PHOTONICS AND NANOTECHNOLOGY Laser-induced modification of transparent crystals and glasses

NASA Astrophysics Data System (ADS)

Bulgakova, N. M.; Stoian, Razvan; Rosenfeld, A.

2010-12-01

We analyse the processes taking place in transparent crystals and glasses irradiated by ultrashort laser pulses in the regimes typical of various applications in optoelectronics and photonics. We consider some phenomena, which have been previously described by the authors within the different model representations: charging of the dielectric surface due to electron photoemission resulting in a Coulomb explosion; crater shaping by using an adaptive control of the laser pulse shape; optimisation of the waveguide writing in materials strongly resistant to laser-induced compaction under ordinary irradiation conditions. The developed models and analysis of the processes relying on these models include the elements of the solid-state physics, plasma physics, thermodynamics, theory of elasticity and plasticity. Some important experimental observations which require explanations and adequate description are summarised.

Complete Moment Tensor Determination of Induced Seismicity in Unconventional and Conventional Oil/Gas Fields

NASA Astrophysics Data System (ADS)

Gu, C.; Li, J.; Toksoz, M. N.

2013-12-01

Induced seismicity occurs both in conventional oil/gas fields due to production and water injection and in unconventional oil/gas fields due to hydraulic fracturing. Source mechanisms of these induced earthquakes are of great importance for understanding their causes and the physics of the seismic processes in reservoirs. Previous research on the analysis of induced seismic events in conventional oil/gas fields assumed a double couple (DC) source mechanism. However, recent studies have shown a non-negligible percentage of a non-double-couple (non-DC) component of source moment tensor in hydraulic fracturing events (Šílený et al., 2009; Warpinski and Du, 2010; Song and Toksöz, 2011). In this study, we determine the full moment tensor of the induced seismicity data in a conventional oil/gas field and for hydrofrac events in an unconventional oil/gas field. Song and Toksöz (2011) developed a full waveform based complete moment tensor inversion method to investigate a non-DC source mechanism. We apply this approach to the induced seismicity data from a conventional gas field in Oman. In addition, this approach is also applied to hydrofrac microseismicity data monitored by downhole geophones in four wells in US. We compare the source mechanisms of induced seismicity in the two different types of gas fields and explain the differences in terms of physical processes.

Numerical analysis of quantitative measurement of hydroxyl radical concentration using laser-induced fluorescence in flame

NASA Astrophysics Data System (ADS)

Shuang, Chen; Tie, Su; Yao-Bang, Zheng; Li, Chen; Ting-Xu, Liu; Ren-Bing, Li; Fu-Rong, Yang

2016-06-01

The aim of the present work is to quantitatively measure the hydroxyl radical concentration by using LIF (laser-induced fluorescence) in flame. The detailed physical models of spectral absorption lineshape broadening, collisional transition and quenching at elevated pressure are built. The fine energy level structure of the OH molecule is illustrated to understand the process with laser-induced fluorescence emission and others in the case without radiation, which include collisional quenching, rotational energy transfer (RET), and vibrational energy transfer (VET). Based on these, some numerical results are achieved by simulations in order to evaluate the fluorescence yield at elevated pressure. These results are useful for understanding the real physical processes in OH-LIF technique and finding a way to calibrate the signal for quantitative measurement of OH concentration in a practical combustor. Project supported by the National Natural Science Foundation of China (Grant No. 11272338) and the Fund from the Science and Technology on Scramjet Key Laboratory, China (Grant No. STSKFKT2013004).

A cyber physical system approach for composite part: From smart manufacturing to predictive maintenance

NASA Astrophysics Data System (ADS)

Quaranta, Giacomo; Abisset-Chavanne, Emmanuelle; Chinesta, Francisco; Duval, Jean-Louis

2018-05-01

In this work, a Cyber Physical System called Hybrid Twin is proposed for composite parts manufactured from RTM. This allows to introduce in the virtual twin of the parts the defect and the final properties induced by the real manufacturing process and to use on line data collection for predictive maintenance.

Physical mechanisms in shock-induced turbulent separated flow

NASA Astrophysics Data System (ADS)

Dolling, D. S.

1987-12-01

It has been demonstrated that the flow downstream of the moving shock is separated and that the foot of the shock is effectively the instantaneous separation point. The shock induced turbulent separation is an intermittant process and the separation line indicated by surface tracer methods, such as kerosene-lampblack, is a downstream boundary of a region of intermittent separation.

How physiological and physical processes contribute to the phenology of cyanobacterial blooms in large shallow lakes: A new Euler-Lagrangian coupled model.

PubMed

Feng, Tao; Wang, Chao; Wang, Peifang; Qian, Jin; Wang, Xun

2018-09-01

Cyanobacterial blooms have emerged as one of the most severe ecological problems affecting large and shallow freshwater lakes. To improve our understanding of the factors that influence, and could be used to predict, surface blooms, this study developed a novel Euler-Lagrangian coupled approach combining the Eulerian model with agent-based modelling (ABM). The approach was subsequently verified based on monitoring datasets and MODIS data in a large shallow lake (Lake Taihu, China). The Eulerian model solves the Eulerian variables and physiological parameters, whereas ABM generates the complete life cycle and transport processes of cyanobacterial colonies. This model ensemble performed well in fitting historical data and predicting the dynamics of cyanobacterial biomass, bloom distribution, and area. Based on the calculated physical and physiological characteristics of surface blooms, principal component analysis (PCA) captured the major processes influencing surface bloom formation at different stages (two bloom clusters). Early bloom outbreaks were influenced by physical processes (horizontal transport and vertical turbulence-induced mixing), whereas buoyancy-controlling strategies were essential for mature bloom outbreaks. Canonical correlation analysis (CCA) revealed the combined actions of multiple environment variables on different bloom clusters. The effects of buoyancy-controlling strategies (ISP), vertical turbulence-induced mixing velocity of colony (VMT) and horizontal drift velocity of colony (HDT) were quantitatively compared using scenario simulations in the coupled model. VMT accounted for 52.9% of bloom formations and maintained blooms over long periods, thus demonstrating the importance of wind-induced turbulence in shallow lakes. In comparison, HDT and buoyancy controlling strategies influenced blooms at different stages. In conclusion, the approach developed here presents a promising tool for understanding the processes of onshore/offshore algal blooms formation and subsequent predicting. Copyright © 2018 Elsevier Ltd. All rights reserved.

Metal and polymer melt jet formation by the high-power laser ablation

NASA Astrophysics Data System (ADS)

Yoh, Jack J.; Gojani, Ardian B.

2010-02-01

The laser-induced metal and polymer melt jets are studied experimentally. Two classes of physical phenomena of interest are: first, the process of explosive phase change of laser induced surface ablation and second, the hydrodynamic jetting of liquid melts ejected from a beamed spot. We focus on the dynamic link between these two distinct physical phenomena in a framework of forming and patterning of metallic and polymer jets using a high-power Nd:YAG laser. The microexplosion of ablative spot on a target first forms a pocket of hot liquid melt and then it is followed by a sudden volume change of gas-liquid mixture leading to a pressure-induced spray jet ejection into surrounding medium.

Interplay between discharge physics, gas phase chemistry and surface processes in hydrocarbon plasmas

NASA Astrophysics Data System (ADS)

Hassouni, Khaled

2013-09-01

In this paper we present two examples that illustrate two different contexts of the interplay between plasma-surface interaction process and discharge physics and gas phase chemistry in hydrocarbon discharges. In the first example we address the case of diamond deposition processes and illustrate how a detailed investigation of the discharge physics, collisional processes and transport phenomena in the plasma phase make possible to accurately predict the key local-parameters, i.e., species density at the growing substrate, as function of the macroscopic process parameters, thus allowing for a precise control of diamond deposition process. In the second example, we illustrate how the interaction between a rare gas pristine discharge and carbon (graphite) electrode induce a dramatic change on the discharge nature, i.e., composition, ionization kinetics, charge equilibrium, etc., through molecular growth and clustering processes, solid particle formation and dusty plasma generation. Work done in collaboration with Alix Gicquel, Francois Silva, Armelle Michau, Guillaume Lombardi, Xavier Bonnin, Xavier Duten, CNRS, Universite Paris 13.

Future warming patterns linked to today’s climate variability

DOE PAGES

Dai, Aiguo

2016-01-11

The reliability of model projections of greenhouse gas (GHG)-induced future climate change is often assessed based on models’ ability to simulate the current climate, but there has been little evidence that connects the two. In fact, this practice has been questioned because the GHG-induced future climate change may involve additional physical processes that are not important for the current climate. Here I show that the spatial patterns of the GHG-induced future warming in the 21 st century is highly correlated with the patterns of the year-to-year variations of surface air temperature for today’s climate, with areas of larger variations duringmore » 1950–1979 having more GHG-induced warming in the 21 st century in all climate models. Such a relationship also exists in other climate fields such as atmospheric water vapor, and it is evident in observed temperatures from 1950–2010. The results suggest that many physical processes may work similarly in producing the year-to-year climate variations in the current climate and the GHG-induced long-term changes in the 21 st century in models and in the real world. Furthermore, they support the notion that models that simulate present-day climate variability better are likely to make more reliable predictions of future climate change.« less

Future warming patterns linked to today’s climate variability

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

Dai, Aiguo

The reliability of model projections of greenhouse gas (GHG)-induced future climate change is often assessed based on models’ ability to simulate the current climate, but there has been little evidence that connects the two. In fact, this practice has been questioned because the GHG-induced future climate change may involve additional physical processes that are not important for the current climate. Here I show that the spatial patterns of the GHG-induced future warming in the 21 st century is highly correlated with the patterns of the year-to-year variations of surface air temperature for today’s climate, with areas of larger variations duringmore » 1950–1979 having more GHG-induced warming in the 21 st century in all climate models. Such a relationship also exists in other climate fields such as atmospheric water vapor, and it is evident in observed temperatures from 1950–2010. The results suggest that many physical processes may work similarly in producing the year-to-year climate variations in the current climate and the GHG-induced long-term changes in the 21 st century in models and in the real world. Furthermore, they support the notion that models that simulate present-day climate variability better are likely to make more reliable predictions of future climate change.« less

Future Warming Patterns Linked to Today's Climate Variability.

PubMed

Dai, Aiguo

2016-01-11

The reliability of model projections of greenhouse gas (GHG)-induced future climate change is often assessed based on models' ability to simulate the current climate, but there has been little evidence that connects the two. In fact, this practice has been questioned because the GHG-induced future climate change may involve additional physical processes that are not important for the current climate. Here I show that the spatial patterns of the GHG-induced future warming in the 21(st) century is highly correlated with the patterns of the year-to-year variations of surface air temperature for today's climate, with areas of larger variations during 1950-1979 having more GHG-induced warming in the 21(st) century in all climate models. Such a relationship also exists in other climate fields such as atmospheric water vapor, and it is evident in observed temperatures from 1950-2010. The results suggest that many physical processes may work similarly in producing the year-to-year climate variations in the current climate and the GHG-induced long-term changes in the 21(st) century in models and in the real world. They support the notion that models that simulate present-day climate variability better are likely to make more reliable predictions of future climate change.

Performance of nanocomposites for preservation of artistic stones

NASA Astrophysics Data System (ADS)

Giancristofaro, Cristina; D'Amato, Rosaria; Caneve, Luisa; Pilloni, Luciano; Rinaldi, Antonio; Persia, Franca

2014-06-01

In this work, the effectiveness of nanocomposite surface treatments as protective systems for artistic stones was evaluated. Pyrolitic silica and titania nanoparticles were dispersed in a commercial silicon-based polymer and applied on marble and travertine samples. Artificial aging processes, both in climatic chamber and in solar box, were carried out to simulate real degradation processes in terms of photo-thermal effects and physical-chemical damage. The performances of the nanocomposites used as consolidant were evaluated comparatively by means of diverse diagnostic techniques, namely: scanning electron microscopy (SEM), laser induced fluorescence (LIF), ultrasonic technique, colorimetry, total immersion water absorption and contact angle. The results show that some properties of conservation materials can be improved by the presences of nanoparticles because they induce substantial changes of surface morphology of the coating layer and counter the physical damage observed during artificial weathering.

Personality traits and individual differences predict threat-induced changes in postural control.

PubMed

Zaback, Martin; Cleworth, Taylor W; Carpenter, Mark G; Adkin, Allan L

2015-04-01

This study explored whether specific personality traits and individual differences could predict changes in postural control when presented with a height-induced postural threat. Eighty-two healthy young adults completed questionnaires to assess trait anxiety, trait movement reinvestment (conscious motor processing, movement self-consciousness), physical risk-taking, and previous experience with height-related activities. Tests of static (quiet standing) and anticipatory (rise to toes) postural control were completed under low and high postural threat conditions. Personality traits and individual differences significantly predicted height-induced changes in static, but not anticipatory postural control. Individuals less prone to taking physical risks were more likely to lean further away from the platform edge and sway at higher frequencies and smaller amplitudes. Individuals more prone to conscious motor processing were more likely to lean further away from the platform edge and sway at larger amplitudes. Individuals more self-conscious about their movement appearance were more likely to sway at smaller amplitudes. Evidence is also provided that relationships between physical risk-taking and changes in static postural control are mediated through changes in fear of falling and physiological arousal. Results from this study may have indirect implications for balance assessment and treatment; however, further work exploring these factors in patient populations is necessary. Copyright © 2015 Elsevier B.V. All rights reserved.

Aloe vera bathing improved physical and humoral protection in breeding stock after induced spawning in matrinxã (Brycon amazonicus).

PubMed

Zanuzzo, Fábio S; Zaiden, Sérgio F; Senhorini, José A; Marzocchi-Machado, Cleni M; Urbinati, Elisabeth C

2015-07-01

In this study, we show that induced spawning causes stress, an intense loss of epithelia and immunosuppression, decreasing physical and humoral protection in fish, effects that were prevented or improved in fish bathed with Aloe vera. A. vera has several medicinal properties, including wound healing and immunostimulatory effects, which we observed in this study. Fish bathed with A. vera had a higher number of epidermal goblet cells and, in general, an improved wound healing rate compared with the control after induced spawning. These effects might be related to (1) the stimulation of leukocyte activity, represented here by the increased leukocyte respiratory activity triggered by A. vera (leukocytes are recognized as playing an important role in wound repair); (2) the antimicrobial properties of A. vera, which decrease wound infection and accelerate the healing process; and (3) several mechanisms that explain the healing effect of A. vera (increased collagen synthesis, rate of epithelialization, and anti-inflammatory and moisturizing effects). Our results also suggest that caution is necessary during the induced spawning process, especially during stripping, and A. vera bathing is recommended after intensive aquaculture operations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Violation of the 2nd Law of Thermodynamics in the Quantum Microworld

NASA Astrophysics Data System (ADS)

Čápek, V.; Frege, O.

2002-05-01

For one open quantum system recently reported to work as a perpetuum mobile of the second kind, basic equations providing basis for discussion of physics beyond the system activity are rederived in an appreciably simpler manner. The equations become exact in one specific scaling limit corresponding to the physical regime where internal processes (relaxations) in the system are commensurable or even slower than relaxation processes induced by bath. In the high-temperature (i.e. classical) limit, the system ceases to work, i.e., validity of the second law is reestablished.

α-induced reaction cross section measurements on 197Au

NASA Astrophysics Data System (ADS)

Szücs, Tamás; Gyürky, György; Halász, Zoltán; Kiss, Gábor Gy.; Fülöp, Zsolt

2018-01-01

The γ-process is responsible for creating the majority of the isotopes of heavier elements on the proton rich side of the valley of stability. The γ-process simulations fail to reproduce the measured solar system abundance of these isotopes. The problem can lie in the not well known astrophysical scenarios where the process takes place, or in the not sufficiently known nuclear physics input. To improve the latter part, α-induced reaction cross section measurements on 197Au were carried out at Atomki. With this dataset new experimental information will become available, which can be later used as validation of the theoretical cross section calculations used in the γ-process simulations.

Fast Adjustments of the Asian Summer Monsoon to Anthropogenic Aerosols

NASA Astrophysics Data System (ADS)

Li, Xiaoqiong; Ting, Mingfang; Lee, Dong Eun

2018-01-01

Anthropogenic aerosols are a major factor contributing to human-induced climate change, particularly over the densely populated Asian monsoon region. Understanding the physical processes controlling the aerosol-induced changes in monsoon rainfall is essential for reducing the uncertainties in the future projections of the hydrological cycle. Here we use multiple coupled and atmospheric general circulation models to explore the physical mechanisms for the aerosol-driven monsoon changes on different time scales. We show that anthropogenic aerosols induce an overall reduction in monsoon rainfall and circulation, which can be largely explained by the fast adjustments over land north of 20∘N. This fast response occurs before changes in sea surface temperature (SST), largely driven by aerosol-cloud interactions. However, aerosol-induced SST feedbacks (slow response) cause substantial changes in the monsoon meridional circulation over the oceanic regions. Both the land-ocean asymmetry and meridional temperature gradient are key factors in determining the overall monsoon circulation response.

The role of trophic factors and inflammatory processes in physical activity-induced neuroprotection in Parkinson's disease.

PubMed

Pałasz, Ewelina; Bąk, Agnieszka; Gąsiorowska, Anna; Niewiadomska, Grażyna

2017-01-04

Glial cells and neurotrophins play an important role in maintaining homeostasis of the CNS. Disturbances of their function can lead to a number of nervous system diseases, including Parkinson's disease (PD). Current clinical studies provide evidence that moderate physical activity adapted to the health status of PD patients can support pharmacological treatment, slow down the onset of motor impairments, and extend the patients period of independence. Physical activity, by stimulating the production and release of endogenous trophic factors, prevents the neurodegeneration of dopaminergic neurons via inhibition of inflammatory processes and the reduction of oxidative stress. The aim of this study is to present the current state of knowledge for the anti-inflammatory and neuroprotective properties of physical activity as a supportive therapy in Parkinson's disease.

A Comparison of Curing Process-Induced Residual Stresses and Cure Shrinkage in Micro-Scale Composite Structures with Different Constitutive Laws

NASA Astrophysics Data System (ADS)

Li, Dongna; Li, Xudong; Dai, Jianfeng; Xi, Shangbin

2018-02-01

In this paper, three kinds of constitutive laws, elastic, "cure hardening instantaneously linear elastic (CHILE)" and viscoelastic law, are used to predict curing process-induced residual stress for the thermoset polymer composites. A multi-physics coupling finite element analysis (FEA) model implementing the proposed three approaches is established in COMSOL Multiphysics-Version 4.3b. The evolution of thermo-physical properties with temperature and degree of cure (DOC), which improved the accuracy of numerical simulations, and cure shrinkage are taken into account for the three models. Subsequently, these three proposed constitutive models are implemented respectively in a 3D micro-scale composite laminate structure. Compared the differences between these three numerical results, it indicates that big error in residual stress and cure shrinkage generates by elastic model, but the results calculated by the modified CHILE model are in excellent agreement with those estimated by the viscoelastic model.

Performance of nanocomposites for preservation of artistic stones

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

Giancristofaro, Cristina; Pilloni, Luciano; Rinaldi, Antonio

2014-06-19

In this work, the effectiveness of nanocomposite surface treatments as protective systems for artistic stones was evaluated. Pyrolitic silica and titania nanoparticles were dispersed in a commercial silicon-based polymer and applied on marble and travertine samples. Artificial aging processes, both in climatic chamber and in solar box, were carried out to simulate real degradation processes in terms of photo-thermal effects and physical-chemical damage. The performances of the nanocomposites used as consolidant were evaluated comparatively by means of diverse diagnostic techniques, namely: scanning electron microscopy (SEM), laser induced fluorescence (LIF), ultrasonic technique, colorimetry, total immersion water absorption and contact angle. Themore » results show that some properties of conservation materials can be improved by the presences of nanoparticles because they induce substantial changes of surface morphology of the coating layer and counter the physical damage observed during artificial weathering.« less

Improved collagen extraction from jellyfish (Acromitus hardenbergi) with increased physical-induced solubilization processes.

PubMed

Khong, Nicholas M H; Yusoff, Fatimah Md; Jamilah, B; Basri, Mahiran; Maznah, I; Chan, Kim Wei; Armania, Nurdin; Nishikawa, Jun

2018-06-15

Efficiency and effectiveness of collagen extraction process contribute to huge impacts to the quality, supply and cost of the collagen produced. Jellyfish is a potential sustainable source of collagen where their applications are not limited by religious constraints and threats of transmittable diseases. The present study compared the extraction yield, physico-chemical properties and toxicology in vitro of collagens obtained by the conventional acid-assisted and pepsin-assisted extraction to an improved physical-aided extraction process. By increasing physical intervention, the production yield increased significantly compared to the conventional extraction processes (p < .05). Collagen extracted using the improved process was found to possess similar proximate and amino acids composition to those extracted using pepsin (p > .05) while retaining high molecular weight distributions and polypeptide profiles similar to those extracted using only acid. Moreover, they exhibited better appearance, instrumental colour and were found to be non-toxic in vitro and free of heavy metal contamination. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Middle Sacramento River: Human Impacts on Physical and Ecological Processes Along a Meandering River

Treesearch

Koll Buer; Dave Forwalter; Mike Kissel; Bill Stohlert

1989-01-01

Native plant and wildlife communities along Northern California's middle Sacramento River (Red Bluff to Colusa) originally adapted to a changing pattern of erosion and deposition across a broad meander belt. The erosion-deposition process was in balance, with the river alternately building and eroding terraces. Human-induced changes to the Sacramento River,...

Aerobic exercise modulates anticipatory reward processing via the μ-opioid receptor system.

PubMed

Saanijoki, Tiina; Nummenmaa, Lauri; Tuulari, Jetro J; Tuominen, Lauri; Arponen, Eveliina; Kalliokoski, Kari K; Hirvonen, Jussi

2018-06-08

Physical exercise modulates food reward and helps control body weight. The endogenous µ-opioid receptor (MOR) system is involved in rewarding aspects of both food and physical exercise, yet interaction between endogenous opioid release following exercise and anticipatory food reward remains unresolved. Here we tested whether exercise-induced opioid release correlates with increased anticipatory reward processing in humans. We scanned 24 healthy lean men after rest and after a 1 h session of aerobic exercise with positron emission tomography (PET) using MOR-selective radioligand [ 11 C]carfentanil. After both PET scans, the subjects underwent a functional magnetic resonance imaging (fMRI) experiment where they viewed pictures of palatable versus nonpalatable foods to trigger anticipatory food reward responses. Exercise-induced changes in MOR binding in key regions of reward circuit (amygdala, thalamus, ventral and dorsal striatum, and orbitofrontal and cingulate cortices) were used to predict the changes in anticipatory reward responses in fMRI. Exercise-induced changes in MOR binding correlated negatively with the exercise-induced changes in neural anticipatory food reward responses in orbitofrontal and cingulate cortices, insula, ventral striatum, amygdala, and thalamus: higher exercise-induced opioid release predicted higher brain responses to palatable versus nonpalatable foods. We conclude that MOR activation following exercise may contribute to the considerable interindividual variation in food craving and consumption after exercise, which might promote compensatory eating and compromise weight control. © 2018 Wiley Periodicals, Inc.

Breathing, bubbling, and bending: DNA flexibility from multimicrosecond simulations.

PubMed

Zeida, Ari; Machado, Matías Rodrigo; Dans, Pablo Daniel; Pantano, Sergio

2012-08-01

Bending of the seemingly stiff DNA double helix is a fundamental physical process for any living organism. Specialized proteins recognize DNA inducing and stabilizing sharp curvatures of the double helix. However, experimental evidence suggests a high protein-independent flexibility of DNA. On the basis of coarse-grained simulations, we propose that DNA experiences thermally induced kinks associated with the spontaneous formation of internal bubbles. Comparison of the protein-induced DNA curvature calculated from the Protein Data Bank with that sampled by our simulations suggests that thermally induced distortions can account for ~80% of the DNA curvature present in experimentally solved structures.

A critical literature review of focused electron beam induced deposition

NASA Astrophysics Data System (ADS)

van Dorp, W. F.; Hagen, C. W.

2008-10-01

An extensive review is given of the results from literature on electron beam induced deposition. Electron beam induced deposition is a complex process, where many and often mutually dependent factors are involved. The process has been studied by many over many years in many different experimental setups, so it is not surprising that there is a great variety of experimental results. To come to a better understanding of the process, it is important to see to which extent the experimental results are consistent with each other and with the existing model. All results from literature were categorized by sorting the data according to the specific parameter that was varied (current density, acceleration voltage, scan patterns, etc.). Each of these parameters can have an effect on the final deposit properties, such as the physical dimensions, the composition, the morphology, or the conductivity. For each parameter-property combination, the available data are discussed and (as far as possible) interpreted. By combining models for electron scattering in a solid, two different growth regimes, and electron beam induced heating, the majority of the experimental results were explained qualitatively. This indicates that the physical processes are well understood, although quantitatively speaking the models can still be improved. The review makes clear that several major issues remain. One issue encountered when interpreting results from literature is the lack of data. Often, important parameters (such as the local precursor pressure) are not reported, which can complicate interpretation of the results. Another issue is the fact that the cross section for electron induced dissociation is unknown. In a number of cases, a correlation between the vertical growth rate and the secondary electron yield was found, which suggests that the secondary electrons dominate the dissociation rather than the primary electrons. Conclusive evidence for this hypothesis has not been found. Finally, there is a limited understanding of the mechanism of electron induced precursor dissociation. In many cases, the deposit composition is not directly dependent on the stoichiometric composition of the precursor and the electron induced decomposition paths can be very different from those expected from calculations or thermal decomposition. The dissociation mechanism is one of the key factors determining the purity of the deposits and a better understanding of this process will help develop electron beam induced deposition into a viable nanofabrication technique.

Traffic-induced changes and processes in forest road aggregate particle-size distributions

Treesearch

Hakjun Rhee; James Fridley; Deborah Page-Dumroese

2018-01-01

Traffic can alter forest road aggregate material in various ways, such as by crushing, mixing it with subgrade material, and sweeping large-size, loose particles (gravel) toward the outside of the road. Understanding the changes and physical processes of the aggregate is essential to mitigate sediment production from forest roads and reduce road maintenance efforts. We...

Laser-induced thermoelastic effects can evoke tactile sensations

NASA Astrophysics Data System (ADS)

Jun, Jae-Hoon; Park, Jong-Rak; Kim, Sung-Phil; Min Bae, Young; Park, Jang-Yeon; Kim, Hyung-Sik; Choi, Seungmoon; Jung, Sung Jun; Hwa Park, Seung; Yeom, Dong-Il; Jung, Gu-In; Kim, Ji-Sun; Chung, Soon-Cheol

2015-06-01

Humans process a plethora of sensory information that is provided by various entities in the surrounding environment. Among the five major senses, technology for touch, haptics, is relatively young and has relatively limited applications largely due to its need for physical contact. In this article, we suggest a new way for non-contact haptic stimulation that uses laser, which has potential advantages such as mid-air stimulation, high spatial precision, and long working distance. We demonstrate such tactile stimulation can be enabled by laser-induced thermoelastic effects by means of physical and perceptual studies, as well as simulations. In the physical study, the mechanical effect of laser on a human skin sample is detected using low-power radiation in accordance with safety guidelines. Limited increases (< ~2.5 °C) in temperature at the surface of the skin, examined by both thermal camera and the Monte Carlo simulation, indicate that laser does not evoke heat-induced nociceptive sensation. In the human EEG study, brain responses to both mechanical and laser stimulation are consistent, along with subjective reports of the non-nociceptive sensation of laser stimuli.

Laser-induced thermoelastic effects can evoke tactile sensations.

PubMed

Jun, Jae-Hoon; Park, Jong-Rak; Kim, Sung-Phil; Min Bae, Young; Park, Jang-Yeon; Kim, Hyung-Sik; Choi, Seungmoon; Jung, Sung Jun; Hwa Park, Seung; Yeom, Dong-Il; Jung, Gu-In; Kim, Ji-Sun; Chung, Soon-Cheol

2015-06-05

Humans process a plethora of sensory information that is provided by various entities in the surrounding environment. Among the five major senses, technology for touch, haptics, is relatively young and has relatively limited applications largely due to its need for physical contact. In this article, we suggest a new way for non-contact haptic stimulation that uses laser, which has potential advantages such as mid-air stimulation, high spatial precision, and long working distance. We demonstrate such tactile stimulation can be enabled by laser-induced thermoelastic effects by means of physical and perceptual studies, as well as simulations. In the physical study, the mechanical effect of laser on a human skin sample is detected using low-power radiation in accordance with safety guidelines. Limited increases (< ~2.5 °C) in temperature at the surface of the skin, examined by both thermal camera and the Monte Carlo simulation, indicate that laser does not evoke heat-induced nociceptive sensation. In the human EEG study, brain responses to both mechanical and laser stimulation are consistent, along with subjective reports of the non-nociceptive sensation of laser stimuli.

Shoreline Change and Storm-Induced Beach Erosion Modeling: A Collection of Seven Papers

DTIC Science & Technology

1990-03-01

reducing, and analyzing the data in a systematic manner. Most physical data needed for evaluating and interpreting shoreline and beach evolution processes...proposed development concepts using both physical and numerical models. b. Analyzed and interpreted model results. c. Provided technical documentation of... interpret study results in the context required for "Confirmation" hearings. 26 The Corps of Engineers, Los Angeles District (SPL), has also begun studies

Influence of physical exercise on traumatic brain injury deficits: scaffolding effect.

PubMed

Archer, Trevor

2012-05-01

Traumatic brain injury (TBI) may be due to a bump, blow, or jolt to the head or a penetrating head injury that disrupts normal brain function; it presents an ever-growing, serious public health problem that causes a considerable number of fatalities and cases of permanent disability annually. Physical exercise restores the healthy homeostatic regulation of stress, affect and the regulation of hypothalamic-pituitary-adrenal axis. Physical activity attenuates or reverses the performance deficits observed in neurocognitive tasks. It induces anti-apoptotic effects and buttresses blood-brain barrier intactness. Exercise offers a unique non-pharmacologic, non-invasive intervention that incorporates different regimes, whether dynamic or static, endurance, or resistance. Exercise intervention protects against vascular risk factors that include hypertension, diabetes, cellular inflammation, and aortic rigidity. It induces direct changes in cerebrovasculature that produce beneficial changes in cerebral blood flow, angiogenesis and vascular disease improvement. The improvements induced by physical exercise regimes in brain plasticity and neurocognitive performance are evident both in healthy individuals and in those afflicted by TBI. The overlap and inter-relations between TBI effects on brain and cognition as related to physical exercise and cognition may provide lasting therapeutic benefits for recovery from TBI. It seems likely that some modification of the notion of scaffolding would postulate that physical exercise reinforces the adaptive processes of the brain that has undergone TBI thereby facilitating the development of existing networks, albeit possibly less efficient, that compensate for those lost through damage. © Springer Science+Business Media, LLC 2011

EEG Brain Activity in Dynamic Health Qigong Training: Same Effects for Mental Practice and Physical Training?

PubMed

Henz, Diana; Schöllhorn, Wolfgang I

2017-01-01

In recent years, there has been significant uptake of meditation and related relaxation techniques, as a means of alleviating stress and fostering an attentive mind. Several electroencephalogram (EEG) studies have reported changes in spectral band frequencies during Qigong meditation indicating a relaxed state. Much less is reported on effects of brain activation patterns induced by Qigong techniques involving bodily movement. In this study, we tested whether (1) physical Qigong training alters EEG theta and alpha activation, and (2) mental practice induces the same effect as a physical Qigong training. Subjects performed the dynamic Health Qigong technique Wu Qin Xi (five animals) physically and by mental practice in a within-subjects design. Experimental conditions were randomized. Two 2-min (eyes-open, eyes-closed) EEG sequences under resting conditions were recorded before and immediately after each 15-min exercise. Analyses of variance were performed for spectral power density data. Increased alpha power was found in posterior regions in mental practice and physical training for eyes-open and eyes-closed conditions. Theta power was increased after mental practice in central areas in eyes-open conditions, decreased in fronto-central areas in eyes-closed conditions. Results suggest that mental, as well as physical Qigong training, increases alpha activity and therefore induces a relaxed state of mind. The observed differences in theta activity indicate different attentional processes in physical and mental Qigong training. No difference in theta activity was obtained in physical and mental Qigong training for eyes-open and eyes-closed resting state. In contrast, mental practice of Qigong entails a high degree of internalized attention that correlates with theta activity, and that is dependent on eyes-open and eyes-closed resting state.

The Impact of Physical and Ergonomic Hazards on Poultry Abattoir Processing Workers: A Review.

PubMed

Harmse, Johannes L; Engelbrecht, Jacobus C; Bekker, Johan L

2016-02-06

The poultry abattoir industry continues to grow and contribute significantly to the gross domestic product in many countries. The industry expects working shifts of eight to eleven hours, during which workers are exposed to occupational hazards which include physical hazards ranging from noise, vibration, exposure to cold and ergonomic stress from manual, repetitive tasks that require force. A PubMed, Medline and Science Direct online database search, using specific keywords was conducted and the results confirmed that physical and ergonomic hazards impact on abattoir processing workers health, with harm not only to workers' health but also as an economic burden due to the loss of their livelihoods and the need for treatment and compensation in the industry. This review endeavours to highlight the contribution poultry processing plays in the development of physical agents and ergonomic stress related occupational diseases in poultry abattoir processing workers. The impact includes noise-induced hearing loss, increased blood pressure, menstrual and work related upper limb disorders. These are summarised as a quick reference guide for poultry abattoir owners, abattoir workers, poultry associations, occupational hygienists and medical practitioners to assist in the safer management of occupational health in poultry abattoirs.

The Impact of Physical and Ergonomic Hazards on Poultry Abattoir Processing Workers: A Review

PubMed Central

Harmse, Johannes L.; Engelbrecht, Jacobus C.; Bekker, Johan L.

2016-01-01

The poultry abattoir industry continues to grow and contribute significantly to the gross domestic product in many countries. The industry expects working shifts of eight to eleven hours, during which workers are exposed to occupational hazards which include physical hazards ranging from noise, vibration, exposure to cold and ergonomic stress from manual, repetitive tasks that require force. A PubMed, Medline and Science Direct online database search, using specific keywords was conducted and the results confirmed that physical and ergonomic hazards impact on abattoir processing workers health, with harm not only to workers’ health but also as an economic burden due to the loss of their livelihoods and the need for treatment and compensation in the industry. This review endeavours to highlight the contribution poultry processing plays in the development of physical agents and ergonomic stress related occupational diseases in poultry abattoir processing workers. The impact includes noise-induced hearing loss, increased blood pressure, menstrual and work related upper limb disorders. These are summarised as a quick reference guide for poultry abattoir owners, abattoir workers, poultry associations, occupational hygienists and medical practitioners to assist in the safer management of occupational health in poultry abattoirs. PMID:26861374

Human-induced geomorphic change across environmental gradients

NASA Astrophysics Data System (ADS)

Vanacker, V.; Molina, A.; Bellin, N.; Christl, M.

2016-12-01

Human-induced land cover changes are causing important adverse effects on the ecological services rendered by mountain ecosystems, and the number of case-studies of the impact of humans on soil erosion and sediment yield has mounted rapidly. Anthropogenic disturbance of natural vegetation can profoundly alter the physical, chemical and biological processes within soils. Rapid removal of topsoil during intense farming can result in an imbalance between soil production through chemical weathering and physical soil erosion, with direct implications on nutrient cycling, soil fertility and agricultural production. In this study, we present a conceptual model for assessing human-induced erosion for a wide variety of environmental settings and pose that human-induced geomorphic change cannot be assessed solely based on modern erosion rates as natural or baseline erosion rates can be important in e.g. mountainous terrain. As such, we assess the vulnerability of a given ecosystem to human-induced land cover change by quantifying the change in catchment-wide erosion rates resulting from anthropogenic changes in vegetation cover. Human-induced erosion is here approximated by the ratio of the total specific sediment yield to the natural erosional mass flux, and is dimensionless. The conceptual model is applied to three contrasting environmental settings where data on soil production, physical soil erosion and long-term denudation are available: the tropical Andes, subtropical southern Brazil, and semi-arid Spanish Cordillera. The magnitude of human-induced geomorphic change strongly differs between the three regions. The data suggest that the sensitivity to human-induced erosion is ecosystem dependent, and related to soil erosivity and potential vegetation cover disturbances as a result of human impact. It may therefore be expected that the potential for erosion regulation is larger in well-vegetated ecosystem where strong differences may exist in vegetation cover between human disturbed and undisturbed or restored sites.

Physical Processes and Real-Time Chemical Measurement of the Insect Olfactory Environment

PubMed Central

Abrell, Leif; Hildebrand, John G.

2009-01-01

Odor-mediated insect navigation in airborne chemical plumes is vital to many ecological interactions, including mate finding, flower nectaring, and host locating (where disease transmission or herbivory may begin). After emission, volatile chemicals become rapidly mixed and diluted through physical processes that create a dynamic olfactory environment. This review examines those physical processes and some of the analytical technologies available to characterize those behavior-inducing chemical signals at temporal scales equivalent to the olfactory processing in insects. In particular, we focus on two areas of research that together may further our understanding of olfactory signal dynamics and its processing and perception by insects. First, measurement of physical atmospheric processes in the field can provide insight into the spatiotemporal dynamics of the odor signal available to insects. Field measurements in turn permit aspects of the physical environment to be simulated in the laboratory, thereby allowing careful investigation into the links between odor signal dynamics and insect behavior. Second, emerging analytical technologies with high recording frequencies and field-friendly inlet systems may offer new opportunities to characterize natural odors at spatiotemporal scales relevant to insect perception and behavior. Characterization of the chemical signal environment allows the determination of when and where olfactory-mediated behaviors may control ecological interactions. Finally, we argue that coupling of these two research areas will foster increased understanding of the physicochemical environment and enable researchers to determine how olfactory environments shape insect behaviors and sensory systems. PMID:18548311

Numerical Investigations of Wave-Induced Mixing in Upper Ocean Layer

NASA Astrophysics Data System (ADS)

Guan, Changlong

2017-04-01

The upper ocean layer is playing an important role in ocean-atmosphere interaction. The typical characteristics depicting the upper ocean layer are the sea surface temperature (SST) and the mixed layer depth (MLD). So far, the existing ocean models tend to over-estimate SST and to under-estimate MLD, due to the inadequate mixing in the mixing layer, which is owing to that several processes related mixing in physics are ignored in these ocean models. The mixing induced by surface gravity wave is expected to be able to enhance the mixing in the upper ocean layer, and therefore the over-estimation of SST and the under-estimate of MLD could be improved by including wave-induced mixing. The wave-induced mixing could be accomplished by the physical mechanisms, such as wave breaking (WB), wave-induced Reynolds stress (WR), and wave-turbulence interaction (WT). The General Ocean Turbulence Model (GOTM) is employed to investigate the effects of the three mechanisms concerning wave-induced mixing. The numerical investigation is carried out for three turbulence closure schemes, say, k-epsilon, k-omega and Mellor-Yamada (1982), with the observational data from OSC Papa station and wave data from ECMWF. The mixing enhancement by various waved-induced mixing mechanisms is investigated and verified.

Understanding the role of floral development in the evolution of angiosperm flowers: clarifications from a historical and physico-dynamic perspective.

PubMed

Ronse De Craene, Louis

2018-05-01

Flower morphology results from the interaction of an established genetic program, the influence of external forces induced by pollination systems, and physical forces acting before, during and after initiation. Floral ontogeny, as the process of development from a meristem to a fully developed flower, can be approached either from a historical perspective, as a "recapitulation of the phylogeny" mainly explained as a process of genetic mutations through time, or from a physico-dynamic perspective, where time, spatial pressures, and growth processes are determining factors in creating the floral morphospace. The first (historical) perspective clarifies how flower morphology is the result of development over time, where evolutionary changes are only possible using building blocks that are available at a certain stage in the developmental history. Flowers are regulated by genetically determined constraints and development clarifies specific transitions between different floral morphs. These constraints are the result of inherent mutations or are induced by the interaction of flowers with pollinators. The second (physico-dynamic) perspective explains how changes in the physical environment of apical meristems create shifts in ontogeny and this is reflected in the morphospace of flowers. Changes in morphology are mainly induced by shifts in space, caused by the time of initiation (heterochrony), pressure of organs, and alterations of the size of the floral meristem, and these operate independently or in parallel with genetic factors. A number of examples demonstrate this interaction and its importance in the establishment of different floral forms. Both perspectives are complementary and should be considered in the understanding of factors regulating floral development. It is suggested that floral evolution is the result of alternating bursts of physical constraints and genetic stabilization processes following each other in succession. Future research needs to combine these different perspectives in understanding the evolution of floral systems and their diversification.

Physical and mathematical modeling of antimicrobial photodynamic therapy

NASA Astrophysics Data System (ADS)

Bürgermeister, Lisa; López, Fernando Romero; Schulz, Wolfgang

2014-07-01

Antimicrobial photodynamic therapy (aPDT) is a promising method to treat local bacterial infections. The therapy is painless and does not cause bacterial resistances. However, there are gaps in understanding the dynamics of the processes, especially in periodontal treatment. This work describes the advances in fundamental physical and mathematical modeling of aPDT used for interpretation of experimental evidence. The result is a two-dimensional model of aPDT in a dental pocket phantom model. In this model, the propagation of laser light and the kinetics of the chemical reactions are described as coupled processes. The laser light induces the chemical processes depending on its intensity. As a consequence of the chemical processes, the local optical properties and distribution of laser light change as well as the reaction rates. The mathematical description of these coupled processes will help to develop treatment protocols and is the first step toward an inline feedback system for aPDT users.

Planetary magnetospheres

NASA Technical Reports Server (NTRS)

Hill, T. W.; Michel, F. C.

1975-01-01

Space-probe observations of planetary magnetospheres are discussed. Three different categories of planetary magnetospheres are identified (intrinsic slowly rotating, intrinsic rapidly rotating, and induced), and the characteristics of each type are outlined. The structure and physical processes of the magnetospheres of Mercury, Mars, and Jupiter are described, and possible configurations are presented for the Martian and Jovian ones. Expected magnetic moments are derived for Saturn, Uranus, and Neptune. Models are constructed for possible induced magnetospheres of the moon, Mercury, Venus, Mars, and Io.

Mechanisms of stress-induced cellular HSP72 release: implications for exercise-induced increases in extracellular HSP72.

PubMed

Lancaster, Graeme I; Febbraio, Mark A

2005-01-01

The heat shock proteins are a family of highly conserved proteins with critical roles in maintaining cellular homeostasis and in protecting the cell from stressful conditions. While the critical intracellular roles of heat shock proteins are undisputed, evidence suggests that the cell possess the necessary machinery to actively secrete specific heat shock proteins in response to cellular stress. In this review, we firstly discuss the evidence that physical exercise induces the release of heat shock protein 72 from specific tissues in humans. Importantly, it appears as though this release is the result of an active secretory process, as opposed to non-specific processes such as cell lysis. Next we discuss recent in vitro evidence that has identified a mechanistic basis for the observation that cellular stress induces the release of a specific subset of heat shock proteins. Importantly, while the classical protein secretory pathway does not seem to be involved in the stress-induced release of HSP72, we discuss the evidence that lipid-rafts and exosomes are important mediators of the stress-induced release of HSP72.

All-SPEEK flexible supercapacitor exploiting laser-induced graphenization

NASA Astrophysics Data System (ADS)

Lamberti, A.; Serrapede, M.; Ferraro, G.; Fontana, M.; Perrucci, F.; Bianco, S.; Chiolerio, A.; Bocchini, S.

2017-09-01

Flexible supercapacitors have emerged as one of the more promising and efficient space-saving energy storage system for portable and wearable electronics. Laser-induced graphenization has been recently proposed as a powerful and scalable method to directly convert a polymeric substrate into a 3D network of few layer graphene as high-performance supercapacitor electrode. Unfortunately this outstanding process has been reported to be feasible only for few thermoplastic polymers, strongly limiting its future developments. Here we show that laser induced graphenization of sulfonated poly(ether ether ketone) (SPEEK) can be obtained and the mechanism of this novel process is proposed. The resulting material can act at the same time as binder-free electrode and current collector. Moreover SPEEK is also used both as separator and polymeric electrolyte allowing the assembling of an all-SPEEK flexible supercapacitor. Chemico-physical characterization provides deep understanding of the laser-induced graphenization process, reported on this polymer for the first time, while the device performance studied by cyclic voltammetry, charging-discharging, and impedance spectroscopy prove the enormous potential of the proposed approach.

Physics based simulation of seismicity induced in the vicinity of a high-pressure fluid injection

NASA Astrophysics Data System (ADS)

McCloskey, J.; NicBhloscaidh, M.; Murphy, S.; O'Brien, G. S.; Bean, C. J.

2013-12-01

High-pressure fluid injection into subsurface is known, in some cases, to induce earthquakes in the surrounding volume. The increasing importance of ';fracking' as a potential source of hydrocarbons has made the seismic hazard from this effect an important issue the adjudication of planning applications and it is likely that poor understanding of the process will be used as justification of refusal of planning in Ireland and the UK. Here we attempt to understand some of the physical controls on the size and frequency of induced earthquakes using a physics-based simulation of the process and examine resulting earthquake catalogues The driver for seismicity in our simulations is identical to that used in the paper by Murphy et al. in this session. Fluid injection is simulated using pore fluid movement throughout a permeable layer from a high-pressure point source using a lattice Boltzmann scheme. Diffusivities and frictional parameters can be defined independently at individual nodes/cells allowing us to reproduce 3-D geological structures. Active faults in the model follow a fractal size distribution and exhibit characteristic event size, resulting in a power-law frequency-size distribution. The fluid injection is not hydraulically connected to the fault (i.e. fluid does not come into physical contact with the fault); however stress perturbations from the injection drive the seismicity model. The duration and pressure-time function of the fluid injection can be adjusted to model any given injection scenario and the rate of induced seismicity is controlled by the local structures and ambient stress field as well as by the stress perturbations resulting from the fluid injection. Results from the rate and state fault models of Murphy et al. are incorporated to include the effect of fault strengthening in seismically quite areas. Initial results show similarities with observed induced seismic catalogues. Seismicity is only induced where the active faults have not been rotated far from the ambient stress field; the ';structural keel' provided by the geology suppresses induction since the fluid induced stress levels are much smaller than the breaking strain of the host rocks. In addition, we observe a systematic increase in observed biggest magnitude event with time during any injection indicating that in none of our simulations is the maximum magnitude event observed; mmax is in fact not estimable from any of our simulations and is unlikely to be observed in any given injection scenario.

Electromelting of confined monolayer ice.

PubMed

Qiu, Hu; Guo, Wanlin

2013-05-10

In sharp contrast to the prevailing view that electric fields promote water freezing, here we show by molecular dynamics simulations that monolayer ice confined between two parallel plates can melt into liquid water under a perpendicularly applied electric field. The melting temperature of the monolayer ice decreases with the increasing strength of the external field due to the field-induced disruption of the water-wall interaction induced well-ordered network of the hydrogen bond. This electromelting process should add an important new ingredient to the physics of water.

The Climatological Annual Cycle of Satellite-derived Phytoplankton Pigments in the Alboran Sea: A Physical Interpretation

NASA Technical Reports Server (NTRS)

Garcia-Gorriz, E.; Carr, M. E.

1998-01-01

The circulation and upwelling processes (coastal and gyre-induced) that control the phytoplankton distribution in the Alboran sea are examined by analyzing monthly climatological patterns of Coastal Zone Color Scanner (CZCS) pigment concentrations, sea surface temperatures, winds, and seasonal geostrophic fields.

Comparative behavioral and protein study of salivary secretions in Homalodisca spp. sharpshooters (Hemiptera: Cicadellidae: Cicadellinae)

USDA-ARS?s Scientific Manuscript database

A novel brush-induced method to physically stimulate salivation was applied to the glassy-winged and smoke tree sharpshooters. This technique enabled the direct observation of salivary secretion processes, solidification of saliva and for collection of salivary secretions. For both species, brush...

Rising synchrony controls western North American ecosystems

Treesearch

Bryan A. Black; Peter van der Sleen; Emanuele Di Lorenzo; Daniel Griffin; William J. Sydeman; Jason B. Dunham; Ryan R. Rykaczewski; Marisol García-Reyes; Mohammad Safeeq; Ivan Arismendi; Steven J. Bograd

2018-01-01

Along the western margin of North America, the winter expression of the North Pacific High (NPH) strongly influences interannual variability in coastal upwelling, storm track position, precipitation, and river discharge. Coherence among these factors induces covariance among physical and biological processes across adjacent marine and terrestrial ecosystems. Here, we...

From bare to renormalized order parameter in gauge space: Structure and reactions

NASA Astrophysics Data System (ADS)

Potel, G.; Idini, A.; Barranco, F.; Vigezzi, E.; Broglia, R. A.

2017-09-01

It is not physically obvious why one can calculate with similar accuracy, as compared to the experimental data, the absolute cross section associated with two-nucleon transfer processes between members of pairing rotational bands, making use of simple BCS (constant matrix elements) or of many-body [Nambu-Gorkov (NG), nuclear field theory (NFT)] spectroscopic amplitudes. Restoration of spontaneous symmetry breaking and associated emergent generalized rigidity in gauge space provides the answer and points to a new emergence: A physical sum rule resulting from the intertwining of structure and reaction processes, closely connected with the central role induced pairing interaction plays in structure, together with the fact that successive transfer dominates Cooper pair tunneling.

Bubble driven quasioscillatory translational motion of catalytic micromotors.

PubMed

Manjare, Manoj; Yang, Bo; Zhao, Y-P

2012-09-21

A new quasioscillatory translational motion has been observed for big Janus catalytic micromotors with a fast CCD camera. Such motional behavior is found to coincide with both the bubble growth and burst processes resulting from the catalytic reaction, and the competition of the two processes generates a net forward motion. Detailed physical models have been proposed to describe the above processes. It is suggested that the bubble growth process imposes a growth force moving the micromotor forward, while the burst process induces an instantaneous local pressure depression pulling the micromotor backward. The theoretic predictions are consistent with the experimental data.

Bubble Driven Quasioscillatory Translational Motion of Catalytic Micromotors

NASA Astrophysics Data System (ADS)

Manjare, Manoj; Yang, Bo; Zhao, Y.-P.

2012-09-01

A new quasioscillatory translational motion has been observed for big Janus catalytic micromotors with a fast CCD camera. Such motional behavior is found to coincide with both the bubble growth and burst processes resulting from the catalytic reaction, and the competition of the two processes generates a net forward motion. Detailed physical models have been proposed to describe the above processes. It is suggested that the bubble growth process imposes a growth force moving the micromotor forward, while the burst process induces an instantaneous local pressure depression pulling the micromotor backward. The theoretic predictions are consistent with the experimental data.

Study of the effect of gamma irradiation on a commercial polycyclooctene I. Thermal and mechanical properties

NASA Astrophysics Data System (ADS)

García-Huete, N.; Laza, J. M.; Cuevas, J. M.; Vilas, J. L.; Bilbao, E.; León, L. M.

2014-09-01

A gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical, chemical and mechanical properties. Gamma irradiation originates free radicals able to induce chain scission or recombination of radicals, which induces annihilation, branching or crosslinking processes. The aim of this work is to research the structural, thermal and mechanical changes induced on a commercial polycyclooctene (PCO) when it is irradiated with a gamma source of 60Co at different doses (25-200 kGy). After gamma irradiation, gel content was determined by Soxhlet extraction in cyclohexane. Furthermore, thermal properties were evaluated before and after Soxhlet extraction by means of Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC), as well as mechanical properties were measured by Dynamic Mechanical Thermal Analysis (DMTA). The results showed the variations of the properties depending on the irradiation dose. Finally, a first approach to evaluate qualitatively the shape memory behaviour of all irradiated PCO samples was performed by a visually monitoring shape recovery process.

Oxidation-induced contraction and strengthening of boron fibers

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.; Wagner, T. C.

1981-01-01

An investigation of the physical and mechanical effects of thermal treatment in a controlled oxygen-argon atmosphere on boron fibers is reported, with attention to the optimization of such treatment as a secondary processing method for improvement of fiber strength. The strengthening mechanism is comprised of an oxidation-induced axial contraction of the fiber, accompanied by axial compression of strength-limiting flaws within the fiber's tungsten boride core. It was found that after an oxidation contraction of 0.3% near 900 C, and a slight surface etch near 100 C, the average tensile strength of 203-micron fibers increased from 500 to 800 ksi. Various physical observations are used to develop mechanistic models of oxidation, contraction, and the formation of new flaws in the boron sheath at contractions greater than 0.3%.

Redox Stimulation of Human THP-1 Monocytes in Response to Cold Physical Plasma.

PubMed

Bekeschus, Sander; Schmidt, Anke; Bethge, Lydia; Masur, Kai; von Woedtke, Thomas; Hasse, Sybille; Wende, Kristian

2016-01-01

In plasma medicine, cold physical plasma delivers a delicate mixture of reactive components to cells and tissues. Recent studies suggested a beneficial role of cold plasma in wound healing. Yet, the biological processes related to the redox modulation via plasma are not fully understood. We here used the monocytic cell line THP-1 as a model to test their response to cold plasma in vitro. Intriguingly, short term plasma treatment stimulated cell growth. Longer exposure only modestly compromised cell viability but apparently supported the growth of cells that were enlarged in size and that showed enhanced metabolic activity. A significantly increased mitochondrial content in plasma treated cells supported this notion. On THP-1 cell proteome level, we identified an increase of protein translation with key regulatory proteins being involved in redox regulation (hypoxia inducible factor 2α), differentiation (retinoic acid signaling and interferon inducible factors), and cell growth (Yin Yang 1). Regulation of inflammation is a key element in many chronic diseases, and we found a significantly increased expression of the anti-inflammatory heme oxygenase 1 (HMOX1) and of the neutrophil attractant chemokine interleukin-8 (IL-8). Together, these results foster the view that cold physical plasma modulates the redox balance and inflammatory processes in wound related cells.

Morphological computation and morphological control: steps toward a formal theory and applications.

PubMed

Füchslin, Rudolf M; Dzyakanchuk, Andrej; Flumini, Dandolo; Hauser, Helmut; Hunt, Kenneth J; Luchsinger, Rolf H; Reller, Benedikt; Scheidegger, Stephan; Walker, Richard

2013-01-01

Morphological computation can be loosely defined as the exploitation of the shape, material properties, and physical dynamics of a physical system to improve the efficiency of a computation. Morphological control is the application of morphological computing to a control task. In its theoretical part, this article sharpens and extends these definitions by suggesting new formalized definitions and identifying areas in which the definitions we propose are still inadequate. We go on to describe three ongoing studies, in which we are applying morphological control to problems in medicine and in chemistry. The first involves an inflatable support system for patients with impaired movement, and is based on macroscopic physics and concepts already tested in robotics. The two other case studies (self-assembly of chemical microreactors; models of induced cell repair in radio-oncology) describe processes and devices on the micrometer scale, in which the emergent dynamics of the underlying physical system (e.g., phase transitions) are dominated by stochastic processes such as diffusion.

Fabrication and Characterization of High Strength Al-Cu Alloys Processed Using Laser Beam Melting in Metal Powder Bed

NASA Astrophysics Data System (ADS)

Ahuja, Bhrigu; Karg, Michael; Nagulin, Konstantin Yu.; Schmidt, Michael

The proposed paper illustrates fabrication and characterization of high strength Aluminium Copper alloys processed using Laser Beam Melting process. Al-Cu alloys EN AW-2219 and EN AW-2618 are classified as wrought alloys and 2618 is typically considered difficult to weld. Laser Beam Melting (LBM) process from the family of Additive Manufacturing processes, has the unique ability to form fully dense complex 3D geometries using micro sized metallic powder in a layer by layer fabrication methodology. LBM process can most closely be associated to the conventional laser welding process, but has significant differences in terms of the typical laser intensities and scan speeds used. Due to the use of high intensities and fast scan speeds, the process induces extremely high heating and cooling rates. This property gives it a unique physical attribute and therefore its ability to process high strength Al-Cu alloys needs to be investigated. Experiments conducted during the investigations associate the induced energy density controlled by varying process parameters to the achieved relative densities of the fabricated 3D structures.

Structural changes induced by high-pressure processing in micellar casein and milk protein concentrates.

PubMed

Cadesky, Lee; Walkling-Ribeiro, Markus; Kriner, Kyle T; Karwe, Mukund V; Moraru, Carmen I

2017-09-01

Reconstituted micellar casein concentrates and milk protein concentrates of 2.5 and 10% (wt/vol) protein concentration were subjected to high-pressure processing at pressures from 150 to 450 MPa, for 15 min, at ambient temperature. The structural changes induced in milk proteins by high-pressure processing were investigated using a range of physical, physicochemical, and chemical methods, including dynamic light scattering, rheology, mid-infrared spectroscopy, scanning electron microscopy, proteomics, and soluble mineral analyses. The experimental data clearly indicate pressure-induced changes of casein micelles, as well as denaturation of serum proteins. Calcium-binding α S1 - and α S2 -casein levels increased in the soluble phase after all pressure treatments. Pressurization up to 350 MPa also increased levels of soluble calcium and phosphorus, in all samples and concentrations, whereas treatment at 450 MPa reduced the levels of soluble Ca and P. Experimental data suggest dissociation of calcium phosphate and subsequent casein micelle destabilization as a result of pressure treatment. Treatment of 10% micellar casein concentrate and 10% milk protein concentrate samples at 450 MPa resulted in weak, physical gels, which featured aggregates of uniformly distributed, casein substructures of 15 to 20 nm in diameter. Serum proteins were significantly denatured by pressures above 250 MPa. These results provide information on pressure-induced changes in high-concentration protein systems, and may inform the development on new milk protein-based foods with novel textures and potentially high nutritional quality, of particular interest being the soft gel structures formed at high pressure levels. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

[Using carnosine and natural antioxidants for the prophylaxis of acute post-loading oxidative stress].

PubMed

Rozhkova, E A; Ordzhonikidze, Z G; Druzhinin, A E; Seĭfulla, N R; Paniushkin, V V; Kuznetsov, Iu M

2007-01-01

The effects of a submaximum single physical load with a mixed aerobic-anaerobic character (combined rowing test) on the intensity of lipid peroxidation (LPO) processes, antioxidant state of the organism, and rheological properties of blood have been studied in a group of athletes. The administration of natural antioxidants significantly decreased the LPO stress induced by the physical load, reduced the suppression of the antioxidant system of the organism, and normalized the LPO-disturbed hemorheological parameters. Antioxidants such as carnosine, cytamine, and apilac can be used as non-doping means for the accelerated recovery and increase in the physical work capacity in athletes.

Smooth muscle tension induces invasive remodeling of the zebrafish intestine.

PubMed

Seiler, Christoph; Davuluri, Gangarao; Abrams, Joshua; Byfield, Fitzroy J; Janmey, Paul A; Pack, Michael

2012-01-01

The signals that initiate cell invasion are not well understood, but there is increasing evidence that extracellular physical signals play an important role. Here we show that epithelial cell invasion in the intestine of zebrafish meltdown (mlt) mutants arises in response to unregulated contractile tone in the surrounding smooth muscle cell layer. Physical signaling in mlt drives formation of membrane protrusions within the epithelium that resemble invadopodia, matrix-degrading protrusions present in invasive cancer cells. Knockdown of Tks5, a Src substrate that is required for invadopodia formation in mammalian cells blocked formation of the protrusions and rescued invasion in mlt. Activation of Src-signaling induced invadopodia-like protrusions in wild type epithelial cells, however the cells did not migrate into the tissue stroma, thus indicating that the protrusions were required but not sufficient for invasion in this in vivo model. Transcriptional profiling experiments showed that genes responsive to reactive oxygen species (ROS) were upregulated in mlt larvae. ROS generators induced invadopodia-like protrusions and invasion in heterozygous mlt larvae but had no effect in wild type larvae. Co-activation of oncogenic Ras and Wnt signaling enhanced the responsiveness of mlt heterozygotes to the ROS generators. These findings present the first direct evidence that invadopodia play a role in tissue cell invasion in vivo. In addition, they identify an inducible physical signaling pathway sensitive to redox and oncogenic signaling that can drive this process.

Smooth Muscle Tension Induces Invasive Remodeling of the Zebrafish Intestine

PubMed Central

Seiler, Christoph; Davuluri, Gangarao; Abrams, Joshua; Byfield, Fitzroy J.; Janmey, Paul A.; Pack, Michael

2012-01-01

The signals that initiate cell invasion are not well understood, but there is increasing evidence that extracellular physical signals play an important role. Here we show that epithelial cell invasion in the intestine of zebrafish meltdown (mlt) mutants arises in response to unregulated contractile tone in the surrounding smooth muscle cell layer. Physical signaling in mlt drives formation of membrane protrusions within the epithelium that resemble invadopodia, matrix-degrading protrusions present in invasive cancer cells. Knockdown of Tks5, a Src substrate that is required for invadopodia formation in mammalian cells blocked formation of the protrusions and rescued invasion in mlt. Activation of Src-signaling induced invadopodia-like protrusions in wild type epithelial cells, however the cells did not migrate into the tissue stroma, thus indicating that the protrusions were required but not sufficient for invasion in this in vivo model. Transcriptional profiling experiments showed that genes responsive to reactive oxygen species (ROS) were upregulated in mlt larvae. ROS generators induced invadopodia-like protrusions and invasion in heterozygous mlt larvae but had no effect in wild type larvae. Co-activation of oncogenic Ras and Wnt signaling enhanced the responsiveness of mlt heterozygotes to the ROS generators. These findings present the first direct evidence that invadopodia play a role in tissue cell invasion in vivo. In addition, they identify an inducible physical signaling pathway sensitive to redox and oncogenic signaling that can drive this process. PMID:22973180

Sestrins: novel antioxidant and AMPK-modulating functions regulated by exercise?

PubMed

Sanchis-Gomar, Fabian

2013-08-01

Oxidative stress results from damage to tissues caused by free radicals and is increased by exercise. Peroxiredoxins (PRXs) maintain the cellular reducing environment by scavenging intracellular hydrogen peroxide. It has been recently noted that physical exercise has a positive effect on the PRX system, exerting a protective effect against oxidative stress-induced damage. However, other compounds, such as sestrins (SESNs), a stress-inducible protein family with antioxidant properties, should also be considered in the function of PRXs. SESNs are clearly involved in the regeneration process of PRXs and therefore may also be modulated by physical exercise. In addition, SESNs are clearly involved in TOR, AMPK, p53, FoxO, and PRXs signaling pathways. The aforementioned pathways are implicated in aging processes by inducing an increased resistance to subsequent stress, thus delaying age-related changes, such as sarcopenia and frailty, and consequently promoting longevity. Likewise, exercise also modulates these pathways. In fact, exercise is one of the most important recommended strategies to prevent sarcopenia and frailty, increase longevity, and improve health in the elderly. Loss of SESNs can cause several chronic pathologies, such as fat accumulation, mitochondrial dysfunction, cardiac arrhythmia, and/or muscle degeneration. Accordingly, physical inactivity leads to accumulation of visceral fat and consequently the activation of a network of inflammatory pathways, which promote development of insulin resistance, atherosclerosis, neurodegeneration, and tumor growth. To date, the SESNs-exercise relationship has not been explored. However, this emerging family of stress proteins may be part of the redox-based adaptive response to exercise. Copyright © 2013 Wiley Periodicals, Inc.

The r-Java 2.0 code: nuclear physics

NASA Astrophysics Data System (ADS)

Kostka, M.; Koning, N.; Shand, Z.; Ouyed, R.; Jaikumar, P.

2014-08-01

Aims: We present r-Java 2.0, a nucleosynthesis code for open use that performs r-process calculations, along with a suite of other analysis tools. Methods: Equipped with a straightforward graphical user interface, r-Java 2.0 is capable of simulating nuclear statistical equilibrium (NSE), calculating r-process abundances for a wide range of input parameters and astrophysical environments, computing the mass fragmentation from neutron-induced fission and studying individual nucleosynthesis processes. Results: In this paper we discuss enhancements to this version of r-Java, especially the ability to solve the full reaction network. The sophisticated fission methodology incorporated in r-Java 2.0 that includes three fission channels (beta-delayed, neutron-induced, and spontaneous fission), along with computation of the mass fragmentation, is compared to the upper limit on mass fission approximation. The effects of including beta-delayed neutron emission on r-process yield is studied. The role of Coulomb interactions in NSE abundances is shown to be significant, supporting previous findings. A comparative analysis was undertaken during the development of r-Java 2.0 whereby we reproduced the results found in the literature from three other r-process codes. This code is capable of simulating the physical environment of the high-entropy wind around a proto-neutron star, the ejecta from a neutron star merger, or the relativistic ejecta from a quark nova. Likewise the users of r-Java 2.0 are given the freedom to define a custom environment. This software provides a platform for comparing proposed r-process sites.

Quantum Zeno Blockade for Next Generation Optical Switching in Fiber Systems

DTIC Science & Technology

2013-09-01

and utilized a self - referential quantum process tomography method to observe the Zeno effect in optical fiber using the ultrafast all- optical switch...controllable and can be used as a knob to study the core physics behind the Zeno-based switching. For this experiment, we developed a self - referential ...efficient optical communications. The quantum Zeno effect can be used to induce or inhibit optical switching through a variety of processes , all of

Molecular Growth Inside of Polycyclic Aromatic Hydrocarbon Clusters Induced by Ion Collisions.

PubMed

Delaunay, Rudy; Gatchell, Michael; Rousseau, Patrick; Domaracka, Alicja; Maclot, Sylvain; Wang, Yang; Stockett, Mark H; Chen, Tao; Adoui, Lamri; Alcamí, Manuel; Martín, Fernando; Zettergren, Henning; Cederquist, Henrik; Huber, Bernd A

2015-05-07

The present work combines experimental and theoretical studies of the collision between keV ion projectiles and clusters of pyrene, one of the simplest polycyclic aromatic hydrocarbons (PAHs). Intracluster growth processes induced by ion collisions lead to the formation of a wide range of new molecules with masses larger than that of the pyrene molecule. The efficiency of these processes is found to strongly depend on the mass and velocity of the incoming projectile. Classical molecular dynamics simulations of the entire collision process-from the ion impact (nuclear scattering) to the formation of new molecular species-reproduce the essential features of the measured molecular growth process and also yield estimates of the related absolute cross sections. More elaborate density functional tight binding calculations yield the same growth products as the classical simulations. The present results could be relevant to understand the physical chemistry of the PAH-rich upper atmosphere of Saturn's moon Titan.

Hierarchical Bayesian Modeling of Fluid-Induced Seismicity

NASA Astrophysics Data System (ADS)

Broccardo, M.; Mignan, A.; Wiemer, S.; Stojadinovic, B.; Giardini, D.

2017-11-01

In this study, we present a Bayesian hierarchical framework to model fluid-induced seismicity. The framework is based on a nonhomogeneous Poisson process with a fluid-induced seismicity rate proportional to the rate of injected fluid. The fluid-induced seismicity rate model depends upon a set of physically meaningful parameters and has been validated for six fluid-induced case studies. In line with the vision of hierarchical Bayesian modeling, the rate parameters are considered as random variables. We develop both the Bayesian inference and updating rules, which are used to develop a probabilistic forecasting model. We tested the Basel 2006 fluid-induced seismic case study to prove that the hierarchical Bayesian model offers a suitable framework to coherently encode both epistemic uncertainty and aleatory variability. Moreover, it provides a robust and consistent short-term seismic forecasting model suitable for online risk quantification and mitigation.

Multi-monochromatic imaging of defect-induced mix experiments at OMEGA

NASA Astrophysics Data System (ADS)

Mancini, Roberto; Johns, Heather; Joshi, Tirtha; Mayes, Daniel; Durmaz, Tunay; Nagayama, Taisuke; Hsu, Scott; Tregillis, Ian; Krasheninnikova, Natalia; Cobble, James; Murphy, Thomas; Shah, Rahul; Kyrala, George; Hakel, Peter; Bradley, Paul; Schmitt, Mark

2012-10-01

In a series of polar-drive implosions performed at OMEGA for the defect-induced mix experiment (DIME) campaign of Los Alamos National Laboratory, two identical multi-monochromatic imager (MMI) instruments were fielded to record gated, x-ray spectrally-resolved images of D-filled Ti-doped plastic shells. The shells included a defect on the equatorial plane to study defect-induced mix while no-defect shells were employed in reference shots. The MMI data recorded simultaneously along quasi-orthogonal lines-of-sight afforded unique observations of the implosion based on the K-shell spectral signatures of the Ti tracer. Several analysis techniques have been used to process the MMI data (T. Nagayama et al, J. App. Phys. 109, 093303 (2011)) in order to study defect-induced mixing by tracking the spatial distribution and state of the tracer. Comparisons were made with results from post-processed 2D and 3D simulations to provide further insight into the interpretation of the experimental results and to constrain the simulation physics model.

Uncertainties of simulated aerosol optical properties induced by assumptions on aerosol physical and chemical properties: an AQMEII-2 perspective

EPA Science Inventory

The calculation of aerosol optical properties from aerosol mass is a process subject to uncertainty related to necessary assumptions on the treatment of the chemical species mixing state, density, refractive index, and hygroscopic growth. In the framework of the AQMEII-2 model in...

Geochemical evidence for the formation of the Moon by impact induced fission of the proto-Earth

NASA Technical Reports Server (NTRS)

Waenke, H.; Dreibus, G.

1984-01-01

Geochemical evidence is discussed which advocates the theory that the Moon was formed by impact induced fission of the Earth. The Earth's mantle exhibits a number of geochemical peculiarities which make our planet a unique object in the solar system. Terrestrial basalts are compared with those from the Eucrite parent body and the Shergotty parent body. Also the Moon's composition is very close to the Earth's in all details except the lower FeO content which is explained. Evidence is discussed for the plausible physical process of formation of the Moon by impact induced fission. Also the theory that impact induced fission occurred at the moment at which accretion of the Earth was not totally complete is briefly discussed.

New trends in laser shock wave physics and applications

NASA Astrophysics Data System (ADS)

Peyre, Patrice; Carboni, Christelle; Sollier, Arnault; Berthe, Laurent; Richard, Caroline; de Los Rios, E.; Fabbro, Remy

2002-09-01

Recent applications for laser-induced shock waves have been demonstrated in the aeronautical and nuclear industries, due to the development of new generations of lasers that enable high cadency rates with rather small designs. In this paper, we first aim at making an overview on basic physical processes involved in Laser Shock Processing, and a presentation of pressure loadings generated by different laser conditions. In a second part, a specific focus is given to new ranges of applications like wear resistance, uniform and localized corrosion or modeling of fatigue behaviour after LSP. For instance it is demonstrated that the pitting corrosion behaviour of 316L steel in saline medium can be improved by laser-induced pure mechanical effects surrounding inclusions. It is also shown that wear rates of a 100Cr6 tool steel can be reduced after LSP provided applied pressures are kept below a material deposit threshold. Last but not least, the fatigue cracking behaviour of 2024-T351 aluminum alloy after LSP was improved and calculated through a computed program taking into account work hardening together with residual stress effects.

High Energy Vibration for Gas Piping

NASA Astrophysics Data System (ADS)

Lee, Gary Y. H.; Chan, K. B.; Lee, Aylwin Y. S.; Jia, ShengXiang

2017-07-01

In September 2016, a gas compressor in offshore Sarawak has its rotor changed out. Prior to this change-out, pipe vibration study was carried-out by the project team to evaluate any potential high energy pipe vibration problems at the compressor’s existing relief valve downstream pipes due to process condition changes after rotor change out. This paper covers high frequency acoustic excitation (HFAE) vibration also known as acoustic induced vibration (AIV) study and discusses detailed methodologies as a companion to the Energy Institute Guidelines for the avoidance of vibration induced fatigue failure, which is a common industry practice to assess and mitigate for AIV induced fatigue failure. Such detailed theoretical studies can help to minimize or totally avoid physical pipe modification, leading to reduce offshore plant shutdown days to plant shutdowns only being required to accommodate gas compressor upgrades, reducing cost without compromising process safety.

Multicomponent ensemble models to forecast induced seismicity

NASA Astrophysics Data System (ADS)

Király-Proag, E.; Gischig, V.; Zechar, J. D.; Wiemer, S.

2018-01-01

In recent years, human-induced seismicity has become a more and more relevant topic due to its economic and social implications. Several models and approaches have been developed to explain underlying physical processes or forecast induced seismicity. They range from simple statistical models to coupled numerical models incorporating complex physics. We advocate the need for forecast testing as currently the best method for ascertaining if models are capable to reasonably accounting for key physical governing processes—or not. Moreover, operational forecast models are of great interest to help on-site decision-making in projects entailing induced earthquakes. We previously introduced a standardized framework following the guidelines of the Collaboratory for the Study of Earthquake Predictability, the Induced Seismicity Test Bench, to test, validate, and rank induced seismicity models. In this study, we describe how to construct multicomponent ensemble models based on Bayesian weightings that deliver more accurate forecasts than individual models in the case of Basel 2006 and Soultz-sous-Forêts 2004 enhanced geothermal stimulation projects. For this, we examine five calibrated variants of two significantly different model groups: (1) Shapiro and Smoothed Seismicity based on the seismogenic index, simple modified Omori-law-type seismicity decay, and temporally weighted smoothed seismicity; (2) Hydraulics and Seismicity based on numerically modelled pore pressure evolution that triggers seismicity using the Mohr-Coulomb failure criterion. We also demonstrate how the individual and ensemble models would perform as part of an operational Adaptive Traffic Light System. Investigating seismicity forecasts based on a range of potential injection scenarios, we use forecast periods of different durations to compute the occurrence probabilities of seismic events M ≥ 3. We show that in the case of the Basel 2006 geothermal stimulation the models forecast hazardous levels of seismicity days before the occurrence of felt events.

Impact of physical permafrost processes on hydrological change

NASA Astrophysics Data System (ADS)

Hagemann, Stefan; Blome, Tanja; Beer, Christian; Ekici, Altug

2015-04-01

Permafrost or perennially frozen ground is an important part of the terrestrial cryosphere; roughly one quarter of Earth's land surface is underlain by permafrost. As it is a thermal phenomenon, its characteristics are highly dependent on climatic factors. The impact of the currently observed warming, which is projected to persist during the coming decades due to anthropogenic CO2 input, certainly has effects for the vast permafrost areas of the high northern latitudes. The quantification of these effects, however, is scientifically still an open question. This is partly due to the complexity of the system, where several feedbacks are interacting between land and atmosphere, sometimes counterbalancing each other. Moreover, until recently, many global circulation models (GCMs) and Earth system models (ESMs) lacked the sufficient representation of permafrost physics in their land surface schemes. Within the European Union FP7 project PAGE21, the land surface scheme JSBACH of the Max-Planck-Institute for Meteorology ESM (MPI-ESM) has been equipped with the representation of relevant physical processes for permafrost studies. These processes include the effects of freezing and thawing of soil water for both energy and water cycles, thermal properties depending on soil water and ice contents, and soil moisture movement being influenced by the presence of soil ice. In the present study, it will be analysed how these permafrost relevant processes impact projected hydrological changes over northern hemisphere high latitude land areas. For this analysis, the atmosphere-land part of MPI-ESM, ECHAM6-JSBACH, is driven by prescribed SST and sea ice in an AMIP2-type setup with and without the newly implemented permafrost processes. Observed SST and sea ice for 1979-1999 are used to consider induced changes in the simulated hydrological cycle. In addition, simulated SST and sea ice are taken from a MPI-ESM simulation conducted for CMIP5 following the RCP8.5 scenario. The corresponding simulations with ECHAM6-JSBACH are used to assess differences in projected hydrological changes induced by the permafrost relevant processes.

Cardiac looping may be driven by compressive loads resulting from unequal growth of the heart and pericardial cavity. Observations on a physical simulation model

PubMed Central

Bayraktar, Meriç; Männer, Jörg

2014-01-01

The transformation of the straight embryonic heart tube into a helically wound loop is named cardiac looping. Such looping is regarded as an essential process in cardiac morphogenesis since it brings the building blocks of the developing heart into an approximation of their definitive topographical relationships. During the past two decades, a large number of genes have been identified which play important roles in cardiac looping. However, how genetic information is physically translated into the dynamic form changes of the looping heart is still poorly understood. The oldest hypothesis of cardiac looping mechanics attributes the form changes of the heart loop (ventral bending → simple helical coiling → complex helical coiling) to compressive loads resulting from growth differences between the heart and the pericardial cavity. In the present study, we have tested the physical plausibility of this hypothesis, which we call the growth-induced buckling hypothesis, for the first time. Using a physical simulation model, we show that growth-induced buckling of a straight elastic rod within the confined space of a hemispherical cavity can generate the same sequence of form changes as observed in the looping embryonic heart. Our simulation experiments have furthermore shown that, under bilaterally symmetric conditions, growth-induced buckling generates left- and right-handed helices (D-/L-loops) in a 1:1 ratio, while even subtle left- or rightward displacements of the caudal end of the elastic rod at the pre-buckling state are sufficient to direct the buckling process toward the generation of only D- or L-loops, respectively. Our data are discussed with respect to observations made in biological “models.” We conclude that compressive loads resulting from unequal growth of the heart and pericardial cavity play important roles in cardiac looping. Asymmetric positioning of the venous heart pole may direct these forces toward a biased generation of D- or L-loops. PMID:24772086

Dislocation-Twin Boundary Interactions Induced Nanocrystalline via SPD Processing in Bulk Metals

NASA Astrophysics Data System (ADS)

Zhang, Fucheng; Feng, Xiaoyong; Yang, Zhinan; Kang, Jie; Wang, Tiansheng

2015-03-01

This report investigated dislocation-twin boundary (TB) interactions that cause the TB to disappear and turn into a high-angle grain boundary (GB). The evolution of the microstructural characteristics of Hadfield steel was shown as a function of severe plastic deformation processing time. Sessile Frank partial dislocations and/or sessile unit dislocations were formed on the TB through possible dislocation reactions. These reactions induced atomic steps on the TB and led to the accumulation of gliding dislocations at the TB, which resulted in the transition from coherent TB to incoherent GB. The factors that affect these interactions were described, and a physical model was established to explain in detail the feasible dislocation reactions at the TB.

Dislocation–Twin Boundary Interactions Induced Nanocrystalline via SPD Processing in Bulk Metals

PubMed Central

Zhang, Fucheng; Feng, Xiaoyong; Yang, Zhinan; Kang, Jie; Wang, Tiansheng

2015-01-01

This report investigated dislocation–twin boundary (TB) interactions that cause the TB to disappear and turn into a high-angle grain boundary (GB). The evolution of the microstructural characteristics of Hadfield steel was shown as a function of severe plastic deformation processing time. Sessile Frank partial dislocations and/or sessile unit dislocations were formed on the TB through possible dislocation reactions. These reactions induced atomic steps on the TB and led to the accumulation of gliding dislocations at the TB, which resulted in the transition from coherent TB to incoherent GB. The factors that affect these interactions were described, and a physical model was established to explain in detail the feasible dislocation reactions at the TB. PMID:25757550

Dislocation-twin boundary interactions induced nanocrystalline via SPD processing in bulk metals.

PubMed

Zhang, Fucheng; Feng, Xiaoyong; Yang, Zhinan; Kang, Jie; Wang, Tiansheng

2015-03-11

This report investigated dislocation-twin boundary (TB) interactions that cause the TB to disappear and turn into a high-angle grain boundary (GB). The evolution of the microstructural characteristics of Hadfield steel was shown as a function of severe plastic deformation processing time. Sessile Frank partial dislocations and/or sessile unit dislocations were formed on the TB through possible dislocation reactions. These reactions induced atomic steps on the TB and led to the accumulation of gliding dislocations at the TB, which resulted in the transition from coherent TB to incoherent GB. The factors that affect these interactions were described, and a physical model was established to explain in detail the feasible dislocation reactions at the TB.

Modifications of structural and physical properties induced by swift heavy ions in Gd2Ti2O7 and Y2Ti2O7 pyrochlores

NASA Astrophysics Data System (ADS)

Sellami, N.; Sattonnay, G.; Grygiel, C.; Monnet, I.; Debelle, A.; Legros, C.; Menut, D.; Miro, S.; Simon, P.; Bechade, J. L.; Thomé, L.

2015-12-01

The structural transformations induced by ionization processes in Gd2Ti2O7 and Y2Ti2O7 pyrochlores irradiated with swift heavy ions have been studied using XRD and Raman experiments. Results show that irradiation induces amorphization and that the phase transformation build-up can be accounted for in the framework of a model involving a single-impact mechanism. The radiation induced amorphization build-up is faster in Gd2Ti2O7 than in Y2Ti2O7. Moreover, a decrease of the thermal conductivity (measured by the laser flash method) is induced by irradiation both in Gd2Ti2O7 and Y2Ti2O7.

Impact Cratering Physics al Large Planetary Scales

NASA Astrophysics Data System (ADS)

Ahrens, Thomas J.

2007-06-01

Present understanding of the physics controlling formation of ˜10^3 km diameter, multi-ringed impact structures on planets were derived from the ideas of Scripps oceanographer, W. Van Dorn, University of London's, W, Murray, and, Caltech's, D. O'Keefe who modeled the vertical oscillations (gravity and elasticity restoring forces) of shock-induced melt and damaged rock within the transient crater immediately after the downward propagating hemispheric shock has processed rock (both lining, and substantially below, the transient cavity crater). The resulting very large surface wave displacements produce the characteristic concentric, multi-ringed basins, as stored energy is radiated away and also dissipated upon inducing further cracking. Initial calculational description, of the above oscillation scenario, has focused upon on properly predicting the resulting density of cracks, and, their orientations. A new numerical version of the Ashby--Sammis crack damage model is coupled to an existing shock hydrodynamics code to predict impact induced damage distributions in a series of 15--70 cm rock targets from high speed impact experiments for a range of impactor type and velocity. These are compared to results of crack damage distributions induced in crustal rocks with small arms impactors and mapped ultrasonically in recent Caltech experiments (Ai and Ahrens, 2006).

The role of inheritance in structuring hyperextended rift systems

NASA Astrophysics Data System (ADS)

Manatschal, Gianreto; Lavier, Luc; Chenin, Pauline

2015-04-01

A long-standing question in Earth Sciences is related to the importance of inheritance in controlling tectonic processes. In contrast to physical processes that are generally applicable, assessing the role of inheritance suffers from two major problems: firstly, it is difficult to appraise without having insights into the history of a geological system; and secondly all inherited features are not reactivated during subsequent deformation phases. Therefore, the aim of our presentation is to give some conceptual framework about how inheritance may control the architecture and evolution of hyperextended rift systems. We use the term inheritance to refer to the difference between an "ideal" layer-cake type lithosphere and a "real" lithosphere containing heterogeneities and we define 3 types of inheritance, namely structural, compositional and thermal inheritance. Moreover, we assume that the evolution of hyperextended rift systems reflects the interplay between their inheritance (innate/"genetic code") and the physical processes at play (acquired/external factors). Thus, by observing the architecture and evolution of hyperextended rift systems and integrating the physical processes, one my get hints on what may have been the original inheritance of a system. Using this approach, we focus on 3 well-studied rift systems that are the Alpine Tethys, Pyrenean-Bay of Biscay and Iberia-Newfoundland rift systems. For the studied examples we can show that: 1) strain localization on a local scale and during early stages of rifting is controlled by inherited structures and weaknesses 2) the architecture of the necking zone seems to be influenced by the distribution and importance of ductile layers during decoupled deformation and is consequently controlled by the thermal structure and/or the inherited composition of the curst 3) the location of breakup in the 3 examples is not significantly controlled by the inherited structures 4) inherited mantle composition and rift-related mantle processes may control the rheology of the mantle, the magmatic budget, the thermal structure and the localization of final rifting Conversely, the deformation in hyperextended domains is strongly controlled by weak hydrated minerals (e.g. clay, serpentinite) that result form the breakdown of feldspar and olivine due to fluid and reaction assisted deformation and is consequently not inherited but the result of rift induced processes. These key observations show that both inheritance and rift-induced processes play a significant role in the development of magma-poor rift systems and that the role of inheritance may change as the physical conditions vary during the evolving rifting and as rift-induced processes (serpentinization; magma) become more important. Thus, it is not only important to determine the "genetic code" of a rift system, but also to understand how it interacts and evolves during rifting. Understand how far these new ideas and concepts derived from the southern North Atlantic and Alpine Tethys can be translated to other less explored hyperextended rift systems will be one of the challenges of the future research in rifted margins.

The role of long-term physical exercise on performance and brain activation during the Stroop colour word task in fibromyalgia patients.

PubMed

Martinsen, S; Flodin, P; Berrebi, J; Löfgren, M; Bileviciute-Ljungar, I; Mannerkorpi, K; Ingvar, M; Fransson, P; Kosek, E

2018-05-01

The Stroop colour word test (SCWT) has been widely used to assess changes in cognitive performance such as processing speed, selective attention and the degree of automaticity. Moreover, the SCWT has proven to be a valuable tool to assess neuronal plasticity that is coupled to improvement in performance in clinical populations. In a previous study, we showed impaired cognitive processing during SCWT along with reduced task-related activations in patients with fibromyalgia. In this study, we used SCWT and functional magnetic resonance imagingFMRI to investigate the effects of a 15-week physical exercise intervention on cognitive performance, task-related cortical activation and distraction-induced analgesia (DIA) in patients with fibromyalgia and healthy controls. The exercise intervention yielded reduced fibromyalgia symptoms, improved cognitive processing and increased task-related activation of amygdala, but no effect on DIA. Our results suggest beneficial effects of physical exercise on cognitive functioning in FM. © 2017 The Authors. Clinical Physiology and Functional Imaging published by John Wiley & Sons Ltd on behalf of Scandinavian Society of Clinical Physiology and Nuclear Medicine.

Plasma treatment effect on angiogenesis in wound healing process evaluated in vivo using angiographic optical coherence tomography

NASA Astrophysics Data System (ADS)

Kim, D. W.; Park, T. J.; Jang, S. J.; You, S. J.; Oh, W. Y.

2016-12-01

Non-thermal atmospheric pressure plasma holds promise for promoting wound healing. However, plasma-induced angiogenesis, which is important to better understand the underlying physics of plasma treatment effect on wound healing, remains largely unknown. We therefore evaluated the effect of non-thermal plasma on angiogenesis during wound healing through longitudinal monitoring over 30 days using non-invasive angiographic optical coherence tomography imaging in vivo. We demonstrate that the plasma-treated vascular wound area of mouse ear was noticeably decreased as compared to that of control during the early days in the wound healing process. We also observed that the vascular area density was increased in the plasma affected region near the wound as compared to the plasma unaffected region. The difference in the vascular wound area and the vascular area density peaked around day 3. This indicates that the plasma treatment induced additional angiogenic effects in the wound healing process especially during the early days. This non-invasive optical angiographic approach for in vivo time-lapse imaging provides further insights into elucidating plasma-induced angiogenesis in the wound healing process and its application in the biomedical plasma evaluation.

Can fish oil supplementation and physical training improve oxidative metabolism in aged rat hearts?

PubMed

da Silva Pedroza, Anderson Apolonio; Lopes, Andréia; Mendes da Silva, Rosângela F; Braz, Glauber Ruda; Nascimento, Luciana P; Ferreira, Diorginis Soares; dos Santos, Ângela Amâncio; Batista-de-Oliveira-Hornsby, Manuella; Lagranha, Claudia J

2015-09-15

It is well known that in the aging process a variety of physiological functions such as cardiac physiology and energy metabolism decline. Imbalance in production and elimination of reactive oxygen species (ROS) may induce oxidative stress. Research shows that oxidative stress is an important factor in the aging process. Studies suggest that ɷ-3 polyunsaturated fatty acids (PUFAs) and moderate physical exercise modulate the ROS system. Therefore, the present study aimed to investigate whether ɷ-3 present in fish oil supplementation coupled with moderate physical training could improve antioxidant and metabolic enzymes in the hearts of adult and aged rats and, if these effects could be associated to glycemia, plasma lipid profile or murinometric parameters. Adult (weighing 315.1±9.3g) and aged rats (weighing 444.5±11.8g) exercised and receive fish oil supplementation for 4weeks. Then they were used to evaluate murinometric parameters, fasting glucose and lipid profile. After this, their hearts were collected to measure the levels of malondialdehyde (MDA), antioxidant enzyme activity (superoxide dismutase-SOD, catalase-CAT, glutathione peroxidase-GPx) and oxidative metabolism marker (citrate synthase-CS activity). Fish oil supplementation increases HDL concentration and activity of CAT and CS. Moreover, physical training coupled with fish oil supplementation induces additional effects on SOD, GPx and CS activity mainly in aged rats. Our data suggest that combined treatment in aged rat hearts improves the antioxidant capacities and metabolic enzyme that can prevent the deleterious effects of aging. Copyright © 2015. Published by Elsevier Inc.

Process depending morphology and resulting physical properties of TPU

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

Frick, Achim, E-mail: achim.frick@hs-aalen.de; Spadaro, Marcel, E-mail: marcel.spadaro@hs-aalen.de

2015-12-17

Thermoplastic polyurethane (TPU) is a rubber like material with outstanding properties, e.g. for seal applications. TPU basically provides high strength, low frictional behavior and excellent wear resistance. Though, due to segmented structure of TPU, which is composed of hard segments (HSs) and soft segments (SSs), physical properties depend strongly on the morphological arrangement of the phase separated HSs at a certain ratio of HSs to SSs. It is obvious that the TPU deforms differently depending on its bulk morphology. Basically, the morphology can either consist of HSs segregated into small domains, which are well dispersed in the SS matrix ormore » of few strongly phase separated large size HS domains embedded in the SS matrix. The morphology development is hardly ruled by the melt processing conditions of the TPU. Depending on the morphology, TPU provides quite different physical properties with respect to strength, deformation behavior, thermal stability, creep resistance and tribological performance. The paper deals with the influence of important melt processing parameters, such as temperature, pressure and shear conditions, on the resulting physical properties tested by tensile and relaxation experiments. Furthermore the morphology is studied employing differential scanning calorimeter (DSC), transmission light microscopy (TLM), scanning electron beam microscopy (SEM) and transmission electron beam microscopy (TEM) investigations. Correlations between processing conditions and resulting TPU material properties are elaborated. Flow and shear simulations contribute to the understanding of thermal and flow induced morphology development.« less

Physical property changes in hydrate-bearing sediment due to depressurization and subsequent repressurization

USGS Publications Warehouse

Waite, W.F.; Kneafsey, T.J.; Winters, W.J.; Mason, D.H.

2008-01-01

Physical property measurements of sediment cores containing natural gas hydrate are typically performed on material exposed, at least briefly, to non-in situ conditions during recovery. To examine the effects of a brief excursion from the gas-hydrate stability field, as can occur when pressure cores are transferred to pressurized storage vessels, we measured physical properties on laboratory-formed sand packs containing methane hydrate and methane pore gas. After depressurizing samples to atmospheric pressure, we repressurized them into the methane-hydrate stability field and remeasured their physical properties. Thermal conductivity, shear strength, acoustic compressional and shear wave amplitudes, and speeds of the original and depressurized/repressurized samples are compared. X– ray computed tomography images track how the gas-hydrate distribution changes in the hydrate-cemented sands owing to the depressurizaton/repressurization process. Because depressurization-induced property changes can be substantial and are not easily predicted, particularly in water-saturated, hydrate-bearing sediment, maintaining pressure and temperature conditions throughout the core recovery and measurement process is critical for using laboratory measurements to estimate in situ properties.

Physical property changes in hydrate-bearing sediment due to depressurization and subsequent repressurization

USGS Publications Warehouse

Waite, W.F.; Kneafsey, T.J.; Winters, W.J.; Mason, D.H.

2008-01-01

Physical property measurements of sediment cores containing natural gas hydrate are typically performed on material exposed, at least briefly, to non-in situ conditions during recovery. To examine the effects of a brief excursion from the gas-hydrate stability field, as can occur when pressure cores are transferred to pressurized storage vessels, we measured physical properties on laboratory-formed sand packs containing methane hydrate and methane pore gas. After depressurizing samples to atmospheric pressure, we repressurized them into the methane-hydrate stability field and remeasured their physical properties. Thermal conductivity, shear strength, acoustic compressional and shear wave amplitudes, and speeds of the original and depressurized/repressurized samples are compared. X-ray computed tomography images track how the gas-hydrate distribution changes in the hydrate-cemented sands owing to the depressurizaton/repressurization process. Because depressurization-induced property changes can be substantial and are not easily predicted, particularly in water-saturated, hydrate-bearing sediment, maintaining pressure and temperature conditions throughout the core recovery and measurement process is critical for using laboratory measurements to estimate in situ properties.

"That part of the body is just gone": understanding and responding to dissociation and physical health.

PubMed

Haven, Terri J

2009-01-01

The past 2 decades have brought a significant surge in interest and research regarding the ways in which psychological trauma relates to the physical body. Researchers now understand a great deal about how the brain and the body process traumatic experiences, as well as the increased likelihood of an array of physical health consequences associated with both childhood and adult trauma and posttraumatic stress disorder. Experts are increasingly challenging mind-body dualism through solid theoretical and clinical bases for the central importance of listening to and communicating with trauma clients' bodies as part of reducing the suffering and long-lasting consequences of trauma. This article integrates this growing body of knowledge through a particular focus on trauma-induced dissociation and the implications of the physical and neurological processes and consequences of dissociation on clients' ability to participate in caring for their own bodies. The author utilizes an in-depth clinical example of expanding relational trauma psychotherapy to include a focus on working directly with trauma-related sensorimotor and physiological sensations and patterns.

Aircraft borne combined measurements of the Fukushima radionuclide Xe-133 and fossil fuel combustion generated pollutants in the TIL - Implications for Cyclone induced lift and TIL physical-chemical processes

NASA Astrophysics Data System (ADS)

Arnold, Frank; Schlager, Hans; Simgen, Hardy; Aufmhoff, Heinfried; Baumann, Robert; Lindemann, Sigfried; Rauch, Ludwig; Kaether, Frank; Pirjolla, Liisa; Schumann, Ulrich

2013-04-01

The radionuclide Xe-133, released by the March 2011 nuclear disaster at Fukushima/Daiichi (hereafter FD), represents an ideal tracer for atmospheric transport. We report the, to our best knowledge, only aircraft borne measurements of FD Xe-133 in the Tropopause Inversion Layer (TIL), indicating rapid lift of Xe-133 rich planetary boundary layer air to the TIL. On the same research aircraft (FALCON), we have also conducted on-line measurements of fossil fuel combustion generated pollutant gases (SO2, NOx, HNO3,NOy), which were found to have increased concentrations in the TIL. In addition, we have conducted supporting model simulations of transport, chemical processes, and aerosol processes. Our investigations reveal a potentially important influence of East-Asian cyclone induced pollutants transport to the TIL, particularly influencing aerosol formation in the TIL.

Numerical studies from quantum to macroscopic scales of carbon nanoparticules in hydrogen plasma

NASA Astrophysics Data System (ADS)

Lombardi, Guillaume; Ngandjong, Alain; Mezei, Zsolt; Mougenot, Jonathan; Michau, Armelle; Hassouni, Khaled; Seydou, Mahamadou; Maurel, François

2016-09-01

Dusty plasmas take part in large scientific domains from Universe Science to nanomaterial synthesis processes. They are often generated by growth from molecular precursor. This growth leads to the formation of larger clusters which induce solid germs nucleation. Particle formed are described by an aerosol dynamic taking into account coagulation, molecular deposition and transport processes. These processes are controlled by the elementary particle. So there is a strong coupling between particle dynamics and plasma discharge equilibrium. This study is focused on the development of a multiscale physic and numeric model of hydrogen plasmas and carbon particles around three essential coupled axes to describe the various physical phenomena: (i) Macro/mesoscopic fluid modeling describing in an auto-coherent way, characteristics of the plasma, molecular clusters and aerosol behavior; (ii) the classic molecular dynamics offering a description to the scale molecular of the chains of chemical reactions and the phenomena of aggregation; (iii) the quantum chemistry to establish the activation barriers of the different processes driving the nanopoarticule formation.

Time-resolved study of femtosecond laser induced micro-modifications inside transparent brittle materials

NASA Astrophysics Data System (ADS)

Hendricks, F.; Matylitsky, V. V.; Domke, M.; Huber, Heinz P.

2016-03-01

Laser processing of optically transparent or semi-transparent, brittle materials is finding wide use in various manufacturing sectors. For example, in consumer electronic devices such as smartphones or tablets, cover glass needs to be cut precisely in various shapes. The unique advantage of material processing with femtosecond lasers is efficient, fast and localized energy deposition in nearly all types of solid materials. When an ultra-short laser pulse is focused inside glass, only the localized region in the neighborhood of the focal volume absorbs laser energy by nonlinear optical absorption. Therefore, the processing volume is strongly defined, while the rest of the target stays unaffected. Thus ultra-short pulse lasers allow cutting of the chemically strengthened glasses such as Corning Gorilla glass without cracking. Non-ablative cutting of transparent, brittle materials, using the newly developed femtosecond process ClearShapeTM from Spectra-Physics, is based on producing a micron-sized material modification track with well-defined geometry inside. The key point for development of the process is to understand the induced modification by a single femtosecond laser shot. In this paper, pump-probe microscopy techniques have been applied to study the defect formation inside of transparent materials, namely soda-lime glass samples, on a time scale between one nanosecond to several tens of microseconds. The observed effects include acoustic wave propagation as well as mechanical stress formation in the bulk of the glass. Besides better understanding of underlying physical mechanisms, our experimental observations have enabled us to find optimal process parameters for the glass cutting application and lead to better quality and speed for the ClearShapeTM process.

Validating a Model for Welding Induced Residual Stress Using High-Energy X-ray Diffraction

NASA Astrophysics Data System (ADS)

Mach, J. C.; Budrow, C. J.; Pagan, D. C.; Ruff, J. P. C.; Park, J.-S.; Okasinski, J.; Beaudoin, A. J.; Miller, M. P.

2017-05-01

Integrated computational materials engineering (ICME) provides a pathway to advance performance in structures through the use of physically-based models to better understand how manufacturing processes influence product performance. As one particular challenge, consider that residual stresses induced in fabrication are pervasive and directly impact the life of structures. For ICME to be an effective strategy, it is essential that predictive capability be developed in conjunction with critical experiments. In the present work, simulation results from a multi-physics model for gas metal arc welding are evaluated through x-ray diffraction using synchrotron radiation. A test component was designed with intent to develop significant gradients in residual stress, be representative of real-world engineering application, yet remain tractable for finely spaced strain measurements with positioning equipment available at synchrotron facilities. The experimental validation lends confidence to model predictions, facilitating the explicit consideration of residual stress distribution in prediction of fatigue life.

Phylogenetic perspectives on noise-induced fear and annoyance

NASA Astrophysics Data System (ADS)

Bowles, Ann

2003-04-01

Negative human responses to noise are typically interpreted in terms of human psychological, cognitive, or social processes. However, it may be useful to frame hypotheses about human responses in terms of evolutionary history, during which negative responses have been part of a suite of adaptions to a variable sound environment. By comparing the responses of a range of nonhuman animals to various types of noise, it is possible to develop hypotheses about the ecology of human responses. Examples of noise-related phenomena that could be explained usefully from this perspective include the Schulz curve, noise-induced physical stress, acute fear responses induced by transient noise, and the relationship between temperament and noise-induced annoyance. Responses of animals from a range of taxa will be described and their behavior interpreted in terms of their life-history strategies. With this perspective, some testable hypotheses about noise-induced fear and annoyance will be suggested.

The DART dispersion analysis research tool: A mechanistic model for predicting fission-product-induced swelling of aluminum dispersion fuels. User`s guide for mainframe, workstation, and personal computer applications

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

Rest, J.

1995-08-01

This report describes the primary physical models that form the basis of the DART mechanistic computer model for calculating fission-product-induced swelling of aluminum dispersion fuels; the calculated results are compared with test data. In addition, DART calculates irradiation-induced changes in the thermal conductivity of the dispersion fuel, as well as fuel restructuring due to aluminum fuel reaction, amorphization, and recrystallization. Input instructions for execution on mainframe, workstation, and personal computers are provided, as is a description of DART output. The theory of fission gas behavior and its effect on fuel swelling is discussed. The behavior of these fission products inmore » both crystalline and amorphous fuel and in the presence of irradiation-induced recrystallization and crystalline-to-amorphous-phase change phenomena is presented, as are models for these irradiation-induced processes.« less

Laser-induced modification of structure and shape of cartilage in otolaryngology and orthopaedics

NASA Astrophysics Data System (ADS)

Sobol', E. N.; Baum, O. I.; Omel'chenko, A. I.; Soshnikova, Yu. M.; Yuzhakov, A. V.; Kas'yanenko, E. M.; Tokareva, A. V.; Baskov, A. V.; Svistushkin, V. M.; Selezneva, L. V.; Shekhter, A. B.

2017-11-01

We present the results of basic research in laser modification of tissues in otolaryngology (correcting the shape of nasal septum and larynx cartilages), cosmetology (correcting ear and nose shape), orthopaedics and spinal surgery (treatment of diseases of spine disc and joints). The physical processes and mechanisms of laser-induced relaxation of stresses and regeneration of tissues are considered. New results of studies in this fast-developing field of laser surgery are presented, in particular, the results of laser correction of costal cartilage shape in the process of making implants for the treatment of larynx stenosis and controlled regeneration of the hyaline articular cartilage. Presented at the Fundamentals of Laser Assisted Micro- and Nanotechnologies (FLAMN-2016) International Symposium (Pushkin, Leningrad oblast, 27 June to 1 July 2016).

Tissue engineering bioreactor systems for applying physical and electrical stimulations to cells.

PubMed

Jin, GyuHyun; Yang, Gi-Hoon; Kim, GeunHyung

2015-05-01

Bioreactor systems in tissue engineering applications provide various types of stimulation to mimic the tissues in vitro and in vivo. Various bioreactors have been designed to induce high cellular activities, including initial cell attachment, cell growth, and differentiation. Although cell-stimulation processes exert mostly positive effects on cellular responses, in some cases such stimulation can also have a negative effect on cultured cells. In this review, we discuss various types of bioreactor and the positive and negative effects of stimulation (physical, chemical, and electrical) on various cultured cell types. © 2014 Wiley Periodicals, Inc.

Quantum error correction for continuously detected errors with any number of error channels per qubit

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

Ahn, Charlene; Wiseman, Howard; Jacobs, Kurt

2004-08-01

It was shown by Ahn, Wiseman, and Milburn [Phys. Rev. A 67, 052310 (2003)] that feedback control could be used as a quantum error correction process for errors induced by weak continuous measurement, given one perfectly measured error channel per qubit. Here we point out that this method can be easily extended to an arbitrary number of error channels per qubit. We show that the feedback protocols generated by our method encode n-2 logical qubits in n physical qubits, thus requiring just one more physical qubit than in the previous case.

FOREWORD: The 12th International Workshop on Desorption Induced by Electronic Transitions (DIET XII) (Pine Mountain, Georgia, USA, 19-23 April 2009) The 12th International Workshop on Desorption Induced by Electronic Transitions (DIET XII) (Pine Mountain, Georgia, USA, 19-23 April 2009)

NASA Astrophysics Data System (ADS)

Orlando, Thomas M.; Diebold, Ulrike

2010-03-01

The 12th International Workshop on Desorption Induced by Electronic Transitions (DIET XII) took place from 19-23 April 2009 in Pine Mountain, Georgia, USA. This was the 12th conference in a strong and vibrant series, which dates back to the early 1980s. DIET XII continued the tradition of exceptional interdisciplinary science and focused on the study of desorption and dynamics induced by electronic excitations of surfaces and interfaces. The format involved invited lectures, contributed talks and a poster session on the most recent developments and advances in this area of surface physics. The Workshop International Steering Committee and attendees wish to dedicate DIET XII to the memory of the late Professor Theodore (Ted) Madey. Ted was one of the main pioneers of this field and was one of the primary individuals working to keep this area of science exciting and adventurous. His overall contributions to surface science were countless and his contributions to the DIET field and community were enormous. He is missed and remembered by many friends and colleagues throughout the world. The papers collected in this issue cover many of the highlights of DIET XII. Topics include ultrafast electron transfer at surfaces and interfaces, quantum and spatially resolved mapping of surface dynamics and desorption, photon-, electron- and ion-beam induced processes at complex interfaces, the role of non-thermal desorption in astrochemistry and astrophysics and laser-/ion-based methods of examining soft matter and biological media. Although the workshop attracted many scientists active in the general area of non-thermal surface processes, DIET XII also attracted many younger scientists (i.e., postdoctoral fellows, advanced graduate students, and a select number of advanced undergraduate students). This field has had an impact in a number of areas including nanoscience, device physics, astrophysics, and now biophysics. We believe that this special issue of Journal of Physics: Condensed Matter will help foster further progress in the study of DIET processes. Since the field remains vibrant and exciting, the workshop series will continue with DIET XIII. Professor Richard Palmer (University of Birmingham, UK) will chair DIET XIII in the UK in early summer 2012. We gratefully acknowledge financial support from SPECS, HIDEN Analytical, BRUKER, The United States National Science Foundation, Georgia Institute of Technology and The State University of New Jersey, Rutgers.

Fundamental Processes in Plasmas

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

Driscoll, Charles Fred

This Final Technical Report gives brief summaries of the plasma physics results developed under DOE grant DE-SC0002451; and provides reference to the published journal articles giving full scientific descriptions. General topics include 1) cyclotron modes; 2) damping and decay of Langmuir modes; 3) 2D vortex dynamics and diocotron modes; 4) separatrix-induced transport and damping; and 5) long-range collisional velocity slowing.

Process for control of cell division

NASA Technical Reports Server (NTRS)

Cone, C. D., Jr. (Inventor)

1977-01-01

A method of controlling mitosis of biological cells was developed, which involved inducing a change in the intracellular ionic hierarchy accompanying the cellular electrical transmembrane potential difference (Esubm) of the cells. The ionic hierarchy may be varied by imposing changes on the relative concentrations of Na(+), K(+) and Cl(-), or by directly imposing changes in the physical Esubm level across the cell surface.

Novel growth techniques of group-IV based semiconductors on insulator for next-generation electronics

NASA Astrophysics Data System (ADS)

Miyao, Masanobu; Sadoh, Taizoh

2017-05-01

Recent progress in the crystal growth of group-IV-based semiconductor-on-insulators is reviewed from physical and technological viewpoints. Liquid-phase growth based on SiGe-mixing-triggered rapid-melting growth enables formation of hybrid (100) (110) (111)-orientation Ge-on-insulator (GOI) structures, which show defect-free GOI with very high carrier mobility (˜1040 cm2 V-1 s-1). Additionally, SiGe mixed-crystals with laterally uniform composition were obtained by eliminating segregation phenomena during the melt-back process. Low-temperature solid-phase growth has been explored by combining this process with ion-beam irradiation, additional doping of group-IV elements, metal induced lateral crystallization with/without electric field, and metal-induced layer exchange crystallization. These efforts have enabled crystal growth on insulators below 400 °C, achieving high carrier mobility (160-320 cm2 V-1 s-1). Moreover, orientation-controlled SiGe and Ge films on insulators have been obtained below the softening temperatures of conventional plastic films (˜300 °C). Detailed characterization provides an understanding of physical phenomena behind these crystal growth techniques. Applying these methods when fabricating next-generation electronics is also discussed.

Universal features underlying the magnetism in diluted magnetic semiconductors

NASA Astrophysics Data System (ADS)

Andriotis, Antonis N.; Menon, Madhu

2018-04-01

Investigation of a diverse variety of wide band gap semiconductors and metal oxides that exhibit magnetism on substitutional doping has revealed the existence of universal features that relate the magnetic moment of the dopant to a number of physical properties inherent to the dopants and the hosts. The investigated materials consist of ZnO, GaN, GaP, TiO2, SnO2, Sn3N4, MoS2, ZnS and CdS doped with 3d-transition metal atoms. The primary physical properties contributing to magnetism include the orbital hybridization and charge distribution, the d-band filling, d-band center, crystal field splitting, electron pairing energy and electronegativity. These features specify the strength of the spin-polarization induced by the dopants on their first nearest neighboring anions which in turn specify the long range magnetic coupling among the dopants through successively induced spin polarizations (SSP) on neighboring dopants. The proposed local SSP process for the establishment of the magnetic coupling among the TM-dopants appears as a competitor to other classical processes (superexchange, double exchange, etc). Furthermore, these properties can be used as a set of descriptors suitable for developing statistical predictive theories for a much larger class of magnetic materials.

Correlative STED and Atomic Force Microscopy on Live Astrocytes Reveals Plasticity of Cytoskeletal Structure and Membrane Physical Properties during Polarized Migration

PubMed Central

Curry, Nathan; Ghézali, Grégory; Kaminski Schierle, Gabriele S.; Rouach, Nathalie; Kaminski, Clemens F.

2017-01-01

The plasticity of the cytoskeleton architecture and membrane properties is important for the establishment of cell polarity, adhesion and migration. Here, we present a method which combines stimulated emission depletion (STED) super-resolution imaging and atomic force microscopy (AFM) to correlate cytoskeletal structural information with membrane physical properties in live astrocytes. Using STED compatible dyes for live cell imaging of the cytoskeleton, and simultaneously mapping the cell surface topology with AFM, we obtain unprecedented detail of highly organized networks of actin and microtubules in astrocytes. Combining mechanical data from AFM with optical imaging of actin and tubulin further reveals links between cytoskeleton organization and membrane properties. Using this methodology we illustrate that scratch-induced migration induces cytoskeleton remodeling. The latter is caused by a polarization of actin and microtubule elements within astroglial cell processes, which correlates strongly with changes in cell stiffness. The method opens new avenues for the dynamic probing of the membrane structural and functional plasticity of living brain cells. It is a powerful tool for providing new insights into mechanisms of cell structural remodeling during physiological or pathological processes, such as brain development or tumorigenesis. PMID:28469559

Crk1/2 and CrkL form a hetero-oligomer and functionally complement each other during podocyte morphogenesis

PubMed Central

Zhang, Jidong; Verma, Rakesh; Park, Tae-Ju; Wong, Hetty; Curran, Tom; Nihalani, Deepak; Holzman, Lawrence B.

2014-01-01

Activation of the slit diaphragm protein Nephrin induces actin cytoskeletal remodeling resulting in lamellipodia formation in podocytes in vitro in a phosphatidylinositol-3 kinase, focal adhesion kinase, Cas, and Crk1/2-dependent fashion. In mice, podocyte-specific deletion of Crk1/2 prevents or attenuates foot process effacement in two models of podocyte injury. This suggests that cellular mechanisms governing lamellipodial protrusion in vitro are similar to those in vivo during foot process effacement. Since Crk1/2 null mice develop and aged normally, we tested whether the Crk1/2 paralog, CrkL, functionally complements Crk1/2 in a podocyte-specific context. Podocyte-specific CrkL null mice, like podocyte-specific Crk1/2 null mice, developed and aged normally but were protected from protamine sulfate-induced foot process effacement. Simultaneous podocyte-specific deletion of Crk1/2 and CrkL resulted in albuminuria detected by six weeks post-partum and associated with altered podocyte process architecture. Nephrin-induced lamellipodia formation in podocytes in vitro was CrkL-dependent. CrkL formed a heterooligomer with Crk2 and, like Crk2, was recruited to tyrosine phosphorylated Nephrin. Thus, Crk1/2 and CrkL are physically-linked, functionally complement each other during podocyte foot process spreading, and together are required for developing typical foot process architecture. PMID:24499776

Optoacoustic induced vibrations within the inner ear.

PubMed

Zhang, K Y; Wenzel, G I; Balster, S; Lim, H H; Lubatschowski, H; Lenarz, T; Ertmer, W; Reuter, G

2009-12-07

An acoustic transient can be generated inside an absorbing tissue as a result of laser-tissue interaction after pulsed laser irradiation. Herein we report a novel application of this physical process, the optoacoustic wave generation in the inner ear and subsequently the induction of basilar membrane vibrations. These laser induced vibrations show a direct correlation to the laser energy and an indirect correlation to the distance from the irradiation focus. Through these characteristics they may be used, in a new generation of cochlear implants, to improve the frequency specific cochlear activation and consequently improve speech perception in hearing impaired patients with residual hearing.

Electronic properties of solids excited with intermediate laser power densities

NASA Astrophysics Data System (ADS)

Sirotti, Fausto; Tempo Beamline Team

Intermediate laser power density up to about 100 GW/cm2 is below the surface damage threshold is currently used to induce modification in the physical properties on short time scales. The absorption of a short laser pulse induces non-equilibrium electronic distributions followed by lattice-mediated equilibrium taking place only in the picosecond range. The role of the hot electrons is particularly important in several domains as for example fast magnetization and demagnetization processes, laser induced phase transitions, charge density waves. Angular resolved photoelectron spectroscopy measuring directly energy and momentum of electrons is the most adapted tool to study the electronic excitations at short time scales during and after fast laser excitations. The main technical problem is the space charge created by the pumping laser pulse. I will present angular resolved multiphoton photoemission results obtained with 800 nm laser pulses showing how space charge electrons emitted during fast demagnetization processes can be measured. Unable enter Affiliation: CNRS-SOLEIL Synchrotron L'Orme des Merisiers , Saint Aubin 91192 Gif sur Yvette France.

Novel mechanism of gene transfection by low-energy shock wave.

PubMed

Ha, Chang Hoon; Lee, Seok Cheol; Kim, Sunghyen; Chung, Jihwa; Bae, Hasuk; Kwon, Kihwan

2015-08-05

Extracorporeal shock wave (SW) therapy has been studied in the transfection of naked nucleic acids into various cell lines through the process of sonoporation, a process that affects the permeation of cell membranes, which can be an effect of cavitation. In this study, siRNAs were efficiently transfected into primary cultured cells and mouse tumor tissue via SW treatment. Furthermore SW-induced siRNA transfection was not mediated by SW-induced sonoporation, but by microparticles (MPs) secreted from the cells. Interestingly, the transfection effect of the siRNAs was transferable through the secreted MPs from human umbilical vein endothelial cell (HUVEC) culture medium after treatment with SW, into HUVECs in another culture plate without SW treatment. In this study, we suggest for the first time a mechanism of gene transfection induced by low-energy SW through secreted MPs, and show that it is an efficient physical gene transfection method in vitro and represents a safe therapeutic strategy for site-specific gene delivery in vivo.

Effect of crumb-rubber particle size on mechanical response of polyurethane foam composites

NASA Astrophysics Data System (ADS)

Sanjay, Omer Sheik

The compression properties of foam are governed by by three factors: i) cell edge bending ii) compression of cell fluid iii) membrane stresses in the cell faces. The effect of reinforcement, granular form of scrap tire rubber on contribution of each of these effects along with the physical properties of polyurethane foam is investigated. It is seen that the addition of crumb-rubber hinders the formation of cell membranes during the foaming process. Four different sizes of particles were chosen to closely study the effect of particle size on the physical properties of the foam composite. There is a definite pattern seen in each of the physical property of the composite with change in the particle size. Addition of crumb-rubber decreases the compressive strength but in turn increases the elastic modulus of the composite. The rubber particles act as the sites for stress concentration and hence the inclusion of rubber particles induces the capability to transfer the axial load laterally along the surface of the foam. Also, the filler material induces porosity into the foam, which is seen in the SEM images, and hence the addition of rubber particles induces brittleness, which makes the foam composites extensively applicable for structural application in sandwich components. The lightweight composite therefore is a potential substitute to the heavier metal foams and honeycombs as a protective layer.

Naphthalene Planar Laser-Induced Fluorescence Imaging of Orion Multi-Purpose Crew Vehicle Heat Shield Ablation Products

NASA Astrophysics Data System (ADS)

Combs, Christopher S.; Clemens, Noel T.; Danehy, Paul M.

2013-11-01

The Orion Multi-Purpose Crew Vehicle (MPCV) calls for an ablative heat shield. In order to better design this heat shield and others that will undergo planetary entry, an improved understanding of the ablation process is required. Given that ablation is a multi-physics process involving heat and mass transfer, codes aiming to predict heat shield ablation are in need of experimental data pertaining to the turbulent transport of ablation products for validation. At The University of Texas at Austin, a technique is being developed that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to visualize the transport of ablation products in a supersonic flow. Since ablation at reentry temperatures can be difficult to recreate in a laboratory setting it is desirable to create a limited physics problem and simulate the ablation process at relatively low temperature conditions using naphthalene. A scaled Orion MPCV model with a solid naphthalene heat shield has been tested in a Mach 5 wind tunnel at various angles of attack in the current work. PLIF images have shown high concentrations of scalar in the capsule wake region, intermittent turbulent structures on the heat shield surface, and interesting details of the capsule shear layer structure. This work was supported by a NASA Office of the Chief Technologist's Space Technology Research Fellowship (NNX11AN55H).

Reply to "Comment on `Dynamics of slow light and light storage in a Doppler-broadened electromagnetically-induced-transparency medium: A numerical approach' "

NASA Astrophysics Data System (ADS)

Gou, Shih-Chuan; Su, Shih-Wei; Yu, Ite A.

2017-10-01

A damping term in the theoretical model of our paper [Phys. Rev. A 83, 013827 (2011), 10.1103/PhysRevA.83.013827] was questioned by the author of the Comment. The author argued this damping term cannot exactly describe the spontaneous decay or quantum jump process and, thus, concluded that our results are prone to be incorrect. However, the physics of electromagnetically induced transparency (EIT) is mainly determined by the ground-state coherence and the optical coherence of the probe transition. We show here that the damping term in our paper described the relaxation process of optical coherence in the EIT system, but not the spontaneous decay process of the population. The case of spontaneous decay used in the argument of the Comment is not an issue in typical EIT studies, in which the probe field is weak and treated as the perturbation. Furthermore, the experimental data in the paper were taken under the condition of a weak probe field. Our theoretical model in the weak-probe condition actually deals with the two coherences of EIT physics, and is suitable for analysis of the data. We believe the results of the study, focusing on the dynamics of slow light and light storage in Doppler-broadened EIT media, are correct.

s-Processing from MHD-induced mixing and isotopic abundances in presolar SiC grains

NASA Astrophysics Data System (ADS)

Palmerini, S.; Trippella, O.; Busso, M.; Vescovi, D.; Petrelli, M.; Zucchini, A.; Frondini, F.

2018-01-01

In the past years the observational evidence that s-process elements from Sr to Pb are produced by stars ascending the so-called Asymptotic Giant Branch (or "AGB") could not be explained by self-consistent models, forcing researchers to extensive parameterizations. The crucial point is to understand how protons can be injected from the envelope into the He-rich layers, yielding the formation of 13C and then the activation of the 13C (α,n)16O reaction. Only recently, attempts to solve this problem started to consider quantitatively physically-based mixing mechanisms. Among them, MHD processes in the plasma were suggested to yield mass transport through magnetic buoyancy. In this framework, we compare results of nucleosynthesis models for Low Mass AGB Stars (M≲ 3M⊙), developed from the MHD scenario, with the record of isotopic abundance ratios of s-elements in presolar SiC grains, which were shown to offer precise constraints on the 13C reservoir. We find that n-captures driven by magnetically-induced mixing can indeed account for the SiC data quite well and that this is due to the fact that our 13C distribution fulfils the above constraints rather accurately. We suggest that similar tests should be now performed using different physical models for mixing. Such comparisons would indeed improve decisively our understanding of the formation of the neutron source.

Attosecond physics at the nanoscale

NASA Astrophysics Data System (ADS)

Ciappina, M. F.; Pérez-Hernández, J. A.; Landsman, A. S.; Okell, W. A.; Zherebtsov, S.; Förg, B.; Schötz, J.; Seiffert, L.; Fennel, T.; Shaaran, T.; Zimmermann, T.; Chacón, A.; Guichard, R.; Zaïr, A.; Tisch, J. W. G.; Marangos, J. P.; Witting, T.; Braun, A.; Maier, S. A.; Roso, L.; Krüger, M.; Hommelhoff, P.; Kling, M. F.; Krausz, F.; Lewenstein, M.

2017-05-01

Recently two emerging areas of research, attosecond and nanoscale physics, have started to come together. Attosecond physics deals with phenomena occurring when ultrashort laser pulses, with duration on the femto- and sub-femtosecond time scales, interact with atoms, molecules or solids. The laser-induced electron dynamics occurs natively on a timescale down to a few hundred or even tens of attoseconds (1 attosecond  =  1 as  =  10-18 s), which is comparable with the optical field. For comparison, the revolution of an electron on a 1s orbital of a hydrogen atom is  ˜152 as. On the other hand, the second branch involves the manipulation and engineering of mesoscopic systems, such as solids, metals and dielectrics, with nanometric precision. Although nano-engineering is a vast and well-established research field on its own, the merger with intense laser physics is relatively recent. In this report on progress we present a comprehensive experimental and theoretical overview of physics that takes place when short and intense laser pulses interact with nanosystems, such as metallic and dielectric nanostructures. In particular we elucidate how the spatially inhomogeneous laser induced fields at a nanometer scale modify the laser-driven electron dynamics. Consequently, this has important impact on pivotal processes such as above-threshold ionization and high-order harmonic generation. The deep understanding of the coupled dynamics between these spatially inhomogeneous fields and matter configures a promising way to new avenues of research and applications. Thanks to the maturity that attosecond physics has reached, together with the tremendous advance in material engineering and manipulation techniques, the age of atto-nanophysics has begun, but it is in the initial stage. We present thus some of the open questions, challenges and prospects for experimental confirmation of theoretical predictions, as well as experiments aimed at characterizing the induced fields and the unique electron dynamics initiated by them with high temporal and spatial resolution.

Attosecond physics at the nanoscale.

PubMed

Ciappina, M F; Pérez-Hernández, J A; Landsman, A S; Okell, W A; Zherebtsov, S; Förg, B; Schötz, J; Seiffert, L; Fennel, T; Shaaran, T; Zimmermann, T; Chacón, A; Guichard, R; Zaïr, A; Tisch, J W G; Marangos, J P; Witting, T; Braun, A; Maier, S A; Roso, L; Krüger, M; Hommelhoff, P; Kling, M F; Krausz, F; Lewenstein, M

2017-05-01

Recently two emerging areas of research, attosecond and nanoscale physics, have started to come together. Attosecond physics deals with phenomena occurring when ultrashort laser pulses, with duration on the femto- and sub-femtosecond time scales, interact with atoms, molecules or solids. The laser-induced electron dynamics occurs natively on a timescale down to a few hundred or even tens of attoseconds (1 attosecond  =  1 as  =  10 -18 s), which is comparable with the optical field. For comparison, the revolution of an electron on a 1s orbital of a hydrogen atom is  ∼152 as. On the other hand, the second branch involves the manipulation and engineering of mesoscopic systems, such as solids, metals and dielectrics, with nanometric precision. Although nano-engineering is a vast and well-established research field on its own, the merger with intense laser physics is relatively recent. In this report on progress we present a comprehensive experimental and theoretical overview of physics that takes place when short and intense laser pulses interact with nanosystems, such as metallic and dielectric nanostructures. In particular we elucidate how the spatially inhomogeneous laser induced fields at a nanometer scale modify the laser-driven electron dynamics. Consequently, this has important impact on pivotal processes such as above-threshold ionization and high-order harmonic generation. The deep understanding of the coupled dynamics between these spatially inhomogeneous fields and matter configures a promising way to new avenues of research and applications. Thanks to the maturity that attosecond physics has reached, together with the tremendous advance in material engineering and manipulation techniques, the age of atto-nanophysics has begun, but it is in the initial stage. We present thus some of the open questions, challenges and prospects for experimental confirmation of theoretical predictions, as well as experiments aimed at characterizing the induced fields and the unique electron dynamics initiated by them with high temporal and spatial resolution.

Effect of small scale transport processes on phytoplankton distribution in coastal seas.

PubMed

Hernández-Carrasco, Ismael; Orfila, Alejandro; Rossi, Vincent; Garçon, Veronique

2018-06-05

Coastal ocean ecosystems are major contributors to the global biogeochemical cycles and biological productivity. Physical factors induced by the turbulent flow play a crucial role in regulating marine ecosystems. However, while large-scale open-ocean dynamics is well described by geostrophy, the role of multiscale transport processes in coastal regions is still poorly understood due to the lack of continuous high-resolution observations. Here, the influence of small-scale dynamics (O(3.5-25) km, i.e. spanning upper submesoscale and mesoscale processes) on surface phytoplankton derived from satellite chlorophyll-a (Chl-a) is studied using Lagrangian metrics computed from High-Frequency Radar currents. The combination of complementary Lagrangian diagnostics, including the Lagrangian divergence along fluid trajectories, provides an improved description of the 3D flow geometry which facilitates the interpretation of two non-exclusive physical mechanisms affecting phytoplankton dynamics and patchiness. Attracting small-scale fronts, unveiled by backwards Lagrangian Coherent Structures, are associated to negative divergence where particles and Chl-a standing stocks cluster. Filaments of positive divergence, representing large accumulated upward vertical velocities and suggesting accrued injection of subsurface nutrients, match areas with large Chl-a concentrations. Our findings demonstrate that an accurate characterization of small-scale transport processes is necessary to comprehend bio-physical interactions in coastal seas.

Dynamic monitoring of membrane nanotubes formation induced by vaccinia virus on a high throughput microfluidic chip

NASA Astrophysics Data System (ADS)

Xiao, Min; Xu, Na; Wang, Cheng; Pang, Dai-Wen; Zhang, Zhi-Ling

2017-03-01

Membrane nanotubes (MNTs) are physical connections for intercellular communication and induced by various viruses. However, the formation of vaccinia virus (VACV)-induced MNTs has never been studied. In this report, VACV-induced MNTs formation process was monitored on a microfluidic chip equipped with a series of side chambers, which protected MNTs from fluidic shear stress. MNTs were formed between susceptible cells and be facilitated by VACV infection through three patterns. The formed MNTs varied with cell migration and virus concentration. The length of MNTs was positively correlated with the distance of cell migration. With increasing virus titer, the peak value of the ratio of MNT-carried cell appeared earlier. The immunofluorescence assay indicated that the rearrangement of actin fibers induced by VACV infection may lead to the formation of MNTs. This study presents evidence for the formation of MNTs induced by virus and helps us to understand the relationship between pathogens and MNTs.

Physical-biological coupling induced aggregation mechanism for the formation of high biomass red tides in low nutrient waters.

PubMed

Lai, Zhigang; Yin, Kedong

2014-01-01

Port Shelter is a semi-enclosed bay in northeast Hong Kong where high biomass red tides are observed to occur frequently in narrow bands along the local bathymetric isobars. Previous study showed that nutrients in the Bay are not high enough to support high biomass red tides. The hypothesis is that physical aggregation and vertical migration of dinoflagellates appear to be the driving mechanism to promote the formation of red tides in this area. To test this hypothesis, we used a high-resolution estuarine circulation model to simulate the near-shore water dynamics based on in situ measured temperature/salinity profiles, winds and tidal constitutes taken from a well-validated regional tidal model. The model results demonstrated that water convergence occurs in a narrow band along the west shore of Port Shelter under a combined effect of stratified tidal current and easterly or northeasterly wind. Using particles as dinoflagellate cells and giving diel vertical migration, the model results showed that the particles aggregate along the convergent zone. By tracking particles in the model predicted current field, we estimated that the physical-biological coupled processes induced aggregation of the particles could cause 20-45 times enhanced cell density in the convergent zone. This indicated that a high cell density red tide under these processes could be initialized without very high nutrients concentrations. This may explain why Port Shelter, a nutrient-poor Bay, is the hot spot for high biomass red tides in Hong Kong in the past 25 years. Our study explains why red tide occurrences are episodic events and shows the importance of taking the physical-biological aggregation mechanism into consideration in the projection of red tides for coastal management. Copyright © 2013 Elsevier B.V. All rights reserved.

Enhanced Antimicrobial Activity Based on a Synergistic Combination of Sublethal Levels of Stresses Induced by UV-A Light and Organic Acids.

PubMed

de Oliveira, Erick F; Cossu, Andrea; Tikekar, Rohan V; Nitin, Nitin

2017-06-01

The reduction of microbial load in food and water systems is critical for their safety and shelf life. Conventionally, physical processes such as heat or light are used for the rapid inactivation of microbes, while natural compounds such as lactic acid may be used as preservatives after the initial physical process. This study demonstrates the enhanced and rapid inactivation of bacteria based on a synergistic combination of sublethal levels of stresses induced by UV-A light and two food-grade organic acids. A reduction of 4.7 ± 0.5 log CFU/ml in Escherichia coli O157:H7 was observed using a synergistic combination of UV-A light, gallic acid (GA), and lactic acid (LA), while the individual treatments and the combination of individual organic acids with UV-A light resulted in a reduction of less than 1 log CFU/ml. Enhanced inactivation of bacteria on the surfaces of lettuce and spinach leaves was also observed based on the synergistic combination. Mechanistic investigations suggested that the treatment with a synergistic combination of GA plus LA plus UV-A (GA+LA+UV-A) resulted in significant increases in membrane permeability and intracellular thiol oxidation and affected the metabolic machinery of E. coli In addition, the antimicrobial activity of the synergistic combination of GA+LA+UV-A was effective only against metabolically active E. coli O157:H7. In summary, this study illustrates the potential of simultaneously using a combination of sublethal concentrations of natural antimicrobials and a low level of physical stress in the form of UV-A light to inactivate bacteria in water and food systems. IMPORTANCE There is a critical unmet need to improve the microbial safety of the food supply, while retaining optimal nutritional and sensory properties of food. Furthermore, there is a need to develop novel technologies that can reduce the impact of food processing operations on energy and water resources. Conventionally, physical processes such as heat and light are used for inactivating microbes in food products, but these processes often significantly reduce the sensory and nutritional properties of food and are highly energy intensive. This study demonstrates that the combination of two natural food-grade antimicrobial agents with a sublethal level of physical stress in the form of UV-A light can greatly increase microbial load inactivation. In addition, this report elucidates the potential mechanisms for this synergistic interaction among physical and chemical stresses. Overall, these results provide a novel approach to develop antimicrobial solutions for food and water systems. Copyright © 2017 American Society for Microbiology.

The association of GSK3 beta with E2F1 facilitates nerve growth factor-induced neural cell differentiation.

PubMed

Zhou, Fangfang; Zhang, Long; Wang, Aijun; Song, Bo; Gong, Kai; Zhang, Lihai; Hu, Min; Zhang, Xiufang; Zhao, Nanming; Gong, Yandao

2008-05-23

It is widely acknowledged that E2F1 and GSK3beta are both involved in the process of cell differentiation. However, the relationship between E2F1 and GSK3beta in cell differentiation has yet to be discovered. Here, we provide evidence that in the differentiation of PC12 cells induced by nerve growth factor (NGF), GSK3beta was increased at both the mRNA and protein levels, whereas E2F1 at these two levels was decreased. Both wild-type GSK3beta and its kinase-defective mutant GSK3beta KM can inhibit E2F1 by promoting its ubiquitination through physical interaction. In addition, the colocalization of GSK3beta and E2F1 and their subcellular distribution, regulated by NGF, were observed in the process of PC12 differentiation. At the tissue level, GSK3beta colocalized and interacted with E2F1 in mouse hippocampus. Furthermore, GSK3beta facilitated neurite outgrowth by rescuing the promoter activities of Cdk inhibitors p21 and p15 from the inhibition caused by E2F1. To summarize, our findings suggest that GSK3beta can promote the ubiquitination of E2F1 via physical interaction and thus inhibit its transcription activity in a kinase activity independent manner, which plays an important role in the NGF-induced PC12 differentiation.

Highly elastic polymer solutions under shear: Polymer migration, viscoelastic instabilities, and anomalous rheology

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

MacDonald, M.J.; Muller, S.J.

1996-12-31

The use of highly elastic polymer solutions has been remarkably successful in elucidating the behavior of polymeric materials under flowing conditions. Here, we present the results of an extensive experimental study into the shear behavior of an athermal, dilute, binary polymer solution that is believed to be free of many of these effects. Under extended shearing, we observe the migration of polymer species: after shearing for several hundred hours, concentrations that are more than double the initial uniform value can be achieved. Although the solutions are well-described by dumbbell models in shear flows on short-time scales, theoretical predictions substantially underestimatemore » the rate of migration. Flow visualization and rheometric experiments suggest that the origin of this discrepancy could be the anomalous long-time rheology of these solutions. While these fluids display the well-known elastic instability in cone and plate flow above a critical Deborah number, extended shearing reveals that the toroidal secondary flow is eventually replaced by a purely azimuthal shearing flow. In addition, when sheared below the critical condition for the instability, the solutions exhibit a slow but reversible decay in normal stresses. The shear-induced migration of polymer species has been predicted by numerous theoretical studies. However, observations on the highly elastic polymer solutions that are most likely to show polymer migration, are complicated by a number of different physical processes that occur as a result of shearing. These phenomena, which include shear-induced phase separation, elastically-induced hydrodynamic instabilities, mixed solvent effects, shear-induced aggregation, and anomalous transient shear and normal stress behavior are often observed at times earlier than and at shear rates less than those where migration is predicted to occur; hence, the experimental detection of polymer migration has been thwarted by these other physical processes.« less

Biological Dimensions of Crack Morphology in Dryland Soils

NASA Astrophysics Data System (ADS)

DeCarlo, K. F.; Spiegel, M.; Caylor, K. K.

2014-12-01

Macropores and cracks have an integral role in soil hydrology, and the physicochemical factors that induce them have been the subject of much laboratory research. How these processes translate to field soils, however, is often obfuscated by the biological elements present that complicate its formation and dynamics. In this study, we investigated the biological influence of herbivores and vegetation on 3D crack morphology in a dryland swelling soil (black cotton/vertisol). Fieldwork was conducted at and near the Kenya Long-Term Exclosure Experiment (KLEE) plots in Mpala, central Kenya, where three different soil regions were identified: highly vegetated areas, animal trails, and termite mounds. Crack networks were physically characterized by pouring liquid resin into the soil and excavating them when dry, after which they were imaged and quantified using medical magnetic resonance imaging (MRI). Cracking intensity of each cast was corrected via soil moisture and bulk density measurements at 5 cm intervals over 30 cm. 3D characterization of the soil system shows that mechanical compaction is a major influence in the formation of extensive and deep cracks in animal trails, with megaherbivores (e.g. elephants) inducing the most extreme cracks. Bioturbation is seen as a major influence in the formation of shallower cracks in termite mounds, as termites loosen and aerate the soil and reduce the soil's cohesive properties. Highly vegetated soils show a large degree of variability: small, disconnected soil patches induced by vegetative cover and a larger root network results in smaller and shallower cracks, but full vegetative cover induces deep and irregular cracks, possibly due to diverted rainfall. Our results highlight the intricate connections between the biology and physics that dictate soil processes in a complex soil system at the field scale.

Asymmetrically interacting spreading dynamics on complex layered networks.

PubMed

Wang, Wei; Tang, Ming; Yang, Hui; Younghae Do; Lai, Ying-Cheng; Lee, GyuWon

2014-05-29

The spread of disease through a physical-contact network and the spread of information about the disease on a communication network are two intimately related dynamical processes. We investigate the asymmetrical interplay between the two types of spreading dynamics, each occurring on its own layer, by focusing on the two fundamental quantities underlying any spreading process: epidemic threshold and the final infection ratio. We find that an epidemic outbreak on the contact layer can induce an outbreak on the communication layer, and information spreading can effectively raise the epidemic threshold. When structural correlation exists between the two layers, the information threshold remains unchanged but the epidemic threshold can be enhanced, making the contact layer more resilient to epidemic outbreak. We develop a physical theory to understand the intricate interplay between the two types of spreading dynamics.

Asymmetrically interacting spreading dynamics on complex layered networks

PubMed Central

Wang, Wei; Tang, Ming; Yang, Hui; Younghae Do; Lai, Ying-Cheng; Lee, GyuWon

2014-01-01

The spread of disease through a physical-contact network and the spread of information about the disease on a communication network are two intimately related dynamical processes. We investigate the asymmetrical interplay between the two types of spreading dynamics, each occurring on its own layer, by focusing on the two fundamental quantities underlying any spreading process: epidemic threshold and the final infection ratio. We find that an epidemic outbreak on the contact layer can induce an outbreak on the communication layer, and information spreading can effectively raise the epidemic threshold. When structural correlation exists between the two layers, the information threshold remains unchanged but the epidemic threshold can be enhanced, making the contact layer more resilient to epidemic outbreak. We develop a physical theory to understand the intricate interplay between the two types of spreading dynamics. PMID:24872257

High-Intensity Ultrasound to Improve Physical and Functional Properties of Lipids.

PubMed

Wagh, Ashwini; Birkin, Peter; Martini, Silvana

2016-01-01

High-intensity ultrasound (HIU) has been used in recent years to change the crystallization behavior of edible lipids. This technique can be used in combination with other processing technologies to tailor lipids' functional properties and broaden their application for various food products. In general, sonication induces crystallization, increases crystallization rate, and generates a harder and more elastic crystalline network characterized by smaller crystals with a sharper melting profile. An important application of HIU is to improve the hardness and elasticity of shortenings that have a low content of saturated fatty acids and are free of trans-fats. This review summarizes recent research that used HIU to change the physical and functional properties of edible lipids and focuses on the importance of controlling processing variables such as sonication power level and duration and crystallization temperature.

Classroom-Based Physical Activity Breaks and Children's Attention: Cognitive Engagement Works!

PubMed Central

Schmidt, Mirko; Benzing, Valentin; Kamer, Mario

2016-01-01

Classroom-based physical activity breaks are postulated to positively impact children's attention during their school day. However, empirical evidence for this claim is scarce and the role of cognitive engagement in enhancing children's attentional performance is unexplored in studies on physical activity breaks. The aim of the present study was therefore to disentangle the separate and/or combined effects of physical exertion and cognitive engagement induced by physical activity breaks on primary school children's attention. In addition, the role of children's affective reactions to acute interventions at school was investigated. Using a 2 × 2 between-subjects experimental design, 92 children between the ages of 11 and 12 years (M = 11.77, SD = 0.41) were randomly assigned to one of four experimental conditions: (1) combo group (physical activity with high cognitive demands), (2) cognition group (sedentary with high cognitive demands), (3) physical group (physical activity with low cognitive demands), and (4) control group (sedentary with low cognitive demands). Attention and affect were measured before and immediately after a 10-min intervention. ANCOVAs revealed that whereas physical exertion had no effect on any measure of children's attentional performance, cognitive engagement was the crucial factor leading to increased focused attention and enhanced processing speed. Mediational analyses showed that changes in positive affect during the interventions mediated the effect between cognitive engagement and focused attention as well as between cognitive engagement and processing speed. These surprising results are discussed in the light of theories predicting both facilitating and deteriorative effects of positive affect on attention. PMID:27757088

Effect of humic acids on intestinal viscosity, leaky gut and ammonia excretion in a 24 h feed restriction model to induce intestinal permeability in broiler chickens

USDA-ARS?s Scientific Manuscript database

Humic acids (HA) are produced by biodegradation of organic matter that involves physical, chemical and microbiological processes, hence, HA are a complex mixture of many different acids containing carboxyl and phenolate groups. The purpose of this study was to evaluate the effect of HA on intestina...

Joint Services Electronics Program.

DTIC Science & Technology

1987-10-15

semiconductor perturb the index of refraction which can be detected in a Nomarski -type optical interferometer. For example, we have demonstrated the real-time...probe relies on a different physical effect and operates by interferometrically detecting the phase change induced in an optical beam by the presence of... interferometric diameter measurement system to monitor the growth process, has been in operation for . several years. The focussing optics and pulling mechanisms

The implicit processing of categorical and dimensional strategies: an fMRI study of facial emotion perception

PubMed Central

Matsuda, Yoshi-Taka; Fujimura, Tomomi; Katahira, Kentaro; Okada, Masato; Ueno, Kenichi; Cheng, Kang; Okanoya, Kazuo

2013-01-01

Our understanding of facial emotion perception has been dominated by two seemingly opposing theories: the categorical and dimensional theories. However, we have recently demonstrated that hybrid processing involving both categorical and dimensional perception can be induced in an implicit manner (Fujimura etal., 2012). The underlying neural mechanisms of this hybrid processing remain unknown. In this study, we tested the hypothesis that separate neural loci might intrinsically encode categorical and dimensional processing functions that serve as a basis for hybrid processing. We used functional magnetic resonance imaging to measure neural correlates while subjects passively viewed emotional faces and performed tasks that were unrelated to facial emotion processing. Activity in the right fusiform face area (FFA) increased in response to psychologically obvious emotions and decreased in response to ambiguous expressions, demonstrating the role of the FFA in categorical processing. The amygdala, insula and medial prefrontal cortex exhibited evidence of dimensional (linear) processing that correlated with physical changes in the emotional face stimuli. The occipital face area and superior temporal sulcus did not respond to these changes in the presented stimuli. Our results indicated that distinct neural loci process the physical and psychological aspects of facial emotion perception in a region-specific and implicit manner. PMID:24133426

Composite Cure Process Modeling and Simulations using COMPRO(Registered Trademark) and Validation of Residual Strains using Fiber Optics Sensors

NASA Technical Reports Server (NTRS)

Sreekantamurthy, Thammaiah; Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.

2016-01-01

Composite cure process induced residual strains and warping deformations in composite components present significant challenges in the manufacturing of advanced composite structure. As a part of the Manufacturing Process and Simulation initiative of the NASA Advanced Composite Project (ACP), research is being conducted on the composite cure process by developing an understanding of the fundamental mechanisms by which the process induced factors influence the residual responses. In this regard, analytical studies have been conducted on the cure process modeling of composite structural parts with varied physical, thermal, and resin flow process characteristics. The cure process simulation results were analyzed to interpret the cure response predictions based on the underlying physics incorporated into the modeling tool. In the cure-kinetic analysis, the model predictions on the degree of cure, resin viscosity and modulus were interpreted with reference to the temperature distribution in the composite panel part and tool setup during autoclave or hot-press curing cycles. In the fiber-bed compaction simulation, the pore pressure and resin flow velocity in the porous media models, and the compaction strain responses under applied pressure were studied to interpret the fiber volume fraction distribution predictions. In the structural simulation, the effect of temperature on the resin and ply modulus, and thermal coefficient changes during curing on predicted mechanical strains and chemical cure shrinkage strains were studied to understand the residual strains and stress response predictions. In addition to computational analysis, experimental studies were conducted to measure strains during the curing of laminated panels by means of optical fiber Bragg grating sensors (FBGs) embedded in the resin impregnated panels. The residual strain measurements from laboratory tests were then compared with the analytical model predictions. The paper describes the cure process procedures and residual strain predications, and discusses pertinent experimental results from the validation studies.

Ethylene-induced differential gene expression during abscission of citrus leaves

PubMed Central

Merelo, Paz; Cercós, Manuel; Tadeo, Francisco R.; Talón, Manuel

2008-01-01

The main objective of this work was to identify and classify genes involved in the process of leaf abscission in Clementina de Nules (Citrus clementina Hort. Ex Tan.). A 7 K unigene citrus cDNA microarray containing 12 K spots was used to characterize the transcriptome of the ethylene-induced abscission process in laminar abscission zone-enriched tissues and the petiole of debladed leaf explants. In these conditions, ethylene induced 100% leaf explant abscission in 72 h while, in air-treated samples, the abscission period started later and took 240 h. Gene expression monitored during the first 36 h of ethylene treatment showed that out of the 12 672 cDNA microarray probes, ethylene differentially induced 725 probes distributed as follows: 216 (29.8%) probes in the laminar abscission zone and 509 (70.2%) in the petiole. Functional MIPS classification and manual annotation of differentially expressed genes highlighted key processes regulating the activation and progress of the cell separation that brings about abscission. These included cell-wall modification, lipid transport, protein biosynthesis and degradation, and differential activation of signal transduction and transcription control pathways. Expression data associated with the petiole indicated the occurrence of a double defensive strategy mediated by the activation of a biochemical programme including scavenging ROS, defence and PR genes, and a physical response mostly based on lignin biosynthesis and deposition. This work identifies new genes probably involved in the onset and development of the leaf abscission process and suggests a different but co-ordinated and complementary role for the laminar abscission zone and the petiole during the process of abscission. PMID:18515267

Particle-induced viscous fingering

NASA Astrophysics Data System (ADS)

Lee, Sungyon

2017-11-01

An inclusion of non-colloidal particles in a Newtonian liquid can fundamentally change the interfacial dynamics and even cause interfacial instabilities. In this talk, we report a particle-induced fingering instability when a mixture of particles and viscous oil is injected radially into a Hele-Shaw cell. Our experimental results show that the onset and characteristics of fingering are most directly affected by the particle volume fraction but also depend on the ratio of the particle diameter to gap size. In particular, the formation of a particle band is observed on the interface only when the particle diameter is comparable to the channel gap thickness. This work demonstrates the complex coupling between suspensions and fluid-fluid interfaces and has broad relevance in suspension processing, particle self-assembly, and oil recovery processes. The physical mechanism behind the instability and a quantitative model are also discussed.

Wiring Damage Analyses for STS OV-103

NASA Technical Reports Server (NTRS)

Thomas, Walter, III

2006-01-01

This study investigated the Shuttle Program s belief that Space Transportation System (STS) wiring damage occurrences are random, that is, a constant occurrence rate. Using Problem Reporting and Corrective Action (PRACA)-derived data for STS Space Shuttle OV-103, wiring damage was observed to increase over the vehicle s life. Causal factors could include wiring physical deterioration, maintenance and inspection induced damage, and inspection process changes resulting in more damage events being reported. Induced damage effects cannot be resolved with existent data. Growth analysis (using Crow-AMSAA, or CA) resolved maintenance/inspection effects (e.g., heightened awareness) on all wire damages and indicated an overall increase since Challenger Return-to-Flight (RTF). An increasing failure or occurrence rate per flight cycle was seen for each wire damage mode; these (individual) rates were not affected by inspection process effects, within statistical error.

A model for traumatic brain injury using laser induced shockwaves

NASA Astrophysics Data System (ADS)

Selfridge, A.; Preece, D.; Gomez, V.; Shi, L. Z.; Berns, M. W.

2015-08-01

Traumatic brain injury (TBI) represents a major treatment challenge in both civilian and military medicine; on the cellular level, its mechanisms are poorly understood. As a method to study the dysfunctional repair mechanisms following injury, laser induced shock waves (LIS) are a useful way to create highly precise, well characterized mechanical forces. We present a simple model for TBI using laser induced shock waves as a model for damage. Our objective is to develop an understanding of the processes responsible for neuronal death, the ways in which we can manipulate these processes to improve cell survival and repair, and the importance of these processes at different levels of biological organization. The physics of shock wave creation has been modeled and can be used to calculate forces acting on individual neurons. By ensuring that the impulse is in the same regime as that occurring in practical TBI, the LIS model can ensure that in vitro conditions and damage are similar to those experienced in TBI. This model will allow for the study of the biochemical response of neurons to mechanical stresses, and can be combined with microfluidic systems for cell growth in order to better isolate areas of damage.

Quantum Hooke's Law to Classify Pulse Laser Induced Ultrafast Melting

NASA Astrophysics Data System (ADS)

Hu, Hao; Ding, Hepeng; Liu, Feng

2014-03-01

We investigate the ultrafast crystal-to-amorphous phase transition induced by femtosecond pulse laser excitation by exploiting the property of quantum electronic stress (QES) induced by the electron-hole plasma, which follows quantum Hooke's law. We demonstrates that two types of crystal-to-amorphous transitions occur in two distinct material classes: the faster nonthermal process, having a time scale shorter than one picosecond (ps), must occur in materials like ice having an anomalous phase diagram characterized with dTm/dP <0, where Tm is the melting temperature and P is pressure; while the slower thermal process, having a time scale of several ps, occurs preferably in other materials. The nonthermal process is driven by the QES acting like a negative internal pressure, which is generated predominantly by the holes in the electron-hole plasma that increases linearly with hole density. These findings significantly advance our fundamental understanding of physics underlying the ultrafast crystal-to-amorphous phase transitions, enabling quantitative a priori prediction. The work was supported by DOE-BES (Grant # DE-FG02-04ER46148), NSF MRSEC (Grant No. DMR-1121252) and DOE EFRC (Grant Number DE-SC0001061).

Final Report: Mechanisms of sputter ripple formation: coupling among energetic ions, surface kinetics, stress and composition

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

Chason, Eric; Shenoy, Vivek

Self-organized pattern formation enables the creation of nanoscale surface structures over large areas based on fundamental physical processes rather than an applied template. Low energy ion bombardment is one such method that induces the spontaneous formation of a wide variety of interesting morphological features (e.g., sputter ripples and/or quantum dots). This program focused on the processes controlling sputter ripple formation and the kinetics controlling the evolution of surfaces and nanostructures in high flux environments. This was done by using systematic, quantitative experiments to measure ripple formation under a variety of processing conditions coupled with modeling to interpret the results.

Discrete Element Method and its application to materials failure problem on the example of Brazilian Test

NASA Astrophysics Data System (ADS)

Klejment, Piotr; Kosmala, Alicja; Foltyn, Natalia; Dębski, Wojciech

2017-04-01

The earthquake focus is the point where a rock under external stress starts to fracture. Understanding earthquake nucleation and earthquake dynamics requires thus understanding of fracturing of brittle materials. This, however, is a continuing problem and enduring challenge to geoscience. In spite of significant progress we still do not fully understand the failure of rock materials due to extreme stress concentration in natural condition. One of the reason of this situation is that information about natural or induced seismic events is still not sufficient for precise description of physical processes in seismic foci. One of the possibility of improving this situation is using numerical simulations - a powerful tool of contemporary physics. For this reason we used an advanced implementation of the Discrete Element Method (DEM). DEM's main task is to calculate physical properties of materials which are represented as an assembly of a great number of particles interacting with each other. We analyze the possibility of using DEM for describing materials during so called Brazilian Test. Brazilian Test is a testing method to obtain the tensile strength of brittle material. One of the primary reasons for conducting such simulations is to measure macroscopic parameters of the rock sample. We would like to report our efforts of describing the fracturing process during the Brazilian Test from the microscopic point of view and give an insight into physical processes preceding materials failure.

Transforming community access to space science models

NASA Astrophysics Data System (ADS)

MacNeice, Peter; Hesse, Michael; Kuznetsova, Maria; Maddox, Marlo; Rastaetter, Lutz; Berrios, David; Pulkkinen, Antti

2012-04-01

Researching and forecasting the ever changing space environment (often referred to as space weather) and its influence on humans and their activities are model-intensive disciplines. This is true because the physical processes involved are complex, but, in contrast to terrestrial weather, the supporting observations are typically sparse. Models play a vital role in establishing a physically meaningful context for interpreting limited observations, testing theory, and producing both nowcasts and forecasts. For example, with accurate forecasting of hazardous space weather conditions, spacecraft operators can place sensitive systems in safe modes, and power utilities can protect critical network components from damage caused by large currents induced in transmission lines by geomagnetic storms.

Transforming Community Access to Space Science Models

NASA Technical Reports Server (NTRS)

MacNeice, Peter; Heese, Michael; Kunetsova, Maria; Maddox, Marlo; Rastaetter, Lutz; Berrios, David; Pulkkinen, Antti

2012-01-01

Researching and forecasting the ever changing space environment (often referred to as space weather) and its influence on humans and their activities are model-intensive disciplines. This is true because the physical processes involved are complex, but, in contrast to terrestrial weather, the supporting observations are typically sparse. Models play a vital role in establishing a physically meaningful context for interpreting limited observations, testing theory, and producing both nowcasts and forecasts. For example, with accurate forecasting of hazardous space weather conditions, spacecraft operators can place sensitive systems in safe modes, and power utilities can protect critical network components from damage caused by large currents induced in transmission lines by geomagnetic storms.

Pain Processing after Social Exclusion and Its Relation to Rejection Sensitivity in Borderline Personality Disorder

PubMed Central

Bungert, Melanie; Koppe, Georgia; Niedtfeld, Inga; Vollstädt-Klein, Sabine; Schmahl, Christian

2015-01-01

Objective There is a general agreement that physical pain serves as an alarm signal for the prevention of and reaction to physical harm. It has recently been hypothesized that “social pain,” as induced by social rejection or abandonment, may rely on comparable, phylogenetically old brain structures. As plausible as this theory may sound, scientific evidence for this idea is sparse. This study therefore attempts to link both types of pain directly. We studied patients with borderline personality disorder (BPD) because BPD is characterized by opposing alterations in physical and social pain; hyposensitivity to physical pain is associated with hypersensitivity to social pain, as indicated by an enhanced rejection sensitivity. Method Twenty unmedicated female BPD patients and 20 healthy participants (HC, matched for age and education) played a virtual ball-tossing game (cyberball), with the conditions for exclusion, inclusion, and a control condition with predefined game rules. Each cyberball block was followed by a temperature stimulus (with a subjective pain intensity of 60% in half the cases). The cerebral responses were measured by functional magnetic resonance imaging. The Adult Rejection Sensitivity Questionnaire was used to assess rejection sensitivity. Results Higher temperature heat stimuli had to be applied to BPD patients relative to HCs to reach a comparable subjective experience of painfulness in both groups, which suggested a general hyposensitivity to pain in BPD patients. Social exclusion led to a subjectively reported hypersensitivity to physical pain in both groups that was accompanied by an enhanced activation in the anterior insula and the thalamus. In BPD, physical pain processing after exclusion was additionally linked to enhanced posterior insula activation. After inclusion, BPD patients showed reduced amygdala activation during pain in comparison with HC. In BPD patients, higher rejection sensitivity was associated with lower activation differences during pain processing following social exclusion and inclusion in the insula and in the amygdala. Discussion Despite the similar behavioral effects in both groups, BPD patients differed from HC in their neural processing of physical pain depending on the preceding social situation. Rejection sensitivity further modulated the impact of social exclusion on neural pain processing in BPD, but not in healthy controls. PMID:26241850

Platelet size and density affect shear-induced thrombus formation in tortuous arterioles

NASA Astrophysics Data System (ADS)

Chesnutt, Jennifer K. W.; Han, Hai-Chao

2013-10-01

Thrombosis accounts for 80% of deaths in patients with diabetes mellitus. Diabetic patients demonstrate tortuous microvessels and larger than normal platelets. Large platelets are associated with increased platelet activation and thrombosis, but the physical effects of large platelets in the microscale processes of thrombus formation are not clear. Therefore, the objective of this study was to determine the physical effects of mean platelet volume (MPV), mean platelet density (MPD) and vessel tortuosity on platelet activation and thrombus formation in tortuous arterioles. A computational model of the transport, shear-induced activation, collision, adhesion and aggregation of individual platelets was used to simulate platelet interactions and thrombus formation in tortuous arterioles. Our results showed that an increase in MPV resulted in a larger number of activated platelets, though MPD and level of tortuosity made little difference on platelet activation. Platelets with normal MPD yielded the lowest amount of mural thrombus. With platelets of normal MPD, the amount of mural thrombus decreased with increasing level of tortuosity but did not have a simple monotonic relationship with MPV. The physical mechanisms associated with MPV, MPD and arteriole tortuosity play important roles in platelet activation and thrombus formation.

Nuclear Physics with 10 PW laser beams at Extreme Light Infrastructure - Nuclear Physics (ELI-NP)

NASA Astrophysics Data System (ADS)

Zamfir, N. V.

2014-05-01

The field of the uncharted territory of high-intensity laser interaction with matter is confronted with new exotic phenomena and, consequently, opens new research perspectives. The intense laser beams interacting with a gas or solid target generate beams of electrons, protons and ions. These beams can induce nuclear reactions. Electrons also generate ions high-energy photons via bremsstrahlung processes which can also induce nuclear reactions. In this context a new research domain began to form in the last decade or so, namely nuclear physics with high power lasers. The observation of high brilliance proton beams of tens of MeV energy from solid targets has stimulated an intense research activity. The laser-driven particle beams have to compete with conventional nuclear accelerator-generated beams. The ultimate goal is aiming at applications of the laser produced beams in research, technology and medicine. The mechanism responsible for ion acceleration are currently subject of intensive research in many laboratories in the world. The existing results, experimental and theoretical, and their perspectives are reviewed in this article in the context of IZEST and the scientific program of ELI-NP.

Fracture induced electromagnetic emissions: extending laboratory findings by observations at the geophysical scale

NASA Astrophysics Data System (ADS)

Potirakis, Stelios M.; Contoyiannis, Yiannis; Kopanas, John; Kalimeris, Anastasios; Antonopoulos, George; Peratzakis, Athanasios; Eftaxias, Konstantinos; Nomicos, Constantinos

2014-05-01

Under natural conditions, it is practically impossible to install an experimental network on the geophysical scale using the same instrumentations as in laboratory experiments for understanding, through the states of stress and strain and their time variation, the laws that govern the friction during the last stages of EQ generation, or to monitor (much less to control) the principal characteristics of a fracture process. Fracture-induced electromagnetic emissions (EME) in a wide range of frequency bands are sensitive to the micro-structural chances. Thus, their study constitutes a nondestructive method for the monitoring of the evolution of damage process at the laboratory scale. It has been suggested that fracture induced MHz-kHz electromagnetic (EM) emissions, which emerge from a few days up to a few hours before the main seismic shock occurrence permit a real time monitoring of the damage process during the last stages of earthquake preparation, as it happens at the laboratory scale. Since the EME are produced both in the case of the laboratory scale fracture and the EQ preparation process (geophysical scale fracture) they should present similar characteristics in these two scales. Therefore, both the laboratory experimenting scientists and the experimental scientists studying the pre-earthquake EME could benefit from each- other's results. Importantly, it is noted that when studying the fracture process by means of laboratory experiments, the fault growth process normally occurs violently in a fraction of a second. However, a major difference between the laboratory and natural processes is the order-of-magnitude differences in scale (in space and time), allowing the possibility of experimental observation at the geophysical scale for a range of physical processes which are not observable at the laboratory scale. Therefore, the study of fracture-induced EME is expected to reveal more information, especially for the last stages of the fracture process, when it is conducted at the geophysical scale. As a characteristic example, we discuss about the case of electromagnetic silence before the global rupture that was first observed in preseismic EME and recently was also observed in the EME measured during laboratory fracture experiments, completely revising the earlier views about the fracture-induced electromagnetic emissions.

RAD18 and associated proteins are immobilized in nuclear foci in human cells entering S-phase with ultraviolet light-induced damage

PubMed Central

Watson, Nicholas B.; Nelson, Eric; Digman, Michelle; Thornburg, Joshua A.; Alphenaar, Bruce W.; McGregor, W. Glenn

2008-01-01

Proteins required for translesion DNA synthesis localize in nuclear foci of cells with replication-blocking lesions. The dynamics of this process were examined in human cells with fluorescence-based biophysical techniques. Photobleaching recovery and raster image correlation spectroscopy experiments indicated that involvement in the nuclear foci reduced the movement of RAD18 from diffusion-controlled to virtual immobility. Examination of the mobility of REV1 indicated that it is similarly immobilized when it is observed in nuclear foci. Reducing the level of RAD18 greatly reduced the focal accumulation of REV1 and reduced UV mutagenesis to background frequencies. Fluorescence lifetime measurements indicated that RAD18 and RAD6A or polη only transferred resonance energy when these proteins colocalized in damage-induced nuclear foci, indicating a close physical association only within such foci. Our data support a model in which RAD18 within damage-induced nuclear foci is immobilized and is required for recruitment of Y-family DNA polymerases and subsequent mutagenesis. In the absence of damage these proteins are not physically associated within the nucleoplasm. PMID:18926833

High-speed manufacturing of highly regular femtosecond laser-induced periodic surface structures: physical origin of regularity.

PubMed

Gnilitskyi, Iaroslav; Derrien, Thibault J-Y; Levy, Yoann; Bulgakova, Nadezhda M; Mocek, Tomáš; Orazi, Leonardo

2017-08-16

Highly regular laser-induced periodic surface structures (HR-LIPSS) have been fabricated on surfaces of Mo, steel alloy and Ti at a record processing speed on large areas and with a record regularity in the obtained sub-wavelength structures. The physical mechanisms governing LIPSS regularity are identified and linked with the decay length (i.e. the mean free path) of the excited surface electromagnetic waves (SEWs). The dispersion of the LIPSS orientation angle well correlates with the SEWs decay length: the shorter this length, the more regular are the LIPSS. A material dependent criterion for obtaining HR-LIPSS is proposed for a large variety of metallic materials. It has been found that decreasing the spot size close to the SEW decay length is a key for covering several cm 2 of material surface by HR-LIPSS in a few seconds. Theoretical predictions suggest that reducing the laser wavelength can provide the possibility of HR-LIPSS production on principally any metal. This new achievement in the unprecedented level of control over the laser-induced periodic structure formation makes this laser-writing technology to be flexible, robust and, hence, highly competitive for advanced industrial applications based on surface nanostructuring.

Physical origin of the incubation time of self-induced GaN nanowires

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

Consonni, V.; Trampert, A.; Geelhaar, L.

2011-07-18

The nucleation process of self-induced GaN nanowires grown by molecular beam epitaxy has been investigated by reflection high-energy electron diffraction measurements. It is found that stable nuclei in the form of spherical cap-shaped islands develop only after an incubation time that is strongly dependent upon the growth conditions. Its evolution with the growth temperature and gallium rate has been described within standard island nucleation theory, revealing a nucleation energy of 4.9 {+-} 0.1 eV and a very small nucleus critical size. The consideration of the incubation time is critical for the control of the nanowire morphology.

[INVITED] Laser-induced forward transfer: A high resolution additive manufacturing technology

NASA Astrophysics Data System (ADS)

Delaporte, Philippe; Alloncle, Anne-Patricia

2016-04-01

Among the additive manufacturing techniques, laser-induced forward transfer addresses the challenges of printing thin films in solid phase or small volume droplets in liquid phase with very high resolution. This paper reviews the physics of this process and explores the pros and cons of this technology versus other digital printing technologies. The main field of applications are printed electronics, organic electronics and tissue engineering, and the most promising short terms ones concern digital laser printing of sensors and conductive tracks. Future directions and emerging areas of interest are discussed such as printing solid from a liquid phase and 3D digital nanomanufacturing.

Nuclear Astrophysics at DANCE

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

Reifarth, R.; Bredeweg, T.A.; Esch, E.-I.

2005-05-24

One of the most interesting nuclear physics challenges is obtaining a detailed understanding of the nucleosynthesis processes of the elements. Knowledge about the stellar sites, and how they are governed by stellar evolution and cosmology are crucial in understanding the overall picture. Information on reaction rates for neutron- and charged-particle-induced reactions have a direct impact on existing stellar models. Except for the stable isotopes, very few neutron-induced reactions in the energy range of interest have been measured to date. DANCE measurements on stable and unstable isotopes will provide many of the missing key reactions that are needed to understand themore » nucleosynthesis of the heavy elements.« less

Earthworm responses to different reclamation processes in post opencast mining lands during succession.

PubMed

Hlava, Jakub; Hlavová, Anna; Hakl, Josef; Fér, Miroslav

2015-01-01

This study provides earthworm population data obtained from localities with a substantial anthropogenic impact spoils. The spoil heaps were reclaimed at the end of an opencast brown coal mining period. We studied spoils reclaimed by the two most commonly used reclamation processes: forestry and agricultural. The results show the significance of the locality age and the utilized reclamation process and treatment and their effect on earthworm communities. Our data indicate that apart from soil physical and chemical properties, the reclamation process itself may also induce viability and distribution of earthworm communities. Under standardized soil properties, the changes in earthworm populations during the succession were larger within the agricultural reclamation process as opposed to the forestry reclamation process for earthworm ecological groups and individual species.

The mechanism of valence-space metaphors: ERP evidence for affective word processing.

PubMed

Xie, Jiushu; Wang, Ruiming; Chang, Song

2014-01-01

Embodied cognition contends that the representation and processing of concepts involve perceptual, somatosensory, motoric, and other physical re-experiencing information. In this view, affective concepts are also grounded in physical information. For instance, people often say "feeling down" or "cheer up" in daily life. These phrases use spatial information to understand affective concepts. This process is referred to as valence-space metaphor. Valence-space metaphors refer to the employment of spatial information (lower/higher space) to elaborate affective concepts (negative/positive concepts). Previous studies have demonstrated that processing affective words affects performance on a spatial detection task. However, the mechanism(s) behind this effect remain unclear. In the current study, we hypothesized that processing affective words might produce spatial information. Consequently, spatial information would affect the following spatial cue detection/discrimination task. In Experiment 1, participants were asked to remember an affective word. Then, they completed a spatial cue detection task while event-related potentials were recorded. The results indicated that the top cues induced enhanced amplitude of P200 component while participants kept positive words relative to negative words in mind. On the contrary, the bottom cues induced enhanced P200 amplitudes while participants kept negative words relative to positive words in mind. In Experiment 2, we conducted a behavioral experiment that employed a similar paradigm to Experiment 1, but used arrows instead of dots to test the attentional nature of the valence-space metaphor. We found a similar facilitation effect as found in Experiment 1. Positive words facilitated the discrimination of upper arrows, whereas negative words facilitated the discrimination of lower arrows. In summary, affective words might activate spatial information and cause participants to allocate their attention to corresponding locations. Valence-space metaphors might be grounded in attention allocation.

Hurricane Ike: Observations and Analysis of Coastal Change

USGS Publications Warehouse

Doran, Kara S.; Plant, Nathaniel G.; Stockdon, Hilary F.; Sallenger, Asbury H.; Serafin, Katherine A.

2009-01-01

Understanding storm-induced coastal change and forecasting these changes require knowledge of the physical processes associated with the storm and the geomorphology of the impacted coastline. The primary physical processes of interest are the wind field, storm surge, and wave climate. Not only does wind cause direct damage to structures along the coast, but it is ultimately responsible for much of the energy that is transferred to the ocean and expressed as storm surge, mean currents, and large waves. Waves and currents are the processes most responsible for moving sediments in the coastal zone during extreme storm events. Storm surge, the rise in water level due to the wind, barometric pressure, and other factors, allows both waves and currents to attack parts of the coast not normally exposed to those processes. Coastal geomorphology, including shapes of the shoreline, beaches, and dunes, is equally important to the coastal change observed during extreme storm events. Relevant geomorphic variables include sand dune elevation, beach width, shoreline position, sediment grain size, and foreshore beach slope. These variables, in addition to hydrodynamic processes, can be used to predict coastal vulnerability to storms The U.S. Geological Survey's (USGS) National Assessment of Coastal Change Hazards Project (http://coastal.er.usgs.gov/hurricanes), strives to provide hazard information to those interested in the Nation's coastlines, including residents of coastal areas, government agencies responsible for coastal management, and coastal researchers. As part of the National Assessment, observations were collected to measure coastal changes associated with Hurricane Ike, which made landfall near Galveston, Texas, on September 13, 2008. Methods of observation included aerial photography and airborne topographic surveys. This report documents these data-collection efforts and presents qualitative and quantitative descriptions of hurricane-induced changes to the shoreline, beaches, dunes, and infrastructure in the region that was heavily impacted by Hurricane Ike.

MCNP6.1 simulations for low-energy atomic relaxation: Code-to-code comparison with GATEv7.2, PENELOPE2014, and EGSnrc

NASA Astrophysics Data System (ADS)

Jung, Seongmoon; Sung, Wonmo; Lee, Jaegi; Ye, Sung-Joon

2018-01-01

Emerging radiological applications of gold nanoparticles demand low-energy electron/photon transport calculations including details of an atomic relaxation process. Recently, MCNP® version 6.1 (MCNP6.1) has been released with extended cross-sections for low-energy electron/photon, subshell photoelectric cross-sections, and more detailed atomic relaxation data than the previous versions. With this new feature, the atomic relaxation process of MCNP6.1 has not been fully tested yet with its new physics library (eprdata12) that is based on the Evaluated Atomic Data Library (EADL). In this study, MCNP6.1 was compared with GATEv7.2, PENELOPE2014, and EGSnrc that have been often used to simulate low-energy atomic relaxation processes. The simulations were performed to acquire both photon and electron spectra produced by interactions of 15 keV electrons or photons with a 10-nm-thick gold nano-slab. The photon-induced fluorescence X-rays from MCNP6.1 fairly agreed with those from GATEv7.2 and PENELOPE2014, while the electron-induced fluorescence X-rays of the four codes showed more or less discrepancies. A coincidence was observed in the photon-induced Auger electrons simulated by MCNP6.1 and GATEv7.2. A recent release of MCNP6.1 with eprdata12 can be used to simulate the photon-induced atomic relaxation.

The use of laser-induced shock wave plasma spectroscopy (LISPS) for examining physical characteristics of pharmaceutical products

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

Abdulmadjid, Syahrun Nur, E-mail: syahrun-madjid@yahoo.com; Lahna, Kurnia, E-mail: kurnialahna@gmail.com; Desiyana, Lydia Septa, E-mail: lydia-septa@yahoo.com

2016-03-11

An experimental study has been performed to examine the physical characteristics of pharmaceutical products, such as tablet, by employing an emission plasma induced by Nd-YAG laser at a low pressure of Helium gas. The hardness of tablet is one of the parameters that examined during the production process for standard quality of pharmaceutical products. In the Laser-Induced Shock Wave Plasma Spectroscopy (LISPS), the shock wave has a significant role in inducing atomic excitation. It was known that, the speed of the shock wavefront depends on the hardness of the sample, and it correlates with the ionization rate of the ablatedmore » atoms. The hardness of the tablet is examined using the intensity ratio between the ion of Mg (II) 275.2 nm and the neutral of Mg (I) 285.2 nm emission lines detected from the laser-induced plasma. It was observed that the ratio changes with respect to the change in the tablet hardness, namely the ratio is higher for the hard tablet. Besides the ratio measurements, we also measured the depth profile of a tablet by focusing 60 shots of irradiation of laser light at a fixed position on the surface of the tablet. It was found that the depth profile varies differently with the hardness of the tablet. These experiment results show that the technique of LISPS can be applied to examine the quality of pharmaceutical products.« less

On-chip plasmon-induced transparency based on plasmonic coupled nanocavities

PubMed Central

Zhu, Yu; Hu, Xiaoyong; Yang, Hong; Gong, Qihuang

2014-01-01

On-chip plasmon-induced transparency offers the possibility of realization of ultrahigh-speed information processing chips. Unfortunately, little experimental progress has been made to date because it is difficult to obtain on-chip plasmon-induced transparency using only a single meta-molecule in plasmonic circuits. Here, we report a simple and efficient strategy to realize on-chip plasmon-induced transparency in a nanoscale U-shaped plasmonic waveguide side-coupled nanocavity pair. High tunability in the transparency window is achieved by covering the pair with different organic polymer layers. It is possible to realize ultrafast all-optical tunability based on pump light-induced refractive index change of a graphene cover layer. Compared with previous reports, the overall feature size of the plasmonic nanostructure is reduced by more than three orders of magnitude, while ultrahigh tunability of the transparency window is maintained. This work also provides a superior platform for the study of the various physical effects and phenomena of nonlinear optics and quantum optics. PMID:24435059

On-chip plasmon-induced transparency based on plasmonic coupled nanocavities.

PubMed

Zhu, Yu; Hu, Xiaoyong; Yang, Hong; Gong, Qihuang

2014-01-17

On-chip plasmon-induced transparency offers the possibility of realization of ultrahigh-speed information processing chips. Unfortunately, little experimental progress has been made to date because it is difficult to obtain on-chip plasmon-induced transparency using only a single meta-molecule in plasmonic circuits. Here, we report a simple and efficient strategy to realize on-chip plasmon-induced transparency in a nanoscale U-shaped plasmonic waveguide side-coupled nanocavity pair. High tunability in the transparency window is achieved by covering the pair with different organic polymer layers. It is possible to realize ultrafast all-optical tunability based on pump light-induced refractive index change of a graphene cover layer. Compared with previous reports, the overall feature size of the plasmonic nanostructure is reduced by more than three orders of magnitude, while ultrahigh tunability of the transparency window is maintained. This work also provides a superior platform for the study of the various physical effects and phenomena of nonlinear optics and quantum optics.

Therapeutic-Ultrasound-Triggered Shape Memory of a Melamine-Enhanced Poly(vinyl alcohol) Physical Hydrogel.

PubMed

Li, Guo; Yan, Qiang; Xia, Hesheng; Zhao, Yue

2015-06-10

Therapeutic-ultrasound-triggered shape memory was demonstrated for the first time with a melamine-enhanced poly(vinyl alcohol) (PVA) physical hydrogel. The addition of a small amount of melamine (up to 1.5 wt %) in PVA results in a strong hydrogel due to the multiple H-bonding between the two constituents. A temporary shape of the hydrogel can be obtained by deformation of the hydrogel (∼65 wt % water) at room temperature, followed by fixation of the deformation by freezing/thawing the hydrogel under strain, which induces crystallization of PVA. We show that the ultrasound delivered by a commercially available device designed for the patient's pain relief could trigger the shape recovery process as a result of ultrasound-induced local heating in the hydrogel that melts the crystallized PVA cross-linking. This hydrogel is thus interesting for potential applications because it combines many desirable properties, being mechanically strong, biocompatible, and self-healable and displaying the shape memory capability triggered by a physiological stimulus.

Validating a Model for Welding Induced Residual Stress Using High-Energy X-ray Diffraction

DOE PAGES

Mach, J. C.; Budrow, C. J.; Pagan, D. C.; ...

2017-03-15

Integrated computational materials engineering (ICME) provides a pathway to advance performance in structures through the use of physically-based models to better understand how manufacturing processes influence product performance. As one particular challenge, consider that residual stresses induced in fabrication are pervasive and directly impact the life of structures. For ICME to be an effective strategy, it is essential that predictive capability be developed in conjunction with critical experiments. In the present paper, simulation results from a multi-physics model for gas metal arc welding are evaluated through x-ray diffraction using synchrotron radiation. A test component was designed with intent to developmore » significant gradients in residual stress, be representative of real-world engineering application, yet remain tractable for finely spaced strain measurements with positioning equipment available at synchrotron facilities. Finally, the experimental validation lends confidence to model predictions, facilitating the explicit consideration of residual stress distribution in prediction of fatigue life.« less

Geomagnetically induced currents: Science, engineering, and applications readiness

NASA Astrophysics Data System (ADS)

Pulkkinen, A.; Bernabeu, E.; Thomson, A.; Viljanen, A.; Pirjola, R.; Boteler, D.; Eichner, J.; Cilliers, P. J.; Welling, D.; Savani, N. P.; Weigel, R. S.; Love, J. J.; Balch, C.; Ngwira, C. M.; Crowley, G.; Schultz, A.; Kataoka, R.; Anderson, B.; Fugate, D.; Simpson, J. J.; MacAlester, M.

2017-07-01

This paper is the primary deliverable of the very first NASA Living With a Star Institute Working Group, Geomagnetically Induced Currents (GIC) Working Group. The paper provides a broad overview of the current status and future challenges pertaining to the science, engineering, and applications of the GIC problem. Science is understood here as the basic space and Earth sciences research that allows improved understanding and physics-based modeling of the physical processes behind GIC. Engineering, in turn, is understood here as the "impact" aspect of GIC. Applications are understood as the models, tools, and activities that can provide actionable information to entities such as power systems operators for mitigating the effects of GIC and government agencies for managing any potential consequences from GIC impact to critical infrastructure. Applications can be considered the ultimate goal of our GIC work. In assessing the status of the field, we quantify the readiness of various applications in the mitigation context. We use the Applications Readiness Level (ARL) concept to carry out the quantification.

Orthogonal cutting modeling of hybrid CFRP/Ti toward specific cutting energy and induced damage analyses

NASA Astrophysics Data System (ADS)

Xu, Jinyang; El Mansori, Mohamed

2016-10-01

This paper studied the machinability of hybrid CFRP/Ti stack via the numerical approach. To this aim, an original FE model consisting of three fundamental physical constituents, i.e., CFRP phase, interface and Ti phase, was established in the Abaqus Explicit/code to construct the machining behavior of the composite-to-metal alliance. The CFRP phase was modeled as an equivalent homogeneous material (EHM) by considering its anisotropic behavior relative to the fiber orientation (θ) while the Ti alloy phase was assumed to exhibit isotropic and elastic-plastic behavior. The "interface" linking the "CFRP-to-Ti" contact boundary was physically modeled as an intermediate transition region through the concept of cohesive zone (CZ). Different constitutive laws and damage criteria were implemented to simulate the chip separation process of the bi-material system. The key cutting responses including specific cutting energy consumption, induced subsurface damage, and interface delamination were precisely addressed via the comprehensive FE analyses, and several key conclusions were drawn from this study.

Geomagnetically induced currents: Science, engineering, and applications readiness

USGS Publications Warehouse

Pulkkinen, Antti; Bernabeu, E.; Thomson, A.; Viljanen, A.; Pirjola, R.; Boteler, D.; Eichner, J.; Cilliers, P.J.; Welling, D.; Savani, N.P.; Weigel, R.S.; Love, Jeffrey J.; Balch, Christopher; Ngwira, C.M.; Crowley, G.; Schultz, Adam; Kataoka, R.; Anderson, B.; Fugate, D.; Simpson, J.J.; MacAlester, M.

2017-01-01

This paper is the primary deliverable of the very first NASA Living With a Star Institute Working Group, Geomagnetically Induced Currents (GIC) Working Group. The paper provides a broad overview of the current status and future challenges pertaining to the science, engineering, and applications of the GIC problem. Science is understood here as the basic space and Earth sciences research that allows improved understanding and physics-based modeling of the physical processes behind GIC. Engineering, in turn, is understood here as the “impact” aspect of GIC. Applications are understood as the models, tools, and activities that can provide actionable information to entities such as power systems operators for mitigating the effects of GIC and government agencies for managing any potential consequences from GIC impact to critical infrastructure. Applications can be considered the ultimate goal of our GIC work. In assessing the status of the field, we quantify the readiness of various applications in the mitigation context. We use the Applications Readiness Level (ARL) concept to carry out the quantification.

Validating a Model for Welding Induced Residual Stress Using High-Energy X-ray Diffraction

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

Mach, J. C.; Budrow, C. J.; Pagan, D. C.

Integrated computational materials engineering (ICME) provides a pathway to advance performance in structures through the use of physically-based models to better understand how manufacturing processes influence product performance. As one particular challenge, consider that residual stresses induced in fabrication are pervasive and directly impact the life of structures. For ICME to be an effective strategy, it is essential that predictive capability be developed in conjunction with critical experiments. In the present paper, simulation results from a multi-physics model for gas metal arc welding are evaluated through x-ray diffraction using synchrotron radiation. A test component was designed with intent to developmore » significant gradients in residual stress, be representative of real-world engineering application, yet remain tractable for finely spaced strain measurements with positioning equipment available at synchrotron facilities. Finally, the experimental validation lends confidence to model predictions, facilitating the explicit consideration of residual stress distribution in prediction of fatigue life.« less

``Recycling'' Geophysics: Monitoring and Isotopic Analysis of Engineered Biological Systems

NASA Astrophysics Data System (ADS)

Doherty, R.; Singh, K. P.; Ogle, N.; Ntarlagiannis, D.

2010-12-01

The emerging sub discipline of biogeophysics has provoked debate on the mechanisms of microbial processes that may contribute to geophysical signatures. At field scales geophysical signatures are often non unique due to the many parameters (physical, chemical, and biological) that are involved. It may be easier to apply geophysical techniques such as electrodic potential (EP), self potential (SP) and induced polarization (IP) to engineered biological systems where there is a degree of control over the design of the physical and chemical domain. Here we present results of a column experiment that was designed to anaerobically biodegrade dissolved organic matter in landfill leachate. The column utilises a recycled porous media (concrete) to help sequester organic carbon. Electrodic potential, self potential and induced polarisation are used in conjunction with chemical and isotopic techniques to monitor the effectiveness of this approach. Preliminary carbon and oxygen isotopic analysis on concrete from the column in contact with leachate show isotopic enrichment suggesting abiotic precipitation of carbonates.

ECCD-induced tearing mode stabilization in coupled IPS/NIMROD/GENRAY HPC simulations

NASA Astrophysics Data System (ADS)

Jenkins, Thomas; Kruger, S. E.; Held, E. D.; Harvey, R. W.; Elwasif, W. R.

2012-03-01

We summarize ongoing developments toward an integrated, predictive model for determining optimal ECCD-based NTM stabilization strategies in ITER. We demonstrate the capability of the SWIM Project's Integrated Plasma Simulator (IPS) framework to choreograph multiple executions of, and data exchanges between, physics codes modeling various spatiotemporal scales of this coupled RF/MHD problem on several thousand HPC processors. As NIMROD evolves fluid equations to model bulk plasma behavior, self-consistent propagation/deposition of RF power in the ensuing plasma profiles is calculated by GENRAY. Data from both codes is then processed by computational geometry packages to construct the RF-induced quasilinear diffusion tensor; moments of this tensor (entering as additional terms in NIMROD's fluid equations due to the disparity in RF/MHD spatiotemporal scales) influence the dynamics of current, momentum, and energy evolution as well as the MHD closures. Initial results are shown to correctly capture the physics of magnetic island stabilization; we also discuss the development of a numerical plasma control system for active feedback stabilization of tearing modes.

Exercise-Induced Skeletal Muscle Remodeling and Metabolic Adaptation: Redox Signaling and Role of Autophagy

PubMed Central

Giammarioli, Anna Maria; Chiandotto, Sergio; Spoletini, Ilaria

2014-01-01

Abstract Significance: Skeletal muscle is a highly plastic tissue. Exercise evokes signaling pathways that strongly modify myofiber metabolism and physiological and contractile properties of skeletal muscle. Regular physical activity is beneficial for health and is highly recommended for the prevention of several chronic conditions. In this review, we have focused our attention on the pathways that are known to mediate physical training-induced plasticity. Recent Advances: An important role for redox signaling has recently been proposed in exercise-mediated muscle remodeling and peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1α (PGC-1α) activation. Still more currently, autophagy has also been found to be involved in metabolic adaptation to exercise. Critical Issues: Both redox signaling and autophagy are processes with ambivalent effects; they can be detrimental and beneficial, depending on their delicate balance. As such, understanding their role in the chain of events induced by exercise and leading to skeletal muscle remodeling is a very complicated matter. Moreover, the study of the signaling induced by exercise is made even more difficult by the fact that exercise can be performed with several different modalities, with this having different repercussions on adaptation. Future Directions: Unraveling the complexity of the molecular signaling triggered by exercise on skeletal muscle is crucial in order to define the therapeutic potentiality of physical training and to identify new pharmacological compounds that are able to reproduce some beneficial effects of exercise. In evaluating the effect of new “exercise mimetics,” it will also be necessary to take into account the involvement of reactive oxygen species, reactive nitrogen species, and autophagy and their controversial effects. Antioxid. Redox Signal. 21, 154–176. PMID:24450966

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

Trahan, Alexis Chanel

The objectives of this presentation are to introduce the basic physics of neutron production, interactions and detection; identify the processes that generate neutrons; explain the most common neutron mechanism, spontaneous and induced fission and (a,n) reactions; describe the properties of neutron from different sources; recognize advantages of neutron measurements techniques; recognize common neutrons interactions; explain neutron cross section measurements; describe the fundamental of 3He detector function and designs; and differentiate between passive and active assay techniques.

Why geodiversity matters in valuing nature's stage.

PubMed

Hjort, Jan; Gordon, John E; Gray, Murray; Hunter, Malcolm L

2015-06-01

Geodiversity--the variability of Earth's surface materials, forms, and physical processes-is an integral part of nature and crucial for sustaining ecosystems and their services. It provides the substrates, landform mosaics, and dynamic physical processes for habitat development and maintenance. By determining the heterogeneity of the physical environment in conjunction with climate interactions, geodiversity has a crucial influence on biodiversity across a wide range of scales. From a literature review, we identified the diverse values of geodiversity; examined examples of the dependencies of biodiversity on geodiversity at a site-specific scale (for geosites <1 km(2) in area); and evaluated various human-induced threats to geosites and geodiversity. We found that geosites are important to biodiversity because they often support rare or unique biota adapted to distinctive environmental conditions or create a diversity of microenvironments that enhance species richness. Conservation of geodiversity in the face of a range of threats is critical both for effective management of nature's stage and for its own particular values. This requires approaches to nature conservation that integrate climate, biodiversity, and geodiversity at all spatial scales. © 2015 Society for Conservation Biology.

Classical Wave Model of Quantum-Like Processing in Brain

NASA Astrophysics Data System (ADS)

Khrennikov, A.

2011-01-01

We discuss the conjecture on quantum-like (QL) processing of information in the brain. It is not based on the physical quantum brain (e.g., Penrose) - quantum physical carriers of information. In our approach the brain created the QL representation (QLR) of information in Hilbert space. It uses quantum information rules in decision making. The existence of such QLR was (at least preliminary) confirmed by experimental data from cognitive psychology. The violation of the law of total probability in these experiments is an important sign of nonclassicality of data. In so called "constructive wave function approach" such data can be represented by complex amplitudes. We presented 1,2 the QL model of decision making. In this paper we speculate on a possible physical realization of QLR in the brain: a classical wave model producing QLR . It is based on variety of time scales in the brain. Each pair of scales (fine - the background fluctuations of electromagnetic field and rough - the cognitive image scale) induces the QL representation. The background field plays the crucial role in creation of "superstrong QL correlations" in the brain.

DNA strand breaks induced by electrons simulated with Nanodosimetry Monte Carlo Simulation Code: NASIC.

PubMed

Li, Junli; Li, Chunyan; Qiu, Rui; Yan, Congchong; Xie, Wenzhang; Wu, Zhen; Zeng, Zhi; Tung, Chuanjong

2015-09-01

The method of Monte Carlo simulation is a powerful tool to investigate the details of radiation biological damage at the molecular level. In this paper, a Monte Carlo code called NASIC (Nanodosimetry Monte Carlo Simulation Code) was developed. It includes physical module, pre-chemical module, chemical module, geometric module and DNA damage module. The physical module can simulate physical tracks of low-energy electrons in the liquid water event-by-event. More than one set of inelastic cross sections were calculated by applying the dielectric function method of Emfietzoglou's optical-data treatments, with different optical data sets and dispersion models. In the pre-chemical module, the ionised and excited water molecules undergo dissociation processes. In the chemical module, the produced radiolytic chemical species diffuse and react. In the geometric module, an atomic model of 46 chromatin fibres in a spherical nucleus of human lymphocyte was established. In the DNA damage module, the direct damages induced by the energy depositions of the electrons and the indirect damages induced by the radiolytic chemical species were calculated. The parameters should be adjusted to make the simulation results be agreed with the experimental results. In this paper, the influence study of the inelastic cross sections and vibrational excitation reaction on the parameters and the DNA strand break yields were studied. Further work of NASIC is underway. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Understanding Large Wind Farm Impacts on Regional Climate and Vegetation Growth from Observational and Modeling Perspectives

NASA Astrophysics Data System (ADS)

Xia, Geng

In the most recent decade, wind energy has experienced exponential growth worldwide and this rapid increase is expected to continue, particularly over farmlands in the United States. This poses an important question regarding whether the widespread deployment of wind turbines (WTs) will influence surface/near-surface microclimate and vegetation growth. In this dissertation, I investigate the potential wind farm (WF) impacts on regional climate and vegetation growth from both observational and modeling perspectives. High resolution satellite, radiosonde and field observations are used to determine the magnitude and variability of WF-induced changes on surface/near-surface temperatures while the Weather Research and Forecasting (WRF) model is used to simulate these changes in real-world WFs at regional scales and to uncover the physical processes behind the simulated temperature changes. First, the primary physical mechanisms controlling the seasonal and diurnal variations of WF impacts on land surface temperature (LST) are investigated by analyzing both satellite data and field observations. It is found that the turbine-induced turbulent kinetic energy (TKE) relative to the background TKE determines the magnitude and variability of such impacts. In addition, atmospheric stability also matters in determining the sign and strength of the net downward heat transport as well as the magnitude of the background TKE. Second, the WRF's ability in simulating the observed WF impacts on LST is examined by conducting real-world WF experiments driven by realistic initial and boundary conditions. Overall, the WRF model can moderately reproduce the observed spatiotemporal variations of the background LST but has difficulties in reproducing such variations for the turbine-induced LST change signals at pixel levels. However, the model is still able to reproduce the coherent and consistent responses of the observed WF-induced LST changes at regional scales. Third, the spatiotemporal characteristics of the simulated temperature changes as well as the relevant physical processes responsible for such changes are further investigated using the WRF model. It is found that (i) the WF-induced sensible heat flux change is the dominant surface forcing responsible for the simulated temperature changes; (ii) the WF-induced temperature changes are not only restricted at the surface but also can extend vertically to the hub-height level and horizontally spread 60 km in the downwind direction; (iii) the vertical divergence of heat flux from the planetary boundary layer scheme and the resolved temperature advection are the two most likely physical processes behind the simulated temperature changes. Finally, the possible WF impacts on vegetation growth are also investigated using high resolution ( 250m) satellite derived vegetation indices (VI) over two well-studied large WF regions. Results indicate that the WFs have insignificant or no detectable impacts on local vegetation growth. At the pixel level, the VI changes demonstrate a random nature and have no spatial coupling with the WF layout. At the regional level, there is no systematic shift in vegetation greenness between the pre- and post-turbine periods. At interannual and seasonal time scales, there are no confident vegetation changes over wind farm pixels relative to non-wind farm pixels. Most importantly, the majority of the VI changes are within the data uncertainty, suggesting that the WF impacts on vegetation, if any, cannot be separated confidently from the data noise.

Physical bases of the generation of short-term earthquake precursors: A complex model of ionization-induced geophysical processes in the lithosphere-atmosphere-ionosphere-magnetosphere system

NASA Astrophysics Data System (ADS)

Pulinets, S. A.; Ouzounov, D. P.; Karelin, A. V.; Davidenko, D. V.

2015-07-01

This paper describes the current understanding of the interaction between geospheres from a complex set of physical and chemical processes under the influence of ionization. The sources of ionization involve the Earth's natural radioactivity and its intensification before earthquakes in seismically active regions, anthropogenic radioactivity caused by nuclear weapon testing and accidents in nuclear power plants and radioactive waste storage, the impact of galactic and solar cosmic rays, and active geophysical experiments using artificial ionization equipment. This approach treats the environment as an open complex system with dissipation, where inherent processes can be considered in the framework of the synergistic approach. We demonstrate the synergy between the evolution of thermal and electromagnetic anomalies in the Earth's atmosphere, ionosphere, and magnetosphere. This makes it possible to determine the direction of the interaction process, which is especially important in applications related to short-term earthquake prediction. That is why the emphasis in this study is on the processes proceeding the final stage of earthquake preparation; the effects of other ionization sources are used to demonstrate that the model is versatile and broadly applicable in geophysics.

The Physics of Molecular Shocks in Star-Forming Regions

NASA Technical Reports Server (NTRS)

Hollenbach, David; Cuzzi, Jeffrey (Technical Monitor)

1996-01-01

Molecular shocks are produced by the impact of the supersonic infall of gas and dust onto protostars and by the interaction of the supersonic outflow from the protostar with the circumstellar material. Infalling gas creates an accretion shock around the circumstellar disk which emits a unique infrared spectrum and which processes the interstellar dust as it enters the disk. The winds and jets from protostars also impact the disk, the infalling material, and the ambient molecular cloud core creating shocks whose spectrum and morphology diagnose the mass loss processes of the protostar and the orientation and structure of the star forming system. We discuss the physics of these shocks, the model spectra derived from theoretical models, and comparisons with observations of H2O masers, H2 emission, as well as other shocks tracers. We show the strong effect of magnetic fields on molecular shock structure, and elucidate the chemical changes induced by the shock heating and compression.

The use of inverse phase gas chromatography to measure the surface energy of crystalline, amorphous, and recently milled lactose.

PubMed

Newell, H E; Buckton, G; Butler, D A; Thielmann, F; Williams, D R

2001-05-01

To assess differences in surface energy due to processing induced disorder and to understand whether the disorder dominated the surfaces of particles. Inverse gas chromatography was used to compare the surface energies of crystalline, amorphous, and ball milled lactose. The milling process made ca 1% of the lactose amorphous, however the dispersive contribution to surface energy was 31.2, 37.1, and 41.6 mJ m(-2) for crystalline, spray dried and milled lactose, respectively. A physical mixture of crystalline (99%) and amorphous (1%) material had a dispersive surface energy of 31.5 mJ m(-2). Milling had made the surface energy similar to that of the amorphous material in a manner that was very different to a physical mixture of the same amorphous content. The milled material will have similar interfacial interactions to the 100% amorphous material.

Optimal control of laser-induced spin-orbit mediated ultrafast demagnetization

NASA Astrophysics Data System (ADS)

Elliott, P.; Krieger, K.; Dewhurst, J. K.; Sharma, S.; Gross, E. K. U.

2016-01-01

Laser induced ultrafast demagnetization is the process whereby the magnetic moment of a ferromagnetic material is seen to drop significantly on a timescale of 10-100 s of femtoseconds due to the application of a strong laser pulse. If this phenomenon can be harnessed for future technology, it offers the possibility for devices operating at speeds several orders of magnitude faster than at present. A key component to successful transfer of such a process to technology is the controllability of the process, i.e. that it can be tuned in order to overcome the practical and physical limitations imposed on the system. In this paper, we demonstrate that the spin-orbit mediated form of ultrafast demagnetization recently investigated (Krieger et al 2015 J. Chem. Theory Comput. 11 4870) by ab initio time-dependent density functional theory (TDDFT) can be controlled. To do so we use quantum optimal control theory (OCT) to couple our TDDFT simulations to the optimization machinery of OCT. We show that a laser pulse can be found which maximizes the loss of moment within a given time interval while subject to several practical and physical constraints. Furthermore we also include a constraint on the fluence of the laser pulses and find the optimal pulse that combines significant demagnetization with a desire for less powerful pulses. These calculations demonstrate optimal control is possible for spin-orbit mediated ultrafast demagnetization and lays the foundation for future optimizations/simulations which can incorporate even more constraints.

Physical Exercise Modulates L-DOPA-Regulated Molecular Pathways in the MPTP Mouse Model of Parkinson's Disease.

PubMed

Klemann, Cornelius J H M; Xicoy, Helena; Poelmans, Geert; Bloem, Bas R; Martens, Gerard J M; Visser, Jasper E

2018-07-01

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc), resulting in motor and non-motor dysfunction. Physical exercise improves these symptoms in PD patients. To explore the molecular mechanisms underlying the beneficial effects of physical exercise, we exposed 1-methyl-4-phenyl-1,2,3,6-tetrahydropyrimidine (MPTP)-treated mice to a four-week physical exercise regimen, and subsequently explored their motor performance and the transcriptome of multiple PD-linked brain areas. MPTP reduced the number of DA neurons in the SNpc, whereas physical exercise improved beam walking, rotarod performance, and motor behavior in the open field. Further, enrichment analyses of the RNA-sequencing data revealed that in the MPTP-treated mice physical exercise predominantly modulated signaling cascades that are regulated by the top upstream regulators L-DOPA, RICTOR, CREB1, or bicuculline/dalfampridine, associated with movement disorders, mitochondrial dysfunction, and epilepsy-related processes. To elucidate the molecular pathways underlying these cascades, we integrated the proteins encoded by the exercise-induced differentially expressed mRNAs for each of the upstream regulators into a molecular landscape, for multiple key brain areas. Most notable was the opposite effect of physical exercise compared to previously reported effects of L-DOPA on the expression of mRNAs in the SN and the ventromedial striatum that are involved in-among other processes-circadian rhythm and signaling involving DA, neuropeptides, and endocannabinoids. Altogether, our findings suggest that physical exercise can improve motor function in PD and may, at the same time, counteract L-DOPA-mediated molecular mechanisms. Further, we hypothesize that physical exercise has the potential to improve non-motor symptoms of PD, some of which may be the result of (chronic) L-DOPA use.

Direct observation of ultrafast-electron-transfer reactions unravels high effectiveness of reductive DNA damage

PubMed Central

Nguyen, Jenny; Ma, Yuhan; Luo, Ting; Bristow, Robert G.; Jaffray, David A.; Lu, Qing-Bin

2011-01-01

Both water and electron-transfer reactions play important roles in chemistry, physics, biology, and the environment. Oxidative DNA damage is a well-known mechanism, whereas the relative role of reductive DNA damage is unknown. The prehydrated electron (), a novel species of electrons in water, is a fascinating species due to its fundamental importance in chemistry, biology, and the environment. is an ideal agent to observe reductive DNA damage. Here, we report both the first in situ femtosecond time-resolved laser spectroscopy measurements of ultrafast-electron-transfer (UET) reactions of with various scavengers (KNO3, isopropanol, and dimethyl sulfoxide) and the first gel electrophoresis measurements of DNA strand breaks induced by and OH• radicals co-produced by two-UV-photon photolysis of water. We strikingly found that the yield of reductive DNA strand breaks induced by each is twice the yield of oxidative DNA strand breaks induced by each OH• radical. Our results not only unravel the long-standing mystery about the relative role of radicals in inducing DNA damage under ionizing radiation, but also challenge the conventional notion that oxidative damage is the main pathway for DNA damage. The results also show the potential of femtomedicine as a new transdisciplinary frontier and the broad significance of UET reactions of in many processes in chemistry, physics, biology, and the environment. PMID:21730183

A physical/psychological and biological stress combine to enhance endoplasmic reticulum stress

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

Mondal, Tapan Kumar; Emeny, Rebecca T.; Gao, Donghong

The generation of an immune response against infectious and other foreign agents is substantially modified by allostatic load, which is increased with chemical, physical and/or psychological stressors. The physical/psychological stress from cold-restraint (CR) inhibits host defense against Listeria monocytogenes (LM), due to early effects of the catecholamine norepinephrine (NE) from sympathetic nerves on β1-adrenoceptors (β1AR) of immune cells. Although CR activates innate immunity within 2 h, host defenses against bacterial growth are suppressed 2–3 days after infection (Cao and Lawrence 2002). CR enhances inducible nitric oxide synthase (iNOS) expression and NO production. The early innate activation leads to cellular reduction-oxidationmore » (redox) changes of immune cells. Lymphocytes from CR-treated mice express fewer surface thiols. Splenic and hepatic immune cells also have fewer proteins with free thiols after CR and/or LM, and macrophages have less glutathione after the in vivo CR exposure or exposure to NE in vitro. The early induction of CR-induced oxidative stress elevates endoplasmic reticulum (ER) stress, which could interfere with keeping phagocytized LM within the phagosome or re-encapsuling LM by autophagy once they escape from the phagosome. ER stress-related proteins, such as glucose-regulated protein 78 (GRP78), have elevated expression with CR and LM. The results indicate that CR enhances the unfolded protein response (UPR), which interferes with host defenses against LM. Thus, it is postulated that increased stress, as exists with living conditions at low socioeconomic conditions, can lower host defenses against pathogens because of oxidative and ER stress processes. - Highlights: • Cold-restraint (physical/psychological stress) induces early oxidative stress. • The oxidative stress relates to catecholamine signaling beta-adrenoceptors. • Physical/psychological stress combines infection enhancing inflammation. • Endoplasmic reticulum stress interferes with host defenses and autophagy.« less

Physics of beer tapping.

PubMed

Rodríguez-Rodríguez, Javier; Casado-Chacón, Almudena; Fuster, Daniel

2014-11-21

The popular bar prank known in colloquial English as beer tapping consists in hitting the top of a beer bottle with a solid object, usually another bottle, to trigger the foaming over of the former within a few seconds. Despite the trick being known for a long time, to the best of our knowledge, the phenomenon still lacks scientific explanation. Although it seems natural to think that shock-induced cavitation enhances the diffusion of CO2 from the supersaturated bulk liquid into the bubbles by breaking them up, the subtle mechanism by which this happens remains unknown. Here, we show that the overall foaming-over process can be divided into three stages where different physical phenomena take place in different time scales: namely, the bubble-collapse (or cavitation) stage, the diffusion-driven stage, and the buoyancy-driven stage. In the bubble-collapse stage, the impact generates a train of expansion-compression waves in the liquid that leads to the fragmentation of preexisting gas cavities. Upon bubble fragmentation, the sudden increase of the interface-area-to-volume ratio enhances mass transfer significantly, which makes the bubble volume grow by a large factor until CO2 is locally depleted. At that point buoyancy takes over, making the bubble clouds rise and eventually form buoyant vortex rings whose volume grows fast due to the feedback between the buoyancy-induced rising speed and the advection-enhanced CO2 transport from the bulk liquid to the bubble. The physics behind this explosive process sheds insight into the dynamics of geological phenomena such as limnic eruptions.

Physics of Beer Tapping

NASA Astrophysics Data System (ADS)

Rodríguez-Rodríguez, Javier; Casado-Chacón, Almudena; Fuster, Daniel

2014-11-01

The popular bar prank known in colloquial English as beer tapping consists in hitting the top of a beer bottle with a solid object, usually another bottle, to trigger the foaming over of the former within a few seconds. Despite the trick being known for a long time, to the best of our knowledge, the phenomenon still lacks scientific explanation. Although it seems natural to think that shock-induced cavitation enhances the diffusion of CO2 from the supersaturated bulk liquid into the bubbles by breaking them up, the subtle mechanism by which this happens remains unknown. Here, we show that the overall foaming-over process can be divided into three stages where different physical phenomena take place in different time scales: namely, the bubble-collapse (or cavitation) stage, the diffusion-driven stage, and the buoyancy-driven stage. In the bubble-collapse stage, the impact generates a train of expansion-compression waves in the liquid that leads to the fragmentation of preexisting gas cavities. Upon bubble fragmentation, the sudden increase of the interface-area-to-volume ratio enhances mass transfer significantly, which makes the bubble volume grow by a large factor until CO2 is locally depleted. At that point buoyancy takes over, making the bubble clouds rise and eventually form buoyant vortex rings whose volume grows fast due to the feedback between the buoyancy-induced rising speed and the advection-enhanced CO2 transport from the bulk liquid to the bubble. The physics behind this explosive process sheds insight into the dynamics of geological phenomena such as limnic eruptions.

Defect generation in electronic devices under plasma exposure: Plasma-induced damage

NASA Astrophysics Data System (ADS)

Eriguchi, Koji

2017-06-01

The increasing demand for higher performance of ULSI circuits requires aggressive shrinkage of device feature sizes in accordance with Moore’s law. Plasma processing plays an important role in achieving fine patterns with anisotropic features in metal-oxide-semiconductor field-effect transistors (MOSFETs). This article comprehensively addresses the negative aspect of plasma processing — plasma-induced damage (PID). PID naturally not only modifies the surface morphology of materials but also degrades the performance and reliability of MOSFETs as a result of defect generation in the materials. Three key mechanisms of PID, i.e., physical, electrical, and photon-irradiation interactions, are overviewed in terms of modeling, characterization techniques, and experimental evidence reported so far. In addition, some of the emerging topics — control of parameter variability in ULSI circuits caused by PID and recovery of PID — are discussed as future perspectives.

Peripheral Pain Enhances the Effects of Incentive Downshifts

ERIC Educational Resources Information Center

Ortega, Leonardo A.; Daniel, Alan M.; Davis, Jessica B.; Fuchs, Perry N.; Papini, Mauricio R.

2011-01-01

Physical pain (induced by tissue damage) and psychological pain (induced by surprising incentive loss) share a set of common neural substrates, but little is known about their interactions. The present research studied such interactions using the formalin test to induce physical pain and consummatory successive negative contrast (cSNC) to induce…

Influence of Joule heating on current-induced domain wall depinning

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

Moretti, Simone, E-mail: simone.moretti@usal.es; Raposo, Victor; Martinez, Eduardo

2016-06-07

The domain wall depinning from a notch in a Permalloy nanostrip on top of a SiO{sub 2}/Si substrate is studied theoretically under application of static magnetic fields and the injection of short current pulses. The influence of Joule heating on current-induced domain wall depinning is explored self-consistently by coupling the magnetization dynamics in the ferromagnetic strip to the heat transport throughout the system. Our results indicate that Joule heating plays a remarkable role in these processes, resulting in a reduction in the critical depinning field and/or in a temporary destruction of the ferromagnetic order for typically injected current pulses. Inmore » agreement with experimental observations, similar pinning-depinning phase diagrams can be deduced for both current polarities when the Joule heating is taken into account. These observations, which are incompatible with the sole contribution of spin transfer torques, provide a deeper understanding of the physics underlying these processes and establish the real scope of the spin transfer torque. They are also relevant for technological applications based on current-induced domain-wall motion along soft strips.« less

Paradigm shift in the management of milk and egg allergy: baked milk and egg diet.

PubMed

Konstantinou, George N; Kim, Jennifer S

2012-02-01

Heat treatment of several foods, including all types of cooking, has been mainly used to minimize the number of viable microbes, reduce pathogenicity, and destroy the undesirable enzymes, maintaining food quality. In addition, food processing improves sensory, nutritional, and physical properties of the foods, due to food protein denaturation. Heat-induced alterations of food proteins can attenuate allergenicity. In this article, the authors review the important role of thermal processing on milk and egg proteins, which comprise the commonest food allergies in infancy and early childhood. Copyright © 2012 Elsevier Inc. All rights reserved.

Kinetics of the mechanochemical synthesis of alkaline-earth metal amides

NASA Astrophysics Data System (ADS)

Garroni, Sebastiano; Takacs, Laszlo; Leng, Haiyan; Delogu, Francesco

2014-07-01

A phenomenological framework is developed to model the kinetics of the formation of alkaline-earth metal amides by the ball milling induced reaction of their hydrides with gaseous ammonia. It is shown that the exponential character of the kinetic curves is modulated by the increase of the total volume of the powder inside the reactor due to the substantially larger molar volume of the products compared to the reactants. It is claimed that the volume of powder effectively processed during each collision connects the transformation rate to the physical and chemical processes underlying the mechanochemical transformations.

Activity-Induced Synaptic Structural Modifications by an Activator of Integrin Signaling at the Drosophila Neuromuscular Junction.

PubMed

Lee, Joo Yeun; Geng, Junhua; Lee, Juhyun; Wang, Andrew R; Chang, Karen T

2017-03-22

Activity-induced synaptic structural modification is crucial for neural development and synaptic plasticity, but the molecular players involved in this process are not well defined. Here, we report that a protein named Shriveled (Shv) regulates synaptic growth and activity-dependent synaptic remodeling at the Drosophila neuromuscular junction. Depletion of Shv causes synaptic overgrowth and an accumulation of immature boutons. We find that Shv physically and genetically interacts with βPS integrin. Furthermore, Shv is secreted during intense, but not mild, neuronal activity to acutely activate integrin signaling, induce synaptic bouton enlargement, and increase postsynaptic glutamate receptor abundance. Consequently, loss of Shv prevents activity-induced synapse maturation and abolishes post-tetanic potentiation, a form of synaptic plasticity. Our data identify Shv as a novel trans-synaptic signal secreted upon intense neuronal activity to promote synapse remodeling through integrin receptor signaling. SIGNIFICANCE STATEMENT The ability of neurons to rapidly modify synaptic structure in response to neuronal activity, a process called activity-induced structural remodeling, is crucial for neuronal development and complex brain functions. The molecular players that are important for this fundamental biological process are not well understood. Here we show that the Shriveled (Shv) protein is required during development to maintain normal synaptic growth. We further demonstrate that Shv is selectively released during intense neuronal activity, but not mild neuronal activity, to acutely activate integrin signaling and trigger structural modifications at the Drosophila neuromuscular junction. This work identifies Shv as a key modulator of activity-induced structural remodeling and suggests that neurons use distinct molecular cues to differentially modulate synaptic growth and remodeling to meet synaptic demand. Copyright © 2017 the authors 0270-6474/17/373246-18$15.00/0.

On the functional order of binocular rivalry and blind spot filling-in.

PubMed

Qian, Cheng S; Brascamp, Jan W; Liu, Taosheng

2017-07-01

Binocular rivalry is an important phenomenon for understanding the mechanisms of visual awareness. Here we assessed the functional locus of binocular rivalry relative to blind spot filling-in, which is thought to transpire in V1, thus providing a reference point for assessing the locus of rivalry. We conducted two experiments to explore the functional order of binocular rivalry and blind spot filling-in. Experiment 1 examined if the information filled-in at the blind spot can engage in rivalry with a physical stimulus at the corresponding location in the fellow eye. Participants' perceptual reports showed no difference between this condition and a condition where filling-in was precluded by presenting the same stimuli away from the blind spot, suggesting that the rivalry process is not influenced by any filling-in that might occur. In Experiment 2, we presented the fellow eye's stimulus directly in rivalry with the 'inducer' stimulus that surrounds the blind spot, and compared it with two control conditions away from the blind spot: one involving a ring physically identical to the inducer, and one involving a disc that resembled the filled-in percept. Perceptual reports in the blind spot condition resembled those in the 'ring' condition, more than those in the latter, 'disc' condition, indicating that a perceptually suppressed inducer does not engender filling-in. Thus, our behavioral data suggest binocular rivalry functionally precedes blind spot filling-in. We conjecture that the neural substrate of binocular rivalry suppression includes processing stages at or before V1. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cold atmospheric-pressure plasma induces DNA-protein crosslinks through protein oxidation.

PubMed

Guo, Li; Zhao, Yiming; Liu, Dingxin; Liu, Zhichao; Chen, Chen; Xu, Ruobing; Tian, Miao; Wang, Xiaohua; Chen, Hailan; Kong, Michael G

2018-05-03

Reactive oxygen and nitrogen species (ROS and RNS) generated by cold atmospheric-pressure plasma could damage genomic DNA, although the precise type of these DNA damage induced by plasma are poorly characterized. Understanding plasma-induced DNA damage will help to elucidate the biological effect of plasma and guide the application of plasma in ROS-based therapy. In this study, it was shown that ROS and RNS generated by physical plasma could efficiently induce DNA-protein crosslinks (DPCs) in bacteria, yeast, and human cells. An in vitro assay showed that plasma treatment resulted in the formation of covalent DPCs by activating proteins to crosslink with DNA. Mass spectrometry and hydroperoxide analysis detected oxidation products induced by plasma. DPC formation were alleviated by singlet oxygen scavenger, demonstrating the importance of singlet oxygen in this process. These results suggested the roles of DPC formation in DNA damage induced by plasma, which could improve the understanding of the biological effect of plasma and help to develop a new strategy in plasma-based therapy including infection and cancer therapy.

Photoassisted physical vapor epitaxial growth of semiconductors: a review of light-induced modifications to growth processes

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

Alberi, Kirstin; Scarpulla, Michael A.

Herein, we review the remarkable range of modifications to materials properties associated with photoexcitation of the growth surface during physical vapor epitaxy of semiconductors. We concentrate on mechanisms producing measureable, utilizable changes in crystalline perfection, phase, composition, doping, and defect distribution. We outline the relevant physics of different mechanisms, concentrating on those yielding effects orthogonal to the primary growth variables of temperature and atomic or molecular fluxes and document the phenomenological effects reported. Based on experimental observations from a range of semiconductor systems and growth conditions, the primary effects include enhanced anion desorption, molecular dissociation, increased doping efficiency, modification tomore » defect populations and improvements to the crystalline quality of epilayers grown at low temperatures. Future research directions and technological applications are also discussed.« less

Photoassisted physical vapor epitaxial growth of semiconductors: a review of light-induced modifications to growth processes

DOE PAGES

Alberi, Kirstin; Scarpulla, Michael A.

2017-11-22

Herein, we review the remarkable range of modifications to materials properties associated with photoexcitation of the growth surface during physical vapor epitaxy of semiconductors. We concentrate on mechanisms producing measureable, utilizable changes in crystalline perfection, phase, composition, doping, and defect distribution. We outline the relevant physics of different mechanisms, concentrating on those yielding effects orthogonal to the primary growth variables of temperature and atomic or molecular fluxes and document the phenomenological effects reported. Based on experimental observations from a range of semiconductor systems and growth conditions, the primary effects include enhanced anion desorption, molecular dissociation, increased doping efficiency, modification tomore » defect populations and improvements to the crystalline quality of epilayers grown at low temperatures. Future research directions and technological applications are also discussed.« less

Simulation studies of GST phase change alloys

NASA Astrophysics Data System (ADS)

Martyna, Glenn

2008-03-01

In order to help drive post-Moore's Law technology development, switching processes involving novel materials, in particular, GeSbTe (GST) alloys are being investigated for use in memory and eFuse applications. An anneal/quench thermal process crystallizes/amorphosizes a GST alloy which then has a low/high resistance and thereby forms a readable/writeable bit; for example, a ``one'' might be the low resistance, conducting crystalline state and a ``zero'' might be the high resistance, glassy state. There are many open questions about the precise nature of the structural transitions and the coupling to electronic structure changes. Computational and experimental studies of the effect of pressure on the GST materials were initiated in order to probe the physics behind the thermal switching process. A new pathway to reversible phase change involving pressure-induced structural metal insulator transitions was discovered. In a binary GS system, a room-temperature, direct, pressure-induced transformation from the high resistance amorphous phase to the low resistance crystalline phase was observed experimentally while the reverse process under tensile load was demonstrated via ab initio MD simulations performed on IBM's Blue Gene/L enabled by massively parallel software. Pressure induced transformations of the ternary material GST-225 (Ge2Sb2Te5) were, also, examined In the talk, the behavior of the two systems will be compared and insight into the nature of the phase change given.

From physical inactivity to immobilization: Dissecting the role of oxidative stress in skeletal muscle insulin resistance and atrophy.

PubMed

Pierre, Nicolas; Appriou, Zephyra; Gratas-Delamarche, Arlette; Derbré, Frédéric

2016-09-01

In the literature, the terms physical inactivity and immobilization are largely used as synonyms. The present review emphasizes the need to establish a clear distinction between these two situations. Physical inactivity is a behavior characterized by a lack of physical activity, whereas immobilization is a deprivation of movement for medical purpose. In agreement with these definitions, appropriate models exist to study either physical inactivity or immobilization, leading thereby to distinct conclusions. In this review, we examine the involvement of oxidative stress in skeletal muscle insulin resistance and atrophy induced by, respectively, physical inactivity and immobilization. A large body of evidence demonstrates that immobilization-induced atrophy depends on the chronic overproduction of reactive oxygen and nitrogen species (RONS). On the other hand, the involvement of RONS in physical inactivity-induced insulin resistance has not been investigated. This observation outlines the need to elucidate the mechanism by which physical inactivity promotes insulin resistance. Copyright © 2015 Elsevier Inc. All rights reserved.

PREFACE: Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications

NASA Astrophysics Data System (ADS)

Wolf, Andreas; Lammich, Lutz; Schmelcher, Peter

2005-01-01

Dissociative recombination between electrons and molecular ions is an elementary reaction in electron-induced chemistry attracting strong attention across discipline boundaries, from fundamental questions of intramolecular dynamics to astrophysics, plasma science, as well as atmospheric and planetary physics. The process is explored on the level of atomic quantum dynamics both experimentally and theoretically, employing cold collisions at temperatures down to 10 Kelvin involving small molecules or also very large systems ranging up to biomolecules. Dissociative recombination (DR) and related processes, such as dissociative excitation, collisional cooling of vibrations and rotations, photodissociation via high-lying electronic states, resonant electron attachment, and electron-induced processes in large molecules and clusters, are studied by a variety of experimental methods, including stored and trapped molecular ions, plasma techniques such as stationary and flowing afterglow, and laser spectroscopic diagnostic of molecular excitations. The Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications (DR2004) was organized by the Research Group on Atomic and Molecular Physics with Stored Ions at the Max-Planck Institute for Nuclear Physics in Heidelberg, Germany, and held near Heidelberg in the town of Mosbach in July 2004. It was attended by about 90 scientists working in atomic and molecular physics, astrophysics, plasma- and biophysics. International Conferences on Dissociative Recombination and related processes were held before at Lake Louise, Alberta, Canada (1988), Saint Jacut, Brittany, France (1992), Ein Gedi, Israel (1995), Nässlingen, Stockholm Archipelago, Sweden (1999), and last within a symposium at the American Chemical Society meeting in Chicago, USA (2001). The presentations of this conference document a strong development of theoretical ideas towards the understanding of DR in particular in polyatomic systems. Strong attention was given to the elementary triatomic benchmark system H3+, characterized by ambitious, complementary experimental projects. Interaction of experiment and theory improves in particular the understanding of non-adiabatic molecular interactions involving electronic continuum states. New experimental techniques focus on a detailed control of the internal molecular excitation on the level of single quantum states, which gives increasing importance to laser interactions and ion storage at cryogenic temperatures. Apart from its place in the series of "DR conferences", this meeting is also the final assembly of the EU Research Training Network "Electron Transfer Reactions" (ETR) which in the period from 2000 to 2004 helped to establish many invaluable links between 15 experimental and theoretical institutes active in the field of DR and related processes. We express our gratitude to the EU for the support through the Research Training Network Programme, which has made possible the attendance of many students and young researchers. Furthermore, generous financial support for this conference was provided by the Max-Planck Institute for Nuclear Physics in Heidelberg. The efficient support of the conference center "Alte Mälzerei", operated by the city of Mosbach, is gratefully acknowledged. Finally we warmly thank the staff and the students of the Max-Planck Institute for Nuclear Physics for the dedicated help during the conference.

Production induced boiling and cold water entry in the Cerro Prieto geothermal reservoir indicated by chemical and physical measurements

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

Grant, M.A.; Truesdell, A.H.; Manon, A.

1981-01-01

Chemical and physical data suggest that the relatively shallow western part of the Cerro Prieto reservoir is bounded below by low permeability rocks, and above and at the sides by an interface with cooler water. There is no continuous permeability barrier around or immediately above the reservoir. Permeability within the reservoir is dominantly intergranular. Mixture with cooler water rather than boiling is the dominant cooling process in the natural state, and production causes displacement of hot water by cooler water, not by vapor. Local boiling occurs near most wells in response to pressure decreases, but no general vapor zone hasmore » formed.« less

Penguin Decays of B Mesons

NASA Astrophysics Data System (ADS)

Lingel, Karen; Skwarnicki, Tomasz; Smith, James G.

Penguin, or loop, decays of B mesons induce effective flavor-changing neutral currents, which are forbidden at tree level in the standard model. These decays give special insight into the CKM matrix and are sensitive to non-standard-model effects. In this review, we give a historical and theoretical introduction to penguins and a description of the various types of penguin processes: electromagnetic, electroweak, and gluonic. We review the experimental searches for penguin decays, including the measurements of the electromagnetic penguins b -> sgamma and B -> K*gamma and gluonic penguins B -> Kpi, B+ -> omegaK+ and B -> eta'K, and their implications for the standard model and new physics. We conclude by exploring the future prospects for penguin physics.

Effect of damping on the laser induced ultrafast switching in rare earth-transition metal alloys

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

Oniciuc, Eugen; Stoleriu, Laurentiu; Cimpoesu, Dorin

2014-06-02

In this paper, we present simulations of thermally induced magnetic switching in ferrimagnetic systems performed with a Landau-Lifshitz-Bloch (LLB) equation for damping constant in a wide range of values. We have systematically studied the GdFeCo ferrimagnet with various concentrations of Gd and compared for some values of parameters the LLB results with atomistic simulations. The agreement is remarkably good, which shows that the dynamics described by the ferrimagnetic LLB is a reasonable approximation of this complex physical phenomenon. As an important element, we show that the LLB is able to also describe the intermediate formation of a ferromagnetic state whichmore » seems to be essential to understand laser induced ultrafast switching. The study reveals the fundamental role of damping during the switching process.« less

Stem mortality in surface fires: Part II, experimental methods for characterizing the thermal response of tree stems to heating by fires

Treesearch

D. M. Jimenez; B. W. Butler; J. Reardon

2003-01-01

Current methods for predicting fire-induced plant mortality in shrubs and trees are largely empirical. These methods are not readily linked to duff burning, soil heating, and surface fire behavior models. In response to the need for a physics-based model of this process, a detailed model for predicting the temperature distribution through a tree stem as a function of...

Simulation of plasma loading of high-pressure RF cavities

NASA Astrophysics Data System (ADS)

Yu, K.; Samulyak, R.; Yonehara, K.; Freemire, B.

2018-01-01

Muon beam-induced plasma loading of radio-frequency (RF) cavities filled with high pressure hydrogen gas with 1% dry air dopant has been studied via numerical simulations. The electromagnetic code SPACE, that resolves relevant atomic physics processes, including ionization by the muon beam, electron attachment to dopant molecules, and electron-ion and ion-ion recombination, has been used. Simulations studies have been performed in the range of parameters typical for practical muon cooling channels.

Refractive index change mechanisms in different glasses induced by femtosecond laser irradiation

NASA Astrophysics Data System (ADS)

Fuerbach, A.; Gross, S.; Little, D.; Arriola, A.; Ams, M.; Dekker, P.; Withford, M.

2016-07-01

Tightly focused femtosecond laser pulses can be used to alter the refractive index of virtually all optical glasses. As the laser-induced modification is spatially limited to the focal volume of the writing beam, this technique enables the fabrication of fully three-dimensional photonic structures and devices that are automatically embedded within the host material. While it is well understood that the laser-material interaction process is initiated by nonlinear, typically multiphoton absorption, the actual mechanism that results in an increase or sometimes decrease of the refractive index of the glass strongly depends on the composition of the material and the process parameters and is still subject to scientific studies. In this paper, we present an overview of our recent work aimed at uncovering the physical and chemical processes that contribute to the observed material modification. Raman microscopy and electron microprobe analysis was used to study the induced modifications that occur within the glass matrix and the influence of atomic species migration forced by the femtosecond laser writing beam. In particular, we concentrate on borosilicate, heavy metal fluoride and phosphate glasses. We believe that our results represent an important step towards the development of engineered glass types that are ideally suited for the fabrication of photonic devices via the femtosecond laser direct write technique.

HAARP-based Investigations of Lightning-induced Nonlinearities within the D-Region Ionosphere

NASA Astrophysics Data System (ADS)

Moore, R. C.

2015-12-01

It is well-documented that energetic lightning can produce fantastical events with the lower ionosphere. Although the High-frequency Active Auroral Research Program (HAARP) transmitter is not as powerful as lightning, it can be used to investigate the nonlinear interactions that occur within the lower ionosphere, many of which also occur during lightning-induced ionospheric events. This paper presents the best experimental results obtained during D-region modification experiments performed by the University of Florida at the HAARP observatory between 2007 and 2014, including ELF/VLF wave generation experiments, wave-wave mixing experiments, and cross-modulation experiments. We emphasize the physical processes important for lightning-ionosphere interactions that can be directly investigated using HAARP.

Dissipative rogue waves induced by soliton explosions in an ultrafast fiber laser.

PubMed

Liu, Meng; Luo, Ai-Ping; Xu, Wen-Cheng; Luo, Zhi-Chao

2016-09-01

We reported on the observation of dissipative rogue waves (DRWs) induced by soliton explosions in an ultrafast fiber laser. It was found that the soliton explosions could be obtained in the fiber laser at a critical pump power level. During the process of the soliton explosion, the high-amplitude waves that fulfill the rogue wave criteria could be detected. The appearance of the DRWs was identified by characterizing the intensity statistics of the time-stretched soliton profile based on the dispersive Fourier-transform method. Our findings provide the first experimental demonstration that the DRWs could be observed in the soliton explosion regime and further enhance the understanding of the physical mechanism of optical RW generation.

Highly periodic laser-induced nanostructures on thin Ti and Cu foils for potential application in laser ion acceleration

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

Das, Susanta Kumar, E-mail: skdasfpy@kiit.ac.in; Andreev, Alexander; Braenzel, Julia

2016-03-21

The feasibility of femtosecond laser-induced periodic nanostructures on thin Ti and Cu foils (thickness down to 1 μm) is demonstrated. At pulse durations of 120 fs and a wavelength of 400 nm, periods of 61 nm to 320 nm were obtained. Particle-in-cell simulations of laser ion acceleration processes with such nanostructured targets indicate their potential for high energy particle physics applications. In particular, a measurable enhancement of the proton cut-off energy and a significant enhancement of the number of accelerated particles compared to non- or weakly structured targets of same thickness and material are expected.

Indirect handle on the down-quark Yukawa coupling.

PubMed

Goertz, Florian

2014-12-31

To measure the Yukawa couplings of the up and down quarks, Yu,d, seems to be far beyond the capabilities of current and (near) future experiments in particle physics. By performing a general analysis of the potential misalignment between quark masses and Yukawa couplings, we derive predictions for the magnitude of induced flavor-changing neutral currents (FCNCs), depending on the shift in the physical Yukawa coupling of first-generation quarks. We find that a change of more than 50% in Yd would generically result in ds transitions in conflict with kaon physics. This could already be seen as evidence for a nonvanishing direct coupling of the down quark to the newly discovered Higgs boson. The nonobservation of certain--already well-constrained--processes is thus turned into a powerful indirect measure of otherwise basically unaccessible physical parameters of the effective standard model. Similarly, improvements in limits on FCNCs in the up-type quark sector can lead to valuable information on Yu.

Radioisotope tracer approach for understanding the impacts of global change-induced pedoturbation on soil C dynamics

NASA Astrophysics Data System (ADS)

Gonzalez-Meler, M. A.; Sturchio, N. C.; Sanchez-de Leon, Y.; Blanc-Betes, E.; Taneva, L.; Poghosyan, A.; Norby, R. J.; Filley, T. R.; Guilderson, T. P.; Welker, J. M.

2010-12-01

Biogeochemical carbon-cycle feedbacks to climate are apparent but uncertain, primarily because of gaps in mechanistic understanding on the ecosystem processes that drive carbon cycling and storage in terrestrial ecosystems, particularly in soils. Recent findings are increasingly recognizing the interaction between soil biota and the soil physical environment. Soil carbon turnover is partly determined by burial of organic matter and its physical and chemical protection. These factors are potentially affected by changes in climate (freezing-thawing or wet-drying cycles) or ecosystem structure including biological invasions. A major impediment to understanding dynamics of soil C in terrestrial systems is our inability to measure soil physical processes such as soil mixing rates or turnover of soil structures, including aggregates. Here we present a multiple radioisotope tracer approach (naturally occurring and man-made) to measure soil mixing rates in response to global change. We will present evidence of soil mixing rate changes in a temperate forest exposed to increased levels of atmospheric CO2 and in a tundra ecosystem exposed to increased thermal insulation. In both cases, radioisotope tracers proved to be an effective way to measure effects of global change on pedoturbation. Results also provided insights into the specific mechanisms involved in the responses. Elevated CO2 resulted in deeper soil mixing cells (increased by about 5cm on average) when compared to control soils as a consequence of changes in biota (increased root growth, higher earthworm density). In the tundra, soil warming induced higher rates of cryoturbation, resulting in what appears to be a net uplift of organic matter to the surface thereby exposing deeper C to decomposers. In both cases, global change factors affected the vertical distribution of C and changed the amount of bulk soil actively involved in soil processes. As a consequence, comparisons of C budgets to a given soil depth in response to global change factors may be misleading if they do not account for the depth change in the soil mixing cells.

Supercomputations and big-data analysis in strong-field ultrafast optical physics: filamentation of high-peak-power ultrashort laser pulses

NASA Astrophysics Data System (ADS)

Voronin, A. A.; Panchenko, V. Ya; Zheltikov, A. M.

2016-06-01

High-intensity ultrashort laser pulses propagating in gas media or in condensed matter undergo complex nonlinear spatiotemporal evolution where temporal transformations of optical field waveforms are strongly coupled to an intricate beam dynamics and ultrafast field-induced ionization processes. At the level of laser peak powers orders of magnitude above the critical power of self-focusing, the beam exhibits modulation instabilities, producing random field hot spots and breaking up into multiple noise-seeded filaments. This problem is described by a (3  +  1)-dimensional nonlinear field evolution equation, which needs to be solved jointly with the equation for ultrafast ionization of a medium. Analysis of this problem, which is equivalent to solving a billion-dimensional evolution problem, is only possible by means of supercomputer simulations augmented with coordinated big-data processing of large volumes of information acquired through theory-guiding experiments and supercomputations. Here, we review the main challenges of supercomputations and big-data processing encountered in strong-field ultrafast optical physics and discuss strategies to confront these challenges.

RELATIVISTIC MHD SIMULATIONS OF COLLISION-INDUCED MAGNETIC DISSIPATION IN POYNTING-FLUX-DOMINATED JETS/OUTFLOWS

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

Deng, Wei; Zhang, Bing; Li, Hui

We perform 3D relativistic ideal magnetohydrodynamics (MHD) simulations to study the collisions between high-σ (Poynting-flux-dominated (PFD)) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable PFD jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvénic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in themore » relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. Our results give support to the proposed astrophysical models that invoke significant magnetic energy dissipation in PFD jets, such as the internal collision-induced magnetic reconnection and turbulence model for gamma-ray bursts, and reconnection triggered mini jets model for active galactic nuclei. The simulation movies are shown in http://www.physics.unlv.edu/∼deng/simulation1.html.« less

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

Jimbert, P.; Fernandez, J. I.; Eguia, I.

It is well known that one of the main advantages of the high speed forming (HSF) processes is the improvement in the forming limits of the used materials.Using the Electromagnetic Forming (EMF) technology two materials have been tested with different mechanical and physical properties: the AA5754 aluminium and the AZ31B magnesium alloys.The EMF process principle can be described as follows: A significant amount of electrical energy is stored in a bank of capacitors which are suddenly discharged releasing all the stored energy. This electric discharge runs through a coil which generates an intense transient magnetic field. At the same timemore » transient Eddy currents are induced in the electrically conductive part placed some millimetres far from the coil. Another intense magnetic field is generated due to those Eddy currents but on the opposite direction as the one generated by the coil. A big magnetic repulsion force is created between the part and the coil. This magnetic repulsion between both fields is used to launch the blank with no physical contact and obtain the desired deformation on it.The Forming Limit Diagrams (FLD) obtained in the EMF experiments were them compared to the ones obtained with the 'Nakazima' method at conventional deformation speed for both alloys. In parallel to these physical experiments, some simulations were carried out. But trying to simulate this process by FEM is a though work. There are several physics and many factors to take into account in a few microseconds deformation process. And all these factors are tightly related with each other, that is why to this date there is no commercial software able to simulate the EMF process accurately.From LABEIN-Tecnalia we are working with to different softwares to simulate the whole process: Maxwell 3D for the electromagnetic part and PAM-STAMP2G for the mechanical part of the problem.« less

Valuing physically and financially-induced flexibility in large-scale water resources systems

NASA Astrophysics Data System (ADS)

Tilmant, Amaury; Pina, Jasson; Côté, Pascal

2017-04-01

In a world characterized by rapid changes in terms of water demands and supplies, there is a growing and persistent need for institutional reforms that promote cross-sectoral, adaptive management processes and policies. Yet, in many regions throughout the world, the continued expansion of supply-side infrastructure is still perceived as the way to go despite the rising financial, social and environmental costs. This trend is further compounded by the risks posed by climate change; reservoir storage, for example, is still perceived as a key element of climate change adaptation strategies in many countries. There is a growing concern that such strategies may result in a rigidity trap whereby the physical and institutional infrastructure become inflexible and unable to adapt to changes because they are mutually reinforcing each other. However, several authors have recently advocated for adaptive, flexible, management techniques involving a more diversified portfolio of measures whose management is regularly updated as new information about supplies and demands becomes available. Despite being conceptually attractive, such a management approach presents several challenges to policy makers. One of them is the sheer amount of information that must be processed each time a management decision must be taken. To address this issue, we propose an optimization framework that can be used to determine the optimal management of a large portfolio of physical and financial assets using various hydro-climatic information. This optimization framework is illustrated with the management of a power system in Quebec involving various power stations, reservoirs, power and energy contracts as well as hydrologic and climatic data. The results can be used to assess the economic value of the flexibility induced by either the physical assets (power stations and reservoirs) or by the financial ones (contracts), an information we believe is important to highlight the benefits of adaptive management techniques.

Peripheral-specific y2 receptor knockdown protects mice from high-fat diet-induced obesity.

PubMed

Shi, Yan-Chuan; Lin, Shu; Castillo, Lesley; Aljanova, Aygul; Enriquez, Ronaldo F; Nguyen, Amy D; Baldock, Paul A; Zhang, Lei; Bijker, Martijn S; Macia, Laurence; Yulyaningsih, Ernie; Zhang, Hui; Lau, Jackie; Sainsbury, Amanda; Herzog, Herbert

2011-11-01

Y2 receptors, particularly those in the brain, have been implicated in neuropeptide Y (NPY)-mediated effects on energy homeostasis and bone mass. Recent evidence also indicates a role for Y2 receptors in peripheral tissues in this process by promoting adipose tissue accretion; however their effects on energy balance remain unclear. Here, we show that adult-onset conditional knockdown of Y2 receptors predominantly in peripheral tissues results in protection against diet-induced obesity accompanied by significantly reduced weight gain, marked reduction in adiposity and improvements in glucose tolerance without any adverse effect on lean mass or bone. These changes occur in association with significant increases in energy expenditure, respiratory exchange ratio, and physical activity and despite concurrent hyperphagia. On a chow diet, knockdown of peripheral Y2 receptors results in increased respiratory exchange ratio and physical activity with no effect on lean or bone mass, but decreases energy expenditure without effecting body weight or food intake. These results suggest that peripheral Y2 receptor signaling is critical in the regulation of oxidative fuel selection and physical activity and protects against the diet-induced obesity. The lack of effects on bone mass seen in this model further indicates that bone mass is primarily controlled by non-peripheral Y2 receptors. This study provides evidence that novel drugs that target peripheral rather than central Y2 receptors could provide benefits for the treatment of obesity and glucose intolerance without adverse effects on lean and bone mass, with the additional benefit of avoiding side effects often associated with pharmaceuticals that act on the central nervous system.

Preventive fraction of physical fitness on risk factors in cardiac patients: Retrospective epidemiological study.

PubMed

Caru, Maxime; Kern, Laurence; Bousquet, Marc; Curnier, Daniel

2018-04-26

To quantify the preventive fraction of physical fitness on the risk factors in patients with cardiovascular diseases (CVDs). A total of 249 subjects (205 men and 44 women) suffering from CVD were categorized into four groups, according to their percentage of physical fitness. We calculated the odds ratio to obtain the preventive fraction in order to evaluate the impact of the physical fitness level on the risk factors ( i.e ., abdominal obesity, depression, diabetes, dyslipidemia, hypertension, obesity, overweight and smoking). It is observed that a normal physical fitness level is sufficient to induce a preventive action on abdominal obesity (38%), diabetes (12%), hypertension (33%), obesity (12%) and overweight (11%). Also, the preventive fraction increases with the level of physical fitness, in particular for hypertension (36%) and overweight (16%). A high physical fitness level does not necessarily induce a preventive action in most risk factors, excluding depression. This is the first study which demonstrates that reaching a normal physical fitness level is enough to induce a protection for some risk factors, despite having a CVD.

Preventive fraction of physical fitness on risk factors in cardiac patients: Retrospective epidemiological study

PubMed Central

Caru, Maxime; Kern, Laurence; Bousquet, Marc; Curnier, Daniel

2018-01-01

AIM To quantify the preventive fraction of physical fitness on the risk factors in patients with cardiovascular diseases (CVDs). METHODS A total of 249 subjects (205 men and 44 women) suffering from CVD were categorized into four groups, according to their percentage of physical fitness. We calculated the odds ratio to obtain the preventive fraction in order to evaluate the impact of the physical fitness level on the risk factors (i.e., abdominal obesity, depression, diabetes, dyslipidemia, hypertension, obesity, overweight and smoking). RESULTS It is observed that a normal physical fitness level is sufficient to induce a preventive action on abdominal obesity (38%), diabetes (12%), hypertension (33%), obesity (12%) and overweight (11%). Also, the preventive fraction increases with the level of physical fitness, in particular for hypertension (36%) and overweight (16%). A high physical fitness level does not necessarily induce a preventive action in most risk factors, excluding depression. CONCLUSION This is the first study which demonstrates that reaching a normal physical fitness level is enough to induce a protection for some risk factors, despite having a CVD. PMID:29707165

An evaluation method of the profile of plasma-induced defects based on capacitance-voltage measurement

NASA Astrophysics Data System (ADS)

Okada, Yukimasa; Ono, Kouichi; Eriguchi, Koji

2017-06-01

Aggressive shrinkage and geometrical transition to three-dimensional structures in metal-oxide-semiconductor field-effect transistors (MOSFETs) lead to potentially serious problems regarding plasma processing such as plasma-induced physical damage (PPD). For the precise control of material processing and future device designs, it is extremely important to clarify the depth and energy profiles of PPD. Conventional methods to estimate the PPD profile (e.g., wet etching) are time-consuming. In this study, we propose an advanced method using a simple capacitance-voltage (C-V) measurement. The method first assumes the depth and energy profiles of defects in Si substrates, and then optimizes the C-V curves. We applied this methodology to evaluate the defect generation in (100), (111), and (110) Si substrates. No orientation dependence was found regarding the surface-oxide layers, whereas a large number of defects was assigned in the case of (110). The damaged layer thickness and areal density were estimated. This method provides the highly sensitive PPD prediction indispensable for designing future low-damage plasma processes.

Simulation of thermally induced processes of diffusion and phase formation in layered binary metallic systems

NASA Astrophysics Data System (ADS)

Rusakov, V. S.; Sukhorukov, I. A.; Zhankadamova, A. M.; Kadyrzhanov, K. K.

2010-05-01

Results of the simulation of thermally induced processes of diffusion and phase formation in model and experimentally investigated layered binary metallic systems are presented. The physical model is based on the Darken phenomenological theory and on the mechanism of interdiffusion of components along the continuous diffusion channels of phases in the two-phase regions of the system. The simulation of processes in the model systems showed that the thermally stabilized concentration profiles in two-layer binary metallic systems are virtually independent of the partial diffusion coefficients; for the systems with the average concentration of components that is the same over the sample depth, the time of the thermal stabilization of the structural and phase state inhomogeneous over the depth grows according to a power law with increasing thickness of the system in such a manner that the thicknesses of the surface layers grow, while the thickness of the intermediate layer approaches a constant value. The results of the simulation of the processes of diffusion and phase formation in experimentally investigated layered binary systems Fe-Ti and Cu-Be upon sequential isothermal and isochronous annealings agree well with the experimental data.

Mass Dependency of Isotope Fractionation of Gases Under Thermal Gradient and Its Possible Implications for Planetary Atmosphere Escaping Process

NASA Technical Reports Server (NTRS)

Sun, Tao; Niles, Paul; Bao, Huiming; Socki, Richard

2014-01-01

Physical processes that unmix elements/isotopes of gas molecules involve phase changes, diffusion (chemical or thermal), effusion and gravitational settling. Some of those play significant roles for the evolution of chemical and isotopic compositions of gases in planetary bodies which lead to better understanding of surface paleoclimatic conditions, e.g. gas bubbles in Antarctic ice, and planetary evolution, e.g. the solar-wind erosion induced gas escaping from exosphere on terrestrial planets.. A mass dependent relationship is always expected for the kinetic isotope fractionations during these simple physical processes, according to the kinetic theory of gases by Chapman, Enskog and others [3-5]. For O-bearing (O16, -O17, -O18) molecules the alpha O-17/ alpha O-18 is expected at 0.5 to 0.515, and for S-bearing (S32,-S33. -S34, -S36) molecules, the alpha S-33/ alpha S-34 is expected at 0.5 to 0.508, where alpha is the isotope fractionation factor associated with unmixing processes. Thus, one isotope pair is generally proxied to yield all the information for the physical history of the gases. However, we recently] reported the violation of mass law for isotope fractionation among isotope pairs of multiple isotope system during gas diffusion or convection under thermal gradient (Thermal Gradient Induced Non-Mass Dependent effect, TGI-NMD). The mechanism(s) that is responsible to such striking observation remains unanswered. In our past studies, we investigated polyatomic molecules, O2 and SF6, and we suggested that nuclear spin effect could be responsible to the observed NMD effect in a way of changing diffusion coefficients of certain molecules, owing to the fact of negligible delta S-36 anomaly for SF6.. On the other hand, our results also showed that for both diffusion and convection under thermal gradient, this NMD effect is increased by lower gas pressure, bigger temperature gradient and lower average temperature, which indicate that the nuclear spin effect may not be the significant contributor as the energies involved in the hyperfine effect are much smaller than those with molecular collisions, especially under convective conditions.

A new physics-based modeling approach for tsunami-ionosphere coupling

NASA Astrophysics Data System (ADS)

Meng, X.; Komjathy, A.; Verkhoglyadova, O. P.; Yang, Y.-M.; Deng, Y.; Mannucci, A. J.

2015-06-01

Tsunamis can generate gravity waves propagating upward through the atmosphere, inducing total electron content (TEC) disturbances in the ionosphere. To capture this process, we have implemented tsunami-generated gravity waves into the Global Ionosphere-Thermosphere Model (GITM) to construct a three-dimensional physics-based model WP (Wave Perturbation)-GITM. WP-GITM takes tsunami wave properties, including the wave height, wave period, wavelength, and propagation direction, as inputs and time-dependently characterizes the responses of the upper atmosphere between 100 km and 600 km altitudes. We apply WP-GITM to simulate the ionosphere above the West Coast of the United States around the time when the tsunami associated with the March 2011 Tohuku-Oki earthquke arrived. The simulated TEC perturbations agree with Global Positioning System observations reasonably well. For the first time, a fully self-consistent and physics-based model has reproduced the GPS-observed traveling ionospheric signatures of an actual tsunami event.

Solid-state thermal behavior and stability studies of theophylline-citric acid cocrystals prepared by neat cogrinding or thermal treatment

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

Hsu, Po-Chun; Lin, Hong-Liang; Wang, Shun-Li, E-mail: wangshunli@mail.ncyu.edu.tw

To investigate the thermal behavior of cocrystal formed between anhydrous theophylline (TP) and anhydrous citric acid (CA) by neat manual cogrinding or thermal treatment, DSC and FTIR microspectroscopy with curve-fitting analysis were applied. The physical mixture and 60-min ground mixture were stored at 55{+-}0.5 Degree-Sign C/40{+-}2% RH condition to determine their stability behavior. Typical TP-CA cocrystals were prepared by slow solvent evaporation method. Results indicate that the cogrinding process could gradually induce the cocrystal formation between TP and CA. The IR spectral peak shift from 3495 to 3512 cm{sup -1} and the stepwise appearance of several new IR peaks atmore » 1731, 1712, 1676, 1651, 1557 and 1265 cm{sup -1} with cogrinding time suggest that the mechanism of TP-CA cocrystal formation was evidenced by interacting TP with CA through the intermolecular O-H{center_dot}{center_dot}{center_dot}O hydrogen bonding. The stability of 60-min ground mixture of TP-CA was confirmed at 55{+-}0.5 Degree-Sign C/40{+-}2% RH condition over a storage time of 60 days. - Garphical abstract: Cogrinding, thermal and solvent-evaporation methods might easily induce the theophylline-citric acid cocrystal formation. Highlights: Black-Right-Pointing-Pointer Cogrinding process could gradually induce the cocrystal formation between TP and CA. Black-Right-Pointing-Pointer The TP-CA cocrystal was formed through the intermolecular O-H{center_dot}{center_dot}{center_dot}O hydrogen bonding. Black-Right-Pointing-Pointer The 60-min TP-CA ground mixture was similar to the solvent-evaporated cocrystal. Black-Right-Pointing-Pointer The thermal-induced TP-CA cocrystal formation was confirmed by pre-heating the physical mixture to 152 Degree-Sign C. Black-Right-Pointing-Pointer The 60-min TP-CA ground mixture was stable at accelerated condition over a storage time of 60 days.« less

Simulation of plasma loading of high-pressure RF cavities

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

Yu, K.; Samulyak, R.; Yonehara, K.

2018-01-11

Muon beam-induced plasma loading of radio-frequency (RF) cavities filled with high pressure hydrogen gas with 1% dry air dopant has been studied via numerical simulations. The electromagnetic code SPACE, that resolves relevant atomic physics processes, including ionization by the muon beam, electron attachment to dopant molecules, and electron-ion and ion-ion recombination, has been used. Simulations studies have also been performed in the range of parameters typical for practical muon cooling channels.

[Xenon: From rare gaz to doping product].

PubMed

Tassel, Camille; Le Daré, Brendan; Morel, Isabelle; Gicquel, Thomas

2016-04-01

Doping is defined as the use of processes or substances to artificially increase physical or mental performance. Xenon is a noble gas used as an anesthetic and recently as a doping agent. Xenon is neuroprotective as an antagonist of NMDA glutamate receptors. Xenon stimulates the synthesis of erythropoietin (EPO) by increase of hypoxia inducible factor (HIF). Xenon would be a new doping product, maintaining doping methods ahead of detection. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Conceptual design for the Space Station Freedom fluid physics/dynamics facility

NASA Technical Reports Server (NTRS)

Thompson, Robert L.; Chucksa, Ronald J.; Omalley, Terence F.; Oeftering, Richard C.

1993-01-01

A study team at NASA's Lewis Research Center has been working on a definition study and conceptual design for a fluid physics and dynamics science facility that will be located in the Space Station Freedom's baseline U.S. Laboratory module. This modular, user-friendly facility, called the Fluid Physics/Dynamics Facility, will be available for use by industry, academic, and government research communities in the late 1990's. The Facility will support research experiments dealing with the study of fluid physics and dynamics phenomena. Because of the lack of gravity-induced convection, research into the mechanisms of fluids in the absence of gravity will help to provide a better understanding of the fundamentals of fluid processes. This document has been prepared as a final version of the handout for reviewers at the Fluid Physics/Dynamics Facility Assessment Workshop held at Lewis on January 24 and 25, 1990. It covers the background, current status, and future activities of the Lewis Project Study Team effort. It is a revised and updated version of a document entitled 'Status Report on the Conceptual Design for the Space Station Fluid Physics/Dynamics Facility', dated January 1990.

Obama cares about visuo-spatial attention: perception of political figures moves attention and determines gaze direction.

PubMed

Mills, Mark; Smith, Kevin B; Hibbing, John R; Dodd, Michael D

2015-02-01

Processing an abstract concept such as political ideology by itself is difficult but becomes easier when a background situation contextualizes it. Political ideology within American politics, for example, is commonly processed using space metaphorically, i.e., the political "left" and "right" (referring to Democrat and Republican views, respectively), presumably to provide a common metric to which abstract features of ideology can be grounded and understood. Commonplace use of space as metaphor raises the question of whether an inherently non-spatial stimulus (e.g., picture of the political "left" leader, Barack Obama) can trigger a spatially-specific response (e.g., attentional bias toward "left" regions of the visual field). Accordingly, pictures of well-known Democrats and Republicans were presented as central cues in peripheral target detection (Experiment 1) and saccadic free-choice (Experiment 2) tasks to determine whether perception of stimuli lacking a direct association with physical space nonetheless induce attentional and oculomotor biases in the direction compatible with the ideological category of the cue (i.e., Democrat/left and Republican/right). In Experiment 1, target detection following presentation of a Democrat (Republican) was facilitated for targets appearing to the left (right). In Experiment 2, participants were more likely to look left (right) following presentation of a Democrat (Republican). Thus, activating an internal representation of political ideology induced a shift of attention and biased choice of gaze direction in a spatially-specific manner. These findings demonstrate that the link between conceptual processing and spatial attention can be totally arbitrary, with no reference to physical or symbolic spatial information. Published by Elsevier B.V.

Maintenance of exercise-induced benefits in physical functioning and bone among elderly women.

PubMed

Karinkanta, S; Heinonen, A; Sievänen, H; Uusi-Rasi, K; Fogelholm, M; Kannus, P

2009-04-01

This study showed that about a half of the exercise-induced gain in dynamic balance and bone strength was maintained one year after cessation of the supervised high-intensity training of home-dwelling elderly women. However, to maintain exercise-induced gains in lower limb muscle force and physical functioning, continued training seems necessary. Maintenance of exercise-induced benefits in physical functioning and bone structure was assessed one year after cessation of 12-month randomized controlled exercise intervention. Originally 149 healthy women 70-78 years of age participated in the 12-month exercise RCT and 120 (81%) of them completed the follow-up study. Self-rated physical functioning, dynamic balance, leg extensor force, and bone structure were assessed. During the intervention, exercise increased dynamic balance by 7% in the combination resistance and balance-jumping training group (COMB). At the follow-up, a 4% (95% CI: 1-8%) gain compared with the controls was still seen, while the exercise-induced isometric leg extension force and self-rated physical functioning benefits had disappeared. During the intervention, at least twice a week trained COMB subjects obtained a significant 2% benefit in tibial shaft bone strength index compared to the controls. A half of this benefit seemed to be maintained at the follow-up. Exercise-induced benefits in dynamic balance and rigidity in the tibial shaft may partly be maintained one year after cessation of a supervised 12-month multi-component training in initially healthy elderly women. However, to maintain the achieved gains in muscle force and physical functioning, continued training seems necessary.

Adaptation of bone to physiological stimuli.

PubMed

Judex, S; Gross, T S; Bray, R C; Zernicke, R F

1997-05-01

The ability of bone to alter its morphology in response to local physical stimuli is predicated upon the appropriate recruitment of bone cell populations. In turn, the ability to initiate cellular recruitment is influenced by numerous local and systemic factors. In this paper, we discuss data from three ongoing projects from our laboratory that examine how physiological processes influence adaptation and growth in the skeleton. In the first study, we recorded in vivo strains to quantify the locomotion-induced distribution of two parameters closely related to bone fluid flow strain rate and strain gradients. We found that the magnitude of these parameters (and thus the implied fluid flow) varies substantially within a given cross-section, and that while strain rate magnitude increases uniformly with elevated speed, strain gradients increase focally as gait speed is increased. Secondly, we examined the influence of vascular alterations on bone adaptation by assessing bone blood flow and bone mechanical properties in an in vivo model of trauma-induced joint laxity. A strong negative correlation (r2 = 0.8) was found between increased blood flow (76%) in the primary and secondary spongiosa and decreased stiffness (-34%) following 14 weeks of joint laxity. These data suggest that blood flow and/or vascular adaptation may interact closely with bone adaptation initiated by trauma. Thirdly, we examined the effect of a systemic influence upon skeletal health. After 4 weeks old rats were fed high fat-sucrose diets for 2 yr, their bone mechanical properties were significantly reduced. These changes were primarily due to interference with normal calcium absorption. In the aggregate, these studies emphasize the complexity of bone's normal physical environment, and also illustrate the potential interactions of local and systemic factors upon the process by which bone adapts to physical stimuli.

Spatiotemporal Evolution of the Wound Repairing Process in a 3D Human Dermis Equivalent.

PubMed

Lombardi, Bernadette; Casale, Costantino; Imparato, Giorgia; Urciuolo, Francesco; Netti, Paolo Antonio

2017-07-01

Several skin equivalent models have been developed to investigate in vitro the re-epithelialization process occurring during wound healing. Although these models recapitulate closure dynamics of epithelial cells, they fail to capture how a wounded connective tissue rebuilds its 3D architecture until the evolution in a scar. Here, the in vitro tissue repair dynamics of a connective tissue is replicated by using a 3D human dermis equivalent (3D-HDE) model composed of fibroblasts embedded in their own extracellular matrix (ECM). After inducing a physical damage, 3D-HDE undergoes a series of cellular and extracellular events quite similar to those occurring in the native dermis. In particular, fibroblasts differentiation toward myofibroblasts phenotype and neosynthesis of hyaluronic acid, fibronectin, and collagen during the repair process are assessed. Moreover, tissue reorganization after physical damage is investigated by measuring the diameter of bundles and the orientation of fibers of the newly formed ECM network. Finally, the ultimate formation of a scar-like tissue as physiological consequence of the repair and closure process is demonstrated. Taking together, the results highlight that the presence of cell-assembled and responsive stromal components enables quantitative and qualitative in vitro evaluation of the processes involved in scarring during wound healing. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Creatine kinase MM TaqI and methylenetetrahydrofolate reductase C677T and A1298C gene polymorphisms influence exercise-induced C-reactive protein levels.

PubMed

Miranda-Vilela, Ana Luisa; Akimoto, Arthur K; Lordelo, Graciana S; Pereira, Luiz C S; Grisolia, Cesar K; Klautau-Guimarães, Maria de Nazaré

2012-01-01

Physical training induces beneficial adaptations, but exhausting exercise increases reactive oxygen species, which can cause muscular injuries with consequent inflammatory processes, implying jeopardized performance and possibly overtraining. Acute strenuous exercise almost certainly exceeds the benefits of physical activity; it can compromise performance and may contribute to increased future risk of cardiovascular disease (CVD) in athletes. Polymorphisms in the muscle-type creatine kinase (CK-MM) gene may influence performance and adaptation to training, while many potentially significant genetic variants are reported as risk factors for CVD. Therefore, we investigated the influence of polymorphisms in CK-MM TaqI and NcoI, methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) and C-reactive protein (CRP G1059C) genes on exercise-induced damage and inflammation markers. Blood samples were taken immediately after a race (of at least 4 km) that took place outdoors on flat tracks, and were submitted to genotyping and biochemical evaluation of aspartate aminotransferase (AST), CK, CRP and high-sensitivity CRP (hs-CRP). CK-MM TaqI polymorphism significantly influenced results of AST, CK and hs-CRP, and an association between MTHFR C677T and A1298C with CRP level was found, although these levels did not exceed reference values. Results indicate that these polymorphisms can indirectly influence performance, contribute to higher susceptibility to exercise-induced inflammation or protection against it, and perhaps affect future risks of CVD in athletes.

Creatine kinase MM TaqI and methylenetetrahydrofolate reductase C677T and A1298C gene polymorphisms influence exercise-induced C-reactive protein levels.

PubMed

Miranda-Vilela, Ana Luisa; Akimoto, Arthur K; Lordelo, Graciana S; Pereira, Luiz C S; Grisolia, Cesar K; Klautau-Guimarães, Maria de Nazaré

2012-03-01

Physical training induces beneficial adaptations, but exhausting exercise increases reactive oxygen species, which can cause muscular injuries with consequent inflammatory processes, implying jeopardized performance and possibly overtraining. Acute strenuous exercise almost certainly exceeds the benefits of physical activity; it can compromise performance and may contribute to increased future risk of cardiovascular disease (CVD) in athletes. Polymorphisms in the muscle-type creatine kinase (CK-MM) gene may influence performance and adaptation to training, while many potentially significant genetic variants are reported as risk factors for CVD. Therefore, we investigated the influence of polymorphisms in CK-MM TaqI and NcoI, methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) and C-reactive protein (CRP G1059C) genes on exercise-induced damage and inflammation markers. Blood samples were taken immediately after a race (of at least 4 km) that took place outdoors on flat tracks, and were submitted to genotyping and biochemical evaluation of aspartate aminotransferase (AST), CK, CRP and high-sensitivity CRP (hs-CRP). CK-MM TaqI polymorphism significantly influenced results of AST, CK and hs-CRP, and an association between MTHFR C677T and A1298C with CRP level was found, although these levels did not exceed reference values. The results indicate that these polymorphisms can indirectly influence performance, contribute to higher susceptibility to exercise-induced inflammation or protection against it, and perhaps affect future risks of CVD in athletes.

The nucleosome: A transparent, slippery, sticky and yet stable DNA-protein complex

NASA Astrophysics Data System (ADS)

Schiessel, H.

2006-03-01

Roughly three quarters of eucaryotic DNA are tightly wrapped onto protein cylinders organized in so-called nucleosomes. Despite this fact, the wrapped DNA cannot be inert since DNA is at the heart of many crucial life processes. We focus here on physical mechanisms that might allow nucleosomes to perform a great deal of such processes, specifically 1) on unwrapping fluctuations that give DNA-binding proteins access to the wrapped DNA portions without disrupting the nucleosome as a whole, 2) on corkscrew sliding along DNA and some implications and on 3) tail-bridging-induced attraction between nucleosomes as a means of controlling higher-order folding.

Preparation and characterization of Tripterygium wilfordii multi-glycoside nanoparticle using supercritical anti-solvent process.

PubMed

Chen, Fengli; Li, Tong; Li, Shuangyang; Hou, Kexin; Liu, Zaizhi; Li, Lili; Cui, Guoqiang; Zu, Yuangang; Yang, Lei

2014-02-17

The aim of this study was to prepare nanosized Tripterygium wilfordii multi-glycoside (GTW) powders by the supercritical antisolvent precipitation process (SAS), and to evaluate the anti-inflammatory effects. Ethanol was used as solvent and carbon dioxide was used as an antisolvent. The effects of process parameters such as precipitation pressure (15-35 MPa), precipitation temperature (45-65 °C), drug solution flow rates (3-7 mL/min) and drug concentrations (10-30 mg/mL) were investigated. The nanospheres obtained with mean diameters ranged from 77.5 to 131.8 nm. The processed and unprocessed GTW were characterized by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and thermal gravimetric analysis. The present study was designed to investigate the beneficial effect of the GTW nanoparticles on adjuvant-induced arthritis in albino rats. The processed and unprocessed GTW were tested against Freund's complete adjuvant-induced arthritis in rats. Blood samples were collected for the estimation of interleukins (IL-1α, IL-1β) and tumor necrosis factor-α (TNF-α). It was concluded that physicochemical properties and anti-inflammatory activity of GTW nanoparticles could be improved by physical modification, such as particle size reduction using supercritical antisolvent (SAS) process. Further, SAS process was a powerful methodology for improving the physicochemical properties and anti-inflammatory activity of GTW.

Preparation and Characterization of Tripterygium wilfordii Multi-Glycoside Nanoparticle Using Supercritical Anti-Solvent Process

PubMed Central

Chen, Fengli; Li, Tong; Li, Shuangyang; Hou, Kexin; Liu, Zaizhi; Li, Lili; Cui, Guoqiang; Zu, Yuangang; Yang, Lei

2014-01-01

The aim of this study was to prepare nanosized Tripterygium wilfordii multi-glycoside (GTW) powders by the supercritical antisolvent precipitation process (SAS), and to evaluate the anti-inflammatory effects. Ethanol was used as solvent and carbon dioxide was used as an antisolvent. The effects of process parameters such as precipitation pressure (15–35 MPa), precipitation temperature (45–65 °C), drug solution flow rates (3–7 mL/min) and drug concentrations (10–30 mg/mL) were investigated. The nanospheres obtained with mean diameters ranged from 77.5 to 131.8 nm. The processed and unprocessed GTW were characterized by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and thermal gravimetric analysis. The present study was designed to investigate the beneficial effect of the GTW nanoparticles on adjuvant-induced arthritis in albino rats. The processed and unprocessed GTW were tested against Freund’s complete adjuvant-induced arthritis in rats. Blood samples were collected for the estimation of interleukins (IL-1α, IL-1β) and tumor necrosis factor-α (TNF-α). It was concluded that physicochemical properties and anti-inflammatory activity of GTW nanoparticles could be improved by physical modification, such as particle size reduction using supercritical antisolvent (SAS) process. Further, SAS process was a powerful methodology for improving the physicochemical properties and anti-inflammatory activity of GTW. PMID:24549173

Graphene nanoribbons: Relevance of etching process

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

Simonet, P., E-mail: psimonet@phys.ethz.ch; Bischoff, D.; Moser, A.

2015-05-14

Most graphene nanoribbons in the experimental literature are patterned using plasma etching. Various etching processes induce different types of defects and do not necessarily result in the same electronic and structural ribbon properties. This study focuses on two frequently used etching techniques, namely, O{sub 2} plasma ashing and O{sub 2 }+ Ar reactive ion etching (RIE). O{sub 2} plasma ashing represents an alternative to RIE physical etching for sensitive substrates, as it is a more gentle chemical process. We find that plasma ashing creates defective graphene in the exposed trenches, resulting in instabilities in the ribbon transport. These are probably caused bymore » more or larger localized states at the edges of the ashed device compared to the RIE defined device.« less

Dynamic behavior of the weld pool in stationary GMAW

NASA Astrophysics Data System (ADS)

Chapuis, J.; Romero, E.; Bordreuil, C.; Soulié, F.; Fras, G.

2010-06-01

Because hump formation limits welding productivity, better understanding of the humping phenomena during the welding process is needed to access to process modifications that decrease the tendency for hump formation and then allow higher productivity welding. From a physical point of view, the mechanism identified is the Rayleigh instability initiated by strong surface tension gradient which induces a variation of kinetic flow. But the causes of the appearance of this instability are not yet well explained. Because of the phenomena complex and multi-physics, we chose in first step to conduct an analysis of the characteristic times involved in weld pool in pulsed stationary GMAW. The goal is to study the dynamic behavior of the weld pool, using our experimental multi physics approach. The experimental tool and methodology developed to understand these fast phenomena are presented first: frames acquisition with high speed digital camera and specific optical devices, numerical library. The analysis of geometric parameters of the weld pool during welding operation are presented in the last part: we observe the variations of wetting angles (or contact lines angles), the base and the height of the weld pool (macro-drop) versus weld time.

Physical fatigue increases neural activation during eyes-closed state: a magnetoencephalography study.

PubMed

Tanaka, Masaaki; Ishii, Akira; Watanabe, Yasuyoshi

2015-11-05

Fatigue, defined as difficulty initiating or sustaining voluntary activities, can be classified as physical or mental. In this study, we use magnetoencephalography (MEG) to quantify the effect of physical fatigue on neural activity under the condition of simulated physical load. Thirteen healthy right-handed male volunteers participated in this study. The experiment consisted of one fatigue-inducing physical task session performed between two MEG sessions. During the 10-min physical task session, participants performed maximum-effort handgrips with the left hand lasting 1 s every 4 s; during MEG sessions, 3-min recordings were made during the eyes-closed state. MEG data were analyzed using narrow-band adaptive spatial filtering methods. Alpha-frequency band (8-13 Hz) power in the left postcentral gyrus, precentral gyrus, and middle frontal gyrus (Brodmann's areas 1, 2, 3, 4, 6, and 46) were decreased after performing the physical fatigue-inducing task. These results show that performing the physical fatigue-inducing task caused activation of the left sensorimotor and prefrontal areas, manifested as decreased alpha-frequency band power in these brain areas. Our results increase understanding of the neural mechanisms of physical fatigue.

Ultrafast spectral dynamics of dual-color-soliton intracavity collision in a mode-locked fiber laser

NASA Astrophysics Data System (ADS)

Wei, Yuan; Li, Bowen; Wei, Xiaoming; Yu, Ying; Wong, Kenneth K. Y.

2018-02-01

The single-shot spectral dynamics of dual-color-soliton collisions inside a mode-locked laser is experimentally and numerically investigated. By using the all-optically dispersive Fourier transform, we spectrally unveil the collision-induced soliton self-reshaping process, which features dynamic spectral fringes over the soliton main lobe, and the rebuilding of Kelly sidebands with wavelength drifting. Meanwhile, the numerical simulations validate the experimental observation and provide additional insights into the physical mechanism of the collision-induced spectral dynamics from the temporal domain perspective. It is verified that the dynamic interference between the soliton and the dispersive waves is responsible for the observed collision-induced spectral evolution. These dynamic phenomena not only demonstrate the role of dispersive waves in the sophisticated soliton interaction inside the laser cavity, but also facilitate a deeper understanding of the soliton's inherent stability.

Finite element analysis when orthogonal cutting of hybrid composite CFRP/Ti

NASA Astrophysics Data System (ADS)

Xu, Jinyang; El Mansori, Mohamed

2015-07-01

Hybrid composite, especially CFRP/Ti stack, is usually considered as an innovative structural configuration for manufacturing the key load-bearing components in modern aerospace industry. This paper originally proposed an FE model to simulate the total chip formation process dominated the hybrid cutting operation. The hybrid composite model was established based on three physical constituents, i.e., Ti constituent, interface and CFRP constituent. Different constitutive models and damage criteria were introduced to replicate the interrelated cutting behaviour of the stack material. The CFRP/Ti interface was modelled as a third phase through the concept of cohesive zone (CZ). Particular attention was made on the comparative studies of the influence of different cutting-sequence strategies on the machining responses induced in hybrid stack cutting. The numerical results emphasized the pivotal role of cutting-sequence strategy on the various machining induced responses including cutting-force generation, machined surface quality and induced interface damage.

Jet-induced star formation by accreting black holes: impact on stellar, galaxy, and cosmic evolution

NASA Astrophysics Data System (ADS)

Mirabel, Igor Felix

2016-07-01

Evidence that relativistic jets trigger star formation along their axis has been found associated to low redshift and high redshift accreting supermassive black holes. However, the physical processes by which jet-cloud interaction may trigger star formation has so far not been elucidated. To gain insight into this potentially important star formation mechanism during reionization, when microquasars were form prolifically before AGN, our international team is carrying out a muliwavelength study of a microquasar jet-induced star formation region in the Milky Way using data from space missions (Chandra, Integral, ISO, Herschel) and from the ground (at cm and mm wavelengths with the VLA and IRAM, and IR with Gemini and VLT). I will show that this relative nearby star forming region is an ideal laboratory to test models of jet-induced star formation elsewhere in the universe.

Spin Flips versus Spin Transport in Nonthermal Electrons Excited by Ultrashort Optical Pulses in Transition Metals

NASA Astrophysics Data System (ADS)

Shokeen, V.; Sanchez Piaia, M.; Bigot, J.-Y.; Müller, T.; Elliott, P.; Dewhurst, J. K.; Sharma, S.; Gross, E. K. U.

2017-09-01

A joint theoretical and experimental investigation is performed to understand the underlying physics of laser-induced demagnetization in Ni and Co films with varying thicknesses excited by 10 fs optical pulses. Experimentally, the dynamics of spins is studied by determining the time-dependent amplitude of the Voigt vector, retrieved from a full set of magnetic and nonmagnetic quantities performed on both sides of films, with absolute time reference. Theoretically, ab initio calculations are performed using time-dependent density functional theory. Overall, we demonstrate that spin-orbit induced spin flips are the most significant contributors with superdiffusive spin transport, which assumes only that the transport of majority spins without spin flips induced by scattering does not apply in Ni. In Co it plays a significant role during the first ˜20 fs only. Our study highlights the material dependent nature of the demagnetization during the process of thermalization of nonequilibrium spins.

Suspected microbial-induced sedimentary structures (MISS) in Furongian (Upper Cambrian; Jiangshanian, Sunwaptan) strata of the Upper Mississippi Valley

USGS Publications Warehouse

Eoff, Jennifer D.

2014-01-01

The Furongian (Upper Cambrian; Jiangshanian and Sunwaptan) Tunnel City Group (Lone Rock Formation and Mazomanie Formation), exposed in Wisconsin and Minnesota, represents a shallow-marine clastic environment during a time of exceptionally high sea level. Lithofacies from shoreface to transitional-offshore settings document deposition in a wave- and storm-dominated sea. Flooding of the cratonic interior was associated with formation of a condensed section and the extensive development of microbial mats. Biolamination, mat fragments, wrinkle structures, and syneresis cracks are preserved in various sandstone facies of the Lone Rock Formation, as is evidence for the cohesive behavior of sand. These microbial-induced sedimentary structures (MISS) provide unique signals of biological–physical processes that physical structures alone cannot mimic. The MISS are associated with a trilobite extinction event in the Steptoean–Sunwaptan boundary interval. This may support recent claims that Phanerozoic microbial mats were opportunistic disaster forms that flourished during periods of faunal turnover. Further investigation of stratigraphic, taphonomic, and other potential biases, however, is needed to fully test this hypothesis.

Applicability of UV laser-induced solid-state fluorescence spectroscopy for characterization of solid dosage forms.

PubMed

Woltmann, Eva; Meyer, Hans; Weigel, Diana; Pritzke, Heinz; Posch, Tjorben N; Kler, Pablo A; Schürmann, Klaus; Roscher, Jörg; Huhn, Carolin

2014-10-01

High production output of solid pharmaceutical formulations requires fast methods to ensure their quality. Likewise, fast analytical procedures are required in forensic sciences, for example at customs, to substantiate an initial suspicion. We here present the design and the optimization of an instrumental setup for rapid and non-invasive characterization of tablets by laser-induced fluorescence spectroscopy (with a UV-laser (λ ex = 266 nm) as excitation source) in reflection geometry. The setup was first validated with regard to repeatability, bleaching phenomena, and sensitivity. The effect on the spectra by the physical and chemical properties of the samples, e.g. their hardness, homogeneity, chemical composition, and granule grain size of the uncompressed material, using a series of tablets, manufactured in accordance with design of experiments, was investigated. Investigation of tablets with regard to homogeneity, especially, is extremely important in pharmaceutical production processes. We demonstrate that multiplicative scatter correction is an appropriate tool for data preprocessing of fluorescence spectra. Tablets with different physical and chemical characteristics can be discriminated well from their fluorescence spectra by subjecting the results to principal component analysis.

Searches for comet-induced solar flares

NASA Astrophysics Data System (ADS)

Ibadov, Subhon; Ibodov, Firuz

During the last decade we have carried out analytical consideration of the impacts of comets with the Sun: the study of passage of cometary nuclei through the solar chromosphere and photosphere was carried out taking into account aerodynamic crushing of the nucleus, transversal expansion of the crushed mass and aerodynamic deceleration of the flattening structure. The results indicate that the stopping of the hypervelocity, more than 600 km/s, comet matter near the photosphere has essentially "explosive" character and will be accompanied by generation of a strong "blast" shock wave as well as ejection of a hot plasma from a relatively very thin,"exploding", near-photosphere layer. Observational manifestations of these processes, comet-induced solar flares, CISF, will be anomalous line emission of metal atoms/ions like Fe, Si, etc. from chromosphere/corona regions and continuum emission of a high-temperature, around 10^6-10^7 K, plasma cloud near the solar surface. Space observations of the phenomena by solar telescopes, including future out-of-ecliptic ones, are of interest for the physics/prognosis of solar flares as well as physics of comets.

Transmission Electron Microscopy of Minerals and Rocks

NASA Astrophysics Data System (ADS)

McLaren, Alex C.

1991-04-01

Of the many techniques that have been applied to the study of crystal defects, none has contributed more to our understanding of their nature and influence on the physical and chemical properties of crystalline materials than transmission electron microscopy (TEM). TEM is now used extensively by an increasing number of earth scientists for direct observation of defect microstructures in minerals and rocks. Transmission Electron Microscopy of Rocks and Minerals is an introduction to the principles of the technique and is the only book to date on the subject written specifically for geologists and mineralogists. The first part of the book deals with the essential physics of the transmission electron microscope and presents the basic theoretical background required for the interpretation of images and electron diffraction patterns. The final chapters are concerned with specific applications of TEM in mineralogy and deal with such topics as planar defects, intergrowths, radiation-induced defects, dislocations and deformation-induced microstructures. The examples cover a wide range of rock-forming minerals from crustal rocks to those in the lower mantle, and also take into account the role of defects in important mineralogical and geological processes.

Influence of processing and storage of integral grape juice (Vitis labrusca L.) on its physical and chemical characteristics, cytotoxicity, and mutagenicity in vitro.

PubMed

Düsman, E; Almeida, I V; Pinto, E P; Lucchetta, L; Vicentini, V E P

2017-05-31

Integral grape juice is extracted from the grape through processes that allow the retention of their natural composition. However, due to the severity of some processes, fruit juices can undergo changes in their quality. The present study evaluated the cytotoxic and mutagenic effects of integral grape juice by a cytokinesis-blocked micronucleus assay in Rattus norvegicus hepatoma cells (HTC) in vitro. Vitis labrusca L. (variety Concord) were produced organically and by a conventional system, and their juice was extracted by a hot extraction process. The organic grapes were subjected to ultraviolet-type C radiation (UV-C). Experiments were performed after production and after 6 months in storage. Physicochemical analyses revealed that UV-C irradiation of organic grapes, the juice production process, and storage resulted in nutraceutical alterations. However, none of the juice concentrations were cytotoxic to HTC cells by the cytokinesis-blocked proliferation index results or were mutagenic, because the formation of micronucleated cells was not induced. In general, juice induced cell proliferation, possibly due to the presence of vitamins and sugar content (total soluble solid). The data increased the understanding of food technology and confirmed the quality and safety consumption of these juices.

RADIATION CHEMISTRY 2010 GORDON RESEARCH CONFERENCE JULY 18-23

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

Thomas Orlando

The 2010 Gordon Conference on Radiation Chemistry will present cutting edge research regarding the study of radiation-induced chemical transformations. Radiation Chemistry or 'high energy' chemistry is primarily initiated by ionizing radiation: i.e. photons or particles with energy sufficient to create conduction band electrons and 'holes', excitons, ionic and neutral free radicals, highly excited states, and solvated electrons. These transients often interact or 'react' to form products vastly different than those produced under thermal equilibrium conditions. The non-equilibrium, non-thermal conditions driving radiation chemistry exist in plasmas, star-forming regions, the outer solar system, nuclear reactors, nuclear waste repositories, radiation-based medical/clinical treatment centersmore » and in radiation/materials processing facilities. The 2010 conference has a strong interdisciplinary flavor with focus areas spanning (1) the fundamental physics and chemistry involved in ultrafast (atto/femtosecond) energy deposition events, (2) radiation-induced processes in biology (particularly spatially resolved studies), (3) radiation-induced modification of materials at the nanoscale and cosmic ray/x-ray mediated processes in planetary science/astrochemistry. While the conference concentrates on fundamental science, topical applied areas covered will also include nuclear power, materials/polymer processing, and clinical/radiation treatment in medicine. The Conference will bring together investigators at the forefront of their field, and will provide opportunities for junior scientists and graduate students to present work in poster format or as contributors to the Young Investigator session. The program and format provides excellent avenues to promote cross-disciplinary collaborations.« less

Understanding the process of fascial unwinding.

PubMed

Minasny, Budiman

2009-09-23

Fascial or myofascial unwinding is a process in which a client undergoes a spontaneous reaction in response to the therapist's touch. It can be induced by using specific techniques that encourage a client's body to move into areas of ease. Unwinding is a popular technique in massage therapy, but its mechanism is not well understood. In the absence of a scientific explanation or hypothesis of the mechanism of action, it can be interpreted as "mystical." This paper proposes a model that builds on the neurobiologic, ideomotor action, and consciousness theories to explain the process and mechanism of fascial unwinding. HYPOTHETICAL MODEL: During fascial unwinding, the therapist stimulates mechanoreceptors in the fascia by applying gentle touch and stretching. Touch and stretching induce relaxation and activate the parasympathetic nervous system. They also activate the central nervous system, which is involved in the modulation of muscle tone as well as movement. As a result, the central nervous system is aroused and thereby responds by encouraging muscles to find an easier, or more relaxed, position and by introducing the ideomotor action. Although the ideomotor action is generated via normal voluntary motor control systems, it is altered and experienced as an involuntary response. Fascial unwinding occurs when a physically induced suggestion by a therapist prompts ideomotor action that the client experiences as involuntary. This action is guided by the central nervous system, which produces continuous action until a state of ease is reached. Consequently, fascial unwinding can be thought of as a neurobiologic process employing the self-regulation dynamic system theory.

Physical Activity Modulates Common Neuroplasticity Substrates in Major Depressive and Bipolar Disorder.

PubMed

Phillips, Cristy

2017-01-01

Mood disorders (MDs) are chronic, recurrent mental diseases that affect millions of individuals worldwide. Although the biogenic amine model has provided some clinical utility, a need remains to better understand the interrelated mechanisms that contribute to neuroplasticity deficits in MDs and the means by which various therapeutics mitigate them. Of those therapeutics being investigated, physical activity (PA) has shown clear and consistent promise. Accordingly, the aims of this review are to (1) explicate key modulators, processes, and interactions that impinge upon multiple susceptibility points to effectuate neuroplasticity deficits in MDs; (2) explore the putative mechanisms by which PA mitigates these features; (3) review protocols used to induce the positive effects of PA in MDs; and (4) highlight implications for clinicians and researchers.

There is more: Intrasexual competitiveness, physical dominance, and intrasexual collaboration.

PubMed

Buunk, Abraham P

2017-01-01

It is emphasized that in organizational settings, the responses to same-sex attractive others are enhanced among individuals high in intrasexual competitiveness; that especially attractive rivals who are perceived as unfriendly will induce competition; that among males, physical dominance may induce more competition than physical attractiveness; and that especially males may prefer to associate with attractive same-sex others for intrasexual collaboration.

On the ejection-induced instability in Navier-Stokes solutions of unsteady separation.

PubMed

Obabko, Aleksandr V; Cassel, Kevin W

2005-05-15

Numerical solutions of the flow induced by a thick-core vortex have been obtained using the unsteady, two-dimensional Navier-Stokes equations. The presence of the vortex causes an adverse pressure gradient along the surface, which leads to unsteady separation. The calculations by Brinckman and Walker for a similar flow identify a possible instability, purported to be an inviscid Rayleigh instability, in the region where ejection of near-wall vorticity occurs during the unsteady separation process. In results for a range of Reynolds numbers in the present investigation, the oscillations are also found to occur. However, they can be eliminated with increased grid resolution. Despite this behaviour, the instability may be physical but requires a sufficient amplitude of disturbances to be realized.

Control of optical bistability and third-order nonlinearity via tunneling induced quantum interference in triangular quantum dot molecules

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

Tian, Si-Cong, E-mail: tiansicong@ciomp.ac.cn; Tong, Cun-Zhu, E-mail: tongcz@ciomp.ac.cn; Zhang, Jin-Long

The optical bistability of a triangular quantum dot molecules embedded inside a unidirectional ring cavity is studied. The type, the threshold and the hysteresis loop of the optical bistability curves can be modified by the tunneling parameters, as well as the probe laser field. The linear and nonlinear susceptibilities of the medium are also studied to interpret the corresponding results. The physical interpretation is that the tunneling can induce the quantum interference, which modifies the linear and the nonlinear response of the medium. As a consequence, the characteristics of the optical bistability are changed. The scheme proposed here can bemore » utilized for optimizing and controlling the optical switching process.« less

Investigating ground effects on mixing and afterburning during a TNT explosion

NASA Astrophysics Data System (ADS)

Fedina, E.; Fureby, C.

2013-05-01

In this paper, the unconfined and semi-confined condensed phase explosions of TNT will be studied using large eddy simulations based on the unsteady, compressible, reacting, multi-species Navier-Stokes equations to gain further understanding of the physical processes involved in a condensed phase explosion and the effect of confinement on the physical processes involved. The analysis of the mixing and afterburning of TNT explosions in free air (unconfined) and near the ground (semi-confined) indicates that the combustion region of detonation products and air is determined by the vorticity patterns, which are induced by the Richtmeyer-Meshkov instabilities that arise during the explosion. When the explosive is detonated in the vicinity of a surface, the surface affects the shock propagation by creating complex shock systems, thereby changing the orientation of the vorticity, giving the afterburning a mushroom shape, and increasing performance of an explosive charge by prolonging the existence of the mixing layer and thereby the afterburning.

Fluid Induced Earthquakes: From KTB Experiments to Natural Seismicity Swarms.

NASA Astrophysics Data System (ADS)

Shapiro, S. A.

2006-12-01

Experiments with borehole fluid injections are typical for exploration and development of hydrocarbon or geothermal reservoirs (e.g., fluid-injection experiments at Soultz, France and at Fenton-Hill, USA). Microseismicity occurring during such operations has a large potential for understanding physics of the seismogenic process as well as for obtaining detailed information about reservoirs at locations as far as several kilometers from boreholes. The phenomenon of microseismicity triggering by borehole fluid injections is related to the process of the Frenkel-Biot slow wave propagation. In the low-frequency range (hours or days of fluid injection duration) this process reduces to the pore pressure diffusion. Fluid induced seismicity typically shows several diffusion indicating features, which are directly related to the rate of spatial grow, to the geometry of clouds of micro earthquake hypocentres and to their spatial density. Several fluid injection experiments were conducted at the German Continental Deep Drilling Site (KTB) in 1994, 2000 and 2003-2005. Microseismicity occurred at different depth intervals. We analyze this microseismicity in terms of its diffusion-related features. Its relation to the 3-D distribution of the seismic reflectivity has important rock physical and tectonic implications. Starting from such diffusion-typical signatures of man-made earthquakes, we seek analogous patterns for the earthquakes in Vogtland/Bohemia at the German/Czech border region in central Europe. There is strong geophysical evidence that there seismic events are correlated to fluid-related processes in the crust. We test the hypothesis that ascending magmatic fluids trigger earthquakes by the mechanism of pore pressure diffusion. This triggering process is mainly controlled by two physical fields, the hydraulic diffusivity and the seismic criticality (i.e., critical pore pressure value leading to failure; stable locations are characterized by higher critical pressures), both heterogeneously distributed in rocks. The results of the analysis of the most significant and best studied (year 2000) earthquake swarm support this concept. Using a numerical model, where spatially correlated diffusivity and criticalit y patches (where patches with higher diffusivity are assumed to be less stable) are considered, we successfully simulate a general seismicity pattern of the swarms, including the spatio-temporal clustering of events and the migration of seismic activity. Therefore, in some cases spontaneously triggered natural seismicity, like earthquake swarms, also shows diffusion-typical signatures mentioned above. However, it seems that there are also some principle differences. They are emphasized in this presentation.

The forgotten face of regular physical exercise: a 'natural' anti-atherogenic activity.

PubMed

Szostak, Justyna; Laurant, Pascal

2011-08-01

Humans are not programmed to be inactive. The combination of both accelerated sedentary lifestyle and constant food availability disturbs ancient metabolic processes leading to excessive storage of energy in tissue, dyslipidaemia and insulin resistance. As a consequence, the prevalence of Type 2 diabetes, obesity and the metabolic syndrome has increased significantly over the last 30 years. A low level of physical activity and decreased daily energy expenditure contribute to the increased risk of cardiovascular morbidity and mortality following atherosclerotic vascular damage. Physical inactivity leads to the accumulation of visceral fat and consequently the activation of the oxidative stress/inflammation cascade, which promotes the development of atherosclerosis. Considering physical activity as a 'natural' programmed state, it is assumed that it possesses atheroprotective properties. Exercise prevents plaque development and induces the regression of coronary stenosis. Furthermore, experimental studies have revealed that exercise prevents the conversion of plaques into a vulnerable phenotype, thus preventing the appearance of fatal lesions. Exercise promotes atheroprotection possibly by reducing or preventing oxidative stress and inflammation through at least two distinct pathways. Exercise, through laminar shear stress activation, down-regulates endothelial AT1R (angiotensin II type 1 receptor) expression, leading to decreases in NADPH oxidase activity and superoxide anion production, which in turn decreases ROS (reactive oxygen species) generation, and preserves endothelial NO bioavailability and its protective anti-atherogenic effects. Contracting skeletal muscle now emerges as a new organ that releases anti-inflammatory cytokines, such as IL-6 (interleukin-6). IL-6 inhibits TNF-α (tumour necrosis factor-α) production in adipose tissue and macrophages. The down-regulation of TNF-α induced by skeletal-muscle-derived IL-6 may also participate in mediating the atheroprotective effect of physical activity.

Hurricane Gustav: Observations and Analysis of Coastal Change

USGS Publications Warehouse

Doran, Kara S.; Stockdon, Hilary F.; Plant, Nathaniel G.; Sallenger, Asbury H.; Guy, Kristy K.; Serafin, Katherine A.

2009-01-01

Understanding storm-induced coastal change and forecasting these changes require knowledge of the physical processes associated with a storm and the geomorphology of the impacted coastline. The primary physical processes of interest are the wind field, storm surge, currents, and wave field. Not only does wind cause direct damage to structures along the coast, but it is ultimately responsible for much of the energy that is transferred to the ocean and expressed as storm surge, mean currents, and surface waves. Waves and currents are the processes most responsible for moving sediments in the coastal zone during extreme storm events. Storm surge, which is the rise in water level due to the wind, barometric pressure, and other factors, allows both waves and currents to attack parts of the coast not normally exposed to these processes. Coastal geomorphology, including shapes of the shoreline, beaches, and dunes, is also a significant aspect of the coastal change observed during extreme storms. Relevant geomorphic variables include sand dune elevation, beach width, shoreline position, sediment grain size, and foreshore beach slope. These variables, in addition to hydrodynamic processes, can be used to predict coastal vulnerability to storms. The U.S. Geological Survey (USGS) National Assessment of Coastal Change Hazards project (http://coastal.er.usgs.gov/hurricanes) strives to provide hazard information to those concerned about the Nation's coastlines, including residents of coastal areas, government agencies responsible for coastal management, and coastal researchers. As part of the National Assessment, observations were collected to measure morphological changes associated with Hurricane Gustav, which made landfall near Cocodrie, Louisiana, on September 1, 2008. Methods of observation included oblique aerial photography, airborne topographic surveys, and ground-based topographic surveys. This report documents these data-collection efforts and presents qualitative and quantitative descriptions of hurricane-induced changes to the shoreline, beaches, dunes, and infrastructure in the region that was heavily impacted by Hurricane Gustav.

Biology-inspired AMO physics

NASA Astrophysics Data System (ADS)

Mathur, Deepak

2015-01-01

This Topical Review presents an overview of increasingly robust interconnects that are being established between atomic, molecular and optical (AMO) physics and the life sciences. AMO physics, outgrowing its historical role as a facilitator—a provider of optical methodologies, for instance—now seeks to partner biology in its quest to link systems-level descriptions of biological entities to insights based on molecular processes. Of course, perspectives differ when AMO physicists and biologists consider various processes. For instance, while AMO physicists link molecular properties and dynamics to potential energy surfaces, these have to give way to energy landscapes in considerations of protein dynamics. But there are similarities also: tunnelling and non-adiabatic transitions occur both in protein dynamics and in molecular dynamics. We bring to the fore some such differences and similarities; we consider imaging techniques based on AMO concepts, like 4D fluorescence microscopy which allows access to the dynamics of cellular processes, multiphoton microscopy which offers a built-in confocality, and microscopy with femtosecond laser beams to saturate the suppression of fluorescence in spatially controlled fashion so as to circumvent the diffraction limit. Beyond imaging, AMO physics contributes with optical traps that probe the mechanical and dynamical properties of single ‘live’ cells, highlighting differences between healthy and diseased cells. Trap methodologies have also begun to probe the dynamics governing of neural stem cells adhering to each other to form neurospheres and, with squeezed light to probe sub-diffusive motion of yeast cells. Strong field science contributes not only by providing a source of energetic electrons and γ-rays via laser-plasma accelerations schemes, but also via filamentation and supercontinuum generation, enabling mainstream collision physics into play in diverse processes like DNA damage induced by low-energy collisions to invoking dissociative attachment in quantification of stress levels in humans. The prognosis is extremely good for more intense interaction of AMO physics and biology; by way of future predictions attention is drawn to only two of very many opportunities for such interactions: application of attosecond techniques and tunnelling experiments to biological problems.

Linking Surface and Subsurface Processes: Implications for Seismic Hazards in Southern California

NASA Astrophysics Data System (ADS)

Lin, J. C.; Moon, S.; Yong, A.; Meng, L.; Martin, A. J.; Davis, P. M.

2017-12-01

Earth's surface and subsurface processes such as bedrock weathering, soil production, and river incision can influence and be influenced by spatial variations in the mechanical strength of surface material. Mechanically weakened rocks tend to have reduced seismic velocity, which can result in larger ground-motion amplification and greater potential for earthquake-induced damages. However, the influence and extent of surface and subsurface processes on the mechanical strength of surface material and seismic site conditions in southern California remain unclear. In this study, we examine whether physics-based models of surface and subsurface processes can explain the spatial variability and non-linearity of near-surface seismic velocity in southern California. We use geophysical measurements (Yong et al., 2013; Ancheta et al., 2014), consisting of shear-wave velocity (Vs) tomography data, Vs profiles, and the time-averaged Vs in the upper 30 m of the crust (Vs30) to infer lateral and vertical variations of surface material properties. Then, we compare Vs30 values with geologic and topographic attributes such as rock type, slope, elevation, and local relief, as well as metrics for surface processes such as soil production and bedrock weathering from topographic stress, frost cracking, chemical reactions, and vegetation presence. Results from this study will improve our understanding of physical processes that control subsurface material properties and their influences on local variability in seismic site conditions.

Of trophies and pillars: exploring the terror management functions of short-term and long-term relationship partners.

PubMed

Kosloff, Spee; Greenberg, Jeff; Sullivan, Daniel; Weise, David

2010-08-01

Prior terror management research shows that mortality salience (MS) motivates both self-esteem striving and worldview bolstering. The present research examined these processes in the context of dating preferences. It was hypothesized that in short-term romantic contexts, MS-induced self-esteem striving motivates interest in dating a physically attractive other, whereas in long-term romantic contexts, MS-induced motives for worldview validation heighten interest in dating a same-religion other. Study 1 showed that in a short-term dating context, MS increased preference for an attractive but religiously dissimilar person, whereas in a long-term dating context, MS increased preference for a religiously similar, less attractive person. Study 2 clarified that MS motivates preference for attractive short-term partners for their self-enhancing properties rather than their potential sexual availability. Study 3 supported the theorized processes, showing that under MS, self-esteem-relevant constructs became spontaneously accessible in short-term dating contexts, whereas worldview-relevant constructs became spontaneously accessible in long-term dating contexts.

Characteristics of Extreme Geoelectric Fields and Their Possible Causes: Localized Peak Enhancements

NASA Astrophysics Data System (ADS)

Pulkkinen, A. A.; Ngwira, C. M.; Bernabeu, E.; Eichner, J.; Viljanen, A.; Crowley, G.

2015-12-01

One of the major challenges pertaining to extreme geomagnetic storms is to understand the basic processes associated with the development of dynamic magnetosphere-ionosphere currents, which generate large induced surface geoelectric fields. Previous studies point out the existence of localized peak geoelectric field enhancements during extreme storms. We examined induced global geoelectric fields derived from ground-based magnetometer recordings for 12 extreme geomagnetic storms between the years 1982--2005. However for the present study, an in-depth analysis was performed for two important extreme storms, October 29, 2003 and March 13, 1989. The primary purpose of this paper is to provide further evidence on the existence of localized peak geoelectric field enhancements, and to show that the structure of the geoelectric field during these localized extremes at single sites can differ greatly from globally and regionally averaged fields. Although the physical processes that govern the development of these localized extremes are still not clear, we discuss some possible causes.

Rheological Characterization of Molten Polymer-Drug Dispersions as a Predictive Tool for Pharmaceutical Hot-Melt Extrusion Processability.

PubMed

Van Renterghem, Jeroen; Vervaet, Chris; De Beer, Thomas

2017-11-01

The aim of this study was to investigate (i) the influence of drug solid-state (crystalline or dissolved in the polymer matrix) on the melt viscosity and (ii) the influence of the drug concentration, temperature and shear rate on polymer crystallization using rheological tests. Poly (ethylene oxide) (PEO) (100.000 g/mol) and physical mixtures (PM) containing 10-20-30-40% (w/w) ketoprofen or 10% (w/w) theophylline in PEO were rheologically characterized. Rheological tests were performed (frequency and temperature sweeps in oscillatory shear as well as shear-induced crystallization experiments) to obtain a thorough understanding of the flow behaviour and crystallization of PEO-drug dispersions. Theophylline did not dissolve in PEO as the complex viscosity (η*) of the drug-polymer mixture increased as compared to that of neat PEO. In contrast, ketoprofen dissolved in PEO and acted as a plasticizer, decreasing η*. Acting as a nucleating agent, theophylline induced the crystallization of PEO upon cooling from the melt. On the other hand, ketoprofen inhibited crystallization upon cooling. Moreover, higher concentrations of ketoprofen in the drug-polymer mixture increasingly inhibited polymer crystallization. However, shear-induced crystallization was observed for all tested mixtures containing ketoprofen. The obtained rheological results are relevant for understanding and predicting HME processability (e.g., barrel temperature selection) and downstream processing such as injection moulding (e.g., mold temperature selection).

Tropical Atlantic climate response to different freshwater input in high latitudes with an ocean-only general circulation model

NASA Astrophysics Data System (ADS)

Men, Guang; Wan, Xiuquan; Liu, Zedong

2016-10-01

Tropical Atlantic climate change is relevant to the variation of Atlantic meridional overturning circulation (AMOC) through different physical processes. Previous coupled climate model simulation suggested a dipole-like SST structure cooling over the North Atlantic and warming over the South Tropical Atlantic in response to the slowdown of the AMOC. Using an ocean-only global ocean model here, an attempt was made to separate the total influence of various AMOC change scenarios into an oceanic-induced component and an atmospheric-induced component. In contrast with previous freshwater-hosing experiments with coupled climate models, the ocean-only modeling presented here shows a surface warming in the whole tropical Atlantic region and the oceanic-induced processes may play an important role in the SST change in the equatorial south Atlantic. Our result shows that the warming is partly governed by oceanic process through the mechanism of oceanic gateway change, which operates in the regime where freshwater forcing is strong, exceeding 0.3 Sv. Strong AMOC change is required for the gateway mechanism to work in our model because only when the AMOC is sufficiently weak, the North Brazil Undercurrent can flow equatorward, carrying warm and salty north Atlantic subtropical gyre water into the equatorial zone. This threshold is likely to be model-dependent. An improved understanding of these issues may have help with abrupt climate change prediction later.

Biological and physical controls on O2/Ar, Ar and pCO2 variability at the Western Antarctic Peninsula and in the Drake Passage

NASA Astrophysics Data System (ADS)

Eveleth, R.; Cassar, N.; Doney, S. C.; Munro, D. R.; Sweeney, C.

2017-05-01

Using simultaneous sub-kilometer resolution underway measurements of surface O2/Ar, total O2 and pCO2 from annual austral summer surveys in 2012, 2013 and 2014, we explore the impacts of biological and physical processes on the O2 and pCO2 system spatial and interannual variability at the Western Antarctic Peninsula (WAP). In the WAP, mean O2/Ar supersaturation was (7.6±9.1)% and mean pCO2 supersaturation was (-28±22)%. We see substantial spatial variability in O2 and pCO2 including sub-mesoscale/mesoscale variability with decorrelation length scales of 4.5 km, consistent with the regional Rossby radius. This variability is embedded within onshore-offshore gradients. O2 in the LTER grid region is driven primarily by biological processes as seen by the median ratio of the magnitude of biological oxygen (O2/Ar) to physical oxygen (Ar) supersaturation anomalies (%) relative to atmospheric equilibrium (2.6), however physical processes have a more pronounced influence in the southern onshore region of the grid where we see active sea-ice melting. Total O2 measurements should be interpreted with caution in regions of significant sea-ice formation and melt and glacial meltwater input. pCO2 undersaturation predominantly reflects biological processes in the LTER grid. In contrast we compare these results to the Drake Passage where gas supersaturations vary by smaller magnitudes and decorrelate at length scales of 12 km, in line with latitudinal changes in the regional Rossby radius. Here biological processes induce smaller O2/Ar supersaturations (mean (0.14±1.3)%) and pCO2 undersaturations (mean (-2.8±3.9)%) than in the WAP, and pressure changes, bubble and gas exchange fluxes drive stable Ar supersaturations.

The effects of fatigue on performance in simulated nursing work.

PubMed

Barker, Linsey M; Nussbaum, Maury A

2011-09-01

Fatigue is associated with increased rates of medical errors and healthcare worker injuries, yet existing research in this sector has not considered multiple dimensions of fatigue simultaneously. This study evaluated hypothesised causal relationships between mental and physical fatigue and performance. High and low levels of mental and physical fatigue were induced in 16 participants during simulated nursing work tasks in a laboratory setting. Task-induced changes in fatigue dimensions were quantified using both subjective and objective measures, as were changes in performance on physical and mental tasks. Completing the simulated work tasks increased total fatigue, mental fatigue and physical fatigue in all experimental conditions. Higher physical fatigue adversely affected measures of physical and mental performance, whereas higher mental fatigue had a positive effect on one measure of mental performance. Overall, these results suggest causal effects between manipulated levels of mental and physical fatigue and task-induced changes in mental and physical performance. STATEMENT OF RELEVANCE: Nurse fatigue and performance has implications for patient and provider safety. Results from this study demonstrate the importance of a multidimensional view of fatigue in understanding the causal relationships between fatigue and performance. The findings can guide future work aimed at predicting fatigue-related performance decrements and designing interventions.

Light driven mesoscale assembly of a coordination polymeric gelator into flowers and stars with distinct properties.

PubMed

Mukhopadhyay, Rahul Dev; Praveen, Vakayil K; Hazra, Arpan; Maji, Tapas Kumar; Ajayaghosh, Ayyappanpillai

2015-11-13

Control over the self-assembly process of porous organic-inorganic hybrids often leads to unprecedented polymorphism and properties. Herein we demonstrate how light can be a powerful tool to intervene in the kinetically controlled mesoscale self-assembly of a coordination polymeric gelator. Ultraviolet light induced coordination modulation via photoisomerisation of an azobenzene based dicarboxylate linker followed by aggregation mediated crystal growth resulted in two distinct morphological forms (flowers and stars), which show subtle differences in their physical properties.

Numerical simulation of the early-time high altitude electromagnetic pulse

NASA Astrophysics Data System (ADS)

Meng, Cui; Chen, Yu-Sheng; Liu, Shun-Kun; Xie, Qin-Chuan; Chen, Xiang-Yue; Gong, Jian-Cheng

2003-12-01

In this paper, the finite difference method is used to develop the Fortran software MCHII. The physical process in which the electromagnetic signal is generated by the interaction of nuclear-explosion-induced Compton currents with the geomagnetic field is numerically simulated. The electromagnetic pulse waveforms below the burst point are investigated. The effects of the height of burst, yield and the time-dependence of gamma-rays are calculated by using the MCHII code. The results agree well with those obtained by using the code CHAP.

Acute stress affects prospective memory functions via associative memory processes.

PubMed

Szőllősi, Ágnes; Pajkossy, Péter; Demeter, Gyula; Kéri, Szabolcs; Racsmány, Mihály

2018-01-01

Recent findings suggest that acute stress can improve the execution of delayed intentions (prospective memory, PM). However, it is unclear whether this improvement can be explained by altered executive control processes or by altered associative memory functioning. To investigate this issue, we used physical-psychosocial stressors to induce acute stress in laboratory settings. Then participants completed event- and time-based PM tasks requiring the different contribution of control processes and a control task (letter fluency) frequently used to measure executive functions. According to our results, acute stress had no impact on ongoing task performance, time-based PM, and verbal fluency, whereas it enhanced event-based PM as measured by response speed for the prospective cues. Our findings indicate that, here, acute stress did not affect executive control processes. We suggest that stress affected event-based PM via associative memory processes. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of microwave argon plasma on the glycosidic and hydrogen bonding system of cotton cellulose.

PubMed

Prabhu, S; Vaideki, K; Anitha, S

2017-01-20

Cotton fabric was processed with microwave (Ar) plasma to alter its hydrophilicity. The process parameters namely microwave power, process gas pressure and processing time were optimized using Box-Behnken method available in the Design Expert software. It was observed that certain combinations of process parameters improved existing hydrophilicity while the other combinations decreased it. ATR-FTIR spectral analysis was used to identify the strain induced in inter chain, intra chain, and inter sheet hydrogen bond and glycosidic covalent bond due to plasma treatment. X-ray diffraction (XRD) studies was used to analyze the effect of plasma on unit cell parameters and degree of crystallinity. Fabric surface etching was identified using FESEM analysis. Thus, it can be concluded that the increase/decrease in the hydrophilicity of the plasma treated fabric was due to these structural and physical changes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Monolithic Active Pixel Sensors (MAPS) in a Quadruple Well Technology for Nearly 100% Fill Factor and Full CMOS Pixels.

PubMed

Ballin, Jamie Alexander; Crooks, Jamie Phillip; Dauncey, Paul Dominic; Magnan, Anne-Marie; Mikami, Yoshiari; Miller, Owen Daniel; Noy, Matthew; Rajovic, Vladimir; Stanitzki, Marcel; Stefanov, Konstantin; Turchetta, Renato; Tyndel, Mike; Villani, Enrico Giulio; Watson, Nigel Keith; Wilson, John Allan

2008-09-02

In this paper we present a novel, quadruple well process developed in a modern 0.18 mm CMOS technology called INMAPS. On top of the standard process, we have added a deep P implant that can be used to form a deep P-well and provide screening of N-wells from the P-doped epitaxial layer. This prevents the collection of radiation-induced charge by unrelated N-wells, typically ones where PMOS transistors are integrated. The design of a sensor specifically tailored to a particle physics experiment is presented, where each 50 mm pixel has over 150 PMOS and NMOS transistors. The sensor has been fabricated in the INMAPS process and first experimental evidence of the effectiveness of this process on charge collection is presented, showing a significant improvement in efficiency.

Δ L =3 processes: Proton decay and the LHC

NASA Astrophysics Data System (ADS)

Fonseca, Renato M.; Hirsch, Martin; Srivastava, Rahul

2018-04-01

We discuss lepton number violation in three units. From an effective field theory point of view, Δ L =3 processes can only arise from dimension 9 or higher operators. These operators also violate baryon number, hence many of them will induce proton decay. Given the high dimensionality of these operators, in order to have a proton half-life in the observable range, the new physics associated to Δ L =3 processes should be at a scale as low as 1 TeV. This opens up the possibility of searching for such processes not only in proton decay experiments but also at the LHC. In this work we analyze the relevant d =9 , 11, 13 operators which violate lepton number in three units. We then construct one simple concrete model with interesting low- and high-energy phenomenology.

Alcohol-induced physiological displacements and their effects on flight-related functions.

DOT National Transportation Integrated Search

1982-03-01

Tolerances of human subjects for orthostasis and physical work were determined at a simulated altitude of 3,048 m. Orthostasis was induced with a lower body negative pressure (LBNP) device and physical work was done on a pedal ergometer. Altitude was...

Forecasting induced seismicity rate and Mmax using calibrated numerical models

NASA Astrophysics Data System (ADS)

Dempsey, D.; Suckale, J.

2016-12-01

At Groningen, The Netherlands, several decades of induced seismicity from gas extraction has culminated in a M 3.6 event (mid 2012). From a public safety and commercial perspective, it is desirable to anticipate future seismicity outcomes at Groningen. One way to quantify earthquake risk is Probabilistic Seismic Hazard Analysis (PSHA), which requires an estimate of the future seismicity rate and its magnitude frequency distribution (MFD). This approach is effective at quantifying risk from tectonic events because the seismicity rate, once measured, is almost constant over timescales of interest. In contrast, rates of induced seismicity vary significantly over building lifetimes, largely in response to changes in injection or extraction. Thus, the key to extending PSHA to induced earthquakes is to estimate future changes of the seismicity rate in response to some proposed operating schedule. Numerical models can describe the physical link between fluid pressure, effective stress change, and the earthquake process (triggering and propagation). However, models with predictive potential of individual earthquakes face the difficulty of characterizing specific heterogeneity - stress, strength, roughness, etc. - at locations of interest. Modeling catalogs of earthquakes provides a means of averaging over this uncertainty, focusing instead on the collective features of the seismicity, e.g., its rate and MFD. The model we use incorporates fluid pressure and stress changes to describe nucleation and crack-like propagation of earthquakes on stochastically characterized 1D faults. This enables simulation of synthetic catalogs of induced seismicity from which the seismicity rate, location and MFD are extracted. A probability distribution for Mmax - the largest event in some specified time window - is also computed. Because the model captures the physics linking seismicity to changes in the reservoir, earthquake observations and operating information can be used to calibrate a model at a specific site (or, ideally, many models). This restricts analysis of future seismicity to likely parameter sets and provides physical justification for linking operational changes to subsequent seismicity. To illustrate these concepts, a recent study of prior and forecast seismicity at Groningen will be presented.

Femtosecond laser-induced cell-cell surgical attachment.

PubMed

Katchinskiy, Nir; Godbout, Roseline; Goez, Helly R; Elezzabi, Abdulhakem Y

2014-04-01

Laser-induced cell-cell surgical attachment using femtosecond laser pulses is reported. We have demonstrated the ability to attach single cells using sub-10 femtosecond laser pulses, with 800 nm central wavelength delivered from a Ti:Sapphire laser. To check that the cells did not go through a cell-fusion process, a fluorescent dye Calcein AM was used to verify that the fluorescent dye did not migrate from a dyed cell to a non-dyed cell. The mechanical integrity of the attached joint was assessed using an optical tweezer. Attachment of cells was performed without the induction of cell-cell fusion, with attachment efficiency of 95%, and while preserving the cells' viability. Cell-cell attachment was achieved by delivery of one to two trains of femtosecond laser pulses lasting 15 ms each. Laser-induced ionization process led to an ultrafast reversible destabilization of the phospholipid layer of the cellular membrane. The inner cell membrane remained intact during the attachment procedure, and isolation of the cells' cytoplasm from the surrounding medium was obtained. A strong physical attachment between the cells was obtained due to the bonding of the membranes' ionized phospholipid molecules and the formation of a joint cellular membrane at the connection point. The cellular attachment technique, femtosecond laser-induced cell-cell surgical attachment, can potentially provide a platform for the creation of engineered tissue and cell cultures. © 2014 Wiley Periodicals, Inc.

The role of physiology in the development of golf performance.

PubMed

Smith, Mark F

2010-08-01

The attainment of consistent high performance in golf requires effective physical conditioning that is carefully designed and monitored in accordance with the on-course demands the player will encounter. Appreciating the role that physiology plays in the attainment of consistent performance, and how a player's physicality can inhibit performance progression, supports the notion that the application of physiology is fundamental for any player wishing to excel in golf. With cardiorespiratory, metabolic, hormonal, musculoskeletal and nutritional demands acting on the golfer within and between rounds, effective physical screening of a player will ensure physiological and anatomical deficiencies that may influence performance are highlighted. The application of appropriate golf-specific assessment methods will ensure that physical attributes that have a direct effect on golf performance can be measured reliably and accurately. With the physical development of golf performance being achieved through a process of conditioning with the purpose of inducing changes in structural and metabolic functions, training must focus on foundation whole-body fitness and golf-specific functional strength and flexibility activities. For long-term player improvement to be effective, comprehensive monitoring will ensure the player reaches an optimal physical state at predetermined times in the competitive season. Through continual assessment of a player's physical attributes, training effectiveness and suitability, and the associated adaptive responses, key physical factors that may impact most on performance success can be determined.

A time-lagged momentary assessment study on daily life physical activity and affect.

PubMed

Wichers, Marieke; Peeters, Frenk; Rutten, Bart P F; Jacobs, Nele; Derom, Catherine; Thiery, Evert; Delespaul, Philippe; van Os, Jim

2012-03-01

Novel study designs using within-subject methodology and frequent and prospective measurements are required to unravel direction of causality and dynamic processes of behavior over time. The current study examined the effects of physical activity on affective state. A primary and within-study replication sample was derived from twin pairs. Female twins (n = 504) participated in an experience sampling method study at baseline. Positive and negative affective changes were examined before and following daily life increases in physical activity. Neuroticism was measured at baseline and depressive symptoms were assessed at baseline and at each of four follow-up assessments. Diagnoses, derived by Structured Clinical Interview for Diagnostic and Statistical Manual for Mental Health-IV axis I disorders, (A. P. A., 1994) were obtained at baseline. A significant increase in positive affect (PA) following the moment of increase in physical activity was replicated across both samples up to 180 min after physical activity. There was no effect of physical activity on negative affect (NA). Across the two samples, a history of fulfilling diagnostic criteria for depression at least once moderated the effect of physical activity on PA, in that the effect was lost more rapidly. The study supports a causal effect of physical activity on PA. However, people with past experience of clinical depression may benefit less from the PA-inducing effect of physical activity. These findings have implications for the use of physical exercise in clinical practice.

FNDC5/irisin, a molecular target for boosting reward-related learning and motivation.

PubMed

Zsuga, Judit; Tajti, Gabor; Papp, Csaba; Juhasz, Bela; Gesztelyi, Rudolf

2016-05-01

Interventions focusing on the prevention and treatment of chronic non-communicable diseases are on rise. In the current article, we propose that dysfunction of the mesocortico-limbic reward system contributes to the emergence of the WHO-identified risk behaviors (tobacco use, unhealthy diet, physical inactivity and harmful use of alcohol), behaviors that underlie the evolution of major non-communicable diseases (e.g. cardiovascular diseases, cancer, diabetes and chronic respiratory diseases). Given that dopaminergic neurons of the mesocortico-limbic system are tightly associated with reward-related processes and motivation, their dysfunction may fundamentally influence behavior. While nicotine and alcohol alter dopamine neuron function by influencing some receptors, mesocortico-limbic system dysfunction was associated with elevation of metabolic set-point leading to hedonic over-eating. Although there is some empirical evidence, precise molecular mechanism for linking physical inactivity and mesocortico-limbic dysfunction per se seems to be missing; identification of which may contribute to higher success rates for interventions targeting lifestyle changes pertaining to physical activity. In the current article, we compile evidence in support of a link between exercise and the mesocortico-limbic system by elucidating interactions on the axis of muscle - irisin - brain derived neurotrophic factor (BDNF) - and dopaminergic function of the midbrain. Irisin is a contraction-regulated myokine formed primarily in skeletal muscle but also in the brain. Irisin stirred considerable interest, when its ability to induce browning of white adipose tissue parallel to increasing thermogenesis was discovered. Furthermore, it may also play a role in the regulation of behavior given it readily enters the central nervous system, where it induces BDNF expression in several brain areas linked to reward processing, e.g. the ventral tegmental area and the hippocampus. BDNF is a neurotropic factor that increases neuronal dopamine content, modulates dopamine release relevant for neuronal plasticity and increased neuronal survival as well as learning and memory. Further linking BDNF to dopaminergic function is BDNF's ability to activate tropomyosin-related kinase B receptor that shares signalization with presynaptic dopamine-3 receptors in the ventral tegmental area. Summarizing, we propose that the skeletal muscle derived irisin may be the link between physical activity and reward-related processes and motivation. Moreover alteration of this axis may contribute to sedentary lifestyle and subsequent non-communicable diseases. Preclinical and clinical experimental models to test this hypothesis are also proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of technetium-99m decay on Escherichia coli inactivation: effects of physical or chemical agents.

PubMed Central

Silva, C. R.; Valsa, J. O.; Caniné, M. S.; Caldeira-de-Araújo, A.; Bernardo-Filho, M.

1998-01-01

Technetium-99m (99mTc) has been used in nuclear medicine and in biomedical research to label molecular and cellular structures employed as radiotracers. Here, we have evaluated, on a DNA repair proficient Escherichia coli strain, the 99mTc decay inactivation and the influence of the (i) pre-treatment with metal ion chelators or of the (ii) treatment with a free radical scavenger on the protection of the cells against the lethal effect of the 99mTc. As SnCl2 is frequently used as a reducing agent in the 99mTc-labeling process, we have also studied the capability of SnCl2 to alter the biological effects induced by the 99mTc decay. As we are exposed to either chemical or physical agents in the nature, we have decided to study a possible influence of the ultraviolet solar radiation in the biological phenomena induced by the 99mTc decay. Our data point out (i) a very important role of the Auger and/or conversion electrons in the cytotoxicity induced by the 99mTc decay; (ii) SnCl2, the metal ion chelators and the free radical scavenger protect the cells against the lethal effect of the 99mTc; and (iii) near-UV does not alter the lethal effect of the 99mTc decay. PMID:9713950

Physical exercise induces structural alterations in the hippocampal astrocytes: exploring the role of BDNF-TrkB signaling.

PubMed

Fahimi, Atoossa; Baktir, Mehmet Akif; Moghadam, Sarah; Mojabi, Fatemeh S; Sumanth, Krithika; McNerney, M Windy; Ponnusamy, Ravikumar; Salehi, Ahmad

2017-05-01

While it has been known that physical activity can improve cognitive function and protect against neurodegeneration, the underlying mechanisms for these protective effects are yet to be fully elucidated. There is a large body of evidence indicating that physical exercise improves neurogenesis and maintenance of neurons. Yet, its possible effects on glial cells remain poorly understood. Here, we tested whether physical exercise in mice alters the expression of trophic factor-related genes and the status of astrocytes in the dentate gyrus of the hippocampus. In addition to a significant increase in Bdnf mRNA and protein levels, we found that 4 weeks of treadmill and running wheel exercise in mice, led to (1) a significant increase in synaptic load in the dentate gyrus, (2) alterations in astrocytic morphology, and (3) orientation of astrocytic projections towards dentate granule cells. Importantly, these changes were possibly linked to increased TrkB receptor levels in astrocytes. Our study suggests that astrocytes actively respond and could indeed mediate the positive effects of physical exercise on the central nervous system and potentially counter degenerative processes during aging and neurodegenerative disorders.

Surgical treatment is effective in severe cases of exercise-induced laryngeal obstruction: A follow-up study.

PubMed

Norlander, Katarina; Johansson, Henrik; Jansson, Christer; Nordvall, Lennart; Nordang, Leif

2015-01-01

Surgery is an effective treatment in severe cases of supraglottic exercise-induced laryngeal obstruction (E-ILO). Conservatively treated subjects and subjects tested negative for E-ILO, who still experience breathing problems 1-3 years after diagnosis, tend to adjust their physical activity to a greater extent than surgically treated subjects. To investigate how symptoms and level of physical activity change over time in patients with E-ILO who have undergone surgery, patients with E-ILO treated conservatively and patients who tested negative for laryngeal obstruction at continuous laryngoscopy exercise-test (CLE-test). Patients referred for exercise-induced breathing difficulties answered questionnaires at diagnostic CLE-test and at follow-up. Questions regarded exercise-induced breathing problems, current physical activity level, and medical history of asthma and perennial allergy. Out of 84 invited subjects, 59 (70%) answered both questionnaires. Surgically treated subjects had less breathing problems at follow-up compared with conservatively treated subjects and subjects who tested negative (p < 0.001). None of the surgically treated subjects were less physically active or had changed sport due to exercise-induced dyspnoea, whereas 41.7% of the conservatively treated subjects had made such adjustments (p < 0.001).

Effects of Lightning in the Upper Atmosphere

NASA Astrophysics Data System (ADS)

Sentman, Davis D.; Pasko, Victor P.; Morrill, Jeff S.

2010-02-01

AGU Chapman Conference on Effects of Thunderstorms and Lightning in the Upper Atmosphere; University Park, Pennsylvania, 10-14 May 2009; The serendipitous observation in 1989 of electrical discharge in the high atmosphere induced by thundercloud lightning launched a new field of geophysical investigation. From this single unexpected observation sprang a vigorous and fertile new research field that simultaneously encompasses geophysical disciplines that are normally pursued independently, such as meteorology and lightning, plasma and gas discharge physics, atmospheric chemistry, ionospheric physics, and energetic particle physics. Transient electrical discharge in the upper atmosphere spans the full range of altitudes between the tropopause and the ionosphere and takes a variety of forms that carry the whimsical names red sprites, blue jets, gigantic jets, elves (emissions of light and very low frequency perturbations from electromagnetic pulse sources), and sprite halos, collectively known as transient luminous events (TLEs). To date, TLEs have been observed from ground and airborne or spaceborne platforms above thunderstorm systems worldwide, and radio observations made concomitantly with optical observations have shown that they are produced by the transient far fields of thundercloud lightning. TLEs appear to be large-scale (tens of kilometers in dimension), upper atmospheric versions of conventional gas discharge akin to weakly ionized, collision-dominated systems found in laboratory discharge devices (millimeter-centimeter dimensions), with characteristic energies of a few electron volts. The dominant physical processes have been identified as described by the familiar kinetic theory of the photochemistry of the upper atmosphere, but with electric field-driven electron impact ionization playing the role of photolysis or energetic precipitating particle-induced ionization.

Insight into nuclear body formation of phytochromes through stochastic modelling and experiment.

PubMed

Grima, Ramon; Sonntag, Sebastian; Venezia, Filippo; Kircher, Stefan; Smith, Robert W; Fleck, Christian

2018-05-01

Spatial relocalization of proteins is crucial for the correct functioning of living cells. An interesting example of spatial ordering is the light-induced clustering of plant photoreceptor proteins. Upon irradiation by white or red light, the red light-active phytochrome, phytochrome B, enters the nucleus and accumulates in large nuclear bodies. The underlying physical process of nuclear body formation remains unclear, but phytochrome B is thought to coagulate via a simple protein-protein binding process. We measure, for the first time, the distribution of the number of phytochrome B-containing nuclear bodies as well as their volume distribution. We show that the experimental data cannot be explained by a stochastic model of nuclear body formation via simple protein-protein binding processes using physically meaningful parameter values. Rather modelling suggests that the data is consistent with a two step process: a fast nucleation step leading to macroparticles followed by a subsequent slow step in which the macroparticles bind to form the nuclear body. An alternative explanation for the observed nuclear body distribution is that the phytochromes bind to a so far unknown molecular structure. We believe it is likely this result holds more generally for other nuclear body-forming plant photoreceptors and proteins. Creative Commons Attribution license.

Improvement of Processing Speed in Executive Function Immediately following an Increase in Cardiovascular Activity.

PubMed

Tam, Nicoladie D

2013-01-01

This study aims to identify the acute effects of physical exercise on specific cognitive functions immediately following an increase in cardiovascular activity. Stair-climbing exercise is used to increase the cardiovascular output of human subjects. The color-naming Stroop Test was used to identify the cognitive improvements in executive function with respect to processing speed and error rate. The study compared the Stroop results before and immediately after exercise and before and after nonexercise, as a control. The results show that there is a significant increase in processing speed and a reduction in errors immediately after less than 30 min of aerobic exercise. The improvements are greater for the incongruent than for the congruent color tests. This suggests that physical exercise induces a better performance in a task that requires resolving conflict (or interference) than a task that does not. There is no significant improvement for the nonexercise control trials. This demonstrates that an increase in cardiovascular activity has significant acute effects on improving the executive function that requires conflict resolution (for the incongruent color tests) immediately following aerobic exercise more than similar executive functions that do not require conflict resolution or involve the attention-inhibition process (for the congruent color tests).

Obesity associated behavior in adolescents of private schools in Lebanon.

PubMed

Salameh, Pascale; Barbour, Bernadette; Issa, Carine; Rachidi, Samar

2011-01-01

Since adolescence obesity is becoming an international concern, our objective was to evaluate obesity-related behavior in Lebanese adolescents. We performed a cross-sectional study in 19 Lebanese private schools, using a random multistage cluster sampling process. Dietary and physical activity behaviors were assessed in 1933 adolescents aged 12 to 18 years, stressing on differences between boys and girls and obesity categories. We found that boys were more obese than girls (72% versus 3.7% ; p < 0.001); they were less likely to adopt dietary behaviors that maintain or increase weight, such as eating lighter food (13.1% versus 20.9% ; p < 0.001). However, girls were less likely to perform physical activity (81% versus 71%; p < 0.001). Our results are similar to those of other researchers. In this sample of Lebanese adolescents, dietary and physical activity behaviors differed between boys and girls ; these differences could explain their obesity rates. Educational and participative scholar interventions are necessary to induce changes in adolescents' behavior, stressing on physical activity for girls and healthier eating for boys.

Recent developments for realistic solar models

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

Serenelli, Aldo M.

2014-05-02

The 'solar abundance problem' has triggered a renewed interest in revising the concept of SSM from different perspectives: 1) constituent microphysics: equation of state, nuclear rates, radiative opacities; 2) constituent macrophysics: the physical processes impact the evolution of the Sun and its present-day structure, e.g. dynamical processes induced by rotation, presence of magnetic fields; 3) challenge the hypothesis that the young Sun was chemically homogeneous: the possible interaction of the young Sun with its protoplanetary disk. Here, I briefly review and then present a (personal) view on recent advances and developments on solar modeling, part of them carried out asmore » attempts to solve the solar abundance problem.« less

Phenomena induced by charged particle beams. [experimental design for Spacelab

NASA Technical Reports Server (NTRS)

Beghin, C.

1981-01-01

The injection of energetic particles along the Earth's magnetic field lines is a possible remote sensing method for measuring the electric fields parallel to the magnetic field with good time resolution over the entire magnetic field. Neutralization processes, return-current effects, dynamics of the beams, triggered instabilities, and waves must be investigated before the fundamental question about proper experimental conditions, such as energy, intensity and divergence of the beams, pitch-angle injection, ion species, proper probes and detectors and their location, and rendezvous conditions, can be resolved. An experiment designed to provide a better understanding of these special physical processes and to provide some answers to questions concerning beam injection techniques is described.

Buddha as an Eye Opener: A Link between Prosocial Attitude and Attentional Control.

PubMed

Colzato, Lorenza S; Hommel, Bernhard; van den Wildenberg, Wery P M; Hsieh, Shulan

2010-01-01

Increasing evidence suggests that religious practice induces systematic biases in attentional control. We used Navon's global-local task to compare attentional bias in Taiwanese Zen Buddhists and Taiwanese atheists; two groups brought up in the same country and culture and matched with respect to race, intelligence, sex, and age. Given the Buddhist emphasis on compassion for the physical and social environment, we expected a more global bias in Buddhist than in Atheist participants. In line with these expectations, Buddhists showed a larger global-precedence effect and increased interference from global distracters when processing local information. This pattern reinforces the idea that people's attentional processing style reflects biases rewarded by their religious practices.

Fluid Physics and Macromolecular Crystal Growth in Microgravity

NASA Technical Reports Server (NTRS)

Pusey, M.; Snell, E.; Judge, R.; Chayen, N.; Boggon, T.; Helliwell, J.; Rose, M. Franklin (Technical Monitor)

2000-01-01

The molecular structure of biological macromolecules is important in understanding how these molecules work and has direct application to rational drug design for new medicines and for the improvement and development of industrial enzymes. In order to obtain the molecular structure, large, well formed, single macromolecule crystals are required. The growth of macromolecule crystals is a difficult task and is often hampered on the ground by fluid flows that result from the interaction of gravity with the crystal growth process. One such effect is the bulk movement of the crystal through the fluid due to sedimentation. A second is buoyancy driven convection close to the crystal surface. On the ground the crystallization process itself induces both of these flows.

Modelling periodic structure formation on 100Cr6 steel after irradiation with femtosecond-pulsed laser beams

NASA Astrophysics Data System (ADS)

Tsibidis, George D.; Mimidis, Alexandros; Skoulas, Evangelos; Kirner, Sabrina V.; Krüger, Jörg; Bonse, Jörn; Stratakis, Emmanuel

2018-01-01

We investigate the periodic structure formation upon intense femtosecond pulsed irradiation of chrome steel (100Cr6) for linearly polarised laser beams. The underlying physical mechanism of the laser-induced periodic structures is explored, their spatial frequency is calculated and theoretical results are compared with experimental observations. The proposed theoretical model comprises estimations of electron excitation, heat transfer, relaxation processes, and hydrodynamics-related mass transport. Simulations describe the sequential formation of sub-wavelength ripples and supra-wavelength grooves. In addition, the influence of the laser wavelength on the periodicity of the structures is discussed. The proposed theoretical investigation offers a systematic methodology towards laser processing of steel surfaces with important applications.

Self-Paced Physics, Segments 37-40.

ERIC Educational Resources Information Center

New York Inst. of Tech., Old Westbury.

Four study segments of the Self-Paced Physics Course materials are presented in this eighth problems and solutions book used as a part of course assignments. The content is related to magnetic induction, Faraday's law, induced currents, Lenz's law, induced electromotive forces, time-varying magnetic fields, self-inductance, inductors,…

Helping Students to Think Like Scientists in Socratic Dialogue-Inducing Labs

ERIC Educational Resources Information Center

Hake, Richard

2012-01-01

Socratic dialogue-inducing (SDI) labs are based on Arnold Arons' half-century of ethnographic research, listening carefully to students' responses to probing Socratic questions on physics, science, and ways of thinking, and culminating in his landmark "Teaching Introductory Physics." They utilize "interactive engagement" methods and are designed,…

Marine fog: a review

USGS Publications Warehouse

Koračin, Darko; Dorman, Clive E.; Lewis, John M.; Hudson, James G.; Wilcox, Eric M.; Torregrosa, Alicia

2014-01-01

The objective of this review is to discuss physical processes over a wide range of spatial scales that govern the formation, evolution, and dissipation of marine fog. We consider marine fog as the collective combination of fog over the open sea along with coastal sea fog and coastal land fog. The review includes a history of sea fog research, field programs, forecasting methods, and detection of sea fog via satellite observations where similarity in radiative properties of fog top and the underlying sea induce further complexity. The main thrust of the study is to provide insight into causality of fog including its initiation, maintenance, and destruction. The interplay between the various physical processes behind the several stages of marine fog is among the most challenging aspects of the problem. An effort is made to identify this interplay between processes that include the microphysics of fog formation and maintenance, the influence of large-scale circulation and precipitation/clouds, radiation, turbulence (air-sea interaction), and advection. The environmental impact of marine fog is also addressed. The study concludes with an assessment of our current knowledge of the phenomenon, our principal areas of ignorance, and future lines of research that hold promise for advances in our understanding.

Process and application of shock compression by nanosecond pulses of frequency-doubled Nd:YAG laser

NASA Astrophysics Data System (ADS)

Sano, Yuji; Kimura, Motohiko; Mukai, Naruhiko; Yoda, Masaki; Obata, Minoru; Ogisu, Tatsuki

2000-02-01

The authors have developed a new process of laser-induced shock compression to introduce a residual compressive stress on material surface, which is effective for prevention of stress corrosion cracking (SCC) and enhancement of fatigue strength of metal materials. The process developed is unique and beneficial. It requires no pre-conditioning for the surface, whereas the conventional process requires that the so-called sacrificial layer is made to protect the surface from damage. The new process can be freely applied to water- immersed components, since it uses water-penetrable green light of a frequency-doubled Nd:YAG laser. The process developed has the potential to open up new high-power laser applications in manufacturing and maintenance technologies. The laser-induced shock compression process (LSP) can be used to improve a residual stress field from tensile to compressive. In order to understand the physics and optimize the process, the propagation of a shock wave generated by the impulse of laser irradiation and the dynamic response of the material were analyzed by time-dependent elasto-plastic calculations with a finite element program using laser-induced plasma pressure as an external load. The analysis shows that a permanent strain and a residual compressive stress remain after the passage of the shock wave with amplitude exceeding the yield strength of the material. A practical system materializing the LSP was designed, manufactured, and tested to confirm the applicability to core components of light water reactors (LWRs). The system accesses the target component and remotely irradiates laser pulses to the heat affected zone (HAZ) along weld lines. Various functional tests were conducted using a full-scale mockup facility, in which remote maintenance work in a reactor vessel could be simulated. The results showed that the system remotely accessed the target weld lines and successfully introduced a residual compressive stress. After sufficient training for operational personnel, the system was applied to the core shroud of an existing nuclear power plant.

The interplay between biological and physical scenarios of bacterial death induced by non-thermal plasma.

PubMed

Lunov, Oleg; Zablotskii, Vitalii; Churpita, Olexander; Jäger, Ales; Polívka, Leoš; Syková, Eva; Dejneka, Alexandr; Kubinová, Šárka

2016-03-01

Direct interactions of plasma matter with living cells and tissues can dramatically affect their functionality, initiating many important effects from cancer elimination to bacteria deactivation. However, the physical mechanisms and biochemical pathways underlying the effects of non-thermal plasma on bacteria and cell fate have still not been fully explored. Here, we report on the molecular mechanisms of non-thermal plasma-induced bacteria inactivation in both Gram-positive and Gram-negative strains. We demonstrate that depending on the exposure time plasma induces either direct physical destruction of bacteria or triggers programmed cell death (PCD) that exhibits characteristic features of apoptosis. The interplay between physical disruption and PCD is on the one hand driven by physical plasma parameters, and on the other hand by biological and physical properties of bacteria. The explored possibilities of the tuneable bacteria deactivation provide a basis for the development of advanced plasma-based therapies. To a great extent, our study opens new possibilities for controlled non-thermal plasma interactions with living systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

Load-induced modulation of signal transduction networks.

PubMed

Jiang, Peng; Ventura, Alejandra C; Sontag, Eduardo D; Merajver, Sofia D; Ninfa, Alexander J; Del Vecchio, Domitilla

2011-10-11

Biological signal transduction networks are commonly viewed as circuits that pass along information--in the process amplifying signals, enhancing sensitivity, or performing other signal-processing tasks--to transcriptional and other components. Here, we report on a "reverse-causality" phenomenon, which we call load-induced modulation. Through a combination of analytical and experimental tools, we discovered that signaling was modulated, in a surprising way, by downstream targets that receive the signal and, in doing so, apply what in physics is called a load. Specifically, we found that non-intuitive changes in response dynamics occurred for a covalent modification cycle when load was present. Loading altered the response time of a system, depending on whether the activity of one of the enzymes was maximal and the other was operating at its minimal rate or whether both enzymes were operating at submaximal rates. These two conditions, which we call "limit regime" and "intermediate regime," were associated with increased or decreased response times, respectively. The bandwidth, the range of frequency in which the system can process information, decreased in the presence of load, suggesting that downstream targets participate in establishing a balance between noise-filtering capabilities and a circuit's ability to process high-frequency stimulation. Nodes in a signaling network are not independent relay devices, but rather are modulated by their downstream targets.

Properties of WZ21 (%wt) alloy processed by a powder metallurgy route.

PubMed

Cabeza, Sandra; Garcés, Gerardo; Pérez, Pablo; Adeva, Paloma

2015-06-01

Microstructure, mechanical properties and corrosion behaviour of WZ21 (%wt) alloy prepared by a powder metallurgy route from rapidly solidified powders have been studied. Results were compared to those of the same alloy prepared through a conventional route of casting and extrusion. The microstructure of the extruded ingot consisted of α-Mg grains and Mg3Zn3Y2 (W-phase) and LPSO-phase particles located at grain boundaries. Moreover, stacking faults were also observed within α-Mg grains. The alloy processed by the powder metallurgy route exhibited a more homogeneous and finer microstructure, with a grain size of 2 μm. In this case W-phase and Mg24Y5 phase were identified, but not the LPSO-phase. The microstructural refinement induced by the use of rapidly solidified powders strengthened the alloy at room temperature and promoted superplasticity at higher strain rates. Corrosion behaviour in PBS medium evidenced certain physical barrier effect of the almost continuous arrangements of second phases aligned along the extrusion direction in conventionally processed WZ21 alloy, with a stable tendency around 7 mm/year. On the other hand, powder metallurgy processing promoted significant pitting corrosion, inducing accelerated corrosion rate during prolonged immersion times. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chromatographic matrix based on hydrogel-coated reticulated polyurethane foams, prepared by gamma irradiation

NASA Astrophysics Data System (ADS)

Sánchez, Mirna L.; Giménez, Claudia Y.; Delgado, Juan F.; Martínez, Leandro J.; Grasselli, Mariano

2017-12-01

Novel chromatographic materials for protein purification with high adsorption capacity and fouling resistance are highly demanded to improve downstream processes. Here, we describe a novel adsorptive material based on reticulated polyurethane foam (rPUF) coated with a functional hydrogel layer. rPUF provides physical rigidity through its macroscopic structure, whereas the hydrogel layer provides capacity to adsorb proteins by specific interactions. The hydrogel coating process was performed by the dip-coating method, using a polyvinyl alcohol (PVA) solution. The PVA hydrogel was linked to the rPUF material by using a radiation-induced crosslinking process in aqueous ethanol solution. The ethanol in the solvent mixture allowed a balance between PVA swelling and PVA dissolution during the irradiation step. The resulting material showed higher thermal stability than the non-irradiated one. In addition, a simultaneous radiation-induced grafting polymerization (SRIGP) was done by simple addition of glycidyl methacrylate monomer into the irradiation solution. In a further step, sulfonic ligands were included specifically in the hydrogel layer, which contained around 200% of PVA respect to the original rPUF. Materials were characterized by FT-IR, thermogravimetric analysis, SEM microscopy and EDX analysis. The cation-exchange rPUF material was functionally characterized by the Langmuir isotherm and a dynamic adsorption experiment to analyze the chromatographic properties for protein purification processes.

Aluminum ions alter the function of non-specific phospholipase C through the changes in plasma membrane physical properties.

PubMed

Pejchar, Přemysl; Martinec, Jan

2015-01-01

The first indication of the aluminum (Al) toxicity in plants growing in acidic soils is the cessation of root growth, but the detailed mechanism of Al effect is unknown. Here we examined the impact of Al stress on the activity of non-specific phospholipase C (NPC) in the connection with the processes related to the plasma membrane using fluorescently labeled phosphatidylcholine. We observed a rapid and significant decrease of labeled diacylglycerol (DAG), product of NPC activity, in Arabidopsis seedlings treated with AlCl₃. Interestingly, an application of the membrane fluidizer, benzyl alcohol, restored the level of DAG during Al treatment. Our observations suggest that the activity of NPC is affected by Al-induced changes in plasma membrane physical properties.

Physical Activity Modulates Common Neuroplasticity Substrates in Major Depressive and Bipolar Disorder

PubMed Central

2017-01-01

Mood disorders (MDs) are chronic, recurrent mental diseases that affect millions of individuals worldwide. Although the biogenic amine model has provided some clinical utility, a need remains to better understand the interrelated mechanisms that contribute to neuroplasticity deficits in MDs and the means by which various therapeutics mitigate them. Of those therapeutics being investigated, physical activity (PA) has shown clear and consistent promise. Accordingly, the aims of this review are to (1) explicate key modulators, processes, and interactions that impinge upon multiple susceptibility points to effectuate neuroplasticity deficits in MDs; (2) explore the putative mechanisms by which PA mitigates these features; (3) review protocols used to induce the positive effects of PA in MDs; and (4) highlight implications for clinicians and researchers. PMID:28529805

RF stabilization of plasma instabilities: a note on physical mechanism

NASA Astrophysics Data System (ADS)

Sen, S.; Martinell, J.; Imadera, K.; Kishimoto, Y.; Vahala, G.

2018-02-01

In a series of recent works, we have developed models including realistic spatial profiles of both flow and radio-frequency-induced ponderomotive force. With these inclusions, the picture of stability of various plasma and fluid instabilities is expected to be changed drastically with ground-breaking consequences. The inhomogeneous parallel flow and the radio-frequency waves can actually stabilize turbulence. This is different from the prevalent notion that both parallel flow shear and radio-frequency waves are responsible for the excitation (destabilization) of plasma turbulence. This model thus aims to open-up new channels and provide a major breakthrough in our knowledge of plasma and fluid turbulence and its consequent roles in energy, space and processing technology. In this short note, we elucidate the physical mechanism behind this novel observation.

Synchrotron and ion beam studies of the bone-cartilage interface

NASA Astrophysics Data System (ADS)

Bradley, D. A.; Kaabar, W.; Gundogdu, O.; Farquharson, M. J.; Janousch, M.; Bailey, M.; Jeynes, C.

2010-07-01

The divalent cations Ca, P and Zn have been reported to play an important role in the normal growth and remodelling of articular cartilage and subchondral bone and in the degenerative and inflammatory processes associated with osteoarthritis (OA). In particular, they act as co-factors of a class of enzymes known as metalloproteinases, believed to be active during the initiation, progress and remodelling processes associated with the disease. The relative presence of cations and anions, in particular the ions Na 2+ and Cl -, is also intimately associated with the fixed charge density (FCD) of cartilage, neutralizing the highly charged structure associated with for instance chondroitin sulphate. Finally, structural components of bone can be expected to result from dietary intake, yielding for instance strontium apatite and fluorapatite that form inclusions in the calcium hydroxyapatite of bone. In the present investigation, thin sections of articular cartilage affected by OA have been examined using a combination of physical techniques: low energy synchrotron micro X-ray fluorescence (μ-SXRF), micro proton induced X-ray emission (μ-PIXE) and micro proton-induced gamma emission (μ-PIGE), primarily to investigate the distribution of essential cations and anions. The combination of these physical techniques offers the ability to make comprehensive assessment of the elemental content of such tissues, simultaneous mappings of a range of relatively low atomic number ions being obtained over quite large areas (˜few mm 2). Such capability has only become a realistic prospect in recent times.

Physical response of a back-barrier estuary to a post-tropical cyclone

USGS Publications Warehouse

Beudin, Alexis; Ganju, Neil Kamal; Defne, Zafer; Aretxabaleta, Alfredo

2017-01-01

This paper presents a modeling investigation of the hydrodynamic and sediment transport response of Chincoteague Bay (VA/MD, USA) to Hurricane Sandy using the Coupled Ocean-Atmosphere-Wave-Sediment-Transport (COAWST) modeling system. Several simulation scenarios with different combinations of remote and local forces were conducted to identify the dominant physical processes. While 80% of the water level increase in the bay was due to coastal sea level at the peak of the storm, a rich spatial and temporal variability in water surface slope was induced by local winds and waves. Local wind increased vertical mixing, horizontal exchanges, and flushing through the inlets. Remote waves (swell) enhanced southward flow through wave setup gradients between the inlets, and increased locally generated wave heights. Locally generated waves had a negligible effect on water level but reduced the residual flow up to 70% due to enhanced apparent roughness and breaking-induced forces. Locally generated waves dominated bed shear stress and sediment resuspension in the bay. Sediment transport patterns mirrored the interior coastline shape and generated deposition on inundated areas. The bay served as a source of fine sediment to the inner shelf, and the ocean-facing barrier island accumulated sand from landward-directed overwash. Despite the intensity of the storm forcing, the bathymetric changes in the bay were on the order of centimeters. This work demonstrates the spectrum of responses to storm forcing, and highlights the importance of local and remote processes on back-barrier estuarine function.

Physical activity and cancer prevention : pathways and targets for intervention.

PubMed

Rogers, Connie J; Colbert, Lisa H; Greiner, John W; Perkins, Susan N; Hursting, Stephen D

2008-01-01

The prevalence of obesity, an established epidemiological risk factor for many cancers, has risen steadily for the past several decades in the US and many other countries. Particularly alarming are the increasing rates of obesity among children, portending continuing increases in the rates of obesity and obesity-related cancers for many years to come. Modulation of energy balance, via increased physical activity, has been shown in numerous comprehensive epidemiological reviews to reduce cancer risk. Unfortunately, the effects and mechanistic targets of physical activity interventions on the carcinogenesis process have not been thoroughly characterized. Studies to date suggest that exercise can exert its cancer-preventive effects at many stages during the process of carcinogenesis, including both tumour initiation and progression. As discussed in this review, exercise may be altering tumour initiation events by modifying carcinogen activation, specifically by enhancing the cytochrome P450 system and by enhancing selective enzymes in the carcinogen detoxification pathway, including, but not limited to, glutathione-S-transferases. Furthermore, exercise may reduce oxidative damage by increasing a variety of anti-oxidant enzymes, enhancing DNA repair systems and improving intracellular protein repair systems. In addition to altering processes related to tumour initiation, exercise may also exert a cancer-preventive effect by dampening the processes involved in the promotion and progression stages of carcinogenesis, including scavenging reactive oxygen species (ROS); altering cell proliferation, apoptosis and differentiation; decreasing inflammation; enhancing immune function; and suppressing angiogenesis. A paucity of data exists as to whether exercise may be working as an anti-promotion strategy via altering ROS in initiated or preneoplastic models; therefore, no conclusions can be made about this possible mechanism. The studies directly examining cell proliferation and apoptosis have shown that exercise can enhance both processes, which is difficult to interpret in the context of carcinogenesis. Studies examining the relationship between exercise and chronic inflammation suggest that exercise may reduce pro-inflammatory mediators and reduce the state of low-grade, chronic inflammation. Additionally, exercise has been shown to enhance components of the innate immune response (i.e. macrophage and natural killer cell function). Finally, only a limited number of studies have explored the relationship between exercise and angiogenesis; therefore, no conclusions can be made currently about the role of exercise in the angiogenesis process as it relates to tumour progression. In summary, exercise can alter biological processes that contribute to both anti-initiation and anti-progression events in the carcinogenesis process. However, more sophisticated, detailed studies are needed to examine each of the potential mechanisms contributing to an exercise-induced decrease in carcinogenesis in order to determine the minimum dose, duration and frequency of exercise needed to yield significant cancer-preventive effects, and whether exercise can be used prescriptively to reverse the obesity-induced physiological changes that increase cancer risk.

Fatigue crack closure: a review of the physical phenomena

PubMed Central

Pippan, R.

2017-01-01

Abstract Plasticity‐induced, roughness‐induced and oxide‐induced crack closures are reviewed. Special attention is devoted to the physical origin, the consequences for the experimental determination and the prediction of the effective crack driving force for fatigue crack propagation. Plasticity‐induced crack closure under plane stress and plane strain conditions require, in principle, a different explanation; however, both types are predictable. This is even the case in the transition region from the plane strain to the plane stress state and all types of loading conditions including constant and variable amplitude loading, the short crack case or the transition from small‐scale to large‐scale yielding. In contrast, the prediction of roughness‐induced and oxide‐induced closures is not as straightforward. PMID:28616624

An Explorative Study to Use DBD Plasma Generation for Aircraft Icing Mitigation

NASA Astrophysics Data System (ADS)

Hu, Hui; Zhou, Wenwu; Liu, Yang; Kolbakir, Cem

2017-11-01

An explorative investigation was performed to demonstrate the feasibility of utilizing thermal effect induced by Dielectric-Barrier-Discharge (DBD) plasma generation for aircraft icing mitigation. The experimental study was performed in an Icing Research Tunnel available at Iowa State University (i.e., ISU-IRT). A NACA0012 airfoil/wing model embedded with DBD plasma actuators was installed in ISU-IRT under typical glaze icing conditions pertinent to aircraft inflight icing phenomena. While a high-speed imaging system was used to record the dynamic ice accretion process over the airfoil surface for the test cases with and without switching on the DBD plasma actuators, an infrared (IR) thermal imaging system was utilized to map the corresponding temperature distributions to quantify the unsteady heat transfer and phase changing process over the airfoil surface. The thermal effect induced by DBD plasma generation was demonstrated to be able to keep the airfoil surface staying free of ice during the entire ice accretion experiment. The measured quantitative surface temperature distributions were correlated with the acquired images of the dynamic ice accretion and water runback processes to elucidate the underlying physics. National Science Foundation CBET-1064196 and CBET-1435590.

Framing the nano-biointeractions by proteomics

NASA Astrophysics Data System (ADS)

Sabella, S.; Maiorano, G.; Rizzello, L.; Kote, S.; Cingolani, R.; Pompa, P. P.

2012-03-01

Knowledge of the molecular mechanisms underlying the interactions between nanomaterials and living systems is fundamental for providing more effective products for nanomedicine and drug delivery. Controlling the response of cells/bacteria (such as activation of inflammatory processes or apoptosis/necrosis in tumor cells or pathogenic bacteria) by tuning specific properties of the nanomaterials is ultimately the challenging goal. Notably, this may also provide crucial information in the assessment of any toxic risks induced by nanoparticles on humans. However, in studying the nano-biointeractions, it is imperative to take into account the dynamic evolutions of nanoparticles in the biological environments (in terms of protein corona formation, size and charge changes) in synergy with the dynamic events occurring in cells, including signal transduction, metabolic processes, homeostasis and membrane trafficking. In this context, we discuss the impact of analytical technologies, especially in the field of proteomics, which can provide major insights into the processes affecting the NPs surface as well as the cells and bacteria functionalities. In particular, we show that a precise control of the chemical-physical characteristics of the interacting nanoparticles or nanostructures may impact the cells by inducing changes in the proteomic profiles with direct consequences on their viability.

Moving beyond the limits of mass transport in liquid absorbent microfilms through the implementation of surface-induced vortices

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

Bigham, S; Yu, DZ; Chugh, D

2014-02-01

The slow diffusion of an absorbate molecule into an absorbent often makes the absorption process a rate-limiting step in many applications. In cases involving an absorbate with a high heat of phase change, such as water absorption into a LiBr (lithium bromide) solution, the absorption rate is further slowed due to significant heating of the absorbent. Recently, it has been demonstrated that constraining a LiBr solution film by a hydrophobic porous structure enables manipulation of the solution flow thermohydraulic characteristics. Here, it is shown that mass transport mode in a constrained laminar solution flow can be changed from diffusive tomore » advective. This change in mode is accomplished through stretching and folding the laminar streamlines within the solution film via the implementation of micro-scale features on the flow channel surface. The process induces vortices within the solution film, which continuously bring concentrated solution from the bottom and middle of the solution channel to its interface with the vapor phase, thus leading to a significant enhancement in the absorption rate. The detailed physics of the involved transport processes is elucidated using the LBM (Lattice Boltzmann Method). Published by Elsevier Ltd.« less

Characterization of Axial Inducer Cavitation Instabilities via High Speed Video Recordings

NASA Technical Reports Server (NTRS)

Arellano, Patrick; Peneda, Marinelle; Ferguson, Thomas; Zoladz, Thomas

2011-01-01

Sub-scale water tests were undertaken to assess the viability of utilizing high resolution, high frame-rate digital video recordings of a liquid rocket engine turbopump axial inducer to characterize cavitation instabilities. These high speed video (HSV) images of various cavitation phenomena, including higher order cavitation, rotating cavitation, alternating blade cavitation, and asymmetric cavitation, as well as non-cavitating flows for comparison, were recorded from various orientations through an acrylic tunnel using one and two cameras at digital recording rates ranging from 6,000 to 15,700 frames per second. The physical characteristics of these cavitation forms, including the mechanisms that define the cavitation frequency, were identified. Additionally, these images showed how the cavitation forms changed and transitioned from one type (tip vortex) to another (sheet cavitation) as the inducer boundary conditions (inlet pressures) were changed. Image processing techniques were developed which tracked the formation and collapse of cavitating fluid in a specified target area, both in the temporal and frequency domains, in order to characterize the cavitation instability frequency. The accuracy of the analysis techniques was found to be very dependent on target size for higher order cavitation, but much less so for the other phenomena. Tunnel-mounted piezoelectric, dynamic pressure transducers were present throughout these tests and were used as references in correlating the results obtained by image processing. Results showed good agreement between image processing and dynamic pressure spectral data. The test set-up, test program, and test results including H-Q and suction performance, dynamic environment and cavitation characterization, and image processing techniques and results will be discussed.

Alcohol and the Intestine

PubMed Central

Patel, Sheena; Behara, Rama; Swanson, Garth R.; Forsyth, Christopher B.; Voigt, Robin M.; Keshavarzian, Ali

2015-01-01

Alcohol abuse is a significant contributor to the global burden of disease and can lead to tissue damage and organ dysfunction in a subset of alcoholics. However, a subset of alcoholics without any of these predisposing factors can develop alcohol-mediated organ injury. The gastrointestinal tract (GI) could be an important source of inflammation in alcohol-mediated organ damage. The purpose of review was to evaluate mechanisms of alcohol-induced endotoxemia (including dysbiosis and gut leakiness), and highlight the predisposing factors for alcohol-induced dysbiosis and gut leakiness to endotoxins. Barriers, including immunologic, physical, and biochemical can regulate the passage of toxins into the portal and systemic circulation. In addition, a host of environmental interactions including those influenced by circadian rhythms can impact alcohol-induced organ pathology. There appears to be a role for therapeutic measures to mitigate alcohol-induced organ damage by normalizing intestinal dysbiosis and/or improving intestinal barrier integrity. Ultimately, the inflammatory process that drives progression into organ damage from alcohol appears to be multifactorial. Understanding the role of the intestine in the pathogenesis of alcoholic liver disease can pose further avenues for pathogenic and treatment approaches. PMID:26501334

Gravity, an Regulation Factor in BMSCs Differentiation to osteoblasts

NASA Astrophysics Data System (ADS)

Yan, Huang; Yinghui, Li; Fen, Yang; Zhongquan, Dai

PURPOSE Most studies of regulatory mechanisms of adult stem cell differentiation are concentrated in chemical factors but few efforts are put into physical factors Recent space life science studies indicate mechanical factors participate in the differentiation of cells The aim of this study is to investigate the effects of simulated microgravity or hypergravity on the osteogenic differentiation of rat bone marrow mesenchymal stem cells BMSCs METHODOLOGY The BMSCs at day 7 were added osteogenic inducer 10nM dexamethasone 10mM beta -glycerophosphate and 50 mu M asorbic acid-2-phosphate for 7 days and cultured under simulated microgravity or hypergravity 2g for 1 day 3 days 5 days or 7 days RESULTS After treating BMSCs with osteogenic inducer and hypergravity the cells expressed more ColIA1 Cbfa1 and ALP than in single steogenic inducer treatment Reversely the cells treated with osteogenic inducer and simulated microgravity expressed less ColIA1 Cbfa1 and ALP CONCLUSIONS Our study suggests that hypergravity promotes the osteogenic differentiation of BMSCs and simulated microgravity inhibits this process Gravity is an important regulation factor in BMSCs differentiation to osteoblasts

Pharmacological action of Panax ginseng on the behavioral toxicities induced by psychotropic agents.

PubMed

Kim, Hyoung-Chun; Shin, Eun-Joo; Jang, Choon-Gon; Lee, Myung-Koo; Eun, Jae-Soon; Hong, Jin-Tae; Oh, Ki-Wan

2005-09-01

Morphine-induced analgesia has been shown to be antagonized by ginseng total saponins (GTS), which also inhibit the development of analgesic tolerance to and physical dependence on morphine. GTS is involved in both of these processes by inhibiting morphine-6-dehydrogenase, which catalyzes the synthesis of morphinone from morphine, and by increasing the level of hepatic glutathione, which participates in the toxicity response. Thus, the dual actions of ginseng are associated with the detoxification of morphine. In addition, the inhibitory or facilitated effects of GTS on electrically evoked contractions in guinea pig ileum (mu-receptors) and mouse vas deferens (delta-receptors) are not mediated through opioid receptors, suggesting the involvement of non-opioid mechanisms. GTS also attenuates hyperactivity, reverse tolerance (behavioral sensitization), and conditioned place preference induced by psychotropic agents, such as methamphetamine, cocaine, and morphine. These effects of GTS may be attributed to complex pharmacological actions between dopamine receptors and a serotonergic/adenosine A2A/ delta-opioid receptor complex. Ginsenosides also attenuate the morphine-induced cAMP signaling pathway. Together, the results suggest that GTS may be useful in the prevention and therapy of the behavioral side effects induced by psychotropic agents.

Real-time Microseismic Processing for Induced Seismicity Hazard Detection

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

Matzel, Eric M.

Induced seismicity is inherently associated with underground fluid injections. If fluids are injected in proximity to a pre-existing fault or fracture system, the resulting elevated pressures can trigger dynamic earthquake slip, which could both damage surface structures and create new migration pathways. The goal of this research is to develop a fundamentally better approach to geological site characterization and early hazard detection. We combine innovative techniques for analyzing microseismic data with a physics-based inversion model to forecast microseismic cloud evolution. The key challenge is that faults at risk of slipping are often too small to detect during the site characterizationmore » phase. Our objective is to devise fast-running methodologies that will allow field operators to respond quickly to changing subsurface conditions.« less

Superhigh moduli and tension-induced phase transition of monolayer gamma-boron at finite temperatures.

PubMed

Zhao, Junhua; Yang, Zhaoyao; Wei, Ning; Kou, Liangzhi

2016-03-16

Two dimensional (2D) gamma-boron (γ-B28) thin films have been firstly reported by the experiments of the chemical vapor deposition in the latest study. However, their mechanical properties are still not clear. Here we predict the superhigh moduli (785 ± 42 GPa at 300 K) and the tension-induced phase transition of monolayer γ-B28 along a zigzag direction for large deformations at finite temperatures using molecular dynamics (MD) simulations. The new phase can be kept stable after unloading process at these temperatures. The predicted mechanical properties are reasonable when compared with our results from density functional theory. This study provides physical insights into the origins of the new phase transition of monolayer γ-B28 at finite temperatures.

Experimental Studies of Nuclear Physics Input for γ -Process Nucleosynthesis

NASA Astrophysics Data System (ADS)

Scholz, Philipp; Heim, Felix; Mayer, Jan; Netterdon, Lars; Zilges, Andreas

The predictions of reaction rates for the γ process in the scope of the Hauser-Feshbach statistical model crucially depend on nuclear physics input-parameters as optical-model potentials (OMP) or γ -ray strength functions. Precise cross-section measurements at astrophysically relevant energies help to constrain adopted models and, therefore, to reduce the uncertainties in the theoretically predicted reaction rates. During the last years, several cross-sections of charged-particle induced reactions on heavy nuclei have been measured at the University of Cologne. Either by means of the in-beam method at the HORUS γ -ray spectrometer or the activation technique using the Cologne Clover Counting Setup, total and partial cross-sections could be used to further constrain different models for nuclear physics input-parameters. It could be shown that modifications on the α -OMP in the case of the 112Sn(α , γ ) reaction also improve the description of the recently measured cross sections of the 108Cd(α , γ ) and 108Cd(α , n) reaction and other reactions as well. Partial cross-sections of the 92Mo(p, γ ) reaction were used to improve the γ -strength function model in 93Tc in the same way as it was done for the 89Y(p, γ ) reaction.

Magnetic Local Time dependency in modeling of the Earth radiation belts

NASA Astrophysics Data System (ADS)

Herrera, Damien; Maget, Vincent; Bourdarie, Sébastien; Rolland, Guy

2017-04-01

For many years, ONERA has been at the forefront of the modeling of the Earth radiation belts thanks to the Salammbô model, which accurately reproduces their dynamics over a time scale of the particles' drift period. This implies that we implicitly assume an homogeneous repartition of the trapped particles along a given drift shell. However, radiation belts are inhomogeneous in Magnetic Local Time (MLT). So, we need to take this new coordinate into account to model rigorously the dynamical structures, particularly induced during a geomagnetic storm. For this purpose, we are working on both the numerical resolution of the Fokker-Planck diffusion equation included in the model and on the MLT dependency of physic-based processes acting in the Earth radiation belts. The aim of this talk is first to present the 4D-equation used and the different steps we used to build Salammbô 4D model before focusing on physical processes taken into account in the Salammbô code, specially transport due to convection electric field. Firstly, we will briefly introduce the Salammbô 4D code developped by talking about its numerical scheme and physic-based processes modeled. Then, we will focus our attention on the impact of the outer boundary condition (localisation and spectrum) at lower L∗ shell by comparing modeling performed with geosynchronous data from LANL-GEO satellites. Finally, we will discuss the prime importance of the convection electric field to the radial and drift transport of low energy particles around the Earth.

Monolithic Active Pixel Sensors (MAPS) in a Quadruple Well Technology for Nearly 100% Fill Factor and Full CMOS Pixels

PubMed Central

Ballin, Jamie Alexander; Crooks, Jamie Phillip; Dauncey, Paul Dominic; Magnan, Anne-Marie; Mikami, Yoshinari; Miller, Owen Daniel; Noy, Matthew; Rajovic, Vladimir; Stanitzki, Marcel; Stefanov, Konstantin; Turchetta, Renato; Tyndel, Mike; Villani, Enrico Giulio; Watson, Nigel Keith; Wilson, John Allan

2008-01-01

In this paper we present a novel, quadruple well process developed in a modern 0.18 μm CMOS technology called INMAPS. On top of the standard process, we have added a deep P implant that can be used to form a deep P-well and provide screening of N-wells from the P-doped epitaxial layer. This prevents the collection of radiation-induced charge by unrelated N-wells, typically ones where PMOS transistors are integrated. The design of a sensor specifically tailored to a particle physics experiment is presented, where each 50 μm pixel has over 150 PMOS and NMOS transistors. The sensor has been fabricated in the INMAPS process and first experimental evidence of the effectiveness of this process on charge collection is presented, showing a significant improvement in efficiency. PMID:27873817

Constructing constitutive relationships for seismic and aseismic fault slip

USGS Publications Warehouse

Beeler, N.M.

2009-01-01

For the purpose of modeling natural fault slip, a useful result from an experimental fault mechanics study would be a physically-based constitutive relation that well characterizes all the relevant observations. This report describes an approach for constructing such equations. Where possible the construction intends to identify or, at least, attribute physical processes and contact scale physics to the observations such that the resulting relations can be extrapolated in conditions and scale between the laboratory and the Earth. The approach is developed as an alternative but is based on Ruina (1983) and is illustrated initially by constructing a couple of relations from that study. In addition, two example constitutive relationships are constructed; these describe laboratory observations not well-modeled by Ruina's equations: the unexpected shear-induced weakening of silica-rich rocks at high slip speed (Goldsby and Tullis, 2002) and fault strength in the brittle ductile transition zone (Shimamoto, 1986). The examples, provided as illustration, may also be useful for quantitative modeling.

Pressure gradient induced generation of microbubbles

NASA Astrophysics Data System (ADS)

Evangelio, Alvaro; Campo-Cortes, Francisco; Gordillo, Jose Manuel

2015-11-01

It is well known that the controlled production of monodisperse bubbles possesses uncountable applications in medicine, pharmacy and industry. Here we provide with a detailed physical description of the bubble formation processes taking place in a type of flow where the liquid pressure gradient can be straightforwardly controlled. In our experiments, a gas flow rate discharges through a cylindrical needle into a pressurized chamber. The pressure gradient created from the exit of the injection needle towards the entrance of a extraction duct promotes the stretching of the gas ligament downstream. In our analysis, which is supported by an exhaustive experimental study in which the liquid viscosity is varied by three orders of magnitude, different regimes can be distinguished depending mainly on the Reynolds number. Through our physical modeling, we provide closed expressions for both the bubbling frequencies and for the bubble diameters as well as the conditions under which a monodisperse generation is obtained in all regimes found. The excellent agreement between our expressions and the experimental data fully validates our physical modeling.

Land-use changes and the physical habitat of streams - a review with emphasis on studies within the U.S. Geological Survey Federal-State Cooperative Program

USGS Publications Warehouse

Jacobson, Robert B.; Femmer, Suzanne R.; McKenney, Rose A.

2001-01-01

Understanding the links between land-use changes and physical stream habitat responses is of increasing importance to guide resource management and stream restoration strategies. Transmission of runoff and sediment to streams can involve complex responses of drainage basins, including time lags, thresholds, and cumulative effects. Land-use induced runoff and sediment yield often combine with channel-scale disturbances that decrease flow resistance and erosion resistance, or increase stream energy. The net effects of these interactions on physical stream habitat—depth, velocity, substrate, cover, and temperature—are a challenge to predict. Improved diagnosis and predictive understanding of future change usually require multifaceted, multi-scale, and multidisciplinary studies based on a firm understanding of the history and processes operating in a drainage basin. The U.S. Geological Survey Federal-State Cooperative Program has been instrumental in fostering studies of the links between land use and stream habitat nationwide.

Cockatiel-induced hypersensitivity pneumonitis.

PubMed

McCluskey, James D; Haight, Robert R; Brooks, Stuart M

2002-07-01

Diagnosing an environmental or occupationally related pulmonary disorder often involves a process of elimination. Unlike commonly diagnosed conditions in other specialties, a cause-and-effect relationship may be implied, yet other factors such as temporality and biologic plausibility are lacking. Our patient was referred with a suspected work-related pulmonary disorder. For several years, she had suffered with dyspnea on exertion and repeated flulike illnesses. She worked at an automobile repair garage that performed a large number of emission tests, and there was concern that her workplace exposures were the cause of her symptoms. After a careful review of her history, physical examination, and laboratory testing, we came to the conclusion that she had hypersensitivity pneumonitis related to pet cockatiels in her home. Clinical points of emphasis include the importance of a complete environmental history and careful auscultation of the chest when performing the physical examination. In addition, we encountered an interesting physical diagnostic clue, a respiratory sound that assisted with the eventual diagnosis.

Cockatiel-induced hypersensitivity pneumonitis.

PubMed Central

McCluskey, James D; Haight, Robert R; Brooks, Stuart M

2002-01-01

Diagnosing an environmental or occupationally related pulmonary disorder often involves a process of elimination. Unlike commonly diagnosed conditions in other specialties, a cause-and-effect relationship may be implied, yet other factors such as temporality and biologic plausibility are lacking. Our patient was referred with a suspected work-related pulmonary disorder. For several years, she had suffered with dyspnea on exertion and repeated flulike illnesses. She worked at an automobile repair garage that performed a large number of emission tests, and there was concern that her workplace exposures were the cause of her symptoms. After a careful review of her history, physical examination, and laboratory testing, we came to the conclusion that she had hypersensitivity pneumonitis related to pet cockatiels in her home. Clinical points of emphasis include the importance of a complete environmental history and careful auscultation of the chest when performing the physical examination. In addition, we encountered an interesting physical diagnostic clue, a respiratory sound that assisted with the eventual diagnosis. PMID:12117652

The physics of lipid droplet nucleation, growth and budding.

PubMed

Thiam, Abdou Rachid; Forêt, Lionel

2016-08-01

Lipid droplets (LDs) are intracellular oil-in-water emulsion droplets, covered by a phospholipid monolayer and mainly present in the cytosol. Despite their important role in cellular metabolism and growing number of newly identified functions, LD formation mechanism from the endoplasmic reticulum remains poorly understood. To form a LD, the oil molecules synthesized in the ER accumulate between the monolayer leaflets and induce deformation of the membrane. This formation process works through three steps: nucleation, growth and budding, exactly as in phase separation and dewetting phenomena. These steps involve sequential biophysical membrane remodeling mechanisms for which we present basic tools of statistical physics, membrane biophysics, and soft matter science underlying them. We aim to highlight relevant factors that could control LD formation size, site and number through this physics description. An emphasis will be given to a currently underestimated contribution of the molecular interactions between lipids to favor an energetically costless mechanism of LD formation. Copyright © 2016 Elsevier B.V. All rights reserved.

Conceptualizing Obesity as a Chronic Disease: An Interview With Dr. Arya Sharma.

PubMed

Sharma, Arya M; Goodwin, Donna L; Causgrove Dunn, Janice

2018-03-23

Dr. Arya M. Sharma challenges the conventional wisdom of relying simply on "lifestyle" approaches involving exercise, diet, and behavioral interventions for managing obesity, suggesting that people living with obesity should receive comprehensive medical interventions similar to the approach taken for other chronic diseases such as Type 2 diabetes or hypertension. He purports that the stigma-inducing focus on self-failing (e.g., coping through food, laziness, lack of self-regulation) does not address biological processes that make obesity a lifelong problem for which there is no easy solution. Interdisciplinary approaches to obesity are advocated, including that of adapted physical activity. Physical activity has multifaceted impacts beyond increasing caloric expenditure, including improved sleep, better mood, increased energy levels, enhanced self-esteem, reduced stress, and an enhanced sense of well-being. The interview with Dr. Sharma, transcribed from a keynote address delivered at the North American Adapted Physical Activity Symposium on September 22, 2016, in Edmonton, AB, Canada, outlines his rationale for approaching obesity as a chronic disease.

Minding the Cyber-Physical Gap: Model-Based Analysis and Mitigation of Systemic Perception-Induced Failure.

PubMed

Mordecai, Yaniv; Dori, Dov

2017-07-17

The cyber-physical gap (CPG) is the difference between the 'real' state of the world and the way the system perceives it. This discrepancy often stems from the limitations of sensing and data collection technologies and capabilities, and is inevitable at some degree in any cyber-physical system (CPS). Ignoring or misrepresenting such limitations during system modeling, specification, design, and analysis can potentially result in systemic misconceptions, disrupted functionality and performance, system failure, severe damage, and potential detrimental impacts on the system and its environment. We propose CPG-Aware Modeling & Engineering (CPGAME), a conceptual model-based approach to capturing, explaining, and mitigating the CPG. CPGAME enhances the systems engineer's ability to cope with CPGs, mitigate them by design, and prevent erroneous decisions and actions. We demonstrate CPGAME by applying it for modeling and analysis of the 1979 Three Miles Island 2 nuclear accident, and show how its meltdown could be mitigated. We use ISO-19450:2015-Object Process Methodology as our conceptual modeling framework.

Accretion-induced variability links young stellar objects, white dwarfs, and black holes.

PubMed

Scaringi, Simone; Maccarone, Thomas J; Körding, Elmar; Knigge, Christian; Vaughan, Simon; Marsh, Thomas R; Aranzana, Ester; Dhillon, Vikram S; Barros, Susana C C

2015-10-01

The central engines of disc-accreting stellar-mass black holes appear to be scaled down versions of the supermassive black holes that power active galactic nuclei. However, if the physics of accretion is universal, it should also be possible to extend this scaling to other types of accreting systems, irrespective of accretor mass, size, or type. We examine new observations, obtained with Kepler/K2 and ULTRACAM, regarding accreting white dwarfs and young stellar objects. Every object in the sample displays the same linear correlation between the brightness of the source and its amplitude of variability (rms-flux relation) and obeys the same quantitative scaling relation as stellar-mass black holes and active galactic nuclei. We also show that the most important parameter in this scaling relation is the physical size of the accreting object. This establishes the universality of accretion physics from proto-stars still in the star-forming process to the supermassive black holes at the centers of galaxies.

Accretion-induced variability links young stellar objects, white dwarfs, and black holes

PubMed Central

Scaringi, Simone; Maccarone, Thomas J.; Körding, Elmar; Knigge, Christian; Vaughan, Simon; Marsh, Thomas R.; Aranzana, Ester; Dhillon, Vikram S.; Barros, Susana C. C.

2015-01-01

The central engines of disc-accreting stellar-mass black holes appear to be scaled down versions of the supermassive black holes that power active galactic nuclei. However, if the physics of accretion is universal, it should also be possible to extend this scaling to other types of accreting systems, irrespective of accretor mass, size, or type. We examine new observations, obtained with Kepler/K2 and ULTRACAM, regarding accreting white dwarfs and young stellar objects. Every object in the sample displays the same linear correlation between the brightness of the source and its amplitude of variability (rms-flux relation) and obeys the same quantitative scaling relation as stellar-mass black holes and active galactic nuclei. We also show that the most important parameter in this scaling relation is the physical size of the accreting object. This establishes the universality of accretion physics from proto-stars still in the star-forming process to the supermassive black holes at the centers of galaxies. PMID:26601307

Single magnetic adsorbates on s-wave superconductors

NASA Astrophysics Data System (ADS)

Heinrich, Benjamin W.; Pascual, Jose I.; Franke, Katharina J.

2018-02-01

In superconductors, magnetic impurities induce a pair-breaking potential for Cooper pairs, which locally affects the Bogoliubov quasiparticles and gives rise to Yu-Shiba-Rusinov (YSR or Shiba, in short) bound states in the density of states (DoS). These states carry information on the magnetic coupling strength of the impurity with the superconductor, which determines the many-body ground state properties of the system. Recently, the interest in Shiba physics was boosted by the prediction of topological superconductivity and Majorana modes in magnetically coupled chains and arrays of Shiba impurities. Here, we review the physical insights obtained by scanning tunneling microscopy into single magnetic adsorbates on the s-wave superconductor lead (Pb). We explore the tunneling processes into Shiba states, show how magnetic anisotropy affects many-body excitations, and determine the crossing of the many-body ground state through a quantum phase transition. Finally, we discuss the coupling of impurities into dimers and chains and their relation to Majorana physics.

Constitutive equations of a tensorial model for strain-induced damage of metals based on three invariants

NASA Astrophysics Data System (ADS)

Tutyshkin, Nikolai D.; Lofink, Paul; Müller, Wolfgang H.; Wille, Ralf; Stahn, Oliver

2017-01-01

On the basis of the physical concepts of void formation, nucleation, and growth, generalized constitutive equations are formulated for a tensorial model of plastic damage in metals based on three invariants. The multiplicative decomposition of the metric transformation tensor and a thermodynamically consistent formulation of constitutive relations leads to a symmetric second-order damage tensor with a clear physical meaning. Its first invariant determines the damage related to plastic dilatation of the material due to growth of the voids. The second invariant of the deviatoric damage tensor is related to the change in void shape. The third invariant of the deviatoric tensor describes the impact of the stress state on damage (Lode angle), including the effect of rotating the principal axes of the stress tensor (Lode angle change). The introduction of three measures with related physical meaning allows for the description of kinetic processes of strain-induced damage with an equivalent parameter in a three-dimensional vector space, including the critical condition of ductile failure. Calculations were performed by using experimentally determined material functions for plastic dilatation and deviatoric strain at the mesoscale, as well as three-dimensional graphs for plastic damage of steel DC01. The constitutive parameter was determined from tests in tension, compression, and shear by using scanning electron microscopy, which allowed to vary the Lode angle over the full range of its values [InlineEquation not available: see fulltext.]. In order to construct the three-dimensional plastic damage curve for a range of triaxiality parameters -1 ≤ ST ≤ 1 and of Lode angles [InlineEquation not available: see fulltext.], we used our own, as well as systematized published experimental data. A comparison of calculations shows a significant effect of the third invariant (Lode angle) on equivalent damage. The measure of plastic damage, based on three invariants, can be useful for assessing the quality of metal mesostructure produced during metal forming processes. In many processes of metal sheet forming the material experiences, a non-proportional loading accompanied by rotating the principal axes of the stress tensor and a corresponding change of Lode angle.

Consideration of vision and picture quality: psychological effects induced by picture sharpness

NASA Astrophysics Data System (ADS)

Kusaka, Hideo

1989-08-01

A psychological hierarchy model of human vision(1)(2) suggests that the visual signals are processed in a serial manner from lower to higher stages: that is "sensation" - "perception" - "emotion." For designing a future television system, it is important to find out what kinds of physical factors affect the "emotion" experienced by an observer in front of the display. This paper describes the psychological effects induced by the sharpness of the picture. The subjective picture quality was evaluated for the same pictures with five different levels of sharpness. The experiment was performed on two kinds of printed pictures: (A) a woman's face, and (B) a town corner. From these experiments, it was found that the amount of high-frequency peaking (physical value of the sharpness) which psychologically gives the best picture quality, differs between pictures (A) and (B). That is, the optimum picture sharpness differs depending on the picture content. From these results, we have concluded that the psychophysical sharpness of the picture is not only determined at the stage of "perception" (e.g., resolution or signal to noise ratio, which everyone can judge immediately), but also at the stage of "emotion" (e.g., sensation of reality or beauty).

A Bidirectional Relationship between Executive Function and Health Behavior: Evidence, Implications, and Future Directions

PubMed Central

Allan, Julia L.; McMinn, David; Daly, Michael

2016-01-01

Physically active lifestyles and other health-enhancing behaviors play an important role in preserving executive function into old age. Conversely, emerging research suggests that executive functions facilitate participation in a broad range of healthy behaviors including physical activity and reduced fatty food, tobacco, and alcohol consumption. They do this by supporting the volition, planning, performance monitoring, and inhibition necessary to enact intentions and override urges to engage in health damaging behavior. Here, we focus firstly on evidence suggesting that health-enhancing behaviors can induce improvements in executive function. We then switch our focus to findings linking executive function to the consistent performance of health-promoting behaviors and the avoidance of health risk behaviors. We suggest that executive function, health behavior, and disease processes are interdependent. In particular, we argue that a positive feedback loop may exist whereby health behavior-induced changes in executive function foster subsequent health-enhancing behaviors, which in turn help sustain efficient executive functions and good health. We conclude by outlining the implications of this reciprocal relationship for intervention strategies, the design of research studies, and the study of healthy aging. PMID:27601977

Electrical modulus analysis on the Ni/CCTO/PVDF system near the percolation threshold

NASA Astrophysics Data System (ADS)

Yang, Wenhu; Yu, Shuhui; Sun, Rong; Ke, Shanming; Huang, Haitao; Du, Ruxu

2011-11-01

A type of Ni/CCTO/PVDF three-phase percolative composite was prepared, in which the filler content (volume fraction) of Ni and CCTO was set at 60 vol%. The dependence of permittivity, electrical modulus and ac conductivity on the concentration of Ni and CCTO fillers near the percolation threshold was investigated in detail. The permittivity of the composites dramatically increased as the Ni content approached 24 vol%. This unique physical mechanism was realized as the formation of conductive channels near the percolation threshold. Analysis on the electrical modulus showed that the conductive channels are governed by three relaxation processes induced by the fillers (Ni, CCTO) and PVDF matrix, which are the interfacial polarization derived from the interfaces between fillers (Ni, CCTO) and PVDF matrix, and the polarization of CCTO ceramic filler and PVDF matrix. The conductivity behaviour with various Ni loadings and temperature suggested that the transition from an insulating to a conducting state should be induced by charge tunnelling between Ni-Ni particles, Ni-CCTO fillers and Ni-PVDF matrix. These findings demonstrated that the tunnelling conduction in the composite can be attributed to the unique physical mechanism near the percolation threshold.

Hepatic steatosis development with four weeks of physical inactivity in previously active, hyperphagic OLETF rats.

PubMed

Linden, Melissa A; Meers, Grace M; Ruebel, Meghan L; Jenkins, Nathan T; Booth, Frank W; Laughlin, M Harold; Ibdah, Jamal A; Thyfault, John P; Rector, R Scott

2013-05-01

Physical activity-induced prevention of hepatic steatosis is maintained during short-term (7-day) transitions to an inactive state; however, whether these protective effects are present under a longer duration of physical inactivity is largely unknown. Here, we sought to determine whether previous physical activity had protective effects on hepatic steatosis and metabolic health following 4 wk of physical inactivity. Four-week old, hyperphagic, male Otsuka Long-Evans Tokushima fatty (OLETF) rats were randomly assigned to either a sedentary group for 16 wk (OLETF-SED), given access to running wheels for 16 wk with wheels locked 5 h (OLETF-WL5hr) or given access to running wheels for 12 wk with wheels locked 4 wk (OLETF-WL4wk) prior to death. Four weeks of physical inactivity caused hepatic steatosis development, but liver triglycerides remained 60% lower than OLETF-SED (P < 0.01), and this was associated with only a partial loss in activity-induced improvements in body composition, serum lipids, and glycemic control. Total hepatic mitochondrial palmitate oxidation, citrate synthase, and β-HAD activity returned to SED levels following 4 wk of inactivity, whereas markers of fatty acid uptake and lipogenesis remained relatively suppressed following 4 wk of inactivity. In addition, 4 wk of inactivity caused a complete loss of activity-induced increases in serum IL-6 and reductions in regulated upon activation, normal T-cell expressed, and secreted (RANTES), and a partial loss in reductions in leptin, monocyte chemoattractant protein-1, and TNF-α. In conclusion, 4 wk of physical inactivity does not result in a complete loss in physical activity-induced benefits but does cause deterioration in the liver phenotype and overall metabolic health in hyperphagic OLETF rats.

A mathematical model for predicting photo-induced voltage and photostriction of PLZT with coupled multi-physics fields and its application

NASA Astrophysics Data System (ADS)

Huang, J. H.; Wang, X. J.; Wang, J.

2016-02-01

The primary purpose of this paper is to propose a mathematical model of PLZT ceramic with coupled multi-physics fields, e.g. thermal, electric, mechanical and light field. To this end, the coupling relationships of multi-physics fields and the mechanism of some effects resulting in the photostrictive effect are analyzed theoretically, based on which a mathematical model considering coupled multi-physics fields is established. According to the analysis and experimental results, the mathematical model can explain the hysteresis phenomenon and the variation trend of the photo-induced voltage very well and is in agreement with the experimental curves. In addition, the PLZT bimorph is applied as an energy transducer for a photovoltaic-electrostatic hybrid actuated micromirror, and the relation of the rotation angle and the photo-induced voltage is discussed based on the novel photostrictive mathematical model.

Human vulnerability, dislocation and resettlement: adaptation processes of river-bank erosion-induced displacees in Bangladesh.

PubMed

Hutton, David; Haque, C Emdad

2004-03-01

The purpose of this research was to identify and analyse patterns of economic and social adaptation among river-bank erosion-induced displacees in Bangladesh. It was hypothesised that the role of social demographic and socio-economic variables in determining the coping ability and recovery of the river-bank erosion-induced displacees is quite significant. The findings of the research reveal that displacees experience substantial socio-economic impoverishment and marginalisation as a consequence of involuntary migration. This in part is a socially constructed process, reflecting inequitable access to land and other resources. Vulnerability to disasters is further heightened by a number of identifiable social and demographic factors including gender, education and age, although extreme poverty and marginalisation create complexity to isolate the relative influence of these variables. The need to integrate hazard analysis and mitigation with the broader economic and social context is discussed. It is argued that the capacity of people to respond to environmental threats is a function of not only the physical forces which affect them, but also of underlying economic and social relationships which increase human vulnerability to risk. Hazard analysis and mitigation can be more effective when it takes into account such social and demographic and socio-economic dimensions of disasters.

Chemical modulation of electronic structure at the excited state

NASA Astrophysics Data System (ADS)

Li, F.; Song, C.; Gu, Y. D.; Saleem, M. S.; Pan, F.

2017-12-01

Spin-polarized electronic structures are the cornerstone of spintronics, and have thus attracted a significant amount of interest; in particular, researchers are looking into how to modulate the electronic structure to enable multifunctional spintronics applications, especially in half-metallic systems. However, the control of the spin polarization has only been predicted in limited two-dimensional systems with spin-polarized Dirac structures and is difficult to achieve experimentally. Here, we report the modulation of the electronic structure in the light-induced excited state in a typical half-metal, L a1 /2S r1 /2Mn O3 -δ . According to the spin-transport measurements, there appears a light-induced increase in magnetoresistance due to the enhanced spin scattering, which is closely associated with the excited spin polarization. Strikingly, the light-induced variation can be enhanced via alcohol processing and reduced by oxygen annealing. X-ray photoelectron spectroscopy measurements show that in the chemical process, a redox reaction occurs with a change in the valence of Mn. Furthermore, first-principles calculations reveal that the change in the valence of Mn alters the electronic structure and consequently modulates the spin polarization in the excited state. Our findings thus report a chemically tunable electronic structure, demonstrating interesting physics and the potential for multifunctional applications and ultrafast spintronics.

Measurement of Low-Energy Nuclear-Recoil Quenching Factors in CsI[Na] and Statistical Analysis of the First Observation of Coherent, Elastic Neutrino-Nucleus Scattering

NASA Astrophysics Data System (ADS)

Rich, Grayson Currie

The COHERENT Collaboration has produced the first-ever observation, with a significance of 6.7sigma, of a process consistent with coherent, elastic neutrino-nucleus scattering (CEnuNS) as first predicted and described by D.Z. Freedman in 1974. Physics of the CEnuNS process are presented along with its relationship to future measurements in the arenas of nuclear physics, fundamental particle physics, and astroparticle physics, where the newly-observed interaction presents a viable tool for investigations into numerous outstanding questions about the nature of the universe. To enable the CEnuNS observation with a 14.6-kg CsI[Na] detector, new measurements of the response of CsI[Na] to low-energy nuclear recoils, which is the only mechanism by which CEnuNS is detectable, were carried out at Triangle Universities Nuclear Laboratory; these measurements are detailed and an effective nuclear-recoil quenching factor of 8.78 +/- 1.66% is established for CsI[Na] in the recoil-energy range of 5-30 keV, based on new and literature data. Following separate analyses of the CEnuNS-search data by groups at the University of Chicago and the Moscow Engineering and Physics Institute, information from simulations, calculations, and ancillary measurements were used to inform statistical analyses of the collected data. Based on input from the Chicago analysis, the number of CEnuNS events expected from the Standard Model is 173 +/- 48; interpretation as a simple counting experiment finds 136 +/- 31 CEnuNS counts in the data, while a two-dimensional, profile likelihood fit yields 134 +/- 22 CEnuNS counts. Details of the simulations, calculations, and supporting measurements are discussed, in addition to the statistical procedures. Finally, potential improvements to the CsI[Na]-based CEnuNS measurement are presented along with future possibilities for COHERENT Collaboration, including new CEnuNS detectors and measurement of the neutrino-induced neutron spallation process.

[Study on physical deviation factors on laser induced breakdown spectroscopy measurement].

PubMed

Wan, Xiong; Wang, Peng; Wang, Qi; Zhang, Qing; Zhang, Zhi-Min; Zhang, Hua-Ming

2013-10-01

In order to eliminate the deviation between the measured LIBS spectral line and the standard LIBS spectral line, and improve the accuracy of elements measurement, a research of physical deviation factors in laser induced breakdown spectroscopy technology was proposed. Under the same experimental conditions, the relationship of ablated hole effect and spectral wavelength was tested, the Stark broadening data of Mg plasma laser induced breakdown spectroscopy with sampling time-delay from 1.00 to 3.00 micros was also studied, thus the physical deviation influences such as ablated hole effect and Stark broadening could be obtained while collecting the spectrum. The results and the method of the research and analysis can also be applied to other laser induced breakdown spectroscopy experiment system, which is of great significance to improve the accuracy of LIBS elements measuring and is also important to the research on the optimum sampling time-delay of LIBS.

Effect of a pharmacologically induced decrease in core temperature in rats resuscitated from cardiac arrest.

PubMed

Katz, Laurence M; Frank, Jonathan E; Glickman, Lawrence T; McGwin, Gerald; Lambert, Brice H; Gordon, Christopher J

2015-07-01

Hypothermia is recommended by international guidelines for treatment of unconscious survivors of cardiac arrest to improve neurologic outcomes. However, temperature management is often underutilized because it may be difficult to implement. The present study evaluated the efficacy of pharmacologically induced hypothermia on survival and neurological outcome in rats resuscitated from cardiac arrest. Cardiac arrest was induced for 10 min in 120 rats. Sixty-one rats were resuscitated and randomized to normothermia, physical cooling or pharmacological hypothermia 5 min after resuscitation. Pharmacological hypothermia rats received a combination of ethanol, vasopressin and lidocaine (HBN-1). Physical hypothermia rats were cooled with intravenous iced saline and cooling pads. Rats in the pharmacological hypothermia group received HBN-1 at ambient temperature (20 °C). Normothermic rats were maintained at 37.3 ± 0.2 °C. HBN-1 (p < 0.0001) shortened the time (85 ± 71 min) to target temperature (33.5 °C) versus physical hypothermia (247 ± 142 min). The duration of hypothermia was 17.0 ± 6.8h in the HBN-1 group and 17.3 ± 7.5h in the physical hypothermia group (p = 0.918). Survival (p = 0.034), neurological deficit scores (p < 0.0001) and Morris Water Maze performance after resuscitation (p = 0.041) was improved in the HBN-1 versus the normothermic group. HBN-1 improved survival and early neurological outcome compared to the physical hypothermia group while there was no significant difference in performance in the Morris water maze. HBN-1 induced rapid and prolonged hypothermia improved survival with good neurological outcomes after cardiac arrest suggesting that pharmacologically induced regulated hypothermia may provide a practical alternative to physical cooling. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Ultrastructural demonstration of chemical modification of melanogenesis in hairless mouse skin

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

Nishimura, M.; Gellin, G.A.; Hoshino, S.

1982-02-01

We investigated chemical and physical modifications of the genetically determined ultrastructure of melanosomes. The flank skin of hairless mice was treated with ultraviolet energy (UV) shorter than 320 nm or with a combination of a photosensitizer and UV (PUVA treatment). All melanosomes in the induced melanocytes and those in resident melanocytes in the ear skin showed eumelanogenesis, although the degree of melanin deposition differed considerably according to the induction process. Eumelanogenesis was most advanced in the resident melanocytes while PUVA-induced melanocytes showed more immature premelanosomes. We then topically applied 4-tertiary butyl catechol on the skin. The depigmenting agent caused anmore » appearance of pheomelanosomes. The alteration in melanogenesis was seen most distinctly in premelanosomes of the PUVA-induced cells. Altered ultrastructure was also observed in matured melanosomes; this change was most apparent in the resident melanocytes. These findings indicate that cells with eumelanogenesis may undergo pheomelanogenesis. The present study demonstrated effects of chemicals on genetically determined function of melanocytes by quantitative analysis of melanosome ultrastructure.« less

Bullous dermatitis artefacta.

PubMed

Sokumbi, Olayemi; Comfere, Nneka I; McEvoy, Marian T; Peters, Margot S

2013-02-01

Bullous artefactual dermatoses are rare and may be induced by various techniques, including chemicals, heat, or electrical current. Proving a factitial etiology and identifying the mechanism of injury may be difficult. We describe the clinical features and histopathology of 2 patients with bullous disease induced by electrical current or heat. Physical examination in both patients demonstrated geometrically shaped tense bullae. Skin biopsies revealed epidermal necrosis overlying a pauci-inflammatory subepidermal cleft, with homogenization of underlying superficial dermal collagen. In 1 of the 2 patients, there was prominent vertical elongation of keratinocyte nuclei and also of cytoplasmic processes. Direct immunofluorescence study of skin plus testing of serum by indirect immunofluorescence and enzyme-linked immunosorbent assay for BP180 and BP230 antibodies revealed no evidence for immunobullous disease in either patient. Vertical elongation of keratinocyte nuclei, often attributed to a polarization effect of electrical current, is characteristic of electrical burn but also may be induced by thermal injury. These 2 patients highlight the importance of histopathology in confirming a diagnosis of bullous dermatitis artefacta.

Quantitative mapping of zinc fluxes in the mammalian egg reveals the origin of fertilization-induced zinc sparks

PubMed Central

Que, Emily L.; Bleher, Reiner; Duncan, Francesca E.; Kong, Betty Y.; Gleber, Sophie C.; Vogt, Stefan; Chen, Si; Garwin, Seth A.; Bayer, Amanda R.; Dravid, Vinayak; Woodruff, Teresa K.; O’Halloran, Thomas V.

2015-01-01

Fertilization of a mammalian egg induces a series of ‘zinc sparks’ that are necessary for inducing the egg-to-embryo transition. Despite the importance of these zinc efflux events little is known about their origin. To understand the molecular mechanism of the zinc spark we combined four physical approaches to resolve zinc distributions in single cells: a chemical probe for dynamic live-cell fluorescence imaging and a combination of scanning transmission electron microscopy with energy dispersive spectroscopy, X-ray fluorescence microscopy, and 3D elemental tomography for high resolution elemental mapping. We show that the zinc spark arises from a system of thousands of zinc-loaded vesicles, each of which contains, on average, 106 zinc atoms. These vesicles undergo dynamic movement during oocyte maturation and exocytosis at the time of fertilization. The discovery of these vesicles and the demonstration that zinc sparks originate from them provides a quantitative framework for understanding how zinc fluxes regulate cellular processes. PMID:25615666

Heavy-ion beam induced effects in enriched gadolinium target films prepared by molecular plating

NASA Astrophysics Data System (ADS)

Mayorov, D. A.; Tereshatov, E. E.; Werke, T. A.; Frey, M. M.; Folden, C. M.

2017-09-01

A series of enriched gadolinium (Gd, Z = 64) targets was prepared using the molecular plating process for nuclear physics experiments at the Cyclotron Institute at Texas A&M University. After irradiation with 48Ca and 45Sc projectiles at center-of-target energies of Ecot = 3.8-4.7 MeV/u, the molecular films displayed visible discoloration. The morphology of the films was examined and compared to the intact target surface. The thin films underwent a heavy-ion beam-induced density change as identified by scanning electron microscopy and α-particle energy loss measurements. The films became thinner and more homogenous, with the transformation occurring early on in the irradiation. This transformation is best described as a crystalline-to-amorphous phase transition induced by atomic displacement and destruction of structural order of the original film. The chemical composition of the thin films was surveyed using energy dispersive spectroscopy and X-ray diffraction, with the results confirming the complex chemistry of the molecular films previously noted in other publications.

Alcohol-induced tolerance and physical dependence in mice with ethanol insensitive α1 GABAA receptors

PubMed Central

Werner, David F.; Swihart, Andrew R.; Ferguson, Carolyn; Lariviere, William R.; Harrison, Neil L.; Homanics, Gregg E.

2009-01-01

Background Although many people consume alcohol (ethanol), it remains unknown why some become addicted. Elucidating the molecular mechanisms of tolerance and physical dependence (withdrawal) may provide insight into alcohol addiction. While the exact molecular mechanisms of ethanol action are unclear, γ-aminobutyric acid type A receptors (GABAA-Rs) have been extensively implicated in ethanol action. The α1 GABAA-R subunit is associated with tolerance and physical dependence, but its exact role remains unknown. In this report, we tested the hypothesis that α1-GABAA-Rs mediate in part these effects of ethanol. Methods Ethanol-induced behavioral responses related to tolerance and physical dependence were investigated in knockin mice that have ethanol-insensitive α1 GABAA-Rs and wildtype controls. Acute functional tolerance (AFT) was assessed using the stationary dowel and loss of righting reflex assays. Chronic tolerance was assessed on the loss of righting reflex, fixed speed rotarod, hypothermia, and radiant tail flick assays following ten consecutive days of ethanol exposure. Withdrawal-related hyperexcitability was assessed by handling-induced convulsions following 3 cycles of ethanol vapor exposure/withdrawal. Immunoblots were used to assess α1 protein levels. Results Compared to controls, knockin mice displayed decreased AFT and chronic tolerance to ethanol-induced motor ataxia, and also displayed heightened ethanol-withdrawal hyperexcitability. No differences between wildtype and knockin mice were seen in other ethanol-induced behavioral measures. Following chronic exposure to ethanol, control mice displayed reductions in α1 protein levels, but knockins did not. Conclusions We conclude that α1-GABAA-Rs play a role in tolerance to ethanol-induced motor ataxia and withdrawal-related hyperexcitability. However, other aspects of behavioral tolerance and physical dependence do not rely on α1-containing GABAA-Rs. PMID:19032579

Mast-cell degranulation induced by physical stimuli involves the activation of transient-receptor-potential channel TRPV2.

PubMed

Zhang, D; Spielmann, A; Wang, L; Ding, G; Huang, F; Gu, Q; Schwarz, W

2012-01-01

A characteristic of mast cells is the degranulation in response to various stimuli. Here we have investigated the effects of various physical stimuli in the human mast-cell line HMC-1. We have shown that HMC-1 express the transient receptor potential channels TRPV1, TRPV2 and TRPV4. In the whole-cell patch-clamp configuration, increasing mechanical stress applied to the mast cell by hydrostatic pressure (-30 to -90 cm H(2)O applied via the patch pipette) induced a current that could be inhibited by 10 microM of ruthenium red. This current was also inhibited by 20 microM SKF96365, an inhibitor that is among TRPV channels specific for the TRPV2. A characteristic of TRPV2 is its activation by high noxious temperature; temperatures exceeding 50 °C induced a similar ruthenium-red-sensitive current. As another physical stimulus, we applied laser light of 640 nm. Here we have shown for the first time that the application of light (at 48 mW for 20 min) induced an SKF96365-sensitive current. All three physical stimuli that led to activation of SKF96365-sensitive current also induced pronounced degranulation in the mast cells, which could be blocked by ruthenium red or SKF96365. The results suggest that TRPV2 is activated by the three different types of physical stimuli. Activation of TRPV2 allows Ca(2+) ions to enter the cell, which in turn will induce degranulation. We, therefore, suggest that TRPV2 plays a key role in mast-cell degranulation in response to mechanical, heat and red laser-light stimulation.

Induced seismicity provides insight into why earthquake ruptures stop.

PubMed

Galis, Martin; Ampuero, Jean Paul; Mai, P Martin; Cappa, Frédéric

2017-12-01

Injection-induced earthquakes pose a serious seismic hazard but also offer an opportunity to gain insight into earthquake physics. Currently used models relating the maximum magnitude of injection-induced earthquakes to injection parameters do not incorporate rupture physics. We develop theoretical estimates, validated by simulations, of the size of ruptures induced by localized pore-pressure perturbations and propagating on prestressed faults. Our model accounts for ruptures growing beyond the perturbed area and distinguishes self-arrested from runaway ruptures. We develop a theoretical scaling relation between the largest magnitude of self-arrested earthquakes and the injected volume and find it consistent with observed maximum magnitudes of injection-induced earthquakes over a broad range of injected volumes, suggesting that, although runaway ruptures are possible, most injection-induced events so far have been self-arrested ruptures.

First-principles modeling of laser-matter interaction and plasma dynamics in nanosecond pulsed laser shock processing

NASA Astrophysics Data System (ADS)

Zhang, Zhongyang; Nian, Qiong; Doumanidis, Charalabos C.; Liao, Yiliang

2018-02-01

Nanosecond pulsed laser shock processing (LSP) techniques, including laser shock peening, laser peen forming, and laser shock imprinting, have been employed for widespread industrial applications. In these processes, the main beneficial characteristic is the laser-induced shockwave with a high pressure (in the order of GPa), which leads to the plastic deformation with an ultrahigh strain rate (105-106/s) on the surface of target materials. Although LSP processes have been extensively studied by experiments, few efforts have been put on elucidating underlying process mechanisms through developing a physics-based process model. In particular, development of a first-principles model is critical for process optimization and novel process design. This work aims at introducing such a theoretical model for a fundamental understanding of process mechanisms in LSP. Emphasis is placed on the laser-matter interaction and plasma dynamics. This model is found to offer capabilities in predicting key parameters including electron and ion temperatures, plasma state variables (temperature, density, and pressure), and the propagation of the laser shockwave. The modeling results were validated by experimental data.

On the tidal interaction between protoplanets and the primordial solar nebula. II - Self-consistent nonlinear interaction

NASA Technical Reports Server (NTRS)

Lin, D. N. C.; Papaloizou, J.

1986-01-01

A method to analyze the full nonlinear response and physical processes associated with the tidal interaction between a binary system and a thin disk in the steady state is presented. Using this approach, density wave propagation, induced by tidal interaction, may be studied for a wide range of sound speeds and viscosities. The effect of self-gravity may also be incorporated. The results of several calculations relevant to the tidal interaction between a protoplanet and the primordial solar nebula are also presented.

Electroweak radiative corrections to the top quark decay

NASA Astrophysics Data System (ADS)

Kuruma, Toshiyuki

1993-12-01

The top quark, once produced, should be an important window to the electroweak symmetry breaking sector. We compute electroweak radiative corrections to the decay process t→b+W + in order to extract information on the Higgs sector and to fix the background in searches for a possible new physics contribution. The large Yukawa coupling of the top quark induces a new form factor through vertex corrections and causes discrepancy from the tree-level longitudinal W-boson production fraction, but the effect is of order 1% or less for m H<1 TeV.

Acoustic Dirac degeneracy and topological phase transitions realized by rotating scatterers

NASA Astrophysics Data System (ADS)

Wen, Xinhua; Qiu, Chunyin; Lu, Jiuyang; He, Hailong; Ke, Manzhu; Liu, Zhengyou

2018-03-01

The artificial crystals for classical waves provide a good platform to explore the topological physics proposed originally in condensed matter systems. In this paper, acoustic Dirac degeneracy is realized by simply rotating the scatterers in sonic crystals, where the degeneracy is induced accidentally by modulating the scattering strength among the scatterers during the rotation process. This gives a flexible way to create a topological phase transition in acoustic systems. Edge states are further observed along the interface separating the two topologically distinct gapped sonic crystals.

The target material influence on the current pulse during high power pulsed magnetron sputtering

NASA Astrophysics Data System (ADS)

Moens, Filip; Konstantinidis, Stéphanos; Depla, Diederik

2017-10-01

The current-time characteristic during high power pulsed magnetron sputtering is measured under identical conditions for seventeen different target materials. Based on physical processes such as gas rarefaction, ion-induced electron emission, and electron impact ionization, two test parameters were derived that significantly correlate with specific features of the current-time characteristic: i) the peak current is correlated to the momentum transfer between the sputtered material and the argon gas, ii) while the observed current plateau after the peak is connected to the metal ionization rate.

Fiber pushout and interfacial shear in metal-matrix composites

NASA Technical Reports Server (NTRS)

Koss, Donald A.; Hellmann, John R.; Kallas, M. N.

1993-01-01

Recent thin-slice pushout tests have suggested that MMC matrix-fiber interface failure processes depend not only on such intrinsic factors as bond strength and toughness, and matrix plasticity, but such extrinsic factors as specimen configuration, thermally-induced residual stresses, and the mechanics associated with a given test. After detailing the contrasts in fiber-pullout and fiber-pushout mechanics, attention is given to selected aspects of thin-slice fiber pushout behavior illustrative of the physical nature of interfacial shear response and its dependence on both intrinsic and extrinsic factors.

Examination of contraction-induced muscle pain as a behavioral correlate of physical activity in women with and without fibromyalgia.

PubMed

Umeda, Masataka; Corbin, Lisa W; Maluf, Katrina S

2015-01-01

This study aimed to compare muscle pain intensity during a sustained isometric contraction in women with and without fibromyalgia (FM), and examine the association between muscle pain and self-reported levels of physical activity. Fourteen women with FM and 14 healthy women completed the study, where muscle pain ratings (MPRs) were obtained every 30 s during a 3 min isometric handgrip task at 25% maximal strength, and self-reported physical activity was quantified using the Baecke Physical Activity Questionnaire. Women with FM were less physically active than healthy controls. During the isometric contraction, MPR progressively increased in both groups at a comparable rate, but women with FM generally reported a greater intensity of muscle pain than healthy controls. Among all women, average MPR scores were inversely associated with self-reported physical activity levels. Women with FM exhibit augmented muscle pain during isometric contractions and reduced physical activity than healthy controls. Furthermore, contraction-induced muscle pain is inversely associated with physical activity levels. These observations suggest that augmented muscle pain may serve as a behavioral correlate of reduced physical activity in women with FM. Implications for Rehabilitation Women with fibromyalgia experience a greater intensity of localized muscle pain in a contracting muscle compared to healthy women. The intensity of pain during muscle contraction is inversely associated with the amount of physical activity in women with and without fibromyalgia. Future studies should determine whether exercise adherence can be improved by considering the relationship between contraction-induced muscle pain and participation in routine physical activity.

Vector Potential, Electromagnetic Induction and "Physical Meaning"

ERIC Educational Resources Information Center

Giuliani, G.

2010-01-01

A forgotten experiment by Andre Blondel (1914) proves, as held on the basis of theoretical arguments in a previous paper, that the time variation of the magnetic flux is not the cause of the induced emf; the physical agent is instead the vector potential through the term [equation omitted] (when the induced circuit is at rest). The "good…

Numerical investigation of electromagnetic pulse welded interfaces between dissimilar metals

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

Xu, Wei; Sun, Xin

Electromagnetic pulse welding (EMPW), an innovative high-speed joining technique, is a potential method for the automotive industry in joining and assembly of dissimilar lightweight metals with drastically different melting temperatures and other thermal physical properties, such as thermal conductivity and thermal expansion coefficients. The weld quality of EMPW is significantly affected by a variety of interacting physical phenomena including large plastic deformation, materials mixing, localized heating and rapid cooling, possible localized melting and subsequent diffusion and solidification, micro-cracking and void, etc. In the present study, a thermo-mechanically coupled dynamic model has been developed to quantitatively resolve the high-speed impact joiningmore » interface characteristics as well as the process-induced interface temperature evolution, defect formation and possible microstructural composition variation. Reasonably good agreement has been obtained between the predicted results and experimental measurements in terms of interfacial morphology characteristics. The modeling framework is expected to provide further understanding of the hierarchical interfacial features of the non-equilibrium material joining process and weld formation mechanisms involved in the EMPW operation, thus accelerating future development and deployment of this advanced joining technology.« less

Carbon Inputs From Riparian Vegetation Limit Oxidation of Physically Bound Organic Carbon Via Biochemical and Thermodynamic Processes: OC Oxidation Processes Across Vegetation

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

Graham, Emily B.; Tfaily, Malak M.; Crump, Alex R.

In light of increasing terrestrial carbon (C) transport across aquatic boundaries, the mechanisms governing organic carbon (OC) oxidation along terrestrial-aquatic interfaces are crucial to future climate predictions. Here, we investigate biochemistry, metabolic pathways, and thermodynamics corresponding to OC oxidation in the Columbia River corridor. We leverage natural vegetative differences to encompass variation in terrestrial C inputs. Our results suggest that decreases in terrestrial C deposition associated with diminished riparian vegetation induce oxidation of physically-bound (i.e., mineral and microbial) OC at terrestrial-aquatic interfaces. We also find that contrasting metabolic pathways oxidize OC in the presence and absence of vegetation and—in directmore » conflict with the concept of ‘priming’—that inputs of water-soluble and thermodynamically-favorable terrestrial OC protects bound-OC from oxidation. Based on our results, we propose a mechanistic conceptualization of OC oxidation along terrestrial-aquatic interfaces that can be used to model heterogeneous patterns of OC loss under changing land cover distributions.« less

Effects of Plant Oil Interesterified Triacylglycerols on Lipemia and Human Health

PubMed Central

Alfieri, Andreina; Vitucci, Daniela; Orrù, Stefania; Buono, Pasqualina; Mancini, Annamaria

2017-01-01

The position of the fatty acids (sn-1, sn-2 and sn-3) (stereospecific numbering (sn)) in triacylglycerol (TAG) molecules produces a characteristic stereospecificity that defines the physical properties of the fats and influences their absorption, metabolism and uptake into tissues. Fat interesterification is a process that implies a positional distribution of fatty acids (FAs) within the TAG molecules, generating new TAG species, without affecting the FA cis-trans natural balance. The interesterified (IE) fats, frequently used in the food industry comprise fats that are rich in long-chain saturated FAs, such as palmitic acid (16:0) and stearic acid (18:0). Within the interesterified fats, a critical role is played by FA occupying the sn-2 position; in fact, the presence of an unsaturated FA in this specific position influences early metabolic processing and postprandial clearance that in turn could induce atherogenesis and thrombogenesis events. Here, we provide an overview on the role of TAG structures and interesterified palmitic and stearic acid-rich fats on fasting and postprandial lipemia, focusing our attention on their physical properties and their effects on human health. PMID:29301208

Neutron coincidence measurements when nuclear parameters vary during the multiplication process

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

Lu, Ming-Shih; Teichmann, T.

1995-07-01

In a recent paper, a physical/mathematical model was developed for neutron coincidence counting, taking explicit account of neutron absorption and leakage, and using dual probability generating function to derive explicit formulae for the single and multiple count-rates in terms of the physical parameters of the system. The results of this modeling proved very successful in a number of cases in which the system parameters (neutron reaction cross-sections, detection probabilities, etc.) remained the same at the various stages of the process (i.e. from collision to collision). However, there are practical circumstances in which such system parameters change from collision to collision,more » and it is necessary to accommodate these, too, in a general theory, applicable to such situations. For instance, in the case of the neutron coincidence collar (NCC), the parameters for the initial, spontaneous fission neutrons, are not the same as those for the succeeding induced fission neutrons, and similar situations can be envisaged for certain other experimental configurations. This present document shows how the previous considerations can be elaborated to embrace these more general requirements.« less

Quantum indistinguishability in chemical reactions.

PubMed

Fisher, Matthew P A; Radzihovsky, Leo

2018-05-15

Quantum indistinguishability plays a crucial role in many low-energy physical phenomena, from quantum fluids to molecular spectroscopy. It is, however, typically ignored in most high-temperature processes, particularly for ionic coordinates, implicitly assumed to be distinguishable, incoherent, and thus well approximated classically. We explore enzymatic chemical reactions involving small symmetric molecules and argue that in many situations a full quantum treatment of collective nuclear degrees of freedom is essential. Supported by several physical arguments, we conjecture a "quantum dynamical selection" (QDS) rule for small symmetric molecules that precludes chemical processes that involve direct transitions from orbitally nonsymmetric molecular states. As we propose and discuss, the implications of the QDS rule include ( i ) a differential chemical reactivity of para- and orthohydrogen, ( ii ) a mechanism for inducing intermolecular quantum entanglement of nuclear spins, ( iii ) a mass-independent isotope fractionation mechanism, ( iv ) an explanation of the enhanced chemical activity of "reactive oxygen species", ( v ) illuminating the importance of ortho-water molecules in modulating the quantum dynamics of liquid water, and ( vi ) providing the critical quantum-to-biochemical linkage in the nuclear spin model of the (putative) quantum brain, among others.

Inelastic electron tunneling mediated by a molecular quantum rotator

NASA Astrophysics Data System (ADS)

Sugimoto, Toshiki; Kunisada, Yuji; Fukutani, Katsuyuki

2017-12-01

Inelastic electron tunneling (IET) accompanying nuclear motion is not only of fundamental physical interest but also has strong impacts on chemical and biological processes in nature. Although excitation of rotational motion plays an important role in enhancing electric conductance at a low bias, the mechanism of rotational excitation remains veiled. Here, we present a basic theoretical framework of IET that explicitly takes into consideration quantum angular momentum, focusing on a molecular H2 rotator trapped in a nanocavity between two metallic electrodes as a model system. It is shown that orientationally anisotropic electrode-rotator coupling is the origin of angular-momentum exchange between the electron and molecule; we found that the anisotropic coupling imposes rigorous selection rules in rotational excitation. In addition, rotational symmetry breaking induced by the anisotropic potential lifts the degeneracy of the energy level of the degenerated rotational state of the quantum rotator and tunes the threshold bias voltage that triggers rotational IET. Our theoretical results provide a paradigm for physical understanding of the rotational IET process and spectroscopy, as well as molecular-level design of electron-rotation coupling in nanoelectronics.

Neural Bases of Social Anxiety Disorder: Emotional Reactivity and Cognitive Regulation During Social and Physical Threat

PubMed Central

Goldin, Philippe R.; Manber, Tali; Hakimi, Shabnam; Canli, Turhan; Gross, James J.

2014-01-01

Context Social anxiety disorder is thought to involve emotional hyper-reactivity, cognitive distortions, and ineffective emotion regulation. While the neural bases of emotional reactivity to social stimuli have been described, the neural bases of emotional reactivity and cognitive regulation during social and physical threat, and their relationship to social anxiety symptom severity, have yet to be investigated. Objective This study investigated behavioral and neural correlates of emotional reactivity and cognitive regulation in patients and controls during processing of social and physical threat stimuli. Design Participants were trained to implement cognitive-linguistic regulation of emotional reactivity induced by social (harsh facial expressions) and physical (violent scenes) threat while undergoing functional magnetic resonance imaging and providing behavioral ratings of negative emotion experience. Setting Academic psychology department. Participants 15 adults with social anxiety disorder and 17 demographically-matched healthy controls. Main Outcome Measures Blood oxygen level dependent signal and negative emotion ratings. Results Behaviorally, patients reported greater negative emotion than controls during social and physical threat, but showed equivalent reduction in negative emotion following cognitive regulation. Neurally, viewing social threat resulted in greater emotion-related neural responses in patients than controls, with social anxiety symptom severity related to activity in a network of emotion and attention processing regions in patients only. Viewing physical threat produced no between-group differences. Regulation during social threat resulted in greater cognitive and attention regulation-related brain activation in controls compared to patients. Regulation during physical threat produced greater cognitive control-related response (i.e., right DLPFC) in patients compared to controls. Conclusions Compared to controls, patients demonstrated exaggerated negative emotion reactivity and reduced cognitive regulation related neural activation, specifically for social threat stimuli. These findings help to elucidate potential neural mechanisms of emotion regulation that might serve as biomarkers for interventions for social anxiety disorder. PMID:19188539

Investigating the rupture direction of induced earthquakes in the Central US using empirical Green's functions

NASA Astrophysics Data System (ADS)

Lui, S. K. Y.; Huang, Y.

2017-12-01

A clear understanding of the source physics of induced seismicity is the key to effective seismic hazard mitigation. In particular, resolving their rupture processes can shed lights on the stress state prior to the main shock, as well as ground motion response. Recent numerical models suggest that, compared to their tectonic counterpart, induced earthquake rupture is more prone to propagate unilaterally toward the injection well where fluid pressure is high. However, this is also dependent on the location of the injection relative to the fault and yet to be compared with field data. In this study, we utilize the rich pool of seismic data in the central US to constrain the rupture processes of major induced earthquakes. By implementing a forward-modeling method, we take smaller earthquake recordings as empirical Green's functions (eGf) to simulate the rupture direction of the beginning motion generated by large events. One advantage of the empirical approach is to bypass the fundamental difficulty in resolving path and site effects. We selected eGf events that are close to the target events both in space and time. For example, we use a Mw 3.6 aftershock approximately 3 km from the 2011 Mw 5.7 earthquake in Prague, OK as its eGf event. Preliminary results indicate a southwest rupture for the Prague main shock, which possibly implies a higher fluid pressure concentration on the northeast end of the fault prior to the rupture. We will present further results on other Mw > 4.5 earthquakes in the States of Oklahoma and Kansas. With additional seismic stations installed in the past few years, events such as the 2014 Mw 4.9 Milan earthquake and the 2016 Mw 5.8 Pawnee earthquake are potential candidates with useful eGfs, as they both have good data coverage and a substantial number of aftershocks nearby. We will discuss the implication of our findings for the causative relationships between the injection operations and the induced rupture process.

Physical exercise in overweight to obese individuals induces metabolic- and neurotrophic-related structural brain plasticity

PubMed Central

Mueller, Karsten; Möller, Harald E.; Horstmann, Annette; Busse, Franziska; Lepsien, Jöran; Blüher, Matthias; Stumvoll, Michael; Villringer, Arno; Pleger, Burkhard

2015-01-01

Previous cross-sectional studies on body-weight-related alterations in brain structure revealed profound changes in the gray matter (GM) and white matter (WM) that resemble findings obtained from individuals with advancing age. This suggests that obesity may lead to structural brain changes that are comparable with brain aging. Here, we asked whether weight-loss-dependent improved metabolic and neurotrophic functioning parallels the reversal of obesity-related alterations in brain structure. To this end we applied magnetic resonance imaging (MRI) together with voxel-based morphometry and diffusion-tensor imaging in overweight to obese individuals who participated in a fitness course with intensive physical training twice a week over a period of 3 months. After the fitness course, participants presented, with inter-individual heterogeneity, a reduced body mass index (BMI), reduced serum leptin concentrations, elevated high-density lipoprotein-cholesterol (HDL-C), and alterations of serum brain-derived neurotrophic factor (BDNF) concentrations suggesting changes of metabolic and neurotrophic function. Exercise-dependent changes in BMI and serum concentration of BDNF, leptin, and HDL-C were related to an increase in GM density in the left hippocampus, the insular cortex, and the left cerebellar lobule. We also observed exercise-dependent changes of diffusivity parameters in surrounding WM structures as well as in the corpus callosum. These findings suggest that weight-loss due to physical exercise in overweight to obese participants induces profound structural brain plasticity, not primarily of sensorimotor brain regions involved in physical exercise, but of regions previously reported to be structurally affected by an increased body weight and functionally implemented in gustation and cognitive processing. PMID:26190989

Hippocampal microRNA-mRNA regulatory network is affected by physical exercise.

PubMed

Fernandes, Jansen; Vieira, Andre Schwambach; Kramer-Soares, Juliana Carlota; Da Silva, Eduardo Alves; Lee, Kil Sun; Lopes-Cendes, Iscia; Arida, Ricardo Mario

2018-05-08

It is widely known that physical activity positively affects the overall health and brain function. Recently, microRNAs (miRNAs) have emerged as potential regulators of numerous biological processes within the brain. These molecules modulate gene expression post-transcriptionally by inducing mRNA degradation and inhibiting the translation of target mRNAs. To verify whether the procognitive effects of physical exercise are accompanied by changes in the activity of miRNA-mRNA network in the brain, differential expression analysis was performed in the hippocampus of control (CTL) and exercised (Ex) rats subjected to 4 weeks of treadmill exercise. Cognition was evaluated by a multiple trial inhibitory avoidance (MTIA) task and Illumina next-generation sequencing (NGS) was used for miRNA and mRNA profiling. Exercise improved memory retention but not acquisition in the MTIA task. It was observed that 4 miRNAs and 54 mRNAs were significantly altered in the hippocampus of Ex2 (euthanized 2 h after the last exercise bout) group when compared to CTL group. Bioinformatic analysis showed an inverse correlation between 3 miRNAs and 6 target mRNAs. The miRNAs miR-129-1-3p and miR-144-5p were inversely correlated to the Igfbp5 and Itm2a, respectively, and the miR-708-5p presented an inverse correlation with Cdkn1a, Per2, Rt1-a2. The exercise-induced memory improvements are accompanied by changes in hippocampal miRNA-mRNA regulatory network. Physical exercise can affect brain function through modulation of epigenetics mechanisms involving miRNA regulation. Copyright © 2018 Elsevier B.V. All rights reserved.

Prevention of bedrest-induced physical deconditioning by daily dobutamine infusions. Implications for drug-induced physical conditioning.

PubMed Central

Sullivan, M J; Binkley, P F; Unverferth, D V; Ren, J H; Boudoulas, H; Bashore, T M; Merola, A J; Leier, C V

1985-01-01

The effects of intermittent infusions of dobutamine were studied in young normal male subjects during a period of bedrest deconditioning to determine whether this synthetic catechol affects physical conditioning processes in humans. 24 volunteers were placed at bedrest and randomized to daily 2-h treatments of saline infusions (control), dobutamine infusions, or maintenance exercise (control). Exercise, hemodynamic, and metabolic studies were performed at base line and at the termination of the 3-wk treatment period. Maximal exercise (duration, oxygen consumption, and workload) fell for the saline group and remained unchanged for the dobutamine and exercise groups. Hemodynamics during exercise were maintained the same as pretreatment base line for the dobutamine and exercise groups, whereas stroke volume and cardiac output dropped and heart rate rose for the saline group. The metabolic profile showed an increased blood lactate response at rest and during submaximal exercise after 3 wk of bedrest for the saline group, and essentially no change for the exercise and the dobutamine groups. Extraction of oxygen across the exercising lower limb rose for the dobutamine group, as did the activity of the skeletal muscle oxidative enzymes, citrate synthetase, and succinate dehydrogenase. In contrast to the exercise control group, the saline and dobutamine groups developed orthostatic hypotension, tachycardia, and accentuation of the renin-aldosterone response over the 3-wk treatment period; for the saline group, this is best explained by the observed fall in blood volume and for the dobutamine group, by the blunting of vascular vasoconstrictive responses. During a period of bedrest deconditioning in humans, infusions of dobutamine maintain many of the physiologic expressions of physical conditioning. PMID:3932470

Microfibrous Solid Dispersions of Poorly Water-Soluble Drugs Produced via Centrifugal Spinning: Unexpected Dissolution Behavior on Recrystallization.

PubMed

Marano, Stefania; Barker, Susan A; Raimi-Abraham, Bahijja T; Missaghi, Shahrzad; Rajabi-Siahboomi, Ali; Aliev, Abil E; Craig, Duncan Q M

2017-05-01

Temperature-controlled, solvent-free centrifugal spinning may be used as a means of rapid production of amorphous solid dispersions in the form of drug-loaded sucrose microfibers. However, due to the high content of amorphous sucrose in the formulations, such microfibers may be highly hygroscopic and unstable on storage. In this study, we explore both the effects of water uptake of the microfibers and the consequences of deliberate recrystallization for the associated dissolution profiles. The stability of sucrose microfibers loaded with three selected BCS class II model drugs (itraconazole (ITZ), olanzapine (OLZ), and piroxicam (PRX)) was investigated under four different relative humidity conditions (11, 33, 53, and 75% RH) at 25 °C for 8 months, particularly focusing on the effect of the highest level of moisture (75% RH) on the morphology, size, drug distribution, physical state, and dissolution performance of microfibers. While all samples were stable at 11% RH, at 33% RH the ITZ-sucrose system showed greater resistance against devitrification compared to the OLZ- and PRX-sucrose systems. For all three samples, the freshly prepared microfibers showed enhanced dissolution and supersaturation compared to the drug alone and physical mixes; surprisingly, the dissolution advantage was largely maintained or even enhanced (in the case of ITZ) following the moisture-induced recrystallization under 75% RH. Therefore, this study suggests that the moisture-induced recrystallization process may result in considerable dissolution enhancement compared to the drug alone, while overcoming the physical stability risks associated with the amorphous state.

Augmenting endogenous repair of soft tissues with nanofibre scaffolds

PubMed Central

Snelling, Sarah; Dakin, Stephanie; Carr, Andrew

2018-01-01

As our ability to engineer nanoscale materials has developed we can now influence endogenous cellular processes with increasing precision. Consequently, the use of biomaterials to induce and guide the repair and regeneration of tissues is a rapidly developing area. This review focuses on soft tissue engineering, it will discuss the types of biomaterial scaffolds available before exploring physical, chemical and biological modifications to synthetic scaffolds. We will consider how these properties, in combination, can provide a precise design process, with the potential to meet the requirements of the injured and diseased soft tissue niche. Finally, we frame our discussions within clinical trial design and the regulatory framework, the consideration of which is fundamental to the successful translation of new biomaterials. PMID:29695606

Higher-order modulation instability in nonlinear fiber optics.

PubMed

Erkintalo, Miro; Hammani, Kamal; Kibler, Bertrand; Finot, Christophe; Akhmediev, Nail; Dudley, John M; Genty, Goëry

2011-12-16

We report theoretical, numerical, and experimental studies of higher-order modulation instability in the focusing nonlinear Schrödinger equation. This higher-order instability arises from the nonlinear superposition of elementary instabilities, associated with initial single breather evolution followed by a regime of complex, yet deterministic, pulse splitting. We analytically describe the process using the Darboux transformation and compare with experiments in optical fiber. We show how a suitably low frequency modulation on a continuous wave field induces higher-order modulation instability splitting with the pulse characteristics at different phases of evolution related by a simple scaling relationship. We anticipate that similar processes are likely to be observed in many other systems including plasmas, Bose-Einstein condensates, and deep water waves. © 2011 American Physical Society

Tuning relaxation dynamics and mechanical properties of polymer films of identical thickness

NASA Astrophysics Data System (ADS)

Kchaou, Marwa; Alcouffe, Pierre; Chandran, Sivasurender; Cassagnau, Philippe; Reiter, Günter; Al Akhrass, Samer

2018-03-01

Using dewetting as a characterization tool, we demonstrate that physical properties of thin polymer films can be regulated and tuned by employing variable processing conditions. For different molecular weights, the variable behavior of polystyrene films of identical thickness, prepared along systematically altered pathways, became predictable through a single parameter P , defined as the ratio of time required over time available for the equilibration of polymers. In particular, preparation-induced residual stresses, the corresponding relaxation times as well as the rupture probability of such films (of identical thickness) varied by orders of magnitude following scaling relations with P . Our experimental findings suggest that we can predictably enhance properties and hence maximize the performance of thin polymer films via appropriately chosen processing conditions.

Fractional Stochastic Field Theory

NASA Astrophysics Data System (ADS)

Honkonen, Juha

2018-02-01

Models describing evolution of physical, chemical, biological, social and financial processes are often formulated as differential equations with the understanding that they are large-scale equations for averages of quantities describing intrinsically random processes. Explicit account of randomness may lead to significant changes in the asymptotic behaviour (anomalous scaling) in such models especially in low spatial dimensions, which in many cases may be captured with the use of the renormalization group. Anomalous scaling and memory effects may also be introduced with the use of fractional derivatives and fractional noise. Construction of renormalized stochastic field theory with fractional derivatives and fractional noise in the underlying stochastic differential equations and master equations and the interplay between fluctuation-induced and built-in anomalous scaling behaviour is reviewed and discussed.

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

Pritychenko, B.; Mughabghab, S.F.

We present calculations of neutron thermal cross sections, Westcott factors, resonance integrals, Maxwellian-averaged cross sections and astrophysical reaction rates for 843 ENDF materials using data from the major evaluated nuclear libraries and European activation file. Extensive analysis of newly-evaluated neutron reaction cross sections, neutron covariances, and improvements in data processing techniques motivated us to calculate nuclear industry and neutron physics quantities, produce s-process Maxwellian-averaged cross sections and astrophysical reaction rates, systematically calculate uncertainties, and provide additional insights on currently available neutron-induced reaction data. Nuclear reaction calculations are discussed and new results are presented. Due to space limitations, the present papermore » contains only calculated Maxwellian-averaged cross sections and their uncertainties. The complete data sets for all results are published in the Brookhaven National Laboratory report.« less

Two-potential approach for electron-molecular collisions at intermediate and high energies - Application to e-N2 scatterings

NASA Technical Reports Server (NTRS)

Choi, B. H.; Poe, R. T.; Sun, J. C.; Shan, Y.

1979-01-01

A general theoretical approach is proposed for the calculation of elastic, vibrational, and rotational transitions for electron-molecule scattering at intermediate and high-electron-impact energies. In this formulation, contributions to the scattering process come from the incoherent sum of two dominant potentials: a short-range shielded nuclear Coulomb potential from individual atomic centers, and a permanent/induced long-range potential. Application to e-N2 scattering from 50-500 eV incident electron energies has yielded good agreement with absolutely calibrated experiments. Comparisons with other theoretical approaches are made. The physical picture as well as the general features of electron-molecule scattering process are discussed within the framework of the two-potential approach.

Progress in piezo-phototronic effect modulated photovoltaics.

PubMed

Que, Miaoling; Zhou, Ranran; Wang, Xiandi; Yuan, Zuqing; Hu, Guofeng; Pan, Caofeng

2016-11-02

Wurtzite structured materials, like ZnO, GaN, CdS, and InN, simultaneously possess semiconductor and piezoelectric properties. The inner-crystal piezopotential induced by external strain can effectively tune/control the carrier generation, transport and separation/combination processes at the metal-semiconductor contact or p-n junction, which is called the piezo-phototronic effect. This effect can efficiently enhance the performance of photovoltaic devices based on piezoelectric semiconductor materials by utilizing the piezo-polarization charges at the junction induced by straining, which can modulate the energy band of the piezoelectric material and then accelerate or prevent the separation process of the photon-generated electrons and vacancies. This paper introduces the fundamental physics principles of the piezo-phototronic effect, and reviews recent progress in piezo-phototronic effect enhanced solar cells, including solar cells based on semiconductor nanowire, organic/inorganic materials, quantum dots, and perovskite. The piezo-phototronic effect is suggested as a suitable basis for the development of an innovative method to enhance the performance of solar cells based on piezoelectric semiconductors by applied extrinsic strains, which might be appropriate for fundamental research and potential applications in various areas of optoelectronics.

Radiation Failures in Intel 14nm Microprocessors

NASA Technical Reports Server (NTRS)

Bossev, Dobrin P.; Duncan, Adam R.; Gadlage, Matthew J.; Roach, Austin H.; Kay, Matthew J.; Szabo, Carl; Berger, Tammy J.; York, Darin A.; Williams, Aaron; LaBel, K.;

Progress in piezo-phototronic effect modulated photovoltaics

NASA Astrophysics Data System (ADS)

Que, Miaoling; Zhou, Ranran; Wang, Xiandi; Yuan, Zuqing; Hu, Guofeng; Pan, Caofeng

2016-11-01

Wurtzite structured materials, like ZnO, GaN, CdS, and InN, simultaneously possess semiconductor and piezoelectric properties. The inner-crystal piezopotential induced by external strain can effectively tune/control the carrier generation, transport and separation/combination processes at the metal-semiconductor contact or p-n junction, which is called the piezo-phototronic effect. This effect can efficiently enhance the performance of photovoltaic devices based on piezoelectric semiconductor materials by utilizing the piezo-polarization charges at the junction induced by straining, which can modulate the energy band of the piezoelectric material and then accelerate or prevent the separation process of the photon-generated electrons and vacancies. This paper introduces the fundamental physics principles of the piezo-phototronic effect, and reviews recent progress in piezo-phototronic effect enhanced solar cells, including solar cells based on semiconductor nanowire, organic/inorganic materials, quantum dots, and perovskite. The piezo-phototronic effect is suggested as a suitable basis for the development of an innovative method to enhance the performance of solar cells based on piezoelectric semiconductors by applied extrinsic strains, which might be appropriate for fundamental research and potential applications in various areas of optoelectronics.

Sources and physical processes responsible for OH/H2O in the lunar soil as revealed by the Moon Mineralogy Mapper (M3)

USGS Publications Warehouse

McCord, T.B.; Taylor, L.A.; Combe, J.-P.; Kramer, G.; Pieters, C.M.; Sunshine, J.M.; Clark, R.N.

2011-01-01

Analysis of two absorption features near 3 m in the lunar reflectance spectrum, observed by the orbiting M3 spectrometer and interpreted as being due to OH and H2O, is presented, and the results are used to discuss the processes producing these molecules. This analysis focuses on the dependence of the absorptions on lunar physical properties, including composition, illumination, latitude, and temperature. Solar wind proton-induced hydroxylation is proposed as the creation process, and its products could be a source for other reported types of hydrogen-rich material and water. The irregular and damaged fine-grained lunar soil seems especially adapted for trapping solar wind protons and forming OH owing to abundant dangling oxygen bonds. The M3 data reveal that the strengths of the two absorptions are correlated and widespread, and both are correlated with lunar composition but in different ways. Feldspathic material seems richer in OH. These results seem to rule out water from the lunar interior and cometary infall as major sources. There appear to be correlations of apparent band strengths with time of day and lighting conditions. However, thermal emission from the Moon reduces the apparent strengths of the M3 absorptions, and its removal is not yet completely successful. Further, many of the lunar physical properties are themselves intercorrelated, and so separating these dependencies on the absorptions is difficult, due to the incomplete M3 data set. This process should also operate on other airless silicate surfaces, such as Mercury and Vesta, which will be visited by the Dawn spacecraft in mid-2011. Copyright 2011 by the American Geophysical Union.

Sources and physical processes responsible for OH/H2O in the lunarsoil as revealed by the Moon Mineralogy Mapper (M3)

USGS Publications Warehouse

McCord, T.B.; Taylor, L.A.; Combe, J.-P.; Kramer, G.; C.M. Pieters,; Sunshine, J.M.; Clark, R.N.

2011-01-01

Analysis of two absorption features near 3 μm in the lunar reflectance spectrum, observed by the orbiting M3 spectrometer and interpreted as being due to OH and H2O, is presented, and the results are used to discuss the processes producing these molecules. This analysis focuses on the dependence of the absorptions on lunar physical properties, including composition, illumination, latitude, and temperature. Solar wind proton-induced hydroxylation is proposed as the creation process, and its products could be a source for other reported types of hydrogen-rich material and water. The irregular and damaged fine-grained lunar soil seems especially adapted for trapping solar wind protons and forming OH owing to abundant dangling oxygen bonds. The M3data reveal that the strengths of the two absorptions are correlated and widespread, and both are correlated with lunar composition but in different ways. Feldspathic material seems richer in OH. These results seem to rule out water from the lunar interior and cometary infall as major sources. There appear to be correlations of apparent band strengths with time of day and lighting conditions. However, thermal emission from the Moon reduces the apparent strengths of the M3absorptions, and its removal is not yet completely successful. Further, many of the lunar physical properties are themselves intercorrelated, and so separating these dependencies on the absorptions is difficult, due to the incomplete M3 data set. This process should also operate on other airless silicate surfaces, such as Mercury and Vesta, which will be visited by the Dawn spacecraft in mid-2011.

Hydro-mechanical modelling of induced seismicity during the deep geothermal project in St. Gallen, Switzerland

NASA Astrophysics Data System (ADS)

Zbinden, Dominik; Rinaldi, Antonio Pio; Kraft, Toni; Diehl, Tobias; Wiemer, Stefan

2017-04-01

The St. Gallen deep geothermal project in 2013 was the second geothermal project in Switzerland with the objective of power production after the Enhanced Geothermal System in Basel in 2006. In St. Gallen, the seismic risk was expected to be smaller than in Basel, since the hydrothermal resource was an aquifer at a depth of about 4 km, not expected to require permeability enhancement and associated hydroshearing of the rock. However, after an injectivity test and two acid stimulations, unexpected gas release from an unidentified source forced the operators to inject drilling mud into the well to fight the gas kick. Subsequently, several seismic events were induced, the largest one having a local magnitude of 3.5, which was distinctly felt by the nearby living population. Even though the induced seismicity could not be handled properly, the community still strongly supported the geothermal project. The project was however halted because the target formation was not as permeable as required to deliver sufficient power. Still, controlling induced seismicity during deep geothermal projects is a key factor to successfully operate future geothermal projects. Hence, it is crucial to understand the physical relations of fluid injection, pressure and stress response at reservoir depth as well as associated induced seismicity. To date, these processes are yet not fully understood. In this study, we aim at developing a hydro-mechanical model reproducing the main features of the induced seismic sequence at the St. Gallen geothermal site. Here, we present the conceptual model and preliminary results accounting for hydraulic and mechanical parameters from the geothermal well, geological information from a seismic survey conducted in the St. Gallen region, and actual fluid injection rates from the injectivity tests. In a future step, we are going to use this model to simulate the physical interaction of injected fluid, gas release, hydraulic response of the rock, and induced seismicity during the St. Gallen project. The results will then allow us to more accurately estimate the seismic hazard for future geothermal projects.

Transcriptional activation by MEIS1A in response to protein kinase A signaling requires the transducers of regulated CREB family of CREB co-activators.

PubMed

Goh, Siew-Lee; Looi, Yvonne; Shen, Hui; Fang, Jun; Bodner, Caroline; Houle, Martin; Ng, Andy Cheuk-Him; Screaton, Robert A; Featherstone, Mark

2009-07-10

The transcription factor encoded by the murine ecotropic integration site 1 gene (MEIS1) is a partner of HOX and PBX proteins. It has been implicated in embryonic patterning and leukemia, and causally linked to restless legs syndrome. The MEIS1A C terminus harbors a transcriptional activation domain that is stimulated by protein kinase A (PKA) in a manner dependent on the co-activator of cAMP response element-binding protein (CREB), CREB-binding protein (CBP). We explored the involvement of another mediator of PKA-inducible transcription, namely the CREB co-activators transducers of regulated CREB activity (TORCs). Overexpression of TORC1 or TORC2 bypassed PKA for activation by MEIS1A. Co-immunoprecipitation experiments demonstrated a physical interaction between MEIS1 and TORC2 that is dependent on the MEIS1A C terminus, whereas chromatin immunoprecipitation revealed PKA-inducible recruitment of MEIS1, PBX1, and TORC2 on the MEIS1 target genes Hoxb2 and Meis1. The MEIS1 interaction domain on TORC1 was mapped to the N-terminal coiled-coil region, and TORC1 mutants lacking this domain attenuated the response to PKA on a natural MEIS1A target enhancer. Thus, TORCs physically cooperate with MEIS1 to achieve PKA-inducible transactivation through the MEIS1A C terminus, suggesting a concerted action in developmental and oncogenic processes.

Transcriptional Activation by MEIS1A in Response to Protein Kinase A Signaling Requires the Transducers of Regulated CREB Family of CREB Co-activators*

PubMed Central

Goh, Siew-Lee; Looi, Yvonne; Shen, Hui; Fang, Jun; Bodner, Caroline; Houle, Martin; Ng, Andy Cheuk-Him; Screaton, Robert A.; Featherstone, Mark

2009-01-01

The transcription factor encoded by the murine ecotropic integration site 1 gene (MEIS1) is a partner of HOX and PBX proteins. It has been implicated in embryonic patterning and leukemia, and causally linked to restless legs syndrome. The MEIS1A C terminus harbors a transcriptional activation domain that is stimulated by protein kinase A (PKA) in a manner dependent on the co-activator of cAMP response element-binding protein (CREB), CREB-binding protein (CBP). We explored the involvement of another mediator of PKA-inducible transcription, namely the CREB co-activators transducers of regulated CREB activity (TORCs). Overexpression of TORC1 or TORC2 bypassed PKA for activation by MEIS1A. Co-immunoprecipitation experiments demonstrated a physical interaction between MEIS1 and TORC2 that is dependent on the MEIS1A C terminus, whereas chromatin immunoprecipitation revealed PKA-inducible recruitment of MEIS1, PBX1, and TORC2 on the MEIS1 target genes Hoxb2 and Meis1. The MEIS1 interaction domain on TORC1 was mapped to the N-terminal coiled-coil region, and TORC1 mutants lacking this domain attenuated the response to PKA on a natural MEIS1A target enhancer. Thus, TORCs physically cooperate with MEIS1 to achieve PKA-inducible transactivation through the MEIS1A C terminus, suggesting a concerted action in developmental and oncogenic processes. PMID:19473990

A Self-Limiting Electro-Ablation Technique for the Top-Down Synthesis of Large-Area Monolayer Flakes of 2D Materials

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

Das, Saptarshi; Bera, Mrinal K.; Tong, Sheng

2016-06-21

We report the discovery of an electrochemical process that converts two dimensional layered materials of arbitrary thicknesses into monolayers. The lateral dimensions of the monolayers obtained by the process within a few seconds time at room temperature were as large as 0.5 mm. The temporal and spatial dynamics of this physical phenomenon, studied on MoS2 flakes using ex-situ AFM imaging, Raman mapping, and photoluminescence measurements trace the origin of monolayer formation to a substrate-assisted self-limiting electrochemical ablation process. Electronic structure and atomistic calculations point to the interplay between three essential factors in the process: (1) strong covalent interaction of monolayermore » MoS2 with the substrate; (2) electric-field induced differences in Gibbs free energy of exfoliation; (3) dispersion of MoS2 in aqueous solution of hydrogen peroxide. This process was successful in obtaining monolayers of other 2D transition metal dichalcogenides, like WS2 and MoTe2 as well.« less

Depletion of key protein components of the RISC pathway impairs pre-ribosomal RNA processing.

PubMed

Liang, Xue-Hai; Crooke, Stanley T

2011-06-01

Little is known about whether components of the RNA-induced silencing complex (RISC) mediate the biogenesis of RNAs other than miRNA. Here, we show that depletion of key proteins of the RISC pathway by antisense oligonucleotides significantly impairs pre-rRNA processing in human cells. In cells depleted of Drosha or Dicer, different precursors to 5.8S rRNA strongly accumulated, without affecting normal endonucleolytic cleavages. Moderate yet distinct processing defects were also observed in Ago2-depleted cells. Physical links between pre-rRNA and these proteins were identified by co-immunoprecipitation analyses. Interestingly, simultaneous depletion of Dicer and Drosha led to a different processing defect, causing slower production of 28S rRNA and its precursor. Both Dicer and Ago2 were detected in the nuclear fraction, and reduction of Dicer altered the structure of the nucleolus, where pre-rRNA processing occurs. Together, these results suggest that Drosha and Dicer are implicated in rRNA biogenesis.

Anisotropic diamond etching through thermochemical reaction between Ni and diamond in high-temperature water vapour.

PubMed

Nagai, Masatsugu; Nakanishi, Kazuhiro; Takahashi, Hiraku; Kato, Hiromitsu; Makino, Toshiharu; Yamasaki, Satoshi; Matsumoto, Tsubasa; Inokuma, Takao; Tokuda, Norio

2018-04-27

Diamond possesses excellent physical and electronic properties, and thus various applications that use diamond are under development. Additionally, the control of diamond geometry by etching technique is essential for such applications. However, conventional wet processes used for etching other materials are ineffective for diamond. Moreover, plasma processes currently employed for diamond etching are not selective, and plasma-induced damage to diamond deteriorates the device-performances. Here, we report a non-plasma etching process for single crystal diamond using thermochemical reaction between Ni and diamond in high-temperature water vapour. Diamond under Ni films was selectively etched, with no etching at other locations. A diamond-etching rate of approximately 8.7 μm/min (1000 °C) was successfully achieved. To the best of our knowledge, this rate is considerably greater than those reported so far for other diamond-etching processes, including plasma processes. The anisotropy observed for this diamond etching was considerably similar to that observed for Si etching using KOH.

Microarray analyses reveal novel targets of exercise-induced stress resistance in the dorsal raphe nucleus

PubMed Central

Loughridge, Alice B.; Greenwood, Benjamin N.; Day, Heidi E. W.; McQueen, Matthew B.; Fleshner, Monika

2013-01-01

Serotonin (5-HT) is implicated in the development of stress-related mood disorders in humans. Physical activity reduces the risk of developing stress-related mood disorders, such as depression and anxiety. In rats, 6 weeks of wheel running protects against stress-induced behaviors thought to resemble symptoms of human anxiety and depression. The mechanisms by which exercise confers protection against stress-induced behaviors, however, remain unknown. One way by which exercise could generate stress resistance is by producing plastic changes in gene expression in the dorsal raphe nucleus (DRN). The DRN has a high concentration of 5-HT neurons and is implicated in stress-related mood disorders. The goal of the current experiment was to identify changes in the expression of genes that could be novel targets of exercise-induced stress resistance in the DRN. Adult, male F344 rats were allowed voluntary access to running wheels for 6 weeks; exposed to inescapable stress or no stress; and sacrificed immediately and 2 h after stressor termination. Laser capture micro dissection selectively sampled the DRN. mRNA expression was measured using the whole genome Affymetrix microarray. Comprehensive data analyses of gene expression included differential gene expression, log fold change (LFC) contrast analyses with False Discovery Rate correction, KEGG and Wiki Web Gestalt pathway enrichment analyses, and Weighted Gene Correlational Network Analysis (WGCNA). Our results suggest that physically active rats exposed to stress modulate expression of twice the number of genes, and display a more rapid and strongly coordinated response, than sedentary rats. Bioinformatics analyses revealed several potential targets of stress resistance including genes that are related to immune processes, tryptophan metabolism, and circadian/diurnal rhythms. PMID:23717271

Fully Coupled 3D Finite Element Model of Hydraulic Fracturing in a Permeable Rock Formation

NASA Astrophysics Data System (ADS)

Salimzadeh, S.; Paluszny, A.; Zimmerman, R. W.

2015-12-01

Hydraulic fracturing in permeable rock formations is a complex three-dimensional multi-physics phenomenon. Numerous analytical models of hydraulic fracturing processes have been proposed that typically simplify the physical processes, or somehow reduce the problem from three dimensions to two dimensions. Moreover, although such simplified models are able to model the growth of a single hydraulic fracture into an initially intact, homogeneous rock mass, they are generally not able to model fracturing of heterogeneous rock formations, or to account for interactions between multiple induced fractures, or between an induced fracture and pre-existing natural fractures. We have developed a numerical finite-element model for hydraulic fracturing that does not suffer from any of the limitations mentioned above. The model accounts for fluid flow within a fracture, the propagation of the fracture, and the leak-off of fluid from the fracture into the host rock. Fluid flow through the permeable rock matrix is modelled using Darcy's law, and is coupled with the laminar flow within the fracture. Fractures are discretely modelled in the three-dimensional mesh. Growth of a fracture is modelled using the concepts of linear elastic fracture mechanics (LEFM), with the onset and direction of growth based on stress intensity factors that are computed for arbitrary tetrahedral meshes. The model has been verified against several analytical solutions available in the literature for plane-strain (2D) and penny-shaped (3D) fractures, for various regimes of domination: viscosity, toughness, storage and leak-off. The interaction of the hydraulically driven fracture with pre-existing fractures and other fluid-driven fractures in terms of fluid leak-off, stress interaction and fracture arrest is investigated and the results are presented. Finally, some preliminary results are presented regarding the interaction of a hydraulically-induced fracture with a set of pre-existing natural fractures.

Influence of megapolis on the physical field variations

NASA Astrophysics Data System (ADS)

Riabova, Svetlana; Loktev, Dmitry; Spivak, Alexander

2016-04-01

The research of geophysical fields in the conditions of megapolis attracts particular interest not only in terms of their influence on the operation of precision equipment and technological processes associated with nanotechnology, but also it is perhaps the most important in terms of the formation of a special human and other biological objects' habitat. Indeed, the megapolis causes significant changes in regime of the physical fields both directly and indirectly. Negative factors of megapolis associated with elevated vibrations of soil as a result of traffic, acoustic load in the construction of infrastructure and transport communications, etc. are complemented by another negative factor, which until quite recently wasn't known much. It is a variation of physical fields (primarily electric and magnetic) induced by anthropogenic activities. As a result of the evolution a man has adapted to the natural regime of physical fields. Therefore, any, even the short-term changes of physical fields in the environment, their deviations from the natural rate can have a significant influence on human health including changes in the psycho-emotional state. In the present work we have evaluated the influence of the megapolis (in our case, Moscow) on the nature and regime of microseismic, electric and acoustic field in the surface atmosphere. We have analyzed data obtained as a result of continuous simultaneous registration of physical fields and meteorological parameters at the Center for geophysical monitoring of Moscow of Institute of Geosphere Dynamics of Russian Academy of Sciences. For determination of the characteristics of physical fields in the megapolis obtained data were compared with the results of the registration carried out at the Geophysical Observatory "Mikhnevo" of IDG RAS (located 85 km south from Moscow). The work is shown that the influence of the megapolis appears to increase the amplitude of physical fields, change of their spectral composition, disturbance of natural periodicities. The important factor characterized the megapolis is the presence of man-made component, which has a significant influence on the course of natural physical processes in the near-surface atmosphere.

Effects of preparation steps on the physical parameters and electromechanical properties of IPMC actuators

NASA Astrophysics Data System (ADS)

Wang, Yanjie; Zhu, Zicai; Chen, Hualing; Luo, Bin; Chang, Longfei; Wang, Yongquan; Li, Dichen

2014-12-01

The electromechanical properties of ionic polymer-metal composites (IPMC) are affected by many factors, including resistivity of surface electrodes, bending stiffness and dielectric modulus, etc, which are closely related to physical and chemical preparation steps. This paper focuses on the effects of preparation steps on these physical parameters and electromechanical properties of IPMC actuators. The mechanisms of electrode formation in the preparation steps are also clarified and investigated. To obtain samples with different features, one or more of the crucial process steps, including pretreatment, impregnation-reduction and chemical plating, were selected to fabricate IPMC. The experimental observations revealed that the physical parameters of IPMC strongly depend on their electrode morphologies caused by different steps, which were reasonable from the standpoint of physics. IPMC with the characteristics of low surface resistance and low bending stiffness, and a large area of interface electrode exhibits a perfect performance. The improvements were considered to be attributed to the double-layer electrostatic effect, induced by the broad dispersion of penetrated electrode nanoparticles. An electrical component, consisting of an equivalent circuit of a parallel combination of the serial circuit of the resistance and the electric double-layer capacitance, is introduced to qualitatively explain the deformation behaviors of IPMC. This research helps to improve the preparation steps and promote the understanding of IPMC.

Induced seismicity provides insight into why earthquake ruptures stop

PubMed Central

Galis, Martin; Ampuero, Jean Paul; Mai, P. Martin; Cappa, Frédéric

2017-01-01

Injection-induced earthquakes pose a serious seismic hazard but also offer an opportunity to gain insight into earthquake physics. Currently used models relating the maximum magnitude of injection-induced earthquakes to injection parameters do not incorporate rupture physics. We develop theoretical estimates, validated by simulations, of the size of ruptures induced by localized pore-pressure perturbations and propagating on prestressed faults. Our model accounts for ruptures growing beyond the perturbed area and distinguishes self-arrested from runaway ruptures. We develop a theoretical scaling relation between the largest magnitude of self-arrested earthquakes and the injected volume and find it consistent with observed maximum magnitudes of injection-induced earthquakes over a broad range of injected volumes, suggesting that, although runaway ruptures are possible, most injection-induced events so far have been self-arrested ruptures. PMID:29291250

Detonative propagation and accelerative expansion of the Crab Nebula shock front.

PubMed

Gao, Yang; Law, Chung K

2011-10-21

The accelerative expansion of the Crab Nebula's outer envelope is a mystery in dynamics, as a conventional expanding blast wave decelerates when bumping into the surrounding interstellar medium. Here we show that the strong relativistic pulsar wind bumping into its surrounding nebula induces energy-generating processes and initiates a detonation wave that propagates outward to form the current outer edge, namely, the shock front, of the nebula. The resulting detonation wave, with a reactive downstream, then provides the needed power to maintain propagation of the shock front. Furthermore, relaxation of the curvature-induced reduction of the propagation velocity from the initial state of formation to the asymptotic, planar state of Chapman-Jouguet propagation explains the observed accelerative expansion. Potential richness in incorporating reactive fronts in the description of various astronomical phenomena is expected. © 2011 American Physical Society

Mechanisms of boron fiber strengthening by thermal treatment

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.

1979-01-01

The fracture strain for boron on tungsten fibers can be improved by heat treatment under vacuum or argon environments. The mechanical basis for this improvement is thermally-induced axial contraction of the entire fiber, whereby strength-controlling core flaws are compressed and fiber fracture strain increased by the value of the contraction strain. By highly sensitive measurements of fiber density and volume, the physical mechanisms responsible for contraction under both environments was identified as boron atom diffusion out of the fiber sheath. The fiber contracts because the average volume of the resulting microvoid was determined to be only 0.26 + or - 0.09 the average atomic volume of the removed atom. The basic and practical implications of these results are discussed with particular emphasis on the theory, use, and limitations of heat-induced contraction as a simple cost-effective secondary processing method.

Size dependence of 13C nuclear spin-lattice relaxation in micro- and nanodiamonds

NASA Astrophysics Data System (ADS)

Panich, A. M.; Sergeev, N. A.; Shames, A. I.; Osipov, V. Yu; Boudou, J.-P.; Goren, S. D.

2015-02-01

Size dependence of physical properties of nanodiamond particles is of crucial importance for various applications in which defect density and location as well as relaxation processes play a significant role. In this work, the impact of defects induced by milling of micron-sized synthetic diamonds was studied by magnetic resonance techniques as a function of the particle size. EPR and 13C NMR studies of highly purified commercial synthetic micro- and nanodiamonds were done for various fractions separated by sizes. Noticeable acceleration of 13C nuclear spin-lattice relaxation with decreasing particle size was found. We showed that this effect is caused by the contribution to relaxation coming from the surface paramagnetic centers induced by sample milling. The developed theory of the spin-lattice relaxation for such a case shows good compliance with the experiment.

A general mechanism for competitor-induced dissociation of molecular complexes

PubMed Central

Paramanathan, Thayaparan; Reeves, Daniel; Friedman, Larry J.; Kondev, Jane; Gelles, Jeff

2014-01-01

The kinetic stability of non-covalent macromolecular complexes controls many biological phenomena. Here we find that physical models of complex dissociation predict that competitor molecules will in general accelerate the breakdown of isolated bimolecular complexes by occluding rapid rebinding of the two binding partners. This prediction is largely independent of molecular details. We confirm the prediction with single-molecule fluorescence experiments on a well-characterized DNA strand dissociation reaction. Contrary to common assumptions, competitor–induced acceleration of dissociation can occur in biologically relevant competitor concentration ranges and does not necessarily implyternary association of competitor with the bimolecular complex. Thus, occlusion of complex rebinding may play a significant role in a variety of biomolecular processes. The results also show that single-molecule colocalization experiments can accurately measure dissociation rates despite their limited spatio temporal resolution. PMID:25342513

Comparison of experimental proton-induced fluorescence spectra for a selection of thin high-Z samples with Geant4 Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Incerti, S.; Barberet, Ph.; Dévès, G.; Michelet, C.; Francis, Z.; Ivantchenko, V.; Mantero, A.; El Bitar, Z.; Bernal, M. A.; Tran, H. N.; Karamitros, M.; Seznec, H.

2015-09-01

The general purpose Geant4 Monte Carlo simulation toolkit is able to simulate radiative and non-radiative atomic de-excitation processes such as fluorescence and Auger electron emission, occurring after interaction of incident ionising radiation with target atomic electrons. In this paper, we evaluate the Geant4 modelling capability for the simulation of fluorescence spectra induced by 1.5 MeV proton irradiation of thin high-Z foils (Fe, GdF3, Pt, Au) with potential interest for nanotechnologies and life sciences. Simulation results are compared to measurements performed at the Centre d'Etudes Nucléaires de Bordeaux-Gradignan AIFIRA nanobeam line irradiation facility in France. Simulation and experimental conditions are described and the influence of Geant4 electromagnetic physics models is discussed.

Use of dissolved and vapor‐phase gases to investigate methanogenic degradation of petroleum hydrocarbon contamination in the subsurface

USGS Publications Warehouse

Amos, Richard T.; Mayer, K. Ulrich; Bekins, Barbara A.; Delin, Geoffrey N.; Williams, Randi L.

2005-01-01

At many sites contaminated with petroleum hydrocarbons, methanogenesis is a significant degradation pathway. Techniques to estimate CH4 production, consumption, and transport processes are needed to understand the geochemical system, provide a complete carbon mass balance, and quantify the hydrocarbon degradation rate. Dissolved and vapor‐phase gas data collected at a petroleum hydrocarbon contaminated site near Bemidji, Minnesota, demonstrate that naturally occurring nonreactive or relatively inert gases such as Ar and N2 can be effectively used to better understand and quantify physical and chemical processes related to methanogenic activity in the subsurface. In the vadose zone, regions of Ar and N2 depletion and enrichment are indicative of methanogenic and methanotrophic zones, and concentration gradients between the regions suggest that reaction‐induced advection can be an important gas transport process. In the saturated zone, dissolved Ar and N2 concentrations are used to quantify degassing driven by methanogenesis and also suggest that attenuation of methane along the flow path, into the downgradient aquifer, is largely controlled by physical processes. Slight but discernable preferential depletion of N2 over Ar, in both the saturated and unsaturated zones near the free‐phase oil, suggests reactivity of N2 and is consistent with other evidence indicating that nitrogen fixation by microbial activity is taking place at this site.

Decay of sandstone monuments in Petra (Jordan): Gravity-induced stress as a stabilizing factor

NASA Astrophysics Data System (ADS)

Řihošek, Jaroslav; Bruthans, Jiří; Mašín, David; Filippi, Michal; Schweigstillova, Jana

2016-04-01

As demonstrated by physical experiments and numerical modeling the gravity-induced stress (stress in further text) in sandstone massive reduces weathering and erosion rate (Bruthans et al. 2014). This finding is in contrast to common view that stress threatens stability of man-made monuments carved to sandstone. Certain low- levels of gravity-induced stress can in fact stabilize and protect these forms against weathering and disintegration. The purpose of this investigation is to evaluate the effect of the stress on weathering of sandstone monuments at the Petra World Heritage Site in Jordan via field observations, salt weathering experiments, and physical and numerical modeling. Previous studies on weathering of Petra monuments have neglected the impact of stress, but the ubiquitous presence of stress-controlled landforms in Petra suggests that it has a substantial effect on weathering and erosion processes on man-made monuments and natural surfaces. Laboratory salt weathering experiments with cubes of Umm Ishrin sandstone from Petra demonstrated the inverse relationship between stress magnitude and decay rate. Physical modeling with Strelec locked sand from the Czech Republic was used to simulate weathering and decay of Petra monuments. Sharp forms subjected to water erosion decayed to rounded shapes strikingly similar to tombs in Petra subjected to more than 2000 years of weathering and erosion. The physical modeling results enabled visualization of the recession of monument surfaces in high spatial and temporal resolution and indicate that the recession rate of Petra monuments is far from constant both in space and time. Numerical modeling of stress fields confirms the physical modeling results. This novel approach to investigate weathering clearly demonstrates that increased stress decreases the decay rate of Petra monuments. To properly delineate the endangered zones of monuments, the potential damage caused by weathering agents should be combined with stress modeling and verified by documentation of real damage. This research was funded by Grant Agency of Charles University (no. 386815) Bruthans J., Soukup J., Vaculíková J., Filippi M., Schweigstillova J., Mayo A.L., Mašín D., Kletetschka G.,Řihošek J. (2014): Sandstone landforms shaped by negative feedback between stress and erosion. Nature Geoscience 7(8): 597-601.

PULSE: A numerical model for the simulation of snowpack solute dynamics to capture runoff ionic pulses during snowmelt

NASA Astrophysics Data System (ADS)

Costa, D.; Pomeroy, J. W.; Wheater, H. S.

2017-12-01

Early ionic pulses in spring snowmelt can cause the temporary acidification of streams and account for a significant portion of the total annual nutrient export, particularly in seasonally snow-covered areas where the frozen ground may limit runoff-soil contact and cause the rapid delivery of these ions to streams. Ionic pulses are a consequence of snow ion exclusion, a process induced by snow metamorphism where ions are segregated from the snow grains losing mass to the surface of the grains gaining mass. While numerous studies have been successful in providing quantitative evidence of this process, few mechanistic mathematical models have been proposed for diagnostic and prediction. A few early modelling attempts have been successful in capturing this process assuming transport through porous media with variable porosity, however their implementation is difficult because they require complex models of snow physics to resolve the evolution of in-snow properties and processes during snowmelt, such as heat conduction, metamorphism, melt and water flow. Furthermore, initial snowpack to snow-surface ion concentration ratios are difficult to measure but are required to initiate these models and ion exclusion processes are not represented in a physically-based transparent fashion. In this research, a standalone numerical model has been developed to capture ionic pulses in snowmelt by emulating solute leaching from snow grains during melt and its subsequent transport by the percolating meltwater. Estimating snow porosity and water content dynamics is shown to be a viable alternative to deployment of complex snow physics models for this purpose. The model was applied to four study sites located in the Arctic and in Sierra Nevada to test for different climatic and hydrological conditions. The model compares very well with observations and could capture both the timing and magnitude of early melt ionic pulses accurately. This study demonstrates how physically based approaches can provide successful simulations of the spatial and temporal fluxes of snowmelt ions, which can be used to improve the prediction of nutrient export in cold regions for the spring freshet.

PULSE: A numerical model for the simulation of snowpack solute dynamics to capture runoff ionic pulses during snowmelt

NASA Astrophysics Data System (ADS)

Clark, M. P.; Nijssen, B.; Lundquist, J. D.; Luce, C. H.; Musselman, K. N.; Wayand, N. E.; Ou, M.; Lapo, K. E.

2016-12-01

Early ionic pulses in spring snowmelt can cause the temporary acidification of streams and account for a significant portion of the total annual nutrient export, particularly in seasonally snow-covered areas where the frozen ground may limit runoff-soil contact and cause the rapid delivery of these ions to streams. Ionic pulses are a consequence of snow ion exclusion, a process induced by snow metamorphism where ions are segregated from the snow grains losing mass to the surface of the grains gaining mass. While numerous studies have been successful in providing quantitative evidence of this process, few mechanistic mathematical models have been proposed for diagnostic and prediction. A few early modelling attempts have been successful in capturing this process assuming transport through porous media with variable porosity, however their implementation is difficult because they require complex models of snow physics to resolve the evolution of in-snow properties and processes during snowmelt, such as heat conduction, metamorphism, melt and water flow. Furthermore, initial snowpack to snow-surface ion concentration ratios are difficult to measure but are required to initiate these models and ion exclusion processes are not represented in a physically-based transparent fashion. In this research, a standalone numerical model has been developed to capture ionic pulses in snowmelt by emulating solute leaching from snow grains during melt and its subsequent transport by the percolating meltwater. Estimating snow porosity and water content dynamics is shown to be a viable alternative to deployment of complex snow physics models for this purpose. The model was applied to four study sites located in the Arctic and in Sierra Nevada to test for different climatic and hydrological conditions. The model compares very well with observations and could capture both the timing and magnitude of early melt ionic pulses accurately. This study demonstrates how physically based approaches can provide successful simulations of the spatial and temporal fluxes of snowmelt ions, which can be used to improve the prediction of nutrient export in cold regions for the spring freshet.

Temperature and Electron Density Determination on Laser-Induced Breakdown Spectroscopy (LIBS) Plasmas: A Physical Chemistry Experiment

ERIC Educational Resources Information Center

Najarian, Maya L.; Chinni, Rosemarie C.

2013-01-01

This laboratory is designed for physical chemistry students to gain experience using laser-induced breakdown spectroscopy (LIBS) in understanding plasma diagnostics. LIBS uses a high-powered laser that is focused on the sample causing a plasma to form. The emission of this plasma is then spectrally resolved and detected. Temperature and electron…

Synthesis of formamide and isocyanic acid after ion irradiation of frozen gas mixtures

NASA Astrophysics Data System (ADS)

Kaňuchová, Z.; Urso, R. G.; Baratta, G. A.; Brucato, J. R.; Palumbo, M. E.; Strazzulla, G.

2016-01-01

Context. Formamide (NH2HCO) and isocyanic acid (HNCO) have been observed as gaseous species in several astronomical environments such as cometary comae and pre- and proto-stellar objects. A debate is open on the formation route of those molecules, in particular if they are formed by chemical reactions in the gas phase and/or on grains. In this latter case it is relevant to understand if the formation occurs through surface reactions or is induced by energetic processing. Aims: We present arguments that support the formation of formamide in the solid phase by cosmic-ion-induced energetic processing of ices present as mantles of interstellar grains and on comets. Formamides, along with other molecules, are expelled in the gas phase when the physical parameters are appropriate to induce the desorption of ices. Methods: We have performed several laboratory experiments in which ice mixtures (H2O:CH4:N2, H2O:CH4:NH3, and CH3OH:N2) were bombarded with energetic (30-200 keV) ions (H+ or He+). FTIR spectroscopy was performed before, during, and after ion bombardment. In particular, the formation of HNCO and NH2HCO was measured quantiatively. Results: Energetic processing of ice can quantitatively reproduce the amount of NH2HCO observed in cometary comae and in many circumstellar regions. HNCO is also formed, but additional formation mechanisms are requested to quantitatively account for the astronomical observations. Conclusions: We suggest that energetic processing of ices in the pre- and proto-stellar regions and in comets is the main mechanism to produce formamide, which, once it is released in the gas phase because of desorption of ices, is observed in the gas phase in these astrophysical environments.

Geothermal induced seismicity: What links source mechanics and event magnitudes to faulting regime and injection rates?

NASA Astrophysics Data System (ADS)

Martinez-Garzon, Patricia; Kwiatek, Grzegorz; Bohnhoff, Marco; Dresen, Georg

2017-04-01

Improving estimates of seismic hazard associated to reservoir stimulation requires advanced understanding of the physical processes governing induced seismicity, which can be better achieved by carefully processing large datasets. To this end, we investigate source-type processes (shear/tensile/compaction) and rupture geometries with respect to the local stress field using seismicity from The Geysers (TG) and Salton Sea geothermal reservoirs, California. Analysis of 869 well-constrained full moment tensors (MW 0.8-3.5) at TG reveals significant non-double-couple (NDC) components (>25%) for 65% of the events and remarkably diversity in the faulting mechanisms. Volumetric deformation is clearly governed by injection rates with larger NDC components observed near injection wells and during high injection periods. The overall volumetric deformation from the moment tensors increases with time, possibly reflecting a reservoir pore pressure increase after several years of fluid injection with no significant production nearby. The obtained source mechanisms and fault orientations are magnitude-dependent and vary significantly between faulting regimes. Normal faulting events (MW < 2) reveal substantial NDC components indicating dilatancy, and they occur on varying fault orientations. In contrast, strike-slip events dominantly reveal a double-couple source, larger magnitudes (MW > 2) and mostly occur on optimally oriented faults with respect to the local stress field. NDC components indicating closure of cracks and pore spaces in the source region are found for reverse faulting events with MW > 2.5. Our findings from TG are generally consistent with preliminary source-type results from a reduced subset of well-recorded seismicity at the Salton Sea geothermal reservoir. Combined results imply that source processes and magnitudes of geothermal-induced seismicity are strongly affected by and systematically related to the hydraulic operations and the local stress state.

Physics-Based Preconditioning of a Compressible Flow Solver for Large-Scale Simulations of Additive Manufacturing Processes

NASA Astrophysics Data System (ADS)

Weston, Brian; Nourgaliev, Robert; Delplanque, Jean-Pierre

2017-11-01

We present a new block-based Schur complement preconditioner for simulating all-speed compressible flow with phase change. The conservation equations are discretized with a reconstructed Discontinuous Galerkin method and integrated in time with fully implicit time discretization schemes. The resulting set of non-linear equations is converged using a robust Newton-Krylov framework. Due to the stiffness of the underlying physics associated with stiff acoustic waves and viscous material strength effects, we solve for the primitive-variables (pressure, velocity, and temperature). To enable convergence of the highly ill-conditioned linearized systems, we develop a physics-based preconditioner, utilizing approximate block factorization techniques to reduce the fully-coupled 3×3 system to a pair of reduced 2×2 systems. We demonstrate that our preconditioned Newton-Krylov framework converges on very stiff multi-physics problems, corresponding to large CFL and Fourier numbers, with excellent algorithmic and parallel scalability. Results are shown for the classic lid-driven cavity flow problem as well as for 3D laser-induced phase change. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Reversibility and energy dissipation in adiabatic superconductor logic.

PubMed

Takeuchi, Naoki; Yamanashi, Yuki; Yoshikawa, Nobuyuki

2017-03-06

Reversible computing is considered to be a key technology to achieve an extremely high energy efficiency in future computers. In this study, we investigated the relationship between reversibility and energy dissipation in adiabatic superconductor logic. We analyzed the evolution of phase differences of Josephson junctions in the reversible quantum-flux-parametron (RQFP) gate and confirmed that the phase differences can change time reversibly, which indicates that the RQFP gate is physically, as well as logically, reversible. We calculated energy dissipation required for the RQFP gate to perform a logic operation and numerically demonstrated that the energy dissipation can fall below the thermal limit, or the Landauer bound, by lowering operation frequencies. We also investigated the 1-bit-erasure gate as a logically irreversible gate and the quasi-RQFP gate as a physically irreversible gate. We calculated the energy dissipation of these irreversible gates and showed that the energy dissipation of these gate is dominated by non-adiabatic state changes, which are induced by unwanted interactions between gates due to logical or physical irreversibility. Our results show that, in reversible computing using adiabatic superconductor logic, logical and physical reversibility are required to achieve energy dissipation smaller than the Landauer bound without non-adiabatic processes caused by gate interactions.

Study of Magnetic Damping Effect on Convection and Solidification Under G-Jitter Conditions

NASA Technical Reports Server (NTRS)

Li, Ben Q.; deGroh, H. C.

2001-01-01

As shown in space flight experiments, g-jitter is a critical issue affecting solidification processing of materials in microgravity. This study aims to provide, through extensive numerical simulations and ground based experiments, an assessment of the use of magnetic fields in combination with microgravity to reduce the g-jitter induced convective flows in space processing systems. Analytical solutions and 2-D and 3-D numerical models for g-jitter driven flows in simple solidification systems with and without the presence of an applied magnetic field have been developed and extensive analyses were carried out. A physical model was also constructed and PIV measurements compared reasonably well with predictions from numerical models. Some key points may be summarized as follows: (1) the amplitude of the oscillating velocity decreases at a rate inversely proportional to the g-jitter frequency and with an increase in the applied magnetic field; (2) the induced flow oscillates at approximately the same frequency as the affecting g-jitter, but out of a phase angle; (3) the phase angle is a complicated function of geometry, applied magnetic field, temperature gradient and frequency; (4) g-jitter driven flows exhibit a complex fluid flow pattern evolving in time; (5) the damping effect is more effective for low frequency flows; and (6) the applied magnetic field helps to reduce the variation of solutal distribution along the solid-liquid interface. Work in progress includes developing numerical models for solidification phenomena with the presence of both g-jitter and magnetic fields and developing a ground-based physical model to verify numerical predictions.

Polyion-induced aggregation of oppositely charged liposomes and charged colloidal particles: the many facets of complex formation in low-density colloidal systems.

PubMed

Cametti, C

2008-10-01

This review focusses on recent developments in the experimental study of polyion-induced charged colloidal particle aggregation, with particular emphasis on the formation of cationic liposome clusters induced by the addition of anionic adsorbing polyions. These structures can be considered, under certain points of view, a new class of colloidal systems, with intriguing properties that opens interesting and promising new opportunities in various biotechnological applications. Lipidic structures of different morphologies and different structural complexities interacting with oppositely charged polyions give rise to a rich variety of self-assembled structures that present various orders of hierarchy in the sense that, starting from a basic level, for example a lipid bilayer, they arrange themselves into superstructures as, for example, multilamellar stacks or liquid-crystalline structures. These structures can be roughly divided into two classes according to the fact that the elementary structure, involved in building a more complex one, keeps or does not keeps its basic arrangement. To the first one, belong those aggregates composed by single structures that maintain their integrity, for example, lipidic vesicles assembled together by an appropriate external agent. The second one encompasses structures that do not resemble the ones of the original objects which form them, but, conversely, derive from a deep restructuring and rearrangement process, where the original morphology of the initial constitutive elements is completely lost. In this review, I will only briefly touch on higher level hierarchy structures and I will focus on the assembling processes involving preformed lipid bilayer vesicles that organize themselves into clusters, the process being induced by the adsorption of oppositely charged polyions. The scientific interest in polyion-induced liposome aggregates is two-fold. On the one hand, in soft-matter physics, they represent an interesting colloidal system, governed by a balance between long-range electrostatic repulsion and short-range attraction, resulting in relatively large, equilibrium clusters, whose size and overall charge can be continuously tunable by simple environmental parameters. These structures present a variety of behaviors with a not yet completely understood phenomenology. On the other hand, the resulting structures possess some peculiar properties that justify their employment as drug delivery systems. Bio-compatibility, stability and ability to deliver various bio-active molecules and, moreover, their environmental responsiveness make liposome-based clusters a versatile carrier, with possibility of efficient targeting to different organs and tissues. Among the different structures made possible by the aggregating mechanism (cationic particles stuck together by anionic polyions or conversely anionic particles stuck together by cationic polyions), I will review the main experimental evidences for the existence of cationic liposome clusters. Especial attention is paid to our own work, mainly aimed at the characterization of these novel structures from a physical point of view.

Ion and neutral dynamics in Hall plasma accelerator ionization instabilities

NASA Astrophysics Data System (ADS)

Lucca Fabris, Andrea; Young, Christopher; Cappelli, Mark

2015-09-01

Hall thrusters, the extensively studied E × B devices used for space propulsion applications, are rife with instabilities and fluctuations. Many are thought to be fundamentally linked to microscopic processes like electron transport across magnetic field lines and propellant ionization that in turn affect macroscopic properties like device performance and lifetime. One of the strongest oscillatory regimes is the ``breathing mode,'' characterized by a propagating ionization front, time-varying ion acceleration profiles, and quasi-periodic 10-50 kHz current oscillations. Determining the temporal and spatial evolution of plasma properties is critical to achieving a fundamental physical understanding of these processes. We present non-intrusive laser-induced fluorescence measurements of the local ion and neutral velocity distribution functions synchronized with the breathing mode oscillations. Measurements reveal strong ion velocity fluctuations, multiple ion populations arising in narrow time windows throughout the near-field plume, and the periodic population and depopulation of neutral excited states. Analyzing these detailed experimental results in the context of the existing literature clarifies the fundamental physical processes underlying the breathing mode. This work is sponsored by the U.S. Air Force Office of Scientific Research with Dr. M. Birkan as program manager. C.Y. acknowledges support from the DOE NSSA Stewardship Science Graduate Fellowship under contract DE-FC52-08NA28752.

[Adaptation to hypoxia and hyperoxia improves physical endurance: the role of reactive oxygen species and redox-signaling].

PubMed

Sazontova, T G; Glazachev, O S; Bolotova, A V; Dudnik, E N; Striapko, N V; Bedareva, I V; Anchishkina, N A; Arkhipenko, Iu V

2012-06-01

We have conducted theoretical foundation, experimental analysis and a pilot study of a new method of adaptation to hypoxia and hyperoxia in the prevention of hypoxic and stress-induced disorders and improving the body's tolerance to physical stress. It has been shown in the experimental part that a combination of physical exercise with adaptation to hypoxia-hyperoxia significantly increased tolerance to acute physical load (APL) and its active phase. Analysis of lipid peroxidation processes, antioxidant enzymes and HSPs showed that short-term training for physical exercise by itself compensates the stressor, but not the hypoxic component of the APL, the combination of training with adaptation to hypoxia-hyperoxia completely normalizes the stressor and hypoxic components of APL. The pilot study has been performed to evaluate the effectiveness of hypoxic-hyperoxic training course in qualified young athletes with over-training syndrome. After completing the course of hypoxia-hyperoxia adaptation, 14 sessions, accompanied by light mode sports training, the athletes set the normalization of autonomic balance, increased resistance to acute hypoxia in hypoxic test, increased physical performance--increased PWC170, maximal oxygen consumption (VO2max) parameters, their relative values to body mass, diminished shift of rate pressure product in the load. Thus, we confirmed experimental findings that hypoxic-hyperoxic training optimizes hypoxic (increased athletes resistance to proper hypoxia) and stress (myocardium economy in acute physical stress testing) components in systemic adaptation and restoration of athletes' with over-training syndrome.

Hide and Seek: Radial-velocity searches for planets around active stars

NASA Astrophysics Data System (ADS)

Haywood, Raphaelle

2017-01-01

The ultimate obstacle to determining the masses of small, rocky exoplanets through radial-velocity (RV) monitoring is the intrinsic variability of the host stars themselves. For my PhD, I developed an intuitive and robust data analysis framework in which the activity-induced variations are modelled with a Gaussian process that has the frequency structure of the stellar magnetic activity. This allowed me to determine precise and accurate masses of the planets in the CoRoT-7, Kepler-78 and Kepler-10 systems. In parallel, I explored the physical origin of activity-induced RV variations of our best-known star: the Sun. I conducted the first systematic RV campaign of the Sun seen as an exoplanet host star using the 3.6m/HARPS spectrograph, by observing sunlight reflected off the bright asteroid 4/Vesta. I used images from the Solar Dynamics Observatory to reconstruct the RV signals incurred by individual surface features such as sunspots, faculae and granulation. I found that the activity-induced RV variations are driven by the suppression of convective blueshift arising dominantly from the presence of faculae. I also identified the full-disc magnetic flux as an excellent proxy for activity-induced RV variations.I am now pursuing my solar investigations using Sun-as-a-star RV observations acquired with the new solar telescope feed at HARPS-N. In particular, I am investigating the impact of magnetic surface features on the shapes of the spectral line profiles, rather than on the RVs themselves (which are a single moment of these lines). This work is key to developing physically-driven, better-tailored models for activity-induced RV variations, in preparation for the potentially habitable, Earth-like planets to be discovered and characterised in the coming years with TESS and GMT/G-CLEF.This work was funded by the Science and Technology Facilities Council in the United Kingdom and the John Templeton Foundation.

Effect and process evaluation of a kindergarten-based, family-involved cluster randomised controlled trial in six European countries on four- to six-year-old children's steps per day: the ToyBox-study.

PubMed

De Craemer, Marieke; Verloigne, Maïté; De Bourdeaudhuij, Ilse; Androutsos, Odysseas; Iotova, Violeta; Moreno, Luis; Koletzko, Berthold; Socha, Piotr; Manios, Yannis; Cardon, Greet

2017-08-29

The ToyBox-intervention is a theory- and evidence-based intervention delivered in kindergartens to improve four- to six-year-old children's energy balance-related behaviours and prevent obesity. The current study aimed to (1) examine the effect of the ToyBox-intervention on increasing European four- to six-year-old children' steps per day, and (2) examine if a higher process evaluation score from teachers and parents was related to a more favourable effect on steps per day. A sample of 2438 four- to six-year-old children (51.9% boys, mean age 4.75 ± 0.43 years) from 6 European countries (Belgium, Bulgaria, Germany, Greece, Poland and Spain) wore a motion sensor (pedometer or accelerometer) for a minimum of two weekdays and one weekend day both at baseline and follow-up to objectively measure their steps per day. Kindergarten teachers implemented the physical activity component of the ToyBox-intervention for 6 weeks in total, with a focus on (1) environmental changes in the classroom, (2) the child performing the actual behaviour and (3) classroom activities. Children's parents received newsletters, tip cards and posters. To assess intervention effects, multilevel repeated measures analyses were conducted for the total sample and the six intervention countries separately. In addition, process evaluation questionnaires were used to calculate a total process evaluation score (with implementation and satisfaction as a part of the overall score) for teachers and parents which was then linked with the physical activity outcomes. No significant intervention effects on four- to six-year-old children' steps per weekday, steps per weekend day and steps per average day were found, both in the total sample and in the country-specific samples (all p > 0.05). In general, the intervention effects on steps per day were least favourable in four- to six-year-old children with a low teachers process evaluation score and most favourable in four- to six-year-old children with a high teachers process evaluation score. No differences in intervention effects were found for a low, medium or high parents' process evaluation score. The physical activity component of the ToyBox-intervention had no overall effect on four- to six-year-old children' steps per day. However, the process evaluation scores showed that kindergarten teachers that implemented the physical activity component of the ToyBox-intervention as planned and were satisfied with the physical activity component led to favourable effects on children's steps per day. Strategies to motivate, actively involve and engage the kindergarten teachers and parents/caregivers are needed to induce larger effects.

WE-DE-202-00: Connecting Radiation Physics with Computational Biology

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

NONE

Radiation therapy for the treatment of cancer has been established as a highly precise and effective way to eradicate a localized region of diseased tissue. To achieve further significant gains in the therapeutic ratio, we need to move towards biologically optimized treatment planning. To achieve this goal, we need to understand how the radiation-type dependent patterns of induced energy depositions within the cell (physics) connect via molecular, cellular and tissue reactions to treatment outcome such as tumor control and undesirable effects on normal tissue. Several computational biology approaches have been developed connecting physics to biology. Monte Carlo simulations are themore » most accurate method to calculate physical dose distributions at the nanometer scale, however simulations at the DNA scale are slow and repair processes are generally not simulated. Alternative models that rely on the random formation of individual DNA lesions within one or two turns of the DNA have been shown to reproduce the clusters of DNA lesions, including single strand breaks (SSBs), double strand breaks (DSBs) without the need for detailed track structure simulations. Efficient computational simulations of initial DNA damage induction facilitate computational modeling of DNA repair and other molecular and cellular processes. Mechanistic, multiscale models provide a useful conceptual framework to test biological hypotheses and help connect fundamental information about track structure and dosimetry at the sub-cellular level to dose-response effects on larger scales. In this symposium we will learn about the current state of the art of computational approaches estimating radiation damage at the cellular and sub-cellular scale. How can understanding the physics interactions at the DNA level be used to predict biological outcome? We will discuss if and how such calculations are relevant to advance our understanding of radiation damage and its repair, or, if the underlying biological processes are too complex for a mechanistic approach. Can computer simulations be used to guide future biological research? We will debate the feasibility of explaining biology from a physicists’ perspective. Learning Objectives: Understand the potential applications and limitations of computational methods for dose-response modeling at the molecular, cellular and tissue levels Learn about mechanism of action underlying the induction, repair and biological processing of damage to DNA and other constituents Understand how effects and processes at one biological scale impact on biological processes and outcomes on other scales J. Schuemann, NCI/NIH grantsS. McMahon, Funding: European Commission FP7 (grant EC FP7 MC-IOF-623630)« less

WE-DE-202-01: Connecting Nanoscale Physics to Initial DNA Damage Through Track Structure Simulations

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

Schuemann, J.

Radiation therapy for the treatment of cancer has been established as a highly precise and effective way to eradicate a localized region of diseased tissue. To achieve further significant gains in the therapeutic ratio, we need to move towards biologically optimized treatment planning. To achieve this goal, we need to understand how the radiation-type dependent patterns of induced energy depositions within the cell (physics) connect via molecular, cellular and tissue reactions to treatment outcome such as tumor control and undesirable effects on normal tissue. Several computational biology approaches have been developed connecting physics to biology. Monte Carlo simulations are themore » most accurate method to calculate physical dose distributions at the nanometer scale, however simulations at the DNA scale are slow and repair processes are generally not simulated. Alternative models that rely on the random formation of individual DNA lesions within one or two turns of the DNA have been shown to reproduce the clusters of DNA lesions, including single strand breaks (SSBs), double strand breaks (DSBs) without the need for detailed track structure simulations. Efficient computational simulations of initial DNA damage induction facilitate computational modeling of DNA repair and other molecular and cellular processes. Mechanistic, multiscale models provide a useful conceptual framework to test biological hypotheses and help connect fundamental information about track structure and dosimetry at the sub-cellular level to dose-response effects on larger scales. In this symposium we will learn about the current state of the art of computational approaches estimating radiation damage at the cellular and sub-cellular scale. How can understanding the physics interactions at the DNA level be used to predict biological outcome? We will discuss if and how such calculations are relevant to advance our understanding of radiation damage and its repair, or, if the underlying biological processes are too complex for a mechanistic approach. Can computer simulations be used to guide future biological research? We will debate the feasibility of explaining biology from a physicists’ perspective. Learning Objectives: Understand the potential applications and limitations of computational methods for dose-response modeling at the molecular, cellular and tissue levels Learn about mechanism of action underlying the induction, repair and biological processing of damage to DNA and other constituents Understand how effects and processes at one biological scale impact on biological processes and outcomes on other scales J. Schuemann, NCI/NIH grantsS. McMahon, Funding: European Commission FP7 (grant EC FP7 MC-IOF-623630)« less

Neutron induced radio-isotopes and background for Ge double beta decay experiments

NASA Astrophysics Data System (ADS)

Chu, Pinghan; Majorana Collaboration

2015-10-01

Environmental neutrons, mostly produced by muons in the cosmic rays, might contribute backgrounds to the search for neutrinoless double beta decays. These neutrons can interact with materials and generate radio-isotopes, which can decay and produce radioactive backgrounds. Some of these neutron-induced isotopes have a signature of a time-delayed coincidence, allowing us to study these infrequent events. For example, such isotopes can decay by beta decay to metastable states and then decay by gamma decay to the ground state. Considering the time-delayed coincidence of these two processes, we can determine candidates for these neutron-induced isotopes in the data and estimate the flux of neutrons in the deep underground environment. In this report, we will list possible neutron-induced isotopes and the methodology to detect them, especially those that can affect the search for neutrinoless double beta decays in 76Ge. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics Program of the National Science Foundation, and the Sanford Underground Research Facility. We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program.

The evolution of machining-induced surface of single-crystal FCC copper via nanoindentation

NASA Astrophysics Data System (ADS)

Zhang, Lin; Huang, Hu; Zhao, Hongwei; Ma, Zhichao; Yang, Yihan; Hu, Xiaoli

2013-05-01

The physical properties of the machining-induced new surface depend on the performance of the initial defect surface and deformed layer in the subsurface of the bulk material. In this paper, three-dimensional molecular dynamics simulations of nanoindentation are preformed on the single-point diamond turning surface of single-crystal copper comparing with that of pristine single-crystal face-centered cubic copper. The simulation results indicate that the nucleation of dislocations in the nanoindentation test on the machining-induced surface and pristine single-crystal copper is different. The dislocation embryos are gradually developed from the sites of homogeneous random nucleation around the indenter in the pristine single-crystal specimen, while the dislocation embryos derived from the vacancy-related defects are distributed in the damage layer of the subsurface beneath the machining-induced surface. The results show that the hardness of the machining-induced surface is softer than that of pristine single-crystal copper. Then, the nanocutting simulations are performed along different crystal orientations on the same crystal surface. It is shown that the crystal orientation directly influences the dislocation formation and distribution of the machining-induced surface. The crystal orientation of nanocutting is further verified to affect both residual defect generations and their propagation directions which are important in assessing the change of mechanical properties, such as hardness and Young's modulus, after nanocutting process.

Redox-Triggered Bonding-Induced Emission of Thiol-Functionalized Gold Nanoclusters for Luminescence Turn-On Detection of Molecular Oxygen.

PubMed

Ao, Hang; Feng, Hui; Zhao, Mengting; Zhao, Meizhi; Chen, Jianrong; Qian, Zhaosheng

2017-11-22

Most optical sensors for molecular oxygen were developed based on the quenching effect of the luminescence of oxygen-sensitive probes; however, the signal turn-off mode of these probes is undesirable to quantify and visualize molecular oxygen. Herein, we report a novel luminescence turn-on detection strategy for molecular oxygen via the specific oxygen-triggered bonding-induced emission of thiol-functionalized gold nanoclusters. Thiol-functionalized gold nanoclusters were prepared by a facile one-step synthesis, and as-prepared gold nanoclusters possess significant aggregation-induced emission (AIE) property. It is the first time to discover the oxygen-triggered bonding-induced emission (BIE) behavior of gold nanoclusters, which results in disulfide-linked covalent bonding assemblies with intensely red luminescence. This specific redox-triggered BIE is capable of quantitatively detecting dissolved oxygen in aqueous solution in a light-up manner, and trace amount of dissolved oxygen at ppb level is achieved based on this detection method. A facile and convenient test strip for oxygen detection was also developed to monitor molecular oxygen in a gas matrix. Covalent bonding-induced emission is proven to be a more efficient way to attain high brightness of AIEgens than a physical aggregation-induced emission process, and provides a more convenient and desirable detection method for molecular oxygen than the previous sensors.

Two-dimensional patterns in bacterial veils arise from self-generated, three-dimensional fluid flows.

PubMed

Cogan, N G; Wolgemuth, C W

2011-01-01

The behavior of collections of oceanic bacteria is controlled by metabolic (chemotaxis) and physical (fluid motion) processes. Some sulfur-oxidizing bacteria, such as Thiovulum majus, unite these two processes via a material interface produced by the bacteria and upon which the bacteria are transiently attached. This interface, termed a bacterial veil, is formed by exo-polymeric substances (EPS) produced by the bacteria. By adhering to the veil while continuing to rotate their flagella, the bacteria are able to exert force on the fluid surroundings. This behavior induces a fluid flow that, in turn, causes the bacteria to aggregate leading to the formation of a physical pattern in the veil. These striking patterns are very similar in flavor to the classic convection instability observed when a shallow fluid is heated from below. However, the physics are very different since the flow around the veil is mediated by the bacteria and affects the bacterial densities. In this study, we extend a model of a one-dimensional veil in a two-dimensional fluid to the more realistic two-dimensional veil in a three-dimensional fluid. The linear stability analysis indicates that the Peclet number serves as a bifurcation parameter, which is consistent with experimental observations. We also solve the nonlinear problem numerically and are able to obtain patterns that are similar to those observed in the experiments.

Effectiveness of Physical Therapy as an Adjunctive Treatment for Trauma-induced Chronic Torticollis in Raptors.

PubMed

Nevitt, Benjamin N; Robinson, Narda; Kratz, Gail; Johnston, Matthew S

2015-03-01

Management of trauma-induced chronic torticollis in raptors has historically been challenging. Euthanasia is common in affected birds because of their inability to maintain normal cervical position, although they may be able to function normally. To assess effectiveness of physical therapy of the neck and head as an adjunct treatment for this condition, a case-control study was done in raptors admitted to the Rocky Mountain Raptor Program from 2003 to 2010. Eleven cases were identified with a diagnosis of chronic torticollis resulting from traumatic brain injury. Five cases were treated with physical therapy of the head and neck, and 6 control cases did not receive any physical therapy for the torticollis. Of the control cases, 0 of 6 had resolution of the torticollis, 0 of 6 were released, and 5 of 6 were euthanatized. Of the treated cases, 4 of 5 had complete resolution of the torticollis and 5 of 5 were released. Resolution of torticollis differed significantly between cases receiving physical therapy and controls. These results indicate that physical therapy should be used as an adjunctive therapy in cases of chronic torticollis induced by trauma in raptors because it results in better resolution of the torticollis and increased likelihood of release.

Bio-psychosocial factors are associated with pain intensity, physical functioning, and ability to work in female healthcare personnel with recurrent low back pain.

PubMed

Taulaniemi, Annika; Kuusinen, Lotta; Tokola, Kari; Kankaanpää, Markku; Suni, Jaana H

2017-08-31

To investigate associations of various bio-psychosocial factors with bodily pain, physical func-tioning, and ability to work in low back pain. Cross-sectional study. A total of 219 female healthcare workers with recurrent non-specific low back pain. Associations between several physical and psychosocial factors and: (i) bodily pain, (ii) physical functioning and (iii) ability to work were studied. Variables with statistically significant associations (p < 0.05) in bivariate analysis were set within a generalized linear model to analyse their relationship with each dependent variable. In generalized linear model analysis, perceived work-induced lumbar exertion (p < 0.001), multi-site pain (p <0.001) and work-related fear-avoidance beliefs (FAB-W) (p = 0.02) best explained bodily pain. Multi-site pain (p < 0.001), lumbar exertion (p = 0.005), FAB-W (p = 0.01) and physical performance in figure-of-eight running (p = 0.01) and modified push-ups (p = 0.05) best explained physical functioning; FAB-W (p <0.001), lumbar exertion (p = 0.003), depression (p = 0.01) and recovery after work (p = 0.03) best explained work ability. In bivariate analysis lumbar exertion was associated with poor physical performance. FAB-W and work-induced lumbar exertion were associated with levels of pain, physical functioning and ability to work. Poor physical performance capacity was associated with work-induced lumbar exertion. Interventions that aim to reduce fear-avoidance and increase fitness capacity might be beneficial.

Manual for Courts-Martial United States. 2002 Edition

DTIC Science & Technology

2002-01-01

are enlistment papers, physical exam- ination papers, outline-figure and fingerprint cards, forensic laboratory reports, chain of custody docu- ments...physical examination papers, outline figure and fin- gerprint cards, forensic laboratory reports, chain of custody documents, morning reports and...Para. 142 e of the 1969 Manual, “Polygraph tests and drug- induced or hypnosis -induced interviews,” has been deleted as a result of the adoption of

The effect of O-1602, an atypical cannabinoid, on morphine-induced conditioned place preference and physical dependence.

PubMed

Alavi, Mohaddeseh Sadat; Hosseinzadeh, Hossein; Shamsizadeh, Ali; Roohbakhsh, Ali

2016-06-01

Previous studies show that some non-CB1/non-CB2 effects of cannabinoids are mediated through G protein coupled receptor 55 (GPR55). As this receptor is activated by some of cannabinoid receptor ligands and is involved in the modulation of pain, it was hypothesized that this receptor may also interact with opioids. This study examined the effect of atypical cannabinoid O-1602 as a GPR55 agonist on morphine-induced conditioned place preference (CPP) and physical dependence. We used a biased CPP model to evaluate the effect of O-1602 (0.2, 1 and 5mg/kg, intraperitoneal; ip) on the acquisition and expression of morphine-induced CPP in male mice. The locomotor activities of mice were also recorded. Moreover, repeated administration of morphine (50, 50 and 75mg/kg/day) for three days, induced physical dependence. The withdrawal signs such as jumps and diarrhea were precipitated by administration of naloxone (5mg/kg, ip). The effect of O-1602 on the development of morphine physical dependence was assessed by injection of O-1602 (0.2, 1 and 5mg/kg) before morphine administrations. Morphine (40mg/kg, subcutaneous; sc), but not O-1602 (5mg/kg) elicited significant preference in the post-conditioning phase. O-1602 at the doses of 0.2 and 1mg/kg, but not 5mg/kg reduced acquisition of morphine CPP with an increase in locomotor activity at the dose of 5mg/kg. O-1602 at the doses of 0.2, 1 and 5mg/kg also reduced expression of morphine CPP with an increase in locomotor activity at the dose of 5mg/kg. O-1602 had a significant inhibitory effect on development of morphine-induced physical dependence at the dose of 5mg/kg by decreasing jumps and diarrhea during withdrawal syndrome. The present results indicate that O-1602 decreased acquisition and expression of morphine CPP and inhibited development of morphine-induced physical dependence. Copyright © 2016 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Evaluation of Graphite Fiber/Polyimide PMCs from Hot Melt vs Solution Prepreg

NASA Technical Reports Server (NTRS)

Shin, E. Eugene; Sutter, James K.; Eakin, Howard; Inghram, Linda; McCorkle, Linda; Scheiman, Dan; Papadopoulos, Demetrios; Thesken, John; Fink, Jeffrey E.

2002-01-01

Carbon fiber reinforced high temperature polymer matrix composites (PMC) have been extensively investigated as potential weight reduction replacements of various metallic components in next generation high performance propulsion rocket engines. The initial phase involves development of comprehensive composite material-process-structure-design-property-in-service performance correlations and database, especially for a high stiffness facesheet of various sandwich structures. Overview of the program plan, technical approaches and current multi-team efforts will be presented. During composite fabrication, it was found that the two large volume commercial prepregging methods (hot-melt vs. solution) resulted in considerably different composite cure behavior. Details of the process-induced physical and chemical modifications in the prepregs, their effects on composite processing, and systematic cure cycle optimization studies will be discussed. The combined effects of prepregging method and cure cycle modification on composite properties and isothermal aging performance were also evaluated.

Interference between light and heavy neutrinos for 0 νββ decay in the left–right symmetric model

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

Ahmed, Fahim; Neacsu, Andrei; Horoi, Mihai

Neutrinoless double-beta decay is proposed as an important low energy phenomenon that could test beyond the Standard Model physics. There are several potentially competing beyond the Standard Model mechanisms that can induce the process. It thus becomes important to disentangle the different processes. In the present study we consider the interference effect between the light left-handed and heavy right-handed Majorana neutrino exchange mechanisms. The decay rate, and consequently, the phase-space factors for the interference term are derived, based on the left–right symmetric model. The numerical values for the interference phase-space factors for several nuclides are calculated, taking into consideration themore » relativistic Coulomb distortion of the electron wave function and finite-size of the nucleus. As a result, the variation of the interference effect with the Q-value of the process is studied.« less

Reduce oil and grease content in wastewater

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

Capps, R.W.; Matelli, G.N.; Bradford, M.L.

Poor water quality is often blamed on biological oxidation unit malfunction. However, poorly treated water entering the bio-unit is more often the problem. At the microscopic level, oil/water-separation dynamics are influenced by pH, fluid velocity, temperature, and unit volumes. Oily water's physical and chemical properties affect pretreatment systems such as API separators, corrugated plate interception (CPI) separators, air flotation and equalization systems. A better understanding of pretreatment systems' limits and efficiencies can improve wastewater quality before it upsets the biological oxidation (BIOX). Oil contamination in refinery wastewater originates from desalting, steam stripping, product treating, tank drains, sample drains and equipmentmore » washdown. The largest volumetric contributors are cooling tower blowdowns and contaminated stormwater. The paper describes the BIOX process; oil/water separation; oil/water emulsions and colloidal solutions; air flotation; surfactants; DAF (dissolved air flotation) process; IAF (induced air flotation) process; equalization; load factors; salts; and system design.« less

Silica decorated on porous activated carbon nanofiber composites for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Kim, So Yeun; Kim, Bo-Hye

2016-10-01

A hybrid of silica decorated on porous activated carbon nanofibers (ACNFs) is fabricated in the form of a web via electrospinning and an activation process as an electrode material for electrochemical capacitors in an organic electrolyte. The introduction of PhSiH3 (PS) into the polyacrylonitrile (PAN) solution induces a porous ACNF structure containing silica nanoparticles (NPs) via the spontaneous sol-gel process of PS by steam in the subsequent physical activation process. These inorganic-organic hybrid composites of porous ACNF containing silica NPs show superior specific capacitance and energy density in electrochemical tests, along with good rate capability and excellent cycle life in an organic electrolyte, which is attributed to the combination of ACNF's high surface area and silica's hydrophilicity. The electrochemical performance decreases with increasing PS concentration, and this trend is consistent with the specific surface area results, which reveal the rapid formation of a double layer.

Interference between light and heavy neutrinos for 0 νββ decay in the left–right symmetric model

DOE PAGES

Ahmed, Fahim; Neacsu, Andrei; Horoi, Mihai

2017-03-31

Neutrinoless double-beta decay is proposed as an important low energy phenomenon that could test beyond the Standard Model physics. There are several potentially competing beyond the Standard Model mechanisms that can induce the process. It thus becomes important to disentangle the different processes. In the present study we consider the interference effect between the light left-handed and heavy right-handed Majorana neutrino exchange mechanisms. The decay rate, and consequently, the phase-space factors for the interference term are derived, based on the left–right symmetric model. The numerical values for the interference phase-space factors for several nuclides are calculated, taking into consideration themore » relativistic Coulomb distortion of the electron wave function and finite-size of the nucleus. As a result, the variation of the interference effect with the Q-value of the process is studied.« less

Interaction-induced decay of a heteronuclear two-atom system

PubMed Central

Xu, Peng; Yang, Jiaheng; Liu, Min; He, Xiaodong; Zeng, Yong; Wang, Kunpeng; Wang, Jin; Papoular, D. J.; Shlyapnikov, G. V.; Zhan, Mingsheng

2015-01-01

Two-atom systems in small traps are of fundamental interest for understanding the role of interactions in degenerate cold gases and for the creation of quantum gates in quantum information processing with single-atom traps. One of the key quantities is the inelastic relaxation (decay) time when one of the atoms or both are in a higher hyperfine state. Here we measure this quantity in a heteronuclear system of 87Rb and 85Rb in a micro optical trap and demonstrate experimentally and theoretically the presence of both fast and slow relaxation processes, depending on the choice of the initial hyperfine states. This experimental method allows us to single out a particular relaxation process thus provides an extremely clean platform for collisional physics studies. Our results have also implications for engineering of quantum states via controlled collisions and creation of two-qubit quantum gates. PMID:26199051

Evaluation of Graphite Fiber/Polyimide PMCs from Hot Melt versus Solution Prepreg

NASA Technical Reports Server (NTRS)

Shin, Eugene E.; Sutter, James K.; Eakin, Howard; Inghram, Linda; McCorkle, Linda; Scheiman, Dan; Papadopoulos, Demetrios; Thesken, John; Fink, Jeffrey E.; Gray, Hugh R. (Technical Monitor)

2002-01-01

Carbon fiber reinforced high temperature polymer matrix composites (PMC) have been extensively investigated as potential weight reduction replacements of various metallic components in next generation high performance propulsion rocket engines. The initial phase involves development of comprehensive composite material-process-structure-design-property in-service performance correlations and database, especially for a high stiffness facesheet of various sandwich structures. Overview of the program plan, technical approaches and current multi-team efforts will be presented. During composite fabrication, it was found that the two large volume commercial prepregging methods (hot-melt vs. solution) resulted in considerably different composite cure behavior. Details of the process-induced physical and chemical modifications in the prepregs, their effects on composite processing, and systematic cure cycle optimization studies will be discussed. The combined effects of prepregging method and cure cycle modification on composite properties and isothermal aging performance were also evaluated.

Synoptic-to-planetary scale wind variability enhances phytoplankton biomass at ocean fronts

NASA Astrophysics Data System (ADS)

Whitt, D. B.; Taylor, J. R.; Lévy, M.

2017-06-01

In nutrient-limited conditions, phytoplankton growth at fronts is enhanced by winds, which drive upward nutrient fluxes via enhanced turbulent mixing and upwelling. Hence, depth-integrated phytoplankton biomass can be 10 times greater at isolated fronts. Using theory and two-dimensional simulations with a coupled physical-biogeochemical ocean model, this paper builds conceptual understanding of the physical processes driving upward nutrient fluxes at fronts forced by unsteady winds with timescales of 4-16 days. The largest vertical nutrient fluxes occur when the surface mixing layer penetrates the nutricline, which fuels phytoplankton in the mixed layer. At a front, mixed layer deepening depends on the magnitude and direction of the wind stress, cross-front variations in buoyancy and velocity at the surface, and potential vorticity at the base of the mixed layer, which itself depends on past wind events. Consequently, mixing layers are deeper and more intermittent in time at fronts than outside fronts. Moreover, mixing can decouple in time from the wind stress, even without other sources of physical variability. Wind-driven upwelling also enhances depth-integrated phytoplankton biomass at fronts; when the mixed layer remains shallower than the nutricline, this results in enhanced subsurface phytoplankton. Oscillatory along-front winds induce both oscillatory and mean upwelling. The mean effect of oscillatory vertical motion is to transiently increase subsurface phytoplankton over days to weeks, whereas slower mean upwelling sustains this increase over weeks to months. Taken together, these results emphasize that wind-driven phytoplankton growth is both spatially and temporally intermittent and depends on a diverse combination of physical processes.

Crop yield changes induced by emissions of individual climate-altering pollutants

NASA Astrophysics Data System (ADS)

Shindell, Drew T.

2016-08-01

Climate change damages agriculture, causing deteriorating food security and increased malnutrition. Many studies have examined the role of distinct physical processes, but impacts have not been previously attributed to individual pollutants. Using a simple model incorporating process-level results from detailed models, here I show that although carbon dioxide (CO2) is the largest driver of climate change, other drivers appear to dominate agricultural yield changes. I calculate that anthropogenic emissions to date have decreased global agricultural yields by 9.5 ± 3.0%, with roughly 93% stemming from non-CO2 emissions, including methane (-5.2 ± 1.7%) and halocarbons (-1.4 ± 0.4%). The differing impacts stem from atmospheric composition responses: CO2 fertilizes crops, offsetting much of the loss induced by warming; halocarbons do not fertilize; methane leads to minimal fertilization but increases surface ozone which augments warming-induced losses. By the end of the century, strong CO2 mitigation improves agricultural yields by ˜3 ± 5%. In contrast, strong methane and hydrofluorocarbon mitigation improve yields by ˜16 ± 5% and ˜5 ± 4%, respectively. These are the first quantitative analyses to include climate, CO2 and ozone simultaneously, and hence, additional studies would be valuable. Nonetheless, as policy makers have leverage over pollutant emissions rather than isolated processes, the perspective presented here may be more useful for decision making than that in the prior work upon which this study builds. The results suggest that policies should target a broad portfolio of pollutant emissions in order to optimize mitigation of societal damages.

Evidence for alteration in chemical and physical properties of water and modulation of its biological functions by sunlight transmitted through color ranges of the visible spectrum-a novel study.

PubMed

Cohly, Hari H P; Panja, Asit; Reno, William L; Obenhuber, Don; Koelle, Margot S; Das, Suman K; Angel, Michael F; Rao, M Rajeswara

2005-08-01

We investigated the changes in the properties of water when exposed to sunlight for 40 days. We hypothesize and prove that solar irradiation to water entraps electromagnetic radiation as potential energy, which becomes kinetic energy in various systems. It is postulated that photochemically-induced energy transfers, associated with individual spectral emission of visible spectrum of solar light, exert diverse influences on biological systems. Bottles of distilled water, individually wrapped in spectral-colored cellophane were exposed to sunlight and compared to an unwrapped bottle to determine chemical and physical changes as well as modifications of biological properties. Each bottle of water was named according to the color of cellophane paper with letter E (stands for exposed) as a prefix with (E-violet, E-indigo, E-blue, E-green, E-yellow, E-orange, and E-red). E-control (without wrap) was exposed to polychromatic sunlight. This study addresses two main issues viz., the chemical and physical changes in E-water and its effect on biological activities. Chemical and physical composition analysis using inductively coupled plasma atomic emission spectrometry; physical conductance by a Wheatstone Bridge type conductivity meter; osmolarity by a vapor pressure osmometer; and, salt solubility profile of 10% sodium bicarbonate were determined. Furthermore, testing the effect of E-waters on human lymphocyte proliferation, mosquito larvae hatching and seed germination determined the functional role of solar radiation through specific spectrum/s of visible light on various biological processes. We found that water exposed to visible spectral emissions of sunlight had an altered elemental composition, electrical conductance, osmolarity and salt-solubility, as well as differences in bio-modulatory effects. A gradual increase in leaching of Boron from E-violet to E-red was noted. E-indigo showed maximal increase in electrical conductance and maximal salt solubility of sodium bicarbonate. E-blue inhibited phyto-hemagglutinin-induced immune cell proliferation and mosquito larvae hatching. E-orange stimulated root elongation in seed germination. We conclude that 40-day exposure of water to specific solar spectrum changes chemical and physical properties and influences on biological activity.

Evidence for Alteration in Chemical and Physical Properties of Water and Modulation of its Biological Functions by Sunlight Transmitted through Color Ranges of the Visible Spectrum-A Novel Study

PubMed Central

Cohly, Hari H. P.; Panja, Asit; Reno, William L.; Obenhuber, Don; Koelle, Margot S.; Das, Suman K.; Angel, Michael F.; Rao, M. Rajeswara

2005-01-01

We investigated the changes in the properties of water when exposed to sunlight for 40 days. We hypothesize and prove that solar irradiation to water entraps electromagnetic radiation as potential energy, which becomes kinetic energy in various systems. It is postulated that photochemically-induced energy transfers, associated with individual spectral emission of visible spectrum of solar light, exert diverse influences on biological systems. Bottles of distilled water, individually wrapped in spectral-colored cellophane were exposed to sunlight and compared to an unwrapped bottle to determine chemical and physical changes as well as modifications of biological properties. Each bottle of water was named according to the color of cellophane paper with letter E (stands for exposed) as a prefix with (E-violet, E-indigo, E-blue, E-green, E-yellow, E-orange, and Ered). E-control (without wrap) was exposed to polychromatic sunlight. This study addresses two main issues viz., the chemical and physical changes in E-water and its effect on biological activities. Chemical and physical composition analysis using inductively coupled plasma atomic emission spectrometry; physical conductance by a Wheatstone Bridge type conductivity meter; osmolarity by a vapor pressure osmometer; and, salt solubility profile of 10% sodium bicarbonate were determined. Furthermore, testing the effect of E-waters on human lymphocyte proliferation, mosquito larvae hatching and seed germination determined the functional role of solar radiation through specific spectrum/s of visible light on various biological processes. We found that water exposed to visible spectral emissions of sunlight had an altered elemental composition, electrical conductance, osmolarity and salt-solubility, as well as differences in bio-modulatory effects. A gradual increase in leaching of Boron from E-violet to E-red was noted. E-indigo showed maximal increase in electrical conductance and maximal salt solubility of sodium bicarbonate. E-blue inhibited phyto-hemagglutinin-induced immune cell proliferation and mosquito larvae hatching. E-orange stimulated root elongation in seed germination. We conclude that 40-day exposure of water to specific solar spectrum changes chemical and physical properties and influences on biological activity. PMID:16705821

Tactile cues significantly modulate the perception of sweat-induced skin wetness independently of the level of physical skin wetness

PubMed Central

Fournet, Damien; Hodder, Simon; Havenith, George

2015-01-01

Humans sense the wetness of a wet surface through the somatosensory integration of thermal and tactile inputs generated by the interaction between skin and moisture. However, little is known on how wetness is sensed when moisture is produced via sweating. We tested the hypothesis that, in the absence of skin cooling, intermittent tactile cues, as coded by low-threshold skin mechanoreceptors, modulate the perception of sweat-induced skin wetness, independently of the level of physical wetness. Ten males (22 yr old) performed an incremental exercise protocol during two trials designed to induce the same physical skin wetness but to induce lower (TIGHT-FIT) and higher (LOOSE-FIT) wetness perception. In the TIGHT-FIT, a tight-fitting clothing ensemble limited intermittent skin-sweat-clothing tactile interactions. In the LOOSE-FIT, a loose-fitting ensemble allowed free skin-sweat-clothing interactions. Heart rate, core and skin temperature, galvanic skin conductance (GSC), and physical (wbody) and perceived skin wetness were recorded. Exercise-induced sweat production and physical wetness increased significantly [GSC: 3.1 μS, SD 0.3 to 18.8 μS, SD 1.3, P < 0.01; wbody: 0.26 no-dimension units (nd), SD 0.02, to 0.92 nd, SD 0.01, P < 0.01], with no differences between TIGHT-FIT and LOOSE-FIT (P > 0.05). However, the limited intermittent tactile inputs generated by the TIGHT-FIT ensemble reduced significantly whole-body and regional wetness perception (P < 0.01). This reduction was more pronounced when between 40 and 80% of the body was covered in sweat. We conclude that the central integration of intermittent mechanical interactions between skin, sweat, and clothing, as coded by low-threshold skin mechanoreceptors, significantly contributes to the ability to sense sweat-induced skin wetness. PMID:25878153

Auditory processing during deep propofol sedation and recovery from unconsciousness.

PubMed

Koelsch, Stefan; Heinke, Wolfgang; Sammler, Daniela; Olthoff, Derk

2006-08-01

Using evoked potentials, this study investigated effects of deep propofol sedation, and effects of recovery from unconsciousness, on the processing of auditory information with stimuli suited to elicit a physical MMN, and a (music-syntactic) ERAN. Levels of sedation were assessed using the Bispectral Index (BIS) and the Modified Observer's Assessment of Alertness and Sedation Scale (MOAAS). EEG-measurements were performed during wakefulness, deep propofol sedation (MOAAS 2-3, mean BIS=68), and a recovery period. Between deep sedation and recovery period, the infusion rate of propofol was increased to achieve unconsciousness (MOAAS 0-1, mean BIS=35); EEG measurements of recovery period were performed after subjects regained consciousness. During deep sedation, the physical MMN was markedly reduced, but still significant. No ERAN was observed in this level. A clear P3a was elicited during deep sedation by those deviants, which were task-relevant during the awake state. As soon as subjects regained consciousness during the recovery period, a normal MMN was elicited. By contrast, the P3a was absent in the recovery period, and the P3b was markedly reduced. Results indicate that the auditory sensory memory (as indexed by the physical MMN) is still active, although strongly reduced, during deep sedation (MOAAS 2-3). The presence of the P3a indicates that attention-related processes are still operating during this level. Processes of syntactic analysis appear to be abolished during deep sedation. After propofol-induced anesthesia, the auditory sensory memory appears to operate normal as soon as subjects regain consciousness, whereas the attention-related processes indexed by P3a and P3b are markedly impaired. Results inform about effects of sedative drugs on auditory and attention-related mechanisms. The findings are important because these mechanisms are prerequisites for auditory awareness, auditory learning and memory, as well as language perception during anesthesia.

Physical and physiological impacts of different foam control strategies during a process involving hydrophobic substrate for the lipase production by Yarrowia lipolytica.

PubMed

Kar, Tambi; Destain, Jacqueline; Thonart, Philippe; Delvigne, Frank

2012-05-01

The potentialities for the intensification of the process of lipase production by the yeast Yarrowia lipolytica on a renewable hydrophobic substrate (methyl oleate) have to be investigated. The key factor governing the lipase yield is the intensification of the oxygen transfer rate, considering the fact that Y. lipolytica is a strict aerobe. However, considering the nature of the substrate and the capacity for protein excretion and biosurfactant production of Y. lipolytica, intensification of oxygen transfer rate is accompanied by an excessive formation of foam. Two different foam control strategies have thus been implemented: a classical chemical foam control strategy and a mechanical foam control (MFM) based on the Stirring As Foam Disruption principle. The second strategy allows foam control without any modifications of the physico-chemical properties of the broth. However, the MFM system design induced the formation of a persistent foam layer in the bioreactor. This phenomenon has led to the segregation of microbial cells between the foam phase and the liquid phase in the case of the bioreactors operated with MFM control, and induced a reduction at the level of the lipase yield. More interestingly, flow cytometry experiments have shown that the residence time of microbial cells in the foam phase tends to induce a dimorphic transition which could potentially explain the reduction of lipase excretion.

Design and fabrication of a full-scale actively controlled satellite appendage simulator unit

NASA Astrophysics Data System (ADS)

Jacobs, Jack H.; Quenon, Dan; Hadden, Steve; Self, Rick

1999-07-01

Modern satellites require the ability to slew and settle quickly in order to acquire or transmit data efficiently. Solar arrays and communication antennas cause low frequency disturbances to the satellite bus during these maneuvers causing undesirable induced vibration of the payload. The ability to develop and experimentally demonstrate attitude control laws which compensate for these flexible body disturbances is of prime importance to modern day satellite manufacturers. Honeywell has designed and fabricated an actively controlled Appendage Simulator Unit (ASU) which can physically induce the modal characteristics of satellite appendages on to a ground based satellite test bed installed on an air bearing. The ASU consists of two orthogonal fulcrum beams weighting over 800 pounds each utilizing two electrodynamic shakers to induce active torques onto the bus. The ASU is programmed with the state space characteristics of the desired appendage and responds in real time to the bus motion to generate realistic disturbances back onto the satellite. Two LVDT's are used on each fulcrum beam to close the loop and insure the system responds in real time the same way a real solar array would on-orbit. Each axis is independently programmable in order to simulate various orientations or modal contributions from an appendage. The design process for the ASU involved the optimization of sensors, actuators, control authority, weight, power and functionality. The smart structure system design process and experimental results are described in detail.

Physical Interpretation of Laboratory Friction Laws in the Context of Damage Physics

NASA Astrophysics Data System (ADS)

Rundle, J. B.; Tiampo, K. F.; Martins, J. S.; Klein, W.

2002-12-01

Frictional on sliding surfaces is ultimately related to processes of surface damage, and can be understood in the context of the physics of dynamical threshold systems. Threshold systems are known to be some of the most important nonlinear, self-organizing systems in nature, including networks of earthquake faults, neural networks, superconductors and semiconductors, and the World Wide Web, as well as political, social, and ecological systems. All of these systems have dynamics that are strongly correlated in space and time, and all typically display a multiplicity of spatial and temporal scales. Here we discuss the physics of self-organization and damage in earthquake threshold systems at the "microscopic" laboratory scale, in which consideration of results from simulations leads to dynamical equations that can be used to derive results obtained from sliding friction experiments, specifically, the empirical "rate-and-state" friction equations of Ruina. Paradoxically, in all of these dissipative systems, long-range interactions induce the existence of locally ergodic dynamics, even though the dissipation of energy is involved. The existence of dissipative effects leads to the appearance of a "leaky threshold" dynamics, equivalent to a new scaling field that controls the size of nucleation events relative to the size of the background fluctuations. The corresponding appearance of a mean field spinodal leads to a general coarse-grained equation, which expresses the balance between rate of stress supplied, and rate of stress dissipated in the processes leading to surface damage. We can use ideas from thermodynamics and kinetics of phase transitions to develop the exact form of the rate-and-state equations, giving clear physical meaning to all terms and variables. Ultimately, the self-organizing dynamics arise from the appearance of an energy landscape in these systems, which in turn arises from the strong correlations and mean field nature of the physics.

Energy dissipation in flows through curved spaces.

PubMed

Debus, J-D; Mendoza, M; Succi, S; Herrmann, H J

2017-02-14

Fluid dynamics in intrinsically curved geometries is encountered in many physical systems in nature, ranging from microscopic bio-membranes all the way up to general relativity at cosmological scales. Despite the diversity of applications, all of these systems share a common feature: the free motion of particles is affected by inertial forces originating from the curvature of the embedding space. Here we reveal a fundamental process underlying fluid dynamics in curved spaces: the free motion of fluids, in the complete absence of solid walls or obstacles, exhibits loss of energy due exclusively to the intrinsic curvature of space. We find that local sources of curvature generate viscous stresses as a result of the inertial forces. The curvature- induced viscous forces are shown to cause hitherto unnoticed and yet appreciable energy dissipation, which might play a significant role for a variety of physical systems involving fluid dynamics in curved spaces.

Exercise training and cardiometabolic diseases: focus on the vascular system.

PubMed

Roque, Fernanda R; Hernanz, Raquel; Salaices, Mercedes; Briones, Ana M

2013-06-01

The regular practice of physical activity is a well-recommended strategy for the prevention and treatment of several cardiovascular and metabolic diseases. Physical exercise prevents the progression of vascular diseases and reduces cardiovascular morbidity and mortality. Exercise training also ameliorates vascular changes including endothelial dysfunction and arterial remodeling and stiffness, usually present in type 2 diabetes, obesity, hypertension and metabolic syndrome. Common to these diseases is excessive oxidative stress, which plays an important role in the processes underlying vascular changes. At the vascular level, exercise training improves the redox state and consequently NO availability. Moreover, growing evidence indicates that other mediators such as prostanoids might be involved in the beneficial effects of exercise. The purpose of this review is to update recent findings describing the adaptation response induced by exercise in cardiovascular and metabolic diseases, focusing more specifically on the beneficial effects of exercise in the vasculature and the underlying mechanisms.

Hunting Down Massless Dark Photons in Kaon Physics

NASA Astrophysics Data System (ADS)

Fabbrichesi, M.; Gabrielli, E.; Mele, B.

2017-07-01

If dark photons are massless, they couple to standard-model particles only via higher dimensional operators, while direct (renormalizable) interactions induced by kinetic mixing, which motivates most of the current experimental searches, are absent. We consider the effect of possible flavor-changing magnetic-dipole couplings of massless dark photons in kaon physics. In particular, we study the branching ratio for the process K+→π+π0γ ¯ with a simplified-model approach, assuming the chiral quark model to evaluate the hadronic matrix element. Possible effects in the K0-K¯ 0 mixing are taken into account. We find that branching ratios up to O (10-7) are allowed—depending on the dark-sector masses and couplings. Such large branching ratios for K+→π+π0γ ¯ could be of interest for experiments dedicated to rare K+ decays like NA62 at CERN, where γ ¯ can be detected as a massless invisible system.

Simulation of the main physical processes in remote laser penetration with large laser spot size

DOE PAGES

Khairallah, S. A.; Anderson, A.; Rubenchik, A. M.; ...

2015-04-10

A 3D model is developed to simulate remote laser penetration of a 1mm Aluminum metal sheet with large laser spot size (~3x3cm²), using the ALE3D multi-physics code. The model deals with the laser-induced melting of the plate and the mechanical interaction between the solid and the melted part through plate elastic-plastic response. The effect of plate oscillations and other forces on plate rupture, the droplet formation mechanism and the influence of gravity and high laser power in further breaking the single melt droplet into many more fragments are analyzed. In the limit of low laser power, the numerical results matchmore » the available experiments. The numerical approach couples mechanical and thermal diffusion to hydrodynamics melt flow and accounts for temperature dependent material properties, surface tension, gravity and vapor recoil pressure.« less

What favors convective aggregation and why?

NASA Astrophysics Data System (ADS)

Muller, Caroline; Bony, Sandrine

2015-07-01

The organization of convection is ubiquitous, but its physical understanding remains limited. One particular type of organization is the spatial self-aggregation of convection, taking the form of cloud clusters, or tropical cyclones in the presence of rotation. We show that several physical processes can give rise to self-aggregation and highlight the key features responsible for it, using idealized simulations. Longwave radiative feedbacks yield a "radiative aggregation." In that case, sufficient spatial variability of radiative cooling rates yields a low-level circulation, which induces the upgradient energy transport and radiative-convective instability. Not only do vertically integrated radiative budgets matter but the vertical profile of cooling is also crucial. Convective aggregation is facilitated when downdrafts below clouds are weak ("moisture-memory aggregation"), and this is sufficient to trigger aggregation in the absence of longwave radiative feedbacks. These results shed some light on the sensitivity of self-aggregation to various parameters, including resolution or domain size.

Biphasic dose responses in biology, toxicology and medicine: accounting for their generalizability and quantitative features.

PubMed

Calabrese, Edward J

2013-11-01

The most common quantitative feature of the hormetic-biphasic dose response is its modest stimulatory response which at maximum is only 30-60% greater than control values, an observation that is consistently independent of biological model, level of organization (i.e., cell, organ or individual), endpoint measured, chemical/physical agent studied, or mechanism. This quantitative feature suggests an underlying "upstream" mechanism common across biological systems, therefore basic and general. Hormetic dose response relationships represent an estimate of the peak performance of integrative biological processes that are allometrically based. Hormetic responses reflect both direct stimulatory or overcompensation responses to damage induced by relatively low doses of chemical or physical agents. The integration of the hormetic dose response within an allometric framework provides, for the first time, an explanation for both the generality and the quantitative features of the hormetic dose response. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effective degrees of freedom of a random walk on a fractal

NASA Astrophysics Data System (ADS)

Balankin, Alexander S.

2015-12-01

We argue that a non-Markovian random walk on a fractal can be treated as a Markovian process in a fractional dimensional space with a suitable metric. This allows us to define the fractional dimensional space allied to the fractal as the ν -dimensional space Fν equipped with the metric induced by the fractal topology. The relation between the number of effective spatial degrees of freedom of walkers on the fractal (ν ) and fractal dimensionalities is deduced. The intrinsic time of random walk in Fν is inferred. The Laplacian operator in Fν is constructed. This allows us to map physical problems on fractals into the corresponding problems in Fν. In this way, essential features of physics on fractals are revealed. Particularly, subdiffusion on path-connected fractals is elucidated. The Coulomb potential of a point charge on a fractal embedded in the Euclidean space is derived. Intriguing attributes of some types of fractals are highlighted.

Synergy in spreading processes: from exploitative to explorative foraging strategies.

PubMed

Pérez-Reche, Francisco J; Ludlam, Jonathan J; Taraskin, Sergei N; Gilligan, Christopher A

2011-05-27

An epidemiological model which incorporates synergistic effects that allow the infectivity and/or susceptibility of hosts to be dependent on the number of infected neighbors is proposed. Constructive synergy induces an exploitative behavior which results in a rapid invasion that infects a large number of hosts. Interfering synergy leads to a slower and sparser explorative foraging strategy that traverses larger distances by infecting fewer hosts. The model can be mapped to a dynamical bond percolation with spatial correlations that affect the mechanism of spread but do not influence the critical behavior of epidemics. © 2011 American Physical Society

Laser Induced Aluminum Surface Breakdown Model

NASA Technical Reports Server (NTRS)

Chen, Yen-Sen; Liu, Jiwen; Zhang, Sijun; Wang, Ten-See (Technical Monitor)

2002-01-01

Laser powered propulsion systems involve complex fluid dynamics, thermodynamics and radiative transfer processes. Based on an unstructured grid, pressure-based computational aerothermodynamics; platform, several sub-models describing such underlying physics as laser ray tracing and focusing, thermal non-equilibrium, plasma radiation and air spark ignition have been developed. This proposed work shall extend the numerical platform and existing sub-models to include the aluminum wall surface Inverse Bremsstrahlung (IB) effect from which surface ablation and free-electron generation can be initiated without relying on the air spark ignition sub-model. The following tasks will be performed to accomplish the research objectives.

International Workshop on Ion Beam Modification and Processing of High Tc- Superconductors: Physics and Devices: Program and Abstracts

DTIC Science & Technology

1989-04-12

Karlsruhe, FRG The application of ion beams with energies in the region of about 0.3 to 3 MeV for the analysis and modification of superconductors is...Jolla Ca- lifornia 92093, USA It is now well cstablished that the oxygen content and ordering plays a crucial role ih thie transport and crystallographic...the Belgian F.K.F.O., C.V.l{. is a Reserch Associate of the Belian N.F.W.O. I I I I I IRRADIATION INDUCED DEPAIRING IN YBACUO J. Lesueur, P Nddtlec

The Intertwined Roles of Transcription and Repair Proteins

PubMed Central

Fong, Yick W.; Cattoglio, Claudia; Tjian, Robert

2014-01-01

Transcription is apparently risky business. Its intrinsic mutagenic potential must be kept in check by networks of DNA repair factors that monitor the transcription process to repair DNA lesions that could otherwise compromise transcriptional fidelity and genome integrity. Intriguingly, recent studies point to an even more direct function of DNA repair complexes as co-activators of transcription and the unexpected role of “scheduled” DNA damage/repair at gene promoters. Paradoxically, spontaneous DNA double-strand breaks also induce ectopic transcription that is essential for repair. Thus, transcription, DNA damage and repair may be more physically and functionally intertwined than previously appreciated. PMID:24207023

The Processing and Mechanical Properties of High Temperature/High Performance Composites. Book 7. In-Situ Measurements of Stress and Damage

DTIC Science & Technology

1994-04-01

Physics, Vol.72, No.12, 1992, pp.5535-5538. (12] Ragan, D.R., Gustavsen, R., and Schiferl , D., "Calibration of the Ruby R2 and R2 Fluorescence Shifts... Schiferl , D., "Pressure and Temperature Dependence of Laser-Induced Fluorescence of Sm:YAG to 100 kbar and 7000 C and an Empirical Model," Journal of...1964). IS. H. D’Amour. D. Schiferl , W. Denner, H. Schulz and 20. J. W. McCauley and G. V. Gibbs. Z. Knistallogr. 135, W, B. Holzapfel, J. appl. Phys. 49

Seismic design and engineering research at the U.S. Geological Survey

USGS Publications Warehouse

1988-01-01

The Engineering Seismology Element of the USGS Earthquake Hazards Reduction Program is responsible for the coordination and operation of the National Strong Motion Network to collect, process, and disseminate earthquake strong-motion data; and, the development of improved methodologies to estimate and predict earthquake ground motion.  Instrumental observations of strong ground shaking induced by damaging earthquakes and the corresponding response of man-made structures provide the basis for estimating the severity of shaking from future earthquakes, for earthquake-resistant design, and for understanding the physics of seismologic failure in the Earth's crust.

Mueller matrix imaging and analysis of cancerous cells

NASA Astrophysics Data System (ADS)

Fernández, A.; Fernández-Luna, J. L.; Moreno, F.; Saiz, J. M.

2017-08-01

Imaging polarimetry is a focus of increasing interest in diagnostic medicine because of its non-invasive nature and its potential for recognizing abnormal tissues. However, handling polarimetric images is not an easy task, and different intermediate steps have been proposed to introduce physical parameters that may be helpful to interpret results. In this work, transmission Mueller matrices (MM) corresponding to cancer cell samples have been experimentally obtained, and three different transformations have been applied: MM-Polar Decomposition, MM-Transformation and MM-Differential Decomposition. Special attention has been paid to diattenuation as a sensitive parameter to identify apoptosis processes induced by cisplatin and etoposide.

Reduced Wiener Chaos representation of random fields via basis adaptation and projection

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

Tsilifis, Panagiotis, E-mail: tsilifis@usc.edu; Department of Civil Engineering, University of Southern California, Los Angeles, CA 90089; Ghanem, Roger G., E-mail: ghanem@usc.edu

2017-07-15

A new characterization of random fields appearing in physical models is presented that is based on their well-known Homogeneous Chaos expansions. We take advantage of the adaptation capabilities of these expansions where the core idea is to rotate the basis of the underlying Gaussian Hilbert space, in order to achieve reduced functional representations that concentrate the induced probability measure in a lower dimensional subspace. For a smooth family of rotations along the domain of interest, the uncorrelated Gaussian inputs are transformed into a Gaussian process, thus introducing a mesoscale that captures intermediate characteristics of the quantity of interest.

Hydrodynamic cavitation: from theory towards a new experimental approach

NASA Astrophysics Data System (ADS)

Lucia, Umberto; Gervino, Gianpiero

2009-09-01

Hydrodynamic cavitation is analysed by a global thermodynamics principle following an approach based on the maximum irreversible entropy variation that has already given promising results for open systems and has been successfully applied in specific engineering problems. In this paper we present a new phenomenological method to evaluate the conditions inducing cavitation. We think this method could be useful in the design of turbo-machineries and related technologies: it represents both an original physical approach to cavitation and an economical saving in planning because the theoretical analysis could allow engineers to reduce the experimental tests and the costs of the design process.

On the Violence of High Explosive Reactions

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

Tarver, C M; Chidester, S K

High explosive reactions can be caused by three general energy deposition processes: impact ignition by frictional and/or shear heating; bulk thermal heating; and shock compression. The violence of the subsequent reaction varies from benign slow combustion to catastrophic detonation of the entire charge. The degree of violence depends on many variables, including the rate of energy delivery, the physical and chemical properties of the explosive, and the strength of the confinement surrounding the explosive charge. The current state of experimental and computer modeling research on the violence of impact, thermal, and shock-induced reactions is reviewed.

Reduced Wiener Chaos representation of random fields via basis adaptation and projection

NASA Astrophysics Data System (ADS)

Tsilifis, Panagiotis; Ghanem, Roger G.

2017-07-01

A new characterization of random fields appearing in physical models is presented that is based on their well-known Homogeneous Chaos expansions. We take advantage of the adaptation capabilities of these expansions where the core idea is to rotate the basis of the underlying Gaussian Hilbert space, in order to achieve reduced functional representations that concentrate the induced probability measure in a lower dimensional subspace. For a smooth family of rotations along the domain of interest, the uncorrelated Gaussian inputs are transformed into a Gaussian process, thus introducing a mesoscale that captures intermediate characteristics of the quantity of interest.

Physically corrected forward operators for induced emission tomography: a simulation study

NASA Astrophysics Data System (ADS)

Viganò, Nicola Roberto; Solé, Vicente Armando

2018-03-01

X-ray emission tomography techniques over non-radioactive materials allow one to investigate different and important aspects of the matter that are usually not addressable with the standard x-ray transmission tomography, such as density, chemical composition and crystallographic information. However, the quantitative reconstruction of these investigated properties is hindered by additional problems, including the self-attenuation of the emitted radiation. Work has been done in the past, especially concerning x-ray fluorescence tomography, but this has always focused on solving very specific problems. The novelty of this work resides in addressing the problem of induced emission tomography from a much wider perspective, introducing a unified discrete representation that can be used to modify existing algorithms to reconstruct the data of the different types of experiments. The direct outcome is a clear and easy mathematical description of the implementation details of such algorithms, despite small differences in geometry and other practical aspects, but also the possibility to express the reconstruction as a minimization problem, allowing the use of variational methods, and a more flexible modeling of the noise involved in the detection process. In addition, we look at the results of a few selected simulated data reconstructions that describe the effect of physical corrections like the self-attenuation, and the response to noise of the adapted reconstruction algorithms.

Isolated and combined effects of photobiomodulation therapy, topical nonsteroidal anti-inflammatory drugs, and physical activity in the treatment of osteoarthritis induced by papain

NASA Astrophysics Data System (ADS)

Tomazoni, Shaiane Silva; Leal-Junior, Ernesto Cesar Pinto; Frigo, Lúcio; Pallotta, Rodney Capp; Teixeira, Simone; de Almeida, Patricia; Bjordal, Jan Magnus; Lopes-Martins, Rodrigo Álvaro Brandão

2016-10-01

Osteoarthritis (OA) is a chronic inflammatory disease and is characterized as a degenerative process. This study aimed to evaluate and compare the effects of a topical nonsteroidal anti-inflammatory drug (NSAID), physical activity, and photobiomodulation therapy (PBMT) applied alone and/or in combination between them in an experimental model of knee OA. OA was induced by injection of papain in the knees of rats. After 21 days, the animals started to be treated with the above treatment. Histological analysis shows that the experimental model of OA induction causes morphological changes consistent with the disease, and among treatments, the PBMT is the most effective for reducing these changes. Moreover, the results demonstrate that PBMT and NSAID reduce the total number of cells in the inflammatory infiltrate (p<0.05) and PBMT was the most effective for reducing the activity of myeloperoxidase (p<0.05). Finally, we observed that both NSAID and PBMT were effective for reducing the gene expression of MMP-3 (p<0.05), but in relation to the gene expression of MMP-13, PBMT was the most effective treatment (p<0.05). The results of this study indicate that PBMT is the most effective therapy in stopping disease progression, and improving inflammatory conditions observed in OA.

Freezing: an underutilized food safety technology?

PubMed

Archer, Douglas L

2004-01-15

Freezing is an ancient technology for preserving foods. Freezing halts the activities of spoilage microorganisms in and on foods and can preserve some microorganisms for long periods of time. Frozen foods have an excellent overall safety record. The few outbreaks of food-borne illness associated with frozen foods indicate that some, but not all human pathogens are killed by commercial freezing processes. Freezing kills microorganisms by physical and chemical effects and possibly through induced genetic changes. Research is needed to better understand the physical and chemical interactions of various food matrices with the microbial cell during freezing and holding at frozen temperatures. The literature suggests that many pathogenic microorganisms may be sublethally injured by freezing, so research should be done to determine how to prevent injured cells from resuscitating and becoming infectious. Studies on the genetics of microbial stress suggest that the induction of resistance to specific stresses may be counteracted by, for example, simple chemicals. Research is needed to better understand how resistance to the lethal effect of freezing is induced in human pathogens and means by which it can be counteracted in specific foods. Through research, it seems possible that freezing may in the future be used to reliably reduce populations of food-borne pathogens as well as to preserve foods.

A thalamic input to the nucleus accumbens mediates opiate dependence.

PubMed

Zhu, Yingjie; Wienecke, Carl F R; Nachtrab, Gregory; Chen, Xiaoke

2016-02-11

Chronic opiate use induces opiate dependence, which is characterized by extremely unpleasant physical and emotional feelings after drug use is terminated. Both the rewarding effects of a drug and the desire to avoid withdrawal symptoms motivate continued drug use, and the nucleus accumbens is important for orchestrating both processes. While multiple inputs to the nucleus accumbens regulate reward, little is known about the nucleus accumbens circuitry underlying withdrawal. Here we identify the paraventricular nucleus of the thalamus as a prominent input to the nucleus accumbens mediating the expression of opiate-withdrawal-induced physical signs and aversive memory. Activity in the paraventricular nucleus of the thalamus to nucleus accumbens pathway is necessary and sufficient to mediate behavioural aversion. Selectively silencing this pathway abolishes aversive symptoms in two different mouse models of opiate withdrawal. Chronic morphine exposure selectively potentiates excitatory transmission between the paraventricular nucleus of the thalamus and D2-receptor-expressing medium spiny neurons via synaptic insertion of GluA2-lacking AMPA receptors. Notably, in vivo optogenetic depotentiation restores normal transmission at these synapses and robustly suppresses morphine withdrawal symptoms. This links morphine-evoked pathway- and cell-type-specific plasticity in the paraventricular nucleus of the thalamus to nucleus accumbens circuit to opiate dependence, and suggests that reprogramming this circuit holds promise for treating opiate addiction.

Acoustically induced slip in sheared granular layers: Application to dynamic earthquake triggering: TRIGGERED SLIP IN SHEARED GRANULAR GOUGE

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

Ferdowsi, Behrooz; Griffa, Michele; Guyer, Robert A.

A fundamental mystery in earthquake physics is “how can an earthquake be triggered by distant seismic sources?” We use discrete element method simulations of a granular layer, during stick slip, that is subject to transient vibrational excitation to gain further insight into the physics of dynamic earthquake triggering. We also observe delayed triggering of slip in the granular gouge, using Coulomb friction law for grains interaction. We find that at a critical vibrational amplitude (strain) there is an abrupt transition from negligible time-advanced slip (clock advance) to full clock advance; i.e., transient vibration and triggered slip are simultaneous. Moreover, themore » critical strain is of order 10 -6, similar to observations in the laboratory and in Earth. The transition is related to frictional weakening of the granular layer due to a dramatic decrease in coordination number and the weakening of the contact force network. Associated with this frictional weakening is a pronounced decrease in the elastic modulus of the layer. The study has important implications for mechanisms of triggered earthquakes and induced seismic events and points out the underlying processes in response of the fault gouge to dynamic transient stresses.« less

Acoustically induced slip in sheared granular layers: Application to dynamic earthquake triggering: TRIGGERED SLIP IN SHEARED GRANULAR GOUGE

DOE PAGES

Ferdowsi, Behrooz; Griffa, Michele; Guyer, Robert A.; ...

2015-11-19

A fundamental mystery in earthquake physics is “how can an earthquake be triggered by distant seismic sources?” We use discrete element method simulations of a granular layer, during stick slip, that is subject to transient vibrational excitation to gain further insight into the physics of dynamic earthquake triggering. We also observe delayed triggering of slip in the granular gouge, using Coulomb friction law for grains interaction. We find that at a critical vibrational amplitude (strain) there is an abrupt transition from negligible time-advanced slip (clock advance) to full clock advance; i.e., transient vibration and triggered slip are simultaneous. Moreover, themore » critical strain is of order 10 -6, similar to observations in the laboratory and in Earth. The transition is related to frictional weakening of the granular layer due to a dramatic decrease in coordination number and the weakening of the contact force network. Associated with this frictional weakening is a pronounced decrease in the elastic modulus of the layer. The study has important implications for mechanisms of triggered earthquakes and induced seismic events and points out the underlying processes in response of the fault gouge to dynamic transient stresses.« less

Health effects of atmospheric particulates: a medical geology perspective.

PubMed

Duzgoren-Aydin, Nurdan S

2008-01-01

In this review, atmospheric particulates as composite airborne earth materials often containing both natural and anthropogenic components were examined in the context of medical geology. Despite a vast number of both experimental and epidemiological studies confirming the direct and indirect links between atmospheric particulates and human health, the exact nature of mechanisms affecting the particulate-induced pathogenesis largely remains unexplored. Future in depth research on these areas would be most successful if potential mechanisms are examined with reference to the physical (e.g., size, shape and surface), chemical, mineralogical and source characteristics of particulate matters. The underlying goal of this review was to present the relevant terminology and processes proposed in the literature to explain the interfaces and interactions between atmospheric particles and human body within the framework of "atmospheric particle cycles." The complexities of the interactions were demonstrated through case studies focusing on particulate matter air pollution and malignant mesothelioma occurrences due to environmental exposure to erionite-a fibrous zeolite mineral. There is an urgent need for a standard protocol or speciation methods applicable to earth-materials to guide and streamline studies on etiology of mineral-induced diseases. This protocol or speciation methods should provide relevant procedures to determine the level and extent of physical, chemical and mineralogical heterogeneity of particulate matters as well as quantitative in-situ particulate characteristics.

Twist effects in quantum vortices and phase defects

NASA Astrophysics Data System (ADS)

Zuccher, Simone; Ricca, Renzo L.

2018-02-01

In this paper we show that twist, defined in terms of rotation of the phase associated with quantum vortices and other physical defects effectively deprived of internal structure, is a property that has observable effects in terms of induced axial flow. For this we consider quantum vortices governed by the Gross-Pitaevskii equation (GPE) and perform a number of test cases to investigate and compare the effects of twist in two different contexts: (i) when this is artificially superimposed on an initially untwisted vortex ring; (ii) when it is naturally produced on the ring by the simultaneous presence of a central straight vortex. In the first case large amplitude perturbations quickly develop, generated by the unnatural setting of the initial condition that is not an analytical solution of the GPE. In the second case much milder perturbations emerge, signature of a genuine physical process. This scenario is confirmed by other test cases performed at higher twist values. Since the second setting corresponds to essential linking, these results provide new evidence of the influence of topology on physics.

Effects of global atmospheric perturbations on forest ecosystems: Predictions of seasonal and cumulative effects

NASA Technical Reports Server (NTRS)

Tinus, R. W.; Roddy, D. J.

1988-01-01

The physical effects of certain large events, such as giant impacts, explosive volcanism, or combined nuclear explosions, have the potential of inducing global catastrophes in our terrestrial environment. Such highly energetic events can inject substantial quantities of material into the atmosphere. In turn, this changes the amount of sunlight reaching the Earth's surface and modifies atmospheric temperatures to produce a wide range of global effects. One consequence is the introduction of serious stresses in both plants and animals throughout the Earth's biosphere. For example, recent studies predict that forest lands, crop lands, and range lands would suffer specific physical and biological degradations if major physical and chemical disruptions occurred in our atmosphere. Forests, which cover over 4 times 10 to the 9th power hectares (4 times 10 to the 7th power sq km) of our planet, or about 3 times the area now cultivated for crops, are critical to many processes in the biosphere. Forests contribute heavily to the production of atmospheric oxygen, supply the major volume of biomass, and provide a significant percentage of plant and animal habitats.

Minding the Cyber-Physical Gap: Model-Based Analysis and Mitigation of Systemic Perception-Induced Failure

PubMed Central

2017-01-01

The cyber-physical gap (CPG) is the difference between the ‘real’ state of the world and the way the system perceives it. This discrepancy often stems from the limitations of sensing and data collection technologies and capabilities, and is inevitable at some degree in any cyber-physical system (CPS). Ignoring or misrepresenting such limitations during system modeling, specification, design, and analysis can potentially result in systemic misconceptions, disrupted functionality and performance, system failure, severe damage, and potential detrimental impacts on the system and its environment. We propose CPG-Aware Modeling & Engineering (CPGAME), a conceptual model-based approach to capturing, explaining, and mitigating the CPG. CPGAME enhances the systems engineer’s ability to cope with CPGs, mitigate them by design, and prevent erroneous decisions and actions. We demonstrate CPGAME by applying it for modeling and analysis of the 1979 Three Miles Island 2 nuclear accident, and show how its meltdown could be mitigated. We use ISO-19450:2015—Object Process Methodology as our conceptual modeling framework. PMID:28714910

Physical Exertion and Immediate Classroom Mental Performance Among Elementary School Children.

ERIC Educational Resources Information Center

Gabbard, Carl

This study was designed (1) to investigate the relationship between physical exertion and mental performance in elementary school children and (2) to determine if male or female mental performances are more affected by physical exertion. A total of 95 second graders participated in six treatments of induced physical exertion during their regularly…

Comparison of physical and chemical properties of high pressure- and heat-treated Lychee (Litchi chinensis Sonn.) in syrup

NASA Astrophysics Data System (ADS)

Dajanta, Katekan; Apichartsrangkoon, Arunee; Somsang, Soontaree

2012-03-01

Lychee usually has white flesh, but its flesh is very sensitive to thermal and enzymatic impairment and ultimately changes in color. This investigation was intended to study the magnitude of color change in lychee by high pressure and thermal processing. The lychee was packed in syrup prior to being processed. Pressurized lychee was performed at 600 MPa at 30°C or 50°C for 20 min, while the pasteurized sample was heated at 90°C for 3 min. It was found that pressurization induced lower color L*, a* and b* values, including low anthocyanin content. For enzymatic activities, high pressure could reduce the activity of polyphenoloxidase by 33-51%, whereas pasteurization markedly reduced that activity by 90%.

Is attention essential for inducing synesthetic colors? Evidence from oculomotor distractors.

PubMed

Nijboer, Tanja C W; Van der Stigchel, Stefan

2009-06-30

In studies investigating visual attention in synesthesia, the targets usually induce a synesthetic color. To measure to what extent attention is necessary to induce synesthetic color experiences, one needs a task in which the synesthetic color is induced by a task-irrelevant distractor. In the current study, an oculomotor distractor task was used in which an eye movement was to be made to a physically colored target while ignoring a single physically colored or synesthetic distractor. Whereas many erroneous eye movements were made to distractors with an identical hue as the target (i.e., capture), much less interference was found with synesthetic distractors. The interference of synesthetic distractors was comparable with achromatic non-digit distractors. These results suggest that attention and hence overt recognition of the inducing stimulus are essential for the synesthetic color experience to occur.

Linking process and structure in the friction stir scribe joining of dissimilar materials: A computational approach with experimental support

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

Gupta, Varun; Upadhyay, Piyush; Fifield, Leonard S.

The friction stir welding (FSW) is a popular technique to join dissimilar materials in numerous applications. The solid state nature of the process enables joining materials with strikingly different physical properties. For the welds in lap configuration, an enhancement to this technology is made by introducing a short hard insert, referred to as cutting-scribe, at the bottom of the tool pin. The cutting-scribe induces deformation in the bottom plate which leads to the formation of mechanical interlocks or hook like structures at the interface of two materials. A thermo-mechanically coupled computational model employing coupled Eulerian-Lagrangian approach is developed to quantitativelymore » capture the morphology of these interlocks during the FSW process. The simulations using developed model are validated by the experimental observations.The identified interface morphology coupled with the predicted temperature field from this process-structure model can then be used to estimate the post-weld microstructure and joint strength.« less

On inducing finite dimensional physical field representations for massless particles in even dimensions

NASA Technical Reports Server (NTRS)

Bhansali, Vineer

1993-01-01

Assuming trivial action of Euclidean translations, the method of induced representations is used to derive a correspondence between massless field representations transforming under the full generalized even dimensional Lorentz group, and highest weight states of the relevant little group. This gives a connection between 'helicity' and 'chirality' in all dimensions. Restrictions on 'gauge independent' representations for physical particles that this induction imposes are also stated.

Interoception and stress

PubMed Central

Schulz, André; Vögele, Claus

2015-01-01

Afferent neural signals are continuously transmitted from visceral organs to the brain. Interoception refers to the processing of visceral-afferent neural signals by the central nervous system, which can finally result in the conscious perception of bodily processes. Interoception can, therefore, be described as a prominent example of information processing on the ascending branch of the brain–body axis. Stress responses involve a complex neuro-behavioral cascade, which is elicited when the organism is confronted with a potentially harmful stimulus. As this stress cascade comprises a range of neural and endocrine pathways, stress can be conceptualized as a communication process on the descending branch of the brain–body axis. Interoception and stress are, therefore, associated via the bi-directional transmission of information on the brain–body axis. It could be argued that excessive and/or enduring activation (e.g., by acute or chronic stress) of neural circuits, which are responsible for successful communication on the brain–body axis, induces malfunction and dysregulation of these information processes. As a consequence, interoceptive signal processing may be altered, resulting in physical symptoms contributing to the development and/or maintenance of body-related mental disorders, which are associated with stress. In the current paper, we summarize findings on psychobiological processes underlying acute and chronic stress and their interaction with interoception. While focusing on the role of the physiological stress axes (hypothalamic-pituitary-adrenocortical axis and autonomic nervous system), psychological factors in acute and chronic stress are also discussed. We propose a positive feedback model involving stress (in particular early life or chronic stress, as well as major adverse events), the dysregulation of physiological stress axes, altered perception of bodily sensations, and the generation of physical symptoms, which may in turn facilitate stress. PMID:26257668

Investigate the complex process in particle-fluid based surface generation technology using reactive molecular dynamics method

NASA Astrophysics Data System (ADS)

Han, Xuesong; Li, Haiyan; Zhao, Fu

2017-07-01

Particle-fluid based surface generation process has already become one of the most important materials processing technology for many advanced materials such as optical crystal, ceramics and so on. Most of the particle-fluid based surface generation technology involves two key process: chemical reaction which is responsible for surface softening; physical behavior which is responsible for materials removal/deformation. Presently, researchers cannot give a reasonable explanation about the complex process in the particle-fluid based surface generation technology because of the small temporal-spatial scale and the concurrent influence of physical-chemical process. Molecular dynamics (MD) method has already been proved to be a promising approach for constructing effective model of atomic scale phenomenon and can serve as a predicting simulation tool in analyzing the complex surface generation mechanism and is employed in this research to study the essence of surface generation. The deformation and piles of water molecule is induced with the feeding of abrasive particle which justifies the property mutation of water at nanometer scale. There are little silica molecule aggregation or materials removal because the water-layer greatly reduce the strength of mechanical interaction between particle and materials surface and minimize the stress concentration. Furthermore, chemical effect is also observed at the interface: stable chemical bond is generated between water and silica which lead to the formation of silconl and the reaction rate changes with the amount of water molecules in the local environment. Novel ring structure is observed in the silica surface and it is justified to be favored of chemical reaction with water molecule. The siloxane bond formation process quickly strengthened across the interface with the feeding of abrasive particle because of the compressive stress resulted by the impacting behavior.

Elicitation: a tool for enriching the bioactive composition of foods.

PubMed

Baenas, Nieves; García-Viguera, Cristina; Moreno, Diego A

2014-09-01

Elicitation is a good strategy to induce physiological changes and stimulate defense or stress-induced responses in plants. The elicitor treatments trigger the synthesis of phytochemical compounds in fruits, vegetables and herbs. These metabolites have been widely investigated as bioactive compounds responsible of plant cell adaptation to the environment, specific organoleptic properties of foods, and protective effects in human cells against oxidative processes in the development of neurodegenerative and cardiovascular diseases and certain types of cancer. Biotic (biological origin), abiotic (chemical or physical origin) elicitors and phytohormones have been applied alone or in combinations, in hydroponic solutions or sprays, and in different selected time points of the plant growth or during post-harvest. Understanding how plant tissues and their specific secondary metabolic pathways respond to specific treatments with elicitors would be the basis for designing protocols to enhance the production of secondary metabolites, in order to produce quality and healthy fresh foods.

Electromagnetized gold nanoparticles mediate direct lineage reprogramming into induced dopamine neurons in vivo for Parkinson's disease therapy

NASA Astrophysics Data System (ADS)

Yoo, Junsang; Lee, Euiyeon; Kim, Hee Young; Youn, Dong-Ho; Jung, Junghyun; Kim, Hongwon; Chang, Yujung; Lee, Wonwoong; Shin, Jaein; Baek, Soonbong; Jang, Wonhee; Jun, Won; Kim, Soochan; Hong, Jongki; Park, Hi-Joon; Lengner, Christopher J.; Moh, Sang Hyun; Kwon, Youngeun; Kim, Jongpil

2017-10-01

Electromagnetic fields (EMF) are physical energy fields generated by electrically charged objects, and specific ranges of EMF can influence numerous biological processes, which include the control of cell fate and plasticity. In this study, we show that electromagnetized gold nanoparticles (AuNPs) in the presence of specific EMF conditions facilitate an efficient direct lineage reprogramming to induced dopamine neurons in vitro and in vivo. Remarkably, electromagnetic stimulation leads to a specific activation of the histone acetyltransferase Brd2, which results in histone H3K27 acetylation and a robust activation of neuron-specific genes. In vivo dopaminergic neuron reprogramming by EMF stimulation of AuNPs efficiently and non-invasively alleviated symptoms in mouse Parkinson's disease models. This study provides a proof of principle for EMF-based in vivo lineage conversion as a potentially viable and safe therapeutic strategy for the treatment of neurodegenerative disorders.

Mechanisms of boron fiber strengthening by thermal treatment

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.

1979-01-01

The fracture strain for boron on tungsten fibers was studied for improvement by heat treatment under vacuum or argon environments. The mechanical basis for this improvement is thermally-induced axial contraction of the entire fiber, whereby strength-controlling core flaws are compressed and fiber fracture strain increased by the value of the contraction strain. By highly sensitive measurements of fiber density and volume, the physical mechanism responsible for contraction under both environments was identified as boron atom diffusion out of the fiber sheath. The fiber contracts because the average volume of the resulting microvoid was determined to be only 0.26 plus or minus 0.09 the average atomic volume of the removed atom. The basic and practical implications of these results are discussed with particular emphasis on the theory, use, and limitations of heat-induced contraction as a simple cost-effective secondary processing method.

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

Pern, F.J.; Glick, S.H.; Czanderna, A.W.

The stabilization effects of various superstrate materials against UV-induced EVA discoloration and the effect of photocurrent enhancement by white light-reflecting substrates are summarized. Based on the results, some alternative PV module encapsulation schemes are proposed for improved module performance, where the current or modified formulations of EVA encapsulants still can be used so that the typical processing tools and conditions need not to be changed significantly. The schemes are designed in an attempt to eliminate or minimize the EVA yellow-browning and to increase the module power output. Four key experimental results from the studies of EVA discoloration and encapsulation aremore » to employ: (1) UV-absorbing (filtering) glasses as superstrates to protect EVA from UV-induced discoloration, (2) gas-permeable polymer films as superstrates and/or substrates to prevent EVA yellowing by permitting photobleaching reactions, (3) modified EVA formulations, and (4) internal reflection of the light by white substrates. {copyright} {ital 1996 American Institute of Physics.}« less

Objectively discriminating the optical analogy of electromagnetically induced transparency from Autler-Townes splitting in a side coupled graphene-based waveguide system

NASA Astrophysics Data System (ADS)

Wei, Buzheng; Jian, Shuisheng

2017-11-01

A mid-infrared side coupled graphene nanotube waveguide system is proposed to investigate the origin discerning from electromagnetically induced transparency (EIT) to Autler-Townes splitting (ATS). The analytic transmission analysis seeks an evolution tendency of transmission spectrum from ATS to EIT, which is numerically verified by the simulation results. The origin of transparency is mainly attributed to ATS effect in the strong coupling regime while EIT is favored in the weak coupling condition. We plot the field distribution to help understand the underlying physics of the interference process. The high group index of 5000 indicates that a slow light effect is successfully observed and Fano resonance is presented by varying the Fermi energy of the dark mode. These ideas may provide potential views in filters, optical buffers, light storage and on chip metamaterials.

Photo-induced spatial modulation of THz waves: opportunities and limitations.

PubMed

Kannegulla, Akash; Shams, Md Itrat Bin; Liu, Lei; Cheng, Li-Jing

2015-12-14

Programmable conductive patterns created by photoexcitation of semiconductor substrates using digital light processing (DLP) provides a versatile approach for spatial and temporal modulation of THz waves. The reconfigurable nature of the technology has great potential in implementing several promising THz applications, such as THz beam steering, THz imaging or THz remote sensing, in a simple, cost-effective manner. In this paper, we provide physical insight about how the semiconducting materials, substrate dimension, optical illumination wavelength and illumination size impact the performance of THz modulation, including modulation depth, modulation speed and spatial resolution. The analysis establishes design guidelines for the development of photo-induced THz modulation technology. Evolved from the theoretical analysis, a new mesa array technology composed by a matrix of sub-THz wavelength structures is introduced to maximize both spatial resolution and modulation depth for THz modulation with low-power photoexcitation by prohibiting the lateral diffusion of photogenerated carriers.

Giant magnetic splitting inducing near-unity valley polarization in van der Waals heterostructures.

PubMed

Nagler, Philipp; Ballottin, Mariana V; Mitioglu, Anatolie A; Mooshammer, Fabian; Paradiso, Nicola; Strunk, Christoph; Huber, Rupert; Chernikov, Alexey; Christianen, Peter C M; Schüller, Christian; Korn, Tobias

2017-11-16

Monolayers of semiconducting transition metal dichalcogenides exhibit intriguing fundamental physics of strongly coupled spin and valley degrees of freedom for charge carriers. While the possibility of exploiting these properties for information processing stimulated concerted research activities towards the concept of valleytronics, maintaining control over spin-valley polarization proved challenging in individual monolayers. A promising alternative route explores type II band alignment in artificial van der Waals heterostructures. The resulting formation of interlayer excitons combines the advantages of long carrier lifetimes and spin-valley locking. Here, we demonstrate artificial design of a two-dimensional heterostructure enabling intervalley transitions that are not accessible in monolayer systems. The resulting giant effective g factor of -15 for interlayer excitons induces near-unity valley polarization via valley-selective energetic splitting in high magnetic fields, even after nonselective excitation. Our results highlight the potential to deterministically engineer novel valley properties in van der Waals heterostructures using crystallographic alignment.

Anomalous Hall effect scaling in ferromagnetic thin films

NASA Astrophysics Data System (ADS)

Grigoryan, Vahram L.; Xiao, Jiang; Wang, Xuhui; Xia, Ke

2017-10-01

We propose a scaling law for anomalous Hall effect in ferromagnetic thin films. Our approach distinguishes multiple scattering sources, namely, bulk impurity, phonon for Hall resistivity, and most importantly the rough surface contribution to longitudinal resistivity. In stark contrast to earlier laws that rely on temperature- and thickness-dependent fitting coefficients, this scaling law fits the recent experimental data excellently with constant parameters that are independent of temperature and film thickness, strongly indicating that this law captures the underlying physical processes. Based on a few data points, this scaling law can even fit all experimental data in full temperature and thickness range. We apply this law to interpret the experimental data for Fe, Co, and Ni and conclude that (i) the phonon-induced skew scattering is unimportant as expected; (ii) contribution from the impurity-induced skew scattering is negative; (iii) the intrinsic (extrinsic) mechanism dominates in Fe (Co), and both the extrinsic and intrinsic contributions are important in Ni.

Single-mode dispersive waves and soliton microcomb dynamics

PubMed Central

Yi, Xu; Yang, Qi-Fan; Zhang, Xueyue; Yang, Ki Youl; Li, Xinbai; Vahala, Kerry

2017-01-01

Dissipative Kerr solitons are self-sustaining optical wavepackets in resonators. They use the Kerr nonlinearity to both compensate dispersion and offset optical loss. Besides providing insights into nonlinear resonator physics, they can be applied in frequency metrology, precision clocks, and spectroscopy. Like other optical solitons, the dissipative Kerr soliton can radiate power as a dispersive wave through a process that is the optical analogue of Cherenkov radiation. Dispersive waves typically consist of an ensemble of optical modes. Here, a limiting case is studied in which the dispersive wave is concentrated into a single cavity mode. In this limit, its interaction with the soliton induces hysteresis behaviour in the soliton's spectral and temporal properties. Also, an operating point of enhanced repetition-rate stability occurs through balance of dispersive-wave recoil and Raman-induced soliton-self-frequency shift. The single-mode dispersive wave can therefore provide quiet states of soliton comb operation useful in many applications. PMID:28332495

Rapid and reversible photoinduced switching of a rotaxane crystal

NASA Astrophysics Data System (ADS)

Chen, Kai-Jen; Tsai, Ya-Ching; Suzaki, Yuji; Osakada, Kohtaro; Miura, Atsushi; Horie, Masaki

2016-11-01

Crystalline phase transitions caused by external stimuli have been used to detect physical changes in the solid-state properties. This study presents the mechanical switching of crystals of ferrocene-containing rotaxane controlled by focused laser light. The expansion and contraction of the crystals can be driven by turning on and off laser light at 445 nm. The irradiation-induced expansion of the crystal involves elongation along the a, b and c axes at 30 °C, whereas heating of the crystal at 105 °C causes the shortening of c axis. The expansions reversibly occur and have the advantage of a rapid relaxation (reverse) process. Single-crystal X-ray crystallography reveals the detailed structural changes of the molecules, corresponding to a change in the size of the crystals on laser irradiation. This molecular crystal behaviour induced by laser irradiation, is demonstrated for the remote control of objects, namely, microparticle transport and microswitching in an electric circuit.

Probing Photocurrent Nonuniformities in the Subcells of Monolithic Perovskite/Silicon Tandem Solar Cells.

PubMed

Song, Zhaoning; Werner, Jérémie; Shrestha, Niraj; Sahli, Florent; De Wolf, Stefaan; Niesen, Björn; Watthage, Suneth C; Phillips, Adam B; Ballif, Christophe; Ellingson, Randy J; Heben, Michael J

2016-12-15

Perovskite/silicon tandem solar cells with high power conversion efficiencies have the potential to become a commercially viable photovoltaic option in the near future. However, device design and optimization is challenging because conventional characterization methods do not give clear feedback on the localized chemical and physical factors that limit performance within individual subcells, especially when stability and degradation is a concern. In this study, we use light beam induced current (LBIC) to probe photocurrent collection nonuniformities in the individual subcells of perovskite/silicon tandems. The choices of lasers and light biasing conditions allow efficiency-limiting effects relating to processing defects, optical interference within the individual cells, and the evolution of water-induced device degradation to be spatially resolved. The results reveal several types of microscopic defects and demonstrate that eliminating these and managing the optical properties within the multilayer structures will be important for future optimization of perovskite/silicon tandem solar cells.

Quantum-optical nonlinearities induced by Rydberg-Rydberg interactions: A perturbative approach

NASA Astrophysics Data System (ADS)

Grankin, A.; Brion, E.; Bimbard, E.; Boddeda, R.; Usmani, I.; Ourjoumtsev, A.; Grangier, P.

2015-10-01

In this article, we theoretically study the quantum statistical properties of the light transmitted through or reflected from an optical cavity, filled by an atomic medium with strong optical nonlinearity induced by Rydberg-Rydberg van der Waals interactions. Atoms are driven on a two-photon transition from their ground state to a Rydberg level via an intermediate state by the combination of a weak signal field and a strong control beam. By using a perturbative approach, we get analytic results which remain valid in the regime of weak feeding fields, even when the intermediate state becomes resonant thus generalizing our previous results. We can thus investigate quantitatively new features associated with the resonant behavior of the system. We also propose an effective nonlinear three-boson model of the system which, in addition to leading to the same analytic results as the original problem, sheds light on the physical processes at work in the system.

Maternal modulation of novelty effects on physical development.

PubMed

Tang, Akaysha C; Yang, Zhen; Reeb-Sutherland, Bethany C; Romeo, Russell D; McEwen, Bruce S

2012-02-07

Familiarity to the mother and the novelty afforded by the postnatal environment are two contrasting sources of neonatal influence. One hypothesis regarding their relationship is the maternal modulation hypothesis, which predicts that the same neonatal stimulation may have different effects depending on the maternal context. Here we tested this hypothesis using physical development, indexed by body weight, as an endpoint and found that, among offspring of mothers with a high initial swim-stress-induced corticosterone (CORT) response, neonatal novelty exposure induced an enhancement in early growth, and among offspring with mothers of a low initial CORT response, the same neonatal stimulation induced an impairment. At an older age, a novelty-induced increase in body weight was also found among offspring of mothers with high postnatal care reliability and a novelty-induced reduction found among offspring of mothers with low care reliability. These results support a maternal modulation of early stimulation effects on physical development and demonstrate that the maternal influence originates from multiple instead of any singular sources. These results (i) significantly extend the findings of maternal modulation from the domain of cognitive development to the domain of physical development; (ii) offer a unifying explanation for a previously inconsistent literature regarding early stimulation effects on body weight; and (iii) highlight the notion that the early experience effect involves no causal primacy but higher order interactions among the initial triggering events and subsequent events involving a multitude of maternal and nonmaternal influences.

Copper Ion Beam Irradiation-Induced Effects on Structural, Morphological and Optical Properties of Tin Dioxide Nanowires

NASA Astrophysics Data System (ADS)

A. Khan, M.; Qayyum, A.; I., Ahmed; T., Iqbal; A. Khan, A.; Waleed, R.; Mohuddin, B.; Malik, M.

2016-07-01

Not Available Supported by the Department of Physics, the University of AJK, High Tech. Centralized Instrumentation Lab, the University of AJK, Pakistan and the Experimental Physics Division, and the National Center for Physics, Islamabad Pakistan.

Time-lapse seismic waveform modelling and attribute analysis using hydromechanical models for a deep reservoir undergoing depletion

NASA Astrophysics Data System (ADS)

He, Y.-X.; Angus, D. A.; Blanchard, T. D.; Wang, G.-L.; Yuan, S.-Y.; Garcia, A.

2016-04-01

Extraction of fluids from subsurface reservoirs induces changes in pore pressure, leading not only to geomechanical changes, but also perturbations in seismic velocities and hence observable seismic attributes. Time-lapse seismic analysis can be used to estimate changes in subsurface hydromechanical properties and thus act as a monitoring tool for geological reservoirs. The ability to observe and quantify changes in fluid, stress and strain using seismic techniques has important implications for monitoring risk not only for petroleum applications but also for geological storage of CO2 and nuclear waste scenarios. In this paper, we integrate hydromechanical simulation results with rock physics models and full-waveform seismic modelling to assess time-lapse seismic attribute resolution for dynamic reservoir characterization and hydromechanical model calibration. The time-lapse seismic simulations use a dynamic elastic reservoir model based on a North Sea deep reservoir undergoing large pressure changes. The time-lapse seismic traveltime shifts and time strains calculated from the modelled and processed synthetic data sets (i.e. pre-stack and post-stack data) are in a reasonable agreement with the true earth models, indicating the feasibility of using 1-D strain rock physics transform and time-lapse seismic processing methodology. Estimated vertical traveltime shifts for the overburden and the majority of the reservoir are within ±1 ms of the true earth model values, indicating that the time-lapse technique is sufficiently accurate for predicting overburden velocity changes and hence geomechanical effects. Characterization of deeper structure below the overburden becomes less accurate, where more advanced time-lapse seismic processing and migration is needed to handle the complex geometry and strong lateral induced velocity changes. Nevertheless, both migrated full-offset pre-stack and near-offset post-stack data image the general features of both the overburden and reservoir units. More importantly, the results from this study indicate that integrated seismic and hydromechanical modelling can help constrain time-lapse uncertainty and hence reduce risk due to fluid extraction and injection.

MAPLE deposition of nanomaterials

NASA Astrophysics Data System (ADS)

Caricato, A. P.; Arima, V.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Martino, M.; Taurino, A.; Rella, R.; Scarfiello, R.; Tunno, T.; Zacheo, A.

2014-05-01

The matrix-assisted pulsed laser evaporation (MAPLE) has been recently exploited for depositing films of nanomaterials by combining the advantages of colloidal inorganic nanoparticles and laser-based techniques. MAPLE-deposition of nanomaterials meeting applicative purposes demands their peculiar properties to be taken into account while planning depositions to guarantee a congruent transfer (in terms of crystal structure and geometric features) and explain the deposition outcome. In particular, since nanofluids can enhance thermal conductivity with respect to conventional fluids, laser-induced heating can induce different ablation thermal regimes as compared to the MAPLE-treatment of soft materials. Moreover, nanoparticles exhibit lower melting temperatures and can experience pre-melting phenomena as compared to their bulk counterparts, which could easily induce shape and or crystal phase modification of the material to be deposited even at very low fluences. In this complex scenario, this review paper focuses on examples of MAPLE-depositions of size and shape controlled nanoparticles for different applications highlights advantages and challenges of the MAPLE-technique. The influence of the deposition parameters on the physical mechanisms which govern the deposition process is discussed.

Quantitative mapping of zinc fluxes in the mammalian egg reveals the origin of fertilization-induced zinc sparks

DOE PAGES

Que, Emily L.; Bleher, Reiner; Duncan, Francesca E.; ...

2014-12-15

Fertilization of a mammalian egg induces a series of ‘zinc sparks’ that are necessary for inducing the egg-to-embryo transition. Despite the importance of these zinc efflux events little is known about their origin. To understand the molecular mechanism of the zinc spark we combined four physical approaches to resolve zinc distributions in single cells: a chemical probe for dynamic live-cell fluorescence imaging and a combination of scanning transmission electron microscopy with energy dispersive spectroscopy, X-ray fluorescence microscopy, and 3D elemental tomography for high resolution elemental mapping. Here we show that the zinc spark arises from a system of thousands ofmore » zinc-loaded vesicles, each of which contains, on average, 106 zinc atoms. These vesicles undergo dynamic movement during oocyte maturation and exocytosis at the time of fertilization. We conclude that the discovery of these vesicles and the demonstration that zinc sparks originate from them provides a quantitative framework for understanding how zinc fluxes regulate cellular processes.« less

Multi-physics modelling contributions to investigate the atmospheric cosmic rays on the single event upset sensitivity along the scaling trend of CMOS technologies.

PubMed

Hubert, G; Regis, D; Cheminet, A; Gatti, M; Lacoste, V

2014-10-01

Particles originating from primary cosmic radiation, which hit the Earth's atmosphere give rise to a complex field of secondary particles. These particles include neutrons, protons, muons, pions, etc. Since the 1980s it has been known that terrestrial cosmic rays can penetrate the natural shielding of buildings, equipment and circuit package and induce soft errors in integrated circuits. Recently, research has shown that commercial static random access memories are now so small and sufficiently sensitive that single event upsets (SEUs) may be induced from the electronic stopping of a proton. With continued advancements in process size, this downward trend in sensitivity is expected to continue. Then, muon soft errors have been predicted for nano-electronics. This paper describes the effects in the specific cases such as neutron-, proton- and muon-induced SEU observed in complementary metal-oxide semiconductor. The results will allow investigating the technology node sensitivity along the scaling trend. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Microbial production of metabolites and associated enzymatic reactions under high pressure.

PubMed

Dong, Yongsheng; Jiang, Hua

2016-11-01

High environmental pressure exerts an external stress on the survival of microorganisms that are commonly found under normal pressure. In response, many growth traits alter, including cell morphology and physiology, cellular structure, metabolism, physical and chemical properties, the reproductive process, and defense mechanisms. The high-pressure technology (HP) has been industrially utilized in pressurized sterilization, synthesis of stress-induced products, and microbial/enzymatic transformation of chemicals. This article reviews current research on pressure-induced production of metabolites in normal-pressure microbes and their enzymatic reactions. Factors that affect the production of such metabolites are summarized, as well as the effect of pressure on the performance of microbial fermentation and the yield of flavoring compounds, different categories of induced enzymatic reactions and their characteristics in the supercritical carbon dioxide fluid, effects on enzyme activity, and the selection of desirable bacterial strains. Technological challenges are discussed, and future research directions are proposed. Information presented here will benefit the research, development, and application of the HP technology to improve microbial fermentation and enzymatic production of biologically active substances, thereby help to meet their increasing demand from the ever-expanding market.

Collective interaction of microscale matters in natural analogy: human cancer cells vs. microspheres

NASA Astrophysics Data System (ADS)

Ahn, Sungsook; Lee, Sang Joon; Postech Team

2014-11-01

Collective behaviors have been considered both in living and lifeless things as a natural phenomenon. During the ordering process, a sudden and spontaneous transition is typically generated between an order and a disorder according to the population density of interacting elements. In a cellular level collective behavior, the cells are distributed in the characteristic patterns according to the population density and the mutual interaction of the individual cells undergo density-dependent diffusive motion. On the other hand, density-controlled surface-modified hollow microsphere suspension induces an overpopulation via buoyancy which provides a driving force to induce an assembly. The collective behaviors of the cells and microspheres in a designed liquid medium are explained in terms of the deviation from the interparticle distance distribution and the induced strength to organize the particle position in a specific distance range. as a result, microscale particulate matters exhibit high resemblance in their pair correlation and dynamical heterogeneity in the intermediate range between a single individual and an agglomerate. Therefore, it is suggested that biological systems are analogically explained to be dominated by physically interactive aspects.

Sensitivity of Induced Seismic Sequences to Rate-and-State Frictional Processes

NASA Astrophysics Data System (ADS)

Kroll, Kayla A.; Richards-Dinger, Keith B.; Dieterich, James H.

2017-12-01

It is well established that subsurface injection of fluids increases pore fluid pressures that may lead to shear failure along a preexisting fault surface. Concern among oil and gas, geothermal, and carbon storage operators has risen dramatically over the past decade due to the increase in the number and magnitude of induced earthquakes. Efforts to mitigate the risk associated with injection-induced earthquakes include modeling of the interaction between fluids and earthquake faults. Here we investigate this relationship with simulations that couple a geomechanical reservoir model and RSQSim, a physics-based earthquake simulator. RSQSim employs rate- and state-dependent friction (RSF) that enables the investigation of the time-dependent nature of earthquake sequences. We explore the effect of two RSF parameters and normal stress on the spatiotemporal characteristics of injection-induced seismicity. We perform >200 simulations to systematically investigate the effect of these model components on the evolution of induced seismicity sequences and compare the spatiotemporal characteristics of our synthetic catalogs to observations of induced earthquakes. We find that the RSF parameters control the ability of seismicity to migrate away from the injection well, the total number and maximum magnitude of induced events. Additionally, the RSF parameters control the occurrence/absence of premonitory events. Lastly, we find that earthquake stress drops can be modulated by the normal stress and/or the RSF parameters. Insight gained from this study can aid in further development of models that address best practice protocols for injection operations, site-specific models of injection-induced earthquakes, and probabilistic hazard and risk assessments.

Sensitivity of Induced Seismic Sequences to Rate-and-State Frictional Processes

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

Kroll, Kayla A.; Richards-Dinger, Keith B.; Dieterich, James H.

It is well established that subsurface injection of fluids increases pore fluid pressures that may lead to shear failure along a preexisting fault surface. Concern among oil and gas, geothermal, and carbon storage operators has risen dramatically over the past decade due to the increase in the number and magnitude of induced earthquakes. Efforts to mitigate the risk associated with injection-induced earthquakes include modeling of the interaction between fluids and earthquake faults. Here we investigate this relationship with simulations that couple a geomechanical reservoir model and RSQSim, a physics-based earthquake simulator. RSQSim employs rate- and state-dependent friction (RSF) that enablesmore » the investigation of the time-dependent nature of earthquake sequences. We explore the effect of two RSF parameters and normal stress on the spatiotemporal characteristics of injection-induced seismicity. We perform >200 simulations to systematically investigate the effect of these model components on the evolution of induced seismicity sequences and compare the spatiotemporal characteristics of our synthetic catalogs to observations of induced earthquakes. We find that the RSF parameters control the ability of seismicity to migrate away from the injection well, the total number and maximum magnitude of induced events. Additionally, the RSF parameters control the occurrence/absence of premonitory events. Finally, we find that earthquake stress drops can be modulated by the normal stress and/or the RSF parameters. Insight gained from this study can aid in further development of models that address best practice protocols for injection operations, site-specific models of injection-induced earthquakes, and probabilistic hazard and risk assessments.« less

Sensitivity of Induced Seismic Sequences to Rate-and-State Frictional Processes

DOE PAGES

Kroll, Kayla A.; Richards-Dinger, Keith B.; Dieterich, James H.

2017-11-09

It is well established that subsurface injection of fluids increases pore fluid pressures that may lead to shear failure along a preexisting fault surface. Concern among oil and gas, geothermal, and carbon storage operators has risen dramatically over the past decade due to the increase in the number and magnitude of induced earthquakes. Efforts to mitigate the risk associated with injection-induced earthquakes include modeling of the interaction between fluids and earthquake faults. Here we investigate this relationship with simulations that couple a geomechanical reservoir model and RSQSim, a physics-based earthquake simulator. RSQSim employs rate- and state-dependent friction (RSF) that enablesmore » the investigation of the time-dependent nature of earthquake sequences. We explore the effect of two RSF parameters and normal stress on the spatiotemporal characteristics of injection-induced seismicity. We perform >200 simulations to systematically investigate the effect of these model components on the evolution of induced seismicity sequences and compare the spatiotemporal characteristics of our synthetic catalogs to observations of induced earthquakes. We find that the RSF parameters control the ability of seismicity to migrate away from the injection well, the total number and maximum magnitude of induced events. Additionally, the RSF parameters control the occurrence/absence of premonitory events. Finally, we find that earthquake stress drops can be modulated by the normal stress and/or the RSF parameters. Insight gained from this study can aid in further development of models that address best practice protocols for injection operations, site-specific models of injection-induced earthquakes, and probabilistic hazard and risk assessments.« less

Assessment of bridge abutment scour and sediment transport under various flow conditions

NASA Astrophysics Data System (ADS)

Gilja, Gordon; Valyrakis, Manousos; Michalis, Panagiotis; Bekić, Damir; Kuspilić, Neven; McKeogh, Eamon

2017-04-01

Safety of bridges over watercourses can be compromised by flow characteristics and bridge hydraulics. Scour process around bridge foundations can develop rapidly during low-recurrence interval floods when structural elements are exposed to increased flows. Variations in riverbed geometry, as a result of sediment removal and deposition processes, can increase flood-induced hazard at bridge sites with catastrophic failures and destructive consequences for civil infrastructure. The quantification of flood induced hazard on bridge safety generally involves coupled hydrodynamic and sediment transport models (i.e. 2D numerical or physical models) for a range of hydrological events covering both high and low flows. Modelled boundary conditions are usually estimated for their probability of occurrence using frequency analysis of long-term recordings at gauging stations. At smaller rivers gauging station records are scarce, especially in upper courses of rivers where weirs, drops and rapids are common elements of river bathymetry. As a result, boundary conditions that accurately represent flow patterns on modelled river reach cannot be often reliably acquired. Sediment transport process is also more complicated to describe due to its complexity and dependence to local flow field making scour hazard assessment a particularly challenging issue. This study investigates the influence of flow characteristics to the development of scour and sedimentation processes around bridge abutments of a single span masonry arch bridge in south Ireland. The impact of downstream weirs on bridge hydraulics through variation of downstream model domain type is also considered in this study. The numerical model is established based on detailed bathymetry data surveyed along a rectangular grid of 50cm spacing. Acquired data also consist of riverbed morphology and water level variations which are monitored continuously on bridge site. The obtained data are then used to compare and calibrate numerical models for several flood scenarios. The determination of the boundary conditions is followed by physical modelling to investigate the development of scour around bridge elements. The comparison of surveyed data with the obtained numerical and physical modelling results provide an insight of various flow patterns and their influence on riverbed morphology. This can deliver important information needed for assessment of structural risk associated with flood events. Acknowledgement: The authors wish to acknowledge the financial support of the European Commission, through the Marie Curie action Industry-Academia Partnership and Pathways Network BRIDGE SMS (Intelligent Bridge Assessment Maintenance and Management System) - FP7-People-2013-IAPP- 612517.

Tsunami-induced boulder transport - combining physical experiments and numerical modelling

NASA Astrophysics Data System (ADS)

Oetjen, Jan; Engel, Max; May, Simon Matthias; Schüttrumpf, Holger; Brueckner, Helmut; Prasad Pudasaini, Shiva

2016-04-01

Coasts are crucial areas for living, economy, recreation, transportation, and various sectors of industry. Many of them are exposed to high-energy wave events. With regard to the ongoing population growth in low-elevation coastal areas, the urgent need for developing suitable management measures, especially for hazards like tsunamis, becomes obvious. These measures require supporting tools which allow an exact estimation of impact parameters like inundation height, inundation area, and wave energy. Focussing on tsunamis, geological archives can provide essential information on frequency and magnitude on a longer time scale in order to support coastal hazard management. While fine-grained deposits may quickly be altered after deposition, multi-ton coarse clasts (boulders) may represent an information source on past tsunami events with a much higher preservation potential. Applying numerical hydrodynamic coupled boulder transport models (BTM) is a commonly used approach to analyse characteristics (e.g. wave height, flow velocity) of the corresponding tsunami. Correct computations of tsunamis and the induced boulder transport can provide essential event-specific information, including wave heights, runup and direction. Although several valuable numerical models for tsunami-induced boulder transport exist (e. g. Goto et al., 2007; Imamura et al., 2008), some important basic aspects of both tsunami hydrodynamics and corresponding boulder transport have not yet been entirely understood. Therefore, our project aims at these questions in four crucial aspects of boulder transport by a tsunami: (i) influence of sediment load, (ii) influence of complex boulder shapes other than idealized rectangular shapes, (iii) momentum transfers between multiple boulders, and (iv) influence of non-uniform bathymetries and topographies both on tsunami and boulder. The investigation of these aspects in physical experiments and the correct implementation of an advanced model is an urgent need since they have been largely neglected. In order to tackle these gaps, we develop a novel BTM in two steps. First, scaled physical experiments are performed that determine the exact hydrodynamic processes within a tsunami during boulder transportations. Furthermore, the experiments are the basis for calibrating the numerical BTM. The BTM is based on the numerical two-phase mass flow model of Pudasaini (2012) that employs an advanced and unified high-resolution computational tool for mixtures consisting of the solid and fluid components and their interactions. This allows for the motion of the boulder while interacting with the particle-laden tsunami on the inundated coastal plane as a function of the total fluid and solid stresses. Our approach leads to fundamentally new insights in to the essential physical processes in BTM. Goto, K., Chavanich, S. A., Imamura, F., Kunthasap, P., Matsui, T., Minoura, K., Sugawara, D. and Yanagisawa, H.: Distribution, origin and transport process of boulders deposited by the 2004 Indian Ocean tsunami at Pakarang Cape, Thailand. Sediment. Geol., 202, 821-837, 2007. Imamura, F., Goto, K. and Ohkubo, S.: A numerical model of the transport of a boulder by tsunami. J. Geophys. Res. Oceans, 113, C01008, 2008. Pudasaini, S. P.: A general two-phase debris flow model. J. Geophys. Res. Earth Surf., 117, F03010, 2012.

Shock response of nanoporous Cu--A molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Zhao, Fengpeng

2015-06-01

Shock response of porous materials can be of crucial significance for shock physics and bears many practical applications in materials synthesis and engineering. Molecular dynamics simulations are carried out to investigate shock response of nanoporous metal materials, including elastic-plastic deformation, Hugoniot states, shock-induced melting, partial or complete void collapse, hotspot formation, nanojetting, and vaporization. A model nanoporous Cu with cylindrical voids and a high porosity under shocking is established to investigate such physical properties as velocity, temperature, density, stress and von Mises stress at different stages of compression and release. The elastic-plastic and overtaking shocks are observed at different shock strengths. A modified power-law P- α model is proposed to describe the Hugoniot states. The Grüneisen equation of state is validated. Shock-induced melting shows no clear signs of bulk premelting or superheating. Void collapse via plastic flow nucleated from voids, and the exact processes are shock strength dependent. With increasing shock strengths, void collapse transits from the ``geometrical'' mode (collapse of a void is dominated by crystallography and void geometry and can be different from that of one another) to ``hydrodynamic'' mode (collapse of a void is similar to one another). The collapse may be achieved predominantly by plastic flows along the {111} slip planes, by way of alternating compression and tension zones, by means of transverse flows, via forward and transverse flows, or through forward nano-jetting. The internal jetting induces pronounced shock front roughening, leading to internal hotspot formation and sizable high speed jets on atomically flat free surfaces. P. O. Box 919-401, Mianyang, 621900, Sichuan, PRC.

THE HOW AND WHY OF THE MOVEMENT SYSTEM AS THE IDENTITY OF PHYSICAL THERAPY

PubMed Central

2017-01-01

The Movement System was adopted as the identity of physical therapy as one of the 8 guiding principles accompanying the Vision Statement of 2013. At its inception physical therapy was considered more of a technical field rather than that of a professional field. Physicians were to diagnose the patient's problem and the therapist was to follow the prescription provided by the physician with the primary purpose being to relieve symptoms such as pain or muscle weakness. Even by the 1960's, the prescription became more of a referral and there was recognition that therapists were making decisions about the patient's treatment and discharge disposition. The role of the physical therapist in pathokinesiologic problems has been well accepted over the years but as insights are gained about the role of movement in musculoskeletal pain, the concept of kinesiopathologic problems is being defined. Whether the movement dysfunction is from a pathokinesiologic or a kinesiopathologic mechanisms, the underlying physiologic process is movement which is the composite action of the movement system. This article provides a brief discussion of the steps leading to promotion of the identity and the reasons that further defining and promoting the movement system as the body system for which physical therapists are responsible is necessary for the full recognition of the profession. As suggested by the kinesiopathologic concept of movement inducing pathology, physical therapists can address the cause of musculoskeletal problems and not just symptoms or consequences such as the pathoanatomic problem. Level of Evidence: 5 PMID:29158948