferroelectric and resistive switching, the complex behavior of oxide tunnel junctions (H Kohlstedt), the possibility to manipulate the magnetic state of a 2d-electron gas by the polarization of an adjacent ferroelectric gate (I Stolitchnov). Latest advancements in ALD processing for high-K thin films in dynamic RAM were reported by S Ramanathan. The advancement of piezoelectric PZT thin film MEMS devices was well documented by outstanding talks on their developments in industry (M Klee, F Tyholdt), new possibilities in GHz filters (T Matshushima), advancements in sol-gel processing (B Tuttle, H Suzuki), and low temperature integration approaches by UV light curing (S Trolier-McKinstry). Recent advances in incipient ferroelectric thin films and nano composites for tunable capacitors in microwave applications were present by A Vorobiev and T Yamada. Integrated electro-optics is another field to be conquered by thin film structures. The impressive progress made in this field was highlighted by P Günter. Many contributions were devoted to processing techniques, showing the increasing importance of CVD techniques to deposit for instance perovskite thin films (G Malandrino). Nevertheless, stunning results were obtained by a sophisticated MBE tool allowing for precise compositional control of individual oxide monolayers and thus enabling High-Tc supraconductivity in individual monolayers to be addressed (I Bosovic). Oxides do not only gleam with giant dielectric properties, giant electronic conduction (superconductivity), there is also a giant electro-caloric effect, as explained by Z Kutnjak. The symposium could take advantage of the EU projects NUOTO and CAMELIA that organized a joint session on giant K dielectrics to present their project results to the scientific and industrial community. The symposium organizers Paul Muralt, EPFL, Lausanne, Switzerland Marija Kosec, Josef Stefan Institute, Ljubljana, Slovenia Vito Raineri, IMM-CNR, Catania, Italy Sebastiano Ravesi, STMicroelectronics, Catania, Italy Scientific Committee Robert Blinc (Josef Stefan Inst., Slovenia) Wolfgang Kleemann (Univ. Duisburg, Germany) Raffaella Lo Nigro (IMM-CNR, Italy) Ian M Reaney (Univ. Sheffield, Great Britain) T Metzger (EPCOS, Germany) Rainer Waser (TH Aachen, Germany)

Small- and Large-Effect Quantitative Trait Locus Interactions Underlie Variation in Yeast Sporulation Efficiency

PubMed Central

Lorenz, Kim; Cohen, Barak A.

2012-01-01

Quantitative trait loci (QTL) with small effects on phenotypic variation can be difficult to detect and analyze. Because of this a large fraction of the genetic architecture of many complex traits is not well understood. Here we use sporulation efficiency in Saccharomyces cerevisiae as a model complex trait to identify and study small-effect QTL. In crosses where the large-effect quantitative trait nucleotides (QTN) have been genetically fixed we identify small-effect QTL that explain approximately half of the remaining variation not explained by the major effects. We find that small-effect QTL are often physically linked to large-effect QTL and that there are extensive genetic interactions between small- and large-effect QTL. A more complete understanding of quantitative traits will require a better understanding of the numbers, effect sizes, and genetic interactions of small-effect QTL. PMID:22942125

Generation of large-scale vorticity in rotating stratified turbulence with inhomogeneous helicity: mean-field theory

NASA Astrophysics Data System (ADS)

Kleeorin, N.

2018-06-01

We discuss a mean-field theory of the generation of large-scale vorticity in a rotating density stratified developed turbulence with inhomogeneous kinetic helicity. We show that the large-scale non-uniform flow is produced due to either a combined action of a density stratified rotating turbulence and uniform kinetic helicity or a combined effect of a rotating incompressible turbulence and inhomogeneous kinetic helicity. These effects result in the formation of a large-scale shear, and in turn its interaction with the small-scale turbulence causes an excitation of the large-scale instability (known as a vorticity dynamo) due to a combined effect of the large-scale shear and Reynolds stress-induced generation of the mean vorticity. The latter is due to the effect of large-scale shear on the Reynolds stress. A fast rotation suppresses this large-scale instability.

[Effect of endogenous H2S on platelet L-Arg transport].

PubMed

Duan, Wen-zhuo; Wang, Yi-peng; Gong, Hai-min

2010-05-01

To observe the effect of novel air neuromodulator H2S on platelet function of L-Arg transport for discussing H2S of effect on platelet function. Saturate H2S solution as donate made rat rich platelet plasma and pre-incubation rat platelet with different density of H2S. To measure the velocity of L-Arg transport in platelet by radioactivity technique. At different concentrations of H2S (6.25, 12.5, 25, 50, 100 micromol/L), the velocity of L-Arg transport was lower than that in control. H2S reduced rapidly the Vmax and velocity of L-Arg transport in platelet (P < 0.05) and this effect had no effect to Km. H2S can affect platelet function by changing rapidly platelet L-Arg transport system function.

Large reversible magnetocaloric effect in a Ni-Co-Mn-In magnetic shape memory alloy

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

Huang, L.; Cong, D. Y.; Ma, L.

Reversibility of the magnetocaloric effect in materials with first-order magnetostructural transformation is of vital significance for practical magnetic refrigeration applications. Here, we report a large reversible magnetocaloric effect in a Ni49.8Co1.2Mn33.5In15.5 magnetic shape memory alloy. A large reversible magnetic entropy change of 14.6 J/(kg K) and a broad operating temperature window of 18 K under 5 T were simultaneously achieved, correlated with the low thermal hysteresis (-8 K) and large magnetic-field-induced shift of transformation temperatures (4.9 K/T) that lead to a narrow magnetic hysteresis (1.1 T) and small average magnetic hysteresis loss (48.4 J/kg under 5 T) as well. Furthermore,more » a large reversible effective refrigeration capacity (76.6 J/kg under 5 T) was obtained, as a result of the large reversible magnetic entropy change, broad operating temperature window, and small magnetic hysteresis loss. The large reversible magnetic entropy change and large reversible effective refrigeration capacity are important for improving the magnetocaloric performance, and the small magnetic hysteresis loss is beneficial to reducing energy dissipation during magnetic field cycle in potential applications.« less

Evaluation of the Contribution of Signals Originating from Large Blood Vessels to Signals of Functionally Specific Brain Areas

PubMed Central

Chung, Jun-Young; Ogawa, Seiji

2015-01-01

The fusiform face area (FFA) is known to play a pivotal role in face processing. The FFA is located in the ventral region, at the base of the brain, through which large blood vessels run. The location of the FFA via functional MRI (fMRI) may be influenced by these large blood vessels. Responses of large blood vessels may not exactly correspond to neuronal activity in a target area, because they may be diluted and influenced by inflow effects. In this study, we investigated the effects of large blood vessels in the FFA, that is, whether the FFA includes large blood vessels and/or whether inflow signals contribute to fMRI signals of the FFA. For this purpose, we used susceptibility-weighted imaging (SWI) sequences to visualize large blood vessels and dual-echo gradient-echo echo-planar imaging (GE-EPI) to measure inflow effects. These results showed that the location and response signals of the FFA were not influenced by large blood vessels or inflow effects, although large blood vessels were located near the FFA. Therefore, the data from the FFA obtained by individual analysis were robust to large blood vessels but leaving a warning that the data obtained by group analysis may be prone to large blood vessels. PMID:26413511

EFFECTS OF LARGE-SCALE POULTRY FARMS ON AQUATIC MICROBIAL COMMUNITIES: A MOLECULAR INVESTIGATION.

EPA Science Inventory

The effects of large-scale poultry production operations on water quality and human health are largely unknown. Poultry litter is frequently applied as fertilizer to agricultural lands adjacent to large poultry farms. Run-off from the land introduces a variety of stressors into t...

Large effects of consumer offense on ecosystem structure and function.

PubMed

Chislock, Michael F; Sarnelle, Orlando; Olsen, Brianna K; Doster, Enrique; Wilson, Alan E

2013-11-01

Study of the role of within-species adaptation in ecological dynamics has focused largely on prey adaptations that reduce consumption risk (prey defense). Few, if any, studies have examined how consumer adaptations to overcome prey defenses (consumer offense) affect ecosystem structure and function. We manipulated two sets of genotypes of a planktonic herbivore (Daphnia pulicaria) in a highly productive ecosystem with abundant toxic prey (cyanobacteria). The two sets of consumer genotypes varied widely in their tolerance of toxic cyanobacteria in the diet (i.e., sensitive vs. tolerant). We found a large effect of tolerant D. pulicaria on phytoplankton biomass and gross primary productivity but no effect of sensitive genotypes, this result stemming from genotype-specific differences in population growth in the presence of toxic prey. The former effect was as large as effects seen in previous Daphnia manipulations at similar productivity levels. Thus, we demonstrated that the effect of consumer genotypes with contrasting offensive adaptations was as large as the effect of consumer presence/absence.

Comparing the Effectiveness of Self-Paced and Collaborative Frame-of-Reference Training on Rater Accuracy in a Large-Scale Writing Assessment

ERIC Educational Resources Information Center

Raczynski, Kevin R.; Cohen, Allan S.; Engelhard, George, Jr.; Lu, Zhenqiu

2015-01-01

There is a large body of research on the effectiveness of rater training methods in the industrial and organizational psychology literature. Less has been reported in the measurement literature on large-scale writing assessments. This study compared the effectiveness of two widely used rater training methods--self-paced and collaborative…

The QTN program and the alleles that matter for evolution: all that's gold does not glitter.

PubMed

Rockman, Matthew V

2012-01-01

The search for the alleles that matter, the quantitative trait nucleotides (QTNs) that underlie heritable variation within populations and divergence among them, is a popular pursuit. But what is the question to which QTNs are the answer? Although their pursuit is often invoked as a means of addressing the molecular basis of phenotypic evolution or of estimating the roles of evolutionary forces, the QTNs that are accessible to experimentalists, QTNs of relatively large effect, may be uninformative about these issues if large-effect variants are unrepresentative of the alleles that matter. Although 20th century evolutionary biology generally viewed large-effect variants as atypical, the field has recently undergone a quiet realignment toward a view of readily discoverable large-effect alleles as the primary molecular substrates for evolution. I argue that neither theory nor data justify this realignment. Models and experimental findings covering broad swaths of evolutionary phenomena suggest that evolution often acts via large numbers of small-effect polygenes, individually undetectable. Moreover, these small-effect variants are different in kind, at the molecular level, from the large-effect alleles accessible to experimentalists. Although discoverable QTNs address some fundamental evolutionary questions, they are essentially misleading about many others. © 2011 The Author(s). Evolution © 2011 The Society for the Study of Evolution.

Ecological effects of large fires on US landscapes: benefit or catastrophe?

Treesearch

Robert E. Keane; James K. Agee; Peter Fule; Jon E. Keeley; Carl Key; Stanley G. Kitchen; Richard Miller; Lisa A. Schulte

2008-01-01

The perception is that today's large fires are an ecological catastrophe because they burn vast areas with high intensities and severities. However, little is known of the ecological impacts of large fires on both historical and contemporary landscapes. The present paper presents a review of the current knowledge of the effects of large fires in the United States...

Interactive effects of large herbivores and plant diversity on insect abundance in a meadow steppe in China

Treesearch

Hui Zhu; Deli Wang; Qinfeng Guo; Jun Liu; Ling Wang

2015-01-01

The structure and dynamics of insect community in grasslands can be influenced by grazing management via altered characteristics of plant community. However, attempts to better understand the complex relationships among plants, insects, and large herbivores is still hampered largely by the interactive effects of plants, insects, and large grazers on each other. In this...

Mutation supply and the repeatability of selection for antibiotic resistance

NASA Astrophysics Data System (ADS)

van Dijk, Thomas; Hwang, Sungmin; Krug, Joachim; de Visser, J. Arjan G. M.; Zwart, Mark P.

2017-10-01

Whether evolution can be predicted is a key question in evolutionary biology. Here we set out to better understand the repeatability of evolution, which is a necessary condition for predictability. We explored experimentally the effect of mutation supply and the strength of selective pressure on the repeatability of selection from standing genetic variation. Different sizes of mutant libraries of antibiotic resistance gene TEM-1 β-lactamase in Escherichia coli, generated by error-prone PCR, were subjected to different antibiotic concentrations. We determined whether populations went extinct or survived, and sequenced the TEM gene of the surviving populations. The distribution of mutations per allele in our mutant libraries followed a Poisson distribution. Extinction patterns could be explained by a simple stochastic model that assumed the sampling of beneficial mutations was key for survival. In most surviving populations, alleles containing at least one known large-effect beneficial mutation were present. These genotype data also support a model which only invokes sampling effects to describe the occurrence of alleles containing large-effect driver mutations. Hence, evolution is largely predictable given cursory knowledge of mutational fitness effects, the mutation rate and population size. There were no clear trends in the repeatability of selected mutants when we considered all mutations present. However, when only known large-effect mutations were considered, the outcome of selection is less repeatable for large libraries, in contrast to expectations. We show experimentally that alleles carrying multiple mutations selected from large libraries confer higher resistance levels relative to alleles with only a known large-effect mutation, suggesting that the scarcity of high-resistance alleles carrying multiple mutations may contribute to the decrease in repeatability at large library sizes.

The large-scale modulation of cosmic rays in mid-1982: Its dependence on heliospheric longitude and radius

NASA Technical Reports Server (NTRS)

Pyle, K. R.; Simpson, J. A.

1985-01-01

Near solar maximum, a series of large radial solar wind shocks in June and July 1982 provided a unique opportunity to study the solar modulation of galactic cosmic rays with an array of spacecraft widely separated both in heliocentric radius and longitude. By eliminating hysteresis effects it is possible to begin to separate radial and azimuthal effects in the outer heliosphere. On the large scale, changes in modulation (both the increasing and recovery phases) propagate outward at close to the solar wind velocity, except for the near-term effects of solar wind shocks, which may propagate at a significantly higher velocity. In the outer heliosphere, azimuthal effects are small in comparison with radial effects for large-scale modulation at solar maximum.

Quantitative Missense Variant Effect Prediction Using Large-Scale Mutagenesis Data.

PubMed

Gray, Vanessa E; Hause, Ronald J; Luebeck, Jens; Shendure, Jay; Fowler, Douglas M

2018-01-24

Large datasets describing the quantitative effects of mutations on protein function are becoming increasingly available. Here, we leverage these datasets to develop Envision, which predicts the magnitude of a missense variant's molecular effect. Envision combines 21,026 variant effect measurements from nine large-scale experimental mutagenesis datasets, a hitherto untapped training resource, with a supervised, stochastic gradient boosting learning algorithm. Envision outperforms other missense variant effect predictors both on large-scale mutagenesis data and on an independent test dataset comprising 2,312 TP53 variants whose effects were measured using a low-throughput approach. This dataset was never used for hyperparameter tuning or model training and thus serves as an independent validation set. Envision prediction accuracy is also more consistent across amino acids than other predictors. Finally, we demonstrate that Envision's performance improves as more large-scale mutagenesis data are incorporated. We precompute Envision predictions for every possible single amino acid variant in human, mouse, frog, zebrafish, fruit fly, worm, and yeast proteomes (https://envision.gs.washington.edu/). Copyright © 2017 Elsevier Inc. All rights reserved.

Aging assessment of large electric motors in nuclear power plants

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

Villaran, M.; Subudhi, M.

1996-03-01

Large electric motors serve as the prime movers to drive high capacity pumps, fans, compressors, and generators in a variety of nuclear plant systems. This study examined the stressors that cause degradation and aging in large electric motors operating in various plant locations and environments. The operating history of these machines in nuclear plant service was studied by review and analysis of failure reports in the NPRDS and LER databases. This was supplemented by a review of motor designs, and their nuclear and balance of plant applications, in order to characterize the failure mechanisms that cause degradation, aging, and failuremore » in large electric motors. A generic failure modes and effects analysis for large squirrel cage induction motors was performed to identify the degradation and aging mechanisms affecting various components of these large motors, the failure modes that result, and their effects upon the function of the motor. The effects of large motor failures upon the systems in which they are operating, and on the plant as a whole, were analyzed from failure reports in the databases. The effectiveness of the industry`s large motor maintenance programs was assessed based upon the failure reports in the databases and reviews of plant maintenance procedures and programs.« less

Effects of large-scale deforestation on precipitation in the monsoon regions: remote versus local effects.

PubMed

Devaraju, N; Bala, Govindasamy; Modak, Angshuman

2015-03-17

In this paper, using idealized climate model simulations, we investigate the biogeophysical effects of large-scale deforestation on monsoon regions. We find that the remote forcing from large-scale deforestation in the northern middle and high latitudes shifts the Intertropical Convergence Zone southward. This results in a significant decrease in precipitation in the Northern Hemisphere monsoon regions (East Asia, North America, North Africa, and South Asia) and moderate precipitation increases in the Southern Hemisphere monsoon regions (South Africa, South America, and Australia). The magnitude of the monsoonal precipitation changes depends on the location of deforestation, with remote effects showing a larger influence than local effects. The South Asian Monsoon region is affected the most, with 18% decline in precipitation over India. Our results indicate that any comprehensive assessment of afforestation/reforestation as climate change mitigation strategies should carefully evaluate the remote effects on monsoonal precipitation alongside the large local impacts on temperatures.

Exogenous L-Arginine Attenuates the Effects of Angiotensin II on Renal Hemodynamics and the Pressure Natriuresis-Diuresis Relationship

PubMed Central

Das, Satarupa; Mattson, David L.

2014-01-01

SUMMARY Administration of exogenous L-Arginine (L-Arg) attenuates Angiotensin II (AngII)-mediated hypertension and kidney disease in rats. The present study assessed renal hemodynamics and pressure-diuresis-natriuresis in anesthetized rats infused with vehicle, AngII (20 ng/kg/min, iv) or AngII + L-Arg (300 µg/kg/min, iv). Increasing renal perfusion pressure (RPP) from approximately 100 to 140 mmHg resulted in a 9–10 fold increase in urine flow and sodium excretion rate in control animals. In comparison, AngII infusion significantly reduced renal blood flow (RBF) and glomerular filtration rate (GFR) by 40–42% and blunted the pressure-dependent increase in urine flow and sodium excretion rate by 54–58% at elevated RPP. Supplementation of L-Arg reversed the vasoconstrictor effects of AngII and restored pressure-dependent diuresis to levels not significantly different from control rats. Experiments in isolated aortic rings were performed to assess L-Arg effects on the vasculature. Dose-dependent contraction to AngII (10−10M to 10−7M) was observed with a maximal force equal to 27±3% of the response to 10−5M phenylephrine. Contraction to 10−7M AngII was blunted by 75±3% with 10−4M L-Arg. The influence of L-Arg to blunt AngII mediated contraction was eliminated by endothelial denudation or incubation with nitric oxide synthase inhibitors. Moreover, the addition of 10−3M cationic or neutral amino acids, which compete with L-Arg for cellular uptake, blocked the effect of L-Arg. Anionic amino acids did not influence the effects of L-Arg on AngII-mediated contraction. These studies indicate that L-Arg blunts AngII-mediated vascular contraction by an endothelial- and NOS-dependent mechanism involving cellular uptake of L-Arg. PMID:24472006

The Analysis of RDF Semantic Data Storage Optimization in Large Data Era

NASA Astrophysics Data System (ADS)

He, Dandan; Wang, Lijuan; Wang, Can

2018-03-01

With the continuous development of information technology and network technology in China, the Internet has also ushered in the era of large data. In order to obtain the effective acquisition of information in the era of large data, it is necessary to optimize the existing RDF semantic data storage and realize the effective query of various data. This paper discusses the storage optimization of RDF semantic data under large data.

Bridgman growth of large-aperture yttrium calcium oxyborate crystal

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

Wu, Anhua, E-mail: wuanhua@mail.sic.ac.cn; Jiang, Linwen; Qian, Guoxing

2012-09-15

Highlights: ► YCOB is a novel non-linear optical crystal possessing good thermal, mechanical and nonlinear optical properties. ► Large size crystal growth is key technology question for YCOB crystal. ► YCOB crystals 3 in. in diameter were grown with modified vertical Bridgman method. ► It is a more effective growth method to obtain large size and high quality YCOB crystal. -- Abstract: Large-aperture yttrium calcium oxyborate YCa{sub 4}O(BO{sub 3}){sub 3} (YCOB) crystals with 3 in. in diameter were grown with modified vertical Bridgman method, and the large crystal plate (63 mm × 68 mm × 20 mm) was harvested formore » high-average power frequency conversion system. The crack, facet growth and spiral growth can be effectively controlled in the as-grown crystal, and Bridgman method displays more effective in obtain large size and high quality YCOB crystal plate than Czochralski technique.« less

Environmental effects and large space systems

NASA Technical Reports Server (NTRS)

Garrett, H. B.

1981-01-01

When planning large scale operations in space, environmental impact must be considered in addition to radiation, spacecraft charging, contamination, high power and size. Pollution of the atmosphere and space is caused by rocket effluents and by photoelectrons generated by sunlight falling on satellite surfaces even light pollution may result (the SPS may reflect so much light as to be a nuisance to astronomers). Large (100 Km 2) structures also will absorb the high energy particles that impinge on them. Altogether, these effects may drastically alter the Earth's magnetosphere. It is not clear if these alterations will in any way affect the Earth's surface climate. Large structures will also generate large plasma wakes and waves which may cause interference with communications to the vehicle. A high energy, microwave beam from the SPS will cause ionospheric turbulence, affecting UHF and VHF communications. Although none of these effects may ultimately prove critical, they must be considered in the design of large structures.

Dispersion in Rectangular Networks: Effective Diffusivity and Large-Deviation Rate Function

NASA Astrophysics Data System (ADS)

Tzella, Alexandra; Vanneste, Jacques

2016-09-01

The dispersion of a diffusive scalar in a fluid flowing through a network has many applications including to biological flows, porous media, water supply, and urban pollution. Motivated by this, we develop a large-deviation theory that predicts the evolution of the concentration of a scalar released in a rectangular network in the limit of large time t ≫1 . This theory provides an approximation for the concentration that remains valid for large distances from the center of mass, specifically for distances up to O (t ) and thus much beyond the O (t1 /2) range where a standard Gaussian approximation holds. A byproduct of the approach is a closed-form expression for the effective diffusivity tensor that governs this Gaussian approximation. Monte Carlo simulations of Brownian particles confirm the large-deviation results and demonstrate their effectiveness in describing the scalar distribution when t is only moderately large.

Practice Makes Perfect?: Effective Practice Instruction in Large Ensembles

ERIC Educational Resources Information Center

Prichard, Stephanie

2012-01-01

Helping young musicians learn how to practice effectively is a challenge faced by all music educators. This article presents a system of individual music practice instruction that can be seamlessly integrated within large-ensemble rehearsals. Using a step-by-step approach, large-ensemble conductors can teach students to identify and isolate…

Estimating the Effectiveness of Special Education Using Large-Scale Assessment Data

ERIC Educational Resources Information Center

Ewing, Katherine Anne

2009-01-01

The inclusion of students with disabilities in large scale assessment and accountability programs has provided new opportunities to examine the impact of special education services on student achievement. Hanushek, Kain, and Rivkin (1998, 2002) evaluated the effectiveness of special education programs by examining students' gains on a large-scale…

Large reversible magnetostrictive effect of MnCoSi-based compounds prepared by high-magnetic-field solidification

NASA Astrophysics Data System (ADS)

Hu, Q. B.; Hu, Y.; Zhang, S.; Tang, W.; He, X. J.; Li, Z.; Cao, Q. Q.; Wang, D. H.; Du, Y. W.

2018-01-01

The MnCoSi compound is a potential magnetostriction material since the magnetic field can drive a metamagnetic transition from an antiferromagnetic phase to a high magnetization phase in it, which accompanies a large lattice distortion. However, a large driving magnetic field, magnetic hysteresis, and poor mechanical properties seriously hinder its application for magnetostriction. By substituting Fe for Mn and introducing vacancies of the Mn element, textured and dense Mn0.97Fe0.03CoSi and Mn0.88CoSi compounds are prepared through a high-magnetic-field solidification approach. As a result, large room-temperature and reversible magnetostriction effects are observed in these compounds at a low magnetic field. The origin of this large magnetostriction effect and potential applications are discussed.

Effects of large vessel on temperature distribution based on photothermal coupling interaction model

NASA Astrophysics Data System (ADS)

Li, Zhifang; Zhang, Xiyang; Li, Zuoran; Li, Hui

2016-10-01

This paper is based on the finite element analysis method for studying effects of large blood vessel on temperature based on photothermal coupling interaction model, and it couples the physical field of optical transmission with the physical field of heat transfer in biological tissue by using COMSOL Multiphysics 4.4 software. The results demonstrate the cooling effect of large blood vessel, which can be potential application for the treatment of liver tumors.

Effects of large-scale deforestation on precipitation in the monsoon regions: Remote versus local effects

PubMed Central

Devaraju, N.; Bala, Govindasamy; Modak, Angshuman

2015-01-01

In this paper, using idealized climate model simulations, we investigate the biogeophysical effects of large-scale deforestation on monsoon regions. We find that the remote forcing from large-scale deforestation in the northern middle and high latitudes shifts the Intertropical Convergence Zone southward. This results in a significant decrease in precipitation in the Northern Hemisphere monsoon regions (East Asia, North America, North Africa, and South Asia) and moderate precipitation increases in the Southern Hemisphere monsoon regions (South Africa, South America, and Australia). The magnitude of the monsoonal precipitation changes depends on the location of deforestation, with remote effects showing a larger influence than local effects. The South Asian Monsoon region is affected the most, with 18% decline in precipitation over India. Our results indicate that any comprehensive assessment of afforestation/reforestation as climate change mitigation strategies should carefully evaluate the remote effects on monsoonal precipitation alongside the large local impacts on temperatures. PMID:25733889

Mean-field dynamo in a turbulence with shear and kinetic helicity fluctuations.

PubMed

Kleeorin, Nathan; Rogachevskii, Igor

2008-03-01

We study the effects of kinetic helicity fluctuations in a turbulence with large-scale shear using two different approaches: the spectral tau approximation and the second-order correlation approximation (or first-order smoothing approximation). These two approaches demonstrate that homogeneous kinetic helicity fluctuations alone with zero mean value in a sheared homogeneous turbulence cannot cause a large-scale dynamo. A mean-field dynamo is possible when the kinetic helicity fluctuations are inhomogeneous, which causes a nonzero mean alpha effect in a sheared turbulence. On the other hand, the shear-current effect can generate a large-scale magnetic field even in a homogeneous nonhelical turbulence with large-scale shear. This effect was investigated previously for large hydrodynamic and magnetic Reynolds numbers. In this study we examine the threshold required for the shear-current dynamo versus Reynolds number. We demonstrate that there is no need for a developed inertial range in order to maintain the shear-current dynamo (e.g., the threshold in the Reynolds number is of the order of 1).

Large anomalous Hall effect driven by a nonvanishing Berry curvature in the noncolinear antiferromagnet Mn3Ge.

PubMed

Nayak, Ajaya K; Fischer, Julia Erika; Sun, Yan; Yan, Binghai; Karel, Julie; Komarek, Alexander C; Shekhar, Chandra; Kumar, Nitesh; Schnelle, Walter; Kübler, Jürgen; Felser, Claudia; Parkin, Stuart S P

2016-04-01

It is well established that the anomalous Hall effect displayed by a ferromagnet scales with its magnetization. Therefore, an antiferromagnet that has no net magnetization should exhibit no anomalous Hall effect. We show that the noncolinear triangular antiferromagnet Mn3Ge exhibits a large anomalous Hall effect comparable to that of ferromagnetic metals; the magnitude of the anomalous conductivity is ~500 (ohm·cm)(-1) at 2 K and ~50 (ohm·cm)(-1) at room temperature. The angular dependence of the anomalous Hall effect measurements confirms that the small residual in-plane magnetic moment has no role in the observed effect except to control the chirality of the spin triangular structure. Our theoretical calculations demonstrate that the large anomalous Hall effect in Mn3Ge originates from a nonvanishing Berry curvature that arises from the chiral spin structure, and that also results in a large spin Hall effect of 1100 (ħ/e) (ohm·cm)(-1), comparable to that of platinum. The present results pave the way toward the realization of room temperature antiferromagnetic spintronics and spin Hall effect-based data storage devices.

Molecular Dissection of a Major Gene Effect on a Quantitative Trait: The Level of Alcohol Dehydrogenase Expression in Drosophila Melanogaster

PubMed Central

Stam, L. F.; Laurie, C. C.

1996-01-01

A molecular mapping experiment shows that a major gene effect on a quantitative trait, the level of alcohol dehydrogenase expression in Drosophila melanogaster, is due to multiple polymorphisms within the Adh gene. These polymorphisms are located in an intron, the coding sequence, and the 3' untranslated region. Because of nonrandom associations among polymorphisms at different sites, the individual effects combine (in some cases epistatically) to produce ``superalleles'' with large effect. These results have implications for the interpretation of major gene effects detected by quantitative trait locus mapping methods. They show that large effects due to a single locus may be due to multiple associated polymorphisms (or sequential fixations in isolated populations) rather than individual mutations of large effect. PMID:8978044

Chronic hypoxia decreases arterial and venous compliance in isolated perfused rat lungs: an effect that is reversed by exogenous l-arginine

PubMed Central

Jin, Yi; Chen, Bernadette; Calvert, Thomas J.; Chicoine, Louis G.; Liu, Yusen

2013-01-01

Chronic hypoxia (CH)-induced pulmonary hypertension is characterized by vasoconstriction and vascular remodeling, leading to right ventricular dysfunction. Given the role of arterial compliance (Ca) in right ventricular work, a decrease in Ca would add to right ventricular work. Nitric oxide (NO) is a potent vasodilator made by NO synthases from l-arginine (l-Arg). However, little is known of the effect of l-Arg on vascular compliance (Cv) in the lung. We hypothesized that exposure to CH would decrease Ca and that this effect would be reversed by exogenous l-Arg. Sprague-Dawley rats were exposed to either normoxia or CH for 14 days; the lungs were then isolated and perfused. Vascular occlusions were performed and modeled using a three-compliance, two-resistor model. Pressure-flow curves were generated, and a distensible vessel model was used to estimate distensibility and a vascular resistance parameter (R0). Hypoxia resulted in the expected increase in arterial resistance (Ra) as well as a decrease in both Ca and Cv. l-Arg had little effect on Ra, Ca, or Cv in isolated lungs from normoxic animals. l-Arg decreased Ra in lungs from CH rats and redistributed compliance to approximately that found in normoxic lungs. CH increased R0, and l-Arg reversed this increase in R0. l-Arg increased exhaled NO, and inhibition of l-Arg uptake attenuated the l-Arg-induced increase in exhaled NO. These data demonstrate that the CH-induced decrease in Ca was reversed by l-Arg, suggesting that l-Arg may improve CH-induced right ventricular dysfunction. PMID:23103497

Does reintroducing large wood influence the hydraulic landscape of a lowland river system?

NASA Astrophysics Data System (ADS)

Matheson, Adrian; Thoms, Martin; Reid, Michael

2017-09-01

Our understanding of the effectiveness of reintroduced large wood for restoration is largely based on studies from high energy river systems. By contrast, few studies of the effectiveness of reintroducing large wood have been undertaken on large, low energy, lowland river systems: river systems where large wood is a significant physical feature on the in-channel environment. This study investigated the effect of reintroduced large wood on the hydraulic landscape of the Barwon-Darling River, Australia, at low flows. To achieve this, the study compared three hydraulic landscapes of replicated reference (naturally wooded), control (unwooded,) and managed (wood reintroduced) treatments on three low flow periods. These time periods were prior to the reintroduction of large wood to managed reaches; several months after the reintroduction of large wood into the managed reaches; and then more than four years after wood reintroduction following several large flood events. Hydraulic landscapes of reaches were characterised using a range of spatial measures calculated from velocity measurements taken with a boat-mounted Acoustic Doppler Profiler. We hypothesised that reintroduced large wood would increase the diversity of the hydraulic landscape at low flows and that managed reaches would be more similar to the reference reaches. Our results suggest that the reintroduction of large wood did not significantly change the character of the hydraulic landscape at the reach scale after several months (p = 0.16) or several years (p = 0.29). Overall, the character of the hydraulic landscape in the managed reaches was more similar to the hydraulic landscape of the control reaches than the hydraulic landscape of the reference reaches, at low flows. Some variability in the hydraulic landscapes was detected over time, and this may reflect reworking of riverbed sediments and sensitivity to variation in discharge. The lack of a response in the low flow hydraulic landscape to the reintroduction of large wood is inferred because the character (the size and complexity of individual pieces) and positioning of large wood in managed reaches did not mimic that of reference reaches effectively despite the abundance of wood pieces being similar in the reference and managed reaches. The results of this study highlight the importance of understanding the natural character and distribution of large wood on hydraulic landscapes in large low energy lowland river systems, especially when reintroducing large wood for river management purposes.

A survey of publication practices of single-case design researchers when treatments have small or large effects.

PubMed

Shadish, William R; Zelinsky, Nicole A M; Vevea, Jack L; Kratochwill, Thomas R

2016-09-01

The published literature often underrepresents studies that do not find evidence for a treatment effect; this is often called publication bias. Literature reviews that fail to include such studies may overestimate the size of an effect. Only a few studies have examined publication bias in single-case design (SCD) research, but those studies suggest that publication bias may occur. This study surveyed SCD researchers about publication preferences in response to simulated SCD results that show a range of small to large effects. Results suggest that SCD researchers are more likely to submit manuscripts that show large effects for publication and are more likely to recommend acceptance of manuscripts that show large effects when they act as a reviewer. A nontrivial minority of SCD researchers (4% to 15%) would drop 1 or 2 cases from the study if the effect size is small and then submit for publication. This article ends with a discussion of implications for publication practices in SCD research. © 2016 Society for the Experimental Analysis of Behavior.

Redesigning a Large Enrollment Course: The Impact on Academic Performance, Course Completion and Student Perceptions in Introductory Psychology

ERIC Educational Resources Information Center

Hudson, Danae L.; Whisenhunt, Brooke L.; Shoptaugh, Carol F.; Rost, Ann D.; Fondren-Happel, Rachel N.

2014-01-01

Increasing college enrollments, and decreased funding have led institutions and instructors to focus on developing courses that can be taught effectively in a large class format. This article presents the effectiveness of a redesigned, blended format of Introductory Psychology taught in large sections. The goals of the project included improving…

Seeking Effectiveness and Equity in a Large College Chemistry Course: An HLM Investigation of Peer-Led Guided Inquiry

ERIC Educational Resources Information Center

Lewis, Scott E.; Lewis, Jennifer E.

2008-01-01

This study employed hierarchical linear models (HLM) to investigate Peer-Led Guided Inquiry (PLGI), a teaching practice combining cooperative learning and inquiry and tailored for a large class. Ultimately, the study provided an example of the effective introduction of a reform pedagogical approach in a large class setting. In the narrative, the…

Context-dependence of long-term responses of terrestrial gastropod populations to large-scale disturbance.

Treesearch

Christopher P. Bloch; Michael R. Willi

2006-01-01

Large-scale natural disturbances, such as hurricanes, can have profound effects on animal populations. Nonetheless, generalizations about the effects of disturbance are elusive, and few studies consider long-term responses of a single population or community to multiple large-scale disturbance events. In the last 20 y, twomajor hurricanes (Hugo and Georges) have struck...

Cumulative effects of restoration efforts on ecological characteristics of an open water area within the Upper Mississippi River

USGS Publications Warehouse

Gray, B.R.; Shi, W.; Houser, J.N.; Rogala, J.T.; Guan, Z.; Cochran-Biederman, J. L.

2011-01-01

Ecological restoration efforts in large rivers generally aim to ameliorate ecological effects associated with large-scale modification of those rivers. This study examined whether the effects of restoration efforts-specifically those of island construction-within a largely open water restoration area of the Upper Mississippi River (UMR) might be seen at the spatial scale of that 3476ha area. The cumulative effects of island construction, when observed over multiple years, were postulated to have made the restoration area increasingly similar to a positive reference area (a proximate area comprising contiguous backwater areas) and increasingly different from two negative reference areas. The negative reference areas represented the Mississippi River main channel in an area proximate to the restoration area and an open water area in a related Mississippi River reach that has seen relatively little restoration effort. Inferences on the effects of restoration were made by comparing constrained and unconstrained models of summer chlorophyll a (CHL), summer inorganic suspended solids (ISS) and counts of benthic mayfly larvae. Constrained models forced trends in means or in both means and sampling variances to become, over time, increasingly similar to those in the positive reference area and increasingly dissimilar to those in the negative reference areas. Trends were estimated over 12- (mayflies) or 14-year sampling periods, and were evaluated using model information criteria. Based on these methods, restoration effects were observed for CHL and mayflies while evidence in favour of restoration effects on ISS was equivocal. These findings suggest that the cumulative effects of island building at relatively large spatial scales within large rivers may be estimated using data from large-scale surveillance monitoring programs. Published in 2010 by John Wiley & Sons, Ltd.

Effects of fat reserves on annual apparent survival of blackbirds Turdus merula

USGS Publications Warehouse

Miller, M.W.; Aradis, A.; Landucci, G.

2003-01-01

1. Fat reserves are stored energy that may help birds survive periods of harsh winter weather. This hypothesis predicts that annual apparent survival is higher for birds with large fat reserves than for birds with few or no fat reserves in winter. 2. Blackbirds (Turdus merula Linnaeus) were ringed in central Italy from 16 November to 20 February during 1990-2001. Fat scores were recorded for each bird. We used these capture-mark-recapture data for 1703 blackbirds to estimate the effect of large fat reserves on annual apparent survival, while controlling for transients, using computer programs surviv and mark. Probability of birds retaining large fat reserves, or retaining few fat reserves, over 2 successive years was also estimated. 3. Birds with large fat reserves did not have higher estimated annual apparent survival than birds with few fat reserves, inconsistent with our prediction. No effects of age, sex or year were detected on annual apparent survival. Birds with few fat reserves in any given year tended to have few fat reserves the following year. Birds with large fat reserves in any given year were unlikely to have large fat reserves the next year. 4. Large fat reserves may not increase annual survival of blackbirds wintering in central Italy. Winter weather in our study area may be too mild to effect survival. Alternatively, increased predation risk associated with large fat reserves may counteract any benefits of reduced starvation risk.

Employment effects of active labor market programs for sick-listed workers.

PubMed

Holm, Anders; Høgelund, Jan; Gørtz, Mette; Rasmussen, Kristin Storck; Houlberg, Helle Sofie Bøje

2017-03-01

We use register data of 88,948 sick-listed workers in Denmark over the period 2008-2011 to investigate the effect of active labor market programs on the duration until returning to non-subsidized employment and the duration of this employment. To identify causal treatment effects, we exploit over-time variation in the use of active labor market programs in 98 job centers and time-to- event. We find that ordinary education and subsidized job training have significant positive employment effects. Subsidized job training has a large, positive effect on the transition into employment but no effect on the subsequent employment duration. In contrast, ordinary education has a positive effect on employment duration but no effect on the transition into employment. The latter effect is the result of two opposing effects, a large positive effect of having completed education and a large negative lock-in effect, with low re-employment chances during program participation. Copyright © 2017. Published by Elsevier B.V.

Understanding the Effects of Defect Modification on the Structure and Properties of Fluorinated Polymers and Implications for Capacitive Energy Storage Technologies

NASA Astrophysics Data System (ADS)

Gadinski, Matthew R.

As the world begins to turn to alternative energy technologies and our electronic devices have become more both mobile and integral to everyday life, increasing interest has been focused on energy storage technologies. Capacitors are one of these energy storage technologies that utilize the polarization of an insulating material sandwiched by two electrodes as a means to store electric charge. Polymers are a preferred dielectric material for capacitors because of both their performance and practicality. However, polymer dielectrics are limited in energy density by low dielectric constant, and high loss at elevated temperature. This work aims to address these issues in order to enable polymer dielectrics for future applications and demands. As most polymer tend to have low dielectric constants (˜2-3), but impressive breakdown strengths, only a moderate improvement in dielectric constant has the potential to vastly improve the energy density of polymer capacitors. As such tremendous interest has been placed on poly(vinylidene fluoride) (PVDF) which has a dielectric of 10+ due to the highly polar C-F bonds of its backbone. To improve PVDF's performance defect monomers have been introduced to tailor the polymorphic crystalline phase to tune its properties. Additionally, this defect modification has implications for piezoelectric, electrocaloric, and thermoelectric applications of PVDF. In Chapter 2 a copolymer of VDF and bromotrifluoroethylene (BTFE) was produced. The effect of BTFE on the structure and dielectric properties of the resulting copolymer had not been previously evaluated, and its synthesis allowed for the comparison to previously reported VDF based copolymers including P(VDF-CTFE) and P(VDF-HFP). Through 19F NMR it was determined due to reactivity ratio differences of BTFE in comparison to previously explored copolymers, BTFE during synthesis is much more likely to link with itself. This results in long runs of BTFE-BTFE defects along with isolated single defects. These long runs are found to have dramatic effects on the distribution of chain conformations determined from FTIR, the melting temperature and total crystallinity determined by DSC, and the crystallite size, lattice spacing, and crystalline phase as determined by XRD. These results indicate that P(VDF-BTFE) has a mix of both included (single) and excluded defects (runs of defects) that rapidly inhibit crystallinity and alter phase. The dielectric analysis also confirmed this by a broadening of the Tg peak in the temperature dependent dielectric spectroscopy with increasing BTFE content in the monomer feed indicative of expansion of the interlamellar region due to defect exclusion. Chapter 3 explores P(VDF-BTFE) copolymers for capacitive energy storage. Due to the rapid decrease in crystallinity only low concentration copolymers (>2 mol %) BTFE were used. This was ultimately a result of stretching being required for high energy density to be exhibited. The 0.5 mol% BTFE copolymer samples was found to possess a discharge energy density of 20.8 J/cm 3 at 750 MV/m along with the highest breakdown strength of any reported PVDF based copolymer. It was found that for this small amount of defect monomer the gamma phase of PVDF was stabilized and mixed with beta phase and along with small crystallite size accounted for the high breakdown strength and energy density. Additionally, by utilizing only a small amount of defect monomer the decrease in crystallinity and melting temperature observed in previously examined PVDF copolymers was avoided. Chapter 4 examines a terpolymer of VDF, trifluoroethylene (TrFE), and chlorotrifluoroethylene (CTFE). The terpolymers of VDF have gained extensive interest as the use of the two defect monomer increases the dielectric constant to 40+ along with altering the polarization behavior from a normal ferroelectric to a relaxor ferroelectric characterized by a slim hysteresis loop. The current understanding of this behavior suggests that only the size of the third bulky monomer (CTFE in this case) determines whether a single hysteresis (SHL) or double hysteresis loop (DHL) will develop. This chapter shows that for a single composition of the terpolymer normal ferroelectric, SHL, and DHL behavior can be tuned through processing of the film. This was rationalized as films give long times to crystallize developed large ferroelectric domains within a paraelectric matrix resulting in the DHL behavior due to reversible switching of these domains. While if these films were stretched below the Tc SHL behavior was observed as this had the effect of dispersing these domains within the crystal. Chapter 5 changes focus to high temperature performance of polymer capacitors. The primary strategy to enable high temperature polymer capacitors has been the utilization of high Tg polymers because of their thermal stability. While these polymers have demonstrated stable dielectric properties at low field and high breakdown strengths at elevated temperatures, the high field loss limits their use at even mildly elevated temperature well below T g. Additionally, these polymers are expensive, brittle, and difficult to process, essentially defeating some of the primary reasons for utilizing a polymer in the first place. This chapter examines a commercially available, extrudable, high temperature fluoropolymer, known as polychlorotrifluoroethylene (PCTFE). The same defect monomer discussed with PVDF above. While this polymer showed comparable performance to BOPP at room temperature, it showed equally susceptible to high field loss at elevated temperature. However, the chlorine of the monomers allow for crosslinking of this polymer by commercially used peroxide/co-agent chemistry. Crosslinking lead to a substantial improvement of the crosslinked film over the pristine polymer, and superior energy density to the commercial high Tg polymers up to 150 °C. The reason for the improvement was found to be the formation of chemical defects produced during the crosslinking that were excluded from the crystalline phase. Through TSDC it was found that these defects concentrated in the interlamellar region led to a substantial enhancement of the charge trapping properties of this relaxation.

Note: Comparison experimental results of the laser heterodyne interferometer for angle measurement based on the Faraday effect.

PubMed

Zhang, Enzheng; Chen, Benyong; Zheng, Hao; Teng, Xueying; Yan, Liping

2018-04-01

A laser heterodyne interferometer for angle measurement based on the Faraday effect is proposed. A novel optical configuration, designed by using the orthogonal return method for a linearly polarized beam based on the Faraday effect, guarantees that the measurement beam can return effectively even though an angular reflector has a large lateral displacement movement. The optical configuration and measurement principle are presented in detail. Two verification experiments were performed; the experimental results show that the proposed interferometer can achieve a large lateral displacement tolerance of 7.4 mm and also can realize high precision angle measurement with a large measurement range.

Note: Comparison experimental results of the laser heterodyne interferometer for angle measurement based on the Faraday effect

NASA Astrophysics Data System (ADS)

Zhang, Enzheng; Chen, Benyong; Zheng, Hao; Teng, Xueying; Yan, Liping

2018-04-01

A laser heterodyne interferometer for angle measurement based on the Faraday effect is proposed. A novel optical configuration, designed by using the orthogonal return method for a linearly polarized beam based on the Faraday effect, guarantees that the measurement beam can return effectively even though an angular reflector has a large lateral displacement movement. The optical configuration and measurement principle are presented in detail. Two verification experiments were performed; the experimental results show that the proposed interferometer can achieve a large lateral displacement tolerance of 7.4 mm and also can realize high precision angle measurement with a large measurement range.

Effect of L-arginine supplementation on immune responsiveness in patients with sickle cell disease.

PubMed

Scavella, Arnette; Leiva, Lily; Monjure, Hanh; Zea, Arnold H; Gardner, Renee V

2010-08-01

L-arginine (L-Arg) is deficient in sickle cell disease (SSD) during vasoocclusion. We investigated possible causal relationship between L-Arg deficiency and immune dysfunction in SSD in steady-state. Fifteen patients with SSD in steady-state and 13 controls were studied. Plasma L-Arg levels were measured using liquid chromatography. T cell subsets and CD3zeta (CD3zeta) chain expression were analyzed using flow cytometry. Lymphocyte proliferative response to phytohemagglutinin (PHA) and production of IL-6 and interferon-gamma (IFN-gamma) were evaluated with and without L-Arg. SSD patients had significantly lower L-Arg levels than controls. CD3 and CD19 cell populations were comparable for both groups, but SSD patients had above normal numbers of natural killer cells (P = 0.06). Patients and controls exhibited significantly increased lymphocyte blastogenesis to PHA after introduction of L-Arg to cultures; response of patients was significantly greater than values for control individuals. Proliferative response to candida in SSD patients was significantly lower than in controls; L-Arg supplementation did not increase this response. L-Arg had no effect on blastogenic response to PPD and candida albicans. No effect was likewise seen in production of IL-6 and IFN-gamma after addition of L-Arg. CD3zeta chain expression increased after addition of L-Arg in both groups; differences were insignificant. L-Arg levels in steady-state SSD are significantly lower than in controls. L-Arg supplementation enhanced lymphocyte blastogenesis to PHA for both controls and patients, but not in response to antigen. There were no significant differences in CD3zeta chain expression although upregulation of expression occurred after L-Arg supplementation for both groups. (c) 2010 Wiley-Liss, Inc.

Accuracy Analysis on Large Blocks of High Resolution Images

NASA Technical Reports Server (NTRS)

Passini, Richardo M.

2007-01-01

Although high altitude frequencies effects are removed at the time of basic image generation, low altitude (Yaw) effects are still present in form of affinity/angular affinity. They are effectively removed by additional parameters. Bundle block adjustment based on properly weighted ephemeris/altitude quaternions (BBABEQ) are not enough to remove the systematic effect. Moreover, due to the narrow FOV of the HRSI, position and altitude are highly correlated making it almost impossible to separate and remove their systematic effects without extending the geometric model (Self-Calib.) The systematic effects gets evident on the increase of accuracy (in terms of RMSE at GCPs) for looser and relaxed ground control at the expense of large and strong block deformation with large residuals at check points. Systematic errors are most freely distributed and their effects propagated all over the block.

Effects of biasing on the galaxy power spectrum at large scales

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

Beltran Jimenez, Jose; Departamento de Fisica Teorica, Universidad Complutense de Madrid, 28040, Madrid; Durrer, Ruth

2011-05-15

In this paper we study the effect of biasing on the power spectrum at large scales. We show that even though nonlinear biasing does introduce a white noise contribution on large scales, the P(k){proportional_to}k{sup n} behavior of the matter power spectrum on large scales may still be visible and above the white noise for about one decade. We show, that the Kaiser biasing scheme which leads to linear bias of the correlation function on large scales, also generates a linear bias of the power spectrum on rather small scales. This is a consequence of the divergence on small scales ofmore » the pure Harrison-Zeldovich spectrum. However, biasing becomes k dependent if we damp the underlying power spectrum on small scales. We also discuss the effect of biasing on the baryon acoustic oscillations.« less

Effect of tachykinins in small human airways.

PubMed

Frossard, N; Barnes, J

1991-07-01

We have compared the contractile responses of substance P (SP) and neurokinin A (NKA) to that of the non degradable muscarinic agonist, carbachol, in small and large human airways in vitro. We have also investigated the effects of the neutral endopeptidase (NEP) inhibitor, thiorphan (100 microM) on these responses. NKA contracted large and small airways to a different extent (56% vs 92% of carbachol maximal contraction, respectively). NKA was significantly less potent in large vs small bronchi (EC50 = 150 +/- 15 vs 12 +/- 5 nM respectively, p less than 0.05). SP had a lower contractile effect in large (26% carbachol maximum) and small airways (59%) with EC50 values higher than 0.5 microM. The enkephalinase inhibitor thiorphan shifted the concentration-response curve to NKA to the left in large (EC50 = 35.2 +/- 8.2 nM) and small bronchi (EC50 = 2.8 +/- 1.3 nM, p less than 0.02). This shift was associated with an increase in the maximal contraction to NKA (75% in large vs 123% in small bronchi). The amplitude of contraction to SP was also potentiated in large (45%) and in smaller bronchi (101%). In conclusion, we have demonstrated that NKA has a significantly greater constrictor effect than a cholinergic agent in more peripheral human airways in vitro. This suggests that non cholinergic constrictor pathways are more likely to be important in more peripheral airways.

[Effect sizes, statistical power and sample sizes in "the Japanese Journal of Psychology"].

PubMed

Suzukawa, Yumi; Toyoda, Hideki

2012-04-01

This study analyzed the statistical power of research studies published in the "Japanese Journal of Psychology" in 2008 and 2009. Sample effect sizes and sample statistical powers were calculated for each statistical test and analyzed with respect to the analytical methods and the fields of the studies. The results show that in the fields like perception, cognition or learning, the effect sizes were relatively large, although the sample sizes were small. At the same time, because of the small sample sizes, some meaningful effects could not be detected. In the other fields, because of the large sample sizes, meaningless effects could be detected. This implies that researchers who could not get large enough effect sizes would use larger samples to obtain significant results.

Non-linear effects of soda taxes on consumption and weight outcomes.

PubMed

Fletcher, Jason M; Frisvold, David E; Tefft, Nathan

2015-05-01

The potential health impacts of imposing large taxes on soda to improve population health have been of interest for over a decade. As estimates of the effects of existing soda taxes with low rates suggest little health improvements, recent proposals suggest that large taxes may be effective in reducing weight because of non-linear consumption responses or threshold effects. This paper tests this hypothesis in two ways. First, we estimate non-linear effects of taxes using the range of current rates. Second, we leverage the sudden, relatively large soda tax increase in two states during the early 1990s combined with new synthetic control methods useful for comparative case studies. Our findings suggest virtually no evidence of non-linear or threshold effects. Copyright © 2014 John Wiley & Sons, Ltd.

Effects of a propionic acid-based preservative on storage characteristics, nutritive value, and energy content for alfalfa hays packaged in large, round bales

USDA-ARS?s Scientific Manuscript database

During 2009 and 2010, alfalfa (Medicago sativa L.) hays from two cuttings that were harvested from the same field site were used to evaluate the effects of a propionic acid-based preservative on the storage characteristics and nutritive value of hays stored as large, round bales. A total of 87 large...

National Implications for Urban School Systems: Strategic Planning in the Human Resource Management Department in a Large Urban School District

ERIC Educational Resources Information Center

Johnson, Clarence; Kritsonis, William Allan

2007-01-01

This article addresses several key ongoing issues in a large urban school district. Literature focuses on what make a large urban school district effective in Human Resource Management. The effectiveness is addressed through recruitment and retention practices. A comparison of the school district with current research is the main approach to the…

Effect of small and large animal skull bone on photoacoustic signal

NASA Astrophysics Data System (ADS)

Xu, Qiuyun; Volinski, Bridget; Hariri, Ali; Fatima, Afreen; Nasiriavanaki, Mohammadreza

2017-03-01

Photoacoustic imaging (PAI) has proved to be a promising non-invasive technique for diagnosis, prognosis and treatment monitoring of neurological disorders in small and large animals. Skull bone effects both light illumination and ultrasound propagation. Hence, the PA signal is largely affected. This study aims to quantify and compare the attenuation of PA signal due to the skull obstacle in the light illumination path, in the ultrasound propagation path, or in both. The effect of mouse, rat, and mesocephalic dog skull bones, ex-vivo, is quantitatively studied.

Group Size Effect on Cooperation in One-Shot Social Dilemmas II: Curvilinear Effect.

PubMed

Capraro, Valerio; Barcelo, Hélène

2015-01-01

In a world in which many pressing global issues require large scale cooperation, understanding the group size effect on cooperative behavior is a topic of central importance. Yet, the nature of this effect remains largely unknown, with lab experiments insisting that it is either positive or negative or null, and field experiments suggesting that it is instead curvilinear. Here we shed light on this apparent contradiction by considering a novel class of public goods games inspired to the realistic scenario in which the natural output limits of the public good imply that the benefit of cooperation increases fast for early contributions and then decelerates. We report on a large lab experiment providing evidence that, in this case, group size has a curvilinear effect on cooperation, according to which intermediate-size groups cooperate more than smaller groups and more than larger groups. In doing so, our findings help fill the gap between lab experiments and field experiments and suggest concrete ways to promote large scale cooperation among people.

Sex chromosomes and speciation in Drosophila

PubMed Central

Presgraves, Daven C.

2010-01-01

Two empirical rules suggest that sex chromosomes play a special role in speciation. The first is Haldane's rule— the preferential sterility and inviability of species hybrids of the heterogametic (XY) sex. The second is the disproportionately large effect of the X chromosome in genetic analyses of hybrid sterility. Whereas the causes of Haldane's rule are well established, the causes of the ‘large X-effect’ have remained controversial. New genetic analyses in Drosophila confirm that the X is a hotspot for hybrid male sterility factors, providing a proximate explanation for the large X-effect. Several other new findings— on faster X evolution, X chromosome meiotic drive, and the regulation of the X chromosome in the male-germline— provide plausible evolutionary explanations for the large X-effect. PMID:18514967

Paws without claws? Ecological effects of large carnivores in anthropogenic landscapes

PubMed Central

Sahlén, E.; Elmhagen, B.; Chamaillé-Jammes, S.; Sand, H.; Lone, K.; Cromsigt, J. P. G. M.

2016-01-01

Large carnivores are frequently presented as saviours of biodiversity and ecosystem functioning through their creation of trophic cascades, an idea largely based on studies coming primarily out of relatively natural landscapes. However, in large parts of the world, particularly in Europe, large carnivores live in and are returning to strongly human-modified ecosystems. At present, we lack a coherent framework to predict the effects of large carnivores in these anthropogenic landscapes. We review how human actions influence the ecological roles of large carnivores by affecting their density or behaviour or those of mesopredators or prey species. We argue that the potential for density-mediated trophic cascades in anthropogenic landscapes is limited to unproductive areas where even low carnivore numbers may impact prey densities or to the limited parts of the landscape where carnivores are allowed to reach ecologically functional densities. The potential for behaviourally mediated trophic cascades may be larger and more widespread, because even low carnivore densities affect prey behaviour. We conclude that predator–prey interactions in anthropogenic landscapes will be highly context-dependent and human actions will often attenuate the ecological effects of large carnivores. We highlight the knowledge gaps and outline a new research avenue to study the role of carnivores in anthropogenic landscapes. PMID:27798302

Impact of Design Effects in Large-Scale District and State Assessments

ERIC Educational Resources Information Center

Phillips, Gary W.

2015-01-01

This article proposes that sampling design effects have potentially huge unrecognized impacts on the results reported by large-scale district and state assessments in the United States. When design effects are unrecognized and unaccounted for they lead to underestimating the sampling error in item and test statistics. Underestimating the sampling…

Evaluating the Effectiveness of a Large-Scale Professional Development Programme

ERIC Educational Resources Information Center

Main, Katherine; Pendergast, Donna

2017-01-01

An evaluation of the effectiveness of a large-scale professional development (PD) programme delivered to 258 schools in Queensland, Australia is presented. Formal evaluations were conducted at two stages during the programme using a tool developed from Desimone's five core features of effective PD. Descriptive statistics of 38 questions and…

The Relationship of Class Size Effects and Teacher Salary

ERIC Educational Resources Information Center

Peevely, Gary; Hedges, Larry; Nye, Barbara A.

2005-01-01

The effects of class size on academic achievement have been studied for decades. Although the results of small-scale, randomized experiments and large-scale, econometric studies point to positive effects of small classes, some scholars see the evidence as ambiguous. Recent analyses from a 4-year, large-scale, randomized experiment on the effects…

Teacher Effects and Teacher-Related Policies

ERIC Educational Resources Information Center

Jackson, C. Kirabo; Rockoff, Jonah E.; Staiger, Douglas O.

2014-01-01

The emergence of large longitudinal data sets linking students to teachers has led to rapid growth in the study of teacher effects on student outcomes by economists over the past decade. One large literature has documented wide variation in teacher effectiveness that is not well explained by observable student or teacher characteristics. A second…

Disproportionate effects of non-colonial small herbivores on structure and diversity of grassland dominated by large herbivores

USDA-ARS?s Scientific Manuscript database

The response of semiarid grasslands to small, non-colonial herbivores has received little attention, focusing primarily on the effects of granivore assemblages on annual plant communities. We studied the long-term effects of small and large herbivores on vegetation structure and species diversity of...

Identification of (E,E)-2,4-undecadienal from coriander (Coriandrum sativum L.) as a highly effective deodorant compound against the offensive odor of porcine large intestine.

PubMed

Ikeura, Hiromi; Kohara, Kaori; Li, Xin-Xian; Kobayashi, Fumiyuki; Hayata, Yasuyoshi

2010-10-27

The leaves of coriander ( Coriandrum sativum L.) exhibited a strong deodorizing effect against porcine internal organs (large intestine). The effective deodorizing compounds of coriander were identified by separating the volatile component of coriander, testing the effectiveness of each fraction against the offensive odor of porcine large intestine, and then identifying the compounds by GC-MS. The volatile component of coriander was first separated into six fractions (A-F) by preparative gas chromatography, and the deodorizing activity of each of these fractions against the offensive odor was measured. Fraction D, which showed the strongest deodorizing effect, was then separated into 12 subfractions by preparative GC. The deodorant activity of each subfraction was evaluated, and the deodorant compounds were identified by GC-MS. It was discovered that (E,E)-2,4-undecadienal was the most effective deodorizing compound. The deodorizing activity of (E,E)-2,4-undecadienal on the porcine large intestine increased as with concentration, reaching almost complete deodorizing ability at 10 ppb.

Numerical Simulations of Vortical Mode Stirring: Effects of Large Scale Shear and Strain

DTIC Science & Technology

2015-09-30

Numerical Simulations of Vortical Mode Stirring: Effects of Large-Scale Shear and Strain M.-Pascale Lelong NorthWest Research Associates...can be implemented in larger-scale ocean models. These parameterizations will incorporate the effects of local ambient conditions including latitude...talk at the 1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Nonlinear Effects in Internal Waves Conference held

How do different data logger sizes and attachment positions affect the diving behaviour of little penguins?

NASA Astrophysics Data System (ADS)

Ropert-Coudert, Yan; Knott, Nathan; Chiaradia, André; Kato, Akiko

2007-02-01

It is crucial in any bio-logging study to establish the potential effect that attachment of loggers may have on the animal. This ensures that the behaviour monitored by the loggers has a biological relevance, as well as for ethical reasons. Evaluation of the effects of externally attached loggers shows that they increase the drag of swimming animals and increase their energy expenditure. Nevertheless, little research has been done on the effects of size or position of such loggers. In this study, we tested whether the size (i.e. large: 4.9% versus small: 3.4% of the bird's frontal area) or the place of attachment (middle versus lower back) affected the diving behaviour of male and female little penguins ( Eudyptula minor). The positioning of the data logger on the middle or lower section of little penguins' back had little, if no effect, on the diving variables measured in this study. Size of the loggers, however, had strong effects. Birds with large loggers made shorter dives and reached shallower depths than those with small loggers. In addition, birds with large loggers made more dives probably to compensate for the extra cost of carrying a large logger. The measured variables also differed between the sexes, with males diving deeper and longer than females. Logger size had a sex-specific effect on the trip duration and descent speed, with males equipped with large loggers staying longer at sea than those with small loggers, and females with large loggers descending faster than those with small loggers. From our results, it appears that effects of logger position do not exist or are very small in comparison with the effects of logger size. The results of the current study indicate that the effects of size of loggers be evaluated more commonly in bio-logging research into the diving activity of free-ranging birds.

Fear of large carnivores causes a trophic cascade

PubMed Central

Suraci, Justin P.; Clinchy, Michael; Dill, Lawrence M.; Roberts, Devin; Zanette, Liana Y.

2016-01-01

The fear large carnivores inspire, independent of their direct killing of prey, may itself cause cascading effects down food webs potentially critical for conserving ecosystem function, particularly by affecting large herbivores and mesocarnivores. However, the evidence of this has been repeatedly challenged because it remains experimentally untested. Here we show that experimentally manipulating fear itself in free-living mesocarnivore (raccoon) populations using month-long playbacks of large carnivore vocalizations caused just such cascading effects, reducing mesocarnivore foraging to the benefit of the mesocarnivore's prey, which in turn affected a competitor and prey of the mesocarnivore's prey. We further report that by experimentally restoring the fear of large carnivores in our study system, where most large carnivores have been extirpated, we succeeded in reversing this mesocarnivore's impacts. We suggest that our results reinforce the need to conserve large carnivores given the significant “ecosystem service” the fear of them provides. PMID:26906881

N-body simulations of gravitational redshifts and other relativistic distortions of galaxy clustering

NASA Astrophysics Data System (ADS)

Zhu, Hongyu; Alam, Shadab; Croft, Rupert A. C.; Ho, Shirley; Giusarma, Elena

2017-10-01

Large redshift surveys of galaxies and clusters are providing the first opportunities to search for distortions in the observed pattern of large-scale structure due to such effects as gravitational redshift. We focus on non-linear scales and apply a quasi-Newtonian approach using N-body simulations to predict the small asymmetries in the cross-correlation function of two galaxy different populations. Following recent work by Bonvin et al., Zhao and Peacock and Kaiser on galaxy clusters, we include effects which enter at the same order as gravitational redshift: the transverse Doppler effect, light-cone effects, relativistic beaming, luminosity distance perturbation and wide-angle effects. We find that all these effects cause asymmetries in the cross-correlation functions. Quantifying these asymmetries, we find that the total effect is dominated by the gravitational redshift and luminosity distance perturbation at small and large scales, respectively. By adding additional subresolution modelling of galaxy structure to the large-scale structure information, we find that the signal is significantly increased, indicating that structure on the smallest scales is important and should be included. We report on comparison of our simulation results with measurements from the SDSS/BOSS galaxy redshift survey in a companion paper.

The large sample size fallacy.

PubMed

Lantz, Björn

2013-06-01

Significance in the statistical sense has little to do with significance in the common practical sense. Statistical significance is a necessary but not a sufficient condition for practical significance. Hence, results that are extremely statistically significant may be highly nonsignificant in practice. The degree of practical significance is generally determined by the size of the observed effect, not the p-value. The results of studies based on large samples are often characterized by extreme statistical significance despite small or even trivial effect sizes. Interpreting such results as significant in practice without further analysis is referred to as the large sample size fallacy in this article. The aim of this article is to explore the relevance of the large sample size fallacy in contemporary nursing research. Relatively few nursing articles display explicit measures of observed effect sizes or include a qualitative discussion of observed effect sizes. Statistical significance is often treated as an end in itself. Effect sizes should generally be calculated and presented along with p-values for statistically significant results, and observed effect sizes should be discussed qualitatively through direct and explicit comparisons with the effects in related literature. © 2012 Nordic College of Caring Science.

On the relativistic large-angle electron collision operator for runaway avalanches in plasmas

NASA Astrophysics Data System (ADS)

Embréus, O.; Stahl, A.; Fülöp, T.

2018-02-01

Large-angle Coulomb collisions lead to an avalanching generation of runaway electrons in a plasma. We present the first fully conservative large-angle collision operator, derived from the relativistic Boltzmann operator. The relation to previous models for large-angle collisions is investigated, and their validity assessed. We present a form of the generalized collision operator which is suitable for implementation in a numerical kinetic equation solver, and demonstrate the effect on the runaway-electron growth rate. Finally we consider the reverse avalanche effect, where runaways are slowed down by large-angle collisions, and show that the choice of operator is important if the electric field is close to the avalanche threshold.

Primary propulsion/large space system interactions

NASA Technical Reports Server (NTRS)

Dergance, R. H.

1980-01-01

Three generic types of structural concepts and nonstructural surface densities were selected and combined to represent potential LSS applications. The design characteristics of various classes of large space systems that are impacted by primary propulsion thrust required to effect orbit transfer were identified. The effects of propulsion system thrust-to-mass ratio, thrust transients, and performance on the mass, area, and orbit transfer characteristics of large space systems were determined.

Exploring proximity effects and large depth of field in helium ion beam lithography: large-area dense patterns and tilted surface exposure.

PubMed

Flatabø, Ranveig; Agarwal, Akshay; Hobbs, Richard; Greve, Martin M; Holst, Bodil; Berggren, Karl K

2018-07-06

Helium ion beam lithography (HIL) is an emerging nanofabrication technique. It benefits from a reduced interaction volume compared to that of an electron beam of similar energy, and hence reduced long-range scattering (proximity effect), higher resist sensitivity and potentially higher resolution. Furthermore, the small angular spread of the helium ion beam gives rise to a large depth of field. This should enable patterning on tilted and curved surfaces without the need of any additional adjustments, such as laser-auto focus. So far, most work on HIL has been focused on exploiting the reduced proximity effect to reach single-digit nanometer resolution, and has thus been concentrated on single-pixel exposures over small areas. Here we explore two new areas of application. Firstly, we investigate the proximity effect in large-area exposures and demonstrate HIL's capabilities in fabricating precise high-density gratings on large planar surfaces (100 μm × 100 μm, with pitch down to 35 nm) using an area dose for exposure. Secondly, we exploit the large depth of field by making the first HIL patterns on tilted surfaces (sample stage tilted 45°). We demonstrate a depth of field greater than 100 μm for a resolution of about 20 nm.

Herbivore-initiated interaction cascades and their modulation by productivity in an African savanna

PubMed Central

Pringle, Robert M.; Young, Truman P.; Rubenstein, Daniel I.; McCauley, Douglas J.

2007-01-01

Despite conceptual recognition that indirect effects initiated by large herbivores are likely to have profound impacts on ecological community structure and function, the existing literature on indirect effects focuses largely on the role of predators. As a result, we know neither the frequency and extent of herbivore-initiated indirect effects nor the mechanisms that regulate their strength. We examined the effects of ungulates on taxa (plants, arthropods, and an insectivorous lizard) representing several trophic levels, using a series of large, long-term, ungulate-exclusion plots that span a landscape-scale productivity gradient in an African savanna. At each of six sites, lizards, trees, and the numerically dominant order of arthropods (Coleoptera) were more abundant in the absence of ungulates. The effect of ungulates on arthropods was mediated by herbaceous vegetation cover. The effect on lizards was simultaneously mediated by both tree density (lizard microhabitat) and arthropod abundance (lizard food). The magnitudes of the experimental effects on all response variables (trees, arthropods, and lizards) were negatively correlated with two distinct measures of primary productivity. These results demonstrate strong cascading effects of ungulates, both trophic and nontrophic, and support the hypothesis that productivity regulates the strength of these effects. Hence, the strongest indirect effects (and thus, the greatest risks to ecosystem integrity after large mammals are extirpated) are likely to occur in low-productivity habitats. PMID:17190823

Impaired flexibility in decision making in rats after administration of the pharmacological stressor yohimbine.

PubMed

Schwager, Andrea L; Haack, Andrew K; Taha, Sharif A

2014-10-01

Stress-induced disruption of decision making has been hypothesized to contribute to drug-seeking behaviors and addiction. Noradrenergic signaling plays a central role in mediating stress responses. However, the effects of acute stress on decision making, and the role of noradrenergic signaling in regulating these effects, have not been well characterized. To characterize changes in decision making caused by acute pharmacological stress, the effects of yohimbine (an α2-adrenergic antagonist) were examined in a delay discounting task. Noradrenergic contributions to decision making were further characterized by examining the effects of propranolol (a β antagonist), prazosin (an α1 antagonist), and guanfacine (an α2 agonist). Sprague-Dawley rats were administered drugs prior to performance on a delay discounting task, in which the delay preceding the large reward increased within each session (ascending delays). To dissociate drug-induced changes in delay sensitivity from behavioral inflexibility, drug effects were subsequently tested in a modified version of the discounting task, in which the delay preceding the large reward decreased within each session (descending delays). Yohimbine increased choice of the large reward when tested with ascending delays but decreased choice of the same large reward when tested with descending delays, suggesting that drug effects could be attributed to perseverative choice of the lever preferred at the beginning of the session. Propranolol increased choice of the large reward when tested with ascending delays. Prazosin and guanfacine had no effect on reward choice. The stress-like effects of yohimbine administration may impair decision making by causing inflexible, perseverative behavior.

Differential response of surface temperature and atmospheric temperature to the biogeophysical effects of deforestation

NASA Astrophysics Data System (ADS)

Winckler, J.; Reick, C. H.; Lejeune, Q.; Pongratz, J.

2017-12-01

Deforestation influences temperature locally by changing the water, energy and momentum balance. While most observation-based studies and some modeling studies focused on the effects on surface temperature, other studies focused on the effects on near-surface air temperature. However, these two variables may respond differently to deforestation because changes in albedo and surface roughness may alter the land-atmosphere coupling and thus the vertical temperature distribution. Thus it is unclear whether it is possible to compare studies that assess the impacts of deforestation on these two different variables. Here, we analyze the biogeophysical effects of global-scale deforestation in the climate model MPI-ESM separately for surface temperature, 2m-air temperature and temperature the lowest atmospheric model layer. We investigate why the response of these variables differs by isolating the effects of only changing surface albedo and only changing surface roughness and by separating effects that are induced at the location of deforestation (local effects) from effects that are induced by advection and changes in circulation (nonlocal effects). Concerning surface temperature, we find that the local effects of deforestation lead to a global mean warming which is overcompensated by the nonlocal effects (up to 0.1K local warming versus -0.3K nonlocal cooling). The surface warming in the local effects is largely driven by the change in surface roughness while the cooling in the nonlocal effects is largely driven by the change in surface albedo. The nonlocal effects are largely consistent across surface temperature, 2m-air temperature, and the temperature of the lowest atmospheric layer. However, the local effects strongly differ across the three considered variables. The local effects are strong for surface temperature, but substantially weaker in the 2m-air temperature and largely absent in the lowest atmospheric layer. We conclude that studies focusing on the deforestation effects on surface temperature should not be compared to studies focusing on the effects on air temperature. While the local effects on surface temperature are useful for model evaluation, they might be less relevant for local adaptation and mitigation than previously thought because they might largely be absent in the atmosphere.

A Study of Large Droplet Ice Accretions in the NASA-Lewis IRT at Near-Freezing Conditions

NASA Technical Reports Server (NTRS)

Miller, Dean R.; Addy, Harold E. , Jr.; Ide, Robert F.

1996-01-01

This report documents the results of an experimental study on large droplet ice accretions which was conducted in the NASA-Lewis Icing Research Tunnel (IRT) with a full-scale 77.25 inch chord Twin-Otter wing section. This study was intended to: (1) document the existing capability of the IRT to produce a large droplet icing cloud, and (2) study the effect of various parameters on large droplet ice accretions. Results are presented from a study of the IRT's capability to produce large droplets with MVD of 99 and 160 microns. The effect of the initial water droplet temperature on the resultant ice accretion was studied for different initial spray bar air and water temperatures. The initial spray bar water temperature was found to have no discernible effect upon the large droplet ice accretions. Also, analytical and experimental results suggest that the water droplet temperature is very nearly the same as the tunnel ambient temperature, thus providing a realistic simulation of the large droplet natural icing condition. The effect of temperature, droplet size, airspeed, angle-of attack, flap setting and de-icer boot cycling time on ice accretion was studied, and will be discussed in this report. It was found that, in almost all of the cases studied, an ice ridge formed immediately aft of the active portion of the de-icer boot. This ridge was irregular in shape, varied in location, and was in some cases discontinuous due to aerodynamic shedding.

The effects of large beach debris on nesting sea turtles

USGS Publications Warehouse

Fujisaki, Ikuko; Lamont, Margaret M.

2016-01-01

A field experiment was conducted to understand the effects of large beach debris on sea turtle nesting behavior as well as the effectiveness of large debris removal for habitat restoration. Large natural and anthropogenic debris were removed from one of three sections of a sea turtle nesting beach and distributions of nests and false crawls (non-nesting crawls) in pre- (2011–2012) and post- (2013–2014) removal years in the three sections were compared. The number of nests increased 200% and the number of false crawls increased 55% in the experimental section, whereas a corresponding increase in number of nests and false crawls was not observed in the other two sections where debris removal was not conducted. The proportion of nest and false crawl abundance in all three beach sections was significantly different between pre- and post-removal years. The nesting success, the percent of successful nests in total nesting attempts (number of nests + false crawls), also increased from 24% to 38%; however the magnitude of the increase was comparably small because both the number of nests and false crawls increased, and thus the proportion of the nesting success in the experimental beach in pre- and post-removal years was not significantly different. The substantial increase in sea turtle nesting activities after the removal of large debris indicates that large debris may have an adverse impact on sea turtle nesting behavior. Removal of large debris could be an effective restoration strategy to improve sea turtle nesting.

Large Faraday effect of borate glasses with high Tb3+ content prepared by containerless processing

NASA Astrophysics Data System (ADS)

Suzuki, Futoshi; Sato, Fumio; Oshita, Hiroyuki; Yao, Situ; Nakatsuka, Yuko; Tanaka, Katsuhisa

2018-02-01

Borate glasses containing a large amount of Tb3+ ions have been prepared by containerless processing. The content of Tb2O3 reached 60 mol%. The glass bearing the highest content of Tb3+ ions showed a large Faraday effect; the Verdet constant was 234 rad/T m. Annealing of the glasses in H2/N2 atmosphere resulted in a low optical absorption coefficient, leading to an extremely large magneto-optical figure of merit that was ∼1.7 times higher than that of Tb3Ga5O12 single crystal.

Large-particle calcium hydroxylapatite injection for correction of facial wrinkles and depressions.

PubMed

Alam, Murad; Havey, Jillian; Pace, Natalie; Pongprutthipan, Marisa; Yoo, Simon

2011-07-01

Small-particle calcium hydroxylapatite (Radiesse, Merz, Frankfurt, Germany) is safe and effective for facial wrinkle reduction, and has medium-term persistence for this indication. There is patient demand for similar fillers that may be longer lasting. We sought to assess the safety and persistence of effect in vivo associated with use of large-particle calcium hydroxylapatite (Coaptite, Merz) for facial augmentation and wrinkle reduction. This was a case series of 3 patients injected with large-particle calcium hydroxylapatite. Large-particle calcium hydroxylapatite appears to be effective and well tolerated for correction of facial depressions, including upper mid-cheek atrophy, nasolabial creases, and HIV-associated lipoatrophy. Adverse events included erythema and edema, and transient visibility of the injection sites. Treated patients, all of whom had received small-particle calcium hydroxylapatite correction before, noted improved persistence at 6 and 15 months with the large-particle injections as compared with prior small-particle injections. This is a small case series, and there was no direct control to compare the persistence of small-particle versus large-particle correction. For facial wrinkle correction, large-particle calcium hydroxylapatite has a safety profile comparable with that of small-particle calcium hydroxylapatite. The large-particle variant may have longer persistence that may be useful in selected clinical circumstances. Copyright © 2010 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

Effects of large herbivores on grassland arthropod diversity.

PubMed

van Klink, R; van der Plas, F; van Noordwijk, C G E Toos; WallisDeVries, M F; Olff, H

2015-05-01

Both arthropods and large grazing herbivores are important components and drivers of biodiversity in grassland ecosystems, but a synthesis of how arthropod diversity is affected by large herbivores has been largely missing. To fill this gap, we conducted a literature search, which yielded 141 studies on this topic of which 24 simultaneously investigated plant and arthropod diversity. Using the data from these 24 studies, we compared the responses of plant and arthropod diversity to an increase in grazing intensity. This quantitative assessment showed no overall significant effect of increasing grazing intensity on plant diversity, while arthropod diversity was generally negatively affected. To understand these negative effects, we explored the mechanisms by which large herbivores affect arthropod communities: direct effects, changes in vegetation structure, changes in plant community composition, changes in soil conditions, and cascading effects within the arthropod interaction web. We identify three main factors determining the effects of large herbivores on arthropod diversity: (i) unintentional predation and increased disturbance, (ii) decreases in total resource abundance for arthropods (biomass) and (iii) changes in plant diversity, vegetation structure and abiotic conditions. In general, heterogeneity in vegetation structure and abiotic conditions increases at intermediate grazing intensity, but declines at both low and high grazing intensity. We conclude that large herbivores can only increase arthropod diversity if they cause an increase in (a)biotic heterogeneity, and then only if this increase is large enough to compensate for the loss of total resource abundance and the increased mortality rate. This is expected to occur only at low herbivore densities or with spatio-temporal variation in herbivore densities. As we demonstrate that arthropod diversity is often more negatively affected by grazing than plant diversity, we strongly recommend considering the specific requirements of arthropods when applying grazing management and to include arthropods in monitoring schemes. Conservation strategies aiming at maximizing heterogeneity, including regulation of herbivore densities (through human interventions or top-down control), maintenance of different types of management in close proximity and rotational grazing regimes, are the most promising options to conserve arthropod diversity. © 2014 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.

Effects of large herbivores on grassland arthropod diversity

PubMed Central

van Klink, R; van der Plas, F; van Noordwijk, C G E (Toos); WallisDeVries, M F; Olff, H

2015-01-01

Both arthropods and large grazing herbivores are important components and drivers of biodiversity in grassland ecosystems, but a synthesis of how arthropod diversity is affected by large herbivores has been largely missing. To fill this gap, we conducted a literature search, which yielded 141 studies on this topic of which 24 simultaneously investigated plant and arthropod diversity. Using the data from these 24 studies, we compared the responses of plant and arthropod diversity to an increase in grazing intensity. This quantitative assessment showed no overall significant effect of increasing grazing intensity on plant diversity, while arthropod diversity was generally negatively affected. To understand these negative effects, we explored the mechanisms by which large herbivores affect arthropod communities: direct effects, changes in vegetation structure, changes in plant community composition, changes in soil conditions, and cascading effects within the arthropod interaction web. We identify three main factors determining the effects of large herbivores on arthropod diversity: (i) unintentional predation and increased disturbance, (ii) decreases in total resource abundance for arthropods (biomass) and (iii) changes in plant diversity, vegetation structure and abiotic conditions. In general, heterogeneity in vegetation structure and abiotic conditions increases at intermediate grazing intensity, but declines at both low and high grazing intensity. We conclude that large herbivores can only increase arthropod diversity if they cause an increase in (a)biotic heterogeneity, and then only if this increase is large enough to compensate for the loss of total resource abundance and the increased mortality rate. This is expected to occur only at low herbivore densities or with spatio-temporal variation in herbivore densities. As we demonstrate that arthropod diversity is often more negatively affected by grazing than plant diversity, we strongly recommend considering the specific requirements of arthropods when applying grazing management and to include arthropods in monitoring schemes. Conservation strategies aiming at maximizing heterogeneity, including regulation of herbivore densities (through human interventions or top-down control), maintenance of different types of management in close proximity and rotational grazing regimes, are the most promising options to conserve arthropod diversity. PMID:24837856

Anthropic prediction for a large multi-jump landscape

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

Schwartz-Perlov, Delia, E-mail: delia@perlov.com

2008-10-15

The assumption of a flat prior distribution plays a critical role in the anthropic prediction of the cosmological constant. In a previous paper we analytically calculated the distribution for the cosmological constant, including the prior and anthropic selection effects, in a large toy 'single-jump' landscape model. We showed that it is possible for the fractal prior distribution that we found to behave as an effectively flat distribution in a wide class of landscapes, but only if the single-jump size is large enough. We extend this work here by investigating a large (N{approx}10{sup 500}) toy 'multi-jump' landscape model. The jump sizesmore » range over three orders of magnitude and an overall free parameter c determines the absolute size of the jumps. We will show that for 'large' c the distribution of probabilities of vacua in the anthropic range is effectively flat, and thus the successful anthropic prediction is validated. However, we argue that for small c, the distribution may not be smooth.« less

Effects of ungulate disturbance and weather variation on Pediocactus winkleri: insights from long-term monitoring

USGS Publications Warehouse

Clark, Deborah J.; Clark, Thomas O.; Duniway, Michael C.; Flagg, Cody B.

2015-01-01

Population dynamics and effects of large ungulate disturbances on Winkler cactus (Pediocactus winkleri K.D. Heil) were documented annually over a 20-year time span at one plot within Capitol Reef National Park, Utah. This cactus species was federally listed as threatened in 1998. The study began in 1995 to gain a better understanding of life history aspects and threats to this species. Data were collected annually in early spring and included diameter, condition, reproductive structures, mortality, recruitment, and disturbance by large ungulates. We used odds ratio and probability model analyses to determine effects of large ungulate trampling and weather on these cacti. During the study, plot population declined by 18%, with trampling of cactus, low precipitation, and cold spring temperatures implicated as causal factors. Precipitation and temperature affected flowering, mortality, and recruitment. Large ungulate disturbances increased mortality and reduced the probability of flowering. These results suggest that large ungulate disturbances and recent climate regimes have had an adverse impact on long-term persistence of this cactus.

77 FR 9700 - Large Residential Washers From Korea and Mexico

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-17

...)] Large Residential Washers From Korea and Mexico Determinations On the basis of the record \\1\\ developed... reasonable indication that an industry is materially injured by reason of imports from Mexico of large... imports of large residential washers from Mexico. Accordingly, effective December 30, 2011, the Commission...

Large-Scale Covariability Between Aerosol and Precipitation Over the 7-SEAS Region: Observations and Simulations

NASA Technical Reports Server (NTRS)

Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Zhang, Chidong; Jeong, Myeong Jae; Gautam, Ritesh; Bettenhausen, Corey; Sayer, Andrew M.; Hansell, Richard A.; Liu, Xiaohong;

When the Test of Mediation is More Powerful than the Test of the Total Effect

PubMed Central

O'Rourke, Holly P.; MacKinnon, David P.

2014-01-01

Although previous research has studied power in mediation models, the extent to which the inclusion of a mediator will increase power has not been investigated. First, a study compared analytical power of the mediated effect to the total effect in a single mediator model to identify the situations in which the inclusion of one mediator increased statistical power. Results from the first study indicated that including a mediator increased statistical power in small samples with large coefficients and in large samples with small coefficients, and when coefficients were non-zero and equal across models. Next, a study identified conditions where power was greater for the test of the total mediated effect compared to the test of the total effect in the parallel two mediator model. Results indicated that including two mediators increased power in small samples with large coefficients and in large samples with small coefficients, the same pattern of results found in the first study. Finally, a study assessed analytical power for a sequential (three-path) two mediator model and compared power to detect the three-path mediated effect to power to detect both the test of the total effect and the test of the mediated effect for the single mediator model. Results indicated that the three-path mediated effect had more power than the mediated effect from the single mediator model and the test of the total effect. Practical implications of these results for researchers are then discussed. PMID:24903690

Effects of long-term use by big game and livestock in the Blue Mountains forest ecosystems.

Treesearch

Larry L. Irwin; John G. Cook; Robert A. Riggs; Jon M. Skovlin

1994-01-01

The effects on eastside forest ecosystems from long-term grazing by large mammals are assessed, because long-term herbivory can reduce or increase ecosystem productivity. The assessment emphasizes elk and cattle in the Blue Mountains of northeast Oregon and southeast Washington. Histories of populations of large mammals and their effects in the Blue Mountains are...

Delayed Effects of a Low-Cost and Large-Scale Summer Reading Intervention on Elementary School Children's Reading Comprehension

ERIC Educational Resources Information Center

Kim, James S.; Guryan, Jonathan; White, Thomas G.; Quinn, David M.; Capotosto, Lauren; Kingston, Helen Chen

2016-01-01

To improve the reading comprehension outcomes of children in high-poverty schools, policymakers need to identify reading interventions that show promise of effectiveness at scale. This study evaluated the effectiveness of a low-cost and large-scale summer reading intervention that provided comprehension lessons at the end of the school year and…

Creating a Community of Inquiry in Large-Enrollment Online Courses: An Exploratory Study on the Effect of Protocols within Online Discussions

ERIC Educational Resources Information Center

Chen, Baiyun; deNoyelles, Aimee; Patton, Kerry; Zydney, Janet

2017-01-01

It can be difficult to foster focused and effective communication in online discussions within large classes. Implementing protocols is a strategy that may help students communicate more effectively, facilitate their learning process, and improve the quality of their work within online discussions. In this exploratory research study, a protocol…

Population density of North American elk: effects on plant diversity.

PubMed

Stewart, Kelley M; Bowyer, R Terry; Kie, John G; Dick, Brian L; Ruess, Roger W

2009-08-01

Large, herbivorous mammals have profound effects on ecosystem structure and function and often act as keystone species in ecosystems they inhabit. Density-dependent processes associated with population structure of large mammals may interact with ecosystem functioning to increase or decrease biodiversity, depending on the relationship of herbivore populations relative to the carrying capacity (K) of the ecosystem. We tested for indirect effects of population density of large herbivores on plant species richness and diversity in a montane ecosystem, where increased net aboveground primary productivity (NAPP) in response to low levels of herbivory has been reported. We documented a positive, linear relationship between plant-species diversity and richness with NAPP. Structural equation modeling revealed significant indirect relationships between population density of herbivores, NAPP, and species diversity. We observed an indirect effect of density-dependent processes in large, herbivorous mammals and species diversity of plants through changes in NAPP in this montane ecosystem. Changes in species diversity of plants in response to herbivory may be more indirect in ecosystems with long histories of herbivory. Those subtle or indirect effects of herbivory may have strong effects on ecosystem functioning, but may be overlooked in plant communities that are relatively resilient to herbivory.

[Emerging novel therapeutic strategy for α-dystroglycanopathy by Large].

PubMed

Saito, Fumiaki

2011-11-01

The past decade of researches have revealed mutations of known or putative glycosyltransferases in several types of muscular dystrophy, including Fukuyama-type congenital muscular dystrophy. In these disorders, the function of α-dystroglycan is severely decreased, therefore they are called α-dystroglycanopathy. Recently, putative glycosyltransferase Large was shown to restore the defective function of α-dystroglycan, thus, it is an intriguing idea to apply this effect to the therapy of α-dystroglycanopathy. In the present study, we sought to test this possibility. Using several cultured cell lines, we confirmed that the overexpression of Large results in hyperglycosylation and marked enhancement of the function of α-dystroglycan. For this effect, the whole luminal domain of Large was shown to be necessary using several deletion constructs. We further generated transgenic mice overexpressing Large ubiquitously. In each tissue of the mice, the glycosylation of α-dystroglycan and its laminin binding activity was remarkably increased. Moreover, the morphological analyses on each tissue stained by H-E revealed no significant abnormality in the transgenic mice, suggesting no serious side effects by the overexpression of Large. Taken together, these results indicate that the restoration of the function of α-dystroglycan by Large should be an important molecular target to develop therapeutic strategies for α-dystroglycanopathy.

Charge renormalization at the large-D limit for N-electron atoms and weakly bound systems

NASA Astrophysics Data System (ADS)

Kais, S.; Bleil, R.

1995-05-01

We develop a systematic way to determine an effective nuclear charge ZRD such that the Hartree-Fock results will be significantly closer to the exact energies by utilizing the analytically known large-D limit energies. This method yields an expansion for the effective nuclear charge in powers of (1/D), which we have evaluated to the first order. This first order approximation to the desired effective nuclear charge has been applied to two-electron atoms with Z=2-20, and weakly bound systems such as H-. The errors for the two-electron atoms when compared with exact results were reduced from ˜0.2% for Z=2 to ˜0.002% for large Z. Although usual Hartree-Fock calculations for H- show this to be unstable, our results reduce the percent error of the Hartree-Fock energy from 7.6% to 1.86% and predicts the anion to be stable. For N-electron atoms (N=3-18, Z=3-28), using only the zeroth order approximation for the effective charge significantly reduces the error of Hartree-Fock calculations and recovers more than 80% of the correlation energy.

Large herbivores facilitate savanna tree establishment via diverse and indirect pathways.

PubMed

Goheen, Jacob R; Palmer, Todd M; Keesing, Felicia; Riginos, Corinna; Young, Truman P

2010-03-01

1. Savanna ecosystems are defined largely by tree-grass mixtures, and tree establishment is a key driver of community structure and ecosystem function in these systems. The factors controlling savanna tree establishment are understudied, but likely involve some combination of seed, microsite and predator/fire limitation. In African savannas, suppression and killing of adult trees by large mammals like elephants (Loxodonta africana Blumenbach, 1797) and giraffes (Giraffa camelopardalis Linnaeus, 1758) can maintain tree-grass co-dominance, although the impacts of even these conspicuous herbivores on tree establishment also are poorly understood. 2. We combined seed addition and predator exclusion experiments with a large-scale, long-term field manipulation of large herbivores to investigate the relative importance of seeds, microsites and predators in limiting establishment of a monodominant tree (Acacia drepanolobium Sjostedt) in a Kenyan savanna. 3. Both wild and domestic (i.e. cattle; Bos taurus Linnaeus, 1758) large herbivores facilitated tree establishment by suppressing abundances of rodents, the most important seed and seedling predators. However, this indirect, positive effect of wild herbivores was negated by wild herbivores' suppression of seed production. Cattle did not have this direct, negative impact; rather, they further assisted tree establishment by reducing cover of understorey grasses. Thus, the impacts of both groups of large herbivores on tree establishment were largely routed through other taxa, with a negligible net effect of wild herbivores and a positive net effect of cattle on tree establishment. 4. The distinction between the (positive) net effect of cattle and (neutral) net effect of wild herbivores is due to the inclusion of browsers and mixed feeders within the assemblage of wild herbivores. Browsing by wild herbivores limited seed production, which reduced tree recruitment; grazing by cattle was more pronounced than that by wild herbivores, and thus promoted germination and subsequent establishment of small trees. 5. Our study is the first to link seed fates to tree establishment in savanna ecosystems in experimentally-manipulated herbivore communities. Further, our results highlight how large herbivores can modify a suite of independent factors - seed production, competition with understorey species, and seed and seedling predation - to collectively drive tree establishment.

Organic field effect transistor with ultra high amplification

NASA Astrophysics Data System (ADS)

Torricelli, Fabrizio

2016-09-01

High-gain transistors are essential for the large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show organic transistors fabricated on plastic foils enabling unipolar amplifiers with ultra-gain. The proposed approach is general and opens up new opportunities for ultra-large signal amplification in organic circuits and sensors.

Imprint of non-linear effects on HI intensity mapping on large scales

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

Umeh, Obinna, E-mail: umeobinna@gmail.com

Intensity mapping of the HI brightness temperature provides a unique way of tracing large-scale structures of the Universe up to the largest possible scales. This is achieved by using a low angular resolution radio telescopes to detect emission line from cosmic neutral Hydrogen in the post-reionization Universe. We use general relativistic perturbation theory techniques to derive for the first time the full expression for the HI brightness temperature up to third order in perturbation theory without making any plane-parallel approximation. We use this result and the renormalization prescription for biased tracers to study the impact of nonlinear effects on themore » power spectrum of HI brightness temperature both in real and redshift space. We show how mode coupling at nonlinear order due to nonlinear bias parameters and redshift space distortion terms modulate the power spectrum on large scales. The large scale modulation may be understood to be due to the effective bias parameter and effective shot noise.« less

A closed form large deformation solution of plate bending with surface effects.

PubMed

Liu, Tianshu; Jagota, Anand; Hui, Chung-Yuen

2017-01-04

We study the effect of surface stress on the pure bending of a finite thickness plate under large deformation. The surface is assumed to be isotropic and its stress consists of a part that can be interpreted as a residual stress and a part that stiffens as the surface increases its area. Our results show that residual surface stress and surface stiffness can both increase the overall bending stiffness but through different mechanisms. For sufficiently large residual surface tension, we discover a new type of instability - the bending moment reaches a maximum at a critical curvature. Effects of surface stress on different stress components in the bulk of the plate are discussed and the possibility of self-bending due to asymmetry of the surface properties is also explored. The results of our calculations provide insights into surface stress effects in the large deformation regime and can be used as a test for implementation of finite element methods for surface elasticity.

Imprint of non-linear effects on HI intensity mapping on large scales

NASA Astrophysics Data System (ADS)

Umeh, Obinna

2017-06-01

Intensity mapping of the HI brightness temperature provides a unique way of tracing large-scale structures of the Universe up to the largest possible scales. This is achieved by using a low angular resolution radio telescopes to detect emission line from cosmic neutral Hydrogen in the post-reionization Universe. We use general relativistic perturbation theory techniques to derive for the first time the full expression for the HI brightness temperature up to third order in perturbation theory without making any plane-parallel approximation. We use this result and the renormalization prescription for biased tracers to study the impact of nonlinear effects on the power spectrum of HI brightness temperature both in real and redshift space. We show how mode coupling at nonlinear order due to nonlinear bias parameters and redshift space distortion terms modulate the power spectrum on large scales. The large scale modulation may be understood to be due to the effective bias parameter and effective shot noise.

Magnetic properties and magnetocaloric effects in HoPd intermetallic

NASA Astrophysics Data System (ADS)

Zhao-Jun, Mo; Jun, Shen; Xin-Qiang, Gao; Yao, Liu; Jian-Feng, Wu; Bao-Gen, Shen; Ji-Rong, Sun

2015-03-01

A large reversible magnetocaloric effect accompanied by a second order magnetic phase transition from PM to FM is observed in the HoPd compound. Under the magnetic field change of and the refrigerant capacity RC for the compound are evaluated to be 20 J/(kg · K) and 342 J/kg, respectively. In particular, large (11.3 J/(kg · K)) and RC (142 J/kg) are achieved under a low magnetic field change of 0-2 T with no thermal hysteresis and magnetic hysteresis loss. The large reversible magnetocaloric effect (both the large -ΔSM and the high RC) indicates that HoPd is a promising material for magnetic refrigeration at low temperature. Project supported by the National Natural Science Foundation of China (Grant Nos. 51322605, 11104337, 51271192, and 11274357) and the Knowledge Innovation Project of the Chinese Academy of Sciences.

The magnetic shear-current effect: Generation of large-scale magnetic fields by the small-scale dynamo

DOE PAGES

Squire, J.; Bhattacharjee, A.

2016-03-14

A novel large-scale dynamo mechanism, the magnetic shear-current effect, is discussed and explored. Here, the effect relies on the interaction of magnetic fluctuations with a mean shear flow, meaning the saturated state of the small-scale dynamo can drive a large-scale dynamo – in some sense the inverse of dynamo quenching. The dynamo is non-helical, with the mean fieldmore » $${\\it\\alpha}$$coefficient zero, and is caused by the interaction between an off-diagonal component of the turbulent resistivity and the stretching of the large-scale field by shear flow. Following up on previous numerical and analytic work, this paper presents further details of the numerical evidence for the effect, as well as an heuristic description of how magnetic fluctuations can interact with shear flow to produce the required electromotive force. The pressure response of the fluid is fundamental to this mechanism, which helps explain why the magnetic effect is stronger than its kinematic cousin, and the basic idea is related to the well-known lack of turbulent resistivity quenching by magnetic fluctuations. As well as being interesting for its applications to general high Reynolds number astrophysical turbulence, where strong small-scale magnetic fluctuations are expected to be prevalent, the magnetic shear-current effect is a likely candidate for large-scale dynamo in the unstratified regions of ionized accretion disks. Evidence for this is discussed, as well as future research directions and the challenges involved with understanding details of the effect in astrophysically relevant regimes.« less

Anomalously large isotope effect in the glass transition of water

DOE PAGES

Gainaru, Catalin; Agapov, Alexander L.; Fuentes-Landete, Violeta; ...

2014-11-24

Here we present the discovery of an unusually large isotope effect in the structural relaxation and the glass transition temperature T g of water. Dielectric relaxation spectroscopy of low-density as well as of vapor deposited amorphous water reveal T g differences of 10±2K between H 2O and D 2O, sharply contrasting with other hydrogen bonded liquids for which H/D exchange increases T g by typically less than 1K. We show that the large isotope effect and the unusual variation of relaxation times in water at low temperatures can be explained in terms of quantum effects. Thus, our findings shed newmore » light on water's peculiar low-temperature dynamics and the possible role of quantum effects in its structural relaxation, and possibly in dynamics of other low molecular weight liquids.« less

Feasibility of large-scale power plants based on thermoelectric effects

NASA Astrophysics Data System (ADS)

Liu, Liping

2014-12-01

Heat resources of small temperature difference are easily accessible, free and enormous on the Earth. Thermoelectric effects provide the technology for converting these heat resources directly into electricity. We present designs for electricity generators based on thermoelectric effects that utilize heat resources of small temperature difference, e.g., ocean water at different depths and geothermal resources, and conclude that large-scale power plants based on thermoelectric effects are feasible and economically competitive. The key observation is that the power factor of thermoelectric materials, unlike the figure of merit, can be improved by orders of magnitude upon laminating good conductors and good thermoelectric materials. The predicted large-scale power generators based on thermoelectric effects, if validated, will have the advantages of the scalability, renewability, and free supply of heat resources of small temperature difference on the Earth.

Nonpainful wide-area compression inhibits experimental pain.

PubMed

Honigman, Liat; Bar-Bachar, Ofrit; Yarnitsky, David; Sprecher, Elliot; Granovsky, Yelena

2016-09-01

Compression therapy, a well-recognized treatment for lymphoedema and venous disorders, pressurizes limbs and generates massive non-noxious afferent sensory barrages. The aim of this study was to study whether such afferent activity has an analgesic effect when applied on the lower limbs, hypothesizing that larger compression areas will induce stronger analgesic effects, and whether this effect correlates with conditioned pain modulation (CPM). Thirty young healthy subjects received painful heat and pressure stimuli (47°C for 30 seconds, forearm; 300 kPa for 15 seconds, wrist) before and during 3 compression protocols of either SMALL (up to ankles), MEDIUM (up to knees), or LARGE (up to hips) compression areas. Conditioned pain modulation (heat pain conditioned by noxious cold water) was tested before and after each compression protocol. The LARGE protocol induced more analgesia for heat than the SMALL protocol (P < 0.001). The analgesic effect interacted with gender (P = 0.015). The LARGE protocol was more efficient for females, whereas the MEDIUM protocol was more efficient for males. Pressure pain was reduced by all protocols (P < 0.001) with no differences between protocols and no gender effect. Conditioned pain modulation was more efficient than the compression-induced analgesia. For the LARGE protocol, precompression CPM efficiency positively correlated with compression-induced analgesia. Large body area compression exerts an area-dependent analgesic effect on experimental pain stimuli. The observed correlation with pain inhibition in response to robust non-noxious sensory stimulation may suggest that compression therapy shares similar mechanisms with inhibitory pain modulation assessed through CPM.

Model for large magnetoresistance effect in p–n junctions

NASA Astrophysics Data System (ADS)

Cao, Yang; Yang, Dezheng; Si, Mingsu; Shi, Huigang; Xue, Desheng

2018-06-01

We present a simple model based on the classic Shockley model to explain the magnetotransport in nonmagnetic p–n junctions. Under a magnetic field, the evaluation of the carrier to compensate Lorentz force establishes the necessary space-charge region distribution. The calculated current–voltage (I–V) characteristics under various magnetic fields demonstrate that the conventional nonmagnetic p–n junction can exhibit an extremely large magnetoresistance effect, which is even larger than that in magnetic materials. Because the large magnetoresistance effect that we discussed is based on the conventional p–n junction device, our model provides new insight into the development of semiconductor magnetoelectronics.

PERSISTENT CURRENT EFFECT IN 15-16 T NB3SN ACCELERATOR DIPOLES AND ITS CORRECTION

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

Kashikhin, V. V.; Zlobin, A. V.

2016-11-08

Nb3Sn magnets with operating fields of 15-16 T are considered for the LHC Energy Doubler and a future Very High Energy pp Collider. Due to large coil volume, high critical current density and large superconducting (SC) filament size the persistent current effect is very large in Nb3Sn dipoles al low fields. This paper presents the results of analysis of the persistent current effect in the 15 T Nb3Sn dipole demonstrator being developed at FNAL, and describes different possibilities of its correction including passive SC wires, iron shims and coil geometry.

Comparing two books and establishing probably efficacious treatment for low sexual desire.

PubMed

Balzer, Alexandra M; Mintz, Laurie B

2015-04-01

Using a sample of 45 women, this study compared the effectiveness of a previously studied (Mintz, Balzer, Zhao, & Bush, 2012) bibliotherapy intervention (Mintz, 2009), a similar self-help book (Hall, 2004), and a wait-list control (WLC) group. To examine intervention effectiveness, between and within group standardized effect sizes (interpreted with Cohen's, 1988 benchmarks .20 = small, .50 = medium, .80+ = large) and their confidence limits are used. In comparison to the WLC group, both interventions yielded large between-group posttest effect sizes on a measure of sexual desire. Additionally, large between-group posttest effect sizes were found for sexual satisfaction and lubrication among those reading the Mintz book. When examining within-group pretest to posttest effect sizes, medium to large effects were found for desire, lubrication, and orgasm for both books and for satisfaction and arousal for those reading the Mintz book. When directly comparing the books, all between-group posttest effect sizes were likely obtained by chance. It is concluded that both books are equally effective in terms of the outcome of desire, but whether or not there is differential efficacy in terms of other domains of sexual functioning is equivocal. Tentative evidence is provided for the longer term effectiveness of both books in enhancing desire. Arguing for applying criteria for empirically supported treatments to self-help, results are purported to establish the Mintz book as probably efficacious and to comprise a first step in this designation for the Hall book. (c) 2015 APA, all rights reserved).

A noncoherent model for microwave emissions and backscattering from the sea surface

NASA Technical Reports Server (NTRS)

Wu, S. T.; Fung, A. K.

1973-01-01

The two-scale (small irregularities superimposed upon large undulations) scattering theory proposed by Semyonov was extended and used to compute microwave apparent temperature and the backscattering cross section from ocean surfaces. The effect of the small irregularities upon the scattering characteristics of the large undulations is included by modifying the Fresnel reflection coefficients; whereas the effect of the large undulations upon those of the small irregularities is taken into account by averaging over the surface normals of the large undulations. The same set of surface parameters is employed for a given wind speed to predict both the scattering and the emission characteristics at both polarizations.

Elastic rubber strips to heal large wounds of the body wall.

PubMed

Petroianu, Andy

2013-12-01

Closure of large wounds is a difficult surgical challenge. This article reports on the effective closure of large surgical wounds using elastic rubber strips. One to 3 circular elastic rubber strips were sutured by applying moderate tension to the opposite edges of 30 large wounds in 28 patients. The strips were sutured in a successive "X" fashion by crossing one over the other. These rubber strips were replaced when they ruptured or after their tension had reduced because of the closure of the wounds. Complete closure of the wounds was achieved with no further need for any surgical procedure or device. One patient with laparostomy and colostomy presented with difficulty on adapting the colostomic bag, and the rubber strips were removed. The rubber strip had little effect on a large wound of the skull. In the late postoperative follow-up, 3 of the 15 closed laparostomies developed incisional hernias, and all these patients were subjected to hernioplasties with good results. The use of circular elastic rubber strips maintained at moderate tension is a simple, effective, and inexpensive surgical option for healing large wounds. It is readily available at any hospital and requires no extensive surgical experience.

Managing conflict between large carnivores and livestock.

PubMed

van Eeden, Lily M; Crowther, Mathew S; Dickman, Chris R; Macdonald, David W; Ripple, William J; Ritchie, Euan G; Newsome, Thomas M

2018-02-01

Large carnivores are persecuted globally because they threaten human industries and livelihoods. How this conflict is managed has consequences for the conservation of large carnivores and biodiversity more broadly. Mitigating human-predator conflict should be evidence-based and accommodate people's values while protecting carnivores. Despite much research into human and large-carnivore coexistence strategies, there have been few attempts to document the success of conflict-mitigation strategies on a global scale. We conducted a meta-analysis of global research on conflict mitigation related to large carnivores and humans. We focused on conflicts that arise from the threat large carnivores pose to livestock. We first used structured and unstructured searching to identify replicated studies that used before-after or control-impact design to measure change in livestock loss as a result of implementing a management intervention. We then extracted relevant data from these studies to calculate an overall effect size for each intervention type. Research effort and focus varied among continents and aligned with the histories and cultures that shaped livestock production and attitudes toward carnivores. Livestock guardian animals most effectively reduced livestock losses. Lethal control was the second most effective control, although its success varied the most, and guardian animals and lethal control did not differ significantly. Financial incentives have promoted tolerance of large carnivores in some settings and reduced retaliatory killings. We suggest coexistence strategies be location-specific, incorporate cultural values and environmental conditions, and be designed such that return on financial investment can be evaluated. Improved monitoring of mitigation measures is urgently required to promote effective evidence-based policy. © 2017 Society for Conservation Biology.

Team-Based Learning Enhances Performance in Introductory Biology

ERIC Educational Resources Information Center

Carmichael, Jeffrey

2009-01-01

Given the problems associated with the traditional lecture method, the constraints associated with large classes, and the effectiveness of active learning, continued development and testing of efficient student-centered learning approaches are needed. This study explores the effectiveness of team-based learning (TBL) in a large-enrollment…

Detecting and monitoring large-scale drought effects on forests: toward an integrated approach

Treesearch

Steve Norman; Frank H. Koch; William W. Hargrove

2016-01-01

Although drought is recognized as an important and overarching driver of ecosystem change, its occurrence and effects have been difficult to describe over large geographic areas (Hogg and others 2008, Panu and Sharma 2002).

Medical students perceive better group learning processes when large classes are made to seem small.

PubMed

Hommes, Juliette; Arah, Onyebuchi A; de Grave, Willem; Schuwirth, Lambert W T; Scherpbier, Albert J J A; Bos, Gerard M J

2014-01-01

Medical schools struggle with large classes, which might interfere with the effectiveness of learning within small groups due to students being unfamiliar to fellow students. The aim of this study was to assess the effects of making a large class seem small on the students' collaborative learning processes. A randomised controlled intervention study was undertaken to make a large class seem small, without the need to reduce the number of students enrolling in the medical programme. The class was divided into subsets: two small subsets (n=50) as the intervention groups; a control group (n=102) was mixed with the remaining students (the non-randomised group n∼100) to create one large subset. The undergraduate curriculum of the Maastricht Medical School, applying the Problem-Based Learning principles. In this learning context, students learn mainly in tutorial groups, composed randomly from a large class every 6-10 weeks. The formal group learning activities were organised within the subsets. Students from the intervention groups met frequently within the formal groups, in contrast to the students from the large subset who hardly enrolled with the same students in formal activities. Three outcome measures assessed students' group learning processes over time: learning within formally organised small groups, learning with other students in the informal context and perceptions of the intervention. Formal group learning processes were perceived more positive in the intervention groups from the second study year on, with a mean increase of β=0.48. Informal group learning activities occurred almost exclusively within the subsets as defined by the intervention from the first week involved in the medical curriculum (E-I indexes>-0.69). Interviews tapped mainly positive effects and negligible negative side effects of the intervention. Better group learning processes can be achieved in large medical schools by making large classes seem small.

Medical Students Perceive Better Group Learning Processes when Large Classes Are Made to Seem Small

PubMed Central

Hommes, Juliette; Arah, Onyebuchi A.; de Grave, Willem; Schuwirth, Lambert W. T.; Scherpbier, Albert J. J. A.; Bos, Gerard M. J.

2014-01-01

Objective Medical schools struggle with large classes, which might interfere with the effectiveness of learning within small groups due to students being unfamiliar to fellow students. The aim of this study was to assess the effects of making a large class seem small on the students' collaborative learning processes. Design A randomised controlled intervention study was undertaken to make a large class seem small, without the need to reduce the number of students enrolling in the medical programme. The class was divided into subsets: two small subsets (n = 50) as the intervention groups; a control group (n = 102) was mixed with the remaining students (the non-randomised group n∼100) to create one large subset. Setting The undergraduate curriculum of the Maastricht Medical School, applying the Problem-Based Learning principles. In this learning context, students learn mainly in tutorial groups, composed randomly from a large class every 6–10 weeks. Intervention The formal group learning activities were organised within the subsets. Students from the intervention groups met frequently within the formal groups, in contrast to the students from the large subset who hardly enrolled with the same students in formal activities. Main Outcome Measures Three outcome measures assessed students' group learning processes over time: learning within formally organised small groups, learning with other students in the informal context and perceptions of the intervention. Results Formal group learning processes were perceived more positive in the intervention groups from the second study year on, with a mean increase of β = 0.48. Informal group learning activities occurred almost exclusively within the subsets as defined by the intervention from the first week involved in the medical curriculum (E-I indexes>−0.69). Interviews tapped mainly positive effects and negligible negative side effects of the intervention. Conclusion Better group learning processes can be achieved in large medical schools by making large classes seem small. PMID:24736272

Interactive effects of fire and large herbivores on web-building spiders.

PubMed

Foster, C N; Barton, P S; Wood, J T; Lindenmayer, D B

2015-09-01

Altered disturbance regimes are a major driver of biodiversity loss worldwide. Maintaining or re-creating natural disturbance regimes is therefore the focus of many conservation programmes. A key challenge, however, is to understand how co-occurring disturbances interact to affect biodiversity. We experimentally tested for the interactive effects of prescribed fire and large macropod herbivores on the web-building spider assemblage of a eucalypt forest understorey and investigated the role of vegetation in mediating these effects using path analysis. Fire had strong negative effects on the density of web-building spiders, which were partly mediated by effects on vegetation structure, while negative effects of large herbivores on web density were not related to changes in vegetation. Fire amplified the effects of large herbivores on spiders, both via vegetation-mediated pathways and by increasing herbivore activity. The importance of vegetation-mediated pathways and fire-herbivore interactions differed for web density and richness and also differed between web types. Our results demonstrate that for some groups of web-building spiders, the effects of co-occurring disturbance drivers may be mostly additive, whereas for other groups, interactions between drivers can amplify disturbance effects. In our study system, the use of prescribed fire in the presence of high densities of herbivores could lead to reduced densities and altered composition of web-building spiders, with potential cascading effects through the arthropod food web. Our study highlights the importance of considering both the independent and interactive effects of disturbances, as well as the mechanisms driving their effects, in the management of disturbance regimes.

Symbolic Numerical Distance Effect Does Not Reflect the Difference between Numbers.

PubMed

Krajcsi, Attila; Kojouharova, Petia

2017-01-01

In a comparison task, the larger the distance between the two numbers to be compared, the better the performance-a phenomenon termed as the numerical distance effect. According to the dominant explanation, the distance effect is rooted in a noisy representation, and performance is proportional to the size of the overlap between the noisy representations of the two values. According to alternative explanations, the distance effect may be rooted in the association between the numbers and the small-large categories, and performance is better when the numbers show relatively high differences in their strength of association with the small-large properties. In everyday number use, the value of the numbers and the association between the numbers and the small-large categories strongly correlate; thus, the two explanations have the same predictions for the distance effect. To dissociate the two potential sources of the distance effect, in the present study, participants learned new artificial number digits only for the values between 1 and 3, and between 7 and 9, thus, leaving out the numbers between 4 and 6. It was found that the omitted number range (the distance between 3 and 7) was considered in the distance effect as 1, and not as 4, suggesting that the distance effect does not follow the values of the numbers predicted by the dominant explanation, but it follows the small-large property association predicted by the alternative explanations.

Assessing the effects of fire disturbances on ecosystems: A scientific agenda for research and management

USGS Publications Warehouse

Schmoldt, D.L.; Peterson, D.L.; Keane, R.E.; Lenihan, J.M.; McKenzie, D.; Weise, D.R.; Sandberg, D.V.

1999-01-01

A team of fire scientists and resource managers convened 17-19 April 1996 in Seattle, Washington, to assess the effects of fire disturbance on ecosystems. Objectives of this workshop were to develop scientific recommendations for future fire research and management activities. These recommendations included a series of numerically ranked scientific and managerial questions and responses focusing on (1) links among fire effects, fuels, and climate; (2) fire as a large-scale disturbance; (3) fire-effects modeling structures; and (4) managerial concerns, applications, and decision support. At the present time, understanding of fire effects and the ability to extrapolate fire-effects knowledge to large spatial scales are limited, because most data have been collected at small spatial scales for specific applications. Although we clearly need more large-scale fire-effects data, it will be more expedient to concentrate efforts on improving and linking existing models that simulate fire effects in a georeferenced format while integrating empirical data as they become available. A significant component of this effort should be improved communication between modelers and managers to develop modeling tools to use in a planning context. Another component of this modeling effort should improve our ability to predict the interactions of fire and potential climatic change at very large spatial scales. The priority issues and approaches described here provide a template for fire science and fire management programs in the next decade and beyond.

Issues in Estimating Program Effects and Studying Implementation in Large-Scale Educational Experiments: The Case of a Connected Classroom Technology Program

ERIC Educational Resources Information Center

Shin, Hye Sook

2009-01-01

Using data from a nationwide, large-scale experimental study of the effects of a connected classroom technology on student learning in algebra (Owens et al., 2004), this dissertation focuses on challenges that can arise in estimating treatment effects in educational field experiments when samples are highly heterogeneous in terms of various…

A hard-to-read font reduces the framing effect in a large sample.

PubMed

Korn, Christoph W; Ries, Juliane; Schalk, Lennart; Oganian, Yulia; Saalbach, Henrik

2018-04-01

How can apparent decision biases, such as the framing effect, be reduced? Intriguing findings within recent years indicate that foreign language settings reduce framing effects, which has been explained in terms of deeper cognitive processing. Because hard-to-read fonts have been argued to trigger deeper cognitive processing, so-called cognitive disfluency, we tested whether hard-to-read fonts reduce framing effects. We found no reliable evidence for an effect of hard-to-read fonts on four framing scenarios in a laboratory (final N = 158) and an online study (N = 271). However, in a preregistered online study with a rather large sample (N = 732), a hard-to-read font reduced the framing effect in the classic "Asian disease" scenario (in a one-sided test). This suggests that hard-read-fonts can modulate decision biases-albeit with rather small effect sizes. Overall, our findings stress the importance of large samples for the reliability and replicability of modulations of decision biases.

A robust and effective time-independent route to the calculation of Resonance Raman spectra of large molecules in condensed phases with the inclusion of Duschinsky, Herzberg-Teller, anharmonic, and environmental effects

PubMed Central

Egidi, Franco; Bloino, Julien; Cappelli, Chiara; Barone, Vincenzo

2015-01-01

We present an effective time-independent implementation to model vibrational resonance Raman (RR) spectra of medium-large molecular systems with the inclusion of Franck-Condon (FC) and Herzberg-Teller (HT) effects and a full account of the possible differences between the harmonic potential energy surfaces of the ground and resonant electronic states. Thanks to a number of algorithmic improvements and very effective parallelization, the full computations of fundamentals, overtones, and combination bands can be routinely performed for large systems possibly involving more than two electronic states. In order to improve the accuracy of the results, an effective inclusion of the leading anharmonic effects is also possible, together with environmental contributions under different solvation regimes. Reduced-dimensionality approaches can further enlarge the range of applications of this new tool. Applications to imidazole, pyrene, and chlorophyll a1 in solution are reported, as well as comparisons with available experimental data. PMID:26550003

Geological implications of impacts of large asteroids and comets on the earth

NASA Technical Reports Server (NTRS)

Silver, L. T. (Editor); Schultz, P. H. (Editor)

1982-01-01

The present conference discusses such topics as large object fluxes in near-earth space and the probabilities of terrestrial impacts, the geological record of impacts, dynamics modeling for large body impacts on continents and oceans, physical, chemical, and biological models of large impacts' atmospheric effects, dispersed impact ejecta and their signatures, general considerations concerning mass biological extinctions, the Cretaceous/Tertiary boundary event, geochemical signatures in the stratigraphic record, and other phanerozoic events. Attention is given to terrestrial impact rates for long- and short-period comets, estimates of crater size for large body impact, a first-order estimate of shock heating and vaporization in oceanic impacts, atmospheric effects in the first few minutes after an impact, a feasibility test for biogeographic extinction, and the planktonic and dinosaur extinctions.

Nonlinear modulation of the HI power spectrum on ultra-large scales. I

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

Umeh, Obinna; Maartens, Roy; Santos, Mario, E-mail: umeobinna@gmail.com, E-mail: roy.maartens@gmail.com, E-mail: mgrsantos@uwc.ac.za

2016-03-01

Intensity mapping of the neutral hydrogen brightness temperature promises to provide a three-dimensional view of the universe on very large scales. Nonlinear effects are typically thought to alter only the small-scale power, but we show how they may bias the extraction of cosmological information contained in the power spectrum on ultra-large scales. For linear perturbations to remain valid on large scales, we need to renormalize perturbations at higher order. In the case of intensity mapping, the second-order contribution to clustering from weak lensing dominates the nonlinear contribution at high redshift. Renormalization modifies the mean brightness temperature and therefore the evolutionmore » bias. It also introduces a term that mimics white noise. These effects may influence forecasting analysis on ultra-large scales.« less

Large object investigation by digital holography with effective spectrum multiplexing under single-exposure approach

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

Liu, Ning, E-mail: coolboy006@sohu.com; Zhang, Yingying; Xie, Jun

2014-10-13

We present a method to investigate large object by digital holography with effective spectrum multiplexing under single-exposure approach. This method splits the original reference beam and redirects one of its branches as a second object beam. Through the modified Mach-Zehnder interferometer, the two object beams can illuminate different parts of the large object and create a spectrum multiplexed hologram onto the focal plane array of the charge-coupled device/complementary metal oxide semiconductor camera. After correct spectrum extraction and image reconstruction, the large object can be fully observed within only one single snap-shot. The flexibility and great performance make our method amore » very attractive and promising technique for large object investigation under common 632.8 nm illumination.« less

An improved output feedback control of flexible large space structures

NASA Technical Reports Server (NTRS)

Lin, Y. H.; Lin, J. G.

1980-01-01

A special output feedback control design technique for flexible large space structures is proposed. It is shown that the technique will increase both the damping and frequency of selected modes for more effective control. It is also able to effect integrated control of elastic and rigid-body modes and, in particular, closed-loop system stability and robustness to modal truncation and parameter variation. The technique is seen as marking an improvement over previous work concerning large space structures output feedback control.

Testing the QCD string at large Nc from the thermodynamics of the hadronic phase

NASA Astrophysics Data System (ADS)

Cohen, Thomas D.

2007-02-01

It is generally believed that in the limit of a large number of colors (Nc) the description of confinement via flux tubes becomes valid and QCD can be modeled accurately via a hadronic string theory—at least for highly excited states. QCD at large Nc also has a well-defined deconfinement transition at a temperature Tc. In this talk it is shown how the thermodyanmics of the metastable hadronic phase of QCD (above Tc) at large NC can be related directly to properties of the effective QCD string. The key points in the derivation is the weakly interacting nature of hadrons at large Nc and the existence of a Hagedorn temperature TH for the effective string theory. From this it can be seen at large Nc and near TH, the energy density and pressure of the hadronic phase scale as E ˜ (TH - T)-(D⊥-6)/2 (for D⊥ < 6) and P ˜ (TH - T)-(D⊥-4)/2 (for D⊥ < 4) where D⊥ is the effective number of transverse dimensions of the string theory. This behavior for D⊥ < 6 is qualitatively different from typical models in statistical mechanics and if observed on the lattice would provide a direct test of the stringy nature of large Nc QCD. However since it can be seen that TH > Tc this behavior is of relevance only to the metastable phase. The prospect of using this result to extract D⊥ via lattice simulations of the metastable hadronic phase at moderately large Nc is discussed.

Considerations for Managing Large-Scale Clinical Trials.

ERIC Educational Resources Information Center

Tuttle, Waneta C.; And Others

1989-01-01

Research management strategies used effectively in a large-scale clinical trial to determine the health effects of exposure to Agent Orange in Vietnam are discussed, including pre-project planning, organization according to strategy, attention to scheduling, a team approach, emphasis on guest relations, cross-training of personnel, and preparing…

PERSPECTIVES ON LARGE-SCALE NATURAL RESOURCES SURVEYS WHEN CAUSE-EFFECT IS A POTENTIAL ISSUE

EPA Science Inventory

Our objective is to present a perspective on large-scale natural resource monitoring when cause-effect is a potential issue. We believe that the approach of designing a survey to meet traditional commodity production and resource state descriptive objectives is too restrictive an...

Effect of organic amendment and cultural practice on large patch occurrence and soil microbial community

USDA-ARS?s Scientific Manuscript database

Organic amendments may suppress soilborne pathogens by stimulating soil microbes. However, little information is available about the effects of organic amendments and cultural practices on suppressing large patch caused by Rhizoctonia solani Kühn on zoysiagrass (Zoysia japonica Steud.) associated wi...

Pipeline embolization device versus coiling for the treatment of large and giant unruptured intracranial aneurysms: a cost-effectiveness analysis.

PubMed

Wali, Arvin R; Park, Charlie C; Santiago-Dieppa, David R; Vaida, Florin; Murphy, James D; Khalessi, Alexander A

2017-06-01

OBJECTIVE Rupture of large or giant intracranial aneurysms leads to significant morbidity, mortality, and health care costs. Both coiling and the Pipeline embolization device (PED) have been shown to be safe and clinically effective for the treatment of unruptured large and giant intracranial aneurysms; however, the relative cost-to-outcome ratio is unknown. The authors present the first cost-effectiveness analysis to compare the economic impact of the PED compared with coiling or no treatment for the endovascular management of large or giant intracranial aneurysms. METHODS A Markov model was constructed to simulate a 60-year-old woman with a large or giant intracranial aneurysm considering a PED, endovascular coiling, or no treatment in terms of neurological outcome, angiographic outcome, retreatment rates, procedural and rehabilitation costs, and rupture rates. Transition probabilities were derived from prior literature reporting outcomes and costs of PED, coiling, and no treatment for the management of aneurysms. Cost-effectiveness was defined, with the incremental cost-effectiveness ratios (ICERs) defined as difference in costs divided by the difference in quality-adjusted life years (QALYs). The ICERs < $50,000/QALY gained were considered cost-effective. To study parameter uncertainty, 1-way, 2-way, and probabilistic sensitivity analyses were performed. RESULTS The base-case model demonstrated lifetime QALYs of 12.72 for patients in the PED cohort, 12.89 for the endovascular coiling cohort, and 9.7 for patients in the no-treatment cohort. Lifetime rehabilitation and treatment costs were $59,837.52 for PED; $79,025.42 for endovascular coiling; and $193,531.29 in the no-treatment cohort. Patients who did not undergo elective treatment were subject to increased rates of aneurysm rupture and high treatment and rehabilitation costs. One-way sensitivity analysis demonstrated that the model was most sensitive to assumptions about the costs and mortality risks for PED and coiling. Probabilistic sampling demonstrated that PED was the cost-effective strategy in 58.4% of iterations, coiling was the cost-effective strategy in 41.4% of iterations, and the no-treatment option was the cost-effective strategy in only 0.2% of iterations. CONCLUSIONS The authors' cost-effective model demonstrated that elective endovascular techniques such as PED and endovascular coiling are cost-effective strategies for improving health outcomes and lifetime quality of life measures in patients with large or giant unruptured intracranial aneurysm.

Instantons and Large N

NASA Astrophysics Data System (ADS)

Mariño, Marcos

2015-09-01

Preface; Part I. Instantons: 1. Instantons in quantum mechanics; 2. Unstable vacua in quantum field theory; 3. Large order behavior and Borel summability; 4. Non-perturbative aspects of Yang-Mills theories; 5. Instantons and fermions; Part II. Large N: 6. Sigma models at large N; 7. The 1=N expansion in QCD; 8. Matrix models and matrix quantum mechanics at large N; 9. Large N QCD in two dimensions; 10. Instantons at large N; Appendix A. Harmonic analysis on S3; Appendix B. Heat kernel and zeta functions; Appendix C. Effective action for large N sigma models; References; Author index; Subject index.

When the test of mediation is more powerful than the test of the total effect.

PubMed

O'Rourke, Holly P; MacKinnon, David P

2015-06-01

Although previous research has studied power in mediation models, the extent to which the inclusion of a mediator will increase power has not been investigated. To address this deficit, in a first study we compared the analytical power values of the mediated effect and the total effect in a single-mediator model, to identify the situations in which the inclusion of one mediator increased statistical power. The results from this first study indicated that including a mediator increased statistical power in small samples with large coefficients and in large samples with small coefficients, and when coefficients were nonzero and equal across models. Next, we identified conditions under which power was greater for the test of the total mediated effect than for the test of the total effect in the parallel two-mediator model. These results indicated that including two mediators increased power in small samples with large coefficients and in large samples with small coefficients, the same pattern of results that had been found in the first study. Finally, we assessed the analytical power for a sequential (three-path) two-mediator model and compared the power to detect the three-path mediated effect to the power to detect both the test of the total effect and the test of the mediated effect for the single-mediator model. The results indicated that the three-path mediated effect had more power than the mediated effect from the single-mediator model and the test of the total effect. Practical implications of these results for researchers are then discussed.

Ecological effects of large fires on US landscapes: benefit or catastrophe?

USGS Publications Warehouse

Keane, Robert E.; Agee, James K.; Fule, Peter; Keeley, Jon E.; Key, Carl H.; Kitchen, Stanley G.; Miller, Richard; Schulte, Lisa A.

2008-01-01

The perception is that today’s large fires are an ecological catastrophe because they burn vast areas with high intensities and severities. However, little is known of the ecological impacts of large fires on both historical and contemporary landscapes. The present paper presents a review of the current knowledge of the effects of large fires in the United States by important ecosystems written by regional experts. The ecosystems are (1) ponderosa pine–Douglas-fir, (2) sagebrush–grasslands, (3) piñon–juniper, (4) chaparral, (5) mixed-conifer, and (6) spruce–fir. This review found that large fires were common on most historical western US landscapes and they will continue to be common today with exceptions. Sagebrush ecosystems are currently experiencing larger, more severe, and more frequent large fires compared to historical conditions due to exotic cheatgrass invasions. Historical large fires in south-west ponderosa pine forest created a mixed severity mosaic dominated by non-lethal surface fires while today’s large fires are mostly high severity crown fires. While large fires play an important role in landscape ecology for most regions, their importance is much less in the dry piñon–juniper forests and sagebrush–grasslands. Fire management must address the role of large fires in maintaining the health of many US fire-dominated ecosystems.

Modeling thermo-optic effect in large mode area double cladding photonic crystal fibers

NASA Astrophysics Data System (ADS)

Coscelli, Enrico; Cucinotta, Annamaria

2014-02-01

The impact of thermally-induced refractive index changes on the single-mode (SM) properties of large mode area (LMA) photonic crystal fibers are thoroughly investigated by means of a full-vector modal solver with integrated thermal model. Three photonic crystal fiber designs are taken into account, namely the 19-cell core fiber, the large-pitch fiber (LPF) and the distributed modal filtering (DMF) fiber, to assess the effects of the interplay between thermal effects and the high-order mode (HOM) suppression mechanisms exploited in order to obtain effectively SM guiding. The results have shown significant differences in the way the SM regime is changed by the increase of heat load, providing useful hints for the design of LMA fibers for high power lasers.

Effect of a large-sized silicone sheet upon recovery of mastoid aeration after mastoidectomy.

PubMed

Kazama, Kyosuke; Takahashi, Haruo; Kaieda, Satoru; Iwanaga, Tetsu; Yamamoto-Fukuda, Tomomi; Yoshida, Haruo; Kumagami, Hidetaka; Takasaki, Kenji

2008-06-01

To evaluate the effect of our large-sized silicone sheet upon postoperative recovery of mastoid aeration in ears after surgery including mastoidectomy and soft-wall reconstruction (SWR). Retrospective chart review in a tertiary care center. Recovery of mastoid aeration was assessed by CT 4 to 12 months after surgery on 72 ears (69 patients), in which the silicone sheet covering from the eustachian tube (ET) to the mastoid was placed after SWR procedure with mastoidectomy were done for their chronic otitis media. Results were compared with those with a small silicone sheet. Recovery of mastoid aeration was significantly better in the large-silicone-sheet group than in the small-silicone-sheet group (chi(2) value = 11.7146, P = 0.0006). This preliminary study suggested that our large-sized silicone sheet may be effective for postoperative recovery of mastoid aeration even in ears operated with SWR procedure.

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

Szabó, R.; Sárneczky, K.; Szabó, Gy. M.

Unlike NASA’s original Kepler Discovery Mission, the renewed K2 Mission will target the plane of the Ecliptic, observing each field for approximately 75 days. This will bring new opportunities and challenges, in particular the presence of a large number of main-belt asteroids that will contaminate the photometry. The large pixel size makes K2 data susceptible to the effects of apparent minor planet encounters. Here, we investigate the effects of asteroid encounters on photometric precision using a subsample of the K2 engineering data taken in 2014 February. We show examples of asteroid contamination to facilitate their recognition and distinguish these eventsmore » from other error sources. We conclude that main-belt asteroids will have considerable effects on K2 photometry of a large number of photometric targets during the Mission that will have to be taken into account. These results will be readily applicable for future space photometric missions applying large-format CCDs, such as TESS and PLATO.« less

Nutraceuticals and Blood Pressure Control: Results from Clinical Trials and Meta-Analyses.

PubMed

Cicero, Arrigo F G; Colletti, Alessandro

2015-09-01

Beyond the well-known effects on blood pressure (BP) of the dietary approaches to stop hypertension (DASH) and the Mediterranean diets, a large number of studies has investigated the possible BP lowering effect of different dietary supplements and nutraceuticals, the most part of them being antioxidant agents with a high tolerability and safety profile. In particular relatively large body of evidence support the use of potassium, L-arginine, vitamin C, cocoa flavonoids, beetroot juice, coenzyme Q10, controlled-release melatonin, and aged garlic extract. However there is a need for data about the long-term safety of a large part of the above discussed products. Moreover further clinical research is advisable to identify between the available active nutraceuticals those with the best cost-effectiveness and risk-benefit ratio for a large use in general population with low-added cardiovascular risk related to uncomplicated hypertension.

Neighborhood diversity of large trees shows independent species patterns in a mixed dipterocarp forest in Sri Lanka.

PubMed

Punchi-Manage, Ruwan; Wiegand, Thorsten; Wiegand, Kerstin; Getzin, Stephan; Huth, Andreas; Gunatilleke, C V Savitri; Gunatilleke, I A U Nimal

2015-07-01

Interactions among neighboring individuals influence plant performance and should create spatial patterns in local community structure. In order to assess the role of large trees in generating spatial patterns in local species richness, we used the individual species-area relationship (ISAR) to evaluate the species richness of trees of different size classes (and dead trees) in circular neighborhoods with varying radius around large trees of different focal species. To reveal signals of species interactions, we compared the ISAR function of the individuals of focal species with that of randomly selected nearby locations. We expected that large trees should strongly affect the community structure of smaller trees in their neighborhood, but that these effects should fade away with increasing size class. Unexpectedly, we found that only few focal species showed signals of species interactions with trees of the different size classes and that this was less likely for less abundant focal species. However, the few and relatively weak departures from independence were consistent with expectations of the effect of competition for space and the dispersal syndrome on spatial patterns. A noisy signal of competition for space found for large trees built up gradually with increasing life stage; it was not yet present for large saplings but detectable for intermediates. Additionally, focal species with animal-dispersed seeds showed higher species richness in their neighborhood than those with gravity- and gyration-dispersed seeds. Our analysis across the entire ontogeny from recruits to large trees supports the hypothesis that stochastic effects dilute deterministic species interactions in highly diverse communities. Stochastic dilution is a consequence of the stochastic geometry of biodiversity in species-rich communities where the identities of the nearest neighbors of a given plant are largely unpredictable. While the outcome of local species interactions is governed for each plant by deterministic fitness and niche differences, the large variability of competitors causes also a large variability in the outcomes of interactions and does not allow for strong directed responses at the species level. Collectively, our results highlight the critical effect of the stochastic geometry of biodiversity in structuring local spatial patterns of tropical forest diversity.

Climate and litter quality differently modulate the effects of soil fauna on litter decomposition across biomes

PubMed Central

García-Palacios, Pablo; Maestre, Fernando T.; Kattge, Jens; Wall, Diana H.

2015-01-01

Climate and litter quality have been identified as major drivers of litter decomposition at large spatial scales. However, the role played by soil fauna remains largely unknown, despite its importance for litter fragmentation and microbial activity. We synthesized litterbag studies to quantify the effect sizes of soil fauna on litter decomposition rates at the global and biome scales, and to assess how climate, litter quality and soil fauna interact to determine such rates. Soil fauna consistently enhanced litter decomposition at both global and biome scales (average increment ~27%). However, climate and litter quality differently modulated the effects of soil fauna on decomposition rates between biomes, from climate-driven biomes to those where climate effects were mediated by changes in litter quality. Our results advocate for the inclusion of biome-specific soil fauna effects on litter decomposition as a mean to reduce the unexplained variation in large-scale decomposition models. PMID:23763716

Dilatancy and compaction effects on the submerged granular column collapse

NASA Astrophysics Data System (ADS)

Wang, Chun; Wang, Yongqi; Peng, Chong; Meng, Xiannan

2017-10-01

The effects of dilatancy on the collapse dynamics of granular materials in air or in a liquid are studied experimentally and numerically. Experiments show that dilatancy has a critical effect on the collapse of granular columns in the presence of an ambient fluid. Two regimes of the collapse, one being quick and the other being slow, are observed from the experiments and the underlying reasons are analyzed. A two-fluid smoothed particle hydrodynamics model, based on the granular-fluid mixture theory and the critical state theory, is employed to investigate the complex interactions between the solid particles and the ambient water. It is found that dilatancy, resulting in large effective stress and large frictional coefficient between solid particles, helps form the slow regime. Small permeability, representing large inter-phase drag force, also retards the collapse significantly. The proposed numerical model is capable of reproducing these effects qualitatively.

Memory bias for negative emotional words in recognition memory is driven by effects of category membership

PubMed Central

White, Corey N.; Kapucu, Aycan; Bruno, Davide; Rotello, Caren M.; Ratcliff, Roger

2014-01-01

Recognition memory studies often find that emotional items are more likely than neutral items to be labeled as studied. Previous work suggests this bias is driven by increased memory strength/familiarity for emotional items. We explored strength and bias interpretations of this effect with the conjecture that emotional stimuli might seem more familiar because they share features with studied items from the same category. Categorical effects were manipulated in a recognition task by presenting lists with a small, medium, or large proportion of emotional words. The liberal memory bias for emotional words was only observed when a medium or large proportion of categorized words were presented in the lists. Similar, though weaker, effects were observed with categorized words that were not emotional (animal names). These results suggest that liberal memory bias for emotional items may be largely driven by effects of category membership. PMID:24303902

Memory bias for negative emotional words in recognition memory is driven by effects of category membership.

PubMed

White, Corey N; Kapucu, Aycan; Bruno, Davide; Rotello, Caren M; Ratcliff, Roger

2014-01-01

Recognition memory studies often find that emotional items are more likely than neutral items to be labelled as studied. Previous work suggests this bias is driven by increased memory strength/familiarity for emotional items. We explored strength and bias interpretations of this effect with the conjecture that emotional stimuli might seem more familiar because they share features with studied items from the same category. Categorical effects were manipulated in a recognition task by presenting lists with a small, medium or large proportion of emotional words. The liberal memory bias for emotional words was only observed when a medium or large proportion of categorised words were presented in the lists. Similar, though weaker, effects were observed with categorised words that were not emotional (animal names). These results suggest that liberal memory bias for emotional items may be largely driven by effects of category membership.

Inducing a health-promoting change process within an organization: the effectiveness of a large-scale intervention on social capital, openness, and autonomous motivation toward health.

PubMed

van Scheppingen, Arjella R; de Vroome, Ernest M M; Ten Have, Kristin C J M; Bos, Ellen H; Zwetsloot, Gerard I J M; van Mechelen, W

2014-11-01

To examine the effectiveness of an organizational large-scale intervention applied to induce a health-promoting organizational change process. A quasi-experimental, "as-treated" design was used. Regression analyses on data of employees of a Dutch dairy company (n = 324) were used to examine the effects on bonding social capital, openness, and autonomous motivation toward health and on employees' lifestyle, health, vitality, and sustainable employability. Also, the sensitivity of the intervention components was examined. Intervention effects were found for bonding social capital, openness toward health, smoking, healthy eating, and sustainable employability. The effects were primarily attributable to the intervention's dialogue component. The change process initiated by the large-scale intervention contributed to a social climate in the workplace that promoted health and ownership toward health. The study confirms the relevance of collective change processes for health promotion.

Large scale obscuration and related climate effects open literature bibliography

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

Russell, N.A.; Geitgey, J.; Behl, Y.K.

1994-05-01

Large scale obscuration and related climate effects of nuclear detonations first became a matter of concern in connection with the so-called ``Nuclear Winter Controversy`` in the early 1980`s. Since then, the world has changed. Nevertheless, concern remains about the atmospheric effects of nuclear detonations, but the source of concern has shifted. Now it focuses less on global, and more on regional effects and their resulting impacts on the performance of electro-optical and other defense-related systems. This bibliography reflects the modified interest.

The Effect of Child Health Insurance Access on Schooling: Evidence from Public Insurance Expansions. NBER Working Paper No. 20178

ERIC Educational Resources Information Center

Cohodes, Sarah; Kleiner, Samuel; Lovenheim, Michael F.; Grossman, Daniel

2014-01-01

Public health insurance programs comprise a large share of federal and state government expenditure, and these programs are due to be expanded as part of the 2010 Affordable Care Act. Despite a large literature on the effects of these programs on health care utilization and health outcomes, little prior work has examined the long-term effects of…

Papers presented to the Conference on Large Body Impacts and Terrestrial Evolution: Geological, Climatological, and Biological Implications

NASA Technical Reports Server (NTRS)

1981-01-01

The effects of large impacts on the environment are discussed and include thermal effects, atmospheric effects, changes in ocean temperatures, and geomagnetic anomalies. Biological factors such as extinction and increases in mutation development were investigated. Geological anomalies studied include stratigraphic gaps, extinction of entire boundary layers from the geological record, and geochemical oddities. Evidence was examined for impact cratering throughout the world.

Performance of informative priors skeptical of large treatment effects in clinical trials: A simulation study.

PubMed

Pedroza, Claudia; Han, Weilu; Thanh Truong, Van Thi; Green, Charles; Tyson, Jon E

2018-01-01

One of the main advantages of Bayesian analyses of clinical trials is their ability to formally incorporate skepticism about large treatment effects through the use of informative priors. We conducted a simulation study to assess the performance of informative normal, Student- t, and beta distributions in estimating relative risk (RR) or odds ratio (OR) for binary outcomes. Simulation scenarios varied the prior standard deviation (SD; level of skepticism of large treatment effects), outcome rate in the control group, true treatment effect, and sample size. We compared the priors with regards to bias, mean squared error (MSE), and coverage of 95% credible intervals. Simulation results show that the prior SD influenced the posterior to a greater degree than the particular distributional form of the prior. For RR, priors with a 95% interval of 0.50-2.0 performed well in terms of bias, MSE, and coverage under most scenarios. For OR, priors with a wider 95% interval of 0.23-4.35 had good performance. We recommend the use of informative priors that exclude implausibly large treatment effects in analyses of clinical trials, particularly for major outcomes such as mortality.

Adaptive Fault-Tolerant Control of Uncertain Nonlinear Large-Scale Systems With Unknown Dead Zone.

PubMed

Chen, Mou; Tao, Gang

2016-08-01

In this paper, an adaptive neural fault-tolerant control scheme is proposed and analyzed for a class of uncertain nonlinear large-scale systems with unknown dead zone and external disturbances. To tackle the unknown nonlinear interaction functions in the large-scale system, the radial basis function neural network (RBFNN) is employed to approximate them. To further handle the unknown approximation errors and the effects of the unknown dead zone and external disturbances, integrated as the compounded disturbances, the corresponding disturbance observers are developed for their estimations. Based on the outputs of the RBFNN and the disturbance observer, the adaptive neural fault-tolerant control scheme is designed for uncertain nonlinear large-scale systems by using a decentralized backstepping technique. The closed-loop stability of the adaptive control system is rigorously proved via Lyapunov analysis and the satisfactory tracking performance is achieved under the integrated effects of unknown dead zone, actuator fault, and unknown external disturbances. Simulation results of a mass-spring-damper system are given to illustrate the effectiveness of the proposed adaptive neural fault-tolerant control scheme for uncertain nonlinear large-scale systems.

Corridors cause differential seed predation.

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

Orrock, John L.; Damschen, Ellen I.

2005-06-01

Orrock, John, L., and Ellen I. Damschen. 2005. Corridors cause differential seed predation. Ecol. Apps. 15(3):793-798. Abstract. Corridors that connect disjunct populations are heavily debated in conservation, largely because the effects of corridors have rarely been evaluated by replicated, large-scale studies. Using large-scale experimental landscapes, we found that, in addition to documented positive effects, corridors also have negative impacts on bird-dispersed plants by affecting seed predation, and that overall predation is a function of the seeds primary consumer (rodents or arthropods). Both large-seeded Prunus serotina and small-seeded Rubus allegheniensis experienced greater predation in connected patches. However, P. serotina experienced significantlymore » less seed predation compared to R. allegheniensis in unconnected patches, due to decreased impacts of rodent seed predators on this large-seeded species. Viewed in light of previous evidence that corridors have beneficial impacts by increasing pollination and seed dispersal, this work demonstrates that corridors may have both positive and negative effects for the same plant species at different life stages. Moreover, these effects may differentially affect plant species within the same community: seeds primarily consumed by rodents suffer less predation in unconnected patches. By shifting the impact of rodent and arthropod seed predators, corridors constructed for plant conservation could lead to shifts in the seed bank.« less

Effects of Acute and Chronic Flunitrazepam on Delay Discounting in Pigeons

PubMed Central

Eppolito, Amy K; France, Charles P; Gerak, Lisa R

2011-01-01

Delay to delivery of a reinforcer can decrease responding for that reinforcer and increase responding for smaller reinforcers that are available concurrently and delivered without delay; acute administration of drugs can alter responding for large, delayed reinforcers, although the impact of chronic treatment on delay discounting is not well understood. In this experiment, the effects of repeated administration of the benzodiazepine flunitrazepam were studied in 6 pigeons responding on one key to receive food that was delivered immediately and on a second key to receive a larger amount of food that was delivered following delays which increased across a single session. Pigeons responded predominantly for the large reinforcer when there were no delays and when delays were short; however, as delays increased, responding for the large reinforcer decreased. Acutely, flunitrazepam (0.32, 1.0 and 3.2 mg/kg) dose-dependently increased responding for the large reinforcer, shifting the discounting curve rightward and upward. Repeated administration of flunitrazepam (0.32, 1.0 and 3.2 mg/kg, each for six sessions, separated by one session during which vehicle was administered) did not markedly alter its effects on responding for the large reinforcer, indicating that the development of tolerance to this effect of flunitrazepam is modest under these conditions. PMID:21541119

On the apparent insignificance of the randomness of flexible joints on large space truss dynamics

NASA Technical Reports Server (NTRS)

Koch, R. M.; Klosner, J. M.

1993-01-01

Deployable periodic large space structures have been shown to exhibit high dynamic sensitivity to period-breaking imperfections and uncertainties. These can be brought on by manufacturing or assembly errors, structural imperfections, as well as nonlinear and/or nonconservative joint behavior. In addition, the necessity of precise pointing and position capability can require the consideration of these usually negligible and unknown parametric uncertainties and their effect on the overall dynamic response of large space structures. This work describes the use of a new design approach for the global dynamic solution of beam-like periodic space structures possessing parametric uncertainties. Specifically, the effect of random flexible joints on the free vibrations of simply-supported periodic large space trusses is considered. The formulation is a hybrid approach in terms of an extended Timoshenko beam continuum model, Monte Carlo simulation scheme, and first-order perturbation methods. The mean and mean-square response statistics for a variety of free random vibration problems are derived for various input random joint stiffness probability distributions. The results of this effort show that, although joint flexibility has a substantial effect on the modal dynamic response of periodic large space trusses, the effect of any reasonable uncertainty or randomness associated with these joint flexibilities is insignificant.

[Safety and effectiveness of large dose compound Sophora flavescens Ait injection in the treatment of advanced malignant tumors].

PubMed

Li, Dao-rui; Lin, Hong-sheng

2011-04-01

To evaluate the effectiveness and safety of large dose compound Sophora flavescens Ait injection in the treatment of advanced malignant tumors. A non-randomized case control trial was conducted. Ninety six patients with pathologically confirmed advanced non-small-cell lung cancer, gastric cancer and colorectal cancer were divided into traditional Chinese medicine group and chemotherapy group, 48 cases each. Patients of the traditional Chinese medicine group received treatment with large dose of compound Sophora flavescens Ait injection (20 ml/d), and 21 days as a cycle. Forty-seven patients of the traditional Chinese medicine group and 46 patients of the chemotherapy group completed their treatment, respectively. The clinical benefit rate (CBR) in the traditional Chinese medicine group was 83.0%, significantly higher than that in the chemotherapy group (69.6%) (P < 0.01). The Karnofsky performance status and weight improvement in the traditional Chinese medicine group was superior to that in the chemotherapy group (P < 0.05). Except the skin irritation in one patient in the traditional Chinese medicine group, there were no other clinical adverse effects related with the large dose compound Sophora flavescens Ait injection. Large dose compound Sophora flavescens Ait injection in the treatment of advanced malignant tumors is safe and effective. The recommended dose is 20 ml/d.

Arginine supplementation induces myoblast fusion via augmentation of nitric oxide production.

PubMed

Long, Jodi H D; Lira, Vitor A; Soltow, Quinlyn A; Betters, Jenna L; Sellman, Jeff E; Criswell, David S

2006-01-01

The semi-essential amino acid, L-arginine (L-Arg), is the substrate for endogenous synthesis of nitric oxide, a molecule that is involved in myoblast proliferation and fusion. Since L-Arg supply may limit nitric oxide synthase (NOS) activity in endothelial cells, we examined L-Arg supplementation in differentiating mouse myoblasts and tested the hypothesis that L-Arg exerts direct effects on myoblast fusion via augmentation of endogenous nitric oxide production. C(2)C(12) myoblasts in differentiation media received one of the following treatments for 120 h: 1 mM L-Arg, 0.1 mM N-nitro-L-arginine methyl ester (L-NAME), L-Arg + L-NAME, 10 mM L-Lysine, or no supplement (Control). Cultures were fixed and stained with hematoxylin and eosin for microphotometric image analysis of myotube density, nuclear density, and fusion index (% of total nuclei in myotubes). Endogenous production of nitric oxide during the treatment period peaked between 24 and 48 h. L-Arg amplified nitric oxide production between 0 and 24 h and increased myotube density, total nuclei number, and nuclear fusion index. These L-Arg effects were prevented by the NOS inhibitor, L-NAME. Further, L-Lysine, a competitive inhibitor of L-Arg uptake, repressed nitric oxide production and reduced myotube density and fusion index. In summary, L-Arg augments myotube formation and increases nitric oxide production in a process limited by cellular L-Arg uptake.

Prediction of large negative shaded-side spacecraft potentials

NASA Technical Reports Server (NTRS)

Prokopenko, S. M. L.; Laframboise, J. G.

1977-01-01

A calculation by Knott, for the floating potential of a spherically symmetric synchronous-altitude satellite in eclipse, was adapted to provide simple calculations of upper bounds on negative potentials which may be achieved by electrically isolated shaded surfaces on spacecraft in sunlight. Large (approximately 60 percent) increases in predicted negative shaded-side potentials are obtained. To investigate effective potential barrier or angular momentum selection effects due to the presence of less negative sunlit-side or adjacent surface potentials, these expressions were replaced by the ion random current, which is a lower bound for convex surfaces when such effects become very severe. Further large increases in predicted negative potentials were obtained, amounting to a doubling in some cases.

Large negative differential resistance in graphene nanoribbon superlattices

NASA Astrophysics Data System (ADS)

Tseng, P.; Chen, C. H.; Hsu, S. A.; Hsueh, W. J.

2018-05-01

A graphene nanoribbon superlattice with a large negative differential resistance (NDR) is proposed. Our results show that the peak-to-valley ratio (PVR) of the graphene superlattices can reach 21 at room temperature with bias voltages between 90-220 mV, which is quite large compared with the one of traditional graphene-based devices. It is found that the NDR is strongly influenced by the thicknesses of the potential barrier. Therefore, the NDR effect can be optimized by designing a proper barrier thickness. The large NDR effect can be attributed to the splitting of the gap in transmission spectrum (segment of Wannier-Stark ladder) with larger thicknesses of barrier when the applied voltage increases.

Nonpainful wide-area compression inhibits experimental pain

PubMed Central

Honigman, Liat; Bar-Bachar, Ofrit; Yarnitsky, David; Sprecher, Elliot; Granovsky, Yelena

2016-01-01

Abstract Compression therapy, a well-recognized treatment for lymphoedema and venous disorders, pressurizes limbs and generates massive non-noxious afferent sensory barrages. The aim of this study was to study whether such afferent activity has an analgesic effect when applied on the lower limbs, hypothesizing that larger compression areas will induce stronger analgesic effects, and whether this effect correlates with conditioned pain modulation (CPM). Thirty young healthy subjects received painful heat and pressure stimuli (47°C for 30 seconds, forearm; 300 kPa for 15 seconds, wrist) before and during 3 compression protocols of either SMALL (up to ankles), MEDIUM (up to knees), or LARGE (up to hips) compression areas. Conditioned pain modulation (heat pain conditioned by noxious cold water) was tested before and after each compression protocol. The LARGE protocol induced more analgesia for heat than the SMALL protocol (P < 0.001). The analgesic effect interacted with gender (P = 0.015). The LARGE protocol was more efficient for females, whereas the MEDIUM protocol was more efficient for males. Pressure pain was reduced by all protocols (P < 0.001) with no differences between protocols and no gender effect. Conditioned pain modulation was more efficient than the compression-induced analgesia. For the LARGE protocol, precompression CPM efficiency positively correlated with compression-induced analgesia. Large body area compression exerts an area-dependent analgesic effect on experimental pain stimuli. The observed correlation with pain inhibition in response to robust non-noxious sensory stimulation may suggest that compression therapy shares similar mechanisms with inhibitory pain modulation assessed through CPM. PMID:27152691

Analytic prediction of baryonic effects from the EFT of large scale structures

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

Lewandowski, Matthew; Perko, Ashley; Senatore, Leonardo, E-mail: mattlew@stanford.edu, E-mail: perko@stanford.edu, E-mail: senatore@stanford.edu

2015-05-01

The large scale structures of the universe will likely be the next leading source of cosmological information. It is therefore crucial to understand their behavior. The Effective Field Theory of Large Scale Structures provides a consistent way to perturbatively predict the clustering of dark matter at large distances. The fact that baryons move distances comparable to dark matter allows us to infer that baryons at large distances can be described in a similar formalism: the backreaction of short-distance non-linearities and of star-formation physics at long distances can be encapsulated in an effective stress tensor, characterized by a few parameters. Themore » functional form of baryonic effects can therefore be predicted. In the power spectrum the leading contribution goes as ∝ k{sup 2} P(k), with P(k) being the linear power spectrum and with the numerical prefactor depending on the details of the star-formation physics. We also perform the resummation of the contribution of the long-wavelength displacements, allowing us to consistently predict the effect of the relative motion of baryons and dark matter. We compare our predictions with simulations that contain several implementations of baryonic physics, finding percent agreement up to relatively high wavenumbers such as k ≅ 0.3 hMpc{sup −1} or k ≅ 0.6 hMpc{sup −1}, depending on the order of the calculation. Our results open a novel way to understand baryonic effects analytically, as well as to interface with simulations.« less

Effects of large scale deforestation on precipitation in the monsoon regions: Remote versus local effects

NASA Astrophysics Data System (ADS)

Bala, G.; N, D.; Modak, A.

2015-12-01

In this study, we investigate the bio-geophysical effects of large-scale deforestation on monsoon regions using idealized deforestation simulations. The simulations are performed using the NCAR CAM5 atmospheric model coupled to a mixed layer ocean model. The four deforestation experiments are named Global, Boreal, Temperate and Tropical, respectively. In these deforestation experiments, trees are replaced by grasses around the globe, between 20oS and 20oN, between 20oN and 50oN and poleward of 50oN, respectively. We find that the remote forcing from large-scale deforestation in the Temperate and Boreal cases shift the Inter-tropical Convergence Zone (ITCZ) southward. This results in a significant decrease in precipitation in the Northern Hemisphere monsoon regions (East Asia, North America, North Africa, South Asia) and moderate precipitation increases in the Southern Hemisphere monsoon regions (South Africa, South America and Australia). The magnitude of the monsoonal precipitation changes depend on the location of deforestation with remote effects showing a larger influence than local effects. The South Asian Monsoon region is affected the most with 18% decline in precipitation over India in the Global deforestation case. Our results indicate that any comprehensive assessment of afforestation/reforestation as climate change mitigation strategies should carefully evaluate the remote effects on monsoonal precipitation besides the large local impacts on temperatures and carbon sequestration benefits. Our results also demonstrate the linkages between any large scale forcing that causes large warming/cooling in the high latitudes and rainfall changes in tropical monsoonal regions via ITCZ shifts. Figure Caption: Changes in annual mean precipitation (mm/day) between the deforestation experiments and the control simulation. Hatched areas are regions where changes are statistically significant at the 95% confidence level. Shading in line plots represents the ±1 standard deviation estimated from the control simulation. Comparison of (b) with (d) clearly indicates that the remote effect has a larger influence on tropical precipitation than local effect.The location of the precipitation centroid in the ITCZ region in the CTL case and the shifts in the experiments are shown above the panels.

The rapid evolution of X-linked male-biased gene expression and the large-X effect in Drosophila yakuba, D. santomea, and their hybrids.

PubMed

Llopart, Ana

2012-12-01

The X chromosome has a large effect on hybrid dysfunction, particularly on hybrid male sterility. Although the evidence for this so-called large-X effect is clear, its molecular causes are not yet fully understood. One possibility is that, under certain conditions, evolution proceeds faster in X-linked than in autosomal loci (i.e., faster-X effect) due to both natural selection and their hemizygosity in males, an effect that is expected to be greatest in genes with male-biased expression. Here, I study genome-wide variation in transcript abundance between Drosophila yakuba and D. santomea, within these species and in their hybrid males to evaluate both the faster-X and large-X effects at the level of expression. I find that in X-linked male-biased genes (MBGs) expression evolves faster than in their autosomal counterparts, an effect that is accompanied by a unique reduction in expression polymorphism. This suggests that Darwinian selection is driving expression differences between species, likely enhanced by the hemizygosity of the X chromosome in males. Despite the recent split of the two sister species under study, abundant changes in both cis- and trans-regulatory elements underlie expression divergence in the majority of the genes analyzed, with significant differences in allelic ratios of transcript abundance between the two reciprocal F(1) hybrid males. Cis-trans coevolution at molecular level, evolved shortly after populations become isolated, may therefore contribute to explain the breakdown of the regulation of gene expression in hybrid males. Additionally, the X chromosome plays a large role in this hybrid male misexpression, which affects not only MBG but also, to a lesser degree, nonsex-biased genes. Interestingly, hybrid male misexpression is concentrated mostly in autosomal genes, likely facilitated by the rapid evolution of sex-linked trans-acting factors. I suggest that the faster evolution of X-linked MBGs, at both protein and expression levels, contributes to explain the large effect of the X chromosome on hybrid male sterility, likely mediating widespread autosomal misexpression through the preferential recognition of cis-regulatory elements by conspecific trans-acting factors (i.e., cis-trans conspecific recognition).

Lifestyle and Metformin Treatment Favorably Influence Lipoprotein Subfraction Distribution in the Diabetes Prevention Program

PubMed Central

Temprosa, M.; Otvos, J.; Brunzell, J.; Marcovina, S.; Mather, K.; Arakaki, R.; Watson, K.; Horton, E.; Barrett-Connor, E.

2013-01-01

Context: Although intensive lifestyle change (ILS) and metformin reduce diabetes incidence in subjects with impaired glucose tolerance (IGT), their effects on lipoprotein subfractions have not been studied. Objective: The objective of the study was to characterize the effects of ILS and metformin vs placebo interventions on lipoprotein subfractions in the Diabetes Prevention Program. Design: This was a randomized clinical trial, testing the effects of ILS, metformin, and placebo on diabetes development in subjects with IGT. Participants: Selected individuals with IGT randomized in the Diabetes Prevention Program participated in the study. Interventions: Interventions included randomization to metformin 850 mg or placebo twice daily or ILS aimed at a 7% weight loss using a low-fat diet with increased physical activity. Main Outcome Measures: Lipoprotein subfraction size, density, and concentration measured by magnetic resonance and density gradient ultracentrifugation at baseline and 1 year were measured. Results: ILS decreased large and buoyant very low-density lipoprotein, small and dense low-density lipoprotein (LDL), and small high-density lipoprotein (HDL) and raised large HDL. Metformin modestly reduced small and dense LDL and raised small and large HDL. Change in insulin resistance largely accounted for the intervention-associated decreases in large very low-density lipoprotein, whereas changes in body mass index (BMI) and adiponectin were strongly associated with changes in LDL. Baseline and a change in adiponectin were related to change in large HDL, and BMI change associated with small HDL change. The effect of metformin to increase small HDL was independent of adiponectin, BMI, and insulin resistance. Conclusion: ILS and metformin treatment have favorable effects on lipoprotein subfractions that are primarily mediated by intervention-related changes in insulin resistance, BMI, and adiponectin. Interventions that slow the development of diabetes may also retard the progression of atherosclerosis. PMID:23979954

Long-term effects of bottom trawling on large sponges in the Gulf of Alaska

NASA Astrophysics Data System (ADS)

Malecha, Patrick; Heifetz, Jonathan

2017-11-01

Manipulative studies that characterize short-term effects of bottom trawls on seafloor habitats are numerous, but studies that examine long-term effects are rare. The long-term (13 years) effects of a single bottom trawl on large (>20 cm) erect sponges were investigated by revisiting the site of prior experimental trawling studies. In prior studies, large sponges were assessed immediately after trawling and 1 yr post-trawling. Thirteen years post-trawling, the average density of large sponges was 31.7% lower (range 1.5-53.0%) and the incidence of sponge damage (torn, necrotic, missing tissue, prone) was 58.8% higher within strip transects in trawled versus untrawled reference areas. For all sponge species combined, the mean density of large sponges was 3.19 individuals 100 m-2 in trawled areas and 4.67 individuals 100 m-2 in reference areas. The most abundant sponge species in both trawled and reference areas was Rhabdocalyptus dawsoni. Mean density of this species differed greatly between trawled (1.57 individuals 100 m-2) and reference areas (2.91 individuals 100 m-2). Thirteen years after trawling, the mean percentage of damaged sponges on strip transects was 15.3% in trawled areas and 6.3% in reference areas. The rate of damage in trawled areas was less than that observed both immediately after trawling and 1 year later. The persistence of damage (lower sponge densities and higher rates of injury in trawled areas) and the potential resultant changes to benthic communities where deepwater habitat-forming biota, such as large erect sponges, are present provide rationale for cautious management of the long term effects of bottom trawling.

Projection Effects of Large-scale Structures on Weak-lensing Peak Abundances

NASA Astrophysics Data System (ADS)

Yuan, Shuo; Liu, Xiangkun; Pan, Chuzhong; Wang, Qiao; Fan, Zuhui

2018-04-01

High peaks in weak lensing (WL) maps originate dominantly from the lensing effects of single massive halos. Their abundance is therefore closely related to the halo mass function and thus a powerful cosmological probe. However, besides individual massive halos, large-scale structures (LSS) along lines of sight also contribute to the peak signals. In this paper, with ray-tracing simulations, we investigate the LSS projection effects. We show that for current surveys with a large shape noise, the stochastic LSS effects are subdominant. For future WL surveys with source galaxies having a median redshift z med ∼ 1 or higher, however, they are significant. For the cosmological constraints derived from observed WL high-peak counts, severe biases can occur if the LSS effects are not taken into account properly. We extend the model of Fan et al. by incorporating the LSS projection effects into the theoretical considerations. By comparing with simulation results, we demonstrate the good performance of the improved model and its applicability in cosmological studies.

A Discretization Algorithm for Meteorological Data and its Parallelization Based on Hadoop

NASA Astrophysics Data System (ADS)

Liu, Chao; Jin, Wen; Yu, Yuting; Qiu, Taorong; Bai, Xiaoming; Zou, Shuilong

2017-10-01

In view of the large amount of meteorological observation data, the property is more and the attribute values are continuous values, the correlation between the elements is the need for the application of meteorological data, this paper is devoted to solving the problem of how to better discretize large meteorological data to more effectively dig out the hidden knowledge in meteorological data and research on the improvement of discretization algorithm for large scale data, in order to achieve data in the large meteorological data discretization for the follow-up to better provide knowledge to provide protection, a discretization algorithm based on information entropy and inconsistency of meteorological attributes is proposed and the algorithm is parallelized under Hadoop platform. Finally, the comparison test validates the effectiveness of the proposed algorithm for discretization in the area of meteorological large data.

Effects of geometric design features on truck crashes on limited-access highways.

DOT National Transportation Integrated Search

2012-06-01

Freight can be transported between most points in the country quite efficiently using trucks. However, involvement of large : trucks in crashes can cause much damage and serious injuries, due to their large sizes and heavy weights. Large truck : cras...

The Effectiveness of Lecture-Integrated, Web-Supported Case Studies in Large Group Teaching

ERIC Educational Resources Information Center

Azzawi, May; Dawson, Maureen M.

2007-01-01

The effectiveness of lecture-integrated and web-supported case studies in supporting a large and academically diverse group of undergraduate students was evaluated in the present study. Case studies and resource (web)-based learning were incorporated as two complementary interactive learning strategies into the traditional curriculum. A truncated…

Effect of Integrating Hydrologic Scaling Concepts on Students Learning and Decision Making Experiences

ERIC Educational Resources Information Center

Najm, Majdi R. Abou; Mohtar, Rabi H.; Cherkauer, Keith A.; French, Brian F.

2010-01-01

Proper understanding of scaling and large-scale hydrologic processes is often not explicitly incorporated in the teaching curriculum. This makes it difficult for students to connect the effect of small scale processes and properties (like soil texture and structure, aggregation, shrinkage, and cracking) on large scale hydrologic responses (like…

Unionism and Productivity in West Virginia Coal Mining.

ERIC Educational Resources Information Center

Boal, William M.

1990-01-01

This study presents econometric estimates of the effects of unionism on productivity in 83 West Virginia coal mines in the early 1920s. Results show that unionism significantly reduced productivity at small mines but not at large mines. The author ascribes this effect to systematic differences between small and large operations in the quality of…

Child Demographics Associated with Outcomes in a Community-Based Pivotal Response Training Program

ERIC Educational Resources Information Center

Baker-Ericzen, Mary J.; Stahmer, Aubyn C.; Burns, Amelia

2007-01-01

Although knowledge about the efficacy of treatments such as pivotal response training (PRT) for children with autism is increasing, studies of large-scale effectiveness for and transportability to diverse community populations are needed. The current study provides a large-scale preliminary assessment of (a) the effectiveness of a community-based…

The Developing Brain: A Largely Overlooked Health Endpoint in Risk Assessments for Synthetic Chemical Substances

ERIC Educational Resources Information Center

McElgunn, Barbara

2010-01-01

A large body of experimental animal research on the neurotoxic effects of certain environmental chemicals provides evidence of a cascade of neurobehavioural effects including learning deficits, hyperactivity, anxiety, depression, lack of motivation, increased aggressiveness, altered maternal care and bonding, and an over-reaction to small…

Case Study Effectiveness in a Team-Teaching and General-Education Environment

ERIC Educational Resources Information Center

Olorunnisola, Anthony A.; Ramasubramanian, Srividya; Russill, Chris; Dumas, Josephine

2003-01-01

This paper examines the effectiveness of the case study method in a team-teaching environment designed to augment a large capstone communications course that satisfies general education requirements. Results from a survey revealed that the use of case study enhanced the otherwise missing connection between the large lecture and the recitation…

Effects of 1997 debris floods in two Klamath Mountain streams: A large woody debris mass-balance approach

Treesearch

Zackary J. Mondry; Susan J. Hilton

2000-01-01

Large landslides and debris flows in January 1997 produced contrasting downstream debris flood effects in two adjacent Northern California Klamath Mountain streams. Valley morphology and riparian forests were examined on post-flood 1:3000 air photos along two approximately 8 km survey reaches.

Production and efficiency of large wildland fire suppression effort: A stochastic frontier analysis

Treesearch

Hari Katuwal; Dave Calkin; Michael S. Hand

2016-01-01

This study examines the production and efficiency of wildland fire suppression effort. We estimate the effectiveness of suppression resource inputs to produce controlled fire lines that contain large wildland fires using stochastic frontier analysis. Determinants of inefficiency are identified and the effects of these determinants on the daily production of...

Parallel and serial computing tools for testing single-locus and epistatic SNP effects of quantitative traits in genome-wide association studies

PubMed Central

Ma, Li; Runesha, H Birali; Dvorkin, Daniel; Garbe, John R; Da, Yang

2008-01-01

Background Genome-wide association studies (GWAS) using single nucleotide polymorphism (SNP) markers provide opportunities to detect epistatic SNPs associated with quantitative traits and to detect the exact mode of an epistasis effect. Computational difficulty is the main bottleneck for epistasis testing in large scale GWAS. Results The EPISNPmpi and EPISNP computer programs were developed for testing single-locus and epistatic SNP effects on quantitative traits in GWAS, including tests of three single-locus effects for each SNP (SNP genotypic effect, additive and dominance effects) and five epistasis effects for each pair of SNPs (two-locus interaction, additive × additive, additive × dominance, dominance × additive, and dominance × dominance) based on the extended Kempthorne model. EPISNPmpi is the parallel computing program for epistasis testing in large scale GWAS and achieved excellent scalability for large scale analysis and portability for various parallel computing platforms. EPISNP is the serial computing program based on the EPISNPmpi code for epistasis testing in small scale GWAS using commonly available operating systems and computer hardware. Three serial computing utility programs were developed for graphical viewing of test results and epistasis networks, and for estimating CPU time and disk space requirements. Conclusion The EPISNPmpi parallel computing program provides an effective computing tool for epistasis testing in large scale GWAS, and the epiSNP serial computing programs are convenient tools for epistasis analysis in small scale GWAS using commonly available computer hardware. PMID:18644146

Risk of large-scale evacuation based on the effectiveness of rescue strategies under different crowd densities.

PubMed

Wang, Jinghong; Lo, Siuming; Wang, Qingsong; Sun, Jinhua; Mu, Honglin

2013-08-01

Crowd density is a key factor that influences the moving characteristics of a large group of people during a large-scale evacuation. In this article, the macro features of crowd flow and subsequent rescue strategies were considered, and a series of characteristic crowd densities that affect large-scale people movement, as well as the maximum bearing density when the crowd is extremely congested, were analyzed. On the basis of characteristic crowd densities, the queuing theory was applied to simulate crowd movement. Accordingly, the moving characteristics of the crowd and the effects of typical crowd density-which is viewed as the representation of the crowd's arrival intensity in front of the evacuation passageways-on rescue strategies was studied. Furthermore, a "risk axle of crowd density" is proposed to determine the efficiency of rescue strategies in a large-scale evacuation, i.e., whether the rescue strategies are able to effectively maintain or improve evacuation efficiency. Finally, through some rational hypotheses for the value of evacuation risk, a three-dimensional distribution of the evacuation risk is established to illustrate the risk axle of crowd density. This work aims to make some macro, but original, analysis on the risk of large-scale crowd evacuation from the perspective of the efficiency of rescue strategies. © 2012 Society for Risk Analysis.

Effects of chitosan combined with nisin treatment on storage quality of large yellow croaker (Pseudosciaena crocea).

PubMed

Hui, Guohua; Liu, Wei; Feng, Hailin; Li, Jian; Gao, Yuanyuan

2016-07-15

Effects of chitosan combined with different concentrations of nisin on quality enhancement of large yellow croaker (Pseudosciaena crocea) stored at 4 °C were evaluated for 8 days. Changes in sensory score and volatile spoilage products, total viable counts (TVC), and physiochemical indexes including weight loss, colour, pH, total volatile basic nitrogen (TVB-N), and K-value were examined. Results demonstrated that nisin-treated samples presented better quality preservation effects than chitosan alone. 1% chitosan combined with 0.6% nisin presented optimal quality enhancement effects, such as moisture loss control, volatile spoilage inhibition, TVB-N reduction, TVC growth control, and colour and sensory acceptability maintenance. Therefore, chitosan combined with nisin is promising in large yellow croaker shelf life extension. Copyright © 2016 Elsevier Ltd. All rights reserved.

Internal migration effectiveness and income effectiveness in the most populous cities in the United States.

PubMed

Ambinakudige, Shrinidhi; Parisi, Domenico

2010-01-01

In this study, migration data compiled by the Internal Revenue Serve (IRS) and the US Census Bureau for 2006-07 were used to analyse internal migration patterns using migration and income effectiveness for the counties containing the 25 most populous cities in the United States. The results indicated that both large metropolitan and rural counties have lost population and income due to migration. Small metropolitan and non-metropolitan counties closer to cities gained population and income. Counties in South Florida attracted a large number of higher-income migrants from the largest cities in the US. In the last 13 years, New York, Los Angeles and Chicago, the three most populous cities in the US, had negative migration effectiveness. Suburban areas and second-tier cities continued to attract people from large metropolitan areas.

Search for large extra dimensions in dielectron and diphoton production.

PubMed

Abbott, B; Abolins, M; Abramov, V; Acharya, B S; Adams, D L; Adams, M; Alves, G A; Amos, N; Anderson, E W; Baarmand, M M; Babintsev, V V; Babukhadia, L; Baden, A; Baldin, B; Balm, P W; Banerjee, S; Bantly, J; Barberis, E; Baringer, P; Bartlett, J F; Bassler, U; Bean, A; Begel, M; Belyaev, A; Beri, S B; Bernardi, G; Bertram, I; Besson, A; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Bhattacharjee, M; Blazey, G; Blessing, S; Boehnlein, A; Bojko, N I; Borcherding, F; Brandt, A; Breedon, R; Briskin, G; Brock, R; Brooijmans, G; Bross, A; Buchholz, D; Buehler, M; Buescher, V; Burtovoi, V S; Butler, J M; Canelli, F; Carvalho, W; Casey, D; Casilum, Z; Castilla-Valdez, H; Chakraborty, D; Chan, K M; Chekulaev, S V; Cho, D K; Choi, S; Chopra, S; Christenson, J H; Chung, M; Claes, D; Clark, A R; Cochran, J; Coney, L; Connolly, B; Cooper, W E; Coppage, D; Cummings, M A; Cutts, D; Dahl, O I; Davis, G A; Davis, K; De, K; Del Signore, K; Demarteau, M; Demina, R; Demine, P; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Di Loreto, G; Doulas, S; Draper, P; Ducros, Y; Dudko, L V; Duensing, S; Dugad, S R; Dyshkant, A; Edmunds, D; Ellison, J; Elvira, V D; Engelmann, R; Eno, S; Eppley, G; Ermolov, P; Eroshin, O V; Estrada, J; Evans, H; Evdokimov, V N; Fahland, T; Feher, S; Fein, D; Ferbel, T; Fisk, H E; Fisyak, Y; Flattum, E; Fleuret, F; Fortner, M; Frame, K C; Fuess, S; Gallas, E; Galyaev, A N; Gartung, P; Gavrilov, V; Genik, R J; Genser, K; Gerber, C E; Gershtein, Y; Gibbard, B; Gilmartin, R; Ginther, G; Gómez, B; Gómez, G; Goncharov, P I; González Solís, J L; Gordon, H; Goss, L T; Gounder, K; Goussiou, A; Graf, N; Graham, G; Grannis, P D; Green, J A; Greenlee, H; Grinstein, S; Groer, L; Grudberg, P; Grünendahl, S; Gupta, A; Gurzhiev, S N; Gutierrez, G; Gutierrez, P; Hadley, N J; Haggerty, H; Hagopian, S; Hagopian, V; Hahn, K S; Hall, R E; Hanlet, P; Hansen, S; Hauptman, J M; Hays, C; Hebert, C; Hedin, D; Heinson, A P; Heintz, U; Heuring, T; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoftun, J S; Hou, S; Huang, Y; Ito, A S; Jerger, S A; Jesik, R; Johns, K; Johnson, M; Jonckheere, A; Jones, M; Jöstlein, H; Juste, A; Kahn, S; Kajfasz, E; Karmanov, D; Karmgard, D; Kehoe, R; Kim, S K; Klima, B; Klopfenstein, C; Knuteson, B; Ko, W; Kohli, J M; Kostritskiy, A V; Kotcher, J; Kotwal, A V; Kozelov, A V; Kozlovsky, E A; Krane, J; Krishnaswamy, M R; Krzywdzinski, S; Kubantsev, M; Kuleshov, S; Kulik, Y; Kunori, S; Kuznetsov, V E; Landsberg, G; Leflat, A; Lehner, F; Li, J; Li, Q Z; Lima, J G; Lincoln, D; Linn, S L; Linnemann, J; Lipton, R; Lucotte, A; Lueking, L; Lundstedt, C; Maciel, A K; Madaras, R J; Manankov, V; Mao, H S; Marshall, T; Martin, M I; Martin, R D; Mauritz, K M; May, B; Mayorov, A A; McCarthy, R; McDonald, J; McMahon, T; Melanson, H L; Meng, X C; Merkin, M; Merritt, K W; Miao, C; Miettinen, H; Mihalcea, D; Mincer, A; Mishra, C S; Mokhov, N; Mondal, N K; Montgomery, H E; Moore, R W; Mostafa, M; da Motta, H; Nagy, E; Nang, F; Narain, M; Narasimham, V S; Neal, H A; Negret, J P; Negroni, S; Norman, D; Oesch, L; Oguri, V; Olivier, B; Oshima, N; Padley, P; Pan, L J; Para, A; Parashar, N; Partridge, R; Parua, N; Paterno, M; Patwa, A; Pawlik, B; Perkins, J; Peters, M; Peters, O; Piegaia, R; Piekarz, H; Pope, B G; Popkov, E; Prosper, H B; Protopopescu, S; Qian, J; Quintas, P Z; Raja, R; Rajagopalan, S; Ramberg, E; Rapidis, P A; Reay, N W; Reucroft, S; Rha, J; Rijssenbeek, M; Rockwell, T; Roco, M; Rubinov, P; Ruchti, R; Rutherfoord, J; Santoro, A; Sawyer, L; Schamberger, R D; Schellman, H; Schwartzman, A; Sculli, J; Sen, N; Shabalina, E; Shankar, H C; Shivpuri, R K; Shpakov, D; Shupe, M; Sidwell, R A; Simak, V; Singh, H; Singh, J B; Sirotenko, V; Slattery, P; Smith, E; Smith, R P; Snihur, R; Snow, G R; Snow, J; Snyder, S; Solomon, J; Sorín, V; Sosebee, M; Sotnikova, N; Soustruznik, K; Souza, M; Stanton, N R; Steinbrück, G; Stephens, R W; Stevenson, M L; Stichelbaut, F; Stoker, D; Stolin, V; Stoyanova, D A; Strauss, M; Streets, K; Strovink, M; Stutte, L; Sznajder, A; Taylor, W; Tentindo-Repond, S; Thompson, J; Toback, D; Tripathi, S M; Trippe, T G; Turcot, A S; Tuts, P M; van Gemmeren, P; Vaniev, V; Van Kooten, R; Varelas, N; Volkov, A A; Vorobiev, A P; Wahl, H D; Wang, H; Wang, Z; Warchol, J; Watts, G; Wayne, M; Weerts, H; White, A; White, J T; Whiteson, D; Wightman, J A; Wijngaarden, D A; Willis, S; Wimpenny, S J; Wirjawan, J V; Womersley, J; Wood, D R; Yamada, R; Yamin, P; Yasuda, T; Yip, K; Youssef, S; Yu, J; Yu, Z; Zanabria, M; Zheng, H; Zhou, Z; Zhu, Z H; Zielinski, M; Zieminska, D; Zieminski, A; Zutshi, V; Zverev, E G; Zylberstejn, A

2001-02-12

We report a search for effects of large extra spatial dimensions in pp collisions at a center-of-mass energy of 1.8 TeV with the D0 detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for several formalisms and numbers of extra dimensions.

The effects of neuron morphology on graph theoretic measures of network connectivity: the analysis of a two-level statistical model.

PubMed

Aćimović, Jugoslava; Mäki-Marttunen, Tuomo; Linne, Marja-Leena

2015-01-01

We developed a two-level statistical model that addresses the question of how properties of neurite morphology shape the large-scale network connectivity. We adopted a low-dimensional statistical description of neurites. From the neurite model description we derived the expected number of synapses, node degree, and the effective radius, the maximal distance between two neurons expected to form at least one synapse. We related these quantities to the network connectivity described using standard measures from graph theory, such as motif counts, clustering coefficient, minimal path length, and small-world coefficient. These measures are used in a neuroscience context to study phenomena from synaptic connectivity in the small neuronal networks to large scale functional connectivity in the cortex. For these measures we provide analytical solutions that clearly relate different model properties. Neurites that sparsely cover space lead to a small effective radius. If the effective radius is small compared to the overall neuron size the obtained networks share similarities with the uniform random networks as each neuron connects to a small number of distant neurons. Large neurites with densely packed branches lead to a large effective radius. If this effective radius is large compared to the neuron size, the obtained networks have many local connections. In between these extremes, the networks maximize the variability of connection repertoires. The presented approach connects the properties of neuron morphology with large scale network properties without requiring heavy simulations with many model parameters. The two-steps procedure provides an easier interpretation of the role of each modeled parameter. The model is flexible and each of its components can be further expanded. We identified a range of model parameters that maximizes variability in network connectivity, the property that might affect network capacity to exhibit different dynamical regimes.

Side effects of problem-solving strategies in large-scale nutrition science: towards a diversification of health.

PubMed

Penders, Bart; Vos, Rein; Horstman, Klasien

2009-11-01

Solving complex problems in large-scale research programmes requires cooperation and division of labour. Simultaneously, large-scale problem solving also gives rise to unintended side effects. Based upon 5 years of researching two large-scale nutrigenomic research programmes, we argue that problems are fragmented in order to be solved. These sub-problems are given priority for practical reasons and in the process of solving them, various changes are introduced in each sub-problem. Combined with additional diversity as a result of interdisciplinarity, this makes reassembling the original and overall goal of the research programme less likely. In the case of nutrigenomics and health, this produces a diversification of health. As a result, the public health goal of contemporary nutrition science is not reached in the large-scale research programmes we studied. Large-scale research programmes are very successful in producing scientific publications and new knowledge; however, in reaching their political goals they often are less successful.

Calculating Second-Order Effects in MOSFET's

NASA Technical Reports Server (NTRS)

Benumof, Reuben; Zoutendyk, John A.; Coss, James R.

1990-01-01

Collection of mathematical models includes second-order effects in n-channel, enhancement-mode, metal-oxide-semiconductor field-effect transistors (MOSFET's). When dimensions of circuit elements relatively large, effects neglected safely. However, as very-large-scale integration of microelectronic circuits leads to MOSFET's shorter or narrower than 2 micrometer, effects become significant in design and operation. Such computer programs as widely-used "Simulation Program With Integrated Circuit Emphasis, Version 2" (SPICE 2) include many of these effects. In second-order models of n-channel, enhancement-mode MOSFET, first-order gate-depletion region diminished by triangular-cross-section deletions on end and augmented by circular-wedge-cross-section bulges on sides.

Measurement of the dipole in the cross-correlation function of galaxies

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

Gaztanaga, Enrique; Bonvin, Camille; Hui, Lam, E-mail: gazta@ice.cat, E-mail: camille.bonvin@unige.ch, E-mail: lhui@astro.columbia.edu

It is usually assumed that in the linear regime the two-point correlation function of galaxies contains only a monopole, quadrupole and hexadecapole. Looking at cross-correlations between different populations of galaxies, this turns out not to be the case. In particular, the cross-correlations between a bright and a faint population of galaxies contain also a dipole. In this paper we present the first attempt to measure this dipole. We discuss the four types of effects that contribute to the dipole: relativistic distortions, evolution effect, wide-angle effect and large-angle effect. We show that the first three contributions are intrinsic anti-symmetric contributions thatmore » do not depend on the choice of angle used to measure the dipole. On the other hand the large-angle effect appears only if the angle chosen to extract the dipole breaks the symmetry of the problem. We show that the relativistic distortions, the evolution effect and the wide-angle effect are too small to be detected in the LOWz and CMASS sample of the BOSS survey. On the other hand with a specific combination of angles we are able to measure the large-angle effect with high significance. We emphasise that this large-angle dipole does not contain new physical information, since it is just a geometrical combination of the monopole and the quadrupole. However this measurement, which is in excellent agreement with theoretical predictions, validates our method for extracting the dipole from the two-point correlation function and it opens the way to the detection of relativistic effects in future surveys like e.g. DESI.« less

Large-scale weakly supervised object localization via latent category learning.

PubMed

Chong Wang; Kaiqi Huang; Weiqiang Ren; Junge Zhang; Maybank, Steve

2015-04-01

Localizing objects in cluttered backgrounds is challenging under large-scale weakly supervised conditions. Due to the cluttered image condition, objects usually have large ambiguity with backgrounds. Besides, there is also a lack of effective algorithm for large-scale weakly supervised localization in cluttered backgrounds. However, backgrounds contain useful latent information, e.g., the sky in the aeroplane class. If this latent information can be learned, object-background ambiguity can be largely reduced and background can be suppressed effectively. In this paper, we propose the latent category learning (LCL) in large-scale cluttered conditions. LCL is an unsupervised learning method which requires only image-level class labels. First, we use the latent semantic analysis with semantic object representation to learn the latent categories, which represent objects, object parts or backgrounds. Second, to determine which category contains the target object, we propose a category selection strategy by evaluating each category's discrimination. Finally, we propose the online LCL for use in large-scale conditions. Evaluation on the challenging PASCAL Visual Object Class (VOC) 2007 and the large-scale imagenet large-scale visual recognition challenge 2013 detection data sets shows that the method can improve the annotation precision by 10% over previous methods. More importantly, we achieve the detection precision which outperforms previous results by a large margin and can be competitive to the supervised deformable part model 5.0 baseline on both data sets.

Effective Mass Calculations for Two-dimensional Gas of Dipolar Fermions

NASA Astrophysics Data System (ADS)

Seydi, I.; Abedinpour, S. H.; Tanatar, B.

2017-06-01

We consider a two-dimensional system of ultracold dipolar fermions with dipole moments aligned in the perpendicular direction. We use the static structure factor information from Fermi-Hypernetted-Chain calculations to obtain the effective many-body dipole-dipole interaction and calculate the many-body effective mass of the system within the G0W approximation to the self-energy. A large cancellation between different contributions to the self-energy results in a weak dependence of the effective mass on the interaction strength over a large range of coupling constants.

An assessment of potential weather effects due to operation of the Space Orbiting Light Augmentation Reflector Energy System (SOLARES)

NASA Technical Reports Server (NTRS)

Allen, N. C.

1978-01-01

Implementation of SOLARES will input large quantities of heat continuously into a stationary location on the Earth's surface. The quantity of heat released by each of the SOlARES ground receivers, having a reflector orbit height of 6378 km, exceeds by 30 times that released by large power parks which were studied in detail. Using atmospheric models, estimates are presented for the local weather effects, the synoptic scale effects, and the global scale effects from such intense thermal radiation.

The role of large eddy fluctuations in the magnetic dynamics of the Madison Dynamo Experiment

NASA Astrophysics Data System (ADS)

Kaplan, Elliot

The Madison Dynamo Experiment (MDE), a liquid sodium magnetohydrodynamics experiment in a 1 m diameter sphere at the University of Wisconsin-Madison, had measured [in Spence et al., 2006] diamagnetic electrical currents in the experiment that violated an anti dynamo theorem for axisymmetric flow. The diamagnetic currents were instead attributed to nonaxisymmetric turbulent fluctuations. The experimental apparatus has been modified to reduce the strength of the large-scale turbulence driven by the shear layer in its flow. A 7.62 cm baffle was affixed to the equator of the machine to stabilize the shear layer. This reduction has correlated with a decrease in the magnetic fields, induced by the flow, which had been associated with the α and β effects of mean-field magnetohydrodynamics. The research presented herein presents the experimental evidence for reduced fluctuations and reduced mean field emfs, and provides a theoretical framework—based upon mean-field MHD—that connects the observations. The shapes of the large-scale velocity fluctuations are inferred by the spectra of induced magnetic fluctuations and measured in a kinematically similar water experiment. The Bullard and Gellman [1954] formalism demonstrates that the large-scale velocity fluctuations that are inhibited by the baffle can beat with the large-scale magnetic fluctuations that they produce to generate a mean-field emf of the sort measured in Spence et al. [2006]. This shows that the reduction of these large-scale eddies has brought the MDE closer to exciting a dynamo magnetic field. We also examine the mean-field like effects of large-scale (stable) eddies in the Dudley-James [1989] two-vortex dynamo (that the MDE was based upon). Rotating the axis of symmetry redefines the problem from one of an axisymmetric flow exciting a nonaxisymmetric field to one of a combination of axisymmetric and nonaxisymmetric flows exciting a predominantly axisymmetric magnetic eigenmode. As a result, specific interactions between large-scale velocity modes and large-scale magnetic modes are shown to correspond to the Ω effect and the mean-field α and β effects.

Tuning the bridging attraction between large hard particles by the softness of small microgels.

PubMed

Luo, Junhua; Yuan, Guangcui; Han, Charles C

2016-09-20

In this study, the attraction between large hard polystyrene (PS) spheres is studied by using three types of small microgels as bridging agents. One is a purely soft poly(N-isopropylacrylamide) (PNIPAM) microgel, the other two have a non-deformable PS hard core surrounded by a soft PNIPAM shell but are different in the core-shell ratio. The affinity for bridging the large PS spheres is provided and thus affected by the PNIPAM constituent in the microgels. The bridging effects caused by the microgels can be indirectly incorporated into their influence on the effective attraction interaction between the large hard spheres, since the size of the microgels is very small in comparison to the size of the PS hard spheres. At a given volume fraction of large PS spheres, they behave essentially as hard spheres in the absence of small microgels. By gradually adding the microgels, the large spheres are connected to each other through the bridging of small particles until the attraction strength reaches a maximum value, after which adding more small particles slowly decreases the effective attraction strength and eventually the large particles disperse individually when saturated adsorption is achieved. The aggregation and gelation behaviors triggered by these three types of small microgels are compared and discussed. A way to tune the strength and range of the short-range attractive potential via changing the softness of bridging microgels (which can be achieved either by using core-shell microgels or by changing the temperature) is proposed.

Superradiance in a Large and Dilute Cloud of Cold Atoms in the Linear-Optics Regime.

PubMed

Araújo, Michelle O; Krešić, Ivor; Kaiser, Robin; Guerin, William

2016-08-12

Superradiance has been extensively studied in the 1970s and 1980s in the regime of superfluorescence, where a large number of atoms are initially excited. Cooperative scattering in the linear-optics regime, or "single-photon superradiance," has been investigated much more recently, and superradiant decay has also been predicted, even for a spherical sample of large extent and low density, where the distance between atoms is much larger than the wavelength. Here, we demonstrate this effect experimentally by directly measuring the decay rate of the off-axis fluorescence of a large and dilute cloud of cold rubidium atoms after the sudden switch off of a low-intensity laser driving the atomic transition. We show that, at large detuning, the decay rate increases with the on-resonance optical depth. In contrast to forward scattering, the superradiant decay of off-axis fluorescence is suppressed near resonance due to attenuation and multiple-scattering effects.

Collapse of the world's largest herbivores.

PubMed

Ripple, William J; Newsome, Thomas M; Wolf, Christopher; Dirzo, Rodolfo; Everatt, Kristoffer T; Galetti, Mauro; Hayward, Matt W; Kerley, Graham I H; Levi, Taal; Lindsey, Peter A; Macdonald, David W; Malhi, Yadvinder; Painter, Luke E; Sandom, Christopher J; Terborgh, John; Van Valkenburgh, Blaire

2015-05-01

Large wild herbivores are crucial to ecosystems and human societies. We highlight the 74 largest terrestrial herbivore species on Earth (body mass ≥100 kg), the threats they face, their important and often overlooked ecosystem effects, and the conservation efforts needed to save them and their predators from extinction. Large herbivores are generally facing dramatic population declines and range contractions, such that ~60% are threatened with extinction. Nearly all threatened species are in developing countries, where major threats include hunting, land-use change, and resource depression by livestock. Loss of large herbivores can have cascading effects on other species including large carnivores, scavengers, mesoherbivores, small mammals, and ecological processes involving vegetation, hydrology, nutrient cycling, and fire regimes. The rate of large herbivore decline suggests that ever-larger swaths of the world will soon lack many of the vital ecological services these animals provide, resulting in enormous ecological and social costs.

Collapse of the world’s largest herbivores

PubMed Central

Ripple, William J.; Newsome, Thomas M.; Wolf, Christopher; Dirzo, Rodolfo; Everatt, Kristoffer T.; Galetti, Mauro; Hayward, Matt W.; Kerley, Graham I. H.; Levi, Taal; Lindsey, Peter A.; Macdonald, David W.; Malhi, Yadvinder; Painter, Luke E.; Sandom, Christopher J.; Terborgh, John; Van Valkenburgh, Blaire

2015-01-01

Large wild herbivores are crucial to ecosystems and human societies. We highlight the 74 largest terrestrial herbivore species on Earth (body mass ≥100 kg), the threats they face, their important and often overlooked ecosystem effects, and the conservation efforts needed to save them and their predators from extinction. Large herbivores are generally facing dramatic population declines and range contractions, such that ~60% are threatened with extinction. Nearly all threatened species are in developing countries, where major threats include hunting, land-use change, and resource depression by livestock. Loss of large herbivores can have cascading effects on other species including large carnivores, scavengers, mesoherbivores, small mammals, and ecological processes involving vegetation, hydrology, nutrient cycling, and fire regimes. The rate of large herbivore decline suggests that ever-larger swaths of the world will soon lack many of the vital ecological services these animals provide, resulting in enormous ecological and social costs. PMID:26601172

Reversing the Signaled Magnitude Effect in Delayed Matching to Sample: Delay-Specific Remembering?

ERIC Educational Resources Information Center

White, K. Geoffrey; Brown, Glenn S.

2011-01-01

Pigeons performed a delayed matching-to-sample task in which large or small reinforcers for correct remembering were signaled during the retention interval. Accuracy was low when small reinforcers were signaled, and high when large reinforcers were signaled (the signaled magnitude effect). When the reinforcer-size cue was switched from small to…

How to Measure Squeeze Out

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

Longacre, R. S.

2016-09-01

Squeeze out happen when the expanding central fireball flows around a large surface flux tube in a central Au-Au collision at RHIC. We model such an effect in a flux tube model. Two particle correlations with respect to the v 2 axis formed by the soft fireball particles flowing around this large flux tube is a way of measuring the effect.

Extreme antagonistic pleiotropy effects of DGAT1 on fat, milk and protein yields

USDA-ARS?s Scientific Manuscript database

A large-scale analysis using 294,079 first lactation Holstein cows, as well as a group of contemporary Holsteins and a Holstein line unselected since 1964, were used to study the genetic architecture associated with a mutation in the DGAT1 gene that has large effects on milk production. The ‘G’ alle...

Effectiveness of Large-Scale, State-Sponsored Language and Literacy Professional Development on Early Childhood Educator Outcomes

ERIC Educational Resources Information Center

Piasta, Shayne B.; Justice, Laura M.; O'Connell, Ann A.; Mauck, Susan A.; Weber-Mayrer, Melissa; Schachter, Rachel E.; Farley, Kristin S.; Spear, Caitlin F.

2017-01-01

The current study investigated the effectiveness of large-scale, state-sponsored language and literacy professional development (PD) intended to improve early childhood educators' knowledge, beliefs, and practices. PD was offered in a real-world context and delivered at-scale across the state, implemented by an independent contractor. Educators (n…

The Effectiveness of Computer-Mediated Communication on SLA: A Meta-Analysis and Research Synthesis

ERIC Educational Resources Information Center

Lin, Huifen

2012-01-01

Over the past two decades, a large body of research has been conducted on the effectiveness of computer-mediated communication (CMC) employed as either standalone or instructional tools in SLA classrooms. Findings from this large body of work, however, are not conclusive, making it important to identify factors that would inform its successful…

Effects of Shell-Buckling Knockdown Factors in Large Cylindrical Shells

NASA Technical Reports Server (NTRS)

Hrinda, Glenn A.

2012-01-01

Shell-buckling knockdown factors (SBKF) have been used in large cylindrical shell structures to account for uncertainty in buckling loads. As the diameter of the cylinder increases, achieving the manufacturing tolerances becomes increasingly more difficult. Knockdown factors account for manufacturing imperfections in the shell geometry by decreasing the allowable buckling load of the cylinder. In this paper, large-diameter (33 ft) cylinders are investigated by using various SBKF's. An investigation that is based on finite-element analysis (FEA) is used to develop design sensitivity relationships. Different manufacturing imperfections are modeled into a perfect cylinder to investigate the effects of these imperfections on buckling. The analysis results may be applicable to large- diameter rockets, cylindrical tower structures, bulk storage tanks, and silos.

Behavioral school psychology goes outdoors: the effect of organized games on playground aggression.

PubMed

Murphy, H A; Hutchison, J M; Bailey, J S

1983-01-01

This research focuses on the inappropriate, largely aggressive, behaviors of 344 K-2 children assigned to a playground prior to the beginning of the school day. Initially, a system for observing large numbers of children freely roaming over a large, open area was developed. This observational method was then used to determine the effectiveness of providing organized games for reducing potentially dangerous playground behaviors. Using a reversal (ABAB) design, it was found that the games, rope jumping, and foot racing, along with an infrequently used time-out procedure, significantly reduced the frequency of inappropriate incidents. It is suggested that when dealing with large groups, antecedent environmental manipulations may be more practical than providing consequences for the behaviors exhibited by identified individuals.

An innovative large scale integration of silicon nanowire-based field effect transistors

NASA Astrophysics Data System (ADS)

Legallais, M.; Nguyen, T. T. T.; Mouis, M.; Salem, B.; Robin, E.; Chenevier, P.; Ternon, C.

2018-05-01

Since the early 2000s, silicon nanowire field effect transistors are emerging as ultrasensitive biosensors while offering label-free, portable and rapid detection. Nevertheless, their large scale production remains an ongoing challenge due to time consuming, complex and costly technology. In order to bypass these issues, we report here on the first integration of silicon nanowire networks, called nanonet, into long channel field effect transistors using standard microelectronic process. A special attention is paid to the silicidation of the contacts which involved a large number of SiNWs. The electrical characteristics of these FETs constituted by randomly oriented silicon nanowires are also studied. Compatible integration on the back-end of CMOS readout and promising electrical performances open new opportunities for sensing applications.

Light-Drag Enhancement by a Highly Dispersive Rubidium Vapor.

PubMed

Safari, Akbar; De Leon, Israel; Mirhosseini, Mohammad; Magaña-Loaiza, Omar S; Boyd, Robert W

2016-01-08

The change in the speed of light as it propagates through a moving material has been a subject of study for almost two centuries. This phenomenon, known as the Fresnel light-drag effect, is quite small and usually requires a large interaction path length and/or a large velocity of the moving medium to be observed. Here, we show experimentally that the observed drag effect can be enhanced by over 2 orders of magnitude when the light beam propagates through a moving slow-light medium. Our results are in good agreement with the theoretical prediction, which indicates that, in the limit of large group indices, the strength of the light-drag effect is proportional to the group index of the moving medium.

High Resolution Mapping of Genetic Factors Affecting Abdominal Bristle Number in Drosophila Melanogaster

PubMed Central

Long, A. D.; Mullaney, S. L.; Reid, L. A.; Fry, J. D.; Langley, C. H.; Mackay, TFC.

1995-01-01

Factors responsible for selection response for abdominal bristle number and correlated responses in sternopleural bristle number were mapped to the X and third chromosome of Drosophila melanogaster. Lines divergent for high and low abdominal bristle number were created by 25 generations of artificial selection from a large base population, with an intensity of 25 individuals of each sex selected from 100 individuals of each sex scored per generation. Isogenic chromosome substitution lines in which the high (H) X or third chromosome were placed in an isogenic low (L) background were derived from the selection lines and from the 93 recombinant isogenic (RI) HL X and 67 RI chromosome 3 lines constructed from them. Highly polymorphic neutral r00 transposable elements were hybridized in situ to the polytene chromosomes of the RI lines to create a set of cytogenetic markers. These techniques yielded a dense map with an average spacing of 4 cM between informative markers. Factors affecting bristle number, and relative viability of the chromosome 3 RI lines, were mapped using a multiple regression interval mapping approach, conditioning on all markers >/=10 cM from the tested interval. Two factors with large effects on abdominal bristle number were mapped on the X chromosome and five factors on the third chromosome. One factor with a large effect on sternopleural bristle number was mapped to the X and two were mapped to the third chromosome; all factors with sternopleural effects corresponded to those with effects on abdominal bristle number. Two of the chromosome 3 factors with large effects on abdominal bristle number were also associated with reduced viability. Significant sex-specific effects and epistatic interactions between mapped factors of the same order of magnitude as the additive effects were observed. All factors mapped to the approximate positions of likely candidate loci (ASC, bb, emc, h, mab, Dl and E(spl)), previously characterized by mutations with large effects on bristle number. PMID:7768438

Finding the Right Fit: Assessing the Impact of Traditional v. Large Lecture/Small Lab Course Formats on a General Education Course

ERIC Educational Resources Information Center

Wildermuth, Susan M.; French, Tammy; Fredrick, Edward

2013-01-01

This study explores alternative approaches for teaching general education courses burdened with serving extremely large enrollments. It compares the effectiveness of a self-contained course in which each course section is taught by one instructor to a large lecture/small lab format in which all course enrollees attend one large lecture section and…

Testing for post-copulatory selection for major histocompatibility complex genotype in a semi-free-ranging primate population.

PubMed

Setchell, Joanna M; Abbott, Kristin M; Gonzalez, Jean-Paul; Knapp, Leslie A

2013-10-01

A large body of evidence suggests that major histocompatibility complex (MHC) genotype influences mate choice. However, few studies have investigated MHC-mediated post-copulatory mate choice under natural, or even semi-natural, conditions. We set out to explore this question in a large semi-free-ranging population of mandrills (Mandrillus sphinx) using MHC-DRB genotypes for 127 parent-offspring triads. First, we showed that offspring MHC heterozygosity correlates positively with parental MHC dissimilarity suggesting that mating among MHC dissimilar mates is efficient in increasing offspring MHC diversity. Second, we compared the haplotypes of the parental dyad with those of the offspring to test whether post-copulatory sexual selection favored offspring with two different MHC haplotypes, more diverse gamete combinations, or greater within-haplotype diversity. Limited statistical power meant that we could only detect medium or large effect sizes. Nevertheless, we found no evidence for selection for heterozygous offspring when parents share a haplotype (large effect size), genetic dissimilarity between parental haplotypes (we could detect an odds ratio of ≥1.86), or within-haplotype diversity (medium-large effect). These findings suggest that comparing parental and offspring haplotypes may be a useful approach to test for post-copulatory selection when matings cannot be observed, as is the case in many study systems. However, it will be extremely difficult to determine conclusively whether post-copulatory selection mechanisms for MHC genotype exist, particularly if the effect sizes are small, due to the difficulty in obtaining a sufficiently large sample. © 2013 Wiley Periodicals, Inc.

Got power? A systematic review of sample size adequacy in health professions education research.

PubMed

Cook, David A; Hatala, Rose

2015-03-01

Many education research studies employ small samples, which in turn lowers statistical power. We re-analyzed the results of a meta-analysis of simulation-based education to determine study power across a range of effect sizes, and the smallest effect that could be plausibly excluded. We systematically searched multiple databases through May 2011, and included all studies evaluating simulation-based education for health professionals in comparison with no intervention or another simulation intervention. Reviewers working in duplicate abstracted information to calculate standardized mean differences (SMD's). We included 897 original research studies. Among the 627 no-intervention-comparison studies the median sample size was 25. Only two studies (0.3%) had ≥80% power to detect a small difference (SMD > 0.2 standard deviations) and 136 (22%) had power to detect a large difference (SMD > 0.8). 110 no-intervention-comparison studies failed to find a statistically significant difference, but none excluded a small difference and only 47 (43%) excluded a large difference. Among 297 studies comparing alternate simulation approaches the median sample size was 30. Only one study (0.3%) had ≥80% power to detect a small difference and 79 (27%) had power to detect a large difference. Of the 128 studies that did not detect a statistically significant effect, 4 (3%) excluded a small difference and 91 (71%) excluded a large difference. In conclusion, most education research studies are powered only to detect effects of large magnitude. For most studies that do not reach statistical significance, the possibility of large and important differences still exists.

Generation of a Large-scale Magnetic Field in a Convective Full-sphere Cross-helicity Dynamo

NASA Astrophysics Data System (ADS)

Pipin, V. V.; Yokoi, N.

2018-05-01

We study the effects of the cross-helicity in the full-sphere large-scale mean-field dynamo models of a 0.3 M ⊙ star rotating with a period of 10 days. In exploring several dynamo scenarios that stem from magnetic field generation by the cross-helicity effect, we found that the cross-helicity provides the natural generation mechanisms for the large-scale scale axisymmetric and nonaxisymmetric magnetic field. Therefore, the rotating stars with convective envelopes can produce a large-scale magnetic field generated solely due to the turbulent cross-helicity effect (we call it γ 2-dynamo). Using mean-field models we compare the properties of the large-scale magnetic field organization that stems from dynamo mechanisms based on the kinetic helicity (associated with the α 2 dynamos) and cross-helicity. For the fully convective stars, both generation mechanisms can maintain large-scale dynamos even for the solid body rotation law inside the star. The nonaxisymmetric magnetic configurations become preferable when the cross-helicity and the α-effect operate independently of each other. This corresponds to situations with purely γ 2 or α 2 dynamos. The combination of these scenarios, i.e., the γ 2 α 2 dynamo, can generate preferably axisymmetric, dipole-like magnetic fields at strengths of several kGs. Thus, we found a new dynamo scenario that is able to generate an axisymmetric magnetic field even in the case of a solid body rotation of the star. We discuss the possible applications of our findings to stellar observations.

Irregular Warfare as a National Military Strategy Approach for Small States

DTIC Science & Technology

2013-12-01

the most effective strategy for them. Analyses of large numbers of historical cases show that a conventional approach is a road to defeat for...this thesis is to illuminate the potential for small states to improve the effect of their military by adopting an irregular strategy. The thesis is... effective strategy for them. Analyses of large numbers of historical cases show that a conventional approach is a road to defeat for small states

Effect of L-arginine on the relaxation caused by sodium nitroprusside on isolated rat renal artery.

PubMed

Orescanin, Z; Milovanović, S R

2006-12-01

In the present study we investigated the mechanism of nitric oxide induced relaxation of renal arteries, with or without endothelium, taken from normotensive and spontaneously hypertensive (SH) rats. With this purpose in mind, the effects of the nitric oxide donor, sodium nitroprusside (SNP), with and without L-arg in the medium, on isolated rat renal artery relaxation were studied. Relaxing effect of SNP was higher in normotensive (10(-5) M of SNP caused 220% of relaxation in the cases with endothelium and 240% without endothelium), in comparison with SH rats (100% of relaxation with endothelium and 150% without). L-arg antagonized the relaxing effect of SNP in the examined renal arteries, more in normotensive (100-160% with endothelium and 110-195% without) than in hypertensive ones (0-10% with endothelium and 35-75% without) at SNP concentrations 10(-7) - 10(-5) M, respectively (*P < 0.05; **P < 0.001). L-arg did not significantly change relaxing effect of SNP in the isolated renal arteries with endothelium taken from SH rats, which show that L-arg, by modifying the chemical versatility of NO into redox active forms -nitrosonium (NO+) and -nitroxyl (NO-), produces different relaxing effects in normotensive and hypertensive isolated arteries of rats, with or without endothelium, potentiating the role of nitroxyl induced relaxation in SH rats.

Small studies may overestimate the effect sizes in critical care meta-analyses: a meta-epidemiological study

PubMed Central

2013-01-01

Introduction Small-study effects refer to the fact that trials with limited sample sizes are more likely to report larger beneficial effects than large trials. However, this has never been investigated in critical care medicine. Thus, the present study aimed to examine the presence and extent of small-study effects in critical care medicine. Methods Critical care meta-analyses involving randomized controlled trials and reported mortality as an outcome measure were considered eligible for the study. Component trials were classified as large (≥100 patients per arm) and small (<100 patients per arm) according to their sample sizes. Ratio of odds ratio (ROR) was calculated for each meta-analysis and then RORs were combined using a meta-analytic approach. ROR<1 indicated larger beneficial effect in small trials. Small and large trials were compared in methodological qualities including sequence generating, blinding, allocation concealment, intention to treat and sample size calculation. Results A total of 27 critical care meta-analyses involving 317 trials were included. Of them, five meta-analyses showed statistically significant RORs <1, and other meta-analyses did not reach a statistical significance. Overall, the pooled ROR was 0.60 (95% CI: 0.53 to 0.68); the heterogeneity was moderate with an I2 of 50.3% (chi-squared = 52.30; P = 0.002). Large trials showed significantly better reporting quality than small trials in terms of sequence generating, allocation concealment, blinding, intention to treat, sample size calculation and incomplete follow-up data. Conclusions Small trials are more likely to report larger beneficial effects than large trials in critical care medicine, which could be partly explained by the lower methodological quality in small trials. Caution should be practiced in the interpretation of meta-analyses involving small trials. PMID:23302257

Effect of daily morphine administration and its discontinuation on delay discounting of food in rhesus monkeys

PubMed Central

Maguire, David R; Gerak, Lisa R; France, Charles P

2015-01-01

Opioid abusers discount delayed reinforcers more rapidly than non-users; however, it is unclear whether chronic drug administration or its discontinuation impact discounting. This study examined daily morphine administration and its discontinuation on delay discounting of food in rhesus monkeys. Responding on one lever delivered 1 food pellet immediately; responding on another lever delivered 2 food pellets either immediately or after a delay (30–120 sec) that increased within the session. Monkeys (n=3) responded for the large reinforcer when both reinforcers were delivered immediately and more for the smaller, immediately available reinforcer as delay to delivery of the large reinforcer increased. When administered acutely, morphine (0.032–5.6 mg/kg) increased trial omissions and had variable effects on choice, with small doses decreasing and large doses increasing choice of the large delayed reinforcer. Chronic morphine administration (0.1 mg/kg/day to 3.2 mg/kg twice daily) reduced choice of the large delayed reinforcer in two monkeys while increasing choice in a third monkey. Despite the development of tolerance to some effects (i.e., rightward shifts in dose-effect curves for the number of trials omitted) and evidence of mild opioid dependence (e.g., decrease in the number of trials completed as well as body weight), discontinuation of treatment did not appear to systematically impact discounting. Overall, these results suggest that repeated opioid administration causes persistent effects on choice under a delay discounting procedure; however, differences in the direction of effect among individuals suggest factors other than, or in addition to, changes in discounting might play a role. PMID:26397762

From the depletion attraction to the bridging attraction: the effect of solvent molecules on the effective colloidal interactions.

PubMed

Chen, Jie; Kline, Steven R; Liu, Yun

2015-02-28

Depletion attraction induced by non-adsorbing polymers or small particles in colloidal solutions has been widely used as a model colloidal interaction to understand aggregation behavior and phase diagrams, such as glass transitions and gelation. However, much less attention has been paid to study the effective colloidal interaction when small particles/molecules can be reversibly attracted to large colloidal particles. At the strong attraction limit, small particles can introduce bridging attraction as it can simultaneously attach to neighbouring large colloidal particles. We use Baxter's multi-component method for sticky hard sphere systems with the Percus-Yevick approximation to study the bridging attraction and its consequence to phase diagrams, which are controlled by the concentration of small particles and their interaction with large particles. When the concentration of small particles is very low, the bridging attraction strength increases very fast with the increase of small particle concentration. The attraction strength eventually reaches a maximum bridging attraction (MBA). Adding more small particles after the MBA concentration keeps decreasing the attraction strength until reaching a concentration above which the net effect of small particles only introduces an effective repulsion between large colloidal particles. These behaviors are qualitatively different from the concentration dependence of the depletion attraction on small particles and make phase diagrams very rich for bridging attraction systems. We calculate the spinodal and binodal regions, the percolation lines, the MBA lines, and the equivalent hard sphere interaction line for bridging attraction systems and have proposed a simple analytic solution to calculate the effective attraction strength using the concentrations of large and small particles. Our theoretical results are found to be consistent with experimental results reported recently.

Large and reversible inverse magnetocaloric effect in Ni48.1Co2.9Mn35.0In14.0 metamagnetic shape memory microwire

NASA Astrophysics Data System (ADS)

Qu, Y. H.; Cong, D. Y.; Chen, Z.; Gui, W. Y.; Sun, X. M.; Li, S. H.; Ma, L.; Wang, Y. D.

2017-11-01

High-performance magnetocaloric materials should have a large reversible magnetocaloric effect and good heat exchange capability. Here, we developed a Ni48.1Co2.9Mn35.0In14.0 metamagnetic shape memory microwire with a large and reversible inverse magnetocaloric effect. As compared to the bulk counterpart, the microwire shows a better combination of magnetostructural transformation parameters (magnetization difference across transformation ΔM, transformation entropy change ΔStr, thermal hysteresis ΔThys, and transformation interval ΔTint) and thus greatly reduced critical field required for complete and reversible magnetic-field-induced transformation. A strong and reversible metamagnetic transition occurred in the microwire, which facilitates the achievement of large reversible magnetoresponsive effects. Consequently, a large and reversible magnetic-field-induced entropy change ΔSm of 12.8 J kg-1 K-1 under 5 T was achieved in the microwire, which is the highest value reported heretofore in Ni-Mn-based magnetic shape memory wires. Furthermore, since microwires have a high surface/volume ratio, they exhibit very good heat exchange capability. The present Ni48.1Co2.9Mn35.0In14.0 microwire shows great potential for magnetic refrigeration. This study may stimulate further development of high-performance magnetocaloric wires for high-efficiency and environmentally friendly solid-state cooling.

Dynamic effective connectivity in cortically embedded systems of recurrently coupled synfire chains.

PubMed

Trengove, Chris; Diesmann, Markus; van Leeuwen, Cees

2016-02-01

As a candidate mechanism of neural representation, large numbers of synfire chains can efficiently be embedded in a balanced recurrent cortical network model. Here we study a model in which multiple synfire chains of variable strength are randomly coupled together to form a recurrent system. The system can be implemented both as a large-scale network of integrate-and-fire neurons and as a reduced model. The latter has binary-state pools as basic units but is otherwise isomorphic to the large-scale model, and provides an efficient tool for studying its behavior. Both the large-scale system and its reduced counterpart are able to sustain ongoing endogenous activity in the form of synfire waves, the proliferation of which is regulated by negative feedback caused by collateral noise. Within this equilibrium, diverse repertoires of ongoing activity are observed, including meta-stability and multiple steady states. These states arise in concert with an effective connectivity structure (ECS). The ECS admits a family of effective connectivity graphs (ECGs), parametrized by the mean global activity level. Of these graphs, the strongly connected components and their associated out-components account to a large extent for the observed steady states of the system. These results imply a notion of dynamic effective connectivity as governing neural computation with synfire chains, and related forms of cortical circuitry with complex topologies.

Proximity Effect Correction by Pattern Modified Stencil Mask in Large-Field Projection Electron-Beam Lithography

NASA Astrophysics Data System (ADS)

Kobinata, Hideo; Yamashita, Hiroshi; Nomura, Eiichi; Nakajima, Ken; Kuroki, Yukinori

1998-12-01

A new method for proximity effect correction, suitable for large-field electron-beam (EB) projection lithography with high accelerating voltage, such as SCALPEL and PREVAIL in the case where a stencil mask is used, is discussed. In this lithography, a large-field is exposed by the same dose, and thus, the dose modification method, which is used in the variable-shaped beam and the cell projection methods, cannot be used in this case. In this study, we report on development of a new proximity effect correction method which uses a pattern modified stencil mask suitable for high accelerating voltage and large-field EB projection lithography. In order to obtain the mask bias value, we have investigated linewidth reduction, due to the proximity effect, in the peripheral memory cell area, and found that it could be expressed by a simple function and all the correction parameters were easily determined from only the mask pattern data. The proximity effect for the peripheral array pattern could also be corrected by considering the pattern density. Calculated linewidth deviation was 3% or less for a 0.07-µm-L/S memory cell pattern and 5% or less for a 0.14-µm-line and 0.42-µm-space peripheral array pattern, simultaneously.

Association of parameter, software, and hardware variation with large-scale behavior across 57,000 climate models

PubMed Central

Knight, Christopher G.; Knight, Sylvia H. E.; Massey, Neil; Aina, Tolu; Christensen, Carl; Frame, Dave J.; Kettleborough, Jamie A.; Martin, Andrew; Pascoe, Stephen; Sanderson, Ben; Stainforth, David A.; Allen, Myles R.

2007-01-01

In complex spatial models, as used to predict the climate response to greenhouse gas emissions, parameter variation within plausible bounds has major effects on model behavior of interest. Here, we present an unprecedentedly large ensemble of >57,000 climate model runs in which 10 parameters, initial conditions, hardware, and software used to run the model all have been varied. We relate information about the model runs to large-scale model behavior (equilibrium sensitivity of global mean temperature to a doubling of carbon dioxide). We demonstrate that effects of parameter, hardware, and software variation are detectable, complex, and interacting. However, we find most of the effects of parameter variation are caused by a small subset of parameters. Notably, the entrainment coefficient in clouds is associated with 30% of the variation seen in climate sensitivity, although both low and high values can give high climate sensitivity. We demonstrate that the effect of hardware and software is small relative to the effect of parameter variation and, over the wide range of systems tested, may be treated as equivalent to that caused by changes in initial conditions. We discuss the significance of these results in relation to the design and interpretation of climate modeling experiments and large-scale modeling more generally. PMID:17640921

Instream large wood: Denitrification hotspots with low N2O production

EPA Science Inventory

We examined the effect of instream large wood on denitrification capacity in two contrasting, lower order streams — one that drains an agricultural watershed with no riparian forest and minimal stores of instream large wood and another that drains a forested watershed with an ext...

Reflections on Teaching a Large Class.

ERIC Educational Resources Information Center

Miner, Rick

1992-01-01

Uses an analysis of small- and large-class differences as a framework for planning for and teaching a large class. Analyzes the process of developing and offering an organizational behavior class to 141 college students. Suggests ways to improve teaching effectiveness by minimizing psychological and physical distances, redistributing resources,…

Effectiveness of buffered propionic-acid preservatives for large hay packages

USDA-ARS?s Scientific Manuscript database

Most hay producers realize that hays packaged in large-round or large-square bales are particularly sensitive to spontaneous heating, dry matter losses, and negative changes in forage quality. During the last two decades, this has become an important dilemma for hay producers because the cost and av...

Collaborative Working for Large Digitisation Projects

ERIC Educational Resources Information Center

Yeates, Robin; Guy, Damon

2006-01-01

Purpose: To explore the effectiveness of large-scale consortia for disseminating local heritage via the web. To describe the creation of a large geographically based cultural heritage consortium in the South East of England and management lessons resulting from a major web site digitisation project. To encourage the improved sharing of experience…

Large-D gravity and low-D strings.

PubMed

Emparan, Roberto; Grumiller, Daniel; Tanabe, Kentaro

2013-06-21

We show that in the limit of a large number of dimensions a wide class of nonextremal neutral black holes has a universal near-horizon limit. The limiting geometry is the two-dimensional black hole of string theory with a two-dimensional target space. Its conformal symmetry explains the properties of massless scalars found recently in the large-D limit. For black branes with string charges, the near-horizon geometry is that of the three-dimensional black strings of Horne and Horowitz. The analogies between the α' expansion in string theory and the large-D expansion in gravity suggest a possible effective string description of the large-D limit of black holes. We comment on applications to several subjects, in particular to the problem of critical collapse.

Designing for Scale: Reflections on Rolling Out Reading Improvement in Kenya and Liberia.

PubMed

Gove, Amber; Korda Poole, Medina; Piper, Benjamin

2017-03-01

Since 2008, the Ministries of Education in Liberia and Kenya have undertaken transitions from small-scale pilot programs to improve reading outcomes among primary learners to the large-scale implementation of reading interventions. The effects of the pilots on learning outcomes were significant, but questions remained regarding whether such large gains could be sustained at scale. In this article, the authors dissect the Liberian and Kenyan experiences with implementing large-scale reading programs, documenting the critical components and conditions of the program designs that affected the likelihood of successfully transitioning from pilot to scale. They also review the design, deployment, and effectiveness of each pilot program and the scale, design, duration, enabling conditions, and initial effectiveness results of the scaled programs in each country. The implications of these results for the design of both pilot and large-scale reading programs are discussed in light of the experiences of both the Liberian and Kenyan programs. © 2017 Wiley Periodicals, Inc.

DOPPLER CALCULATIONS FOR LARGE FAST CERAMIC REACTORS--EFFECTS OF IMPROVED METHODS AND RECENT CROSS SECTION INFORMATION

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

Greebler, P.; Goldman, E.

1962-12-19

Doppler calculations for large fast ceramic reactors (FCR), using recent cross section information and improved methods, are described. Cross sections of U/sup 238/, Pu/sup 239/, and Pu/sup 210/ with fuel temperature variations needed for perturbation calculations of Doppler reactivity changes are tabulated as a function of potential scattering cross section per absorber isotope at energies below 400 kev. These may be used in Doppler calculations for anv fast reactor. Results of Doppler calculations on a large fast ceramic reactor are given to show the effects of the improved calculation methods and of recent cross secrion data on the calculated Dopplermore » coefficient. The updated methods and cross sections used yield a somewhat harder spectrum and accordingly a somewhat smaller Doppler coefficient for a given FCR core size and composition than calculated in earlier work, but they support the essential conclusion derived earlier that the Doppler effect provides an important safety advantage in a large FCR. 28 references. (auth)« less

Charged black rings at large D

NASA Astrophysics Data System (ADS)

Chen, Bin; Li, Peng-Cheng; Wang, Zi-zhi

2017-04-01

We study the charged slowly rotating black holes in the Einstein-Maxwell theory in the large dimensions ( D). By using the 1 /D expansion in the near regions of the black holes we obtain the effective equations for the charged slowly rotating black holes. The effective equations capture the dynamics of various stationary solutions, including the charged black ring, the charged slowly rotating Myers-Perry black hole and the charged slowly boosted black string. Via different embeddings we construct these stationary solutions explicitly. For the charged black ring at large D, we find that the charge lowers the angular momentum due to the regularity condition on the solution. By performing the perturbation analysis of the effective equations, we obtain the quasinormal modes of the charge perturbation and the gravitational perturbation analytically. Like the neutral case the charged thin black ring suffers from the Gregory-Laflamme-like instability under the non-axisymmetric perturbations, but the charge weakens the instability. Besides, we find that the large D analysis always respects the cosmic censorship.

Influence of the large-small split effect on strategy choice in complex subtraction.

PubMed

Xiang, Yan Hui; Wu, Hao; Shang, Rui Hong; Chao, Xiaomei; Ren, Ting Ting; Zheng, Li Ling; Mo, Lei

2018-04-01

Two main theories have been used to explain the arithmetic split effect: decision-making process theory and strategy choice theory. Using the inequality paradigm, previous studies have confirmed that individuals tend to adopt a plausibility-checking strategy and a whole-calculation strategy to solve large and small split problems in complex addition arithmetic, respectively. This supports strategy choice theory, but it is unknown whether this theory also explains performance in solving different split problems in complex subtraction arithmetic. This study used small, intermediate and large split sizes, with each split condition being further divided into problems requiring and not requiring borrowing. The reaction times (RTs) for large and intermediate splits were significantly shorter than those for small splits, while accuracy was significantly higher for large and middle splits than for small splits, reflecting no speed-accuracy trade-off. Further, RTs and accuracy differed significantly between the borrow and no-borrow conditions only for small splits. This study indicates that strategy choice theory is suitable to explain the split effect in complex subtraction arithmetic. That is, individuals tend to choose the plausibility-checking strategy or the whole-calculation strategy according to the split size. © 2016 International Union of Psychological Science.

Conservation lessons from large-mammal manipulations in East African savannas: the KLEE, UHURU, and GLADE experiments.

PubMed

Goheen, Jacob R; Augustine, David J; Veblen, Kari E; Kimuyu, Duncan M; Palmer, Todd M; Porensky, Lauren M; Pringle, Robert M; Ratnam, Jayashree; Riginos, Corinna; Sankaran, Mahesh; Ford, Adam T; Hassan, Abdikadir A; Jakopak, Rhiannon; Kartzinel, Tyler R; Kurukura, Samson; Louthan, Allison M; Odadi, Wilfred O; Otieno, Tobias O; Wambua, Alois M; Young, Hillary S; Young, Truman P

2018-05-11

African savannas support an iconic fauna, but they are undergoing large-scale population declines and extinctions of large (>5 kg) mammals. Long-term, controlled, replicated experiments that explore the consequences of this defaunation (and its replacement with livestock) are rare. The Mpala Research Centre in Laikipia County, Kenya, hosts three such experiments, spanning two adjacent ecosystems and environmental gradients within them: the Kenya Long-Term Exclosure Experiment (KLEE; since 1995), the Glade Legacies and Defaunation Experiment (GLADE; since 1999), and the Ungulate Herbivory Under Rainfall Uncertainty experiment (UHURU; since 2008). Common themes unifying these experiments are (1) evidence of profound effects of large mammalian herbivores on herbaceous and woody plant communities; (2) competition and compensation across herbivore guilds, including rodents; and (3) trophic cascades and other indirect effects. We synthesize findings from the past two decades to highlight generalities and idiosyncrasies among these experiments, and highlight six lessons that we believe are pertinent for conservation. The removal of large mammalian herbivores has dramatic effects on the ecology of these ecosystems; their ability to rebound from these changes (after possible refaunation) remains unexplored. © 2018 New York Academy of Sciences.

Mindfulness-based interventions for binge eating: a systematic review and meta-analysis.

PubMed

Godfrey, Kathryn M; Gallo, Linda C; Afari, Niloofar

2015-04-01

Mindfulness-based interventions are increasingly used to treat binge eating. The effects of these interventions have not been reviewed comprehensively. This systematic review and meta-analysis sought to summarize the literature on mindfulness-based interventions and determine their impact on binge eating behavior. PubMED, Web of Science, and PsycINFO were searched using keywords binge eating, overeating, objective bulimic episodes, acceptance and commitment therapy, dialectical behavior therapy, mindfulness, meditation, mindful eating. Of 151 records screened, 19 studies met inclusion criteria. Most studies showed effects of large magnitude. Results of random effects meta-analyses supported large or medium-large effects of these interventions on binge eating (within-group random effects mean Hedge's g = -1.12, 95 % CI -1.67, -0.80, k = 18; between-group mean Hedge's g = -0.70, 95 % CI -1.16, -0.24, k = 7). However, there was high statistical heterogeneity among the studies (within-group I(2) = 93 %; between-group I(2) = 90 %). Limitations and future research directions are discussed.

Climate and litter quality differently modulate the effects of soil fauna on litter decomposition across biomes.

PubMed

García-Palacios, Pablo; Maestre, Fernando T; Kattge, Jens; Wall, Diana H

2013-08-01

Climate and litter quality have been identified as major drivers of litter decomposition at large spatial scales. However, the role played by soil fauna remains largely unknown, despite its importance for litter fragmentation and microbial activity. We synthesised litterbag studies to quantify the effect sizes of soil fauna on litter decomposition rates at the global and biome scales, and to assess how climate, litter quality and soil fauna interact to determine such rates. Soil fauna consistently enhanced litter decomposition at both global and biome scales (average increment ~ 37%). [corrected]. However, climate and litter quality differently modulated the effects of soil fauna on decomposition rates between biomes, from climate-driven biomes to those where climate effects were mediated by changes in litter quality. Our results advocate for the inclusion of biome-specific soil fauna effects on litter decomposition as a mean to reduce the unexplained variation in large-scale decomposition models. © 2013 John Wiley & Sons Ltd/CNRS.

Co-occurrence frequency evaluated with large language corpora boosts semantic priming effects.

PubMed

Brunellière, Angèle; Perre, Laetitia; Tran, ThiMai; Bonnotte, Isabelle

2017-09-01

In recent decades, many computational techniques have been developed to analyse the contextual usage of words in large language corpora. The present study examined whether the co-occurrence frequency obtained from large language corpora might boost purely semantic priming effects. Two experiments were conducted: one with conscious semantic priming, the other with subliminal semantic priming. Both experiments contrasted three semantic priming contexts: an unrelated priming context and two related priming contexts with word pairs that are semantically related and that co-occur either frequently or infrequently. In the conscious priming presentation (166-ms stimulus-onset asynchrony, SOA), a semantic priming effect was recorded in both related priming contexts, which was greater with higher co-occurrence frequency. In the subliminal priming presentation (66-ms SOA), no significant priming effect was shown, regardless of the related priming context. These results show that co-occurrence frequency boosts pure semantic priming effects and are discussed with reference to models of semantic network.

Eddy current effect on the microwave permeability of Fe-based nanocrystalline flakes with different sizes

NASA Astrophysics Data System (ADS)

Wu, Yanhui; Han, Mangui; Tang, Zhongkai; Deng, Longjiang

2014-04-01

The effective permeability values of composites containing Fe-Cu-Nb-Si-B nanocrystalline flakes have been studied within 0.5-10 GHz. Obvious differences in microwave permeability have been observed between large flakes (size range: 23-111 μm, average thickness: 4.5 μm) and small flakes (size range: 3-21 μm, average thickness: 1.3 μm). The initial real part of microwave permeability of large flakes is larger but it is decreasing faster. The larger flakes also show a larger magnetic loss. Taking into account the eddy current effect, the intrinsic microwave permeability values have been extracted based on the modified Maxwell-Garnet law, which have also been verified by the Acher's law. The dependences of skin depth on frequency have been calculated for both kinds of flakes. It is shown that the eddy current effect in the large flakes is significant. However, the eddy current effect can be ignored in the small flakes.

Seemingly unrelated intervention time series models for effectiveness evaluation of large scale environmental remediation.

PubMed

Ip, Ryan H L; Li, W K; Leung, Kenneth M Y

2013-09-15

Large scale environmental remediation projects applied to sea water always involve large amount of capital investments. Rigorous effectiveness evaluations of such projects are, therefore, necessary and essential for policy review and future planning. This study aims at investigating effectiveness of environmental remediation using three different Seemingly Unrelated Regression (SUR) time series models with intervention effects, including Model (1) assuming no correlation within and across variables, Model (2) assuming no correlation across variable but allowing correlations within variable across different sites, and Model (3) allowing all possible correlations among variables (i.e., an unrestricted model). The results suggested that the unrestricted SUR model is the most reliable one, consistently having smallest variations of the estimated model parameters. We discussed our results with reference to marine water quality management in Hong Kong while bringing managerial issues into consideration. Copyright © 2013 Elsevier Ltd. All rights reserved.

Vibrations of beams and rods carrying a moving mass

NASA Astrophysics Data System (ADS)

Zhao, X. W.; van der Heijden, G. H. M.; Hu, Z. D.

2016-05-01

We study the vibration of slender one-dimensional elastic structures (beams, cables, wires, rods) under the effect of a moving mass or load. We first consider the classical small- deflection (Euler-Bernoulli) beam case, where we look at tip vibrations of a cantilever as a model for a barreled launch system. Then we develop a theory for large deformations based on Cosserat rod theory. We illustrate the effect of moving loads on large-deformation structures with a few cable and arch problems. Large deformations are found to have a resonance detuning effect on the cable. For the arch we find different failure modes depending on its depth: a shallow arch fails by in-plane collapse, while a deep arch fails by sideways flopping. In both cases the speed of the traversing load is found to have a stabilising effect on the structure, with failure suppressed entirely at sufficiently high speed.

Effect of Eccentricity on the Static and Dynamic Performance of a Turbulent Hybrid Bearing

NASA Technical Reports Server (NTRS)

Sanandres, Luis A.

1991-01-01

The effect of journal eccentricity on the static and dynamic performance of a water lubricated, 5-recess hybrid bearing is presented in detail. The hydrostatic bearing has been designed to operate at a high speed and with a large level of external pressurization. The operating conditions determine the flow in the bearing to be highly turbulent and strongly dominated by fluid inertia effects. The analysis covers the spectrum of journal center displacements directed towards the middle of a recess and towards the mid-land portion between two consecutive recesses. Predicted dynamic force coefficients are uniform for small to moderate eccentricities. For large journal center displacements, fluid cavitation and recess position determine large changes in the bearing dynamic performance. The effect of fluid inertia force coefficients on the threshold speed of instability and whirl ratio of a single mass flexible rotor is discussed.

Ultra-high gain diffusion-driven organic transistor.

PubMed

Torricelli, Fabrizio; Colalongo, Luigi; Raiteri, Daniele; Kovács-Vajna, Zsolt Miklós; Cantatore, Eugenio

2016-02-01

Emerging large-area technologies based on organic transistors are enabling the fabrication of low-cost flexible circuits, smart sensors and biomedical devices. High-gain transistors are essential for the development of large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show a new organic field-effect transistor architecture with a gain larger than 700. This is the highest gain ever reported for organic field-effect transistors. In the proposed organic field-effect transistor, the charge injection and extraction at the metal-semiconductor contacts are driven by the charge diffusion. The ideal conditions of ohmic contacts with negligible contact resistance and flat current saturation are demonstrated. The approach is general and can be extended to any thin-film technology opening unprecedented opportunities for the development of high-performance flexible electronics.

Ultra-high gain diffusion-driven organic transistor

NASA Astrophysics Data System (ADS)

Torricelli, Fabrizio; Colalongo, Luigi; Raiteri, Daniele; Kovács-Vajna, Zsolt Miklós; Cantatore, Eugenio

2016-02-01

Emerging large-area technologies based on organic transistors are enabling the fabrication of low-cost flexible circuits, smart sensors and biomedical devices. High-gain transistors are essential for the development of large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show a new organic field-effect transistor architecture with a gain larger than 700. This is the highest gain ever reported for organic field-effect transistors. In the proposed organic field-effect transistor, the charge injection and extraction at the metal-semiconductor contacts are driven by the charge diffusion. The ideal conditions of ohmic contacts with negligible contact resistance and flat current saturation are demonstrated. The approach is general and can be extended to any thin-film technology opening unprecedented opportunities for the development of high-performance flexible electronics.

Effects of Single P-Element Insertions on Bristle Number and Viability in Drosophila Melanogaster

PubMed Central

Lyman, R. F.; Lawrence, F.; Nuzhdin, S. V.; Mackay, TFC.

1996-01-01

Single P-element mutagenesis was used to construct 1094 lines with P[lArB] inserts on all three major chromosomes in an isogenic background previously free of P elements. The effects of insertions on bristle number and on viability were assessed by comparison to 392 control lines. The variance and effects of P-element inserts on bristle number and viability were larger than those inferred from spontaneous mutations. The distributions of effects on bristle number were symmetrical and highly leptokurtic, such that a few inserts with large effects caused most of the increase in variance. The distribution of effects on viability were negatively skewed and platykurtic. On average, the effects of P-element insertions on bristle number were partly recessive and on viability were completely recessive. P-element inserts with large effects on bristle number tended to have reduced viability, but the correlation between the absolute value of the effects on bristle number and on viability was not strong. Fifty P-element inserts tagging quantitative trait loci (QTLs) with large effects on bristle number were mapped cytogenetically. Two P-element-induced scabrous alleles and five extramacrochaetae alleles were generated. Single P-element mutagenesis is a powerful method for identifying QTLs at the level of genetic locus. PMID:8722781

Effects of single P-element insertions on bristle number and viability in Drosophila melanogaster.

PubMed

Lyman, R F; Lawrence, F; Nuzhdin, S V; Mackay, T F

1996-05-01

Single P-element mutagenesis was used to construct 1094 lines with P[lArB] inserts on all three major chromosomes in an isogenic background previously free of P elements. The effects of insertions on bristle number and on viability were assessed by comparison to 392 control lines. The variance and effects of P-element inserts on bristle number and viability were larger than those inferred from spontaneous mutations. The distributions of effects on bristle number were symmetrical and highly leptokurtic, such that a few inserts with large effects caused most of the increase in variance. The distribution of effects on viability were negatively skewed and platykurtic. On average, the effects of P-element insertions on bristle number were partly recessive and on viability were completely recessive. P-element inserts with large effects on bristle number tended to have reduced viability, but the correlation between the absolute value of the effects on bristle number and on viability was not strong. Fifty P-element inserts tagging quantitative trait loci (QTLs) with large effects on bristle number were mapped cytogenetically. Two P-element-induced scabrous alleles and five extramacrochaetae alleles were generated. Single P-element mutagenesis is a powerful method for identifying QTLs at the level of genetic locus.

Nonlinear ordinary difference equations

NASA Technical Reports Server (NTRS)

Caughey, T. K.

1979-01-01

Future space vehicles will be relatively large and flexible, and active control will be necessary to maintain geometrical configuration. While the stresses and strains in these space vehicles are not expected to be excessively large, their cumulative effects will cause significant geometrical nonlinearities to appear in the equations of motion, in addition to the nonlinearities caused by material properties. Since the only effective tool for the analysis of such large complex structures is the digital computer, it will be necessary to gain a better understanding of the nonlinear ordinary difference equations which result from the time discretization of the semidiscrete equations of motion for such structures.

Effects of large-scale irregularities of the ionosphere in the propagation of decametric radio waves

NASA Astrophysics Data System (ADS)

Kerblai, T. S.; Kovalevskaia, E. M.

1985-12-01

A numerical experiment is used to study the simultaneous influence of regular space-time gradients and large-scale traveling ionospheric disturbances (TIDs) as manifested in the angular and Doppler characteristics of decametric-wave propagation. Conditions typical for middle latitudes are chosen as the ionospheric models: conditions under which large-scale TIDs in the F2-layer evolve on the background of winter or equinox structures of the ionosphere. Certain conclusions on the character of TID effects for various states of the background ionosphere are drawn which can be used to interpret experimental results.

Large structures and tethers working group

NASA Technical Reports Server (NTRS)

Murphy, G.; Garrett, H.; Samir, U.; Barnett, A.; Raitt, J.; Sullivan, J.; Katz, I.

1986-01-01

The Large Structures and Tethers Working Group sought to clarify the meaning of large structures and tethers as they related to space systems. Large was assumed to mean that the characteristic length of the structure was greater than one of such relevant plasma characteristics as ion gyroradius or debey length. Typically, anything greater than or equal to the Shuttle dimensions was considered large. It was agreed that most large space systems that the tether could be better categorized as extended length, area, or volume structures. The key environmental interactions were then identified in terms of these three categories. In the following Working Group summary, these categories and the related interactions are defined in detail. The emphasis is on how increases in each of the three spatial dimensions uniquely determine the interactions with the near-Earth space environment. Interactions with the environments around the other planets and the solar wind were assumed to be similar or capable of being extrapolated from the near-Earth results. It should be remembered in the following that the effects on large systems do not just affect specific technologies but will quite likely impact whole missions. Finally, the possible effects of large systems on the plasma environment, although only briefly discussed, were felt to be of potentially great concern.

Effects of symmetry and spin configuration on spin-dependent transport properties of iron-phthalocyanine-based devices

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

Cui, Li-Ling; School of Science, Hunan University of Technology, Zhuzhou 412007; Yang, Bing-Chu, E-mail: bingchuyang@csu.edu.cn

2014-07-21

Spin-dependent transport properties of nanodevices constructed by iron-phthalocyanine (FePc) molecule sandwiched between two zigzag graphene nanoribbon electrodes are studied using first-principles quantum transport calculations. The effects of the symmetry and spin configuration of electrodes have been taken into account. It is found that large magnetoresistance, large spin polarization, dual spin-filtering, and negative differential resistance (NDR) can coexist in these devices. Our results show that 5Z-FePc system presents well conductive ability in both parallel (P) and anti-parallel (AP) configurations. For 6Z-FePc-P system, spin filtering effect and large spin polarization can be found. A dual spin filtering and NDR can also bemore » shown in 6Z-FePc-AP. Our studies indicate that the dual spin filtering effect depends on the orbitals symmetry of the energy bands and spin mismatching of the electrodes. And all the effects would open up possibilities for their applications in spin-valve, spin-filter as well as effective spin diode devices.« less

Cross-lingual neighborhood effects in generalized lexical decision and natural reading.

PubMed

Dirix, Nicolas; Cop, Uschi; Drieghe, Denis; Duyck, Wouter

2017-06-01

The present study assessed intra- and cross-lingual neighborhood effects, using both a generalized lexical decision task and an analysis of a large-scale bilingual eye-tracking corpus (Cop, Dirix, Drieghe, & Duyck, 2016). Using new neighborhood density and frequency measures, the general lexical decision task yielded an inhibitory cross-lingual neighborhood density effect on reading times of second language words, replicating van Heuven, Dijkstra, and Grainger (1998). Reaction times for native language words were not influenced by neighborhood density or frequency but error rates showed cross-lingual neighborhood effects depending on target word frequency. The large-scale eye movement corpus confirmed effects of cross-lingual neighborhood on natural reading, even though participants were reading a novel in a unilingual context. Especially second language reading and to a lesser extent native language reading were influenced by lexical candidates from the nontarget language, although these effects in natural reading were largely facilitatory. These results offer strong and direct support for bilingual word recognition models that assume language-independent lexical access. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Effect of Plyometric Training on Vertical Jump Performance in Female Athletes: A Systematic Review and Meta-Analysis.

PubMed

Stojanović, Emilija; Ristić, Vladimir; McMaster, Daniel Travis; Milanović, Zoran

2017-05-01

Plyometric training is an effective method to prevent knee injuries in female athletes; however, the effects of plyometric training on jump performance in female athletes is unclear. The aim of this systematic review and meta-analysis was to determine the effectiveness of plyometric training on vertical jump (VJ) performance of amateur, collegiate and elite female athletes. Six electronic databases were searched (PubMed, MEDLINE, ERIC, Google Scholar, SCIndex and ScienceDirect). The included studies were coded for the following criteria: training status, training modality and type of outcome measures. The methodological quality of each study was assessed using the physiotherapy evidence database (PEDro) scale. The effects of plyometric training on VJ performance were based on the following standardised pre-post testing effect size (ES) thresholds: trivial (<0.20), small (0.21-0.60), moderate (0.61-1.20), large (1.21-2.00), very large (2.01-4.00) and extremely large (>4.00). A total of 16 studies met the inclusion criteria. The meta-analysis revealed that plyometric training had a most likely moderate effect on countermovement jump (CMJ) height performance (ES = 1.09; 95 % confidence interval [CI] 0.57-1.61; I 2  = 75.60 %). Plyometric training interventions of less than 10 weeks in duration had a most likely small effect on CMJ height performance (ES = 0.58; 95 % CI 0.25-0.91). In contrast, plyometric training durations greater than 10 weeks had a most likely large effect on CMJ height (ES = 1.87; 95 % CI 0.73-3.01). The effect of plyometric training on concentric-only squat jump (SJ) height was likely small (ES = 0.44; 95 % CI -0.09 to 0.97). Similar effects were observed on SJ height after 6 weeks of plyometric training in amateur (ES = 0.35) and young (ES = 0.49) athletes, respectively. The effect of plyometric training on CMJ height with the arm swing was likely large (ES = 1.31; 95 % CI -0.04 to 2.65). The largest plyometric training effects were observed in drop jump (DJ) height performance (ES = 3.59; 95 % CI -3.04 to 10.23). Most likely extremely large plyometric training effects on DJ height performance (ES = 7.07; 95 % CI 4.71-9.43) were observed following 12 weeks of plyometric training. In contrast, a possibly small positive training effect (ES = 0.30; 95 % CI -0.63 to 1.23) was observed following 6 weeks of plyometric training. Plyometric training is an effective form of training to improve VJ performance (e.g. CMJ, SJ and DJ) in female athletes. The benefits of plyometric training on VJ performance are greater for interventions of longer duration (≥10 weeks).

Impact of large-scale tides on cosmological distortions via redshift-space power spectrum

NASA Astrophysics Data System (ADS)

Akitsu, Kazuyuki; Takada, Masahiro

2018-03-01

Although large-scale perturbations beyond a finite-volume survey region are not direct observables, these affect measurements of clustering statistics of small-scale (subsurvey) perturbations in large-scale structure, compared with the ensemble average, via the mode-coupling effect. In this paper we show that a large-scale tide induced by scalar perturbations causes apparent anisotropic distortions in the redshift-space power spectrum of galaxies in a way depending on an alignment between the tide, wave vector of small-scale modes and line-of-sight direction. Using the perturbation theory of structure formation, we derive a response function of the redshift-space power spectrum to large-scale tide. We then investigate the impact of large-scale tide on estimation of cosmological distances and the redshift-space distortion parameter via the measured redshift-space power spectrum for a hypothetical large-volume survey, based on the Fisher matrix formalism. To do this, we treat the large-scale tide as a signal, rather than an additional source of the statistical errors, and show that a degradation in the parameter is restored if we can employ the prior on the rms amplitude expected for the standard cold dark matter (CDM) model. We also discuss whether the large-scale tide can be constrained at an accuracy better than the CDM prediction, if the effects up to a larger wave number in the nonlinear regime can be included.

A steadying effect of acoustic excitation on transitory stall

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.

1991-01-01

The effect of acoustic excitation on a class of separated flows with a transitional boundary layer at the point of separation is considered. Experimental results on the flow over airfoils, a two-dimensional backward-facing step, and through large angle conical diffusers are presented. In all cases, the separated flow undergoes large amplitude fluctuations, much of the energy being concentrated at unusually low frequencies. In each case, an appropriate high frequency acoustic excitation is found to be effective in reducing the fluctuations substantially. The effective excitation frequency scales on the initial boundary layer thickness and the effect is apparently achieved through acoustic tripping of the separating boundary layer.

Effects of large woody debris placement on stream channels and benthic macroinvertebrates

Treesearch

Robert H. Hilderbrand; A. Dennis Lemly; C. Andrew Dolloff; Kelly L. Harpster

1997-01-01

Large woody debris (LWD)was added as an experimental stream restoration techniquein two streams in southwest Virginia. Additions were designed to compare human judgement in log placements against a randomized design and an unmanipulated reach, &d also to compare effectiveness in a low- and a high-gradient stream. Pool area increased 146% in the systematic placement...

Effect of Audio vs. Video on Aural Discrimination of Vowels

ERIC Educational Resources Information Center

McCrocklin, Shannon

2012-01-01

Despite the growing use of media in the classroom, the effects of using of audio versus video in pronunciation teaching has been largely ignored. To analyze the impact of the use of audio or video training on aural discrimination of vowels, 61 participants (all students at a large American university) took a pre-test followed by two training…

Forest landscape models, a tool for understanding the effect of the large-scale and long-term landscape processes

Treesearch

Hong S. He; Robert E. Keane; Louis R. Iverson

2008-01-01

Forest landscape models have become important tools for understanding large-scale and long-term landscape (spatial) processes such as climate change, fire, windthrow, seed dispersal, insect outbreak, disease propagation, forest harvest, and fuel treatment, because controlled field experiments designed to study the effects of these processes are often not possible (...

The Washback Effect of Konkoor on Teachers' Attitudes toward Their Teaching

ERIC Educational Resources Information Center

Birjandi, Parviz; Shirkhani, Servat

2012-01-01

Large scale tests have been considered by many scholars in the field of language testing and teaching to influence teaching and learning considerably. The present study looks at the effect of a large scale test (Konkoor) on the attitudes of teachers in high schools. Konkoor is the university entrance examination in Iran which is taken by at least…

Nurture Groups: A Large-Scale, Controlled Study of Effects on Development and Academic Attainment

ERIC Educational Resources Information Center

Reynolds, Sue; MacKay, Tommy; Kearney, Maura

2009-01-01

Nurture groups have contributed to inclusive practices in primary schools in the UK for some time now and have frequently been the subject of articles in this journal. This large-scale, controlled study of nurture groups across 32 schools in the City of Glasgow provides further evidence for their effectiveness in addressing the emotional…

The Partially Flipped Classroom: The Effects of Flipping a Module on "Junk Science" in a Large Methods Course

ERIC Educational Resources Information Center

Burgoyne, Stephanie; Eaton, Judy

2018-01-01

Flipped classrooms are gaining popularity, especially in psychology statistics courses. However, not all courses lend themselves to a fully flipped design, and some instructors might not want to commit to flipping every class. We tested the effectiveness of flipping just one component (a module on junk science) of a large methods course. We…

Playing to Teachers' Strengths: Using Multiple Measures of Teacher Effectiveness to Improve Teacher Assignments

ERIC Educational Resources Information Center

Fox, Lindsay

2016-01-01

Current uses of value-added modeling largely ignore or assume away the potential for teachers to be more effective with one type of student than another or in one subject than another. This paper explores the stability of value-added measures across different subgroups and subjects using administrative data from a large urban school district. For…

Identification of QTL with large effect on seed weight in a selective population of soybean with genome-wide association and fixation index analyses

USDA-ARS?s Scientific Manuscript database

Our objective was to identify candidate QTL that had a large effect on seed weight using a selective population through GWAS and fixation index analysis. A selective population was previously used for the identification of QTL in linkage analysis of bi-parental RIL populations in plant species, but ...

Improving the Effectiveness and Efficiency of Teaching Large Classes: Development and Evaluation of a Novel e-Resource in Cancer Biology

ERIC Educational Resources Information Center

Hejmadi, Momna V.

2007-01-01

This paper describes the development and evaluation of a blended learning resource in the biosciences, created by combining online learning with formal face-face lectures and supported by formative assessments. In order to improve the effectiveness and efficiency of teaching large classes with mixed student cohorts, teaching was delivered through…

Intelligence Makes People Think like Economists: Evidence from the General Social Survey

ERIC Educational Resources Information Center

Caplan, Bryan; Miller, Stephen C.

2010-01-01

Education is by far the strongest predictor of whether a non-economist will share the economic beliefs of the average economist. (Caplan, 2001) Is the effect of education as large as it seems? Or is education largely a proxy for cognitive ability? Using data from the General Social Survey (GSS), we show that the estimated effect of education…

Small Changes: Using Assessment to Direct Instructional Practices in Large-Enrollment Biochemistry Courses

PubMed Central

Xu, Xiaoying; Lewis, Jennifer E.; Loertscher, Jennifer; Minderhout, Vicky; Tienson, Heather L.

2017-01-01

Multiple-choice assessments provide a straightforward way for instructors of large classes to collect data related to student understanding of key concepts at the beginning and end of a course. By tracking student performance over time, instructors receive formative feedback about their teaching and can assess the impact of instructional changes. The evidence of instructional effectiveness can in turn inform future instruction, and vice versa. In this study, we analyzed student responses on an optimized pretest and posttest administered during four different quarters in a large-enrollment biochemistry course. Student performance and the effect of instructional interventions related to three fundamental concepts—hydrogen bonding, bond energy, and pKa—were analyzed. After instructional interventions, a larger proportion of students demonstrated knowledge of these concepts compared with data collected before instructional interventions. Student responses trended from inconsistent to consistent and from incorrect to correct. The instructional effect was particularly remarkable for the later three quarters related to hydrogen bonding and bond energy. This study supports the use of multiple-choice instruments to assess the effectiveness of instructional interventions, especially in large classes, by providing instructors with quick and reliable feedback on student knowledge of each specific fundamental concept. PMID:28188280

Effect of drop size on the impact thermodynamics for supercooled large droplet in aircraft icing

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

Zhang, Chen; Liu, Hong, E-mail: hongliu@sjtu.edu.cn

Supercooled large droplet (SLD), which can cause abnormal icing, is a well-known issue in aerospace engineering. Although efforts have been exerted to understand large droplet impact dynamics and the supercooled feature in the film/substrate interface, respectively, the thermodynamic effect during the SLD impact process has not received sufficient attention. This work conducts experimental studies to determine the effects of drop size on the thermodynamics for supercooled large droplet impingement. Through phenomenological reproduction, the rapid-freezing characteristics are observed in diameters of 400, 800, and 1300 μm. The experimental analysis provides information on the maximum spreading rate and the shrinkage rate ofmore » the drop, the supercooled diffusive rate, and the freezing time. A physical explanation of this unsteady heat transfer process is proposed theoretically, which indicates that the drop size is a critical factor influencing the supercooled heat exchange and effective heat transfer duration between the film/substrate interface. On the basis of the present experimental data and theoretical analysis, an impinging heating model is developed and applied to typical SLD cases. The model behaves as anticipated, which underlines the wide applicability to SLD icing problems in related fields.« less

EASApprox® skin-stretching system: A secure and effective method to achieve wound closure.

PubMed

Song, Mingzhi; Zhang, Zhen; Liu, Tao; Liu, Song; Li, Gang; Liu, Zhaochang; Huang, Jingyang; Chen, Song; Li, Linan; Guo, Li; Qiu, Yang; Wan, Jiajia; Liu, Yuejian; Wu, Tao; Wang, Xiaoyong; Lu, Ming; Wang, Shouyu

2017-07-01

Large skin defects are commonly observed in the clinic and have attracted much attention recently. Therefore, finding an effective solution for large skin defects is a global problem. The objective of the present study was to assess the effectiveness of the EASApprox ® skin-stretching system for closing large skin defects. Skin defects (5×5 cm) were created on the forearms of 9 Bama miniature pigs, which were randomly divided into the following three groups: Direct suture, the new EASApprox ® skin-stretching device and Kirschner wires. Microcirculation was assessed before surgery and after wound closure. Following the different treatments, the defects were sutured, and wound healing was assessed based on a clinical score. Furthermore, microscopic and ultramicroscopic structures were evaluated, including collagen, elastic fibers and the microvessel density. Significant differences in the clinical score and microvessel density were observed among the groups. Additionally, the mean length obtained for elastic fibers was larger than that obtained for the other two groups. Finally, the new EASApprox ® skin-stretching device resulted in successful wound management and with only minor side effects on skin histology and microcirculation. Therefore, this method has the potential to be used for healing large skin defects.

Thermoelectric effects in superconductor-ferromagnet tunnel junctions on europium sulfide

NASA Astrophysics Data System (ADS)

Kolenda, S.; Sürgers, C.; Fischer, G.; Beckmann, D.

2017-06-01

We report on large thermoelectric effects in superconductor-ferromagnet tunnel junctions in proximity contact with the ferromagnetic insulator europium sulfide. The combination of a spin-splitting field and spin-polarized tunnel conductance in these systems breaks the electron-hole symmetry and leads to spin-dependent thermoelectric currents. We show that the exchange splitting induced by europium sulfide boosts the thermoelectric effect in small applied fields and can therefore eliminate the need to apply large magnetic fields, which might otherwise impede applications in thermometry or cooling.

Effectiveness and cost-effectiveness of telehealthcare for chronic obstructive pulmonary disease: study protocol for a cluster randomized controlled trial.

PubMed

Udsen, Flemming Witt; Lilholt, Pernille Heyckendorff; Hejlesen, Ole; Ehlers, Lars Holger

2014-05-21

Several feasibility studies show promising results of telehealthcare on health outcomes and health-related quality of life for patients suffering from chronic obstructive pulmonary disease, and some of these studies show that telehealthcare may even lower healthcare costs. However, the only large-scale trial we have so far - the Whole System Demonstrator Project in England - has raised doubts about these results since it conclude that telehealthcare as a supplement to usual care is not likely to be cost-effective compared with usual care alone. The present study is known as 'TeleCare North' in Denmark. It seeks to address these doubts by implementing a large-scale, pragmatic, cluster-randomized trial with nested economic evaluation. The purpose of the study is to assess the effectiveness and the cost-effectiveness of a telehealth solution for patients suffering from chronic obstructive pulmonary disease compared to usual practice. General practitioners will be responsible for recruiting eligible participants (1,200 participants are expected) for the trial in the geographical area of the North Denmark Region. Twenty-six municipality districts in the region define the randomization clusters. The primary outcomes are changes in health-related quality of life, and the incremental cost-effectiveness ratio measured from baseline to follow-up at 12 months. Secondary outcomes are changes in mortality and physiological indicators (diastolic and systolic blood pressure, pulse, oxygen saturation, and weight). There has been a call for large-scale clinical trials with rigorous cost-effectiveness assessments in telehealthcare research. This study is meant to improve the international evidence base for the effectiveness and cost-effectiveness of telehealthcare to patients suffering from chronic obstructive pulmonary disease by implementing a large-scale pragmatic cluster-randomized clinical trial. Clinicaltrials.gov, http://NCT01984840, November 14, 2013.

L-Arginine supplementation improves antioxidant defenses through L-arginine/nitric oxide pathways in exercised rats.

PubMed

Shan, Lingling; Wang, Bin; Gao, Guizhen; Cao, Wengen; Zhang, Yunkun

2013-10-15

l-Arginine (l-Arg) supplementation has been shown to enhance physical exercise capacity and delay onset of fatigue. This work investigated the potential beneficial mechanism(s) of l-Arg supplementation by examining its effect on the cellular oxidative and nitrosative stress pathways in the exercised rats. Forty-eight rats were randomly divided into six groups: sedentary control; sedentary control with l-Arg treatment; endurance training (daily swimming training for 8 wk) control; endurance training with l-Arg treatment; an exhaustive exercise (one time swimming to fatigue) control; and an exhaustive exercise with l-Arg treatment. l-Arg (500 mg/kg body wt) or saline was given to rats by intragastric administration 1 h before the endurance training and the exhaustive swimming test. Expression levels and activities of the l-Arg/nitric oxide (NO) pathway components and parameters of the oxidative stress and antioxidant defense capacity were investigated in l-Arg-treated and control rats. The result show that the l-Arg supplementation completely reversed the exercise-induced activation of NO synthase and superoxide dismutase, increased l-Arg transport capacity, and increased NO and anti-superoxide anion levels. These data demonstrate that l-Arg supplementation effectively reduces the exercise-induced imbalance between oxidative stress and antioxidant defense capacity, and this modulation is likely mediated through the l-Arg/NO pathways. The findings of this study improved our understanding of how l-Arg supplementation prevents elevations of reactive oxygen species and favorably enhances the antioxidant defense capacity during physical exercise.

Large thermopower from dressed quasiparticles in the layered cobaltates and rhodates

DOE PAGES

Chen, Su-Di; He, Yu; Zong, Alfred; ...

2017-08-15

The origin of the large thermopower in Na x CoO 2 is complicated by correlation phenomena. To disentangle the effects from multiple interactions, we use angle-resolved photoemission to study K x RhO 2, an isostructural analogy of Na xCoO 2 with large thermopower and weak electron correlation. In using the experimentally measured electronic structure, we demonstrate that the thermopower in K xRhO 2 can be quantitatively explained within the quasiparticle framework after including an electron-phonon mass enhancement effect. Extending the analysis to the cobaltate, we find the doubling in thermopower is well accounted for by additional band renormalization frommore » electron correlation. Thus, the large thermopower emerges from the itinerant quasiparticles dressed by hierarchical electron-phonon and electron-electron interactions.« less

The effect of the geomagnetic field on cosmic ray energy estimates and large scale anisotropy searches on data from the Pierre Auger Observatory

NASA Astrophysics Data System (ADS)

Pierre Auger Collaboration; Abreu, P.; Aglietta, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antičić, T.; Anzalone, A.; Aramo, C.; Arganda, E.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Bäcker, T.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Bardenet, R.; Barroso, S. L. C.; Baughman, B.; Bäuml, J.; Beatty, J. J.; Becker, B. R.; Becker, K. H.; Bellétoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Caballero-Mora, K. S.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chudoba, J.; Clay, R. W.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; Decerprit, G.; del Peral, L.; del Río, M.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Fajardo Tapia, I.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Ferrero, A.; Fick, B.; Filevich, A.; Filipčič, A.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fröhlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; García, B.; García Gámez, D.; Garcia-Pinto, D.; Gascon, A.; Gemmeke, H.; Gesterling, K.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gonçalves, P.; Gonzalez, D.; Gonzalez, J. G.; Gookin, B.; Góra, D.; Gorgi, A.; Gouffon, P.; Gozzini, S. R.; Grashorn, E.; Grebe, S.; Griffith, N.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Guzman, A.; Hague, J. D.; Hansen, P.; Harari, D.; Harmsma, S.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Hollon, N.; Holmes, V. C.; Homola, P.; Hörandel, J. R.; Horneffer, A.; Horvath, P.; Hrabovský, M.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jarne, C.; Jiraskova, S.; Josebachuili, M.; Kadija, K.; Kampert, K. H.; Karhan, P.; Kasper, P.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kelley, J. L.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D.-H.; Kotera, K.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuehn, F.; Kuempel, D.; Kulbartz, J. K.; Kunka, N.; La Rosa, G.; Lachaud, C.; Lautridou, P.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Lemiere, A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, J.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Mertsch, P.; Meurer, C.; Mićanović, S.; Micheletti, M. I.; Miller, W.; Miramonti, L.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Morris, C.; Mostafá, M.; Moura, C. A.; Mueller, S.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niemietz, L.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nožka, L.; Nyklicek, M.; Oehlschläger, J.; Olinto, A.; Oliva, P.; Olmos-Gilbaja, V. M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Parsons, R. D.; Pastor, S.; Paul, T.; Pech, M.; Pękala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Petrovic, J.; Pfendner, C.; Phan, N.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Ponce, V. H.; Pontz, M.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Robledo, C.; Rodrigues de Carvalho, W.; Rodriguez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Cabo, I.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Rühle, C.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Schmidt, F.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovánek, P.; Schröder, F.; Schulte, S.; Schuster, D.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Silva Lopez, H. H.; Śacute; Smiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Stanic, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tamashiro, A.; Tapia, A.; Tartare, M.; Taşąu, O.; Tavera Ruiz, C. G.; Tcaciuc, R.; Tegolo, D.; Thao, N. T.; Thomas, D.; Tiffenberg, J.; Timmermans, C.; Tiwari, D. K.; Tkaczyk, W.; Todero Peixoto, C. J.; Tomé, B.; Tonachini, A.; Travnicek, P.; Tridapalli, D. B.; Tristram, G.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van den Berg, A. M.; Varela, E.; Vargas Cárdenas, B.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Warner, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Westerhoff, S.; Whelan, B. J.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Winnick, M. G.; Wommer, M.; Wundheiler, B.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zimbres Silva, M.; Ziolkowski, M.

2011-11-01

We present a comprehensive study of the influence of the geomagnetic field on the energy estimation of extensive air showers with a zenith angle smaller than 60°, detected at the Pierre Auger Observatory. The geomagnetic field induces an azimuthal modulation of the estimated energy of cosmic rays up to the ~ 2% level at large zenith angles. We present a method to account for this modulation of the reconstructed energy. We analyse the effect of the modulation on large scale anisotropy searches in the arrival direction distributions of cosmic rays. At a given energy, the geomagnetic effect is shown to induce a pseudo-dipolar pattern at the percent level in the declination distribution that needs to be accounted for.

Over-Water Aspects of Ground-Effect Vehicles

NASA Technical Reports Server (NTRS)

Kuhn, Richard E.; Carter, Arthur W.; Schade, Robert O.

1960-01-01

The large thrust augmentation obtainable with annular-jet configurations in ground proximity has led to the serious investigation of ground-effect machines. The basic theoretical work on these phenomena has been done by Chaplin and Boehler. Large thrust-augmentation factors, however, can be obtained only at very low heights, that is, of the order of a few percent of the diameter of the vehicle. To take advantage of this thrust augmentation therefore the vehicle must be either very large or must operate over very smooth terrain. Over-land uses of these vehicles then will probably be rather limited. The water, however, is inherently smooth and those irregularities that do exist, that is waves, are statistically known. It appears therefore that some practical application of ground-effect machines may be made in over-water application.

Implementing Summative Assessment with a Formative Flavour: A Case Study in a Large Class

ERIC Educational Resources Information Center

Broadbent, Jaclyn; Panadero, Ernesto; Boud, David

2018-01-01

Teaching a large class can present real challenges in design, management and standardisation of assessment practices. One of the main dilemmas for university teachers is how to implement effective formative assessment practices with accompanying high-quality feedback consistently over time with large classroom groups. This article reports on how…

Spatially explicit shallow landslide susceptibility mapping over large areas

Treesearch

Dino Bellugi; William E. Dietrich; Jonathan Stock; Jim McKean; Brian Kazian; Paul Hargrove

2011-01-01

Recent advances in downscaling climate model precipitation predictions now yield spatially explicit patterns of rainfall that could be used to estimate shallow landslide susceptibility over large areas. In California, the United States Geological Survey is exploring community emergency response to the possible effects of a very large simulated storm event and to do so...

Large Space Systems/Low-Thrust Propulsion Technology

NASA Technical Reports Server (NTRS)

1980-01-01

The potentially critical interactions that occur between propulsion, structures and materials, and controls for large spacecraft are considered, the technology impacts within these fields are defined and the net effect on large systems and the resulting missions is determined. Topical areas are systems/mission analysis, LSS static and dynamic characterization, and propulsion systems characterization.

Large Groups in the Boundary Waters Canoe Area - Their Numbers, Characteristics, and Impact

Treesearch

David W. Lime

1972-01-01

The impact of "large" parties in the BWCA is discussed in terms of their effect on the resource and on the experience of other visitors. The amount of use by large groups and the visitors most likely to be affected by a reduction in party size limit are described.

SCALE(ing)-UP Teaching: A Case Study of Student Motivation in an Undergraduate Course

ERIC Educational Resources Information Center

Chittum, Jessica R.; McConnell, Kathryne Drezek; Sible, Jill

2017-01-01

Teaching large classes is increasingly common; thus, demand for effective large-class pedagogy is rising. One method, titled "SCALE-UP" (Student-Centered Active Learning Environment for Undergraduate Programs), is intended for large classes and involves collaborative, active learning in a technology-rich and student-centered environment.…

Observations of Radar Backscatter at Ku and C Bands in the Presence of Large Waves during the Surface Wave Dynamics Experiment

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Li, Fuk K.; Lou, Shu-Hsiang; Neumann, Gregory; McIntosh, Robert E.; Carson, Steven C.; Carswell, James R.; Walsh, Edward J.; Donelan, Mark A.; Drennan, William M.

1995-01-01

Ocean radar backscatter in the presence of large waves is investigated using data acquired with the Jet Propulsion Laboratory NUSCAT radar at Ku band for horizontal and vertical polarizations and the University of Massachusetts CSCAT radar at C band for vertical polarization during the Surface Wave Dynamics Experiment. Off-nadir backscatter data of ocean surfaces were obtained in the presence of large waves with significant wave height up to 5.6 m. In moderate-wind cases, effects of large waves are not detectable within the measurement uncertainty and no noticeable correlation between backscatter coefficients and wave height is found. Under high-wave light-wind conditions, backscatter is enhanced significantly at large incidence angles with a weaker effect at small incidence angles. Backscatter coefficients in the wind speed range under consideration are compared with SASS-2 (Ku band), CMOD3-H1 (C band), and Plant's model results which confirm the experimental observations. Variations of the friction velocity, which can give rise to the observed backscatter behaviors in the presence of large waves, are presented.

Large Electro-Optic Kerr Effect in Ionic Liquid Crystals: Connecting Features of Liquid Crystals and Polyelectrolytes.

PubMed

Schlick, M Christian; Kapernaum, Nadia; Neidhardt, Manuel M; Wöhrle, Tobias; Stöckl, Yannick; Laschat, Sabine; Giesselmann, Frank

2018-06-06

The electro-optic Kerr effect in simple dipolar fluids such as nitrobenzene has been widely applied in electro-optical phase modulators and light shutters. In 2005, the discovery of the large Kerr effect in liquid-crystalline blue phases (Y. Hisakado et al., Adv. Mater. 2005, 17, 96-98.) gave new directions to the search for advanced Kerr effect materials. Even though the Kerr effect is present in all transparent and optically isotropic media, it is well known that the effect can be anomalously large in complex fluids, namely in the isotropic phase of liquid crystals or in polyelectrolyte solutions. Herein, it is shown that the Kerr effect in the isotropic phase of ionic liquid crystals combines the effective counterion polarization mechanism found in polyelectrolytes and the unique pretransitional growth of the Kerr constant found in the isotropic phase of nematic liquid crystals. Maximum Kerr constants in the order of several 10 -11  m V -2 (ten times higher than the Kerr constant of the toxic nitrobenzene and less temperature sensitive than Kerr constants of nematic liquid crystals) make ionic liquid crystals attractive as new class of functional materials in low-speed Kerr effect applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effective constitutive relations for large repetitive frame-like structures

NASA Technical Reports Server (NTRS)

Nayfeh, A. H.; Hefzy, M. S.

1981-01-01

Effective mechanical properties for large repetitive framelike structures are derived using combinations of strength of material and orthogonal transformation techniques. Symmetry considerations are used in order to identify independent property constants. The actual values of these constants are constructed according to a building block format which is carried out in the three consecutive steps: (1) all basic planar lattices are identified; (2) effective continuum properties are derived for each of these planar basic grids using matrix structural analysis methods; and (3) orthogonal transformations are used to determine the contribution of each basic set to the overall effective continuum properties of the structure.

Thinking outside the box: effects of modes larger than the survey on matter power spectrum covariance

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

Putter, Roland de; Wagner, Christian; Verde, Licia

2012-04-01

Accurate power spectrum (or correlation function) covariance matrices are a crucial requirement for cosmological parameter estimation from large scale structure surveys. In order to minimize reliance on computationally expensive mock catalogs, it is important to have a solid analytic understanding of the different components that make up a covariance matrix. Considering the matter power spectrum covariance matrix, it has recently been found that there is a potentially dominant effect on mildly non-linear scales due to power in modes of size equal to and larger than the survey volume. This beat coupling effect has been derived analytically in perturbation theory andmore » while it has been tested with simulations, some questions remain unanswered. Moreover, there is an additional effect of these large modes, which has so far not been included in analytic studies, namely the effect on the estimated average density which enters the power spectrum estimate. In this article, we work out analytic, perturbation theory based expressions including both the beat coupling and this local average effect and we show that while, when isolated, beat coupling indeed causes large excess covariance in agreement with the literature, in a realistic scenario this is compensated almost entirely by the local average effect, leaving only ∼ 10% of the excess. We test our analytic expressions by comparison to a suite of large N-body simulations, using both full simulation boxes and subboxes thereof to study cases without beat coupling, with beat coupling and with both beat coupling and the local average effect. For the variances, we find excellent agreement with the analytic expressions for k < 0.2 hMpc{sup −1} at z = 0.5, while the correlation coefficients agree to beyond k = 0.4 hMpc{sup −1}. As expected, the range of agreement increases towards higher redshift and decreases slightly towards z = 0. We finish by including the large-mode effects in a full covariance matrix description for arbitrary survey geometry and confirming its validity using simulations. This may be useful as a stepping stone towards building an actual galaxy (or other tracer's) power spectrum covariance matrix.« less

Gravitational lenses and large scale structure

NASA Technical Reports Server (NTRS)

Turner, Edwin L.

1987-01-01

Four possible statistical tests of the large scale distribution of cosmic material are described. Each is based on gravitational lensing effects. The current observational status of these tests is also summarized.

Large-scale bioenergy production: how to resolve sustainability trade-offs?

NASA Astrophysics Data System (ADS)

Humpenöder, Florian; Popp, Alexander; Bodirsky, Benjamin Leon; Weindl, Isabelle; Biewald, Anne; Lotze-Campen, Hermann; Dietrich, Jan Philipp; Klein, David; Kreidenweis, Ulrich; Müller, Christoph; Rolinski, Susanne; Stevanovic, Miodrag

2018-02-01

Large-scale 2nd generation bioenergy deployment is a key element of 1.5 °C and 2 °C transformation pathways. However, large-scale bioenergy production might have negative sustainability implications and thus may conflict with the Sustainable Development Goal (SDG) agenda. Here, we carry out a multi-criteria sustainability assessment of large-scale bioenergy crop production throughout the 21st century (300 EJ in 2100) using a global land-use model. Our analysis indicates that large-scale bioenergy production without complementary measures results in negative effects on the following sustainability indicators: deforestation, CO2 emissions from land-use change, nitrogen losses, unsustainable water withdrawals and food prices. One of our main findings is that single-sector environmental protection measures next to large-scale bioenergy production are prone to involve trade-offs among these sustainability indicators—at least in the absence of more efficient land or water resource use. For instance, if bioenergy production is accompanied by forest protection, deforestation and associated emissions (SDGs 13 and 15) decline substantially whereas food prices (SDG 2) increase. However, our study also shows that this trade-off strongly depends on the development of future food demand. In contrast to environmental protection measures, we find that agricultural intensification lowers some side-effects of bioenergy production substantially (SDGs 13 and 15) without generating new trade-offs—at least among the sustainability indicators considered here. Moreover, our results indicate that a combination of forest and water protection schemes, improved fertilization efficiency, and agricultural intensification would reduce the side-effects of bioenergy production most comprehensively. However, although our study includes more sustainability indicators than previous studies on bioenergy side-effects, our study represents only a small subset of all indicators relevant for the SDG agenda. Based on this, we argue that the development of policies for regulating externalities of large-scale bioenergy production should rely on broad sustainability assessments to discover potential trade-offs with the SDG agenda before implementation.

Effects of wildlife and cattle on tick abundance in central Kenya.

PubMed

Keesing, Felicia; Allan, Brian F; Young, Truman P; Ostfeld, Richard S

2013-09-01

In African savannas, large mammals, both wild and domestic, support an abundant and diverse population of tick ectoparasites. Because of the density of ticks and the many pathogens that they vector, cattle in East Africa are often treated with acaricides. While acaricides are known to be effective at reducing tick burdens on cattle, their effects on the overall abundance and community composition of ticks in savanna ecosystems are less well understood. It is also not known how well tick populations can be maintained in the absence of large mammals. We evaluated the effects of wildlife and of acaricide-treated cattle on host-seeking tick populations in a long-term, exclusion experiment in central Kenya. Over seven years, we sampled larval, nymphal, and adult ticks monthly on replicated treatment plots that controlled for the presence of cattle and for the presence of two guilds of large wild mammals: megaherbivores (giraffes and elephants) and all other large wild herbivores (> 15 kg). Two species of ticks were found in this habitat; across all surveys, 93% were Rhipicephalus pulchellus and 7% were R. praetextatus. The presence of acaricide-treated cattle dramatically reduced the abundance of host-seeking nymphal and adult ticks but did not affect the abundance of host-seeking larval ticks. The abundance of larval ticks was determined by the presence of large wild mammals, which appear to import gravid female ticks into the experimental plots. On plots with no large mammals, either wild or domestic, larval and nymphal ticks were rare. Adult R. pulchellus were most abundant in plots that allowed wildlife but excluded cattle. Adult R. praetextatus were relatively abundant in plots without any large mammals. These differences suggest that these ticks utilize different members of the host community. The reduction in ticks that results from the presence of acaricide-treated cattle has potential health benefits for humans and wildlife, but these benefits must be weighed against potential costs, including reduced availability of food for birds such as oxpeckers that feed on ticks.

Word length, set size, and lexical factors: Re-examining what causes the word length effect.

PubMed

Guitard, Dominic; Gabel, Andrew J; Saint-Aubin, Jean; Surprenant, Aimée M; Neath, Ian

2018-04-19

The word length effect, better recall of lists of short (fewer syllables) than long (more syllables) words has been termed a benchmark effect of working memory. Despite this, experiments on the word length effect can yield quite different results depending on set size and stimulus properties. Seven experiments are reported that address these 2 issues. Experiment 1 replicated the finding of a preserved word length effect under concurrent articulation for large stimulus sets, which contrasts with the abolition of the word length effect by concurrent articulation for small stimulus sets. Experiment 2, however, demonstrated that when the short and long words are equated on more dimensions, concurrent articulation abolishes the word length effect for large stimulus sets. Experiment 3 shows a standard word length effect when output time is equated, but Experiments 4-6 show no word length effect when short and long words are equated on increasingly more dimensions that previous demonstrations have overlooked. Finally, Experiment 7 compared recall of a small and large neighborhood words that were equated on all the dimensions used in Experiment 6 (except for those directly related to neighborhood size) and a neighborhood size effect was still observed. We conclude that lexical factors, rather than word length per se, are better predictors of when the word length effect will occur. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Large bipolarons and oxide superconductivity

NASA Astrophysics Data System (ADS)

Emin, David

2017-02-01

Large-bipolaron superconductivity is plausible with carrier densities well below those of conventional metals. Bipolarons form when carriers self-trap in pairs. Coherently moving large-bipolarons require extremely large ratios of static to optical dielectric-constants. The mutual Coulomb repulsion of a planar large-bipolaron's paired carriers drives it to a four-lobed shape. A phonon-mediated attraction among large-bipolarons propels their condensation into a liquid. This liquid's excitations move slowly with a huge effective mass. Excitations' concomitant weak scattering by phonons produces a moderate low-temperature dc resistivity that increases linearly with rising temperature. With falling temperature an energy gap opens between large-bipolarons' excitations and those of their self-trapped electronic carriers.

A control approach to cross-coupling compensation of piezotube scanners in tapping-mode atomic force microscope imaging.

PubMed

Wu, Ying; Shi, Jian; Su, Chanmin; Zou, Qingze

2009-04-01

In this article, an approach based on the recently developed inversion-based iterative control (IIC) to cancel the cross-axis coupling effect of piezoelectric tube scanners (piezoscanners) in tapping-mode atomic force microscope (AFM) imaging is proposed. Cross-axis coupling effect generally exists in piezoscanners used for three-dimensional (x-y-z axes) nanopositioning in applications such as AFM, where the vertical z-axis movement can be generated by the lateral x-y axes scanning. Such x/y-to-z cross-coupling becomes pronounced when the scanning is at large range and/or at high speed. In AFM applications, the coupling-caused position errors, when large, can generate various adverse effects, including large imaging and topography distortions, and damage of the cantilever probe and/or the sample. This paper utilizes the IIC technique to obtain the control input to precisely track the coupling-caused x/y-to-z displacement (with sign-flipped). Then the obtained input is augmented as a feedforward control to the existing feedback control in tapping-mode imaging, resulting in the cancellation of the coupling effect. The proposed approach is illustrated through two exemplary applications in industry, the pole-tip recession examination, and the nanoasperity measurement on hard-disk drive. Experimental results show that the x/y-to-z coupling effect in large-range (20 and 45 microm) tapping-mode imaging at both low to high scan rates (2, 12.2 to 24.4 Hz) can be effectively removed.

Jackpot Structural Features: Rollover Effect and Goal-Gradient Effect in EGM Gambling.

PubMed

Li, En; Rockloff, Matthew J; Browne, Matthew; Donaldson, Phillip

2016-06-01

Relatively little research has been undertaken on the influence of jackpot structural features on electronic gaming machine (EGM) gambling behavior. This study considered two common features of EGM jackpots: progressive (i.e., the jackpot incrementally growing in value as players make additional bets), and deterministic (i.e., a guaranteed jackpot after a fixed number of bets, which is determined in advance and at random). Their joint influences on player betting behavior and the moderating role of jackpot size were investigated in a crossed-design experiment. Using real money, players gambled on a computer simulated EGM with real jackpot prizes of either $500 (i.e., small jackpot) or $25,000 (i.e., large jackpot). The results revealed three important findings. Firstly, players placed the largest bets (20.3 % higher than the average) on large jackpot EGMs that were represented to be deterministic and non-progressive. This finding was supportive of a hypothesized 'goal-gradient effect', whereby players might have felt subjectively close to an inevitable payoff for a high-value prize. Secondly, large jackpots that were non-deterministic and progressive also promoted high bet sizes (17.8 % higher than the average), resembling the 'rollover effect' demonstrated in lottery betting, whereby players might imagine that their large bets could be later recouped through a big win. Lastly, neither the hypothesized goal-gradient effect nor the rollover effect was evident among players betting on small jackpot machines. These findings suggest that certain high-value jackpot configurations may have intensifying effects on player behavior.

The Impact of Instructional Design on College Students' Cognitive Load and Learning Outcomes in a Large Food Science and Human Nutrition Course

ERIC Educational Resources Information Center

Andrade, Jeanette; Huang, Wen-Hao David; Bohn, Dawn M.

2015-01-01

The effective design of course materials is critical for student learning, especially for large lecture introductory courses. This quantitative study was designed to explore the effect multimedia and content difficulty has on students' cognitive load and learning outcomes. College students (n = 268) were randomized into 1 of 3 multimedia groups:…

An Exploration of the Effects of a Literature-Based Socialemotional Learning Curriculum on the Kindergarten Classes in a Large K-5 Elementary School

ERIC Educational Resources Information Center

Werkheiser, Susan N. Gravle

2014-01-01

The purpose of this case study was to explore the effects of a literature-based social-emotional learning curriculum on kindergarten students' social-emotional behaviors, awareness, and early reading skills in a large elementary school. The study examined beliefs/perceptions of kindergarten teachers in regards to what reading skills students…

The Impact of Effective Scheduling on the Climate and Culture in a Large Comprehensive High School

ERIC Educational Resources Information Center

Hayes, Matthew

2013-01-01

Scheduling in any school or organization plays a vital role in the effectiveness that stakeholders' needs are met. The administration at a large comprehensive high school in the Charlotte Mecklenburg School District realized that in order for their school to meet the changing needs of its student body, it had to build a culture and climate that…

The Effects of Group Relaxation Training/Large Muscle Exercise, and Parental Involvement on Attention to Task, Impulsivity, and Locus of Control among Hyperactive Boys.

ERIC Educational Resources Information Center

Porter, Sally S.; Omizo, Michael M.

1984-01-01

The study examined the effects of group relaxation training/large muscle exercise and parental involvement on attention to task, impulsivity, and locus of control among 34 hyperactive boys. Following treatment both experimental groups recorded significantly higher attention to task, lower impulsivity, and lower locus of control scores. (Author/CL)

Differential effects of co-administration of oxotremorine with SCH 23390 on impulsive choice in high-impulsive rats and low-impulsive rats.

PubMed

Tian, Lin; Qin, Xingna; Sun, Jinling; Li, Xinwang; Wei, Li

2016-03-01

The effect of acetylcholine on impulsive choice is thought to be due to interactions between cholinergic and dopaminergic systems, but this hypothesis has not been proven. This study investigated whether D1-like receptors were involved in the effects of the muscarinic cholinergic agonist oxotremorine on impulsive choice in high-impulsive rats (HI rats, n=8) and low-impulsive rats (LI rats, n=8) characterized by basal levels of impulsive choice in a delay-discounting task. The results revealed that oxotremorine (0.05mg/kg) significantly increased the choice of the large reinforcer in HI rats, whereas decreased the choice of the large reinforcer in LI rats. The D1-like antagonist SCH 23390 produced significant reductions in the large-reinforcer choice in HI rats (0.01mg/kg) and LI rats (0.005, 0.0075, and 0.01mg/kg). SCH 23390 significantly inhibited the increase in the choice of the large reinforcer induced by oxotremorine (0.05mg/kg) in HI rats at doses of 0.005 and 0.0075mg/kg, but enhanced the effect of oxotremorine in LI rats only at the dose of 0.0075mg/kg. These findings suggested that D1-like receptors might be involved in the differential effects of oxotremorine on impulsive choice between HI rats and LI rats. Copyright © 2016 Elsevier Inc. All rights reserved.

Association between Firearm Laws and Homicide in Urban Counties.

PubMed

Crifasi, Cassandra K; Merrill-Francis, Molly; McCourt, Alex; Vernick, Jon S; Wintemute, Garen J; Webster, Daniel W

2018-05-21

Laws related to the sale, use, and carrying of firearms have been associated with differences in firearm homicide rates at the state level. Right-to-carry (RTC) and stand your ground (SYG) laws are associated with increases in firearm homicide; permit-to-purchase (PTP) laws and those prohibiting individuals convicted of violent misdemeanors (VM) have been associated with decreases in firearm homicide. Evidence for the effect of comprehensive background checks (CBC) not tied to PTP is inconclusive. Because firearm homicide tends to concentrate in urban areas, this study was designed to test the effects of firearm laws on homicide in large, urban U.S. counties. We conducted a longitudinal study using an interrupted time series design to evaluate the effect of firearm laws on homicide in large, urban U.S. counties from 1984 to 2015 (N = 136). We used mixed effects Poisson regression models with random intercepts for counties and year fixed effects to account for national trends. Models also included county and state characteristics associated with violence. Homicide was stratified by firearm versus all other methods to test for specificity of the laws' effects. PTP laws were associated with a 14% reduction in firearm homicide in large, urban counties (IRR = 0.86, 95% CI 0.82-0.90). CBC-only, SYG, RTC, and VM laws were all associated with increases in firearm homicide. None of the laws were associated with differences in non-firearm homicide rates. These findings are consistent with prior research at the state level showing PTP laws are associated with decreased firearm homicide. Testing the effects of PTP laws specifically in large, urban counties strengthens available evidence by isolating the effects in the geographic locations in which firearm homicides concentrate.

Local and Long-Distance Effects of Land Use Change on Nutrient Levels in Streams and Rivers of the Conterminous United States

NASA Astrophysics Data System (ADS)

Smith, R. A.; Alexander, R. B.; Schwarz, G. E.

2003-12-01

Determining the effects of land use change (e.g. urbanization, deforestation) on water quality at large spatial scales has been difficult because water quality measurements in large rivers with heterogeneous basins show the integrated effects of multiple factors. Moreover, the observed effects of land use changes on water quality in small homogeneous stream basins may not be indicative of downstream effects (including effects on such ecologically relevant characteristics as nutrient levels and elemental ratios) because of loss processes occurring during downstream transport in river channels. In this study we used the USGS SPARROW (Spatially-Referenced Regression on Watersheds) models of total nitrogen (TN) and total phosphorus (TP) in streams and rivers of the conterminous US to examine the effects of various aspects of land use change on nutrient concentrations and flux from the pre-development era to the present. The models were calibrated with data from 370 long-term monitoring stations representing a wide range of basin sizes, land use/cover classes, climates, and physiographies. The non-linear formulation for each model includes 20+ statistically estimated parameters relating to land use/cover characteristics and other environmental variables such as temperature, soil conditions, hill slope, and the hydraulic characteristics of 2200 large lakes and reservoirs. Model predictions are available for 62,000 river/stream channel nodes. Model predictions of pre-development water quality compare favorably with nutrient data from 63 undeveloped (reference) sites. Error statistics are available for predictions at all nodes. Model simulations were chosen to compare the effects of selected aspects of land use change on nutrient levels at large and small basin scales, lacustrine and coastal receiving waters, and among the major US geographic regions.

Similar frequency of the McGurk effect in large samples of native Mandarin Chinese and American English speakers.

PubMed

Magnotti, John F; Basu Mallick, Debshila; Feng, Guo; Zhou, Bin; Zhou, Wen; Beauchamp, Michael S

2015-09-01

Humans combine visual information from mouth movements with auditory information from the voice to recognize speech. A common method for assessing multisensory speech perception is the McGurk effect: When presented with particular pairings of incongruent auditory and visual speech syllables (e.g., the auditory speech sounds for "ba" dubbed onto the visual mouth movements for "ga"), individuals perceive a third syllable, distinct from the auditory and visual components. Chinese and American cultures differ in the prevalence of direct facial gaze and in the auditory structure of their languages, raising the possibility of cultural- and language-related group differences in the McGurk effect. There is no consensus in the literature about the existence of these group differences, with some studies reporting less McGurk effect in native Mandarin Chinese speakers than in English speakers and others reporting no difference. However, these studies sampled small numbers of participants tested with a small number of stimuli. Therefore, we collected data on the McGurk effect from large samples of Mandarin-speaking individuals from China and English-speaking individuals from the USA (total n = 307) viewing nine different stimuli. Averaged across participants and stimuli, we found similar frequencies of the McGurk effect between Chinese and American participants (48 vs. 44 %). In both groups, we observed a large range of frequencies both across participants (range from 0 to 100 %) and stimuli (15 to 83 %) with the main effect of culture and language accounting for only 0.3 % of the variance in the data. High individual variability in perception of the McGurk effect necessitates the use of large sample sizes to accurately estimate group differences.

Contrasting Effects of Errorless Naming Treatment and Gestural Facilitation for Word Retrieval in Aphasia

PubMed Central

Raymer, Anastasia M.; McHose, Beth; Smith, Kimberly G.; Iman, Lisa; Ambrose, Alexis; Casselton, Colleen

2011-01-01

Purpose We compared the effects of two treatments for aphasic word retrieval impairments, errorless naming treatment (ENT) and gestural facilitation of naming (GES), within the same individuals, anticipating that the use of gesture would enhance the effect of treatment over errorless treatment alone. In addition to picture naming, we evaluated results for other outcome measures that were largely untested in earlier ENT studies. Methods In a single participant crossover treatment design, we examined the effects of ENT and GES in eight individuals with stroke-induced aphasia and word retrieval impairments (three semantic anomia, five phonologic anomia) in counterbalanced phases across participants. We evaluated effects of the two treatments for a daily picture naming/gesture production probe measure and in standardized aphasia tests and communication rating scales administered across phases of the experiment. Results Both treatments led to improvements in naming of trained words (small-to-large effect sizes) in individuals with semantic and phonologic anomia. Small generalized naming improvements were noted for three individuals with phonologic anomia. GES improved use of corresponding gestures for trained words (large effect sizes). Results were largely maintained at one month post treatment completion. Increases in scores on standardized aphasia testing also occurred for both ENT and GES training. Discussion Both ENT and GES led to improvements in naming measures, with no clear difference between treatments. Increased use of gestures following GES providing a potential compensatory means of communication for those who did not improve verbal skills. Both treatments are considered to be effective methods to promote recovery of word retrieval and verbal production skills in individuals with aphasia. PMID:22047100

Power of mental health nursing research: a statistical analysis of studies in the International Journal of Mental Health Nursing.

PubMed

Gaskin, Cadeyrn J; Happell, Brenda

2013-02-01

Having sufficient power to detect effect sizes of an expected magnitude is a core consideration when designing studies in which inferential statistics will be used. The main aim of this study was to investigate the statistical power in studies published in the International Journal of Mental Health Nursing. From volumes 19 (2010) and 20 (2011) of the journal, studies were analysed for their power to detect small, medium, and large effect sizes, according to Cohen's guidelines. The power of the 23 studies included in this review to detect small, medium, and large effects was 0.34, 0.79, and 0.94, respectively. In 90% of papers, no adjustments for experiment-wise error were reported. With a median of nine inferential tests per paper, the mean experiment-wise error rate was 0.51. A priori power analyses were only reported in 17% of studies. Although effect sizes for correlations and regressions were routinely reported, effect sizes for other tests (χ(2)-tests, t-tests, ANOVA/MANOVA) were largely absent from the papers. All types of effect sizes were infrequently interpreted. Researchers are strongly encouraged to conduct power analyses when designing studies, and to avoid scattergun approaches to data analysis (i.e. undertaking large numbers of tests in the hope of finding 'significant' results). Because reviewing effect sizes is essential for determining the clinical significance of study findings, researchers would better serve the field of mental health nursing if they reported and interpreted effect sizes. © 2012 The Authors. International Journal of Mental Health Nursing © 2012 Australian College of Mental Health Nurses Inc.

A compact large-format streak tube for imaging lidar

NASA Astrophysics Data System (ADS)

Hui, Dandan; Luo, Duan; Tian, Liping; Lu, Yu; Chen, Ping; Wang, Junfeng; Sai, Xiaofeng; Wen, Wenlong; Wang, Xing; Xin, Liwei; Zhao, Wei; Tian, Jinshou

2018-04-01

The streak tubes with a large effective photocathode area, large effective phosphor screen area, and high photocathode radiant sensitivity are essential for improving the field of view, depth of field, and detectable range of the multiple-slit streak tube imaging lidar. In this paper, a high spatial resolution, large photocathode area, and compact meshless streak tube with a spherically curved cathode and screen is designed and tested. Its spatial resolution reaches 20 lp/mm over the entire Φ28 mm photocathode working area, and the simulated physical temporal resolution is better than 30 ps. The temporal distortion in our large-format streak tube, which is shown to be a non-negligible factor, has a minimum value as the radius of curvature of the photocathode varies. Furthermore, the photocathode radiant sensitivity and radiant power gain reach 41 mA/W and 18.4 at the wavelength of 550 nm, respectively. Most importantly, the external dimensions of our streak tube are no more than Φ60 mm × 110 mm.

Unveiling adaptation using high-resolution lineage tracking

NASA Astrophysics Data System (ADS)

Blundell, Jamie; Levy, Sasha; Fisher, Daniel; Petrov, Dmitri; Sherlock, Gavin

2013-03-01

Human diseases such as cancer and microbial infections are adaptive processes inside the human body with enormous population sizes: between 106 -1012 cells. In spite of this our understanding of adaptation in large populations is limited. The key problem is the difficulty in identifying anything more than a handful of rare, large-effect beneficial mutations. The development and use of molecular barcodes allows us to uniquely tag hundreds of thousands of cells and enable us to track tens of thousands of adaptive mutations in large yeast populations. We use this system to test some of the key theories on which our understanding of adaptation in large populations is based. We (i) measure the fitness distribution in an evolving population at different times, (ii) identify when an appreciable fraction of clones in the population have at most a single adaptive mutation and isolate a large number of clones with independent single adaptive mutations, and (iii) use this clone collection to determine the distribution of fitness effects of single beneficial mutations.

Are Social Networking Sites Making Health Behavior Change Interventions More Effective? A Meta-Analytic Review.

PubMed

Yang, Qinghua

2017-03-01

The increasing popularity of social networking sites (SNSs) has drawn scholarly attention in recent years, and a large amount of efforts have been made in applying SNSs to health behavior change interventions. However, these interventions showed mixed results, with a large variance of effect sizes in Cohen's d ranging from -1.17 to 1.28. To provide a better understanding of SNS-based interventions' effectiveness, a meta-analysis of 21 studies examining the effects of health interventions using SNS was conducted. Results indicated that health behavior change interventions using SNS are effective in general, but the effects were moderated by health topic, methodological features, and participant features. Theoretical and practical implications of findings are discussed.

The effects of exercise on muscle strength, body composition, physical functioning and the inflammatory profile of older adults: a systematic review.

PubMed

Liberman, Keliane; Forti, Louis N; Beyer, Ingo; Bautmans, Ivan

2017-01-01

This systematic review reports the most recent literature regarding the effects of physical exercise on muscle strength, body composition, physical functioning and inflammation in older adults. All articles were assessed for methodological quality and where possible effect size was calculated. Thirty-four articles were included - four involving frail, 24 healthy and five older adults with a specific disease. One reported on both frail and nonfrail patients. Several types of exercise were used: resistance training, aerobic training, combined resistance training and aerobic training and others. In frail older persons, moderate-to-large beneficial exercise effects were noted on inflammation, muscle strength and physical functioning. In healthy older persons, effects of resistance training (most frequently investigated) on inflammation or muscle strength can be influenced by the exercise modalities (intensity and rest interval between sets). Muscle strength seemed the most frequently used outcome measure, with moderate-to-large effects obtained regardless the exercise intervention studied. Similar effects were found in patients with specific diseases. Exercise has moderate-to-large effects on muscle strength, body composition, physical functioning and inflammation in older adults. Future studies should focus on the influence of specific exercise modalities and target the frail population more.

[The protective effect of XD in ConA-induced liver injury].

PubMed

Liu, Xiao-Bin; Wang, Jing; Zhang, Qian-Qian; Liu, Tao; Dang, Tong-Mei; Cao, Yi-Ming

2010-12-01

To explore the protective effect and its mechanism of Modified Xiaochaihu decoction(MXD) in the liver injury of mice. METHORDS: Using Reitman methord to examine serum ALT and ATS; Using sandwich enzyme immunoassay ABC-ELISA to examine serum TNF-α and IFN-γ. Serum ALT and ATS of MXD large dose group and Xiaochaihu decoction (XD )group were lower than that of animal models group, there was significant difference among groups (P<0.05). There were not significant difference (P>0.05) between serum ALT and ATS of MXD small dose group and that of animal models group; MXD large dose group, XD group and Biphenyldimethylesterate (DDB) group are similar, no difference (P>0.05). Serum TNF-α and IFN-γ of MXD large dose group and XD group were significant lower than that of animal models group, there was significant difference among groups (P<0.05). Serum TNF-α and IFN-γ of XD group ware higher than that of MXD large dose group, there was significant difference among groups (P<0.05). MXD large dose group, XD group and DDB group were similar, no difference. Xiaocaihu decoction possesses the effect of pro2 tection of hepatic impairment and the protective mechanism might be associated with the inhibition of apoptosis and immunomodulation.

Dendrimer brain uptake and targeted therapy for brain injury in a large animal model of hypothermic circulatory arrest.

PubMed

Mishra, Manoj K; Beaty, Claude A; Lesniak, Wojciech G; Kambhampati, Siva P; Zhang, Fan; Wilson, Mary A; Blue, Mary E; Troncoso, Juan C; Kannan, Sujatha; Johnston, Michael V; Baumgartner, William A; Kannan, Rangaramanujam M

2014-03-25

Treatment of brain injury following circulatory arrest is a challenging health issue with no viable therapeutic options. Based on studies in a clinically relevant large animal (canine) model of hypothermic circulatory arrest (HCA)-induced brain injury, neuroinflammation and excitotoxicity have been identified as key players in mediating the brain injury after HCA. Therapy with large doses of valproic acid (VPA) showed some neuroprotection but was associated with adverse side effects. For the first time in a large animal model, we explored whether systemically administered polyamidoamine (PAMAM) dendrimers could be effective in reaching target cells in the brain and deliver therapeutics. We showed that, upon systemic administration, hydroxyl-terminated PAMAM dendrimers are taken up in the brain of injured animals and selectively localize in the injured neurons and microglia in the brain. The biodistribution in other major organs was similar to that seen in small animal models. We studied systemic dendrimer-drug combination therapy with two clinically approved drugs, N-acetyl cysteine (NAC) (attenuating neuroinflammation) and valproic acid (attenuating excitotoxicity), building on positive outcomes in a rabbit model of perinatal brain injury. We prepared and characterized dendrimer-NAC (D-NAC) and dendrimer-VPA (D-VPA) conjugates in multigram quantities. A glutathione-sensitive linker to enable for fast intracellular release. In preliminary efficacy studies, combination therapy with D-NAC and D-VPA showed promise in this large animal model, producing 24 h neurological deficit score improvements comparable to high dose combination therapy with VPA and NAC, or free VPA, but at one-tenth the dose, while significantly reducing the adverse side effects. Since adverse side effects of drugs are exaggerated in HCA, the reduced side effects with dendrimer conjugates and suggestions of neuroprotection offer promise for these nanoscale drug delivery systems.

Dendrimer Brain Uptake and Targeted Therapy for Brain Injury in a Large Animal Model of Hypothermic Circulatory Arrest

PubMed Central

2015-01-01

Treatment of brain injury following circulatory arrest is a challenging health issue with no viable therapeutic options. Based on studies in a clinically relevant large animal (canine) model of hypothermic circulatory arrest (HCA)-induced brain injury, neuroinflammation and excitotoxicity have been identified as key players in mediating the brain injury after HCA. Therapy with large doses of valproic acid (VPA) showed some neuroprotection but was associated with adverse side effects. For the first time in a large animal model, we explored whether systemically administered polyamidoamine (PAMAM) dendrimers could be effective in reaching target cells in the brain and deliver therapeutics. We showed that, upon systemic administration, hydroxyl-terminated PAMAM dendrimers are taken up in the brain of injured animals and selectively localize in the injured neurons and microglia in the brain. The biodistribution in other major organs was similar to that seen in small animal models. We studied systemic dendrimer–drug combination therapy with two clinically approved drugs, N-acetyl cysteine (NAC) (attenuating neuroinflammation) and valproic acid (attenuating excitotoxicity), building on positive outcomes in a rabbit model of perinatal brain injury. We prepared and characterized dendrimer-NAC (D-NAC) and dendrimer-VPA (D-VPA) conjugates in multigram quantities. A glutathione-sensitive linker to enable for fast intracellular release. In preliminary efficacy studies, combination therapy with D-NAC and D-VPA showed promise in this large animal model, producing 24 h neurological deficit score improvements comparable to high dose combination therapy with VPA and NAC, or free VPA, but at one-tenth the dose, while significantly reducing the adverse side effects. Since adverse side effects of drugs are exaggerated in HCA, the reduced side effects with dendrimer conjugates and suggestions of neuroprotection offer promise for these nanoscale drug delivery systems. PMID:24499315

A novel use of structural equation models to examine factors associated with prediabetes among adults aged 50 years and older: National Health and Nutrition Examination Survey 2001-2006.

PubMed

Bardenheier, Barbara H; Bullard, Kai McKeever; Caspersen, Carl J; Cheng, Yiling J; Gregg, Edward W; Geiss, Linda S

2013-09-01

To use structural modeling to test a hypothesized model of causal pathways related with prediabetes among older adults in the U.S. Cross-sectional study of 2,230 older adults (≥ 50 years) without diabetes included in the morning fasting sample of the 2001-2006 National Health and Nutrition Examination Surveys. Demographic data included age, income, marital status, race/ethnicity, and education. Behavioral data included physical activity (metabolic equivalent hours per week for vigorous or moderate muscle strengthening, walking/biking, and house/yard work), and poor diet (refined grains, red meat, added sugars, solid fats, and high-fat dairy). Structural-equation modeling was performed to examine the interrelationships among these variables with family history of diabetes, high blood pressure, BMI, large waist (waist circumference: women, ≥ 35 inches; men, ≥ 40 inches), triglycerides ≥ 200 mg/dL, and total and HDL (≥ 60 mg/dL) cholesterol. After dropping BMI and total cholesterol, our best-fit model included three single factors: socioeconomic position (SEP), physical activity, and poor diet. Large waist had the strongest direct effect on prediabetes (0.279), followed by male sex (0.270), SEP (-0.157), high blood pressure (0.122), family history of diabetes (0.070), and age (0.033). Physical activity had direct effects on HDL (0.137), triglycerides (-0.136), high blood pressure (-0.132), and large waist (-0.067); poor diet had direct effects on large waist (0.146) and triglycerides (0.148). Our results confirmed that, while including factors known to be associated with high risk of developing prediabetes, large waist circumference had the strongest direct effect. The direct effect of SEP on prediabetes suggests mediation by some unmeasured factor(s).

The Status of Large-Scale Assessment in the Pacific Region. REL Technical Brief. REL 2008-No. 003

ERIC Educational Resources Information Center

Ryan, Jennifer; Keir, Scott

2008-01-01

This technical brief describes the large-scale assessment measures and practices used in the jurisdictions served by the Pacific Regional Educational Laboratory. The need for effective large-scale assessment was identified as a major priority for improving student achievement in the Pacific Region jurisdictions: American Samoa, Guam, Hawaii, the…

A Fundamental Study for Efficient Implementaion of Online Collaborative Activities in Large-Scale Classes

ERIC Educational Resources Information Center

Matsuba, Ryuichi; Suzuki, Yusei; Kubota, Shin-Ichiro; Miyazaki, Makoto

2015-01-01

We study tactics for writing skills development through cross-disciplinary learning in online large-scale classes, and particularly are interested in implementation of online collaborative activities such as peer reviewing of writing. The goal of our study is to carry out collaborative works efficiently via online effectively in large-scale…

A General Conditional Large Deviation Principle

DOE PAGES

La Cour, Brian R.; Schieve, William C.

2015-07-18

Given a sequence of Borel probability measures on a Hausdorff space which satisfy a large deviation principle (LDP), we consider the corresponding sequence of measures formed by conditioning on a set B. If the large deviation rate function I is good and effectively continuous, and the conditioning set has the property that (1)more » $$\\overline{B°}$$=$$\\overline{B}$$ and (2) I(x)<∞ for all xε$$\\overline{B}$$, then the sequence of conditional measures satisfies a LDP with the good, effectively continuous rate function I B, where I B(x)=I(x)-inf I(B) if xε$$\\overline{B}$$ and I B(x)=∞ otherwise.« less

Towards an explicit model of large field inflation

NASA Astrophysics Data System (ADS)

Dorronsoro, Juan Diaz; Schillo, Marjorie

2018-05-01

The unwinding inflation mechanism is studied in a type IIB flux compactification where all moduli are stabilized using flux, non-perturbative effects, and the leading α' corrections of the large volume scenario. We consider the backreaction on the geometry due to the presence of anti-D3 branes as well as the backreaction of inflation on the Kähler moduli, and compute the resulting corrections to the slow-roll potential. By taking large flux numbers, we are able to find inflationary epochs where backreaction effects are under control, the inflaton traverses a super-Planckian field range, and the resulting amplitude of scalar perturbations is consistent with observation.

Electromagnetic duality and the electric memory effect

NASA Astrophysics Data System (ADS)

Hamada, Yuta; Seo, Min-Seok; Shiu, Gary

2018-02-01

We study large gauge transformations for soft photons in quantum electrodynamics which, together with the helicity operator, form an ISO(2) algebra. We show that the two non-compact generators of the ISO(2) algebra correspond respectively to the residual gauge symmetry and its electromagnetic dual gauge symmetry that emerge at null infinity. The former is helicity universal (electric in nature) while the latter is helicity distinguishing (magnetic in nature). Thus, the conventional large gauge transformation is electric in nature, and is naturally associated with a scalar potential. We suggest that the electric Aharonov-Bohm effect is a direct measure for the electromagnetic memory arising from large gauge transformations.

Scaling up to address data science challenges

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

Wendelberger, Joanne R.

Statistics and Data Science provide a variety of perspectives and technical approaches for exploring and understanding Big Data. Partnerships between scientists from different fields such as statistics, machine learning, computer science, and applied mathematics can lead to innovative approaches for addressing problems involving increasingly large amounts of data in a rigorous and effective manner that takes advantage of advances in computing. Here, this article will explore various challenges in Data Science and will highlight statistical approaches that can facilitate analysis of large-scale data including sampling and data reduction methods, techniques for effective analysis and visualization of large-scale simulations, and algorithmsmore » and procedures for efficient processing.« less

Cosmic string induced peculiar velocities

NASA Technical Reports Server (NTRS)

Van Dalen, Anthony; Schramm, David N.

1988-01-01

This paper considers the scenario of a flat universe with a network of heavy cosmic strings as the primordial fluctuation spectrum. The joint probability of finding streaming velocities of at least 600 km/s on large scales and local peculiar velocities of less than 800 km/s is calculated. It is shown how the effects of loops breaking up and being born with a spectrum of sizes can be estimated. It is found that to obtain large-scale streaming velocities of at least 600 km/s, it is necessary that either a large value for beta G mu exist or the effect of loop fissioning and production details be considerable.

Scaling up to address data science challenges

DOE PAGES

Wendelberger, Joanne R.

2017-04-27

Statistics and Data Science provide a variety of perspectives and technical approaches for exploring and understanding Big Data. Partnerships between scientists from different fields such as statistics, machine learning, computer science, and applied mathematics can lead to innovative approaches for addressing problems involving increasingly large amounts of data in a rigorous and effective manner that takes advantage of advances in computing. Here, this article will explore various challenges in Data Science and will highlight statistical approaches that can facilitate analysis of large-scale data including sampling and data reduction methods, techniques for effective analysis and visualization of large-scale simulations, and algorithmsmore » and procedures for efficient processing.« less

Production of large resonant plasma volumes in microwave electron cyclotron resonance ion sources

DOEpatents

Alton, Gerald D.

1998-01-01

Microwave injection methods for enhancing the performance of existing electron cyclotron resonance (ECR) ion sources. The methods are based on the use of high-power diverse frequency microwaves, including variable-frequency, multiple-discrete-frequency, and broadband microwaves. The methods effect large resonant "volume" ECR regions in the ion sources. The creation of these large ECR plasma volumes permits coupling of more microwave power into the plasma, resulting in the heating of a much larger electron population to higher energies, the effect of which is to produce higher charge state distributions and much higher intensities within a particular charge state than possible in present ECR ion sources.

Nonlinear Control of Large Disturbances in Magnetic Bearing Systems

NASA Technical Reports Server (NTRS)

Jiang, Yuhong; Zmood, R. B.

1996-01-01

In this paper, the nonlinear operation of magnetic bearing control methods is reviewed. For large disturbances, the effects of displacement constraints and power amplifier current and di/dt limits on bearing control system performance are analyzed. The operation of magnetic bearings exhibiting self-excited large scale oscillations have been studied both experimentally and by simulation. The simulation of the bearing system has been extended to include the effects of eddy currents in the actuators, so as to improve the accuracy of the simulation results. The results of these experiments and simulations are compared, and some useful conclusions are drawn for improving bearing system robustness.

Breakdown of an ant-plant mutualism follows the loss of large herbivores from an African savanna.

PubMed

Palmer, Todd M; Stanton, Maureen L; Young, Truman P; Goheen, Jacob R; Pringle, Robert M; Karban, Richard

2008-01-11

Mutualisms are key components of biodiversity and ecosystem function, yet the forces maintaining them are poorly understood. We investigated the effects of removing large mammals on an ant-Acacia mutualism in an African savanna. Ten years of large-herbivore exclusion reduced the nectar and housing provided by plants to ants, increasing antagonistic behavior by a mutualistic ant associate and shifting competitive dominance within the plant-ant community from this nectar-dependent mutualist to an antagonistic species that does not depend on plant rewards. Trees occupied by this antagonist suffered increased attack by stem-boring beetles, grew more slowly, and experienced doubled mortality relative to trees occupied by the mutualistic ant. These results show that large mammals maintain cooperation within a widespread symbiosis and suggest complex cascading effects of megafaunal extinction.

Feasibility of depopulation of a large feedlot during a foot-and-mouth disease outbreak.

PubMed

McReynolds, Sara W; Sanderson, Michael W

2014-02-01

To examine the feasibility of depopulation of a large feedlot during a foot-and-mouth disease (FMD) outbreak in the United States. Delphi survey followed by facilitated discussion. 27 experts, including veterinary toxicologists and pharmacologists, animal welfare experts, feedlot managers, and consulting veterinarians. 4 veterinary pharmacologists, 5 veterinary toxicologists, 4 animal welfare experts, 26 consulting veterinarians, and 8 feedlot managers were invited to participate in a Delphi survey to identify methods for depopulation of a large feedlot during an FMD outbreak. A facilitated discussion that included 1 pharmacologist, 1 toxicologist, 1 animal welfare expert, 2 consulting veterinarians, and 2 feedlot managers was held to review the survey results. 27 of 47 invited experts participated in the Delphi survey. Survey consensus was that, although several toxic agents would effectively cause acute death in a large number of animals, all of them had substantial animal welfare concerns. Pentobarbital sodium administered IV was considered the most effective pharmacological agent for euthanasia, and xylazine was considered the most effective sedative. Animal welfare concerns following administration of a euthanasia solution IV or a penetrating captive bolt were minimal; however, both veterinarians and feedlot managers felt that use of a captive bolt would be inefficient for depopulation. Veterinarians were extremely concerned about public perception, human safety, and timely depopulation of a large feedlot during an FMD outbreak. Depopulation of a large feedlot during an FMD outbreak would be difficult to complete in a humane and timely fashion.

Effect of Intraperitoneal Radiotelemetry Instrumentation on Voluntary Wheel Running and Surgical Recovery in Mice

PubMed Central

Helwig, Bryan G; Ward, Jermaine A; Blaha, Michael D; Leon, Lisa R

2012-01-01

Radiotelemetry transmitters support tracking of physiologic variables in conscious animals, but the size of the transmitter may alter animal health and behavior. We hypothesized that the size of the device adversely affects body weight, food intake, water intake, circadian core temperature, activity, voluntary running patterns, and the health of internal organs and that these negative effects can be minimized with smaller transmitter devices. Male C57BL/6J mice (weight, 20 to 24 g) were implanted with small (1.1 g, 0.52 mL) or large (3.5 g, 1.75 mL) radiotransmitters. Recovery of presurgical body weight, food intake, and water intake occurred within 3 d in mice implanted with small transmitter and 9 d in those with large transmitters. Mice with small transmitters displayed robust circadian core body temperature and activity patterns within 1 d after surgery, whereas activity was depressed in mice with large transmitters throughout experimentation. The most robust effects of the large transmitter included significantly reduced voluntary running, which never recovered to baseline, and inflammation of the diaphragm, large intestine, and duodenum. These results demonstrate that the large transmitter delayed surgical recovery, disrupted normal growth, reduced voluntary running, and induced inflammatory reactions of the internal organs of mice. The choice of radiotelemetry transmitter can significantly affect the health and wellbeing of experimental mice as well as data quality, such that the smallest transmitter device available and appropriate to the situation should be chosen for experimentation. PMID:23312089

High-Temperature-Short-Time Annealing Process for High-Performance Large-Area Perovskite Solar Cells.

PubMed

Kim, Minjin; Kim, Gi-Hwan; Oh, Kyoung Suk; Jo, Yimhyun; Yoon, Hyun; Kim, Ka-Hyun; Lee, Heon; Kim, Jin Young; Kim, Dong Suk

2017-06-27

Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large-size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 °C for 4 s, the perovskite film with an average domain size of 1 μm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm 2 active area and 18% over a 1 cm 2 active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.

Mapping the integrated Sachs-Wolfe effect

NASA Astrophysics Data System (ADS)

Manzotti, A.; Dodelson, S.

2014-12-01

On large scales, the anisotropies in the cosmic microwave background (CMB) reflect not only the primordial density field but also the energy gain when photons traverse decaying gravitational potentials of large scale structure, what is called the integrated Sachs-Wolfe (ISW) effect. Decomposing the anisotropy signal into a primordial piece and an ISW component, the main secondary effect on large scales, is more urgent than ever as cosmologists strive to understand the Universe on those scales. We present a likelihood technique for extracting the ISW signal combining measurements of the CMB, the distribution of galaxies, and maps of gravitational lensing. We test this technique with simulated data showing that we can successfully reconstruct the ISW map using all the data sets together. Then we present the ISW map obtained from a combination of real data: the NRAO VLA sky survey (NVSS) galaxy survey, temperature anisotropies, and lensing maps made by the Planck satellite. This map shows that, with the data sets used and assuming linear physics, there is no evidence, from the reconstructed ISW signal in the Cold Spot region, for an entirely ISW origin of this large scale anomaly in the CMB. However a large scale structure origin from low redshift voids outside the NVSS redshift range is still possible. Finally we show that future surveys, thanks to a better large scale lensing reconstruction will be able to improve the reconstruction signal to noise which is now mainly coming from galaxy surveys.

Analyzing the cosmic variance limit of remote dipole measurements of the cosmic microwave background using the large-scale kinetic Sunyaev Zel'dovich effect

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

Terrana, Alexandra; Johnson, Matthew C.; Harris, Mary-Jean, E-mail: aterrana@perimeterinstitute.ca, E-mail: mharris8@perimeterinstitute.ca, E-mail: mjohnson@perimeterinstitute.ca

Due to cosmic variance we cannot learn any more about large-scale inhomogeneities from the primary cosmic microwave background (CMB) alone. More information on large scales is essential for resolving large angular scale anomalies in the CMB. Here we consider cross correlating the large-scale kinetic Sunyaev Zel'dovich (kSZ) effect and probes of large-scale structure, a technique known as kSZ tomography. The statistically anisotropic component of the cross correlation encodes the CMB dipole as seen by free electrons throughout the observable Universe, providing information about long wavelength inhomogeneities. We compute the large angular scale power asymmetry, constructing the appropriate transfer functions, andmore » estimate the cosmic variance limited signal to noise for a variety of redshift bin configurations. The signal to noise is significant over a large range of power multipoles and numbers of bins. We present a simple mode counting argument indicating that kSZ tomography can be used to estimate more modes than the primary CMB on comparable scales. A basic forecast indicates that a first detection could be made with next-generation CMB experiments and galaxy surveys. This paper motivates a more systematic investigation of how close to the cosmic variance limit it will be possible to get with future observations.« less

Allometry indicates giant eyes of giant squid are not exceptional.

PubMed

Schmitz, Lars; Motani, Ryosuke; Oufiero, Christopher E; Martin, Christopher H; McGee, Matthew D; Gamarra, Ashlee R; Lee, Johanna J; Wainwright, Peter C

2013-02-18

The eyes of giant and colossal squid are among the largest eyes in the history of life. It was recently proposed that sperm whale predation is the main driver of eye size evolution in giant squid, on the basis of an optical model that suggested optimal performance in detecting large luminous visual targets such as whales in the deep sea. However, it is poorly understood how the eye size of giant and colossal squid compares to that of other aquatic organisms when scaling effects are considered. We performed a large-scale comparative study that included 87 squid species and 237 species of acanthomorph fish. While squid have larger eyes than most acanthomorphs, a comparison of relative eye size among squid suggests that giant and colossal squid do not have unusually large eyes. After revising constants used in a previous model we found that large eyes perform equally well in detecting point targets and large luminous targets in the deep sea. The eyes of giant and colossal squid do not appear exceptionally large when allometric effects are considered. It is probable that the giant eyes of giant squid result from a phylogenetically conserved developmental pattern manifested in very large animals. Whatever the cause of large eyes, they appear to have several advantages for vision in the reduced light of the deep mesopelagic zone.

Entanglement transitions induced by large deviations

NASA Astrophysics Data System (ADS)

Bhosale, Udaysinh T.

2017-12-01

The probability of large deviations of the smallest Schmidt eigenvalue for random pure states of bipartite systems, denoted as A and B , is computed analytically using a Coulomb gas method. It is shown that this probability, for large N , goes as exp[-β N2Φ (ζ ) ] , where the parameter β is the Dyson index of the ensemble, ζ is the large deviation parameter, while the rate function Φ (ζ ) is calculated exactly. Corresponding equilibrium Coulomb charge density is derived for its large deviations. Effects of the large deviations of the extreme (largest and smallest) Schmidt eigenvalues on the bipartite entanglement are studied using the von Neumann entropy. Effect of these deviations is also studied on the entanglement between subsystems 1 and 2, obtained by further partitioning the subsystem A , using the properties of the density matrix's partial transpose ρ12Γ. The density of states of ρ12Γ is found to be close to the Wigner's semicircle law with these large deviations. The entanglement properties are captured very well by a simple random matrix model for the partial transpose. The model predicts the entanglement transition across a critical large deviation parameter ζ . Log negativity is used to quantify the entanglement between subsystems 1 and 2. Analytical formulas for it are derived using the simple model. Numerical simulations are in excellent agreement with the analytical results.

Entanglement transitions induced by large deviations.

PubMed

Bhosale, Udaysinh T

2017-12-01

The probability of large deviations of the smallest Schmidt eigenvalue for random pure states of bipartite systems, denoted as A and B, is computed analytically using a Coulomb gas method. It is shown that this probability, for large N, goes as exp[-βN^{2}Φ(ζ)], where the parameter β is the Dyson index of the ensemble, ζ is the large deviation parameter, while the rate function Φ(ζ) is calculated exactly. Corresponding equilibrium Coulomb charge density is derived for its large deviations. Effects of the large deviations of the extreme (largest and smallest) Schmidt eigenvalues on the bipartite entanglement are studied using the von Neumann entropy. Effect of these deviations is also studied on the entanglement between subsystems 1 and 2, obtained by further partitioning the subsystem A, using the properties of the density matrix's partial transpose ρ_{12}^{Γ}. The density of states of ρ_{12}^{Γ} is found to be close to the Wigner's semicircle law with these large deviations. The entanglement properties are captured very well by a simple random matrix model for the partial transpose. The model predicts the entanglement transition across a critical large deviation parameter ζ. Log negativity is used to quantify the entanglement between subsystems 1 and 2. Analytical formulas for it are derived using the simple model. Numerical simulations are in excellent agreement with the analytical results.

Moduli thermalization and finite temperature effects in "big" divisor large volume D3/ D7 Swiss-cheese compactification

NASA Astrophysics Data System (ADS)

Shukla, Pramod

2011-01-01

In the context of Type IIB compactified on a large volume Swiss-Cheese orientifold in the presence of a mobile space-time filling D3-brane and stacks of fluxed D7-branes wrapping the "big" divisor Σ B of a Swiss-Cheese Calabi Yau in WCP 4[1, 1, 1, 6, 9], we explore various implications of moduli dynamics and discuss their couplings and decay into MSSM (-like) matter fields early in the history of universe to reach thermal equilibrium. Like finite temperature effects in O'KKLT, we observe that the local minimum of zero-temperature effective scalar potential is stable against any finite temperature corrections (up to two-loops) in large volume scenarios as well. Also we find that moduli are heavy enough to avoid any cosmological moduli problem.

Large-scale tidal effect on redshift-space power spectrum in a finite-volume survey

NASA Astrophysics Data System (ADS)

Akitsu, Kazuyuki; Takada, Masahiro; Li, Yin

2017-04-01

Long-wavelength matter inhomogeneities contain cleaner information on the nature of primordial perturbations as well as the physics of the early Universe. The large-scale coherent overdensity and tidal force, not directly observable for a finite-volume galaxy survey, are both related to the Hessian of large-scale gravitational potential and therefore are of equal importance. We show that the coherent tidal force causes a homogeneous anisotropic distortion of the observed distribution of galaxies in all three directions, perpendicular and parallel to the line-of-sight direction. This effect mimics the redshift-space distortion signal of galaxy peculiar velocities, as well as a distortion by the Alcock-Paczynski effect. We quantify its impact on the redshift-space power spectrum to the leading order, and discuss its importance for ongoing and upcoming galaxy surveys.

k-neighborhood Decentralization: A Comprehensive Solution to Index the UMLS for Large Scale Knowledge Discovery

PubMed Central

Xiang, Yang; Lu, Kewei; James, Stephen L.; Borlawsky, Tara B.; Huang, Kun; Payne, Philip R.O.

2011-01-01

The Unified Medical Language System (UMLS) is the largest thesaurus in the biomedical informatics domain. Previous works have shown that knowledge constructs comprised of transitively-associated UMLS concepts are effective for discovering potentially novel biomedical hypotheses. However, the extremely large size of the UMLS becomes a major challenge for these applications. To address this problem, we designed a k-neighborhood Decentralization Labeling Scheme (kDLS) for the UMLS, and the corresponding method to effectively evaluate the kDLS indexing results. kDLS provides a comprehensive solution for indexing the UMLS for very efficient large scale knowledge discovery. We demonstrated that it is highly effective to use kDLS paths to prioritize disease-gene relations across the whole genome, with extremely high fold-enrichment values. To our knowledge, this is the first indexing scheme capable of supporting efficient large scale knowledge discovery on the UMLS as a whole. Our expectation is that kDLS will become a vital engine for retrieving information and generating hypotheses from the UMLS for future medical informatics applications. PMID:22154838

Large and Small Cars in Real-World Crashes -Patterns of Use, Collision Types and Injury Outcomes

PubMed Central

Thomas, Pete; Frampton, Richard

1999-01-01

Previous work examining the effect of vehicle mass has demonstrated the link with occupant injury severity. The principal factor has been related to Newtonian mechanics. This paper analyses data from the UK Co-operative Crash Injury Study and identifies other factors associated with car size. The mass of the car is found to have a predominant effect on injury outcome in frontal collisions only where the effect is seen most in injuries to the head, face and chest. Most fatal casualties in small cars die when in collision with another car in front or side collisions while the key group for large cars is frontal collisions with road-side objects. There are several characteristics of small car occupants that differ from those in large cars including gender, age and vehicle occupancy. New information in the analysis concerns the priorities in casualty reduction between small and large car occupants and the paper argues that vehicle design should take account of this variation to produce vehicles optimised for the complete range of crashes and car occupants.

[Interventional radiology in bone metastases].

PubMed

Chiras, Jacques; Cormier, Evelyne; Baragan, Hector; Jean, Betty; Rose, Michèle

2007-02-01

Interventional radiology takes a large place in the treatment of bone metastases by numerous techniques, percutaneous or endovascular. Vertebroplasty appears actually as the most important technique for stabilisation of spine metastases as it induces satisfactory stabilisation of the vertebra and offer clear improvement of the quality of life. Due to the success of this technique cementoplasty of other bones, mainly pelvic girdle, largely develop. The heath due to the polymerisation of the cement induce carcinolytic effect but this effect is not as important as that can be created with radiofrequency destruction. This last technique appears actually as the most important development to destroy definitively some bone metastases and replace progressively alcoholic destruction of such lesions. Angiographic techniques appear more confidential but endovascular embolization is very useful to diminish the risk of surgical treatment of hyper vascular metastases. Chemoembolization is actually developped to associate the relief of pain induced by endovascular embolization and the carcinolytic effect obtained by local endovascular chemotherapy. All these techniques should develop largely during the next years and their efficacy and safety should improve largely by treating earlier the metastasis.

k-Neighborhood decentralization: a comprehensive solution to index the UMLS for large scale knowledge discovery.

PubMed

Xiang, Yang; Lu, Kewei; James, Stephen L; Borlawsky, Tara B; Huang, Kun; Payne, Philip R O

2012-04-01

The Unified Medical Language System (UMLS) is the largest thesaurus in the biomedical informatics domain. Previous works have shown that knowledge constructs comprised of transitively-associated UMLS concepts are effective for discovering potentially novel biomedical hypotheses. However, the extremely large size of the UMLS becomes a major challenge for these applications. To address this problem, we designed a k-neighborhood Decentralization Labeling Scheme (kDLS) for the UMLS, and the corresponding method to effectively evaluate the kDLS indexing results. kDLS provides a comprehensive solution for indexing the UMLS for very efficient large scale knowledge discovery. We demonstrated that it is highly effective to use kDLS paths to prioritize disease-gene relations across the whole genome, with extremely high fold-enrichment values. To our knowledge, this is the first indexing scheme capable of supporting efficient large scale knowledge discovery on the UMLS as a whole. Our expectation is that kDLS will become a vital engine for retrieving information and generating hypotheses from the UMLS for future medical informatics applications. Copyright © 2011 Elsevier Inc. All rights reserved.

Feeding strategy and cannibalism of the Argentine hake Merluccius hubbsi.

PubMed

Ocampo Reinaldo, M; González, R; Romero, M A

2011-12-01

The diet composition and feeding strategy of the Argentine hake Merluccius hubbsi in the San Matías Gulf were analysed in order to use this information for the sustainable management of the fishery. Merluccius hubbsi behaved as an opportunistic predator. Small M. hubbsi consumed planktonic crustaceans, whereas medium and large fish ate numerous prey taxa with low frequency of occurrence and variable specific abundance. Intra- and intercohort cannibalism were detected in all size groups and were particularly significant in large M. hubbsi. Medium-sized M. hubbsi consumed small conspecifics and large-sized M. hubbsi consumed both small and medium M. hubbsi. These results indicate that the removal of large M. hubbsi by fishing may increase the risk of overfishing by two combined effects: a direct effect of recruitment-overfishing and an indirect effect of growth-overfishing through an enhanced cannibalism of medium M. hubbsi on small M. hubbsi. Intra- and intercohort cannibalism and other trophic relationships in the M. hubbsi should therefore be considered explicitly in stock assessment models. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.

Effect of gate voltage polarity on the ionic liquid gating behavior of NdNiO 3/NdGaO 3 heterostructures

DOE PAGES

Dong, Yongqi; Xu, Haoran; Luo, Zhenlin; ...

2017-05-16

The effect of gate voltage polarity on the behavior of NdNiO 3 epitaxial thin films during ionic liquid gating is studied using in situ synchrotron X-ray techniques. We show that while negative biases have no discernible effect on the structure or composition of the films, large positive gate voltages result in the injection of a large concentration of oxygen vacancies (similar to 3%) and pronounced lattice expansion (0.17%) in addition to a 1000-fold increase in sheet resistance at room temperature. Despite the creation of large defect densities, the heterostructures exhibit a largely reversible switching behavior when sufficient time is providedmore » for the vacancies to migrate in and out of the thin film surface. The results confirm that electrostatic gating takes place at negative gate voltages for p-type complex oxides while positive voltages favor the electrochemical reduction of Ni 3+. Switching between positive and negative gate voltages therefore involves a combination of electronic and ionic doping processes that may be utilized in future electrochemical transistors.« less

On effective holographic Mott insulators

NASA Astrophysics Data System (ADS)

Baggioli, Matteo; Pujolàs, Oriol

2016-12-01

We present a class of holographic models that behave effectively as prototypes of Mott insulators — materials where electron-electron interactions dominate transport phenomena. The main ingredient in the gravity dual is that the gauge-field dynamics contains self-interactions by way of a particular type of non-linear electrodynamics. The electrical response in these models exhibits typical features of Mott-like states: i) the low-temperature DC conductivity is unboundedly low; ii) metal-insulator transitions appear by varying various parameters; iii) for large enough self-interaction strength, the conductivity can even decrease with increasing doping (density of carriers) — which appears as a sharp manifestation of `traffic-jam'-like behaviour; iv) the insulating state becomes very unstable towards superconductivity at large enough doping. We exhibit some of the properties of the resulting insulator-superconductor transition, which is sensitive to the momentum dissipation rate in a specific way. These models imply a clear and generic correlation between Mott behaviour and significant effects in the nonlinear electrical response. We compute the nonlinear current-voltage curve in our model and find that indeed at large voltage the conductivity is largely reduced.

Effectively-truncated large-scale shell-model calculations and nuclei around 100Sn

NASA Astrophysics Data System (ADS)

Gargano, A.; Coraggio, L.; Itaco, N.

2017-09-01

This paper presents a short overview of a procedure we have recently introduced, dubbed the double-step truncation method, which is aimed to reduce the computational complexity of large-scale shell-model calculations. Within this procedure, one starts with a realistic shell-model Hamiltonian defined in a large model space, and then, by analyzing the effective single particle energies of this Hamiltonian as a function of the number of valence protons and/or neutrons, reduced model spaces are identified containing only the single-particle orbitals relevant to the description of the spectroscopic properties of a certain class of nuclei. As a final step, new effective shell-model Hamiltonians defined within the reduced model spaces are derived by way of a unitary transformation of the original large-scale Hamiltonian. A detailed account of this transformation is given and the merit of the double-step truncation method is illustrated by discussing few selected results for 96Mo, described as four protons and four neutrons outside 88Sr. Some new preliminary results for light odd-tin isotopes from A = 101 to 107 are also reported.

Late Veneer collisions and their impact on the evolution of Venus (PS Division Outstanding ECS Award Lecture)

NASA Astrophysics Data System (ADS)

Gillmann, Cedric; Golabek, Gregor; Tackley, Paul; Raymond, Sean

2017-04-01

During the end of the accretion, the so-called Late Veneer phase, while the bulk of the mass of terrestrial planets is already in place, a substantial number of large collisions can still occur. Those impacts are thought to be responsible for the repartition of the Highly Siderophile Elements. They are also susceptible to have a strong effect on volatile repartition and mantle convection. We study how Late Veneer impacts modify the evolution of Venus and its atmosphere, using a coupled numerical simulation. We focus on volatile exchanges and their effects on surface conditions. Mantle dynamics, volcanism and degassing processes lead to an input of gases in the atmosphere and are modeled using the StagYY mantle convection code. Volatile losses are estimated through atmospheric escape modeling. It involves two different aspects: hydrodynamic escape (0-500 Myr) and non-thermal escape. Hydrodynamic escape is massive but occurs only when the solar energy input is strong. Post 4 Ga escape from non-thermal processes is comparatively low but long-lived. The resulting state of the atmosphere is used to the calculate greenhouse effect and surface temperature, through a one-dimensional gray radiative-convective model. Large impacts are capable of contributing to (i) atmospheric escape, (ii) volatile replenishment and (iii) energy transfer to the mantle. We test various impactor compositions, impact parameters (velocity, location, size, and timing) and eroding power. Scenarios we tested are adapted from numerical stochastic simulations (Raymond et al., 2013). Impactor sizes are dominated by large bodies (R>500 km). Erosion of the atmosphere by a few large impacts appears limited. Swarms of smaller more mass-effective impactors seem required for this effect to be significant. Large impactors have two main effects on the atmosphere. They can (i) create a large input of volatile from the melting they cause during the impact and through the volatiles they carry. This leads to an increase in atmosphere density and surface temperatures. However, early impacts can also (ii) deplete the mantle of Venus and (assuming strong early escape) ultimately remove volatiles from the system, leading to lower late degassing and lower surface temperatures. The competition between those effects depends on the time of the impact, which directly governs the strength of atmospheric losses.

Achieving large linear elasticity and high strength in bulk nanocompsite via synergistic effect

DOE PAGES

Hao, Shijie; Cui, Lishan; Guo, Fangmin; ...

2015-03-09

Elastic strain in bulk metallic materials is usually limited to only a fraction of 1%. Developing bulk metallic materials showing large linear elasticity and high strength has proven to be difficult. Here, based on the synergistic effect between nanowires and orientated martensite NiTi shape memory alloy, we developed an in-situ Nb nanowires-orientated martensitic NiTi matrix composite showing an ultra-large linear elastic strain of 4% and an ultrahigh yield strength of 1.8 GPa. This material also has a high mechanical energy storage efficiency of 96% and a high energy storage density of 36 J/cm 3 that is almost one order ofmore » larger than that of spring steel. It is demonstrated that the synergistic effect allows the exceptional mechanical properties of nanowires to be harvested at macro scale and the mechanical properties of matrix to be greatly improved, resulting in these superior properties. This research provides new avenues for developing advanced composites with superior properties by using effective synergistic effect between components.« less

Enhanced optical limiting effects in a double-decker bis(phthalocyaninato) rare earth complex using radially polarized beams

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

Wu, Jia-Lu; Gu, Bing, E-mail: gubing@seu.edu.cn; Liu, Dahui

2014-10-27

Optical limiting (OL) effects can be enhanced by exploiting various limiting mechanisms and by designing nonlinear optical materials. In this work, we present the large enhancement of OL effects by manipulating the polarization distribution of the light field. Theoretically, we develop the Z-scan and nonlinear transmission theories on a two-photon absorber under the excitation of cylindrical vector beams. It is shown that both the sensitivity of Z-scan technique and the OL effect using radially polarized beams have the large enhancement compared with that using linearly polarized beams (LPBs). Experimentally, we investigate the nonlinear absorption properties of a double-decker Pr[Pc(OC{sub 8}H{submore » 17}){sub 8}]{sub 2} rare earth complex by performing Z-scan measurements with femtosecond-pulsed radially polarized beams at 800 nm wavelength. The observed two-photon absorption process, which originates from strong intramolecular π–π interaction, is exploited for OL application. The results demonstrate the large enhancement of OL effects using radially polarized beams instead of LPBs.« less

Aeroacoustics of large wind turbines

NASA Technical Reports Server (NTRS)

Hubbard, Harvey H.; Shepherd, Kevin P.

1991-01-01

This paper reviews published information on aerodynamically generated noise from large horizontal axis wind turbines operated for electric power generation. Methods are presented for predicting both the discrete frequency rotational noise components and the broadband noise components, and results are compared with measurements. Refraction effects that result in the formation of high-frequency shadow zones in the upwind direction and channeling effects for the low frequencies in the downwind direction are illustrated. Special topics such as distributed source effects in prediction and the role of building dynamics in perception are also included.

Renormalization in Large Momentum Effective Theory of Parton Physics.

PubMed

Ji, Xiangdong; Zhang, Jian-Hui; Zhao, Yong

2018-03-16

In the large-momentum effective field theory approach to parton physics, the matrix elements of nonlocal operators of quark and gluon fields, linked by straight Wilson lines in a spatial direction, are calculated in lattice quantum chromodynamics as a function of hadron momentum. Using the heavy-quark effective theory formalism, we show a multiplicative renormalization of these operators at all orders in perturbation theory, both in dimensional and lattice regularizations. The result provides a theoretical basis for extracting parton properties through properly renormalized observables in Monte Carlo simulations.

Effect of Heat-Treatment on the Phases of Ni-Mn-Ga Magnetic Shape Memory Alloys

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

Huq, Ashfia; Ari-Gur, Pnina; Kimmel, Giora

2009-01-01

The Heusler alloys Ni50Mn25+xGa25-x display magnetic shape memory effect (MSM) with very fast and large reversible strain under magnetic fields. This large strain and the speed of reaction make MSM alloys attractive as smart materials. Our crystallographic investigation of these alloys, focused on non-stoichiometric composition with excess of manganese. Using neutron diffraction, we revealed the necessary processing parameters to achieve and preserve the homogeneous metastable one-phase martensitic structure that is needed for an MSM effect at room temperature.

Volcanic effects on climate

NASA Technical Reports Server (NTRS)

Robock, Alan

1991-01-01

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.

Environmental Factors Affecting Large-Bodied Coral Reef Fish Assemblages in the Mariana Archipelago

PubMed Central

Richards, Benjamin L.; Williams, Ivor D.; Vetter, Oliver J.; Williams, Gareth J.

2012-01-01

Large-bodied reef fishes represent an economically and ecologically important segment of the coral reef fish assemblage. Many of these individuals supply the bulk of the reproductive output for their population and have a disproportionate effect on their environment (e.g. as apex predators or bioeroding herbivores). Large-bodied reef fishes also tend to be at greatest risk of overfishing, and their loss can result in a myriad of either cascading (direct) or indirect trophic and other effects. While many studies have investigated habitat characteristics affecting populations of small-bodied reef fishes, few have explored the relationship between large-bodied species and their environment. Here, we describe the distribution of the large-bodied reef fishes in the Mariana Archipelago with an emphasis on the environmental factors associated with their distribution. Of the factors considered in this study, a negative association with human population density showed the highest relative influence on the distribution of large-bodied reef fishes; however, depth, water temperature, and distance to deep water also were important. These findings provide new information on the ecology of large-bodied reef fishes can inform discussions concerning essential fish habitat and ecosystem-based management for these species and highlight important knowledge gaps worthy of additional research. PMID:22384014

Environmental factors affecting large-bodied coral reef fish assemblages in the Mariana Archipelago.

PubMed

Richards, Benjamin L; Williams, Ivor D; Vetter, Oliver J; Williams, Gareth J

2012-01-01

Large-bodied reef fishes represent an economically and ecologically important segment of the coral reef fish assemblage. Many of these individuals supply the bulk of the reproductive output for their population and have a disproportionate effect on their environment (e.g. as apex predators or bioeroding herbivores). Large-bodied reef fishes also tend to be at greatest risk of overfishing, and their loss can result in a myriad of either cascading (direct) or indirect trophic and other effects. While many studies have investigated habitat characteristics affecting populations of small-bodied reef fishes, few have explored the relationship between large-bodied species and their environment. Here, we describe the distribution of the large-bodied reef fishes in the Mariana Archipelago with an emphasis on the environmental factors associated with their distribution. Of the factors considered in this study, a negative association with human population density showed the highest relative influence on the distribution of large-bodied reef fishes; however, depth, water temperature, and distance to deep water also were important. These findings provide new information on the ecology of large-bodied reef fishes can inform discussions concerning essential fish habitat and ecosystem-based management for these species and highlight important knowledge gaps worthy of additional research.

Dietary Supplement of Large Yellow Tea Ameliorates Metabolic Syndrome and Attenuates Hepatic Steatosis in db/db Mice

PubMed Central

Teng, Yun; Li, Daxiang; Guruvaiah, Ponmari; Xu, Na; Xie, Zhongwen

2018-01-01

Yellow tea has been widely recognized for its health benefits. However, its effects and mechanism are largely unknown. The current study investigated the mechanism of dietary supplements of large yellow tea and its effects on metabolic syndrome and the hepatic steatosis in male db/db mice. Our data showed that dietary supplements of large yellow tea and water extract significantly reduced water intake and food consumption, lowered the serum total and low-density lipoprotein cholesterol and triglyceride levels, and significantly reduced blood glucose level and increased glucose tolerance in db/db mice when compared to untreated db/db mice. In addition, the dietary supplement of large yellow tea prevented the fatty liver formation and restored the normal hepatic structure of db/db mice. Furthermore, the dietary supplement of large yellow tea obviously reduced the lipid synthesis related to gene fatty acid synthase, the sterol regulatory element-binding transcription factor 1 and acetyl-CoA carboxylase α, as well as fatty acid synthase and sterol response element-binding protein 1 expression, while the lipid catabolic genes were not altered in the liver of db/db mice. This study substantiated that the dietary supplement of large yellow tea has potential as a food additive for ameliorating type 2 diabetes-associated symptoms. PMID:29329215

NLO Higgs+jet at Large Transverse Momenta Including Top Quark Mass Effects

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

Neumann, Tobias

We present a next-to-leading order calculation of H+jet in gluon fusion including the effect of a finite top quark massmore » $$m_t$$ at large transverse momenta. Using the recently published two-loop amplitudes in the high energy expansion and our previous setup that includes finite $$m_t$$ effects in a low energy expansion, we are able to obtain $$m_t$$-finite results for transverse momenta below 225 GeV and above 500 GeV with negligible remaining top quark mass uncertainty. The only remaining region that has to rely on the common leading order rescaling approach is the threshold region $$\\sqrt{\\hat s}\\simeq 2m_t$$. We demonstrate that this rescaling provides an excellent approximation in the high $$p_T$$ region. Our calculation settles the issue of top quark mass effects at large transverse momenta. It is implemented in the parton level Monte Carlo code MCFM and is publicly available immediately in version 8.2.« less

Modeling the Fear Effect in Predator-Prey Interactions with Adaptive Avoidance of Predators.

PubMed

Wang, Xiaoying; Zou, Xingfu

2017-06-01

Recent field experiments on vertebrates showed that the mere presence of a predator would cause a dramatic change of prey demography. Fear of predators increases the survival probability of prey, but leads to a cost of prey reproduction. Based on the experimental findings, we propose a predator-prey model with the cost of fear and adaptive avoidance of predators. Mathematical analyses show that the fear effect can interplay with maturation delay between juvenile prey and adult prey in determining the long-term population dynamics. A positive equilibrium may lose stability with an intermediate value of delay and regain stability if the delay is large. Numerical simulations show that both strong adaptation of adult prey and the large cost of fear have destabilizing effect while large population of predators has a stabilizing effect on the predator-prey interactions. Numerical simulations also imply that adult prey demonstrates stronger anti-predator behaviors if the population of predators is larger and shows weaker anti-predator behaviors if the cost of fear is larger.

STUDIES ON MECHANISM OF BACTERICIDAL ACTION BY IRRADIATION WITH RADIOISOTOPE COBALT-60 (in Japanese)

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

Akimoto, T.

1960-04-01

E.Coli, YC-1 strain, were subjected to 40-C irradiation under various conditions and the survival ratios measured. The following results were obtained: With radiation dosage held constant, prolonged irradiation produced less bactericidal effect. Temperature and environment before irradiation had little influence on the bactericidal effect. Preirradiation washing had little effect. In the earlier stage metabolism continued but gradually decreased later. The more densely the suspension is populated, the higher the survival ratio. This ratio is decreased when a large number of bacteria is treated with a sublethal dose of streptomycin before irradiation. Treatment with chloramphenicol showed no effect in a smallmore » population, but the survival ratio decreased in a large population. Penicillin caused a decrease in a large population also, but in a small population the ratio became markedly high. It is presumed that the activity of bacterial metabolism is closely related to the bacterial action of irradiation. (P.C.H.)« less

Impact of a large density gradient on linear and nonlinear edge-localized mode simulations

DOE PAGES

Xi, P. W.; Xu, X. Q.; Xia, T. Y.; ...

2013-09-27

Here, the impact of a large density gradient on edge-localized modes (ELMs) is studied linearly and nonlinearly by employing both two-fluid and gyro-fluid simulations. In two-fluid simulations, the ion diamagnetic stabilization on high-n modes disappears when the large density gradient is taken into account. But gyro-fluid simulations show that the finite Larmor radius (FLR) effect can effectively stabilize high-n modes, so the ion diamagnetic effect alone is not sufficient to represent the FLR stabilizing effect. We further demonstrate that additional gyroviscous terms must be kept in the two-fluid model to recover the linear results from the gyro-fluid model. Nonlinear simulations show that the density variation significantly weakens the E × B shearing at the top of the pedestal and thus leads to more energy loss during ELMs. The turbulence spectrum after an ELM crash is measured and has the relation ofmore » $$P(k_{z})\\propto k_{z}^{-3.3}$$ .« less

Axonal Transport: How High Microtubule Density Can Compensate for Boundary Effects in Small-Caliber Axons

PubMed Central

Wortman, Juliana C.; Shrestha, Uttam M.; Barry, Devin M.; Garcia, Michael L.; Gross, Steven P.; Yu, Clare C.

2014-01-01

Long-distance intracellular axonal transport is predominantly microtubule-based, and its impairment is linked to neurodegeneration. In this study, we present theoretical arguments that suggest that near the axon boundaries (walls), the effective viscosity can become large enough to impede cargo transport in small (but not large) caliber axons. Our theoretical analysis suggests that this opposition to motion increases rapidly as the cargo approaches the wall. We find that having parallel microtubules close enough together to enable a cargo to simultaneously engage motors on more than one microtubule dramatically enhances motor activity, and thus minimizes the effects of any opposition to transport. Even if microtubules are randomly placed in axons, we find that the higher density of microtubules found in small-caliber axons increases the probability of having parallel microtubules close enough that they can be used simultaneously by motors on a cargo. The boundary effect is not a factor in transport in large-caliber axons where the microtubule density is lower. PMID:24559984

Effects of reinforcement on test-enhanced learning in a large, diverse introductory college psychology course.

PubMed

Trumbo, Michael C; Leiting, Kari A; McDaniel, Mark A; Hodge, Gordon K

2016-06-01

A robust finding within laboratory research is that structuring information as a test confers benefit on long-term retention-referred to as the testing effect. Although well characterized in laboratory environments, the testing effect has been explored infrequently within ecologically valid contexts. We conducted a series of 3 experiments within a very large introductory college-level course. Experiment 1 examined the impact of required versus optional frequent low-stakes testing (quizzes) on student grades, revealing students were much more likely to take advantage of quizzing if it was a required course component. Experiment 2 implemented a method of evaluating pedagogical intervention within a single course (thereby controlling for instructor bias and student self-selection), which revealed a testing effect. Experiment 3 ruled out additional exposure to information as an explanation for the findings of Experiment 2 and suggested that students at the college level, enrolled in very large sections, accept frequent quizzing well. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

A prospective study of the effects of ultralow volume (ULV) aerial application of malathion on epidemic Plasmodium falciparum malaria. II. Entomologic and operational aspects.

PubMed

Taylor, R T; Solis, M; Weathers, D B; Taylor, J W

1975-03-01

In a large-scale study in the Miragoane Valley of Haiti, designed to test the effects of aerial ultralow volume (ULV) malathion on epidemic Plasmodium falciparum malaria, spray operations resulted in an immediate and sharp decline in numbers of the vector, Anopheles albimanus. The adult population of this mosquito remained at less than 1% of previous levels until several weeks after a 50-day spray period (27 October-16 December 1972) during which six cycles were completed. The study area offered ideal conditions of wind, temperature, humidity, and mountain barriers. Mosquitoes in the area were highly susceptible to malathion. Results indicated that aerial ULV treatment with malathion can reduce A. albimanus populations rapidly and effectively when applications are made over an area as large as 20,000 acres. Preliminary results showed that effective control was not achieved in areas one-quarter that size; these areas were not sufficiently large, and infiltration of mosquitoes from adjacent untreated areas was possible.

Ultra-high gain diffusion-driven organic transistor

PubMed Central

Torricelli, Fabrizio; Colalongo, Luigi; Raiteri, Daniele; Kovács-Vajna, Zsolt Miklós; Cantatore, Eugenio

2016-01-01

Emerging large-area technologies based on organic transistors are enabling the fabrication of low-cost flexible circuits, smart sensors and biomedical devices. High-gain transistors are essential for the development of large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show a new organic field-effect transistor architecture with a gain larger than 700. This is the highest gain ever reported for organic field-effect transistors. In the proposed organic field-effect transistor, the charge injection and extraction at the metal–semiconductor contacts are driven by the charge diffusion. The ideal conditions of ohmic contacts with negligible contact resistance and flat current saturation are demonstrated. The approach is general and can be extended to any thin-film technology opening unprecedented opportunities for the development of high-performance flexible electronics. PMID:26829567

Effects of Internal Waves on Sound Propagation in the Shallow Waters of the Continental Shelves

DTIC Science & Technology

2016-09-01

experiment area were largely generated by tidal forcing. Compared to simulations without internal waves , simulations accounting for the effects of...internal waves in the experiment area were largely generated by tidal forcing. Compared to simulations without internal waves , simulations accounting for...IN THE SHALLOW WATERS OF THE CONTINENTAL SHELVES ..................................4  1.  Internal Tides—Internal Waves Generated by Tidal Forcing

Modeling and simulation of thermally actuated bilayer plates

NASA Astrophysics Data System (ADS)

Bartels, Sören; Bonito, Andrea; Muliana, Anastasia H.; Nochetto, Ricardo H.

2018-02-01

We present a mathematical model of polymer bilayers that undergo large bending deformations when actuated by non-mechanical stimuli such as thermal effects. The simple model captures a large class of nonlinear bending effects and can be discretized with standard plate elements. We devise a fully practical iterative scheme and apply it to the simulation of folding of several practically useful compliant structures comprising of thin elastic layers.

The effect of landform and plant size on mortallity and recovery of longleaf pine during a 100-year loog1

Treesearch

Brain J. Palik; William K. Michener; Robert J. Mitchell; Joseph W. Jones

1999-01-01

Unlike annual floods, large floods affect plant species outside of bottomland ecosystems. We know little about the effects of catastrophic floods on upland plants because of the rarity of this type of disturbance. Here we report on mortality and vegetative recovery of upland longleaf pines (Pinus palustris) after a large flood. The flood top-killed most seedlings...

Aspects of Coulomb damping in rotors supported on hydrodynamic bearings

NASA Technical Reports Server (NTRS)

Morton, P. G.

1982-01-01

The paper is concerned with the effect of friction in drive couplings on the non-sychronous whirling of a shaft. A simplified model is used to demonstrate the effect of large coupling misalignments on the stability of the system. It is concluded that provided these misalignments are large enough, the system becomes totally stable provided the shaft is supported on bearings exhibiting a viscous damping capacity.

Experimental study and large eddy simulation of effect of terrain slope on marginal burning in shrub fuel beds

Treesearch

Xiangyang Zhou; Shankar Mahalingam; David Weise

2007-01-01

This paper presents a combined study of laboratory scale fire spread experiments and a three-dimensional large eddy simulation (LES) to analyze the effect of terrain slope on marginal burning behavior in live chaparral shrub fuel beds. Line fire was initiated in single species fuel beds of four common chaparral plants under various fuel bed configurations and ambient...

Global anomalies and effective field theory

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

Golkar, Siavash; Sethi, Savdeep

2016-05-17

Here, we show that matching anomalies under large gauge transformations and large diffeomorphisms can explain the appearance and non-renormalization of couplings in effective field theory. We focus on thermal effective field theory, where we argue that the appearance of certain unusual Chern-Simons couplings is a consequence of global anomalies. As an example, we show that a mixed global anomaly in four dimensions fixes the chiral vortical effect coefficient (up to an overall additive factor). This is an experimentally measurable prediction from a global anomaly. For certain situations, we propose a simpler method for calculating global anomalies which uses correlation functionsmore » rather than eta invariants.« less

Adolescent health and adult labor market outcomes.

PubMed

Lundborg, Petter; Nilsson, Anton; Rooth, Dan-Olof

2014-09-01

Whereas a large literature has shown the importance of early life health for adult socioeconomic outcomes, there is little evidence on the importance of adolescent health. We contribute to the literature by studying the impact of adolescent health status on adult labor market outcomes using a unique and large-scale dataset covering almost the entire population of Swedish males. We show that most types of major conditions have long-run effects on future outcomes, and that the strongest effects result from mental conditions. Including sibling fixed effects or twin pair fixed effects reduces the magnitudes of the estimates, but they remain substantial. Copyright © 2014 Elsevier B.V. All rights reserved.

Spin precession and spin Hall effect in monolayer graphene/Pt nanostructures

NASA Astrophysics Data System (ADS)

Savero Torres, W.; Sierra, J. F.; Benítez, L. A.; Bonell, F.; Costache, M. V.; Valenzuela, S. O.

2017-12-01

Spin Hall effects have surged as promising phenomena for spin logics operations without ferromagnets. However, the magnitude of the detected electric signals at room temperature in metallic systems has been so far underwhelming. Here, we demonstrate a two-order of magnitude enhancement of the signal in monolayer graphene/Pt devices when compared to their fully metallic counterparts. The enhancement stems in part from efficient spin injection and the large spin resistance of graphene but we also observe 100% spin absorption in Pt and find an unusually large effective spin Hall angle of up to 0.15. The large spin-to-charge conversion allows us to characterise spin precession in graphene under the presence of a magnetic field. Furthermore, by developing an analytical model based on the 1D diffusive spin-transport, we demonstrate that the effective spin-relaxation time in graphene can be accurately determined using the (inverse) spin Hall effect as a means of detection. This is a necessary step to gather full understanding of the consequences of spin absorption in spin Hall devices, which is known to suppress effective spin lifetimes in both metallic and graphene systems.

Acute effects of a large bolide impact simulated by a global atmospheric circulation model

NASA Technical Reports Server (NTRS)

Thompson, Starley L.; Crutzen, P. J.

1988-01-01

The goal is to use a global three-dimensional atmospheric circulation model developed for studies of atmospheric effects of nuclear war to examine the time evolution of atmospheric effects from a large bolide impact. The model allows for dust and NOx injection, atmospheric transport by winds, removal by precipitation, radiative transfer effects, stratospheric ozone chemistry, and nitric acid formation and deposition on a simulated Earth having realistic geography. Researchers assume a modest 2 km-diameter impactor of the type that could have formed the 32 km-diameter impact structure found near Manson, Iowa and dated at roughly 66 Ma. Such an impact would have created on the order of 5 x 10 to the 10th power metric tons of atmospheric dust (about 0.01 g cm(-2) if spread globally) and 1 x 10 to the 37th power molecules of NO, or two orders of magnitude more stratospheric NO than might be produced in a large nuclear war. Researchers ignore potential injections of CO2 and wildfire smoke, and assume the direct heating of the atmosphere by impact ejecta on a regional scale is not large compared to absorption of solar energy by dust. Researchers assume an impact site at 45 N in the interior of present day North America.

Electrotherapy for the treatment of painful diabetic peripheral neuropathy: a review.

PubMed

Pieber, Karin; Herceg, Malvina; Paternostro-Sluga, Tatjana

2010-04-01

To review different types of electrotherapy for the treatment of painful diabetic peripheral neuropathy. A structured search of the electronic database MEDLINE was performed from the time of its initiation to July 2009. Articles in English and German were selected. The efficacy of different types of electrotherapy for painful diabetic peripheral neuropathy has been evaluated in 15 studies; the effects of transcutaneous electrical nerve stimulation are consistent. The beneficial effects of prolonged use have been reported in three large studies and one small study. The effects of frequency-modulated electromagnetic neural stimulation were assessed in one large study, and a significant reduction in pain was reported. Treatment with pulsed and static electromagnetic fields has been investigated in two small and three large studies, and analgesic benefits have been reported. In one large study focusing on pulsed electromagnetic fields, no beneficial effect on pain was registered. Only small studies were found concerning other types of electrotherapy, such as pulsed-dose electrical stimulation, high-frequency external muscle stimulation or high-tone external muscle stimulation. The conclusions drawn in these articles are diverse. Shortcomings and problems, including a poor study design, were observed in some. Further randomized, double-blind, placebo-controlled studies comprising larger sample sizes, a longer duration of treatment, and longer follow-up assessments are required.

The Role of Large-Scale Motions in Catalysis by Dihydrofolate Reductase

PubMed Central

2011-01-01

Dihydrofolate reductase has long been used as a model system to study the coupling of protein motions to enzymatic hydride transfer. By studying environmental effects on hydride transfer in dihydrofolate reductase (DHFR) from the cold-adapted bacterium Moritella profunda (MpDHFR) and comparing the flexibility of this enzyme to that of DHFR from Escherichia coli (EcDHFR), we demonstrate that factors that affect large-scale (i.e., long-range, but not necessarily large amplitude) protein motions have no effect on the kinetic isotope effect on hydride transfer or its temperature dependence, although the rates of the catalyzed reaction are affected. Hydrogen/deuterium exchange studies by NMR-spectroscopy show that MpDHFR is a more flexible enzyme than EcDHFR. NMR experiments with EcDHFR in the presence of cosolvents suggest differences in the conformational ensemble of the enzyme. The fact that enzymes from different environmental niches and with different flexibilities display the same behavior of the kinetic isotope effect on hydride transfer strongly suggests that, while protein motions are important to generate the reaction ready conformation, an optimal conformation with the correct electrostatics and geometry for the reaction to occur, they do not influence the nature of the chemical step itself; large-scale motions do not couple directly to hydride transfer proper in DHFR. PMID:22060818

A study on large-scale nudging effects in regional climate model simulation

NASA Astrophysics Data System (ADS)

Yhang, Yoo-Bin; Hong, Song-You

2011-05-01

The large-scale nudging effects on the East Asian summer monsoon (EASM) are examined using the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM). The NCEP/DOE reanalysis data is used to provide large-scale forcings for RSM simulations, configured with an approximately 50-km grid over East Asia, centered on the Korean peninsula. The RSM with a variant of spectral nudging, that is, the scale selective bias correction (SSBC), is forced by perfect boundary conditions during the summers (June-July-August) from 1979 to 2004. The two summers of 2000 and 2004 are investigated to demonstrate the impact of SSBC on precipitation in detail. It is found that the effect of SSBC on the simulated seasonal precipitation is in general neutral without a discernible advantage. Although errors in large-scale circulation for both 2000 and 2004 are reduced by using the SSBC method, the impact on simulated precipitation is found to be negative in 2000 and positive in 2004 summers. One possible reason for a different effect is that precipitation in the summer of 2004 is characterized by a strong baroclinicity, while precipitation in 2000 is caused by thermodynamic instability. The reduction of convective rainfall over the oceans by the application of the SSBC method seems to play an important role in modeled atmosphere.

Interactive Effects of Large- and Small-Scale Sources of Feral Honey-Bees for Sunflower in the Argentine Pampas

PubMed Central

Sáez, Agustín; Sabatino, Malena; Aizen, Marcelo A.

2012-01-01

Pollinators for animal pollinated crops can be provided by natural and semi-natural habitats, ranging from large vegetation remnants to small areas of non-crop land in an otherwise highly modified landscape. It is unknown, however, how different small- and large-scale habitat patches interact as pollinator sources. In the intensively managed Argentine Pampas, we studied the additive and interactive effects of large expanses (up to 2200 ha) of natural habitat, represented by untilled isolated “sierras”, and narrow (3–7 m wide) strips of semi-natural habitat, represented by field margins, as pollinator sources for sunflower (Helianthus annus). We estimated visitation rates by feral honey-bees, Apis mellifera, and native flower visitors (as a group) at 1, 5, 25, 50 and 100 m from a field margin in 17 sunflower fields 0–10 km distant from the nearest sierra. Honey-bees dominated the pollinator assemblage accounting for >90% of all visits to sunflower inflorescences. Honey-bee visitation was strongly affected by proximity to the sierras decreasing by about 70% in the most isolated fields. There was also a decline in honey-bee visitation with distance from the field margin, which was apparent with increasing field isolation, but undetected in fields nearby large expanses of natural habitat. The probability of observing a native visitor decreased with isolation from the sierras, but in other respects visitation by flower visitors other than honey-bees was mostly unaffected by the habitat factors assessed in this study. Overall, we found strong hierarchical and interactive effects between the study large and small-scale pollinator sources. These results emphasize the importance of preserving natural habitats and managing actively field verges in the absence of large remnants of natural habitat for improving pollinator services. PMID:22303477

Interactive effects of large- and small-scale sources of feral honey-bees for sunflower in the Argentine Pampas.

PubMed

Sáez, Agustín; Sabatino, Malena; Aizen, Marcelo A

2012-01-01

Pollinators for animal pollinated crops can be provided by natural and semi-natural habitats, ranging from large vegetation remnants to small areas of non-crop land in an otherwise highly modified landscape. It is unknown, however, how different small- and large-scale habitat patches interact as pollinator sources. In the intensively managed Argentine Pampas, we studied the additive and interactive effects of large expanses (up to 2200 ha) of natural habitat, represented by untilled isolated "sierras", and narrow (3-7 m wide) strips of semi-natural habitat, represented by field margins, as pollinator sources for sunflower (Helianthus annus). We estimated visitation rates by feral honey-bees, Apis mellifera, and native flower visitors (as a group) at 1, 5, 25, 50 and 100 m from a field margin in 17 sunflower fields 0-10 km distant from the nearest sierra. Honey-bees dominated the pollinator assemblage accounting for >90% of all visits to sunflower inflorescences. Honey-bee visitation was strongly affected by proximity to the sierras decreasing by about 70% in the most isolated fields. There was also a decline in honey-bee visitation with distance from the field margin, which was apparent with increasing field isolation, but undetected in fields nearby large expanses of natural habitat. The probability of observing a native visitor decreased with isolation from the sierras, but in other respects visitation by flower visitors other than honey-bees was mostly unaffected by the habitat factors assessed in this study. Overall, we found strong hierarchical and interactive effects between the study large and small-scale pollinator sources. These results emphasize the importance of preserving natural habitats and managing actively field verges in the absence of large remnants of natural habitat for improving pollinator services.

Large prospective birth cohort studies on environmental contaminants and child health - goals, challenges, limitations and needs.

PubMed

Luo, Zhong-Cheng; Liu, Jian-Meng; Fraser, William D

2010-02-01

The adverse health effects of environmental contaminants (ECs) are a rising public health concern, and a major threat to sustainable socioeconomic development. The developing fetuses and growing children are particularly vulnerable to the adverse effects of ECs. However, assessing the health impact of ECs presents a major challenge, given that multiple outcomes may arise from one exposure, multiple exposures may result in one outcome, and the complex interactions between ECs, and between ECs, nutrients and genetic factors, and the dynamic temporal changes in EC exposures during the life course. Large-scale prospective birth cohort studies collecting extensive data and specimen starting from the prenatal or pre-conception period, although costly, hold promise as a means to more clearly quantify the health effects of ECs, and to unravel the complex interactions between ECs, nutrients and genotypes. A number of such large-scale studies have been launched in some developed counties. We present an overview of "why", "what" and "how" behind these efforts with an objective to uncover major unidentified limitations and needs. Three major limitations were identified: (1) limited data and bio-specimens regarding early life EC exposure assessments in some birth cohort studies; (2) heavy participant burdens in some birth cohort studies may bias participant recruitment, and risk substantial loss to follow-up, protocol deviations limiting the quality of data and specimens collection, with an overall potential bias towards the null effect; (3) lack of concerted efforts in building comparable birth cohorts across countries to take advantage of natural "experiments" (large EC exposure level differences between countries) for more in-depth assessments of dose-response relationships, threshold exposure levels, and positive and negative effect modifiers. Addressing these concerns in current or future large-scale birth cohort studies may help to produce better evidence on the health effects of ECs.

Volcanic Aerosol Radiative Properties

NASA Technical Reports Server (NTRS)

Lacis, Andrew

2015-01-01

Large sporadic volcanic eruptions inject large amounts of sulfur bearing gases into the stratosphere which then get photochemically converted to sulfuric acid aerosol droplets that exert a radiative cooling effect on the global climate system lasting for several years.

Distribution of fixed beneficial mutations and the rate of adaptation in asexual populations

PubMed Central

Good, Benjamin H.; Rouzine, Igor M.; Balick, Daniel J.; Hallatschek, Oskar; Desai, Michael M.

2012-01-01

When large asexual populations adapt, competition between simultaneously segregating mutations slows the rate of adaptation and restricts the set of mutations that eventually fix. This phenomenon of interference arises from competition between mutations of different strengths as well as competition between mutations that arise on different fitness backgrounds. Previous work has explored each of these effects in isolation, but the way they combine to influence the dynamics of adaptation remains largely unknown. Here, we describe a theoretical model to treat both aspects of interference in large populations. We calculate the rate of adaptation and the distribution of fixed mutational effects accumulated by the population. We focus particular attention on the case when the effects of beneficial mutations are exponentially distributed, as well as on a more general class of exponential-like distributions. In both cases, we show that the rate of adaptation and the influence of genetic background on the fixation of new mutants is equivalent to an effective model with a single selection coefficient and rescaled mutation rate, and we explicitly calculate these effective parameters. We find that the effective selection coefficient exactly coincides with the most common fixed mutational effect. This equivalence leads to an intuitive picture of the relative importance of different types of interference effects, which can shift dramatically as a function of the population size, mutation rate, and the underlying distribution of fitness effects. PMID:22371564

A RESEARCH PLAN FOR THE USE OF THERMAL AVHRR IMAGERY TO STUDY ANNUAL AND SEASONAL MEAN SURFACE TEMPERATURES FOR LARGE LAKES IN NORTH AMERICA

EPA Science Inventory

Surface and vertical temperature data will be obtained from several large lakes With surface areas large enough to be effectively sampled with AVHRR imagery. Yearly and seasonal patterns of surface and whole water column thermal values will be compared to estimates of surface tem...

An Effective Methodology for Processing and Analyzing Large, Complex Spacecraft Data Streams

ERIC Educational Resources Information Center

Teymourlouei, Haydar

2013-01-01

The emerging large datasets have made efficient data processing a much more difficult task for the traditional methodologies. Invariably, datasets continue to increase rapidly in size with time. The purpose of this research is to give an overview of some of the tools and techniques that can be utilized to manage and analyze large datasets. We…

A robust and high-performance queue management controller for large round trip time networks

NASA Astrophysics Data System (ADS)

Khoshnevisan, Ladan; Salmasi, Farzad R.

2016-05-01

Congestion management for transmission control protocol is of utmost importance to prevent packet loss within a network. This necessitates strategies for active queue management. The most applied active queue management strategies have their inherent disadvantages which lead to suboptimal performance and even instability in the case of large round trip time and/or external disturbance. This paper presents an internal model control robust queue management scheme with two degrees of freedom in order to restrict the undesired effects of large and small round trip time and parameter variations in the queue management. Conventional approaches such as proportional integral and random early detection procedures lead to unstable behaviour due to large delay. Moreover, internal model control-Smith scheme suffers from large oscillations due to the large round trip time. On the other hand, other schemes such as internal model control-proportional integral and derivative show excessive sluggish performance for small round trip time values. To overcome these shortcomings, we introduce a system entailing two individual controllers for queue management and disturbance rejection, simultaneously. Simulation results based on Matlab/Simulink and also Network Simulator 2 (NS2) demonstrate the effectiveness of the procedure and verify the analytical approach.

Seismic analysis of a LNG storage tank isolated by a multiple friction pendulum system

NASA Astrophysics Data System (ADS)

Zhang, Ruifu; Weng, Dagen; Ren, Xiaosong

2011-06-01

The seismic response of an isolated vertical, cylindrical, extra-large liquefied natural gas (LNG) tank by a multiple friction pendulum system (MFPS) is analyzed. Most of the extra-large LNG tanks have a fundamental frequency which involves a range of resonance of most earthquake ground motions. It is an effective way to decrease the response of an isolation system used for extra-large LNG storage tanks under a strong earthquake. However, it is difficult to implement in practice with common isolation bearings due to issues such as low temperature, soft site and other severe environment factors. The extra-large LNG tank isolated by a MFPS is presented in this study to address these problems. A MFPS is appropriate for large displacements induced by earthquakes with long predominant periods. A simplified finite element model by Malhotra and Dunkerley is used to determine the usefulness of the isolation system. Data reported and statistically sorted include pile shear, wave height, impulsive acceleration, convective acceleration and outer tank acceleration. The results show that the isolation system has excellent adaptability for different liquid levels and is very effective in controlling the seismic response of extra-large LNG tanks.

High population density enhances recruitment and survival of a harvested coral reef fish.

PubMed

Wormald, Clare L; Steele, Mark A; Forrester, Graham E

2013-03-01

A negative relationship between population growth and population density (direct density dependence) is necessary for population regulation and is assumed in most models of harvested populations. Experimental tests for density dependence are lacking for large-bodied, harvested fish because of the difficulty of manipulating population density over large areas. We studied a harvested coral reef fish, Lutjanus apodus (schoolmaster snapper), using eight large, isolated natural reefs (0.4-1.6 ha) in the Bahamas as replicates. An initial observational test for density dependence was followed by a manipulation of population density. The manipulation weakened an association between density and shelter-providing habitat features and revealed a positive effect of population density on recruitment and survival (inverse density dependence), but no effect of density on somatic growth. The snappers on an individual reef were organized into a few shoals, and we hypothesize that large shoals on high-density reefs were less vulnerable to large piscivores (groupers and barracudas) than the small shoals on low-density reefs. Reductions in predation risk for individuals in large social groups are well documented, but because snapper shoals occupied reefs the size of small marine reserves, these ecological interactions may influence the outcome of management actions.

The Effects of Wave Escape on Fast Magnetosonic Wave Turbulence in Solar Flares

NASA Technical Reports Server (NTRS)

Pongkitiwanichakul, Peera; Chandran, Benjamin D. G.; Karpen, Judith T.; DeVore, C. Richard

2012-01-01

One of the leading models for electron acceleration in solar flares is stochastic acceleration by weakly turbulent fast magnetosonic waves ("fast waves"). In this model, large-scale flows triggered by magnetic reconnection excite large-wavelength fast waves, and fast-wave energy then cascades from large wavelengths to small wavelengths. Electron acceleration by large-wavelength fast-waves is weak, and so the model relies on the small-wavelength waves produced by the turbulent cascade. In order for the model to work, the energy cascade time for large-wavelength fast waves must be shorter than the time required for the waves to propagate out of the solar-flare acceleration region. To investigate the effects of wave escape, we solve the wave kinetic equation for fast waves in weak turbulence theory, supplemented with a homogeneous wave-loss term.We find that the amplitude of large-wavelength fast waves must exceed a minimum threshold in order for a significant fraction of the wave energy to cascade to small wavelengths before the waves leave the acceleration region.We evaluate this threshold as a function of the dominant wavelength of the fast waves that are initially excited by reconnection outflows.

Potential health effects of space radiation

NASA Technical Reports Server (NTRS)

Yang, Chui-Hsu; Craise, Laurie M.

1993-01-01

Crewmembers on missions to the Moon or Mars will be exposed to radiation belts, galactic cosmic rays, and possibly solar particle events. The potential health hazards due to these space radiations must be considered carefully to ensure the success of space exploration. Because there is no human radioepidemiological data for acute and late effects of high-LET (Linear-Energy-Transfer) radiation, the biological risks of energetic charged particles have to be estimated from experimental results on animals and cultured cells. Experimental data obtained to date indicate that charged particle radiation can be much more effective than photons in causing chromosome aberrations, cell killing, mutation, and tumor induction. The relative biological effectiveness (RBE) varies with biological endpoints and depends on the LET of heavy ions. Most lesions induced by low-LET radiation can be repaired in mammalian cells. Energetic heavy ions, however, can produce large complex DNA damages, which may lead to large deletions and are irreparable. For high-LET radiation, therefore, there are less or no dose rate effects. Physical shielding may not be effective in minimizing the biological effects on energetic heavy ions, since fragments of the primary particles can be effective in causing biological effects. At present the uncertainty of biological effects of heavy particles is still very large. With further understanding of the biological effects of space radiation, the career doses can be kept at acceptable levels so that the space radiation environment need not be a barrier to the exploitation of the promise of space.

Semantic transparency in free stems: The effect of Orthography-Semantics Consistency on word recognition.

PubMed

Marelli, Marco; Amenta, Simona; Crepaldi, Davide

2015-01-01

A largely overlooked side effect in most studies of morphological priming is a consistent main effect of semantic transparency across priming conditions. That is, participants are faster at recognizing stems from transparent sets (e.g., farm) in comparison to stems from opaque sets (e.g., fruit), regardless of the preceding primes. This suggests that semantic transparency may also be consistently associated with some property of the stem word. We propose that this property might be traced back to the consistency, throughout the lexicon, between the orthographic form of a word and its meaning, here named Orthography-Semantics Consistency (OSC), and that an imbalance in OSC scores might explain the "stem transparency" effect. We exploited distributional semantic models to quantitatively characterize OSC, and tested its effect on visual word identification relying on large-scale data taken from the British Lexicon Project (BLP). Results indicated that (a) the "stem transparency" effect is solid and reliable, insofar as it holds in BLP lexical decision times (Experiment 1); (b) an imbalance in terms of OSC can account for it (Experiment 2); and (c) more generally, OSC explains variance in a large item sample from the BLP, proving to be an effective predictor in visual word access (Experiment 3).

Detection of Supernova Neutrinos on the Earth for Large θ13

NASA Astrophysics Data System (ADS)

Xu, Jing; Huang, Ming-Yang; Hu, Li-Jun; Guo, Xin-Heng; Young, Bing-Lin

2014-02-01

Supernova (SN) neutrinos detected on the Earth are subject to the shock wave effects, the Mikheyev—Smirnov—Wolfenstein (MSW) effects, the neutrino collective effects and the Earth matter effects. Considering the recent experimental result about the large mixing angle θ13 (≃ 8.8°) provided by the Daya Bay Collaboration and applying the available knowledge for the neutrino conversion probability in the high resonance region of SN, PH, which is in the form of hypergeometric function in the case of large θ13, we deduce the expression of PH taking into account the shock wave effects. It is found that PH is not zero in a certain range of time due to the shock wave effects. After considering all the four physical effects and scanning relevant parameters, we calculate the event numbers of SN neutrinos for the “Garching” distribution of neutrino energy spectrum. From the numerical results, it is found that the behaviors of neutrino event numbers detected on the Earth depend on the neutrino mass hierarchy and neutrino spectrum parameters including the dimensionless pinching parameter βα (where α refers to neutrino flavor), the average energy , and the SN neutrino luminosities Lα. Finally, we give the ranges of SN neutrino event numbers that will be detected at the Daya Bay experiment.

Effects of Size and Age of the Host Musca domestica (Diptera: Muscidae) on Production of the Parasitoid Wasp Spalangia endius (Hymenoptera: Pteromalidae).

PubMed

Broski, Scott A; King, B H

2017-02-01

One method of control of house flies, Musca domestica L. (Diptera: Muscidae), and other filth flies is by repeated release of large numbers of pupal parasitoids such as Spalangia endius Walker. Rearing these parasitoids may be facilitated by understanding how host factors affect their production. Previous studies have examined the effects of host size and host age on parasitoid production, but have not examined the interaction between host size and host age or the effects with older females, which may be less capable of drilling tough hosts. Females were given hosts of a single size-age category (small young, small old, large young, or large old) for 2 wk. The effect of host size and of host age on parasitoid production depended on female age. On their first day of oviposition, females produced more offspring from large than from small hosts, but host age had no significant effect. The cumulative number of parasitoids produced in the first week was not significantly affected by host size or host age. However, the cumulative number of parasitoids produced over 2 wk was affected by both host size and host age, with the greatest number of parasitoids produced from small young hosts. Thus, not only are smaller hosts cheaper to produce, but these results suggest that their use may have no effect or a positive effect on the number of parasitoids that can be produced when females are ovipositing for a week or two. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Quantifying streamflow change caused by forest disturbance at a large spatial scale: A single watershed study

NASA Astrophysics Data System (ADS)

Wei, Xiaohua; Zhang, Mingfang

2010-12-01

Climatic variability and forest disturbance are commonly recognized as two major drivers influencing streamflow change in large-scale forested watersheds. The greatest challenge in evaluating quantitative hydrological effects of forest disturbance is the removal of climatic effect on hydrology. In this paper, a method was designed to quantify respective contributions of large-scale forest disturbance and climatic variability on streamflow using the Willow River watershed (2860 km2) located in the central part of British Columbia, Canada. Long-term (>50 years) data on hydrology, climate, and timber harvesting history represented by equivalent clear-cutting area (ECA) were available to discern climatic and forestry influences on streamflow by three steps. First, effective precipitation, an integrated climatic index, was generated by subtracting evapotranspiration from precipitation. Second, modified double mass curves were developed by plotting accumulated annual streamflow against annual effective precipitation, which presented a much clearer picture of the cumulative effects of forest disturbance on streamflow following removal of climatic influence. The average annual streamflow changes that were attributed to forest disturbances and climatic variability were then estimated to be +58.7 and -72.4 mm, respectively. The positive (increasing) and negative (decreasing) values in streamflow change indicated opposite change directions, which suggest an offsetting effect between forest disturbance and climatic variability in the study watershed. Finally, a multivariate Autoregressive Integrated Moving Average (ARIMA) model was generated to establish quantitative relationships between accumulated annual streamflow deviation attributed to forest disturbances and annual ECA. The model was then used to project streamflow change under various timber harvesting scenarios. The methodology can be effectively applied to any large-scale single watershed where long-term data (>50 years) are available.

Parallel Large-Scale Molecular Dynamics Simulation Opens New Perspective to Clarify the Effect of a Porous Structure on the Sintering Process of Ni/YSZ Multiparticles.

PubMed

Xu, Jingxiang; Higuchi, Yuji; Ozawa, Nobuki; Sato, Kazuhisa; Hashida, Toshiyuki; Kubo, Momoji

2017-09-20

Ni sintering in the Ni/YSZ porous anode of a solid oxide fuel cell changes the porous structure, leading to degradation. Preventing sintering and degradation during operation is a great challenge. Usually, a sintering molecular dynamics (MD) simulation model consisting of two particles on a substrate is used; however, the model cannot reflect the porous structure effect on sintering. In our previous study, a multi-nanoparticle sintering modeling method with tens of thousands of atoms revealed the effect of the particle framework and porosity on sintering. However, the method cannot reveal the effect of the particle size on sintering and the effect of sintering on the change in the porous structure. In the present study, we report a strategy to reveal them in the porous structure by using our multi-nanoparticle modeling method and a parallel large-scale multimillion-atom MD simulator. We used this method to investigate the effect of YSZ particle size and tortuosity on sintering and degradation in the Ni/YSZ anodes. Our parallel large-scale MD simulation showed that the sintering degree decreased as the YSZ particle size decreased. The gas fuel diffusion path, which reflects the overpotential, was blocked by pore coalescence during sintering. The degradation of gas diffusion performance increased as the YSZ particle size increased. Furthermore, the gas diffusion performance was quantified by a tortuosity parameter and an optimal YSZ particle size, which is equal to that of Ni, was found for good diffusion after sintering. These findings cannot be obtained by previous MD sintering studies with tens of thousands of atoms. The present parallel large-scale multimillion-atom MD simulation makes it possible to clarify the effects of the particle size and tortuosity on sintering and degradation.

Predator cannibalism can intensify negative impacts on heterospecific prey.

PubMed

Takatsu, Kunio; Kishida, Osamu

2015-07-01

Although natural populations consist of individuals with different traits, and the degree of phenotypic variation varies among populations, the impact of phenotypic variation on ecological interactions has received little attention, because traditional approaches to community ecology assume homogeneity of individuals within a population. Stage structure, which is a common way of generating size and developmental variation within predator populations, can drive cannibalistic interactions, which can affect the strength of predatory effects on the predator's heterospecific prey. Studies have shown that predator cannibalism weakens predatory effects on heterospecific prey by reducing the size of the predator population and by inducing less feeding activity of noncannibal predators. We predict, however, that predator cannibalism, by promoting rapid growth of the cannibals, can also intensify predation pressure on heterospecific prey, because large predators have large resource requirements and may utilize a wider variety of prey species. To test this hypothesis, we conducted an experiment in which we created carnivorous salamander (Hynobius retardatus) populations with different stage structures by manipulating the salamander's hatch timing (i.e., populations with large or small variation in the timing of hatching), and explored the resultant impacts on the abundance, behavior, morphology, and life history of the salamander's large heterospecific prey, Rana pirica frog tadpoles. Cannibalism was rare in salamander populations having small hatch-timing variation, but was frequent in those having large hatch-timing variation. Thus, giant salamander cannibals occurred only in the latter. We clearly showed that salamander giants exerted strong predation pressure on frog tadpoles, which induced large behavioral and morphological defenses in the tadpoles and caused them to metamorphose late at large size. Hence, predator cannibalism arising from large variation in the timing of hatching can strengthen predatory effects on heterospecific prey and can have impacts on various, traits of both predator and prey. Because animals commonly broaden their diet as they grow, such negative impacts of predator cannibalism on the heterospecific prey may be common in interactions between predators and prey species of similar size.

Modulation of NO and ROS production by AdiNOS transduced vascular cells through supplementation with L-Arg and BH4: implications for gene therapy of restenosis.

PubMed

Forbes, Scott P; Alferiev, Ivan S; Chorny, Michael; Adamo, Richard F; Levy, Robert J; Fishbein, Ilia

2013-09-01

Gene therapy with viral vectors encoding for NOS enzymes has been recognized as a potential therapeutic approach for the prevention of restenosis. Optimal activity of iNOS is dependent on the intracellular availability of L-Arg and BH4 via prevention of NOS decoupling and subsequent ROS formation. Herein, we investigated the effects of separate and combined L-Arg and BH4 supplementation on the production of NO and ROS in cultured rat arterial smooth muscle and endothelial cells transduced with AdiNOS, and their impact on the antirestenotic effectiveness of AdiNOS delivery to balloon-injured rat carotid arteries. Supplementation of AdiNOS transduced endothelial and vascular smooth muscle cells with L-Arg (3.0 mM), BH4 (10 μM) and especially their combination resulted in a significant increase in NO production as measured by nitrite formation in media. Formation of ROS was dose-dependently increased following transduction with increasing MOIs of AdiNOS. Exposure of RASMC to AdiNOS tethered to meshes via a hydrolyzable cross-linker, modeling viral delivery from stents, resulted in increased ROS production, which was decreased by supplementation with BH4 but not L-Arg or L-Arg/BH4. Enhanced cell death, caused by AdiNOS transduction, was also preventable with BH4 supplementation. In the rat carotid model of balloon injury, intraluminal delivery of AdiNOS in BH4-, L-Arg-, and especially in BH4 and L-Arg supplemented animals was found to significantly enhance the antirestenotic effects of AdiNOS-mediated gene therapy. Fine-tuning of iNOS function by L-Arg and BH4 supplementation in the transduced vasculature augments the therapeutic potential of gene therapy with iNOS for the prevention of restenosis. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Modulation of NO and ROS production by AdiNOS transduced vascular cells through supplementation with L-Arg and BH4: Implications for gene therapy of restenosis

PubMed Central

Forbes, Scott P.; Alferiev, Ivan S.; Chorny, Michael; Adamo, Richard F.; Levy, Robert J.; Fishbein, Ilia

2013-01-01

Objective Gene therapy with viral vectors encoding for NOS enzymes has been recognized as a potential therapeutic approach for the prevention of restenosis. Optimal activity of iNOS is dependent on the intracellular availability of L-Arg and BH4 via prevention of NOS decoupling and subsequent ROS formation. Herein, we investigated the effects of separate and combined L-Arg and BH4 supplementation on the production of NO and ROS in cultured rat arterial smooth muscle and endothelial cells transduced with AdiNOS, and their impact on the antirestenotic effectiveness of AdiNOS delivery to balloon-injured rat carotid arteries. Methods and Results Supplementation of AdiNOS transduced endothelial and vascular smooth muscle cells with L-Arg (3.0 mM), BH4 (10 μM) and especially their combination resulted in a significant increase in NO production as measured by nitrite formation in media. Formation of ROS was dose-dependently increased following transduction with increasing MOIs of AdiNOS. Exposure of RASMC to AdiNOS tethered to meshes via a hydrolysable cross-linker, modeling viral delivery from stents, resulted in increased ROS production, which was decreased by supplementation with BH4 but not L-Arg or L-Arg/BH4. Enhanced cell death, caused by AdiNOS transduction, was also preventable with BH4 supplementation. In the rat carotid model of balloon injury, intraluminal delivery of AdiNOS in BH4-, L-Arg-, and especially in BH4 and L-Arg supplemented animals was found to significantly enhance the antirestenotic effects of AdiNOS-mediated gene therapy. Conclusions Fine-tuning of iNOS function by L-Arg and BH4 supplementation in the transduced vasculature augments the therapeutic potential of gene therapy with iNOS for the prevention of restenosis. PMID:23958248

Application of a drainage film reduces fibroblast ingrowth into large-pored polyurethane foam during negative-pressure wound therapy in an in vitro model.

PubMed

Wiegand, Cornelia; Springer, Steffen; Abel, Martin; Wesarg, Falko; Ruth, Peter; Hipler, Uta-Christina

2013-01-01

Negative-pressure wound therapy (NPWT) is an advantageous treatment option in wound management to promote healing and reduce the risk of complications. NPWT is mainly carried out using open-cell polyurethane (PU) foams that stimulate granulation tissue formation. However, growth of wound bed tissue into foam material, leading to disruption of newly formed tissue upon dressing removal, has been observed. Consequently, it would be of clinical interest to preserve the positive effects of open-cell PU foams while avoiding cellular ingrowth. The study presented analyzed effects of NPWT using large-pored PU foam, fine-pored PU foam, and the combination of large-pored foam with drainage film on human dermal fibroblasts grown in a collagen matrix. The results showed no difference between the dressings in stimulating cellular migration during NPWT. However, when NPWT was applied using a large-pored PU foam, the fibroblasts continued to migrate into the dressing. This led to significant breaches in the cell layers upon removal of the samples after vacuum treatment. In contrast, cell migration stopped at the collagen matrix edge when fine-pored PU foam was used, as well as with the combination of PU foam and drainage film. In conclusion, placing a drainage film between collagen matrix and the large-pored PU foam dressing reduced the ingrowth of cells into the foam significantly. Moreover, positive effects on cellular migration were not affected, and the effect of the foam on tissue surface roughness in vitro was also reduced. © 2013 by the Wound Healing Society.

Dynamic and heterogeneous effects of sibling death on children's outcomes.

PubMed

Fletcher, Jason; Vidal-Fernandez, Marian; Wolfe, Barbara

2018-01-02

This paper explores the effects of experiencing the death of a sibling on children's developmental outcomes. Recent work has shown that experiencing a sibling death is common and long-term effects are large. We extend understanding of these effects by estimating dynamic effects on surviving siblings' cognitive and socioemotional outcomes, as well as emotional and cognitive support by parents. Using the Children of the National Longitudinal Survey of Youth 1979 (CNLSY79), we find large initial effects on cognitive and noncognitive outcomes that decline over time. We also provide evidence that the effects are larger if the surviving child is older and less prominent if the deceased child was either disabled or an infant, suggesting sensitive periods of exposure. Auxiliary results show that parental investments in the emotional support of surviving children decline following the death of their child.

Design of an amplifier model accounting for thermal effect in fully aperiodic large pitch fibers

NASA Astrophysics Data System (ADS)

Tragni, K.; Molardi, C.; Poli, F.; Dauliat, R.; Leconte, B.; Darwich, D.; du Jeu, R.; Malleville, M. A.; Jamier, R.; Selleri, S.; Roy, P.; Cucinotta, A.

2018-02-01

Yb-doped Photonic Crystal Fibers (PCFs) have triggered a significant power scaling into fiber-based lasers. However thermally-induced effects, like mode instability, can compromise the output beam quality. PCF design with improved Higher Order Mode (HOM) delocalization and effective thermal resilience can contain the problem. In particular, Fully- Aperiodic Large-Pitch Fibers (FA-LPFs) have shown interesting properties in terms of resilience to thermal effects. In this paper the performances of a Yb-doped FA-LPF amplifier are experimentally and numerically investigated. Modal properties and gain competition between Fundamental Mode (FM) and first HOM have been calculated, in presence of thermal effects. The main doped fiber characteristics have been derived by comparison between experimental and numerical results.

Mitigating chromatic effects for the transverse focusing of intense charged particle beams

NASA Astrophysics Data System (ADS)

Mitrani, James; Kaganovich, Igor; Davidson, Ronald

2013-09-01

A final focusing scheme designed to minimize chromatic effects is discussed. Solenoids are often used for transverse focusing in accelerator systems that require a charged particle beam with a small focal spot and/or large energy density A sufficiently large spread in axial momentum will reduce the effectiveness of transverse focusing, and result in chromatic effects on the final focal spot. Placing a weaker solenoid upstream of a stronger final focusing solenoid (FFS) mitigates chromatic effects on transverse beam focusing. J.M. Mitrani et al., Nucl. Inst. Meth. Phys. Res. A (2013) http://dx.doi.org/10.1016/j.nima.2013.05.09 This work was supported by DOE contract DE-AC02-09CH11466.

A comparison of three approaches to compute the effective Reynolds number of the implicit large-eddy simulations

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

Zhou, Ye; Thornber, Ben

2016-04-12

Here, the implicit large-eddy simulation (ILES) has been utilized as an effective approach for calculating many complex flows at high Reynolds number flows. Richtmyer–Meshkov instability (RMI) induced flow can be viewed as a homogeneous decaying turbulence (HDT) after the passage of the shock. In this article, a critical evaluation of three methods for estimating the effective Reynolds number and the effective kinematic viscosity is undertaken utilizing high-resolution ILES data. Effective Reynolds numbers based on the vorticity and dissipation rate, or the integral and inner-viscous length scales, are found to be the most self-consistent when compared to the expected phenomenology andmore » wind tunnel experiments.« less

Theme II Joint Work Plan -2017 Collaboration and Knowledge Sharing on Large-scale Demonstration Projects

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

Zhang, Xiaoliang; Stauffer, Philip H.

This effort is designed to expedite learnings from existing and planned large demonstration projects and their associated research through effective knowledge sharing among participants in the US and China.

National Weatherization Assistance Program Impact Evaluation: Energy Impacts for Large Multifamily Buildings

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

Blasnik, Michael; Dalhoff, Greg; Carroll, David

This report estimates energy savings, energy cost savings, and cost effectiveness attributable to weatherizing large multifamily buildings under the auspices of the Department of Energy's Weatherization Assistance Program during Program Year 2008.

The influence of large-scale wind power on global climate.

PubMed

Keith, David W; Decarolis, Joseph F; Denkenberger, David C; Lenschow, Donald H; Malyshev, Sergey L; Pacala, Stephen; Rasch, Philip J

2004-11-16

Large-scale use of wind power can alter local and global climate by extracting kinetic energy and altering turbulent transport in the atmospheric boundary layer. We report climate-model simulations that address the possible climatic impacts of wind power at regional to global scales by using two general circulation models and several parameterizations of the interaction of wind turbines with the boundary layer. We find that very large amounts of wind power can produce nonnegligible climatic change at continental scales. Although large-scale effects are observed, wind power has a negligible effect on global-mean surface temperature, and it would deliver enormous global benefits by reducing emissions of CO(2) and air pollutants. Our results may enable a comparison between the climate impacts due to wind power and the reduction in climatic impacts achieved by the substitution of wind for fossil fuels.

Seismic safety in conducting large-scale blasts

NASA Astrophysics Data System (ADS)

Mashukov, I. V.; Chaplygin, V. V.; Domanov, V. P.; Semin, A. A.; Klimkin, M. A.

2017-09-01

In mining enterprises to prepare hard rocks for excavation a drilling and blasting method is used. With the approach of mining operations to settlements the negative effect of large-scale blasts increases. To assess the level of seismic impact of large-scale blasts the scientific staff of Siberian State Industrial University carried out expertise for coal mines and iron ore enterprises. Determination of the magnitude of surface seismic vibrations caused by mass explosions was performed using seismic receivers, an analog-digital converter with recording on a laptop. The registration results of surface seismic vibrations during production of more than 280 large-scale blasts at 17 mining enterprises in 22 settlements are presented. The maximum velocity values of the Earth’s surface vibrations are determined. The safety evaluation of seismic effect was carried out according to the permissible value of vibration velocity. For cases with exceedance of permissible values recommendations were developed to reduce the level of seismic impact.

Tropical warming and the dynamics of endangered primates.

PubMed

Wiederholt, Ruscena; Post, Eric

2010-04-23

Many primate species are severely threatened, but little is known about the effects of global warming and the associated intensification of El Niño events on primate populations. Here, we document the influences of the El Niño southern oscillation (ENSO) and hemispheric climatic variability on the population dynamics of four genera of ateline (neotropical, large-bodied) primates. All ateline genera experienced either an immediate or a lagged negative effect of El Niño events. ENSO events were also found to influence primate resource levels through neotropical arboreal phenology. Furthermore, frugivorous primates showed a high degree of interspecific population synchrony over large scales across Central and South America attributable to the recent trends in large-scale climate. These results highlight the role of large-scale climatic variation and trends in ateline primate population dynamics, and emphasize that global warming could pose additional threats to the persistence of multiple species of endangered primates.

Postinflationary Higgs relaxation and the origin of matter-antimatter asymmetry.

PubMed

Kusenko, Alexander; Pearce, Lauren; Yang, Louis

2015-02-13

The recent measurement of the Higgs boson mass implies a relatively slow rise of the standard model Higgs potential at large scales, and a possible second minimum at even larger scales. Consequently, the Higgs field may develop a large vacuum expectation value during inflation. The relaxation of the Higgs field from its large postinflationary value to the minimum of the effective potential represents an important stage in the evolution of the Universe. During this epoch, the time-dependent Higgs condensate can create an effective chemical potential for the lepton number, leading to a generation of the lepton asymmetry in the presence of some large right-handed Majorana neutrino masses. The electroweak sphalerons redistribute this asymmetry between leptons and baryons. This Higgs relaxation leptogenesis can explain the observed matter-antimatter asymmetry of the Universe even if the standard model is valid up to the scale of inflation, and any new physics is suppressed by that high scale.

Parallel computing for probabilistic fatigue analysis

NASA Technical Reports Server (NTRS)

Sues, Robert H.; Lua, Yuan J.; Smith, Mark D.

1993-01-01

This paper presents the results of Phase I research to investigate the most effective parallel processing software strategies and hardware configurations for probabilistic structural analysis. We investigate the efficiency of both shared and distributed-memory architectures via a probabilistic fatigue life analysis problem. We also present a parallel programming approach, the virtual shared-memory paradigm, that is applicable across both types of hardware. Using this approach, problems can be solved on a variety of parallel configurations, including networks of single or multiprocessor workstations. We conclude that it is possible to effectively parallelize probabilistic fatigue analysis codes; however, special strategies will be needed to achieve large-scale parallelism to keep large number of processors busy and to treat problems with the large memory requirements encountered in practice. We also conclude that distributed-memory architecture is preferable to shared-memory for achieving large scale parallelism; however, in the future, the currently emerging hybrid-memory architectures will likely be optimal.

Large-current-controllable carbon nanotube field-effect transistor in electrolyte solution

NASA Astrophysics Data System (ADS)

Myodo, Miho; Inaba, Masafumi; Ohara, Kazuyoshi; Kato, Ryogo; Kobayashi, Mikinori; Hirano, Yu; Suzuki, Kazuma; Kawarada, Hiroshi

2015-05-01

Large-current-controllable carbon nanotube field-effect transistors (CNT-FETs) were fabricated with mm-long CNT sheets. The sheets, synthesized by remote-plasma-enhanced CVD, contained both single- and double-walled CNTs. Titanium was deposited on the sheet as source and drain electrodes, and an electrolyte solution was used as a gate electrode (solution gate) to apply a gate voltage to the CNTs through electric double layers formed around the CNTs. The drain current came to be well modulated as electrolyte solution penetrated into the sheets, and one of the solution gate CNT-FETs was able to control a large current of over 2.5 A. In addition, we determined the transconductance parameter per tube and compared it with values for other CNT-FETs. The potential of CNT sheets for applications requiring the control of large current is exhibited in this study.

Large enhancement of the spin Hall effect in Au by side-jump scattering on Ta impurities

NASA Astrophysics Data System (ADS)

Laczkowski, P.; Fu, Y.; Yang, H.; Rojas-Sánchez, J.-C.; Noel, P.; Pham, V. T.; Zahnd, G.; Deranlot, C.; Collin, S.; Bouard, C.; Warin, P.; Maurel, V.; Chshiev, M.; Marty, A.; Attané, J.-P.; Fert, A.; Jaffrès, H.; Vila, L.; George, J.-M.

2017-10-01

We present measurements of the spin Hall effect (SHE) in AuW and AuTa alloys for a large range of W or Ta concentrations by combining experiments on lateral spin valves and ferromagnetic-resonance/spin-pumping techniques. The main result is the identification of a large enhancement of the spin Hall angle (SHA) by the side-jump mechanism on Ta impurities, with a SHA as high as +0.5 (i.e., 50 % ) for about 10% of Ta. In contrast, the SHA in AuW does not exceed +0.15 and can be explained by intrinsic SHE of the alloy without significant extrinsic contribution from skew or side-jump scattering by W impurities. The AuTa alloys, as they combine a very large SHA with a moderate resistivity (smaller than 85 μ Ω cm ), are promising for spintronic devices exploiting the SHE.

Design of a broadband ultra-large area acoustic cloak based on a fluid medium

NASA Astrophysics Data System (ADS)

Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Jiang, Ping

2014-10-01

A broadband ultra-large area acoustic cloak based on fluid medium was designed and numerically implemented with homogeneous metamaterials according to the transformation acoustics. In the present work, fluid medium as the body of the inclusion could be tuned by changing the fluid to satisfy the variant acoustic parameters instead of redesign the whole cloak. The effective density and bulk modulus of the composite materials were designed to agree with the parameters calculated from the coordinate transformation methodology by using the effective medium theory. Numerical simulation results showed that the sound propagation and scattering signature could be controlled in the broadband ultra-large area acoustic invisibility cloak, and good cloaking performance has been achieved and physically realized with homogeneous materials. The broadband ultra-large area acoustic cloaking properties have demonstrated great potentials in the promotion of the practical applications of acoustic cloak.

Allogeneic cell therapy bioprocess economics and optimization: downstream processing decisions.

PubMed

Hassan, Sally; Simaria, Ana S; Varadaraju, Hemanthram; Gupta, Siddharth; Warren, Kim; Farid, Suzanne S

2015-01-01

To develop a decisional tool to identify the most cost effective process flowsheets for allogeneic cell therapies across a range of production scales. A bioprocess economics and optimization tool was built to assess competing cell expansion and downstream processing (DSP) technologies. Tangential flow filtration was generally more cost-effective for the lower cells/lot achieved in planar technologies and fluidized bed centrifugation became the only feasible option for handling large bioreactor outputs. DSP bottlenecks were observed at large commercial lot sizes requiring multiple large bioreactors. The DSP contribution to the cost of goods/dose ranged between 20-55%, and 50-80% for planar and bioreactor flowsheets, respectively. This analysis can facilitate early decision-making during process development.

Production of large resonant plasma volumes in microwave electron cyclotron resonance ion sources

DOEpatents

Alton, G.D.

1998-11-24

Microwave injection methods are disclosed for enhancing the performance of existing electron cyclotron resonance (ECR) ion sources. The methods are based on the use of high-power diverse frequency microwaves, including variable-frequency, multiple-discrete-frequency, and broadband microwaves. The methods effect large resonant ``volume`` ECR regions in the ion sources. The creation of these large ECR plasma volumes permits coupling of more microwave power into the plasma, resulting in the heating of a much larger electron population to higher energies, the effect of which is to produce higher charge state distributions and much higher intensities within a particular charge state than possible in present ECR ion sources. 5 figs.

Experimental determination of quantum-well lifetime effect on large-signal resonant tunneling diode switching time

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

Growden, Tyler A.; Berger, Paul R., E-mail: pberger@ieee.org; Brown, E. R.

An experimental determination is presented of the effect the quantum-well lifetime has on a large-signal resonant tunneling diode (RTD) switching time. Traditional vertical In{sub 0.53}Ga{sub 0.47}As/AlAs RTDs were grown, fabricated, and characterized. The switching time was measured with a high-speed oscilloscope and found to be close to the sum of the calculated RC-limited 10%–90% switching time and the quantum-well quasibound-state lifetime. This method displays experimental evidence that the two intrinsic resonant-tunneling characteristic times act independently, and that the quasibound-state lifetime then serves as a quantum-limit on the large-signal speed of RTDs.

Large scale static tests of a tilt-nacelle V/STOL propulsion/attitude control system

NASA Technical Reports Server (NTRS)

1978-01-01

The concept of a combined V/STOL propulsion and aircraft attitude control system was subjected to large scale engine tests. The tilt nacelle/attitude control vane package consisted of the T55 powered Hamilton Standard Q-Fan demonstrator. Vane forces, moments, thermal and acoustic characteristics as well as the effects on propulsion system performance were measured under conditions simulating hover in and out of ground effect.

The effects of reinforcement magnitude on skill acquisition for children with autism.

PubMed

Paden, Amber R; Kodak, Tiffany

2015-12-01

We examined the effects of reinforcement magnitude on skill acquisition during discrete-trial training. After conducting a magnitude preference assessment, we compared acquisition during conditions with large and small magnitudes of edible reinforcement to a praise-only condition. Although all participants showed a preference for the large-magnitude reinforcer, preference did not predict the magnitude that produced the fastest skill acquisition. © Society for the Experimental Analysis of Behavior.

Pollution monitoring of puget sound with honey bees.

PubMed

Bromenshenk, J J; Carlson, S R; Simpson, J C; Thomas, J M

1985-02-08

To show that honey bees are effective biological monitors of environmental contaminants over large geographic areas, beekeepers of Puget Sound, Washington, collected pollen and bees for chemical analysis. From these data, kriging maps of arsenic, cadmium, and fluoride were generated. Results, based on actual concentrations of contaminants in bee tissues, show that the greatest concentrations of contaminants occur close to Commencement Bay and that honey bees are effective as large-scale monitors.

Improved turbulence models based on large eddy simulation of homogeneous, incompressible turbulent flows

NASA Technical Reports Server (NTRS)

Bardino, J.; Ferziger, J. H.; Reynolds, W. C.

1983-01-01

The physical bases of large eddy simulation and subgrid modeling are studied. A subgrid scale similarity model is developed that can account for system rotation. Large eddy simulations of homogeneous shear flows with system rotation were carried out. Apparently contradictory experimental results were explained. The main effect of rotation is to increase the transverse length scales in the rotation direction, and thereby decrease the rates of dissipation. Experimental results are shown to be affected by conditions at the turbulence producing grid, which make the initial states a function of the rotation rate. A two equation model is proposed that accounts for effects of rotation and shows good agreement with experimental results. In addition, a Reynolds stress model is developed that represents the turbulence structure of homogeneous shear flows very well and can account also for the effects of system rotation.

Interferon γ limits the effectiveness of melanoma peptide vaccines.

PubMed

Cho, Hyun-Il; Lee, Young-Ran; Celis, Esteban

2011-01-06

The development of effective therapeutic vaccines to generate tumor-reactive cytotoxic T lymphocytes (CTLs) continues to be a top research priority. However, in spite of some promising results, there are no clear examples of vaccines that eradicate established tumors. Most vaccines are ineffective because they generate low numbers of CTLs and because numerous immunosuppressive factors abound in tumor-bearing hosts. We designed a peptide vaccine that produces large numbers of tumor-reactive CTLs in a mouse model of melanoma. Surprisingly, CTL tumor recognition and antitumor effects decreased in the presence of interferon γ (IFNγ), a cytokine that can provide therapeutic benefit. Tumors exposed to IFNγ evade CTLs by inducing large amounts of noncognate major histocompatibility complex class I molecules, which limit T-cell activation and effector function. Our results demonstrate that peptide vaccines can eradicate large, established tumors in circumstances under which the inhibitory activities of IFNγ are curtailed.

Theoretical study of thermopower behavior of LaFeO3 compound in high temperature region

NASA Astrophysics Data System (ADS)

Singh, Saurabh; Shastri, Shivprasad S.; Pandey, Sudhir K.

2018-04-01

The electronic structure and thermopower (α) behavior of LaFeO3 compound were investigated by combining the ab-initio electronic structures and Boltzmann transport calculations. LSDA plus Hubbard U (U = 5 eV) calculation on G-type anti-ferromagnetic (AFM) configuration gives an energy gap of ˜2 eV, which is very close to the experimentally reported energy gap. The calculated values of effective mass of holes (mh*) in valance band (VB) are found ˜4 times that of the effective mass of electrons (me*) in conduction band (CB). The large effective masses of holes are responsible for the large and positive thermopower exhibited by this compound. The calculated values of α using BoltzTraP code are found to be large and positive in the 300-1200 K temperature range, which is in agreement with the experimentally reported data.

On the enrichment of hydrophobic organic compounds in fog droplets

NASA Astrophysics Data System (ADS)

Valsaraj, K. T.; Thoma, G. J.; Reible, D. D.; Thibodeaux, L. J.

The unusual degree of enrichment of hydrophobic organics in fogwater droplets reported by several investigators can be interpreted as a result of (a) the effects of temperature correction on the reported enrichment factors, (b) the effects of colloidal organic matter (both filterable and non-filterable) in fog water and (c) the effects of the large air-water interfacial adsorption of neutral hydrophobic organics on the tiny fog droplets. The enrichment factor was directly correlated to the hydrophobicity (or the activity coefficient in water) of the compounds, as indicated by their octanol-water partition constants. Compounds with large octanol-water partition coefficients (high activity coefficients in water) showed the largest enrichment. Available experimental data on the adsorption of hydrophobic compounds at the air-water interface and on colloidal organic carbon were used to show that the large specific air-water interfacial areas of fog droplets contribute significantly to the enrichment factor.

High-frequency large-amplitude oscillations of a non-isothermal N/S boundary

NASA Astrophysics Data System (ADS)

Bezuglyj, A. I.; Shklovskij, V. A.

2016-10-01

Within the framework of a phenomenological approach based on the heat balance equation and the current dependence of the critical temperature of the superconductor, the effect of high-frequency current of large amplitude and arbitrary waveform on the non-isothermal balance of an oscillating N/S interface in a long superconductor was studied. Self-consistent average temperature field of the rapidly oscillating non-isothermal N/S boundary (heat kink) was introduced, which allowed us to go beyond the well-known concept of mean-square heating and consider the effect of the current waveform. With regard to experiments on the effects of high-power microwave radiation on the current-voltage (IV) characteristics of superconducting films, their classification was performed and the families of IV curves of inhomogeneous superconductors carrying a current containing a high-frequency component of large amplitude. Several IV curves exhibited a hysteresis of thermal nature.

Cost-effectiveness analysis of the treatment of large leiomyomas: laparoscopic assisted vaginal hysterectomy versus abdominal hysterectomy.

PubMed

Mittapalli, Raja; Fanning, James; Flora, Robert; Fenton, Bradford W

2007-05-01

The purpose of this study was to perform a cost-effectiveness analysis comparing the treatment of large leiomyomas by laparoscopic assisted vaginal hysterectomy (LAVH) versus abdominal hysterectomy (AH). Twenty consecutive LAVH were compared to 20 consecutive AH for leiomyoma > or = 250 g. Hospital costs were obtained through Healthcare cost accounting system. The 6 principles of cost-effectiveness analysis were used. The groups were similar in respect to age, weight, race, medical comorbidities, blood loss, and operative time. Median uterine weight (513 g) was approximately 20% > for LAVH. Length of stay and pain was significantly less for LAVH. Total hospital cost for AH was approximately 12% less expensive ($4394 vs $5023, P = .18). Because of multiple benefits of LAVH versus AH and no significant difference in cost, we believe LAVH is an acceptable treatment for large leiomyoma.

Status and ecological effects of the world's largest carnivores.

PubMed

Ripple, William J; Estes, James A; Beschta, Robert L; Wilmers, Christopher C; Ritchie, Euan G; Hebblewhite, Mark; Berger, Joel; Elmhagen, Bodil; Letnic, Mike; Nelson, Michael P; Schmitz, Oswald J; Smith, Douglas W; Wallach, Arian D; Wirsing, Aaron J

2014-01-10

Large carnivores face serious threats and are experiencing massive declines in their populations and geographic ranges around the world. We highlight how these threats have affected the conservation status and ecological functioning of the 31 largest mammalian carnivores on Earth. Consistent with theory, empirical studies increasingly show that large carnivores have substantial effects on the structure and function of diverse ecosystems. Significant cascading trophic interactions, mediated by their prey or sympatric mesopredators, arise when some of these carnivores are extirpated from or repatriated to ecosystems. Unexpected effects of trophic cascades on various taxa and processes include changes to bird, mammal, invertebrate, and herpetofauna abundance or richness; subsidies to scavengers; altered disease dynamics; carbon sequestration; modified stream morphology; and crop damage. Promoting tolerance and coexistence with large carnivores is a crucial societal challenge that will ultimately determine the fate of Earth's largest carnivores and all that depends upon them, including humans.

On The Evidence For Large-Scale Galactic Conformity In The Local Universe

NASA Astrophysics Data System (ADS)

Sin, Larry P. T.; Lilly, Simon J.; Henriques, Bruno M. B.

2017-10-01

We re-examine the observational evidence for large-scale (4 Mpc) galactic conformity in the local Universe, as presented in Kauffmann et al. We show that a number of methodological features of their analysis act to produce a misleadingly high amplitude of the conformity signal. These include a weighting in favour of central galaxies in very high density regions, the likely misclassification of satellite galaxies as centrals in the same high-density regions and the use of medians to characterize bimodal distributions. We show that the large-scale conformity signal in Kauffmann et al. clearly originates from a very small number of central galaxies in the vicinity of just a few very massive clusters, whose effect is strongly amplified by the methodological issues that we have identified. Some of these 'centrals' are likely misclassified satellites, but some may be genuine centrals showing a real conformity effect. Regardless, this analysis suggests that conformity on 4 Mpc scales is best viewed as a relatively short-range effect (at the virial radius) associated with these very large neighbouring haloes, rather than a very long-range effect (at tens of virial radii) associated with the relatively low-mass haloes that host the nominal central galaxies in the analysis. A mock catalogue constructed from a recent semi-analytic model shows very similar conformity effects to the data when analysed in the same way, suggesting that there is no need to introduce new physical processes to explain galactic conformity on 4 Mpc scales.

Biology relevant to space radiation

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

Fry, R J.M.

There are only very limited data on the health effects to humans from the two major components of the radiations in space, namely protons and heavy ions. As a result, predictions of the accompanying effects must be based either on (1) data generated through studies of experimental systems exposed on earth at rates and fluences higher than those in space, or (2) extrapolations from studies of gamma and x rays. Better information is needed about the doses, dose rates, and the energy and LET spectra of the radiations at the organ level that are anticipated to be encountered during extendedmore » space missions. In particular, there is a need for better estimates of the relationship between radiation quality and biological effects. In the case of deterministic effects, it is the threshold that is important. The possibility of the occurrence of a large solar particle event (SPE) requires that such effects be considered during extended space missions. Analyses suggest, however, that it is feasible to provide sufficient shielding so as to reduce such effects to acceptable levels, particularly if the dose rates can be limited. If these analyses prove correct, the primary biological risks will be the stochastic effects (latent cancer induction). The contribution of one large SPE to the risk of stochastic effects while undesirable will not be large in comparison to the potential total dose on a mission of long duration.« less

Determination of Interfacial Rheological Properties through Microgravity Oscillations of Bubbles and Drops

NASA Technical Reports Server (NTRS)

Nadim, Ali; Rush, Brian M.

2000-01-01

This report summarizes our derivations of analytical expressions for the frequencies and damping constants for small-amplitude axisymmetric shape oscillations of a liquid drop suspended in an immiscible fluid host in microgravity. In particular, this work addresses large Reynolds number shape oscillations and focuses on the surface rheological effects that arise from the presence of insoluble surfactants at the interface. Parameters characterizing viscous effects from the bulk phases, surface viscous effects, Marangoni effects from the surface advection and diffusion of surfactants, and the Gibbs elasticity are all considered and analyzed to determine the relative importance of each contribution. Supplementing the analytical treatment for small-amplitude oscillations, a numerical boundary integral equation formulation is developed for the study of large-amplittide axisymmetric oscillations of a drop in vacuum. The boundary integral formulation is an extension of classical potential flow theory and approximately accounts for viscous effects in the bulk fluid as well as the surface viscous and Marangoni effects resulting from an insoluble surfactant contaminating the interface. Theoretical and numerical results are presented for four distinct cases. These, range from the case when the effects of the surfactants are 'negligible' to 'large' when compared to the viscous effects in the bulk phases. The feasibility of the non-contact measurement of the surface parameters, using experimental observations for the oscillation frequencies and damping constants of drops and bubbles, is discussed.

Large-scale quarantine following biological terrorism in the United States: scientific examination, logistic and legal limits, and possible consequences.

PubMed

Barbera, J; Macintyre, A; Gostin, L; Inglesby, T; O'Toole, T; DeAtley, C; Tonat, K; Layton, M

2001-12-05

Concern for potential bioterrorist attacks causing mass casualties has increased recently. Particular attention has been paid to scenarios in which a biological agent capable of person-to-person transmission, such as smallpox, is intentionally released among civilians. Multiple public health interventions are possible to effect disease containment in this context. One disease control measure that has been regularly proposed in various settings is the imposition of large-scale or geographic quarantine on the potentially exposed population. Although large-scale quarantine has not been implemented in recent US history, it has been used on a small scale in biological hoaxes, and it has been invoked in federally sponsored bioterrorism exercises. This article reviews the scientific principles that are relevant to the likely effectiveness of quarantine, the logistic barriers to its implementation, legal issues that a large-scale quarantine raises, and possible adverse consequences that might result from quarantine action. Imposition of large-scale quarantine-compulsory sequestration of groups of possibly exposed persons or human confinement within certain geographic areas to prevent spread of contagious disease-should not be considered a primary public health strategy in most imaginable circumstances. In the majority of contexts, other less extreme public health actions are likely to be more effective and create fewer unintended adverse consequences than quarantine. Actions and areas for future research, policy development, and response planning efforts are provided.

An imperative need for global change research in tropical forests.

PubMed

Zhou, Xuhui; Fu, Yuling; Zhou, Lingyan; Li, Bo; Luo, Yiqi

2013-09-01

Tropical forests play a crucial role in regulating regional and global climate dynamics, and model projections suggest that rapid climate change may result in forest dieback or savannization. However, these predictions are largely based on results from leaf-level studies. How tropical forests respond and feedback to climate change is largely unknown at the ecosystem level. Several complementary approaches have been used to evaluate the effects of climate change on tropical forests, but the results are conflicting, largely due to confounding effects of multiple factors. Although altered precipitation and nitrogen deposition experiments have been conducted in tropical forests, large-scale warming and elevated carbon dioxide (CO2) manipulations are completely lacking, leaving many hypotheses and model predictions untested. Ecosystem-scale experiments to manipulate temperature and CO2 concentration individually or in combination are thus urgently needed to examine their main and interactive effects on tropical forests. Such experiments will provide indispensable data and help gain essential knowledge on biogeochemical, hydrological and biophysical responses and feedbacks of tropical forests to climate change. These datasets can also inform regional and global models for predicting future states of tropical forests and climate systems. The success of such large-scale experiments in natural tropical forests will require an international framework to coordinate collaboration so as to meet the challenges in cost, technological infrastructure and scientific endeavor.

Acute L-arginine supplementation has no effect on cardiovascular or thermoregulatory responses to rest, exercise, and recovery in the heat.

PubMed

Tyler, Christopher J; Coffey, Thomas R M; Hodges, Gary J

2016-02-01

To investigate the effect of acute L-arginine (L-ARG) supplementation on cardiovascular and thermoregulatory responses to rest, exercise, and recovery in the heat. Eight healthy men (age 27 ± 6 years; stature 176 ± 6 cm; body mass 76 ± 4 kg; maximal power output 237 ± 39 W) participated in a double-blind, crossover study, attending the laboratory for two experimental trials. On each occasion, participants consumed 500 ml of a black currant-flavoured cordial beverage 30 min before completing a 90 min experiment in the heat (35 °C and 50% rh). The experiment consisted of 30 min of seated rest, followed by 30 min submaximal cycling (60% maximal power output) and 30 min passive seated recovery. On one visit the drink contained 10 g of dissolved L-ARG while on the other visit it did not. L-ARG supplementation increased plasma L-ARG concentrations (peak +223 ± 80% after 60 min of the 90 min experiment); however, supplementation had no effect on rectal temperature, mean skin temperature, heart rate, arterial pressure, forearm skin vascular conductance, oxygen consumption or sweat loss at rest, during exercise, or during recovery in the heat (p > 0.05). Acute ingestion of 10 g L-ARG supplementation failed to elicit any changes in the cardiovascular or thermoregulatory responses to active or passive heat exposure in young, healthy males.

Effects of acute administration of nicotine, amphetamine, diazepam, morphine, and ethanol on risky decision-making in rats

PubMed Central

Mitchell, Marci R.; Vokes, Colin M.; Blankenship, Amy L.; Simon, Nicholas W.

2011-01-01

Rationale Most individuals can accurately assess the risks and rewards associated with choice alternatives and decide accordingly; however, drug users often display maladaptive decision-making, such that choices are biased toward excessively risky options. Objective The purpose of this study was to investigate the effects of a range of drugs of abuse on risky decision-making. Methods Male Long–Evans rats were trained in the Risky Decision-Making Task, in which they chose between two levers, one which produced a small, “safe” food reward and the other which produced a large, “risky” food reward. The large reward was accompanied by the risk of a mild footshock, the probability of which increased over the course of each test session (0%, 25%, 50%, 75%, and 100%). Results Nicotine (0.6 mg/kg) and amphetamine (1.5 mg/kg) caused a significant decrease in choice of the large risky reward (decreased risk taking). Diazepam (1.0 mg/kg) caused a significant increase in choice of the large risky reward (increased risk taking), whereas morphine (3.0 mg/kg) caused only a trend toward increased choice of the large risky reward. Ethanol had no effect on choice behavior. Conclusions These results show that acute administration of drugs of abuse can modulate risk taking in a drug-specific manner, either increasing or decreasing preference for highly rewarding, but risky, options. PMID:21638222

Application of a roughness-length representation to parameterize energy loss in 3-D numerical simulations of large rivers

NASA Astrophysics Data System (ADS)

Sandbach, S. D.; Lane, S. N.; Hardy, R. J.; Amsler, M. L.; Ashworth, P. J.; Best, J. L.; Nicholas, A. P.; Orfeo, O.; Parsons, D. R.; Reesink, A. J. H.; Szupiany, R. N.

2012-12-01

Recent technological advances in remote sensing have enabled investigation of the morphodynamics and hydrodynamics of large rivers. However, measuring topography and flow in these very large rivers is time consuming and thus often constrains the spatial resolution and reach-length scales that can be monitored. Similar constraints exist for computational fluid dynamics (CFD) studies of large rivers, requiring maximization of mesh- or grid-cell dimensions and implying a reduction in the representation of bedform-roughness elements that are of the order of a model grid cell or less, even if they are represented in available topographic data. These "subgrid" elements must be parameterized, and this paper applies and considers the impact of roughness-length treatments that include the effect of bed roughness due to "unmeasured" topography. CFD predictions were found to be sensitive to the roughness-length specification. Model optimization was based on acoustic Doppler current profiler measurements and estimates of the water surface slope for a variety of roughness lengths. This proved difficult as the metrics used to assess optimal model performance diverged due to the effects of large bedforms that are not well parameterized in roughness-length treatments. However, the general spatial flow patterns are effectively predicted by the model. Changes in roughness length were shown to have a major impact upon flow routing at the channel scale. The results also indicate an absence of secondary flow circulation cells in the reached studied, and suggest simpler two-dimensional models may have great utility in the investigation of flow within large rivers.

Artificial intelligence issues related to automated computing operations

NASA Technical Reports Server (NTRS)

Hornfeck, William A.

1989-01-01

Large data processing installations represent target systems for effective applications of artificial intelligence (AI) constructs. The system organization of a large data processing facility at the NASA Marshall Space Flight Center is presented. The methodology and the issues which are related to AI application to automated operations within a large-scale computing facility are described. Problems to be addressed and initial goals are outlined.

Cost-effectiveness comparison of response strategies to a large-scale anthrax attack on the chicago metropolitan area: impact of timing and surge capacity.

PubMed

Kyriacou, Demetrios N; Dobrez, Debra; Parada, Jorge P; Steinberg, Justin M; Kahn, Adam; Bennett, Charles L; Schmitt, Brian P

2012-09-01

Rapid public health response to a large-scale anthrax attack would reduce overall morbidity and mortality. However, there is uncertainty about the optimal cost-effective response strategy based on timing of intervention, public health resources, and critical care facilities. We conducted a decision analytic study to compare response strategies to a theoretical large-scale anthrax attack on the Chicago metropolitan area beginning either Day 2 or Day 5 after the attack. These strategies correspond to the policy options set forth by the Anthrax Modeling Working Group for population-wide responses to a large-scale anthrax attack: (1) postattack antibiotic prophylaxis, (2) postattack antibiotic prophylaxis and vaccination, (3) preattack vaccination with postattack antibiotic prophylaxis, and (4) preattack vaccination with postattack antibiotic prophylaxis and vaccination. Outcomes were measured in costs, lives saved, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs). We estimated that postattack antibiotic prophylaxis of all 1,390,000 anthrax-exposed people beginning on Day 2 after attack would result in 205,835 infected victims, 35,049 fulminant victims, and 28,612 deaths. Only 6,437 (18.5%) of the fulminant victims could be saved with the existing critical care facilities in the Chicago metropolitan area. Mortality would increase to 69,136 if the response strategy began on Day 5. Including postattack vaccination with antibiotic prophylaxis of all exposed people reduces mortality and is cost-effective for both Day 2 (ICER=$182/QALY) and Day 5 (ICER=$1,088/QALY) response strategies. Increasing ICU bed availability significantly reduces mortality for all response strategies. We conclude that postattack antibiotic prophylaxis and vaccination of all exposed people is the optimal cost-effective response strategy for a large-scale anthrax attack. Our findings support the US government's plan to provide antibiotic prophylaxis and vaccination for all exposed people within 48 hours of the recognition of a large-scale anthrax attack. Future policies should consider expanding critical care capacity to allow for the rescue of more victims.

Cost-Effectiveness Comparison of Response Strategies to a Large-Scale Anthrax Attack on the Chicago Metropolitan Area: Impact of Timing and Surge Capacity

PubMed Central

Dobrez, Debra; Parada, Jorge P.; Steinberg, Justin M.; Kahn, Adam; Bennett, Charles L.; Schmitt, Brian P.

2012-01-01

Rapid public health response to a large-scale anthrax attack would reduce overall morbidity and mortality. However, there is uncertainty about the optimal cost-effective response strategy based on timing of intervention, public health resources, and critical care facilities. We conducted a decision analytic study to compare response strategies to a theoretical large-scale anthrax attack on the Chicago metropolitan area beginning either Day 2 or Day 5 after the attack. These strategies correspond to the policy options set forth by the Anthrax Modeling Working Group for population-wide responses to a large-scale anthrax attack: (1) postattack antibiotic prophylaxis, (2) postattack antibiotic prophylaxis and vaccination, (3) preattack vaccination with postattack antibiotic prophylaxis, and (4) preattack vaccination with postattack antibiotic prophylaxis and vaccination. Outcomes were measured in costs, lives saved, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs). We estimated that postattack antibiotic prophylaxis of all 1,390,000 anthrax-exposed people beginning on Day 2 after attack would result in 205,835 infected victims, 35,049 fulminant victims, and 28,612 deaths. Only 6,437 (18.5%) of the fulminant victims could be saved with the existing critical care facilities in the Chicago metropolitan area. Mortality would increase to 69,136 if the response strategy began on Day 5. Including postattack vaccination with antibiotic prophylaxis of all exposed people reduces mortality and is cost-effective for both Day 2 (ICER=$182/QALY) and Day 5 (ICER=$1,088/QALY) response strategies. Increasing ICU bed availability significantly reduces mortality for all response strategies. We conclude that postattack antibiotic prophylaxis and vaccination of all exposed people is the optimal cost-effective response strategy for a large-scale anthrax attack. Our findings support the US government's plan to provide antibiotic prophylaxis and vaccination for all exposed people within 48 hours of the recognition of a large-scale anthrax attack. Future policies should consider expanding critical care capacity to allow for the rescue of more victims. PMID:22845046

Choosing the Most Effective Pattern Classification Model under Learning-Time Constraint.

PubMed

Saito, Priscila T M; Nakamura, Rodrigo Y M; Amorim, Willian P; Papa, João P; de Rezende, Pedro J; Falcão, Alexandre X

2015-01-01

Nowadays, large datasets are common and demand faster and more effective pattern analysis techniques. However, methodologies to compare classifiers usually do not take into account the learning-time constraints required by applications. This work presents a methodology to compare classifiers with respect to their ability to learn from classification errors on a large learning set, within a given time limit. Faster techniques may acquire more training samples, but only when they are more effective will they achieve higher performance on unseen testing sets. We demonstrate this result using several techniques, multiple datasets, and typical learning-time limits required by applications.

Unsuppressed primordial standard clocks in warm quasi-single field inflation

NASA Astrophysics Data System (ADS)

Tong, Xi; Wang, Yi; Zhou, Siyi

2018-06-01

We study the non-Gaussianities in quasi-single field inflation with a warm inflation background. The thermal effects at small scales can sufficiently enhance the magnitude of the primordial standard clock signal. This scenario offers us the possibility of probing the UV physics of the very early universe without the exponentially small Boltzmann factor when the mass of the isocurvaton is much heavier than Hubble. The thermal effects at small scales can be studied using the flat space thermal field theory, connected to an effective description using non-Bunch-Davies vacuum at large scales, with large clock signal.

Some Aspects of Self-Field Effects in Large Vanadium-Based Josephson Junctions

NASA Astrophysics Data System (ADS)

Cristiano, R.; Russo, M.; Di Chiara, A.; Huang, Hesheng; Peluso, G.

1984-03-01

Experiments concerning large V-VxOy-Pb Josephson junctions have been performed. Structures having an overlap-type geometry have been considered. Preliminary experimental results are justified in the framework of the linearized current-phase model.

SAMPLING LARGE RIVERS FOR ALGAE, BENTHIC MACROINVERTEBRATES AND FISH

EPA Science Inventory

Multiple projects are currently underway to increase our understanding of the effects of different sampling methods and designs used for the biological assessment and monitoring of large (boatable) rivers. Studies include methods used to assess fish, benthic macroinvertebrates, ...

Large-scale shell-model study of the Sn isotopes

NASA Astrophysics Data System (ADS)

Osnes, Eivind; Engeland, Torgeir; Hjorth-Jensen, Morten

2015-05-01

We summarize the results of an extensive study of the structure of the Sn isotopes using a large shell-model space and effective interactions evaluated from realistic two-nucleon potentials. For a fuller account, see ref. [1].

Time for pulse traversal through slabs of dispersive and negative ({epsilon}, {mu}) materials

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

Nanda, Lipsa; Ramakrishna, S. Anantha

2007-12-15

The traversal times for an electromagnetic pulse traversing a slab of dispersive and dissipative material with negative dielectric permittivity ({epsilon}) and magnetic permeability ({mu}) have been calculated by using the average flow of electromagnetic energy in the medium. The effects of bandwidth of the pulse and dissipation in the medium have been investigated. While both large bandwidth and large dissipation have similar effects in smoothening out the resonant features that appear due to Fabry-Perot resonances, large dissipation can result in very small or even negative traversal times near the resonant frequencies. We have also investigated the traversal times and Wignermore » delay times for obliquely incident pulses and evanescent pulses. The coupling to slab plasmon-polariton modes in frequency ranges with negative {epsilon} or {mu} is shown to result in large traversal times at the resonant conditions. We also find that the group velocity mainly contributes to the delay times for pulses propagating across a slab with n=-1. We have checked that the traversal times are positive and subluminal for pulses with sufficiently large bandwidths.« less

Acicular photomultiplier photocathode structure

DOEpatents

Craig, Richard A.; Bliss, Mary

2003-09-30

A method and apparatus for increasing the quantum efficiency of a photomultiplier tube by providing a photocathode with an increased surface-to-volume ratio. The photocathode includes a transparent substrate, upon one major side of which is formed one or more large aspect-ratio structures, such as needles, cones, fibers, prisms, or pyramids. The large aspect-ratio structures are at least partially composed of a photoelectron emitting material, i.e., a material that emits a photoelectron upon absorption of an optical photon. The large aspect-ratio structures may be substantially composed of the photoelectron emitting material (i.e., formed as such upon the surface of a relatively flat substrate) or be only partially composed of a photoelectron emitting material (i.e., the photoelectron emitting material is coated over large aspect-ratio structures formed from the substrate material itself.) The large aspect-ratio nature of the photocathode surface allows for an effective increase in the thickness of the photocathode relative the absorption of optical photons, thereby increasing the absorption rate of incident photons, without substantially increasing the effective thickness of the photocathode relative the escape incidence of the photoelectrons.

Large electroweak penguin contribution in B{yields}K{pi} and {pi}{pi} decay modes

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

Mishima, Satoshi; Yoshikawa, Tadashi

2004-11-01

We discuss a possibility of large electroweak penguin contribution in B{yields}K{pi} and {pi}{pi} from recent experimental data. The experimental data may be suggesting that there are some discrepancies between the data and theoretical estimation in the branching ratios of them. In B{yields}K{pi} decays, to explain it, a large electroweak penguin contribution and large strong phase differences seem to be needed. The contributions should appear also in B{yields}{pi}{pi}. We show, as an example, a solution to solve the discrepancies in both B{yields}K{pi} and B{yields}{pi}{pi}. However the magnitude of the parameters and the strong phase estimated from experimental data are quite largemore » compared with the theoretical estimations. It may be suggesting some new physics effects are included in these processes. We will have to discuss about the dependence of the new physics. To explain both modes at once, we may need large electroweak penguin contribution with new weak phases and some SU(3) breaking effects by new physics in both QCD and electroweak penguin-type processes.« less

Responses of large mammals to climate change.

PubMed

Hetem, Robyn S; Fuller, Andrea; Maloney, Shane K; Mitchell, Duncan

2014-01-01

Most large terrestrial mammals, including the charismatic species so important for ecotourism, do not have the luxury of rapid micro-evolution or sufficient range shifts as strategies for adjusting to climate change. The rate of climate change is too fast for genetic adaptation to occur in mammals with longevities of decades, typical of large mammals, and landscape fragmentation and population by humans too widespread to allow spontaneous range shifts of large mammals, leaving only the expression of latent phenotypic plasticity to counter effects of climate change. The expression of phenotypic plasticity includes anatomical variation within the same species, changes in phenology, and employment of intrinsic physiological and behavioral capacity that can buffer an animal against the effects of climate change. Whether that buffer will be realized is unknown, because little is known about the efficacy of the expression of plasticity, particularly for large mammals. Future research in climate change biology requires measurement of physiological characteristics of many identified free-living individual animals for long periods, probably decades, to allow us to detect whether expression of phenotypic plasticity will be sufficient to cope with climate change.

Vulnerability of China's nearshore ecosystems under intensive mariculture development.

PubMed

Liu, Hui; Su, Jilan

2017-04-01

Rapid economic development and increasing population in China have exerted tremendous pressures on the coastal ecosystems. In addition to land-based pollutants and reclamation, fast expansion of large-scale intensive mariculture activities has also brought about additional effects. So far, the ecological impact of rapid mariculture development and its large-scale operations has not drawn enough attention. In this paper, the rapid development of mariculture in China is reviewed, China's effort in the application of ecological mariculture is examined, and the vulnerability of marine ecosystem to mariculture impact is evaluated through a number of examples. Removal or reduced large and forage fish, due to both habitat loss to reclamation/mariculture and overfishing for food or fishmeal, may have far-reaching effects on the coastal and shelf ecosystems in the long run. Large-scale intensive mariculture operations carry with them undesirable biological and biochemical characteristics, which may have consequences on natural ecosystems beyond normally perceived spatial and temporal boundaries. As our understanding of possible impacts of large-scale intensive mariculture is lagging far behind its development, much research is urgently needed.

Responses of large mammals to climate change

PubMed Central

Hetem, Robyn S; Fuller, Andrea; Maloney, Shane K; Mitchell, Duncan

2014-01-01

Most large terrestrial mammals, including the charismatic species so important for ecotourism, do not have the luxury of rapid micro-evolution or sufficient range shifts as strategies for adjusting to climate change. The rate of climate change is too fast for genetic adaptation to occur in mammals with longevities of decades, typical of large mammals, and landscape fragmentation and population by humans too widespread to allow spontaneous range shifts of large mammals, leaving only the expression of latent phenotypic plasticity to counter effects of climate change. The expression of phenotypic plasticity includes anatomical variation within the same species, changes in phenology, and employment of intrinsic physiological and behavioral capacity that can buffer an animal against the effects of climate change. Whether that buffer will be realized is unknown, because little is known about the efficacy of the expression of plasticity, particularly for large mammals. Future research in climate change biology requires measurement of physiological characteristics of many identified free-living individual animals for long periods, probably decades, to allow us to detect whether expression of phenotypic plasticity will be sufficient to cope with climate change. PMID:27583293

Paramagnetic Spin Seebeck Effect

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

Wu, Stephen M.; Pearson, John E.; Bhattacharya, Anand

2015-05-01

We report the observation of the longitudinal spin Seebeck effect in paramagnetic insulators. By using a microscale on-chip local heater, we generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. Using this technique at low temperatures (< 20 K), we resolve the paramagnetic spin Seebeck effect in the insulating paramagnets Gd3Ga5O12 (gadolinium gallium garnet) and DyScO3 (DSO), using either W or Pt as the spin detector layer. By taking advantage of the strong magnetocrystalline anisotropy of DSO, we eliminate contributions from the Nernst effect in W or Pt, which producesmore » a phenomenologically similar signal.« less

Light extraction from organic light-emitting diodes for lighting applications by sand-blasting substrates.

PubMed

Chen, Shuming; Kwok, Hoi Sing

2010-01-04

Light extraction from organic light-emitting diodes (OLEDs) by scattering the light is one of the effective methods for large-area lighting applications. In this paper, we present a very simple and cost-effective method to rough the substrates and hence to scatter the light. By simply sand-blasting the edges and back-side surface of the glass substrates, a 20% improvement of forward efficiency has been demonstrated. Moreover, due to scattering effect, a constant color over all viewing angles and uniform light pattern with Lambertian distribution has been obtained. This simple and cost-effective method may be suitable for mass production of large-area OLEDs for lighting applications.

Linking crop yield anomalies to large-scale atmospheric circulation in Europe.

PubMed

Ceglar, Andrej; Turco, Marco; Toreti, Andrea; Doblas-Reyes, Francisco J

2017-06-15

Understanding the effects of climate variability and extremes on crop growth and development represents a necessary step to assess the resilience of agricultural systems to changing climate conditions. This study investigates the links between the large-scale atmospheric circulation and crop yields in Europe, providing the basis to develop seasonal crop yield forecasting and thus enabling a more effective and dynamic adaptation to climate variability and change. Four dominant modes of large-scale atmospheric variability have been used: North Atlantic Oscillation, Eastern Atlantic, Scandinavian and Eastern Atlantic-Western Russia patterns. Large-scale atmospheric circulation explains on average 43% of inter-annual winter wheat yield variability, ranging between 20% and 70% across countries. As for grain maize, the average explained variability is 38%, ranging between 20% and 58%. Spatially, the skill of the developed statistical models strongly depends on the large-scale atmospheric variability impact on weather at the regional level, especially during the most sensitive growth stages of flowering and grain filling. Our results also suggest that preceding atmospheric conditions might provide an important source of predictability especially for maize yields in south-eastern Europe. Since the seasonal predictability of large-scale atmospheric patterns is generally higher than the one of surface weather variables (e.g. precipitation) in Europe, seasonal crop yield prediction could benefit from the integration of derived statistical models exploiting the dynamical seasonal forecast of large-scale atmospheric circulation.

Impacts of large herbivorous mammals on bird diversity and abundance in an African savanna.

PubMed

Ogada, D L; Gadd, M E; Ostfeld, R S; Young, T P; Keesing, F

2008-05-01

Large native mammals are declining dramatically in abundance across Africa, with strong impacts on both plant and animal community dynamics. However, the net effects of this large-scale loss in megafauna are poorly understood because responses by several ecologically important groups have not been assessed. We used a large-scale, replicated exclusion experiment in Kenya to investigate the impacts of different guilds of native and domestic large herbivores on the diversity and abundance of birds over a 2-year period. The exclusion of large herbivorous native mammals, including zebras (Equus burchelli), giraffes (Giraffa camelopardalis), elephants (Loxodonta africana), and buffalos (Syncerus caffer), increased the diversity of birds by 30%. Most of this effect was attributable to the absence of elephants and giraffes; these megaherbivores reduced both the canopy area of subdominant woody vegetation and the biomass of ground-dwelling arthropods, and both of these factors were good predictors of the diversity of birds. The canopy area of subdominant trees was positively correlated with the diversity of granivorous birds. The biomass of ground-dwelling arthropods was positively correlated with the diversity of insectivorous birds. Our results suggest that most native large herbivores are compatible with an abundant and diverse bird fauna, as are cattle if they are at a relatively low stocking rate. Future research should focus on determining the spatial arrangements and densities of megaherbivores that will optimize both megaherbivore abundance and bird diversity.

Demographic and Phenotypic Effects of Human Mediated Trophic Subsidy on a Large Australian Lizard (Varanus varius): Meal Ticket or Last Supper?

PubMed Central

Jessop, Tim S.; Smissen, Peter; Scheelings, Franciscus; Dempster, Tim

2012-01-01

Humans are increasingly subsidizing and altering natural food webs via changes to nutrient cycling and productivity. Where human trophic subsidies are concentrated and persistent within natural environments, their consumption could have complex consequences for wild animals through altering habitat preferences, phenotypes and fitness attributes that influence population dynamics. Human trophic subsidies conceptually create both costs and benefits for animals that receive increased calorific and altered nutritional inputs. Here, we evaluated the effects of a common terrestrial human trophic subsidies, human food refuse, on population and phenotypic (comprising morphological and physiological health indices) parameters of a large predatory lizard (∼2 m length), the lace monitor (Varanus varius), in southern Australia by comparison with individuals not receiving human trophic subsidies. At human trophic subsidies sites, lizards were significantly more abundant and their sex ratio highly male biased compared to control sites in natural forest. Human trophic subsidies recipient lizards were significantly longer, heavier and in much greater body condition. Blood parasites were significantly lower in human trophic subsidies lizards. Collectively, our results imply that human trophic subsidized sites were especially attractive to adult male lace monitors and had large phenotypic effects. However, we cannot rule out that the male-biased aggregations of large monitors at human trophic subsidized sites could lead to reductions in reproductive fitness, through mate competition and offspring survival, and through greater exposure of eggs and juveniles to predation. These possibilities could have negative population consequences. Aggregations of these large predators may also have flow on effects to surrounding food web dynamics through elevated predation levels. Given that flux of energy and nutrients into food webs is central to the regulation of populations and their communities, we advocate further studies of human trophic subsidies be undertaken to evaluate the potentially large ecological implications of this significant human environmental alteration. PMID:22509271

An Integrated Analysis of MicroRNA and mRNA Expression Profiles to Identify RNA Expression Signatures in Lambskin Hair Follicles in Hu Sheep

PubMed Central

Lv, Xiaoyang; Sun, Wei; Yin, Jinfeng; Ni, Rong; Su, Rui; Wang, Qingzeng; Gao, Wen; Bao, Jianjun; Yu, Jiarui; Wang, Lihong; Chen, Ling

2016-01-01

Wave patterns in lambskin hair follicles are an important factor determining the quality of sheep’s wool. Hair follicles in lambskin from Hu sheep, a breed unique to China, have 3 types of waves, designated as large, medium, and small. The quality of wool from small wave follicles is excellent, while the quality of large waves is considered poor. Because no molecular and biological studies on hair follicles of these sheep have been conducted to date, the molecular mechanisms underlying the formation of different wave patterns is currently unknown. The aim of this article was to screen the candidate microRNAs (miRNA) and genes for the development of hair follicles in Hu sheep. Two-day-old Hu lambs were selected from full-sib individuals that showed large, medium, and small waves. Integrated analysis of microRNA and mRNA expression profiles employed high-throughout sequencing technology. Approximately 13, 24, and 18 differentially expressed miRNAs were found between small and large waves, small and medium waves, and medium and large waves, respectively. A total of 54, 190, and 81 differentially expressed genes were found between small and large waves, small and medium waves, and medium and large waves, respectively, by RNA sequencing (RNA-seq) analysis. Differentially expressed genes were classified using gene ontology and pathway analyses. They were found to be mainly involved in cell differentiation, proliferation, apoptosis, growth, immune response, and ion transport, and were associated with MAPK and the Notch signaling pathway. Reverse transcription-polymerase chain reaction (RT-PCR) analyses of differentially-expressed miRNA and genes were consistent with sequencing results. Integrated analysis of miRNA and mRNA expression indicated that, compared to small waves, large waves included 4 downregulated miRNAs that had regulatory effects on 8 upregulated genes and 3 upregulated miRNAs, which in turn influenced 13 downregulated genes. Compared to small waves, medium waves included 13 downregulated miRNAs that had regulatory effects on 64 upregulated genes and 4 upregulated miRNAs, which in turn had regulatory effects on 22 downregulated genes. Compared to medium waves, large waves consisted of 13 upregulated miRNAs that had regulatory effects on 48 downregulated genes. These differentially expressed miRNAs and genes may play a significant role in forming different patterns, and provide evidence for the molecular mechanisms underlying the formation of hair follicles of varying patterns. PMID:27404636

Revisiting the cognitive buffer hypothesis for the evolution of large brains

PubMed Central

Sol, Daniel

2008-01-01

Why have some animals evolved large brains despite substantial energetic and developmental costs? A classic answer is that a large brain facilitates the construction of behavioural responses to unusual, novel or complex socioecological challenges. This buffer effect should increase survival rates and favour a longer reproductive life, thereby compensating for the costs of delayed reproduction. Although still limited, evidence in birds and mammals is accumulating that a large brain facilitates the construction of novel and altered behavioural patterns and that this ability helps dealing with new ecological challenges more successfully, supporting the cognitive-buffer interpretation of the evolution of large brains. PMID:19049952

Defaunation leads to microevolutionary changes in a tropical palm

PubMed Central

Carvalho, Carolina S.; Galetti, Mauro; Colevatti, Rosane G.; Jordano, Pedro

2016-01-01

Many large species have declined worldwide due to habitat fragmentation and poaching. The defaunation of large frugivores and the consequent reductions of seed dispersal services may have immediate effects on plant demography. Yet, the lasting effects of frugivore defaunation on microevolutionary processes of the plants they disperse remain understudied. We tested if the loss of large seed dispersers can lead to microevolutionary changes of a tropical palm. We show that frugivore defaunation is the main driver of changes in allelic frequency among populations. Turnover of alleles accounted for 100% of dissimilarity in allelic frequencies of individuals between defaunated and non-defaunated forests; and individuals from defaunated sites are 1.5 times more similar genetically than those found in pristine sites. Given that sizeable fractions of the palm fruit crops remain undispersed in defaunated sites due to lack of large-bodied frugivores, this distinct pattern of gene pool composition of early recruits may reveal strong dispersal limitation for specific genotypes, or collapses of gene flow between fragmented areas, or both. Because most of tropical tree species rely on seed dispersal by vertebrates, our results show that defaunation has a lasting effect on microevolutionary processes, with potential consequences for persistence under scenarios of environmental change. PMID:27535709

``Large''- vs Small-scale friction control in turbulent channel flow

NASA Astrophysics Data System (ADS)

Canton, Jacopo; Örlü, Ramis; Chin, Cheng; Schlatter, Philipp

2017-11-01

We reconsider the ``large-scale'' control scheme proposed by Hussain and co-workers (Phys. Fluids 10, 1049-1051 1998 and Phys. Rev. Fluids, 2, 62601 2017), using new direct numerical simulations (DNS). The DNS are performed in a turbulent channel at friction Reynolds number Reτ of up to 550 in order to eliminate low-Reynolds-number effects. The purpose of the present contribution is to re-assess this control method in the light of more modern developments in the field, in particular also related to the discovery of (very) large-scale motions. The goals of the paper are as follows: First, we want to better characterise the physics of the control, and assess what external contribution (vortices, forcing, wall motion) are actually needed. Then, we investigate the optimal parameters and, finally, determine which aspects of this control technique actually scale in outer units and can therefore be of use in practical applications. In addition to discussing the mentioned drag-reduction effects, the present contribution will also address the potential effect of the naturally occurring large-scale motions on frictional drag, and give indications on the physical processes for potential drag reduction possible at all Reynolds numbers.

Formation of quantum spin Hall state on Si surface and energy gap scaling with strength of spin orbit coupling

DOE PAGES

Zhou, Miao; Ming, Wenmei; Liu, Zheng; ...

2014-11-19

For potential applications in spintronics and quantum computing, it is desirable to place a quantum spin Hall insulator [i.e., a 2D topological insulator (TI)] on a substrate while maintaining a large energy gap. Here, we demonstrate a unique approach to create the large-gap 2D TI state on a semiconductor surface, based on first-principles calculations and effective Hamiltonian analysis. We show that when heavy elements with strong spin orbit coupling (SOC) such as Bi and Pb atoms are deposited on a patterned H-Si(111) surface into a hexagonal lattice, they exhibit a 2D TI state with a large energy gap of ≥0.5more » eV. The TI state arises from an intriguing substrate orbital filtering effect that selects a suitable orbital composition around the Fermi level, so that the system can be matched onto a four-band effective model Hamiltonian. Furthermore, it is found that within this model, the SOC gap does not increase monotonically with the increasing strength of SOC. These interesting results may shed new light in future design and fabrication of large-gap topological quantum states.« less

Formation of quantum spin Hall state on Si surface and energy gap scaling with strength of spin orbit coupling.

PubMed

Zhou, Miao; Ming, Wenmei; Liu, Zheng; Wang, Zhengfei; Yao, Yugui; Liu, Feng

2014-11-19

For potential applications in spintronics and quantum computing, it is desirable to place a quantum spin Hall insulator [i.e., a 2D topological insulator (TI)] on a substrate while maintaining a large energy gap. Here, we demonstrate a unique approach to create the large-gap 2D TI state on a semiconductor surface, based on first-principles calculations and effective Hamiltonian analysis. We show that when heavy elements with strong spin orbit coupling (SOC) such as Bi and Pb atoms are deposited on a patterned H-Si(111) surface into a hexagonal lattice, they exhibit a 2D TI state with a large energy gap of ≥ 0.5 eV. The TI state arises from an intriguing substrate orbital filtering effect that selects a suitable orbital composition around the Fermi level, so that the system can be matched onto a four-band effective model Hamiltonian. Furthermore, it is found that within this model, the SOC gap does not increase monotonically with the increasing strength of SOC. These interesting results may shed new light in future design and fabrication of large-gap topological quantum states.

Animal water balance drives top-down effects in a riparian forest—implications for terrestrial trophic cascades

PubMed Central

Sabo, John L.

2016-01-01

Despite the clear importance of water balance to the evolution of terrestrial life, much remains unknown about the effects of animal water balance on food webs. Based on recent research suggesting animal water imbalance can increase trophic interaction strengths in cages, we hypothesized that water availability could drive top-down effects in open environments, influencing the occurrence of trophic cascades. We manipulated large spider abundance and water availability in 20 × 20 m open-air plots in a streamside forest in Arizona, USA, and measured changes in cricket and small spider abundance and leaf damage. As expected, large spiders reduced both cricket abundance and herbivory under ambient, dry conditions, but not where free water was added. When water was added (free or within moist leaves), cricket abundance was unaffected by large spiders, but spiders still altered herbivory, suggesting behavioural effects. Moreover, we found threshold-type increases in herbivory at moderately low soil moisture (between 5.5% and 7% by volume), suggesting the possibility that water balance may commonly influence top-down effects. Overall, our results point towards animal water balance as an important driver of direct and indirect species interactions and food web dynamics in terrestrial ecosystems. PMID:27534953

The effect of numbers of noise events on people's reactions to noise - An analysis of existing survey data

NASA Technical Reports Server (NTRS)

Fields, J. M.

1984-01-01

Even though there are surveys in which annoyance decreases as the number of events increases above about 150 a day, the available evidence is not considered strong enough to reject the conventional assumption that reactions are related to the logarithm of the number of events. The data do not make it possible to reject the conventional assumption that the effects of the number of events and the peak noise level are additive. It is found that even when equivalent questionnaire items and definitions of noise events could be used, differences between the surveys' estimates of the effect of the number of events remained large. Three explanations are suggested for inconsistent estimates. The first has to do with errors in specifying the values of noise parameters, the second with the effects of unmeasured acoustical and area characteristics that are correlated with noise level or number, and the third with large sampling errors deriving from community differences in response to noise. It is concluded that significant advances in the knowledge about the effects of the number of noise events can be made only if surveys include large numbers of study areas.

Pollution monitoring of Puget Sound with honey bees

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

Bromenshenk, J.J.; Carlson, S.R.; Simpson, J.C.

To show that honey bees are effective biological monitors of environmental contaminants over large geographic areas, beekeepers of Puget Sound, Washington, collected pollen and bees for chemical analysis. From these data, kriging maps of arsenic, cadmium, and fluoride were generated. Results, based on actual concentrations of contaminants in bee tissues, show that the greatest concentrations of contaminants occur close to Commencement Bay and that honey bees are effective as large-scale monitors. 27 references, 2 figures.