Reversing the attention effect in figure-ground perception.

PubMed

Huang, Liqiang; Pashler, Harold

2009-10-01

Human visual perception is sometimes ambiguous, switching between different perceptual structures, and shifts of attention sometimes favor one perceptual structure over another. It has been proposed that, in figure-ground segmentation, attention to certain regions tends to cause those regions to be perceived as closer to the observer. Here, we show that this attention effect can be reversed under certain conditions. To account for these phenomena, we propose an alternative principle: The visual system chooses the interpretation that maximizes simplicity of the attended regions.

The computational nature of memory modification.

PubMed

Gershman, Samuel J; Monfils, Marie-H; Norman, Kenneth A; Niv, Yael

2017-03-15

Retrieving a memory can modify its influence on subsequent behavior. We develop a computational theory of memory modification, according to which modification of a memory trace occurs through classical associative learning, but which memory trace is eligible for modification depends on a structure learning mechanism that discovers the units of association by segmenting the stream of experience into statistically distinct clusters (latent causes). New memories are formed when the structure learning mechanism infers that a new latent cause underlies current sensory observations. By the same token, old memories are modified when old and new sensory observations are inferred to have been generated by the same latent cause. We derive this framework from probabilistic principles, and present a computational implementation. Simulations demonstrate that our model can reproduce the major experimental findings from studies of memory modification in the Pavlovian conditioning literature.

The Selfish Goal: autonomously operating motivational structures as the proximate cause of human judgment and behavior.

PubMed

Huang, Julie Y; Bargh, John A

2014-04-01

We propose the Selfish Goal model, which holds that a person's behavior is driven by psychological processes called goals that guide his or her behavior, at times in contradictory directions. Goals can operate both consciously and unconsciously, and when activated they can trigger downstream effects on a person's information processing and behavioral possibilities that promote only the attainment of goal end-states (and not necessarily the overall interests of the individual). Hence, goals influence a person as if the goals themselves were selfish and interested only in their own completion. We argue that there is an evolutionary basis to believe that conscious goals evolved from unconscious and selfish forms of pursuit. This theoretical framework predicts the existence of unconscious goal processes capable of guiding behavior in the absence of conscious awareness and control (the automaticity principle), the ability of the most motivating or active goal to constrain a person's information processing and behavior toward successful completion of that goal (the reconfiguration principle), structural similarities between conscious and unconscious goal pursuit (the similarity principle), and goal influences that produce apparent inconsistencies or counterintuitive behaviors in a person's behavior extended over time (the inconsistency principle). Thus, we argue that a person's behaviors are indirectly selected at the goal level but expressed (and comprehended) at the individual level.

First-principles calculations of K-shell X-ray absorption spectra for warm dense nitrogen

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

Li, Zi; Zhang, Shen; Kang, Wei

2016-05-15

X-ray absorption spectrum is a powerful tool for atomic structure detection on warm dense matter. Here, we perform first-principles molecular dynamics and X-ray absorption spectrum calculations on warm dense nitrogen along a Hugoniot curve. From the molecular dynamics trajectory, the detailed atomic structures are examined for each thermodynamical condition. The K-shell X-ray absorption spectrum is calculated, and its changes with temperature and pressure along the Hugoniot curve are discussed. The warm dense nitrogen systems may contain isolated nitrogen atoms, N{sub 2} molecules, and nitrogen clusters, which show quite different contributions to the total X-ray spectrum due to their different electronmore » density of states. The changes of X-ray spectrum along the Hugoniot curve are caused by the different nitrogen structures induced by the temperature and the pressure. Some clear signatures on X-ray spectrum for different thermodynamical conditions are pointed out, which may provide useful data for future X-ray experiments.« less

First principle investigation of electronic structure, chemical bonding and optical properties of tetrabarium gallium trinitride oxide single crystal

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

Khan, Saleem Ayaz, E-mail: sayaz_usb@yahoo.com; Azam, Sikander

The electronic band structure, valence electron charge density and optical susceptibilities of tetrabarium gallium trinitride (TGT) were calculated via first principle study. The electronic band structure calculation describes TGT as semiconductor having direct band gap of 1.38 eV. The valence electronic charge density contour verified the non-polar covalent nature of the bond. The absorption edge and first peak of dielectric tensor components showed electrons transition from N-p state to Ba-d state. The calculated uniaxial anisotropy (0.4842) and birefringence (−0.0061) of present paper is prearranged as follow the spectral components of the dielectric tensor. The first peak in energy loss functionmore » (ELOS) shows the energy loss of fast traveling electrons in the material. The first sharp peak produced in ELOS around 10.5 eV show plasmon loss having plasma frequencies 0.1536, 0.004 and 0.066 of dielectric tensor components. This plasmon loss also cause decrease in reflectivity spectra.« less

Self-organisation and motion in plants

NASA Astrophysics Data System (ADS)

Lenau, T. A.; Hesselberg, T.

2014-03-01

Self-organisation appeals to humans because difficult and repeated actions can be avoided through automation via bottom-up nonhierarchical processes. This is in contrast to the top-level controlled action strategy normally applied in automated products and in manufacturing. There are many situations where it is required that objects perform an action dependent on external stimuli. An example is automatic window blinds that open or closes in response to sunlight level. However, simpler and more robust designs could be made using the self-organising principles for movement found in many plants. Plants move to adapt to external conditions, e.g. sun-flower buds tracking the sun, touch-me-not Mimosa and Venus fly trap responding to mechanical stimuli by closing leaves to protect them and capture insects respectively. This paper describes 3 of the basic biomimetic principles used by plants to track the sun; i) light causing an inhibiting effect on the illuminated side causing it to bend, ii) light inducing a signal from the illuminated side that causes an action on the darker side and iii) light illuminating a number of sensing plates pointing upwards at an angle activate an expansion on the same side. A concept for mimicking the second principle is presented. It is a very simple and possible reliable self-organising structure that aligns a plate perpendicular to the source of illumination.

Factors Related to Continuation of Health Behaviours among Stroke Survivors

PubMed Central

Kudo, Makoto

2011-01-01

Abstract Purpose: This study investigated stroke survivors' perspectives of health behaviours after stroke. We aimed to explore the actual process by which stroke survivors changed their health behaviours. Method: Semi-structured interviews were conducted with 40 people in a 1-year prospective study in the regional city of Chiba, Japan. Interviews covered views of health behaviours in order to explore why patients change their risk factors. Data were analysed using the principles of modified grounded theory. Results: Six categories related to practising health behaviours were identified: cause of stroke, antithetic thinking, awareness of the body, fear of disease progression, view of health, and psychological meaning of practise. Stroke survivors constructed a meaning of practise for each health behaviour. The recognition of previous lifestyle as cause of stroke, hope for recovery, and fear of future progression influenced health behaviours. Conclusions: The key finding of this study is that when cognitive behavioural therapy principles are enforced, an important aspect is that stroke survivors recognize the possibility that previous lifestyle was a cause of stroke and appreciate the necessity of preventing a new stroke. PMID:25792892

The computational nature of memory modification

PubMed Central

Gershman, Samuel J; Monfils, Marie-H; Norman, Kenneth A; Niv, Yael

2017-01-01

Retrieving a memory can modify its influence on subsequent behavior. We develop a computational theory of memory modification, according to which modification of a memory trace occurs through classical associative learning, but which memory trace is eligible for modification depends on a structure learning mechanism that discovers the units of association by segmenting the stream of experience into statistically distinct clusters (latent causes). New memories are formed when the structure learning mechanism infers that a new latent cause underlies current sensory observations. By the same token, old memories are modified when old and new sensory observations are inferred to have been generated by the same latent cause. We derive this framework from probabilistic principles, and present a computational implementation. Simulations demonstrate that our model can reproduce the major experimental findings from studies of memory modification in the Pavlovian conditioning literature. DOI: http://dx.doi.org/10.7554/eLife.23763.001 PMID:28294944

Research on a new wave energy absorption device

NASA Astrophysics Data System (ADS)

Lu, Zhongyue; Shang, Jianzhong; Luo, Zirong; Sun, Chongfei; Zhu, Yiming

2018-01-01

To reduce impact of global warming and the energy crisis problems caused by pollution of energy combustion, the research on renewable and clean energies becomes more and more important. This paper designed a new wave absorption device, and also gave an introduction on its mechanical structure. The flow tube model is analyzed, and presented the formulation of the proposed method. To verify the principle of wave absorbing device, an experiment was carried out in a laboratory environment, and the results of the experiment can be applied for optimizing the structure design of output power.

A new submarine oil-water separation system

NASA Astrophysics Data System (ADS)

Cai, Wen-Bin; Liu, Bo-Hong

2017-12-01

In order to solve the oil field losses of environmental problems and economic benefit caused by the separation of lifting production liquid to offshore platforms in the current offshore oil production, from the most basic separation principle, a new oil-water separation system has been processed of adsorption and desorption on related materials, achieving high efficiency and separation of oil and water phases. And the submarine oil-water separation device has been designed. The main structure of the device consists of gas-solid phase separation device, period separating device and adsorption device that completed high efficiency separation of oil, gas and water under the adsorption and desorption principle, and the processing capacity of the device is calculated.

Nanodopant-Induced Band Modulation in AgPbmSbTe2+m-Type Nanocomposites

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

Zhang, Yi; Ke, Xuezhi; Chen, Changfeng

2011-01-01

We elucidate the fundamental physics of nanoscale dopants in narrow band-gap thermoelectric nanocomposites XPbmYTe2+m (X=Ag,Na; Y=Sb,Bi) using first-principles calculations. Our re- sults unveil distinct band-structure modulations, most notably a sizable band-gap widening driven by nanodopant-induced lattice strain and a band split-off at the conduction band minimum caused by the spin-orbit interaction of the dopant Sb or Bi atoms. Boltzmann transport calculations demon- strate that these band modulations have significant but competing effects on high-temperature elec- tron transport behavior. These results offer insights for understanding recent experimental findings and suggest principles for optimizing thermoelectric properties of narrow band-gap semiconductors.

A Novel Optical Fiber Sensor for Steel Corrosion in Concrete Structures.

PubMed

Leung, Christopher K Y; Wan, Kai Tai; Chen, Liquan

2008-03-20

Steel corrosion resulting from the penetration of chloride ions or carbon dioxide is a major cause of degradation for reinforced concrete structures,. The objective of the present investigation was to develop a low-cost sensor for steel corrosion, which is based on a very simple physical principle. The flat end of a cut optical fiber is coated with an iron thin film using the ion sputtering technique. Light is then sent into a fiber embedded in concrete and the reflected signal is monitored. Initially, most of the light is reflected by the iron layer. When corrosion occurs to remove the iron layer, a significant portion of the light power will leave the fiber at its exposed end, and the reflected power is greatly reduced. Monitoring of the reflected signal is hence an effective way to assess if the concrete environment at the location of the fiber tip may induce steel corrosion or not. In this paper, first the principle of the corrosion sensor and its fabrication are described. The sensing principle is then verified by experimental results. Sensor packaging for practical installation will be presented and the performance of the packaged sensors is assessed by additional experiments.

A Novel Optical Fiber Sensor for Steel Corrosion in Concrete Structures

PubMed Central

Leung, Christopher K.Y.; Wan, Kai Tai; Chen, Liquan

2008-01-01

Steel corrosion resulting from the penetration of chloride ions or carbon dioxide is a major cause of degradation for reinforced concrete structures,. The objective of the present investigation was to develop a low-cost sensor for steel corrosion, which is based on a very simple physical principle. The flat end of a cut optical fiber is coated with an iron thin film using the ion sputtering technique. Light is then sent into a fiber embedded in concrete and the reflected signal is monitored. Initially, most of the light is reflected by the iron layer. When corrosion occurs to remove the iron layer, a significant portion of the light power will leave the fiber at its exposed end, and the reflected power is greatly reduced. Monitoring of the reflected signal is hence an effective way to assess if the concrete environment at the location of the fiber tip may induce steel corrosion or not. In this paper, first the principle of the corrosion sensor and its fabrication are described. The sensing principle is then verified by experimental results. Sensor packaging for practical installation will be presented and the performance of the packaged sensors is assessed by additional experiments. PMID:27879805

Nonplanar core structure of the screw dislocations in tantalum from the improved Peierls-Nabarro theory

NASA Astrophysics Data System (ADS)

Hu, Xiangsheng; Wang, Shaofeng

2018-02-01

The extended structure of ? screw dislocation in Ta has been studied theoretically using the improved Peierls-Nabarro model combined with the first principles calculation. An instructive way to derive the fundamental equation for dislocations with the nonplanar structure is presented. The full ?-surface of ? plane in tantalum is evaluated from the first principles. In order to compare the energy of the screw dislocation with different structures, the structure parameter is introduced to describe the core configuration. Each kind of screw dislocation is described by an overall-shape component and a core component. Far from the dislocation centre, the asymptotic behaviour of dislocation is uniquely controlled by the overall-shape component. Near the dislocation centre, the structure detail is described by the core component. The dislocation energy is explicitly plotted as a function of the core parameter for the nonplanar dislocation as well as for the planar dislocation. It is found that in the physical regime of the core parameter, the sixfold nonplanar structure always has the lowest energy. Our result clearly confirms that the sixfold nonplanar structure is the most stable. Furthermore, the pressure effect on the dislocation structure is explored up to 100 GPa. The stability of the sixfold nonplanar structure is not changed by the applied pressure. The equilibrium structure and the related stress field are calculated, and a possible mechanism of the dislocation movement is discussed briefly based on the structure deformation caused by the external stress.

A practical guide to applying lean tools and management principles to health care improvement projects.

PubMed

Simon, Ross W; Canacari, Elena G

2012-01-01

Manufacturing organizations have used Lean management principles for years to help eliminate waste, streamline processes, and cut costs. This pragmatic approach to structured problem solving can be applied to health care process improvement projects. Health care leaders can use a step-by-step approach to document processes and then identify problems and opportunities for improvement using a value stream process map. Leaders can help a team identify problems and root causes and consider additional problems associated with methods, materials, manpower, machinery, and the environment by using a cause-and-effect diagram. The team then can organize the problems identified into logical groups and prioritize the groups by impact and difficulty. Leaders must manage action items carefully to instill a sense of accountability in those tasked to complete the work. Finally, the team leaders must ensure that a plan is in place to hold the gains. Copyright © 2012 AORN, Inc. Published by Elsevier Inc. All rights reserved.

Effects of interlayer screening and temperature on dielectric functions of graphene by first-principles

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

Yang, J. Y.; Liu, L. H., E-mail: lhliu@hit.edu.cn; Department of Physics, Harbin Institute of Technology, Harbin 150001

2016-07-21

The dielectric functions of few-layer graphene and the related temperature dependence are investigated from the atomic scale using first-principles calculations. Compared with ellipsometry experiments in the spectral range of 190–2500 nm, the normalized optical constants of mono-layer graphene demonstrate good agreement and further validate first-principles calculations. To interpret dielectric function of mono-layer graphene, the electronic band structure and density of states are analyzed. By comparing dielectric functions of mono-, bi-, and tri-layer graphene, it shows that interlayer screening strengthens intraband transition and greatly enhances the absorption peak located around 1 eV. The strengthened optical absorption is intrinsically caused by the increasing electronmore » states near the Fermi level. To investigate temperature effect, the first-principles calculations and lattice dynamics are combined. The lattice vibration enhances parallel optical absorption peak around 1 eV and induces redshift. Moreover, it is observed that the van der Waals force plays a key role in keeping the interlayer distance stable during dynamics simulations.« less

Math Activities that Encourage Inductive Thinking

ERIC Educational Resources Information Center

Freeman, Christopher

2005-01-01

There are two kinds of logical reasoning: "inductive" and "deductive". Inductive reasoning proceeds from effect back to cause, from special case to general principle. Detectives use it, examining the clues and conjecturing the actions that caused them. On the other hand, deductive reasoning proceeds from cause to effect, from principle to…

[Gait disorders in geriatric patients. Classification and therapy].

PubMed

Jahn, K; Heinze, C; Selge, C; Heßelbarth, K; Schniepp, R

2015-04-01

Slow walking with reduced body dynamics is a characteristic feature of locomotion in the elderly. Impaired mobility and falls associated with gait disorders significantly contribute to a reduced quality of life in the elderly. A gait disorder is not an inevitable consequence of aging. This article shows that it is worth recognizing specific deficits and differentiating specific aspects in multifactorial disorders because many causes can be well treated. Also provided are the bases for clinical classification and therapeutic principles. Review of recent literature and clinical review based on own experience and own scientific results. Common causes of disturbed gait in the elderly are neurological deficits, including sensory deficits (e.g. peripheral neuropathy and vestibulopathy), neurodegeneration (e.g. cerebellar ataxia and parkinsonian syndromes, cognitive impairment (e.g. degenerative dementia), degeneration of joints (e.g. coxarthrosis) and general loss of muscle mass (sarcopenia). Furthermore, a fear of falling also contributes to the gait disorder. Multimodal therapies are often necessary and the principles are presented. Identification of deficits is a prerequisite for specific therapy. As physical activity protects against cognitive impairment, reduces the risk of falling and improves overall quality of life, a structured assessment of causes for gait impairment is crucial.

Design of Edible Oil Degradation Tool by Using Electromagnetic Field Absorbtion Principle which was Characterized to Peroxide Number

NASA Astrophysics Data System (ADS)

Isnen, M.; Nasution, T. I.; Perangin-angin, B.

2016-08-01

The identification of changes in oil quality has been conducted by indicating the change of dielectric constant which was showed by sensor voltage. Sensor was formed from two parallel flats that worked by electromagnetic wave propagation principle. By measuring its amplitude of electromagnetic wave attenuation caused by interaction between edible oil samples and the sensor, dielectric constant could be identified and estimated as well as peroxide number. In this case, the parallel flats were connected to an electric oscillator 700 kHz. Furthermore, sensor system could showed measurable voltage differences for each different samples. The testing carried out to five oil samples after undergoing an oxidation treatment at fix temperature of 235oC for 0, 5, 10, 15 and 20 minutes. Iodometry method testing showed peroxide values about 1.99, 9.95, 5.96, 11.86, and 15.92 meq/kg respectively with rising trend. Besides that, the testing result by sensor system showed voltages values 1.139, 1.147, 1.165, 1.173, and 1.176 volts with rising trend, respectively. It means that the higher sensor voltages showed the higher damage rate of edible oil when the change in sensor voltage was caused by the change in oil dielectric constant in which heating process caused damage in edible oil molecules structure. The more damage of oil structure caused the more difficulties of oil molecules to polarize and it is indicated by smaller dielectric constant. Therefore electric current would be smaller when sensor voltage was higher. On the other side, the higher sensor voltage means the smaller dielectric constant and the higher peroxide number.

Residual-QSAR. Implications for genotoxic carcinogenesis

PubMed Central

2011-01-01

Introduction Both main types of carcinogenesis, genotoxic and epigenetic, were examined in the context of non-congenericity and similarity, respectively, for the structure of ligand molecules, emphasizing the role of quantitative structure-activity relationship ((Q)SAR) studies in accordance with OECD (Organization for Economic and Cooperation Development) regulations. The main purpose of this report involves electrophilic theory and the need for meaningful physicochemical parameters to describe genotoxicity by a general mechanism. Residual-QSAR Method The double or looping multiple linear correlation was examined by comparing the direct and residual structural information against the observed activity. A self-consistent equation of observed-computed activity was assumed to give maximum correlation efficiency for those situations in which the direct correlations gave non-significant statistical information. Alternatively, it was also suited to describe slow and apparently non-noticeable cancer phenomenology, with special application to non-congeneric molecules involved in genotoxic carcinogenesis. Application and Discussions The QSAR principles were systematically applied to a given pool of molecules with genotoxic activity in rats to elucidate their carcinogenic mechanisms. Once defined, the endpoint associated with ligand-DNA interaction was used to select variables that retained the main Hansch physicochemical parameters of hydrophobicity, polarizability and stericity, computed by the custom PM3 semiempirical quantum method. The trial and test sets of working molecules were established by implementing the normal Gaussian principle of activities that applies when the applicability domain is not restrained to the congeneric compounds, as in the present study. The application of the residual, self-consistent QSAR method and the factor (or average) method yielded results characterized by extremely high and low correlations, respectively, with the latter resembling the direct activity to parameter QSARs. Nevertheless, such contrasted correlations were further incorporated into the advanced statistical minimum paths principle, which selects the minimum hierarchy from Euclidean distances between all considered QSAR models for all combinations and considered molecular sets (i.e., school and validation). This ultimately led to a mechanistic picture based on the identified alpha, beta and gamma paths connecting structural indicators (i.e., the causes) to the global endpoint, with all included causes. The molecular mechanism preserved the self-consistent feature of the residual QSAR, with each descriptor appearing twice in the course of one cycle of ligand-DNA interaction through inter-and intra-cellular stages. Conclusions Both basal features of the residual-QSAR principle of self-consistency and suitability for non-congeneric molecules make it appropriate for conceptually assessing the mechanistic description of genotoxic carcinogenesis. Additionally, it could be extended to enriched physicochemical structural indices by considering the molecular fragments or structural alerts (or other molecular residues), providing more detailed maps of chemical-biological interactions and pathways. PMID:21668999

Selective vulnerability of Rich Club brain regions is an organizational principle of structural connectivity loss in Huntington’s disease

PubMed Central

Seunarine, Kiran K.; Razi, Adeel; Cole, James H.; Gregory, Sarah; Durr, Alexandra; Roos, Raymund A. C.; Stout, Julie C.; Landwehrmeyer, Bernhard; Scahill, Rachael I.; Clark, Chris A.; Rees, Geraint

2015-01-01

Huntington’s disease can be predicted many years before symptom onset, and thus makes an ideal model for studying the earliest mechanisms of neurodegeneration. Diffuse patterns of structural connectivity loss occur in the basal ganglia and cortex early in the disease. However, the organizational principles that underlie these changes are unclear. By understanding such principles we can gain insight into the link between the cellular pathology caused by mutant huntingtin and its downstream effect at the macroscopic level. The ‘rich club’ is a pattern of organization established in healthy human brains, where specific hub ‘rich club’ brain regions are more highly connected to each other than other brain regions. We hypothesized that selective loss of rich club connectivity might represent an organizing principle underlying the distributed pattern of structural connectivity loss seen in Huntington’s disease. To test this hypothesis we performed diffusion tractography and graph theoretical analysis in a pseudo-longitudinal study of 50 premanifest and 38 manifest Huntington’s disease participants compared with 47 healthy controls. Consistent with our hypothesis we found that structural connectivity loss selectively affected rich club brain regions in premanifest and manifest Huntington’s disease participants compared with controls. We found progressive network changes across controls, premanifest Huntington’s disease and manifest Huntington’s disease characterized by increased network segregation in the premanifest stage and loss of network integration in manifest disease. These regional and whole brain network differences were highly correlated with cognitive and motor deficits suggesting they have pathophysiological relevance. We also observed greater reductions in the connectivity of brain regions that have higher network traffic and lower clustering of neighbouring regions. This provides a potential mechanism that results in a characteristic pattern of structural connectivity loss targeting highly connected brain regions with high network traffic and low clustering of neighbouring regions. Our findings highlight the role of the rich club as a substrate for the structural connectivity loss seen in Huntington’s disease and have broader implications for understanding the connection between molecular and systems level pathology in neurodegenerative disease. PMID:26384928

Selective vulnerability of Rich Club brain regions is an organizational principle of structural connectivity loss in Huntington's disease.

PubMed

McColgan, Peter; Seunarine, Kiran K; Razi, Adeel; Cole, James H; Gregory, Sarah; Durr, Alexandra; Roos, Raymund A C; Stout, Julie C; Landwehrmeyer, Bernhard; Scahill, Rachael I; Clark, Chris A; Rees, Geraint; Tabrizi, Sarah J

2015-11-01

Huntington's disease can be predicted many years before symptom onset, and thus makes an ideal model for studying the earliest mechanisms of neurodegeneration. Diffuse patterns of structural connectivity loss occur in the basal ganglia and cortex early in the disease. However, the organizational principles that underlie these changes are unclear. By understanding such principles we can gain insight into the link between the cellular pathology caused by mutant huntingtin and its downstream effect at the macroscopic level. The 'rich club' is a pattern of organization established in healthy human brains, where specific hub 'rich club' brain regions are more highly connected to each other than other brain regions. We hypothesized that selective loss of rich club connectivity might represent an organizing principle underlying the distributed pattern of structural connectivity loss seen in Huntington's disease. To test this hypothesis we performed diffusion tractography and graph theoretical analysis in a pseudo-longitudinal study of 50 premanifest and 38 manifest Huntington's disease participants compared with 47 healthy controls. Consistent with our hypothesis we found that structural connectivity loss selectively affected rich club brain regions in premanifest and manifest Huntington's disease participants compared with controls. We found progressive network changes across controls, premanifest Huntington's disease and manifest Huntington's disease characterized by increased network segregation in the premanifest stage and loss of network integration in manifest disease. These regional and whole brain network differences were highly correlated with cognitive and motor deficits suggesting they have pathophysiological relevance. We also observed greater reductions in the connectivity of brain regions that have higher network traffic and lower clustering of neighbouring regions. This provides a potential mechanism that results in a characteristic pattern of structural connectivity loss targeting highly connected brain regions with high network traffic and low clustering of neighbouring regions. Our findings highlight the role of the rich club as a substrate for the structural connectivity loss seen in Huntington's disease and have broader implications for understanding the connection between molecular and systems level pathology in neurodegenerative disease. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain.

First-principles study on the initial decomposition process of CH3NH3PbI3

NASA Astrophysics Data System (ADS)

Xue, Yuanbin; Shan, Yueyue; Xu, Hu

2017-09-01

Hybrid perovskites are promising materials for high-performance photovoltaics. Unfortunately, hybrid perovskites readily decompose in particular under humid conditions, and the mechanisms of this phenomenon have not yet been fully understood. In this work, we systematically studied the possible mechanisms and the structural properties during the initial decomposition process of MAPbI3 (MA = CH3NH3+) using first-principles calculations. The theoretical results show that it is energetically favorable for PbI2 to nucleate and crystalize from the MAPbI3 matrix ahead of other decomposition products. Additionally, the structural instability is an intrinsic property of MAPbI3, regardless of whether the system is exposed to humidity. We find that H2O could facilitate the desorption of gaseous components, acting as a catalyst to transfer the H+ ion. These results provide insight into the cause of the instability of MAPbI3 and may improve our understanding of the properties of hybrid perovskites.

High pressure phase transformation in uranium carbide: A first principle study

NASA Astrophysics Data System (ADS)

Sahoo, B. D.; Joshi, K. D.; Gupta, Satish C.

2013-02-01

First principles calculations have been carried out to analyze structural, elastic and dynamic stability, of UC under hydrostatic compression. The comparison of enthalpies of rocksalt type (B1) and body centered orthorhombic (bco) structures as a function of pressure suggests the B1 →bco transition at ˜ 23 GPa, in good agreement with experimental value of 27 GPa. From the lattice dynamic calculations we have determined the phonon dispersion relations for B1 phase at various compressions. It is found that TA phonon branch along Γ-X direction becomes imaginary around the transition pressure. Further, the phonon instability so caused is of long wavelength nature as it occurs near the Brillouin zone centre. This long wavelength phonon instability at the transition point indicates that the B1 →bco transition is driven by elastic failure (the vanishing of C44 modulus). Various physical quantities such as equilibrium volume, bulk modulus, pressure derivative of bulk modulus and elastic constants have been determined at zero pressure and compared with data available in literature.

A study on high NA and evanescent imaging with polarized illumination

NASA Astrophysics Data System (ADS)

Yang, Seung-Hune

Simulation techniques are developed for high NA polarized microscopy with Babinet's principle, partial coherence and vector diffraction for non-periodic geometries. A mathematical model for the Babinet approach is developed and interpreted. Simulation results of the Babinet's principle approach are compared with those of Rigorous Coupled Wave Theory (RCWT) for periodic structures to investigate the accuracy of this approach and its limitations. A microscope system using a special solid immersion lens (SIL) is introduced to image Blu-Ray (BD) optical disc samples without removing the protective cover layer. Aberration caused by the cover layer is minimized with a truncated SIL. Sub-surface imaging simulation is achieved by RCWT, partial coherence, vector diffraction and Babinet's Principle. Simulated results are compared with experimental images and atomic force microscopy (AFM) measurement. A technique for obtaining native and induced using a significant amount of evanescent energy is described for a solid immersion lens (SIL) microscope. Characteristics of native and induced polarization images for different object structures and materials are studied in detail. Experiments are conducted with a NA = 1.48 at lambda = 550nm microscope. Near-field images are simulated and analyzed with an RCWT approach. Contrast curve versus object spatial frequency calculations are compared with experimental measurements. Dependencies of contrast versus source polarization angles and air gap for native and induced polarization image profiles are evaluated. By using the relationship between induced polarization and topographical structure, an induced polarization image of an alternating phase shift mask (PSM) is converted into a topographical image, which shows very good agreement with AFM measurement. Images of other material structures include a dielectric grating, chrome-on-glass grating, silicon CPU structure, BD-R and BD-ROM.

[Examination of laser-treated tooth surfaces after exposure to acid].

PubMed

Beeking, P O; Herrmann, C; Zuhrt, R

1990-12-01

In principle it is possible to homogenize the enamel surface by melting structural elements with the continuous wave CO2 laser. An experimental caries model was used for testing the acid resistance of the laser exposed tooth surfaces. Laser-treatment and measured exposure to acid produced zones of homogeneous smelting with microcracks and disintegration symptoms. Underneath the melted region the heat leakage obviously causes photo-thermic++ effects determined by increased resistance to acid.

Effect of External Vibration on PZT Impedance Signature.

PubMed

Yang, Yaowen; Miao, Aiwei

2008-11-01

Piezoelectric ceramic Lead Zirconate Titanate (PZT) transducers, working on the principle of electromechanical impedance (EMI), are increasingly applied for structural health monitoring (SHM) in aerospace, civil and mechanical engineering. The PZT transducers are usually surface bonded to or embedded in a structure and subjected to actuation so as to interrogate the structure at the desired frequency range. The interrogation results in the electromechanical admittance (inverse of EMI) signatures which can be used to estimate the structural health or integrity according to the changes of the signatures. In the existing EMI method, the monitored structure is only excited by the PZT transducers for the interrogating of EMI signature, while the vibration of the structure caused by the external excitations other than the PZT actuation is not considered. However, many structures work under vibrations in practice. To monitor such structures, issues related to the effects of vibration on the EMI signature need to be addressed because these effects may lead to misinterpretation of the structural health. This paper develops an EMI model for beam structures, which takes into account the effect of beam vibration caused by the external excitations. An experimental study is carried out to verify the theoretical model. A lab size specimen with different external excitations is tested and the effect of vibration on EMI signature is discussed.

Quantum Common Causes and Quantum Causal Models

NASA Astrophysics Data System (ADS)

Allen, John-Mark A.; Barrett, Jonathan; Horsman, Dominic C.; Lee, Ciarán M.; Spekkens, Robert W.

2017-07-01

Reichenbach's principle asserts that if two observed variables are found to be correlated, then there should be a causal explanation of these correlations. Furthermore, if the explanation is in terms of a common cause, then the conditional probability distribution over the variables given the complete common cause should factorize. The principle is generalized by the formalism of causal models, in which the causal relationships among variables constrain the form of their joint probability distribution. In the quantum case, however, the observed correlations in Bell experiments cannot be explained in the manner Reichenbach's principle would seem to demand. Motivated by this, we introduce a quantum counterpart to the principle. We demonstrate that under the assumption that quantum dynamics is fundamentally unitary, if a quantum channel with input A and outputs B and C is compatible with A being a complete common cause of B and C , then it must factorize in a particular way. Finally, we show how to generalize our quantum version of Reichenbach's principle to a formalism for quantum causal models and provide examples of how the formalism works.

The Structuring Principle: Political Socialization and Belief Systems

ERIC Educational Resources Information Center

Searing, Donald D.; And Others

1973-01-01

Assesses the significance of data on childhood political learning to political theory by testing the structuring principle,'' considered one of the central assumptions of political socialization research. This principle asserts that basic orientations acquired during childhood structure the later learning of specific issue beliefs.'' The…

Health monitoring for subway station structure by fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Zhou, Yao; Wang, Yuan-Feng; Han, Bing; Zhou, Zhi

2008-03-01

Fiber Bragg grating (FBG) sensors hold a great deal of potential for structural monitoring because of their high sensitivity and exceptional stability for long-term monitoring. FBG sensors have been applied to sense a number of physical measurands including strain, temperature, pressure etc. These applications are based on the same principle, i.e. the measurement of Bragg wavelength shift caused by the measurands. The characters and principle of FBG sensors have been introduced in detail. The relative experiment is done. The results show that FBG sensors have high sensitivity and long-term stability. It is feasible to use the sensors to the structural health monitoring (SHM). Cement hydration produces heat, which may provoke important temperature rises in massive structures. Such a high temperature may be a factor for cracking during the cooling phase. Thus, it is important to be able to calculate and control the heat to be produced by a given concrete at the mixture-proportioning stage. Theory of heat of hydration is also introduced in this paper. FBG sensors have been applied successfully in health monitoring for Guomao subway station structure. Compared with results measured by vibrating wire sensors and computed by finite element method, the monitoring results show temperature and strains can be accurately measured by FBG sensors. It is convenient to study on heat of hydration of massive concrete and guide structural design.

RNA structures as mediators of neurological diseases and as drug targets

PubMed Central

Bernat, Viachaslau; Disney, Matthew D.

2015-01-01

RNAs adopt diverse folded structures that are essential for function and thus play critical roles in cellular biology. A striking example of this is the ribosome, a complex, three-dimensionally folded macromolecular machine that orchestrates protein synthesis. Advances in RNA biochemistry, structural and molecular biology, and bioinformatics have revealed other non-coding RNAs whose functions are dictated by their structure. It is not surprising that aberrantly folded RNA structures contribute to disease. In this review, we provide a brief introduction into RNA structural biology and then describe how RNA structures function in cells and cause or contribute to neurological disease. Finally, we highlight successful applications of rational design principles to provide chemical probes and lead compounds targeting structured RNAs. Based on several examples of well-characterized RNA-driven neurological disorders, we demonstrate how designed small molecules can facilitate study of RNA dysfunction, elucidating previously unknown roles for RNA in disease, and provide lead therapeutics. PMID:26139368

Chemical Principls Exemplified

ERIC Educational Resources Information Center

Plumb, Robert C.

1973-01-01

Two topics are discussed: (1) Stomach Upset Caused by Aspirin, illustrating principles of acid-base equilibrium and solubility; (2) Physical Chemistry of the Drinking Duck, illustrating principles of phase equilibria and thermodynamics. (DF)

From micro to nano contacts in biological attachment devices

PubMed Central

Arzt, Eduard; Gorb, Stanislav; Spolenak, Ralph

2003-01-01

Animals with widely varying body weight, such as flies, spiders, and geckos, can adhere to and move along vertical walls and even ceilings. This ability is caused by very efficient attachment mechanisms in which patterned surface structures interact with the profile of the substrate. An extensive microscopic study has shown a strong inverse scaling effect in these attachment devices. Whereas μm dimensions of the terminal elements of the setae are sufficient for flies and beetles, geckos must resort to sub-μm devices to ensure adhesion. This general trend is quantitatively explained by applying the principles of contact mechanics, according to which splitting up the contact into finer subcontacts increases adhesion. This principle is widely spread in design of natural adhesive systems and may also be transferred into practical applications. PMID:12960386

First Principles Study of Band Structure and Band Gap Engineering in Graphene for Device Applications

DTIC Science & Technology

2015-03-20

In the bandstructure of graphene which is dominated by Dirac description, valence and conduction bands cross the Fermi level at a single point (K...of energy bands and appearance of Dirac cones near the ‘K’ point and Fermi level the electrons behave like massless Dirac fermions. For applications...results. Introduction Graphene, the super carbon , is now accepted as wonder material with new physics and it has caused major

Lattice structures and electronic properties of MO/MoSe2 interface from first-principles calculations

NASA Astrophysics Data System (ADS)

Zhang, Yu; Tang, Fu-Ling; Xue, Hong-Tao; Lu, Wen-Jiang; Liu, Jiang-Fei; Huang, Min

2015-02-01

Using first-principles plane-wave calculations within density functional theory, we theoretically studied the atomic structure, bonding energy and electronic properties of the perfect Mo (110)/MoSe2 (100) interface with a lattice mismatch less than 4.2%. Compared with the perfect structure, the interface is somewhat relaxed, and its atomic positions and bond lengths change slightly. The calculated interface bonding energy is about -1.2 J/m2, indicating that this interface is very stable. The MoSe2 layer on the interface has some interface states near the Fermi level, the interface states are mainly caused by Mo 4d orbitals, while the Se atom almost have no contribution. On the interface, Mo-5s and Se-4p orbitals hybridize at about -6.5 to -5.0 eV, and Mo-4d and Se-4p orbitals hybridize at about -5.0 to -1.0 eV. These hybridizations greatly improve the bonding ability of Mo and Se atom in the interface. By Bader charge analysis, we find electron redistribution near the interface which promotes the bonding of the Mo and MoSe2 layer.

[Food additives and healthiness].

PubMed

Heinonen, Marina

2014-01-01

Additives are used for improving food structure or preventing its spoilage, for example. Many substances used as additives are also naturally present in food. The safety of additives is evaluated according to commonly agreed principles. If high concentrations of an additive cause adverse health effects for humans, a limit of acceptable daily intake (ADI) is set for it. An additive is a risk only when ADI is exceeded. The healthiness of food is measured on the basis of nutrient density and scientifically proven effects.

The Precautionary Principle and the Tolerability of Blood Transfusion Risks.

PubMed

Kramer, Koen; Zaaijer, Hans L; Verweij, Marcel F

2017-03-01

Tolerance for blood transfusion risks is very low, as evidenced by the implementation of expensive blood tests and the rejection of gay men as blood donors. Is this low risk tolerance supported by the precautionary principle, as defenders of such policies claim? We discuss three constraints on applying (any version of) the precautionary principle and show that respecting these implies tolerating certain risks. Consistency means that the precautionary principle cannot prescribe precautions that it must simultaneously forbid taking, considering the harms they might cause. Avoiding counterproductivity requires rejecting precautions that cause more harm than they prevent. Proportionality forbids taking precautions that are more harmful than adequate alternatives. When applying these constraints, we argue, attention should not be restricted to harms that are human caused or that affect human health or the environment. Tolerating transfusion risks can be justified if available precautions have serious side effects, such as high social or economic costs.

Piezospectroscopy and first-principles calculations of the nitrogen-vacancy center in gallium arsenide

NASA Astrophysics Data System (ADS)

Kovac, Nicola; Künneth, Christopher; Alt, Hans Christian

2018-04-01

The nitrogen-vacancy (NV) center occurs in GaAs bulk crystals doped or implanted with nitrogen. The local vibration of nitrogen gives rise to a sharp infrared absorption band at 638 cm-1, exhibiting a fine structure due to the different masses of neighboring 69Ga and 71Ga host isotopes. Piezospectroscopic investigations in the crystallographic ⟨ 100 ⟩ direction prove that the center has C3v point symmetry, which is weakly perturbed by the isotope effect. The stress-induced shifts of some band components show an unusual non-linear behavior that can be explained by coupling between the isotope and the stress splitting. First-principles density-functional theory calculations are in full accordance with the experiments and confirm the C3v symmetry, caused by relaxation of the nitrogen atom from the anion lattice site towards the nearest-neighbor Ga plane. Furthermore, the calculations indicate the -3 charge state of the center as the most stable one for nearly all Fermi level positions. The NV center in GaAs is structurally analogous to the same center in diamond.

The Baby Care Questionnaire: A measure of parenting principles and practices during infancy☆

PubMed Central

Winstanley, Alice; Gattis, Merideth

2013-01-01

The current report provides a new framework to explore the role of parenting practices and principles during infancy. We identify structure and attunement as key parenting principles during infancy. Structure represents reliance on regularity and routines in daily life. Attunement represents reliance on infant cues and close physical contact. We suggest parents’ relative endorsement of these parenting principles is related to their choices about practices such as feeding, holding and night-time sleeping. We designed the Baby Care Questionnaire to measure parents’ endorsement of structure and attunement, as well as their daily parenting practices. We report data demonstrating the factor structure, reliability and validity of the BCQ. The BCQ, to our knowledge, is the first comprehensive measure of parenting practices and principles during infancy. We conclude with a discussion of future directions for the measure. PMID:24050932

Principle of relative positioning of structures in the human body☆

PubMed Central

Meng, Buliang; Pang, Ailan; Li, Ming

2013-01-01

The arrangement of various biological structures should generally ensure the safety of crucial structures and increase their working efficiency; however, other principles governing the relative positions of structures in humans have not been reported. The present study therefore investigated other principles using nerves and their companion vessels in the human body as an example. Nerves and blood vessels usually travel together and in the most direct way towards their targets. Human embryology, histology, and gross anatomy suggest that there are many possible positions for these structures during development. However, for mechanical reasons, tougher or stronger structures should take priority. Nerves are tougher than most other structures, followed by arteries, veins, and lymphatic vessels. Nerves should therefore follow the most direct route, and be followed by the arteries, veins, and lymphatic vessels. This general principle should be applicable to all living things. PMID:25206733

RNA Structures as Mediators of Neurological Diseases and as Drug Targets.

PubMed

Bernat, Viachaslau; Disney, Matthew D

2015-07-01

RNAs adopt diverse folded structures that are essential for function and thus play critical roles in cellular biology. A striking example of this is the ribosome, a complex, three-dimensionally folded macromolecular machine that orchestrates protein synthesis. Advances in RNA biochemistry, structural and molecular biology, and bioinformatics have revealed other non-coding RNAs whose functions are dictated by their structure. It is not surprising that aberrantly folded RNA structures contribute to disease. In this Review, we provide a brief introduction into RNA structural biology and then describe how RNA structures function in cells and cause or contribute to neurological disease. Finally, we highlight successful applications of rational design principles to provide chemical probes and lead compounds targeting structured RNAs. Based on several examples of well-characterized RNA-driven neurological disorders, we demonstrate how designed small molecules can facilitate the study of RNA dysfunction, elucidating previously unknown roles for RNA in disease, and provide lead therapeutics. Copyright © 2015 Elsevier Inc. All rights reserved.

The Texas horned lizard as model for robust capillary structures for passive directional transport of cooling lubricants

NASA Astrophysics Data System (ADS)

Comanns, Philipp; Winands, Kai; Pothen, Mario; Bott, Raya A.; Wagner, Hermann; Baumgartner, Werner

2016-04-01

Moisture-harvesting lizards, such as the Texas horned lizard Phrynosoma cornutum, have remarkable adaptations for inhabiting arid regions. Special skin structures, in particular capillary channels in between imbricate overlapping scales, enable the lizard to collect water by capillarity and to transport it to the snout for ingestion. This fluid transport is passive and directional towards the lizard's snout. The directionality is based on geometric principles, namely on a periodic pattern of interconnected half-open capillary channels that narrow and widen. Following a biomimetic approach, these principles were transferred to technical prototype design and manufacturing. Capillary structures, 50 μm to 300 μm wide and approx. 70 μm deep, were realized by use of a pulsed picosecond laser in hot working tool steel, hardened to 52 HRC. In order to achieve highest functionality, strategies were developed to minimize potential structural inaccuracies, which can occur at the bottom of the capillary structures caused by the laser process. Such inaccuracies are in the range of 10 μm to 15 μm and form sub-capillary structures with greater capillary forces than the main channels. Hence, an Acceleration Compensation Algorithm was developed for the laser process to minimize or even avoid these inaccuracies. The capillary design was also identified to have substantial influence; by a hexagonal capillary network of non-parallel capillaries potential influences of sub-capillaries on the functionality were reduced to realize a robust passive directional capillary transport. Such smart surface structures can lead to improvements of technical systems by decreasing energy consumption and increasing the resource efficiency.

Tunable electronic structures of germanium monochalcogenide nanosheets via light non-metallic atom functionalization: a first-principles study.

PubMed

Ding, Yi; Wang, Yanli

2016-08-17

Germanium monochalcogenides, i.e. GeS and GeSe sheets, are isoelectronic analogues of phosphorene, which have been synthesized in recent experiments (P. Ramasamy et al., J. Mater. Chem. C, 2016, 4, 479). Utilizing first-principles calculations, we have investigated their tunable electronic and magnetic properties via light non-metallic atom (B, C, N, O, Si, P, S) functionalization. We find that on these GeS and GeSe sheets O and S adatoms prefer to locate at the top site above the Ge atom, while the other ones like to occupy the anion site, which push the original S/Se atom to the hollow site instead. O and S adatoms slightly affect the semiconducting behaviour of the doped systems, while B, C, N, Si, P ones will drastically modify their band structures and induce versatile spintronic properties. Through the supercell calculations, B and C adatoms are found to induce a bipolar semiconducting behaviour in the decorated systems, while the N/P adatom will cause a spin-gapless-semiconducting/nearly-half-metallic feature in them. The B/C/N/Si/P-substituted GeS/GeSe sheet can be formed by removing the hollow-site S/Se atom from the adatom-decorated structures, which exhibit an opposite semiconducting/metallic behaviour to their phosphorene counterparts. A general odd-even rule is proposed for this phenomenon, which shows that an odd (even) number of valence electron difference between the substitution and host atoms would cause a metallic (semiconducting) feature in the substituted systems. Our study demonstrates that atom functionalization is an efficient way to tailor the properties of GeS and GeSe nanosheets, which have adaptable electronic properties for potential applications in nanoelectronics and spintronics.

Understanding Lithium Solvation and Diffusion through Topological Analysis of First-Principles Molecular Dynamics

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

Bhatia, Harsh; Gyulassy, Attila; Ong, Mitchell

2016-09-27

The performance of lithium-ion batteries is strongly influenced by the ionic conductivity of the electrolyte, which depends on the speed at which Li ions migrate across the cell and relates to their solvation structure. The choice of solvent can greatly impact, both, the solvation and diffusivity of Li ions. In this work, we present our application of the topological techniques to extract and predict such behavior in the data generated by the first-principles molecular dynamics simulation of Li ions in an important organic solvent -ethylene carbonate. More specifically, we use the scalar topology of the electron charge density field tomore » analyze the evolution of the solvation structures. This allows us to derive a parameter-free bond definition for lithium-oxygen bonds, to provide a quantitative measure for bond strength, and to understand the regions of influence of each atom in the simulation. This has provided new insights into how and under what conditions certain bonds may form and break. As a result, we can identify and, more importantly, predict, unstable configurations in solvation structures. This can be very useful in understanding when small changes to the atoms' movements can cause significantly different bond structures to evolve. Ultimately, this promises to allow scientists to explore lithium ion solvation and diffusion more systematically, with the aim of new insights and potentially accelerating the calculations themselves.« less

Management of chronic low back pain: rationales, principles, and targets of imaging-guided spinal injections.

PubMed

Fritz, Jan; Niemeyer, Thomas; Clasen, Stephan; Wiskirchen, Jakub; Tepe, Gunnar; Kastler, Bruno; Nägele, Thomas; König, Claudius W; Claussen, Claus D; Pereira, Philippe L

2007-01-01

If low back pain does not improve with conservative management, the cause of the pain must be determined before further therapy is initiated. Information obtained from the patient's medical history, physical examination, and imaging may suffice to rule out many common causes of chronic pain (eg, fracture, malignancy, visceral or metabolic abnormality, deformity, inflammation, and infection). However, in most cases, the initial clinical and imaging findings have a low predictive value for the identification of specific pain-producing spinal structures. Diagnostic spinal injections performed in conjunction with imaging may be necessary to test the hypothesis that a particular structure is the source of pain. To ensure a valid test result, diagnostic injection procedures should be monitored with fluoroscopy, computed tomography, or magnetic resonance imaging. The use of controlled and comparative injections helps maximize the reliability of the test results. After a symptomatic structure has been identified, therapeutic spinal injections may be administered as an adjunct to conservative management, especially in patients with inoperable conditions. Therapeutic injections also may help hasten the recovery of patients with persistent or recurrent pain after spinal surgery. RSNA, 2007

The electronic structure, elastic and optical properties of Cu2ZnGe(SexS1 - x)4 alloys: density functional calculations

NASA Astrophysics Data System (ADS)

Shen, Kesheng; Jia, Guangrui; Zhang, Xianzhou; Jiao, Zhaoyong

2016-10-01

The electronic structure, elastic and optical properties of Cu2ZnGe(SexS1 - x)4 alloys are systematically analysed using first-principles calculations. The lattice parameters agree well with the theoretical and experimental values which are searched as complete as possible indicating our calculations are reliable. The elastic properties are investigated first and are compared with the similar compounds CZTS and CZTSe due to the unavailable experimental data currently. The variation of the optical properties caused by the increase of Se/S ratio is discussed. The static optical constants are calculated and the corrected values are also predicted according to the available experimental data.

Band structures of TiO2 doped with N, C and B*

PubMed Central

Xu, Tian-Hua; Song, Chen-Lu; Liu, Yong; Han, Gao-Rong

2006-01-01

This study on the band structures and charge densities of nitrogen (N)-, carbon (C)- and boron (B)-doped titanium dioxide (TiO2) by first-principles simulation with the CASTEP code (Segall et al., 2002) showed that the three 2p bands of impurity atom are located above the valence-band maximum and below the Ti 3d bands, and that along with the decreasing of impurity atomic number, the fluctuations become more intensive. We cannot observe obvious band-gap narrowing in our result. Therefore, the cause of absorption in visible light might be the isolated impurity atom 2p states in band-gap rather than the band-gap narrowing. PMID:16532532

Preschool Children Learn about Causal Structure from Conditional Interventions

ERIC Educational Resources Information Center

Schulz, Laura E.; Gopnik, Alison; Glymour, Clark

2007-01-01

The conditional intervention principle is a formal principle that relates patterns of interventions and outcomes to causal structure. It is a central assumption of experimental design and the causal Bayes net formalism. Two studies suggest that preschoolers can use the conditional intervention principle to distinguish causal chains, common cause…

Organizing to Manage Base-Level Service Contracts in the 1990s.

DTIC Science & Technology

1986-04-01

management of service contracts is the present day organizational structure. The structure is flawed and violates basic principles of management . Until the...are classic principles of management . To state the principle I will quote Ernest Dale: "Authority should be commensurate with responsibility. That is

Psychosomatic medicine and cybernetics.

PubMed

Ishikawa, H

1979-01-01

In our daily psychosomatic medicine clinics, we have adopted four principles from Wiener's cybernetics and von Bertalanffy's general system theory. We use the polygraphic method for the diagnosis of psychosomatic disease (black box principle). For the control of psychosomatic symptoms, we use the biofeedback method (feedback principle). We use systematic desensitization to relieve social stresses which cause psychosomatic disease (open and closed system principle). And lastly, transactional analysis, which corresponds to the information and energy principle.

Noncommutative Common Cause Principles in algebraic quantum field theory

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

Hofer-Szabo, Gabor; Vecsernyes, Peter

2013-04-15

States in algebraic quantum field theory 'typically' establish correlation between spacelike separated events. Reichenbach's Common Cause Principle, generalized to the quantum field theoretical setting, offers an apt tool to causally account for these superluminal correlations. In the paper we motivate first why commutativity between the common cause and the correlating events should be abandoned in the definition of the common cause. Then we show that the Noncommutative Weak Common Cause Principle holds in algebraic quantum field theory with locally finite degrees of freedom. Namely, for any pair of projections A, B supported in spacelike separated regions V{sub A} and V{submore » B}, respectively, there is a local projection C not necessarily commuting with A and B such that C is supported within the union of the backward light cones of V{sub A} and V{sub B} and the set {l_brace}C, C{sup Up-Tack }{r_brace} screens off the correlation between A and B.« less

75 FR 40845 - Preventing Deaths and Injuries of Fire Fighters Using Risk Management Principles at Structure Fires

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-14

... NIOSH 141-A] Preventing Deaths and Injuries of Fire Fighters Using Risk Management Principles at Structure Fires AGENCY: National Institute for Occupational Safety and Health (NIOSH) of the Centers for... publication entitled ``Preventing Deaths and Injuries of Fire Fighters Using Risk Management Principles at...

A neighbor pixel communication filtering structure for Dynamic Vision Sensors

NASA Astrophysics Data System (ADS)

Xu, Yuan; Liu, Shiqi; Lu, Hehui; Zhang, Zilong

2017-02-01

For Dynamic Vision Sensors (DVS), thermal noise and junction leakage current induced Background Activity (BA) is the major cause of the deterioration of images quality. Inspired by the smoothing filtering principle of horizontal cells in vertebrate retina, A DVS pixel with Neighbor Pixel Communication (NPC) filtering structure is proposed to solve this issue. The NPC structure is designed to judge the validity of pixel's activity through the communication between its 4 adjacent pixels. The pixel's outputs will be suppressed if its activities are determined not real. The proposed pixel's area is 23.76×24.71μm2 and only 3ns output latency is introduced. In order to validate the effectiveness of the structure, a 5×5 pixel array has been implemented in SMIC 0.13μm CIS process. 3 test cases of array's behavioral model show that the NPC-DVS have an ability of filtering the BA.

A new blackhole theorem and its applications to cosmology and astrophysics

NASA Astrophysics Data System (ADS)

Wang, Shouhong; Ma, Tian

2015-04-01

We shall present a blackhole theorem and a theorem on the structure of our Universe, proved in a recently published paper, based on 1) the Einstein general theory of relativity, and 2) the cosmological principle that the universe is homogeneous and isotropic. These two theorems are rigorously proved using astrophysical dynamical models coupling fluid dynamics and general relativity based on a symmetry-breaking principle. With the new blackhole theorem, we further demonstrate that both supernovae explosion and AGN jets, as well as many astronomical phenomena including e.g. the recent reported are due to combined relativistic, magnetic and thermal effects. The radial temperature gradient causes vertical Benard type convection cells, and the relativistic viscous force (via electromagnetic, the weak and the strong interactions) gives rise to a huge explosive radial force near the Schwarzschild radius, leading e.g. to supernovae explosion and AGN jets.

Phase Stability and Superconductivity of Compressed Argon-Hydrogen Compounds from First-Principles

NASA Astrophysics Data System (ADS)

Ishikawa, Takahiro; Nakanishi, Akitaka; Shimizu, Katsuya; Oda, Tatsuki

2017-12-01

We present the phase stability and superconductivity of Ar-H compounds under high pressure predicted by first-principles calculations and a genetic algorithm technique for crystal structure search. We found that insulating ArH4, earlier predicted to be metalized at 350 GPa, survives up to 700 GPa owing to the transition into a new phase Pnma at around 250 GPa and then decomposes into metallic ArH2 and pure solid hydrogen. At around 1500 GPa, the bonding form of ArH2 is changed by the dissociation of H2 molecules at the interstitial site of the argon lattice, and antibonding orbitals are partially filled, which causes an increase in the density of states at the Fermi level. Results showed that electron-phonon coupling is enhanced and the superconducting critical temperature is increased from 0.2 to 67 K.

Forensic engineering: applying materials and mechanics principles to the investigation of product failures.

PubMed

Hainsworth, S V; Fitzpatrick, M E

2007-06-01

Forensic engineering is the application of engineering principles or techniques to the investigation of materials, products, structures or components that fail or do not perform as intended. In particular, forensic engineering can involve providing solutions to forensic problems by the application of engineering science. A criminal aspect may be involved in the investigation but often the problems are related to negligence, breach of contract, or providing information needed in the redesign of a product to eliminate future failures. Forensic engineering may include the investigation of the physical causes of accidents or other sources of claims and litigation (for example, patent disputes). It involves the preparation of technical engineering reports, and may require giving testimony and providing advice to assist in the resolution of disputes affecting life or property.This paper reviews the principal methods available for the analysis of failed components and then gives examples of different component failure modes through selected case studies.

Ignorance is a bliss: Mathematical structure of many-box models

NASA Astrophysics Data System (ADS)

Tylec, Tomasz I.; Kuś, Marek

2018-03-01

We show that the propositional system of a many-box model is always a set-representable effect algebra. In particular cases of 2-box and 1-box models, it is an orthomodular poset and an orthomodular lattice, respectively. We discuss the relation of the obtained results with the so-called Local Orthogonality principle. We argue that non-classical properties of box models are the result of a dual enrichment of the set of states caused by the impoverishment of the set of propositions. On the other hand, quantum mechanical models always have more propositions as well as more states than the classical ones. Consequently, we show that the box models cannot be considered as generalizations of quantum mechanical models and seeking additional principles that could allow us to "recover quantum correlations" in box models are, at least from the fundamental point of view, pointless.

Sea loads on ships and offshore structures

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

Faltinsen, O.

1990-01-01

The book introduces the theory of the structural loading on ships and offshore structures caused by wind, waves and currents, and goes on to describe the applications of this theory in terms of real structures. The main topics described are linear-wave induced motions, loads on floating structures, numerical methods for ascertaining wave induced motions and loads, viscous wave loads and damping, stationkeeping and water impact and entry. The applications of the theoretical principles are introduced with extensive use of exercises and examples. Applications covered include conventional ships, barges, high speed marine vehicles, semisubmersibles, tension leg platforms, moored or dynamic positionedmore » ships, risers, buoys, fishing nets, jacket structures and gravity platforms. One aim of the book is to provide a physical understanding through simplified mathematical models. In this way one can develop analytical tools to evaluate results from test models, full scale trials or computer simulation, and learns which parameters represent the major contributions and influences on sea loads.« less

Fuel-Mediated Transient Clustering of Colloidal Building Blocks.

PubMed

van Ravensteijn, Bas G P; Hendriksen, Wouter E; Eelkema, Rienk; van Esch, Jan H; Kegel, Willem K

2017-07-26

Fuel-driven assembly operates under the continuous influx of energy and results in superstructures that exist out of equilibrium. Such dissipative processes provide a route toward structures and transient behavior unreachable by conventional equilibrium self-assembly. Although perfected in biological systems like microtubules, this class of assembly is only sparsely used in synthetic or colloidal analogues. Here, we present a novel colloidal system that shows transient clustering driven by a chemical fuel. Addition of fuel causes an increase in hydrophobicity of the building blocks by actively removing surface charges, thereby driving their aggregation. Depletion of fuel causes reappearance of the charged moieties and leads to disassembly of the formed clusters. This reassures that the system returns to its initial, equilibrium state. By taking advantage of the cyclic nature of our system, we show that clustering can be induced several times by simple injection of new fuel. The fuel-mediated assembly of colloidal building blocks presented here opens new avenues to the complex landscape of nonequilibrium colloidal structures, guided by biological design principles.

Humanization of work circumstances in dialog communication using data display devices, volume 1

NASA Astrophysics Data System (ADS)

Graunke, H.; Julich, H.; Petersen, H. C.; Schaefer, H.; Strupp, K.

1982-11-01

The effects of data display on working places was investigated. Data processing by data display devices is not considered. Important criteria for job contentment is the integration into complex job structures. Corresponding to this principle of organization is team work with a flexible way of labor division which provides the chance and the motivation for a cooperative self controlled working process which give strain caused by data display devices. It is found that in public administration a team with an institutional leadership with primarily social integrative functions is appreciated most.

[Measuring microhardness of laser exposed tooth surface].

PubMed

Florin, R; Herrmann, C; Bernhardt, W

1990-02-01

In principle it is possible to homogenize the enamel surface by melting structural elements with the continuous wave CO2 laser. Using the precision instrument NEOPHOT 2 (Carl Zeiss JENA) the microhardness of extracted laserexposed premolares were tested so as to clarify the functional strain capasity and the mechanical characteristics of laserexposed regions of enamel surfaces. The proven higher hardness in the centre of the laserinduced fusing zones (in comparison with adjacent enamel) objectify an attainable refining of the enamel surface that probably causes an increase in the caries-preventive resistance.

Itch Management: General Principles.

PubMed

Misery, Laurent

2016-01-01

Like pain, itch is a challenging condition that needs to be managed. Within this setting, the first principle of itch management is to get an appropriate diagnosis to perform an etiology-oriented therapy. In several cases it is not possible to treat the cause, the etiology is undetermined, there are several causes, or the etiological treatment is not effective enough to alleviate itch completely. This is also why there is need for symptomatic treatment. In all patients, psychological support and associated pragmatic measures might be helpful. General principles and guidelines are required, yet patient-centered individual care remains fundamental. © 2016 S. Karger AG, Basel.

Silicon-carbon bond inversions driven by 60-keV electrons in graphene.

PubMed

Susi, Toma; Kotakoski, Jani; Kepaptsoglou, Demie; Mangler, Clemens; Lovejoy, Tracy C; Krivanek, Ondrej L; Zan, Recep; Bangert, Ursel; Ayala, Paola; Meyer, Jannik C; Ramasse, Quentin

2014-09-12

We demonstrate that 60-keV electron irradiation drives the diffusion of threefold-coordinated Si dopants in graphene by one lattice site at a time. First principles simulations reveal that each step is caused by an electron impact on a C atom next to the dopant. Although the atomic motion happens below our experimental time resolution, stochastic analysis of 38 such lattice jumps reveals a probability for their occurrence in a good agreement with the simulations. Conversions from three- to fourfold coordinated dopant structures and the subsequent reverse process are significantly less likely than the direct bond inversion. Our results thus provide a model of nondestructive and atomically precise structural modification and detection for two-dimensional materials.

16 CFR 260.3 - Structure of the guides.

Code of Federal Regulations, 2010 CFR

2010-01-01

... ENVIRONMENTAL MARKETING CLAIMS § 260.3 Structure of the guides. The guides are composed of general principles and specific guidance on the use of environmental claims. These general principles and specific...

Enhancement of electron correlation due to the molecular dimerization in organic superconductors β -(BDA-TTP )2X (X =I3, SbF6)

NASA Astrophysics Data System (ADS)

Aizawa, Hirohito; Kuroki, Kazuhiko; Yamada, Jun-ichi

2015-10-01

We perform a first-principles band calculation for quasi-two-dimensional organic superconductors β -(BDA -TTP) 2I3 and β -(BDA -TTP) 2SbF6. The first-principles band structures between the I3 and SbF6 salts are apparently different. We construct a tight-binding model for each material which accurately reproduces the first-principles band structure. The obtained transfer energies give the differences as follows: (i) larger dimerization in the I3 salt than the SbF6 salt, and (ii) different signs and directions of the interstacking transfer energies. To decompose the origin of the difference into the dimerization and the interstacking transfer energies, we adopt a simplified model by eliminating the dimerization effect and focus only on the difference caused by the interstacking transfer energies. From the analysis using the simplified model, we find that the difference of the band structure comes mainly from the strength of the dimerization. To compare the strength of the electron correlation having roots in the band structure, we calculate the physical properties originating from the effect of the electron correlation such as the spin susceptibility applying the two-particle self-consistent method. We find that the maximum value of the spin susceptibility for the I3 salt is larger than that of the SbF6 salt. Hypothetically decreasing the dimerization within the model of the I3 salt, the spin susceptibility takes almost the same value as that of the SbF6 salt for the same magnitude of the dimerization. We expect that the different ground state between the I3 and SbF6 salt mainly comes from the strength of the dimerization which is apparently masked in the band calculation along a particular k path.

The structural, electronic and optical properties of Nd doped ZnO using first-principles calculations

NASA Astrophysics Data System (ADS)

Wen, Jun-Qing; Zhang, Jian-Min; Chen, Guo-Xiang; Wu, Hua; Yang, Xu

2018-04-01

The density functional theory calculations using general gradient approximation (GGA) applying Perdew-Burke-Ernzerhof (PBE) as correlation functional have been systematically performed to research the formation energy, the electronic structures, band structures, total and partial DOS, and optical properties of Nd doping ZnO with the content from 6.25% to 12.5%. The formation energies are negative for both models, which show that two structures are energetically stable. Nd doping ZnO crystal is found to be a direct band gap semiconductor and Fermi level shifts upward into conduction band, which show the properties of n-type semiconductor. Band structures are more compact after Nd doping ZnO, implying that Nd doping induces the strong interaction between different atoms. Nd doping ZnO crystal presents occupied states at near Fermi level, which mainly comes from the Nd 4f orbital. The calculated optical properties imply that Nd doping causes a red-shift of absorption peaks, and enhances the absorption of the visible light.

Long-term archiving and data access: modelling and standardization

NASA Technical Reports Server (NTRS)

Hoc, Claude; Levoir, Thierry; Nonon-Latapie, Michel

1996-01-01

This paper reports on the multiple difficulties inherent in the long-term archiving of digital data, and in particular on the different possible causes of definitive data loss. It defines the basic principles which must be respected when creating long-term archives. Such principles concern both the archival systems and the data. The archival systems should have two primary qualities: independence of architecture with respect to technological evolution, and generic-ness, i.e., the capability of ensuring identical service for heterogeneous data. These characteristics are implicit in the Reference Model for Archival Services, currently being designed within an ISO-CCSDS framework. A system prototype has been developed at the French Space Agency (CNES) in conformance with these principles, and its main characteristics will be discussed in this paper. Moreover, the data archived should be capable of abstract representation regardless of the technology used, and should, to the extent that it is possible, be organized, structured and described with the help of existing standards. The immediate advantage of standardization is illustrated by several concrete examples. Both the positive facets and the limitations of this approach are analyzed. The advantages of developing an object-oriented data model within this contxt are then examined.

Biomimetic cellular metals-using hierarchical structuring for energy absorption.

PubMed

Bührig-Polaczek, A; Fleck, C; Speck, T; Schüler, P; Fischer, S F; Caliaro, M; Thielen, M

2016-07-19

Fruit walls as well as nut and seed shells typically perform a multitude of functions. One of the biologically most important functions consists in the direct or indirect protection of the seeds from mechanical damage or other negative environmental influences. This qualifies such biological structures as role models for the development of new materials and components that protect commodities and/or persons from damage caused for example by impacts due to rough handling or crashes. We were able to show how the mechanical properties of metal foam based components can be improved by altering their structure on various hierarchical levels inspired by features and principles important for the impact and/or puncture resistance of the biological role models, rather than by tuning the properties of the bulk material. For this various investigation methods have been established which combine mechanical testing with different imaging methods, as well as with in situ and ex situ mechanical testing methods. Different structural hierarchies especially important for the mechanical deformation and failure behaviour of the biological role models, pomelo fruit (Citrus maxima) and Macadamia integrifolia, were identified. They were abstracted and transferred into corresponding structural principles and thus hierarchically structured bio-inspired metal foams have been designed. A production route for metal based bio-inspired structures by investment casting was successfully established. This allows the production of complex and reliable structures, by implementing and combining different hierarchical structural elements found in the biological concept generators, such as strut design and integration of fibres, as well as by minimising casting defects. To evaluate the structural effects, similar investigation methods and mechanical tests were applied to both the biological role models and the metallic foams. As a result an even deeper quantitative understanding of the form-structure-function relationship of the biological concept generators as well as the bio-inspired metal foams was achieved, on deeper hierarchical levels and overarching different levels.

Knowledge about the Brain for Parents, Students, and Teachers: The Keys to Removing the Invisible Roadblocks to Learning and High Self-Esteem for All Students.

ERIC Educational Resources Information Center

Beamish, Claude R.

This paper presents basic information about the brain and how learning takes place, considers causes of differing human temperaments as explained by principles of Jungian psychology, reports on research on the causes of low achievement, and suggests a method to correct many educational problems. Principles of developmental neurology and right/left…

Defects and impurities induced structural and electronic changes in pyrite CoS2: first principles studies.

PubMed

Li, Shengwen; Zhang, Yanning; Niu, Xiaobin

2018-05-03

Cobalt pyrite (CoS2) and related materials are attracting much attention due to their potential use in renewable energy applications. In this work, first-principles studies were performed to investigate the effects of various neutral defects and ion dopants on the structural, energetic, magnetic and electronic properties of the bulk CoS2. Our theoretical results show that the concentrations of single cobalt (VCo) and sulfur (VS) vacancies in CoS2 samples can be high under S-rich and S-poor conditions, respectively. Although the single vacancies induce defect states near the gap edge, they are still half-metallic. We find that the substitution of one S with the O atom does not obviously change the structural, magnetic and electronic features near the Fermi level of the system. Most transition metal impurities (MnCo, FeCo, and MoCo) and Group IV and V anion impurities (CS, SiS, NS, PS, and AsS) create impurity states that are deep and/or near the gap edge. However, NiCo and Group VII elements (FS, ClS, and BrS) cause very localized gap states close to the Fermi level in the minority spin channel, which may modify their electrochemical performances. Our extensive calculations provide instructive information for the design and optimization of CoS2-related energy materials.

Ethical principles in federal regulations: the case of children and research risks.

PubMed

Williams, P C

1996-04-01

Ethical principles play an important part not only in the promulgation of regulations but also in their application, i.e., enforcement and adjudication. while traditional ethical principles--promotion of welfare, freedom, and fairness--play an important role in both elements of regulation, some other kinds of ethical principles are significant as well. Principles governing the structure of decision processes should shape the structure and actions of agencies; principles of wise application should govern the work of those whose responsibility it is to apply regulatory language to particular situations. These points are demonstrated by investigating a case study: federal regulations designed to protect children involved in scientific research applied to a placebo study of the effects of recombinant human growth hormone on children of extremely short stature.

The organizational structure and governing principles of the Food and Drug Administration's Mini-Sentinel pilot program.

PubMed

Forrow, Susan; Campion, Daniel M; Herrinton, Lisa J; Nair, Vinit P; Robb, Melissa A; Wilson, Marcus; Platt, Richard

2012-01-01

The US Food and Drug Administration's Mini-Sentinel pilot program is developing an organizational structure as well as principles and policies to govern its operations. These will inform the structure and function of the eventual Sentinel System. Mini-Sentinel is a collaboration that includes 25 participating institutions. We describe the program's current organizational structure and its major principles and policies. The organization includes a coordinating center with program leadership provided by a principal investigator; a planning board and subcommittees; an operations center; and data, methods, and protocol cores. Ad hoc workgroups are created as needed. A privacy panel advises about protection of individual health information. Principles and policies are intended to ensure that Mini-Sentinel conforms to the principles of fair information practices, protects the privacy of individual health information, maintains the security and integrity of data, assures the confidentiality of proprietary information, provides accurate and timely communications, prevents or manages conflicts of interest, and preserves respect for intellectual property rights. Copyright © 2012 John Wiley & Sons, Ltd.

Nanoscale-Barrier Formation Induced by Low-Dose Electron-Beam Exposure in Ultrathin MoS2 Transistors.

PubMed

Matsunaga, Masahiro; Higuchi, Ayaka; He, Guanchen; Yamada, Tetsushi; Krüger, Peter; Ochiai, Yuichi; Gong, Yongji; Vajtai, Robert; Ajayan, Pulickel M; Bird, Jonathan P; Aoki, Nobuyuki

2016-10-05

Utilizing an innovative combination of scanning-probe and spectroscopic techniques, supported by first-principles calculations, we demonstrate how electron-beam exposure of field-effect transistors, implemented from ultrathin molybdenum disulfide (MoS 2 ), may cause nanoscale structural modifications that in turn significantly modify the electrical operation of these devices. Quite surprisingly, these modifications are induced by even the relatively low electron doses used in conventional electron-beam lithography, which are found to induce compressive strain in the atomically thin MoS 2 . Likely arising from sulfur-vacancy formation in the exposed regions, the strain gives rise to a local widening of the MoS 2 bandgap, an idea that is supported both by our experiment and by the results of first-principles calculations. A nanoscale potential barrier develops at the boundary between exposed and unexposed regions and may cause extrinsic variations in the resulting electrical characteristics exhibited by the transistor. The widespread use of electron-beam lithography in nanofabrication implies that the presence of such strain must be carefully considered when seeking to harness the potential of atomically thin transistors. At the same time, this work also promises the possibility of exploiting the strain as a means to achieve "bandstructure engineering" in such devices.

[Precautionary principle. State of the situation in Argentina].

PubMed

Kemelmajer de Carlucci, Aída

2017-10-13

The new Argentine Civil and Commercial Code includes the prevention principle. The precautionary Principle is regulated by the Environmental Protection Act.A significant number of cases have reached the Supreme Court of the Nation. This Court, in general, estimates that the decisions concerning the precautionary principle have definitive nature, i.e., are not merely provisional. Usually, the situation is caused by the State itself, which fails to control. The different decisions show a Judiciary worried about protecting the environment.

Stability and superconducting properties of GaH5 at high pressure

NASA Astrophysics Data System (ADS)

Ning, Yan-Li; Yang, Wen-Hua; Zang, Qing-Jun; Lu, Wen-Cai

2017-11-01

Using genetic algorithm (GA) method combined with first-principles calculations, the structures, dynamical and thermodynamic stabilities of GaH5 were studied. The calculated results suggested that at the pressure range 150-400 GPa, the P21/m phase of GaH5 is the most favorable phase and dynamically stable, but thermodynamically it is unstable and can decompose into GaH3 and H2. The superconducting property of GaH5 was further calculated, and the predicted superconducting transformation temperature Tc of GaH5 P21/m phase is about 35.63 K at 250 GPa. Besides, we compared the GaH5 and GaH3 superconducting properties, and found that GaH3-Pm-3n structure has a larger DOS near Fermi level than GaH5-P21/m structure, which may be the main reason causing higher Tc of GaH3 than GaH5.

Strong excitonic interactions in the oxygen K-edge of perovskite oxides.

PubMed

Tomita, Kota; Miyata, Tomohiro; Olovsson, Weine; Mizoguchi, Teruyasu

2017-07-01

Excitonic interactions of the oxygen K-edge electron energy-loss near-edge structure (ELNES) of perovskite oxides, CaTiO 3 , SrTiO 3 , and BaTiO 3 , together with reference oxides, MgO, CaO, SrO, BaO, and TiO 2 , were investigated using a first-principles Bethe-Salpeter equation calculation. Although the transition energy of oxygen K-edge is high, strong excitonic interactions were present in the oxygen K-edge ELNES of the perovskite oxides, whereas the excitonic interactions were negligible in the oxygen K-edge ELNES of the reference compounds. Detailed investigation of the electronic structure suggests that the strong excitonic interaction in the oxygen K-edge ELNES of the perovskite oxides is caused by the directionally confined, low-dimensional electronic structure at the Ti-O-Ti bonds. Copyright © 2016 Elsevier B.V. All rights reserved.

First principles and experimental study of the electronic structure and phase stability of bulk thallium bromide

NASA Astrophysics Data System (ADS)

Smith, Holland M.; Zhou, Yuzhi; Ciampi, Guido; Kim, Hadong; Cirignano, Leonard J.; Shah, Kanai S.; Haller, E. E.; Chrzan, D. C.

2013-08-01

We apply state-of-art first principle calculations to study the polymorphism and electronic structure of three previously reported phases of TlBr. The calculated band structures of NaCl-structure phase and orthorhombic-structure phase have different features than that of commonly observed CsCl-structure phase. We further interpret photoluminescence spectra based on our calculations. Several peaks close to calculated band gap values of the NaCl-structure phase and the orthorhombic-structure phase are found in unpolished TlBr samples.

Strain measurement on stiff structures: experimental evaluation of three integrated measurement principles

NASA Astrophysics Data System (ADS)

Rausch, J.; Hatzfeld, C.; Karsten, R.; Kraus, R.; Millitzer, J.; Werthschützky, R.

2012-06-01

This paper presents an experimental evaluation of three different strain measuring principles. Mounted on a steel beam resembling a car engine mount, metal foil strain gauges, piezoresistive silicon strain gauges and piezoelectric patches are investigated to measure structure-borne forces to control an active mounting structure. FEA simulation determines strains to be measured in the range of 10-8 up to 10-5 m × m-1. These low strains cannot be measured with conventional metal foil strain gauges, as shown in the experiment conducted. Both piezoresistive and piezoelectric gauges show good results compared to a conventional piezoelectric force sensor. Depending on bandwidth, overload capacity and primary electronic costs, these principles seem to be worth considering in an adaptronic system design. These parameters are described in detail for the principles investigated.

Free-energy and the brain

PubMed Central

Friston, Karl J.; Stephan, Klaas E.

2009-01-01

If one formulates Helmholtz’s ideas about perception in terms of modern-day theories one arrives at a model of perceptual inference and learning that can explain a remarkable range of neurobiological facts. Using constructs from statistical physics it can be shown that the problems of inferring what cause our sensory input and learning causal regularities in the sensorium can be resolved using exactly the same principles. Furthermore, inference and learning can proceed in a biologically plausible fashion. The ensuing scheme rests on Empirical Bayes and hierarchical models of how sensory information is generated. The use of hierarchical models enables the brain to construct prior expectations in a dynamic and context-sensitive fashion. This scheme provides a principled way to understand many aspects of the brain’s organisation and responses. In this paper, we suggest that these perceptual processes are just one emergent property of systems that conform to a free-energy principle. The free-energy considered here represents a bound on the surprise inherent in any exchange with the environment, under expectations encoded by its state or configuration. A system can minimise free-energy by changing its configuration to change the way it samples the environment, or to change its expectations. These changes correspond to action and perception respectively and lead to an adaptive exchange with the environment that is characteristic of biological systems. This treatment implies that the system’s state and structure encode an implicit and probabilistic model of the environment. We will look at models entailed by the brain and how minimisation of free-energy can explain its dynamics and structure. PMID:19325932

Structural and electronic phase transitions of ThS 2 from first-principles calculations

DOE PAGES

Guo, Yongliang; Wang, Changying; Qiu, Wujie; ...

2016-10-07

Performed a systematic study using first-principles methods of the pressure-induced structural and electronic phase transitions in ThS 2, which may play an important role in the next generation nuclear energy fuel technology.

Will Global Warming Cause a Rise in Sea Level? A Simple Activity about the States of Water

ERIC Educational Resources Information Center

Oguz, Ayse

2009-01-01

In this activity, a possible problem related to global warming is clarified by the principle of states of water. The activity consists of an experiment that includes three scientific principles: Archimedes' Principle, the Law of Conservation of Matter, and the fluidity of liquids. The experiment helps students raise questions and open new horizons…

Ultrasound Guidance for Botulinum Neurotoxin Chemodenervation Procedures.

PubMed

Alter, Katharine E; Karp, Barbara I

2017-12-28

Injections of botulinum neurotoxins (BoNTs) are prescribed by clinicians for a variety of disorders that cause over-activity of muscles; glands; pain and other structures. Accurately targeting the structure for injection is one of the principle goals when performing BoNTs procedures. Traditionally; injections have been guided by anatomic landmarks; palpation; range of motion; electromyography or electrical stimulation. Ultrasound (US) based imaging based guidance overcomes some of the limitations of traditional techniques. US and/or US combined with traditional guidance techniques is utilized and or recommended by many expert clinicians; authors and in practice guidelines by professional academies. This article reviews the advantages and disadvantages of available guidance techniques including US as well as technical aspects of US guidance and a focused literature review related to US guidance for chemodenervation procedures including BoNTs injection.

Ab initio studies of ultrafast x-ray scattering of the photodissociation of iodine

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

Debnarova, Andrea; Techert, Simone; Schmatz, Stefan

2010-09-28

We computationally examine various aspects of the reaction dynamics of the photodissociation and recombination of molecular iodine. We use our recently proposed formalism to calculate time-dependent x-ray scattering signal changes from first principles. Different aspects of the dynamics of this prototypical reaction are studied, such as coherent and noncoherent processes, features of structural relaxation that are periodic in time versus nonperiodic dissociative processes, as well as small electron density changes caused by electronic excitation, all with respect to x-ray scattering. We can demonstrate that wide-angle x-ray scattering offers a possibility to study the changes in electron densities in nonperiodic systems,more » which render it a suitable technique for the investigation of chemical reactions from a structural dynamics point of view.« less

Flow structure in continuous flow electrophoresis chambers

NASA Technical Reports Server (NTRS)

Deiber, J. A.; Saville, D. A.

1982-01-01

There are at least two ways that hydrodynamic processes can limit continiuous flow electrophoresis. One arises from the sensitivity of the flow to small temerature gradients, especially at low flow rates and power levels. This sensitivity can be suppressed, at least in principle, by providing a carefully tailored, stabilizing temperature gradient in the cooling system that surrounds the flow channel. At higher power levels another limitation arises due to a restructuring of the main flow. This restructuring is caused by buoyancy, which is in turn affected by the electro-osmotic crossflow. Approximate solutions to appropriate partial differential equations have been computed by finite difference methods. One set of results is described here to illustrate the strong coupling between the structure of the main (axial) flow and the electro-osmotic flow.

Research status of wave energy conversion (WEC) device of raft structure

NASA Astrophysics Data System (ADS)

Dong, Jianguo; Gao, Jingwei; Tao, Liang; Zheng, Peng

2017-10-01

This paper has briefly described the concept of wave energy generation and six typical conversion devices. As for raft structure, detailed analysis is provided from its development process to typical devices. Taking the design process and working principle of Plamis as an example, the general principle of raft structure is briefly described. After that, a variety of raft structure models are introduced. Finally, the advantages and disadvantages, and development trend of raft structure are pointed out.

Temperature-driven topological quantum phase transitions in a phase-change material Ge2Sb2Te5.

PubMed

Eremeev, S V; Rusinov, I P; Echenique, P M; Chulkov, E V

2016-12-13

The Ge 2 Sb 2 Te 5 is a phase-change material widely used in optical memory devices and is a leading candidate for next generation non-volatile random access memory devices which are key elements of various electronics and portable systems. Despite the compound is under intense investigation its electronic structure is currently not fully understood. The present work sheds new light on the electronic structure of the Ge 2 Sb 2 Te 5 crystalline phases. We demonstrate by predicting from first-principles calculations that stable crystal structures of Ge 2 Sb 2 Te 5 possess different topological quantum phases: a topological insulator phase is realized in low-temperature structure and Weyl semimetal phase is a characteristic of the high-temperature structure. Since the structural phase transitions are caused by the temperature the switching between different topologically non-trivial phases can be driven by variation of the temperature. The obtained results reveal the rich physics of the Ge 2 Sb 2 Te 5 compound and open previously unexplored possibility for spintronics applications of this material, substantially expanding its application potential.

On the structure-bounded growth processes in plant populations.

PubMed

Kilian, H G; Kazda, M; Király, F; Kaufmann, D; Kemkemer, R; Bartkowiak, D

2010-07-01

If growing cells in plants are considered to be composed of increments (ICs) an extended version of the law of mass action can be formulated. It evidences that growth of plants runs optimal if the reaction-entropy term (entropy times the absolute temperature) matches the contact energy of ICs. Since these energies are small, thermal molecular movements facilitate via relaxation the removal of structure disturbances. Stem diameter distributions exhibit extra fluctuations likely to be caused by permanent constraints. Since the signal-response system enables in principle perfect optimization only within finite-sized cell ensembles, plants comprising relatively large cell numbers form a network of size-limited subsystems. The maximal number of these constituents depends both on genetic and environmental factors. Accounting for logistical structure-dynamics interrelations, equations can be formulated to describe the bimodal growth curves of very different plants. The reproduction of the S-bended growth curves verifies that the relaxation modes with a broad structure-controlled distribution freeze successively until finally growth is fully blocked thus bringing about "continuous solidification".

Interfaces between hexagonal and cubic oxides and their structure alternatives

DOE PAGES

Zhou, Hua; Wu, Lijun; Wang, Hui-Qiong; ...

2017-11-14

Multi-layer structure of functional materials often involves the integration of different crystalline phases. The film growth orientation thus frequently exhibits a transformation, owing to multiple possibilities caused by incompatible in-plane structural symmetry. Nevertheless, the detailed mechanism of the transformation has not yet been fully explored. Here we thoroughly probe the heteroepitaxially grown hexagonal zinc oxide (ZnO) films on cubic (001)-magnesium oxide (MgO) substrates using advanced scanning transition electron microscopy, X-ray diffraction and first principles calculations, revealing two distinct interface models of (001) ZnO/(001) MgO and (100) ZnO/(001) MgO. Here we have found that the structure alternatives are controlled thermodynamically bymore » the nucleation, while kinetically by the enhanced Zn adsorption and O diffusion upon the phase transformation. Finally, this work not only provides a guideline for the interface fabrication with distinct crystalline phases but also shows how polar and non-polar hexagonal ZnO films might be manipulated on the same cubic substrate.« less

[Mechanism of "crescent sign" formation in avascular necrosis of femoral head].

PubMed

Zhang, Nianfei; Qi, Shengwen; Chai, Jianfeng

2008-03-01

To investigate corresponding relation between structure change of the femoral head with "crescent sign" and stress exerted on the avascular necrosis of femoral head, to explore the mechanism of the "crescent sign" formation. From March 1998 to April 2003, the femoral heads of 18 hips in 16 cases having osteonecrosis and "crescent sign" in X-ray film before total hip arthroplasty, were collected. General and coronal section plane morphology of the femoral heads were observed. The principle of effective stress and stress concentration theory were used to explain the phenomena and structure changes in osteonecrosis of the femoral head. Cancellous bone existed as a three-dimensional, interconnected network of trabeculae rods and plates, with 50%-90% of porosity and 20-30 mmHg bone marrow pressure. According to the definition of porous media, bones especially cancellous bone was a kind of solid and liquid two phases porous media. Cross-sectional structure changes in the junction between subchondral plate and cancellous were the place where stress concentrated. The principle of effective stress and stress concentration theory could explain the phenomena and their relationship that occurred in avascular necrosis of the femoral head. The "crescent sign" starts in an area of very focal resorption in the subchondral plate laterally and peripherally. The focal resorption in the subchondral plate breaks the continuity of subchondral plate and causes stress concentration in the resorption region. The concentrated stress accumulates in the junction between subchondral plate and unrepaired necrotic cancellous bone brings on the fracture right below the subchondral plate. The focal resorption of the subchondral plate also provides a pathway for the pore water in the unrepaired necrotic bone skeleton to outflow, therefore cause effective stress increase and unrepaired necrotic bone skeleton be compacted by increased effective stress applied on unrepaired necrotic cancellous bone skeleton, and results in the volume decrease of unrepaired necrotic cancellous bone and the formation of cavum below the subchondral plate. The cavum shows "crescent sign" in the X-ray film.

Unusual phonon behavior and ultra-low thermal conductance of monolayer InSe.

PubMed

Zhou, Hangbo; Cai, Yongqing; Zhang, Gang; Zhang, Yong-Wei

2017-12-21

Monolayer indium selenide (InSe) possesses numerous fascinating properties, such as high electron mobility, quantum Hall effect and anomalous optical response. However, its phonon properties, thermal transport properties and the origin of its structural stability remain unexplored. Using first-principles calculations, we show that the atoms in InSe are highly polarized and such polarization causes strong long-range dipole-dipole interaction (DDI). For acoustic modes, DDI is essential for maintaining its structural stability. For optical modes, DDI causes a significant frequency shift of its out-of-phase vibrations. Surprisingly, we observed that there were two isolated frequency regimes, which were completely separated from other frequency regimes with large frequency gaps. Within each frequency regime, only a single phonon mode exists. We further reveal that InSe possesses the lowest thermal conductance among the known two-dimensional materials due to the low cut-off frequency, low phonon group velocities and the presence of large frequency gaps. These unique behaviors of monolayer InSe can enable the fabrication of novel devices, such as thermoelectric module, single-mode phonon channel and phononic laser.

Federalism and decentralization: impact on international and Brazilian health policies.

PubMed

Leite, Valéria Rodrigues; de Vasconcelos, Cipriano Maia; Lima, Kenio Costa

2011-01-01

This article discusses the implications of decentralization in the light of international and Brazilian federalism, and its effects on public health policy. In a comparative analysis among countries, the authors find there is no single model; rather, each country has a unique structure of institutions and norms that have important implications for the operation of its health system. Brazil shares some similarities with other countries that have adopted a decentralized system and is assuming features ever closer to U.S. federalism, with a complex web of relationships. The degree of inequality among Brazilian municipalities and states, along with the budgetary imbalances caused by the minimal levels of resource utilization, undermines Brazil's constitutional principles and, consequently, its federalism. To ensure the constitutional mandate in Brazil, it is essential, as in other countries, to create a stable source of funds and increase the volume and efficiency of spending. Also important are investing in the training of managers, improving information systems, strengthening the principles of autonomy and interdependence, and defining patterns of cooperation within the federation.

Unmanned Mine of the 21st Centuries

NASA Astrophysics Data System (ADS)

Semykina, Irina; Grigoryev, Aleksandr; Gargayev, Andrey; Zavyalov, Valeriy

2017-11-01

The article is analytical. It considers the construction principles of the automation system structure which realize the concept of «unmanned mine». All of these principles intend to deal with problems caused by a continuous complication of mining-and-geological conditions at coalmine such as the labor safety and health protection, the weak integration of different mining automation subsystems and the deficiency of optimal balance between a quantity of resource and energy consumed by mining machines and their throughput. The authors describe the main problems and neck stage of mining machines autonomation and automation subsystem. The article makes a general survey of the applied «unmanned technology» in the field of mining such as the remotely operated autonomous complexes, the underground positioning systems of mining machines using infrared radiation in mine workings etc. The concept of «unmanned mine» is considered with an example of the robotic road heading machine. In the final, the authors analyze the techniques and methods that could solve the task of underground mining without human labor.

Mixed variational formulations of finite element analysis of elastoacoustic/slosh fluid-structure interaction

NASA Technical Reports Server (NTRS)

Felippa, Carlos A.; Ohayon, Roger

1991-01-01

A general three-field variational principle is obtained for the motion of an acoustic fluid enclosed in a rigid or flexible container by the method of canonical decomposition applied to a modified form of the wave equation in the displacement potential. The general principle is specialized to a mixed two-field principle that contains the fluid displacement potential and pressure as independent fields. This principle contains a free parameter alpha. Semidiscrete finite-element equations of motion based on this principle are displayed and applied to the transient response and free-vibrations of the coupled fluid-structure problem. It is shown that a particular setting of alpha yields a rich set of formulations that can be customized to fit physical and computational requirements. The variational principle is then extended to handle slosh motions in a uniform gravity field, and used to derive semidiscrete equations of motion that account for such effects.

[Conceptual approach to formation of a modern system of medical provision].

PubMed

Belevitin, A B; Miroshnichenko, Iu V; Bunin, S A; Goriachev, A B; Krasavin, K D

2009-09-01

Within the frame of forming of a new face of medical service of the Armed Forces, were determined the principle approaches to optimization of the process of development of the system of medical supply. It was proposed to use the following principles: principle of hierarchic structuring, principle of purposeful orientation, principle of vertical task sharing, principle of horizontal task sharing, principle of complex simulation, principle of permanent perfection. The main direction of optimization of structure and composition of system of medical supply of the Armed Forces are: forming of modern institutes of medical supply--centers of support by technique and facilities on the base of central, regional storehouses, and attachment of several functions of organs of military government to them; creation of medical supply office on the base military hospitals, being basing treatment-prophylaxis institutes, in adjusted territorial zones of responsibility for the purpose of realization of complex of tasks of supplying the units and institutes, attached to them on medical support, by medical equipment. Building of medical support system is realized on three levels: Center - Military region (NAVY region) - territorial zone of responsibility.

Structural crashworthiness

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

Jones, N.; Wierzbicki, T.

1983-01-01

Behind the quest for safety in all forms of transport lies a complex technology of which structural crashworthiness forms an important part. This volume contains the work of over twenty experts whose interests range from the fundamental principles of structural collapse to the application of those principles to the design of ships, aircraft, road vehicles, and rail vehicles. The text focuses on the application of analytical and experimental techniques to predict energy dissipation characteristics of thin-walled structures and structural members under quasi-static and dynamic loadings.

Protein folding and misfolding: mechanism and principles

PubMed Central

Englander, S. Walter; Mayne, Leland; Krishna, Mallela M. G.

2012-01-01

Two fundamentally different views of how proteins fold are now being debated. Do proteins fold through multiple unpredictable routes directed only by the energetically downhill nature of the folding landscape or do they fold through specific intermediates in a defined pathway that systematically puts predetermined pieces of the target native protein into place? It has now become possible to determine the structure of protein folding intermediates, evaluate their equilibrium and kinetic parameters, and establish their pathway relationships. Results obtained for many proteins have serendipitously revealed a new dimension of protein structure. Cooperative structural units of the native protein, called foldons, unfold and refold repeatedly even under native conditions. Much evidence obtained by hydrogen exchange and other methods now indicates that cooperative foldon units and not individual amino acids account for the unit steps in protein folding pathways. The formation of foldons and their ordered pathway assembly systematically puts native-like foldon building blocks into place, guided by a sequential stabilization mechanism in which prior native-like structure templates the formation of incoming foldons with complementary structure. Thus the same propensities and interactions that specify the final native state, encoded in the amino-acid sequence of every protein, determine the pathway for getting there. Experimental observations that have been interpreted differently, in terms of multiple independent pathways, appear to be due to chance misfolding errors that cause different population fractions to block at different pathway points, populate different pathway intermediates, and fold at different rates. This paper summarizes the experimental basis for these three determining principles and their consequences. Cooperative native-like foldon units and the sequential stabilization process together generate predetermined stepwise pathways. Optional misfolding errors are responsible for 3-state and heterogeneous kinetic folding. PMID:18405419

Electronic Structure Principles and Aromaticity

ERIC Educational Resources Information Center

Chattaraj, P. K.; Sarkar, U.; Roy, D. R.

2007-01-01

The relationship between aromaticity and stability in molecules on the basis of quantities such as hardness and electrophilicity is explored. The findings reveal that aromatic molecules are less energetic, harder, less polarizable, and less electrophilic as compared to antiaromatic molecules, as expected from the electronic structure principles.

Magnetic-field enhancement beyond the skin-depth limit

NASA Astrophysics Data System (ADS)

Shin, Jonghwa; Park, Namkyoo; Fan, Shanhui; Lee, Yong-Hee

2010-02-01

Electric field enhancement has been actively studied recently and many metallic structures that are capable of locally enhancing electric field have been reported. The Babinet's principle can be utilized, especially in the form of Booker's extension, to transform the known electric field enhancing structures into magnetic field enhancing structures. The authors explain this transformation process and discuss the regime in which this principle breaks down. Unless the metals used can be well approximated with a PEC model, the principle's predictions fails to hold true. Authors confirm this aspect using numerical simulations based on realistic material parameters for actual metals. There is large discrepancy especially when the structural dimensions are comparable or less than the skin-depth at the wavelength of interest. An alternative way to achieve magnetic field enhancement is presented and the design of a connected bow-tie structure is proposed as an example. FDTD simulation results confirm the operation of the proposed structure.

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

Morris, J.R.; Lu, Z.; Ring, D.M.

We have examined a variety of structures for the {l_brace}510{r_brace} symmetric tilt boundary in Si and Ge, using tight-binding and first-principles calculations. These calculations show that the observed structure in Si is the lowest-energy structure, despite the fact that it is more complicated than what is necessary to preserve fourfold coordination. Contrary to calculations using a Tersoff potential, first-principles calculations show that the energy depends strongly upon the structure. A recently developed tight-binding model for Si produces results in very good agreement with the first-principles calculations. Electronic density of states calculations based upon this model show no evidence of midgapmore » states and little evidence of electronic states localized to the grain boundary. {copyright} {ital 1998} {ital The American Physical Society}« less

Cause-and-effect relationships in tandem swimmer models using transfer entropy

NASA Astrophysics Data System (ADS)

Peterson, Sean; Rosen, Maxwell; Gementzopoulos, Antonios; Zhang, Peng; Porfiri, Maurizio

2017-11-01

Swimming in a group affords a number of advantages to fish, including an enhanced ability to escape from predators, search for food, and mate. To study coordinated movements of fish, principled approaches are needed to unravel cause-and-effect relationships from raw-time series of multiple bodies moving in an encompassing fluid. In this work, we aim at demonstrating the validity of transfer entropy to elucidate cause-and-effect relationships in a fluid-structure interaction problem. Specifically, we consider two tandem airfoils in a uniform flow, wherein the pitching angle of one airfoil is actively controlled while the other is allowed to passively rotate. The active control alternates the pitch angle based upon an underlying two-state ergodic Markov process. We monitor the pitch angle of both the active and passive airfoils in time and demonstrate that transfer entropy can detect causality independent of which airfoil is actuated. The influence estimated by transfer entropy is found to be modulated by the distance between the two airfoils. The proposed data-driven technique offers a model-free perspective on fluid-structure interactions that can help illuminate the mechanisms of swimming in coordination. This work was supported by the National Science Foundation under Grant Numbers CBET-1332204 and CMMI-1433670.

New transmission planning methodology for requesting proposals for wind generation

NASA Astrophysics Data System (ADS)

Isaacs, Andrew L.

The increasing interest in renewable energy technologies during the last decade has caused conventional transmission and generation expansion planning methodologies to be strained and in some cases abandoned. This is due both to the quantity of generator interconnection requests and the constraints imposed by deregulated energy industry structures. One technique used to control the influx of renewable generation while maintaining competitive principles is a Request for Proposals (RFP). However, lack of transmission planning due to a disconnection between generation and transmission owners, difficulty in identifying viable projects, and high risk for proponents stand as obstacles to the goals of an RFP. This research proposes a procedure which minimizes the effect of these obstacles; meeting the purchaser requirements for low price and combining conventional planning concepts with feedback from competitive structures. The general features of the method include definition of generation limits and study area, expansion plan design, transmission cost evaluation, optimal selection of requested generation levels, and final selection of successful proponents. The method is shown to be effective in creating an RFP where proponents are well-informed and provided with cost certainty to reduce bid price, buyers are able to determine end costs of their energy, and good expansion planning principles are maintained. A case study using a real system in New Mexico demonstrates these concepts.

The Effects of Graphene Stacking on the Performance of Methane Sensor: A First-Principles Study on the Adsorption, Band Gap and Doping of Graphene

PubMed Central

Yang, Daoguo; Zhang, Guoqi; Chen, Liangbiao; Liu, Dongjing; Cai, Miao; Fan, Xuejun

2018-01-01

The effects of graphene stacking are investigated by comparing the results of methane adsorption energy, electronic performance, and the doping feasibility of five dopants (i.e., B, N, Al, Si, and P) via first-principles theory. Both zigzag and armchair graphenes are considered. It is found that the zigzag graphene with Bernal stacking has the largest adsorption energy on methane, while the armchair graphene with Order stacking is opposite. In addition, both the Order and Bernal stacked graphenes possess a positive linear relationship between adsorption energy and layer number. Furthermore, they always have larger adsorption energy in zigzag graphene. For electronic properties, the results show that the stacking effects on band gap are significant, but it does not cause big changes to band structure and density of states. In the comparison of distance, the average interlamellar spacing of the Order stacked graphene is the largest. Moreover, the adsorption effect is the result of the interactions between graphene and methane combined with the change of graphene’s structure. Lastly, the armchair graphene with Order stacking possesses the lowest formation energy in these five dopants. It could be the best choice for doping to improve the methane adsorption. PMID:29389860

The Effects of Graphene Stacking on the Performance of Methane Sensor: A First-Principles Study on the Adsorption, Band Gap and Doping of Graphene.

PubMed

Yang, Ning; Yang, Daoguo; Zhang, Guoqi; Chen, Liangbiao; Liu, Dongjing; Cai, Miao; Fan, Xuejun

2018-02-01

The effects of graphene stacking are investigated by comparing the results of methane adsorption energy, electronic performance, and the doping feasibility of five dopants (i.e., B, N, Al, Si, and P) via first-principles theory. Both zigzag and armchair graphenes are considered. It is found that the zigzag graphene with Bernal stacking has the largest adsorption energy on methane, while the armchair graphene with Order stacking is opposite. In addition, both the Order and Bernal stacked graphenes possess a positive linear relationship between adsorption energy and layer number. Furthermore, they always have larger adsorption energy in zigzag graphene. For electronic properties, the results show that the stacking effects on band gap are significant, but it does not cause big changes to band structure and density of states. In the comparison of distance, the average interlamellar spacing of the Order stacked graphene is the largest. Moreover, the adsorption effect is the result of the interactions between graphene and methane combined with the change of graphene's structure. Lastly, the armchair graphene with Order stacking possesses the lowest formation energy in these five dopants. It could be the best choice for doping to improve the methane adsorption.

First-principles study of low-spin LaCoO3 with structurally consistent Hubbard U

NASA Astrophysics Data System (ADS)

Hsu, H.; Umemoto, K.; Cococcioni, M.; Wentzcovitch, R.

2008-12-01

We use the local density approximation + Hubbard U (LDA+U) method to calculate the structural and electronic properties of low-spin LaCoO3. The Hubbard U is obtained by first principles and consistent with each fully-optimized atomic structure at different pressures. With structurally consistent U, the fully-optimized atomic structure agrees with experimental data better than the calculations with fixed or vanishing U. A discussion on how the Hubbard U affects the electronic and atomic structure of LaCoO3 is also given.

Protein structure similarity from Principle Component Correlation analysis.

PubMed

Zhou, Xiaobo; Chou, James; Wong, Stephen T C

2006-01-25

Owing to rapid expansion of protein structure databases in recent years, methods of structure comparison are becoming increasingly effective and important in revealing novel information on functional properties of proteins and their roles in the grand scheme of evolutionary biology. Currently, the structural similarity between two proteins is measured by the root-mean-square-deviation (RMSD) in their best-superimposed atomic coordinates. RMSD is the golden rule of measuring structural similarity when the structures are nearly identical; it, however, fails to detect the higher order topological similarities in proteins evolved into different shapes. We propose new algorithms for extracting geometrical invariants of proteins that can be effectively used to identify homologous protein structures or topologies in order to quantify both close and remote structural similarities. We measure structural similarity between proteins by correlating the principle components of their secondary structure interaction matrix. In our approach, the Principle Component Correlation (PCC) analysis, a symmetric interaction matrix for a protein structure is constructed with relationship parameters between secondary elements that can take the form of distance, orientation, or other relevant structural invariants. When using a distance-based construction in the presence or absence of encoded N to C terminal sense, there are strong correlations between the principle components of interaction matrices of structurally or topologically similar proteins. The PCC method is extensively tested for protein structures that belong to the same topological class but are significantly different by RMSD measure. The PCC analysis can also differentiate proteins having similar shapes but different topological arrangements. Additionally, we demonstrate that when using two independently defined interaction matrices, comparison of their maximum eigenvalues can be highly effective in clustering structurally or topologically similar proteins. We believe that the PCC analysis of interaction matrix is highly flexible in adopting various structural parameters for protein structure comparison.

Phase Separation and d Electronic Orbitals on Cyclic Degradation in Li-Mn-O Compounds: First-Principles Multiscale Modeling and Experimental Observations.

PubMed

Kim, Duho; Lim, Jin-Myoung; Park, Min-Sik; Cho, Kyeongjae; Cho, Maenghyo

2016-07-06

A combined study involving experiments and multiscale computational approaches is conducted to propose a theoretical solution for the suppression of the Jahn-Teller distortion which causes severe cyclic degradation. As-synthesized pristine and Al-doped Mn spinel compounds are the focus to understand the mechanism of the cyclic degradation in terms of the Jahn-Teller distortion, and the electrochemical performance of the Al-doped sample shows enhanced cyclic performance compared with that of the pristine one. Considering the electronic structures of the two systems using first-principles calculations, the pristine spinel suffers entirely from the Jahn-Teller distortion by Mn(3+), indicating an anisotropic electronic structure, but the Al-doped spinel exhibits an isotropic electronic structure, which means the suppressed Jahn-Teller distortion. A multiscale phase field model in nanodomain shows that the phase separation of the pristine spinel occurs to inactive Li0Mn2O4 (i.e., fully delithiated) gradually during cycles. In contrast, the Al-doped spinel does not show phase separation to an inactive phase. This explains why the Al-doped spinel maintains the capacity of the first charge during the subsequent cycles. On the basis of the mechanistic understanding of the origins and mechanism of the suppression of the Jahn-Teller distortion, fundamental insight for making tremendous cuts in the cyclic degradation could be provided for the Li-Mn-O compounds of Li-ion batteries.

The peculiarities of structurizing enclosing rock massif while developing a coal seam

NASA Astrophysics Data System (ADS)

Kozyreva, E. N.; Shinkevich, M. V.

2017-09-01

Different concepts of the development of geo-mechanical processes during longwall mining of a seam which are fundamentally different from the conventional ones are introduced in the article. Fundamental principles of the model for structurizing enclosing rock mass while longwall mining along the strike are described. The model was developed on the bases of non-linear geomechanical laws. According to the model, rock mass in the area of mining operation is organized as rock geomechanical layers with shifting arches. And the formation period of shifting arches in disintegrated rock mass is divisible by the length of the stope. Undulate characteristic of a massif as a peculiarity of man-made structurization of a massif is defined. It is shown that structuring the broken massif causes the formation of block-structured system and it can be detected while monitoring the ground pressure in powered support props. The results of the research allow decreasing the negative influence of a ground pressure and can be applied to specify parameters for controlling the roof, defining geometrical dimensions of a mining section and positioning of holing chute (face entry).

10 Tips to Reduce Your Chance of Losing Vision from the Most Common Cause of Blindness

MedlinePlus

... 2019 Basic and Clinical Science Course, Section 02: Fundamentals and Principles of Ophthalmology 2018-2019 Basic and ... 2019 Basic and Clinical Science Course, Section 02: Fundamentals and Principles of Ophthalmology Print 2018-2019 Basic ...

An Alternative to the Problematic Macro-Micro Structure of Introductory Economics.

ERIC Educational Resources Information Center

Tinari, Frank D.

The paper explains an alternative structure to teaching micro and macroeconomic theory and describes the characteristics that make it an effective framework for introductory and principles courses. The teaching of economics principles typically proceeds by separating macroeconomic theory and microeconomic theory. But the use of the macro-micro…

The Zero Product Principle Error.

ERIC Educational Resources Information Center

Padula, Janice

1996-01-01

Argues that the challenge for teachers of algebra in Australia is to find ways of making the structural aspects of algebra accessible to a greater percentage of students. Uses the zero product principle to provide an example of a common student error grounded in the difficulty of understanding the structure of algebra. (DDR)

Regionalism of Air Force Accounting and Finance Offices.

DTIC Science & Technology

1988-04-01

facilities. (2:40) The present organizational structure of AFOs is a structure which Leonard Kazm.ier in Principles of Management would describe as...Leonard J. Principles of Management . New York: McGraw-Hill Book Company, 1964, p. 82. 2. Newman, William H. and Summer, Charles E. Jr., The Process

Modeling and analysis of a large deployable antenna structure

NASA Astrophysics Data System (ADS)

Chu, Zhengrong; Deng, Zongquan; Qi, Xiaozhi; Li, Bing

2014-02-01

One kind of large deployable antenna (LDA) structure is proposed by combining a number of basic deployable units in this paper. In order to avoid vibration caused by fast deployment speed of the mechanism, a braking system is used to control the spring-actuated system. Comparisons between the LDA structure and a similar structure used by the large deployable reflector (LDR) indicate that the former has potential for use in antennas with up to 30 m aperture due to its lighter weight. The LDA structure is designed to form a spherical surface found by the least square fitting method so that it can be symmetrical. In this case, the positions of the terminal points in the structure are determined by two principles. A method to calculate the cable network stretched on the LDA structure is developed, which combines the original force density method and the parabolic surface constraint. Genetic algorithm is applied to ensure that each cable reaches a desired tension, which avoids the non-convergence issue effectively. We find that the pattern for the front and rear cable net must be the same when finding the shape of the rear cable net, otherwise anticlastic surface would generate.

Principles for Sustainable Governance of the Oceans

PubMed

Costanza; Andrade; Antunes; den Belt M; Boersma; Boesch; Catarino; Hanna; Limburg; Low; Molitor; Pereira; Rayner; Santos; Wilson; Young

1998-07-10

Pressures being exerted on the ocean ecosystems through overfishing, pollution, and environmental and climate change are increasing. Six core principles are proposed to guide governance and use of ocean resources and to promote sustainability. Examples of governance structures that embody these principles are given.

Effect of Mg doping on the Structure and Reflectivity of Alumina surfaces

NASA Astrophysics Data System (ADS)

Pennycook, Timothy; Idrobo, Juan C.; Varga, Kalman; Pantelides, Sokrates T.

2008-03-01

Mg is used in the fabrication of Al alloys to increase the strength of the material. In typical applications, a layer of alumina is present on the surface. The high diffusivity and chemical reactivity of Mg means that Mg can migrate from the bulk alloy to the alumina film and the surface, where it can affect the structural and optical properties of the material. The doping of Al alloys with Mg is known to cause ``darkening'' and affect the coloration of the material. We will report results of first principles density functional theory calculations that explore the segregation modes of Mg in the near-surface region of alumina and the corresponding effect on optical properties, i.e., reflectivity. This work is supported in part by NSF grant DMR-0513048 and ALCOA Inc.

Oscillatory electrostatic potential on graphene induced by group IV element decoration

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

Du, Chunyan; Yu, Liwei; Liu, Xiaojie

The structures and electronic properties of partial C, Si and Ge decorated graphene were investigated by first-principles calculations. The calculations show that the interaction between graphene and the decoration patches is weak and the semiconductor patches act as agents for weak electron doping without much disturbing graphene electronic π-bands. Redistribution of electrons due to the partial decoration causes the electrostatic potential lower in the decorated graphene areas, thus induced an electric field across the boundary between the decorated and non-decorated domains. Such an alternating electric field can change normal stochastic adatom diffusion to biased diffusion, leading to selective mass transport.

Plenoptic wavefront sensor with scattering pupil.

PubMed

Vdovin, Gleb; Soloviev, Oleg; Loktev, Mikhail

2014-04-21

We consider a wavefront sensor combining scattering pupil with a plenoptic imager. Such a sensor utilizes the same reconstruction principle as the Hartmann-Shack sensor, however it is free from the ambiguity of the spot location caused by the periodic structure of the sensor matrix, and allows for wider range of measured aberrations. In our study, sensor with scattering pupil has demonstrated a good match between the introduced and reconstructed aberrations, both in the simulation and experiment. The concept is expected to be applicable to optical metrology of strongly distorted wavefronts, especially for measurements through dirty, distorted, or scattering windows and pupils, such as cataract eyes.

Computational Thermomechanical Modelling of Early-Age Silicate Composites

NASA Astrophysics Data System (ADS)

Vala, J.; Št'astník, S.; Kozák, V.

2009-09-01

Strains and stresses in early-age silicate composites, widely used in civil engineering, especially in fresh concrete mixtures, in addition to those caused by exterior mechanical loads, are results of complicated non-deterministic physical and chemical processes. Their numerical prediction at the macro-scale level requires the non-trivial physical analysis based on the thermodynamic principles, making use of micro-structural information from both theoretical and experimental research. The paper introduces a computational model, based on a nonlinear system of macroscopic equations of evolution, supplied with certain effective material characteristics, coming from the micro-scale analysis, and sketches the algorithm for its numerical analysis.

Oscillatory electrostatic potential on graphene induced by group IV element decoration

DOE PAGES

Du, Chunyan; Yu, Liwei; Liu, Xiaojie; ...

2017-10-13

The structures and electronic properties of partial C, Si and Ge decorated graphene were investigated by first-principles calculations. The calculations show that the interaction between graphene and the decoration patches is weak and the semiconductor patches act as agents for weak electron doping without much disturbing graphene electronic π-bands. Redistribution of electrons due to the partial decoration causes the electrostatic potential lower in the decorated graphene areas, thus induced an electric field across the boundary between the decorated and non-decorated domains. Such an alternating electric field can change normal stochastic adatom diffusion to biased diffusion, leading to selective mass transport.

Proteins as sponges: a statistical journey along protein structure organization principles.

PubMed

Paola, Luisa Di; Paci, Paola; Santoni, Daniele; Ruvo, Micol De; Giuliani, Alessandro

2012-02-27

The analysis of a large database of protein structures by means of topological and shape indexes inspired by complex network and fractal analysis shed light on some organizational principles of proteins. Proteins appear much more similar to "fractal" sponges than to closely packed spheres, casting doubts on the tenability of the hydrophobic core concept. Principal component analysis highlighted three main order parameters shaping the protein universe: (1) "size", with the consequent generation of progressively less dense and more empty structures at an increasing number of residues, (2) "microscopic structuring", linked to the existence of a spectrum going from the prevalence of heterologous (different hydrophobicity) to the prevalence of homologous (similar hydrophobicity) contacts, and (3) "fractal shape", an organizing protein data set along a continuum going from approximately linear to very intermingled structures. Perhaps the time has come for seriously taking into consideration the real relevance of time-honored principles like the hydrophobic core and hydrophobic effect.

Clinical Trial Design Principles and Endpoint Definitions for Transcatheter Mitral Valve Repair and Replacement: Part 1: Clinical Trial Design Principles: A Consensus Document From the Mitral Valve Academic Research Consortium.

PubMed

Stone, Gregg W; Vahanian, Alec S; Adams, David H; Abraham, William T; Borer, Jeffrey S; Bax, Jeroen J; Schofer, Joachim; Cutlip, Donald E; Krucoff, Mitchell W; Blackstone, Eugene H; Généreux, Philippe; Mack, Michael J; Siegel, Robert J; Grayburn, Paul A; Enriquez-Sarano, Maurice; Lancellotti, Patrizio; Filippatos, Gerasimos; Kappetein, Arie Pieter

2015-07-21

Mitral regurgitation (MR) is one of the most prevalent valve disorders and has numerous etiologies, including primary (organic) MR, due to underlying degenerative/structural mitral valve (MV) pathology, and secondary (functional) MR, which is principally caused by global or regional left ventricular remodeling and/or severe left atrial dilation. Diagnosis and optimal management of MR requires integration of valve disease and heart failure specialists, MV cardiac surgeons, interventional cardiologists with expertise in structural heart disease, and imaging experts. The introduction of transcatheter MV therapies has highlighted the need for a consensus approach to pragmatic clinical trial design and uniform endpoint definitions to evaluate outcomes in patients with MR. The Mitral Valve Academic Research Consortium is a collaboration between leading academic research organizations and physician-scientists specializing in MV disease from the United States and Europe. Three in-person meetings were held in Virginia and New York during which 44 heart failure, valve, and imaging experts, MV surgeons and interventional cardiologists, clinical trial specialists and statisticians, and representatives from the U.S. Food and Drug Administration considered all aspects of MV pathophysiology, prognosis, and therapies, culminating in a 2-part document describing consensus recommendations for clinical trial design (Part 1) and endpoint definitions (Part 2) to guide evaluation of transcatheter and surgical therapies for MR. The adoption of these recommendations will afford robustness and consistency in the comparative effectiveness evaluation of new devices and approaches to treat MR. These principles may be useful for regulatory assessment of new transcatheter MV devices, as well as for monitoring local and regional outcomes to guide quality improvement initiatives. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Birth-date dependent population ethics: critical-level principles.

PubMed

Blackorby, C; Bossert, W; Donaldson, D

1997-12-01

"This paper investigates birth-date dependent principles for social evaluation in an intertemporal framework in which population size may vary. We weaken the strong Pareto principle in order to allow individuals' birth dates to matter in establishing a social ordering. Using the axiom independence of the utilities of the dead, we characterize population principles with a recursive structure. If the individual substitution principle and an individual intertemporal equivalence axiom are added, birth-date dependent generalizations of the critical-level generalized utilitarian principles result. Stationarity leads to the special case of geometric discounting." excerpt

Structural building principles of complex face-centered cubic intermetallics.

PubMed

Dshemuchadse, Julia; Jung, Daniel Y; Steurer, Walter

2011-08-01

Fundamental structural building principles are discussed for all 56 known intermetallic phases with approximately 400 or more atoms per unit cell and space-group symmetry F43m, Fd3m, Fd3, Fm3m or Fm3c. Despite fundamental differences in chemical composition, bonding and electronic band structure, their complex crystal structures show striking similarities indicating common building principles. We demonstrate that the structure-determining elements are flat and puckered atomic {110} layers stacked with periodicities 2p. The atoms on this set of layers, which intersect each other, form pentagon face-sharing endohedral fullerene-like clusters arranged in a face-centered cubic packing (f.c.c.). Due to their topological layer structure, all these crystal structures can be described as (p × p × p) = p(3)-fold superstructures of a common basic structure of the double-diamond type. The parameter p, with p = 3, 4, 7 or 11, is determined by the number of layers per repeat unit and the type of cluster packing, which in turn are controlled by chemical composition.

Anisotropy and temperature dependence of structural, thermodynamic, and elastic properties of crystalline cellulose Iβ: a first-principles investigation

Treesearch

ShunLi Shang; Louis G. Hector Jr.; Paul Saxe; Zi-Kui Liu; Robert J. Moon; Pablo D. Zavattieri

2014-01-01

Anisotropy and temperature dependence of structural, thermodynamic and elastic properties of crystalline cellulose Iβ were computed with first-principles density functional theory (DFT) and a semi-empirical correction for van der Waals interactions. Specifically, we report the computed temperature variation (up to 500...

CARd-3D: Carbon Distribution in 3D Structure Program for Globular Proteins

PubMed Central

Ekambaram, Rajasekaran; Kannaiyan, Akila; Marimuthu, Vijayasarathy; Swaminathan, Vinobha Chinnaiah; Renganathan, Senthil; Perumal, Ananda Gopu

2014-01-01

Spatial arrangement of carbon in protein structure is analyzed here. Particularly, the carbon fractions around individual atoms are compared. It is hoped that it follows the principle of 31.45% carbon around individual atoms. The results reveal that globular protein's atoms follow this principle. A comparative study on monomer versus dimer reveal that carbon is better distributed in dimeric form than in its monomeric form. Similar study on solid versus liquid structures reveals that the liquid (NMR) structure has better carbon distribution over the corresponding solid (X-Ray) structure. The carbon fraction distributions in fiber and toxin protein are compared. Fiber proteins follow the principle of carbon fraction distribution. At the same time it has another broad spectrum of carbon distribution than in globular proteins. The toxin protein follows an abnormal carbon fraction distribution. The carbon fraction distribution plays an important role in deciding the structure and shape of proteins. It is hoped to help in understanding the protein folding and function. PMID:24748753

The Ammonia Synthesis Reaction: An Exception to the Le Chatelier Principle and Effects of Nonideality

ERIC Educational Resources Information Center

Uline, Mark J.; Corti, David S.

2006-01-01

Le Chatelier's principle states that the further addition of a particular component will cause the reaction to shift in the direction that reduces the total number of moles of the system. However, the addition of one reactant [N[subscript 2

Structured light optical microscopy for three-dimensional reconstruction of technical surfaces

NASA Astrophysics Data System (ADS)

Kettel, Johannes; Reinecke, Holger; Müller, Claas

2016-04-01

In microsystems technology quality control of micro structured surfaces with different surface properties is playing an ever more important role. The process of quality control incorporates three-dimensional (3D) reconstruction of specularand diffusive reflecting technical surfaces. Due to the demand on high measurement accuracy and data acquisition rates, structured light optical microscopy has become a valuable solution to solve this problem providing high vertical and lateral resolution. However, 3D reconstruction of specular reflecting technical surfaces still remains a challenge to optical measurement principles. In this paper we present a measurement principle based on structured light optical microscopy which enables 3D reconstruction of specular- and diffusive reflecting technical surfaces. It is realized using two light paths of a stereo microscope equipped with different magnification levels. The right optical path of the stereo microscope is used to project structured light onto the object surface. The left optical path is used to capture the structured illuminated object surface with a camera. Structured light patterns are generated by a Digital Light Processing (DLP) device in combination with a high power Light Emitting Diode (LED). Structured light patterns are realized as a matrix of discrete light spots to illuminate defined areas on the object surface. The introduced measurement principle is based on multiple and parallel processed point measurements. Analysis of the measured Point Spread Function (PSF) by pattern recognition and model fitting algorithms enables the precise calculation of 3D coordinates. Using exemplary technical surfaces we demonstrate the successful application of our measurement principle.

Conformational structures of a decapeptide validated by first principles calculations and cold ion spectroscopy.

PubMed

Roy, Tapta Kanchan; Kopysov, Vladimir; Nagornova, Natalia S; Rizzo, Thomas R; Boyarkin, Oleg V; Gerber, R Benny

2015-05-18

Calculated structures of the two most stable conformers of a protonated decapeptide gramicidin S in the gas phase have been validated by comparing the vibrational spectra, calculated from first- principles and measured in a wide spectral range using infrared (IR)-UV double resonance cold ion spectroscopy. All the 522 vibrational modes of each conformer were calculated quantum mechanically and compared with the experiment without any recourse to an empirical scaling. The study demonstrates that first-principles calculations, when accounting for vibrational anharmonicity, can reproduce high-resolution experimental spectra well enough for validating structures of molecules as large as of 200 atoms. The validated accurate structures of the peptide may serve as templates for in silico drug design and absolute calibration of ion mobility measurements. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of truncation on very small cardiac SPECT camerasystems

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

Rohmer, Damien; Eisner, Robert L.; Gullberg, Grant T.

2006-08-01

Background: The limited transaxial field-of-view (FOV) of avery small cardiac SPECT camera system causes view-dependent truncationof the projection of structures exterior to, but near the heart. Basictomographic principles suggest that the reconstruction of non-attenuatedtruncated data gives a distortion-free image in the interior of thetruncated region, but the DC term of the Fourier spectrum of thereconstructed image is incorrect, meaning that the intensity scale of thereconstruction is inaccurate. The purpose of this study was tocharacterize the reconstructed image artifacts from truncated data, andto quantify their effects on the measurement of tracer uptake in themyocardial. Particular attention was given to instances wheremore » the heartwall is close to hot structures (structures of high activity uptake).Methods: The MCAT phantom was used to simulate a 2D slice of the heartregion. Truncated and non-truncated projections were formed both with andwithout attenuation. The reconstructions were analyzed for artifacts inthe myocardium caused by truncation, and for the effect that attenuationhas relative to increasing those artifacts. Results: The inaccuracy dueto truncation is primarily caused by an incorrect DC component. Forvisualizing theleft ventricular wall, this error is not worse than theeffect of attenuation. The addition of a small hot bowel-like structurenear the left ventricle causes few changes in counts on the wall. Largerartifacts due to the truncation are located at the boundary of thetruncation and can be eliminated by sinogram interpolation. Finally,algebraic reconstruction methods are shown to give better reconstructionresults than an analytical filtered back-projection reconstructionalgorithm. Conclusion: Small inaccuracies in reconstructed images fromsmall FOV camera systems should have little effect on clinicalinterpretation. However, changes in the degree of inaccuracy in countsfrom slice toslice are due to changes in the truncated structures. Thesecan result in a visual 3-dimensional distortion. As with conventionallarge FOV systems attenuation effects have a much more significant effecton image accuracy.« less

Symmetry as Bias: Rediscovering Special Relativity

NASA Technical Reports Server (NTRS)

Lowry, Michael R.

1992-01-01

This paper describes a rational reconstruction of Einstein's discovery of special relativity, validated through an implementation: the Erlanger program. Einstein's discovery of special relativity revolutionized both the content of physics and the research strategy used by theoretical physicists. This research strategy entails a mutual bootstrapping process between a hypothesis space for biases, defined through different postulated symmetries of the universe, and a hypothesis space for physical theories. The invariance principle mutually constrains these two spaces. The invariance principle enables detecting when an evolving physical theory becomes inconsistent with its bias, and also when the biases for theories describing different phenomena are inconsistent. Structural properties of the invariance principle facilitate generating a new bias when an inconsistency is detected. After a new bias is generated. this principle facilitates reformulating the old, inconsistent theory by treating the latter as a limiting approximation. The structural properties of the invariance principle can be suitably generalized to other types of biases to enable primal-dual learning.

Extinction by a Homogeneous Spherical Particle in an Absorbing Medium

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Videen, Gorden; Yang, Ping

2017-01-01

We use a recent computer implementation of the first principles theory of electromagnetic scattering to compute far-field extinction by a spherical particle embedded in an absorbing unbounded host. Our results show that the suppressing effect of increasing absorption inside the host medium on the ripple structure of the extinction efficiency factor as a function of the size parameter is similar to the well-known effect of increasing absorption inside a particle embedded in a nonabsorbing host. However, the accompanying effects on the interference structure of the extinction efficiency curves are diametrically opposite. As a result, sufficiently large absorption inside the host medium can cause negative particulate extinction. We offer a simple physical explanation of the phenomenon of negative extinction consistent with the interpretation of the interference structure as being the result of interference of the field transmitted by the particle and the diffracted field due to an incomplete wave front resulting from the blockage of the incident plane wave by the particle's geometrical projection.

Dynamical ion transfer between coupled Coulomb crystals in a double-well potential.

PubMed

Klumpp, Andrea; Zampetaki, Alexandra; Schmelcher, Peter

2017-09-01

We investigate the nonequilibrium dynamics of coupled Coulomb crystals of different sizes trapped in a double well potential. The dynamics is induced by an instantaneous quench of the potential barrier separating the two crystals. Due to the intra- and intercrystal Coulomb interactions and the asymmetric population of the potential wells, we observe a complex reordering of ions within the two crystals as well as ion transfer processes from one well to the other. The study and analysis of the latter processes constitutes the main focus of this work. In particular, we examine the dependence of the observed ion transfers on the quench amplitude performing an analysis for different crystalline configurations ranging from one-dimensional ion chains via two-dimensional zigzag chains and ring structures to three-dimensional spherical structures. Such an analysis provides us with the means to extract the general principles governing the ion transfer dynamics and we gain some insight on the structural disorder caused by the quench of the barrier height.

Monitoring of corrosion damage using high-frequency guided ultrasonic waves

NASA Astrophysics Data System (ADS)

Chew, D.; Fromme, P.

2014-03-01

Due to adverse environmental conditions corrosion can develop during the life cycle of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the integrity and load bearing capacity of the structure. Structural health monitoring of corrosion damage in difficult to access areas can in principle be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic transducers with single sided access to the structure, high frequency guided wave modes were generated that penetrate through the complete thickness of the structure. Wall thickness reduction was induced using accelerated corrosion in a salt water bath. The corrosion damage was monitored based on the effect on the wave propagation and interference of the different modes. The change in the wave interference was quantified based on an analysis in the frequency domain (Fourier transform) and was found to match well with theoretical predictions for the wall thickness loss. High frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

Monitoring of corrosion damage using high-frequency guided ultrasonic waves

NASA Astrophysics Data System (ADS)

Chew, D.; Fromme, P.

2015-03-01

Due to adverse environmental conditions corrosion can develop during the life cycle of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the integrity and load bearing capacity of the structure. Structural health monitoring of corrosion damage in difficult to access areas can in principle be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic transducers with single sided access to the structure, high frequency guided wave modes were generated that penetrate through the complete thickness of the structure. Wall thickness reduction was induced using accelerated corrosion in a salt water bath. The corrosion damage was monitored based on the effect on the wave propagation and interference of the different modes. The change in the wave interference was quantified based on an analysis in the frequency domain (Fourier transform) and was found to match well with theoretical predictions for the wall thickness loss. High frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

Iron Deprivation Treatment of Breast Cancer: Preclinical Studies

DTIC Science & Technology

1999-01-01

of cytotoxic T lymphocytes in vivo and can cause some degree of inhibition of skin graft rejection. This finding could, in principle, be of therapeutic...generation of cytotoxic T lymphocytes and can, in some cases, retard skin graft rejection. Such findings might, in principle, be relevant to the treatment

Spinal Injuries in the Aquatics Environment, Part I: Prevention.

ERIC Educational Resources Information Center

Dworkin, Gerald M.

1987-01-01

Water-related activities are the number one cause of spinal cord injuries resulting from sports and recreation activities. This article discusses principles of safe diving; principles of safe water sliding; ways to reduce springboard diving accidents; factors contributing to springboard diving accidents; and safety recommendations for open water…

Evidence-based topical management of chronic wounds according to the T.I.M.E. principle.

PubMed

Klein, Silvan; Schreml, Stephan; Dolderer, Juergen; Gehmert, Sebastian; Niederbichler, Andreas; Landthaler, Michael; Prantl, Lukas

2013-09-01

The number of patients suffering from chronic wound healing disorders in Germany alone is estimated to be 2.5-4 million. Therapy related expenses reach 5-8 billion Euros annually. This number is partially caused by costly dressing changes due to non-standardized approaches and the application of non-evidence-based topical wound therapies. The purpose of this paper is to elucidate a straightforward principle for the management of chronic wounds, and to review the available evidence for the particular therapy options. The T.I.M.E.-principle (Tissue management, Inflammation and infection control, Moisture balance, Epithelial [edge] advancement) was chosen as a systematic strategy for wound bed preparation. Literature was retrieved from the PubMed and Cochrane Library databases and subjected to selective analysis. Topical wound management should be carried out according to a standardized principle and should further be synchronized to the phases of wound healing. Despite the broad implementation of these products in clinical practice, often no benefit exists in the rate of healing, when evaluated in meta-analyses or systematic reviews. This insufficient evidence is additionally limited by varying study designs. In case of non-superiority, the results suggest to prefer relatively inexpensive wound dressings over expensive alternatives. Arbitrary endpoints to prove the effectiveness of wound dressings, contribute to the random use of such therapies. Defining rational endpoints for future studies as well as the deployment of structured therapy strategies will be essential for the economical and evidence-based management of chronic wounds. © The Authors | Journal compilation © Blackwell Verlag GmbH, Berlin.

Cognitive Science Implications for Enhancing Training Effectiveness in a Serious Gaming Context

ERIC Educational Resources Information Center

Greitzer, Frank L.; Kuchar, Olga Anna; Huston, Kristy

2007-01-01

Serious games use entertainment principles, creativity, and technology to meet government or corporate training objectives, but these principles alone will not guarantee that the intended learning will occur. To be effective, serious games must incorporate sound cognitive, learning, and pedagogical principles into their design and structure. In…

The Capacity for Music: What Is It, and What's Special about It?

ERIC Educational Resources Information Center

Jackendoff, Ray; Lerdahl, Fred

2006-01-01

We explore the capacity for music in terms of five questions: (1) What cognitive structures are invoked by music? (2) What are the principles that create these structures? (3) How do listeners acquire these principles? (4) What pre-existing resources make such acquisition possible? (5) Which aspects of these resources are specific to music, and…

Fraction of boroxol rings in vitreous boron oxide from a first-principles analysis of Raman and NMR spectra.

PubMed

Umari, P; Pasquarello, Alfredo

2005-09-23

We determine the fraction f of B atoms belonging to boroxol rings in vitreous boron oxide through a first-principles analysis. After generating a model structure of vitreous B2O3 by first-principles molecular dynamics, we address a large set of properties, including the neutron structure factor, the neutron density of vibrational states, the infrared spectra, the Raman spectra, and the 11B NMR spectra, and find overall good agreement with corresponding experimental data. From the analysis of Raman and 11B NMR spectra, we yield consistently for both probes a fraction f of approximately 0.75. This result indicates that the structure of vitreous boron oxide is largely dominated by boroxol rings.

Relativistic Spin-Orbit Heavy Atom on the Light Atom NMR Chemical Shifts: General Trends Across the Periodic Table Explained.

PubMed

Vícha, Jan; Komorovsky, Stanislav; Repisky, Michal; Marek, Radek; Straka, Michal

2018-06-12

The importance of relativistic effects on the NMR parameters in heavy-atom (HA) compounds, particularly the SO-HALA (Spin-Orbit Heavy Atom on the Light Atom) effect on NMR chemical shifts, has been known for about 40 years. Yet, a general correlation between the electronic structure and SO-HALA effect has been missing. By analyzing 1 H NMR chemical shifts of the sixth-period hydrides (Cs-At), we discovered general electronic-structure principles and mechanisms that dictate the size and sign of the SO-HALA NMR chemical shifts. In brief, partially occupied HA valence shells induce relativistic shielding at the light atom (LA) nuclei, while empty HA valence shells induce relativistic deshielding. In particular, the LA nucleus is relativistically shielded in 5d 2 -5d 8 and 6p 4 HA hydrides and deshielded in 4f 0 , 5d 0 , 6s 0 , and 6p 0 HA hydrides. This general and intuitive concept explains periodic trends in the 1 H NMR chemical shifts along the sixth-period hydrides (Cs-At) studied in this work. We present substantial evidence that the introduced principles have a general validity across the periodic table and can be extended to nonhydride LAs. The decades-old question of why compounds with occupied frontier π molecular orbitals (MOs) cause SO-HALA shielding at the LA nuclei, while the frontier σ MOs cause deshielding is answered. We further derive connection between the SO-HALA NMR chemical shifts and Spin-Orbit-induced Electron Deformation Density (SO-EDD), a property that can be obtained easily from differential electron densities and can be represented graphically. SO-EDD provides an intuitive understanding of the SO-HALA effect in terms of the depletion/concentration of the electron density at LA nuclei caused by spin-orbit coupling due to HA in the presence of a magnetic field. Using an analogy between the SO-EDD concept and arguments from classic NMR theory, the complex question of the SO-HALA NMR chemical shifts becomes easily understandable for a wide chemical audience.

Zebrafish Discoveries in Cancer Epigenetics.

PubMed

Chernyavskaya, Yelena; Kent, Brandon; Sadler, Kirsten C

2016-01-01

The cancer epigenome is fundamentally different than that of normal cells. How these differences arise in and contribute to carcinogenesis is not known, and studies using model organisms such as zebrafish provide an opportunity to address these important questions. Modifications of histones and DNA comprise the complex epigenome, and these influence chromatin structure, genome stability and gene expression, all of which are fundamental to the cellular changes that cause cancer. The cancer genome atlas covers the wide spectrum of genetic changes associated with nearly every cancer type, however, this catalog is currently uni-dimensional. As the pattern of epigenetic marks and chromatin structure in cancer cells is described and overlaid on the mutational landscape, the map of the cancer genome becomes multi-dimensional and highly complex. Two major questions remain in the field: (1) how the epigenome becomes repatterned in cancer and (2) which of these changes are cancer-causing. Zebrafish provide a tractable in vivo system to monitor the epigenome during transformation and to identify epigenetic drivers of cancer. In this chapter, we review principles of cancer epigenetics and discuss recent work using zebrafish whereby epigenetic modifiers were established as cancer driver genes, thus providing novel insights into the mechanisms of epigenetic reprogramming in cancer.

Visceral fat estimation method by bioelectrical impedance analysis and causal analysis

NASA Astrophysics Data System (ADS)

Nakajima, Hiroshi; Tasaki, Hiroshi; Tsuchiya, Naoki; Hamaguchi, Takehiro; Shiga, Toshikazu

2011-06-01

It has been clarified that abdominal visceral fat accumulation is closely associated to the lifestyle disease and metabolic syndrome. The gold standard in medical fields is visceral fat area measured by an X-ray computer tomography (CT) scan or magnetic resonance imaging. However, their measurements are high invasive and high cost; especially a CT scan causes X-ray exposure. They are the reasons why medical fields need an instrument for viscera fat measurement with low invasive, ease of use, and low cost. The article proposes a simple and practical method of visceral fat estimation by employing bioelectrical impedance analysis and causal analysis. In the method, abdominal shape and dual impedances of abdominal surface and body total are measured to estimate a visceral fat area based on the cause-effect structure. The structure is designed according to the nature of abdominal body composition to be fine-tuned by statistical analysis. The experiments were conducted to investigate the proposed model. 180 subjects were hired to be measured by both a CT scan and the proposed method. The acquired model explained the measurement principle well and the correlation coefficient is 0.88 with the CT scan measurements.

Material design and structural color inspired by biomimetic approach

PubMed Central

Saito, Akira

2011-01-01

Generation of structural color is one of the essential functions realized by living organisms, and its industrial reproduction can result in numerous applications. From this viewpoint, the mechanisms, materials, analytical methods and fabrication technologies of the structural color are reviewed in this paper. In particular, the basic principles of natural photonic materials, the ideas developed from these principles, the directions of applications and practical industrial realizations are presented by summarizing the recent research results. PMID:27877459

[A basic health care center. Care oriented at the community].

PubMed

Marquilles Bonet, C; Quesada Santaulaira, L; Florensa Roca, C; Piñol Jové, M A; Cruz Esteve, I; Rodríguez Rosich, A

1997-01-01

Principle problems of a basic health care area (Lérida) are identified. This area, which has a patient case load of 22,244 people, was studied during the winter of 1993-94 by using information from various sources. Results indicate that the population of this community are basically young, urban, have a high cultural and social level, and are mostly employed. The principle causes of mortality are the same as in the rest of Cataluña. Diseases that cause the most working days lost to illness are: respiratory, mental and bone-joint problems. The most frequent diseases seen in the clinic are: hypertension, respiratory infections, endocrine and mental. An overall look at the state of health of these patients show that the principle problems are: tobacco use, high blood pressure, arthritis, lumbago, depression, stroke, diabetes and breast cancer.

Heat Transfer Principles in Thermal Calculation of Structures in Fire

PubMed Central

Zhang, Chao; Usmani, Asif

2016-01-01

Structural fire engineering (SFE) is a relatively new interdisciplinary subject, which requires a comprehensive knowledge of heat transfer, fire dynamics and structural analysis. It is predominantly the community of structural engineers who currently carry out most of the structural fire engineering research and design work. The structural engineering curriculum in universities and colleges do not usually include courses in heat transfer and fire dynamics. In some institutions of higher education, there are graduate courses for fire resistant design which focus on the design approaches in codes. As a result, structural engineers who are responsible for structural fire safety and are competent to do their jobs by following the rules specified in prescriptive codes may find it difficult to move toward performance-based fire safety design which requires a deep understanding of both fire and heat. Fire safety engineers, on the other hand, are usually focused on fire development and smoke control, and may not be familiar with the heat transfer principles used in structural fire analysis, or structural failure analysis. This paper discusses the fundamental heat transfer principles in thermal calculation of structures in fire, which might serve as an educational guide for students, engineers and researchers. Insights on problems which are commonly ignored in performance based fire safety design are also presented. PMID:26783379

First-principles surface interaction studies of aluminum-copper and aluminum-copper-magnesium secondary phases in aluminum alloys

NASA Astrophysics Data System (ADS)

da Silva, Thiago H.; Nelson, Eric B.; Williamson, Izaak; Efaw, Corey M.; Sapper, Erik; Hurley, Michael F.; Li, Lan

2018-05-01

First-principles density functional theory-based calculations were performed to study θ-phase Al2Cu, S-phase Al2CuMg surface stability, as well as their interactions with water molecules and chloride (Cl-) ions. These secondary phases are commonly found in aluminum-based alloys and are initiation points for localized corrosion. Density functional theory (DFT)-based simulations provide insight into the origins of localized (pitting) corrosion processes of aluminum-based alloys. For both phases studied, Cl- ions cause atomic distortions on the surface layers. The nature of the distortions could be a factor to weaken the interlayer bonds in the Al2Cu and Al2CuMg secondary phases, facilitating the corrosion process. Electronic structure calculations revealed not only electron charge transfer from Cl- ions to alloy surface but also electron sharing, suggesting ionic and covalent bonding features, respectively. The S-phase Al2CuMg structure has a more active surface than the θ-phase Al2Cu. We also found a higher tendency of formation of new species, such as Al3+, Al(OH)2+, HCl, AlCl2+, Al(OH)Cl+, and Cl2 on the S-phase Al2CuMg surface. Surface chemical reactions and resultant species present contribute to establishment of local surface chemistry that influences the corrosion behavior of aluminum alloys.

Hybrid phosphorene/graphene nanocomposite as an anode material for Na-ion batteries: a first-principles study

NASA Astrophysics Data System (ADS)

Wang, Linxia; Jiang, Zhiqiang; Li, Wei; Gu, Xiao; Huang, Li

2017-04-01

The potential application of the hybrid phosphorene/graphene (P/G) composites as an anode material in Na-ion batteries (NIBs) has been explored based on first-principles calculations. The calculated elastic constants reveal that the P/G has an ultrahigh stiffness, which can effectively suppress the undesirable structural deformation during the sodiation and desodiation cycles. Na atoms can strongly bind with the phosphorene single-layer (SP), double-layer (DP), and their composites with graphene (SP/G, DP/G, G/DP/G), and can even cause a sliding between the layers when the DP/G accommodate more Na atoms. The migration of Na in P/G is anisotropic with the minimum energy path along the zigzag channel. The low diffusion barriers of only about several tens of meV ensure the high mobility of Na within the layers, and thus lead to rapid charge/discharge capacity of P/G. The electronic structures show that the hybrid P/G becomes metallic with the Na incorporation, which contributes to the good electric conductivity in P/G. We further demonstrate that the average open circuit voltage (OCV) of DP/G is 0.53 V, which is comparable to other anode materials. These results suggest that P/G composites hold great potential to be a good anode material in NIBs.

Out-of-Focus Projector Calibration Method with Distortion Correction on the Projection Plane in the Structured Light Three-Dimensional Measurement System.

PubMed

Zhang, Jiarui; Zhang, Yingjie; Chen, Bo

2017-12-20

The three-dimensional measurement system with a binary defocusing technique is widely applied in diverse fields. The measurement accuracy is mainly determined by out-of-focus projector calibration accuracy. In this paper, a high-precision out-of-focus projector calibration method that is based on distortion correction on the projection plane and nonlinear optimization algorithm is proposed. To this end, the paper experimentally presents the principle that the projector has noticeable distortions outside its focus plane. In terms of this principle, the proposed method uses a high-order radial and tangential lens distortion representation on the projection plane to correct the calibration residuals caused by projection distortion. The final accuracy parameters of out-of-focus projector were obtained using a nonlinear optimization algorithm with good initial values, which were provided by coarsely calibrating the parameters of the out-of-focus projector on the focal and projection planes. Finally, the experimental results demonstrated that the proposed method can accuracy calibrate an out-of-focus projector, regardless of the amount of defocusing.

The helium effect at grain boundaries in Fe-Cr alloys: A first-principles study

NASA Astrophysics Data System (ADS)

Zemła, M. R.; Wróbel, J. S.; Wejrzanowski, T.; Nguyen-Manh, D.; Kurzydłowski, K. J.

2017-02-01

Helium is produced in the structural materials in nuclear power plants by nuclear transmutation following neutron irradiation. Since the solubility of helium in all metals is extremely low, helium tends to be trapped at defects such as vacancies, dislocations and grain boundaries, which cause material embrittlement. Density functional theory (DFT) calculations were performed in order to investigate the helium effect at grain boundaries (GBs) in iron-chromium alloys. Both cohesive energy and magnetic properties at symmetric Σ3(1 1 1) and Σ5(2 1 0) tilt Fe GBs are studied in the presence of Cr and He atoms. It is found that the presence of Cr atoms increases cohesive energy, at different He concentrations, and strongly influences magnetic properties at the GBs. The effect of the segregation energy of helium atom as a function of the different positions of Cr atoms located inside/outside a GB has been considered. Results of the present first-principles study enable one to clarify the role of Cr in understanding the helium effect in Fe-Cr-based alloys.

Understanding the pseudocapacitance of RuO2 from joint density functional theory

NASA Astrophysics Data System (ADS)

Zhan, Cheng; Jiang, De-en

2016-11-01

Pseudocapacitors have been experimentally studied for many years in electric energy storage. However, first principles understanding of the pseudocapacitive behavior is still not satisfactory due to the complexity involved in modeling electrochemistry. In this paper, we applied joint density functional theory (JDFT) to simulate the pseudocapacitive behavior of RuO2, a prototypical material, in a model electrolyte. We obtained from JDFT a capacitive curve which showed a redox peak position comparable to that in the experimental cyclic voltammetry (CV) curve. We found that the experimental turning point from double-layer to pseudocapacitive charge storage at low scan rates could be explained by the hydrogen adsorption at low coverage. As the electrode voltage becomes more negative, H coverage increases and causes the surface-structure change, leading to bended -OH bonds at the on-top oxygen atoms and large capacitance. This H coverage-dependent capacitance can explain the high pseudocapacitance of hydrous RuO2. Our work here provides a first principles understanding of the pseudocapacitance for RuO2 in particular and for transition-metal oxides in general.

Fiber-optic perimeter security system based on WDM technology

NASA Astrophysics Data System (ADS)

Polyakov, Alexandre V.

2017-10-01

Intelligent underground fiber optic perimeter security system is presented. Their structure, operation, software and hardware with neural networks elements are described. System allows not only to establish the fact of violation of the perimeter, but also to locate violations. This is achieved through the use of WDM-technology division spectral information channels. As used quasi-distributed optoelectronic recirculation system as a discrete sensor. The principle of operation is based on registration of the recirculation period change in the closed optoelectronic circuit at different wavelengths under microstrain exposed optical fiber. As a result microstrain fiber having additional power loss in a fiber optical propagating pulse, which causes a time delay as a result of switching moments of the threshold device. To separate the signals generated by intruder noise and interference, the signal analyzer is used, based on the principle of a neural network. The system detects walking, running or crawling intruder, as well as undermining attempts to register under the perimeter line. These alarm systems can be used to protect the perimeters of facilities such as airports, nuclear reactors, power plants, warehouses, and other extended territory.

First-principles study on the stability and magnetoelectric properties of multiferroic materials XTiO3 (X = Mn, Fe, Co, Ni)

NASA Astrophysics Data System (ADS)

Chen, Xing-Yuan; Lai, Guo-Xia; Gu, Di; Zhu, Wei-Ling; Lai, Tian-Shu; Zhao, Yu-Jun

2018-04-01

The XTiO3 (X = Mn, Fe, Co and Ni) materials with R3c structure could be grown under critical conditions based on first-principles calculations and thermodynamic stability analysis. FeTiO3 and MnTiO3 could be synthesized relatively easily under metal-rich and O-poor conditions, while NiTiO3 could be stable under Ni-rich, O-rich and Ti-poor conditions. The predicted R3c CoTiO3 under thermodynamic equilibrium conditions is suggested to be synthesized under Co-rich, O-rich and Ti-poor conditions, but the calculated phonon dispersion indicates R3c CoTiO3 becomes unstable under the dynamical conditions. The ferroelectric behavior in the XTiO3 (X = Mn, Fe, Co and Ni) system could be dominated by the Ti ion with d0 state and the strong hybridization between Ti and O, while the magnetic property is mainly caused by the contribution of 3d transition metal.

Ethical Implications in the Use of Embryonic and Adult Neural Stem Cells

PubMed Central

Ramos-Zúñiga, Rodrigo; González-Pérez, Oscar; Macías-Ornelas, Ana; Capilla-González, Vivian; Quiñones-Hinojosa, Alfredo

2012-01-01

The advent and growth of technological advances have led to new routes of knowledge. Thereby, we currently face new challenges. We have just started to get a glimpse of the structural and functional role of neural stem cells in differentiation and migration processes, the origin of synaptic networks, and subsequent readjustments in specific circuits. A whole range of treatment possibilities originates from this knowledge that potentially can be used for different neurological diseases in humans. Although this is an encouraging scenario, it implies that the human brain is the object of such study, as well as its potential manipulation and transplantation. It is, therefore, pertinent that ethical principles should be followed in such research to have proper balance between what can be done and what should be done, according to every specific context. Hence, it is wise to consider ethical implications in every research project, along with potential clinical applications, under the principle of causing no harm, following risk and benefit rules in decision making and with respect of the human condition as a priority. PMID:22997522

Allotropes of Phosphorus with Remarkable Stability and Intrinsic Piezoelectricity

NASA Astrophysics Data System (ADS)

Li, Zhenqing; He, Chaoyu; Ouyang, Tao; Zhang, Chunxiao; Tang, Chao; Römer, Rudolf A.; Zhong, Jianxin

2018-04-01

We construct a class of two-dimensional (2D) phosphorus allotropes by assembling a previously proposed ultrathin metastable phosphorus nanotube into planar structures in different stacking orientations. Based on first-principles methods, the structures, stabilities, and fundamental electronic properties of these allotropes are systematically investigated. Our results show that these 2D van der Waals phosphorene allotropes possess remarkable stabilities due to the strong intertube van der Waals interactions, which cause an energy release of about 30 - 70 meV /atom , depending on their stacking details. Most of them are confirmed to be energetically more favorable than the experimentally viable α -P and β -P . Three of them, showing a relatively higher probability of being synthesized in the future, are further confirmed to be dynamically stable semiconductors with strain-tunable band gaps and intrinsic piezoelectricity, which may have potential applications in nanosized sensors, piezotronics, and energy harvesting in portable electronic nanodevices.

Hidden Order and Dimensional Crossover of the Charge Density Waves in TiSe 2

DOE PAGES

Chen, P.; Chan, Y. -H.; Fang, X. -Y.; ...

2016-11-29

Charge density wave (CDW) formation, a key physics issue for materials, arises from interactions among electrons and phonons that can also lead to superconductivity and other competing or entangled phases. The prototypical system TiSe 2, with a particularly simple (2 × 2 × 2) transition and no Kohn anomalies caused by electron-phonon coupling, is a fascinating but unsolved case after decades of research. Our angle-resolved photoemission measurements of the band structure as a function of temperature, aided by first-principles calculations, reveal a hitherto undetected but crucial feature: a (2 × 2) electronic order in each layer sets in at ~232more » K before the widely recognized three-dimensional structural order at ~205 K. The dimensional crossover, likely a generic feature of such layered materials, involves renormalization of different band gaps in two stages.« less

A novel algorithm using an orthotropic material model for topology optimization

NASA Astrophysics Data System (ADS)

Tong, Liyong; Luo, Quantian

2017-09-01

This article presents a novel algorithm for topology optimization using an orthotropic material model. Based on the virtual work principle, mathematical formulations for effective orthotropic material properties of an element containing two materials are derived. An algorithm is developed for structural topology optimization using four orthotropic material properties, instead of one density or area ratio, in each element as design variables. As an illustrative example, minimum compliance problems for linear and nonlinear structures are solved using the present algorithm in conjunction with the moving iso-surface threshold method. The present numerical results reveal that: (1) chequerboards and single-node connections are not present even without filtering; (2) final topologies do not contain large grey areas even using a unity penalty factor; and (3) the well-known numerical issues caused by low-density material when considering geometric nonlinearity are resolved by eliminating low-density elements in finite element analyses.

[Proposing a physiological model for Emergency Department. Operating principles, classification of overcrowding and guidelines for redesign].

PubMed

Herrera Carranza, M; Aguado Correa, F; Padilla Garrido, N; López Camacho, F

2017-04-30

The operation of Emergency Departments (ED) is determined by demand, their own organizational structures and the connection to other medical care levels. When these elements are not simultaneous, it hinders patient flow and decreases capacity, making it necessary to employ a systemic approach to the chain of emergency care as a single operational entity. With this theoretical orientation, we suggest a conceptual model similar to the physiological cardiac output, in which the preload is the demand, the contractile or flow pump is the organizational structure, the afterload is the hospital, the pre-ED valve is primary care and outpatient emergencies, and the post-ED valve is the diagnostic support services and the specialist consultants. Based on this theoretical approach we classify the different types of ED overcrowding and systematise its causes and the different waiting lists that it generates, which can help to redesign the service and avoid its saturation.

Theoretical analysis of stack gas emission velocity measurement by optical scintillation

NASA Astrophysics Data System (ADS)

Yang, Yang; Dong, Feng-Zhong; Ni, Zhi-Bo; Pang, Tao; Zeng, Zong-Yong; Wu, Bian; Zhang, Zhi-Rong

2014-04-01

Theoretical analysis for an online measurement of the stack gas flow velocity based on the optical scintillation method with a structure of two parallel optical paths is performed. The causes of optical scintillation in a stack are first introduced. Then, the principle of flow velocity measurement and its mathematical expression based on cross correlation of the optical scintillation are presented. The field test results show that the flow velocity measured by the proposed technique in this article is consistent with the value tested by the Pitot tube. It verifies the effectiveness of this method. Finally, by use of the structure function of logarithmic light intensity fluctuations, the theoretical explanation of optical scintillation spectral characteristic in low frequency is given. The analysis of the optical scintillation spectrum provides the basis for the measurement of the stack gas flow velocity and particle concentration simultaneously.

Interface structure in Cu/Ta2O5/Pt resistance switch: a first-principles study.

PubMed

Xiao, Bo; Watanabe, Satoshi

2015-01-14

The interface structures of a Cu/Ta2O5/Pt resistance switch under various oxidation conditions have been examined from first-principles. The O-rich Cu/Ta2O5 interface is found to be stable within a wide range of O chemical potentials. In this interface structure, a considerable number of interface Cu atoms tend to migrate to the amorphous Ta2O5 (a-Ta2O5) layer, which causes the formation of the Cu2O layer. The interface Cu atoms become more ionized with an increase in the interface O concentration and/or temperature. These ionized Cu(+) ions could function as one of the main sources for the formation of conduction filaments in the Cu/a-Ta2O5/Pt resistance switch. In contrast, the ionization of the interface Cu atoms is not observed in the Cu/crystal-Ta2O5 interface primarily due to the much lower Cu ionic conductivity in crystal-Ta2O5 than that in amorphous state. In addition, the Pt electrode could not be ionized, irrespective of the interface O concentration and temperature. The formation of interface O vacancies in Pt/Ta2O5 is always energetically more stable than that in Cu/Ta2O5, which may be partly responsible for the cone shape of conduction filament formed in the Cu/a-Ta2O5/Pt resistance switch, where the base of the cone lies on the Pt/Ta2O5 interface.

The Choice between MapMan and Gene Ontology for Automated Gene Function Prediction in Plant Science

PubMed Central

Klie, Sebastian; Nikoloski, Zoran

2012-01-01

Since the introduction of the Gene Ontology (GO), the analysis of high-throughput data has become tightly coupled with the use of ontologies to establish associations between knowledge and data in an automated fashion. Ontologies provide a systematic description of knowledge by a controlled vocabulary of defined structure in which ontological concepts are connected by pre-defined relationships. In plant science, MapMan and GO offer two alternatives for ontology-driven analyses. Unlike GO, initially developed to characterize microbial systems, MapMan was specifically designed to cover plant-specific pathways and processes. While the dependencies between concepts in MapMan are modeled as a tree, in GO these are captured in a directed acyclic graph. Therefore, the difference in ontologies may cause discrepancies in data reduction, visualization, and hypothesis generation. Here provide the first systematic comparative analysis of GO and MapMan for the case of the model plant species Arabidopsis thaliana (Arabidopsis) with respect to their structural properties and difference in distributions of information content. In addition, we investigate the effect of the two ontologies on the specificity and sensitivity of automated gene function prediction via the coupling of co-expression networks and the guilt-by-association principle. Automated gene function prediction is particularly needed for the model plant Arabidopsis in which only half of genes have been functionally annotated based on sequence similarity to known genes. The results highlight the need for structured representation of species-specific biological knowledge, and warrants caution in the design principles employed in future ontologies. PMID:22754563

Validation of "Teaching and Learning Guiding Principles Instrument" for Malaysian Higher Learning Institutions

ERIC Educational Resources Information Center

Rahman, Nurulhuda Abd; Masuwai, Azwani; Tajudin, Nor'ain Mohd; Tek, Ong Eng; Adnan, Mazlini

2016-01-01

Purpose: This study was aimed at establishing, through the validation of the "Teaching and Learning Guiding Principles Instrument" (TLGPI), the validity and reliability of the underlying factor structure of the Teaching and Learning Guiding Principles (TLGP) generated by a previous study. Method: A survey method was used to collect data…

Kuhn's Paradigm and Example-Based Teaching of Newtonian Mechanics.

ERIC Educational Resources Information Center

Whitaker, M. A. B.

1980-01-01

Makes a recommendation for more direct teaching of the basic principles of mechanics. Contends that students currently learn mechanics in terms of standard examples. This causes difficulty when the student is confronted with a problem that can be solved from basic principles, but which does not fit a standard category. (GS)

Some principles to guide wilderness campsite management

Treesearch

David N. Cole

1990-01-01

Seven principles, derived from research on wilderness campsites, are proposed: (1) campsite impacts are complex; (2) impact is inevitable with repetitive use of campsites; (3) impact occurs rapidly, recovery occurs slowly; (4) the relationship between use and impact is asymptotic; (5) certain sites are more durable than others; (6) certain users cause less impact than...

How Does Your Protein Fold? Elucidating the Apomyoglobin Folding Pathway

PubMed Central

Dyson, H. Jane; Wright, Peter E.

2017-01-01

Conspectus Although each type of protein fold and in some cases individual proteins within a fold classification can have very different mechanisms of folding, the underlying biophysical and biochemical principles that operate to cause a linear polypeptide chain to fold into a globular structure must be the same. In an aqueous solution, the protein takes up the thermodynamically most stable structure, but the pathway along which the polypeptide proceeds in order to reach that structure is a function of the amino acid sequence, which must be the final determining factor, not only in shaping the final folded structure, but in dictating the folding pathway. A number of groups have focused on a single protein or group of proteins, to determine in detail the factors that influence the rate and mechanism of folding in a defined system, with the hope that hypothesis-driven experiments can elucidate the underlying principles governing the folding process. Our research group has focused on the folding of the globin family of proteins, and in particular on the monomeric protein apomyoglobin. Apomyoglobin (apoMb) folds relatively slowly (~2 seconds) via an ensemble of obligatory intermediates that form rapidly after the initiation of folding. The folding pathway can be dissected using rapid-mixing techniques, which can probe processes in the millisecond time range. Stopped-flow measurements detected by circular dichroism (CD) or fluorescence spectroscopy give information on the rates of folding events. Quench-flow experiments utilize the differential rates of hydrogen-deuterium exchange of amide protons protected in parts of the structure that are folded early; protection of amides can be detected by mass spectrometry or proton nuclear magnetic resonance spectroscopy (NMR). In addition, apoMb forms an intermediate at equilibrium at pH ~ 4, which is sufficiently stable for it to be structurally characterized by solution methods such as CD, fluorescence and NMR spectroscopies, and the conformational ensembles formed in the presence of denaturing agents and low pH can be characterized as models for the unfolded states of the protein. Newer NMR techniques such as measurement of residual dipolar couplings in the various partly folded states, and relaxation dispersion measurements to probe invisible states present at low concentrations, have contributed to providing a detailed picture of the apomyoglobin folding pathway. The research summarized in this review was aimed at characterizing and comparing the equilibrium and kinetic intermediates both structurally and dynamically, as well as delineating the complete folding pathway at a residue-specific level, in order to answer the question “What is it about the amino acid sequence that causes each molecule in the unfolded protein ensemble to start folding, and, once started, to proceed towards the formation of the correctly folded three-dimensional structure?” PMID:28032989

Applying lean management principles to the creation of a postpartum hemorrhage care bundle.

PubMed

Faulkner, Beth

2013-10-01

A lean management process is a set of interventions, each of which creates value for the customer. Lean management is not a new concept, but is relatively new to health care. Postpartum hemorrhage (PPH) is the most common cause of maternal death worldwide in both developing and developed countries. We applied lean management principles as an innovative approach to improving outcomes in patients with PPH. Initial results using principles of lean management indicated significant improvements in response time and family-centered care. When applied rigorously and throughout the organization, lean principles can have a dramatic effect on productivity, cost and quality. © 2013 AWHONN.

Investigation of structural stability and elastic properties of CrH and MnH: A first principles study

NASA Astrophysics Data System (ADS)

Kanagaprabha, S.; Rajeswarapalanichamy, R.; Sudhapriyanga, G.; Murugan, A.; Santhosh, M.; Iyakutti, K.

2015-06-01

The structural and mechanical properties of CrH and MnH are investigated using first principles calculation based on density functional theory as implemented in VASP code with generalized gradient approximation. The calculated ground state properties are in good agreement with previous experimental and other theoretical results. A structural phase transition from NaCl to NiAs phase at a pressure of 76 GPa is predicted for both CrH and MnH.

Cognitive approaches to emotions.

PubMed

Oatley, Keith; Johnson-Laird, P N

2014-03-01

Cognitive approaches offer clear links between how emotions are thought about in everyday life and how they are investigated psychologically. Cognitive researchers have focused on how emotions are caused when events or other people affect concerns and on how emotions influence processes such as reasoning, memory, and attention. Three representative cognitive theories of emotion continue to develop productively: the action-readiness theory, the core-affect theory, and the communicative theory. Some principles are common to them and divergences can be resolved by future research. Recent explanations have included how emotions structure social relationships, how they function in psychological illnesses, and how they are central to music and fiction. Copyright © 2013 Elsevier Ltd. All rights reserved.

Branching angles of pyramidal cell dendrites follow common geometrical design principles in different cortical areas.

PubMed

Bielza, Concha; Benavides-Piccione, Ruth; López-Cruz, Pedro; Larrañaga, Pedro; DeFelipe, Javier

2014-08-01

Unraveling pyramidal cell structure is crucial to understanding cortical circuit computations. Although it is well known that pyramidal cell branching structure differs in the various cortical areas, the principles that determine the geometric shapes of these cells are not fully understood. Here we analyzed and modeled with a von Mises distribution the branching angles in 3D reconstructed basal dendritic arbors of hundreds of intracellularly injected cortical pyramidal cells in seven different cortical regions of the frontal, parietal, and occipital cortex of the mouse. We found that, despite the differences in the structure of the pyramidal cells in these distinct functional and cytoarchitectonic cortical areas, there are common design principles that govern the geometry of dendritic branching angles of pyramidal cells in all cortical areas.

Branching angles of pyramidal cell dendrites follow common geometrical design principles in different cortical areas

PubMed Central

Bielza, Concha; Benavides-Piccione, Ruth; López-Cruz, Pedro; Larrañaga, Pedro; DeFelipe, Javier

2014-01-01

Unraveling pyramidal cell structure is crucial to understanding cortical circuit computations. Although it is well known that pyramidal cell branching structure differs in the various cortical areas, the principles that determine the geometric shapes of these cells are not fully understood. Here we analyzed and modeled with a von Mises distribution the branching angles in 3D reconstructed basal dendritic arbors of hundreds of intracellularly injected cortical pyramidal cells in seven different cortical regions of the frontal, parietal, and occipital cortex of the mouse. We found that, despite the differences in the structure of the pyramidal cells in these distinct functional and cytoarchitectonic cortical areas, there are common design principles that govern the geometry of dendritic branching angles of pyramidal cells in all cortical areas. PMID:25081193

Exchange-Hole Dipole Dispersion Model for Accurate Energy Ranking in Molecular Crystal Structure Prediction.

PubMed

Whittleton, Sarah R; Otero-de-la-Roza, A; Johnson, Erin R

2017-02-14

Accurate energy ranking is a key facet to the problem of first-principles crystal-structure prediction (CSP) of molecular crystals. This work presents a systematic assessment of B86bPBE-XDM, a semilocal density functional combined with the exchange-hole dipole moment (XDM) dispersion model, for energy ranking using 14 compounds from the first five CSP blind tests. Specifically, the set of crystals studied comprises 11 rigid, planar compounds and 3 co-crystals. The experimental structure was correctly identified as the lowest in lattice energy for 12 of the 14 total crystals. One of the exceptions is 4-hydroxythiophene-2-carbonitrile, for which the experimental structure was correctly identified once a quasi-harmonic estimate of the vibrational free-energy contribution was included, evidencing the occasional importance of thermal corrections for accurate energy ranking. The other exception is an organic salt, where charge-transfer error (also called delocalization error) is expected to cause the base density functional to be unreliable. Provided the choice of base density functional is appropriate and an estimate of temperature effects is used, XDM-corrected density-functional theory is highly reliable for the energetic ranking of competing crystal structures.

TRIZ theory in NEA photocathode preparation system

NASA Astrophysics Data System (ADS)

Qiao, Jianliang; Huang, Dayong; Li, Xiangjiang; Gao, Youtang

2016-09-01

The solutions to the engineering problems were provided according to the innovation principle based on the theory of TRIZ. The ultra high vacuum test and evaluation system for the preparation of negative electron affinity (NEA) photocathode has the characteristics of complex structure and powerful functions. Segmentation principle, advance function principle, curved surface principle, dynamic characteristics principle and nested principle adopted by the design of ultra high vacuum test and evaluation system for cathode preparation were analyzed. The applications of the physical contradiction and the substance-field analysis method of the theory of TRIZ in the cathode preparation ultra high vacuum test and evaluation system were discussed.

Silicon as a potential anode material for Li-ion batteries: where size, geometry and structure matter.

PubMed

Ashuri, Maziar; He, Qianran; Shaw, Leon L

2016-01-07

Silicon has attracted huge attention in the last decade because it has a theoretical capacity ∼10 times that of graphite. However, the practical application of Si is hindered by three major challenges: large volume expansion during cycling (∼300%), low electrical conductivity, and instability of the SEI layer caused by repeated volume changes of the Si material. Significant research efforts have been devoted to addressing these challenges, and significant breakthroughs have been made particularly in the last two years (2014 and 2015). In this review, we have focused on the principles of Si material design, novel synthesis methods to achieve such structural designs, and the synthesis-structure-performance relationships to enhance the properties of Si anodes. To provide a systematic overview of the Si material design strategies, we have grouped the design strategies into several categories: (i) particle-based structures (containing nanoparticles, solid core-shell structures, hollow core-shell structures, and yolk-shell structures), (ii) porous Si designs, (iii) nanowires, nanotubes and nanofibers, (iv) Si-based composites, and (v) unusual designs. Finally, our personal perspectives on outlook are offered with an aim to stimulate further discussion and ideas on the rational design of durable and high performance Si anodes for the next generation Li-ion batteries in the near future.

Analytical investigations of seismic responses for reinforced concrete bridge columns subjected to strong near-fault ground motion

NASA Astrophysics Data System (ADS)

Su, Chin-Kuo; Sung, Yu-Chi; Chang, Shuenn-Yih; Huang, Chao-Hsun

2007-09-01

Strong near-fault ground motion, usually caused by the fault-rupture and characterized by a pulse-like velocity-wave form, often causes dramatic instantaneous seismic energy (Jadhav and Jangid 2006). Some reinforced concrete (RC) bridge columns, even those built according to ductile design principles, were damaged in the 1999 Chi-Chi earthquake. Thus, it is very important to evaluate the seismic response of a RC bridge column to improve its seismic design and prevent future damage. Nonlinear time history analysis using step-by-step integration is capable of tracing the dynamic response of a structure during the entire vibration period and is able to accommodate the pulsing wave form. However, the accuracy of the numerical results is very sensitive to the modeling of the nonlinear load-deformation relationship of the structural member. FEMA 273 and ATC-40 provide the modeling parameters for structural nonlinear analyses of RC beams and RC columns. They use three parameters to define the plastic rotation angles and a residual strength ratio to describe the nonlinear load-deformation relationship of an RC member. Structural nonlinear analyses are performed based on these parameters. This method provides a convenient way to obtain the nonlinear seismic responses of RC structures. However, the accuracy of the numerical solutions might be further improved. For this purpose, results from a previous study on modeling of the static pushover analyses for RC bridge columns (Sung et al. 2005) is adopted for the nonlinear time history analysis presented herein to evaluate the structural responses excited by a near-fault ground motion. To ensure the reliability of this approach, the numerical results were compared to experimental results. The results confirm that the proposed approach is valid.

Impact of documentation errors on accuracy of cause of death coding in an educational hospital in Southern Iran.

PubMed

Haghighi, Mohammad Hosein Hayavi; Dehghani, Mohammad; Teshnizi, Saeid Hoseini; Mahmoodi, Hamid

2014-01-01

Accurate cause of death coding leads to organised and usable death information but there are some factors that influence documentation on death certificates and therefore affect the coding. We reviewed the role of documentation errors on the accuracy of death coding at Shahid Mohammadi Hospital (SMH), Bandar Abbas, Iran. We studied the death certificates of all deceased patients in SMH from October 2010 to March 2011. Researchers determined and coded the underlying cause of death on the death certificates according to the guidelines issued by the World Health Organization in Volume 2 of the International Statistical Classification of Diseases and Health Related Problems-10th revision (ICD-10). Necessary ICD coding rules (such as the General Principle, Rules 1-3, the modification rules and other instructions about death coding) were applied to select the underlying cause of death on each certificate. Demographic details and documentation errors were then extracted. Data were analysed with descriptive statistics and chi square tests. The accuracy rate of causes of death coding was 51.7%, demonstrating a statistically significant relationship (p=.001) with major errors but not such a relationship with minor errors. Factors that result in poor quality of Cause of Death coding in SMH are lack of coder training, documentation errors and the undesirable structure of death certificates.

Perspective: Role of structure prediction in materials discovery and design

NASA Astrophysics Data System (ADS)

Needs, Richard J.; Pickard, Chris J.

2016-05-01

Materials informatics owes much to bioinformatics and the Materials Genome Initiative has been inspired by the Human Genome Project. But there is more to bioinformatics than genomes, and the same is true for materials informatics. Here we describe the rapidly expanding role of searching for structures of materials using first-principles electronic-structure methods. Structure searching has played an important part in unraveling structures of dense hydrogen and in identifying the record-high-temperature superconducting component in hydrogen sulfide at high pressures. We suggest that first-principles structure searching has already demonstrated its ability to determine structures of a wide range of materials and that it will play a central and increasing part in materials discovery and design.

Site-specific electronic structure analysis by channeling EELS and first-principles calculations.

PubMed

Tatsumi, Kazuyoshi; Muto, Shunsuke; Yamamoto, Yu; Ikeno, Hirokazu; Yoshioka, Satoru; Tanaka, Isao

2006-01-01

Site-specific electronic structures were investigated by electron energy loss spectroscopy (EELS) under electron channeling conditions. The Al-K and Mn-L(2,3) electron energy loss near-edge structure (ELNES) of, respectively, NiAl2O4 and Mn3O4 were measured. Deconvolution of the raw spectra with the instrumental resolution function restored the blunt and hidden fine features, which allowed us to interpret the experimental spectral features by comparing with theoretical spectra obtained by first-principles calculations. The present method successfully revealed the electronic structures specific to the differently coordinated cationic sites.

Principles of the Unification of Our Agency

ERIC Educational Resources Information Center

Roth, Klas

2011-01-01

Do we need principles of the unification of our agency, our mode of acting? Immanuel Kant and Christine Korsgaard argue that the reflective structure of our mind forces us to have some conception of ourselves, others and the world--including our agency--and that it is through will and reason, and in particular principles of our agency, that we…

An ancient rule for constructing dodecagonal quasiperiodic patterns

NASA Astrophysics Data System (ADS)

Ajlouni, Rima

2017-02-01

The discovery of complex dodecagonal patterns in historical Islamic architecture is generating a renewed interest into understanding the mathematical principles of traditional Islamic geometry. By employing a compass and a straightedge, ancient craftsmen utilized consistent design principles that allowed for diverse geometric expressions to be realized throughout the ancient world. Derived from these principles, a global multi-level structural model is proposed that provides a general guiding principle for constructing a wide variety of infinite dodecagon-based quasiperiodic patterns.

Investigation 8th Grade Students Secondary School Cognitive Structure about Principles of Ataturk through Word Association Test

ERIC Educational Resources Information Center

Akman, Ozkan; Koçoglu, Erol

2016-01-01

The purpose of this study is to present the connections between the concepts in perception and cognitive structures of secondary school 8th grade students for principles of Ataturk. Word association test is used in data collection. The number of the total participants in this research is 190. A frequency table is formed for the data obtained in…

Physical Principles of Discrete Hierarchies Formation in Protein Macromolecules

NASA Astrophysics Data System (ADS)

Malyshko, E. V.; Tverdislov, V. A.

2017-11-01

A model for chiral periodicity with alternating chiral sense in hierarchies of protein and nucleic acid structures is proposed and substantiated. Regular alternation of the chirality sense is revealed in transitions from the lowest to higher levels of structural-functional organization in proteins where it is L-D-L-D. The stratification principle combines the ideas of biomacromolecules folding and molecular biological machines.

Size variability of the unit building block of peripheral light-harvesting antennas as a strategy for effective functioning of antennas of variable size that is controlled in vivo by light intensity.

PubMed

Taisova, A S; Yakovlev, A G; Fetisova, Z G

2014-03-01

This work continuous a series of studies devoted to discovering principles of organization of natural antennas in photosynthetic microorganisms that generate in vivo large and highly effective light-harvesting structures. The largest antenna is observed in green photosynthesizing bacteria, which are able to grow over a wide range of light intensities and adapt to low intensities by increasing of size of peripheral BChl c/d/e antenna. However, increasing antenna size must inevitably cause structural changes needed to maintain high efficiency of its functioning. Our model calculations have demonstrated that aggregation of the light-harvesting antenna pigments represents one of the universal structural factors that optimize functioning of any antenna and manage antenna efficiency. If the degree of aggregation of antenna pigments is a variable parameter, then efficiency of the antenna increases with increasing size of a single aggregate of the antenna. This means that change in degree of pigment aggregation controlled by light-harvesting antenna size is biologically expedient. We showed in our previous work on the oligomeric chlorosomal BChl c superantenna of green bacteria of the Chloroflexaceae family that this principle of optimization of variable antenna structure, whose size is controlled by light intensity during growth of bacteria, is actually realized in vivo. Studies of this phenomenon are continued in the present work, expanding the number of studied biological materials and investigating optical linear and nonlinear spectra of chlorosomes having different structures. We show for oligomeric chlorosomal superantennas of green bacteria (from two different families, Chloroflexaceae and Oscillochloridaceae) that a single BChl c aggregate is of small size, and the degree of BChl c aggregation is a variable parameter, which is controlled by the size of the entire BChl c superantenna, and the latter, in turn, is controlled by light intensity in the course of cell culture growth.

Building blocks for correlated superconductors and magnets

DOE PAGES

Sarrao, J. L.; Ronning, F.; Bauer, E. D.; ...

2015-04-01

Recent efforts at Los Alamos to discover strongly correlated superconductors and hard ferromagnets are reviewed. While serendipity remains a principal engine of materials discovery, design principles and structural building blocks are beginning to emerge that hold potential for predictive discovery. In addition, successes over the last decade with the so-called “115” strongly correlated superconductors are summarized, and more recent efforts to translate these insights and principles to novel hard magnets are discussed. While true “materials by design” remains a distant aspiration, progress is being made in coupling empirical design principles to electronic structure simulation to accelerate and guide materials designmore » and synthesis.« less

Polymer separations by liquid interaction chromatography: principles - prospects - limitations.

PubMed

Radke, Wolfgang

2014-03-28

Most heterogeneities of polymers with respect to different structural features cannot be resolved by only size exclusion chromatography (SEC), the most frequently applied mode of polymer chromatography. Instead, methods of interaction chromatography became increasingly important. However, despite the increasing applications the principles and potential of polymer interaction chromatography are still often unknown to a large number of polymer scientists. The present review will explain the principles of the different modes of polymer chromatography. Based on selected examples it will be shown which separation techniques can be successfully applied for separations with respect to the different structural features of polymers. Copyright © 2013 Elsevier B.V. All rights reserved.

Socratic Knowledge, Christian Love, Confucian Virtue and Buddhist Emptiness: Guiding Principles for Education

ERIC Educational Resources Information Center

Clarken, Rodney

2010-01-01

Socrates' view of knowledge, Jesus' conception of love, Confucius' idea of virtue and Buddha's path of emptiness provide valuable insights and guiding principles to help us achieve a well-rounded education. Each of these individuals caused a transformation in the individual and collective lives of their followers and their respective societies…

When Good Evidence Goes Bad: The Weak Evidence Effect in Judgment and Decision-Making

ERIC Educational Resources Information Center

Fernbach, Philip M.; Darlow, Adam; Sloman, Steven A.

2011-01-01

An indispensable principle of rational thought is that positive evidence should increase belief. In this paper, we demonstrate that people routinely violate this principle when predicting an outcome from a weak cause. In Experiment 1 participants given weak positive evidence judged outcomes of public policy initiatives to be less likely than…

26 CFR 1.882-5 - Determination of interest deduction.

Code of Federal Regulations, 2013 CFR

2013-04-01

... differ from U.S. tax principles to a degree that will materially affect the value of taxpayer's worldwide... determine the value of an asset must not differ from U.S. tax principles to a degree that will materially... the reserves. The additions to the reserves under country X tax rules cause the value of Bank Z's...

26 CFR 1.882-5 - Determination of interest deduction.

Code of Federal Regulations, 2012 CFR

2012-04-01

... differ from U.S. tax principles to a degree that will materially affect the value of taxpayer's worldwide... determine the value of an asset must not differ from U.S. tax principles to a degree that will materially... the reserves. The additions to the reserves under country X tax rules cause the value of Bank Z's...

26 CFR 1.882-5 - Determination of interest deduction.

Code of Federal Regulations, 2011 CFR

2011-04-01

... differ from U.S. tax principles to a degree that will materially affect the value of taxpayer's worldwide... determine the value of an asset must not differ from U.S. tax principles to a degree that will materially... reserves. The additions to the reserves under country X tax rules cause the value of Bank Z's assets to...

26 CFR 1.882-5 - Determination of interest deduction.

Code of Federal Regulations, 2014 CFR

2014-04-01

... differ from U.S. tax principles to a degree that will materially affect the value of taxpayer's worldwide... determine the value of an asset must not differ from U.S. tax principles to a degree that will materially... the reserves. The additions to the reserves under country X tax rules cause the value of Bank Z's...

Greek classicism in living structure? Some deductive pathways in animal morphology.

PubMed

Zweers, G A

1985-01-01

Classical temples in ancient Greece show two deterministic illusionistic principles of architecture, which govern their functional design: geometric proportionalism and a set of illusion-strengthening rules in the proportionalism's "stochastic margin". Animal morphology, in its mechanistic-deductive revival, applies just one architectural principle, which is not always satisfactory. Whether a "Greek Classical" situation occurs in the architecture of living structure is to be investigated by extreme testing with deductive methods. Three deductive methods for explanation of living structure in animal morphology are proposed: the parts, the compromise, and the transformation deduction. The methods are based upon the systems concept for an organism, the flow chart for a functionalistic picture, and the network chart for a structuralistic picture, whereas the "optimal design" serves as the architectural principle for living structure. These methods show clearly the high explanatory power of deductive methods in morphology, but they also make one open end most explicit: neutral issues do exist. Full explanation of living structure asks for three entries: functional design within architectural and transformational constraints. The transformational constraint brings necessarily in a stochastic component: an at random variation being a sort of "free management space". This variation must be a variation from the deterministic principle of the optimal design, since any transformation requires space for plasticity in structure and action, and flexibility in role fulfilling. Nevertheless, finally the question comes up whether for animal structure a similar situation exists as in Greek Classical temples. This means that the at random variation, that is found when the optimal design is used to explain structure, comprises apart from a stochastic part also real deviations being yet another deterministic part. This deterministic part could be a set of rules that governs actualization in the "free management space".

Is the Precautionary Principle Really Incoherent?

PubMed

Boyer-Kassem, Thomas

2017-11-01

The Precautionary Principle has been an increasingly important principle in international treaties since the 1980s. Through varying formulations, it states that when an activity can lead to a catastrophe for human health or the environment, measures should be taken to prevent it even if the cause-and-effect relationship is not fully established scientifically. The Precautionary Principle has been critically discussed from many sides. This article concentrates on a theoretical argument by Peterson (2006) according to which the Precautionary Principle is incoherent with other desiderata of rational decision making, and thus cannot be used as a decision rule that selects an action among several ones. I claim here that Peterson's argument fails to establish the incoherence of the Precautionary Principle, by attacking three of its premises. I argue (i) that Peterson's treatment of uncertainties lacks generality, (ii) that his Archimedian condition is problematic for incommensurability reasons, and (iii) that his explication of the Precautionary Principle is not adequate. This leads me to conjecture that the Precautionary Principle can be envisaged as a coherent decision rule, again. © 2017 Society for Risk Analysis.

A Variational Principle for Reconstruction of Elastic Deformations in Shear Deformable Plates and Shells

NASA Technical Reports Server (NTRS)

Tessler, Alexander; Spangler, Jan L.

2003-01-01

A variational principle is formulated for the inverse problem of full-field reconstruction of three-dimensional plate/shell deformations from experimentally measured surface strains. The formulation is based upon the minimization of a least squares functional that uses the complete set of strain measures consistent with linear, first-order shear-deformation theory. The formulation, which accommodates for transverse shear deformation, is applicable for the analysis of thin and moderately thick plate and shell structures. The main benefit of the variational principle is that it is well suited for C(sup 0)-continuous displacement finite element discretizations, thus enabling the development of robust algorithms for application to complex civil and aeronautical structures. The methodology is especially aimed at the next generation of aerospace vehicles for use in real-time structural health monitoring systems.

Coupled fluid-structure interaction. Part 1: Theory. Part 2: Application

NASA Technical Reports Server (NTRS)

Felippa, Carlos A.; Ohayon, Roger

1991-01-01

A general three dimensional variational principle is obtained for the motion of an acoustic field enclosed in a rigid or flexible container by the method of canonical decomposition applied to a modified form of the wave equation in the displacement potential. The general principle is specialized to a mixed two-field principle that contains the fluid displacement potential and pressure as independent fields. Semidiscrete finite element equations of motion based on this principle are derived and sample cases are given.

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

Greitzer, Frank L.; Kuchar, Olga A.; Huston, Kristy A.

Serious games use entertainment principles, creativity, and technology to meet government or corporate training objectives, but these principles alone will not guarantee that the intended learning will occur. To be effective, serious games must incorporate sound cognitive, learning, and pedagogical principles into their design and structure. In this paper, we review cognitive principles that can be applied to improve the training effectiveness in serious games and we describe a process we used to design improvements for an existing game-based training application in the domain of cyber security education.

Structural electronic and mechanical properties of YM2 (M=Mn, Fe, Co) laves phase compounds: First principle calculations analyzed with datamining approach

NASA Astrophysics Data System (ADS)

Saidi, F.; Sebaa, N.; Mahmoudi, A.; Aourag, H.; Merad, G.; Dergal, M.

2018-06-01

We performed first-principle calculations to investigate structural, phase stability, electronic and mechanical properties for the Laves phases YM2 (M = Mn, Fe, Co) with C15, C14 and C36 structures. We used the density functional theory within the framework of both pseudo-potentials and plane wave basis using VASP (Vienna Ab Initio Software Package). The calculated equilibrium structural parameters are in accordance with available theoretical values. Mechanical properties were calculated, discussed, and analyzed with data mining approach in terms of structure stability. The results reveal that YCo2 is harder than YFe2 and YMn2.

Pressure-induced structural phase transformation and superconducting properties of titanium mononitride

NASA Astrophysics Data System (ADS)

Li, Qian; Guo, Yanan; Zhang, Miao; Ge, Xinlei

2018-03-01

In this work, we have systematically performed the first-principles structure search on titanium mononitride (TiN) within Crystal Structure AnaLYsis by Particle Swarm Optimization (CALYPSO) methodology at high pressures. Here, we have confirmed a phase transition from cubic rock-salt (fcc) phase to CsCl (bcc) phase of TiN at ∼348 GPa. Further simulations reveal that the bcc phase is dynamically stable, and could be synthesized experimentally in principle. The calculated elastic anisotropy decreases with the phase transformation from fcc to bcc structure under high pressures, and the material changes from ductile to brittle simultaneously. Moreover, we found that both structures are superconductive with the superconducting critical temperature of 2-12 K.

Multigrid based First-Principles Molecular Dynamics

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

Fattebert, Jean-Luc; Osei-Kuffuor, Daniel; Dunn, Ian

2017-06-01

MGmol ls a First-Principles Molecular Dynamics code. It relies on the Born-Oppenheimer approximation and models the electronic structure using Density Functional Theory, either LDA or PBE. Norm-conserving pseudopotentials are used to model atomic cores.

Novel Natural Convection Heat Sink Design Concepts From First Principles

DTIC Science & Technology

2016-06-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited NOVEL NATURAL ...COVERED Master’s Thesis 4. TITLE AND SUBTITLE NOVEL NATURAL CONVECTION HEAT SINK DESIGN CONCEPTS FROM FIRST PRINCIPLES 5. FUNDING NUMBERS 6...geometric structures that incorporate the principles of the stack effect to improve the heat transfer capability of a heat sink under natural convection

Optimizing the discovery organization for innovation.

PubMed

Sams-Dodd, Frank

2005-08-01

Strategic management is the process of adapting organizational structure and management principles to fit the strategic goal of the business unit. The pharmaceutical industry has generally been expert at optimizing its organizations for drug development, but has rarely implemented different structures for the early discovery process, where the objective is innovation and the transformation of innovation into drug projects. Here, a set of strategic management methods is proposed, covering team composition, organizational structure, management principles and portfolio management, which are designed to increase the level of innovation in the early drug discovery process.

A comparative first-principles study of structural and electronic properties among memantine, amantadine and rimantadine

NASA Astrophysics Data System (ADS)

Middleton, Kirsten; Zhang, G. P.; Nichols, Michael R.; George, Thomas F.

2012-05-01

Memantine, amantadine and rimantadine are structurally derived from the same diamondoid, adamantane. These derivatives demonstrate therapeutic efficacy in human diseases: memantine for Alzheimer's disease and amantadine and rimantadine for influenza. In order to better understand some of the properties that distinguish these three compounds, we conduct first-principles calculations on their structure and electronic properties. Our results indicate that protonation has a significant effect on the dipole moment, where the dipole moment in protonated memantine is over eight times larger than in the deprotonated form.

Confirmation of a de novo structure prediction for an atomically precise monolayer-coated silver nanoparticle

PubMed Central

Conn, Brian E.; Atnagulov, Aydar; Yoon, Bokwon; Barnett, Robert N.; Landman, Uzi; Bigioni, Terry P.

2016-01-01

Fathoming the principles underpinning the structures of monolayer-coated molecular metal nanoparticles remains an enduring challenge. Notwithstanding recent x-ray determinations, coveted veritable de novo structural predictions are scarce. Building on recent syntheses and de novo structure predictions of M3AuxAg17−x(TBBT)12, where M is a countercation, x = 0 or 1, and TBBT is 4-tert-butylbenzenethiol, we report an x-ray–determined structure that authenticates an a priori prediction and, in conjunction with first-principles theoretical analysis, lends force to the underlying forecasting methodology. The predicted and verified Ag(SR)3 monomer, together with the recently discovered Ag2(SR)5 dimer and Ag3(SR)6 trimer, establishes a family of unique mount motifs for silver thiolate nanoparticles, expanding knowledge beyond the earlier-known Au-S staples in thiol-capped gold nanoclusters. These findings demonstrate key principles underlying ligand-shell anchoring to the metal core, as well as unique T-like benzene dimer and cyclic benzene trimer ligand bundling configurations, opening vistas for rational design of metal and alloy nanoparticles. PMID:28138537

Local Telephone Costs and the Design of Rate Structures,

DTIC Science & Technology

1981-05-01

guide the setting of prices for the multi-product regulated firm. Economic effi- ciency can be increased by designing rate structures that incorporate the... basic principles developed from this theory. These principles call for provisionally pricing each of the firm’s outputs at its marginal cost, testing...rule--prices are increased above marginal costs in inverse proportion to the individual price elasticities of demand. This paper applies ratemaking

First principle study of structural, electronic and fermi surface properties of aluminum praseodymium

NASA Astrophysics Data System (ADS)

Shugani, Mani; Aynyas, Mahendra; Sanyal, S. P.

2018-05-01

We present a structural, Electronic and Fermi surface properties of Aluminum Praseodymium (AlPr) using First-principles density functional calculation by using full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA). The ground state properties along with electronic and Fermi surface properties are studied. It is found that AlPr is metallic and the bonding between Al and Pr is covalent.

On the relationship between cell cycle analysis with ergodic principles and age-structured cell population models.

PubMed

Kuritz, K; Stöhr, D; Pollak, N; Allgöwer, F

2017-02-07

Cyclic processes, in particular the cell cycle, are of great importance in cell biology. Continued improvement in cell population analysis methods like fluorescence microscopy, flow cytometry, CyTOF or single-cell omics made mathematical methods based on ergodic principles a powerful tool in studying these processes. In this paper, we establish the relationship between cell cycle analysis with ergodic principles and age structured population models. To this end, we describe the progression of a single cell through the cell cycle by a stochastic differential equation on a one dimensional manifold in the high dimensional dataspace of cell cycle markers. Given the assumption that the cell population is in a steady state, we derive transformation rules which transform the number density on the manifold to the steady state number density of age structured population models. Our theory facilitates the study of cell cycle dependent processes including local molecular events, cell death and cell division from high dimensional "snapshot" data. Ergodic analysis can in general be applied to every process that exhibits a steady state distribution. By combining ergodic analysis with age structured population models we furthermore provide the theoretic basis for extensions of ergodic principles to distribution that deviate from their steady state. Copyright © 2016 Elsevier Ltd. All rights reserved.

Speech therapy for errors secondary to cleft palate and velopharyngeal dysfunction.

PubMed

Kummer, Ann W

2011-05-01

Individuals with a history of cleft lip/palate or velopharyngeal dysfunction may demonstrate any combination of speech sound errors, hypernasality, and nasal emission. Speech sound distortion can also occur due to other structural anomalies, including malocclusion. Whenever there are structural anomalies, speech can be affected by obligatory distortions or compensatory errors. Obligatory distortions (including hypernasality due to velopharyngeal insufficiency) are caused by abnormal structure and not by abnormal function. Therefore, surgery or other forms of physical management are needed for correction. In contrast, speech therapy is indicated for compensatory articulation productions where articulation placement is changed in response to the abnormal structure. Speech therapy is much more effective if it is done after normalization of the structure. When speech therapy is appropriate, the techniques involve methods to change articulation placement using standard articulation therapy principles. Oral-motor exercises, including the use of blowing and sucking, are never indicated to improve velopharyngeal function. The purpose of this article is to provide information regarding when speech therapy is appropriate for individuals with a history of cleft palate or other structural anomalies and when physical management is needed. In addition, some specific therapy techniques are offered for the elimination of common compensatory articulation productions. © Thieme Medical Publishers.

Causal discovery and inference: concepts and recent methodological advances.

PubMed

Spirtes, Peter; Zhang, Kun

This paper aims to give a broad coverage of central concepts and principles involved in automated causal inference and emerging approaches to causal discovery from i.i.d data and from time series. After reviewing concepts including manipulations, causal models, sample predictive modeling, causal predictive modeling, and structural equation models, we present the constraint-based approach to causal discovery, which relies on the conditional independence relationships in the data, and discuss the assumptions underlying its validity. We then focus on causal discovery based on structural equations models, in which a key issue is the identifiability of the causal structure implied by appropriately defined structural equation models: in the two-variable case, under what conditions (and why) is the causal direction between the two variables identifiable? We show that the independence between the error term and causes, together with appropriate structural constraints on the structural equation, makes it possible. Next, we report some recent advances in causal discovery from time series. Assuming that the causal relations are linear with nonGaussian noise, we mention two problems which are traditionally difficult to solve, namely causal discovery from subsampled data and that in the presence of confounding time series. Finally, we list a number of open questions in the field of causal discovery and inference.

The structural, electronic and optical properties of Au-ZnO interface structure from the first-principles calculation

NASA Astrophysics Data System (ADS)

Huo, Jin-Rong; Li, Lu; Cheng, Hai-Xia; Wang, Xiao-Xu; Zhang, Guo-Hua; Qian, Ping

2018-03-01

The interface structure, electronic and optical properties of Au-ZnO are studied using the first-principles calculation based on density functional theory (DFT). Given the interfacial distance, bonding configurations and terminated surface, we built the optimal interface structure and calculated the electronic and optical properties of the interface. The total density of states, partial electronic density of states, electric charge density and atomic populations (Mulliken) are also displayed. The results show that the electrons converge at O atoms at the interface, leading to a stronger binding of interfaces and thereby affecting the optical properties of interface structures. In addition, we present the binding energies of different interface structures. When the interface structure of Au-ZnO gets changed, furthermore, varying optical properties are exhibited.

Therapeutic principles of primaquine against relapse of Plasmodium vivax malaria

NASA Astrophysics Data System (ADS)

Baird, J. K.

2018-03-01

Plasmodium vivax causes tens of millions of clinical attacks annually all across the malarious globe. Unlike the other major cause of human malaria, Plasmodium falciparum, P. vivax places dormant stages called hypnozoites into the human liver that later awaken and provoke multiple clinical attacks in the weeks, months, and few years following the infectious anopheline mosquito bite. The only available treatment to prevent those recurrent attacks is primaquine (hypnozoitocide), and it must be administered with the drugs applied to end the acute attack (blood schizontocides). This paper reviews the therapeutic principles of applying primaquine to achieve radical cure of acute vivax malaria.

Structure and properties of microporous titanosilicate determined by first-principles calculations

NASA Astrophysics Data System (ADS)

Ching, W. Y.; Xu, Yong-Nian; Gu, Zong-Quan

1996-12-01

The structure of EST-10, a member of synthetic microporous titanosilicates, was recently determined by an ingenious combination of experimental and simulational techniques. However, the locations of the alkali atoms in the framework remain elusive and its electronic structure is totally unknown. Based on first-principles local density calculations, the possible locations of the alkali atoms are identified and its electronic structure and bonding fully elucidated. ETS-10 is a semiconductor with a direct band gap of 2.33 eV. The Na atoms are likely to locate inside the seven-member ring pore adjacent to the one-dimensional Ti-O-Ti-O- chain.

Evaluation of aerodynamic characteristics of a coupled fluid-structure system using generalized Bernoulli’s principle: An application to vocal folds vibration

PubMed Central

Zhang, Lucy T.; Yang, Jubiao

2017-01-01

In this work we explore the aerodynamics flow characteristics of a coupled fluid-structure interaction system using a generalized Bernoulli equation derived directly from the Cauchy momentum equations. Unlike the conventional Bernoulli equation where incompressible, inviscid, and steady flow conditions are assumed, this generalized Bernoulli equation includes the contributions from compressibility, viscous, and unsteadiness, which could be essential in defining aerodynamic characteristics. The application of the derived Bernoulli’s principle is on a fully-coupled fluid-structure interaction simulation of the vocal folds vibration. The coupled system is simulated using the immersed finite element method where compressible Navier-Stokes equations are used to describe the air and an elastic pliable structure to describe the vocal fold. The vibration of the vocal fold works to open and close the glottal flow. The aerodynamics flow characteristics are evaluated using the derived Bernoulli’s principles for a vibration cycle in a carefully partitioned control volume based on the moving structure. The results agree very well to experimental observations, which validate the strategy and its use in other types of flow characteristics that involve coupled fluid-structure interactions. PMID:29527541

Evaluation of aerodynamic characteristics of a coupled fluid-structure system using generalized Bernoulli's principle: An application to vocal folds vibration.

PubMed

Zhang, Lucy T; Yang, Jubiao

2016-12-01

In this work we explore the aerodynamics flow characteristics of a coupled fluid-structure interaction system using a generalized Bernoulli equation derived directly from the Cauchy momentum equations. Unlike the conventional Bernoulli equation where incompressible, inviscid, and steady flow conditions are assumed, this generalized Bernoulli equation includes the contributions from compressibility, viscous, and unsteadiness, which could be essential in defining aerodynamic characteristics. The application of the derived Bernoulli's principle is on a fully-coupled fluid-structure interaction simulation of the vocal folds vibration. The coupled system is simulated using the immersed finite element method where compressible Navier-Stokes equations are used to describe the air and an elastic pliable structure to describe the vocal fold. The vibration of the vocal fold works to open and close the glottal flow. The aerodynamics flow characteristics are evaluated using the derived Bernoulli's principles for a vibration cycle in a carefully partitioned control volume based on the moving structure. The results agree very well to experimental observations, which validate the strategy and its use in other types of flow characteristics that involve coupled fluid-structure interactions.

An ambiguity principle for assigning protein structural domains.

PubMed

Postic, Guillaume; Ghouzam, Yassine; Chebrek, Romain; Gelly, Jean-Christophe

2017-01-01

Ambiguity is the quality of being open to several interpretations. For an image, it arises when the contained elements can be delimited in two or more distinct ways, which may cause confusion. We postulate that it also applies to the analysis of protein three-dimensional structure, which consists in dividing the molecule into subunits called domains. Because different definitions of what constitutes a domain can be used to partition a given structure, the same protein may have different but equally valid domain annotations. However, knowledge and experience generally displace our ability to accept more than one way to decompose the structure of an object-in this case, a protein. This human bias in structure analysis is particularly harmful because it leads to ignoring potential avenues of research. We present an automated method capable of producing multiple alternative decompositions of protein structure (web server and source code available at www.dsimb.inserm.fr/sword/). Our innovative algorithm assigns structural domains through the hierarchical merging of protein units, which are evolutionarily preserved substructures that describe protein architecture at an intermediate level, between domain and secondary structure. To validate the use of these protein units for decomposing protein structures into domains, we set up an extensive benchmark made of expert annotations of structural domains and including state-of-the-art domain parsing algorithms. The relevance of our "multipartitioning" approach is shown through numerous examples of applications covering protein function, evolution, folding, and structure prediction. Finally, we introduce a measure for the structural ambiguity of protein molecules.

The Effects of Social Cue Principles on Cognitive Load, Situational Interest, Motivation, and Achievement in Pedagogical Agent Multimedia Learning

ERIC Educational Resources Information Center

Park, Sanghoon

2015-01-01

Animated pedagogical agents have become popular in multimedia learning with combined delivery of verbal and non-verbal forms of information. In order to reduce unnecessary cognitive load caused by such multiple forms of information and also to foster generative cognitive processing, multimedia design principles with social cues are suggested…

Some Analogies of the Banach Contraction Principle in Fuzzy Modular Spaces

PubMed Central

Wongkum, Kittipong; Chaipunya, Parin; Kumam, Poom

2013-01-01

We established some theorems under the aim of deriving variants of the Banach contraction principle, using the classes of inner contractions and outer contractions, on the structure of fuzzy modular spaces. PMID:23766681

Clinical ethics and values: how do norms evolve from practice?

PubMed

Spranzi, Marta

2013-02-01

Bioethics laws in France have just undergone a revision process. The bioethics debate is often cast in terms of ethical principles and norms resisting emerging social and technological practices. This leads to the expression of confrontational attitudes based on widely differing interpretations of the same principles and values, and ultimately results in a deadlock. In this paper I would like to argue that focusing on values, as opposed to norms and principles, provides an interesting perspective on the evolution of norms. As Joseph Raz has convincingly argued, "life-building" values and practices are closely intertwined. Precisely because values have a more indeterminate meaning than norms, they can be cited as reasons for action by concerned stakeholders, and thus can help us understand how controversial practices, e.g. surrogate motherhood, can be justified. Finally, norms evolve when the interpretations of the relevant values shift and cause a change in the presumptions implicit in the norms. Thus, norms are not a prerequisite of the ethical solution of practical dilemmas, but rather the outcome of the decision-making process itself. Struggling to reach the right decision in controversial clinical ethics situations indirectly causes social and moral values to change and principles to be understood differently.

Endogenous patient responses and the consistency principle in cost-effectiveness analysis.

PubMed

Liu, Liqun; Rettenmaier, Andrew J; Saving, Thomas R

2012-01-01

In addition to incurring direct treatment costs and generating direct health benefits that improve longevity and/or health-related quality of life, medical interventions often have further or "unrelated" financial and health impacts, raising the issue of what costs and effects should be included in calculating the cost-effectiveness ratio of an intervention. The "consistency principle" in medical cost-effectiveness analysis (CEA) requires that one include both the cost and the utility benefit of a change (in medical expenditures, consumption, or leisure) caused by an intervention or neither of them. By distinguishing between exogenous changes directly brought about by an intervention and endogenous patient responses to the exogenous changes, and within a lifetime utility maximization framework, this article addresses 2 questions related to the consistency principle: 1) how to choose among alternative internally consistent exclusion/inclusion rules, and 2) what to do with survival consumption costs and earnings. It finds that, for an endogenous change, excluding or including both the cost and the utility benefit of the change does not alter cost-effectiveness results. Further, in agreement with the consistency principle, welfare maximization implies that consumption costs and earnings during the extended life directly caused by an intervention should be included in CEA.

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

Zeng, Li; Jacobsen, Stein B., E-mail: astrozeng@gmail.com, E-mail: jacobsen@neodymium.harvard.edu

In the past few years, the number of confirmed planets has grown above 2000. It is clear that they represent a diversity of structures not seen in our own solar system. In addition to very detailed interior modeling, it is valuable to have a simple analytical framework for describing planetary structures. The variational principle is a fundamental principle in physics, entailing that a physical system follows the trajectory, which minimizes its action. It is alternative to the differential equation formulation of a physical system. Applying the variational principle to the planetary interior can beautifully summarize the set of differential equationsmore » into one, which provides us some insight into the problem. From this principle, a universal mass–radius relation, an estimate of the error propagation from the equation of state to the mass–radius relation, and a form of the virial theorem applicable to planetary interiors are derived.« less

Nondestructive methods of integrating energy harvesting systems with structures

NASA Astrophysics Data System (ADS)

Inamdar, Sumedh; Zimowski, Krystian; Crawford, Richard; Wood, Kristin; Jensen, Dan

2012-04-01

Designing an attachment structure that is both novel and meets the system requirements can be a difficult task especially for inexperienced designers. This paper presents a design methodology for concept generation of a "parent/child" attachment system. The "child" is broadly defined as any device, part, or subsystem that will attach to any existing system, part, or device called the "parent." An inductive research process was used to study a variety of products, patents, and biological examples that exemplified the parent/child system. Common traits among these products were found and categorized as attachment principles in three different domains: mechanical, material, and field. The attachment principles within the mechanical domain and accompanying examples are the focus of this paper. As an example of the method, a case study of generating concepts for a bridge mounted wind energy harvester using the mechanical attachment principles derived from the methodology and TRIZ principles derived from Altshuller's matrix of contradictions is presented.

Using in-cell SHAPE-Seq and simulations to probe structure-function design principles of RNA transcriptional regulators.

PubMed

Takahashi, Melissa K; Watters, Kyle E; Gasper, Paul M; Abbott, Timothy R; Carlson, Paul D; Chen, Alan A; Lucks, Julius B

2016-06-01

Antisense RNA-mediated transcriptional regulators are powerful tools for controlling gene expression and creating synthetic gene networks. RNA transcriptional repressors derived from natural mechanisms called attenuators are particularly versatile, though their mechanistic complexity has made them difficult to engineer. Here we identify a new structure-function design principle for attenuators that enables the forward engineering of new RNA transcriptional repressors. Using in-cell SHAPE-Seq to characterize the structures of attenuator variants within Escherichia coli, we show that attenuator hairpins that facilitate interaction with antisense RNAs require interior loops for proper function. Molecular dynamics simulations of these attenuator variants suggest these interior loops impart structural flexibility. We further observe hairpin flexibility in the cellular structures of natural RNA mechanisms that use antisense RNA interactions to repress translation, confirming earlier results from in vitro studies. Finally, we design new transcriptional attenuators in silico using an interior loop as a structural requirement and show that they function as desired in vivo. This work establishes interior loops as an important structural element for designing synthetic RNA gene regulators. We anticipate that the coupling of experimental measurement of cellular RNA structure and function with computational modeling will enable rapid discovery of structure-function design principles for a diverse array of natural and synthetic RNA regulators. © 2016 Takahashi et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

Numerical and experimental study of bistable plates for morphing structures

NASA Astrophysics Data System (ADS)

Nicassio, F.; Scarselli, G.; Avanzini, G.; Del Core, G.

2017-04-01

This study is concerned with the activation energy threshold of bistable composite plates in order to tailor a bistable system for specific aeronautical applications. The aim is to explore potential configurations of the bistable plates and their dynamic behavior for designing novel morphing structure suitable for aerodynamic surfaces and, as a possible further application, for power harvesters. Bistable laminates have two stable mechanical shapes that can withstand aerodynamic loads without additional constraint forces or locking mechanisms. This kind of structures, when properly loaded, snap-through from one stable configuration to another, causing large strains that can also be used for power harvesting scopes. The transition between the stable states of the composite laminate can be triggered, in principle, simply by aerodynamic loads (pilot, disturbance or passive inputs) without the need of servo-activated control systems. Both numerical simulations based on Finite Element models and experimental testing based on different activating forcing spectra are used to validate this concept. The results show that dynamic activation of bistable plates depend on different parameters that need to be carefully managed for their use as aircraft passive wing flaps.

The compression dome concept: the restorative implications.

PubMed

Milicich, Graeme

2017-01-01

Evidence now supports the concept that the enamel on a tooth acts like a compression dome, much like the dome of a cathedral. With an overlying enamel compression dome, the underlying dentin is protected from damaging tensile forces. Disruption of a compression system leads to significant shifts in load pathways. The clinical restorative implications are significant and far-reaching. Cutting the wrong areas of a tooth exposes the underlying dentin to tensile forces that exceed natural design parameters. These forces lead to crack propagation, causing flexural pain and eventual fracture and loss of tooth structure. Improved understanding of the microanatomy of tooth structure and where it is safe to cut teeth has led to a revolution in dentistry that is known by several names, including microdentistry, minimally invasive dentistry, biomimetic dentistry, and bioemulation dentistry. These treatment concepts have developed due to a coalescence of principles of tooth microanatomy, material science, adhesive dentistry, and reinforcing techniques that, when applied together, will allow dentists to repair a compromised compression dome so that it more closely replicates the structure of the healthy tooth.

Segmental Isotopic Labeling of Proteins for Nuclear Magnetic Resonance

PubMed Central

Dongsheng, Liu; Xu, Rong; Cowburn, David

2009-01-01

Nuclear Magnetic Resonance (NMR) spectroscopy has emerged as one of the principle techniques of structural biology. It is not only a powerful method for elucidating the 3D structures under near physiological conditions, but also a convenient method for studying protein-ligand interactions and protein dynamics. A major drawback of macromolecular NMR is its size limitation caused by slower tumbling rates and greater complexity of the spectra as size increases. Segmental isotopic labeling allows specific segment(s) within a protein to be selectively examined by NMR thus significantly reducing the spectral complexity for large proteins and allowing a variety of solution-based NMR strategies to be applied. Two related approaches are generally used in the segmental isotopic labeling of proteins: expressed protein ligation and protein trans-splicing. Here we describe the methodology and recent application of expressed protein ligation and protein trans-splicing for NMR structural studies of proteins and protein complexes. We also describe the protocol used in our lab for the segmental isotopic labeling of a 50 kDa protein Csk (C-terminal Src Kinase) using expressed protein ligation methods. PMID:19632474

A Monitoring Method Based on FBG for Concrete Corrosion Cracking

PubMed Central

Mao, Jianghong; Xu, Fangyuan; Gao, Qian; Liu, Shenglin; Jin, Weiliang; Xu, Yidong

2016-01-01

Corrosion cracking of reinforced concrete caused by chloride salt is one of the main determinants of structure durability. Monitoring the entire process of concrete corrosion cracking is critical for assessing the remaining life of the structure and determining if maintenance is needed. Fiber Bragg Grating (FBG) sensing technology is extensively developed in photoelectric monitoring technology and has been used on many projects. FBG can detect the quasi-distribution of strain and temperature under corrosive environments, and thus it is suitable for monitoring reinforced concrete cracking. According to the mechanical principle that corrosion expansion is responsible for the reinforced concrete cracking, a package design of reinforced concrete cracking sensors based on FBG was proposed and investigated in this study. The corresponding relationship between the grating wavelength and strain was calibrated by an equal strength beam test. The effectiveness of the proposed method was verified by an electrically accelerated corrosion experiment. The fiber grating sensing technology was able to track the corrosion expansion and corrosion cracking in real time and provided data to inform decision-making for the maintenance and management of the engineering structure. PMID:27428972

A Monitoring Method Based on FBG for Concrete Corrosion Cracking.

PubMed

Mao, Jianghong; Xu, Fangyuan; Gao, Qian; Liu, Shenglin; Jin, Weiliang; Xu, Yidong

2016-07-14

Corrosion cracking of reinforced concrete caused by chloride salt is one of the main determinants of structure durability. Monitoring the entire process of concrete corrosion cracking is critical for assessing the remaining life of the structure and determining if maintenance is needed. Fiber Bragg Grating (FBG) sensing technology is extensively developed in photoelectric monitoring technology and has been used on many projects. FBG can detect the quasi-distribution of strain and temperature under corrosive environments, and thus it is suitable for monitoring reinforced concrete cracking. According to the mechanical principle that corrosion expansion is responsible for the reinforced concrete cracking, a package design of reinforced concrete cracking sensors based on FBG was proposed and investigated in this study. The corresponding relationship between the grating wavelength and strain was calibrated by an equal strength beam test. The effectiveness of the proposed method was verified by an electrically accelerated corrosion experiment. The fiber grating sensing technology was able to track the corrosion expansion and corrosion cracking in real time and provided data to inform decision-making for the maintenance and management of the engineering structure.

Making sense of the conflicting magic numbers in WSi{sub n} clusters

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

Abreu, Marissa Baddick; Reber, Arthur C.; Khanna, Shiv N.

2015-08-21

First principles studies on the geometric structure, stability, and electronic structure of WSi{sub n} clusters, n = 6-16, have been carried out to show that the observed differing “magic sizes” for WSi{sub n} clusters are associated with the nature of the growth processes. The WSi{sub 12} cluster, observed as a magic species in experiments reacting transition metal ions with silane, is not stable due to a filled shell of 18 electrons, as previously proposed, but due to its atomic structure that arrests further growth because of an endohedral transition metal site. In fact, it is found that all of thesemore » clusters, n = 6-16, have filled 5d shells except for WSi{sub 12}, which has a 5d{sup 8} configuration that is caused by crystal field splitting. The stability of WSi{sub 15}{sup +}, observed as highly stable in clusters generated by vaporizing silicon and metal carbonyls, is shown to be associated with a combination of geometric and electronic features. The findings are compared with previous results on CrSi{sub n} clusters.« less

Lyotropic chromonic liquid crystals as materials for optical and biosensing applications

NASA Astrophysics Data System (ADS)

Tortora, L.; Park, H.-S.; Antion, K.; Finotello, D.; Lavrentovich, O. D.

2007-02-01

Lyotropic chromonic liquid crystals (LCLCs) are formed by molecules with rigid polyaromatic cores and ionic groups at the periphery that form aggregates while in water. Most of the LCLCs are not toxic to the biological cells and can be used as an amplifying medium in real-time biosensors. The detector is based on the principle that the immune aggregates growing in the LCLC bulk trigger the director distortions. Self-assembly of LCLC molecules into oriented structures allows one to use them in various structured films. For example, layer-by-layer electrostatic deposition produces monomolecular layers and stacks of layers of LCLC with long-range in-plane orientational order which sets them apart from the standard Langmuir-Blodgett films. We demonstrate that divalent and multivalent salts as well as acidic and basic materials that alter pH of the LCLC water solutions, are drastically modifying the phase diagrams of LCLC, from shifting the phase transition temperatures by tens of degrees, to causing condensation of the LCLC aggregates into more compact structures, such as birefringent bundles or formation of a columnar hexagonal phase from the nematic phase.

First-Principles Investigation of Lithium Polysulfide Structure and Behavior in Solution

DOE PAGES

Kamphaus, Ethan P.; Balbuena, Perla B.

2017-09-07

We present the Lithium-Sulfur battery is a promising next generation energy storage technology that could meet the demands of modern society with a theoretical specific energy near 2500 W h kg -1. However, this battery chemistry faces unique problems such as the parasitic polysulfide shuttle reaction which hinders battery performance severely. This shuttle phenomenon is caused by solubilities of intermediate reaction products in the electrolyte during the reduction chemistry of the battery. With molecular simulation and computational chemistry tools, we studied the thermodynamics, solvation structure, and dynamics of the long-chain lithium polysulfide species Li 2S 6 and Li 2S 8more » in dimethoxyethane and 1,3-dioxolane to gain a deeper fundamental understanding of this process. We determined the structure of the 1st solvation shell for Li + as well as those of Li 2S 6, Li 2S 8 closed and Li 2S 8 linear in pure solvents and solvents with extra Li + added. Finally, the lithium polysulfide species were found not to favor dissociation and would most likely exist as fully lithiated species in solution.« less

First-Principles Investigation of Lithium Polysulfide Structure and Behavior in Solution

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

Kamphaus, Ethan P.; Balbuena, Perla B.

We present the Lithium-Sulfur battery is a promising next generation energy storage technology that could meet the demands of modern society with a theoretical specific energy near 2500 W h kg -1. However, this battery chemistry faces unique problems such as the parasitic polysulfide shuttle reaction which hinders battery performance severely. This shuttle phenomenon is caused by solubilities of intermediate reaction products in the electrolyte during the reduction chemistry of the battery. With molecular simulation and computational chemistry tools, we studied the thermodynamics, solvation structure, and dynamics of the long-chain lithium polysulfide species Li 2S 6 and Li 2S 8more » in dimethoxyethane and 1,3-dioxolane to gain a deeper fundamental understanding of this process. We determined the structure of the 1st solvation shell for Li + as well as those of Li 2S 6, Li 2S 8 closed and Li 2S 8 linear in pure solvents and solvents with extra Li + added. Finally, the lithium polysulfide species were found not to favor dissociation and would most likely exist as fully lithiated species in solution.« less

First-principles density functional theory (DFT) study of gold nanorod and its interaction with alkanethiol ligands.

PubMed

Hu, Hang; Reven, Linda; Rey, Alejandro

2013-10-17

The structure and mechanical properties of gold nanorods and their interactions with alkenthiolate self-assembled monolayers have been determined using a novel first-principle density functional theory simulation approach. The multifaceted, 1-dimensional, octagonal nanorod has alternate Au100 and Au110 surfaces. The structural optimization of the gold nanorods was performed with a mixed basis: the outermost layer of gold atoms used double-ζ plus polarization (DZP), the layer below used double-ζ (DZ), and the inner layers used single-ζ (SZ). The final structure compares favorably with simulations using DZP for all atoms. Phonon dispersion calculations and ab initio molecular dynamics (AIMD) were used to establish the dynamic and thermal stability of the system. From the AIMD simulations it was found that the nanorod system will undergo significant surface reconstruction at 300 K. In addition, when subjected to mechanical stress in the axial direction, the nanorod responds as an orthotropic material, with uniform expansion along the radial direction. The Young's moduli are 207 kbar in the axial direction and 631 kbar in the radial direction. The binding of alkanethiolates, ranging from methanethiol to pentanethiol, caused formation of surface point defects on the Au110 surfaces. On the Au100 surfaces, the defects occurred in the inner layer, creating a small surface island. These defects make positive and negative concavities on the gold nanorod surface, which helps the ligand to achieve a more stable state. The simulation results narrowed significant knowledge gaps on the alkanethiolate adsorption process and on their mutual interactions on gold nanorods. The mechanical characterization offers a new dimension to understand the physical chemistry of these complex nanoparticles.

Human factors in operations design

NASA Technical Reports Server (NTRS)

Chafin, R. L.

1982-01-01

The manner in which organizations develop their organizational structure is considered, taking into account an example in which the environment changes for an older organization. In such cases, it would be preferable to have some theoretical foundation on which to base the restructuring of the organization to meet new environmental needs. A description is given of a theoretic foundation based on the principles of Differentiation/Integration and Procedural/Knowledge based operations. The organizational design principle of Differentiation and Integration has been presented by Lawrence and Lorsch (1969). The differentiation/integration processes are related to the organizational structures presented in studies concerning NASA Deep Space Network (DSN) operations. The principles presented provide valuable tools for analyzing operations organization.

Requirements and principles for the implementation and construction of large-scale geographic information systems

NASA Technical Reports Server (NTRS)

Smith, Terence R.; Menon, Sudhakar; Star, Jeffrey L.; Estes, John E.

1987-01-01

This paper provides a brief survey of the history, structure and functions of 'traditional' geographic information systems (GIS), and then suggests a set of requirements that large-scale GIS should satisfy, together with a set of principles for their satisfaction. These principles, which include the systematic application of techniques from several subfields of computer science to the design and implementation of GIS and the integration of techniques from computer vision and image processing into standard GIS technology, are discussed in some detail. In particular, the paper provides a detailed discussion of questions relating to appropriate data models, data structures and computational procedures for the efficient storage, retrieval and analysis of spatially-indexed data.

Inertial Frames Without the Relativity Principle: Breaking Lorentz Symmetry

NASA Astrophysics Data System (ADS)

Baccetti, Valentina; Tate, Kyle; Visser, Matt

2015-01-01

We investigate inertial frames in the absence of Lorentz invariance, reconsidering the usual group structure implied by the relativity principle. We abandon the relativity principle, discarding the group structure for the transformations between inertial frames, while requiring these transformations to be at least linear (to preserve homogeneity). In theories with a preferred frame (aether), the set of transformations between inertial frames forms a groupoid/pseudogroup instead of a group, a characteristic essential to evading the von Ignatowsky theorems. In order to understand the dynamics, we also demonstrate that the transformation rules for energy and momentum are in general affine. We finally focus on one specific and compelling model implementing a minimalist violation of Lorentz invariance.

Bioinspired toughening mechanism: lesson from dentin.

PubMed

An, Bingbing; Zhang, Dongsheng

2015-07-09

Inspired by the unique microstructure of dentin, in which the hard peritubular dentin surrounding the dentin tubules is embedded in the soft intertubular dentin, we explore the crack propagation in the bioinspired materials with fracture process zone possessing a dentin-like microstructure, i.e. the composite structure consisting of a soft matrix and hard reinforcements with cylindrical voids. A micromechanical model under small-scale yielding conditions is developed, and numerical simulations are performed, showing that the rising resistant curve (R-curve) is observed for crack propagation caused by the plastic collapse of the intervoid ligaments in the fracture process zone. The dentin-like microstructure in the fracture process zone exhibits enhanced fracture toughness, compared with the case of voids embedded in the homogeneous soft matrix. Further computational simulations show that the dentin-like microstructure can retard void growth, thereby promoting fracture toughness. The typical fracture mechanism of the bioinspired materials with fracture process zone possessing the dentin-like structure is void by void growth, while it is the multiple void interaction in the case of voids in the homogeneous matrix. Based on the results, we propose a bioinspired material design principle, which is that the combination of a hard inner material encompassing voids and a soft outer material in the fracture process zone can give rise to exceptional fracture toughness, achieving damage tolerance. It is expected that the proposed design principle could shed new light on the development of novel man-made engineering materials.

Thermal Conductivity of Wurtzite Zinc-Oxide from First-Principles Lattice Dynamics - a Comparative Study with Gallium Nitride

NASA Astrophysics Data System (ADS)

Wu, Xufei; Lee, Jonghoon; Varshney, Vikas; Wohlwend, Jennifer L.; Roy, Ajit K.; Luo, Tengfei

2016-03-01

Wurtzite Zinc-Oxide (w-ZnO) is a wide bandgap semiconductor that holds promise in power electronics applications, where heat dissipation is of critical importance. However, large discrepancies exist in the literature on the thermal conductivity of w-ZnO. In this paper, we determine the thermal conductivity of w-ZnO using first-principles lattice dynamics and compare it to that of wurtzite Gallium-Nitride (w-GaN) - another important wide bandgap semiconductor with the same crystal structure and similar atomic masses as w-ZnO. However, the thermal conductivity values show large differences (400 W/mK of w-GaN vs. 50 W/mK of w-ZnO at room temperature). It is found that the much lower thermal conductivity of ZnO originates from the smaller phonon group velocities, larger three-phonon scattering phase space and larger anharmonicity. Compared to w-GaN, w-ZnO has a smaller frequency gap in phonon dispersion, which is responsible for the stronger anharmonic phonon scattering, and the weaker interatomic bonds in w-ZnO leads to smaller phonon group velocities. The thermal conductivity of w-ZnO also shows strong size effect with nano-sized grains or structures. The results from this work help identify the cause of large discrepancies in w-ZnO thermal conductivity and will provide in-depth understanding of phonon dynamics for the design of w-ZnO-based electronics.

Thermal Conductivity of Wurtzite Zinc-Oxide from First-Principles Lattice Dynamics – a Comparative Study with Gallium Nitride

PubMed Central

Wu, Xufei; Lee, Jonghoon; Varshney, Vikas; Wohlwend, Jennifer L.; Roy, Ajit K.; Luo, Tengfei

2016-01-01

Wurtzite Zinc-Oxide (w-ZnO) is a wide bandgap semiconductor that holds promise in power electronics applications, where heat dissipation is of critical importance. However, large discrepancies exist in the literature on the thermal conductivity of w-ZnO. In this paper, we determine the thermal conductivity of w-ZnO using first-principles lattice dynamics and compare it to that of wurtzite Gallium-Nitride (w-GaN) – another important wide bandgap semiconductor with the same crystal structure and similar atomic masses as w-ZnO. However, the thermal conductivity values show large differences (400 W/mK of w-GaN vs. 50 W/mK of w-ZnO at room temperature). It is found that the much lower thermal conductivity of ZnO originates from the smaller phonon group velocities, larger three-phonon scattering phase space and larger anharmonicity. Compared to w-GaN, w-ZnO has a smaller frequency gap in phonon dispersion, which is responsible for the stronger anharmonic phonon scattering, and the weaker interatomic bonds in w-ZnO leads to smaller phonon group velocities. The thermal conductivity of w-ZnO also shows strong size effect with nano-sized grains or structures. The results from this work help identify the cause of large discrepancies in w-ZnO thermal conductivity and will provide in-depth understanding of phonon dynamics for the design of w-ZnO-based electronics. PMID:26928396

First-principles study of strain effect on the formation and electronic structures of oxygen vacancy in SrFeO2

NASA Astrophysics Data System (ADS)

Wei, Zhang; Jie, Huang

2016-05-01

Motivated by recent experimental observations of metallic conduction in the quasi-two-dimensional SrFeO2, we study the epitaxial strain effect on the formation and electronic structures of oxygen vacancy (Vo) by first-principles calculations. The bulk SrFeO2 is found to have the G-type antiferromagnetic ordering (G-AFM) at zero strain, which agrees with the experiment. Under compressive strain the bulk SrFeO2 keeps the G-AFM and has the trend of Mott insulator-metal transition. Different from most of the previous similar work about the strain effect on Vo, both the tensile strain and the compressive strain enhance the Vo formation. It is found that the competitions between the band energies and the electrostatic interactions are the dominant mechanisms in determining the Vo formation. We confirm that the Vo in SrFeO2 would induce the n-type conductivity where the donor levels are occupied by the delocalized d x 2-y 2 electrons. It is suggested that the vanishing of n-type conductivity observed by the Hall measurement on the strained films are caused by the shift of donor levels into the conduction band. These results would provide insightful information for the realization of metallic conduction in SrFeO2. Project supported by the Creative Plan Project of Nanjing Forest Police College, China (Grant Nos. 201512213045xy and 201512213007x).

First-principles Theory of Magnetic Multipoles in Condensed Matter Systems

NASA Astrophysics Data System (ADS)

Suzuki, Michi-To; Ikeda, Hiroaki; Oppeneer, Peter M.

2018-04-01

The multipole concept, which characterizes the spacial distribution of scalar and vector objects by their angular dependence, has already become widely used in various areas of physics. In recent years it has become employed to systematically classify the anisotropic distribution of electrons and magnetization around atoms in solid state materials. This has been fuelled by the discovery of several physical phenomena that exhibit unusual higher rank multipole moments, beyond that of the conventional degrees of freedom as charge and magnetic dipole moment. Moreover, the higher rank electric/magnetic multipole moments have been suggested as promising order parameters in exotic hidden order phases. While the experimental investigations of such anomalous phases have provided encouraging observations of multipolar order, theoretical approaches have developed at a slower pace. In particular, a materials' specific theory has been missing. The multipole concept has furthermore been recognized as the key quantity which characterizes the resultant configuration of magnetic moments in a cluster of atomic moments. This cluster multipole moment has then been introduced as macroscopic order parameter for a noncollinear antiferromagnetic structure in crystals that can explain unusual physical phenomena whose appearance is determined by the magnetic point group symmetry. It is the purpose of this review to discuss the recent developments in the first-principles theory investigating multipolar degrees of freedom in condensed matter systems. These recent developments exemplify that ab initio electronic structure calculations can unveil detailed insight in the mechanism of physical phenomena caused by the unconventional, multipole degree of freedom.

Electric field effect on the electronic structure of 2D Y2C electride

NASA Astrophysics Data System (ADS)

Oh, Youngtek; Lee, Junsu; Park, Jongho; Kwon, Hyeokshin; Jeon, Insu; Wng Kim, Sung; Kim, Gunn; Park, Seongjun; Hwang, Sung Woo

2018-07-01

Electrides are ionic compounds in which electrons confined in the interstitial spaces serve as anions and are attractive owing to their exotic physical and chemical properties in terms of their low work function and efficient charge-transfer characteristics. Depending on the topology of the anionic electrons, the surface electronic structures of electrides can be significantly altered. In particular, the electronic structures of two-dimensional (2D) electride surfaces are of interest because the localized anionic electrons at the interlayer space can be naturally exposed to cleaved surfaces. In this paper, we report the electronic structure of 2D Y2C electride surface using scanning tunneling microscopy (STM) and first-principles calculations, which reveals that anionic electrons at a cleaved surface are absorbed by the surface and subsequently resurged onto the surface due to an applied electric field. We highlight that the estranged anionic electrons caused by the electric field occupy the slightly shifted crystallographic site compared with a bulk Y2C electride. We also measure the work function of the Y2C single crystal, and it shows a slightly lower value than the calculated one, which appears to be due to the electric field from the STM junction.

First-principles investigation of graphitic carbon nitride monolayer with embedded Fe atom

NASA Astrophysics Data System (ADS)

Abdullahi, Yusuf Zuntu; Yoon, Tiem Leong; Halim, Mohd Mahadi; Hashim, Md. Roslan; Lim, Thong Leng

2018-01-01

Density-functional theory (DFT) calculations with spin-polarized generalized gradient approximation and Hubbard U correction are carried out to investigate the mechanical, structural, electronic and magnetic properties of graphitic heptazine with embedded Fe atom under bi-axial tensile strain and applied perpendicular electric field. It was found that the binding energy of heptazine with embedded Fe atom system decreases as larger tensile strain is applied, while it increases as larger electric field strength is applied. Our calculations also predict a band gap at a peak value of 5% tensile strain but at expense of the structural stability of the system. The band gap open up at 5% tensile strain is due to distortion in the structure caused by the repulsive effect in the cavity between the lone pairs of the edge nitrogen atoms and dxy /dx2 -y2 orbital of Fe atom, forcing the unoccupied pz- orbital is forced to shift toward higher energy. The electronic and magnetic properties of the heptazine with embedded Fe system under perpendicular electric field up to a peak value of 8 V/nm is also well preserved despite an obvious buckled structure. Such properties are desirable for diluted magnetic semiconductors, spintronics, and sensing devices.

Experimental investigation of jet pulse control on flexible vibrating structures

NASA Astrophysics Data System (ADS)

Karaiskos, Grigorios; Papanicolaou, Panos; Zacharopoulos, Dimitrios

2016-08-01

The feasibility of applying on-line fluid jet pulses to actively control the vibrations of flexible structures subjected to harmonic and earthquake-like base excitations provided by a shake table is explored. The operating principles and capabilities of the control system applied have been investigated in a simplified small-scale laboratory model that is a mass attached at the top free end of a vertical flexible slender beam with rectangular cross-section, the other end of which is mounted on an electrodynamic shaker. A pair of opposite jets placed on the mass at the top of the cantilever beam applied the appropriate forces by ejecting pressurized air pulses controlled by on/off solenoid electro-valves via in house developed control software, in order to control the vibration caused by harmonic, periodic and random excitations at pre-selected frequency content provided by the shaker. The dynamics of the structure was monitored by accelerometers and the jet impulses by pressure sensors. The experimental results have demonstrated the effectiveness and reliability of Jet Pulse Control Systems (JPCS). It was verified that the measured root mean square (RMS) vibration levels of the controlled structure from harmonic and earthquake base excitations, could be reduced by approximately 50% and 33% respectively.

A Model for Determining Optimal Governance Structure in DoD Acquisition Projects in a Performance-Based Environment

DTIC Science & Technology

2010-04-30

combating market dynamism (Aldrich, 1979; Child, 1972), which is a result of evolving technology, shifting prices, or variance in product availability... principles : (1) human beings are bounded rationally, and (2), as a result of being rationally bound, will always choose to further their own self... principles to govern the relationship among the buyers and suppliers. Our conceptual model aligns the alternative governance structures derived

Design Principles for the Atomic and Electronic Structure of Halide Perovskite Photovoltaic Materials: Insights from Computation.

PubMed

Berger, Robert F

2018-02-09

In the current decade, perovskite solar cell research has emerged as a remarkably active, promising, and rapidly developing field. Alongside breakthroughs in synthesis and device engineering, halide perovskite photovoltaic materials have been the subject of predictive and explanatory computational work. In this Minireview, we focus on a subset of this computation: density functional theory (DFT)-based work highlighting the ways in which the electronic structure and band gap of this class of materials can be tuned via changes in atomic structure. We distill this body of computational literature into a set of underlying design principles for the band gap engineering of these materials, and rationalize these principles from the viewpoint of band-edge orbital character. We hope that this perspective provides guidance and insight toward the rational design and continued improvement of perovskite photovoltaics. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

First-principles investigation of mechanical properties of silicene, germanene and stanene

NASA Astrophysics Data System (ADS)

Mortazavi, Bohayra; Rahaman, Obaidur; Makaremi, Meysam; Dianat, Arezoo; Cuniberti, Gianaurelio; Rabczuk, Timon

2017-03-01

Two-dimensional allotropes of group-IV substrates including silicene, germanene and stanene have recently attracted considerable attention in nanodevice fabrication industry. These materials involving the buckled structure have been experimentally fabricated lately. In this study, first-principles density functional theory calculations were utilized to investigate the mechanical properties of single-layer and free-standing silicene, germanene and stanene. Uniaxial tensile and compressive simulations were carried out to probe and compare stress-strain properties; such as the Young's modulus, Poisson's ratio and ultimate strength. We evaluated the chirality effect on the mechanical response and bond structure of the 2D substrates. Our first-principles simulations suggest that in all studied samples application of uniaxial loading can alter the electronic nature of the buckled structures into the metallic character. Our investigation provides a general but also useful viewpoint with respect to the mechanical properties of silicene, germanene and stanene.

Band Structures and Transport Properties of High-Performance Half-Heusler Thermoelectric Materials by First Principles.

PubMed

Fang, Teng; Zhao, Xinbing; Zhu, Tiejun

2018-05-19

Half-Heusler (HH) compounds, with a valence electron count of 8 or 18, have gained popularity as promising high-temperature thermoelectric (TE) materials due to their excellent electrical properties, robust mechanical capabilities, and good high-temperature thermal stability. With the help of first-principles calculations, great progress has been made in half-Heusler thermoelectric materials. In this review, we summarize some representative theoretical work on band structures and transport properties of HH compounds. We introduce how basic band-structure calculations are used to investigate the atomic disorder in n-type M NiSb ( M = Ti, Zr, Hf) compounds and guide the band engineering to enhance TE performance in p-type Fe R Sb ( R = V, Nb) based systems. The calculations on electrical transport properties, especially the scattering time, and lattice thermal conductivities are also demonstrated. The outlook for future research directions of first-principles calculations on HH TE materials is also discussed.

Computational study of Li2OHCl as a possible solid state battery material

NASA Astrophysics Data System (ADS)

Howard, Jason; Holzwarth, N. A. W.

Preparations of Li2OHCl have recently been experimentally studied as solid state Li ion electrolytes. A disordered cubic phase is known to be stable at temperatures T >35o C. Following previous ideas, first principles supercells are constructed with up to 320 atoms to model the cubic phase. First principles molecular dynamics simulations of the cubic phase show Li ion diffusion occuring on the t =10-12 s time scale, at temperatures as low as T = 400 K. The structure of the lower temperature phase (T <35o C) is not known in detail. A reasonable model of this structure is developed by using the tetragonal ideal structure found by first principles simulations and a model Hamiltonian to account for alternative orientations of the OH groups. Supported by NSF Grant DMR-1507942. Thanks to Zachary D. Hood of GaTech and ORNL for introducing these materials to us.

Band Structures and Transport Properties of High-Performance Half-Heusler Thermoelectric Materials by First Principles

PubMed Central

Fang, Teng; Zhao, Xinbing

2018-01-01

Half-Heusler (HH) compounds, with a valence electron count of 8 or 18, have gained popularity as promising high-temperature thermoelectric (TE) materials due to their excellent electrical properties, robust mechanical capabilities, and good high-temperature thermal stability. With the help of first-principles calculations, great progress has been made in half-Heusler thermoelectric materials. In this review, we summarize some representative theoretical work on band structures and transport properties of HH compounds. We introduce how basic band-structure calculations are used to investigate the atomic disorder in n-type MNiSb (M = Ti, Zr, Hf) compounds and guide the band engineering to enhance TE performance in p-type FeRSb (R = V, Nb) based systems. The calculations on electrical transport properties, especially the scattering time, and lattice thermal conductivities are also demonstrated. The outlook for future research directions of first-principles calculations on HH TE materials is also discussed. PMID:29783759

FORTRAN Automated Code Evaluation System (faces) system documentation, version 2, mod 0. [error detection codes/user manuals (computer programs)

NASA Technical Reports Server (NTRS)

1975-01-01

A system is presented which processes FORTRAN based software systems to surface potential problems before they become execution malfunctions. The system complements the diagnostic capabilities of compilers, loaders, and execution monitors rather than duplicating these functions. Also, it emphasizes frequent sources of FORTRAN problems which require inordinate manual effort to identify. The principle value of the system is extracting small sections of unusual code from the bulk of normal sequences. Code structures likely to cause immediate or future problems are brought to the user's attention. These messages stimulate timely corrective action of solid errors and promote identification of 'tricky' code. Corrective action may require recoding or simply extending software documentation to explain the unusual technique.

Challenge of false alarms in nitroaromatic explosive detection--a detection device based on surface-enhanced Raman spectroscopy.

PubMed

Wackerbarth, Hainer; Gundrum, Lars; Salb, Christian; Christou, Konstantin; Viöl, Wolfgang

2010-08-10

A challenge in the detection of explosives is the differentiation between explosives and contaminants. Synthetic musk-containing perfumes can cause false alarms, as these perfumes are nitroaromatic compounds, which can be mistaken for trinitro toluene (TNT) by some detectors. We present a detection principle based on surface-enhanced Raman scattering (SERS). A stream of the airborne compounds is focused and resublimated on a cooled nanostructured gold surface. We recorded high-resolution SERS spectra of TNT, musk xylene, and musk ketone. The nitroaromatic compounds can be identified unambiguously by their SERS spectra. Even the dominant bands containing nitro-group scissoring and symmetric stretching modes are significantly shifted by the difference in molecular structure.

Data Banks; Bibliography.

ERIC Educational Resources Information Center

van der Aa, H. J., Comp.; And Others

This 249 item, mostly annotated bibliography cites literature on the general themes of basic principles, hardware, software and application studies of data bases. The broad categories are principles, development possibilities, organizational design, bibliographies, economic aspects, data structure-design, file organization, programing, aviation,…

Clinical trial design principles and endpoint definitions for transcatheter mitral valve repair and replacement: part 1: clinical trial design principles: A consensus document from the mitral valve academic research consortium.

PubMed

Stone, Gregg W; Vahanian, Alec S; Adams, David H; Abraham, William T; Borer, Jeffrey S; Bax, Jeroen J; Schofer, Joachim; Cutlip, Donald E; Krucoff, Mitchell W; Blackstone, Eugene H; Généreux, Philippe; Mack, Michael J; Siegel, Robert J; Grayburn, Paul A; Enriquez-Sarano, Maurice; Lancellotti, Patrizio; Filippatos, Gerasimos; Kappetein, Arie Pieter

2015-08-01

Mitral regurgitation (MR) is one of the most prevalent valve disorders and has numerous aetiologies, including primary (organic) MR, due to underlying degenerative/structural mitral valve (MV) pathology, and secondary (functional) MR, which is principally caused by global or regional left ventricular remodelling and/or severe left atrial dilation. Diagnosis and optimal management of MR requires integration of valve disease and heart failure specialists, MV cardiac surgeons, interventional cardiologists with expertise in structural heart disease, and imaging experts. The introduction of transcatheter MV therapies has highlighted the need for a consensus approach to pragmatic clinical trial design and uniform endpoint definitions to evaluate outcomes in patients with MR. The Mitral Valve Academic Research Consortium is a collaboration between leading academic research organizations and physician-scientists specializing in MV disease from the United States and Europe. Three in-person meetings were held in Virginia and New York during which 44 heart failure, valve, and imaging experts, MV surgeons and interventional cardiologists, clinical trial specialists and statisticians, and representatives from the U.S. Food and Drug Administration considered all aspects of MV pathophysiology, prognosis, and therapies, culminating in a 2-part document describing consensus recommendations for clinical trial design (Part 1) and endpoint definitions (Part 2) to guide evaluation of transcatheter and surgical therapies for MR. The adoption of these recommendations will afford robustness and consistency in the comparative effectiveness evaluation of new devices and approaches to treat MR. These principles may be useful for regulatory assessment of new transcatheter MV devices, as well as for monitoring local and regional outcomes to guide quality improvement initiatives. Published on behalf of the European Society of Cardiology. All rights reserved. © American College of Cardiology 2015. For permissions please email: journals.permissions@oup.com. This article is being published concurrently in Journal of the American College of Cardiology [1]. The articles are identical except for minor stylistic and spelling differences in keeping with each journal's style. Either citation can be used when citing this article. [1] Stone GW, Vahanian AS, Adams DH, Abraham WT, Borer JS et al. Clinical trial design principles and endpoint definitions for transcatheter mitral valve repair and replacement: Part 1: Clinical Trial Design Principles. J Am Coll Cardiol 2015;66:278–307. doi: 10.1016/j.jacc.2015.05.046.

A Canadian framework for applying the precautionary principle to public health issues.

PubMed

Weir, Erica; Schabas, Richard; Wilson, Kumanan; Mackie, Chris

2010-01-01

The precautionary principle has influenced environmental and public health policy. It essentially states that complete evidence of a potential risk is not required before action is taken to mitigate the effects of the potential risk. The application of precaution to public health issues is not straightforward and could paradoxically cause harm to the public's health when applied inappropriately. To avoid this, we propose a framework for applying the precautionary principle to potential public health risks. The framework consists of ten guiding questions to help establish whether a proposed application of the precautionary principle on a public health matter is based on adequacy of the evidence of causation, severity of harm and acceptability of the precautionary measures.

Factitious diarrhea

PubMed Central

Saibil, F. G.

1974-01-01

The causes of diarrhea are legion. In any diagnostic problem a factitious etiology must be carefully considered. Three cases are presented, in two of which daily ingestion of prunes and prune juice was found to be the cause of chronic diarrhea. In the third case an edible oil product, Coffee Rich, was determined by dietary manipulation to be the cause, carrageenan possibly being the laxative principle. PMID:4429937

Factitious diarrhea.

PubMed

Saibil, F G

1974-11-16

The causes of diarrhea are legion. In any diagnostic problem a factitious etiology must be carefully considered. Three cases are presented, in two of which daily ingestion of prunes and prune juice was found to be the cause of chronic diarrhea. In the third case an edible oil product, Coffee Rich, was determined by dietary manipulation to be the cause, carrageenan possibly being the laxative principle.

Foundations of quantum gravity: The role of principles grounded in empirical reality

NASA Astrophysics Data System (ADS)

Holman, Marc

2014-05-01

When attempting to assess the strengths and weaknesses of various principles in their potential role of guiding the formulation of a theory of quantum gravity, it is crucial to distinguish between principles which are strongly supported by empirical data - either directly or indirectly - and principles which instead (merely) rely heavily on theoretical arguments for their justification. Principles in the latter category are not necessarily invalid, but their a priori foundational significance should be regarded with due caution. These remarks are illustrated in terms of the current standard models of cosmology and particle physics, as well as their respective underlying theories, i.e., essentially general relativity and quantum (field) theory. For instance, it is clear that both standard models are severely constrained by symmetry principles: an effective homogeneity and isotropy of the known universe on the largest scales in the case of cosmology and an underlying exact gauge symmetry of nuclear and electromagnetic interactions in the case of particle physics. However, in sharp contrast to the cosmological situation, where the relevant symmetry structure is more or less established directly on observational grounds, all known, nontrivial arguments for the "gauge principle" are purely theoretical (and far less conclusive than usually advocated). Similar remarks apply to the larger theoretical structures represented by general relativity and quantum (field) theory, where - actual or potential - empirical principles, such as the (Einstein) equivalence principle or EPR-type nonlocality, should be clearly differentiated from theoretical ones, such as general covariance or renormalizability. It is argued that if history is to be of any guidance, the best chance to obtain the key structural features of a putative quantum gravity theory is by deducing them, in some form, from the appropriate empirical principles (analogous to the manner in which, say, the idea that gravitation is a curved spacetime phenomenon is arguably implied by the equivalence principle). Theoretical principles may still be useful however in formulating a concrete theory (analogous to the manner in which, say, a suitable form of general covariance can still act as a sieve for separating theories of gravity from one another). It is subsequently argued that the appropriate empirical principles for deducing the key structural features of quantum gravity should at least include (i) quantum nonlocality, (ii) irreducible indeterminacy (or, essentially equivalently, given (i), relativistic causality), (iii) the thermodynamic arrow of time, (iv) homogeneity and isotropy of the observable universe on the largest scales. In each case, it is explained - when appropriate - how the principle in question could be implemented mathematically in a theory of quantum gravity, why it is considered to be of fundamental significance and also why contemporary accounts of it are insufficient. For instance, the high degree of uniformity observed in the Cosmic Microwave Background is usually regarded as theoretically problematic because of the existence of particle horizons, whereas the currently popular attempts to resolve this situation in terms of inflationary models are, for a number of reasons, less than satisfactory. However, rather than trying to account for the required empirical features dynamically, an arguably much more fruitful approach consists in attempting to account for these features directly, in the form of a lawlike initial condition within a theory of quantum gravity.

Structural Polymorphism in “Kesterite” Cu 2ZnSnS 4 : Raman Spectroscopy and First-Principles Calculations Analysis

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

Dimitrievska, Mirjana; Boero, Federica; Litvinchuk, Alexander P.

This work presents detailed structural and vibrational characterization of different Cu 2ZnSnS 4 (CZTS) polymorphs (space groups: Imore » $$\\bar{4}$$, P$$\\bar{4}$$2c, and P$$\\bar{4}$$2m), using Raman spectroscopy and first-principles calculations. Multiwavelength Raman measurements on bulk crystalline CZTS samples permitted determination of the vibrational modes of each polymorph structure, with frequencies matching well with the results obtained from simulations. Lastly, the results present Raman spectra fingerprints as well as experimental references for the different polymorph modifications.« less

Structural Polymorphism in “Kesterite” Cu 2ZnSnS 4 : Raman Spectroscopy and First-Principles Calculations Analysis

DOE PAGES

Dimitrievska, Mirjana; Boero, Federica; Litvinchuk, Alexander P.; ...

2017-03-06

This work presents detailed structural and vibrational characterization of different Cu 2ZnSnS 4 (CZTS) polymorphs (space groups: Imore » $$\\bar{4}$$, P$$\\bar{4}$$2c, and P$$\\bar{4}$$2m), using Raman spectroscopy and first-principles calculations. Multiwavelength Raman measurements on bulk crystalline CZTS samples permitted determination of the vibrational modes of each polymorph structure, with frequencies matching well with the results obtained from simulations. Lastly, the results present Raman spectra fingerprints as well as experimental references for the different polymorph modifications.« less

A first principles prediction of the crystal structure of C6Br2ClFH2

NASA Astrophysics Data System (ADS)

Misquitta, Alston J.; Welch, Gareth W. A.; Stone, Anthony J.; Price, Sarah L.

2008-04-01

We have constructed an intermolecular potential for the 1,3-dibromo-2-chloro-5-fluorobenzene molecule from first principles using SAPT(DFT) interaction energy calculations and the Williams-Stone-Misquitta method for obtaining molecular properties in distributed form. This molecule was included in the fourth Blind Test of crystal structure prediction organised by the Cambridge Crystallographic Data Centre. Using our potential, we have predicted the crystal structure of CBrClFH and found the lowest energy solution to be in excellent agreement with the experimentally observed crystal when it was subsequently revealed.

The structural and electronic properties of amorphous HgCdTe from first-principles calculations

NASA Astrophysics Data System (ADS)

Zhao, Huxian; Chen, Xiaoshuang; Lu, Jianping; Shu, Haibo; Lu, Wei

2014-01-01

Amorphous mercury cadmium telluride (a-MCT) model structures, with x being 0.125 and 0.25, are obtained from first-principles calculations. We generate initial structures by computation alchemy method. It is found that most atoms in the network of amorphous structures tend to be fourfold and form tetrahedral structures, implying that the chemical ordered continuous random network with some coordination defects is the ideal structure for a-MCT. The electronic structure is also concerned. The gap is found to be 0.30 and 0.26 eV for a-Hg0.875Cd0.125Te and a-Hg0.75Cd0.25Te model structures, independent of the composition. By comparing with the properties of crystalline MCT with the same composition, we observe a blue-shift of energy band gap. The localization of tail states and its atomic origin are also discussed.

Elastohydrodynamic principles applied to the design of helicopter components.

NASA Technical Reports Server (NTRS)

Townsend, D. P.

1973-01-01

Elastohydrodynamic principles affecting the lubrication of transmission components are presented and discussed. Surface temperatures of the transmission bearings and gears affect elastohydrodynamic film thickness. Traction forces and sliding as well as the inlet temperature determine surface temperatures. High contact ratio gears cause increased sliding and may run at higher surface temperatures. Component life is a function of the ratio of elastohydrodynamic film thickness to composite surface roughness. Lubricant starvation reduces elastohydrodynamic film thickness and increases surface temperatures. Methods are presented which allow for the application of elastohydrodynamic principles to transmission design in order to increase system life and reliability.

Elastohydrodynamic principles applied to the design of helicopter components

NASA Technical Reports Server (NTRS)

Townsend, D. P.

1973-01-01

Elastohydrodynamic principles affecting the lubrication of transmission components are presented and discussed. Surface temperature of the transmission bearings and gears affect elastohydrodynamic film thickness. Traction forces and sliding as well as the inlet temperature determine surface temperatures. High contact ratio gears cause increased sliding and may run at higher surface temperatures. Component life is a function of the ratio of elastohydrodynamic film thickness to composite surface roughness. Lubricant starvation reduces elastrohydrodynamic film thickness and increases surface temperatures. Methods are presented which allow for the application of elastohydrodynamic principles to transmission design in order to increase system life and reliability.

Building Structure Housing: Case Study of Community Housing in Kendari City

NASA Astrophysics Data System (ADS)

Umar, M. Z.; Faslih, A.; Arsyad, M.; Sjamsu, A. S.; Kadir, I.

2017-11-01

Housing development has been pioneered through a simple home construction program to reduce the production cost. Simple housing program was developed in Kendari City. The purpose of this study is to show the principles of reducing the cost production for the type 36 homes, in Kendari City. The selected architectural objects are the lower, middle and the upper structure of type 36 house. The data collection was done by observation and in-depth discussion with construction workers. The analysis technique used in this research was a descriptive narrative analysis technique in the form of tabulation data. This study concluded that there are several principles of price reduction in the structure of public housing buildings. Quick principles exist in constructing techniques such as using cigarette packs as a foundation pad, mortar usage for rapid wall standing, and the spacing of mortars could be done manually by using two fingers on a human hand. Economic principles could be used for material matters, such as eliminating the use of gravel for concrete, the use of sand material to contain the soil, the foundation does not use sand and empty stone, and the shape of the ring beam was made using triangle reinforcement.

[Evidence-based medicine as a fundamental principle of health care management for workers].

PubMed

Amirov, N Kh; Fatkhutdinova, L M

2011-01-01

Evidence-based principles in occupational medicine should include prevention, diagnosis, treatment and rehabilitation. Specific feature of occupational medicine is necessity to prove cause-effect relationships between occupational factor and the disease emerged. Important place is occupied by cohort and intervention studies, systematic reviews and meta-analysis. Information obtained by scientific society should be presented to practical specialists and put into everyday activities.

Brain structural covariance network centrality in maltreated youth with PTSD and in maltreated youth resilient to PTSD.

PubMed

Sun, Delin; Haswell, Courtney C; Morey, Rajendra A; De Bellis, Michael D

2018-04-10

Child maltreatment is a major cause of pediatric posttraumatic stress disorder (PTSD). Previous studies have not investigated potential differences in network architecture in maltreated youth with PTSD and those resilient to PTSD. High-resolution magnetic resonance imaging brain scans at 3 T were completed in maltreated youth with PTSD (n = 31), without PTSD (n = 32), and nonmaltreated controls (n = 57). Structural covariance network architecture was derived from between-subject intraregional correlations in measures of cortical thickness in 148 cortical regions (nodes). Interregional positive partial correlations controlling for demographic variables were assessed, and those correlations that exceeded specified thresholds constituted connections in cortical brain networks. Four measures of network centrality characterized topology, and the importance of cortical regions (nodes) within the network architecture were calculated for each group. Permutation testing and principle component analysis method were employed to calculate between-group differences. Principle component analysis is a methodological improvement to methods used in previous brain structural covariance network studies. Differences in centrality were observed between groups. Larger centrality was found in maltreated youth with PTSD in the right posterior cingulate cortex; smaller centrality was detected in the right inferior frontal cortex compared to youth resilient to PTSD and controls, demonstrating network characteristics unique to pediatric maltreatment-related PTSD. Larger centrality was detected in right frontal pole in maltreated youth resilient to PTSD compared to youth with PTSD and controls, demonstrating structural covariance network differences in youth resilience to PTSD following maltreatment. Smaller centrality was found in the left posterior cingulate cortex and in the right inferior frontal cortex in maltreated youth compared to controls, demonstrating attributes of structural covariance network topology that is unique to experiencing maltreatment. This work is the first to identify cortical thickness-based structural covariance network differences between maltreated youth with and without PTSD. We demonstrated network differences in both networks unique to maltreated youth with PTSD and those resilient to PTSD. The networks identified are important for the successful attainment of age-appropriate social cognition, attention, emotional processing, and inhibitory control. Our findings in maltreated youth with PTSD versus those without PTSD suggest vulnerability mechanisms for developing PTSD.

Cocklebur (Xanthium strumarium, L. var. strumarium) intoxication in swine: review and redefinition of the toxic principle.

PubMed

Stuart, B P; Cole, R J; Gosser, H S

1981-05-01

Cocklebur (Xanthium strumarium) fed to feeder pigs was associated with acute to subacute hepatotoxicosis. Cotyledonary seedings fed at 0.75% to 3% of body weight or ground bur fed at 20% to 30% of the ration caused acute depression, convulsions, and death. Principle gross lesions were marked serofibrinous ascites, edema of the gallbladder wall, and lobular accentuation of the liver. Acute to subacute centrilobular hepatic necrosis was present microscopically. The previously reported toxic principle, hydroquinone, was not recovered from the plant or bur of X. strumarium. Authentic hydroquinone administered orally failed to produce lesions typical of cocklebur intoxication but did produce marked hyperglycemia. Carboxyatractyloside recovered from the aqueous extract of X. strumarium and authentic carboxyatractyloside, when fed to pigs, caused signs and lesions typical of cocklebur intoxication. Marked hypoglycemia and elevated serum glutamic oxaloacetic transaminase and serum isocitric dehydrogenase concentrations occurred in pigs with acute hepatic necrosis that had received either cocklebur seedlings, ground bur or carboxyatractyloside.

Darwin, Hume, Morgan, and the verae causae of psychology.

PubMed

Clatterbuck, Hayley

2016-12-01

Charles Darwin and C. Lloyd Morgan forward two influential principles of cognitive ethological inference that yield conflicting results about the extent of continuity in the cognitive traits of humans and other animals. While these principles have been interpreted as reflecting commitments to different senses of parsimony, in fact, both principles result from the same vera causa inferential strategy, according to which "We ought to admit no more causes of natural things, than such as are both true and sufficient to explain their appearances". Instead, the conflict stems from Darwin's and Morgan's views about the true causes of human psychology. Darwin holds a thoroughly Humean philosophy of the human mind, from which he infers significant continuity between human and animal minds. In contrast, Morgan argues that Humean cognitive mechanisms cannot account for a class of uniquely human behaviors, and therefore, he concludes that there is a significant discontinuity between human and animal cognition. This historical debate is informative for current controversies in comparative psychology. Copyright © 2016 Elsevier Ltd. All rights reserved.

Identification of F impurities in F-doped ZnO by synchrotron X-ray absorption near edge structures

NASA Astrophysics Data System (ADS)

Na-Phattalung, Sutassana; Limpijumnong, Sukit; Min, Chul-Hee; Cho, Deok-Yong; Lee, Seung-Ran; Char, Kookrin; Yu, Jaejun

2018-04-01

Synchrotron X-ray absorption near edge structure (XANES) measurements of F K-edge in conjunction with first-principles calculations are used to identify the local structure of the fluorine (F) atom in F-doped ZnO. The ZnO film was grown by pulsed laser deposition with an Nd:YAG laser, and an oxyfluoridation method was used to introduce F ions into the ZnO films. The measured XANES spectrum of the sample was compared against the first-principles XANES calculations based on various models for local atomic structures surrounding F atoms. The observed spectral features are attributed to ZnF2 and FO defects in wurtzite bulk ZnO.

First-principles study of structural and electronic properties of Be0.25Zn0.75S mixed compound

NASA Astrophysics Data System (ADS)

Paliwal, U.; Joshi, K. B.

2018-05-01

In this work the first-principles study of structural and electronic properties of Be0.25Zn0.75S mixed compound is presented. The calculations are performed applying the QUANTUM ESPRESSO code utilizing the Perdew, Becke, Ernzerhof generalized gradient approximation in the framework of density functional theory. Adopting standard optimization strategy, the ground state equilibrium lattice constant and bulk modulus are calculated. After settling the structure the electronic band structure, bandgap and static dielectric constant are evaluated. In absence of any experimental work on this system our findings are compared with the available theoretical calculations which are found to follow well anticipated general trends.

Structure and properties of microporous titanosilicate determined by first-principles calculations

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

Ching, W.Y.; Xu, Y.; Gu, Z.

1996-12-01

The structure of EST-10, a member of synthetic microporous titanosilicates, was recently determined by an ingenious combination of experimental and simulational techniques. However, the locations of the alkali atoms in the framework remain elusive and its electronic structure is totally unknown. Based on first-principles local density calculations, the possible locations of the alkali atoms are identified and its electronic structure and bonding fully elucidated. ETS-10 is a semiconductor with a direct band gap of 2.33 eV. The Na atoms are likely to locate inside the seven-member ring pore adjacent to the one-dimensional Ti-O-Ti-O- chain. {copyright} {ital 1996 The American Physicalmore » Society.}« less

Lithium halide monolayers: Structural, electronic and optical properties by first principles study

NASA Astrophysics Data System (ADS)

Safari, Mandana; Maskaneh, Pegah; Moghadam, Atousa Dashti; Jalilian, Jaafar

2016-09-01

Using first principle study, we investigate the structural, electronic and optical properties of lithium halide monolayers (LiF, LiCl, LiBr). In contrast to graphene and other graphene-like structures that form hexagonal rings in plane, these compounds can form and stabilize in cubic shape interestingly. The type of band structure in these insulators is identified as indirect type and ionic nature of their bonds are illustrated as well. The optical properties demonstrate extremely transparent feature for them as a result of wide band gap in the visible range; also their electron transitions are indicated for achieving a better vision on the absorption mechanism in these kinds of monolayers.

Fermion systems in discrete space-time

NASA Astrophysics Data System (ADS)

Finster, Felix

2007-05-01

Fermion systems in discrete space-time are introduced as a model for physics on the Planck scale. We set up a variational principle which describes a non-local interaction of all fermions. This variational principle is symmetric under permutations of the discrete space-time points. We explain how for minimizers of the variational principle, the fermions spontaneously break this permutation symmetry and induce on space-time a discrete causal structure.

Ashley, Two Born as One, and the Best Interests of a Child.

PubMed

Gillett, Grant

2016-01-01

What is in the best interests of a child, and could that ever include interventions that we might regard as prima facie detrimental to a child's physical well-being? This question is raised a fortiori by growth attenuation treatments in children with severe neurological disorders causing extreme developmental delay. I argue that two principles that provide guidance in generating a conception of best interests for each individual child yield the right results in such cases. The principles are as follows: the potentiality principle, whereby every child should be able to develop its potential and is entitled to receive certain help in doing so, and the principle of psychosomatic harmony, whereby every human being is entitled to treatment that is appropriate to or enables a life in which mind and body are in tune with each other. These principles indicate a certain response to what we can call Ashley-type cases and admit certain caveats.

Minimization principles for the coupled problem of Darcy-Biot-type fluid transport in porous media linked to phase field modeling of fracture

NASA Astrophysics Data System (ADS)

Miehe, Christian; Mauthe, Steffen; Teichtmeister, Stephan

2015-09-01

This work develops new minimization and saddle point principles for the coupled problem of Darcy-Biot-type fluid transport in porous media at fracture. It shows that the quasi-static problem of elastically deforming, fluid-saturated porous media is related to a minimization principle for the evolution problem. This two-field principle determines the rate of deformation and the fluid mass flux vector. It provides a canonically compact model structure, where the stress equilibrium and the inverse Darcy's law appear as the Euler equations of a variational statement. A Legendre transformation of the dissipation potential relates the minimization principle to a characteristic three field saddle point principle, whose Euler equations determine the evolutions of deformation and fluid content as well as Darcy's law. A further geometric assumption results in modified variational principles for a simplified theory, where the fluid content is linked to the volumetric deformation. The existence of these variational principles underlines inherent symmetries of Darcy-Biot theories of porous media. This can be exploited in the numerical implementation by the construction of time- and space-discrete variational principles, which fully determine the update problems of typical time stepping schemes. Here, the proposed minimization principle for the coupled problem is advantageous with regard to a new unconstrained stable finite element design, while space discretizations of the saddle point principles are constrained by the LBB condition. The variational principles developed provide the most fundamental approach to the discretization of nonlinear fluid-structure interactions, showing symmetric systems in algebraic update procedures. They also provide an excellent starting point for extensions towards more complex problems. This is demonstrated by developing a minimization principle for a phase field description of fracture in fluid-saturated porous media. It is designed for an incorporation of alternative crack driving forces, such as a convenient criterion in terms of the effective stress. The proposed setting provides a modeling framework for the analysis of complex problems such as hydraulic fracture. This is demonstrated by a spectrum of model simulations.

Highly responsive ground state of PbTaSe 2 : Structural phase transition and evolution of superconductivity under pressure

DOE PAGES

Kaluarachchi, Udhara S.; Deng, Yuhang; Besser, Matthew F.; ...

2017-06-09

Transport and magnetic studies of PbTaSe 2 under pressure suggest the existence of two superconducting phases with the low temperature phase boundary at ~ 0.25 GPa that is defined by a very sharp, first order, phase transition. The first order phase transition line can be followed via pressure dependent resistivity measurements, and is found to be near 0.12 GPa near room temperature. Transmission electron microscopy and x-ray diffraction at elevated temperatures confirm that this first order phase transition is structural and occurs at ambient pressure near ~ 425 K. The new, high temperature/high pressure phase has a similar crystal structuremore » and slightly lower unit cell volume relative to the ambient pressure, room temperature structure. Based on first-principles calculations this structure is suggested to be obtained by shifting the Pb atoms from the 1 a to 1 e Wyckoff position without changing the positions of Ta and Se atoms. PbTaSe 2 has an exceptionally pressure sensitive, structural phase transition with Δ T s / Δ P ≈ -1400 K/GPa near room temperature, and ≈ -1700 K/GPa near 4 K. This first order transition causes a ~ 1 K (~ 25 % ) steplike decrease in T c as pressure is increased through 0.25 GPa.« less

Effect of oxygen vacancies on the electronic and optical properties of tungsten oxide from first principles calculations

NASA Astrophysics Data System (ADS)

Mehmood, Faisal; Pachter, Ruth; Murphy, Neil R.; Johnson, Walter E.; Ramana, Chintalapalle V.

2016-12-01

In this work, we investigated theoretically the role of oxygen vacancies on the electronic and optical properties of cubic, γ-monoclinic, and tetragonal phases of tungsten oxide (WO3) thin films. Following the examination of structural properties and stability of the bulk tungsten oxide polymorphs, we analyzed band structures and optical properties, applying density functional theory (DFT) and GW (Green's (G) function approximation with screened Coulomb interaction (W)) methods. Careful benchmarking of calculated band gaps demonstrated the importance of using a range-separated functional, where results for the pristine room temperature γ-monoclinic structure indicated agreement with experiment. Further, modulation of the band gap for WO3 structures with oxygen vacancies was quantified. Dielectric functions for cubic WO3, calculated at both the single-particle, essentially time-dependent DFT, as well as many-body GW-Bethe-Salpeter equation levels, indicated agreement with experimental data for pristine WO3. Interestingly, we found that introducing oxygen vacancies caused appearance of lower energy absorptions. A smaller refractive index was indicated in the defective WO3 structures. These predictions could lead to further experiments aimed at tuning the optical properties of WO3 by introducing oxygen vacancies, particularly for the lower energy spectral region.

An Ultrastable Heterobimetallic Uranium(IV)/Vanadium(III) Solid Compound Protected by a Redox-Active Phosphite Ligand: Crystal Structure, Oxidative Dissolution, and First-Principles Simulation.

PubMed

Gui, Daxiang; Dai, Xing; Zheng, Tao; Wang, Xiangxiang; Silver, Mark A; Chen, Lanhua; Zhang, Chao; Diwu, Juan; Zhou, Ruhong; Chai, Zhifang; Wang, Shuao

2018-02-05

The first heterobimetallic uranium(IV)/vanadium(III) phosphite compound, Na 2 UV 2 (HPO 3 ) 6 (denoted as UVP), was synthesized via an in situ redox-active hydrothermal reaction. It exhibits superior hydrolytic and antioxidant stability compared to the majority of structures containing low-valent uranium or vanadium, further elucidated by first-principles simulations, and therefore shows potential applications in nuclear waste management.

Research on the fundamental principles of China's marine invasive species prevention legislation.

PubMed

Bai, Jiayu

2014-12-15

China's coastal area is severely damaged by marine invasive species. Traditional tort theory resolves issues relevant to property damage or personal injuries, through which plaintiffs cannot cope with the ecological damage caused by marine invasive species. Several defects exist within the current legal regimes, such as imperfect management systems, insufficient unified technical standards, and unsound legal responsibility systems. It is necessary to pass legislation to prevent the ecological damage caused by marine invasive species. This investigation probes the fundamental principles needed for the administration and legislation of an improved legal framework to combat the problem of invasive species within China's coastal waters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Natural frequency identification of smart washer by using adaptive observer

NASA Astrophysics Data System (ADS)

Ito, Hitoshi; Okugawa, Masayuki

2014-04-01

Bolted joints are used in many machines/structures and some of them have been loosened during long time use, and unluckily these bolt loosening may cause a great accident of machines/structures system. These bolted joint, especially in important places, are main object of maintenance inspection. Maintenance inspection with human- involvement is desired to be improved owing to time-consuming, labor-intensive and high-cost. By remote and full automation monitoring of the bolt loosening, constantly monitoring of bolted joint is achieved. In order to detect loosening of bolted joints without human-involvement, applying a structural health monitoring technique and smart structures/materials concept is the key objective. In this study, a new method of bolt loosening detection by adopting a smart washer has been proposed, and the basic detection principle was discussed with numerical analysis about frequency equation of the system, was confirmed experimentally. The smart washer used in this study is in cantilever type with piezoelectric material, which adds the washer the self-sensing and actuation function. The principle used to detect the loosening of the bolts is a method of a bolt loosening detection noted that the natural frequency of a smart washer system is decreasing by the change of the bolt tightening axial tension. The feature of this proposed method is achieving to identify the natural frequency at current condition on demand by adopting the self-sensing and actuation function and system identification algorithm for varying the natural frequency depending the bolt tightening axial tension. A novel bolt loosening detection method by adopting adaptive observer is proposed in this paper. The numerical simulations are performed to verify the possibility of the adaptive observer-based loosening detection. Improvement of the detection accuracy for a bolt loosening is confirmed by adopting initial parameter and variable adaptive gain by numerical simulation.

Meaningful questions: The acquisition of auxiliary inversion in a connectionist model of sentence production.

PubMed

Fitz, Hartmut; Chang, Franklin

2017-09-01

Nativist theories have argued that language involves syntactic principles which are unlearnable from the input children receive. A paradigm case of these innate principles is the structure dependence of auxiliary inversion in complex polar questions (Chomsky, 1968, 1975, 1980). Computational approaches have focused on the properties of the input in explaining how children acquire these questions. In contrast, we argue that messages are structured in a way that supports structure dependence in syntax. We demonstrate this approach within a connectionist model of sentence production (Chang, 2009) which learned to generate a range of complex polar questions from a structured message without positive exemplars in the input. The model also generated different types of error in development that were similar in magnitude to those in children (e.g., auxiliary doubling, Ambridge, Rowland, & Pine, 2008; Crain & Nakayama, 1987). Through model comparisons we trace how meaning constraints and linguistic experience interact during the acquisition of auxiliary inversion. Our results suggest that auxiliary inversion rules in English can be acquired without innate syntactic principles, as long as it is assumed that speakers who ask complex questions express messages that are structured into multiple propositions. Copyright © 2017 Elsevier B.V. All rights reserved.

A conductive grating sensor for online quantitative monitoring of fatigue crack.

PubMed

Li, Peiyuan; Cheng, Li; Yan, Xiaojun; Jiao, Shengbo; Li, Yakun

2018-05-01

Online quantitative monitoring of crack damage due to fatigue is a critical challenge for structural health monitoring systems assessing structural safety. To achieve online quantitative monitoring of fatigue crack, a novel conductive grating sensor based on the principle of electrical potential difference is proposed. The sensor consists of equidistant grating channels to monitor the fatigue crack length and conductive bars to provide the circuit path. An online crack monitoring system is established to verify the sensor's capability. The experimental results prove that the sensor is suitable for online quantitative monitoring of fatigue crack. A finite element model for the sensor is also developed to optimize the sensitivity of crack monitoring, which is defined by the rate of sensor resistance change caused by the break of the first grating channel. Analysis of the model shows that the sensor sensitivity can be enhanced by reducing the number of grating channels and increasing their resistance and reducing the resistance of the conductive bar.

Radiation field control at the latest BWR plants -- design principle, operational experience and future subjects

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

Uchida, Shunsuke; Ohsumi, Katsumi; Takashima, Yoshie

1995-03-01

Improvements of operational procedures to control water chemistry, e.g., nickel/iron control, as well as application of hardware improvements for reducing radioactive corrosion products resulted in an extremely low occupational exposure of less than 0.5 man.Sv/yr without any serious impact on the radwaste system, for BWR plants involved in the Japanese Improvement and Standardization Program. Recently, {sup 60}C radioactively in the reactor water has been increasing due to less crud fixation on the two smooth surfaces of new type high performance fuels and to the pH drop caused by chromium oxide anions released from stainless steel structures and pipings. This increasemore » must be limited by changes in water chemistry, e.g., applications of modified nickel/iron ratio control and weak alkali control. Controlled water chemistry to optimize three points, the plant radiation level and integrities of fuel and structural materials, is the primary future subject for BWR water chemistry.« less

Aspects of structural landscape of human islet amyloid polypeptide

NASA Astrophysics Data System (ADS)

He, Jianfeng; Dai, Jin; Li, Jing; Peng, Xubiao; Niemi, Antti J.

2015-01-01

The human islet amyloid polypeptide (hIAPP) co-operates with insulin to maintain glycemic balance. It also constitutes the amyloid plaques that aggregate in the pancreas of type-II diabetic patients. We have performed extensive in silico investigations to analyse the structural landscape of monomeric hIAPP, which is presumed to be intrinsically disordered. For this, we construct from first principles a highly predictive energy function that describes a monomeric hIAPP observed in a nuclear magnetic resonance experiment, as a local energy minimum. We subject our theoretical model of hIAPP to repeated heating and cooling simulations, back and forth between a high temperature regime where the conformation resembles a random walker and a low temperature limit where no thermal motions prevail. We find that the final low temperature conformations display a high level of degeneracy, in a manner which is fully in line with the presumed intrinsically disordered character of hIAPP. In particular, we identify an isolated family of α-helical conformations that might cause the transition to amyloidosis, by nucleation.

Modeling Carbon and Hydrocarbon Molecular Structures in EZTB

NASA Technical Reports Server (NTRS)

Lee, Seungwon; vonAllmen, Paul

2007-01-01

A software module that models the electronic and mechanical aspects of hydrocarbon molecules and carbon molecular structures on the basis of first principles has been written for incorporation into, and execution within, the Easy (Modular) Tight-Binding (EZTB) software infrastructure, which is summarized briefly in the immediately preceding article. Of particular interest, this module can model carbon crystals and nanotubes characterized by various coordinates and containing defects, without need to adjust parameters of the physical model. The module has been used to study the changes in electronic properties of carbon nanotubes, caused by bending of the nanotubes, for potential utility as the basis of a nonvolatile, electriccharge- free memory devices. For example, in one application of the module, it was found that an initially 50-nmlong carbon, (10,10)-chirality nanotube, which is a metallic conductor when straight, becomes a semiconductor with an energy gap of .3 meV when bent to a lateral displacement of 4 nm at the middle.

A mechanism of institutional isomorphism in referral networks among hospitals in Seoul, South Korea.

PubMed

Jung, Minsoo; Choi, Mankyu

2010-01-01

Hospitals engage in medical referral system relations voluntarily, by virtue of their own service capacities. These capacities include medical technology, equipment supply, and patient management, which are assessed individually by medical institutions in efforts to control costs and maintain efficiency in tertiary hospitals. This study assessed referral networks according to the institutional isomorphism theory of new economic sociology. As a result, the referral networks were shown to exhibit emergent structural hierarchy via cumulative clustering by established year and were not affected by attributive variables such as region, bed number, and year of establishment. In particular, the networks evidenced institutional isomorphism with certain central hospitals. As a consequence, personal indices were shown to decrease in accordance with its period, and only the structural index increased. Normative pressures cause organizations to become hierarchically homogenized, in accordance with the principle of organizational learning in specialized fields. Therefore, normative isomorphism on the basis of public domains should be considered an inherent factor in the development of referral networks.

A conductive grating sensor for online quantitative monitoring of fatigue crack

NASA Astrophysics Data System (ADS)

Li, Peiyuan; Cheng, Li; Yan, Xiaojun; Jiao, Shengbo; Li, Yakun

2018-05-01

Online quantitative monitoring of crack damage due to fatigue is a critical challenge for structural health monitoring systems assessing structural safety. To achieve online quantitative monitoring of fatigue crack, a novel conductive grating sensor based on the principle of electrical potential difference is proposed. The sensor consists of equidistant grating channels to monitor the fatigue crack length and conductive bars to provide the circuit path. An online crack monitoring system is established to verify the sensor's capability. The experimental results prove that the sensor is suitable for online quantitative monitoring of fatigue crack. A finite element model for the sensor is also developed to optimize the sensitivity of crack monitoring, which is defined by the rate of sensor resistance change caused by the break of the first grating channel. Analysis of the model shows that the sensor sensitivity can be enhanced by reducing the number of grating channels and increasing their resistance and reducing the resistance of the conductive bar.

The design of the intelligent monitoring system for dam safety

NASA Astrophysics Data System (ADS)

Yuan, Chun-qiao; Jiang, Chen-guang; Wang, Guo-hui

2008-12-01

Being a vital manmade water-control structure, a dam plays a very important role in the living and production of human being. To make a dam run safely, the best design and the superior construction quality are paramount; moreover, with working periods increasing, various dynamic, alternative and bad loads generate little by little various distortions on the dam structure inevitably, which shall lead to potential safety problems or further a disaster (dam burst). There are many signs before the occurrence of a dam accident, so the timely and effective surveying on the distortion of a dam is important. On the basis of the cause supra, two intelligent (automatic) monitoring systems about the dam's safety based on the RTK-GPS technology and the measuring robot has been developed. The basic principle, monitoring method and monitoring process of these two intelligent (automatic) monitoring systems are introduced. It presents examples of monitor and puts forward the basic rule of dam warning based on data of actual monitor.

GaAs monolayer: Excellent SHG responses and semi metallic to metallic transition modulated by vacancy effect

NASA Astrophysics Data System (ADS)

Rozahun, Ilmira; Bahti, Tohtiaji; He, Guijie; Ghupur, Yasenjan; Ablat, Abduleziz; Mamat, Mamatrishat

2018-05-01

Monolayer materials are considered as a promising candidate for novel applications due to their attractive magnetic, electronic and optical properties. Investigation on nonlinear optical (NLO) properties and effect of vacancy on monolayer materials are vital to property modulations of monolayers and extending their applications. In this work, with the aid of first-principles calculations, the crystal structure, electronic, magnetic, and optical properties of GaAs monolayers with the vacancy were investigated. The result shows gallium arsenic (GaAs) monolayer produces a strong second harmonic generation (SHG) response. Meanwhile, the vacancy strongly affects structural, electronic, magnetic and optical properties of GaAs monolayers. Furthermore, arsenic vacancy (VAs) brings semi metallic to metallic transition, while gallium vacancy (VGa) causes nonmagnetic to magnetic conversion. Our result reveals that GaAs monolayer possesses application potentials in Nano-amplifying modulator and Nano-optoelectronic devices, and may provide useful guidance in designing new generation of Nano-electronic devices.

Active colloids as assembly machines

NASA Astrophysics Data System (ADS)

Goodrich, Carl; Brenner, Michael

Controlling motion at the microscopic scale is a fundamental goal in the development of biologically-inspired systems. We show that the motion of active, self-propelled colloids can be sufficiently controlled for use as a tool to assemble complex structures such as braids and weaves out of microscopic filaments. Unlike typical self-assembly paradigms, these structures are held together by geometric constraints rather than adhesive bonds. The out-of-equilibrium assembly that we propose involves precisely controlling the two-dimensional motion of active colloids so that their path has a non-trivial topology. We demonstrate with proof-of-principle Brownian dynamics simulations that, when the colloids are attached to long semi-flexible filaments, this motion causes the filaments to braid. The ability of the active particles to provide sufficient force necessary to bend the filaments into a braid depends on a number of factors, including the self-propulsion mechanism, the properties of the filament, and the maximum curvature in the braid. Our work demonstrates that non-equilibrium assembly pathways can be designed using active particles.

Unifying treatments for depression: an application of the Free Energy Principle

PubMed Central

Chekroud, Adam M.

2015-01-01

Major Depressive Disorder is a debilitating and increasingly prevalent psychiatric condition (Compton et al., 2006; Andersen et al., 2011). At present, its primary treatments are antidepressant medications and psychotherapy. Curiously, although the pharmacological effects of antidepressants manifest within hours, remission of clinical symptoms takes a number of weeks—if at all. Independently, support has grown for an idea—proposed as early as Helmholtz (von Helmholtz, 1924)—that the brain is a prediction machine, holding generative models1 for the purpose of inferring causes of sensory information (Dayan et al., 1995; Rao and Ballard, 1999; Knill and Pouget, 2004; Friston et al., 2006; Friston, 2010). If the brain does indeed represent a collection of beliefs about the causal structure of the world, then the depressed phenotype may emerge from a collection of depressive beliefs. These beliefs are modified gradually through successive combinations of expectations with observations. As a result, phenotypic remission ought to take some time as the brain's relevant statistical structures become less pessimistic. PMID:25750630

Laser interferometer used for nanometer vibration measurements

NASA Astrophysics Data System (ADS)

Sun, Jiaxing; Yang, Jun; Liu, Zhihai; Yuan, Libo

2007-01-01

A novel laser interferometer which adopts alternating modulation phase tracking homodyne technique is proposed. The vibration of nanometer-accuracy is measured with the improved Michelson interferometer by adding cat's eye moving mirror and PZT phase modulation tracking structure. The working principle and the structure of the interferometer are analyzed and the demodulation scheme of alternating phase modulation and tracking is designed. The signal detection is changed from direct current detecting to alternating current detecting. The signal's frequency spectrum transform is achieved, the low-frequency noise jamming is abated, the Signal-to-Noise of the system is improved and the measured resolution is enhanced. Phase tracking technique effectively suppresses the low-frequency noise which is caused by outside environment factors such as temperature and vibration, and the stability of the system is enhanced. The experimental results indicate that for the signal with the frequency of 100Hz and the amplitude of 25nm, the output Signal-to-Noise is 30dB and the measured resolution is 1nm.

Using in-cell SHAPE-Seq and simulations to probe structure–function design principles of RNA transcriptional regulators

PubMed Central

Takahashi, Melissa K.; Watters, Kyle E.; Gasper, Paul M.; Abbott, Timothy R.; Carlson, Paul D.; Chen, Alan A.

2016-01-01

Antisense RNA-mediated transcriptional regulators are powerful tools for controlling gene expression and creating synthetic gene networks. RNA transcriptional repressors derived from natural mechanisms called attenuators are particularly versatile, though their mechanistic complexity has made them difficult to engineer. Here we identify a new structure–function design principle for attenuators that enables the forward engineering of new RNA transcriptional repressors. Using in-cell SHAPE-Seq to characterize the structures of attenuator variants within Escherichia coli, we show that attenuator hairpins that facilitate interaction with antisense RNAs require interior loops for proper function. Molecular dynamics simulations of these attenuator variants suggest these interior loops impart structural flexibility. We further observe hairpin flexibility in the cellular structures of natural RNA mechanisms that use antisense RNA interactions to repress translation, confirming earlier results from in vitro studies. Finally, we design new transcriptional attenuators in silico using an interior loop as a structural requirement and show that they function as desired in vivo. This work establishes interior loops as an important structural element for designing synthetic RNA gene regulators. We anticipate that the coupling of experimental measurement of cellular RNA structure and function with computational modeling will enable rapid discovery of structure–function design principles for a diverse array of natural and synthetic RNA regulators. PMID:27103533

Conceptual Models and Theory-Embedded Principles on Effective Schooling.

ERIC Educational Resources Information Center

Scheerens, Jaap

1997-01-01

Reviews models and theories on effective schooling. Discusses four rationality-based organization theories and a fifth perspective, chaos theory, as applied to organizational functioning. Discusses theory-embedded principles flowing from these theories: proactive structuring, fit, market mechanisms, cybernetics, and self-organization. The…

Freud's philosophical inheritance: Schopenhauer and Nietzsche in Beyond the Pleasure Principle.

PubMed

Grimwade, Robert

2012-06-01

This essay explores the possible significance of Freud's references to Schopenhauer and Nietzsche in Beyond the Pleasure Principle. It attempts to reveal two sides of Freud's philosophical inheritance and explores the structure of Freud's ambivalence toward his intellectual predecessors.

Structures and magnetic properties of Co-Zr-B magnets studied by first-principles calculations

DOE PAGES

Zhao, Xin; Ke, Liqin; Nguyen, Manh Cuong; ...

2015-06-23

The structures and magnetic properties of Co-Zr-B alloys near the composition of Co 5Zr with B at. % ≤6% were studied using adaptive genetic algorithm and first-principles calculations. The energy and magnetic moment contour maps as a function of chemical composition were constructed for the Co-Zr-B magnet alloys through extensive structure searches and calculations. We found that Co-Zr-B system exhibits the same structure motif as the “Co 11Zr 2” polymorphs, and such motif plays a key role in achieving strong magnetic anisotropy. Boron atoms were found to be able to substitute cobalt atoms or occupy the “interruption” sites. First-principles calculationsmore » showed that the magnetocrystalline anisotropy energies of the boron-doped alloys are close to that of the high-temperature rhombohedral Co 5Zr phase and larger than that of the low-temperature Co 5.25Zr phase. As a result, our calculations provide useful guidelines for further experimental optimization of the magnetic performances of these alloys.« less

Babinet's principle for optical frequency metamaterials and nanoantennas

NASA Astrophysics Data System (ADS)

Zentgraf, T.; Meyrath, T. P.; Seidel, A.; Kaiser, S.; Giessen, H.; Rockstuhl, C.; Lederer, F.

2007-07-01

We consider Babinet’s principle for metamaterials at optical frequencies and include realistic conditions which deviate from the theoretical assumptions of the classic principle such as an infinitely thin and perfectly conducting metal layer. It is shown that Babinet’s principle associates not only transmission and reflection between a structure and its complement but also the field modal profiles of the electromagnetic resonances as well as effective material parameters—a critical concept for metamaterials. Also playing an important role in antenna design, Babinet’s principle is particularly interesting to consider in this case where the metasurfaces and their complements can be regarded as variations on a folded dipole antenna array and patch antenna array, respectively.

Structural, electronic, elastic, and thermodynamic properties of CaSi, Ca2Si, and CaSi2 phases from first-principles calculations

NASA Astrophysics Data System (ADS)

Li, X. D.; Li, K.; Wei, C. H.; Han, W. D.; Zhou, N. G.

2018-06-01

The structural, electronic, elastic, and thermodynamic properties of CaSi, Ca2Si, and CaSi2 are systematically investigated by using first-principles calculations method based on density functional theory (DFT). The calculated formation enthalpies and cohesive energies show that CaSi2 possesses the greatest structural stability and CaSi has the strongest alloying ability. The structural stability of the three phases is compared according to electronic structures. Further analysis on electronic structures indicates that the bonding of these phases exhibits the combinations of metallic, covalent, and ionic bonds. The elastic constants are calculated, and the bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and anisotropy factor of polycrystalline materials are deduced. Additionally, the thermodynamic properties were theoretically predicted and discussed.

Protein structure and evolution: are they constrained globally by a principle derived from information theory?

PubMed

Hatton, Leslie; Warr, Gregory

2015-01-01

That the physicochemical properties of amino acids constrain the structure, function and evolution of proteins is not in doubt. However, principles derived from information theory may also set bounds on the structure (and thus also the evolution) of proteins. Here we analyze the global properties of the full set of proteins in release 13-11 of the SwissProt database, showing by experimental test of predictions from information theory that their collective structure exhibits properties that are consistent with their being guided by a conservation principle. This principle (Conservation of Information) defines the global properties of systems composed of discrete components each of which is in turn assembled from discrete smaller pieces. In the system of proteins, each protein is a component, and each protein is assembled from amino acids. Central to this principle is the inter-relationship of the unique amino acid count and total length of a protein and its implications for both average protein length and occurrence of proteins with specific unique amino acid counts. The unique amino acid count is simply the number of distinct amino acids (including those that are post-translationally modified) that occur in a protein, and is independent of the number of times that the particular amino acid occurs in the sequence. Conservation of Information does not operate at the local level (it is independent of the physicochemical properties of the amino acids) where the influences of natural selection are manifest in the variety of protein structure and function that is well understood. Rather, this analysis implies that Conservation of Information would define the global bounds within which the whole system of proteins is constrained; thus it appears to be acting to constrain evolution at a level different from natural selection, a conclusion that appears counter-intuitive but is supported by the studies described herein.

Electronic and crystal structure of NiTi martensite

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

Sanati, M.; Albers, R.C.; Pinski, F.J.

1998-11-01

All of the first-principles electronic-structure calculations for the martensitic structure of NiTi have used the experimental atomic parameters reported by Michal and Sinclair [Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. {bold B37}, 1803 (1981)]. We have used first-principles, full-potential, linear muffin-tin orbital calculations to examine the total energy of all the experimental martensitic structures reported in the literature. We find that another crystal structure, that of Kudoh {ital et al.} [Acta Metall. Mater. {bold 33}, 2049 (1985)], has the lowest total energy at zero temperature. Ground-state and formation energies were calculated for all of the experimental structures. Total andmore » local densities of states were calculated and compared with each other for the structures of both Kudoh {ital et al.} and Michal and Sinclair thinsp {copyright} {ital 1998} {ital The American Physical Society}« less

Principles of assembly reveal a periodic table of protein complexes.

PubMed

Ahnert, Sebastian E; Marsh, Joseph A; Hernández, Helena; Robinson, Carol V; Teichmann, Sarah A

2015-12-11

Structural insights into protein complexes have had a broad impact on our understanding of biological function and evolution. In this work, we sought a comprehensive understanding of the general principles underlying quaternary structure organization in protein complexes. We first examined the fundamental steps by which protein complexes can assemble, using experimental and structure-based characterization of assembly pathways. Most assembly transitions can be classified into three basic types, which can then be used to exhaustively enumerate a large set of possible quaternary structure topologies. These topologies, which include the vast majority of observed protein complex structures, enable a natural organization of protein complexes into a periodic table. On the basis of this table, we can accurately predict the expected frequencies of quaternary structure topologies, including those not yet observed. These results have important implications for quaternary structure prediction, modeling, and engineering. Copyright © 2015, American Association for the Advancement of Science.

First principles study of structural stability, electronic structure and mechanical properties of ReN and TcN

NASA Astrophysics Data System (ADS)

Rajeswarapalanichamy, R.; Kavitha, M.; Sudha Priyanga, G.; Iyakutti, K.

2015-03-01

The crystal structure, structural stability, electronic and mechanical properties of ReN and TcN are investigated using first principles calculations. We have considered five different crystal structures: NaCl, zinc blende (ZB), NiAs, tungsten carbide (WC) and wurtzite (WZ). Among these ZB phase is found to be the lowest energy phase for ReN and TcN at normal pressure. Pressure induced structural phase transitions from ZB to WZ phase at 214 GPa in ReN and ZB to NiAs phase at 171 GPa in TcN are predicted. The electronic structure reveals that both ReN and TcN are metallic in nature. The computed elastic constants indicate that both the nitrides are mechanically stable. As ReN in NiAs phase has high bulk and shear moduli and low Poisson's ratio, it is found to be a potential ultra incompressible super hard material.

First-principles study of high-pressure structural phase transitions of magnesium

NASA Astrophysics Data System (ADS)

Liu, Qiuxiang; Fan, Changzeng; Zhang, Ruijun

2009-06-01

The structural phase transitions for the hcp, bcc, dhcp, and fcc of magnesium at hydrostatic pressures larger than about 200 GPa at zero temperature are studied by first-principles total energy calculations. The plane-wave basis pseudopotential method has been adopted, in which the generalized gradient approximation implanted in the CASTEP code is employed. By comparing the enthalpy differences of the hcp structure with other three structures under different pressures, it can be seen that when the pressure becomes higher than about 65, 130, and 190 GPa, the bcc, dhcp, and fcc structures become more stable relative to the hcp structure, respectively. Due to the lowest enthalpy value of the bcc structure above 65 GPa, it can be deduced that magnesium may transform to the bcc structure from the ground state hcp structure around 65 GPa, but no further phase transitions occur without additionally applying high temperature. In addition, the equation of state of magnesium is calculated, indicating that bcc structure is the softest phase.

Apparatus, system, and method for providing fabric-elastomer composites as pneumatic actuators

DOEpatents

Martinez, Ramses V.; Whitesides, George M.

2017-10-25

Soft pneumatic actuators based on composites consisting of elastomers with embedded sheet or fiber structures (e.g., paper or fabric) that are flexible but not extensible are described. On pneumatic inflation, these actuators move anisotropically, based on the motions accessible by their composite structures. They are inexpensive, simple to fabricate, light in weight, and easy to actuate. This class of structure is versatile: the same principles of design lead to actuators that respond to pressurization with a wide range of motions (bending, extension, contraction, twisting, and others). Paper, when used to introduce anisotropy into elastomers, can be readily folded into three-dimensional structures following the principles of origami; these folded structures increase the stiffness and anisotropy of the elastomeric actuators, while keeping them light in weight.

Hydrologic consistency as a basis for assessing complexity of monthly water balance models for the continental United States

NASA Astrophysics Data System (ADS)

Martinez, Guillermo F.; Gupta, Hoshin V.

2011-12-01

Methods to select parsimonious and hydrologically consistent model structures are useful for evaluating dominance of hydrologic processes and representativeness of data. While information criteria (appropriately constrained to obey underlying statistical assumptions) can provide a basis for evaluating appropriate model complexity, it is not sufficient to rely upon the principle of maximum likelihood (ML) alone. We suggest that one must also call upon a "principle of hydrologic consistency," meaning that selected ML structures and parameter estimates must be constrained (as well as possible) to reproduce desired hydrological characteristics of the processes under investigation. This argument is demonstrated in the context of evaluating the suitability of candidate model structures for lumped water balance modeling across the continental United States, using data from 307 snow-free catchments. The models are constrained to satisfy several tests of hydrologic consistency, a flow space transformation is used to ensure better consistency with underlying statistical assumptions, and information criteria are used to evaluate model complexity relative to the data. The results clearly demonstrate that the principle of consistency provides a sensible basis for guiding selection of model structures and indicate strong spatial persistence of certain model structures across the continental United States. Further work to untangle reasons for model structure predominance can help to relate conceptual model structures to physical characteristics of the catchments, facilitating the task of prediction in ungaged basins.

Aboriginal and Torres Strait Islander community governance of health research: Turning principles into practice.

PubMed

Gwynn, Josephine; Lock, Mark; Turner, Nicole; Dennison, Ray; Coleman, Clare; Kelly, Brian; Wiggers, John

2015-08-01

Gaps exist in researchers' understanding of the 'practice' of community governance in relation to research with Aboriginal and Torres Strait Islander peoples. We examine Aboriginal community governance of two rural NSW research projects by applying principles-based criteria from two independent sources. One research project possessed a strong Aboriginal community governance structure and evaluated a 2-year healthy lifestyle program for children; the other was a 5-year cohort study examining factors influencing the mental health and well-being of participants. The National Health and Medical Research Council of Australia's 'Values and ethics: guidelines for ethical conduct in Aboriginal and Torres Strait Islander research' and 'Ten principles relevant to health research among Indigenous Australian populations' described by experts in the field. Adopt community-based participatory research constructs. Develop clear governance structures and procedures at the beginning of the study and allow sufficient time for their establishment. Capacity-building must be a key component of the research. Ensure sufficient resources to enable community engagement, conduct of research governance procedures, capacity-building and results dissemination. The implementation of governance structures and procedures ensures research addresses the priorities of the participating Aboriginal and Torres Strait Islander communities, minimises risks and improves outcomes for the communities. Principles-based Aboriginal and Torres Strait Islander community governance of research is very achievable. Next steps include developing a comprehensive evidence base for appropriate governance structures and procedures, and consolidating a suite of practical guides for structuring clear governance in health research. © 2015 National Rural Health Alliance Inc.

Leibniz on teleology and the laws of optics

NASA Astrophysics Data System (ADS)

McDonough, Jeffrey Keegan

This essay explores Leibniz's defense of teleology and teleological explanations in the domain of physics in general, and the roles that teleology plays in his studies of optics in particular. I argue first that Leibniz draws upon Plato's defense of final causes to introduce a novel research program intended to steer a middle course, on the one hand, between Aristotelian-Scholasticism and the new mechanical philosophy, and, on the other hand, between Cartesian rationalism and Gassendist empiricism. The implementation of this program leads Leibniz to significant conceptual innovations, as he attempts to reconcile teleological and efficient explanatory frameworks, and important discoveries, as he tries to show how final causes can be used to achieve results in the study of the natural world. Having situated Leibniz's defense of final causes in the broader context of his general philosophy of physics, I turn to a more detailed investigation of the roles that teleology plays in his work in geometrical optics. Interest in final causes leads Leibniz to introduce his "Most Determined Path Principle" from which both of the central laws of geometrical optics may be derived. I argue that Leibniz uses the discovery of such principles to introduce a thin notion of final causation within the order of nature based on teleological laws that link prior events to subsequent events via the likely or expected outcomes of those events, and defend this view against objections made both by Leibniz's contemporaries and our own. I also argue that Leibniz uses the discovery of principles like Most Determined Path Principle to provide a novel connection within his system between considerations of divine perfection and the laws of nature. I defend the internal consistency of this connection, and explore its relations to Leibniz's mature physics, and to his view that the world is governed by two sets of equipotent laws, one teleological and one mechanical.

A 3D Bioprinted Model for the Study of Premalignant Breast Disease

DTIC Science & Technology

2017-05-01

these glands and performed proof-of-principle 3D printing . We have printed simple ductal structures (tubes) and seeded breast epithelial cells. The...performed proof-of-principle 3D printing . We have printed simple ductal structures (tubes) and seeded breast epithelial cells. The next year we will...All of the PN17 reconstruction data from the 5 completed strains has also been sent to the University of Pittsburg for 3D printing . A summary of the

Applications of Lexical Link Analysis Web Service for Large-Scale Automation, Validation, Discovery, Visualization, and Real-Time Program-Awareness

DTIC Science & Technology

2012-04-30

individualistic , Western view of human behavior. That is, it assumes that people adhere to the individualistic principles of Western culture . What happens to...people with networks rich in structural holes that live/work in environments that adhere to other principles, such as those of a collectivistic ... culture ? •http://orgtheory.wordpress.com/2007/06/19/structural-holes-in-context/ Preferential Attachment (PA) [Barabási & Albert, 1999] • The most

Study of the extra-ionic electron distributions in semi-metallic structures by nuclear quadrupole resonance techniques

NASA Technical Reports Server (NTRS)

Murty, A. N.

1976-01-01

A straightforward self-consistent method was developed to estimate solid state electrostatic potentials, fields and field gradients in ionic solids. The method is a direct practical application of basic electrostatics to solid state and also helps in the understanding of the principles of crystal structure. The necessary mathematical equations, derived from first principles, were presented and the systematic computational procedure developed to arrive at the solid state electrostatic field gradients values was given.

Novel active principles from spider venom.

PubMed

Vassilevski, Alexander A; Grishin, Eugene V

2011-12-01

Spiders are one of the most intriguing groups of venomous animals. Substances found in their venom vary from simple inorganic compounds to large multi-domain proteins. In this article, we review some of the latest work presenting active principles that add to the known spider toxin universe. Two aspects of novelty are addressed in particular, structural (novel types of molecules in terms of structure) and functional (novel types of biological targets hit by substances from spider venom and novel mechanisms of action).

First-principles molecular dynamics simulation study on electrolytes for use in redox flow battery

NASA Astrophysics Data System (ADS)

Choe, Yoong-Kee; Tsuchida, Eiji; Tokuda, Kazuya; Ootsuka, Jun; Saito, Yoshihiro; Masuno, Atsunobu; Inoue, Hiroyuki

2017-11-01

Results of first-principles molecular dynamics simulations carried out to investigate structural aspects of electrolytes for use in a redox flow battery are reported. The electrolytes studied here are aqueous sulfuric acid solutions where its property is of importance for dissolving redox couples in redox flow battery. The simulation results indicate that structural features of the acid solutions depend on the concentration of sulfuric acid. Such dependency arises from increase of proton dissociation from sulfuric acid.

Electronic structure and microscopic model of CoNb2O6

NASA Astrophysics Data System (ADS)

Molla, Kaimujjaman; Rahaman, Badiur

2018-05-01

We present the first principle density functional calculations to figure out the underlying spin model of CoNb2O6. The first principles calculations define the main paths of superexchange interaction between Co spins in this compound. We discuss the nature of the exchange paths and provide quantitative estimates of magnetic exchange couplings. A microscopic modeling based on analysis of the electronic structure of this system puts it in the interesting class of weakly couple geometrically frustrated isosceles triangular Ising antiferromagnet.

Alcoholics Anonymous-Related Helping and the Helper Therapy Principle

PubMed Central

Pagano, Maria E.; Post, Stephen G.; Johnson, Shannon M.

2012-01-01

The helper therapy principle (HTP) observes the helper’s health benefits derived from helping another with a shared malady. The HTP is embodied by the program of Alcoholics Anonymous as a method to diminish egocentrism as a root cause of addiction. This article reviews recent evidence of the HTP in alcohol populations, extends to populations with chronic conditions beyond addiction, and concludes with new directions of empirical inquiry. PMID:23525280

A pilot study designed to acquaint medical educators with basic pedagogic principles.

PubMed

McLeod, P J; Brawer, J; Steinert, Y; Chalk, C; McLeod, A

2008-02-01

Faculty development activities in medical schools regularly target teaching behaviours but rarely address basic pedagogic principles underlying those behaviours. Although many teachers have an intuitive or tacit knowledge of basic pedagogic principles, overt knowledge of fundamental educational principles is rare. We conducted a short-term pilot study designed to transform teachers' tacit knowledge into explicit knowledge of pedagogic principles. We hypothesized that conscious awareness of these principles will positively influence their teaching effectiveness. The intervention included a workshop, provision of a workbook on pedagogic principles and free access to educational consultants. For the intervention, we chose a purposive sample of experienced teachers at our medical school. Evaluation of the impact of the intervention using questionnaires and semi-structured interviews revealed three notable findings; 1. Participants were surprised to discover the existence of an extensive body of pedagogic science underlying teaching and learning. 2. They were enthusiastic about the intervention and expressed interest in learning more about basic pedagogic principles. 3. The knowledge acquired had an immediate impact on their teaching.

Indicine-N-oxide: the antitumor principle of Heliotropium indicum.

PubMed

Kugelman, M; Liu, W C; Axelrod, M; McBride, T J; Rao, K V

1976-01-01

Extracts of Heliotropium indicum Linn. (Boraginaceae) showed significant activity in several experimental tumor systems. The active principle is isolated and shown to be the N-oxide of the alkaloid, indicine, previously isolated from this plant. Supporting structural data and anti-tumor data are provided.

Delegation: A Competency of Superior Performers?

DTIC Science & Technology

1982-12-01

subordinate, distribution of power and responsibility. Henri Fayol does no better with this subject in his classic fourteen principles of management . He...Structure and Behavior, Litterer, Joseph A., Wiley and Sons, Inc., New York, 1963. 4. Fayol, Henri, "General Principles of Management ", from Classics

Ethical aspects of limiting residents' work hours.

PubMed

Wiesing, Urban

2007-09-01

The regulation of residents' work hours involves several ethical conflicts which need to be systematically analysed and evaluated. ARGUMENTS AND CONCLUSION: The most important ethical principle when regulating work hours is to avoid the harm resulting from the over-work of physicians and from an excessive division of labour. Additionally, other ethical principles have to be taken into account, in particular the principles of nonmaleficence and beneficence for future patients and for physicians. The article presents arguments for balancing the relevant ethical principles and analyses the structural difficulties that occur unavoidably in any regulation of the complex activities of physicians.

Shallow Acceptor State in Mg-Doped CuAlO2 and Its Effect on Electrical and Optical Properties: An Experimental and First-Principles Study.

PubMed

Liu, Ruijian; Li, Yongfeng; Yao, Bin; Ding, Zhanhui; Jiang, Yuhong; Meng, Lei; Deng, Rui; Zhang, Ligong; Zhang, Zhenzhong; Zhao, Haifeng; Liu, Lei

2017-04-12

Shallow acceptor states in Mg-doped CuAlO 2 and their effect on structural, electrical, and optical properties are investigated by combining first-principles calculations and experiments. First-principles calculations demonstrate that Mg substituting at the Al site in CuAlO 2 plays the role of shallow acceptor and has a low formation energy, suggesting that Mg doping can increase hole concentration and improve the conductivity of CuAlO 2 . Hall effect measurements indicate that the hole concentration of the Mg-doped CuAlO 2 thin film is 2 orders of magnitude higher than that of undoped CuAlO 2 . The best room temperature conductivity of 8.0 × 10 -2 S/cm is obtained. A band gap widening is observed in the optical absorption spectra of Mg-doped CuAlO 2 , which is well supported by the results from first-principles electronic structure calculations.

An ambiguity principle for assigning protein structural domains

PubMed Central

Postic, Guillaume; Ghouzam, Yassine; Chebrek, Romain; Gelly, Jean-Christophe

2017-01-01

Ambiguity is the quality of being open to several interpretations. For an image, it arises when the contained elements can be delimited in two or more distinct ways, which may cause confusion. We postulate that it also applies to the analysis of protein three-dimensional structure, which consists in dividing the molecule into subunits called domains. Because different definitions of what constitutes a domain can be used to partition a given structure, the same protein may have different but equally valid domain annotations. However, knowledge and experience generally displace our ability to accept more than one way to decompose the structure of an object—in this case, a protein. This human bias in structure analysis is particularly harmful because it leads to ignoring potential avenues of research. We present an automated method capable of producing multiple alternative decompositions of protein structure (web server and source code available at www.dsimb.inserm.fr/sword/). Our innovative algorithm assigns structural domains through the hierarchical merging of protein units, which are evolutionarily preserved substructures that describe protein architecture at an intermediate level, between domain and secondary structure. To validate the use of these protein units for decomposing protein structures into domains, we set up an extensive benchmark made of expert annotations of structural domains and including state-of-the-art domain parsing algorithms. The relevance of our “multipartitioning” approach is shown through numerous examples of applications covering protein function, evolution, folding, and structure prediction. Finally, we introduce a measure for the structural ambiguity of protein molecules. PMID:28097215

Computing the structural influence matrix for biological systems.

PubMed

Giordano, Giulia; Cuba Samaniego, Christian; Franco, Elisa; Blanchini, Franco

2016-06-01

We consider the problem of identifying structural influences of external inputs on steady-state outputs in a biological network model. We speak of a structural influence if, upon a perturbation due to a constant input, the ensuing variation of the steady-state output value has the same sign as the input (positive influence), the opposite sign (negative influence), or is zero (perfect adaptation), for any feasible choice of the model parameters. All these signs and zeros can constitute a structural influence matrix, whose (i, j) entry indicates the sign of steady-state influence of the jth system variable on the ith variable (the output caused by an external persistent input applied to the jth variable). Each entry is structurally determinate if the sign does not depend on the choice of the parameters, but is indeterminate otherwise. In principle, determining the influence matrix requires exhaustive testing of the system steady-state behaviour in the widest range of parameter values. Here we show that, in a broad class of biological networks, the influence matrix can be evaluated with an algorithm that tests the system steady-state behaviour only at a finite number of points. This algorithm also allows us to assess the structural effect of any perturbation, such as variations of relevant parameters. Our method is applied to nontrivial models of biochemical reaction networks and population dynamics drawn from the literature, providing a parameter-free insight into the system dynamics.

Concentration of small ring structures in vitreous silica from a first-principles analysis of the Raman spectrum.

PubMed

Umari, P; Gonze, Xavier; Pasquarello, Alfredo

2003-01-17

Using a first-principles approach, we calculate Raman spectra for a model structure of vitreous silica. We develop a perturbational method for calculating the dielectric tensor in an ultrasoft pseudopotential scheme and obtain Raman coupling tensors by finite differences with respect to atomic displacements. For frequencies below 1000 cm(-1), the parallel-polarized Raman spectrum of vitreous silica is dominated by oxygen bending motions, showing a strong sensitivity to the intermediate range structure. By modeling the Raman coupling, we derive estimates for the concentrations of three- and four-membered rings from the experimental intensities of the Raman defect lines.

First principles investigation of structural, vibrational and thermal properties of black and blue phosphorene

NASA Astrophysics Data System (ADS)

Arif Khalil, R. M.; Ahmad, Javed; Rana, Anwar Manzoor; Bukhari, Syed Hamad; Tufiq Jamil, M.; Tehreem, Tuba; Nissar, Umair

2018-05-01

In this investigation, structural, dynamical and thermal properties of black and blue phosphorene (P) are presented through the first principles calculations based on the density functional theory (DFT). These DFT calculations depict that due to the approximately same values of ground state energy at zero Kelvin and Helmholtz free energy at room-temperature, it is expected that both structures can coexist at transition temperature. Lattice dynamics of both phases were investigated by using the finite displacement supercell approach. It is noticed on the basis of harmonic approximation thermodynamic calculations that the blue phase is thermodynamically more stable than the black phase above 155 K.

THE STRUCTURE, MAGNETISM AND CONDUCTIVITY OF Li3V2(PO4)3: A THEORETICAL AND EXPERIMENTAL STUDY

NASA Astrophysics Data System (ADS)

Lin, Zhi-Ping; Zhao, Yu-Jun; Zhao, Yan-Ming

2013-10-01

In this paper, we present a combination of first-principles and experimental investigations on the structural, magnetic and electronic properties of monoclinic Li3V2(PO4)3. The change of dielectric constant indicates that the structural phase transition appear around the temperature 120°C. The first-principles calculation and magnetic measurement display that Li3V2(PO4)3 is a compound with weak ferromagnetism, with Curie constant of C = 0.004 and Curie temperature of 140 K. The experimental and theoretical results demonstrated that the Li3V2(PO4)3 is a typical semiconductor.

First principles calculation of material properties of group IV elements and III-V compounds

NASA Astrophysics Data System (ADS)

Malone, Brad Dean

This thesis presents first principles calculations on the properties of group IV elements and group III-V compounds. It includes investigations into what structure a material is likely to form in, and given that structure, what are its electronic, optical, and lattice dynamical properties as well as what are the properties of defects that might be introduced into the sample. The thesis is divided as follows: • Chapter 1 contains some of the conceptual foundations used in the present work. These involve the major approximations which allow us to approach the problem of systems with huge numbers of interacting electrons and atomic cores. • Then, in Chapter 2, we discuss one of the major limitations to the DFT formalism introduced in Chapter 1, namely its inability to predict the quasiparticle spectra of materials and in particular the band gap of a semiconductor. We introduce a Green's function approach to the electron self-energy Sigma known as the GW approximation and use it to compute the quasiparticle band structures of a number of group IV and III-V semiconductors. • In Chapter 3 we present a first-principles study of a number of high-pressure metastable phases of Si with tetrahedral bonding. The phases studied include all experimentally determined phases that result from decompression from the metallic beta-Sn phase, specifically the BC8 (Si-III), hexagonal diamond (Si-IV), and R8 (Si-XII). In addition to these, we also study the hypothetical ST12 structure found upon decompression from beta-Sn in germanium. • Our attention is then turned to the first principles calculations of optical properties in Chapter 4. The Bethe-Salpeter equation is then solved to obtain the optical spectrum of this material including electron-hole interactions. The calculated optical spectrum is compared with experimental data for other forms of silicon commonly used in photovoltaic devices, namely the cubic, polycrystalline, and amorphous forms. • In Chapter 5 we present first principles calculations of the quasiparticle and optical excitation spectra of recently predicted silicon and germanium polytypes in the body-centered-tetragonal (bct) structure. The quasiparticle spectra calculated within the GW approximation predict that both silicon and germanium in the bct structure are small band gap materials. The optical spectra are then evaluated by solving the Bethe-Salpeter equation taking into account. • We examine the low-pressure phases of Ge in Chapter 6 by performing first principles calculations of the electronic structure and lattice dynamics of the R8, BC8, ST12, and hexagonal diamond structures of Ge. To aid future experimental investigation, we include predictions of the Raman-active frequencies of these phases as well as present the full phonon dispersion throughout the zone. • In Chapter 7 we demonstrate how first principles calculations can be used to predict new structures. In a study aimed at finding new useful forms of silicon, we use an ab initio random structure searching (AIRSS) method to identify a new phase of silicon in the Ibamstructure. The Ibam phase is found to be semimetallic within density functional theory with a small band overlap, and it is expected that quasiparticle corrections using the GW approximation would yield a semiconducting state with a small band gap. • We present a first-principles study of boron and phosphorus substitutional defects in Si-XII in Chapter 8. Recent result from nanoindentation experiments reveal that the Si-XII phase is semiconducting and has the interesting property that it can be doped n- and p-type at room temperature without an annealing step. Using the hybrid functional of Heyd, Scuseria, and Ernzerhof (HSE), we examine the formation energies of the B and P defects at the two distinct atomic sites in Si-XII to find on which site the substitutional defects are more easily accommodated. We also estimate the thermodynamic transition levels of each defect in its relevant charge states. (Abstract shortened by UMI.).

The role of syllabic structure in French visual word recognition.

PubMed

Rouibah, A; Taft, M

2001-03-01

Two experiments are reported in which the processing units involved in the reading of French polysyllabic words are examined. A comparison was made between units following the maximal onset principle (i.e., the spoken syllable) and units following the maximal coda principle (i.e., the basic orthographic syllabic structure [BOSS]). In the first experiment, it took longer to recognize that a syllable was the beginning of a word (e.g., the FOE of FOETUS) than to make the same judgment of a BOSS (e.g., FOET). The fact that a BOSS plus one letter (e.g., FOETU) also took longer to judge than the BOSS indicated that the maximal coda principle applies to the units of processing in French. The second experiment confirmed this, using a lexical decision task with the different units being demarcated on the basis of color. It was concluded that the syllabic structure that is so clearly manifested in the spoken form of French is not involved in visual word recognition.

Physics of the gut: How polymers dynamically structure the gut environment

NASA Astrophysics Data System (ADS)

Preska Steinberg, Asher; Datta, Sujit; Bogatyrev, Said; Ismagilov, Rustem

While the gut microbiome and biological regulation of the gut environment is being exhaustively studied by the microbiology community, little is known about the rich physics that governs the macro- and microstructure of the gut environment. The mammalian gut abounds in soft materials; ranging from soluble polymers (e.g. dietary fibers, therapeutic polymers and mucins) to colloidal matter (e.g. bacteria, viruses and nanoparticles carrying drugs). We have found experimentally that soluble polymers can dynamically re-structure the colonic mucus hydrogel by modulating its degree of swelling. We implemented a mean-field Flory-Huggins model to reveal that these polymer-mucus interactions can be captured using a simple, first principles thermodynamics model. In this model, the amount of deswelling increases with polymer concentration and size. We then used these physical principles to make predictions about how different polymer solutions affect the structure of mucus. Lastly, we explore applying this framework and similar physical principles to a variety of biological problems in the gut.

Concept of dynamic memory in economics

NASA Astrophysics Data System (ADS)

Tarasova, Valentina V.; Tarasov, Vasily E.

2018-02-01

In this paper we discuss a concept of dynamic memory and an application of fractional calculus to describe the dynamic memory. The concept of memory is considered from the standpoint of economic models in the framework of continuous time approach based on fractional calculus. We also describe some general restrictions that can be imposed on the structure and properties of dynamic memory. These restrictions include the following three principles: (a) the principle of fading memory; (b) the principle of memory homogeneity on time (the principle of non-aging memory); (c) the principle of memory reversibility (the principle of memory recovery). Examples of different memory functions are suggested by using the fractional calculus. To illustrate an application of the concept of dynamic memory in economics we consider a generalization of the Harrod-Domar model, where the power-law memory is taken into account.

Addressing refractive error visual impairment: volunteer organisations' alignment with Vision 2020 and public health principles.

PubMed

Pearce, Matthew G; Pearce, Nicole

2012-11-01

Eye care professionals have been making short visits to developing countries for decades in an effort to reduce visual impairment caused by refractive error. A 2006 survey revealed that volunteer organisations were not working within the Vision 2020 framework. Recommendations were made for volunteer organisations that would better align their work with accepted Vision 2020 and public health principles. This study re-evaluates the alignment of volunteer organisations with Vision 2020 and public health principles. To determine their philosophies and methods, a web-based survey was sent to 89 volunteer organisations identified from an internet search. The response rate was 48 per cent. Many (70.7 per cent) organisations exclusively mention direct service provision in their statement of purpose, often provided by student volunteers (75.6 per cent). A few (19.5 per cent) provide short training in refraction, not necessarily following best principles. The majority (82.1 per cent) dispenses recycled spectacles and many use medications not on national essential drug lists. Few attempt to follow aid effectiveness principles with only 26.8 per cent stating they follow Vision 2020 country plans. Overall, as in 2006, the work of these organisations is largely not in alignment with Vision 2020 and public health principles. Organisations interested in decreasing visual impairment due to refractive error in the developing world are encouraged to transition to organisations that not only recognise but also implement public health principles. This should include reprioritisation of their work to developing human resources and infrastructure, determining the burden and causes of disease, assisting in the training of mid-level personnel and providing professional and community education, collaborating via partnerships, discontinuing the use of recycled spectacles and inappropriate medications, and evaluating their outcomes. Following these recommendations as well as creating a better alignment with public health principles in general will increase the likelihood that their programs will be effective in decreasing visual impairment due to refractive error in the developing world. © 2012 The Authors. Clinical and Experimental Optometry © 2012 Optometrists Association Australia.

First principles molecular dynamics of molten NaCl

NASA Astrophysics Data System (ADS)

Galamba, N.; Costa Cabral, B. J.

2007-03-01

First principles Hellmann-Feynman molecular dynamics (HFMD) results for molten NaCl at a single state point are reported. The effect of induction forces on the structure and dynamics of the system is studied by comparison of the partial radial distribution functions and the velocity and force autocorrelation functions with those calculated from classical MD based on rigid-ion and shell-model potentials. The first principles results reproduce the main structural features of the molten salt observed experimentally, whereas they are incorrectly described by both rigid-ion and shell-model potentials. Moreover, HFMD Green-Kubo self-diffusion coefficients are in closer agreement with experimental data than those predicted by classical MD. A comprehensive discussion of MD results for molten NaCl based on different ab initio parametrized polarizable interionic potentials is also given.

Chemical expansion affected oxygen vacancy stability in different oxide structures from first principles calculations

DOE PAGES

Aidhy, Dilpuneet S.; Liu, Bin; Zhang, Yanwen; ...

2015-01-21

We study the chemical expansion for neutral and charged oxygen vacancies in fluorite, rocksalt, perovskite and pyrochlores materials using first principles calculations. We show that the neutral oxygen vacancy leads to lattice expansion whereas the charged vacancy leads to lattice contraction. In addition, we show that there is a window of strain within which an oxygen vacancy is stable; beyond that range, the vacancy can become unstable. Using CeO 2|ZrO 2 interface structure as an example, we show that the concentration of oxygen vacancies can be manipulated via strain, and the vacancies can be preferentially stabilized. Furthermore, these results couldmore » serve as guiding principles in predicting oxygen vacancy stability in strained systems and in the design of vacancy stabilized materials.« less

A hotspot model for leaf canopies

NASA Technical Reports Server (NTRS)

Jupp, David L. B.; Strahler, Alan H.

1991-01-01

The hotspot effect, which provides important information about canopy structure, is modeled using general principles of environmental physics as driven by parameters of interest in remote sensing, such as leaf size, leaf shape, leaf area index, and leaf angle distribution. Specific examples are derived for canopies of horizontal leaves. The hotspot effect is implemented within the framework of the model developed by Suits (1972) for a canopy of leaves to illustrate what might occur in an agricultural crop. Because the hotspot effect arises from very basic geometrical principles and is scale-free, it occurs similarly in woodlands, forests, crops, rough soil surfaces, and clouds. The scaling principles advanced are also significant factors in the production of image spatial and angular variance and covariance which can be used to assess land cover structure through remote sensing.

A Study of the Program Management Responsibility Transfer Process for the F-16.

DTIC Science & Technology

1975-09-01

Guidance . . . ... 19 Subjective Criteria. .......... 21 Criteria Based on the Principles of Management ....... ........... ... 27 Planning...26 GSM/SM/75S-8 and then they will be fitted to the management structure of the two commands and IIQ USAF. Criteria Based on the Principles Of Management From...with each of these ýunc- tional areas with emphasis on some of the principles of management that are (in the writer’s opinion) important to the PMRT

Interactions between C and Cu atoms in single-layer graphene: direct observation and modelling.

PubMed

Kano, Emi; Hashimoto, Ayako; Kaneko, Tomoaki; Tajima, Nobuo; Ohno, Takahisa; Takeguchi, Masaki

2016-01-07

Metal doping into the graphene lattice has been studied recently to develop novel nanoelectronic devices and to gain an understanding of the catalytic activities of metals in nanocarbon structures. Here we report the direct observation of interactions between Cu atoms and single-layer graphene by transmission electron microscopy. We document stable configurations of Cu atoms in the graphene sheet and unique transformations of graphene promoted by Cu atoms. First-principles calculations based on density functional theory reveal a reduction of energy barrier that caused rotation of C-C bonds near Cu atoms. We discuss two driving forces, electron irradiation and in situ heating, and conclude that the observed transformations were mainly promoted by electron irradiation. Our results suggest that individual Cu atoms can promote reconstruction of single-layer graphene.

Broken symmetry phase transition in solid p-H 2, o-D 2 and HD: crystal field effects

NASA Astrophysics Data System (ADS)

Freiman, Yu. A.; Hemley, R. J.; Jezowski, A.; Tretyak, S. M.

1999-04-01

We report the effect of the crystal field (CF) on the broken symmetry phase transition (BSP) in solid parahydrogen, orthodeuterium, and hydrogen deuteride. The CF was calculated taking into account a distortion from the ideal HCP structure. We find that, in addition to the molecular field generated by the coupling terms in the intermolecular potential, the Hamiltonian of the system contains a crystal-field term, originating from single-molecular terms in the intermolecular potential. Ignoring the CF is the main cause of the systematic underestimation of the transition pressure, characteristic of published theories of the BSP transition. The distortion of the lattice that gives rise to the negative CF in response to the applied pressure is in accord with the general Le Chatelier-Braun principle.

Functionalization and migration of bromine adatoms on zigzag graphene nanoribbons: A first-principles study

NASA Astrophysics Data System (ADS)

Jaiswal, Neeraj K.; Kumar, Amit; Patel, Chandrabhan

2018-05-01

Tailoring the electronic band gap of graphene nanoribbons (GNR) through edge functionalization and understanding the adsorption of guest adatoms on GNR is crucial for realization of upcoming organic devices. In the present work, we have investigated the structural stability and electronic property of bromine (Br) termination at the edges of zigzag GNR (ZGNR). The migration pathways of Br adatom on ZGNR have also been discussed along four different diffusion paths. It is revealed that Br termination induces metallicity in ZGNR and caused upward shifting of Fermi level. Further, the migration is predicted to take place preferable along the ribbon edges whereas across the ribbon width, migration is least probable to take place due to sufficiently higher migration barrier of ˜160 meV.

Numerical model for learning concepts of streamflow simulation

USGS Publications Warehouse

DeLong, L.L.; ,

1993-01-01

Numerical models are useful for demonstrating principles of open-channel flow. Such models can allow experimentation with cause-and-effect relations, testing concepts of physics and numerical techniques. Four PT is a numerical model written primarily as a teaching supplement for a course in one-dimensional stream-flow modeling. Four PT options particularly useful in training include selection of governing equations, boundary-value perturbation, and user-programmable constraint equations. The model can simulate non-trivial concepts such as flow in complex interconnected channel networks, meandering channels with variable effective flow lengths, hydraulic structures defined by unique three-parameter relations, and density-driven flow.The model is coded in FORTRAN 77, and data encapsulation is used extensively to simplify maintenance and modification and to enhance the use of Four PT modules by other programs and programmers.

Proposed principles of maximum local entropy production.

PubMed

Ross, John; Corlan, Alexandru D; Müller, Stefan C

2012-07-12

Articles have appeared that rely on the application of some form of "maximum local entropy production principle" (MEPP). This is usually an optimization principle that is supposed to compensate for the lack of structural information and measurements about complex systems, even systems as complex and as little characterized as the whole biosphere or the atmosphere of the Earth or even of less known bodies in the solar system. We select a number of claims from a few well-known papers that advocate this principle and we show that they are in error with the help of simple examples of well-known chemical and physical systems. These erroneous interpretations can be attributed to ignoring well-established and verified theoretical results such as (1) entropy does not necessarily increase in nonisolated systems, such as "local" subsystems; (2) macroscopic systems, as described by classical physics, are in general intrinsically deterministic-there are no "choices" in their evolution to be selected by using supplementary principles; (3) macroscopic deterministic systems are predictable to the extent to which their state and structure is sufficiently well-known; usually they are not sufficiently known, and probabilistic methods need to be employed for their prediction; and (4) there is no causal relationship between the thermodynamic constraints and the kinetics of reaction systems. In conclusion, any predictions based on MEPP-like principles should not be considered scientifically founded.

Research and exploration of product innovative design for function

NASA Astrophysics Data System (ADS)

Wang, Donglin; Wei, Zihui; Wang, Youjiang; Tan, Runhua

2009-07-01

Products innovation is under the prerequisite of realizing the new function, the realization of the new function must solve the contradiction. A new process model of new product innovative design was proposed based on Axiomatic Design (AD) Theory and Functional Structure Analysis (FSA), imbedded Principle of Solving Contradiction. In this model, employ AD Theory to guide FSA, determine the contradiction for the realization of the principle solution. To provide powerful support for innovative design tools in principle solution, Principle of Solving Contradiction in the model were imbedded, so as to boost up the innovation of principle solution. As a case study, an innovative design of button battery separator paper punching machine has been achieved with application of the proposed model.

School Attendance Problems: Using the TQM Tools To Identify Root Causes.

ERIC Educational Resources Information Center

Weller, L. David

2000-01-01

Deming's principles and TQM problem-solving tools and techniques can be used to solve noninstructional problems such as vandalism, dropouts, and student absenteeism. This case study presents a model for principals to apply to identify root causes, resolve problems, and provide quality outcomes (at reduced cost) in noninstructional areas. (Contains…

[Most common skin disorders caused by excessive exposure to sunlight].

PubMed

Zitás, Éva; Mészáros, Judit

2016-01-17

The healing properties of sunlight has been known for millennia, however the gradual deterioration of the ozone layer and the increased use of sun tanning beds in recent decades are causing an increase in skin damaging ultraviolet exposure. In this article the most common photodermatoses and the principles of their treatments are reviewed.

Modeling mammary organogenesis from biological first principles: Cells and their physical constraints.

PubMed

Montévil, Maël; Speroni, Lucia; Sonnenschein, Carlos; Soto, Ana M

2016-10-01

In multicellular organisms, relations among parts and between parts and the whole are contextual and interdependent. These organisms and their cells are ontogenetically linked: an organism starts as a cell that divides producing non-identical cells, which organize in tri-dimensional patterns. These association patterns and cells types change as tissues and organs are formed. This contextuality and circularity makes it difficult to establish detailed cause and effect relationships. Here we propose an approach to overcome these intrinsic difficulties by combining the use of two models; 1) an experimental one that employs 3D culture technology to obtain the structures of the mammary gland, namely, ducts and acini, and 2) a mathematical model based on biological principles. The typical approach for mathematical modeling in biology is to apply mathematical tools and concepts developed originally in physics or computer sciences. Instead, we propose to construct a mathematical model based on proper biological principles. Specifically, we use principles identified as fundamental for the elaboration of a theory of organisms, namely i) the default state of cell proliferation with variation and motility and ii) the principle of organization by closure of constraints. This model has a biological component, the cells, and a physical component, a matrix which contains collagen fibers. Cells display agency and move and proliferate unless constrained; they exert mechanical forces that i) act on collagen fibers and ii) on other cells. As fibers organize, they constrain the cells on their ability to move and to proliferate. The model exhibits a circularity that can be interpreted in terms of closure of constraints. Implementing the mathematical model shows that constraints to the default state are sufficient to explain ductal and acinar formation, and points to a target of future research, namely, to inhibitors of cell proliferation and motility generated by the epithelial cells. The success of this model suggests a step-wise approach whereby additional constraints imposed by the tissue and the organism could be examined in silico and rigorously tested by in vitro and in vivo experiments, in accordance with the organicist perspective we embrace. Copyright © 2016. Published by Elsevier Ltd.

Modeling mammary organogenesis from biological first principles: Cells and their physical constraints

PubMed Central

Montévil, Maël; Speroni, Lucia; Sonnenschein, Carlos; Soto, Ana M.

2017-01-01

In multicellular organisms, relations among parts and between parts and the whole are contextual and interdependent. These organisms and their cells are ontogenetically linked: an organism starts as a cell that divides producing non-identical cells, which organize in tri-dimensional patterns. These association patterns and cells types change as tissues and organs are formed. This contextuality and circularity makes it difficult to establish detailed cause and effect relationships. Here we propose an approach to overcome these intrinsic difficulties by combining the use of two models; 1) an experimental one that employs 3D culture technology to obtain the structures of the mammary gland, namely, ducts and acini, and 2) a mathematical model based on biological principles. The typical approach for mathematical modeling in biology is to apply mathematical tools and concepts developed originally in physics or computer sciences. Instead, we propose to construct a mathematical model based on proper biological principles. Specifically, we use principles identified as fundamental for the elaboration of a theory of organisms, namely i) the default state of cell proliferation with variation and motility and ii) the principle of organization by closure of constraints. This model has a biological component, the cells, and a physical component, a matrix which contains collagen fibers. Cells display agency and move and proliferate unless constrained; they exert mechanical forces that i) act on collagen fibers and ii) on other cells. As fibers organize, they constrain the cells on their ability to move and to proliferate. The model exhibits a circularity that can be interpreted in terms of closure of constraints. Implementing the mathematical model shows that constraints to the default state are sufficient to explain ductal and acinar formation, and points to a target of future research, namely, to inhibitors of cell proliferation and motility generated by the epithelial cells. The success of this model suggests a step-wise approach whereby additional constraints imposed by the tissue and the organism could be examined in silico and rigorously tested by in vitro and in vivo experiments, in accordance with the organicist perspective we embrace. PMID:27544910

The Principle of General Tovariance

NASA Astrophysics Data System (ADS)

Heunen, C.; Landsman, N. P.; Spitters, B.

2008-06-01

We tentatively propose two guiding principles for the construction of theories of physics, which should be satisfied by a possible future theory of quantum gravity. These principles are inspired by those that led Einstein to his theory of general relativity, viz. his principle of general covariance and his equivalence principle, as well as by the two mysterious dogmas of Bohr's interpretation of quantum mechanics, i.e. his doctrine of classical concepts and his principle of complementarity. An appropriate mathematical language for combining these ideas is topos theory, a framework earlier proposed for physics by Isham and collaborators. Our principle of general tovariance states that any mathematical structure appearing in the laws of physics must be definable in an arbitrary topos (with natural numbers object) and must be preserved under so-called geometric morphisms. This principle identifies geometric logic as the mathematical language of physics and restricts the constructions and theorems to those valid in intuitionism: neither Aristotle's principle of the excluded third nor Zermelo's Axiom of Choice may be invoked. Subsequently, our equivalence principle states that any algebra of observables (initially defined in the topos Sets) is empirically equivalent to a commutative one in some other topos.

Causal learning with local computations.

PubMed

Fernbach, Philip M; Sloman, Steven A

2009-05-01

The authors proposed and tested a psychological theory of causal structure learning based on local computations. Local computations simplify complex learning problems via cues available on individual trials to update a single causal structure hypothesis. Structural inferences from local computations make minimal demands on memory, require relatively small amounts of data, and need not respect normative prescriptions as inferences that are principled locally may violate those principles when combined. Over a series of 3 experiments, the authors found (a) systematic inferences from small amounts of data; (b) systematic inference of extraneous causal links; (c) influence of data presentation order on inferences; and (d) error reduction through pretraining. Without pretraining, a model based on local computations fitted data better than a Bayesian structural inference model. The data suggest that local computations serve as a heuristic for learning causal structure. Copyright 2009 APA, all rights reserved.

Acoustic levitation and the Boltzmann-Ehrenfest principle

NASA Technical Reports Server (NTRS)

Putterman, S.; Rudnick, Joseph; Barmatz, M.

1989-01-01

The Boltzmann-Ehrenfest principle of adiabatic invariance relates the acoustic potential acting on a sample positioned in a single-mode cavity to the shift in resonant frequency caused by the presence of this sample. This general and simple relation applies to samples and cavities of arbitrary shape, dimension, and compressibility. Positioning forces and torques can, therefore, be determined from straightforward measurements of frequency shifts. Applications to the Rayleigh disk phenomenon and levitated cylinders are presented.

JPRS Report, East Europe.

DTIC Science & Technology

1991-06-10

this would degrade the Federal Assembly and turn it into the legislative department of some office. Give us certain principles, we will adapt them...does cause problems of course and this plan has to be adapted to the realities. One major difference between the plan and the realities is that the...Machiavellian sons of devils , intend to at least respect for the time being the fact that in principle, the present coalition received a four year

The U.S. Trade Deficit: Causes, Consequences, and Policy Options

DTIC Science & Technology

2010-07-12

4 For further discussion of the standard model of open economy macroeconomics , see N. Gregory Mankiw , Principles of Economics...index.htm#bop. 7 For a fuller discussion of this analytical framework, see N. Gregory Mankiw , Principles of Economics (Fort Worth, TX: The Dryden Press...record 6.1% in 2006. The size of the U.S. trade deficit is ultimately rooted in macroeconomic conditions at home and abroad. U.S. saving falls short

THE USE OF STRUCTURE-ACTIVITY RELATIONSHIPS IN INTEGRATING THE CHEMISTRY AND TOXICOLOGY OF ENDOCRINE DISRUPTING CHEMICALS

EPA Science Inventory

Structure activity relationships (SARs) are based on the principle that structurally similar chemicals should have similar biological activity. SARs relate specifically-defined toxicological activity of chemicals to their molecular structure and physico-chemical properties. To de...

A hybrid computational-experimental approach for automated crystal structure solution

NASA Astrophysics Data System (ADS)

Meredig, Bryce; Wolverton, C.

2013-02-01

Crystal structure solution from diffraction experiments is one of the most fundamental tasks in materials science, chemistry, physics and geology. Unfortunately, numerous factors render this process labour intensive and error prone. Experimental conditions, such as high pressure or structural metastability, often complicate characterization. Furthermore, many materials of great modern interest, such as batteries and hydrogen storage media, contain light elements such as Li and H that only weakly scatter X-rays. Finally, structural refinements generally require significant human input and intuition, as they rely on good initial guesses for the target structure. To address these many challenges, we demonstrate a new hybrid approach, first-principles-assisted structure solution (FPASS), which combines experimental diffraction data, statistical symmetry information and first-principles-based algorithmic optimization to automatically solve crystal structures. We demonstrate the broad utility of FPASS to clarify four important crystal structure debates: the hydrogen storage candidates MgNH and NH3BH3; Li2O2, relevant to Li-air batteries; and high-pressure silane, SiH4.

Total Quality Management for Schools.

ERIC Educational Resources Information Center

Greenwood, Malcolm S.; Gaunt, Helen J.

Education in the United Kingdom has been shaped by the advent of local school management and the rapid growth of grant-maintained schools. Total Quality Management (TQM) offers a new way of looking at management principles and structures by identifying the needs of both internal and external customers. This book applies principles of TQM…

Efficient Predictions of Excited State for Nanomaterials Using Aces 3 and 4

DTIC Science & Technology

2017-12-20

by first-principle methods in the software package ACES by using large parallel computers, growing tothe exascale. 15. SUBJECT TERMS Computer...modeling, excited states, optical properties, structure, stability, activation barriers first principle methods , parallel computing 16. SECURITY...2 Progress with new density functional methods

The Application of Tissue Engineering Procedures to Repair the Larynx

ERIC Educational Resources Information Center

Ringel, Robert L.; Kahane, Joel C.; Hillsamer, Peter J.; Lee, Annie S.; Badylak, Stephen F.

2006-01-01

The field of tissue engineering/regenerative medicine combines the quantitative principles of engineering with the principles of the life sciences toward the goal of reconstituting structurally and functionally normal tissues and organs. There has been relatively little application of tissue engineering efforts toward the organs of speech, voice,…

Effective Peer Learning: From Principles to Practical Implementation

ERIC Educational Resources Information Center

Topping, Keith; Buchs, Céline; Duran, David; van Keer, Hilde

2017-01-01

Peer learning allows a positive use of differences between pupils, turning them into learning opportunities. Yet education professionals often remain unfamiliar with the principles necessary to guarantee its effectiveness. The aim of this book is to help practitioners establish well-structured and effective peer learning projects using a variety…

Basic Comfort Heating Principles.

ERIC Educational Resources Information Center

Dempster, Chalmer T.

The material in this beginning book for vocational students presents fundamental principles needed to understand the heating aspect of the sheet metal trade and supplies practical experience to the student so that he may become familiar with the process of determining heat loss for average structures. Six areas covered are: (1) Background…

Overemphasis on Perfectly Competitive Markets in Microeconomics Principles Textbooks

ERIC Educational Resources Information Center

Hill, Roderick; Myatt, Anthony

2007-01-01

Microeconomic principles courses focus on perfectly competitive markets far more than other market structures. The authors examine five possible reasons for this but find none of them sufficiently compelling. They conclude that textbook authors should place more emphasis on how economists select appropriate models and test models' predictions…

The Macro and Micro Structure of the Foreign Language Curriculum.

ERIC Educational Resources Information Center

Politzer, Robert L.

A representative six-year foreign language curriculum (grades 7-12) is analyzed and noted to be based on several underlying principles. Difficulties which arise from rigid adherence to certain methodological principles are discussed, particularly those concerning the relationship between audiolingual and writing skills. Suggestions on ways to…

Understanding Phylogenies in Biology: The Influence of a Gestalt Perceptual Principle

ERIC Educational Resources Information Center

Novick, Laura R.; Catley, Kefyn M.

2007-01-01

Cladograms, hierarchical diagrams depicting evolutionary histories among (groups of) species, are commonly drawn in 2 informationally equivalent formats--tree and ladder. The authors hypothesize that these formats are not computationally equivalent because the Gestalt principle of good continuation obscures the hierarchical structure of ladders.…

Sign Language and the Brain: A Review

ERIC Educational Resources Information Center

Campbell, Ruth; MacSweeney, Mairead; Waters, Dafydd

2008-01-01

How are signed languages processed by the brain? This review briefly outlines some basic principles of brain structure and function and the methodological principles and techniques that have been used to investigate this question. We then summarize a number of different studies exploring brain activity associated with sign language processing…

Dirac structures in vakonomic mechanics

NASA Astrophysics Data System (ADS)

Jiménez, Fernando; Yoshimura, Hiroaki

2015-08-01

In this paper, we explore dynamics of the nonholonomic system called vakonomic mechanics in the context of Lagrange-Dirac dynamical systems using a Dirac structure and its associated Hamilton-Pontryagin variational principle. We first show the link between vakonomic mechanics and nonholonomic mechanics from the viewpoints of Dirac structures as well as Lagrangian submanifolds. Namely, we clarify that Lagrangian submanifold theory cannot represent nonholonomic mechanics properly, but vakonomic mechanics instead. Second, in order to represent vakonomic mechanics, we employ the space TQ ×V∗, where a vakonomic Lagrangian is defined from a given Lagrangian (possibly degenerate) subject to nonholonomic constraints. Then, we show how implicit vakonomic Euler-Lagrange equations can be formulated by the Hamilton-Pontryagin variational principle for the vakonomic Lagrangian on the extended Pontryagin bundle (TQ ⊕T∗ Q) ×V∗. Associated with this variational principle, we establish a Dirac structure on (TQ ⊕T∗ Q) ×V∗ in order to define an intrinsic vakonomic Lagrange-Dirac system. Furthermore, we also establish another construction for the vakonomic Lagrange-Dirac system using a Dirac structure on T∗ Q ×V∗, where we introduce a vakonomic Dirac differential. Finally, we illustrate our theory of vakonomic Lagrange-Dirac systems by some examples such as the vakonomic skate and the vertical rolling coin.

Effects of magnetic dopants in (Li0.8M0.2OH )FeSe (M =Fe , Mn, Co): Density functional theory study using a band unfolding technique

NASA Astrophysics Data System (ADS)

Chen, M. X.; Chen, Wei; Zhang, Zhenyu; Weinert, M.

2017-12-01

The effects of Fe dopants on the electronic bands structure of (Li0.8Fe0.2OH )FeSe are investigated by a band unfolding (k -projection) technique and first-principles supercell calculations. Doping 20% Fe into the LiOH layers causes electron donation to the FeSe layers, significantly changing the profile of bands around the Fermi level. Because of the weak bonding between the LiOH and FeSe layers the magnetic configuration of the dopants has only minor effects on the band structure. The electronic bands for the surface FeSe layer of (Li0.8Fe0.2OH )FeSe show noticeable differences compared to those of the inner layers, both in the location of the Fermi level and in details of the bands near the high symmetry points, resulting from different effective doping levels and the broken symmetry at the surface. The band structure for the surface FeSe layer with checkerboard antiferromagnetic order is reasonably consistent with angle-resolved photoemission results. The 3 d transition metals Mn and Co have similar doping effects on the band structure of (LiOH)FeSe.

An optimal baseline selection methodology for data-driven damage detection and temperature compensation in acousto-ultrasonics

NASA Astrophysics Data System (ADS)

Torres-Arredondo, M.-A.; Sierra-Pérez, Julián; Cabanes, Guénaël

2016-05-01

The process of measuring and analysing the data from a distributed sensor network all over a structural system in order to quantify its condition is known as structural health monitoring (SHM). For the design of a trustworthy health monitoring system, a vast amount of information regarding the inherent physical characteristics of the sources and their propagation and interaction across the structure is crucial. Moreover, any SHM system which is expected to transition to field operation must take into account the influence of environmental and operational changes which cause modifications in the stiffness and damping of the structure and consequently modify its dynamic behaviour. On that account, special attention is paid in this paper to the development of an efficient SHM methodology where robust signal processing and pattern recognition techniques are integrated for the correct interpretation of complex ultrasonic waves within the context of damage detection and identification. The methodology is based on an acousto-ultrasonics technique where the discrete wavelet transform is evaluated for feature extraction and selection, linear principal component analysis for data-driven modelling and self-organising maps for a two-level clustering under the principle of local density. At the end, the methodology is experimentally demonstrated and results show that all the damages were detectable and identifiable.

An interactive web-tool for molecular analyses links naturally occurring mutation data with three-dimensional structures of the rhodopsin-like glycoprotein hormone receptors.

PubMed

Kleinau, Gunnar; Kreuchwig, Annika; Worth, Catherine L; Krause, Gerd

2010-06-01

The collection, description and molecular analysis of naturally occurring (pathogenic) mutations are important for understanding the functional mechanisms and malfunctions of biological units such as proteins. Numerous databases collate a huge amount of functional data or descriptions of mutations, but tools to analyse the molecular effects of genetic variations are as yet poorly provided. The goal of this work was therefore to develop a translational web-application that facilitates the interactive linkage of functional and structural data and which helps improve our understanding of the molecular basis of naturally occurring gain- or loss- of function mutations. Here we focus on the human glycoprotein hormone receptors (GPHRs), for which a huge number of mutations are known to cause diseases. We describe new options for interactive data analyses within three-dimensional structures, which enable the assignment of molecular relationships between structure and function. Strikingly, as the functional data are converted into relational percentage values, the system allows the comparison and classification of data from different GPHR subtypes and different experimental approaches. Our new application has been incorporated into a freely available database and website for the GPHRs (http://www.ssfa-gphr.de), but the principle development would also be applicable to other macromolecules.

Glass Forming Ability in Systems with Competing Orderings

NASA Astrophysics Data System (ADS)

Russo, John; Romano, Flavio; Tanaka, Hajime

2018-04-01

Some liquids, if cooled rapidly enough to avoid crystallization, can be frozen into a nonergodic glassy state. The tendency for a material to form a glass when quenched is called "glass-forming ability," and it is of key significance both fundamentally and for materials science applications. Here, we consider liquids with competing orderings, where an increase in the glass-forming ability is signaled by a depression of the melting temperature towards its minimum at triple or eutectic points. With simulations of two model systems where glass-forming ability can be tuned by an external parameter, we are able to interpolate between crystal-forming and glass-forming behavior. We find that the enhancement of the glass-forming ability is caused by an increase in the structural difference between liquid and crystal: stronger competition in orderings towards the melting point minimum makes a liquid structure more disordered (more complex). This increase in the liquid-crystal structure difference can be described by a single adimensional parameter, i.e., the interface energy cost scaled by the thermal energy, which we call the "thermodynamic interface penalty." Our finding may provide a general physical principle for not only controlling the glass-forming ability but also the emergence of glassy behavior of various systems with competing orderings, including orderings of structural, magnetic, electronic, charge, and dipolar origin.

Adopting an ecological view of metropolitan landscape: the case of "three circles" system for ecological construction and restoration in Beijing area.

PubMed

Zhang, Feng; Zhang, Xin-shi

2004-01-01

Ecological construction and restoration for sustainable development are now a driving paradigm. It is increasingly recognized that ecological principles, especially landscape ecology theory, are not only necessary but also essential to maintain the long-term sustainability worldwide. Key landscape ecology principles-element, structure and process, dynamics, heterogeneity, hierarchies, connectivity, place and time were reviewed, and use Beijing area as a case study to illustrate how these principles might be applied to ecological construction and restoration, to eventually achieve sustainability. An example to more effectively incorporate the ecological principles in sustainable planning in China was presented.

Drawing the line in clinical treatment of companion animals: recommendations from an ethics working party.

PubMed

Grimm, Herwig; Bergadano, Alessandra; Musk, Gabrielle C; Otto, Klaus; Taylor, Polly M; Duncan, Juliet Clare

2018-06-09

Modern veterinary medicine offers numerous options for treatment and clinicians must decide on the best one to use. Interventions causing short-term harm but ultimately benefitting the animal are often justified as being in the animal's best interest. Highly invasive clinical veterinary procedures with high morbidity and low success rates may not be in the animal's best interest. A working party was set up by the European College of Veterinary Anaesthesia and Analgesia to discuss the ethics of clinical veterinary practice and improve the approach to ethically challenging clinical cases. Relevant literature was reviewed. The 'best interest principle' was translated into norms immanent to the clinic by means of the 'open question argument'. Clinical interventions with potential to cause harm need ethical justification, and suggest a comparable structure of ethical reflection to that used in the context of in vivo research should be applied to the clinical setting. To structure the ethical debate, pertinent questions for ethical decision-making were identified. These were incorporated into a prototype ethical tool developed to facilitate clinical ethical decision-making. The ethical question 'Where should the line on treatment be drawn' should be replaced by 'How should the line be drawn?' © British Veterinary Association (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Discrimination Enhancement with Transient Feature Analysis of a Graphene Chemical Sensor.

PubMed

Nallon, Eric C; Schnee, Vincent P; Bright, Collin J; Polcha, Michael P; Li, Qiliang

2016-01-19

A graphene chemical sensor is subjected to a set of structurally and chemically similar hydrocarbon compounds consisting of toluene, o-xylene, p-xylene, and mesitylene. The fractional change in resistance of the sensor upon exposure to these compounds exhibits a similar response magnitude among compounds, whereas large variation is observed within repetitions for each compound, causing a response overlap. Therefore, traditional features depending on maximum response change will cause confusion during further discrimination and classification analysis. More robust features that are less sensitive to concentration, sampling, and drift variability would provide higher quality information. In this work, we have explored the advantage of using transient-based exponential fitting coefficients to enhance the discrimination of similar compounds. The advantages of such feature analysis to discriminate each compound is evaluated using principle component analysis (PCA). In addition, machine learning-based classification algorithms were used to compare the prediction accuracies when using fitting coefficients as features. The additional features greatly enhanced the discrimination between compounds while performing PCA and also improved the prediction accuracy by 34% when using linear discrimination analysis.

A small molecule mitigates hearing loss in a mouse model of Usher syndrome III.

PubMed

Alagramam, Kumar N; Gopal, Suhasini R; Geng, Ruishuang; Chen, Daniel H-C; Nemet, Ina; Lee, Richard; Tian, Guilian; Miyagi, Masaru; Malagu, Karine F; Lock, Christopher J; Esmieu, William R K; Owens, Andrew P; Lindsay, Nicola A; Ouwehand, Krista; Albertus, Faywell; Fischer, David F; Bürli, Roland W; MacLeod, Angus M; Harte, William E; Palczewski, Krzysztof; Imanishi, Yoshikazu

2016-06-01

Usher syndrome type III (USH3), characterized by progressive deafness, variable balance disorder and blindness, is caused by destabilizing mutations in the gene encoding the clarin-1 (CLRN1) protein. Here we report a new strategy to mitigate hearing loss associated with a common USH3 mutation CLRN1(N48K) that involves cell-based high-throughput screening of small molecules capable of stabilizing CLRN1(N48K), followed by a secondary screening to eliminate general proteasome inhibitors, and finally an iterative process to optimize structure-activity relationships. This resulted in the identification of BioFocus 844 (BF844). To test the efficacy of BF844, we developed a mouse model that mimicked the progressive hearing loss associated with USH3. BF844 effectively attenuated progressive hearing loss and prevented deafness in this model. Because the CLRN1(N48K) mutation causes both hearing and vision loss, BF844 could in principle prevent both sensory deficiencies in patients with USH3. Moreover, the strategy described here could help identify drugs for other protein-destabilizing monogenic disorders.

In-situ probing of coupled atomic restructuring and metallicity of oxide heterointerfaces induced by polar adsorbates

NASA Astrophysics Data System (ADS)

Ryu, S.; Zhou, H.; Paudel, T. R.; Irwin, J.; Podkaminer, J. P.; Bark, C. W.; Lee, D.; Kim, T. H.; Fong, D. D.; Rzchowski, M. S.; Tsymbal, E. Y.; Eom, C. B.

2017-10-01

Microscopic understanding of the surface-controlled conductivity of the two dimensional electron gas at complex oxide interfaces is crucial for developing functional interfaces. We observe conductivity and structural modification using in-situ synchrotron surface x-ray diffraction as the surface of a model LaAlO3/SrTiO3 (001) heterostructure is changed by polar adsorbates. We find that polar adsorbate-induced interfacial metallicity reduces polar distortions in the LaAlO3 layer. First-principles density functional theory calculations show that surface dipoles introduced by polar adsorbates lead to additional charge transfer and the reduction of polar displacements in the LaAlO3 layer, consistent with the experimental observations. Our study supports that internal structural deformations controlling functionalities can be driven without the application of direct electrical or thermal bias and offers a route to tuning interfacial properties. These results also highlight the important role of in-situ x-ray scattering with atomic resolution in capturing and exploring structural distortions and charge density changes caused by external perturbations such as chemical adsorption, redox reaction, and generation and/or annihilation of surface defects.

First-Principles Investigation of Radiation Induced Defects in SiC and Si.

NASA Astrophysics Data System (ADS)

Windl, Wolfgang; Lenosky, Thomas J.; Kress, Joel D.; Voter, Arthur F.

1997-03-01

SiC shows promise as a structural material for fusion reactors, partly because of its low activation under neutron irradiation. This radiation, however, can cause damage to its crystal structure, thereby degrading its properties. The focus of this work is the understanding of this neutron-induced radiation damage to SiC. Neutrons interact with matter primarily by scattering off nuclei, an event which suddenly imparts energy and momentum to an atom. If enough energy is transferred, this scattering event creates structural damage, such as displacement of the impacted atom from its original position to an interstitial site. We performed quantum molecular dynamics simulations to determine the displacement energy threshold, i.e., the minimum energy transfer required to create damage. To do this, we used the self-consistent Demkov-Ortega-Grumbach-Sankey (DOGS) extension(A. A. Demkov et al.), Phys. Rev. B 52, 1618 (1995). of the Harris-functional local orbital LDA method of Sankey et al. In order to benchmark the quality of our methodology for studying radiation damage, we compare our results to those of calculations employing classical interatomic potentials; furthermore, we performed similar simulations for Si, where experimental data exist.

Non-iridescent structural colors from uniform-sized SiO2 colloids

NASA Astrophysics Data System (ADS)

Topçu, Gökhan; Güner, Tuğrul; Demir, Mustafa M.

2018-05-01

Structural colors have recently attracted interest from diverse fields of research due to their ease of fabrication and eco-friendliness. These types of colors are, in principle, achieved by periodically arranged submicron-diameter colloidal particles. The interaction of light with a structure containing long-range ordered colloidal particles leads to coloration; this usually varies depending on the angle of observation (iridescence). However, the majority of the applications demand constant color that is independent of the viewing angle (non-iridescence). In this work, silica colloids were obtained using the Stöber method at different sizes from 150 to 300 nm in an alcoholic dispersion. The casting of the dispersion on a substrate leaves behind a photonic crystal showing a colorful iridescent film. However, centrifugation and redispersion of the SiO2 particles into fresh solvent may cause the formation of small, aggregated silica domains in the new dispersion. The casting of this dispersion allows for the development of photonic glass, presumably due to the accumulation of aggregates showing stable colloidal film independent of viewing angle. Moreover, depending on the size of the silica colloids, non-iridescent photonic glasses with various colors (violet, blue, green, and orange) are obtained.

Tuning near-gap electronic structure, interface charge transfer and visible light response of hybrid doped graphene and Ag3PO4 composite: Dopant effects

PubMed Central

He, Chao-Ni; Huang, Wei-Qing; Xu, Liang; Yang, Yin-Cai; Zhou, Bing-Xin; Huang, Gui-Fang; Peng, P.; Liu, Wu-Ming

2016-01-01

The enhanced photocatalytic performance of doped graphene (GR)/semiconductor nanocomposites have recently been widely observed, but an understanding of the underlying mechanisms behind it is still out of reach. As a model system to study the dopant effects, we investigate the electronic structures and optical properties of doped GR/Ag3PO4 nanocomposites using the first-principles calculations, demonstrating that the band gap, near-gap electronic structure and interface charge transfer of the doped GR/Ag3PO4(100) composite can be tuned by the dopants. Interestingly, the doping atom and C atoms bonded to dopant become active sites for photocatalysis because they are positively or negatively charged due to the charge redistribution caused by interaction. The dopants can enhance the visible light absorption and photoinduced electron transfer. We propose that the N atom may be one of the most appropriate dopants for the GR/Ag3PO4 photocatalyst. This work can rationalize the available experimental results about N-doped GR-semiconductor composites, and enriches our understanding on the dopant effects in the doped GR-based composites for developing high-performance photocatalysts. PMID:26923338

Bidirectional Coupling between Astrocytes and Neurons Mediates Learning and Dynamic Coordination in the Brain: A Multiple Modeling Approach

PubMed Central

Wade, John J.; McDaid, Liam J.; Harkin, Jim; Crunelli, Vincenzo; Kelso, J. A. Scott

2011-01-01

In recent years research suggests that astrocyte networks, in addition to nutrient and waste processing functions, regulate both structural and synaptic plasticity. To understand the biological mechanisms that underpin such plasticity requires the development of cell level models that capture the mutual interaction between astrocytes and neurons. This paper presents a detailed model of bidirectional signaling between astrocytes and neurons (the astrocyte-neuron model or AN model) which yields new insights into the computational role of astrocyte-neuronal coupling. From a set of modeling studies we demonstrate two significant findings. Firstly, that spatial signaling via astrocytes can relay a “learning signal” to remote synaptic sites. Results show that slow inward currents cause synchronized postsynaptic activity in remote neurons and subsequently allow Spike-Timing-Dependent Plasticity based learning to occur at the associated synapses. Secondly, that bidirectional communication between neurons and astrocytes underpins dynamic coordination between neuron clusters. Although our composite AN model is presently applied to simplified neural structures and limited to coordination between localized neurons, the principle (which embodies structural, functional and dynamic complexity), and the modeling strategy may be extended to coordination among remote neuron clusters. PMID:22242121

The modular architecture of protein-protein binding interfaces.

PubMed

Reichmann, D; Rahat, O; Albeck, S; Meged, R; Dym, O; Schreiber, G

2005-01-04

Protein-protein interactions are essential for life. Yet, our understanding of the general principles governing binding is not complete. In the present study, we show that the interface between proteins is built in a modular fashion; each module is comprised of a number of closely interacting residues, with few interactions between the modules. The boundaries between modules are defined by clustering the contact map of the interface. We show that mutations in one module do not affect residues located in a neighboring module. As a result, the structural and energetic consequences of the deletion of entire modules are surprisingly small. To the contrary, within their module, mutations cause complex energetic and structural consequences. Experimentally, this phenomenon is shown on the interaction between TEM1-beta-lactamase and beta-lactamase inhibitor protein (BLIP) by using multiple-mutant analysis and x-ray crystallography. Replacing an entire module of five interface residues with Ala created a large cavity in the interface, with no effect on the detailed structure of the remaining interface. The modular architecture of binding sites, which resembles human engineering design, greatly simplifies the design of new protein interactions and provides a feasible view of how these interactions evolved.

In-situ probing of coupled atomic restructuring and metallicity of oxide heterointerfaces induced by polar adsorbates

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

Ryu, S.; Zhou, H.; Paudel, T. R.

Microscopic understanding of the surface-controlled conductivity of the two dimensional electron gas at complex oxide interfaces is crucial for developing functional interfaces. We observe conductivity and structural modification using in-situ synchrotron surface x-ray diffraction as the surface of a model LaAlO3/SrTiO3 (001) heterostructure is changed by polar adsorbates. We find that polar adsorbate-induced interfacial metallicity reduces polar distortions in the LaAlO3 layer. First-principles density functional theory calculations show that surface dipoles introduced by polar adsorbates lead to additional charge transfer and the reduction of polar displacements in the LaAlO3 layer, consistent with the experimental observations. Our study supports that internalmore » structural deformations controlling functionalities can be driven without the application of direct electrical or thermal bias and offers a route to tuning interfacial properties. These results also highlight the important role of in-situ x-ray scattering with atomic resolution in capturing and exploring structural distortions and charge density changes caused by external perturbations such as chemical adsorption, redox reaction, and generation and/or annihilation of surface defects.« less

The Equivalence Principle and the Constants of Nature

NASA Astrophysics Data System (ADS)

Damour, Thibault

2009-12-01

We briefly review the various contexts within which one might address the issue of “why” the dimensionless constants of Nature have the particular values that they are observed to have. Both the general historical trend, in physics, of replacing a-priori-given, absolute structures by dynamical entities, and anthropic considerations, suggest that coupling “constants” have a dynamical nature. This hints at the existence of observable violations of the Equivalence Principle at some level, and motivates the need for improved tests of the Equivalence Principle.

Ab-initio study on the absorption spectrum of color change sapphire based on first-principles calculations with considering lattice relaxation-effect

NASA Astrophysics Data System (ADS)

Novita, Mega; Nagoshi, Hikari; Sudo, Akiho; Ogasawara, Kazuyoshi

2018-01-01

In this study, we performed an investigation on α-Al2O3: V3+ material, or the so-called color change sapphire, based on first-principles calculations without referring to any experimental parameter. The molecular orbital (MO) structure was estimated by the one-electron MO calculations using the discrete variational-Xα (DV-Xα) method. Next, the absorption spectra were estimated by the many-electron calculations using the discrete variational multi-electron (DVME) method. The effect of lattice relaxation on the crystal structures was estimated based on the first-principles band structure calculations. We performed geometry optimizations on the pure α-Al2O3 and with the impurity V3+ ion using Cambridge Serial Total Energy Package (CASTEP) code. The effect of energy corrections such as configuration dependence correction and correlation correction was also investigated in detail. The results revealed that the structural change on the α-Al2O3: V3+ resulted from the geometry optimization improved the calculated absorption spectra. By a combination of both the lattice relaxation-effect and the energy correction-effect improve the agreement to the experiment fact.

First-principles phase stability at high temperatures and pressure in Nb 90Zr 10 alloy

DOE PAGES

Landa, A.; Soderlind, P.

2016-08-18

The phase stability of Nb 90Zr 10 alloy at high temperatures and compression is explored by means of first-principles electronic-structure calculations. Utilizing the self-consistent ab initio lattice dynamics (SCAILD) approach in conjunction with density-functional theory, we show that pressure-induced mechanical instability of the body-centered cubic phase, which results in formation of a rhombohedral phase at around 50 GPa, will prevail significant heating. As a result, the body-centered cubic structure will recover before melting at ~1800 K.

Application of fractography to core and outcrop fracture investigations

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

Kulander, B.R.; Barton, C.C.; Dean, S.L.

1979-03-01

Purpose of this paper is to introduce geologists to the principles of fractography, especially those principles that govern the formation of fracture surface structures commonly observed in rocks. A knowledge of the inception mechanics governing the formation of a fracture's tendential and transient structures should provide geologists with a method to distinguish natural from coring-induced and handling-induced fractures in oriented core samples, and show how coring-induced fractures may be assisted in their formation by stresses that can be attributed to the drilling process. 118 figures.

Basic hydraulic principles of open-channel flow

USGS Publications Warehouse

Jobson, Harvey E.; Froehlich, David C.

1988-01-01

The three basic principles of open-channel-flow analysis--the conservation of mass, energy, and momentum--are derived, explained, and applied to solve problems of open-channel flow. These principles are introduced at a level that can be comprehended by a person with an understanding of the principles of physics and mechanics equivalent to that presented in the first college level course of the subject. The reader is assumed to have a working knowledge of algebra and plane geometry as well as some knowledge of calculus. Once the principles have been derived, a number of example applications are presented that illustrate the computation of flow through culverts and bridges, and over structures, such as dams and weirs. Because resistance to flow is a major obstacle to the successful application of the energy principle to open-channel flow, procedures are outlined for the rational selection of flow resistance coefficients. The principle of specific energy is shown to be useful in the prediction of water-surface profiles both in the qualitative and quantitative sense. (USGS)

Structural and electronic properties of LaPd2As2 superconductor: First-principle calculations

NASA Astrophysics Data System (ADS)

Singh, Birender; Kumar, Pradeep

2017-05-01

In present work we have studied electronic and structural properties of superconducting LaPd2As2 compound having collapsed tetragonal structure using first-principle calculations. The band structure calculations show that the LaPd2As2 is metallic consistent with the reported experimental observation, and the density of states plots clearly shows that at the Fermi level major contribution to density of states arises from Pd 4d and As 4p states, unlike the Fe-based superconductors where major contribution at the Fermi level comes from Fe 3d states. The estimated value of electron-phonon coupling is found to be 0.37, which gives the upper bound of superconducting transition temperature of 5K, suggesting the conventional nature of this superconductor.

The precautionary principle within European Union public health policy. The implementation of the principle under conditions of supranationality and citizenship.

PubMed

Antonopoulou, Lila; van Meurs, Philip

2003-11-01

The present study examines the precautionary principle within the parameters of public health policy in the European Union, regarding both its meaning, as it has been shaped by relevant EU institutions and their counterparts within the Member States, and its implementation in practice. In the initial section I concentrate on the methodological question of "scientific uncertainty" concerning the calculation of risk and possible damage. Calculation of risk in many cases justifies the adopting of preventive measures, but, as it is argued, the principle of precaution and its implementation cannot be wholly captured by a logic of calculation; such a principle does not only contain scientific uncertainty-as the preventive principle does-but it itself is generated as a principle by this scientific uncertainty, recognising the need for a society to act. Thus, the implementation of the precautionary principle is also a simultaneous search for justification of its status as a principle. This justification would result in the adoption of precautionary measures against risk although no proof of this principle has been produced based on the "cause-effect" model. The main part of the study is occupied with an examination of three cases from which the stance of the official bodies of the European Union towards the precautionary principle and its implementation emerges: the case of the "mad cows" disease, the case of production and commercialization of genetically modified foodstuffs. The study concludes with the assessment that the effective implementation of the precautionary principle on a European level depends on the emergence of a concerned Europe-wide citizenship and its acting as a mechanism to counteract the material and social conditions that pose risks for human health.

A structured policy review of the principles of professional self-regulation.

PubMed

Benton, D C; González-Jurado, M A; Beneit-Montesinos, J V

2013-03-01

The International Council of Nurses (ICN) has, for many years, based its work on professional self-regulation on a set of 12 principles. These principles are research based and were identified nearly three decades ago. ICN has conducted a number of reviews of the principles; however, changes have been minimal. In the past 5-10 years, a number of authors and governments, often as part of the review of regulatory systems, have started to propose principles to guide the way regulatory frameworks are designed and implemented. These principles vary in number and content. This study examines the current policy literature on principle-based regulation and compares this with the set of principles advocated by the ICN. A systematic search of the literature on principle-based regulation is used as the basis for a qualitative thematic analysis to compare and contrast the 12 principles of self-regulation with more recently published work. A mapping of terms based on a detailed description of the principles used in the various research and policy documents was generated. This mapping forms the basis of a critique of the current ICN principles. A professional self-regulation advocated by the ICN were identified. A revised and extended set of 13 principles is needed if contemporary developments in the field of regulatory frameworks are to be accommodated. These revised principles should be considered for adoption by the ICN to underpin their advocacy work on professional self-regulation. © 2013 The Authors. International Nursing Review © 2013 International Council of Nurses.

First-principles study of graphene under c-HfO{sub 2}(111) layers: Electronic structures and transport properties

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

Kaneko, Tomoaki, E-mail: kaneko@flex.phys.tohoku.ac.jp; Materials Research Consortium for Energy Efficient Electronic Devices; Ohno, Takahisa, E-mail: OHNO.Takahisa@nims.go.jp

2016-08-22

We investigated the electronic properties, stability, and transport of graphene under c-HfO{sub 2}(111) layers by performing first-principles calculations with special attention to the chemical bonding between graphene and HfO{sub 2} surfaces. When the interface of HfO{sub 2}/graphene is terminated by an O layer, the linear dispersion of graphene is preserved and the degradation of transport is suppressed. For other interface structures, HfO{sub 2} is tightly adsorbed on graphene and the transport is strictly limited. In terms of the stability of the interface structures, an O-terminated interface is preferable, which is achieved under an O-deficient condition.

First principle study of transport properties of a graphene nano structure

NASA Astrophysics Data System (ADS)

Kumar, Naveen; Sharma, Munish; Sharma, Jyoti Dhar; Ahluwalia, P. K.

2013-06-01

The first principle quantum transport calculations have been performed for graphene using Tran SIESTA which calculates transport properties using nonequilibrium Green's function method in conjunction with density-functional theory. Transmission functions, electron density of states and current-voltage characteristic have been calculated for a graphene nano structure using graphene electrodes. Transmission function, density of states and projected density of states show a discrete band structure which varies with applied voltage. The value of current is very low for applied voltage between 0.0 V to 5.0 V and lies in the range of pico ampere. In the V-I characteristic current shows non-linear fluctuating pattern with increase in voltage.

Babinet's principle and the band structure of surface waves on patterned metal arrays

NASA Astrophysics Data System (ADS)

Edmunds, J. D.; Taylor, M. C.; Hibbins, A. P.; Sambles, J. R.; Youngs, I. J.

2010-05-01

The microwave response of an array of square metal patches and its complementary structure, an array of square holes, has been experimentally studied. The resonant phenomena, which yield either enhanced transmission or reflection, are attributed to the excitation of diffractively coupled surface waves. The band structure of these surface modes has been quantified for both p-(transverse magnetic) and s-(transverse electric) polarized radiation and is found to be dependent on the periodicity of the electric and magnetic fields on resonance. The results are in excellent accord with predictions from finite element method modeling and the electromagnetic form of Babinet's principle [Babinet, C. R. Acad. Sci. 4, 638 (1837)].

A Review of the Pilot Backache Problem in the CH113 Labrador Helicopter

DTIC Science & Technology

1985-12-01

and increasing the kyphosis may not, by itself, cause a higher incidence of backache. Based on the numerous reports of back pain and observa- tions...regular exer- cise Based on the symptoms identified in the questionnaire and the causes identified by other investigators, design principles for an...helicopter pilots and, the causes of helicopter induced backache. While the prevelnnce of backache is difficult to establish at any given time, consid

Modeling causes of death: an integrated approach using CODEm

PubMed Central

2012-01-01

Background Data on causes of death by age and sex are a critical input into health decision-making. Priority setting in public health should be informed not only by the current magnitude of health problems but by trends in them. However, cause of death data are often not available or are subject to substantial problems of comparability. We propose five general principles for cause of death model development, validation, and reporting. Methods We detail a specific implementation of these principles that is embodied in an analytical tool - the Cause of Death Ensemble model (CODEm) - which explores a large variety of possible models to estimate trends in causes of death. Possible models are identified using a covariate selection algorithm that yields many plausible combinations of covariates, which are then run through four model classes. The model classes include mixed effects linear models and spatial-temporal Gaussian Process Regression models for cause fractions and death rates. All models for each cause of death are then assessed using out-of-sample predictive validity and combined into an ensemble with optimal out-of-sample predictive performance. Results Ensemble models for cause of death estimation outperform any single component model in tests of root mean square error, frequency of predicting correct temporal trends, and achieving 95% coverage of the prediction interval. We present detailed results for CODEm applied to maternal mortality and summary results for several other causes of death, including cardiovascular disease and several cancers. Conclusions CODEm produces better estimates of cause of death trends than previous methods and is less susceptible to bias in model specification. We demonstrate the utility of CODEm for the estimation of several major causes of death. PMID:22226226

Syntactic analysis in sentence comprehension: effects of dependency types and grammatical constraints.

PubMed

De Vincenzi, M

1996-01-01

This paper presents three experiments on the parsing of Italian wh-questions that manipulate the wh-type (who vs. which-N) and the wh extraction site (main clause, dependent clause with or without complementizer). The aim of these manipulations is to see whether the parser is sensitive to the type of dependencies being processed and whether the processing effects can be explained by a unique processing principle, the minimal chain principle (MCP; De Vincenzi, 1991). The results show that the parser, following the MCP, prefers structures with fewer and less complex chains. In particular: (1) There is a processing advantage for the wh-subject extractions, the structures with less complex chains; (2) there is a processing dissociation between the who and which questions; (3) the parser respects the principle that governs the well-formedness of the empty categories (ECP).

Unifying decoherence and the Heisenberg Principle

NASA Astrophysics Data System (ADS)

Janssens, Bas

2017-08-01

We exhibit three inequalities involving quantum measurement, all of which are sharp and state independent. The first inequality bounds the performance of joint measurement. The second quantifies the trade-off between the measurement quality and the disturbance caused on the measured system. Finally, the third inequality provides a sharp lower bound on the amount of decoherence in terms of the measurement quality. This gives a unified description of both the Heisenberg uncertainty principle and the collapse of the wave function.

A Study of the Less-Developed-Countries Debt Crisis in Mexico and Subsequent Economic Policies

DTIC Science & Technology

2012-09-01

August, 1982, the Finance Minister of Mexico, Silvia Herzog informed the International Monetary Fund that Mexico was unable to meet its principle ...world. A principle cause of the 1983 debt crisis proved to be the ability of Mexico to borrow considerable sums of capital from the international...environment that is favorable to the accumulation of human knowledge.”30 Additionally, studies conducted by “Barro (1991), Mankiw , Romer, and Well (1992

Development of principles of two-cascaded laser speckle-microscopy with implication to high-precision express diagnostics of chlamydial infection

NASA Astrophysics Data System (ADS)

Ulianova, Onega; Moiseeva, Yulia; Filonova, Nadezhda; Subbotina, Irina; Zaitsev, Sergey; Saltykov, Yury; Polyanina, Tatiana; Lyapina, Anna; Ulyanov, Sergey; Larionova, Olga; Utz, Sergey; Feodorova, Valentina

2018-04-01

Principles of two-cascaded laser speckle-microscopy prospect for application to express diagnostics of chlamydial infection are developed. Prototype of two-cascaded speckle-microscope is designed and tested. Specific case of illumination of bacterial cells by dynamic speckles is considered. Express method of detection of epithelial cells, containing defects, which are caused by Chlamydia trachomatis bacteria, is suggested. Results of improved recognition of C. trachomatis bacteria are discussed.

A proposal for digital electro-optic switches with free-carrier dispersion effect and Goos-Hanchen shift in silicon-on-insulator waveguide corner mirror

NASA Astrophysics Data System (ADS)

Sun, DeGui

2013-09-01

In a silicon-on-insulator (SOI) waveguide corner mirror (WCM) structure, with the quantum process of a frustrated total internal reflection (FTIR) phenomenon and the time delay principle in the two-dimensional potential barrier tunneling process of a mass of particles, we derive an accurate physical model for the Goos-Hanchen (GH) shift of optical guided-mode in the FTIR process, and in principle match the GH shift jumping states with the independent guided-modes. Then, we propose and demonstrate a new regime of 1 × N digital optical switches with a matching state between the free-carrier dispersion (FCD) based refractive index modulation (RIM) of silicon to create a GH shift jumping function of a photonic signal at the reflecting interface and the independent guided-modes in the FTIR process, where a MOS-capacitor type electro-optic modulation regime is proposed and discussed to realize an effective FCD-based RIM. At the critical matching state, i.e., the incident of an optical beam is at the vicinity of Brewster angle in the WCM, a mini-change of refractive index of waveguide material can cause a great jump of GH shift along the FTIR reflecting interface, and further a 1 × N digital optical switching process could be realized. For a 350-500 nm single-mode rib waveguide made on the 220 nm CMOS-compatible SOI substrate and with the FCD effect based RIM of silicon crystal, a concentration variation of 1018-1019 cm-3 has caused a 0.5-2.5 μm GH shift of reflected beam, which is at 2-5 times of a mode-size and hence radically convinces an optical switching function with a 1 × 3-1 × 10 scale.

Understanding Reflectance Anisotropy: Surface-structure signatures and bulk-related features

NASA Astrophysics Data System (ADS)

Gero Schmidt, W.

2000-03-01

Reflectance anisotropy spectroscopy (RAS) is becoming an increasingly important tool for in situ control of semiconductor processing with real-time feedback. The understanding and interpretation of the measured spectra, however, has been hampered by relatively slow theoretical progress. Using a massively parallel real-space multigrid technique [1] and ab initio pseudopotentials we calculated the optical spectra of a variety of III-V(001) growth structures and stepped Si(111):H surfaces. Our results agree well with experiment, notably with respect to the stoichiometric changes induced by different surface preparations. We identify two distinct sources for the optical anisotropy: (i) highly structure-dependent features are caused by transitions involving electronic surface states, and (ii) derivative-like oscillations or peaks at the bulk critical point energies arise from transitions between surface-modified bulk wave functions. The latter are nearly independent from the actual surface structure. The agreement between the calculated and measured spectra is further improved by applying quasi-particle corrections obtained from numerically efficient, simplified GW calculations [2]. The combination of converged first-principles calculations with an approximate treatment of many-particle effects allows the reliable identification of ``surface-structure fingerprints'' in the optical spectra, paving the way for the exploitation of their rich technological potential. [1ex] [1] EL Briggs, DJ Sullivan, J Bernholc, Phys. Rev. B 54, 14362 (1996). [2] F Bechstedt, R Del Sole, G Cappellini, L Reining, Solid State Commun. 84, 765 (1992).

Fluorescence Aggregation-Caused Quenching versus Aggregation-Induced Emission: A Visual Teaching Technology for Undergraduate Chemistry Students

ERIC Educational Resources Information Center

Ma, Xiaofeng; Sun, Rui; Cheng, Jinghui; Liu, Jiaoyan; Gou, Fei; Xiang, Haifeng; Zhou, Xiangge

2016-01-01

A laboratory experiment visually exploring two opposite basic principles of fluorescence of aggregation-caused quenching (ACQ) and aggregation-induced emission (AIE) is demonstrated. The students would prepared two salicylaldehyde-based Schiff bases through a simple one-pot condensation reaction of one equiv of 1,2-diamine with 2 equiv of…

Effects of Practice Schedule on Wind Instrument Performance: A Preliminary Application of a Motor Learning Principle

ERIC Educational Resources Information Center

Stambaugh, Laura A.; Demorest, Steven M.

2010-01-01

The effects of three practice schedules on beginning instrumental achievement were explored. A total of 19 seventh-grade clarinet and saxophone students completed one 18-minute practice session using either a blocked schedule causing a low level of cognitive (contextual) interference, a hybrid schedule causing a moderate level of interference, or…

Clinical management of chronic testicular pain.

PubMed

Kumar, Priyadarshi; Mehta, Vivek; Nargund, Vinod H

2010-01-01

To review the causes and principles and recent concepts in the management of testicular pain. Chronic testicular pain is a common presenting symptom in genitourinary surgery. Due to increased awareness of testicular cancer and in men's health more cases are likely to be referred. A literature search was made for abstracts, original papers and review articles in the Cochrane Database, Medline and medical textbooks using the words 'testicular pain' and orchialgia to find the causes and mechanisms of testicular pain. The management and algorithm have been structured on evidence-based management strategies. The management of chronic testicular pain remains essentially based on clinical assessment. In recent years there have been advances in the non-surgical management of testicular pain mainly because of the emergence of pain relief as a specialty. However, in some cases pain control is a problem and may ultimately conclude with orchiectomy. The management of chronic testicular pain includes a careful assessment of testicular and extratesticular causes. Relief of symptoms is not always possible and gaining an insight into the patient's concerns and empathizing with their condition is paramount in helping them cope with their symptoms. Surgery should not be undertaken lightly for there is no guarantee that there will always be resolution of symptoms and the patient should be counseled accordingly. Copyright (c) 2010 S. Karger AG, Basel.

Recurrent miscarriage: principles of management.

PubMed

Li, T C

1998-02-01

Recurrent miscarriage is a heterogeneous condition which has many possible underlying causes. Ideally, couples with the problem should be managed in a dedicated miscarriage clinic, with thorough investigations according to a protocol, with structured history and investigation sheets. Counselling is an important feature and may be provided by a specially trained counsellor, or specialized nurse appropriately trained in counselling. Counselling should include an explanation of the possible underlying causes of the condition, and of the prognosis of each of the conditions. There is no definite cause of miscarriage in approximately half of the patients. No treatment is needed in this group, apart from reassurance and tender loving care. Treatment of unproven value, for example progesterone support in early pregnancy, should not be offered. Treatment offered empirically or as part of a research project should have a sound scientific and statistical basis, and should include careful counselling with informed consent of the patient. There are many controversial issues in the management of recurrent miscarriage; consequently, there is a need for locally agreed guidelines for management. Women who conceive again should be offered regular monitoring, including serial ultrasonography in the first trimester of pregnancy. An active audit programme to review regularly the various outcome measures set against defined targets should be established in the clinic.

Ethical problems in radiology: radiological consumerism.

PubMed

Magnavita, N; Bergamaschi, A

2009-10-01

One of the causes of the increasing request for radiological examinations occurring in all economically developed countries is the active role played by the patient-consumer. Consumerism places the radiologist in an ethical dilemma, between the principle of autonomy on the one hand and the ethical principles of beneficence, nonmaleficence and justice on the other. The choice made by radiologists in moral dilemmas is inspired by an adherence to moral principles, which in Italy and elsewhere refer to the Judaeo-Christian tradition or to neo-Darwinian relativism. Whatever the choice, the radiologist is bound to adhere to that choice and to provide the patient with all the relevant information regarding his or her state of health.

Least action and entropy considerations of self-organization in Benard cells

NASA Astrophysics Data System (ADS)

Georgiev, Georgi; Iannacchione, Germano

We study self-organization in complex systems using first principles in physics. Our approach involves the principle of least action and the second law of thermodynamics. In far from equilibrium systems, energy gradients cause internal ordering to facilitate the dissipation of energy in the environment. This internal ordering decreases their internal entropy in order to obey the principle of least action, minimizing the product of time and energy for transport through the system. We are considering the connection between action and entropy decrease inside Benard cells in order to derive some general features of self-organization. We are developing mathematical treatment of this coupling and comparing it to results from experiments and simulations.

Distributive justice in American healthcare: institutions, power, and the equitable care of patients.

PubMed

Putsch, Robert W; Pololi, Linda

2004-09-01

The authors argue that the American healthcare system has developed in a fashion that permits and may support ongoing, widespread inequities based on poverty, race, gender, and ethnicity. Institutional structures also contribute to this problem. Analysis is based on (1) discussions of a group of experts convened by the Office of Minority Health, US Department of Health and Human Services at a conference to address healthcare disparities; and (2) review of documentation and scientific literature focused on health, health-related news, language, healthcare financing, and the law. Institutional factors contributing to inequity include the cost and financing of American healthcare, healthcare insurance principles such as mutual aid versus actuarial fairness, and institutional power. Additional causes for inequity are bias in decision making by healthcare practitioners, clinical training environments linked to abuse of patients and coworkers, healthcare provider ethnicity, and politics. Recommendations include establishment of core attributes of trust, relationship and advocacy in health systems; universal healthcare; and insurance systems based on mutual aid. In addition, monitoring of equity in health services and the development of a set of ethical principles to guide systems change and rule setting would provide a foundation for distributive justice in healthcare. Additionally, training centers should model the behaviors they seek to foster and be accountable to the communities they serve.

Ca-Embedded C2N: an efficient adsorbent for CO2 capture.

PubMed

Liu, Yuzhen; Meng, Zhaoshun; Guo, Xiaojian; Xu, Genjian; Rao, Dewei; Wang, Yuhui; Deng, Kaiming; Lu, Ruifeng

2017-10-25

Carbon dioxide as a greenhouse gas causes severe impacts on the environment, whereas it is also a necessary chemical feedstock that can be converted into carbon-based fuels via electrochemical reduction. To efficiently and reversibly capture CO 2 , it is important to find novel materials for a good balance between adsorption and desorption. In this study, we performed first-principles calculations and grand canonical Monte Carlo (GCMC) simulations, to systematically study metal-embedded carbon nitride (C 2 N) nanosheets for CO 2 capture. Our first-principles results indicated that Ca atoms can be uniformly trapped in the cavity center of C 2 N structure, while the transition metals (Sc, Ti, V, Cr, Mn, Fe, Co) are favorably embedded in the sites off the center of the cavity. The determined maximum number of CO 2 molecules with strong physisorption showed that Ca-embedded C 2 N monolayer is the most promising CO 2 adsorbent among all considered metal-embedded materials. Moreover, GCMC simulations revealed that at room temperature the gravimetric density for CO 2 adsorbed on Ca-embedded C 2 N reached 50 wt% at 30 bar and 23 wt% at 1 bar, higher than other layered materials, thus providing a satisfactory system for the CO 2 capture and utilization.

Design of an adjustable bipod flexure for a large-aperture mirror of a space camera.

PubMed

Liu, Bei; Wang, Wei; Qu, Yan-Jun; Li, Xu-Peng; Wang, Xiao; Zhao, Hui

2018-05-20

An adjustable bipod flexure (ABF) technique for a large-aperture mirror of a space camera is presented. The proposed flexure mount can decrease the surface distortions caused by the machining error and the assembly error of the mirror assembly (MA) in a horizontal optical testing layout. Through the analysis of the compliance matrix of conventional bipod flexure, the positional relationship between the rotation center and the apex of the flexure is investigated. Then, the principle of the adjustable flexure, known as the trapezoidal switching principle, is proposed based on the analysis result. The structure and application of the flexure are also described. The optical performance of the mirror mounted by the adjustable flexures in different misalignments was performed using finite element methods. The result shows that the astigmatic aberration due to gravity is effectively reduced by adjusting the mount, and the root-mean-square value of the mirror can be minimized with the misalignment between the flexure pivot and the neutral plane minimized. New monolithic bipod flexures, based on the optimal regulating variable Δ u according to the measurement results, are manufactured to replace the ABFs to secure the mirror's safety against launch loads. Modal analysis verified the mechanical safety of the MA with respect to the new monolithic flexures.

Integrating Sex and Drugs into the Principles Course: Market-Failures versus Failures-of-Market Outcomes.

ERIC Educational Resources Information Center

Colander, David

2003-01-01

Argues that microeconomics principles courses are structured around an approach to policy that avoids many controversial but central policy issues including: the interplay of moral issues and efficiency; questions of consumer sovereignty; and questions of the interrelation between measures of efficiency and income distribution. Suggests a dual…

Perceptual Organization of Visual Structure Requires a Flexible Learning Mechanism

ERIC Educational Resources Information Center

Aslin, Richard N.

2011-01-01

Bhatt and Quinn (2011) provide a compelling and comprehensive review of empirical evidence that supports the operation of principles of perceptual organization in young infants. They also have provided a comprehensive list of experiences that could serve to trigger the learning of at least some of these principles of perceptual organization, and…

The Experimental State of Mind in Elicitation: Illustrations from Tonal Fieldwork

ERIC Educational Resources Information Center

Yu, Kristine M.

2014-01-01

This paper illustrates how an "experimental state of mind", i.e. principles of experimental design, can inform hypothesis generation and testing in structured fieldwork elicitation. The application of these principles is demonstrated with case studies in toneme discovery. Pike's classic toneme discovery procedure is shown to be a special…

Pivotal Response Treatment for Children with Autism: Core Principles and Applications for School Psychologists

ERIC Educational Resources Information Center

Renshaw, Tyler L.; Kuriakose, Sarah

2011-01-01

During the past 2 decades, pivotal response treatment (PRT) has emerged as an evidence-based methodology for intervening with the behavioral, communicative, social, and academic impairments of children with autism. Unlike other highly structured behavioral interventions for autism, PRT emphasizes principles over procedures and focuses on enhancing…

A first-principles study on second-order ferroelectric phase transition in two-dimensional puckered group V materials

NASA Astrophysics Data System (ADS)

Lee, Sang-Hoon; Jhi, Seung-Hoon

We study two-dimensional group V materials (P, As, Sb, and Bi) in puckered honeycomb structure using first-principles calculations. Two factors, the degree of puckering and buckling characterize not only the atomic structure but also the electronic structure and its topological phase. By analyzing the lone-pair character of constituent elements and the softening of the phonon mode, we clarify the origin of the buckling. We show that the phonon softening leads the second-order type structural phase transition from a flat to a buckled configuration. The inversion symmetry breaking associated with the structural transition induces the spontaneous polarization in these homogenous materials. Our calculations suggest that external strains or n-type doping are effective methods to control the degree of buckling. We find that the ferroelectric and non-trivial topological phase can coexist in puckered Bi when tensile strains are applied.

Foreword to 'Multiscale structural biology: biophysical principles and mechanisms underlying the action of bio-nanomachines', a special issue in Honour of Fumio Arisaka's 70th birthday.

PubMed

Hall, Damien; Takagi, Junichi; Nakamura, Haruki

2018-04-01

This issue of Biophysical Reviews, titled 'Multiscale structural biology: biophysical principles and mechanisms underlying the action of bio-nanomachines', is a collection of articles dedicated in honour of Professor Fumio Arisaka's 70th birthday. Initially, working in the fields of haemocyanin and actin filament assembly, Fumio went on to publish important work on the elucidation of structural and functional aspects of T4 phage biology. As his career has transitioned levels of complexity from proteins (hemocyanin) to large protein complexes (actin) to even more massive bio-nanomachinery (phage), it is fitting that the subject of this special issue is similarly reflective of his multiscale approach to structural biology. This festschrift contains articles spanning biophysical structure and function from the bio-molecular through to the bio-nanomachine level.

Modeling the structural, dynamical, and magnetic properties of liquid Al1-xMnx ( x=0.14 , 0.2, and 0.4): A first-principles investigation

NASA Astrophysics Data System (ADS)

Jakse, N.; Pasturel, A.

2007-07-01

We report the results of first-principles molecular dynamics simulations of liquid Al1-xMnx alloys at three different compositions. The local structure as defined by the Bhatia-Thornton partial structure factors is found to display significant changes at x=0.4 . In addition, a structural analysis using three-dimensional pair-analysis techniques evidences a fivefold symmetry around x=0.14 , in agreement with the experimental quasicrystal-forming range, and an increasing complexity of the Frank-Kasper polytetrahedral symmetry around Mn atoms at x=0.4 . We also examine the time evolution of the configurations at the three compositions in terms of the mean-square displacements and self-diffusion coefficients. Finally, we show a strong interplay between the structural changes and the evolution of the magnetic properties of the Mn atoms as a function of composition.

Errors Analysis of Students in Mathematics Department to Learn Plane Geometry

NASA Astrophysics Data System (ADS)

Mirna, M.

2018-04-01

This article describes the results of qualitative descriptive research that reveal the locations, types and causes of student error in answering the problem of plane geometry at the problem-solving level. Answers from 59 students on three test items informed that students showed errors ranging from understanding the concepts and principles of geometry itself to the error in applying it to problem solving. Their type of error consists of concept errors, principle errors and operational errors. The results of reflection with four subjects reveal the causes of the error are: 1) student learning motivation is very low, 2) in high school learning experience, geometry has been seen as unimportant, 3) the students' experience using their reasoning in solving the problem is very less, and 4) students' reasoning ability is still very low.

Structures, phase transitions, and magnetic properties of C o3Si from first-principles calculations

NASA Astrophysics Data System (ADS)

Zhao, Xin; Yu, Shu; Wu, Shunqing; Nguyen, Manh Cuong; Wang, Cai-Zhuang; Ho, Kai-Ming

2017-07-01

C o3Si was recently reported to exhibit remarkable magnetic properties in the nanoparticle form [B. Balasubramanian et al., Appl. Phys. Lett. 108, 152406 (2016)], 10.1063/1.4945987, yet better understanding of this material should be promoted. Here we report a study on the crystal structures of C o3Si using an adaptive genetic algorithm and discuss its electronic and magnetic properties from first-principles calculations. Several competing phases of C o3Si have been revealed from our calculations. We show that the hexagonal C o3Si structure reported in experiments has lower energy in the nonmagnetic state than in the ferromagnetic state at zero temperature. The ferromagnetic state of the hexagonal structure is dynamically unstable with imaginary phonon modes and transforms into a new orthorhombic structure, which is confirmed by our structure searches to have the lowest energy for both C o3Si and C o3Ge . Magnetic properties of the experimental hexagonal structure and the lowest-energy structures obtained from our structure searches are investigated in detail.

Vivek S. Bharadwaj | NREL

Science.gov Websites

Interests Vivek's interests broadly span across protein structure and dynamics, reaction mechanisms, and energetics and kinetics from first principles Protein structure prediction and docking Education PhD structure on the fumarate addition mechanism - a gas-phase ab initio study," Physical Chemistry

Colour Chemistry, Part I, Principles, Colour, and Molecular Structure

ERIC Educational Resources Information Center

Hallas, G.

1975-01-01

Discusses various topics in color chemistry, including the electromagnetic spectrum, the absorption and reflection of light, additive and subtractive color mixing, and the molecular structure of simple colored substances. (MLH)

Differentiation with Stratification: A Principle of Theoretical Physics in the Tradition of the Memory Art

NASA Astrophysics Data System (ADS)

Pombo, Claudia

2015-10-01

The art of memory started with Aristotle's questions on memory. During its long evolution, it had important contributions from alchemists, was transformed by Ramon Llull and apparently ended with Giordano Bruno, who was considered the best known representative of this art. This tradition did not disappear, but lives in the formulations of our modern scientific theories. From its initial form as a method of keeping information via associations, it became a principle of classification and structuring of knowledge. This principle, which we here name differentiation with stratification, is a structural design behind classical mechanics. Integrating two different traditions of science in one structure, this physical theory became the modern paradigm of science. In this paper, we show that this principle can also be formulated as a set of questions. This is done via an analysis of theories, based on the epistemology of observational realism. A combination of Rudolph Carnap's concept of theory as a system of observational and theoretical languages, with a criterion for separating observational languages, based on analytical psychology, shapes this epistemology. The `nuclear' role of the observational laws and the differentiations from these nucleus, reproducing the general cases of phenomena, reveals the memory art's heritage in the theories. Here in this paper we argue that this design is also present in special relativity and in quantum mechanics.

The contribution of new findings and ideas to the old principles of teratology.

PubMed

Jelínek, Richard

2005-01-01

Although the last generally accepted concept of principles of teratology was issued more than 30 years ago, the cause of less than 50% of all congenital anomalies is known and no substantial change in their incidence has been observed worldwide. In the meantime, powerful techniques of molecular biology as well as many sophisticated preventive measures have been introduced with marginal effects on the overall birth defects numbers. In this paper, we follow the history of basic concepts of teratology starting with Isidore Geoffroy Saint-Hilaire and Dareste, followed in the 20th century by James Wilson. Since that time no bright and completely new idea, which would deserve the name principle, has emerged. The advanced molecular studies support the long-existing principles and disclose the great variability of individuals and their responses to adverse exposures. In this way, the future of teratology counseling may be seen in a deep analysis of any individual case.

The Roots of Vandalism.

ERIC Educational Resources Information Center

Black, Susan

2002-01-01

Summarizes research on the causes of school vandalism, especially connection with educational environment. Suggests ways (with examples) for schools to prevent vandalism. Describes three core principles of Crime Prevention Through Environmental Design. (PKP)

Congenital rubella

MedlinePlus

... mother is infected with the virus that causes German measles. Congenital means the condition is present at ... Gershon AA. Rubella virus (German measles). In: Bennett JE, Dolin R, ... Principles and Practice of Infectious Diseases, Updated ...

Structure of naturally hydrated ferrihydrite revealed through neutron diffraction and first-principles modeling

NASA Astrophysics Data System (ADS)

Chappell, Helen F.; Thom, William; Bowron, Daniel T.; Faria, Nuno; Hasnip, Philip J.; Powell, Jonathan J.

2017-08-01

Ferrihydrite, with a ``two-line'' x-ray diffraction pattern (2L-Fh), is the most amorphous of the iron oxides and is ubiquitous in both terrestrial and aquatic environments. It also plays a central role in the regulation and metabolism of iron in bacteria, algae, higher plants, and animals, including humans. In this study, we present a single-phase model for ferrihydrite that unifies existing analytical data while adhering to fundamental chemical principles. The primary particle is small (20-50 Å) and has a dynamic and variably hydrated surface, which negates long-range order; collectively, these features have hampered complete characterization and frustrated our understanding of the mineral's reactivity and chemical/biochemical function. Near and intermediate range neutron diffraction (NIMROD) and first-principles density functional theory (DFT) were employed in this study to generate and interpret high-resolution data of naturally hydrated, synthetic 2L-Fh at standard temperature. The structural optimization overcomes transgressions of coordination chemistry inherent within previously proposed structures, to produce a robust and unambiguous single-phase model.

Adsorption of organic molecules on mineral surfaces studied by first-principle calculations: A review.

PubMed

Zhao, Hongxia; Yang, Yong; Shu, Xin; Wang, Yanwei; Ran, Qianping

2018-04-09

First-principle calculations, especially by the density functional theory (DFT) methods, are becoming a power technique to study molecular structure and properties of organic/inorganic interfaces. This review introduces some recent examples on the study of adsorption models of organic molecules or oligomers on mineral surfaces and interfacial properties obtained from first-principles calculations. The aim of this contribution is to inspire scientists to benefit from first-principle calculations and to apply the similar strategies when studying and tailoring interfacial properties at the atomistic scale, especially for those interested in the design and development of new molecules and new products. Copyright © 2017. Published by Elsevier B.V.

Combination of confocal principle and aperture stop separation improves suppression of crystalline lens fluorescence in an eye model.

PubMed

Klemm, Matthias; Blum, Johannes; Link, Dietmar; Hammer, Martin; Haueisen, Jens; Schweitzer, Dietrich

2016-09-01

Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a new technique to detect changes in the human retina. The autofluorescence decay over time, generated by endogenous fluorophores, is measured in vivo. The strong autofluorescence of the crystalline lens, however, superimposes the intensity decay of the retina fluorescence, as the confocal principle is not able to suppress it sufficiently. Thus, the crystalline lens autofluorescence causes artifacts in the retinal fluorescence lifetimes determined from the intensity decays. Here, we present a new technique to suppress the autofluorescence of the crystalline lens by introducing an annular stop into the detection light path, which we call Schweitzer's principle. The efficacy of annular stops with an outer diameter of 7 mm and inner diameters of 1 to 5 mm are analyzed in an experimental setup using a model eye based on fluorescent dyes. Compared to the confocal principle, Schweitzer's principle with an inner diameter of 3 mm is able to reduce the simulated crystalline lens fluorescence to 4%, while 42% of the simulated retina fluorescence is preserved. Thus, we recommend the implementation of Schweitzer's principle in scanning laser ophthalmoscopes used for fundus autofluorescence measurements, especially the FLIO device, for improved image quality.

Design principles and developmental mechanisms underlying retinal mosaics.

PubMed

Reese, Benjamin E; Keeley, Patrick W

2015-08-01

Most structures within the central nervous system (CNS) are composed of different types of neuron that vary in both number and morphology, but relatively little is known about the interplay between these two features, i.e. about the population dynamics of a given cell type. How such arrays of neurons are distributed within a structure, and how they differentiate their dendrites relative to each other, are issues that have recently drawn attention in the invertebrate nervous system, where the genetic and molecular underpinnings of these organizing principles are being revealed in exquisite detail. The retina is one of the few locations where these principles have been extensively studied in the vertebrate CNS, indeed, where the design principles of 'mosaic regularity' and 'uniformity of coverage' were first explicitly defined, quantified, and related to each other. Recent studies have revealed a number of genes that influence the formation of these histotypical features in the retina, including homologues of those invertebrate genes, although close inspection reveals that they do not always mediate comparable developmental processes nor elucidate fundamental design principles. The present review considers just how pervasive these features of 'mosaic regularity' and 'uniform dendritic coverage' are within the mammalian retina, discussing the means by which such features can be assessed in the mature and developing nervous system and examining the limitations associated with those assessments. We then address the extent to which these two design principles co-exist within different populations of neurons, and how they are achieved during development. Finally, we consider the neural phenotypes obtained in mutant nervous systems, to address whether a prospective gene of interest underlies those very design principles. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

Toward a Unified Sub-symbolic Computational Theory of Cognition

PubMed Central

Butz, Martin V.

2016-01-01

This paper proposes how various disciplinary theories of cognition may be combined into a unifying, sub-symbolic, computational theory of cognition. The following theories are considered for integration: psychological theories, including the theory of event coding, event segmentation theory, the theory of anticipatory behavioral control, and concept development; artificial intelligence and machine learning theories, including reinforcement learning and generative artificial neural networks; and theories from theoretical and computational neuroscience, including predictive coding and free energy-based inference. In the light of such a potential unification, it is discussed how abstract cognitive, conceptualized knowledge and understanding may be learned from actively gathered sensorimotor experiences. The unification rests on the free energy-based inference principle, which essentially implies that the brain builds a predictive, generative model of its environment. Neural activity-oriented inference causes the continuous adaptation of the currently active predictive encodings. Neural structure-oriented inference causes the longer term adaptation of the developing generative model as a whole. Finally, active inference strives for maintaining internal homeostasis, causing goal-directed motor behavior. To learn abstract, hierarchical encodings, however, it is proposed that free energy-based inference needs to be enhanced with structural priors, which bias cognitive development toward the formation of particular, behaviorally suitable encoding structures. As a result, it is hypothesized how abstract concepts can develop from, and thus how they are structured by and grounded in, sensorimotor experiences. Moreover, it is sketched-out how symbol-like thought can be generated by a temporarily active set of predictive encodings, which constitute a distributed neural attractor in the form of an interactive free-energy minimum. The activated, interactive network attractor essentially characterizes the semantics of a concept or a concept composition, such as an actual or imagined situation in our environment. Temporal successions of attractors then encode unfolding semantics, which may be generated by a behavioral or mental interaction with an actual or imagined situation in our environment. Implications, further predictions, possible verification, and falsifications, as well as potential enhancements into a fully spelled-out unified theory of cognition are discussed at the end of the paper. PMID:27445895

Applicability of Similarity Principles to Structural Models

NASA Technical Reports Server (NTRS)

Goodier, J N; Thomson, W T

1944-01-01

A systematic account is given in part I of the use of dimensional analysis in constructing similarity conditions for models and structures. The analysis covers large deflections, buckling, plastic behavior, and materials with nonlinear stress-strain characteristics, as well as the simpler structural problems. (author)

DCS (Defense Communications System) Technical Control Engineering Criteria. Revision 1

DTIC Science & Technology

1981-05-01

Switched Network 5-9-14 5.9.6(g) Application of Principle of Time-Slot Interchange for Alt-Routing 5-9-15 5.9.6(h) Digital Interface (typical...is an approximate chart and does not take into account signal degradations which may be caused by frame cross-connects, patch jacks, or splices...Manual, TSEC/KG-30/30A/33A/34/34A Volume I - Description, Installation, and Principles of Operation KAM-238/TSEC Maintenance Maliual TSEC/KG-30/30A/33/33A

Flexibility of movement organization in piano performance.

PubMed

Furuya, Shinichi; Altenmüller, Eckart

2013-01-01

Piano performance involves a large repertoire of highly skilled movements. The acquisition of these exceptional skills despite innate neural and biomechanical constraints requires a sophisticated interaction between plasticity of the neural system and organization of a redundant number of degrees of freedom (DOF) in the motor system. Neuroplasticity subserving virtuosity of pianists has been documented in neuroimaging studies investigating effects of long-term piano training on structure and function of the cortical and subcortical regions. By contrast, recent behavioral studies have advanced the understanding of neuromuscular strategies and biomechanical principles behind the movement organization that enables skilled piano performance. Here we review the motor control and biomechanics literature, introducing the importance of describing motor behaviors not only for understanding mechanisms responsible for skillful motor actions in piano playing, but also for advancing diagnosis and rehabilitation of movement disorders caused by extensive piano practice.

Single nucleotide variations: Biological impact and theoretical interpretation

PubMed Central

Katsonis, Panagiotis; Koire, Amanda; Wilson, Stephen Joseph; Hsu, Teng-Kuei; Lua, Rhonald C; Wilkins, Angela Dawn; Lichtarge, Olivier

2014-01-01

Genome-wide association studies (GWAS) and whole-exome sequencing (WES) generate massive amounts of genomic variant information, and a major challenge is to identify which variations drive disease or contribute to phenotypic traits. Because the majority of known disease-causing mutations are exonic non-synonymous single nucleotide variations (nsSNVs), most studies focus on whether these nsSNVs affect protein function. Computational studies show that the impact of nsSNVs on protein function reflects sequence homology and structural information and predict the impact through statistical methods, machine learning techniques, or models of protein evolution. Here, we review impact prediction methods and discuss their underlying principles, their advantages and limitations, and how they compare to and complement one another. Finally, we present current applications and future directions for these methods in biological research and medical genetics. PMID:25234433

[Return to Work: A Workplace Focused Module to be Integrated in Cognitive Behavioral Therapy].

PubMed

Winter, Lotta; Kraft, Julia; Boss, Katharina; Kahl, Kai G

2015-08-01

Psychiatric disorders, in particular depression and anxiety disorders, are important causes of impaired job performance and increased sick leave. Longer periods of sickness leave lead regularly to difficulties concerning return to work. Furthermore, work is an important factor for psychological health. The central issue of the "return to work" (RTW) module by Lagerveldt and colleagues 5 is remission from psychiatric disorder, and structured support to return to work. The module is based on principles of cognitive-behavioral therapy (CBT), and can be integrated in standard CBT. Existing data from a randomized controlled trial suggest that treatment outcome concerning remission is similar between CBT supplemented with RTW (CBT-W) module and standard CBT. However, time to return to work is reduced in CBT-W. © Georg Thieme Verlag KG Stuttgart · New York.

Half-metallic antiferromagnetism in double perovskite BiPbCrCuO{sub 6}

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

Weng, Ke-Chuan; Wang, Y. K., E-mail: kant@ntnu.edu.tw

2015-05-07

The electronic structure and magnetic properties of BiPbCrCuO{sub 6} double perovskite are investigated based on first-principles density functional calculations with generalized gradient approximation (GGA) and GGA incorporated with Coulomb correlation interaction U (GGA + U). The results suggest the half-metallic (HM) and antiferromagnetic (AFM) properties of BiPbCrCuO{sub 6} double perovskite. The HM-AFM property of the double perovskite is caused by the double-exchange mechanism between neighboring Cr{sup 5+}(t{sub 2g}{sup 1}↓) and Cu{sup 2+}(t{sub 2g}{sup 3}↑t{sub 2g}{sup 3}↓e{sub g}{sup 2}↑e{sub g}↓) via the intermediate O{sup 2−}(2s{sup 2}2p{sup 6}) ion.

Pacific Northwest Laboratory annual report for 1988 to the DOE Office of Energy Research: Part 1, Biomedical Sciences

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

Park, J.F.

1989-06-01

This report summarizes progress on OHER biomedical and health-effects research conducted at PNL in FY 1988. The research develops the knowledge and scientific principles necessary to identify, understand, and anticipate the long-term health consequences of energy-related radiation and chemicals. Our continuing emphasis is to decrease the uncertainty of health-effects risk estimates from existing and/or developing energy-related technologies through an increased understanding of how radiation and chemicals cause health effects. The report is arranged to reflect PNL research relative to OHER programmatic structure. The first section, on human health effects, concerns statistical and epidemiological studies for assessing health risks. The nextmore » section, which contains reports of health-effects research in biological systems, includes research with radiation and chemicals.« less

Students with Autism Spectrum Disorder and Their Parents in the Transition into Higher Education: Impact on Dynamics in the Parent-Child Relationship.

PubMed

Van Hees, Valérie; Roeyers, Herbert; De Mol, Jan

2018-05-02

This study examined how 34 senior students and first-year college students with autism spectrum disorder, their mothers (n = 34) and fathers (n = 26) navigate the higher education transition, and how this context impacts on dynamics in the parent-child relationships. Semi-structured interviews were analyzed based on grounded theory and dyadic analysis principles. Both parties were confronted with an abundance of challenges and experienced strong feelings of ambivalence, stress and anxiety. Differences in perspectives occurred regarding the construction of adulthood, the acquisition of autonomy, disclosure and subscribing to support services. These differences caused tensions in the parent-child relationship, hindering the transformation of the relationship into an adult-like mutual relationship. Clinical implications are extrapolated on the basis of these findings.

Conformational switching upon phosphorylation: a predictive framework based on energy landscape principles.

PubMed

Lätzer, Joachim; Shen, Tongye; Wolynes, Peter G

2008-02-19

We investigate how post-translational phosphorylation modifies the global conformation of a protein by changing its free energy landscape using two test proteins, cystatin and NtrC. We first examine the changes in a free energy landscape caused by phosphorylation using a model containing information about both structural forms. For cystatin the free energy cost is fairly large indicating a low probability of sampling the phosphorylated conformation in a perfectly funneled landscape. The predicted barrier for NtrC conformational transition is several times larger than the barrier for cystatin, indicating that the switch protein NtrC most probably follows a partial unfolding mechanism to move from one basin to the other. Principal component analysis and linear response theory show how the naturally occurring conformational changes in unmodified proteins are captured and stabilized by the change of interaction potential. We also develop a partially guided structure prediction Hamiltonian which is capable of predicting the global structure of a phosphorylated protein using only knowledge of the structure of the unphosphorylated protein or vice versa. This algorithm makes use of a generic transferable long-range residue contact potential along with details of structure short range in sequence. By comparing the results obtained with this guided transferable potential to those from the native-only, perfectly funneled Hamiltonians, we show that the transferable Hamiltonian correctly captures the nature of the global conformational changes induced by phosphorylation and can sample substantially correct structures for the modified protein with high probability.

Lepromin skin test

MedlinePlus

... infection if left untreated. It is caused by Mycobacterium leprae bacteria. This test is a research tool that ... Renault CA, Ernst JD. Mycobacterium leprae (leprosy). In: Bennett JE, ... Principles and Practice of Infectious Diseases, Updated ...

Colorado tick fever

MedlinePlus

... cord ( meningitis ) Irritation and swelling of the brain ( encephalitis ) Repeated bleeding episodes for no apparent cause Call ... Beckham JD, Tyler KL. Encephalitis. In: Bennett JE, Dolin R, ... Principles and Practice of Infectious Disease, Updated Edition . ...

Pharyngitis - sore throat

MedlinePlus

... by colds, the flu, coxsackie virus or mono (mononucleosis). Bacteria that can cause pharyngitis in some cases: ... Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier ...

Guidelines for Reproductive Toxicity Risk Assessment

EPA Pesticide Factsheets

These guidelines discuss the scientific basis for concern about exposure to agents that cause reproductive toxicity and describe the principles and procedures to be followed in conducting risk assessments for reproductive toxicity.

Solid iron-hydrogen alloys under high pressure by first principles

NASA Astrophysics Data System (ADS)

Umemoto, K.; Hirose, K.

2016-12-01

Hydrogen and iron are two of major constituents of the Earth and planetary interiors. The crystal structure of solid FeHx is one of the most fundamental information in order to understand properties of planetary cores. It is well known that FeH takes closed-packed structures: dhcp, hcp, and fcc. Recently, hydrogen-rich phases, FeH2 and FeH3, were experimentally synthesized [1]. Although a tetragonal structure of FeH2 was proposed, it could not explain experimental observations, energetic stability and compression curve. Here we propose a new crystal structure of FeH2. The symmetry of the new structure is completely identical to that in originally proposed one, but the hydrogen sublattice which cannot be directly determined by XRD experiments is different. It will be demonstrated by first principles that the new structure can be fully consistent with experimental observations. [1] C. M. Pépin, A. Dewaele, G. Geneste, P. Loubeyre, and M. Mezouar, Phys. Rev. Lett. 113, 265504 (2014).

M3Ag17(SPh)12 Nanoparticles and Their Structure Prediction.

PubMed

Wickramasinghe, Sameera; Atnagulov, Aydar; Conn, Brian E; Yoon, Bokwon; Barnett, Robert N; Griffith, Wendell P; Landman, Uzi; Bigioni, Terry P

2015-09-16

Although silver nanoparticles are of great fundamental and practical interest, only one structure has been determined thus far: M4Ag44(SPh)30, where M is a monocation, and SPh is an aromatic thiolate ligand. This is in part due to the fact that no other molecular silver nanoparticles have been synthesized with aromatic thiolate ligands. Here we report the synthesis of M3Ag17(4-tert-butylbenzene-thiol)12, which has good stability and an unusual optical spectrum. We also present a rational strategy for predicting the structure of this molecule. First-principles calculations support the structural model, predict a HOMO-LUMO energy gap of 1.77 eV, and predict a new "monomer mount" capping motif, Ag(SR)3, for Ag nanoparticles. The calculated optical absorption spectrum is in good correspondence with the measured spectrum. Heteroatom substitution was also used as a structural probe. First-principles calculations based on the structural model predicted a strong preference for a single Au atom substitution in agreement with experiment.

High-Resolution Mapping of Chromatin Conformation in Cardiac Myocytes Reveals Structural Remodeling of the Epigenome in Heart Failure

PubMed Central

Rosa-Garrido, Manuel; Chapski, Douglas J.; Schmitt, Anthony D.; Kimball, Todd H.; Karbassi, Elaheh; Monte, Emma; Balderas, Enrique; Pellegrini, Matteo; Shih, Tsai-Ting; Soehalim, Elizabeth; Liem, David; Ping, Peipei; Galjart, Niels J.; Ren, Shuxun; Wang, Yibin; Ren, Bing

2017-01-01

Background: Cardiovascular disease is associated with epigenomic changes in the heart; however, the endogenous structure of cardiac myocyte chromatin has never been determined. Methods: To investigate the mechanisms of epigenomic function in the heart, genome-wide chromatin conformation capture (Hi-C) and DNA sequencing were performed in adult cardiac myocytes following development of pressure overload–induced hypertrophy. Mice with cardiac-specific deletion of CTCF (a ubiquitous chromatin structural protein) were generated to explore the role of this protein in chromatin structure and cardiac phenotype. Transcriptome analyses by RNA-seq were conducted as a functional readout of the epigenomic structural changes. Results: Depletion of CTCF was sufficient to induce heart failure in mice, and human patients with heart failure receiving mechanical unloading via left ventricular assist devices show increased CTCF abundance. Chromatin structural analyses revealed interactions within the cardiac myocyte genome at 5-kb resolution, enabling examination of intra- and interchromosomal events, and providing a resource for future cardiac epigenomic investigations. Pressure overload or CTCF depletion selectively altered boundary strength between topologically associating domains and A/B compartmentalization, measurements of genome accessibility. Heart failure involved decreased stability of chromatin interactions around disease-causing genes. In addition, pressure overload or CTCF depletion remodeled long-range interactions of cardiac enhancers, resulting in a significant decrease in local chromatin interactions around these functional elements. Conclusions: These findings provide a high-resolution chromatin architecture resource for cardiac epigenomic investigations and demonstrate that global structural remodeling of chromatin underpins heart failure. The newly identified principles of endogenous chromatin structure have key implications for epigenetic therapy. PMID:28802249

High-Resolution Mapping of Chromatin Conformation in Cardiac Myocytes Reveals Structural Remodeling of the Epigenome in Heart Failure.

PubMed

Rosa-Garrido, Manuel; Chapski, Douglas J; Schmitt, Anthony D; Kimball, Todd H; Karbassi, Elaheh; Monte, Emma; Balderas, Enrique; Pellegrini, Matteo; Shih, Tsai-Ting; Soehalim, Elizabeth; Liem, David; Ping, Peipei; Galjart, Niels J; Ren, Shuxun; Wang, Yibin; Ren, Bing; Vondriska, Thomas M

2017-10-24

Cardiovascular disease is associated with epigenomic changes in the heart; however, the endogenous structure of cardiac myocyte chromatin has never been determined. To investigate the mechanisms of epigenomic function in the heart, genome-wide chromatin conformation capture (Hi-C) and DNA sequencing were performed in adult cardiac myocytes following development of pressure overload-induced hypertrophy. Mice with cardiac-specific deletion of CTCF (a ubiquitous chromatin structural protein) were generated to explore the role of this protein in chromatin structure and cardiac phenotype. Transcriptome analyses by RNA-seq were conducted as a functional readout of the epigenomic structural changes. Depletion of CTCF was sufficient to induce heart failure in mice, and human patients with heart failure receiving mechanical unloading via left ventricular assist devices show increased CTCF abundance. Chromatin structural analyses revealed interactions within the cardiac myocyte genome at 5-kb resolution, enabling examination of intra- and interchromosomal events, and providing a resource for future cardiac epigenomic investigations. Pressure overload or CTCF depletion selectively altered boundary strength between topologically associating domains and A/B compartmentalization, measurements of genome accessibility. Heart failure involved decreased stability of chromatin interactions around disease-causing genes. In addition, pressure overload or CTCF depletion remodeled long-range interactions of cardiac enhancers, resulting in a significant decrease in local chromatin interactions around these functional elements. These findings provide a high-resolution chromatin architecture resource for cardiac epigenomic investigations and demonstrate that global structural remodeling of chromatin underpins heart failure. The newly identified principles of endogenous chromatin structure have key implications for epigenetic therapy. © 2017 The Authors.

Electronic structures of anatase (TiO2)1-x(TaON)x solid solutions: a first-principles study.

PubMed

Dang, Wenqiang; Chen, Hungru; Umezawa, Naoto; Zhang, Junying

2015-07-21

Sensitizing wide band gap photo-functional materials under visible-light irradiation is an important task for efficient solar energy conversion. Although nitrogen doping into anatase TiO2 has been extensively studied for this purpose, it is hard to increase the nitrogen content in anatase TiO2 because of the aliovalent nitrogen substituted for oxygen, leading to the formation of secondary phases or defects that hamper the migration of photoexcited charge carriers. In this paper, electronic structures of (TiO2)1-x(TaON)x (0 ≤ x ≤ 1) solid solutions, in which the stoichiometry is satisfied with the co-substitution of Ti for Ta along with O for N, are investigated within the anatase crystal structure using first-principles calculations. Our computational results show that the solid solutions have substantially narrower band gaps than TiO2, without introducing any localized energy states in the forbidden gap. In addition, in comparison with the pristine TiO2, the solid solution has a direct band gap when the content of TaON exceeds 0.25, which is advantageous to light absorption. The valence band maximum (VBM) of the solid solutions, which is mainly composed of N 2p states hybridized with O 2p, Ti 3d or Ta 5d orbitals, is higher in energy than that of pristine anatase TiO2 consisting of non-bonding O 2p states. On the other hand, incorporating TaON into TiO2 causes the formation of d-d bonding states through π interactions and substantially lowers the conduction band minimum (CBM) because of the shortened distance between some metal atoms. As a result, the anatase (TiO2)1-x(TaON)x is expected to become a promising visible-light absorber. In addition, some atomic configurations are found to possess exceptionally narrow band gaps.

Molecular principles behind Boceprevir resistance due to mutations in hepatitis C NS3/4A protease.

PubMed

Nagpal, Neha; Goyal, Sukriti; Wahi, Divya; Jain, Ritu; Jamal, Salma; Singh, Aditi; Rana, Preeti; Grover, Abhinav

2015-10-01

The hepatitis C virus (HCV) infection is a primary cause of chronic hepatitis which eventually progresses to cirrhosis and in some instances might advance to hepatocellular carcinoma. According to the WHO report, HCV infects 130-150 million people globally and every year 350,000 to 500,000 people die from hepatitis C virus infection. Great achievement has been made in viral treatment evolution, after the development of HCV NS3/4A protease inhibitor (Boceprevir). However, efficacy of Boceprevir is compromised by the emergence of drug resistant variants. The molecular principle behind drug resistance of the protease mutants such as (V36M, T54S and R155K) is still poorly understood. Therefore in this study, we employed a series of computational strategies to analyze the binding of antiviral drug, Boceprevir to HCV NS3/4A protease mutants. Our results clearly demonstrate that the point mutations (V36M, T54S and R155K) in protease are associated with lowering of its binding affinity with Boceprevir. Exhaustive analysis of the simulated Boceprevir-bound wild and mutant complexes revealed variations in hydrophobic interactions, hydrogen bond occupancy and salt bridge interactions. Also, substrate envelope analysis scrutinized that the studied mutations reside outside the substrate envelope which may affect the Boceprevir affinity towards HCV protease but not the protease enzymatic activity. Furthermore, structural analyses of the binding site volume and flexibility show impairment in flexibility and stability of the binding site residues in mutant structures. In order to combat Boceprevir resistance, renovation of binding interactions between the drug and protease may be valuable. The structural insight from this study reveals the mechanism of the Boceprevir resistance and the results can be valuable for the design of new PIs with improved efficiency. Copyright © 2015 Elsevier B.V. All rights reserved.

Shaping up the protein folding funnel by local interaction: lesson from a structure prediction study.

PubMed

Chikenji, George; Fujitsuka, Yoshimi; Takada, Shoji

2006-02-28

Predicting protein tertiary structure by folding-like simulations is one of the most stringent tests of how much we understand the principle of protein folding. Currently, the most successful method for folding-based structure prediction is the fragment assembly (FA) method. Here, we address why the FA method is so successful and its lesson for the folding problem. To do so, using the FA method, we designed a structure prediction test of "chimera proteins." In the chimera proteins, local structural preference is specific to the target sequences, whereas nonlocal interactions are only sequence-independent compaction forces. We find that these chimera proteins can find the native folds of the intact sequences with high probability indicating dominant roles of the local interactions. We further explore roles of local structural preference by exact calculation of the HP lattice model of proteins. From these results, we suggest principles of protein folding: For small proteins, compact structures that are fully compatible with local structural preference are few, one of which is the native fold. These local biases shape up the funnel-like energy landscape.

Shaping up the protein folding funnel by local interaction: Lesson from a structure prediction study

PubMed Central

Chikenji, George; Fujitsuka, Yoshimi; Takada, Shoji

2006-01-01

Predicting protein tertiary structure by folding-like simulations is one of the most stringent tests of how much we understand the principle of protein folding. Currently, the most successful method for folding-based structure prediction is the fragment assembly (FA) method. Here, we address why the FA method is so successful and its lesson for the folding problem. To do so, using the FA method, we designed a structure prediction test of “chimera proteins.” In the chimera proteins, local structural preference is specific to the target sequences, whereas nonlocal interactions are only sequence-independent compaction forces. We find that these chimera proteins can find the native folds of the intact sequences with high probability indicating dominant roles of the local interactions. We further explore roles of local structural preference by exact calculation of the HP lattice model of proteins. From these results, we suggest principles of protein folding: For small proteins, compact structures that are fully compatible with local structural preference are few, one of which is the native fold. These local biases shape up the funnel-like energy landscape. PMID:16488978

[Alienation and adaptation in English translation of traditional Chinese medicinal literature].

PubMed

Liang, Jun-xiong; Wang, Guan-jun

2006-10-01

Alienation and adaptation are two of the principles and methods in translation, each possessing their own values. Alienation should be applied in translating linguistic content in order to transfer the imbedded cultural messages trustfully; while the principle of adaptation should be followed in linguistic structure translation due to the different thinking patterns between Chinese and English which results in a great linguistic structure difference. Therefore, the translator must express the original meaning trustfully, on the other hand, to make the Chinese version more smooth, linguistic structure should be transformed to conform to the thinking habit of the readers. In brief,alienation and adaptation should complement each other in translation to make it a bridge connecting the different cultures.

General cognitive principles for learning structure in time and space.

PubMed

Goldstein, Michael H; Waterfall, Heidi R; Lotem, Arnon; Halpern, Joseph Y; Schwade, Jennifer A; Onnis, Luca; Edelman, Shimon

2010-06-01

How are hierarchically structured sequences of objects, events or actions learned from experience and represented in the brain? When several streams of regularities present themselves, which will be learned and which ignored? Can statistical regularities take effect on their own, or are additional factors such as behavioral outcomes expected to influence statistical learning? Answers to these questions are starting to emerge through a convergence of findings from naturalistic observations, behavioral experiments, neurobiological studies, and computational analyses and simulations. We propose that a small set of principles are at work in every situation that involves learning of structure from patterns of experience and outline a general framework that accounts for such learning. (c) 2010 Elsevier Ltd. All rights reserved.

The architecture of personality.

PubMed

Cervone, David

2004-01-01

This article presents a theoretical framework for analyzing psychological systems that contribute to the variability, consistency, and cross-situational coherence of personality functioning. In the proposed knowledge-and-appraisal personality architecture (KAPA), personality structures and processes are delineated by combining 2 principles: distinctions (a) between knowledge structures and appraisal processes and (b) among intentional cognitions with varying directions of fit, with the latter distinction differentiating among beliefs, evaluative standards, and aims. Basic principles of knowledge activation and use illuminate relations between knowledge and appraisal, yielding a synthetic account of personality structures and processes. Novel empirical data illustrate the heuristic value of the knowledge/appraisal distinction by showing how self-referent and situational knowledge combine to foster cross-situational coherence in appraisals of self-efficacy.

Rotational stellar structures based on the Lagrangian variational principle

NASA Astrophysics Data System (ADS)

Yasutake, Nobutoshi; Fujisawa, Kotaro; Yamada, Shoichi

2017-06-01

A new method for multi-dimensional stellar structures is proposed in this study. As for stellar evolution calculations, the Heney method is the defacto standard now, but basically assumed to be spherical symmetric. It is one of the difficulties for deformed stellar-evolution calculations to trace the potentially complex movements of each fluid element. On the other hand, our new method is very suitable to follow such movements, since it is based on the Lagrange coordinate. This scheme is also based on the variational principle, which is adopted to the studies for the pasta structures inside of neutron stars. Our scheme could be a major break through for evolution calculations of any types of deformed stars: proto-planets, proto-stars, and proto-neutron stars, etc.

Helicopter Fatigue Design Guide

DTIC Science & Technology

1983-11-01

for example, glass and carbon fibre reinforced plastics. The general principles behind the substantiation procedures for these materials are...initiating cause of many minor (and sometimes major) cracks that can lead to expensive repair, even though they may not immediately cause a safety...be seen, blade stresses correlated well with both unsteady models. However, push rod loads calculated with the Time Delay Model are much less than

Project-Based Learning and Pedagogy in Teacher Preparation: Staking out the Theoretical Mid-Ground

ERIC Educational Resources Information Center

Roessingh, Hetty; Chambers, Wendy

2011-01-01

In this article, we advance a model of project-based learning (PJBL) offering eight guiding principles to support a pragmatic and principled approach to teacher preparation at the undergraduate and graduate levels. We provide a template for structuring PJBL, and we include illustrative exemplars that demonstrate that the ideological mid-ground can…

Rawls, Sartre, and the Question of Camaraderie

ERIC Educational Resources Information Center

Arcilla, René V.

2013-01-01

In his classic text, "A Theory of Justice", John Rawls argues that the structural principles of a society are just when they issue from a procedure that is fair. One crucial feature that makes the procedure fair is that the persons who will be subjected to these principles choose them after they have deliberated together in a condition…

Using Video-Taped Examples of Stand-Up Comedy Routines To Teach Principles of Public Speaking.

ERIC Educational Resources Information Center

Siddens, Paul J., III

This paper investigates the use of stand-up comedy routines to demonstrate principles of public speaking to college students in communication classes. The paper examines particular elements of the public speaking process, which include the structural elements of speeches: (1) introductions; (2) the body of the speech, including organization,…

The Minimal Control Principle Predicts Strategy Shifts in the Abstract Decision Making Task

ERIC Educational Resources Information Center

Taatgen, Niels A.

2011-01-01

The minimal control principle (Taatgen, 2007) predicts that people strive for problem-solving strategies that require as few internal control states as possible. In an experiment with the Abstract Decision Making task (ADM task; Joslyn & Hunt, 1998) the reward structure was manipulated to make either a low-control strategy or a high-strategy…

External Quality Arrangements for the Review of Modern Apprenticeship Off-the-Job Training

ERIC Educational Resources Information Center

Education Scotland, 2015

2015-01-01

This publication provides a quality framework to provide a structure for external review of Modern Apprenticeship off-the-job training.? The indicators in this framework are arranged under three key principles, addressing five questions which Education Scotland is adopting for evaluation purposes. These are underpinned by a wider principle on the…

Reframing the Principle of Specialisation in Legitimation Code Theory: A Blended Learning Perspective

ERIC Educational Resources Information Center

Owusu-Agyeman, Yaw; Larbi-Siaw, Otu

2017-01-01

This study argues that in developing a robust framework for students in a blended learning environment, Structural Alignment (SA) becomes the third principle of specialisation in addition to Epistemic Relation (ER) and Social Relation (SR). We provide an extended code: (ER+/-, SR+/-, SA+/-) that present strong classification and framing to the…

Design Principles for Covalent Organic Frameworks as Efficient Electrocatalysts in Clean Energy Conversion and Green Oxidizer Production.

PubMed

Lin, Chun-Yu; Zhang, Lipeng; Zhao, Zhenghang; Xia, Zhenhai

2017-05-01

Covalent organic frameworks (COFs), an emerging class of framework materials linked by covalent bonds, hold potential for various applications such as efficient electrocatalysts, photovoltaics, and sensors. To rationally design COF-based electrocatalysts for oxygen reduction and evolution reactions in fuel cells and metal-air batteries, activity descriptors, derived from orbital energy and bonding structures, are identified with the first-principle calculations for the COFs, which correlate COF structures with their catalytic activities. The calculations also predict that alkaline-earth metal-porphyrin COFs could catalyze the direct production of H 2 O 2 , a green oxidizer and an energy carrier. These predictions are supported by experimental data, and the design principles derived from the descriptors provide an approach for rational design of new electrocatalysts for both clean energy conversion and green oxidizer production. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Principle research on a single mass piezoelectric six-degrees-of-freedom accelerometer.

PubMed

Liu, Jun; Li, Min; Qin, Lan; Liu, Jingcheng

2013-08-16

A signal mass piezoelectric six-degrees-of-freedom (six-DOF) accelerometer is put forward in response to the need for health monitoring of the dynamic vibration characteristics of high grade digitally controlled machine tools. The operating principle of the piezoelectric six-degrees-of-freedom accelerometer is analyzed, and its structure model is constructed. The numerical simulation model (finite element model) of the six axis accelerometer is established. Piezoelectric quartz is chosen for the acceleration sensing element and conversion element, and its static sensitivity, static coupling interference and dynamic natural frequency, dynamic cross coupling are analyzed by ANSYS software. Research results show that the piezoelectric six-DOF accelerometer has advantages of simple and rational structure, correct sensing principle and mathematic model, good linearity, high rigidity, and theoretical natural frequency is more than 25 kHz, no nonlinear cross coupling and no complex decoupling work.

Principle Research on a Single Mass Piezoelectric Six-Degrees-of-Freedom Accelerometer

PubMed Central

Liu, Jun; Li, Min; Qin, Lan; Liu, Jingcheng

2013-01-01

A signal mass piezoelectric six-degrees-of-freedom (six-DOF) accelerometer is put forward in response to the need for health monitoring of the dynamic vibration characteristics of high grade digitally controlled machine tools. The operating principle of the piezoelectric six-degrees-of-freedom accelerometer is analyzed, and its structure model is constructed. The numerical simulation model (finite element model) of the six axis accelerometer is established. Piezoelectric quartz is chosen for the acceleration sensing element and conversion element, and its static sensitivity, static coupling interference and dynamic natural frequency, dynamic cross coupling are analyzed by ANSYS software. Research results show that the piezoelectric six-DOF accelerometer has advantages of simple and rational structure, correct sensing principle and mathematic model, good linearity, high rigidity, and theoretical natural frequency is more than 25 kHz, no nonlinear cross coupling and no complex decoupling work. PMID:23959243

Detection principles of biological and chemical FET sensors.

PubMed

Kaisti, Matti

2017-12-15

The seminal importance of detecting ions and molecules for point-of-care tests has driven the search for more sensitive, specific, and robust sensors. Electronic detection holds promise for future miniaturized in-situ applications and can be integrated into existing electronic manufacturing processes and technology. The resulting small devices will be inherently well suited for multiplexed and parallel detection. In this review, different field-effect transistor (FET) structures and detection principles are discussed, including label-free and indirect detection mechanisms. The fundamental detection principle governing every potentiometric sensor is introduced, and different state-of-the-art FET sensor structures are reviewed. This is followed by an analysis of electrolyte interfaces and their influence on sensor operation. Finally, the fundamentals of different detection mechanisms are reviewed and some detection schemes are discussed. In the conclusion, current commercial efforts are briefly considered. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

What are the Ethical Problems Raised by the Increase of Cognitive Capabilities in the Defence Structure: The French Legal Structure, the Ethical Position of the French Military Health Service

DTIC Science & Technology

2009-10-01

principles for conducting research on humans as animals has been defined in 1988 and confirmed in the bioethical law in 1994 [3]. Some modifications...ethical principles for conducting research on humans as animals has been defined in 1988 and confirmed in the bioethical law in 1994 [3]. Some...partly, to the doctors and it had become necessary to think of the power of man outside of medicine. According to the German Hans Jonas “ bioethics

First principle calculation in FeCo overlayer on GaAs substrate

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

Jain, Vishal, E-mail: vjain045@gmail.com; Lakshmi, N.; Jain, Vivek Kumar

In this work the first principle electronic structure calculation is reported for FeCo/GaAs thin film system to investigate the effect of orientation on the electronic structural properties. A unit cell describing FeCo layers and GaAs layers is constructed for (100), (110), (111) orientation with vacuum of 30Å to reduce dimensions. It is found that although the (110) orientation is energetically more favorable than others, the magnetic moment is quite large in (100) and (111) system compared to the (110) and is due to the total DOS variation with orientation.

First-principles study of giant thermoelectric power in incommensurate TlInSe2

NASA Astrophysics Data System (ADS)

Ishikawa, M.; Nakayama, T.; Wakita, K.; Shim, Y. G.; Mamedov, N.

2018-04-01

Ternary thallium compound TlInSe2 exhibits a giant Seebeck effect below around 410 K, where Tl atoms form one dimensional incommensurate (IC) arrays. To clarify the origin of large thermoelectric power in the IC phase, the electronic properties of Tl-atom super-structured TlInSe2 were studied using the first-principles calculations. It was shown that the super-structures induce strong binding states between Se-p orbitals in the nearest neighboring layers and produce large density of states near lower conduction bands, which might be one of the origins to produce large thermoelectric power.

Machine & electrical double control air dryer for vehicle air braking system

NASA Astrophysics Data System (ADS)

Zhang, Xuan; Yang, Liu; Wang, Xian Yan; Tan, Xiao Yan; Wang, Wei

2017-09-01

As is known to all, a vehicle air brake system, in which usually contains moisture. To solve the problem, it is common to use air dryer to dry compressed air effectively and completely remove the moisture and oil of braking system. However, the existing air dryer is not suitable for all commercial vehicles. According to the operational status of the new energy vehicles in the initial operating period, the structure design principle of the machine & electric control air dryer is expounded from the aspects of the structure and operating principle, research & development process.

First-principles study on the phase transitions, crystal stabilities and thermodynamic properties of TiN under high pressure

NASA Astrophysics Data System (ADS)

Sun, Xinjun; Liu, Changdong; Guo, Yongliang; Sun, Deyan; Ke, Xuezhi

2018-03-01

The structural and thermodynamic properties of titanium nitride (TiN) have been investigated by merging first-principles calculations and particle-swarm algorithm. The three phases are identified for TiN, including the B1, the P63 / mmc, and the B2 phases. A new phase of anti-TiP structure with the space group P63 / mmc has been predicted. The calculated phase transition from the B1 to the P63 / mmc occurs at 270 GPa. The vibrational, elastic, and thermodynamic properties for the three phases have been calculated and discussed.

Effects of B site doping on electronic structures of InNbO4 based on hybrid density functional calculations

NASA Astrophysics Data System (ADS)

Lu, M. F.; Zhou, C. P.; Li, Q. Q.; Zhang, C. L.; Shi, H. F.

2018-01-01

In order to improve the photocatalytic activity under visible-light irradiation, we adopted first principle calculations based on density functional theory (DFT) to calculate the electronic structures of B site transition metal element doped InNbO4. The results indicated that the complete hybridization of Nb 4d states and some Ti 3d states contributed to the new conduction band of Ti doped InNbO4, barely changing the position of band edge. For Cr doping, some localized Cr 3d states were introduced into the band gap. Nonetheless, the potential of localized levels was too positive to cause visible-light reaction. When it came to Cu doping, the band gap was almost same with that of InNbO4 as well as some localized Cu 3d states appeared above the top of VB. The introduction of localized energy levels benefited electrons to migrate from valence band (VB) to conduction band (CB) by absorbing lower energy photons, realizing visible-light response.

Electrical, thermal, and species transport properties of liquid eutectic Ga-In and Ga-In-Sn from first principles

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

Yu, Seungho; Kaviany, Massoud, E-mail: kaviany@umich.edu

2014-02-14

Using ab initio molecular dynamics, the atomic structure and transport properties of eutectic Ga-In and Ga-In-Sn are investigated. The Kubo-Greenwood (K-G) and the Ziman-Faber (Z-F) formulations and the Wiedemann-Franz (W-F) law are used for the electrical and electronic thermal conductivity. The species diffusivity and the viscosity are also predicted using the mean square displacement and the Stokes-Einstein (S-E) relation. Alloying Ga causes more disordered structure, i.e., broadening the atomic distance near the In and Sn atoms, which reduces the transport properties and the melting temperature. The K-G treatment shows excellent agreement with the experimental results while Z-F treatment formula slightlymore » overestimates the electrical conductivity. The predicted thermal conductivity also shows good agreement with the experiments. The species diffusivity and the viscosity are slightly reduced by the alloying of Ga with In and Sn atoms. Good agreements are found with available experimental results and new predicted transport-property results are provided.« less

Durability tests of a fiber optic corrosion sensor.

PubMed

Wan, Kai Tai; Leung, Christopher K Y

2012-01-01

Steel corrosion is a major cause of degradation in reinforced concrete structures, and there is a need to develop cost-effective methods to detect the initiation of corrosion in such structures. This paper presents a low cost, easy to use fiber optic corrosion sensor for practical application. Thin iron film is deposited on the end surface of a cleaved optical fiber by sputtering. When light is sent into the fiber, most of it is reflected by the coating. If the surrounding environment is corrosive, the film is corroded and the intensity of the reflected signal drops significantly. In previous work, the sensing principle was verified by various experiments in laboratory and a packaging method was introduced. In this paper, the method of multiplexing several sensors by optical time domain reflectometer (OTDR) and optical splitter is introduced, together with the interpretation of OTDR results. The practical applicability of the proposed sensors is demonstrated in a three-year field trial with the sensors installed in an aggressive marine environment. The durability of the sensor against chemical degradation and physical degradation is also verified by accelerated life test and freeze-thaw cycling test, respectively.

Tilt performance of the ground settlement sensor configured in a fiber-optic low-coherent interferometer.

PubMed

Zhang, Pinglei; Wei, Heming; Guo, Jingjing; Sun, Changsen

2016-10-01

Ground settlement (GS) is one of the causes that destroy the durability of reinforced concrete structures. It could lead to a deterioration in the structural basement and increase the risk of collapse. The methods used for GS monitoring were mostly electronic-based sensors for reading the changes in resistance, resonant frequencies, etc. These sensors often bear low accuracy in the long term. Our published work demonstrated that a fiber-optic low-coherent interferometer configured in a Michelson interferometer was designed as a GS sensor, and a micro-meter resolution in the room environment was approached. However, the designed GS sensor, which in principle is based on a hydraulic connecting vessel, has to suffer from a tilt degeneration problem due to a strictly vertical requirement in practical installment. Here, we made a design for the GS sensor based on its robust tilt performance. The experimental tests show that the sensor can work well within a ±5° tilt. This could meet the requirements in most designed GS sensor installment applications.

Phonon quarticity induced by changes in phonon-tracked hybridization during lattice expansion and its stabilization of rutile TiO 2

DOE PAGES

Lan, Tian; Li, Chen W.; Hellman, O.; ...

2015-08-11

Although the rutile structure of TiO 2 is stable at high temperatures, the conventional quasiharmonic approximation predicts that several acoustic phonons decrease anomalously to zero frequency with thermal expansion, incorrectly predicting a structural collapse at temperatures well below 1000 K. In this paper, inelastic neutron scattering was used to measure the temperature dependence of the phonon density of states (DOS) of rutile TiO 2 from 300 to 1373 K. Surprisingly, these anomalous acoustic phonons were found to increase in frequency with temperature. First-principles calculations showed that with lattice expansion, the potentials for the anomalous acoustic phonons transform from quadratic tomore » quartic, stabilizing the rutile phase at high temperatures. In these modes, the vibrational displacements of adjacent Ti and O atoms cause variations in hybridization of 3d electrons of Ti and 2p electrons of O atoms. Finally, with thermal expansion, the energy variation in this “phonon-tracked hybridization” flattens the bottom of the interatomic potential well between Ti and O atoms, and induces a quarticity in the phonon potential.« less

System to Detect Racial-Based Bullying through Gamification.

PubMed

Álvarez-Bermejo, José A; Belmonte-Ureña, Luis J; Martos-Martínez, Africa; Barragán-Martín, Ana B; Del Mar Simón-Marquez, María

2016-01-01

Prevention and detection of bullying due to racial stigma was studied in school contexts using a system designed following "gamification" principles and integrating less usual elements, such as social interaction, augmented reality and cell phones in educational scenarios. "Grounded Theory" and "User Centered Design" were employed to explore coexistence inside and outside the classroom in terms of preferences and distrust in several areas of action and social frameworks of activity, and to direct the development of a cell phone app for early detection of school bullying scenarios. One hundred and fifty-one interviews were given at five schools selected for their high multiracial percentage and conflict. The most outstanding results were structural, that is the distribution of the classroom group by type of activity and subject being dealt with. Furthermore, in groups over 12 years of age, the relational structures in the classroom in the digital settings in which they participated with their cell phones did not reoccur, because face-to-face and virtual interaction between students with the supervision and involvement of the teacher combined to detect bullying caused by racial discrimination.

System to Detect Racial-Based Bullying through Gamification

PubMed Central

Álvarez-Bermejo, José A.; Belmonte-Ureña, Luis J.; Martos-Martínez, Africa; Barragán-Martín, Ana B.; del Mar Simón-Marquez, María

2016-01-01

Prevention and detection of bullying due to racial stigma was studied in school contexts using a system designed following “gamification” principles and integrating less usual elements, such as social interaction, augmented reality and cell phones in educational scenarios. “Grounded Theory” and “User Centered Design” were employed to explore coexistence inside and outside the classroom in terms of preferences and distrust in several areas of action and social frameworks of activity, and to direct the development of a cell phone app for early detection of school bullying scenarios. One hundred and fifty-one interviews were given at five schools selected for their high multiracial percentage and conflict. The most outstanding results were structural, that is the distribution of the classroom group by type of activity and subject being dealt with. Furthermore, in groups over 12 years of age, the relational structures in the classroom in the digital settings in which they participated with their cell phones did not reoccur, because face-to-face and virtual interaction between students with the supervision and involvement of the teacher combined to detect bullying caused by racial discrimination. PMID:27933006

Hydrogen adsorption in metal-decorated silicon carbide nanotubes

NASA Astrophysics Data System (ADS)

Singh, Ram Sevak; Solanki, Ankit

2016-09-01

Hydrogen storage for fuel cell is an active area of research and appropriate materials with excellent hydrogen adsorption properties are highly demanded. Nanotubes, having high surface to volume ratio, are promising storage materials for hydrogen. Recently, silicon carbide nanotubes have been predicted as potential materials for future hydrogen storage application, and studies in this area are ongoing. Here, we report a systematic study on hydrogen adsorption properties in metal (Pt, Ni and Al) decorated silicon carbide nanotubes (SiCNTs) using first principles calculations based on density functional theory. The hydrogen adsorption properties are investigated by calculations of adsorption energy, electronic band structure, density of states (DOS) and Mulliken charge population analysis. Our findings show that hydrogen adsorptions on Pt, Ni and Al-decorated SiCNTs undergo spontaneous exothermic reactions with significant modulation of electronic structure of SiCNTs in all cases. Importantly, according to the Mulliken charge population analysis, dipole-dipole interaction causes chemisorptions of hydrogen in Pt, Ni and Al decorated SiCNTs with formation of chemical bonds. The study is a platform for the development of metal decorated SiCNTs for hydrogen adsorption or hydrogen storage application.

Structure and Thermodynamical Properties of Zirconium Hydrides from First-Principle

NASA Astrophysics Data System (ADS)

Blomqvist, Jakob; Olofsson, Johan; Alvarez, Anna-Maria; Bjerkén, Christina

Zirconium alloys are used as nuclear fuel cladding material due to their mechanical and corrosion resistant properties together with their favorable cross-section for neutron scattering. At running conditions, however, there will be an increase of hydrogen in the vicinity of the cladding surface at the water side of the fuel. The hydrogen will diffuse into the cladding material and at certain conditions, such as lower temperatures and external load, hydrides will precipitate out in the material and cause well known embrittlement, blistering and other unwanted effects. Using phase-field methods it is now possible to model precipitation buildup in metals, for example as a function of hydrogen concentration, temperature and external load, but the technique relies on input of parameters, such as the formation energy of the hydrides and matrix. To that end, we have computed, using the density functional theory (DFT) code GPAW, the latent heat of fusion as well as solved the crystal structure for three zirconium hydride polymorphs: δ-ZrH1.6, γ-ZrH, and Є-ZrH2.

Interface-induced multiferroism by design in complex oxide superlattices

PubMed Central

Guo, Hangwen; Wang, Zhen; Dong, Shuai; Ghosh, Saurabh; Saghayezhian, Mohammad; Chen, Lina; Weng, Yakui; Herklotz, Andreas; Ward, Thomas Z.; Jin, Rongying; Pantelides, Sokrates T.; Zhu, Yimei; Zhang, Jiandi; Plummer, E. W.

2017-01-01

Interfaces between materials present unique opportunities for the discovery of intriguing quantum phenomena. Here, we explore the possibility that, in the case of superlattices, if one of the layers is made ultrathin, unexpected properties can be induced between the two bracketing interfaces. We pursue this objective by combining advanced growth and characterization techniques with theoretical calculations. Using prototype La2/3Sr1/3MnO3 (LSMO)/BaTiO3 (BTO) superlattices, we observe a structural evolution in the LSMO layers as a function of thickness. Atomic-resolution EM and spectroscopy reveal an unusual polar structure phase in ultrathin LSMO at a critical thickness caused by interfacing with the adjacent BTO layers, which is confirmed by first principles calculations. Most important is the fact that this polar phase is accompanied by reemergent ferromagnetism, making this system a potential candidate for ultrathin ferroelectrics with ferromagnetic ordering. Monte Carlo simulations illustrate the important role of spin–lattice coupling in LSMO. These results open up a conceptually intriguing recipe for developing functional ultrathin materials via interface-induced spin–lattice coupling. PMID:28607082

Improving ex vivo skin permeation of non-steroidal anti-inflammatory drugs: enhancing extemporaneous transformation of liposomes into planar lipid bilayers.

PubMed

Vázquez-González, Martha L; Bernad, Rafael; Calpena, Ana C; Domènech, Oscar; Montero, M T; Hernández-Borrell, Jordi

2014-01-30

Transdermal delivery of active principles is a versatile method widely used in medicine. The main drawback for the transdermal route, however, is the low efficiency achieved in the absorption of many drugs, mostly due to the complexity of the skin barrier. To improve drug delivery through the skin, we prepared and characterized liposomes loaded with ibuprofen and designed pharmaceutical formulations based on the extemporaneous addition of penetration enhancer (PE) surfactants. Afterwards, permeation and release studies were carried out. According to the permeation studies, the ibuprofen liposomal formulation supplemented with PEs exhibited similar therapeutic effects, but at lower doses (20%) comparing with a commercial formulation used as a reference. Atomic force microscopy (AFM) was used to investigate the effect caused by PEs on the adsorption mechanism of liposomal formulations onto the skin. Non-fused liposomes, bilayers and multilayered lipid structures were observed. The transformation of vesicles into planar structures is proposed as a possible rationale for explaining the lower doses required when a liposome formulation is supplemented with surfactant PEs. Copyright © 2013 Elsevier B.V. All rights reserved.

Using active colloids as machines to weave and braid on the micrometer scale

NASA Astrophysics Data System (ADS)

Goodrich, Carl P.; Brenner, Michael P.

2017-01-01

Controlling motion at the microscopic scale is a fundamental goal in the development of biologically inspired systems. We show that the motion of active, self-propelled colloids can be sufficiently controlled for use as a tool to assemble complex structures such as braids and weaves out of microscopic filaments. Unlike typical self-assembly paradigms, these structures are held together by geometric constraints rather than adhesive bonds. The out-of-equilibrium assembly that we propose involves precisely controlling the 2D motion of active colloids so that their path has a nontrivial topology. We demonstrate with proof-of-principle Brownian dynamics simulations that, when the colloids are attached to long semiflexible filaments, this motion causes the filaments to braid. The ability of the active particles to provide sufficient force necessary to bend the filaments into a braid depends on a number of factors, including the self-propulsion mechanism, the properties of the filament, and the maximum curvature in the braid. Our work demonstrates that nonequilibrium assembly pathways can be designed using active particles.

Interface-induced multiferroism by design in complex oxide superlattices

DOE PAGES

Guo, Hangwen; Wang, Zhen; Dong, Shuai; ...

2017-05-19

Interfaces between materials present unique opportunities for the discovery of intriguing quantum phenomena. Here, we explore the possibility that, in the case of superlattices, if one of the layers is made ultrathin, unexpected properties can be induced between the two bracketing interfaces. We pursue this objective by combining advanced growth and characterization techniques with theoretical calculations. Using prototype La 2/3Sr 1/3MnO 3 (LSMO)/BaTiO 3 (BTO) superlattices, we observe a structural evolution in the LSMO layers as a function of thickness. Atomic-resolution EM and spectroscopy reveal an unusual polar structure phase in ultrathin LSMO at a critical thickness caused by interfacingmore » with the adjacent BTO layers, which is confirmed by first principles calculations. Most important is the fact that this polar phase is accompanied by reemergent ferromagnetism, making this system a potential candidate for ultrathin ferroelectrics with ferromagnetic ordering. Monte Carlo simulations illustrate the important role of spin–lattice coupling in LSMO. These results open up a conceptually intriguing recipe for developing functional ultrathin materials via interface-induced spin–lattice coupling.« less

Using active colloids as machines to weave and braid on the micrometer scale

PubMed Central

Goodrich, Carl P.; Brenner, Michael P.

2017-01-01

Controlling motion at the microscopic scale is a fundamental goal in the development of biologically inspired systems. We show that the motion of active, self-propelled colloids can be sufficiently controlled for use as a tool to assemble complex structures such as braids and weaves out of microscopic filaments. Unlike typical self-assembly paradigms, these structures are held together by geometric constraints rather than adhesive bonds. The out-of-equilibrium assembly that we propose involves precisely controlling the 2D motion of active colloids so that their path has a nontrivial topology. We demonstrate with proof-of-principle Brownian dynamics simulations that, when the colloids are attached to long semiflexible filaments, this motion causes the filaments to braid. The ability of the active particles to provide sufficient force necessary to bend the filaments into a braid depends on a number of factors, including the self-propulsion mechanism, the properties of the filament, and the maximum curvature in the braid. Our work demonstrates that nonequilibrium assembly pathways can be designed using active particles. PMID:28034922

SU-E-T-191: PITSTOP: Process Improvement Techniques, Software Tools, and Operating Principles for a Quality Initiative Discovery Framework.

PubMed

Siochi, R

2012-06-01

To develop a quality initiative discovery framework using process improvement techniques, software tools and operating principles. Process deviations are entered into a radiotherapy incident reporting database. Supervisors use an in-house Event Analysis System (EASy) to discuss incidents with staff. Major incidents are analyzed with an in-house Fault Tree Analysis (FTA). A meta-Analysis is performed using association, text mining, key word clustering, and differential frequency analysis. A key operating principle encourages the creation of forcing functions via rapid application development. 504 events have been logged this past year. The results for the key word analysis indicate that the root cause for the top ranked key words was miscommunication. This was also the root cause found from association analysis, where 24% of the time that an event involved a physician it also involved a nurse. Differential frequency analysis revealed that sharp peaks at week 27 were followed by 3 major incidents, two of which were dose related. The peak was largely due to the front desk which caused distractions in other areas. The analysis led to many PI projects but there is still a major systematic issue with the use of forms. The solution we identified is to implement Smart Forms to perform error checking and interlocking. Our first initiative replaced our daily QA checklist with a form that uses custom validation routines, preventing therapists from proceeding with treatments until out of tolerance conditions are corrected. PITSTOP has increased the number of quality initiatives in our department, and we have discovered or confirmed common underlying causes of a variety of seemingly unrelated errors. It has motivated the replacement of all forms with smart forms. © 2012 American Association of Physicists in Medicine.

12 CFR 1780.26 - Discovery.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Constitution, any applicable act of Congress, or the principles of common law. (e) Time limits. All discovery... the presiding officer finds on the record that good cause exists for waiving the requirements of this...

Structural studies of TiC{sub 1−x}O{sub x} solid solution by Rietveld refinement and first-principles calculations

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

Jiang, Bo, E-mail: youqin5912@yahoo.com.cn; Hou, Na; Huang, Shanyan

2013-08-15

The lattice parameters, structural stability and electronic structure of titanium oxycarbides (TiC{sub 1−x}O{sub x}, 0≤x≤1) solid solution were investigated by Rietveld refinement and first-principles calculations. Series of TiC{sub 1−x}O{sub x} were precisely synthesized by sintering process under the vacuum. Rietveld refinement results of XRD patterns show the properties of continuous solid solution in TiC{sub 1−x}O{sub x} over the whole composition range. The lattice parameters vary from 0.4324 nm to 0.4194 nm decreasing with increasing oxygen concentration. Results of first-principles calculations reveal that the disorder C/O structure is stable than the order C/O structure. Further investigations of the vacancy in Ti{submore » 1−Va}(C{sub 1−x}O{sub x}){sub 1−Va} solid solution present that the structure of vacancy segregated in TiO-part is more stable than the disorder C/O structure, which can be ascribed to the Ti–Ti bond across O-vacancy and the charge redistributed around Ti-vacancy via the analysis of the electron density difference plots and PDOS. - Graphical abstract: XRD of series of titanium oxycarbides (TiC{sub 1−x}O{sub x}, 0≤x≤1) solid solution prepared by adjusting the proportion of TiO in the starting material. Highlights: • Titanium oxycarbides were obtained by sintering TiO and TiC under carefully controlled conditions. • Rietveld refinement results show continuous solid solution with FCC structure in TiC{sub 1−x}O{sub x}. • The disorder C/O structure is stable than the order C/O structure. • Introduction of vacancy segregated in TiO-part is more stable than disorder C/O structure. • Ti–Ti bond across O-vacancy and the charge redistributed around Ti-vacancy enhance structural stability.« less

Hydrocerussite-related minerals and materials: structural principles, chemical variations and infrared spectroscopy.

PubMed

Siidra, Oleg; Nekrasova, Diana; Depmeier, Wulf; Chukanov, Nikita; Zaitsev, Anatoly; Turner, Rick

2018-04-01

White lead or basic lead carbonate, 2PbCO 3 ·Pb(OH) 2 , the synthetic analogue of hydrocerussite Pb 3 (OH) 2 (CO 3 ) 2 , has been known since antiquity as the most frequently used white paint. A number of different minerals and synthetic materials compositionally and structurally related to hydrocerussite have been described within the last two decades. Herein, a review is given of general structural principles, chemical variations and IR spectra of the rapidly growing family of hydrocerussite-related minerals and synthetic materials. Only structures containing a hydroxo- and/or oxo-component, i.e. which are compositionally directly related with hydrocerussite and `white lead', are reviewed in detail. An essential structural feature of all the considered phases is the presence of electroneutral [PbCO 3 ] 0 cerussite-type layers or sheets. Various interleaved sheets can be incorporated between the cerussite-type sheets. Different sheets are stacked into two-dimensional blocks separated by the stereochemically active 6s 2 lone electron pairs on Pb 2+ cations. Minerals and synthetic materials described herein, together with a number of still hypothetical members, constitute a family of modular structures. Hydrocerussite, abellaite and grootfonteinite can be considered to constitute a merotype family of structures. The remaining hydrocerussite-related structures discussed are built on similar principles, but are more complex. Structural architectures of somersetite and slag phase from Lavrion, Attica, Greece, are unique for oxysalt mineral structures in general. Thus, the whole family of hydrocerussite-related phases can be denoted as a plesiotype family of modular structures. The crystal structures of hydrocerussite from Merehead quarry, Somerset, England, and of its synthetic analogue, both determined from single crystals, are reported here for the first time. The results of the infrared (IR) spectroscopy show that this method is useful for distinguishing several different minerals related to hydrocerussite and their synthetic analogues.

The Structures & Properties of Carbon

ERIC Educational Resources Information Center

Castellini, Olivia M.; Lisensky, George C.; Ehrlich, Jennifer; Zenner, Greta M.; Crone, Wendy C.

2006-01-01

The four main forms of carbon--diamond, graphite, buckyballs, and carbon nanotubes (CNTs)--are an excellent vehicle for teaching fundamental principles of chemical bonding, material structure, and properties. Carbon atoms form a variety of structures that are intrinsically connected to the properties they exhibit. Educators can take advantage of…