Interpreting anomalous electron pairs as new particle decays

NASA Astrophysics Data System (ADS)

Wilczynski, Henryk

1999-08-01

In heavy particle decays found in cosmic ray interactions recorded in the JACEE emulsion chambers, multiple electron pairs were previously reported. These pairs apparently originated from conversions of photons emitted in the decays. It is difficult to explain the overall properties of these decays in terms of known heavy particle decay modes. A recently published compilation of low-energy nuclear data suggests existence of excess electron pairs with invariant mass about 9 MeV/c2 , which may be explained by postulating a new neutral boson decaying into the electron pair. The feasibility of explaining the JACEE electron pairs with this hypothesis is presented.

Influence of Role-Switching on Phonetic Convergence in Conversation

ERIC Educational Resources Information Center

Pardo, Jennifer S.; Jay, Isabel Cajori; Hoshino, Risa; Hasbun, Sara Maria; Sowemimo-Coker, Chantal; Krauss, Robert M.

2013-01-01

The current study examined phonetic convergence when talkers alternated roles during conversational interaction. The talkers completed a map navigation task in which they alternated instruction Giver and Receiver roles across multiple map pairs. Previous studies found robust effects of the role of a talker on phonetic convergence, and it was…

Retrospective Analysis of Cognitive and Affective Responses in Intercultural and Intracultural Conversations

ERIC Educational Resources Information Center

Nguyen, Duyen T.; Fussell, Susan R.

2015-01-01

We report a study that uses retrospective analysis to understand the relationships between American and Chinese participants' utterances during a conversation and the moment-by-moment feelings and reactions they subsequently described. Intercultural and intracultural pairs of Chinese and American participants talked about a fictional crime story…

Einstein-Podolsky-Rosen-Bohm experiment and Bell inequality violation using Type 2 parametric down conversion

NASA Technical Reports Server (NTRS)

Kiess, Thomas E.; Shih, Yan-Hua; Sergienko, A. V.; Alley, Carroll O.

1994-01-01

We report a new two-photon polarization correlation experiment for realizing the Einstein-Podolsky-Rosen-Bohm (EPRB) state and for testing Bell-type inequalities. We use the pair of orthogonally-polarized light quanta generated in Type 2 parametric down conversion. Using 1 nm interference filters in front of our detectors, we observe from the output of a 0.5mm beta - BaB2O4 (BBO) crystal the EPRB correlations in coincidence counts, and measure an associated Bell inequality violation of 22 standard deviations. The quantum state of the photon pair is a polarization analog of the spin-1/2 singlet state.

Effects of activity interference on annoyance due to aircraft noise

NASA Technical Reports Server (NTRS)

Willshire, K. F.; Powell, C. A.

1981-01-01

The effects of aircraft flyover noise on annoyance were compared for face to face conversation, reverie, and television viewing. Eighteen 5 minute sessions, each composed of three flyovers, were presented on each of 2 days to subjects in a simulated living room. Twelve pairs of females and 12 pairs of males were tested, once before and once after work. Flyovers varied in peak noise level from 53 to 83 dB, A weighted. On each day, subjects engaged in 18 sessions, six of conversation, six of television viewing, and six of reverie. The subjects completed subjective ratings of annoyance and acceptability following every session. Annoyance and unacceptability rating scores were significantly higher for the activity of television viewing compared to conversation or reverie. There was no difference between judgments during the latter two activities. No differences were found in the judgments when compared on the basis of "fatigue" (before/after work) or sex of the subject.

Resonance coupling and polarization conversion in terahertz metasurfaces with twisted split-ring resonator pairs

DOE PAGES

Li, Chenyu; Chang, Chun-Chieh; Zhou, Qingli; ...

2017-10-10

Here, we investigate edge-coupling of twisted split-ring resonator (SRR) pairs in the terahertz (THz) frequency range. By using a simple coupled-resonator model we show that such a system exhibits resonance splitting and cross-polarization conversion. Numerical simulations and experimental measurements agree well with theoretical calculations, verifying the resonance splitting as a function of the coupling strength given by the SRR separation. We further show that a metal ground plane can be integrated to significantly enhance the resonance coupling, which enables the effective control of resonance splitting and the efficiency and bandwidth of the cross-polarization conversion. Our findings improve the fundamental understandingmore » of metamaterials with a view of accomplishing metamaterial functionalities with enhanced performance, which is of great interest in realizing THz functional devices required in a variety of applications.« less

Probing CP violation in $$h\\rightarrow\\gamma\\gamma$$ with converted photons

DOE PAGES

Bishara, Fady; Grossman, Yuval; Harnik, Roni; ...

2014-04-11

We study Higgs diphoton decays, in which both photons undergo nuclear conversion to electron- positron pairs. The kinematic distribution of the two electron-positron pairs may be used to probe the CP violating (CPV) coupling of the Higgs to photons, that may be produced by new physics. Detecting CPV in this manner requires interference between the spin-polarized helicity amplitudes for both conversions. We derive leading order, analytic forms for these amplitudes. In turn, we obtain compact, leading-order expressions for the full process rate. While performing experiments involving photon conversions may be challenging, we use the results of our analysis to constructmore » experimental cuts on certain observables that may enhance sensitivity to CPV. We show that there exist regions of phase space on which sensitivity to CPV is of order unity. As a result, the statistical sensitivity of these cuts are verified numerically, using dedicated Monte-Carlo simulations.« less

Apparatuses and method for converting electromagnetic radiation to direct current

DOEpatents

Kotter, Dale K; Novack, Steven D

2014-09-30

An energy conversion device may include a first antenna and a second antenna configured to generate an AC current responsive to incident radiation, at least one stripline, and a rectifier coupled with the at least one stripline along a length of the at least one stripline. An energy conversion device may also include an array of nanoantennas configured to generate an AC current in response to receiving incident radiation. Each nanoantenna of the array includes a pair of resonant elements, and a shared rectifier operably coupled to the pair of resonant elements, the shared rectifier configured to convert the AC current to a DC current. The energy conversion device may further include a bus structure operably coupled with the array of nanoantennas and configured to receive the DC current from the array of nanoantennas and transmit the DC current away from the array of nanoantennas.

Designing for Learning Conversations: How Parents Support Children's Science Learning within an Immersive Simulation

ERIC Educational Resources Information Center

Tscholl, Michael; Lindgren, Robb

2016-01-01

This research investigates the social learning affordances of a room-sized, immersive, and interactive augmented reality simulation environment designed to support children's understanding of basic physics concepts in a science center. Conversations between 97 parent-child pairs were analyzed in relation to categories of talk through which…

Strengths-Based Advising Approaches: Benefits for First-Year Undergraduates

ERIC Educational Resources Information Center

Soria, Krista M.; Laumer, Nicole L.; Morrow, Dale J.; Marttinen, Garrett

2017-01-01

We explored the benefits of strengths-based academic advising approaches for first-year students (N = 1,228). We used propensity score matching techniques to create matched pairs of students who did and did not engage in strengths-based advising conversations with an advisor. First-year students who experienced strengths-based conversations had…

Foreign Language Students' Conversational Negotiations in Different Task Environments

ERIC Educational Resources Information Center

Hardy, Ilonca M.; Moore, Joyce L.

2004-01-01

This study examined the effect of structural and content characteristics of language tasks on foreign language learners' conversational negotiations. In a 2x2 Greco-Latin square design, degree of structural support of language tasks, students' degree of familiarity with German video segments, and task order were varied. Twenty-eight pairs of…

Selective photooxidation of hydrocarbons in zeolites by oxygen

DOEpatents

Frei, Heinz; Blatter, Fritz; Sun, Hai

1998-01-01

A selective photooxidation process for the conversion of hydrocarbon molecules to partially oxygenated derivatives, which comprises the steps of adsorbing a hydrocarbon and oxygen onto a dehydrated zeolite support matrix to form a hydrocarbon-oxygen contact pair, and subsequently exposing the hydrocarbon-oxygen contact pair to visible light, thereby forming a partially oxygenated derivative.

Evaluation of coal-related model compounds using a tandem mass spectrometry.

PubMed

Li, Guo-Sheng; Dong, Xueming; Fan, Xing; You, Chun-Yan; Wu, Ge; Zhao, Yun-Peng; Lu, Yao; Wei, Xian-Yong; Ma, Feng-Yun

2018-05-08

Gas chromotography/mass spectrometry (GC/MS) is a routine and basic instrumental method for the analysis of complex coal conversion products in chemical industry. To further enhance practical potentials of GC/MS in chemical industry, a tandem MS method for the selection of ion pair applied in monitoring coal conversions was established by using GC/quadrupole time-of-flight MS (GC/Q-TOF MS). The corresponding fragmentation pathways were explored and suitable ion pairs were screened. Fourteen coal-related model compounds (CRMCs) were analyzed using a GC/Q-TOF MS with different collision induced dissociation (CID) energies (5-20 eV). The fragmentation pathways can offer a better understanding of chemical bond breaking, hydrogen transfer, rearrangement reactions and elimination of neutral fragments for CRMCs during the CID process. The precursor ions of aromatic hydrocarbons without alkyl chain were hard to fragment with a CID energy of 20 eV. But aromatic hydrocarbons with branched chains were prone to fragment via the loss of alkyl chains and further fragmented through ring-open reactions. Compared to C alk -C ar bond, C ar -C ar bond was hard to fragment duo to its high bond dissociation energy. The existence of heteroatoms facilitated fragmentation that was conducive to screening ion pair. The CID technique of GC/Q-TOF MS will contribute to the studies on the organic composition of coals and building monitoring methods for coal conversions via fragmentation and ion pair selection. This article is protected by copyright. All rights reserved.

The Impact of Mutation and Gene Conversion on the Local Diversification of Antigen Genes in African Trypanosomes

PubMed Central

Gjini, Erida; Haydon, Daniel T.; Barry, J. David; Cobbold, Christina A.

2012-01-01

Patterns of genetic diversity in parasite antigen gene families hold important information about their potential to generate antigenic variation within and between hosts. The evolution of such gene families is typically driven by gene duplication, followed by point mutation and gene conversion. There is great interest in estimating the rates of these processes from molecular sequences for understanding the evolution of the pathogen and its significance for infection processes. In this study, a series of models are constructed to investigate hypotheses about the nucleotide diversity patterns between closely related gene sequences from the antigen gene archive of the African trypanosome, the protozoan parasite causative of human sleeping sickness in Equatorial Africa. We use a hidden Markov model approach to identify two scales of diversification: clustering of sequence mismatches, a putative indicator of gene conversion events with other lower-identity donor genes in the archive, and at a sparser scale, isolated mismatches, likely arising from independent point mutations. In addition to quantifying the respective probabilities of occurrence of these two processes, our approach yields estimates for the gene conversion tract length distribution and the average diversity contributed locally by conversion events. Model fitting is conducted using a Bayesian framework. We find that diversifying gene conversion events with lower-identity partners occur at least five times less frequently than point mutations on variant surface glycoprotein (VSG) pairs, and the average imported conversion tract is between 14 and 25 nucleotides long. However, because of the high diversity introduced by gene conversion, the two processes have almost equal impact on the per-nucleotide rate of sequence diversification between VSG subfamily members. We are able to disentangle the most likely locations of point mutations and conversions on each aligned gene pair. PMID:22735079

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions.

PubMed

Denlinger, Kendra Leahy; Ortiz-Trankina, Lianna; Carr, Preston; Benson, Kingsley; Waddell, Daniel C; Mack, James

2018-01-01

Mechanochemistry is maturing as a discipline and continuing to grow, so it is important to continue understanding the rules governing the system. In a mechanochemical reaction, the reactants are added into a vessel along with one or more grinding balls and the vessel is shaken at high speeds to facilitate a chemical reaction. The dielectric constant of the solvent used in liquid-assisted grinding (LAG) and properly chosen counter-ion pairing increases the percentage conversion of stilbenes in a mechanochemical Wittig reaction. Utilizing stepwise addition/evaporation of ethanol in liquid-assisted grinding also allows for the tuning of the diastereoselectivity in the Wittig reaction.

Clustering of cycloidal wave energy converters

DOEpatents

Siegel, Stefan G.

2016-03-29

A wave energy conversion system uses a pair of wave energy converters (WECs) on respective active mountings on a floating platform, so that the separation of the WECs from each other or from a central WEC can be actively adjusted according to the wavelength of incident waves. The adjustable separation facilitates operation of the system to cancel reactive forces, which may be generated during wave energy conversion. Modules on which such pairs of WECs are mounted can be assembled with one or more central WECs to form large clusters in which reactive forces and torques can be made to cancel. WECs of different sizes can be employed to facilitate cancelation of reactive forces and torques.

Effects of conversation interference on annoyance due to aircraft noise

NASA Technical Reports Server (NTRS)

Key, K. F.; Powell, C. A.

1980-01-01

The annoyance and interference effects of aircraft flyover noise on face to face conversation were investigated. Twenty 5 minute sessions, each composed of three flyovers, were presented to each of 20 pairs of female subjects in a simulated living room. Flyovers varied in peak noise level (55-79 dB, A-weighted) and spectrum (low or high frequency components). Subjects engaged in conversation for 10 sessions and in reverie for the other 10 sessions, and completed subjective ratings following every session. Annoyance was affected by noise level, but was not significantly different for the two activities of reverie and conversation. A noise level of 77 db was found unacceptable for conversation by 50 percent of the subjects. Conversation interference was assessed by incidence of increased vocal effort and/or interruption of conversation during flyovers. Although conversation interference increased with noise level, the conversation interference measures did not improve prediction of individual annoyance judgments.

Femtosecond Laser--Pumped Source of Entangled Photons for Quantum Cryptography Applications

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

Pan, D.; Donaldson, W.; Sobolewski, R.

2007-07-31

We present an experimental setup for generation of entangled-photon pairs via spontaneous parametric down-conversion, based on the femtosecond-pulsed laser. Our entangled-photon source utilizes a 76-MHz-repetition-rate, 100-fs-pulse-width, mode-locked, ultrafast femtosecond laser, which can produce, on average, more photon pairs than a cw laser of an equal pump power. The resulting entangled pairs are counted by a pair of high-quantum-efficiency, single-photon, silicon avalanche photodiodes. Our apparatus is intended as an efficient source/receiver system for the quantum communications and quantum cryptography applications.

Improved Usability of Locomotion Devices Using Human-Centric Taxonomy

DTIC Science & Technology

2009-03-01

the muscle fibers to which they are attached. Our muscles work mainly in antagonistic pairs, with one muscle contracting and its antagonist...skeletal system by the muscles signifies a conversion of electrochemical energy into physical energy, and thus, constitutes the commencement of the...Function of antagonistic pairs in muscles ........................................... 22 Figure 10. Physical interaction between right leg and

Interfacing a quantum dot with a spontaneous parametric down-conversion source

NASA Astrophysics Data System (ADS)

Huber, Tobias; Prilmüller, Maximilian; Sehner, Michael; Solomon, Glenn S.; Predojević, Ana; Weihs, Gregor

2017-09-01

Quantum networks require interfacing stationary and flying qubits. These flying qubits are usually nonclassical states of light. Here we consider two of the leading source technologies for nonclassical light, spontaneous parametric down-conversion and single semiconductor quantum dots. Down-conversion delivers high-grade entangled photon pairs, whereas quantum dots excel at producing single photons. We report on an experiment that joins these two technologies and investigates the conditions under which optimal interference between these dissimilar light sources may be achieved.

Ultrasonic guided wave propagation across waveguide transitions: energy transfer and mode conversion.

PubMed

Puthillath, Padmakumar; Galan, Jose M; Ren, Baiyang; Lissenden, Cliff J; Rose, Joseph L

2013-05-01

Ultrasonic guided wave inspection of structures containing adhesively bonded joints requires an understanding of the interaction of guided waves with geometric and material discontinuities or transitions in the waveguide. Such interactions result in mode conversion with energy being partitioned among the reflected and transmitted modes. The step transition between an aluminum layer and an aluminum-adhesive-aluminum multi-layer waveguide is analyzed as a model structure. Dispersion analysis enables assessment of (i) synchronism through dispersion curve overlap and (ii) wavestructure correlation. Mode-pairs in the multi-layer waveguide are defined relative to a prescribed mode in a single layer as being synchronized and having nearly perfect wavestructure matching. Only a limited number of mode-pairs exist, and each has a unique frequency range. A hybrid model based on semi-analytical finite elements and the normal mode expansion is implemented to assess mode conversion at a step transition in a waveguide. The model results indicate that synchronism and wavestructure matching is associated with energy transfer through the step transition, and that the energy of an incident wave mode in a single layer is transmitted almost entirely to the associated mode-pair, where one exists. This analysis guides the selection of incident modes that convert into transmitted modes and improve adhesive joint inspection with ultrasonic guided waves.

Photon up-conversion production in Tb{sup 3+}–Yb{sup 3+} co-doped CaF{sub 2} phosphors prepared by combustion synthesis

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

Rakov, Nikifor, E-mail: nikifor.gomez@univasf.edu.br; Guimarães, Renato B.; Maciel, Glauco S., E-mail: glauco@if.uff.br

2016-02-15

Graphical abstract: Up-conversion luminescence from Tb{sup 3+} obtained by energy transfer from Yb{sup 3+} pairs in CaF{sub 2} powder prepared by combustion synthesis. - Highlights: • Calcium fluoride (CaF{sub 2}) powders were prepared by combustion synthesis. • Rare-earth ions doped in this material were found in interstitial sites. • Cooperative up-conversion was observed in Tb{sup 3+}:Yb{sup 3+}:CaF{sub 2} powder. • Energy transfer between Tb{sup 3+} and pairs of Yb{sup 3+} was analyzed using rate equations. - Abstract: Calcium fluoride (CaF{sub 2}) crystalline powders were successfully prepared by the combustion synthesis method. The powder material containing luminescent rare-earth ions, more specificallymore » terbium (Tb{sup 3+}) and ytterbium (Yb{sup 3+}), was studied by X-ray diffraction, scanning electronic microscopy and optical spectroscopy. These ions are allocated in charge compensated interstitial positions of tetragonal (C{sub 4v}) and trigonal (C{sub 3v}) symmetry sites of the cubic (O{sub h}) CaF{sub 2} lattice. Up-conversion (UC) luminescence in Tb{sup 3+} was achieved using a low power diode laser operating at 975 nm. Tb{sup 3+} is insensitive to near-infrared radiation but UC can be achieved via energy transfer from pairs of Yb{sup 3+} ions to Tb{sup 3+} ions. The UC luminescence dynamics of Tb{sup 3+} was used to study the energy transfer mechanism.« less

Thermodynamics and kinetics of Na+/K+-formate ion pairs association in polarizable water: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Nguyen, Phuong T. M.; Nguyen, Van T.; Annapureddy, Harsha V. R.; Dang, Liem X.; Do, D. D.

2012-12-01

To enhance our understanding of ion specific activity in biological systems, the potential of mean force approach was utilized to study solvent effects on the interactions between two alkali cations (Na+ and K+) with a formate anion in water. A very complex free energy landscape was observed, much more so than alkali-halide ion pairs. Furthermore, a stronger binding between the Na+-formate pair was found in comparison to the K+-formate pair in water, which is in agreement with experimental and theoretical studies [1-4]. The kinetics of ion-pair inter-conversions was studied using the transition rate theory, along with a number of theoretical approaches such as the Kramers and Grote-Hynes theories. These kinetic results were used to predict solvent effects on dynamical features of ion-pair association, in which we have found that the dynamics of K+-formate pairs is faster than Na+-formate pairs.

Learner Agency and Non-Native Speaker Identity in Pedagogical Lingua Franca Conversations: Insights from Intercultural Telecollaboration in Foreign Language Education

ERIC Educational Resources Information Center

Kohn, Kurt; Hoffstaedter, Petra

2017-01-01

This article discusses insights gained from a case study on telecollaboration for intercultural communication in foreign language school contexts. Focus was on non-native English and German lingua franca conversations between pairs of students (aged 14-16, B1 level) from schools in France, Germany, the Netherlands and Spain. Telecollaboration…

Understanding Task-in-Process through the Lens of Laughter: Activity Designs, Instructional Materials, Learner Orientations, and Interpersonal Relationships

ERIC Educational Resources Information Center

Hasegawa, Atsushi

2018-01-01

Using the framework of conversation analysis, this study investigated the interactional workings of laughter in task-based interactions. The analysis was drawn from 160 cases of pair work interactions, collected in 2nd-semester Japanese-as-a-foreign-language classrooms. The pair work activities examined in this study are mostly grammar-focused,…

Flexible Coordination of Stationary and Mobile Conversations with Gaze: Resource Allocation among Multiple Joint Activities

PubMed Central

Mayor, Eric; Bangerter, Adrian

2016-01-01

Gaze is instrumental in coordinating face-to-face social interactions. But little is known about gaze use when social interactions co-occur with other joint activities. We investigated the case of walking while talking. We assessed how gaze gets allocated among various targets in mobile conversations, whether allocation of gaze to other targets affects conversational coordination, and whether reduced availability of gaze for conversational coordination affects conversational performance and content. In an experimental study, pairs were videotaped in four conditions of mobility (standing still, talking while walking along a straight-line itinerary, talking while walking along a complex itinerary, or walking along a complex itinerary with no conversational task). Gaze to partners was substantially reduced in mobile conversations, but gaze was still used to coordinate conversation via displays of mutual orientation, and conversational performance and content was not different between stationary and mobile conditions. Results expand the phenomena of multitasking to joint activities. PMID:27822189

1.5-μm band polarization entangled photon-pair source with variable Bell states.

PubMed

Arahira, Shin; Kishimoto, Tadashi; Murai, Hitoshi

2012-04-23

In this paper we report a polarization-entangled photon-pair source in a 1.5-μm band which can generate arbitrary entangled states including four maximum entangled states (Bell states) by using cascaded optical second nonlinearities (second-harmonic generation and the following spontaneous parametric down conversion) in a periodically poled LiNbO(3) (PPLN) ridge-waveguide device. Exchange among the Bell states was achieved by using an optical phase bias compensator (OPBC) in a Sagnac loop interferometer and a half-wave plate outside the loop for polarization conversion. Quantitative evaluation was made on the performance of the photon-pair source through the experiments of two-photon interferences, quantum state tomography, and test of violation of Bell inequality. We observed high visibilities of 96%, fidelities of 97%, and 2.71 of the S parameter in inequality of Clauser, Horne, Shimony, and Holt (CHSH). The experimental values, including peak coincidence counts in the two-photon interference (approximately 170 counts per second), remained almost unchanged in despite of the exchange among the Bell states. They were also in good agreement with the theoretical assumption from the mean number of the photon-pairs under the test (0.04 per pulse). More detailed experimental studies on the dependence of the mean number of the photon-pairs revealed that the quantum states were well understood as the Werner state. © 2012 Optical Society of America

Is e+e- pair emission important in the determination of the 3He+4He S factor?

NASA Astrophysics Data System (ADS)

Snover, K. A.; Hurd, A. E.

2003-05-01

We show that the cross section for direct E0 pair emission is related to the cross section for direct E2 photon emission, and is a negligible contribution to the total capture cross section for 3He+4He→7Be. E0 resonance emission, E1 pair emission, and internal conversion are also negligible. Thus there cannot be significant contributions to the 3He+4He→7Be capture cross section at low energies from electromagnetic emission processes other than single photon emission.

Effect of the Molecular Nature of Mutation on the Efficiency of Intrachromosomal Gene Conversion in Mouse Cells

PubMed Central

Letsou, Anthea; Liskay, R. Michael

1987-01-01

With the intent of further exploring the nature of gene conversion in mammalian cells, we systematically addressed the effects of the molecular nature of mutation on the efficiency of intrachromosomal gene conversion in cultured mouse cells. Comparison of conversion rates revealed that all mutations studied were suitable substrates for gene conversion; however, we observed that the rates at which different mutations converted to wild-type could differ by two orders of magnitude. Differences in conversion rates were correlated with the molecular nature of the mutations. In general, rates of conversion decreased with increasing size of the molecular lesions. In comparisons of conversion rates for single base pair insertions and deletions we detected a genotype-directed path for conversion, by which an insertion was converted to wild-type three to four times more efficiently than was a deletion which maps to the same site. The data are discussed in relation to current theories of gene conversion, and are consistent with the idea that gene conversion in mammalian cells can result from repair of heteroduplex DNA (hDNA) intermediates. PMID:2828159

Twofold spin-triplet pairing states and tunneling conductance in ferromagnet/ferromagnet/iron pnictide superconductor heterojunctions

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

Yang, X.; Tao, Y.C., E-mail: yctao88@163.com; Dong, Z.C.

By applying an extended eight-component Bogoliubov–de Gennes equation, we study theoretically the tunneling conductance in clean ferromagnet/ferromagnet/iron pnictide superconductor (FM/FM/iron-based SC) heterojunctions. Under the condition of noncollinear magnetizations, twofold novel Andreev reflections exist due to the existence of two bands in the SC, in which the incident electron and the two Andreev-reflected holes, belonging to the same spin subband, form twofold spin-triplet pairing states near the FM/iron-based SC interface. It is shown that the conversions of the conductance not only between the zero-bias peak and valley at zero energy but also between the peaks and dips at two gap energiesmore » are strongly dependent on both the interband coupling strength in the SC and the spin polarization in the FM. The qualitative differences from tunneling into a conventional s-wave SC are also presented, which may help with experimentally probing and identifying the antiphase s-wave pairing symmetry in the iron-based SC. -- Highlights: •An eight-component Bogoliubov–de Gennes (BDG) equation. •Twofold novel ARs and twofold usual ARs. •Conversions of conductance between the zero-bias peak and valley at zero energy. •Conversions of conductance between peaks and dips at two gap energies. •The importance of the interband coupling strength in the SC.« less

Multi-client quantum key distribution using wavelength division multiplexing

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

Grice, Warren P; Bennink, Ryan S; Earl, Dennis Duncan

Quantum Key Distribution (QKD) exploits the rules of quantum mechanics to generate and securely distribute a random sequence of bits to two spatially separated clients. Typically a QKD system can support only a single pair of clients at a time, and so a separate quantum link is required for every pair of users. We overcome this limitation with the design and characterization of a multi-client entangled-photon QKD system with the capacity for up to 100 clients simultaneously. The time-bin entangled QKD system includes a broadband down-conversion source with two unique features that enable the multi-user capability. First, the photons aremore » emitted across a very large portion of the telecom spectrum. Second, and more importantly, the photons are strongly correlated in their energy degree of freedom. Using standard wavelength division multiplexing (WDM) hardware, the photons can be routed to different parties on a quantum communication network, while the strong spectral correlations ensure that each client is linked only to the client receiving the conjugate wavelength. In this way, a single down-conversion source can support dozens of channels simultaneously--and to the extent that the WDM hardware can send different spectral channels to different clients, the system can support multiple client pairings. We will describe the design and characterization of the down-conversion source, as well as the client stations, which must be tunable across the emission spectrum.« less

Experimental extraction of an entangled photon pair from two identically decohered pairs.

PubMed

Yamamoto, Takashi; Koashi, Masato; Ozdemir, Sahin Kaya; Imoto, Nobuyuki

2003-01-23

Entanglement is considered to be one of the most important resources in quantum information processing schemes, including teleportation, dense coding and entanglement-based quantum key distribution. Because entanglement cannot be generated by classical communication between distant parties, distribution of entangled particles between them is necessary. During the distribution process, entanglement between the particles is degraded by the decoherence and dissipation processes that result from unavoidable coupling with the environment. Entanglement distillation and concentration schemes are therefore needed to extract pairs with a higher degree of entanglement from these less-entangled pairs; this is accomplished using local operations and classical communication. Here we report an experimental demonstration of extraction of a polarization-entangled photon pair from two decohered photon pairs. Two polarization-entangled photon pairs are generated by spontaneous parametric down-conversion and then distributed through a channel that induces identical phase fluctuations to both pairs; this ensures that no entanglement is available as long as each pair is manipulated individually. Then, through collective local operations and classical communication we extract from the two decohered pairs a photon pair that is observed to be polarization-entangled.

Efficiency of Synchrotron Radiation from Rotation-powered Pulsars

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

Kisaka, Shota; Tanaka, Shuta J., E-mail: kisaka@phys.aoyama.ac.jp, E-mail: sjtanaka@center.konan-u.ac.jp

2017-03-01

Synchrotron radiation is widely considered to be the origin of the pulsed non-thermal emissions from rotation-powered pulsars in optical and X-ray bands. In this paper, we study the synchrotron radiation emitted by the created electron and positron pairs in the pulsar magnetosphere to constrain the energy conversion efficiency from the Poynting flux to the particle energy flux. We model two pair creation processes, two-photon collision, which efficiently works in young γ -ray pulsars (≲10{sup 6} year), and magnetic pair creation, which is the dominant process to supply pairs in old pulsars (≳10{sup 6} year). Using the analytical model, we derivemore » the maximum synchrotron luminosity as a function of the energy conversion efficiency. From the comparison with observations, we find that the energy conversion efficiency to the accelerated particles should be an order of unity in the magnetosphere, even though we make a number of the optimistic assumptions to enlarge the synchrotron luminosity. In order to explain the luminosity of the non-thermal X-ray/optical emission from pulsars with low spin-down luminosity L {sub sd} ≲ 10{sup 34} erg s{sup −1}, non-dipole magnetic field components should be dominant at the emission region. For the γ -ray pulsars with L {sub sd} ≲ 10{sup 35} erg s{sup −1}, observed γ -ray to X-ray and optical flux ratios are much higher than the flux ratio between curvature and the synchrotron radiations. We discuss some possibilities such as the coexistence of multiple accelerators in the magnetosphere as suggested from the recent numerical simulation results. The obtained maximum luminosity would be useful to select observational targets in X-ray and optical bands.« less

Simultaneous parametric generation and up-conversion of entangled optical images

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

Saygin, M. Yu., E-mail: mihasyu@gmail.com; Chirkin, A. S., E-mail: aschirkin@rambler.r

A quantum theory of parametric amplification and frequency conversion of an optical image in coupled nonlinear optical processes that include one parametric amplification process at high-frequency pumping and two up-conversion processes in the same pump field is developed. The field momentum operator that takes into account the diffraction and group velocities of the waves is used to derive the quantum equations related to the spatial dynamics of the images during the interaction. An optical scheme for the amplification and conversion of a close image is considered. The mean photon number density and signal-to-noise ratio are calculated in the fixed-pump-field approximationmore » for images at various frequencies. It has been established that the signal-to-noise ratio decreases with increasing interaction length in the amplified image and increases in the images at the generated frequencies, tending to asymptotic values for all interacting waves. The variance of the difference of the numbers of photons is calculated for various pairs of frequencies. The quantum entanglement of the optical images formed in a high-frequency pump field is shown to be converted to higher frequencies during the generation of sum frequencies. Thus, two pairs of entangled optical images are produced in the process considered.« less

Overview of Multi-Kilowatt Free-Piston Stirling Power Conversion Research at Glenn Research Center

NASA Technical Reports Server (NTRS)

Geng, Steven M.; Mason, Lee S.; Dyson, Rodger W.; Penswick, L. Barry

2008-01-01

As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors and a pair of commercially available pressure wave generators (which will be plumbed together to create a high power Stirling linear alternator test rig) have been procured for in-house testing at Glenn Research Center (GRC). Delivery of both the Stirling convertors and the linear alternator test rig is expected by October 2007. The 1 kW class free-piston Stirling convertors will be tested at GRC to map and verify performance. The convertors will later be modified to operate with a NaK liquid metal pumped loop for thermal energy input. The high power linear alternator test rig will be used to map and verify high power Stirling linear alternator performance and to develop power management and distribution (PMAD) methods and techniques. This paper provides an overview of the multi-kilowatt free-piston Stirling power conversion work being performed at GRC.

Overview of Multi-kilowatt Free-Piston Stirling Power Conversion Research at GRC

NASA Technical Reports Server (NTRS)

Geng, Steven M.; Mason, Lee S.; Dyson, Rodger W.; Penswick, L. Barry

2008-01-01

As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors and a pair of commercially available pressure wave generators (which will be plumbed together to create a high power Stirling linear alternator test rig) have been procured for in-house testing at Glenn Research Center. Delivery of both the Stirling convertors and the linear alternator test rig is expected by October, 2007. The 1 kW class free-piston Stirling convertors will be tested at GRC to map and verify performance. The convertors will later be modified to operate with a NaK liquid metal pumped loop for thermal energy input. The high power linear alternator test rig will be used to map and verify high power Stirling linear alternator performance and to develop power management and distribution (PMAD) methods and techniques. This paper provides an overview of the multi-kilowatt free-piston Stirling power conversion work being performed at GRC.

Overview of Multi-Kilowatt Free-Piston Stirling Power Conversion Research at GRC

NASA Astrophysics Data System (ADS)

Geng, Steven M.; Mason, Lee S.; Dyson, Rodger W.; Penswick, L. Barry

2008-01-01

As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors and a pair of commercially available pressure wave generators (which will be plumbed together to create a high power Stirling linear alternator test rig) have been procured for in-house testing at Glenn Research Center. Delivery of both the Stirling convertors and the linear alternator test rig is expected by October, 2007. The 1 kW class free-piston Stirling convertors will be tested at GRC to map and verify performance. The convertors will later be modified to operate with a NaK liquid metal pumped loop for thermal energy input. The high power linear alternator test rig will be used to map and verify high power Stirling linear alternator performance and to develop power management and distribution (PMAD) methods and techniques. This paper provides an overview of the multi-kilowatt free-piston Stirling power conversion work being performed at GRC.

Tracking the coherent generation of polaron pairs in conjugated polymers

NASA Astrophysics Data System (ADS)

de Sio, Antonietta; Troiani, Filippo; Maiuri, Margherita; Réhault, Julien; Sommer, Ephraim; Lim, James; Huelga, Susana F.; Plenio, Martin B.; Rozzi, Carlo Andrea; Cerullo, Giulio; Molinari, Elisa; Lienau, Christoph

2016-12-01

The optical excitation of organic semiconductors not only generates charge-neutral electron-hole pairs (excitons), but also charge-separated polaron pairs with high yield. The microscopic mechanisms underlying this charge separation have been debated for many years. Here we use ultrafast two-dimensional electronic spectroscopy to study the dynamics of polaron pair formation in a prototypical polymer thin film on a sub-20-fs time scale. We observe multi-period peak oscillations persisting for up to about 1 ps as distinct signatures of vibronic quantum coherence at room temperature. The measured two-dimensional spectra show pronounced peak splittings revealing that the elementary optical excitations of this polymer are hybridized exciton-polaron-pairs, strongly coupled to a dominant underdamped vibrational mode. Coherent vibronic coupling induces ultrafast polaron pair formation, accelerates the charge separation dynamics and makes it insensitive to disorder. These findings open up new perspectives for tailoring light-to-current conversion in organic materials.

Electromagnetic cascades in pulsars

NASA Technical Reports Server (NTRS)

Daugherty, J. K.; Harding, A. K.

1981-01-01

The development of pair photon cascades initiated by high energy electrons above a pulsar polar cap is simulated numerically. The calculation uses the energy of the primary electron, the magnetic field strength, and the period of rotation as parameters and follows the curvature radiation emitted by the primary, the conversion of this radiation e(+) - e(-) pairs in the intense fields, and the quantized synchrotron radiation by the secondary pairs. A recursive technique allows the tracing of an indefinite number of generations using a Monte Carlo method. Gamma ray and pair spectra are calculated for cascades in different parts of the polar cap and with different acceleration models. It is found that synchrotron radiation from secondary pairs makes an important contribution to the gamma ray spectrum above 25 MeV, and that the final gamma ray and pair spectra are insensitive to the height of the accelerating region, as long as the acceleration of the primary electrons is not limited by radiation reaction.

Equivalences between nonuniform exponential dichotomy and admissibility

NASA Astrophysics Data System (ADS)

Zhou, Linfeng; Lu, Kening; Zhang, Weinian

2017-01-01

Relationship between exponential dichotomies and admissibility of function classes is a significant problem for hyperbolic dynamical systems. It was proved that a nonuniform exponential dichotomy implies several admissible pairs of function classes and conversely some admissible pairs were found to imply a nonuniform exponential dichotomy. In this paper we find an appropriate admissible pair of classes of Lyapunov bounded functions which is equivalent to the existence of nonuniform exponential dichotomy on half-lines R± separately, on both half-lines R± simultaneously, and on the whole line R. Additionally, the maximal admissibility is proved in the case on both half-lines R± simultaneously.

Novel insights into the mechanism of the ortho/para spin conversion of hydrogen pairs: implications for catalysis and interstellar water.

PubMed

Limbach, Hans-Heinrich; Buntkowsky, Gerd; Matthes, Jochen; Gründemann, Stefan; Pery, Tal; Walaszek, Bernadeta; Chaudret, Bruno

2006-03-13

The phenomenon of exchange coupling is taken into account in the description of the magnetic nuclear spin conversion between bound ortho- and para-dihydrogen. This conversion occurs without bond breaking, in contrast to the chemical spin conversion. It is shown that the exchange coupling needs to be reduced so that the corresponding exchange barrier can increase and the given magnetic interaction can effectively induce a spin conversion. The implications for related molecules such as water are discussed. For ice, a dipolar magnetic conversion and for liquid water a chemical conversion are predicted to occur within the millisecond timescale. It follows that a separation of water into its spin isomers, as proposed by Tikhonov and Volkov (Science 2002, 296, 2363), is not feasible. Nuclear spin temperatures of water vapor in comets, which are smaller than the gas-phase equilibrium temperatures, are proposed to be diagnostic for the temperature of the ice or the dust surface from which the water was released.

Conversion of amino-acid sequence in proteins to classical music: search for auditory patterns

PubMed Central

2007-01-01

We have converted genome-encoded protein sequences into musical notes to reveal auditory patterns without compromising musicality. We derived a reduced range of 13 base notes by pairing similar amino acids and distinguishing them using variations of three-note chords and codon distribution to dictate rhythm. The conversion will help make genomic coding sequences more approachable for the general public, young children, and vision-impaired scientists. PMID:17477882

Diffusion affected magnetic field effect in exciplex fluorescence

NASA Astrophysics Data System (ADS)

Burshtein, Anatoly I.; Ivanov, Anatoly I.

2014-07-01

The fluorescence of the exciplex, 1[D+δA-δ], formed at contact of photoexcited acceptor 1A* with an electron donor 1D, is known to be very sensitive to an external magnetic field, reducing the spin conversion efficiency in the resulting geminate radical ion pair, 1, 3[D+…A-]. The relative increase of the exciplex fluorescence in the highest magnetic field compared to the lowest one, known as the magnetic field effect, crucially depends on the viscosity of the solvent. This phenomenon first studied experimentally is at first reproduced here theoretically. The magnetic field effect is shown to vanish in both limits of high and low solvent diffusivity reaching a maximum in between. It is also very sensitive to the solvent dielectric constant and to the exciplex and radical-ion pair conversion rates.

Diffusion affected magnetic field effect in exciplex fluorescence.

PubMed

Burshtein, Anatoly I; Ivanov, Anatoly I

2014-07-14

The fluorescence of the exciplex, (1)[D(+δ)A(-δ)], formed at contact of photoexcited acceptor (1)A(*) with an electron donor (1)D, is known to be very sensitive to an external magnetic field, reducing the spin conversion efficiency in the resulting geminate radical ion pair, (1, 3)[D(+)…A(-)]. The relative increase of the exciplex fluorescence in the highest magnetic field compared to the lowest one, known as the magnetic field effect, crucially depends on the viscosity of the solvent. This phenomenon first studied experimentally is at first reproduced here theoretically. The magnetic field effect is shown to vanish in both limits of high and low solvent diffusivity reaching a maximum in between. It is also very sensitive to the solvent dielectric constant and to the exciplex and radical-ion pair conversion rates.

Dosimetry of high-energy electron linac produced photoneutrons and the bremsstrahlung gamma-rays using TLD-500 and TLD-700 dosimeter pairs

NASA Astrophysics Data System (ADS)

Mukherjee, Bhaskar; Makowski, Dariusz; Simrock, Stefan

2005-06-01

The neutron and gamma doses are crucial to interpreting the radiation effects in microelectronic devices operating in a high-energy accelerator environment. This report highlights a method for an accurate estimation of photoneutron and the accompanying bremsstrahlung (gamma) doses produced by a 450 MeV electron linear accelerator (linac) operating in pulsed mode. The principle is based on the analysis of thermoluminescence glow-curves of TLD-500 (Aluminium Oxide) and TLD-700 (Lithium Fluoride) dosimeter pairs. The gamma and fast neutron response of the TLD-500 and TLD-700 dosimeter pairs were calibrated with a 60Co (gamma) and a 241Am-Be (α, n) neutron standard-source, respectively. The Kinetic Energy Released in Materials (kerma) conversion factor for photoneutrons was evaluated by folding the neutron kerma (dose) distribution in 7LiF (the main component of the TLD-700 dosimeter) with the energy spectra of the 241Am-Be (α, n) neutrons and electron accelerator produced photoneutrons. The neutron kerma conversion factors for 241Am-Be neutrons and photoneutrons were calculated to be 2.52×10 -3 and 1.37×10 -3 μGy/a.u. respectively. The bremsstrahlung (gamma) dose conversion factor was evaluated to be 7.32×10 -4 μGy/a.u. The above method has been successfully utilised to assess the photoneutron and bremsstrahlung doses from a 450 MeV electron linac operating at DESY Research Centre in Hamburg, Germany.

Thirty-year results from a paired-catchment study of upland flowpath responses to forest cover conversion in northern Minnesota

Treesearch

Stephen Sebestyen; Randy Kolka

2016-01-01

Long-term studies on paired-research catchments have often showed periods of changes to water yields and peak stormflow after forest harvesting. Most studies have focused on wholecatchment or downstream responses. In contrast, few studies have ever been established to measure and investigate specific pathways of water routing through catchment soils or how sub-...

Alpha voltaic batteries and methods thereof

NASA Technical Reports Server (NTRS)

Jenkins, Phillip (Inventor); Scheiman, David (Inventor); Castro, Stephanie (Inventor); Raffaelle, Ryne P. (Inventor); Wilt, David (Inventor); Chubb, Donald (Inventor)

2011-01-01

An alpha voltaic battery includes at least one layer of a semiconductor material comprising at least one p/n junction, at least one absorption and conversion layer on the at least one layer of semiconductor layer, and at least one alpha particle emitter. The absorption and conversion layer prevents at least a portion of alpha particles from the alpha particle emitter from damaging the p/n junction in the layer of semiconductor material. The absorption and conversion layer also converts at least a portion of energy from the alpha particles into electron-hole pairs for collection by the one p/n junction in the layer of semiconductor material.

Quantum teleportation in the spin-orbit variables of photon pairs

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

Khoury, A. Z.; Milman, P.; Laboratoire Materiaux et Phenomenes Quantiques, CNRS UMR 7162, Universite Paris Diderot, F-75013, Paris

2011-06-15

We propose a polarization to orbital angular momentum teleportation scheme using entangled photon pairs generated by spontaneous parametric down-conversion. By making a joint detection of the polarization and angular momentum parity of a single photon, we are able to detect all the Bell states and perform, in principle, perfect teleportation from a discrete to a continuous system using minimal resources. The proposed protocol implementation demands experimental resources that are currently available in quantum optics laboratories.

Franson Interference Generated by a Two-Level System

NASA Astrophysics Data System (ADS)

Peiris, M.; Konthasinghe, K.; Muller, A.

2017-01-01

We report a Franson interferometry experiment based on correlated photon pairs generated via frequency-filtered scattered light from a near-resonantly driven two-level semiconductor quantum dot. In contrast to spontaneous parametric down-conversion and four-wave mixing, this approach can produce single pairs of correlated photons. We have measured a Franson visibility as high as 66%, which goes beyond the classical limit of 50% and approaches the limit of violation of Bell's inequalities (70.7%).

IR studies of the impact of Ge doping on the successive conversion of VOn defects in Czochralski-Si containing carbon

NASA Astrophysics Data System (ADS)

Londos, C. A.; Andrianakis, A.; Sgourou, E. N.; Emtsev, V. V.; Ohyama, H.

2011-02-01

We report infrared absorption studies of oxygen-related defects in electron-irradiated Ge-doped Czochralski-Si. Our investigation was mainly focused on the reaction channel leading to the formation of VOn (1≤n≤6) defects. The VOn defects form mainly upon annealing, as a result of the successive aggregation of oxygen atoms in the initial VO defect produced by the irradiation: (VO+Oi→VO2+Oi→VO3+Oi→VO4,…). It was found that the ratio of the conversion of VOn to VOn+1 defects is sensitive to the Ge content of the material. In particular, the ratio of the conversion of the VO to the VO2 defects was found to decrease with the increase in Ge concentration of the samples, although the opposite trend was observed for the VO3 to VO4 conversion. However, the VO2 to VO3 conversion changes only slightly with Ge content, being practically unaffected for Ge concentrations up to 2×1020 cm-3. In the case of VO2 formation, the phenomenon was attributed to the elastic strains induced in the lattice due to the Ge presence which affects the balance between the reactions VO+Oi→VO2, VO+SiI→Oi, mainly involved in the decay of the VO and the growth of the VO2 defects. In the case of VO4 formation, the phenomenon was discussed by taking into account the enhancement of the diffusivity of the Oi atoms in the Ge-doped Si, which could lead to an enhancement of the rate of the reaction VO3+Oi→VO4. For the VO3 formation this effect is practically negligible due to the fact that at the temperatures of VO2 to VO3 conversion oxygen diffusivity is quite small. The exhibited behavior in the conversion of the VOn to VOn+1 defects (n=1,2,3) was similar in Ge-doped samples with low carbon content ([Cs]<2×1016 cm-3) and in Ge-doped samples with high carbon content ([Cs]≥1×1017 cm-3). The impact of C as well as its role in the conversion efficiency of VO to VO2 was studied by comparing the spectra in low carbon and high carbon Ge free Si material. Furthermore, a pair of bands at (1037,1051 cm-1) was attributed to the VO5 defect. The origin of another pair of bands (967,1005 cm-1) was discussed and tentatively correlated with a VOnCs structure. The role of Ge and C in the formation of the latter two pairs of bands was discussed.

Japanese mothers’ utterances about agents and actions during joint picture-book reading

PubMed Central

Murase, Toshiki

2013-01-01

This study extended the research on the scaffolding provided by mothers while reading picture books with their children from a focus on conversational styles related to labeling to a focus on those related to agents and actions to clarify the process by which language develops from the one-word to the syntactic stage. We clarified whether mothers decreased the degree of scaffolding in their initiation of conversations, in the responses to their children’s utterances, and in the choice of referential ranges of their utterances. We also investigated whether maternal conversational styles contributed to the development of their children’s vocabularies. Eighteen pairs of Japanese mothers and their children were longitudinally observed when the children were 20 and 27 months of age. The pairs were given a picture book depicting 24 animals engaged in everyday behavior. The mothers shifted their approach in the initiation of conversation from providing to requesting information as a function of their children’s age. The proportion of maternal elaborative information-seeking responses was positively correlated with the size of their children’s productive vocabulary. In terms of referential choices, mothers broadened the range of their references as their children aged. In terms of the contribution of maternal conversational styles to children’s vocabulary development, the use of a maternal elaborative information-seeking style when the children were 20 months of age predicted the size of the children’s productive vocabulary at 27 months. These results indicate that mothers decrease the degree of scaffolding by introducing more complex information into the conversations and transferring the role of actively producing information to their children by requesting information as their children develop. The results also indicate that these conversational styles promote the development of children’s vocabularies during the transition from the one-word to the syntactic stage. PMID:24847288

Coevolution of Siglec-11 and Siglec-16 via gene conversion in primates.

PubMed

Hayakawa, Toshiyuki; Khedri, Zahra; Schwarz, Flavio; Landig, Corinna; Liang, Suh-Yuen; Yu, Hai; Chen, Xi; Fujito, Naoko T; Satta, Yoko; Varki, Ajit; Angata, Takashi

2017-11-23

Siglecs-11 and -16 are members of the sialic acid recognizing Ig-like lectin family, and expressed in same cells. Siglec-11 functions as an inhibitory receptor, whereas Siglec-16 exhibits activating properties. In humans, SIGLEC11 and SIGLEC16 gene sequences are extremely similar in the region encoding the extracellular domain due to gene conversions. Human SIGLEC11 was converted by the nonfunctional SIGLEC16P allele, and the converted SIGLEC11 allele became fixed in humans, possibly because it provides novel neuroprotective functions in brain microglia. However, the detailed evolutionary history of SIGLEC11 and SIGLEC16 in other primates remains unclear. We analyzed SIGLEC11 and SIGLEC16 gene sequences of multiple primate species, and examined glycan binding profiles of these Siglecs. The phylogenetic tree demonstrated that gene conversions between SIGLEC11 and SIGLEC16 occurred in the region including the exon encoding the sialic acid binding domain in every primate examined. Functional assays showed that glycan binding preference is similar between Siglec-11 and Siglec-16 in all analyzed hominid species. Taken together with the fact that Siglec-11 and Siglec-16 are expressed in the same cells, Siglec-11 and Siglec-16 are regarded as paired receptors that have maintained similar ligand binding preferences via gene conversions. Relaxed functional constraints were detected on the SIGLEC11 and SIGLEC16 exons that underwent gene conversions, possibly contributing to the evolutionary acceptance of repeated gene conversions. The frequency of nonfunctional SIGLEC16P alleles is much higher than that of SIGLEC16 alleles in every human population. Our findings indicate that Siglec-11 and Siglec-16 have been maintained as paired receptors by repeated gene conversions under relaxed functional constraints in the primate lineage. The high prevalence of the nonfunctional SIGLEC16P allele and the fixation of the converted SIGLEC11 imply that the loss of Siglec-16 and the gain of Siglec-11 in microglia might have been favored during the evolution of human lineage.

Another look at retroactive and proactive interference: a quantitative analysis of conversion processes.

PubMed

Blank, Hartmut

2005-02-01

Traditionally, the causes of interference phenomena were sought in "real" or "hard" memory processes such as unlearning, response competition, or inhibition, which serve to reduce the accessibility of target items. I propose an alternative approach which does not deny the influence of such processes but highlights a second, equally important, source of interference-the conversion (Tulving, 1983) of accessible memory information into memory performance. Conversion is conceived as a problem-solving-like activity in which the rememberer tries to find solutions to a memory task. Conversion-based interference effects are traced to different conversion processes in the experimental and control conditions of interference designs. I present a simple theoretical model that quantitatively predicts the resulting amount of interference. In two paired-associate learning experiments using two different types of memory tests, these predictions were corroborated. Relations of the present approach to traditional accounts of interference phenomena and implications for eyewitness testimony are discussed.

Spectroscopy of Isolated Prebiotic Nucleobases

NASA Technical Reports Server (NTRS)

Svadlenak, Nathan; Callahan, Michael P.; Ligare, Marshall; Gulian, Lisa; Gengeliczki, Zsolt; Nachtigallova, Dana; Hobza, Pavel; deVries, Mattanjah

2011-01-01

We use multiphoton ionization and double resonance spectroscopy to study the excited state dynamics of biologically relevant molecules as well as prebiotic nucleobases, isolated in the gas phase. Molecules that are biologically relevant to life today tend to exhibit short excited state lifetimes compared to similar but non-biologically relevant analogs. The mechanism is internal conversion, which may help protect the biologically active molecules from UV damage. This process is governed by conical intersections that depend very strongly on molecular structure. Therefore we have studied purines and pyrimidines with systematic variations of structure, including substitutions, tautomeric forms, and cluster structures that represent different base pair binding motifs. These structural variations also include possible alternate base pairs that may shed light on prebiotic chemistry. With this in mind we have begun to probe the ultrafast dynamics of molecules that exhibit very short excited states and search for evidence of internal conversions.

Highly efficient heralded single-photon source for telecom wavelengths based on a PPLN waveguide.

PubMed

Bock, Matthias; Lenhard, Andreas; Chunnilall, Christopher; Becher, Christoph

2016-10-17

We present the realization of a highly efficient photon pair source based on spontaneous parametric downconversion (SPDC) in a periodically poled lithium niobate (PPLN) ridge waveguide. The source is suitable for long distance quantum communication applications as the photon pairs are located at the centers of the telecommunication O- and C- band at 1312 nm and 1557 nm. The high efficiency is confirmed by a conversion efficiency of 4 × 10^-6 - which is to our knowledge among the highest conversion efficiencies reported so far - and a heralding efficiency of 64.1 ± 2.1%. The heralded single-photon properties are confirmed by the measurement of the photon statistics with a Click/No-Click method as well as the heralded g⁽²⁾-function. A minimum value for g⁽²⁾(0) of 0.001 ± 0.0003 indicating clear antibunching has been observed.

Temporal Multimode Storage of Entangled Photon Pairs

NASA Astrophysics Data System (ADS)

Tiranov, Alexey; Strassmann, Peter C.; Lavoie, Jonathan; Brunner, Nicolas; Huber, Marcus; Verma, Varun B.; Nam, Sae Woo; Mirin, Richard P.; Lita, Adriana E.; Marsili, Francesco; Afzelius, Mikael; Bussières, Félix; Gisin, Nicolas

2016-12-01

Multiplexed quantum memories capable of storing and processing entangled photons are essential for the development of quantum networks. In this context, we demonstrate and certify the simultaneous storage and retrieval of two entangled photons inside a solid-state quantum memory and measure a temporal multimode capacity of ten modes. This is achieved by producing two polarization-entangled pairs from parametric down-conversion and mapping one photon of each pair onto a rare-earth-ion-doped (REID) crystal using the atomic frequency comb (AFC) protocol. We develop a concept of indirect entanglement witnesses, which can be used as Schmidt number witnesses, and we use it to experimentally certify the presence of more than one entangled pair retrieved from the quantum memory. Our work puts forward REID-AFC as a platform compatible with temporal multiplexing of several entangled photon pairs along with a new entanglement certification method, useful for the characterization of multiplexed quantum memories.

High-Efficiency Solar Cells Using Photonic-Bandgap Materials

NASA Technical Reports Server (NTRS)

Dowling, Jonathan; Lee, Hwang

2005-01-01

Solar photovoltaic cells would be designed to exploit photonic-bandgap (PBG) materials to enhance their energy-conversion efficiencies, according to a proposal. Whereas the energy-conversion efficiencies of currently available solar cells are typically less than 30 percent, it has been estimated that the energy-conversion efficiencies of the proposed cells could be about 50 percent or possibly even greater. The primary source of inefficiency of a currently available solar cell is the mismatch between the narrow wavelength band associated with the semiconductor energy gap (the bandgap) and the broad wavelength band of solar radiation. This mismatch results in loss of power from both (1) long-wavelength photons, defined here as photons that do not have enough energy to excite electron-hole pairs across the bandgap, and (2) short-wavelength photons, defined here as photons that excite electron- hole pairs with energies much above the bandgap. It follows that a large increase in efficiency could be obtained if a large portion of the incident solar energy could be funneled into a narrow wavelength band corresponding to the bandgap. In the proposed approach, such funneling would be effected by use of PBG materials as intermediaries between the Sun and photovoltaic cells.

Isolated and soft-switched power converter

DOEpatents

Peng, Fang Zheng; Adams, Donald Joe

2002-01-01

An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.

The entangled triplet pair state in acene and heteroacene materials

PubMed Central

Yong, Chaw Keong; Musser, Andrew J.; Bayliss, Sam L.; Lukman, Steven; Tamura, Hiroyuki; Bubnova, Olga; Hallani, Rawad K.; Meneau, Aurélie; Resel, Roland; Maruyama, Munetaka; Hotta, Shu; Herz, Laura M.; Beljonne, David; Anthony, John E.; Clark, Jenny; Sirringhaus, Henning

2017-01-01

Entanglement of states is one of the most surprising and counter-intuitive consequences of quantum mechanics, with potent applications in cryptography and computing. In organic materials, one particularly significant manifestation is the spin-entangled triplet-pair state, which mediates the spin-conserving fission of one spin-0 singlet exciton into two spin-1 triplet excitons. Despite long theoretical and experimental exploration, the nature of the triplet-pair state and inter-triplet interactions have proved elusive. Here we use a range of organic semiconductors that undergo singlet exciton fission to reveal the photophysical properties of entangled triplet-pair states. We find that the triplet pair is bound with respect to free triplets with an energy that is largely material independent (∼30 meV). During its lifetime, the component triplets behave cooperatively as a singlet and emit light through a Herzberg–Teller-type mechanism, resulting in vibronically structured photoluminescence. In photovoltaic blends, charge transfer can occur from the bound triplet pairs with >100% photon-to-charge conversion efficiency. PMID:28699637

The entangled triplet pair state in acene and heteroacene materials

NASA Astrophysics Data System (ADS)

Yong, Chaw Keong; Musser, Andrew J.; Bayliss, Sam L.; Lukman, Steven; Tamura, Hiroyuki; Bubnova, Olga; Hallani, Rawad K.; Meneau, Aurélie; Resel, Roland; Maruyama, Munetaka; Hotta, Shu; Herz, Laura M.; Beljonne, David; Anthony, John E.; Clark, Jenny; Sirringhaus, Henning

2017-07-01

Entanglement of states is one of the most surprising and counter-intuitive consequences of quantum mechanics, with potent applications in cryptography and computing. In organic materials, one particularly significant manifestation is the spin-entangled triplet-pair state, which mediates the spin-conserving fission of one spin-0 singlet exciton into two spin-1 triplet excitons. Despite long theoretical and experimental exploration, the nature of the triplet-pair state and inter-triplet interactions have proved elusive. Here we use a range of organic semiconductors that undergo singlet exciton fission to reveal the photophysical properties of entangled triplet-pair states. We find that the triplet pair is bound with respect to free triplets with an energy that is largely material independent (~30 meV). During its lifetime, the component triplets behave cooperatively as a singlet and emit light through a Herzberg-Teller-type mechanism, resulting in vibronically structured photoluminescence. In photovoltaic blends, charge transfer can occur from the bound triplet pairs with >100% photon-to-charge conversion efficiency.

General Conversion for Obtaining Strongly Existentially Unforgeable Signatures

NASA Astrophysics Data System (ADS)

Teranishi, Isamu; Oyama, Takuro; Ogata, Wakaha

We say that a signature scheme is strongly existentially unforgeable (SEU) if no adversary, given message/signature pairs adaptively, can generate a signature on a new message or a new signature on a previously signed message. We propose a general and efficient conversion in the standard model that transforms a secure signature scheme to SEU signature scheme. In order to construct that conversion, we use a chameleon commitment scheme. Here a chameleon commitment scheme is a variant of commitment scheme such that one can change the committed value after publishing the commitment if one knows the secret key. We define the chosen message security notion for the chameleon commitment scheme, and show that the signature scheme transformed by our proposed conversion satisfies the SEU property if the chameleon commitment scheme is chosen message secure. By modifying the proposed conversion, we also give a general and efficient conversion in the random oracle model, that transforms a secure signature scheme into a SEU signature scheme. This second conversion also uses a chameleon commitment scheme but only requires the key only attack security for it.

Two-photon geometrical phase

NASA Astrophysics Data System (ADS)

Strekalov, D. V.; Shih, Y. H.

1997-10-01

An advanced wave model is applied to a two-photon interference experiment to show that the observed interference effect is due to the geometrical phase of a two-photon state produced in spontaneous parametric down-conversion. The polarization state of the signal-idler pair is changed adiabatically so that the ``loop'' on the Poincaré sphere is opened in the signal channel and closed in the idler channel. Therefore, we observed an essentially nonlocal geometrical phase, shared by the entangled photon pair, or a biphoton.

Three-photon N00N states generated by photon subtraction from double photon pairs.

PubMed

Kim, Heonoh; Park, Hee Su; Choi, Sang-Kyung

2009-10-26

We describe an experimental demonstration of a novel three-photon N00N state generation scheme using a single source of photons based on spontaneous parametric down-conversion (SPDC). The three-photon entangled state is generated when a photon is subtracted from a double pair of photons and detected by a heralding counter. Interference fringes measured with an emulated three-photon detector reveal the three-photon de Broglie wavelength and exhibit visibility > 70% without background subtraction.

Generation of High Purity Photon-Pair in a Short Highly Non-Linear Fiber

DTIC Science & Technology

2013-01-01

Avalanche photodiode. A 10 m long HNLF fabricated by Sumitomo with a core diameter of 4 microns is fusion spliced to a single mode fiber for a...parametric down conversion (SPDC) was first observed in χ(2) nonlinear crystal [3]. However, the compatibility of a nonlinear crystal source with fiber and...PAIR IN A SHORT HIGHLY NON-LINEAR FIBER 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA8750-12-1-0136 5c. PROGRAM ELEMENT NUMBER N/A 6. AUTHOR(S

Support effects in catalysis studied by in-situ sum frequency generation vibrational spectroscopy and in-situ x-ray spectroscopies

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

Kennedy, Griffin John

Here, kinetic measurements are paired with in-situ spectroscopic characterization tools to investigate colloidally based, supported Pt catalytic model systems in order to elucidate the mechanisms by which metal and support work in tandem to dictate activity and selectivity. The results demonstrate oxide support materials, while inactive in absence of Pt nanoparticles, possess unique active sites for the selective conversion of gas phase molecules when paired with an active metal catalyst.

Methods for natural gas and heavy hydrocarbon co-conversion

DOEpatents

Kong, Peter C [Idaho Falls, ID; Nelson, Lee O [Idaho Falls, ID; Detering, Brent A [Idaho Falls, ID

2009-02-24

A reactor for reactive co-conversion of heavy hydrocarbons and hydrocarbon gases and includes a dielectric barrier discharge plasma cell having a pair of electrodes separated by a dielectric material and passageway therebetween. An inlet is provided for feeding heavy hydrocarbons and other reactive materials to the passageway of the discharge plasma cell, and an outlet is provided for discharging reaction products from the reactor. A packed bed catalyst may optionally be used in the reactor to increase efficiency of conversion. The reactor can be modified to allow use of a variety of light sources for providing ultraviolet light within the discharge plasma cell. Methods for upgrading heavy hydrocarbons are also disclosed.

Nonthermal plasma systems and methods for natural gas and heavy hydrocarbon co-conversion

DOEpatents

Kong, Peter C.; Nelson, Lee O.; Detering, Brent A.

2005-05-24

A reactor for reactive co-conversion of heavy hydrocarbons and hydrocarbon gases and includes a dielectric barrier discharge plasma cell having a pair of electrodes separated by a dielectric material and passageway therebetween. An inlet is provided for feeding heavy hydrocarbons and other reactive materials to the passageway of the discharge plasma cell, and an outlet is provided for discharging reaction products from the reactor. A packed bed catalyst may optionally be used in the reactor to increase efficiency of conversion. The reactor can be modified to allow use of a variety of light sources for providing ultraviolet light within the discharge plasma cell. Methods for upgrading heavy hydrocarbons are also disclosed.

A linear polarization converter with near unity efficiency in microwave regime

NASA Astrophysics Data System (ADS)

Xu, Peng; Wang, Shen-Yun; Geyi, Wen

2017-04-01

In this paper, we present a linear polarization converter in the reflective mode with near unity conversion efficiency. The converter is designed in an array form on the basis of a pair of orthogonally arranged three-dimensional split-loop resonators sharing a common terminal coaxial port and a continuous metallic ground slab. It converts the linearly polarized incident electromagnetic wave at resonance to its orthogonal counterpart upon the reflection mode. The conversion mechanism is explained by an equivalent circuit model, and the conversion efficiency can be tuned by changing the impedance of the terminal port. Such a scheme of the linear polarization converter has potential applications in microwave communications, remote sensing, and imaging.

An inverse problem for Gibbs fields with hard core potential

NASA Astrophysics Data System (ADS)

Koralov, Leonid

2007-05-01

It is well known that for a regular stable potential of pair interaction and a small value of activity one can define the corresponding Gibbs field (a measure on the space of configurations of points in Rd). In this paper we consider a converse problem. Namely, we show that for a sufficiently small constant ρ¯1 and a sufficiently small function ρ¯2(x), x ∈Rd, that is equal to zero in a neighborhood of the origin, there exist a hard core pair potential and a value of activity such that ρ¯1 is the density and ρ¯2 is the pair correlation function of the corresponding Gibbs field.

Unity-Efficiency Parametric Down-Conversion via Amplitude Amplification.

PubMed

Niu, Murphy Yuezhen; Sanders, Barry C; Wong, Franco N C; Shapiro, Jeffrey H

2017-03-24

We propose an optical scheme, employing optical parametric down-converters interlaced with nonlinear sign gates (NSGs), that completely converts an n-photon Fock-state pump to n signal-idler photon pairs when the down-converters' crystal lengths are chosen appropriately. The proof of this assertion relies on amplitude amplification, analogous to that employed in Grover search, applied to the full quantum dynamics of single-mode parametric down-conversion. When we require that all Grover iterations use the same crystal, and account for potential experimental limitations on crystal-length precision, our optimized conversion efficiencies reach unity for 1≤n≤5, after which they decrease monotonically for n values up to 50, which is the upper limit of our numerical dynamics evaluations. Nevertheless, our conversion efficiencies remain higher than those for a conventional (no NSGs) down-converter.

Effect of hang cleans or squats paired with countermovement vertical jumps on vertical displacement.

PubMed

Andrews, Tedi R; Mackey, Theresa; Inkrott, Thomas A; Murray, Steven R; Clark, Ida E; Pettitt, Robert W

2011-09-01

Complex training is characterized by pairing resistance exercise with plyometric exercise to exploit the postactivation potentiation (PAP) phenomenon, thereby promising a better training effect. Studies on PAP as measured by human power performances are equivocal. One issue may be the lack of analyses across multiple sets of paired exercises, a common practice used by athletes. We evaluated countermovement vertical jump (CMJ) performance in 19 women, collegiate athletes in 3 of the following trials: (a) CMJs-only, where 1 set of CMJs served as a conditioning exercise, (b) heavy-load, back squats paired with CMJs, and (c) hang cleans paired with CMJs. The CMJ vertical displacement (3-attempt average), as measured with digital video, served as the dependent variable of CMJ performance. Across 3 sets of paired-exercise regimens, CMJ-only depreciated 1.6 cm and CMJ paired with back squats depreciated 2.0 cm (main effect, p < 0.05). Conversely, CMJ paired with hang cleans depreciated 0.30 cm (interaction, p < 0.05). Thus, the best complex training scheme was achieved by pairing CMJs with hang cleans in comparison to back squats or CMJs in and of themselves. Future research on exercise modes of complex training that best help athletes preserve and train with the highest power possible, in a given training session, is warranted.

Nonreciprocal Single Photon Frequency Conversion via Chiral Coupling between a V-Type System and a Pair of Waveguides

NASA Astrophysics Data System (ADS)

Shi, Ce; Cheng, Mu-Tian; Ma, Xiao-San; Wang, Dong; Huang, Xianshan; Wang, Bing; Zhang, Jia-Yan

2018-05-01

Not Available Supported by the Anhui Provincial Natural Science Foundation under Grant No 1608085MA09, and the National Natural Science Foundation of China under Grant Nos 11774262, 61675006, 11474003 and 61472282.

Tritium-field betacells

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

Walko, R.J.; Lincoln, R.C.; Baca, W.E.

1991-01-01

Betavoltaic power sources operate by converting the nuclear decay energy of beta-emitting radioisotopes into electricity. Since they are not chemically driven, they could operate at temperatures which would either be to hot or too cold for typical chemical batteries. Further, for long lived isotopes, they offer the possibility of multi-decade active lifetimes. Two approaches are being investigated: direct and indirect conversion. Direct conversion cells consist of semiconductor diodes similar to photovoltaic cells. Beta particle directly bombard these cells, generating electron-hole pairs in the semiconductor which are converted to useful power. Many using low power flux beta emitters, wide bandgap semiconductorsmore » are required to achieve useful conversion efficiencies. The combination of tritium, as the beta emitter, and gallium phosphide (GaP), as the semiconductor converter, was evaluated. Indirect conversion betacells first convert the beta energy to light with a phosphor, and then to electricity with photovoltaic cells. An indirect conversion power source using a tritium radioluminescent (RL) light is being investigated. Our analysis indicates that this approach has the potential for significant volume and cost savings over the direct conversion method. 7 refs., 11 figs.« less

Tritium-field betacells

NASA Astrophysics Data System (ADS)

Walko, R. J.; Lincoln, R. C.; Baca, W. E.; Goods, S. H.; Negley, G. H.

Betavoltaic power sources operate by converting the nuclear decay energy of beta-emitting radioisotopes into electricity. Since they are not chemically driven, they could operate at temperatures which would either be too hot or too cold for typical chemical batteries. Further, for long lived isotopes, they offer the possibility of multi-decade active lifetimes. Two approaches are being investigated: direct and indirect conversion. Direct conversion cells consist of semiconductor diodes similar to photovoltaic cells. Beta particle directly bombard these cells, generating electron-hole pairs in the semiconductor which are converted to useful power. When using low power flux beta emitters, wide bandgap semiconductors are required to achieve useful conversion efficiencies. The combination of tritium, as the beta emitter, and gallium phosphide (GaP), as the semiconductor converter, was evaluated. Indirect conversion betacells first convert the beta energy to light with a phosphor, and then to electricity with photovoltaic cells. An indirect conversion power source using a tritium radioluminescent (RL) light is being investigated. Our analysis indicates that this approach has the potential for significant volume and cost savings over the direct conversion method.

Semi-automatic engineering and tailoring of high-efficiency Bragg-reflection waveguide samples for quantum photonic applications

NASA Astrophysics Data System (ADS)

Pressl, B.; Laiho, K.; Chen, H.; Günthner, T.; Schlager, A.; Auchter, S.; Suchomel, H.; Kamp, M.; Höfling, S.; Schneider, C.; Weihs, G.

2018-04-01

Semiconductor alloys of aluminum gallium arsenide (AlGaAs) exhibit strong second-order optical nonlinearities. This makes them prime candidates for the integration of devices for classical nonlinear optical frequency conversion or photon-pair production, for example, through the parametric down-conversion (PDC) process. Within this material system, Bragg-reflection waveguides (BRW) are a promising platform, but the specifics of the fabrication process and the peculiar optical properties of the alloys require careful engineering. Previously, BRW samples have been mostly derived analytically from design equations using a fixed set of aluminum concentrations. This approach limits the variety and flexibility of the device design. Here, we present a comprehensive guide to the design and analysis of advanced BRW samples and show how to automatize these tasks. Then, nonlinear optimization techniques are employed to tailor the BRW epitaxial structure towards a specific design goal. As a demonstration of our approach, we search for the optimal effective nonlinearity and mode overlap which indicate an improved conversion efficiency or PDC pair production rate. However, the methodology itself is much more versatile as any parameter related to the optical properties of the waveguide, for example the phasematching wavelength or modal dispersion, may be incorporated as design goals. Further, we use the developed tools to gain a reliable insight in the fabrication tolerances and challenges of real-world sample imperfections. One such example is the common thickness gradient along the wafer, which strongly influences the photon-pair rate and spectral properties of the PDC process. Detailed models and a better understanding of the optical properties of a realistic BRW structure are not only useful for investigating current samples, but also provide important feedback for the design and fabrication of potential future turn-key devices.

biobambam: tools for read pair collation based algorithms on BAM files

PubMed Central

2014-01-01

Background Sequence alignment data is often ordered by coordinate (id of the reference sequence plus position on the sequence where the fragment was mapped) when stored in BAM files, as this simplifies the extraction of variants between the mapped data and the reference or of variants within the mapped data. In this order paired reads are usually separated in the file, which complicates some other applications like duplicate marking or conversion to the FastQ format which require to access the full information of the pairs. Results In this paper we introduce biobambam, a set of tools based on the efficient collation of alignments in BAM files by read name. The employed collation algorithm avoids time and space consuming sorting of alignments by read name where this is possible without using more than a specified amount of main memory. Using this algorithm tasks like duplicate marking in BAM files and conversion of BAM files to the FastQ format can be performed very efficiently with limited resources. We also make the collation algorithm available in the form of an API for other projects. This API is part of the libmaus package. Conclusions In comparison with previous approaches to problems involving the collation of alignments by read name like the BAM to FastQ or duplication marking utilities our approach can often perform an equivalent task more efficiently in terms of the required main memory and run-time. Our BAM to FastQ conversion is faster than all widely known alternatives including Picard and bamUtil. Our duplicate marking is about as fast as the closest competitor bamUtil for small data sets and faster than all known alternatives on large and complex data sets.

Defect engineering of the oxygen-vacancy clusters formation in electron irradiated silicon by isovalent doping: An infrared perspective

NASA Astrophysics Data System (ADS)

Londos, C. A.; Sgourou, E. N.; Chroneos, A.

2012-12-01

Infrared spectroscopy was used to study the production and evolution of oxygen-vacancy (VOn for n = 1, 2, 3 and VmO for m = 1, 2, 3) clusters, in electron-irradiated Czochralski silicon (Cz-Si) samples, doped with isovalent dopants. It was determined that the production of the VO pair is enhanced in Ge-doped Si but is suppressed in Sn and Pb-doped Si. The phenomenon is discussed in terms of the competition between isovalent dopants and oxygen atoms in capturing vacancies in the course of irradiation. In the case of Ge, only transient GeV pairs form, leading finally to an increase of the VO production. Conversely, for Sn and Pb the corresponding pairs with vacancies are stable, having an opposite impact on the formation of VO pairs. Regarding V2O and V3O clusters, our measurements indicate that Ge doping enhances their formation, although Sn and Pb dopants suppress it. Similar arguments as those for the VO pair could be put forward, based on the effect of isovalent impurities on the availability of vacancies. Additionally, it was found that the conversion ratio of VO to VO2 decreases as the covalent radius of the isovalent dopant increases. These results are discussed in terms of the local strains introduced by the isovalent dopants in the Si lattice. These local strains affect the balance of the intrinsic defects created as a result of irradiation, as well as the balance between the two main reactions (VO + Oi → VO2 and VO + SiI → Oi) participating in the VO annealing, leading finally to a decrease of the VO2 production. The larger the covalent radius of the isovalent dopant (rGe < rSn < rPb), the larger the introduced strains in the lattice and then the less the VO2 formation in accordance with our experimental results. Interestingly, an opposite trend was observed for the conversion ratio of VO2 to VO3. The phenomenon is attributed to the enhanced diffusivity of oxygen impurity as a result of the presence of isovalent dopants, leading to an enhanced formation of the VO3 cluster. The results indicate that isovalent doping of Si is an effective way to control the formation of the deleterious oxygen-vacancy clustering that can affect Si-based devices.

Time-bin entangled photon pairs from spontaneous parametric down-conversion pumped by a cw multi-mode diode laser.

PubMed

Kwon, Osung; Park, Kwang-Kyoon; Ra, Young-Sik; Kim, Yong-Su; Kim, Yoon-Ho

2013-10-21

Generation of time-bin entangled photon pairs requires the use of the Franson interferometer which consists of two spatially separated unbalanced Mach-Zehnder interferometers through which the signal and idler photons from spontaneous parametric down-conversion (SPDC) are made to transmit individually. There have been two SPDC pumping regimes where the scheme works: the narrowband regime and the double-pulse regime. In the narrowband regime, the SPDC process is pumped by a narrowband cw laser with the coherence length much longer than the path length difference of the Franson interferometer. In the double-pulse regime, the longitudinal separation between the pulse pair is made equal to the path length difference of the Franson interferometer. In this paper, we propose another regime by which the generation of time-bin entanglement is possible and demonstrate the scheme experimentally. In our scheme, differently from the previous approaches, the SPDC process is pumped by a cw multi-mode (i.e., short coherence length) laser and makes use of the coherence revival property of such a laser. The high-visibility two-photon Franson interference demonstrates clearly that high-quality time-bin entanglement source can be developed using inexpensive cw multi-mode diode lasers for various quantum communication applications.

Bi-stable frequency up-conversion piezoelectric energy harvester driven by non-contact magnetic repulsion

NASA Astrophysics Data System (ADS)

Tang, Q. C.; Yang, Y. L.; Li, Xinxin

2011-12-01

This paper presents miniaturized energy harvesters, where the frequency up-conversion technique is used to improve the bandwidth of vibration energy harvesters. The proposed and developed miniature piezoelectric energy harvester utilizes magnetic repulsion forces to achieve non-contact frequency up-conversion, thereby avoiding mechanical collision and wear for long-term working durability. A pair of piezoelectric resonant cantilevers is micro-fabricated to generate electric power. A simplified model involving linear oscillators and magnetic interaction is deployed to demonstrate the feasibility of the device design. A bench-top harvester has been fabricated and characterized, resulting in average power generation of over 10 µW within a broad frequency range of 10-22 Hz under 1g acceleration.

Joint temporal density measurements for two-photon state characterization.

PubMed

Kuzucu, Onur; Wong, Franco N C; Kurimura, Sunao; Tovstonog, Sergey

2008-10-10

We demonstrate a technique for characterizing two-photon quantum states based on joint temporal correlation measurements using time-resolved single-photon detection by femtosecond up-conversion. We measure for the first time the joint temporal density of a two-photon entangled state, showing clearly the time anticorrelation of the coincident-frequency entangled photon pair generated by ultrafast spontaneous parametric down-conversion under extended phase-matching conditions. The new technique enables us to manipulate the frequency entanglement by varying the down-conversion pump bandwidth to produce a nearly unentangled two-photon state that is expected to yield a heralded single-photon state with a purity of 0.88. The time-domain correlation technique complements existing frequency-domain measurement methods for a more complete characterization of photonic entanglement.

Hydrogen adsorption on two catalysts for the ortho- to parahydrogen conversion: Cr-doped silica and ferric oxide gel.

PubMed

Hartl, Monika; Gillis, Robert Chad; Daemen, Luke; Olds, Daniel P; Page, Katherine; Carlson, Stefan; Cheng, Yongqiang; Hügle, Thomas; Iverson, Erik B; Ramirez-Cuesta, A J; Lee, Yongjoong; Muhrer, Günter

2016-06-29

Molecular hydrogen exists in two spin-rotation coupled states: parahydrogen and orthohydrogen. Due to the variation of energy with rotational level, the occupation of ortho- and parahydrogen states is temperature dependent, with parahydrogen being the dominant species at low temperatures. The equilibrium at 20 K (99.8% parahydrogen) can be reached by natural conversion only after a lengthy process. With the use of a suitable catalyst, this process can be shortened significantly. Two types of commercial catalysts currently being used for ortho- to parahydrogen conversion are: iron(iii) oxide (Fe2O3, IONEX®), and chromium(ii) oxide doped silica catalyst (CrO·SiO2, OXISORB®). We investigate the interaction of ortho- and parahydrogen with the surfaces of these ortho-para conversion catalysts using neutron vibrational spectroscopy. The catalytic surfaces have been characterized using X-ray absorption fine structure (XAFS) and X-ray/neutron pair distribution function measurements.

Probing the photon polarization in B → K*γ with conversion

DOE PAGES

Bishara, Fady; Robinson, Dean J.

2015-09-02

We re-examine the possibility to measure the photon polarization in B → K*γ decays, via decays in which the photon subsequently undergoes nuclear conversion to a lepton pair. We obtain compact expressions for the full decay-plus-conversion amplitude. With these results we show that interference between the B → (K* → Kπ)γ decay and the γN → ℓ + ℓ – N conversion permits both the ratio and relative weak phase between the left- and right-handed photon amplitudes to be probed by an angular observable, constructed from the final state dilepton, kaon and pion kinematic configuration. Exploiting this technique will bemore » experimentally challenging. However, we present special kinematic cuts that enhance the statistical power of this technique by an O(1) factor. Furthermore, we verify this effect and extract pertinent angular kinematic distributions with dedicated numerical simulations.« less

Magnetic field effect in fluorescence of excited fluorophore equilibrated with exciplex that reversibly dissociates into radical-ion pair undergoing the spin conversion.

PubMed

Dodin, Dmitry V; Ivanov, Anatoly I; Burshtein, Anatoly I

2012-07-14

The fluorescence of the photoexcited electron acceptor, (1)A∗, and the exciplex, (1)[D(+δ)A(-δ)] formed at contact of (1)A∗ with an electron donor (1)D, is known to be very sensitive to a magnetic field, assisting the spin conversion in the resulting geminate radical ion pair (RIP), (1, 3)[D(+)...A(-)]. The relative increase of the fluorescence in the highest magnetic field compared to the lowest one, known as the magnetic field effect, crucially depends on the dielectric constant of the solvent, ɛ. This phenomenon first studied experimentally is at first reproduced here theoretically by means of the so called integral encounter theory. It was shown to be very sensitive to the position of the exciplex energy level relative to the levels of exciplex precursors and the charged products of its dissociation. The results obtained strongly depend on the dielectric properties of the solvents as well as on the exciplex and RIP formation rates.

Hyperfine interaction mechanism of magnetic field effects in sequential fluorophore and exciplex fluorescence.

PubMed

Dodin, Dmitry V; Ivanov, Anatoly I; Burshtein, Anatoly I

2013-03-28

The magnetic field effect on the fluorescence of the photoexcited electron acceptor, (1)A∗, and the exciplex, (1)[D(+δ)A(-δ)] formed at contact of (1)A∗ with an electron donor (1)D, is theoretically explored in the framework of Integral Encounter Theory. It is assumed that the excited fluorophore is equilibrated with the exciplex that reversibly dissociates into the radical-ion pair. The magnetic field sensitive stage is the spin conversion in the resulting geminate radical-ion pair, (1, 3)[D(+)...A(-)] that proceeds due to hyperfine interaction. We confirm our earlier conclusion (obtained with a rate description of spin conversion) that in the model with a single nucleus spin 1/2 the magnitude of the Magnetic Field Effect (MFE) also vanishes in the opposite limits of low and high dielectric permittivity of the solvent. Moreover, it is shown that MFE being positive at small hyperfine interaction A, first increases with A but approaching the maximum starts to decrease and even changes the sign.

Communicating with sentences: A multi-word naming game model

NASA Astrophysics Data System (ADS)

Lou, Yang; Chen, Guanrong; Hu, Jianwei

2018-01-01

Naming game simulates the process of naming an object by a single word, in which a population of communicating agents can reach global consensus asymptotically through iteratively pair-wise conversations. We propose an extension of the single-word model to a multi-word naming game (MWNG), simulating the case of describing a complex object by a sentence (multiple words). Words are defined in categories, and then organized as sentences by combining them from different categories. We refer to a formatted combination of several words as a pattern. In such an MWNG, through a pair-wise conversation, it requires the hearer to achieve consensus with the speaker with respect to both every single word in the sentence as well as the sentence pattern, so as to guarantee the correct meaning of the saying; otherwise, they fail reaching consensus in the interaction. We validate the model in three typical topologies as the underlying communication network, and employ both conventional and man-designed patterns in performing the MWNG.

Using others' words: conversational use of reported speech by individuals with aphasia and their communication partners.

PubMed

Hengst, Julie A; Frame, Simone R; Neuman-Stritzel, Tiffany; Gannaway, Rachel

2005-02-01

Reported speech, wherein one quotes or paraphrases the speech of another, has been studied extensively as a set of linguistic and discourse practices. Researchers agree that reported speech is pervasive, found across languages, and used in diverse contexts. However, to date, there have been no studies of the use of reported speech among individuals with aphasia. Grounded in an interactional sociolinguistic perspective, the study presented here documents and analyzes the use of reported speech by 7 adults with mild to moderately severe aphasia and their routine communication partners. Each of the 7 pairs was videotaped in 4 everyday activities at home or around the community, yielding over 27 hr of conversational interaction for analysis. A coding scheme was developed that identified 5 types of explicitly marked reported speech: direct, indirect, projected, indexed, and undecided. Analysis of the data documented reported speech as a common discourse practice used successfully by the individuals with aphasia and their communication partners. All participants produced reported speech at least once, and across all observations the target pairs produced 400 reported speech episodes (RSEs), 149 by individuals with aphasia and 251 by their communication partners. For all participants, direct and indirect forms were the most prevalent (70% of RSEs). Situated discourse analysis of specific episodes of reported speech used by 3 of the pairs provides detailed portraits of the diverse interactional, referential, social, and discourse functions of reported speech and explores ways that the pairs used reported speech to successfully frame talk despite their ongoing management of aphasia.

Moral Appraisals Affect Doing/Allowing Judgments

ERIC Educational Resources Information Center

Cushman, Fiery; Knobe, Joshua; Sinnott-Armstrong, Walter

2008-01-01

An extensive body of research suggests that the distinction between doing and allowing plays a critical role in shaping moral appraisals. Here, we report evidence from a pair of experiments suggesting that the converse is also true: moral appraisals affect doing/allowing judgments. Specifically, morally bad behavior is more likely to be construed…

Effects of Visual and Verbal Interaction on Unintentional Interpersonal Coordination

ERIC Educational Resources Information Center

Richardson, Michael J.; Marsh, Kerry L.; Schmidt, R. C.

2005-01-01

Previous research has demonstrated that people's movements can become unintentionally coordinated during interpersonal interaction. The current study sought to uncover the degree to which visual and verbal (conversation) interaction constrains and organizes the rhythmic limb movements of coactors. Two experiments were conducted in which pairs of…

Speed Pairs, a Spoken Exercise

ERIC Educational Resources Information Center

Kishi, Adrienne

2017-01-01

While written exercises may serve students adequately on tests, the structures they emphasize can remain elusive or difficult for students to master in conversation. Students tend to interpret their difficulty in applying what they have learned as a lack of language ability, and they can quickly lose confidence when speaking. Producing a target…

Conversion of carbohydrate into hydrogen fuel by a photocatalytic process

NASA Astrophysics Data System (ADS)

Kawai, T.; Sakata, T.

1980-07-01

A photocatalytic process for the conversion of carbohydrates into hydrogen fuel is presented. The method involves the irradiation of sugar, starch or cellulose in the presence of water and a RuO2/TiO2/Pt catalyst, which has been found to lead to the generation of CO2 and H2 at efficiencies 100 times larger than those obtained with TiO2 alone, with no detectable amounts of other products. The reaction mechanism can be explained in terms of an electrochemical microcell, in which electron-hole pairs generated in TiO2 cause redox reactions at the surface. The process may thus be used in the conversion of solar energy stored in the form of carbohydrates by green plant photosynthesis into useful hydrogen fuels.

Generation of Nonclassical Biphoton States through Cascaded Quantum Walks on a Nonlinear Chip

NASA Astrophysics Data System (ADS)

Solntsev, Alexander S.; Setzpfandt, Frank; Clark, Alex S.; Wu, Che Wen; Collins, Matthew J.; Xiong, Chunle; Schreiber, Andreas; Katzschmann, Fabian; Eilenberger, Falk; Schiek, Roland; Sohler, Wolfgang; Mitchell, Arnan; Silberhorn, Christine; Eggleton, Benjamin J.; Pertsch, Thomas; Sukhorukov, Andrey A.; Neshev, Dragomir N.; Kivshar, Yuri S.

2014-07-01

We demonstrate a nonlinear optical chip that generates photons with reconfigurable nonclassical spatial correlations. We employ a quadratic nonlinear waveguide array, where photon pairs are generated through spontaneous parametric down-conversion and simultaneously spread through quantum walks between the waveguides. Because of the quantum interference of these cascaded quantum walks, the emerging photons can become entangled over multiple waveguide positions. We experimentally observe highly nonclassical photon-pair correlations, confirming the high fidelity of on-chip quantum interference. Furthermore, we demonstrate biphoton-state tunability by spatial shaping and frequency tuning of the classical pump beam.

Total teleportation of a single-photon state

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

Humble, Travis S; Bennink, Ryan S; Grice, Warren P

2008-01-01

Recent demonstrations of teleportation have transferred quantum information encoded into either polarization or field-quadrature degrees of freedom (DOFs), but an outstanding question is how to simultaneously teleport quantum information encoded into multiple DOFs. We describe how the transverse-spatial, spectral and polarization states of a single photon can be simultaneously teleported using a pair of multimode, polarization-entangled photons derived from spontaneous parametric down-conversion. Furthermore, when the initial photon pair is maximally entangled in the spatial, spectral, and polarization DOFs then the photon s full quantum state can be reliably teleported using a Bell-state measurement based on sum-frequency generation.

Units of rotational information

NASA Astrophysics Data System (ADS)

Yang, Yuxiang; Chiribella, Giulio; Hu, Qinheping

2017-12-01

Entanglement in angular momentum degrees of freedom is a precious resource for quantum metrology and control. Here we study the conversions of this resource, focusing on Bell pairs of spin-J particles, where one particle is used to probe unknown rotations and the other particle is used as reference. When a large number of pairs are given, we show that every rotated spin-J Bell state can be reversibly converted into an equivalent number of rotated spin one-half Bell states, at a rate determined by the quantum Fisher information. This result provides the foundation for the definition of an elementary unit of information about rotations in space, which we call the Cartesian refbit. In the finite copy scenario, we design machines that approximately break down Bell states of higher spins into Cartesian refbits, as well as machines that approximately implement the inverse process. In addition, we establish a quantitative link between the conversion of Bell states and the simulation of unitary gates, showing that the fidelity of probabilistic state conversion provides upper and lower bounds on the fidelity of deterministic gate simulation. The result holds not only for rotation gates, but also to all sets of gates that form finite-dimensional representations of compact groups. For rotation gates, we show how rotations on a system of given spin can simulate rotations on a system of different spin.

Weak e+e- lines from internal pair conversion observed in collisions of 238U with heavy nuclei

NASA Astrophysics Data System (ADS)

Heinz, S.; Berdermann, E.; Heine, F.; Joeres, O.; Kienle, P.; Koenig, I.; Koenig, W.; Kozhuharov, C.; Leinberger, U.; Rhein, M.; Schröter, A.; Tsertos, H.

1998-01-01

We present the results of a Doppler-shift correction to the measured e+e- sum-energy spectra obtained from e+e- coincidence measurements in 238U +206Pb and 238U +181Ta collisions at beam energies close to the Coulomb barrier, using an improved experimental setup at the double-Orange spectrometer of GSI. Internal-Pair-Conversion (IPC) e+e- pairs from discrete nuclear transitions of a moving emitter have been observed following Coulomb excitation of the 1.844 MeV (E1) transition in 206Pb and neutron transfer to the 1.770 MeV (M1) transition in 207Pb. In the collision system 238U +181Ta, IPC transitions were observed from the Ta-like as well as from the U-like nuclei. In all systems the Doppler-shift corrected e+e- sum-energy spectra show weak lines at the energies expected from the corresponding γ ray spectra with cross sections being consistent with the measured excitation cross sections of the γ lines and the theoretically predicted IPC coefficients. No other than IPC e+e- sum-energy lines were found in the measured spectra. The transfer cross sections show a strong dependence on the distance of closest approach (Rmin), thus signaling also a strong dependence on the bombarding energy close to the Coulomb barrier.

Experimental Demonstration of a Hybrid-Quantum-Emitter Producing Individual Entangled Photon Pairs in the Telecom Band

PubMed Central

Chen, Geng; Zou, Yang; Zhang, Wen-Hao; Zhang, Zi-Huai; Zhou, Zong-Quan; He, De-Yong; Tang, Jian-Shun; Liu, Bi-Heng; Yu, Ying; Zha, Guo-Wei; Ni, Hai-Qiao; Niu, Zhi-Chuan; Han, Yong-Jian; Li, Chuan-Feng; Guo, Guang-Can

2016-01-01

Quantum emitters generating individual entangled photon pairs (IEPP) have significant fundamental advantages over schemes that suffer from multiple photon emission, or schemes that require post-selection techniques or the use of photon-number discriminating detectors. Quantum dots embedded within nanowires (QD-NWs) represent one of the most promising candidate for quantum emitters that provide a high collection efficiency of photons. However, a quantum emitter that generates IEPP in the telecom band is still an issue demanding a prompt solution. Here, we demonstrate in principle that IEPPs in the telecom band can be created by combining a single QD-NW and a nonlinear crystal waveguide. The QD-NW system serves as the single photon source, and the emitted visible single photons are split into IEPPs at approximately 1.55 μm through the process of spontaneous parametric down conversion (SPDC) in a periodically poled lithium niobate (PPLN) waveguide. The compatibility of the QD-PPLN interface is the determinant factor in constructing this novel hybrid-quantum-emitter (HQE). Benefiting from the desirable optical properties of QD-NWs and the extremely high nonlinear conversion efficiency of PPLN waveguides, we successfully generate IEPPs in the telecom band with the polarization degree of freedom. The entanglement of the generated photon pairs is confirmed by the entanglement witness. Our experiment paves the way to producing HQEs inheriting the advantages of multiple systems. PMID:27225881

Experimental Demonstration of a Hybrid-Quantum-Emitter Producing Individual Entangled Photon Pairs in the Telecom Band.

PubMed

Chen, Geng; Zou, Yang; Zhang, Wen-Hao; Zhang, Zi-Huai; Zhou, Zong-Quan; He, De-Yong; Tang, Jian-Shun; Liu, Bi-Heng; Yu, Ying; Zha, Guo-Wei; Ni, Hai-Qiao; Niu, Zhi-Chuan; Han, Yong-Jian; Li, Chuan-Feng; Guo, Guang-Can

2016-05-26

Quantum emitters generating individual entangled photon pairs (IEPP) have significant fundamental advantages over schemes that suffer from multiple photon emission, or schemes that require post-selection techniques or the use of photon-number discriminating detectors. Quantum dots embedded within nanowires (QD-NWs) represent one of the most promising candidate for quantum emitters that provide a high collection efficiency of photons. However, a quantum emitter that generates IEPP in the telecom band is still an issue demanding a prompt solution. Here, we demonstrate in principle that IEPPs in the telecom band can be created by combining a single QD-NW and a nonlinear crystal waveguide. The QD-NW system serves as the single photon source, and the emitted visible single photons are split into IEPPs at approximately 1.55 μm through the process of spontaneous parametric down conversion (SPDC) in a periodically poled lithium niobate (PPLN) waveguide. The compatibility of the QD-PPLN interface is the determinant factor in constructing this novel hybrid-quantum-emitter (HQE). Benefiting from the desirable optical properties of QD-NWs and the extremely high nonlinear conversion efficiency of PPLN waveguides, we successfully generate IEPPs in the telecom band with the polarization degree of freedom. The entanglement of the generated photon pairs is confirmed by the entanglement witness. Our experiment paves the way to producing HQEs inheriting the advantages of multiple systems.

Temporal plasticity in auditory cortex improves neural discrimination of speech sounds

PubMed Central

Engineer, Crystal T.; Shetake, Jai A.; Engineer, Navzer D.; Vrana, Will A.; Wolf, Jordan T.; Kilgard, Michael P.

2017-01-01

Background Many individuals with language learning impairments exhibit temporal processing deficits and degraded neural responses to speech sounds. Auditory training can improve both the neural and behavioral deficits, though significant deficits remain. Recent evidence suggests that vagus nerve stimulation (VNS) paired with rehabilitative therapies enhances both cortical plasticity and recovery of normal function. Objective/Hypothesis We predicted that pairing VNS with rapid tone trains would enhance the primary auditory cortex (A1) response to unpaired novel speech sounds. Methods VNS was paired with tone trains 300 times per day for 20 days in adult rats. Responses to isolated speech sounds, compressed speech sounds, word sequences, and compressed word sequences were recorded in A1 following the completion of VNS-tone train pairing. Results Pairing VNS with rapid tone trains resulted in stronger, faster, and more discriminable A1 responses to speech sounds presented at conversational rates. Conclusion This study extends previous findings by documenting that VNS paired with rapid tone trains altered the neural response to novel unpaired speech sounds. Future studies are necessary to determine whether pairing VNS with appropriate auditory stimuli could potentially be used to improve both neural responses to speech sounds and speech perception in individuals with receptive language disorders. PMID:28131520

Multi-user distribution of polarization entangled photon pairs

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

Trapateau, J.; Orieux, A.; Diamanti, E.

We experimentally demonstrate multi-user distribution of polarization entanglement using commercial telecom wavelength division demultiplexers. The entangled photon pairs are generated from a broadband source based on spontaneous parametric down conversion in a periodically poled lithium niobate crystal using a double path setup employing a Michelson interferometer and active phase stabilisation. We test and compare demultiplexers based on various technologies and analyze the effect of their characteristics, such as losses and polarization dependence, on the quality of the distributed entanglement for three channel pairs of each demultiplexer. In all cases, we obtain a Bell inequality violation, whose value depends on themore » demultiplexer features. This demonstrates that entanglement can be distributed to at least three user pairs of a network from a single source. Additionally, we verify for the best demultiplexer that the violation is maintained when the pairs are distributed over a total channel attenuation corresponding to 20 km of optical fiber. These techniques are therefore suitable for resource-efficient practical implementations of entanglement-based quantum key distribution and other quantum communication network applications.« less

How does conversion of natural tropical rainforest ecosystems affect soil bacterial and fungal communities in the Nile river watershed of Uganda?

PubMed

Alele, Peter O; Sheil, Douglas; Surget-Groba, Yann; Lingling, Shi; Cannon, Charles H

2014-01-01

Uganda's forests are globally important for their conservation values but are under pressure from increasing human population and consumption. In this study, we examine how conversion of natural forest affects soil bacterial and fungal communities. Comparisons in paired natural forest and human-converted sites among four locations indicated that natural forest soils consistently had higher pH, organic carbon, nitrogen, and calcium, although variation among sites was large. Despite these differences, no effect on the diversity of dominant taxa for either bacterial or fungal communities was detected, using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Composition of fungal communities did generally appear different in converted sites, but surprisingly, we did not observe a consistent pattern among sites. The spatial distribution of some taxa and community composition was associated with soil pH, organic carbon, phosphorus and sodium, suggesting that changes in soil communities were nuanced and require more robust metagenomic methods to understand the various components of the community. Given the close geographic proximity of the paired sampling sites, the similarity between natural and converted sites might be due to continued dispersal between treatments. Fungal communities showed greater environmental differentiation than bacterial communities, particularly according to soil pH. We detected biotic homogenization in converted ecosystems and substantial contribution of β-diversity to total diversity, indicating considerable geographic structure in soil biota in these forest communities. Overall, our results suggest that soil microbial communities are relatively resilient to forest conversion and despite a substantial and consistent change in the soil environment, the effects of conversion differed widely among sites. The substantial difference in soil chemistry, with generally lower nutrient quantity in converted sites, does bring into question, how long this resilience will last.

Enlightenment of Yeast Mitochondrial Homoplasmy: Diversified Roles of Gene Conversion

PubMed Central

Ling, Feng; Mikawa, Tsutomu; Shibata, Takehiko

2011-01-01

Mitochondria have their own genomic DNA. Unlike the nuclear genome, each cell contains hundreds to thousands of copies of mitochondrial DNA (mtDNA). The copies of mtDNA tend to have heterogeneous sequences, due to the high frequency of mutagenesis, but are quickly homogenized within a cell (“homoplasmy”) during vegetative cell growth or through a few sexual generations. Heteroplasmy is strongly associated with mitochondrial diseases, diabetes and aging. Recent studies revealed that the yeast cell has the machinery to homogenize mtDNA, using a common DNA processing pathway with gene conversion; i.e., both genetic events are initiated by a double-stranded break, which is processed into 3′ single-stranded tails. One of the tails is base-paired with the complementary sequence of the recipient double-stranded DNA to form a D-loop (homologous pairing), in which repair DNA synthesis is initiated to restore the sequence lost by the breakage. Gene conversion generates sequence diversity, depending on the divergence between the donor and recipient sequences, especially when it occurs among a number of copies of a DNA sequence family with some sequence variations, such as in immunoglobulin diversification in chicken. MtDNA can be regarded as a sequence family, in which the members tend to be diversified by a high frequency of spontaneous mutagenesis. Thus, it would be interesting to determine why and how double-stranded breakage and D-loop formation induce sequence homogenization in mitochondria and sequence diversification in nuclear DNA. We will review the mechanisms and roles of mtDNA homoplasmy, in contrast to nuclear gene conversion, which diversifies gene and genome sequences, to provide clues toward understanding how the common DNA processing pathway results in such divergent outcomes. PMID:24710143

How Does Conversion of Natural Tropical Rainforest Ecosystems Affect Soil Bacterial and Fungal Communities in the Nile River Watershed of Uganda?

PubMed Central

Alele, Peter O.; Sheil, Douglas; Surget-Groba, Yann; Lingling, Shi; Cannon, Charles H.

2014-01-01

Uganda's forests are globally important for their conservation values but are under pressure from increasing human population and consumption. In this study, we examine how conversion of natural forest affects soil bacterial and fungal communities. Comparisons in paired natural forest and human-converted sites among four locations indicated that natural forest soils consistently had higher pH, organic carbon, nitrogen, and calcium, although variation among sites was large. Despite these differences, no effect on the diversity of dominant taxa for either bacterial or fungal communities was detected, using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Composition of fungal communities did generally appear different in converted sites, but surprisingly, we did not observe a consistent pattern among sites. The spatial distribution of some taxa and community composition was associated with soil pH, organic carbon, phosphorus and sodium, suggesting that changes in soil communities were nuanced and require more robust metagenomic methods to understand the various components of the community. Given the close geographic proximity of the paired sampling sites, the similarity between natural and converted sites might be due to continued dispersal between treatments. Fungal communities showed greater environmental differentiation than bacterial communities, particularly according to soil pH. We detected biotic homogenization in converted ecosystems and substantial contribution of β-diversity to total diversity, indicating considerable geographic structure in soil biota in these forest communities. Overall, our results suggest that soil microbial communities are relatively resilient to forest conversion and despite a substantial and consistent change in the soil environment, the effects of conversion differed widely among sites. The substantial difference in soil chemistry, with generally lower nutrient quantity in converted sites, does bring into question, how long this resilience will last. PMID:25118069

Plasma Heating and Alfvénic Turbulence Enhancement During Two Steps of Energy Conversion in Magnetic Reconnection Exhaust Region of Solar Wind

NASA Astrophysics Data System (ADS)

Jiansen, He; Xingyu, Zhu; Yajie, Chen; Chadi, Salem; Michael, Stevens; Hui, Li; Wenzhi, Ruan; Lei, Zhang; Chuanyi, Tu

2018-04-01

The magnetic reconnection exhaust is a pivotal region with enormous magnetic energy being continuously released and converted. The physical processes of energy conversion involved are so complicated that an all-round understanding based on in situ measurements is still lacking. We present the evidence of plasma heating by illustrating the broadening of proton and electron velocity distributions, which are extended mainly along the magnetic field, in an exhaust of interchange reconnection between two interplanetary magnetic flux tubes of the same polarity on the Sun. The exhaust is asymmetric across an interface, with both sides being bounded by a pair of compound discontinuities consisting of rotational discontinuity and slow shock. The energized plasmas are found to be firehose unstable, and responsible for the emanation of Alfvén waves during the second step of energy conversion. It is realized that the energy conversion in the exhaust can be a two-step process involving both plasma energization and wave emission.

First Footing Inter-Faith Dialogue

ERIC Educational Resources Information Center

Luby, Antony

2014-01-01

This article examines an action research project on inter-faith dialogue within the sensitive context of Catholic pupils being taught Catholic religious education in state-funded secondary schools. Twenty pupils in S3 and S4 (Year 10 and Year 11) participated in a series of three paired conversations that focused primarily on science and religion,…

Cooperative Autonomy in Online Lingua Franca Exchanges: A Case Study on Foreign Language Education in Secondary Schools

ERIC Educational Resources Information Center

Hoffstaedter, Petra; Kohn, Kurt

2016-01-01

We report on a case study on pedagogical affordances of intercultural telecollaboration for authentic communication practice and competence development in the local foreign language. Focus is on spoken and written conversations involving pairs of secondary school pupils of different linguacultural backgrounds. Particular attention is given to…

SiC/Si diode trigger circuit provides automatic range switching for log amplifier

NASA Technical Reports Server (NTRS)

1967-01-01

SiC/Si diode pair provides automatic range change to extend the operating range of a logarithmic amplifier-conversion circuit and assures stability at or near the range switch-over point. the diode provides hysteresis for a trigger circuit that actuates a relay at the desired range extension point.

Here's Looking at You, Kid.

ERIC Educational Resources Information Center

Milshtein, Amy

1997-01-01

The University of Maryland at College Park installed 25 surveillance cameras to combat crime. A minimum of disruption occurred because unused twisted pair wires left in place when the conversion to a fiber optic telephone system was made could be used for the camera installations. The campus is safer, and its budget is intact. (RE)

Whose Thinking Is It Anyway? Role-Pair Blends in the ALM Community.

ERIC Educational Resources Information Center

Duffin, Janet; Simpson, Adrian

Evidence of tension between teachers and researchers regarding the work that researchers undertake in classrooms surfaces from time to time. The title of this conference, "A Conversation between Researchers and Practitioners", testifies to the importance of interaction between the users and providers of research. Indeed, in this paper, we will…

Structural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics

NASA Astrophysics Data System (ADS)

Tautz, Raphael; da Como, Enrico; Limmer, Thomas; Feldmann, Jochen; Egelhaaf, Hans-Joachim; von Hauff, Elizabeth; Lemaur, Vincent; Beljonne, David; Yilmaz, Seyfullah; Dumsch, Ines; Allard, Sybille; Scherf, Ullrich

2012-07-01

Polymeric semiconductors are materials where unique optical and electronic properties often originate from a tailored chemical structure. This allows for synthesizing conjugated macromolecules with ad hoc functionalities for organic electronics. In photovoltaics, donor-acceptor co-polymers, with moieties of different electron affinity alternating on the chain, have attracted considerable interest. The low bandgap offers optimal light-harvesting characteristics and has inspired work towards record power conversion efficiencies. Here we show for the first time how the chemical structure of donor and acceptor moieties controls the photogeneration of polaron pairs. We show that co-polymers with strong acceptors show large yields of polaron pair formation up to 24% of the initial photoexcitations as compared with a homopolymer (η=8%). π-conjugated spacers, separating the donor and acceptor centre of masses, have the beneficial role of increasing the recombination time. The results provide useful input into the understanding of polaron pair photogeneration in low-bandgap co-polymers for photovoltaics.

An experimental investigation of preorgasmic reconditioning and postorgasmic deconditioning.

PubMed Central

Kantorowitz, D A

1978-01-01

The effects of pre- and postorgasmic presentation of moderately erotic cues were assessed in an analogue study. Eight heterosexual male volunteers (18 to 23 years) participated in three assessment (baseline, termination-of-treatment, and two- to three-month followup) and eight masturbatory conditioning sessions. Three slides of nude females of initially equal erotic value were paired respectively with the plateau, refractory, and resolution phases of the subjects' sexual cycles. Over treatment, stimuli paired with the plateau phase increased significantly in penile tumescence indices of eroticism; conversely, stimuli paired with the refractory phase decreased significantly. The conditioned effects on tumescence were largely extinguished at followup. While treatment did not alter short-term subjective indices of eroticism, stimuli presented during the refractory phase were rated significantly less erotic than the other stimuli at followup. The findings suggest that the "pairing" model of orgasmic conditioning is insufficient to account for previously reported clinical findings. A broader conceptualization of the mechanisms of orgasmic conditioning, and implications for treatment are discussed. PMID:649527

An experimental investigation of preorgasmic reconditioning and postorgasmic deconditioning.

PubMed

Kantorowitz, D A

1978-01-01

The effects of pre- and postorgasmic presentation of moderately erotic cues were assessed in an analogue study. Eight heterosexual male volunteers (18 to 23 years) participated in three assessment (baseline, termination-of-treatment, and two- to three-month followup) and eight masturbatory conditioning sessions. Three slides of nude females of initially equal erotic value were paired respectively with the plateau, refractory, and resolution phases of the subjects' sexual cycles. Over treatment, stimuli paired with the plateau phase increased significantly in penile tumescence indices of eroticism; conversely, stimuli paired with the refractory phase decreased significantly. The conditioned effects on tumescence were largely extinguished at followup. While treatment did not alter short-term subjective indices of eroticism, stimuli presented during the refractory phase were rated significantly less erotic than the other stimuli at followup. The findings suggest that the "pairing" model of orgasmic conditioning is insufficient to account for previously reported clinical findings. A broader conceptualization of the mechanisms of orgasmic conditioning, and implications for treatment are discussed.

Energy conversion modeling of the intrinsic persistent luminescence of solids via energy transfer paths between transition levels.

PubMed

Huang, Bolong; Sun, Mingzi

2017-04-05

An energy conversion model has been established for the intrinsic persistent luminescence in solids related to the native point defect levels, formations, and transitions. In this study, we showed how the recombination of charge carriers between different defect levels along the zero phonon line (ZPL) can lead to energy conversions supporting the intrinsic persistent phosphorescence in solids. This suggests that the key driving force for this optical phenomenon is the pair of electrons hopping between different charged defects with negative-U eff . Such a negative correlation energy will provide a sustainable energy source for electron-holes to further recombine in a new cycle with a specific quantum yield. This will help us to understand the intrinsic persistent luminescence with respect to native point defect levels as well as the correlations of electronics and energetics.

Properties of entangled photon pairs generated in one-dimensional nonlinear photonic-band-gap structures

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

Perina, Jan Jr.; Centini, Marco; Sibilia, Concita

We have developed a rigorous quantum model of spontaneous parametric down-conversion in a nonlinear 1D photonic-band-gap structure based upon expansion of the field into monochromatic plane waves. The model provides a two-photon amplitude of a created photon pair. The spectra of the signal and idler fields, their intensity profiles in the time domain, as well as the coincidence-count interference pattern in a Hong-Ou-Mandel interferometer are determined both for cw and pulsed pumping regimes in terms of the two-photon amplitude. A broad range of parameters characterizing the emitted down-converted fields can be used. As an example, a structure composed of 49more » layers of GaN/AlN is analyzed as a suitable source of photon pairs having high efficiency.« less

Gamma beams generation with high intensity lasers for two photon Breit-Wheeler pair production

NASA Astrophysics Data System (ADS)

D'Humieres, Emmanuel; Ribeyre, Xavier; Jansen, Oliver; Esnault, Leo; Jequier, Sophie; Dubois, Jean-Luc; Hulin, Sebastien; Tikhonchuk, Vladimir; Arefiev, Alex; Toncian, Toma; Sentoku, Yasuhiko

2017-10-01

Linear Breit-Wheeler pair creation is the lowest threshold process in photon-photon interaction, controlling the energy release in Gamma Ray Bursts and Active Galactic Nuclei, but it has never been directly observed in the laboratory. Using numerical simulations, we demonstrate the possibility to produce collimated gamma beams with high energy conversion efficiency using high intensity lasers and innovative targets. When two of these beams collide at particular angles, our analytical calculations demonstrate a beaming effect easing the detection of the pairs in the laboratory. This effect has been confirmed in photon collision simulations using a recently developed innovative algorithm. An alternative scheme using Bremsstrahlung radiation produced by next generation high repetition rate laser systems is also being explored and the results of first optimization campaigns in this regime will be presented.

Approach bias for food cues in obese individuals.

PubMed

Kemps, Eva; Tiggemann, Marika

2015-01-01

This study aimed to investigate the existence of an approach bias for food cues in obese individuals. A community sample of 56 obese women and 56 normal weight controls completed an approach-avoidance variant of the implicit association task. The obese participants were faster to respond to trials that paired food words with approach words, and trials that paired non-food words with avoid words, than the converse pairings, thus, demonstrating an approach bias for food. This bias was evident for both high caloric and low caloric food words, and was not attributable to a state of deprivation or feelings of hunger. By contrast, the normal weight controls did not show any such bias. The results are consistent with recent neurocognitive perspectives of obesity. At a practical level, approach biases for food may present a potential target for modifying (excessive) food intake.

The communicative functions of final rises in Finnish intonation.

PubMed

Ogden, Richard; Routarinne, Sara

2005-01-01

This paper considers the communicative function of final rises in Finnish conversational talk between pairs of teenage girls. Final rises are fairly common, occurring approximately twice a minute, predominantly on declaratives and in narrative sequences. We briefly consider the interplay between voice quality (known to be a marker of transition relevance) and rising intonation in Finnish. We argue that in narrative sequences, rising terminals manage two main interactional tasks: they provide a place for a coparticipant to mark recipiency, and they project more talk by the current speaker. Using a methodology which combines phonetic observation with conversation analysis, we demonstrate participants' orientation to these functions.

Carbon aerogel electrodes for direct energy conversion

DOEpatents

Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

1997-01-01

A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

Simple performance evaluation of pulsed spontaneous parametric down-conversion sources for quantum communications.

PubMed

Smirr, Jean-Loup; Guilbaud, Sylvain; Ghalbouni, Joe; Frey, Robert; Diamanti, Eleni; Alléaume, Romain; Zaquine, Isabelle

2011-01-17

Fast characterization of pulsed spontaneous parametric down conversion (SPDC) sources is important for applications in quantum information processing and communications. We propose a simple method to perform this task, which only requires measuring the counts on the two output channels and the coincidences between them, as well as modeling the filter used to reduce the source bandwidth. The proposed method is experimentally tested and used for a complete evaluation of SPDC sources (pair emission probability, total losses, and fidelity) of various bandwidths. This method can find applications in the setting up of SPDC sources and in the continuous verification of the quality of quantum communication links.

The "Supercritical Pile" Model for GRB: Tapping the Proton Energy and Getting the v F(sub V) Peak at Approx. 1 MeV

NASA Technical Reports Server (NTRS)

Kazanas, D.; Georganopoulos, M.; Mastichladis, A.

2003-01-01

We propose a process by which the kinetic energy of the protons, that carry most of the energy of GRB relativistic blast waves (RBW) of Lorentz factor is converted explosively into relativistic electrons of the same Lorentz factor, which subsequently produce the observed prompt gamma-ray emission of the burst. This conversion is the result of the combined effects of the reflection of photons produced within the flow by upstream located matter, their re-interception and conversion into e(+) e(-) pairs on the RBW by the p gamma (right arrow) p e(+) e(-) reaction.

Impact of deep learning on the normalization of reconstruction kernel effects in imaging biomarker quantification: a pilot study in CT emphysema

NASA Astrophysics Data System (ADS)

Jin, Hyeongmin; Heo, Changyong; Kim, Jong Hyo

2018-02-01

Differing reconstruction kernels are known to strongly affect the variability of imaging biomarkers and thus remain as a barrier in translating the computer aided quantification techniques into clinical practice. This study presents a deep learning application to CT kernel conversion which converts a CT image of sharp kernel to that of standard kernel and evaluates its impact on variability reduction of a pulmonary imaging biomarker, the emphysema index (EI). Forty cases of low-dose chest CT exams obtained with 120kVp, 40mAs, 1mm thickness, of 2 reconstruction kernels (B30f, B50f) were selected from the low dose lung cancer screening database of our institution. A Fully convolutional network was implemented with Keras deep learning library. The model consisted of symmetric layers to capture the context and fine structure characteristics of CT images from the standard and sharp reconstruction kernels. Pairs of the full-resolution CT data set were fed to input and output nodes to train the convolutional network to learn the appropriate filter kernels for converting the CT images of sharp kernel to standard kernel with a criterion of measuring the mean squared error between the input and target images. EIs (RA950 and Perc15) were measured with a software package (ImagePrism Pulmo, Seoul, South Korea) and compared for the data sets of B50f, B30f, and the converted B50f. The effect of kernel conversion was evaluated with the mean and standard deviation of pair-wise differences in EI. The population mean of RA950 was 27.65 +/- 7.28% for B50f data set, 10.82 +/- 6.71% for the B30f data set, and 8.87 +/- 6.20% for the converted B50f data set. The mean of pair-wise absolute differences in RA950 between B30f and B50f is reduced from 16.83% to 1.95% using kernel conversion. Our study demonstrates the feasibility of applying the deep learning technique for CT kernel conversion and reducing the kernel-induced variability of EI quantification. The deep learning model has a potential to improve the reliability of imaging biomarker, especially in evaluating the longitudinal changes of EI even when the patient CT scans were performed with different kernels.

Layer-Based Approach for Image Pair Fusion.

PubMed

Son, Chang-Hwan; Zhang, Xiao-Ping

2016-04-20

Recently, image pairs, such as noisy and blurred images or infrared and noisy images, have been considered as a solution to provide high-quality photographs under low lighting conditions. In this paper, a new method for decomposing the image pairs into two layers, i.e., the base layer and the detail layer, is proposed for image pair fusion. In the case of infrared and noisy images, simple naive fusion leads to unsatisfactory results due to the discrepancies in brightness and image structures between the image pair. To address this problem, a local contrast-preserving conversion method is first proposed to create a new base layer of the infrared image, which can have visual appearance similar to another base layer such as the denoised noisy image. Then, a new way of designing three types of detail layers from the given noisy and infrared images is presented. To estimate the noise-free and unknown detail layer from the three designed detail layers, the optimization framework is modeled with residual-based sparsity and patch redundancy priors. To better suppress the noise, an iterative approach that updates the detail layer of the noisy image is adopted via a feedback loop. This proposed layer-based method can also be applied to fuse another noisy and blurred image pair. The experimental results show that the proposed method is effective for solving the image pair fusion problem.

Divorce and infidelity are associated with skewed adult sex ratios in birds.

PubMed

Liker, András; Freckleton, Robert P; Székely, Tamás

2014-04-14

Adult sex ratio (ASR) is a fundamental concept in population demography, and recent theory suggests that ASR plays a central role in social behavior, mating systems, and parental care. Unbalanced ASRs are predicted to influence pair-bond and mating behavior, since the rarer sex in the population has more potential partners to mate with than the more common sex. Here we use phylogenetic comparative analyses to test whether ASR is related to three major aspects of mating behavior: divorce, social polygamy, and pair-bond infidelity. ASR is strongly correlated with long-term pair bonds, since the divorce rate is higher in species with a female-biased sex ratio, indicating that mate change by pair members and/or breaking of pair bonds by unmated individuals is more frequent when females outnumber males. Short-term pair bonds are also associated with unbalanced ASRs: males are more commonly polygamous when females outnumber males, and conversely, females are more polygamous when males outnumber females. Furthermore, infidelity increases with male-biased ASR in socially monogamous birds, suggesting that male coercion and/or female willingness to cheat the partner are facilitated by male-biased ASR. Our results provide the first comprehensive support for the proposition that ASR influences multiple aspects of pair-bond and mating behavior in wild populations. Copyright © 2014 Elsevier Ltd. All rights reserved.

What's the Problem? L2 Learners' Use of the L1 during Consciousness-Raising, Form-Focused Tasks

ERIC Educational Resources Information Center

Scott, Virginia M.; de la Fuente, Maria Jose

2008-01-01

This qualitative study provides preliminary insight into the role of the first language (L1) when pairs of intermediate-level college learners of French and Spanish are engaged in consciousness-raising, form-focused grammar tasks. Using conversation analysis of audiotaped interactions and stimulated recall sessions, we explored the ways students…

Investigating Negotiation of Meaning in EFL Children with Very Low Levels of Proficiency

ERIC Educational Resources Information Center

Lázaro, Amparo; Azpilicueta-Martinez, Raúl

2015-01-01

Numerous studies hold that interaction has beneficial effects on second language acquisition among adults and children in second language contexts. However, data from children learning English as a foreign language are still unavailable. In order to fill this research niche, this study examines the conversational interactions of 8 pairs of young…

Conversion to pine: Changes in timing and magnitude of high and low flows.

Treesearch

Yusuf Serengil; Wayne T. Swank; Mark S. Riedel; James M. Vose

2011-01-01

Understanding watershed responses to extreme events is important for assessing potential impacts of floods, droughts, episodic pollution, and other external driving variables on watershed resources. In this study, we combine trend and frequency analyses with paired watershed techniques to evaluate the long-term high- and low-flow data from Coweeta Hydrologic Laboratory...

Evidence for degenerate tetraploidy in bdelloid rotifers.

PubMed

Mark Welch, David B; Mark Welch, Jessica L; Meselson, Matthew

2008-04-01

Rotifers of class Bdelloidea have evolved for millions of years apparently without sexual reproduction. We have sequenced 45- to 70-kb regions surrounding the four copies of the hsp82 gene of the bdelloid rotifer Philodina roseola, each of which is on a separate chromosome. The four regions comprise two colinear gene-rich pairs with gene content, order, and orientation conserved within each pair. Only a minority of genes are common to both pairs, also in the same orientation and order, but separated by gene-rich segments present in only one or the other pair. The pattern is consistent with degenerate tetraploidy with numerous segmental deletions, some in one pair of colinear chromosomes and some in the other. Divergence in 1,000-bp windows varies along an alignment of a colinear pair, from zero to as much as 20% in a pattern consistent with gene conversion associated with recombinational repair of DNA double-strand breaks. Although pairs of colinear chromosomes are a characteristic of sexually reproducing diploids and polyploids, a quite different explanation for their presence in bdelloids is suggested by the recent finding that bdelloid rotifers can recover and resume reproduction after suffering hundreds of radiation-induced DNA double-strand breaks per oocyte nucleus. Because bdelloid primary oocytes are in G(1) and therefore lack sister chromatids, we propose that bdelloid colinear chromosome pairs are maintained as templates for the repair of DNA double-strand breaks caused by the frequent desiccation and rehydration characteristic of bdelloid habitats.

Localised and delocalised optically induced conversion of composite glow peak 5 in LiF:Mg,Ti (TLD-100) to glow peak 4 as a function of postirradiation annealing temperature.

PubMed

Horowitz, Y S; Einav, Y; Biderman, S; Oster, L

2002-01-01

The composite structure of glow peak 5 in LiF:Mg,Ti (TLD-100) has been investigated using optical bleaching by 310 nm (4 eV) light. The glow peak conversion efficiency of peak 5a (Tm = 187 degrees C) to peak 4 traps is very high at a value of 3+/-0.5 (1 SD) whereas the glow peak conversion efficiency of peak 5 (Tm = 205 degrees C) to peak 4 traps is 0.0026+/-0.0012 (1 SD). The high conversion efficiency of peak 5a to peak 4 arises from direct optical ionisation of the electron in the electron-hole pair. leaving behind a singly-trapped hole (peak 4), a direct mechanism, relatively free of competitive mechanisms. Optical ionisation of the 'singly-trapped' electron (peak 5), however, can lead to peak 4 only via multi-stage mechanisms involving charge carrier transport in the valence and conduction bands, a mechanism subject to competitive processes. The conduction/valence band competitive processes lead to the factor of one thousand decrease in the conversion efficiency of peak 5 compared to peak 5a.

Rapid 2D-to-3D conversion

NASA Astrophysics Data System (ADS)

Harman, Philip V.; Flack, Julien; Fox, Simon; Dowley, Mark

2002-05-01

The conversion of existing 2D images to 3D is proving commercially viable and fulfills the growing need for high quality stereoscopic images. This approach is particularly effective when creating content for the new generation of autostereoscopic displays that require multiple stereo images. The dominant technique for such content conversion is to develop a depth map for each frame of 2D material. The use of a depth map as part of the 2D to 3D conversion process has a number of desirable characteristics: 1. The resolution of the depth may be lower than that of the associated 2D image. 2. It can be highly compressed. 3. 2D compatibility is maintained. 4. Real time generation of stereo, or multiple stereo pairs, is possible. The main disadvantage has been the laborious nature of the manual conversion techniques used to create depth maps from existing 2D images, which results in a slow and costly process. An alternative, highly productive technique has been developed based upon the use of Machine Leaning Algorithm (MLAs). This paper describes the application of MLAs to the generation of depth maps and presents the results of the commercial application of this approach.

Gradient-Type Magnetoelectric Current Sensor with Strong Multisource Noise Suppression.

PubMed

Zhang, Mingji; Or, Siu Wing

2018-02-14

A novel gradient-type magnetoelectric (ME) current sensor operating in magnetic field gradient (MFG) detection and conversion mode is developed based on a pair of ME composites that have a back-to-back capacitor configuration under a baseline separation and a magnetic biasing in an electrically-shielded and mechanically-enclosed housing. The physics behind the current sensing process is the product effect of the current-induced MFG effect associated with vortex magnetic fields of current-carrying cables (i.e., MFG detection) and the MFG-induced ME effect in the ME composite pair (i.e., MFG conversion). The sensor output voltage is directly obtained from the gradient ME voltage of the ME composite pair and is calibrated against cable current to give the current sensitivity. The current sensing performance of the sensor is evaluated, both theoretically and experimentally, under multisource noises of electric fields, magnetic fields, vibrations, and thermals. The sensor combines the merits of small nonlinearity in the current-induced MFG effect with those of high sensitivity and high common-mode noise rejection rate in the MFG-induced ME effect to achieve a high current sensitivity of 0.65-12.55 mV/A in the frequency range of 10 Hz-170 kHz, a small input-output nonlinearity of <500 ppm, a small thermal drift of <0.2%/℃ in the current range of 0-20 A, and a high common-mode noise rejection rate of 17-28 dB from multisource noises.

Gradient-Type Magnetoelectric Current Sensor with Strong Multisource Noise Suppression

PubMed Central

2018-01-01

A novel gradient-type magnetoelectric (ME) current sensor operating in magnetic field gradient (MFG) detection and conversion mode is developed based on a pair of ME composites that have a back-to-back capacitor configuration under a baseline separation and a magnetic biasing in an electrically-shielded and mechanically-enclosed housing. The physics behind the current sensing process is the product effect of the current-induced MFG effect associated with vortex magnetic fields of current-carrying cables (i.e., MFG detection) and the MFG-induced ME effect in the ME composite pair (i.e., MFG conversion). The sensor output voltage is directly obtained from the gradient ME voltage of the ME composite pair and is calibrated against cable current to give the current sensitivity. The current sensing performance of the sensor is evaluated, both theoretically and experimentally, under multisource noises of electric fields, magnetic fields, vibrations, and thermals. The sensor combines the merits of small nonlinearity in the current-induced MFG effect with those of high sensitivity and high common-mode noise rejection rate in the MFG-induced ME effect to achieve a high current sensitivity of 0.65–12.55 mV/A in the frequency range of 10 Hz–170 kHz, a small input-output nonlinearity of <500 ppm, a small thermal drift of <0.2%/℃ in the current range of 0–20 A, and a high common-mode noise rejection rate of 17–28 dB from multisource noises. PMID:29443920

Apparatus and methods for direct conversion of gaseous hydrocarbons to liquids

DOEpatents

Kong, Peter C.; Lessing, Paul A.

2006-04-25

A chemical reactor for direct conversion of hydrocarbons includes a dielectric barrier discharge plasma cell and a solid oxide electrochemical cell in fluid communication therewith. The discharge plasma cell comprises a pair of electrodes separated by a dielectric material and passageway therebetween. The electrochemical cell comprises a mixed-conducting solid oxide electrolyte membrane tube positioned between a porous cathode and a porous anode, and a gas inlet tube for feeding oxygen containing gas to the porous cathode. An inlet is provided for feeding hydrocarbons to the passageway of the discharge plasma cell, and an outlet is provided for discharging reaction products from the reactor. A packed bed catalyst may optionally be used in the reactor to increase efficiency of conversion. The reactor can be modified to allow use of a light source for directing ultraviolet light into the discharge plasma cell and the electrochemical cell.

Movement Coordination during Conversation

PubMed Central

Latif, Nida; Barbosa, Adriano V.; Vatiokiotis-Bateson, Eric; Castelhano, Monica S.; Munhall, K. G.

2014-01-01

Behavioral coordination and synchrony contribute to a common biological mechanism that maintains communication, cooperation and bonding within many social species, such as primates and birds. Similarly, human language and social systems may also be attuned to coordination to facilitate communication and the formation of relationships. Gross similarities in movement patterns and convergence in the acoustic properties of speech have already been demonstrated between interacting individuals. In the present studies, we investigated how coordinated movements contribute to observers’ perception of affiliation (friends vs. strangers) between two conversing individuals. We used novel computational methods to quantify motor coordination and demonstrated that individuals familiar with each other coordinated their movements more frequently. Observers used coordination to judge affiliation between conversing pairs but only when the perceptual stimuli were restricted to head and face regions. These results suggest that observed movement coordination in humans might contribute to perceptual decisions based on availability of information to perceivers. PMID:25119189

Method for direct conversion of gaseous hydrocarbons to liquids

DOEpatents

Kong, Peter C.; Lessing, Paul A.

2006-03-07

A chemical reactor for direct conversion of hydrocarbons includes a dielectric barrier discharge plasma cell and a solid oxide electrochemical cell in fluid communication therewith. The discharge plasma cell comprises a pair of electrodes separated by a dielectric material and passageway therebetween. The electrochemical cell comprises a mixed-conducting solid oxide electrolyte membrane tube positioned between a porous cathode and a porous anode, and a gas inlet tube for feeding oxygen containing gas to the porous cathode. An inlet is provided for feeding hydrocarbons to the passageway of the discharge plasma cell, and an outlet is provided for discharging reaction products from the reactor. A packed bed catalyst may optionally be used in the reactor to increase efficiency of conversion. The reactor can be modified to allow use of a light source for directing ultraviolet light into the discharge plasma cell and the electrochemical cell.

High-fidelity entanglement swapping and generation of three-qubit GHZ state using asynchronous telecom photon pair sources.

PubMed

Tsujimoto, Yoshiaki; Tanaka, Motoki; Iwasaki, Nobuo; Ikuta, Rikizo; Miki, Shigehito; Yamashita, Taro; Terai, Hirotaka; Yamamoto, Takashi; Koashi, Masato; Imoto, Nobuyuki

2018-01-23

We experimentally demonstrate a high-fidelity entanglement swapping and a generation of the Greenberger-Horne-Zeilinger (GHZ) state using polarization-entangled photon pairs at telecommunication wavelength produced by spontaneous parametric down conversion with continuous-wave pump light. While spatially separated sources asynchronously emit photon pairs, the time-resolved photon detection guarantees the temporal indistinguishability of photons without active timing synchronizations of pump lasers and/or adjustment of optical paths. In the experiment, photons are sufficiently narrowed by fiber-based Bragg gratings with the central wavelengths of 1541 nm & 1580 nm, and detected by superconducting nanowire single-photon detectors with low timing jitters. The observed fidelities of the final states for entanglement swapping and the generated three-qubit state were 0.84 ± 0.04 and 0.70 ± 0.05, respectively.

Generalized quantum interference of correlated photon pairs.

PubMed

Kim, Heonoh; Lee, Sang Min; Moon, Han Seb

2015-05-07

Superposition and indistinguishablility between probability amplitudes have played an essential role in observing quantum interference effects of correlated photons. The Hong-Ou-Mandel interference and interferences of the path-entangled photon number state are of special interest in the field of quantum information technologies. However, a fully generalized two-photon quantum interferometric scheme accounting for the Hong-Ou-Mandel scheme and path-entangled photon number states has not yet been proposed. Here we report the experimental demonstrations of the generalized two-photon interferometry with both the interferometric properties of the Hong-Ou-Mandel effect and the fully unfolded version of the path-entangled photon number state using photon-pair sources, which are independently generated by spontaneous parametric down-conversion. Our experimental scheme explains two-photon interference fringes revealing single- and two-photon coherence properties in a single interferometer setup. Using the proposed interferometric measurement, it is possible to directly estimate the joint spectral intensity of a photon pair source.

Multiplying and detecting propagating microwave photons using inelastic Cooper-pair tunneling

NASA Astrophysics Data System (ADS)

Leppäkangas, Juha; Marthaler, Michael; Hazra, Dibyendu; Jebari, Salha; Albert, Romain; Blanchet, Florian; Johansson, Göran; Hofheinz, Max

2018-01-01

The interaction between propagating microwave fields and Cooper-pair tunneling across a DC-voltage-biased Josephson junction can be highly nonlinear. We show theoretically that this nonlinearity can be used to convert an incoming single microwave photon into an outgoing n -photon Fock state in a different mode. In this process, the electrostatic energy released in a Cooper-pair tunneling event is transferred to the outgoing Fock state, providing energy gain. The created multiphoton Fock state is frequency entangled and highly bunched. The conversion can be made reflectionless (impedance matched) so that all incoming photons are converted to n -photon states. With realistic parameters, multiplication ratios n >2 can be reached. By two consecutive multiplications, the outgoing Fock-state number can get sufficiently large to accurately discriminate it from vacuum with linear postamplification and power measurement. Therefore, this amplification scheme can be used as a single-photon detector without dead time.

Improved gastrointestinal symptom burden after conversion from mycophenolate mofetil to enteric-coated mycophenolate sodium in kidney transplanted children.

PubMed

Pape, Lars; Ahlenstiel, Thurid; Kreuzer, Martin; Ehrich, Jochen H H

2008-09-01

It has been shown in adult kidney transplant recipients that a conversion from MMF to EC-MPS significantly reduced the GI related symptom burden. No such study exists on children with GI problems while receiving MMF therapy. Ten paediatric kidney transplant recipients (mean age 14.5 yr, s.d. 4.5) receiving triple immunosuppression (Cyclosporin A or Tacrolimus + MMF + Prednisolone) with severe GI symptoms were converted to an equimolar dose of EC-MPS. The GSRS was completed before and at four wk after the switch, and GFR was determined for a mean period of six months. Values were compared by the paired t-test. Mean GSRS improved significantly after the switch to EC-MPS in all but one patient, from 2.1 (s.d. 0.9) to 1.1 (s.d. 0.6). The differences could be found in all four subscales. Graft function did not change after conversion to EC-MPS. In children with moderate or severe GI symptoms while receiving MMF, conversion to EC-MPS led to significantly reduced GI symptoms.

Investigation of thermodynamic parameters in the pyrolysis conversion of biomass and manure to biochars using thermogravimetric analysis.

PubMed

Xu, Yiliang; Chen, Baoliang

2013-10-01

The thermodynamic parameters of the conversion of two companion pair materials, i.e., rice straw vs dairy manure, and rice bran vs chicken manure, to biochars were characterized by thermogravimetric analysis. The overall changes of activation energy (Ea) were well described by the Flynn-Wall method. The Ea values increased steeply from about 120 to 180 kJ/mol at the mass conversion (α) at 0.2-0.4, followed by a relatively steady change at 0.4<α<0.65, thereafter showed a quick increase at α>0.65. The higher contents of minerals in manures resulted in the larger Ea. The individual conversion of hemicellulose, cellulose and lignin in the feedstocks was identified and their thermodynamic parameters (ΔH°, ΔG° and ΔS°) were calculated. The yields of biochars calculated from TG curve were compared with the determined yields of biochars using muffle pyrolysis. Along with Fourier transform infrared spectra data, the distinct decompositions of biomasses and manures were evaluated. Copyright © 2013 Elsevier Ltd. All rights reserved.

Double-use linear polarization convertor using hybrid metamaterial based on VO2 phase transition in the terahertz region

NASA Astrophysics Data System (ADS)

Zou, Huanling; Xiao, Zhongyin; Li, Wei; Li, Chuan

2018-04-01

A number of polarization convertors based on metamaterials(MMs) have been investigated recently, but no one has proposed a high-efficiency linear polarization transformer both in transmission and reflection modes. Here, a bilayered MM embedded with vanadium dioxide (VO2) composed of a pair of sloping gold patches, bottom hybrid layer and a dielectric spacer is proposed as a double-use linear polarization convertor. It has been demonstrated numerically that this device has advantages of switching between transmission polarization conversion and reflection polarization conversion based on the phase transition of the VO2 film in the terahertz (THz) regime and the polarization conversion ratios (PCR) in both cases are higher than 90% in wide bands. The simulated linear polarization transmission/reflection coefficients and the surface current distributions give insight into the mechanism of the linear polarization conversions. Moreover, the physical mechanism of polarization sensitivity of the designed structure is investigated by the distributions of electric field. The proposed double-use linear polarization convertor shows great prospects in polarization imaging, and polarized light communications.

Carbon aerogel electrodes for direct energy conversion

DOEpatents

Mayer, S.T.; Kaschmitter, J.L.; Pekala, R.W.

1997-02-11

A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes is described, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome. 1 fig.

Realization of the purely spatial Einstein-Podolsky-Rosen paradox in full-field images of spontaneous parametric down-conversion

NASA Astrophysics Data System (ADS)

Moreau, Paul-Antoine; Mougin-Sisini, Joé; Devaux, Fabrice; Lantz, Eric

2012-07-01

We demonstrate Einstein-Podolsky-Rosen (EPR) entanglement by detecting purely spatial quantum correlations in the near and far fields of spontaneous parametric down-conversion generated in a type-2 beta barium borate crystal. Full-field imaging is performed in the photon-counting regime with an electron-multiplying CCD camera. The data are used without any postselection, and we obtain a violation of Heisenberg inequalities with inferred quantities taking into account all the biphoton pairs in both the near and far fields by integration on the entire two-dimensional transverse planes. This ensures a rigorous demonstration of the EPR paradox in its original position-momentum form.

Relations of Parent-Youth Interactive Exchanges to Adolescent Socioemotional Development

PubMed Central

Hutt, Rachel L.; Wang, Qi; Evans, Gary W.

2013-01-01

This study examined the relations of parent-youth agreement and disagreement during a joint problem-solving task and multi-methodological indices of socioemotional outcomes in adolescents (Mean age = 13). One hundred and sixty seven parents and their adolescent children participated. Each parent-youth pair played the interactive game Jenga, and their interactions were analyzed for frequency of elaborations (agreement during three or more conversational turns) and negotiations (disagreement during three or more conversational turns). Elaborations during parent-youth interactions were related to less negative classroom behavior, better self-regulation, and more task persistence in youth. Findings are discussed in light of the importance of parent-youth interaction and youth autonomy in adolescent socioemotional development. PMID:24031158

Hydrogenation of carboxylic acids with a homogeneous cobalt catalyst.

PubMed

Korstanje, Ties J; van der Vlugt, Jarl Ivar; Elsevier, Cornelis J; de Bruin, Bas

2015-10-16

The reduction of esters and carboxylic acids to alcohols is a highly relevant conversion for the pharmaceutical and fine-chemical industries and for biomass conversion. It is commonly performed using stoichiometric reagents, and the catalytic hydrogenation of the acids previously required precious metals. Here we report the homogeneously catalyzed hydrogenation of carboxylic acids to alcohols using earth-abundant cobalt. This system, which pairs Co(BF4)2·6H2O with a tridentate phosphine ligand, can reduce a wide range of esters and carboxylic acids under relatively mild conditions (100°C, 80 bar H2) and reaches turnover numbers of up to 8000. Copyright © 2015, American Association for the Advancement of Science.

Peer-Peer Interaction in a Speaking Test: The Case of the "First Certificate in English" Examination

ERIC Educational Resources Information Center

Galaczi, Evelina D.

2008-01-01

This discourse-based study turns its attention to paired test-taker discourse in the First Certificate in English speaking test. Its primary aim is to focus on fundamental conversation management concepts, such as overall structural organisation, turn-taking, sequencing, and topic organisation found in the dyadic test-taker interaction in 30 pairs…

Classroom Use of Multimedia-Supported Predict--Observe--Explain Tasks in a Social Constructivist Learning Environment

ERIC Educational Resources Information Center

Kearney, Matthew

2004-01-01

This paper focuses on the use of multimedia-based predict--observe--explain (POE) tasks to facilitate small group learning conversations. Although the tasks were given to pairs of students as a diagnostic tool to elicit their pre-instructional physics conceptions, they also provided a peer learning opportunity for students. The study adopted a…

Violation of continuous-variable Einstein-Podolsky-Rosen steering with discrete measurements.

PubMed

Schneeloch, James; Dixon, P Ben; Howland, Gregory A; Broadbent, Curtis J; Howell, John C

2013-03-29

In this Letter, we derive an entropic Einstein-Podolsky-Rosen (EPR) steering inequality for continuous-variable systems using only experimentally measured discrete probability distributions and details of the measurement apparatus. We use this inequality to witness EPR steering between the positions and momenta of photon pairs generated in spontaneous parametric down-conversion. We examine the asymmetry between parties in this inequality, and show that this asymmetry can be used to reduce the technical requirements of experimental setups intended to demonstrate the EPR paradox. Furthermore, we develop a more stringent steering inequality that is symmetric between parties, and use it to show that the down-converted photon pairs also exhibit symmetric EPR steering.

Violation of Continuous-Variable Einstein-Podolsky-Rosen Steering with Discrete Measurements

NASA Astrophysics Data System (ADS)

Schneeloch, James; Dixon, P. Ben; Howland, Gregory A.; Broadbent, Curtis J.; Howell, John C.

2013-03-01

In this Letter, we derive an entropic Einstein-Podolsky-Rosen (EPR) steering inequality for continuous-variable systems using only experimentally measured discrete probability distributions and details of the measurement apparatus. We use this inequality to witness EPR steering between the positions and momenta of photon pairs generated in spontaneous parametric down-conversion. We examine the asymmetry between parties in this inequality, and show that this asymmetry can be used to reduce the technical requirements of experimental setups intended to demonstrate the EPR paradox. Furthermore, we develop a more stringent steering inequality that is symmetric between parties, and use it to show that the down-converted photon pairs also exhibit symmetric EPR steering.

Search for a massive short-lived axion in nuclear transitions

NASA Astrophysics Data System (ADS)

Hatzikoutelis, Athanasios

Recent reports of the possible existence of an Axion with mass = 9.5 MeV and lifetime less than 10-14 sec do not contradict any negative results of the 20-year long search. The present work aims at confirming or disproving these reports. An Axion may compete with M1 nuclear transitions and decay into a e+-e- pair, producing events with high angle separation, thus being detectable in the presence of internal pair conversion which favors small separation angles. In the present experiment the M1 transitions from two discrete states in 12C were produced using a (d,n) reaction. A hermetic array of plastic scintillator detectors for e+-e- pairs from nuclear transitions was upgraded to 65 elements covering 50% of 4pi. A target chamber made of carbon fiber/epoxy resin, with wall thickness 0.8 mm, was introduced which absorbs only 172. 2 keV of the kinetic energy of minimum ionizing e+/e-. A neutron detector with total efficiency of 3% was constructed to measure the time of flight of neutrons. The detectors and chamber were installed on the beam line of the Stony Brook heavy ion LINAC. A test run was conducted using the reaction 11B(p,e+e-)12C (Ep = 7.2 MeV) to populate the Giant Dipole Resonance of 12C. The observation of the IPC from the 22.6-MeV E1 transition to the ground state of 12C established the pair-energy line-shape and produced an absolute pairenergy calibration. The angular correlation distribution of the pairs was found to be in agreement with the Born and point nucleus approximation of E1 angular correlations. A data run with the stripping reaction 11B(d,n)12C* (Ed = 7.2 MeV) populated the (Ipi,T) = (1+,1) 15.11-MeV and the (1 +,0) 12.7-MeV states of 12C. Detected pair events without neutron coincidence required showed a clear and strong peak of the 15.11 MeV to ground state transition. Analysis of these data agreed with angular correlations of M1 internal pair conversion. These did not support the earlier work and showed no evidence of an Axion emitted in the transition. A second test with neutron coincidence required, demonstrated that the full experiment is working as designed. However, for the kinematically complete experiment including neutron coincidence the rate of good events was found to be only 4--6 events/hr. A statistically decisive test will take data runs of about six months.

Bisphenol A release from an orthodontic adhesive and its correlation with the degree of conversion on varying light-curing tip distances.

PubMed

Sunitha, Catherine; Kailasam, Vignesh; Padmanabhan, Sridevi; Chitharanjan, Arun B

2011-08-01

The aims of this research were to use high-performance liquid chromatography to assess the bisphenol A (BPA) released from an orthodontic adhesive (Transbond XT; 3M Unitek, Monrovia, Calif) with various light-curing tip distances and to correlate the release to the degree of conversion. One hundred thirty-eight premolar brackets were divided into 3 groups of 40 each for the high-performance liquid chromatography analysis and 3 groups of 6 each for assessing the degree of conversion. Fourier transform infrared spectroscopy was used for this purpose. Each group was studied at light-curing tip distances of 0, 5, and 10 mm. Statistical analyses were performed by using 2-way analysis of variance (ANOVA), post-hoc multiple comparisons Tukey HSD tests, and paired t tests. Pearson correlation was used to assess the correlation between the degree of conversion and BPA release. BPA release was greater in specimens cured with a greater light-curing tip distance. The degree of conversion decreased with increased light-curing tip distances. A negative correlation was found between BPA release and degree of conversion. Clinicians should ensure that the adhesive is completely cured by keeping the light-curing tip as close to the adhesive as clinically possible. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Biomass for thermochemical conversion: targets and challenges

PubMed Central

Tanger, Paul; Field, John L.; Jahn, Courtney E.; DeFoort, Morgan W.; Leach, Jan E.

2013-01-01

Bioenergy will be one component of a suite of alternatives to fossil fuels. Effective conversion of biomass to energy will require the careful pairing of advanced conversion technologies with biomass feedstocks optimized for the purpose. Lignocellulosic biomass can be converted to useful energy products via two distinct pathways: enzymatic or thermochemical conversion. The thermochemical pathways are reviewed and potential biotechnology or breeding targets to improve feedstocks for pyrolysis, gasification, and combustion are identified. Biomass traits influencing the effectiveness of the thermochemical process (cell wall composition, mineral and moisture content) differ from those important for enzymatic conversion and so properties are discussed in the language of biologists (biochemical analysis) as well as that of engineers (proximate and ultimate analysis). We discuss the genetic control, potential environmental influence, and consequences of modification of these traits. Improving feedstocks for thermochemical conversion can be accomplished by the optimization of lignin levels, and the reduction of ash and moisture content. We suggest that ultimate analysis and associated properties such as H:C, O:C, and heating value might be more amenable than traditional biochemical analysis to the high-throughput necessary for the phenotyping of large plant populations. Expanding our knowledge of these biomass traits will play a critical role in the utilization of biomass for energy production globally, and add to our understanding of how plants tailor their composition with their environment. PMID:23847629

Performance measurement of HARPO: A time projection chamber as a gamma-ray telescope and polarimeter

NASA Astrophysics Data System (ADS)

Gros, P.; Amano, S.; Attié, D.; Baron, P.; Baudin, D.; Bernard, D.; Bruel, P.; Calvet, D.; Colas, P.; Daté, S.; Delbart, A.; Frotin, M.; Geerebaert, Y.; Giebels, B.; Götz, D.; Hashimoto, S.; Horan, D.; Kotaka, T.; Louzir, M.; Magniette, F.; Minamiyama, Y.; Miyamoto, S.; Ohkuma, H.; Poilleux, P.; Semeniouk, I.; Sizun, P.; Takemoto, A.; Yamaguchi, M.; Yonamine, R.; Wang, S.

2018-01-01

We analyse the performance of a gas time projection chamber (TPC) as a high-performance gamma-ray telescope and polarimeter in the e+e- pair-creation regime. We use data collected at a gamma-ray beam of known polarisation. The TPC provides two orthogonal projections (x, z) and (y, z) of the tracks induced by each conversion in the gas volume. We use a simple vertex finder in which vertices and pseudo-tracks exiting from them are identified. We study the various contributions to the single-photon angular resolution using Monte Carlo simulations, compare them with the experimental data and find that they are in excellent agreement. The distribution of the azimuthal angle of pair conversions shows a bias due to the non-cylindrical-symmetric structure of the detector. This bias would average out for a long duration exposure on a space mission, but for this pencil-beam characterisation we have ensured its accurate simulation by a double systematics-control scheme, data taking with the detector rotated at several angles with respect to the beam polarisation direction and systematics control with a non-polarised beam. We measure, for the first time, the polarisation asymmetry of a linearly polarised gamma-ray beam in the low energy pair-creation regime. This sub-GeV energy range is critical for cosmic sources as their spectra are power laws which fall quickly as a function of increasing energy. This work could pave the way to extending polarised gamma-ray astronomy beyond the MeV energy regime.

Efficient 525 nm laser generation in single or double resonant cavity

NASA Astrophysics Data System (ADS)

Liu, Shilong; Han, Zhenhai; Liu, Shikai; Li, Yinhai; Zhou, Zhiyuan; Shi, Baosen

2018-03-01

This paper reports the results of a study into highly efficient sum frequency generation from 792 and 1556 nm wavelength light to 525 nm wavelength light using either a single or double resonant ring cavity based on a periodically poled potassium titanyl phosphate crystal (PPKTP). By optimizing the cavity's parameters, the maximum power achieved for the resultant 525 nm laser was 263 and 373 mW for the single and double resonant cavity, respectively. The corresponding quantum conversion efficiencies were 8 and 77% for converting 1556 nm photons to 525 nm photons with the single and double resonant cavity, respectively. The measured intra-cavity single pass conversion efficiency for both configurations was about 5%. The performances of the sum frequency generation in these two configurations was studied and compared in detail. This work will provide guidelines for optimizing the generation of sum frequency generated laser light for a variety of configurations. The high conversion efficiency achieved in this work will help pave the way for frequency up-conversion of non-classical quantum states, such as the squeezed vacuum and single photon states. The proposed green laser source will be used in our future experiments, which includes a plan to generate two-color entangled photon pairs and achieve the frequency down-conversion of single photons carrying orbital angular momentum.

Vitamin C supplementation improve the sputum conversion culture rate in pulmonary tuberculosis treatment while rifampicin susceptible

NASA Astrophysics Data System (ADS)

Susanto, L.; Siregar, Y.; Kusumawati, L.

2018-03-01

The failure of first-line tuberculosis treatment greatly affects multiple drug-resistant tuberculosis. In vitro study of vitamin C induces the death of M. tuberculosis bacteria and accelerates healing of tuberculosis, so the multiple drug-resistant tuberculosis can be avoided. This research aimed to identify the effect of vitamin C as a supportive treatment on the sputum conversion rate. The randomizedand double group with a parallel design by matching pair method was used to collect samples. The first group was treated with standard tuberculosis treatment, and the other was given vitamin C supplementation. Vitamin C plasma level analyzation was performed before and after two months of treatment. Sputum conversion was evaluated every week for eight weeks. The comparison of vitamin C plasma level in pre and post-treatment group was significant (p=0.03) but not in the other group. There was no significant difference in vitamin C plasma level between two groups (p=0.21). The proportion of sputum conversion rate in both group in the first week was 0% vs. 9.6% (p=0.83) and the last week of study was 83.9% vs. 100% (p=0.02). In conclusion, vitamin C supplementation has effects in improving the healing process of tuberculosis patients as indicated by higher in sputum conversion rate.

What are Middle School Students Talking About During Clicker Questions? Characterizing Small-Group Conversations Mediated by Classroom Response Systems

NASA Astrophysics Data System (ADS)

Barth-Cohen, Lauren A.; Smith, Michelle K.; Capps, Daniel K.; Lewin, Justin D.; Shemwell, Jonathan T.; Stetzer, MacKenzie R.

2016-02-01

There is a growing interest in using classroom response systems or clickers in science classrooms at both the university and K-12 levels. Typically, when instructors use this technology, students are asked to answer and discuss clicker questions with their peers. The existing literature on using clickers at the K-12 level has largely focused on the efficacy of clicker implementation, with few studies investigating collaboration and discourse among students. To expand on this work, we investigated the question: Does clicker use promote productive peer discussion among middle school science students? Specifically, we collected data from middle school students in a physical science course. Students were asked to answer a clicker question individually, discuss the question with their peers, answer the same question again, and then subsequently answer a new matched-pair question individually. We audio recorded the peer conversations to characterize the nature of the student discourse. To analyze these conversations, we used a grounded analysis approach and drew on literature about collaborative knowledge co-construction. The analysis of the conversations revealed that middle school students talked about science content and collaboratively discussed ideas. Furthermore, the majority of conversations, both ones that positively and negatively impacted student performance, contained evidence of collaborative knowledge co-construction.

Bisulfite Conversion of DNA: Performance Comparison of Different Kits and Methylation Quantitation of Epigenetic Biomarkers that Have the Potential to Be Used in Non-Invasive Prenatal Testing

PubMed Central

Leontiou, Chrysanthia A.; Hadjidaniel, Michael D.; Mina, Petros; Antoniou, Pavlos; Ioannides, Marios; Patsalis, Philippos C.

2015-01-01

Introduction Epigenetic alterations, including DNA methylation, play an important role in the regulation of gene expression. Several methods exist for evaluating DNA methylation, but bisulfite sequencing remains the gold standard by which base-pair resolution of CpG methylation is achieved. The challenge of the method is that the desired outcome (conversion of unmethylated cytosines) positively correlates with the undesired side effects (DNA degradation and inappropriate conversion), thus several commercial kits try to adjust a balance between the two. The aim of this study was to compare the performance of four bisulfite conversion kits [Premium Bisulfite kit (Diagenode), EpiTect Bisulfite kit (Qiagen), MethylEdge Bisulfite Conversion System (Promega) and BisulFlash DNA Modification kit (Epigentek)] regarding conversion efficiency, DNA degradation and conversion specificity. Methods Performance was tested by combining fully methylated and fully unmethylated λ-DNA controls in a series of spikes by means of Sanger sequencing (0%, 25%, 50% and 100% methylated spikes) and Next-Generation Sequencing (0%, 3%, 5%, 7%, 10%, 25%, 50% and 100% methylated spikes). We also studied the methylation status of two of our previously published differentially methylated regions (DMRs) at base resolution by using spikes of chorionic villus sample in whole blood. Results The kits studied showed different but comparable results regarding DNA degradation, conversion efficiency and conversion specificity. However, the best performance was observed with the MethylEdge Bisulfite Conversion System (Promega) followed by the Premium Bisulfite kit (Diagenode). The DMRs, EP6 and EP10, were confirmed to be hypermethylated in the CVS and hypomethylated in whole blood. Conclusion Our findings indicate that the MethylEdge Bisulfite Conversion System (Promega) was shown to have the best performance among the kits. In addition, the methylation level of two of our DMRs, EP6 and EP10, was confirmed. Finally, we showed that bisulfite amplicon sequencing is a suitable approach for methylation analysis of targeted regions. PMID:26247357

Bisulfite Conversion of DNA: Performance Comparison of Different Kits and Methylation Quantitation of Epigenetic Biomarkers that Have the Potential to Be Used in Non-Invasive Prenatal Testing.

PubMed

Leontiou, Chrysanthia A; Hadjidaniel, Michael D; Mina, Petros; Antoniou, Pavlos; Ioannides, Marios; Patsalis, Philippos C

2015-01-01

Epigenetic alterations, including DNA methylation, play an important role in the regulation of gene expression. Several methods exist for evaluating DNA methylation, but bisulfite sequencing remains the gold standard by which base-pair resolution of CpG methylation is achieved. The challenge of the method is that the desired outcome (conversion of unmethylated cytosines) positively correlates with the undesired side effects (DNA degradation and inappropriate conversion), thus several commercial kits try to adjust a balance between the two. The aim of this study was to compare the performance of four bisulfite conversion kits [Premium Bisulfite kit (Diagenode), EpiTect Bisulfite kit (Qiagen), MethylEdge Bisulfite Conversion System (Promega) and BisulFlash DNA Modification kit (Epigentek)] regarding conversion efficiency, DNA degradation and conversion specificity. Performance was tested by combining fully methylated and fully unmethylated λ-DNA controls in a series of spikes by means of Sanger sequencing (0%, 25%, 50% and 100% methylated spikes) and Next-Generation Sequencing (0%, 3%, 5%, 7%, 10%, 25%, 50% and 100% methylated spikes). We also studied the methylation status of two of our previously published differentially methylated regions (DMRs) at base resolution by using spikes of chorionic villus sample in whole blood. The kits studied showed different but comparable results regarding DNA degradation, conversion efficiency and conversion specificity. However, the best performance was observed with the MethylEdge Bisulfite Conversion System (Promega) followed by the Premium Bisulfite kit (Diagenode). The DMRs, EP6 and EP10, were confirmed to be hypermethylated in the CVS and hypomethylated in whole blood. Our findings indicate that the MethylEdge Bisulfite Conversion System (Promega) was shown to have the best performance among the kits. In addition, the methylation level of two of our DMRs, EP6 and EP10, was confirmed. Finally, we showed that bisulfite amplicon sequencing is a suitable approach for methylation analysis of targeted regions.

Development of a Beam Trajectory Monitoring System Using e+/e- Pair Production Events

NASA Astrophysics Data System (ADS)

Kimura, Shota; Emoto, Yusaku; Fujihara, Kento; Ito, Hiroshi; Kawai, Hideyuki; Kobayashi, Atsushi; Mizuno, Takahiro

2018-01-01

In particle therapy, it is important to monitor the Bragg-peak position. It was simulated by GEANT4 Monte Carlo Simulation Code that the distribution of secondary generated gamma rays on the carbon beam therapy and the proton beam therapy. This simulation shows that gamma rays whose energy is 10 MeV or more are intensively generated at the Bragg-peak position. We are developing the system to monitor the Bragg-peak position which can measure pair production events occurred in the detector by gamma rays from irradiation points. The momentum direction of the gamma ray can be determined by measuring passing points and energy of e+ and e- generated by pair production. This system has 5 parts. The first is the conversion part. This part consists of several layers. Each layer is composed of a La-GPS ((Gd0.75La0.24Ce0.01)2Si2O7) scintillator plate and wavelength-shifting fibre (WLSF) sheets. The scintillator plate is sandwiched between sheets, where the directions of the sheets are in orthogonally x and y directions. In this part, gamma rays are converted to e+ e- pairs and the position where the conversion occured is determined. The second is the tracking part. This part consists of 2 layers of scintillating fibre tracker. Each layer has 6 scintillating fibre sheets for x, x', u, u', v, and v'. The third is the energy measurement part. It measures the energy of e+ and e- by scintillator array and Silicon Photomultipliers. The fourth is the veto counter for bremsstrahlung gamma rays from e+ and e-. The fifth is the beam monitor. By experiment, the number of photoelectrons of La-GPS with a WLSF (B-3(300)MJ, Kuraray) sheet and scintillating fibre (SCSF-78, Kuraray) when charged particle passed was measured as 9.7 and 7.6 respectively.

Simulation of ultra-high energy photon propagation with PRESHOWER 2.0

NASA Astrophysics Data System (ADS)

Homola, P.; Engel, R.; Pysz, A.; Wilczyński, H.

2013-05-01

In this paper we describe a new release of the PRESHOWER program, a tool for Monte Carlo simulation of propagation of ultra-high energy photons in the magnetic field of the Earth. The PRESHOWER program is designed to calculate magnetic pair production and bremsstrahlung and should be used together with other programs to simulate extensive air showers induced by photons. The main new features of the PRESHOWER code include a much faster algorithm applied in the procedures of simulating the processes of gamma conversion and bremsstrahlung, update of the geomagnetic field model, and a minor correction. The new simulation procedure increases the flexibility of the code so that it can also be applied to other magnetic field configurations such as, for example, encountered in the vicinity of the sun or neutron stars. Program summaryProgram title: PRESHOWER 2.0 Catalog identifier: ADWG_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWG_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3968 No. of bytes in distributed program, including test data, etc.: 37198 Distribution format: tar.gz Programming language: C, FORTRAN 77. Computer: Intel-Pentium based PC. Operating system: Linux or Unix. RAM:< 100 kB Classification: 1.1. Does the new version supercede the previous version?: Yes Catalog identifier of previous version: ADWG_v1_0 Journal reference of previous version: Comput. Phys. Comm. 173 (2005) 71 Nature of problem: Simulation of a cascade of particles initiated by UHE photon in magnetic field. Solution method: The primary photon is tracked until its conversion into an e+ e- pair. If conversion occurs each individual particle in the resultant preshower is checked for either bremsstrahlung radiation (electrons) or secondary gamma conversion (photons). Reasons for new version: Slow and outdated algorithm in the old version (a significant speed up is possible); Extension of the program to allow simulations also for extraterrestrial magnetic field configurations (e.g. neutron stars) and very long path lengths. Summary of revisions: A veto algorithm was introduced in the gamma conversion and bremsstrahlung tracking procedures. The length of the tracking step is now variable along the track and depends on the probability of the process expected to occur. The new algorithm reduces significantly the number of tracking steps and speeds up the execution of the program. The geomagnetic field model has been updated to IGRF-11, allowing for interpolations up to the year 2015. Numerical Recipes procedures to calculate modified Bessel functions have been replaced with an open source CERN routine DBSKA. One minor bug has been fixed. Restrictions: Gamma conversion into particles other than an electron pair is not considered. Spatial structure of the cascade is neglected. Additional comments: The following routines are supplied in the package, IGRF [1, 2], DBSKA [3], ran2 [4] Running time: 100 preshower events with primary energy 1020 eV require a 2.66 GHz CPU time of about 200 sec.; at the energy of 1021 eV, 600 sec.

Morphology evolution in high-performance polymer solar cells processed from nonhalogenated solvent

DOE PAGES

Cai, Wanzhu; Liu, Peng; Jin, Yaocheng; ...

2015-05-26

A new processing protocol based on non-halogenated solvent and additive is developed to produce polymer solar cells with power conversion efficiencies better than those processed from commonly used halogenated solvent-additive pair. Morphology studies show that good performance correlates with a finely distributed nanomorphology with a well-defined polymer fibril network structure, which leads to balanced charge transport in device operation.

Nesting pair density and abundance of ferruginous hawks (Buteo regalis) and golden eagles (Aquila chrysaetos) from aerial surveys in Wyoming

Treesearch

Lucretia E. Olson; Robert J. Oakleaf; John R. Squires; Zachary P. Wallace; Patricia L. Kennedy

2015-01-01

Raptors that inhabit sagebrush steppe and grassland ecosystems in the western United States may be threatened by continued loss and modification of their habitat due to energy development, conversion to agriculture, and human encroachment. Actions to protect these species are hampered by a lack of reliable data on such basic information as population size and...

Distillation of the two-mode squeezed state.

PubMed

Kurochkin, Yury; Prasad, Adarsh S; Lvovsky, A I

2014-02-21

We experimentally demonstrate entanglement distillation of the two-mode squeezed state obtained by parametric down-conversion. Applying the photon annihilation operator to both modes, we raise the fraction of the photon-pair component in the state, resulting in the increase of both squeezing and entanglement by about 50%. Because of the low amount of initial squeezing, the distilled state does not experience significant loss of Gaussian character.

Doing Being a Foreign Language Learner in a Classroom: Embodiment of Cognitive States as Social Events

ERIC Educational Resources Information Center

Mori, Junko; Hasegawa, Atsushi

2009-01-01

Encountering trouble producing a word in the midst of a turn at talk is an everyday experience for foreign language learners. By employing conversation analysis (CA) as a central tool for analysis, the current study explores how students undertake a range of word searches while they organize a pair work session designed for the purpose of language…

Experimental generation of complex noisy photonic entanglement

NASA Astrophysics Data System (ADS)

Dobek, K.; Karpiński, M.; Demkowicz-Dobrzański, R.; Banaszek, K.; Horodecki, P.

2013-02-01

We present an experimental scheme based on spontaneous parametric down-conversion to produce multiple-photon pairs in maximally entangled polarization states using an arrangement of two type-I nonlinear crystals. By introducing correlated polarization noise in the paths of the generated photons we prepare mixed-entangled states whose properties illustrate fundamental results obtained recently in quantum information theory, in particular those concerning bound entanglement and privacy.

Improved results of LINE-1 methylation analysis in formalin-fixed, paraffin-embedded tissues with the application of a heating step during the DNA extraction process.

PubMed

Wen, Xianyu; Jeong, Seorin; Kim, Younghoon; Bae, Jeong Mo; Cho, Nam Yun; Kim, Jung Ho; Kang, Gyeong Hoon

2017-01-01

Formalin-fixed, paraffin-embedded (FFPE) tissues are important resources for profiling DNA methylation changes and for studying a variety of diseases. However, formalin fixation introduces inter-strand crosslinking, which might cause incomplete bisulfite conversion of unmethylated cytosines, which might lead to falsely elevated measurements of methylation levels in pyrosequencing assays. Long interspersed nucleotide element-1 (LINE-1) is a major constituent of repetitive transposable DNA elements, and its methylation is referred to correlates with global DNA methylation. To identify whether formalin fixation might impact the measured values of methylation in LINE-1 repetitive elements and whether prolonged heat-induced denaturation of DNA might reduce the artificial increases in measured values caused by formalin fixation, we analyzed paired fresh-frozen (FF) and FFPE xenograft tissue samples for their methylation levels in LINE-1 using a pyrosequencing assay. To further confirm the effect of a heating step in the measurement of LINE-1 or single gene methylation levels, we analyzed FFPE tissue samples of gastric cancer and colorectal cancer for their methylation status in LINE-1 and eight single genes, respectively. Formalin fixation led to an increase in the measured values of LINE-1 methylation regardless of the duration of fixation. Prolonged heating of the DNA at 95 °C for 30 min before bisulfite conversion was found (1) to decrease the discrepancy in the measured values between the paired FF and FFPE tissue samples, (2) to decrease the standard deviation of the measured value of LINE-1 methylation levels in FFPE tissue samples of gastric cancer, and (3) to improve the performance in the measurement of single gene methylation levels in FFPE tissue samples of colorectal cancer. Formalin fixation leads to artificial increases in the measured values of LINE-1 methylation, and the application of prolonged heating of DNA samples decreases the discrepancy in the measured values of LINE-1 methylation between paired FF and FFPE tissue samples. The application of prolonged heating of DNA samples improves bisulfite conversion-based measurement of LINE-1 or single gene methylation levels in FFPE tissue samples.

Has the conversion of natural wetlands to agricultural land increased the incidence and severity of damaging freezes in south Florida?

USGS Publications Warehouse

Marshall, C.H.; Pielke, R.A.; Steyaert, L.T.

2004-01-01

On several occasions, winter freezes have wrought severe destruction on Florida agriculture. A series of devastating freezes around the turn of the twentieth century, and again during the 1980s, were related to anomalies in the large-scale flow of the ocean–atmosphere system. During the twentieth century, substantial areas of wetlands in south Florida were drained and converted to agricultural land for winter fresh vegetable and sugarcane production. During this time, much of the citrus industry also was relocated to those areas to escape the risk of freeze farther to the north. The purpose of this paper is to present a modeling study designed to investigate whether the conversion of the wetlands to agriculture itself could have resulted in or exacerbated the severity of recent freezes in those agricultural areas of south Florida.For three recent freeze events, a pair of simulations was undertaken with the Regional Atmospheric Modeling System. One member of each pair employed land surface properties that represent pre-1900s (near natural) land cover, whereas the other member of each pair employed data that represent near-current land-use patterns as derived from analysis of Landsat data valid for 1992/93. These two different land cover datasets capture well the conversion of wetlands to agriculture in south Florida during the twentieth century. Use of current land surface properties resulted in colder simulated minimum temperatures and temperatures that remained below freezing for a longer period at locations of key agricultural production centers in south Florida that were once natural wetlands. Examination of time series of the surface energy budget from one of the cases reveals that when natural land cover is used, a persistent moisture flux from the underlying wetlands during the nighttime hours served to prevent the development of below-freezing temperatures at those same locations. When the model results were subjected to an important sensitivity factor, the depth of standing water in the wetlands, the outcome remained consistent. These results provide another example of the potential for humans to perturb the climate system in ways that can have severe socioeconomic consequences by altering the land surface alone.

Caught in the Act: How Extraverted and Introverted Friends Communally Cope with Being Recorded.

PubMed

Thorne, Avril; Shapiro, Lauren; Cardilla, Kim; Korobov, Neill; Nelson, Paul A

2009-08-01

This study explored how close friends who were similar or opposite on extraversion communally coped with being put on the spot to produce a recorded conversation. Participants were 50 pairs of same-sex college-age friends (54% female) who explicitly discussed the fact that their conversation was being recorded. The initial 'on-stage' episode emerged consistently earliest for extraverted dyads, and the majority of their episodes quickly diverted the on-stage moment. Dyads that included at least one introvert engaged in more extensive assortments of on-stage maneuvers, including research talk, soothing, and joking. In introvert-extravert dyads the extravert usually initiated and ended these episodes. Implications are discussed for understanding how personality is reciprocally implicated in managing shared everyday problems.

Nurses' fidelity to theory-based core components when implementing Family Health Conversations - a qualitative inquiry.

PubMed

Östlund, Ulrika; Bäckström, Britt; Lindh, Viveca; Sundin, Karin; Saveman, Britt-Inger

2015-09-01

A family systems nursing intervention, Family Health Conversation, has been developed in Sweden by adapting the Calgary Family Assessment and Intervention Models and the Illness Beliefs Model. The intervention has several theoretical assumptions, and one way translate the theory into practice is to identify core components. This may produce higher levels of fidelity to the intervention. Besides information about how to implement an intervention in accordance to how it was developed, evaluating whether it was actually implemented as intended is important. Accordingly, we describe the nurses' fidelity to the identified core components of Family Health Conversation. Six nurses, working in alternating pairs, conducted Family Health Conversations with seven families in which a family member younger than 65 had suffered a stroke. The intervention contained a series of three-1-hour conversations held at 2-3 week intervals. The nurses followed a conversation structure based on 12 core components identified from theoretical assumptions. The transcripts of the 21 conversations were analysed using manifest qualitative content analysis with a deductive approach. The 'core components' seemed to be useful even if nurses' fidelity varied among the core components. Some components were followed relatively well, but others were not. This indicates that the process for achieving fidelity to the intervention can be improved, and that it is necessary for nurses to continually learn theory and to practise family systems nursing. We suggest this can be accomplished through reflections, role play and training on the core components. Furthermore, as in this study, joint reflections on how the core components have been implemented can lead to deeper understanding and knowledge of how Family Health Conversation can be delivered as intended. © 2014 Nordic College of Caring Science.

A 4 π dilepton spectrometer: PEPSI

NASA Astrophysics Data System (ADS)

Buda, A.; Bacelar, J. C. S.; Bałanda, A.; van Klinken, J.; Sujkowski, Z.; van der Woude, A.

1993-11-01

A novel positron-electron pair spectroscopy instrument (PEPSI) was designed to measure transitions in the energy region 10-40 MeV. It consists of Nd 2Fe 14B permanent magnets forming a compact 4 π magnetic filter consisting of 12 positron and 20 electron mini-orange-like spectrometers. The response function of PEPSI has been measured with mono-energetic beams of electrons from 5 to 20 MeV. The PEPSI spectrometer was used for measuring the internal pair conversion coefficient ( απ) of the 15.1 MeV M1 transition from a Jπ = 1 + state to the ground state in 12C. Our experimental value of απ = (3.3 ± 0.5) × 10 -3 is in good agreement with theoretical estimates.

Experimental demonstration of entanglement-enhanced classical communication over a quantum channel with correlated noise.

PubMed

Banaszek, Konrad; Dragan, Andrzej; Wasilewski, Wojciech; Radzewicz, Czesław

2004-06-25

We present an experiment demonstrating the entanglement enhanced capacity of a quantum channel with correlated noise, modeled by a fiber optic link exhibiting fluctuating birefringence. In this setting, introducing entanglement between two photons is required to maximize the amount of information that can be encoded into their joint polarization degree of freedom. We demonstrated this effect using a fiber-coupled source of entangled photon pairs based on spontaneous parametric down-conversion, and a linear-optics Bell state measurement. The obtained experimental classical capacity with entangled states is equal to 0.82+/-0.04 per a photon pair, and it exceeds approximately 2.5 times the theoretical upper limit when no quantum correlations are allowed.

Gene conversion and positive selection driving the evolution of the Caenorhabditis ssp. ZIM/HIM-8 protein family.

PubMed

Liu, Qingpo

2009-03-01

In C. elegans, four C2H2 zinc-finger proteins (ZIM-1, ZIM-2, ZIM-3, and HIM-8), which are arranged in tandem, mediate chromosome-specific pairing and synapsis during meiosis. The zim/him-8 genes from three Caenorhabditis species were contrasted in an effort to investigate the mechanisms driving their evolution. Here it is shown that the preservation of higher degree of sequence similarity in the N-terminal portion, particularly in several regions within the second exon between paralogous zim genes (especially between zim-1 and zim-3), is due to independent interparalogue gene conversions. However, the evolutionary force is not uniformly strong across species. The present data reveal that more frequent gene conversion events have occurred in C. elegans, whereas only gene conversions between zim-1 and zim-3 are detected in C. remanei. Although gene conversions are predicted to be present among zim-1, zim-2, and zim-3 in C. briggsae, the conversion tracts between zim-1/zim-2 and zim-2/zim-3 are very short. Moreover, positive selection analysis was performed on the basis of the significantly discordant phylogenies reconstructed using the N- and C-terminal sequences, respectively. Several codon sites located in the regions that are supposed not to have experienced gene conversions are predicted to be under the influence of positive selection. In comparison, stronger positive selection has acted on the C-terminal region relative to the N-terminal region. Thus, the zim/him-8 genes that evolve concertedly have also been shown to undergo adaptive diversifying selection.

Beyond ketonization: selective conversion of carboxylic acids to olefins over balanced Lewis acid–base pairs

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

Baylon, Rebecca A. L.; Sun, Junming; Martin, Kevin J.

Dwindling petroleum reserves combined with increased energy demand and political factors encouraging an increase in energy independence have led to a large amount of research on sustainable alternatives. To this end, biomass conversion has been recognized as themost readily viable technology to produce biofuel concerning our reliance on liquid fuels for transportation and has the advantage of being easily integrated into our heavy use of combustion engines. The interest in biomass conversion has also resulted in reduced costs and a greater abundance of bio-oil, a mixture of hundreds of oxygenates including alcohols, aldehydes, carboxylic acids, and ketones. However, the presencemore » of carboxylic acids in bio-oil derived from lignocellulose pyrolysis leads to low pH, instability, and corrosiveness. In addition, carboxylic acids (i.e. acetic acid) can also be produced via fermentation of sugars. This can be accomplished by a variety of homoacetogenic microorganisms that can produce acetic acid with 100% carbon yield.« less

Antenna-coupled photon emission from hexagonal boron nitride tunnel junctions.

PubMed

Parzefall, M; Bharadwaj, P; Jain, A; Taniguchi, T; Watanabe, K; Novotny, L

2015-12-01

The ultrafast conversion of electrical signals to optical signals at the nanoscale is of fundamental interest for data processing, telecommunication and optical interconnects. However, the modulation bandwidths of semiconductor light-emitting diodes are limited by the spontaneous recombination rate of electron-hole pairs, and the footprint of electrically driven ultrafast lasers is too large for practical on-chip integration. A metal-insulator-metal tunnel junction approaches the ultimate size limit of electronic devices and its operating speed is fundamentally limited only by the tunnelling time. Here, we study the conversion of electrons (localized in vertical gold-hexagonal boron nitride-gold tunnel junctions) to free-space photons, mediated by resonant slot antennas. Optical antennas efficiently bridge the size mismatch between nanoscale volumes and far-field radiation and strongly enhance the electron-photon conversion efficiency. We achieve polarized, directional and resonantly enhanced light emission from inelastic electron tunnelling and establish a novel platform for studying the interaction of electrons with strongly localized electromagnetic fields.

Deception Detection: The Relationship of Levels of Trust and Perspective Taking in Real-Time Online and Offline Communication Environments.

PubMed

Friend, Catherine; Fox Hamilton, Nicola

2016-09-01

Where humans have been found to detect lies or deception only at the rate of chance in offline face-to-face communication (F2F), computer-mediated communication (CMC) online can elicit higher rates of trust and sharing of personal information than F2F. How do levels of trust and empathetic personality traits like perspective taking (PT) relate to deception detection in real-time CMC compared to F2F? A between groups correlational design (N = 40) demonstrated that, through a paired deceptive conversation task with confederates, levels of participant trust could predict accurate detection online but not offline. Second, participant PT abilities could not predict accurate detection in either conversation medium. Finally, this study found that conversation medium also had no effect on deception detection. This study finds support for the effects of the Truth Bias and online disinhibition in deception, and further implications in law enforcement are discussed.

A waveguide frequency converter connecting rubidium-based quantum memories to the telecom C-band.

PubMed

Albrecht, Boris; Farrera, Pau; Fernandez-Gonzalvo, Xavier; Cristiani, Matteo; de Riedmatten, Hugues

2014-02-27

Coherently converting the frequency and temporal waveform of single and entangled photons will be crucial to interconnect the various elements of future quantum information networks. Of particular importance is the quantum frequency conversion of photons emitted by material systems able to store quantum information, so-called quantum memories. There have been significant efforts to implement quantum frequency conversion using nonlinear crystals, with non-classical light from broadband photon-pair sources and solid-state emitters. However, solid state quantum frequency conversion has not yet been achieved with long-lived optical quantum memories. Here we demonstrate an ultra-low-noise solid state photonic quantum interface suitable for connecting quantum memories based on atomic ensembles to the telecommunication fibre network. The interface is based on an integrated-waveguide nonlinear device. We convert heralded single photons at 780 nm from a rubidium-based quantum memory to the telecommunication wavelength of 1,552 nm, showing significant non-classical correlations between the converted photon and the heralding signal.

[Comparison of noise characteristics of direct and indirect conversion flat panel detectors].

PubMed

Murai, Masami; Kishimoto, Kenji; Tanaka, Katsuhisa; Oota, Kenji; Ienaga, Akinori

2010-11-20

Flat-panel detector (FPD) digital radiography systems have direct and indirect conversion systems, and the 2 conversion systems provide different imaging performances. We measured some imaging performances [input-output characteristic, presampled modulation transfer function (presampled MTF), noise power spectrum (NPS)] of direct and indirect FPD systems. Moreover, some image samples of the NPSs were visually evaluated by the pair comparison method. As a result, the presampled MTF of the direct FPD system was substantially higher than that of the indirect FPD system. The NPS of the direct FPD system had a high value for all spatial frequencies. In contrast, the NPS of the indirect FPD system had a lower value as the frequency became higher. The results of visual evaluations showed the same tendency as that found for NPSs. We elucidated the cause of the difference in NPSs in a simulation study, and we determined that the cause of the difference in the noise components of the direct and indirect FPD systems was closely related to the presampled MTF.

Major Mergers in CANDELS up to z=3: Calibrating the Close-Pair Method Using Semi-Analytic Models and Baryonic Mass Ratio Estimates

NASA Astrophysics Data System (ADS)

Mantha, Kameswara; McIntosh, Daniel H.; Conselice, Christopher; Cook, Joshua S.; Croton, Darren J.; Dekel, Avishai; Ferguson, Henry C.; Hathi, Nimish; Kodra, Dritan; Koo, David C.; Lotz, Jennifer M.; Newman, Jeffrey A.; Popping, Gergo; Rafelski, Marc; Rodriguez-Gomez, Vicente; Simmons, Brooke D.; Somerville, Rachel; Straughn, Amber N.; Snyder, Gregory; Wuyts, Stijn; Yu, Lu; Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) Team

2018-01-01

Cosmological simulations predict that the rate of merging between similar-mass massive galaxies should increase towards early cosmic-time. We study the incidence of major (stellar mass ratio SMR<4) close-pairs among log(Mstellar/Msun) > 10.3 galaxies spanning 01.5 in strong disagreement with theoretical merger rate predictions. On the other hand, if we compare to a simulation-tuned, evolving timescale prescription from Snyder et al., 2017, we find that the merger rate evolution agrees with theory out to z=3. These results highlight the need for robust calibrations on the complex and presumably redshift-dependent pair-to-merger-rate conversion factors to improve constraints of the empirical merger history. To address this, we use a unique compilation of mock datasets produced by three independent state-of-the-art Semi-Analytic Models (SAMs). We present preliminary calibrations of the close-pair observability timescale and outlier fraction as a function of redshift, stellar-mass, mass-ratio, and local over-density. Furthermore, to verify the hypothesis by previous empirical studies that SMR-selection of major pairs may be biased, we present a new analysis of the baryonic (gas+stars) mass ratios of a subset of close pairs in our sample. For the first time, our preliminary analysis highlights that a noticeable fraction of SMR-selected minor pairs (SMR>4) have major baryonic-mass ratios (BMR<4), which indicate that merger rates based on SMR selection may be under-estimated.

Heralded wave packet manipulation and storage of a frequency-converted pair photon at telecom wavelength

NASA Astrophysics Data System (ADS)

Kroh, Tim; Ahlrichs, Andreas; Sprenger, Benjamin; Benson, Oliver

2017-09-01

Future quantum networks require a hybrid platform of dissimilar quantum systems. Within the platform, joint quantum states have to be mediated either by single photons, photon pairs or entangled photon pairs. The photon wavelength has to lie within the telecommunication band to enable long-distance fibre transmission. In addition, the temporal shape of the photons needs to be tailored to efficiently match the involved quantum systems. Altogether, this requires the efficient coherent wavelength-conversion of arbitrarily shaped single-photon wave packets. Here, we demonstrate the heralded temporal filtering of single photons as well as the synchronisation of state manipulation and detection as key elements in a typical experiment, besides of delaying a photon in a long fibre. All three are realised by utilising commercial telecommunication fibre-optical components which will permit the transition of quantum networks from the lab to real-world applications. The combination of these renders a temporally filtering single-photon storage in a fast switchable fibre loop possible.

CW-pumped telecom band polarization entangled photon pair generation in a Sagnac interferometer.

PubMed

Li, Yan; Zhou, Zhi-Yuan; Ding, Dong-Sheng; Shi, Bao-Sen

2015-11-02

Polarization entangled photon pair source is widely used in many quantum information processing applications such as teleportation, quantum communications, quantum computation and high precision quantum metrology. We report on the generation of a continuous-wave pumped 1550 nm polarization entangled photon pair source at telecom wavelength using a type-II periodically poled KTiOPO(4) (PPKTP) crystal in a Sagnac interferometer. Hong-Ou-Mandel (HOM) interference measurement yields signal and idler photon bandwidth of 2.4 nm. High quality of entanglement is verified by various kinds of measurements, for example two-photon interference fringes, Bell inequality and quantum states tomography. The source can be tuned over a broad range against temperature or pump power without loss of visibilities. This source will be used in our future experiments such as generation of orbital angular momentum entangled source at telecom wavelength for quantum frequency up-conversion, entanglement based quantum key distributions and many other quantum optics experiments at telecom wavelengths.

Entangled photons from single atoms and molecules

NASA Astrophysics Data System (ADS)

Nordén, Bengt

2018-05-01

The first two-photon entanglement experiment performed 50 years ago by Kocher and Commins (KC) provided isolated pairs of entangled photons from an atomic three-state fluorescence cascade. In view of questioning of Bell's theorem, data from these experiments are re-analyzed and shown sufficiently precise to confirm quantum mechanical and dismiss semi-classical theory without need for Bell's inequalities. Polarization photon correlation anisotropy (A) is useful: A is near unity as predicted quantum mechanically and well above the semi-classic range, 0 ⩽ A ⩽ 1 / 2 . Although yet to be found, one may envisage a three-state molecule emitting entangled photon pairs, in analogy with the KC atomic system. Antibunching in fluorescence from single molecules in matrix and entangled photons from quantum dots promise it be possible. Molecules can have advantages to parametric down-conversion as the latter photon distribution is Poissonian and unsuitable for producing isolated pairs of entangled photons. Analytical molecular applications of entangled light are also envisaged.

Generalized quantum interference of correlated photon pairs

PubMed Central

Kim, Heonoh; Lee, Sang Min; Moon, Han Seb

2015-01-01

Superposition and indistinguishablility between probability amplitudes have played an essential role in observing quantum interference effects of correlated photons. The Hong-Ou-Mandel interference and interferences of the path-entangled photon number state are of special interest in the field of quantum information technologies. However, a fully generalized two-photon quantum interferometric scheme accounting for the Hong-Ou-Mandel scheme and path-entangled photon number states has not yet been proposed. Here we report the experimental demonstrations of the generalized two-photon interferometry with both the interferometric properties of the Hong-Ou-Mandel effect and the fully unfolded version of the path-entangled photon number state using photon-pair sources, which are independently generated by spontaneous parametric down-conversion. Our experimental scheme explains two-photon interference fringes revealing single- and two-photon coherence properties in a single interferometer setup. Using the proposed interferometric measurement, it is possible to directly estimate the joint spectral intensity of a photon pair source. PMID:25951143

An overview of Laser-Produced Relativistic Positrons in the Laboratory

NASA Astrophysics Data System (ADS)

Edghill, Brandon; Williams, Gerald; Chen, Hui; Beg, Farhat

2017-10-01

The production of relativistic positrons using ultraintense lasers can facilitate studies of fundamental pair plasma science in the relativistic regime and laboratory studies of scaled energetic astrophysical mechanisms such as gamma ray bursts. The positron densities and spatial scales required for these applications, however, are larger than current capabilities. Here, we present an overview of the experimental laser-produced positron results and their respective modeling for both the direct laser-irradiated process and the indirect process (laser wakefield accelerated electrons irradiating a high-Z converter). Conversion efficiency into positrons and positron beam characteristics are compared, including total pair yield, mean energy, angular divergence, and inferred pair density for various laser and target conditions. Prospects towards increasing positron densities and beam repetition rates will also be discussed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and funded by LDRD (#17-ERD-010).

Multiple-Band Linear-Polarization Conversion and Circular Polarization in Reflection Mode Using a Symmetric Anisotropic Metasurface

NASA Astrophysics Data System (ADS)

Lin, Bao-Qin; Guo, Jian-Xin; Chu, Peng; Huo, Wen-Jun; Xing, Zhuo; Huang, Bai-Gang; Wu, Lan

2018-02-01

In this work, we propose a multiband linear-polarization (LP) conversion and circular polarization (CP) maintaining reflector using a symmetric anisotropic metasurface. The anisotropic metasurface is composed of a square array of a two-corner-cut square multiring disk printed on a grounded dielectric substrate, which is a symmetric structure with a pair of mutually perpendicular symmetric axes u and v along the ±45 ° directions with respect to the y -axis direction. The simulated results show that the reflector can realize LP conversion in five frequency bands at both x - and y -polarized incidence, the first four bands all have a certain bandwidth, and the fourth one, especially, is an ultrawideband. In addition, because of the symmetry of the reflector structure, the polarization state of a CP wave can be maintained after reflection, and the magnitude of the copolarized reflection coefficient at the CP incidence is just equal to that of the cross-polarized reflection coefficient at the x - and y -polarized incidence. We analyze the root cause of the multiband LP conversion and CP maintaining reflection, and carry out one experiment to verify the proposed reflector.

Providing views of the driving scene to drivers' conversation partners mitigates cell-phone-related distraction.

PubMed

Gaspar, John G; Street, Whitney N; Windsor, Matthew B; Carbonari, Ronald; Kaczmarski, Henry; Kramer, Arthur F; Mathewson, Kyle E

2014-12-01

Cell-phone use impairs driving safety and performance. This impairment may stem from the remote partner's lack of awareness about the driving situation. In this study, pairs of participants completed a driving simulator task while conversing naturally in the car and while talking on a hands-free cell phone. In a third condition, the driver drove while the remote conversation partner could see video of both the road ahead and the driver's face. We tested the extent to which this additional visual information diminished the negative effects of cell-phone distraction and increased situational awareness. Collision rates for unexpected merging events were high when participants drove in a cell-phone condition but were reduced when they were in a videophone condition, reaching a level equal to that observed when they drove with an in-car passenger or drove alone. Drivers and their partners made shorter utterances and made longer, more frequent traffic references when they spoke in the videophone rather than the cell-phone condition. Providing a view of the driving scene allows remote partners to help drivers by modulating their conversation and referring to traffic more often. © The Author(s) 2014.

Imprints of neutrino-pair flavor conversions on nucleosynthesis in ejecta from neutron-star merger remnants

NASA Astrophysics Data System (ADS)

Wu, Meng-Ru; Tamborra, Irene; Just, Oliver; Janka, Hans-Thomas

2017-12-01

The remnant of neutron star mergers is dense in neutrinos. By employing inputs from one hydrodynamical simulation of a binary neutron star merger remnant with a black hole of 3 M⊙ in the center, dimensionless spin parameter 0.8 and an accretion torus of 0.3 M⊙, the neutrino emission properties are investigated as the merger remnant evolves. Initially, the local number density of ν¯e is larger than that of νe everywhere above the remnant. Then, as the torus approaches self-regulated equilibrium, the local abundance of neutrinos overcomes that of antineutrinos in a funnel around the polar region. The region where the fast pairwise flavor conversions can occur shrinks accordingly as time evolves. Still, we find that fast flavor conversions do affect most of the neutrino-driven ejecta. Assuming that fast flavor conversions lead to flavor equilibration, a significant enhancement of nuclei with mass numbers A >130 is found as well as a change of the lanthanide mass fraction by more than a factor of a thousand. Our findings hint towards a potentially relevant role of neutrino flavor oscillations for the prediction of the kilonova (macronova) light curves and motivate further work in this direction.

Characteristics of manipulator for industrial robot with three rotational pairs having parallel axes

NASA Astrophysics Data System (ADS)

Poteyev, M. I.

1986-01-01

The dynamics of a manipulator with three rotatinal kinematic pairs having parallel axes are analyzed, for application in an industrial robot. The system of Lagrange equations of the second kind, describing the motion of such a mechanism in terms of kinetic energy in generalized coordinates, is reduced to equations of motion in terms of Newton's laws. These are useful not only for either determining the moments of force couples which will produce a prescribed motion or, conversely determining the motion which given force couples will produce but also for solving optimization problems under constraints in both cases and for estimating dynamic errors. As a specific example, a manipulator with all three axes of vertical rotation is considered. The performance of this manipulator, namely the parameters of its motion as functions of time, is compared with that of a manipulator having one rotational and two translational kinematic pairs. Computer aided simulation of their motion on the basis of ideal models, with all three links represented by identical homogeneous bars, has yielded velocity time diagrams which indicate that the manipulator with three rotational pairs is 4.5 times faster.

The Wildcat Corpus of Native- and Foreign-Accented English: Communicative Efficiency across Conversational Dyads with Varying Language Alignment Profiles

PubMed Central

Van Engen, Kristin J.; Baese-Berk, Melissa; Baker, Rachel E.; Choi, Arim; Kim, Midam; Bradlow, Ann R.

2012-01-01

This paper describes the development of the Wildcat Corpus of native- and foreign-accented English, a corpus containing scripted and spontaneous speech recordings from 24 native speakers of American English and 52 non-native speakers of English. The core element of this corpus is a set of spontaneous speech recordings, for which a new method of eliciting dialogue-based, laboratory-quality speech recordings was developed (the Diapix task). Dialogues between two native speakers of English, between two non-native speakers of English (with either shared or different L1s), and between one native and one non-native speaker of English are included and analyzed in terms of general measures of communicative efficiency. The overall finding was that pairs of native talkers were most efficient, followed by mixed native/non-native pairs and non-native pairs with shared L1. Non-native pairs with different L1s were least efficient. These results support the hypothesis that successful speech communication depends both on the alignment of talkers to the target language and on the alignment of talkers to one another in terms of native language background. PMID:21313992

Free-space entangled quantum carpets

NASA Astrophysics Data System (ADS)

Barros, Mariana R.; Ketterer, Andreas; Farías, Osvaldo Jiménez; Walborn, Stephen P.

2017-04-01

The Talbot effect in quantum physics is known to produce intricate patterns in the probability distribution of a particle, known as "quantum carpets," corresponding to the revival and replication of the initial wave function. Recently, it was shown that one can encode a D -level qudit in such a way that the Talbot effect can be used to process the D -dimensional quantum information [Farías et al., Phys. Rev. A 91, 062328 (2015), 10.1103/PhysRevA.91.062328]. Here we introduce a scheme to produce free-propagating "entangled quantum carpets" with pairs of photons produced by spontaneous parametric down-conversion. First we introduce an optical device that can be used to synthesize arbitrary superposition states of Talbot qudits. Sending spatially entangled photon pairs through a pair of these devices produces an entangled pair of qudits. As an application, we show how the Talbot effect can be used to test a D -dimensional Bell inequality. Numerical simulations show that violation of the Bell inequality depends strongly on the amount of spatial correlation in the initial two-photon state. We briefly discuss how our optical scheme might be adapted to matter wave experiments.

Mother-child memory conversations and self-construal in Eastern Turkey, Western Turkey and the USA.

PubMed

Sahin-Acar, Basak; Leichtman, Michelle D

2015-01-01

Eighty-seven mothers and their four-year-old children from Eastern Turkey (N = 32 pairs), Western Turkey (N = 30 pairs) and the USA (N = 25 pairs) participated in a study of mother-child memory talk as a reflection of mothers' self construal, in view of differences in the function of memory talk across cultures. Mother-child pairs were audio-recorded while talking about shared past and anticipated future events. Mothers completed the Balanced Integration-Differentiation questionnaire measure of self-construal and were scored as high or low on individuation and relatedness orientations. Mothers' memory and future talk showed similar patterns of cultural differences: American mothers provided the most voluminous, descriptive and elaborative talk, while Eastern Turkish mothers showed the highest level of repetitiveness, and Western Turkish mothers' talk fell in between. Children's memory talk was similar across cultures. In all cultures, mothers who scored high on both individuation and relatedness (balanced self-construal subtype) engaged in more voluminous and contexted memory talk, and individuation was associated with more elaborative talk about future events. Results are discussed in light of literature on cultural differences in self-construal and memory function.

Dancing to CHANGA: a self-consistent prediction for close SMBH pair formation time-scales following galaxy mergers

NASA Astrophysics Data System (ADS)

Tremmel, M.; Governato, F.; Volonteri, M.; Quinn, T. R.; Pontzen, A.

2018-04-01

We present the first self-consistent prediction for the distribution of formation time-scales for close supermassive black hole (SMBH) pairs following galaxy mergers. Using ROMULUS25, the first large-scale cosmological simulation to accurately track the orbital evolution of SMBHs within their host galaxies down to sub-kpc scales, we predict an average formation rate density of close SMBH pairs of 0.013 cMpc-3 Gyr-1. We find that it is relatively rare for galaxy mergers to result in the formation of close SMBH pairs with sub-kpc separation and those that do form are often the result of Gyr of orbital evolution following the galaxy merger. The likelihood and time-scale to form a close SMBH pair depends strongly on the mass ratio of the merging galaxies, as well as the presence of dense stellar cores. Low stellar mass ratio mergers with galaxies that lack a dense stellar core are more likely to become tidally disrupted and deposit their SMBH at large radii without any stellar core to aid in their orbital decay, resulting in a population of long-lived `wandering' SMBHs. Conversely, SMBHs in galaxies that remain embedded within a stellar core form close pairs in much shorter time-scales on average. This time-scale is a crucial, though often ignored or very simplified, ingredient to models predicting SMBH mergers rates and the connection between SMBH and star formation activity.

Hawking radiation

NASA Astrophysics Data System (ADS)

Parentani, Renaud; Spindel, Philippe

2011-12-01

Hawking radiation is the thermal radiation predicted to be spontaneously emitted by black holes. It arises from the steady conversion of quantum vacuum fluctuations into pairs of particles, one of which escaping at infinity while the other is trapped inside the black hole horizon. It is named after the physicist Stephen Hawking who derived its existence in 1974. This radiation reduces the mass of black holes and is therefore also known as black hole evaporation.

Exploring the Role of Peer Advice in Self-Regulated Learning: Metacognitive, Social, and Environmental Factors.

PubMed

Rashid, Hanin; Lebeau, Robert; Saks, Norma; Cianciolo, Anna T; Artino, Anthony R; Shea, Judy A; Ten Cate, Olle

2016-01-01

This Conversation Starters article presents a selected research abstract from the 2016 Association of American Medical Colleges Northeast Region Group on Educational Affairs annual spring meeting. The abstract is paired with the integrative commentary of three experts who shared their thoughts stimulated by the pilot study. These thoughts explore the metacognitive, social, and environmental mechanisms whereby advice plays a role in self-regulated learning.

Inhibition of riboflavin metabolism in rat tissues by chlorpromazine, imipramine, and amitriptyline.

PubMed

Pinto, J; Huang, Y P; Rivlin, R S

1981-05-01

Prompted by recognition of the similar structures of riboflavin (vitamin B(2)), phenothiazine drugs, and tricyclic antidepressants, our studies sought to determine effects of drugs of these two types upon the conversion of riboflavin into its active coenzyme derivative, flavin adenine dinucleotide (FAD) in rat tissues. Chlorpromazine, a phenothiazine derivative, and imipramine and amitriptyline, both tricyclic antidepressants, each inhibited the incorporation of [(14)C]riboflavin into [(14)C]FAD in liver, cerebrum, cerebellum, and heart. A variety of psychoactive drugs structurally unrelated to riboflavin were ineffective. Chlorpromazine, imipramine, and amitriptyline in vitro inhibited hepatic flavokinase, the first of two enzymes in the conversion of riboflavin to FAD. Evidence was obtained that chlorpromazine administration for a 3- or 7-wk period at doses comparable on a weight basis to those used clinically has significant effects upon riboflavin metabolism in the animal as a whole: (a) the activity coefficient of erythrocyte glutathione reductase, an FAD-containing enzyme used as an index of riboflavin status physiologically, was elevated, a finding compatible with a deficiency state, (b) the urinary excretion of riboflavin was more than twice that of age- and sex-matched pair-fed control rats, and (c) after administration of chlorpromazine for a 7-wk period, tissue levels of flavin mononucleotide and FAD were significantly lower than those of pair-fed littermates, despite consumption of a diet estimated to contain 30 times the recommended dietary allowance. The present study suggests that certain psychotropic drugs interfere with riboflavin metabolism at least in part by inhibiting the conversion of riboflavin to its coenzyme derivatives, and that as a consequence of such inhibition, the overall utilization of the vitamin is impaired.

Conversations in end-of-life care: communication tools for critical care practitioners.

PubMed

Shannon, Sarah E; Long-Sutehall, Tracy; Coombs, Maureen

2011-01-01

Communication skills are the key for quality end-of-life care including in the critical care setting. While learning general, transferable communication skills, such as therapeutic listening, has been common in nursing education, learning specific communication tools, such as breaking bad news, has been the norm for medical education. Critical care nurses may also benefit from learning communication tools that are more specific to end-of-life care. We conducted a 90-min interactive workshop at a national conference for a group of 78 experienced critical care nurses where we presented three communication tools using short didactics. We utilized theatre style and paired role play simulation. The Ask-Tell-Ask, Tell Me More and Situation-Background-Assessment-Recommendation (SBAR) tools were demonstrated or practiced using a case of a family member who feels that treatment is being withdrawn prematurely for the patient. The audience actively participated in debriefing the role play to maximize learning. The final communication tool, SBAR, was practiced using an approach of pairing with another member of the audience. At the end of the session, a brief evaluation was completed by 59 nurses (80%) of the audience. These communication tools offer nurses new strategies for approaching potentially difficult and emotionally charged conversations. A case example illustrated strategies for applying these skills to clinical situations. The three tools assist critical care nurses to move beyond compassionate listening to knowing what to say. Ask-Tell-Ask reminds nurses to carefully assess concerns before imparting information. Tell Me More provides a tool for encouraging dialogue in challenging situations. Finally, SBAR can assist nurses to distill complex and often long conversations into concise and informative reports for colleagues. © 2011 The Authors. Nursing in Critical Care © 2011 British Association of Critical Care Nurses.

[Cross comparison of ASTER and Landsat ETM+ multispectral measurements for NDVI and SAVI vegetation indices].

PubMed

Xu, Han-qiu; Zhang, Tie-jun

2011-07-01

The present paper investigates the quantitative relationship between the NDVI and SAVI vegetation indices of Landsat and ASTER sensors based on three tandem image pairs. The study examines how well ASTER sensor vegetation observations replicate ETM+ vegetation observations, and more importantly, the difference in the vegetation observations between the two sensors. The DN values of the three image pairs were first converted to at-sensor reflectance to reduce radiometric differences between two sensors, images. The NDVI and SAVI vegetation indices of the two sensors were then calculated using the converted reflectance. The quantitative relationship was revealed through regression analysis on the scatter plots of the vegetation index values of the two sensors. The models for the conversion between the two sensors, vegetation indices were also obtained from the regression. The results show that the difference does exist between the two sensors, vegetation indices though they have a very strong positive linear relationship. The study found that the red and near infrared measurements differ between the two sensors, with ASTER generally producing higher reflectance in the red band and lower reflectance in the near infrared band than the ETM+ sensor. This results in the ASTER sensor producing lower spectral vegetation index measurements, for the same target, than ETM+. The relative spectral response function differences in the red and near infrared bands between the two sensors are believed to be the main factor contributing to their differences in vegetation index measurements, because the red and near infrared relative spectral response features of the ASTER sensor overlap the vegetation "red edge" spectral region. The obtained conversion models have high accuracy with a RMSE less than 0.04 for both sensors' inter-conversion between corresponding vegetation indices.

Alpha-Voltaic Sources Using Diamond as Conversion Medium

NASA Technical Reports Server (NTRS)

Patel, Jagadish U.; Fleurial, Jean-Pierre; Kolawa, Elizabeth

2006-01-01

A family of proposed miniature sources of power would exploit the direct conversion of the kinetic energy of a particles into electricity in diamond semiconductor diodes. These power sources would function over a wide range of temperatures encountered in terrestrial and outer-space environments. These sources are expected to have operational lifetimes of 10 to 20 years and energy conversion efficiencies >35 percent. A power source according to the proposal would include a pair of devices like that shown in the figure. Each device would contain Schottky and p/n diode devices made from high-band-gap, radiation-hard diamond substrates. The n and p layers in the diode portion would be doped sparsely (<1014 cm-3) in order to maximize the volume of the depletion region and thereby maximize efficiency. The diode layers would be supported by an undoped diamond substrate. The source of a particles would be a thin film of 244Cm (half-life 18 years) sandwiched between the two paired devices. The sandwich arrangement would force almost every a particle to go through the active volume of at least one of the devices. Typical a particle track lengths in the devices would range from 20 to 30 microns. The a particles would be made to stop only in the undoped substrates to prevent damage to the crystalline structures of the diode portions. The overall dimensions of a typical source are expected to be about 2 by 2 by 1 mm. Assuming an initial 244Cm mass of 20 mg, the estimated initial output of the source is 20 mW (a current of 20 mA at a potential of 1 V).

Development of a Broad High-Energy Gamma-Ray Telescope using Silicon Strip Detectors

NASA Technical Reports Server (NTRS)

Michelson, Peter F.

1998-01-01

The research effort has led to the development and demonstration of technology to enable the design and construction of a next-generation high-energy gamma-ray telescope that operates in the pair-production regime (E greater than 10 MeV). In particular, the technology approach developed is based on silicon-strip detector technology. A complete instrument concept based on this technology for the pair-conversion tracker and the use of CsI(T1) crystals for the calorimeter is now the baseline instrument concept for the Gamma-ray Large Area Space Telescope (GLAST) mission. GLAST is NASA's proposed high-energy gamma-ray mission designed to operate in the energy range from 10 MeV to approximately 300 GeV. GLAST, with nearly 100 times the sensitivity of EGRET, operates through pair conversion of gamma-rays and measurement of the direction and energy of the resulting e (+) - e (-) shower. The baseline design, developed with support from NASA includes a charged particle anticoincidence shield, a tracker/converter made of thin sheets of high-Z material interspersed with Si strip detectors, a CsI calorimeter and a programmable data trigger and acquisition system. The telescope is assembled as an array of modules or towers. Each tower contains elements of the tracker, calorimeter, and anticoincidence system. As originally proposed, the telescope design had 49 modules. In the more optimized design that emerged at the end of the grant period the individual modules are larger and the total number in the GLAST array is 25. Also the calorimeter design was advanced substantially to the point that it has a self-contained imaging capability, albeit much cruder than the tracker.

Stereo-selective partitioning of translation-to-internal energy conversion in gas ensembles

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

McCaffery, Anthony J., E-mail: A.J.McCaffery@sussex.ac.uk

2014-11-07

A recent computational study of translation-to-internal energy transfer to H{sub 2} (v = 0,j = 0), hereinafter denoted H{sub 2} (0;0), in a bath of H atoms [A. J. McCaffery and R. J. Marsh, J. Chem. Phys. 139, 234310 (2013)] revealed an unexpected energy partitioning in which the H{sub 2} vibrational temperature greatly exceeds that of rotation. This occurs despite rotation and vibration distributions being close to Boltzmann from early in ensemble evolution. In this work, the study is extended to include H{sub 2} (0;0), O{sub 2} (0;0), and HF (0;0) in a wide range of atomic bath gases comprisingmore » some 22 ensembles in all. Translation-to-internal energy conversion in the systems studied was found to be relatively inefficient, falling approximately with (√μ′){sup −1} as bath gas mass increases, where μ′ is the reduced mass of the diatomic–bath gas pair. In all 22 systems studied, T{sub v} exceeds T{sub r} – by a factor > 4 for some pairs. Analysis of the constraints that influence (0;0) → (1;j) excitation for each diatomic–atom pair in momentum–angular momentum space demonstrates that a vibrational preference results from energy constraints that limit permitted collision trajectories to those of low effective impact parameter, i.e., to those that are axial or near axial on impact with the Newton surface. This implies that a steric constraint is an inherent feature of vibration-rotation excitation and arises because momentum and energy barriers must be overcome before rotational states may be populated in the higher vibrational level.« less

Quantum optical measurement with tripartite entangled photons generated by triple parametric down-conversion

NASA Astrophysics Data System (ADS)

Cho, Minhaeng

2018-05-01

Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams. Recently, we considered another quantum optical measurement scheme utilizing W-type tripartite entangled signal photons that can be generated by employing three spontaneous parametric down-conversion crystals and by inducing coherences or path-indistinguishabilities between their correlated idler beams and between quantum vacuum fields. Here, we consider an extended triple stimulated parametric down-conversion scheme for quantum optical measurement of sample properties with undetected idler and photons. Noting the real effect of vacuum field indistinguishability on the fringe visibility as well as the role of zero-point field energy in the interferometry, we show that this scheme is an ideal and efficient way to create a coherent state of W-type entangled signal photons. We anticipate that this scheme would be of critical use in further developing quantum optical measurements in spectroscopy and microscopy with undetected photons.

Isolation of Cu Atoms in Pd Lattice: Forming Highly Selective Sites for Photocatalytic Conversion of CO2 to CH4.

PubMed

Long, Ran; Li, Yu; Liu, Yan; Chen, Shuangming; Zheng, Xusheng; Gao, Chao; He, Chaohua; Chen, Nanshan; Qi, Zeming; Song, Li; Jiang, Jun; Zhu, Junfa; Xiong, Yujie

2017-03-29

Photocatalytic conversion of CO 2 to CH 4 , a carbon-neutral fuel, represents an appealing approach to remedy the current energy and environmental crisis; however, it suffers from the large production of CO and H 2 by side reactions. The design of catalytic sites for CO 2 adsorption and activation holds the key to address this grand challenge. In this Article, we develop highly selective sites for photocatalytic conversion of CO 2 to CH 4 by isolating Cu atoms in Pd lattice. According to our synchrotron-radiation characterizations and theoretical simulations, the isolation of Cu atoms in Pd lattice can play dual roles in the enhancement of CO 2 -to-CH 4 conversion: (1) providing the paired Cu-Pd sites for the enhanced CO 2 adsorption and the suppressed H 2 evolution; and (2) elevating the d-band center of Cu sites for the improved CO 2 activation. As a result, the Pd 7 Cu 1 -TiO 2 photocatalyst achieves the high selectivity of 96% for CH 4 production with a rate of 19.6 μmol g cat -1 h -1 . This work provides fresh insights into the catalytic site design for selective photocatalytic CO 2 conversion, and highlights the importance of catalyst lattice engineering at atomic precision to catalytic performance.

Quantum optical measurement with tripartite entangled photons generated by triple parametric down-conversion.

PubMed

Cho, Minhaeng

2018-05-14

Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams. Recently, we considered another quantum optical measurement scheme utilizing W-type tripartite entangled signal photons that can be generated by employing three spontaneous parametric down-conversion crystals and by inducing coherences or path-indistinguishabilities between their correlated idler beams and between quantum vacuum fields. Here, we consider an extended triple stimulated parametric down-conversion scheme for quantum optical measurement of sample properties with undetected idler and photons. Noting the real effect of vacuum field indistinguishability on the fringe visibility as well as the role of zero-point field energy in the interferometry, we show that this scheme is an ideal and efficient way to create a coherent state of W-type entangled signal photons. We anticipate that this scheme would be of critical use in further developing quantum optical measurements in spectroscopy and microscopy with undetected photons.

Theoretical limits of the multistacked 1D and 2D microstructured inorganic solar cells

NASA Astrophysics Data System (ADS)

Yengel, Emre; Karaagac, Hakan; VJ, Logeeswaran; Islam, M. Saif

2015-09-01

Recent studies in monocrystalline semiconductor solar cells are focused on mechanically stacking multiple cells from different materials to increase the power conversion efficiency. Although, the results show promising increase in the device performance, the cost remains as the main drawback. In this study, we calculated the theoretical limits of multistacked 1D and 2D microstructered inorganic monocrstalline solar cells. This system is studied for Si and Ge material pair. The results show promising improvements in the surface reflection due to enhanced light trapping caused by photon-microstructures interactions. The theoretical results are also supported with surface reflection and angular dependent power conversion efficiency measurements of 2D axial microwall solar cells. We address the challenge of cost reduction by proposing to use our recently reported mass-manufacturable fracture-transfer- printing method which enables the use of a monocrystalline substrate wafer for repeated fabrication of devices by consuming only few microns of materials in each layer of devices. We calculated thickness dependent power conversion efficiencies of multistacked Si/Ge microstructured solar cells and found the power conversion efficiency to saturate at 26% with a combined device thickness of 30 μm. Besides having benefits of fabricating low-cost, light weight, flexible, semi-transparent, and highly efficient devices, the proposed fabrication method is applicable for other III-V materials and compounds to further increase the power conversion efficiency above 35% range.

The behavior of exciplex decay processes and interplay of radiationless transition and preliminary reorganization mechanisms of electron transfer in loose and tight pairs of reactants.

PubMed

Kuzmin, Michael G; Soboleva, Irina V; Dolotova, Elena V

2007-01-18

Exciplex emission spectra and rate constants of their decay via internal conversion and intersystem crossing are studied and discussed in terms of conventional radiationless transition approach. Exciplexes of 9-cyanophenanthrene with 1,2,3-trimethoxybenzene and 1,3,5-trimethoxybenzene were studied in heptane, toluene, butyl acetate, dichloromethane, butyronitrile, and acetonitrile. A better description of spectra and rate constants is obtained using 0-0 transition energy and Gauss broadening of vibrational bands rather than the free energy of electron transfer and reorganization energy. The coincidence of parameters describing exciplex emission spectra and dependence of exciplex decay rate constants on energy gap gives the evidence of radiationless quantum transition mechanism rather than thermally activated medium reorganization mechanism of charge recombination in exciplexes and excited charge transfer complexes (contact radical ion pairs) as well as in solvent separated radical ion pairs. Radiationless quantum transition mechanism is shown to provide an appropriate description also for the main features of exergonic excited-state charge separation reactions if fast mutual transformations of loose and tight pairs of reactants are considered. In particular, very fast electron transfer (ET) in tight pairs of reactants with strong electronic coupling of locally excited and charge transfer states can prevent the observation of an inverted region in bimolecular excited-state charge separation even for highly exergonic reactions.

Performance of a Kilowatt-Class Stirling Power Conversion System in a Thermodynamically Coupled Configuration

NASA Technical Reports Server (NTRS)

Geng, Steven M.; Briggs, Maxwell H.; Hervol, David S.

2011-01-01

A pair of 1-kWe free-piston Stirling power convertors has been modified into a thermodynamically coupled configuration, and performance map testing has been completed. This is the same configuration planned for the full-scale 12-kWe power conversion unit (PCU) that will be used in the Fission Power System Technology Demonstration Unit (TDU). The 1-kWe convertors were operated over a range of conditions to evaluate the effects of thermodynamic coupling on convertor performance and to identify any possible control challenges. The thermodynamically coupled convertor showed no measureable difference in performance from the baseline data collected when the engines were separate, and no major control issues were encountered during operation. The results of this test are guiding controller development and instrumentation selection for the TDU.

Determination of arsenate and organic arsenic via potentiometric titration of its heteropoly anions.

PubMed

Metelka, R; Slavíková, S; Vytras, K

2002-08-16

Determination of arsenate based on its conversion to molybdoarsenate heteropoly anions followed by potentiometric titration is described. The titration is realized on the ion-pairing principle using cetylpyridinium chloride (or an analogous titrant containing a lipophilic cation), and is monitored by a carbon paste electrode, although other liquid-polymeric membrane-based electrodes can also be used. Calibration plots of the titrant end-point consumption versus concentration of arsenic were constructed and used to evaluate the content of arsenic in aqueous samples. The method could be applied in the analyses of samples with quite low arsenic content (amounts approximately 10 mug As in 50 cm(3) could be titrated). Organic arsenic was determined analogously after the Schöniger combustion of the sample and conversion of its arsenic to arsenate.

Effect of an observer's presence on facial behavior during dyadic communication.

PubMed

Yamamoto, K; Suzuki, N

2012-06-01

In everyday life, people communicate not only with another person but also in front of other people. How do people behave during communication when observed by others? Effects of an observer (presence vs absence) and interpersonal relationship (friends vs strangers vs alone) on facial behavior were examined. Participants viewed film clips that elicited positive affect (film presentation) and discussed their impressions about the clips (conversation). Participants rated their subjective emotions and social motives. Durations of smiles, gazes, and utterances of each participant were coded. The presence of an observer did not affect facial behavior during the film presentation, but did affect gazes during conversation. Whereas the presence of an observer seemed to facilitate affiliation in pairs of strangers, communication between friends was exclusive and not affected by an observer.

Channeling Identity: A Study of Storytelling in Conversations Between Introverted and Extraverted Friends

PubMed Central

Thorne, Avril; Korobov, Neill; Morgan, Elizabeth M.

2009-01-01

This narrative study examined the process of personal storytelling between college-age friends who were similarly introverted or extraverted. Participants were 19 introverted and 20 extraverted same-sex pairs (49 percent female) who had been friends for an average of 18 months. Stories emerged spontaneously during 10-minute catch-up conversations. Extraverted friends more often told stories that changed the topic, and more often co-constructed story plots. Introverted friends more often told stories that were embedded in a developing theme, and constructed story plots solo. With regard to content, extraverted friends told stories about romance more so than introverted friends, whose stories more often concerned family/hometown, and older events. The findings suggest that the traits of extraversion and introversion channel the identity-making process. PMID:19325709

Direct adaptive control of wind energy conversion systems using Gaussian networks.

PubMed

Mayosky, M A; Cancelo, I E

1999-01-01

Grid connected wind energy conversion systems (WECS) present interesting control demands, due to the intrinsic nonlinear characteristics of windmills and electric generators. In this paper a direct adaptive control strategy for WECS control is proposed. It is based on the combination of two control actions: a radial basis zfunction network-based adaptive controller, which drives the tracking error to zero with user specified dynamics, and a supervisory controller, based on crude bounds of the system's nonlinearities. The supervisory controller fires when the finite neural-network approximation properties cannot be guaranteed. The form of the supervisor control and the adaptation law for the neural controller are derived from a Lyapunov analysis of stability. The results are applied to a typical turbine/generator pair, showing the feasibility of the proposed solution.

Conversion-electron spectroscopy and gamma-gamma angular correlation measurements in 116Sn

NASA Astrophysics Data System (ADS)

Cross, D. S.; Pore, J. L.; Andreoiu, C.; Ball, G. C.; Bender, P. C.; Chester, A. S.; Churchman, R.; Demand, G. A.; Diaz Varela, A.; Dunlop, R.; Garnsworthy, A. B.; Garrett, P. E.; Hackman, G.; Hadinia, B.; Jigmeddorj, B.; Laffoley, A. T.; Liblong, A.; Kanungo, R.; Miller, D. T.; Noakes, B.; Petrache, C. M.; Starosta, K.; Svensson, C. E.; Voss, P.; Wang, Z.-M.; Wilson, J. M.; Wood, J. L.; Yates, S. W.

2017-11-01

The 116Sn nucleus was studied via the β- decay of 116In utilizing the 8π spectrometer and its auxiliary detectors at TRIUMF-ISAC. The resulting K-shell conversion coefficients, K/L ratios, and multipole mixing ratios are presented. The 23+ → 21+ 931 keV and 22+ → 21+ 819 keV transition mixing ratios were re-measured and found to be δ = +1.8_{-0.5}^{+0.7} and -1.83(8), respectively. Newly measured mixing ratios for transitions among the low-lying I^{π} = 4+ states in 116Sn, when combined with γ-ray intensity data, suggest that the 2529 keV 42+ state possesses a neutron broken-pair admixture in addition to its dominant proton 2p-2h component.

Caught in the Act: How Extraverted and Introverted Friends Communally Cope with Being Recorded

PubMed Central

Thorne, Avril; Shapiro, Lauren; Cardilla, Kim; Korobov, Neill; Nelson, Paul A.

2009-01-01

This study explored how close friends who were similar or opposite on extraversion communally coped with being put on the spot to produce a recorded conversation. Participants were 50 pairs of same-sex college-age friends (54% female) who explicitly discussed the fact that their conversation was being recorded. The initial 'on-stage' episode emerged consistently earliest for extraverted dyads, and the majority of their episodes quickly diverted the on-stage moment. Dyads that included at least one introvert engaged in more extensive assortments of on-stage maneuvers, including research talk, soothing, and joking. In introvert-extravert dyads the extravert usually initiated and ended these episodes. Implications are discussed for understanding how personality is reciprocally implicated in managing shared everyday problems. PMID:20161279

Performance of a Kilowatt-Class Stirling Power Conversion System in a Thermodynamically-Coupled Configuration

NASA Astrophysics Data System (ADS)

Geng, S. M.; Briggs, M. H.; Hervol, D. S.

A pair of 1kWe free-piston Stirling power convertors has been modified into a thermodynamically coupled configuration, and performance map testing has been completed. This is the same configuration planned for the full-scale 12 kWe power conversion unit (PCU) that will be used in the Fission Power System Technology Demonstration Unit (TDU). The 1-kWe convertors were operated over a range of conditions to evaluate the effects of thermodynamic coupling on convertor performance and to identify any possible control challenges. The thermodynamically coupled convertor showed no measurable difference in performance from the baseline data collected when the engines were separate and no major control issues were encountered during operation. The results of this test are guiding controller development and instrumentation selection for the TDU.

MPPT Algorithm Development for Laser Powered Surveillance Camera Power Supply Unit

NASA Astrophysics Data System (ADS)

Zhang, Yungui; Dushantha Chaminda, P. R.; Zhao, Kun; Cheng, Lin; Jiang, Yi; Peng, Kai

2018-03-01

Photovoltaics (PV) cells, modules which are semiconducting materials, convert light energy into electricity. Operation of a PV cell requires 3 basic features. When the light is absorbed it generate pairs of electron holes or excitons. An external circuit carrier opposite types of electrons irrespective of the source (sunlight or LASER light). The PV arrays have photovoltaic effect and the PV cells are defined as a device which has electrical characteristics: such as current, voltage and resistance. It varies when exposed to light, that the power output is depend on direct Laser-light. In this paper Laser-light to electricity by direct conversion with the use of PV cells and its concept of Band gap Energy, Series Resistance, Conversion Efficiency and Maximum Power Point Tracking (MPPT) methods [1].

Nationwide conversion to generic tacrolimus in pediatric kidney transplant recipients.

PubMed

Naicker, Derisha; Reed, Peter W; Ronaldson, Jane; Kara, Tonya; Wong, William; Prestidge, Chanel

2017-11-01

Bioequivalence between Tacrolimus Prograf® and generic tacrolimus formulations has been demonstrated in adult populations, however clinical experience and safety data regarding generic tacrolimus in pediatric transplant recipients is limited. This study aimed to evaluate conversion from Tacrolimus Prograf® to Sandoz® in pediatric renal transplant recipients nationwide. The primary outcome was a change in mean trough tacrolimus concentration. Additionally, changes in tacrolimus intra-patient coefficient of variation (CoV), allograft function, requirement for dose adjustments, and episodes of biopsy-proven rejection were evaluated. Retrospective cohort study in 37 pediatric renal transplant recipients who switched to Tacrolimus Sandoz®. Each patient had three pre-conversion tacrolimus trough and creatinine concentrations within the 4 months prior and three post-conversion concentrations on day 3, 10, and the next subsequent level. Mean pre- and post-conversion tacrolimus trough concentrations and glomerular filtration rate (eGFR) were calculated. Tacrolimus concentration, CoV, and creatinine differences were compared by paired t test. Thirty-seven patients (41% females, age 3-18 years) were included. Average intra-patient difference in trough tacrolimus concentration was 0.05μg/l (95% CI -0.37 to 0.47). Average intra-patient difference in eGFR was -1.20 ml/min/1.73 2 (95% CI -3.53 to 1.13). Three patients had acute rejection during 12 months post-conversion compared to none during 12 months pre-conversion. Pediatric renal transplant recipients can be converted from Tacrolimus Prograf® to Sandoz® with negligible change in trough concentration, dose adjustments, or immediate allograft function. Of concern was the number of acute rejection episodes, however non-adherence contributed to at least one episode and this difference was determined clinically and statistically not significant.

Evidence for somatic gene conversion and deletion in bipolar disorder, Crohn's disease, coronary artery disease, hypertension, rheumatoid arthritis, type-1 diabetes, and type-2 diabetes

PubMed Central

2011-01-01

Background During gene conversion, genetic information is transferred unidirectionally between highly homologous but non-allelic regions of DNA. While germ-line gene conversion has been implicated in the pathogenesis of some diseases, somatic gene conversion has remained technically difficult to investigate on a large scale. Methods A novel analysis technique is proposed for detecting the signature of somatic gene conversion from SNP microarray data. The Wellcome Trust Case Control Consortium has gathered SNP microarray data for two control populations and cohorts for bipolar disorder (BD), cardiovascular disease (CAD), Crohn's disease (CD), hypertension (HT), rheumatoid arthritis (RA), type-1 diabetes (T1D) and type-2 diabetes (T2D). Using the new analysis technique, the seven disease cohorts are analyzed to identify cohort-specific SNPs at which conversion is predicted. The quality of the predictions is assessed by identifying known disease associations for genes in the homologous duplicons, and comparing the frequency of such associations with background rates. Results Of 28 disease/locus pairs meeting stringent conditions, 22 show various degrees of disease association, compared with only 8 of 70 in a mock study designed to measure the background association rate (P < 10-9). Additional candidate genes are identified using less stringent filtering conditions. In some cases, somatic deletions appear likely. RA has a distinctive pattern of events relative to other diseases. Similarities in patterns are apparent between BD and HT. Conclusions The associations derived represent the first evidence that somatic gene conversion could be a significant causative factor in each of the seven diseases. The specific genes provide potential insights about disease mechanisms, and are strong candidates for further study. Please see Commentary: http://www.biomedcentral.com/1741-7015/9/13/abstract. PMID:21291537

Evidence for somatic gene conversion and deletion in bipolar disorder, Crohn's disease, coronary artery disease, hypertension, rheumatoid arthritis, type-1 diabetes, and type-2 diabetes.

PubMed

Ross, Kenneth Andrew

2011-02-03

During gene conversion, genetic information is transferred unidirectionally between highly homologous but non-allelic regions of DNA. While germ-line gene conversion has been implicated in the pathogenesis of some diseases, somatic gene conversion has remained technically difficult to investigate on a large scale. A novel analysis technique is proposed for detecting the signature of somatic gene conversion from SNP microarray data. The Wellcome Trust Case Control Consortium has gathered SNP microarray data for two control populations and cohorts for bipolar disorder (BD), cardiovascular disease (CAD), Crohn's disease (CD), hypertension (HT), rheumatoid arthritis (RA), type-1 diabetes (T1D) and type-2 diabetes (T2D). Using the new analysis technique, the seven disease cohorts are analyzed to identify cohort-specific SNPs at which conversion is predicted. The quality of the predictions is assessed by identifying known disease associations for genes in the homologous duplicons, and comparing the frequency of such associations with background rates. Of 28 disease/locus pairs meeting stringent conditions, 22 show various degrees of disease association, compared with only 8 of 70 in a mock study designed to measure the background association rate (P < 10-9). Additional candidate genes are identified using less stringent filtering conditions. In some cases, somatic deletions appear likely. RA has a distinctive pattern of events relative to other diseases. Similarities in patterns are apparent between BD and HT. The associations derived represent the first evidence that somatic gene conversion could be a significant causative factor in each of the seven diseases. The specific genes provide potential insights about disease mechanisms, and are strong candidates for further study.

Tailoring entanglement through domain engineering in a lithium niobate waveguide

PubMed Central

Ming, Yang; Tan, Ai-Hong; Wu, Zi-Jian; Chen, Zhao-Xian; Xu, Fei; Lu, Yan-Qing

2014-01-01

We propose to integrate the electro-optic (EO) tuning function into on-chip domain engineered lithium niobate (LN) waveguide. Due to the versatility of LN, both the spontaneously parametric down conversion (SPDC) and EO interaction could be realized simultaneously. Photon pairs are generated through SPDC, and the formation of entangled state is modulated by EO processes. An EO tunable polarization-entangled photon state is proposed. Orthogonally-polarized and parallel-polarized entanglements of photon pairs are instantly switchable by tuning the applied field. The characteristics of the source are theoretically investigated showing adjustable bandwidths and high entanglement degrees. Moreover, other kinds of reconfigurable entanglement are also achievable based on suitable domain-design. We believe tailoring entanglement based on domain engineering is a very promising solution for next generation function-integrated quantum circuits. PMID:24770555

Coincidence detection of spatially correlated photon pairs with a monolithic time-resolving detector array.

PubMed

Unternährer, Manuel; Bessire, Bänz; Gasparini, Leonardo; Stoppa, David; Stefanov, André

2016-12-12

We demonstrate coincidence measurements of spatially entangled photons by means of a multi-pixel based detection array. The sensor, originally developed for positron emission tomography applications, is a fully digital 8×16 silicon photomultiplier array allowing not only photon counting but also per-pixel time stamping of the arrived photons with an effective resolution of 265 ps. Together with a frame rate of 500 kfps, this property exceeds the capabilities of conventional charge-coupled device cameras which have become of growing interest for the detection of transversely correlated photon pairs. The sensor is used to measure a second-order correlation function for various non-collinear configurations of entangled photons generated by spontaneous parametric down-conversion. The experimental results are compared to theory.

Pulsed source of spectrally uncorrelated and indistinguishable photons at telecom wavelengths.

PubMed

Bruno, N; Martin, A; Guerreiro, T; Sanguinetti, B; Thew, R T

2014-07-14

We report on the generation of indistinguishable photon pairs at telecom wavelengths based on a type-II parametric down conversion process in a periodically poled potassium titanyl phosphate (PPKTP) crystal. The phase matching, pump laser characteristics and coupling geometry are optimised to obtain spectrally uncorrelated photons with high coupling efficiencies. Four photons are generated by a counter-propagating pump in the same crystal and anlysed via two photon interference experiments between photons from each pair source as well as joint spectral and g((2)) measurements. We obtain a spectral purity of 0.91 and coupling efficiencies around 90% for all four photons without any filtering. These pure indistinguishable photon sources at telecom wavelengths are perfectly adapted for quantum network demonstrations and other multi-photon protocols.

Two-Particle Interference of Electron Pairs on a Molecular Level

DOE PAGES

Waitz, M.; Metz, D.; Lower, J.; ...

2016-08-15

Here, wWe investigate the photodouble ionization of H 2 molecules with 400 eV photons. We find that the emitted electrons do not show any sign of two-center interference fringes in their angular emission distributions if considered separately. Conversely, the quasiparticle consisting of both electrons (i.e., the "dielectron") does. The work highlights the fact that nonlocal effects are embedded everywhere in nature where many-particle processes are involved.

Multipli-Entangled Photons from a Spontaneous Parametric Down-Conversion Source

DTIC Science & Technology

2011-01-01

Alsing, Corey J. Peters (AFRL/RITA); Enrique J. Galvez ( Colgate University, Hamilton, NY) 5d. PROJECT NUMBER QIS0 5e. TASK NUMBER PR 5f...and Enrique J. Galvez Colgate University, Hamilton, NY (USA) 1. ABSTRACT In this work, we discuss a novel compact source that generates six...single pair of entangled photons per pass in conventional SPDC-based sources. We first describe the experimental testbed used for evaluation and

Comparative analysis of main bio-active components in the herb pair Danshen-Honghua and its single herbs by ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry.

PubMed

Qu, Cheng; Pu, Zong-Jin; Zhou, Gui-Sheng; Wang, Jun; Zhu, Zhen-Hua; Yue, Shi-Jun; Li, Jian-Ping; Shang, Li-Li; Tang, Yu-Ping; Shi, Xu-Qin; Liu, Pei; Guo, Jian-Ming; Sun, Jing; Tang, Zhi-Shu; Zhao, Jing; Zhao, Bu-Chang; Duan, Jin-Ao

2017-09-01

A sensitive, reliable, and powerful ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry method was developed for simultaneous quantification of the 15 main bio-active components including phenolic acids and flavonoids within 13 min for the first time. The proposed method was first reported and validated by good linearity (r 2  > 0.9975), limit of detection (1.12-7.01 ng/mL), limit of quantification (3.73-23.37 ng/mL), intra- and inter-day precisions (RSD ≤ 1.92%, RSD ≤ 2.45%), stability (RSD ≤ 5.63%), repeatability (RSD ≤ 4.34%), recovery (96.84-102.12%), and matrix effects (0.92-1.02). The established analytical methodology was successfully applied to comparative analysis of main bio-active components in the herb pair Danshen-Honghua and its single herbs. Compared to the single herb, the content of most flavonoid glycosides was remarkably increased in their herb pair, and main phenolic acids were decreased, conversely. The content changes of the main components in the herb pair supported the synergistic effects on promoting blood circulation and removing blood stasis. The results provide a scientific basis and reference for the quality control of Danshen-Honghua herb pair and the drug interactions based on variation of bio-active components in herb pairs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ion pair particles at the air–water interface

NASA Astrophysics Data System (ADS)

Kumar, Manoj; Francisco, Joseph S.

2017-11-01

Although the role of methanesulfonic acid (HMSA) in particle formation in the gas phase has been extensively studied, the details of the HMSA-induced ion pair particle formation at the air–water interface are yet to be examined. In this work, we have performed Born–Oppenheimer molecular dynamics simulations and density functional theory calculations to investigate the ion pair particle formation from HMSA and (R1)(R2)NH (for NH3, R1 = R2 = H; for CH3NH2, R1 = H and R2 = CH3; and for CH3NH2, R1 = R2 = CH3) at the air–water interface. The results show that, at the air–water interface, HMSA deprotonates within a few picoseconds and results in the formation of methanesulfonate ion (MSA‑)ṡṡH3O+ ion pair. However, this ion pair decomposes immediately, explaining why HMSA and water alone are not sufficient for forming stable particles in atmosphere. Interestingly, the particle formation from the gas-phase hydrogen-bonded complexes of HMSA with (R1)(R2)NH on the water droplet is observed with a few femtoseconds, suggesting a mechanism for the gas to particle conversion in aqueous environments. The reaction involves a direct proton transfer between HMSA and (R1)(R2)NH, and the resulting MSA‑ṡṡ(R1)(R2)NH2+ complex is bound by one to four interfacial water molecules. The mechanistic insights gained from this study may serve as useful leads for understanding about the ion pair particle formation from other precursors in forested and polluted urban environments.

Microresonators for Nonlinear Quantum Optics

NASA Astrophysics Data System (ADS)

Vernon, Zachary

In this thesis I study in detail the quantum dynamics of several nonlinear optical processes in microresonator systems. A Heisenberg-picture input-output formalism is developed from first principles that includes the effects of scattering losses and independent quality factors and coupling ratios for different resonances. The task of calculating the device output is then reduced to solving a set of driven, damped, ordinary differential equations for the resonator mode operators alone. This theoretical framework is used to study photon pair generation via spontaneous four-wave mixing in the weakly pumped regime, on which the effects of scattering losses are appraised. A more strongly driven regime is studied for continuous wave pumps, demonstrating when self- and cross-phase modulation and multi-photon pair generation become important, and their effects on the spectral and power scaling properties of the system are examined; A detuning strategy is presented that compensates for some of these effects. The results of the weak-pump regime are applied to study microresonator-based heralded single photon sources. The impact of scattering losses is studied, revealing that typical systems suffer from low heralding efficiency due to these losses. A technique to improve heralding efficiency is presented through over-coupling the resonator-channel system, and a resultant trade-off between heralding rate and heralding efficiency is uncovered. Limitations to the spectral purity of the heralded single photon output for conventional microresonator systems are also analysed, and a more sophisticated coupling scheme presented to overcome the upper bound for spectral purity of 93% that exists in typical systems, permitting the generation of single photons with spectral purity arbitrarily close to 100% without spectral filtering or sophisticated phase-matching techniques. The theory of quantum frequency conversion in microresonators using four-wave mixing is then developed in detail, and the spectral conversion probability and conversion efficiency studied. Efficiencies exceeding 90% using less than 100 mW of pump power are predicted to be achievable with current technology. A dressed mode picture is developed to better understand the conversion dynamics. Rabi-like spectral splitting and temporal oscillations of the intraresonator mean photon number are predicted, exhibiting a novel regime of strongly coupled photonic modes.

Local Structure Evolution and Modes of Charge Storage in Secondary Li–FeS 2 Cells

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

Butala, Megan M.; Mayo, Martin; Doan-Nguyen, Vicky V. T.

2017-03-27

In the pursuit of high-capacity electrochemical energy storage, a promising domain of research involves conversion reaction schemes, wherein electrode materials are fully transformed during charge and discharge. There are, however, numerous difficulties in realizing theoretical capacity and high rate capability in many conversion schemes. Here we employ operando studies to understand the conversion material FeS2, focusing on the local structure evolution of this relatively reversible material. X-ray absorption spectroscopy, pair distribution function analysis, and first-principles calculations of intermediate structures shed light on the mechanism of charge storage in the Li-FeS2 system, with some general principles emerging for charge storage inmore » chalcogenide materials. Focusing on second and later charge/discharge cycles, we find small, disordered domains that locally resemble Fe and Li2S at the end of the first discharge. Upon charge, this is converted to a Li-Fe-S composition whose local structure reveals tetrahedrally coordinated Fe. With continued charge, this ternary composition displays insertion extraction behavior at higher potentials and lower Li content. The finding of hybrid modes of charge storage, rather than simple conversion, points to the important role of intermediates that appear to store charge by mechanisms that more closely resemble intercalation.« less

Correlation between pairing initiation sites, recombination nodules and meiotic recombination in Sordaria macrospora.

PubMed

Zickler, D; Moreau, P J; Huynh, A D; Slezec, A M

1992-09-01

The decrease of meiotic exchanges (crossing over and conversion) in two mutants of Sordaria macrospora correlated strongly with a reduction of chiasmata and of both types of "recombination nodules." Serial section reconstruction electron microscopy was used to compare the synapsis pattern of meiotic prophase I in wild type and mutants. First, synapsis occurred but the number of synaptonemal complex initiation sites was reduced in both mutants. Second, this reduction was accompanied by, or resulted in, modifications of the pattern of synapsis. Genetic and synaptonemal complex maps were compared in three regions along one chromosome arm divided into well marked intervals. Reciprocal exchange frequencies and number of recombination nodules correlated in wild type in the three analyzed intervals, but disparity was found between the location of recombination nodules and exchanges in the mutants. Despite the twofold exchange decrease, sections of the genome such as the short arm of chromosome 2 and telomere regions were sheltered from nodule decrease and from pairing modifications. This indicated a certain amount of diversity in the control of these features and suggested that exchange frequency was dependent not only on the amount of effective pairing but also on the localization of the pairing sites, as revealed by the synaptonemal complex progression in the mutants.

Direct Generation and Detection of Quantum Correlated Photons with 3.2 um Wavelength Spacing.

PubMed

Sua, Yong Meng; Fan, Heng; Shahverdi, Amin; Chen, Jia-Yang; Huang, Yu-Ping

2017-12-13

Quantum correlated, highly non-degenerate photons can be used to synthesize disparate quantum nodes and link quantum processing over incompatible wavelengths, thereby constructing heterogeneous quantum systems for otherwise unattainable superior performance. Existing techniques for correlated photons have been concentrated in the visible and near-IR domains, with the photon pairs residing within one micron. Here, we demonstrate direct generation and detection of high-purity photon pairs at room temperature with 3.2 um wavelength spacing, one at 780 nm to match the rubidium D2 line, and the other at 3950 nm that falls in a transparent, low-scattering optical window for free space applications. The pairs are created via spontaneous parametric downconversion in a lithium niobate waveguide with specially designed geometry and periodic poling. The 780 nm photons are measured with a silicon avalanche photodiode, and the 3950 nm photons are measured with an upconversion photon detector using a similar waveguide, which attains 34% internal conversion efficiency. Quantum correlation measurement yields a high coincidence-to-accidental ratio of 54, which indicates the strong correlation with the extremely non-degenerate photon pairs. Our system bridges existing quantum technology to the challenging mid-IR regime, where unprecedented applications are expected in quantum metrology and sensing, quantum communications, medical diagnostics, and so on.

Real-time observation of formation and relaxation dynamics of NH4 in (CH3OH)m(NH3)n clusters.

PubMed

Yamada, Yuji; Nishino, Yoko; Fujihara, Akimasa; Ishikawa, Haruki; Fuke, Kiyokazu

2009-03-26

The formation and relaxation dynamics of NH4(CH3OH)m(NH3)n clusters produced by photolysis of ammonia-methanol mixed clusters has been observed by a time-resolved pump-probe method with femtosecond pulse lasers. From the detailed analysis of the time evolutions of the protonated cluster ions, NH4(+)(CH3OH)m(NH3)n, the kinetic model has been constructed, which consists of sequential three-step reaction: ultrafast hydrogen-atom transfer producing the radical pair (NH4-NH2)*, the relaxation process of radical-pair clusters, and dissociation of the solvated NH4 clusters. The initial hydrogen transfer hardly occurs between ammonia and methanol, implying the unfavorable formation of radical pair, (CH3OH2-NH2)*. The remarkable dependence of the time constants in each step on the number and composition of solvents has been explained by the following factors: hydrogen delocalization within the clusters, the internal conversion of the excited-state radical pair, and the stabilization of NH4 by solvation. The dependence of the time profiles on the probe wavelength is attributed to the different ionization efficiency of the NH4(CH3OH)m(NH3)n clusters.

Correlation between Pairing Initiation Sites, Recombination Nodules and Meiotic Recombination in Sordaria Macrospora

PubMed Central

Zickler, D.; Moreau, PJF.; Huynh, A. D.; Slezec, A. M.

1992-01-01

The decrease of meiotic exchanges (crossing over and conversion) in two mutants of Sordaria macrospora correlated strongly with a reduction of chiasmata and of both types of ``recombination nodules.'' Serial section reconstruction electron microscopy was used to compare the synapsis pattern of meiotic prophase I in wild type and mutants. First, synapsis occurred but the number of synaptonemal complex initiation sites was reduced in both mutants. Second, this reduction was accompanied by, or resulted in, modifications of the pattern of synapsis. Genetic and synaptonemal complex maps were compared in three regions along one chromosome arm divided into well marked intervals. Reciprocal exchange frequencies and number of recombination nodules correlated in wild type in the three analyzed intervals, but disparity was found between the location of recombination nodules and exchanges in the mutants. Despite the twofold exchange decrease, sections of the genome such as the short arm of chromosome 2 and telomere regions were sheltered from nodule decrease and from pairing modifications. This indicated a certain amount of diversity in the control of these features and suggested that exchange frequency was dependent not only on the amount of effective pairing but also on the localization of the pairing sites, as revealed by the synaptonemal complex progression in the mutants. PMID:1398050

Multiplicity of the 660-km discontinuity beneath the Izu-Bonin area

NASA Astrophysics Data System (ADS)

Zhou, Yuan-Ze; Yu, Xiang-Wei; Yang, Hui; Zang, Shao-Xian

2012-05-01

The relatively simple subducting slab geometry in the Izu-Bonin region provides a valuable opportunity to study the multiplicity of the 660-km discontinuity and the related response of the subducting slab on the discontinuity. Vertical short-period recordings of deep events with simple direct P phases beneath the Izu-Bonin region were retrieved from two seismic networks in the western USA and were used to study the structure of the 660-km discontinuity. After careful selection and pre-processing, 23 events from the networks, forming 32 pairs of event-network records, were processed. Related vespagrams were produced using the N-th root slant stack method for detecting weak down-going SdP phases that were inverted to the related conversion points. From depth histograms and the spatial distribution of the conversion points, there were three clear interfaces at depths of 670, 710 and 730 km. These interfaces were depressed approximately 20-30 km in the northern region. In the southern region, only two layers were identified in the depth histograms, and no obvious layered structure could be observed from the distribution of the conversion points.

Low phase noise microwave extraction from femtosecond laser by frequency conversion pair and IF-domain processing.

PubMed

Dai, Yitang; Cen, Qizhuang; Wang, Lei; Zhou, Yue; Yin, Feifei; Dai, Jian; Li, Jianqiang; Xu, Kun

2015-12-14

Extraction of a microwave component from a low-time-jitter femtosecond pulse train has been attractive for current generation of spectrally pure microwave. In order to avoid the transfer from the optical amplitude noise to microwave phase noise (AM-PM), we propose to down-convert the target component to intermediate frequency (IF) before the opto-electronic conversion. Due to the much lower carrier frequency, the AM-PM is greatly suppressed. The target is then recovered by up-conversion with the same microwave local oscillation (LO). As long as the time delay of the second LO matches that of the IF carrier, the phase noise of the LO shows no impact on the extraction process. The residual noise of the proposed extraction is analyzed in theory, which is also experimentally demonstrated as averagely around -155 dBc/Hz under offset frequency larger than 1 kHz when 10-GHz tone is extracted from a home-made femtosecond fiber laser. Large tunable extraction from 1 GHz to 10 GHz is also reported.

Ultrafast Electron Dynamics in Solar Energy Conversion.

PubMed

Ponseca, Carlito S; Chábera, Pavel; Uhlig, Jens; Persson, Petter; Sundström, Villy

2017-08-23

Electrons are the workhorses of solar energy conversion. Conversion of the energy of light to electricity in photovoltaics, or to energy-rich molecules (solar fuel) through photocatalytic processes, invariably starts with photoinduced generation of energy-rich electrons. The harvesting of these electrons in practical devices rests on a series of electron transfer processes whose dynamics and efficiencies determine the function of materials and devices. To capture the energy of a photogenerated electron-hole pair in a solar cell material, charges of opposite sign have to be separated against electrostatic attractions, prevented from recombining and being transported through the active material to electrodes where they can be extracted. In photocatalytic solar fuel production, these electron processes are coupled to chemical reactions leading to storage of the energy of light in chemical bonds. With the focus on the ultrafast time scale, we here discuss the light-induced electron processes underlying the function of several molecular and hybrid materials currently under development for solar energy applications in dye or quantum dot-sensitized solar cells, polymer-fullerene polymer solar cells, organometal halide perovskite solar cells, and finally some photocatalytic systems.

Scalable 3D image conversion and ergonomic evaluation

NASA Astrophysics Data System (ADS)

Kishi, Shinsuke; Kim, Sang Hyun; Shibata, Takashi; Kawai, Takashi; Häkkinen, Jukka; Takatalo, Jari; Nyman, Göte

2008-02-01

Digital 3D cinema has recently become popular and a number of high-quality 3D films have been produced. However, in contrast with advances in 3D display technology, it has been pointed out that there is a lack of suitable 3D content and content creators. Since 3D display methods and viewing environments vary widely, there is expectation that high-quality content will be multi-purposed. On the other hand, there is increasing interest in the bio-medical effects of image content of various types and there are moves toward international standardization, so 3D content production needs to take into consideration safety and conformity with international guidelines. The aim of the authors' research is to contribute to the production and application of 3D content that is safe and comfortable to watch by developing a scalable 3D conversion technology. In this paper, the authors focus on the process of changing the screen size, examining a conversion algorithm and its effectiveness. The authors evaluated the visual load imposed during the viewing of various 3D content converted by the prototype algorithm as compared with ideal conditions and with content expanded without conversion. Sheffe's paired comparison method was used for evaluation. To examine the effects of screen size reduction on viewers, changes in user impression and experience were elucidated using the IBQ methodology. The results of the evaluation are presented along with a discussion of the effectiveness and potential of the developed scalable 3D conversion algorithm and future research tasks.

Table talk: How mothers and adolescents across socioeconomic status discuss food.

PubMed

Fielding-Singh, Priya; Wang, Jennifer

2017-08-01

This article reports findings from a qualitative study of food practices among families of differing socioeconomic circumstances. Using in-depth interviews from sixty-two families in the San Francisco Bay Area in 2015-2016, we find socioeconomic differences in how mothers and adolescents talk about food. Across SES, mothers and adolescents engage in discussions about healthy eating. However, these conversations are more commonplace and embedded within high-SES family life than among low-SES families. Beyond conversations about 1) healthy eating, the topics of 2) food quality and 3) price are discussed to varying degrees across SES. Within high-SES families, frequent discussions of healthy eating are paired with dialogue highlighting the importance of consuming higher quality food. Price is largely absent as a topic of conversation among high-SES families. On the other end of the socioeconomic spectrum, low-SES mothers and adolescents frequently engage in conversations about price when discussing food. Mentions of food quality are rare, but when they do occur, they underscore important trade-offs between food's healthiness, quality and price. Given prior research showing the impact of dialogue between parents and adolescents on adolescents' dietary behaviors, these findings help us understand how family discussions contribute to shaping adolescents' approaches to food. An important implication is that high-SES families' discussions of food quality may strengthen messages about healthy eating, while conversations about affordability within low-SES families may highlight financial barriers to healthy eating. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fine-scale mergers of chloroplast and mitochondrial genes create functional, transcompartmentally chimeric mitochondrial genes.

PubMed

Hao, Weilong; Palmer, Jeffrey D

2009-09-29

The mitochondrial genomes of flowering plants possess a promiscuous proclivity for taking up sequences from the chloroplast genome. All characterized chloroplast integrants exist apart from native mitochondrial genes, and only a few, involving chloroplast tRNA genes that have functionally supplanted their mitochondrial counterparts, appear to be of functional consequence. We developed a novel computational approach to search for homologous recombination (gene conversion) in a large number of sequences and applied it to 22 mitochondrial and chloroplast gene pairs, which last shared common ancestry some 2 billion years ago. We found evidence of recurrent conversion of short patches of mitochondrial genes by chloroplast homologs during angiosperm evolution, but no evidence of gene conversion in the opposite direction. All 9 putative conversion events involve the atp1/atpA gene encoding the alpha subunit of ATP synthase, which is unusually well conserved between the 2 organelles and the only shared gene that is widely sequenced across plant mitochondria. Moreover, all conversions were limited to the 2 regions of greatest nucleotide and amino acid conservation of atp1/atpA. These observations probably reflect constraints operating on both the occurrence and fixation of recombination between ancient homologs. These findings indicate that recombination between anciently related sequences is more frequent than previously appreciated and creates functional mitochondrial genes of chimeric origin. These results also have implications for the widespread use of mitochondrial atp1 in phylogeny reconstruction.

Remote sensing analysis of vegetation recovery following short-interval fires in Southern California shrublands.

PubMed

Meng, Ran; Dennison, Philip E; D'Antonio, Carla M; Moritz, Max A

2014-01-01

Increased fire frequency has been shown to promote alien plant invasions in the western United States, resulting in persistent vegetation type change. Short interval fires are widely considered to be detrimental to reestablishment of shrub species in southern California chaparral, facilitating the invasion of exotic annuals and producing "type conversion". However, supporting evidence for type conversion has largely been at local, site scales and over short post-fire time scales. Type conversion has not been shown to be persistent or widespread in chaparral, and past range improvement studies present evidence that chaparral type conversion may be difficult and a relatively rare phenomenon across the landscape. With the aid of remote sensing data covering coastal southern California and a historical wildfire dataset, the effects of short interval fires (<8 years) on chaparral recovery were evaluated by comparing areas that burned twice to adjacent areas burned only once. Twelve pairs of once- and twice-burned areas were compared using normalized burn ratio (NBR) distributions. Correlations between measures of recovery and explanatory factors (fire history, climate and elevation) were analyzed by linear regression. Reduced vegetation cover was found in some lower elevation areas that were burned twice in short interval fires, where non-sprouting species are more common. However, extensive type conversion of chaparral to grassland was not evident in this study. Most variables, with the exception of elevation, were moderately or poorly correlated with differences in vegetation recovery.

Reading: Interaction With Memory

DTIC Science & Technology

1993-12-15

Ken Baime to Gregory Ward in conversation, August 8. 1990) 37. 1 used a gautter person before. but just to clean them. (Julia Hirschberg in...second of two items in a Ken Church was extremely generous with his ideas and his time in providing us with a large list of possible stimuli and their...target. For these pairs, we expected to replicate materials included words of the 48 triples from Balota and Loach McNamara and Altarriba’s finding of a

Impact of Communication Competency Training on Nursing Students' Self-advocacy Skills.

PubMed

Doherty, Christi; Landry, Heidi; Pate, Barbara; Reid, Helen

2016-01-01

Deficiencies in nursing students' communication skills need to be addressed for students to influence and skillfully collaborate in crucial patient and self-advocacy conversations. This study evaluated the effectiveness of a communication competency educational program for nursing students (N = 61). A paired-sample t test determined that there was a statistical significance from pre to post intervention, indicating the importance of communication competency education for nursing students' ability to advocate for themselves and their patients.

SWCNT Photocatalyst for Hydrogen Production from Water upon Photoexcitation of (8, 3) SWCNT at 680-nm Light

NASA Astrophysics Data System (ADS)

Murakami, Noritake; Tango, Yuto; Miyake, Hideaki; Tajima, Tomoyuki; Nishina, Yuta; Kurashige, Wataru; Negishi, Yuichi; Takaguchi, Yutaka

2017-03-01

Single-walled carbon nanotubes (SWCNTs) are potentially strong optical absorbers with tunable absorption bands depending on their chiral indices (n, m). Their application for solar energy conversion is difficult because of the large binding energy (>100 meV) of electron-hole pairs, known as excitons, produced by optical absorption. Recent development of photovoltaic devices based on SWCNTs as light-absorbing components have shown that the creation of heterojunctions by pairing chirality-controlled SWCNTs with C60 is the key for high power conversion efficiency. In contrast to thin film devices, photocatalytic reactions in a dispersion/solution system triggered by the photoexcitation of SWCNTs have never been reported due to the difficulty of the construction of a well-ordered surface on SWCNTs. Here, we show a clear-cut example of a SWCNT photocatalyst producing H2 from water. Self-organization of a fullerodendron on the SWCNT core affords water-dispersible coaxial nanowires possessing SWCNT/C60 heterojunctions, of which a dendron shell can act as support of a co-catalyst for H2 evolution. Because the band offset between the LUMO levels of (8, 3)SWCNT and C60 satisfactorily exceeds the exciton binding energy to allow efficient exciton dissociation, the (8, 3)SWCNT/fullerodendron coaxial photocatalyst shows H2-evolving activity (QY = 0.015) upon 680-nm illumination, which is E22 absorption of (8, 3) SWCNT.

In vitro extinction learning in Hermissenda: involvement of conditioned inhibition molecules

PubMed Central

Cavallo, Joel S.; Hamilton, Brittany N.; Farley, Joseph

2014-01-01

Extinction of a conditioned association is typically viewed as the establishment of new learning rather than the erasure of the original memory. However, recent research in the nudibranch, Hermissenda crassicornis (H.c.) demonstrated that extinction training (using repeated light-alone presentations) given 15 min, but not 23 h, after memory acquisition reversed both the cellular correlates of learning (enhanced Type B cell excitability) and the behavioral changes (reduced phototaxis) produced by associative conditioning (pairings of light, CS, and rotation, US). Here, we investigated the putative molecular signaling pathways that underlie this extinction in H.c. by using a novel in vitro protocol combined with pharmacological manipulations. After intact H.c. received either light-rotation pairings (Paired), random presentations of light and rotation (Random), or no stimulation (Untrained), B cells from isolated CNSs were recorded from during exposure to extinction training consisting of two series of 15 consecutive light-steps (LSs). When in vitro extinction was administered shortly (2 h, but not 24 h) after paired training, B cells from Paired animals showed progressive and robust declines in spike frequency by the 30th LS, while control cells (Random and Untrained) did not. We found that several molecules implicated in H.c. conditioned inhibitory (CI) learning, protein phosphatase 1 (PP1) and arachidonic acid (AA)/12-lipoxygenase (12-LOX) metabolites, also contributed to the spike frequency decreases produced by in vitro extinction. Protein phosphatase 2B (PP2B) also appeared to play a role. Calyculin A (PP1 inhibitor), cyclosporin A (PP2B inhibitor), and baicalein (a 12-LOX inhibitor) all blocked the spike frequency declines in Paired B cells produced by 30 LSs. Conversely, injection of catalytically-active PP1 (caPP1) or PP2B (caPP2B) into Untrained B cells partially mimicked the spike frequency declines observed in Paired cells, as did bath-applied AA, and occluded additional LS-produced reductions in spiking in Paired cells. PMID:25374517

Mother-Child Conversation and Children's Social Understanding During Middle Childhood.

PubMed

Pearson, RaeAnne M; Pillow, Bradford H

2016-01-01

The authors investigated the relationship between mother-child conversation and children's social understanding during middle childhood. Thirty-eight mother-child pairs participated, including a younger group (5-7 years old) and an older group (8-10 years old). Children completed 2 measures of social understanding and mothers and children discussed 4 stories involving social dilemmas. Results indicated that compared to the younger group, the older group (a) performed better on both measures of social understanding and (b) produced more basic mental talk (i.e., talk about beliefs, emotions, personality traits, and desires), and more advanced mental talk (i.e., talk about contrasting perspectives, recursion and relationship between mental states, and advanced emotions). Mothers of older children also produced more basic and advanced mental talk. Mothers' advanced mental talk predicted both children's social understanding and children's advanced mental talk.

A circular polarization converter based on in-linked loop antenna frequency selective surface

NASA Astrophysics Data System (ADS)

Wang, Shen-Yun; Liu, Wei; Geyi, Wen

2018-06-01

In this paper, we report the design, fabrication and measurement of a circular polarization converter based on an in-linked loop-antenna frequency selective surface. The building unit cell is the in-linked loop-antenna module, which consists of same front and back planar loop antennas in-linked by a pair of through-via holes passing through a sandwiched perforated metal ground plane. The proposed device can achieve transmission polarization conversions from right- or left-handed circularly polarized waves to left- or right-handed ones, respectively, or vice versa. Simulation and experimental results show that it has relative conversion ratio of near unity at resonant frequency and very low Joule insertion loss in the operating frequency band. The proposed circular polarization converter may be applied to wireless systems where circular polarization diversity is needed.

Structural determinants in the bulk heterojunction.

PubMed

Acocella, Angela; Höfinger, Siegfried; Haunschmid, Ernst; Pop, Sergiu C; Narumi, Tetsu; Yasuoka, Kenji; Yasui, Masato; Zerbetto, Francesco

2018-02-21

Photovoltaics is one of the key areas in renewable energy research with remarkable progress made every year. Here we consider the case of a photoactive material and study its structural composition and the resulting consequences for the fundamental processes driving solar energy conversion. A multiscale approach is used to characterize essential molecular properties of the light-absorbing layer. A selection of bulk-representative pairs of donor/acceptor molecules is extracted from the molecular dynamics simulation of the bulk heterojunction and analyzed at increasing levels of detail. Significantly increased ground state energies together with an array of additional structural characteristics are identified that all point towards an auxiliary role of the material's structural organization in mediating charge-transfer and -separation. Mechanistic studies of the type presented here can provide important insights into fundamental principles governing solar energy conversion in next-generation photovoltaic devices.

Ultrabright, narrow-band photon-pair source for atomic quantum memories

NASA Astrophysics Data System (ADS)

Tsai, Pin-Ju; Chen, Ying-Cheng

2018-06-01

We demonstrate an ultrabright, narrow-band and frequency-tunable photon-pair source based on cavity-enhanced spontaneous parametric down conversion (SPDC) which is compatible with atomic transition of rubidium D 2-line (780 nm) or cesium D 2-line (852 nm). With the pump beam alternating between a high and a low power phase, the output is switching between the optical parametric oscillator (OPO) and photon-pair generation mode. We utilize the OPO output light to lock the cavity length to maintain the double resonances of signal and idler, as well as to lock the signal frequency to cesium atomic transition. With a type-II phase matching and a double-passed pump scheme such that the cluster frequency spacing is larger than the SPDC bandwidth, the photon-pair output is in a nearly single-mode operation as confirmed by a scanning Fabry–Perot interferometer with its output detected by a photomultiplier. The achieved generation and detection rates are 7.24× {10}5 and 6142 s‑1 mW‑1, respectively. The correlation time of the photon pair is 21.6(2.2) ns, corresponding to a bandwidth of 2π × 6.6(6) MHz. The spectral brightness is 1.06× {10}5 s‑1 mW‑1 MHz‑1. This is a relatively high value under a single-mode operation with the cavity-SPDC scheme. The generated single photons can be readily used in experiments related to atomic quantum memories.

Self-healing of quantum entanglement after an obstruction.

PubMed

McLaren, Melanie; Mhlanga, Thandeka; Padgett, Miles J; Roux, Filippus S; Forbes, Andrew

2014-01-01

Quantum entanglement between photon pairs is fragile and can easily be masked by losses in transmission path and noise in the detection system. When observing the quantum entanglement between the spatial states of photon pairs produced by parametric down-conversion, the presence of an obstruction introduces losses that can mask the correlations associated with the entanglement. Here we show that we can overcome these losses by measuring in the Bessel basis, thus once again revealing the entanglement after propagation beyond the obstruction. We confirm that, for the entanglement of orbital angular momentum, measurement in the Bessel basis is more robust to these losses than measuring in the usually employed Laguerre-Gaussian basis. Our results show that appropriate choice of measurement basis can overcome some limitations of the transmission path, perhaps offering advantages in free-space quantum communication or quantum processing systems.

Controlling the superconducting transition by spin-orbit coupling

NASA Astrophysics Data System (ADS)

Banerjee, N.; Ouassou, J. A.; Zhu, Y.; Stelmashenko, N. A.; Linder, J.; Blamire, M. G.

2018-05-01

Whereas considerable evidence exists for the conversion of singlet Cooper pairs into triplet Cooper pairs in the presence of inhomogeneous magnetic fields, recent theoretical proposals have suggested an alternative way to exert control over triplet generation: intrinsic spin-orbit coupling in a homogeneous ferromagnet coupled to a superconductor. Here, we proximity couple Nb to an asymmetric Pt/Co/Pt trilayer, which acts as an effective spin-orbit-coupled ferromagnet owing to structural inversion asymmetry. Unconventional modulation of the superconducting critical temperature as a function of in-plane and out-of-plane applied magnetic fields suggests the presence of triplets that can be controlled by the magnetic orientation of a single homogeneous ferromagnet. Our studies demonstrate an active role of spin-orbit coupling in controlling the triplets, an important step towards the realization of novel superconducting spintronic devices.

Characterisation and comparison of event generators for pair conversion: A crucial step for future low energy gamma telescope

NASA Astrophysics Data System (ADS)

Gros, P.; Bernard, D.

2017-05-01

Gamma ray astronomy suffers from a sensitivity gap between 0.1 and 100Mev. With high angular resolution for the electrons, it will also be possible to probe the linear polarisation of the photons. An accurate simulation is necessary to correctly design and compare these detectors. We establish baseline distributions of key kinematic variables as simulated by a 5D, exact down to threshold, and polarised event generator. We compare them to simulations with the low energy electromagnetic models available in Geant4 and in EGS5. We show that different generators give a different picture of the optimal angular resolution of pair telescopes. We also show that, of all the simulations we used, only the full 5D generator describes accurately the angular asymmetry in the case of polarised photons.

The positron peak puzzle - Recent results from APEX

DOE PAGES

Ahmad, I; Austin, SM; Back, BB; ...

1996-01-01

Results are presented from a new experiment, APEX, designed to study the previously reported sharp lines in sum-energy spectra of positrons and electrons produced in collisions of very heavy ions. Data have been collected for 238U + 181Ta and 238U + 232Th. No evidence is found for narrow structures similar to those previously reported. For the specific case of the isolated decay of a neutral particle of mass 1.4–2.1 MeV/c 2, the upper limits on cross sections obtained are significantly less than previously reported. Data are also presented for internal pair conversion in 206Pb. These results are used to setmore » limits for the possible contribution to the pair yield of a 1780 keV transition in 238U observed in heavy-ion gamma-ray coincidence measurements.« less

The effect of green tea extract supplementation on sputum smear conversion and weight changes in pulmonary TB patients: A randomized controlled trial

PubMed Central

Honarvar, Mohammad Reza; Eghtesadi, Shahryar; Gill, Pooria; Jazayeri, Shima; Vakili, Mohammad Ali; Shamsardekani, Mohammad Reza; Abbasi, Abdollah

2016-01-01

Background: Acceleration in sputum smear conversion helps faster improvement and decreased probability of the transfer of TB. In this study, we aimed to investigate the effect of green tea extract supplementation on sputum smear conversion and weight changes in smear positive pulmonary TB patients in Iran. Methods: In this double blind clinical study, TB patients were divided into intervention, (n=43) receiving 500 mg green tea extract (GTE), and control groups (n=40) receiving placebo for two months, using balanced randomization. Random allocation and allocation concealment were observed. Height and weight were measured at the beginning, and two and six months post-treatment. Evaluations were performed on three slides, using the ZiehlNeelsen method. Independent and paired t test, McNemar’s, Wilcoxon, Kaplan-Meier, Cox regression model and Log-Rank test were utilized. Statistical significance was set at p<0.05. This trial was registered under IRCT201212232602N11. Results: The interventional changes and the interactive effect of intervention on weight were not significant (p>0.05). In terms of shortening the duration of conversion, the case to control proportion showed a significant difference (p=0.032). Based on the Cox regression model, the hazard ratio of the relative risk of delay in sputum smear conversion was 3.7 (p=0.002) in the higher microbial load group compared to the placebo group and 0.54 (95% CI: 0.31-0.94) in the intervention compared to the placebo group. Conclusion: GTE decreases the risk of delay in sputum smear conversion, but has no effect on weight gain. Moreover, it may be used as an adjuvant therapy for faster rehabilitation for pulmonary TB patients. PMID:27493925

Estimating historical respirable crystalline silica exposures for Chinese pottery workers and iron/copper, tin, and tungsten miners.

PubMed

Zhuang, Z; Hearl, F J; Odencrantz, J; Chen, W; Chen, B T; Chen, J Q; McCawley, M A; Gao, P; Soderholm, S C

2001-11-01

Collaborative studies of Chinese workers, using over four decades of dust monitoring data, are being conducted by the National Institute for Occupational Safety and Health (NIOSH) and Tongji Medical University in China. The goal of these projects is to establish exposure-response relationships for the development of diseases such as silicosis or lung cancer in cohorts of pottery and mine workers. It is necessary to convert Chinese dust measurements to respirable silica measurements in order to make results from the Chinese data comparable to other results in the literature. This article describes the development of conversion factors and estimates of historical respirable crystalline silica exposure for Chinese workers. Ambient total dust concentrations (n>17000) and crystalline silica concentrations (n=347) in bulk dust were first gathered from historical industrial hygiene records. Analysis of the silica content in historical bulk samples revealed no trend from 1950 up to the present. During 1988-1989, side-by-side airborne dust samples (n=143 pairs) were collected using nylon cyclones and traditional Chinese samplers in 20 metal mines and nine pottery factories in China. These data were used to establish conversion factors between respirable crystalline silica concentrations and Chinese total dust concentrations. Based on the analysis of the available evidence, conversion factors derived from the 1988-1989 sampling campaign are assumed to apply to other time periods in this paper. The conversion factors were estimated to be 0.0143 for iron/copper, 0.0355 for pottery factories, 0.0429 for tin mines, and 0.0861 for tungsten mines. Conversion factors for individual facilities within each industry were also calculated. Analysis of variance revealed that mean conversion factors are significantly different among facilities within the iron/copper industry and within the pottery industry. The relative merits of using facility-specific conversion factors, industry-wide conversion factors, or a weighted average of the two are discussed. The exposure matrix of the historical Chinese total dust concentrations was multiplied by these conversion factors to obtain an exposure matrix of historical respirable crystalline silica concentrations.

Extremely Efficient Multiple Electron-hole Pair Generation in Carbon Nanotube Photodiodes

NASA Astrophysics Data System (ADS)

Gabor, Nathaniel

2010-03-01

The efficient generation of multiple electron-hole (e-h) pairs from a single photon could improve the efficiency of photovoltaic solar cells beyond standard thermodynamic limits [1] and has been the focus of much recent work in semiconductor nanomaterials [2,3]. In single walled carbon nanotubes (SWNTs), the small Fermi velocity and low dielectric constant suggests that electron-electron interactions are very strong and that high-energy carriers should efficiently generate e-h pairs. Here, I will discuss observations of highly efficient generation of e-h pairs due to impact excitation in SWNT p-n junction photodiodes [4]. To investigate optoelectronic transport properties of individual SWNT photodiodes, we focus a laser beam over the device while monitoring the electronic characteristics. Optical excitation into the second electronic subband E22 ˜ 2 EGAP leads to striking photocurrent steps in the device I-VSD characteristics that occur at voltage intervals of the band gap energy EGAP/ e. Spatially and spectrally resolved photocurrent combined with temperature-dependent studies suggest that these steps result from efficient generation of multiple e-h pairs from a single hot E22 carrier. We conclude that in the SWNT photodiode, a single photon with energy greater than 2EGAP is converted into multiple e-h pairs, leading to enhanced photocurrent and increased photo-conversion efficiency. [1] W. Shockley, and H. J. Queisser, Journal of Applied Physics 32, 510 (1961). [2] R. D. Schaller, and V. I. Klimov, Physical Review Letters 92 (18), 186601 (2004). [3] R. J. Ellingson, et al, Nano Letters, 5 (5), 865-871 (2005). [4] Nathaniel M. Gabor, Zhaohui Zhong, Ken Bosnick, Jiwoong Park, and Paul McEuen, Science, 325, 1367 (2009).

Supernova 2007bi as a pair-instability explosion.

PubMed

Gal-Yam, A; Mazzali, P; Ofek, E O; Nugent, P E; Kulkarni, S R; Kasliwal, M M; Quimby, R M; Filippenko, A V; Cenko, S B; Chornock, R; Waldman, R; Kasen, D; Sullivan, M; Beshore, E C; Drake, A J; Thomas, R C; Bloom, J S; Poznanski, D; Miller, A A; Foley, R J; Silverman, J M; Arcavi, I; Ellis, R S; Deng, J

2009-12-03

Stars with initial masses such that 10M[symbol: see text] or= 140M[symbol: see text] (if such exist) develop oxygen cores with masses, M(core), that exceed 50M[symbol: see text], where high temperatures are reached at relatively low densities. Conversion of energetic, pressure-supporting photons into electron-positron pairs occurs before oxygen ignition and leads to a violent contraction which triggers a nuclear explosion that unbinds the star in a pair-instability supernova. Transitional objects with 100M[symbol: see text] < M(initial) < 140M[symbol: see text] may end up as iron-core-collapse supernovae following violent mass ejections, perhaps as a result of brief episodes of pair instability, and may already have been identified. Here we report observations of supernova SN 2007bi, a luminous, slowly evolving object located within a dwarf galaxy. We estimate the exploding core mass to be M(core) approximately 100M[symbol: see text], in which case theory unambiguously predicts a pair-instability supernova. We show that >3M[symbol: see text] of radioactive (56)Ni was synthesized during the explosion and that our observations are well fitted by models of pair-instability supernovae. This indicates that nearby dwarf galaxies probably host extremely massive stars, above the apparent Galactic stellar mass limit, which perhaps result from processes similar to those that created the first stars in the Universe.

Irreversible Catalyst Activation Enables Hyperpolarization and Water Solubility for NMR Signal Amplification by Reversible Exchange

DTIC Science & Technology

2016-09-12

Phys. Rev. Lett. 1986 , 57, 2645−2648. (8) Goldman, M.; Johannesson, H. Conversion of a Proton Pair Para Order into C-13 Polarization by Rf...A.; Harris, K.; Batchelder, L. S.; Bhattacharya, P.; Ross , B. D.; Weitekamp, D. P. PASADENA Hyperpolarization of Succinic Acid for MRI and NMR...Bhattacharya, P.; Chekmenev, E. Y.; Perman, W. H.; Harris, K. C.; Lin, A. P.; Norton, V. A.; Tan, C. T.; Ross , B. D.; Weitekamp, D. P. Towards

Catalytic Gas-Phase Glycerol Processing over SiO2-, Cu-, Ni- and Fe- Supported Au Nanoparticles

PubMed Central

Kapkowski, Maciej; Siudyga, Tomasz; Sitko, Rafal; Lelątko, Józef; Szade, Jacek; Balin, Katarzyna; Klimontko, Joanna; Bartczak, Piotr; Polanski, Jaroslaw

2015-01-01

In this study, we investigated different metal pairings of Au nanoparticles (NPs) as potential catalysts for glycerol dehydration for the first time. All of the systems preferred the formation of hydroxyacetone (HYNE). Although the bimetallics that were tested, i.e., Au NPs supported on Ni, Fe and Cu appeared to be more active than the Au/SiO2 system, only Cu supported Au NPs gave high conversion (ca. 63%) and selectivity (ca. 70%) to HYNE. PMID:26580400

Machine Learning Techniques for Persuasion Detection in Conversation

DTIC Science & Technology

2010-06-01

files maintained the original post and tile ordering within each transcript. These files were each internally shuffled prior to creating test and...of the number of post or tiles. The other 90% was used for training data. Each post and each tile appeared in only one of the 10 test sets. Each post ...concatenating 5 test sets and pairing it with the 6th test set. This process was conducted for both posts and tiles. The shortest transcript (19 posts , 0 tiles

"Yes, and …" Exploring the Future of Learning Analytics in Medical Education.

PubMed

Cirigliano, Matt M; Guthrie, Charlie; Pusic, Martin V; Cianciolo, Anna T; Lim-Dunham, Jennifer E; Spickard, Anderson; Terry, Valerie

2017-01-01

This Conversations Starter article presents a selected research abstract from the 2017 Association of American Medical Colleges Northeastern Region Group on Educational Affairs annual spring meeting. The abstract is paired with the integrative commentary of three experts who shared their thoughts stimulated by the study. Commentators brainstormed "what's next" with learning analytics in medical education, including advancements in interaction metrics and the use of interactivity analysis to deepen understanding of perceptual, cognitive, and social learning and transfer processes.

Broadband asymmetric transmission of linearly polarized electromagnetic waves based on chiral metamaterial

NASA Astrophysics Data System (ADS)

Stephen, Lincy; Yogesh, N.; Subramanian, V.

2018-01-01

The giant optical activity of chiral metamaterials (CMMs) holds great potential for tailoring the polarization state of an electromagnetic (EM) wave. In controlling the polarization state, the aspect of asymmetric transmission (AT), where a medium allows the EM radiation to pass through in one direction while restricting it in the opposite direction, adds additional degrees of freedom such as one-way channelling functionality. In this work, a CMM formed by a pair of mutually twisted slanted complementary metal strips is realized for broadband AT accompanied with cross-polarization (CP) conversion for linearly polarized EM waves. Numerically, the proposed ultra-thin (˜λ/42) CMM shows broadband AT from 8.58 GHz to 9.73 GHz (bandwidth of 1.15 GHz) accompanied with CP transmission magnitude greater than 0.9. The transmission and reflection spectra reveal the origin of the asymmetric transmission as the direction sensitive cross polarization conversion and anisotropic electric coupling occurring in the structure which is then elaborated with the surface current analysis and electric field distribution within the structure. An experiment is carried out to verify the broadband AT based CP conversion of the proposed CMM at microwave frequencies, and a reliable agreement between numerical and experimental results is obtained. Being ultra-thin, the reported broadband AT based CP conversion of the proposed CMM is useful for controlling radiation patterns in non-reciprocal EM devices and communication networks.

Consequences of buffelgrass pasture development for primary productivity, perennial plant richness, and vegetation structure in the drylands of Sonora, Mexico.

PubMed

Franklin, Kimberly; Molina-Freaner, Francisco

2010-12-01

In large parts of northern Mexico native plant communities are being converted to non-native buffelgrass (Pennisetum ciliare) pastures, and this conversion could fundamentally alter primary productivity and species richness. In Sonora, Mexico land conversion is occurring at a regional scale along a rainfall-driven gradient of primary productivity, across which native plant communities transition from desert scrub to thorn scrub. We used a paired sampling design to compare a satellite-derived index of primary productivity, richness of perennial plant species, and canopy-height profiles of native plant communities with buffelgrass pastures. We sampled species richness across a gradient of primary productivity in desert scrub and thorn scrub vegetation to examine the influence of site productivity on the outcomes of land conversion. We also examined the influence of pasture age on species richness of perennial plants. Index values of primary productivity were lower in buffelgrass pastures than in native vegetation, which suggests a reduction in primary productivity. Land conversion reduced species richness by approximately 50% at local and regional scales, reduced tree and shrub cover by 78%, and reduced canopy height. Land conversion disproportionately reduced shrub species richness, which reflects the common practice among Sonoran ranchers of conserving certain tree and cactus species. Site productivity did not affect the outcomes of land conversion. The age of a buffelgrass pasture was unrelated to species richness within the pasture, which suggests that passive recovery of species richness to preconversion levels is unlikely. Our findings demonstrate that land conversion can result in large losses of plant species richness at local and regional scales and in substantial changes to primary productivity and vegetation structure, which casts doubt on the feasibility of restoring native plant communities without active intervention on the part of land managers. © 2010 Society for Conservation Biology.

Electric Monopole Transition Strengths in the Stable Nickel Isotopes

NASA Astrophysics Data System (ADS)

Evitts, Lee John

A series of measurements of stable nickel isotopes were performed at the Australian National University in Canberra. Excited states in 58,60,62Ni were populated via inelastic scattering of proton beams delivered by the 14UD Pelletron accelerator. Multiple setups were used in order to determine the structure of low-lying states. The CAESAR array of Compton-suppressed HPGe detectors was used to measure the (E2/M1) mixing ratio of transitions from angular distributions of gamma rays. The Super-e spectrometer was used to measure conversion coefficients for a number of J to J transitions. The data obtained from both devices was combined with previously measured parent lifetimes and branching ratios to determine E0 transition strengths between J-pi transitions. The E0 transition strength for the second 0+ to first 0+ transitions in 60,62Ni have been measured for the first time through internal conversion electron detection. The experimental value of 132(+59,-70) for 62Ni agrees within 2 sigma of the previous result obtained from internal pair formation. However it is likely that the previous experimental results used an outdated theoretical model for internal pair formation emission. This work also represents the first measurements of E0 transition strengths between 2+ states in Ni isotopes. There is generally large E0 strength between the 2+ states, particularly in the second 2+ to first 2+ transition, however there is also a large uncertainty in the measurements owing to the difficulties involved in measuring conversion coefficients. In 62Ni, the E0 transition strength of 172(+62,-77) for the second 2+ to first 2+ transition gives further weight to the argument against the spherical vibrator model, as an E0 transition is forbidden if there is a change of only one phonon. The large measurement also indicates the presence of shape coexistence, complementing the recent experimental work carried out in the neutron-rich Ni isotopes.

Learning to Teach as Situated Learning: An Examination of Student Teachers as Legitimate Peripheral Participants in Cooperating Teachers' Classrooms

NASA Astrophysics Data System (ADS)

McDonald, Eric J.

Learning to teach science well is a complex endeavor and student teaching provides a time for emerging teachers to learn how to reason in this uncertain landscape. Many pre-service teachers have rated student teaching as a very important part of their teacher education program (Koerner, Rust, & Baumgartner, 2002; Levine, 2006) and there is little doubt that this aspect of teacher preparation has a great impact (Wilson, Floden, Ferrinin-Mundy, 2001). It is surprising, therefore, that the interaction between the cooperating teacher and student teacher represents a gap in the literature (Cochran-Smith & Zeichner, 2005). In fact, little effort has been made in science education "to understand the contributions of cooperating teachers and teacher educators" (p. 322). Research is needed into not only how teacher preparation programs can help pre-service teachers make this transition from student teacher to effective teacher but also how the expertise of the cooperating teacher can be a better articulated part of the development of the student teacher. This instrumental case study examines the nature and substance of the cooperating teacher/student teacher conversations and the changes in those conversations over time. Using the theoretical framework of situated learning (Lave & Wenger, 1991; Lave, 1996) the movement of the student teacher from their position on the periphery of practice toward a more central role is examined. Three cooperating teacher/student teacher pairs provided insight into this important time with case data coming from pre and post interviews, baseline surveys, weekly update surveys, and recorded conversations from the pair during their time together. Four major themes emerged from the cases and from cross case comparisons with implications for student teachers regarding how they react to greater responsibility, cooperating teachers regarding how they give access to the community of practice, and the teacher preparation community regarding the role it plays in helping to facilitate this process.

Precise measurement of spin-averaged {chi}{sub cJ}(1P) mass using photon conversions in {psi}(2S){yields}{gamma}{chi}{sub cJ}

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

Ablikim, M.; Bai, J.Z.; Bian, J.G.

2005-05-01

Using photon conversions to e{sup +}e{sup -} pairs, the energy spectrum of inclusive photons from {psi}(2S) radiative decays is measured with photon energy resolution ({sigma}{sub E{sub {gamma}}}) in the range from 2.3 to 3.8 MeV by BESII at the Beijing Electron-Positron Collider. The {chi}{sub cJ}(1P) states (J=0,1,2) are clearly observed, and their masses and the spin-averaged {chi}{sub cJ} mass are determined to be M{sub {chi}{sub c}{sub 0}}=3414.21{+-}0.39{+-}0.27, M{sub {chi}{sub c}{sub 1}}=3510.30{+-}0.14{+-}0.16, M{sub {chi}{sub c}{sub 2}}=3555.70{+-}0.59{+-}0.39, and M({sup 3}P{sub cog})=3524.85{+-}0.32{+-}0.30 MeV/c{sup 2}, respectively.

Liquid-phase tuning of porous PVDF-TrFE film on flexible substrate for energy harvesting

NASA Astrophysics Data System (ADS)

Chen, Dajing; Chen, Kaina; Brown, Kristopher; Hang, Annie; Zhang, John X. J.

2017-04-01

Emerging wearable and implantable biomedical energy harvesting devices demand efficient power conversion, flexible structures, and lightweight construction. This paper presents Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) micro-porous structures, which can be tuned to specific mechanical flexibilities and optimized for piezoelectric power conversion. Specifically, the water vapor phase separation method was developed to control microstructure formation, pore diameter, porosity, and mechanical flexibility. Furthermore, we investigated the effects of the piezoelectric layer to supporting layer Young's modulus ratio, through using both analytical calculation and experimentation. Both structure flexibility and stress-induced voltage were considered in the analyses. Specification of electromechanical coupling efficiency, made possible by carefully designed three-dimensional porous structures, was shown to increase the power output by five-fold relative to uncoupled structures. Therefore, flexible PVDF-TrFE films with tunable microstructures, paired with substrates of different rigidities, provide highly efficient designs of compact piezoelectric energy generating devices.

A novel energy conversion based method for velocity correction in molecular dynamics simulations

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

Jin, Hanhui; Collaborative Innovation Center of Advanced Aero-Engine, Hangzhou 310027; Liu, Ningning

2017-05-01

Molecular dynamics (MD) simulation has become an important tool for studying micro- or nano-scale dynamics and the statistical properties of fluids and solids. In MD simulations, there are mainly two approaches: equilibrium and non-equilibrium molecular dynamics (EMD and NEMD). In this paper, a new energy conversion based correction (ECBC) method for MD is developed. Unlike the traditional systematic correction based on macroscopic parameters, the ECBC method is developed strictly based on the physical interaction processes between the pair of molecules or atoms. The developed ECBC method can apply to EMD and NEMD directly. While using MD with this method, themore » difference between the EMD and NEMD is eliminated, and no macroscopic parameters such as external imposed potentials or coefficients are needed. With this method, many limits of using MD are lifted. The application scope of MD is greatly extended.« less

ULTRAFAST CHEMISTRY: Using Time-Resolved Vibrational Spectroscopy for Interrogation of Structural Dynamics

NASA Astrophysics Data System (ADS)

Nibbering, Erik T. J.; Fidder, Henk; Pines, Ehud

2005-05-01

Time-resolved infrared (IR) and Raman spectroscopy elucidates molecular structure evolution during ultrafast chemical reactions. Following vibrational marker modes in real time provides direct insight into the structural dynamics, as is evidenced in studies on intramolecular hydrogen transfer, bimolecular proton transfer, electron transfer, hydrogen bonding during solvation dynamics, bond fission in organometallic compounds and heme proteins, cis-trans isomerization in retinal proteins, and transformations in photochromic switch pairs. Femtosecond IR spectroscopy monitors the site-specific interactions in hydrogen bonds. Conversion between excited electronic states can be followed for intramolecular electron transfer by inspection of the fingerprint IR- or Raman-active vibrations in conjunction with quantum chemical calculations. Excess internal vibrational energy, generated either by optical excitation or by internal conversion from the electronic excited state to the ground state, is observable through transient frequency shifts of IR-active vibrations and through nonequilibrium populations as deduced by Raman resonances.

Understanding a reference-free impedance method using collocated piezoelectric transducers

NASA Astrophysics Data System (ADS)

Kim, Eun Jin; Kim, Min Koo; Sohn, Hoon; Park, Hyun Woo

2010-03-01

A new concept of a reference-free impedance method, which does not require direct comparison with a baseline impedance signal, is proposed for damage detection in a plate-like structure. A single pair of piezoelectric (PZT) wafers collocated on both surfaces of a plate are utilized for extracting electro-mechanical signatures (EMS) associated with mode conversion due to damage. A numerical simulation is conducted to investigate the EMS of collocated PZT wafers in the frequency domain at the presence of damage through spectral element analysis. Then, the EMS due to mode conversion induced by damage are extracted using the signal decomposition technique based on the polarization characteristics of the collocated PZT wafers. The effects of the size and the location of damage on the decomposed EMS are investigated as well. Finally, the applicability of the decomposed EMS to the reference-free damage diagnosis is discussed.

Structure and diffusion of furans and other cellulose-derived compounds in solvents via MD simulation

NASA Astrophysics Data System (ADS)

Rabideau, Brooks; Ismail, Ahmed

2011-03-01

There is now a large push towards the development of energy sources that are both environmentally friendly and sustainable; with the conversion of cellulose derived from biomass into biofuels being one promising route. In this conversion, a variety of intermediary compounds have been identified, which appear critical to successful expansion of the process to an industrial scale. Here we examine the structure and diffusion of these furans and acids derived from cellulose within ionic liquids via molecular dynamic simulation. Ionic liquids have shown the ability to dissolve cellulose with certain `green' benefits over existing, conventional solvents. Specifically, we study the solvation properties of these chemicals by examining the pair correlation functions of solute with solvent, and by exploring the agglomeration and separation of these chemicals from the solvent as well as the hydrogen bonding between species. Additionally, we determine the diffusion constant of these compounds in ionic liquid and aqueous solvents.

Effects of exposing rats to 100% oxygen at 450 and 600 mm Hg on in vitro liver and adipose tissue lipid synthesis.

NASA Technical Reports Server (NTRS)

Feller, D. D.; Neville, E. D.; Talarico, K. S.

1972-01-01

Male rats (260-285 gm) were exposed to 100% oxygen at 450 or 600 mm Hg for 1 to 4 days. Rats maintained at 450 mm Hg ate 92% the amount of food eaten by ad libitum controls maintained at sea level conditions. At 600 mm Hg, the food intake was 77% of the ad libitum controls. No difference was found in the plasma level of glucose, free fatty acids, and corticosterone between oxygen exposed rats and their respective pair-fed controls. The in vitro conversion of acetate into fatty acids by adipose tissue from rats exposed at 450 mm Hg for 2, 3, or 4 days was significantly increased above pair-fed controls and ad libitum controls. Increasing the oxygen pressure to 600 mm Hg abolished this increase, and in fact, reversed the increased synthesis to a significant decrease for the 4-day exposure.

Analog quadrature signal to phase angle data conversion by a quadrature digitizer and quadrature counter

DOEpatents

Buchenauer, C.J.

1981-09-23

The quadrature phase angle phi (t) of a pair of quadrature signals S/sub 1/(t) and S/sub 2/(t) is digitally encoded on a real time basis by a quadrature digitizer for fractional phi (t) rotational excursions and by a quadrature up/down counter for full phi (t) rotations. The pair of quadrature signals are of the form S/sub 1/(t) = k(t) sin phi (t) and S/sub 2/(t) = k(t) cos phi (t) where k(t) is a signal common to both. The quadrature digitizer and the quadrature up/down counter may be used together or singularly as desired or required. Optionally, a digital-to-analog converter may follow the outputs of the quadrature digitizer and the quadrature up/down counter to provide an analog signal output of the quadrature phase angle phi (t).

Analog quadrature signal to phase angle data conversion by a quadrature digitizer and quadrature counter

DOEpatents

Buchenauer, C. Jerald

1984-01-01

The quadrature phase angle .phi.(t) of a pair of quadrature signals S.sub.1 (t) and S.sub.2 (t) is digitally encoded on a real time basis by a quadrature digitizer for fractional .phi.(t) rotational excursions and by a quadrature up/down counter for full .phi.(t) rotations. The pair of quadrature signals are of the form S.sub.1 (t)=k(t) sin .phi.(t) and S.sub.2 (t)=k(t) cos .phi.(t) where k(t) is a signal common to both. The quadrature digitizer and the quadrature up/down counter may be used together or singularly as desired or required. Optionally, a digital-to-analog converter may follow the outputs of the quadrature digitizer and the quadrature up/down counter to provide an analog signal output of the quadrature phase angle .phi.(t).

Effects of visual and verbal interaction on unintentional interpersonal coordination.

PubMed

Richardson, Michael J; Marsh, Kerry L; Schmidt, R C

2005-02-01

Previous research has demonstrated that people's movements can become unintentionally coordinated during interpersonal interaction. The current study sought to uncover the degree to which visual and verbal (conversation) interaction constrains and organizes the rhythmic limb movements of coactors. Two experiments were conducted in which pairs of participants completed an interpersonal puzzle task while swinging handheld pendulums with instructions that minimized intentional coordination but facilitated either visual or verbal interaction. Cross-spectral analysis revealed a higher degree of coordination for conditions in which the pairs were visually coupled. In contrast, verbal interaction alone was not found to provide a sufficient medium for unintentional coordination to occur, nor did it enhance the unintentional coordination that emerged during visual interaction. The results raise questions concerning differences between visual and verbal informational linkages during interaction and how these differences may affect interpersonal movement production and its coordination.

Magnetic Field Effects in Hybrid Perovskite Devices

NASA Astrophysics Data System (ADS)

Zhang, C.; Sun, D.; Sheng, C.-X.; Zhai, Y.; Mielczarek, K.; Zakhidov, A.; Vardeny, Z. V.

2015-03-01

Solar cells based on the organic-inorganic perovskites (CH3NH3PbX3, X =halogen) have reached a remarkable power conversion efficiency approaching 20%, which calls for research studies of the photophysics behind this high device performance. We measured significant magneto-photocurrent (MPC) response in CH3NH3PbI3-xClx photovoltaic cells, in the form of Lorentzian up to field B = 1T. We attribute the MPC(B) response to spin mixing of loosely-bound photogenerated e-h pairs having different g-factor (dubbed `` Δg mechanism''). We verified this mechanism by measuring Δg directly, using the field induced circularly polarized photoluminescence emission at low temperature, along with the photocarriers' lifetime measured by picosecond pump-probe spectroscopy. We conclude that MPC of spin 1/2 e-h pairs provides a promising method for investigating the spin-related properties of photoexcitations in the novel hybrid perovskites.

Annual-ring-type quasi-phase-matching crystal for generation of narrowband high-dimensional entanglement

NASA Astrophysics Data System (ADS)

Hua, Yi-Lin; Zhou, Zong-Quan; Liu, Xiao; Yang, Tian-Shu; Li, Zong-Feng; Li, Pei-Yun; Chen, Geng; Xu, Xiao-Ye; Tang, Jian-Shun; Xu, Jin-Shi; Li, Chuan-Feng; Guo, Guang-Can

2018-01-01

A photon pair can be entangled in many degrees of freedom such as polarization, time bins, and orbital angular momentum (OAM). Among them, the OAM of photons can be entangled in an infinite-dimensional Hilbert space which enhances the channel capacity of sharing information in a network. Twisted photons generated by spontaneous parametric down-conversion offer an opportunity to create this high-dimensional entanglement, but a photon pair generated by this process is typically wideband, which makes it difficult to interface with the quantum memories in a network. Here we propose an annual-ring-type quasi-phase-matching (QPM) crystal for generation of the narrowband high-dimensional entanglement. The structure of the QPM crystal is designed by tracking the geometric divergences of the OAM modes that comprise the entangled state. The dimensionality and the quality of the entanglement can be greatly enhanced with the annual-ring-type QPM crystal.

Entangled quantum key distribution over two free-space optical links.

PubMed

Erven, C; Couteau, C; Laflamme, R; Weihs, G

2008-10-13

We report on the first real-time implementation of a quantum key distribution (QKD) system using entangled photon pairs that are sent over two free-space optical telescope links. The entangled photon pairs are produced with a type-II spontaneous parametric down-conversion source placed in a central, potentially untrusted, location. The two free-space links cover a distance of 435 m and 1,325 m respectively, producing a total separation of 1,575 m. The system relies on passive polarization analysis units, GPS timing receivers for synchronization, and custom written software to perform the complete QKD protocol including error correction and privacy amplification. Over 6.5 hours during the night, we observed an average raw key generation rate of 565 bits/s, an average quantum bit error rate (QBER) of 4.92%, and an average secure key generation rate of 85 bits/s.

Age-related differences in communication and audience design.

PubMed

Horton, William S; Spieler, Daniel H

2007-06-01

This article reports an experiment examining the extent to which younger and older speakers engage in audience design, the process of adapting one's speech for particular addresses. Through an initial card-matching task, pairs of younger adults and pairs of older adults established common ground for sets of picture cards. Subsequently, the same individuals worked separately on a computer-based picture-description task that involved a novel partner-cuing paradigm. Younger speakers' descriptions to the familiar partner were shorter and were initiated more quickly than were descriptions to an unfamiliar partner. In addition, younger speakers' descriptions to the familiar partner exhibited a higher proportion of lexical overlap with previous descriptions than did descriptions to an unfamiliar partner. Older speakers showed no equivalent evidence for audience design, which may reflect difficulties with retrieving partner-specific information from memory during conversation. ((c) 2007 APA, all rights reserved).

A feasibility of single-incision laparoscopic percutaneous extraperitoneal closure for treatment of incarcerated inguinal hernia in children: our preliminary outcome and review of the literature.

PubMed

Murase, Naruhiko; Uchida, Hiroo; Seki, Takashi; Hiramatsu, Kiyoshi

2016-02-01

The purpose of this study is to examine the feasibility of single-incision laparoscopic percutaneous extraperitoneal closure (LPEC) for incarcerated inguinal hernia (IIH) repair. 6 single-incision LPEC procedures were performed for IIH repair and 60 procedures were performed for reducible inguinal hernia (RIH) in the same period of time in one hospital. The laparoscope and one pair of grasping forceps were placed through the same umbilical incision. In IIH repair, the herniated organ was gently pulled using the grasping forceps with external manual pressure. If it was difficult to reduce the herniated organ with one pair of forceps, another pair of forceps were inserted through a multi-channel port without extending the umbilical incidion. Using the LPEC needle, the hernia orifice was closed extraperitoneally. We performed a retrospective analysis to compare the outcomes of single-incision LPEC for IIH repair or reducible inguinal hernia. All procedures were completed by single-incision without open conversion. A multi-channel port with another pair of forceps was needed in three cases. The operation time and the length of stay were significantly longer with IIH repair than with RIH repair. There were no major complications and there was no evidence of early recurrence in any patient. In conclusion, single-incision LPEC with a multi-channel port is feasible and safe for IIH repair.

Roles of the amino group of purine bases in the thermodynamic stability of DNA base pairing.

PubMed

Nakano, Shu-ichi; Sugimoto, Naoki

2014-08-05

The energetic aspects of hydrogen-bonded base-pair interactions are important for the design of functional nucleotide analogs and for practical applications of oligonucleotides. The present study investigated the contribution of the 2-amino group of DNA purine bases to the thermodynamic stability of oligonucleotide duplexes under different salt and solvent conditions, using 2'-deoxyriboinosine (I) and 2'-deoxyribo-2,6-diaminopurine (D) as non-canonical nucleotides. The stability of DNA duplexes was changed by substitution of a single base pair in the following order: G • C > D • T ≈ I • C > A • T > G • T > I • T. The apparent stabilization energy due to the presence of the 2-amino group of G and D varied depending on the salt concentration, and decreased in the water-ethanol mixed solvent. The effects of salt concentration on the thermodynamics of DNA duplexes were found to be partially sequence-dependent, and the 2-amino group of the purine bases might have an influence on the binding of ions to DNA through the formation of a stable base-paired structure. Our results also showed that physiological salt conditions were energetically favorable for complementary base recognition, and conversely, low salt concentration media and ethanol-containing solvents were effective for low stringency oligonucleotide hybridization, in the context of conditions employed in this study.

High resolution multispectral photogrammetric imagery: enhancement, interpretation and evaluations

NASA Astrophysics Data System (ADS)

Roberts, Arthur; Haefele, Martin; Bostater, Charles; Becker, Thomas

2007-10-01

A variety of aerial mapping cameras were adapted and developed into simulated multiband digital photogrammetric mapping systems. Direct digital multispectral, two multiband cameras (IIS 4 band and Itek 9 band) and paired mapping and reconnaissance cameras were evaluated for digital spectral performance and photogrammetric mapping accuracy in an aquatic environment. Aerial films (24cm X 24cm format) tested were: Agfa color negative and extended red (visible and near infrared) panchromatic, and; Kodak color infrared and B&W (visible and near infrared) infrared. All films were negative processed to published standards and digitally converted at either 16 (color) or 10 (B&W) microns. Excellent precision in the digital conversions was obtained with scanning errors of less than one micron. Radiometric data conversion was undertaken using linear density conversion and centered 8 bit histogram exposure. This resulted in multiple 8 bit spectral image bands that were unaltered (not radiometrically enhanced) "optical count" conversions of film density. This provided the best film density conversion to a digital product while retaining the original film density characteristics. Data covering water depth, water quality, surface roughness, and bottom substrate were acquired using different measurement techniques as well as different techniques to locate sampling points on the imagery. Despite extensive efforts to obtain accurate ground truth data location errors, measurement errors, and variations in the correlation between water depth and remotely sensed signal persisted. These errors must be considered endemic and may not be removed through even the most elaborate sampling set up. Results indicate that multispectral photogrammetric systems offer improved feature mapping capability.

The Association between Primary Tooth Emergence and Anthropometric Measures in Young Adults: Findings from a Large Prospective Cohort Study

PubMed Central

Fatemifar, Ghazaleh; Evans, David M.; Tobias, Jonathan H.

2014-01-01

Cross sectional studies suggest a link may exist between tooth emergence and obesity. To explore this relationship, we aimed to evaluate the prospective associations between primary tooth emergence and anthropometric measures in young adults. Multivariable linear regression was used to analyse relationships between primary tooth emergence, and anthropometric measures measured at 17.8 years, in 2977 participants (1362 males and 1615 females) from the Avon Longitudinal Study of Parents and Children (ALSPAC). In minimally adjusted models, ‘quintiles of number of paired teeth’ (assessed by questionnaire at 15 months) was positively associated with height [change in height (cm) per quintile increase in ‘number of paired teeth’ (β) = 0.35 (95%CI: 0.18, 0.52) P = 0.0001] and weight [ratio of geometric mean weight per quintile increase in ‘number of paired teeth’ (RGM) = 1.015 (95%CI: 1.010, 1.019) P<0.0001]. The relationship with weight was largely driven by fat mass, which showed an equivalent relationship with ‘quintiles of number of paired teeth’ to that seen for weight [RGM = 1.036 (95%CI: 1.022, 1.051) P<0.0001] (adjusted for height)]. Conversely, no association was seen between ‘quintiles of number of paired teeth’ and lean mass. An increase in ‘quintiles of number of paired teeth’ at age 15 months was associated with a higher Tanner stage at age 13 in girls but not boys, but further adjustment of associations between ‘quintiles of number of paired teeth’ and anthropometric traits for Tanner stage was without effect. Primary tooth emergence is associated with subsequent fat mass, suggesting these could share common constitutive factors, and that early primary tooth emergence may represent a hitherto unrecognised risk factor for the development of obesity in later life. PMID:24823714

Phenomenology of the sound-induced flash illusion.

PubMed

Abadi, Richard V; Murphy, Jonathan S

2014-07-01

Past studies, using pairings of auditory tones and visual flashes, which were static and coincident in space but variable in time, demonstrated errors in judging the temporal patterning of the visual flashes-the sound-induced flash illusion. These errors took one of the two forms: under-reporting (sound-induced fusion) or over-reporting (sound-induced fission) of the flash numbers. Our study had three objectives: to examine the robustness of both illusions and to consider the effects of stimulus set and response bias. To this end, we used an extended range of fixed spatial location flash-tone pairings, examined stimuli that were variable in space and time and measured confidence in judging flash numbers. Our results indicated that the sound-induced flash illusion is a robust percept, a finding underpinned by the confidence measures. Sound-induced fusion was found to be more robust than sound-induced fission and a most likely outcome when high numbers of flashes were incorporated within an incongruent flash-tone pairing. Conversely, sound-induced fission was the most likely outcome for the flash-tone pairing which contained two flashes. Fission was also shown to be strongly driven by stimuli confounds such as categorical boundary conditions (e.g. flash-tone pairings with ≤2 flashes) and compressed response options. These findings suggest whilst both fission and fusion are associated with 'auditory driving', the differences in the occurrence and strength of the two illusions not only reflect the separate neuronal mechanisms underlying audio and visual signal processing, but also the test conditions that have been used to investigate the sound-induced flash illusion.

Acceleration of the highest energy cosmic rays through proton-neutron conversions in relativistic bulk flows

NASA Astrophysics Data System (ADS)

Derishev, E.; Aharonian, F.

We show that, in the presence of radiation field, relativistic bulk flows can very quikly accelerate protons and electrons up to the energies limited either by Hillas criterion or by synchrotron losses. Unlike the traditional approach, we take advantage of continuous photon-induced conversion of charged particle species to neutral ones, and vice versa (proton-neutron or electron-photon). Such a conversion, though it leads to considerable energy losses, allows accelerated particles to increase their energies in each scattering by a factor roughly equal to the bulk Lorentz factor, thus avoiding the need in slow and relatively inefficient diffusive acceleration. The optical depth of accelerating region with respect to inelastic photon-induced reactions (pair production for electrons and photomeson reactions for protons) should be a substancial fraction of unity. Remarkably, self-tuning of the optical depth is automatically achieved as long as the photon density depends on the distance along the bulk flow. This mechanism can work in Gamma-Ray Bursts (GRBs), Active Galactic Nuclei (AGNs), microquasars, or any other object with relativistic bulk flows embedded in radiation-reach environment. Both GRBs and AGNs turn out to be capable of producing 1020 eV cosmic rays.

Reversible hydrogen transfer reactions of cysteine thiyl radicals in peptides: the conversion of cysteine into dehydroalanine and alanine, and of alanine into dehydroalanine

PubMed Central

Mozziconacci, Olivier; Kerwin, Bruce A.; Schöneich, Christian

2013-01-01

The photodissociation of disulfide bonds in model peptides containing Ala and Ala-d3 generates a series of photoproducts following the generation of a CysS• thiyl radical pair. These photoproducts include transformations of Cys to dehydroalanine (Dha) and Ala, as well as Ala to Dha. Intramolecular Michael addition of an intact Cys with a photolytically generated Dha results in the formation of cyclic thioethers. The conversion of Cys into Dha likely involves a 1,3-H-shift from the Cys αC-H bond to the thiyl radical, followed by elimination of HS•. The conversion of Dha into Ala most likely involves hydrated electrons, which are generated through the photolysis of Cys, the photoproduct of disulfide photolysis. Prior to stable product formation, CysS• radicals engage in reversible hydrogen transfer reactions with αC-H and βC-H bonds of the surrounding amino acids. Especially for the βC-H bonds of Ala such hydrogen transfer reactions are unexpected based on thermodynamic grounds; however, the replacement of deuterons in Ala-d3 by hydrogens in H2O provides strong experimental evidence for such reactions. PMID:21895001

Development of digital sideband separating down-conversion for Yuan-Tseh Lee Array

NASA Astrophysics Data System (ADS)

Li, Chao-Te; Kubo, Derek; Cheng, Jen-Chieh; Kuroda, John; Srinivasan, Ranjani; Ho, Solomon; Guzzino, Kim; Chen, Ming-Tang

2016-07-01

This report presents a down-conversion method involving digital sideband separation for the Yuan-Tseh Lee Array (YTLA) to double the processing bandwidth. The receiver consists of a MMIC HEMT LNA front end operating at a wavelength of 3 mm, and sub-harmonic mixers that output signals at intermediate frequencies (IFs) of 2-18 GHz. The sideband separation scheme involves an analog 90° hybrid followed by two mixers that provide down-conversion of the IF signal to a pair of in-phase (I) and quadrature (Q) signals in baseband. The I and Q baseband signals are digitized using 5 Giga sample per second (Gsps) analog-to-digital converters (ADCs). A second hybrid is digitally implemented using field-programmable gate arrays (FPGAs) to produce two sidebands, each with a bandwidth of 1.6 GHz. The 2 x 1.6 GHz band can be tuned to cover any 3.6 GHz window within the aforementioned IF range of the array. Sideband rejection ratios (SRRs) above 20 dB can be obtained across the 3.6 GHz bandwidth by equalizing the power and delay between the I and Q baseband signals. Furthermore, SRRs above 30 dB can be achieved when calibration is applied.

Inhibition of colorectal cancer genomic copy number alterations and chromosomal fragile site tumor suppressor FHIT and WWOX deletions by DNA mismatch repair

PubMed Central

Gelincik, Ozkan; Blecua, Pedro; Edelmann, Winfried; Kucherlapati, Raju; Zhou, Kathy; Jasin, Maria; Gümüş, Zeynep H.; Lipkin, Steven M.

2017-01-01

Homologous recombination (HR) enables precise DNA repair after DNA double strand breaks (DSBs) using identical sequence templates, whereas homeologous recombination (HeR) uses only partially homologous sequences. Homeologous recombination introduces mutations through gene conversion and genomic deletions through single-strand annealing (SSA). DNA mismatch repair (MMR) inhibits HeR, but the roles of mammalian MMR MutL homologues (MLH1, PMS2 and MLH3) proteins in HeR suppression are poorly characterized. Here, we demonstrate that mouse embryonic fibroblasts (MEFs) carrying Mlh1, Pms2, and Mlh3 mutations have higher HeR rates, by using 7,863 uniquely mapping paired direct repeat sequences (DRs) in the mouse genome as endogenous gene conversion and SSA reporters. Additionally, when DSBs are induced by gamma-radiation, Mlh1, Pms2 and Mlh3 mutant MEFs have higher DR copy number alterations (CNAs), including DR CNA hotspots previously identified in mouse MMR-deficient colorectal cancer (dMMR CRC). Analysis of The Cancer Genome Atlas CRC data revealed that dMMR CRCs have higher genome-wide DR HeR rates than MMR proficient CRCs, and that dMMR CRCs have deletion hotspots in tumor suppressors FHIT/WWOX at chromosomal fragile sites FRA3B and FRA16D (which have elevated DSB rates) flanked by paired homologous DRs and inverted repeats (IR). Overall, these data provide novel insights into the MMR-dependent HeR inhibition mechanism and its role in tumor suppression. PMID:29069730

Presence of Peierls pairing and absence of insulator-to-metal transition in VO2 (A): a structure-property relationship study.

PubMed

Popuri, S R; Artemenko, A; Decourt, R; Villesuzanne, A; Pollet, M

2017-03-01

Layered vanadium oxides have been extensively explored due to their interesting metal-insulator transitions and energy conversion/storage applications. In the present study, we have successfully synthesized VO 2 (A) polymorph powder samples by a single-step hydrothermal synthesis process and consolidated them using spark plasma sintering. The structural and electronic properties of VO 2 (A) are measured over a large temperature range from liquid helium, across the structural transition (400-440 K) and up to 500 K. The structural analysis around this transition reveals an antiferrodistorsive to partially ferrodistorsive ordering upon cooling. It is followed by a progressive antiferromagnetic spin pairing which fully settles at about 150 K. The transport measurements show that, in contrast to the rutile archetype VO 2 (R/M1), the structural transition comes with a transition from semiconductor to band-type insulator. Under these circumstances, we propose a scenario with a high temperature antiferrodistorsive paramagnetic semiconducting phase, followed by an intermediate regime with a partially ferrodistorsive paramagnetic semiconducting phase, and finally a low temperature partially ferrodistorsive antiferromagnetic band insulator phase with a possible V-V Peierls-type pairing.

Altered Reward Reactivity as a Behavioural Endophenotype in Eating Disorders: A Pilot Investigation in Twins.

PubMed

Kanakam, Natalie; Krug, Isabel; Collier, David; Treasure, Janet

2017-05-01

Altered reward reactivity is a potential risk endophenotype for eating disorders (EDs). The aim of this study was to examine reward reactivity in female twins with EDs and compare it with a twin control group. A sample of 112 twins [n = 51 met lifetime DSM-IV ED criteria (anorexia nervosa n = 26; bulimic disorders n = 24), n = 19 unaffected cotwins and n = 42 control twins] was administered measures assessing reward reactivity, including the Game of Dice Task, the Behavioural Inhibition/Activation (BIS/BAS) Scales and the Appetitive Motivation Scale (AMS). Within pair, correlations for monozygotic and dizygotic twins were calculated and generalised estimating equations compared probands with non-ED cotwins and controls. The BAS and the AMS were reduced in EDs and negatively associated with restrictive symptoms. In addition, monozygotic twins pairs demonstrated significant within pair similarity for the BAS and AMS. Conversely, there was less evidence to support the BIS or risky decision-making as measured by the Game of Dice Task as an endophenotype in EDs. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

Frequency-bin entanglement of ultra-narrow band non-degenerate photon pairs

NASA Astrophysics Data System (ADS)

Rieländer, Daniel; Lenhard, Andreas; Jime`nez Farìas, Osvaldo; Máttar, Alejandro; Cavalcanti, Daniel; Mazzera, Margherita; Acín, Antonio; de Riedmatten, Hugues

2018-01-01

We demonstrate frequency-bin entanglement between ultra-narrowband photons generated by cavity enhanced spontaneous parametric down conversion. Our source generates photon pairs in widely non-degenerate discrete frequency modes, with one photon resonant with a quantum memory material based on praseodymium doped crystals and the other photon at telecom wavelengths. Correlations between the frequency modes are analyzed using phase modulators and narrowband filters before detection. We show high-visibility two photon interference between the frequency modes, allowing us to infer a coherent superposition of the modes. We develop a model describing the state that we create and use it to estimate optimal measurements to achieve a violation of the Clauser-Horne (CH) Bell inequality under realistic assumptions. With these settings we perform a Bell test and show a significant violation of the CH inequality, thus proving the entanglement of the photons. Finally we demonstrate the compatibility with a quantum memory material by using a spectral hole in the praseodymium (Pr) doped crystal as spectral filter for measuring high-visibility two-photon interference. This demonstrates the feasibility of combining frequency-bin entangled photon pairs with Pr-based solid state quantum memories.

Experience-Dependent Effects of Cocaine Self-Administration/Conditioning on Prefrontal and Accumbens Dopamine Responses

PubMed Central

Ikegami, Aiko; Olsen, Christopher M.; D’Souza, Manoranjan S.; Duvauchelle, Christine L.

2008-01-01

Experiments were performed to examine the effects of cocaine self-administration and conditioning experience on operant behavior, locomotor activity, and nucleus accumbens (NAcc) and prefrontal cortex (PFC) dopamine (DA) responses. Sensory cues were paired with alternating cocaine and nonreinforcement during 12 (limited training) or 40 (long-term training) daily operant sessions. After limited training, NAcc DA responses to cocaine were significantly enhanced in the presence of cocaine-associated cues compared with nonreward cues and significantly depressed after cocaine-paired cues accompanied a nonreinforced lever response. PFC DA levels were generally nonresponsive to cues after the same training duration. However, after long-term training, cocaine-associated cues increased the magnitude of cocaine-stimulated PFC DA levels significantly over levels observed with nonreinforcement cues. Conversely, conditioned cues no longer influenced NAcc DA levels after long-term training. In addition, cocaine-stimulated locomotor activity was enhanced by cocaine-paired cues after long-term, but not after limited, training. Findings demonstrate that cue-induced cocaine expectation exerts a significant impact on dopaminergic and behavioral systems, progressing from mesolimbic to mesocortical regions and from latent to patent behaviors as cocaine and associative experiences escalate. PMID:17469929

Mutual Mate Choice: When it Pays Both Sexes to Avoid Inbreeding

PubMed Central

Lihoreau, Mathieu; Zimmer, Cédric; Rivault, Colette

2008-01-01

Theoretical models of sexual selection predict that both males and females of many species should benefit by selecting their mating partners. However, empirical evidence testing and validating this prediction is scarce. In particular, whereas inbreeding avoidance is expected to induce sexual conflicts, in some cases both partners could benefit by acting in concert and exerting mutual mate choice for non-assortative pairings. We tested this prediction with the gregarious cockroach Blattella germanica (L.). We demonstrated that males and females base their mate choice on different criteria and that choice occurs at different steps during the mating sequence. Males assess their relatedness to females through antennal contacts before deciding to court preferentially non-siblings. Conversely, females biased their choice towards the most vigorously courting males that happened to be non-siblings. This study is the first to demonstrate mutual mate choice leading to close inbreeding avoidance. The fact that outbred pairs were more fertile than inbred pairs strongly supports the adaptive value of this mating system, which includes no “best phenotype” as the quality of two mating partners is primarily linked to their relatedness. We discuss the implications of our results in the light of inbreeding conflict models. PMID:18843373

Mutual mate choice: when it pays both sexes to avoid inbreeding.

PubMed

Lihoreau, Mathieu; Zimmer, Cédric; Rivault, Colette

2008-01-01

Theoretical models of sexual selection predict that both males and females of many species should benefit by selecting their mating partners. However, empirical evidence testing and validating this prediction is scarce. In particular, whereas inbreeding avoidance is expected to induce sexual conflicts, in some cases both partners could benefit by acting in concert and exerting mutual mate choice for non-assortative pairings. We tested this prediction with the gregarious cockroach Blattella germanica (L.). We demonstrated that males and females base their mate choice on different criteria and that choice occurs at different steps during the mating sequence. Males assess their relatedness to females through antennal contacts before deciding to court preferentially non-siblings. Conversely, females biased their choice towards the most vigorously courting males that happened to be non-siblings. This study is the first to demonstrate mutual mate choice leading to close inbreeding avoidance. The fact that outbred pairs were more fertile than inbred pairs strongly supports the adaptive value of this mating system, which includes no "best phenotype" as the quality of two mating partners is primarily linked to their relatedness. We discuss the implications of our results in the light of inbreeding conflict models.

Structure and conversion kinetics of a bi-stable DNA i-motif: broken symmetry in the [d(5mCCTCC)]4 tetramer.

PubMed

Nonin, S; Leroy, J L

1996-08-23

At slightly acidic pH, protonation of C-rich oligomers results in the formation of a four-stranded structure composed of two parallel duplexes in a head to tail orientation with their hemi-protonated C.C+ pairs intercalated in a so-called i-motif. In all cases reported previously the duplexes are identical. The tetramer formed by the d(5mCCTCC) oligomer is different. The structure is computed on the basis of 55 inter-residue distances derived from NOESY cross-peaks measured at short mixing times. It consists of two intercalated non-equivalent symmetrical duplexes. The base stacking order is C5* C1 C4* C2 (T3*) T3 C2* C4 C1* C5, but the thymidine bases (T3*) of one duplex are looped out and lie in the wide grooves of the tetramer. The thymidine bases T3 stack as a symmetrical T.T pair between the sequentially adjacent C2.C2+ pair and the C2*.C2*+ pair of the other duplex. Numerous exchange cross-peaks provide evidence for duplex interconversion. The interconversion rate is 1.4 s-1 at 0 degree C and the activation energy is 94 kJ/mol. The opening of the T3.T3 pair, the closing of the T3*.T3 pair, and the opening of the C2*.C2*+ pair occur simultaneously with the duplex interconversion. This suggests that the concerted opening and closing of the thymidine bases drive the duplex interconversion. Opening of the C4.C4+ and C4*.C4*+ pairs, and dissociation of the tetramer are not part of the interconversion since they occur at much slower rates. Duplex interconversion within the [d(5mCCTCC)]4 tetramer provides the first structural and kinetics characterization of broken symmetry in a biopolymer. The tetramer formed by d(5mCCUCC) adopts a similar structure, but the rate of duplex interconversion is faster: 40 s-1 at 0 degree C. At 32 degrees C, interconversion is fast on the NMR time scale.

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

Grice, Warren P; Bennink, Ryan S; Evans, Philip G

A growing number of experiments make use of multiple pairs of photons generated in the process of spontaneous parametric down-conversion. We show that entanglement in unwanted degrees of freedom can adversely affect the results of these experiments. We also discuss techniques to reduce or eliminate spectral and spatial entanglement, and we present results from two-photon polarization-entangled source with almost no entanglement in these degrees of freedom. Finally, we present two methods for the generation of four-photon polarization- entangled states. In one of these methods, four-photon can be generated without the need for intermediate two-photon entanglement.

Local Sampling of the Wigner Function at Telecom Wavelength with Loss-Tolerant Detection of Photon Statistics.

PubMed

Harder, G; Silberhorn, Ch; Rehacek, J; Hradil, Z; Motka, L; Stoklasa, B; Sánchez-Soto, L L

2016-04-01

We report the experimental point-by-point sampling of the Wigner function for nonclassical states created in an ultrafast pulsed type-II parametric down-conversion source. We use a loss-tolerant time-multiplexed detector based on a fiber-optical setup and a pair of photon-number-resolving avalanche photodiodes. By capitalizing on an expedient data-pattern tomography, we assess the properties of the light states with outstanding accuracy. The method allows us to reliably infer the squeezing of genuine two-mode states without any phase reference.

CsI Calorimeter for a Compton-Pair Telescope

NASA Astrophysics Data System (ADS)

Grove, Eric J.

We propose to build and test a hodoscopic CsI(Tl) scintillating-crystal calorimeter for a medium-energy γ-ray Compton and pair telescope. The design and technical approach for this calorimeter relies deeply on heritage from the Fermi LAT CsI Calorimeter, but it dramatically improves the low-energy performance of that design by reading out the scintillation light with silicon photomultipliers (SiPMs), making the technology developed for Fermi applicable in the Compton regime. While such a hodoscopic calorimeter is useful for an entire class of medium-energy γ-ray telescope designs, we propose to build it explicitly to support beam tests and balloon flight of the Proto-ComPair telescope, the development and construction of which was funded in a four-year APRA program beginning in 2015 ("ComPair: Steps to a Medium Energy γ-ray Mission" with PI J. McEnery of GSFC). That award did not include funding for its CsI calorimeter subsystem, and this proposal is intended to cover that gap. ComPair is a MIDEX-class instrument concept to perform a high-sensitivity survey of the γ-ray sky from 0.5 MeV to 500 MeV. ComPair is designed to provide a dramatic increase in sensitivity relative to previous instruments in this energy range (predominantly INTEGRAL/SPI and Compton COMPTEL), with the same transformative sensitivity increase - and corresponding scientific return- that the Fermi Large Area Telescope provided relative to Compton EGRET. To enable transformative science over a broad range of MeV energies and with a wide field of view, ComPair is a combined Compton telescope and pair telescope employing a silicon-strip tracker (for Compton scattering and pair conversion and tracking) and a solid-state CdZnTe calorimeter (for Compton absorption) and CsI calorimeter (for pair calorimetry), surrounded by a plastic scintillator anti-coincidence detector. Under the current proposal, we will complete the detailed design, assembly, and test of the CsI calorimeter for the risk-reduction prototype telescope, Proto-ComPair. We will: 1. Purchase CsI(Tl) crystals, Silicon Photomultipliers (SiPMs), and components for the analog and digital readout of the SiPMs; 2. Assemble and test Crystal Detector Elements (CDEs) from crystals, SiPMs and optical wrap; 3. Assemble and test analog and digital front-end and readout control boards; 4. Fabricate the mechanical structure that supports and contains the CDEs and electronics boards; and 5. Assemble and test the CsI calorimeter, and integrate it with the remainder of the Proto-ComPair subsystems. The PI team for this proposal conceived, designed, developed, assembled, tested, and currently operates the LAT calorimeter and is uniquely qualified to leverage the experience gained from that effort for ComPair.

A longitudinal evaluation of performance of automated BCR-ABL1 quantitation using cartridge-based detection system.

PubMed

Enjeti, Anoop; Granter, Neil; Ashraf, Asma; Fletcher, Linda; Branford, Susan; Rowlings, Philip; Dooley, Susan

2015-10-01

An automated cartridge-based detection system (GeneXpert; Cepheid) is being widely adopted in low throughput laboratories for monitoring BCR-ABL1 transcript in chronic myelogenous leukaemia. This Australian study evaluated the longitudinal performance specific characteristics of the automated system.The automated cartridge-based system was compared prospectively with the manual qRT-PCR-based reference method at SA Pathology, Adelaide, over a period of 2.5 years. A conversion factor determination was followed by four re-validations. Peripheral blood samples (n = 129) with international scale (IS) values within detectable range were selected for assessment. The mean bias, proportion of results within specified fold difference (2-, 3- and 5-fold), the concordance rate of major molecular remission (MMR) and concordance across a range of IS values on paired samples were evaluated.The initial conversion factor for the automated system was determined as 0.43. Except for the second re-validation, where a negative bias of 1.9-fold was detected, all other biases fell within desirable limits. A cartridge-specific conversion factor and efficiency value was introduced and the conversion factor was confirmed to be stable in subsequent re-validation cycles. Concordance with the reference method/laboratory at >0.1-≤10 IS was 78.2% and at ≤0.001 was 80%, compared to 86.8% in the >0.01-≤0.1 IS range. The overall and MMR concordance were 85.7% and 94% respectively, for samples that fell within ± 5-fold of the reference laboratory value over the entire period of study.Conversion factor and performance specific characteristics for the automated system were longitudinally stable in the clinically relevant range, following introduction by the manufacturer of lot specific efficiency values.

T-SPOT.TB Interferon-γ Release Assay Performance in Healthcare Worker Screening at Nineteen U.S. Hospitals.

PubMed

King, Thomas C; Upfal, Mark; Gottlieb, Andrew; Adamo, Philip; Bernacki, Edward; Kadlecek, Chris P; Jones, Jeffrey G; Humphrey-Carothers, Frances; Rielly, Albert F; Drewry, Pamela; Murray, Kathy; DeWitt, Marcie; Matsubara, Janet; O'Dea, Louis; Balser, John; Wrighton-Smith, Peter

2015-08-01

Interferon-γ release assays have significant advantages over tuberculin skin testing in many clinical situations. However, recent studies have called into question their reliability in serial testing of healthcare workers because of reportedly high rates of positivity and high conversion/reversion rates on retesting. To define the performance characteristics of the T-SPOT.TB test, an interferon-γ release assay, during serial screening programs of healthcare workers at 19 U.S. hospitals. A total of 42,155 T-SPOT.TB test results from healthcare workers at 19 geographically diverse hospitals obtained for routine tuberculosis screening programs were analyzed to determine the rates of positivity, reversion, and conversion in serial testing data. In 19,630 evaluable serial pairs from 16,076 healthcare workers, the mean test positivity rate was 2.3% (range, 0.0-27.4%). The mean conversion rate was 0.8% (range, 0.0-2.5%), and the mean reversion rate was 17.6%. Positivity and conversion rates correlated with known tuberculosis risk factors including age and sex. The observed specificity of the T-SPOT.TB test was at least 98.6%. The high concordance and test completion rates in this study suggest that the T-SPOT.TB test is a reliable tool for healthcare worker serial screening. As expected, the observed positivity rates were lower compared with the tuberculin skin test, likely reflecting the higher specificity of this test. Furthermore, the observed rates of conversion were low and significantly correlated with the geographic incidence of tuberculosis. Our findings suggest that the T-SPOT.TB test is an accurate and reliable way to screen healthcare workers.

Remote Sensing Analysis of Vegetation Recovery following Short-Interval Fires in Southern California Shrublands

PubMed Central

Meng, Ran; Dennison, Philip E.; D’Antonio, Carla M.; Moritz, Max A.

2014-01-01

Increased fire frequency has been shown to promote alien plant invasions in the western United States, resulting in persistent vegetation type change. Short interval fires are widely considered to be detrimental to reestablishment of shrub species in southern California chaparral, facilitating the invasion of exotic annuals and producing “type conversion”. However, supporting evidence for type conversion has largely been at local, site scales and over short post-fire time scales. Type conversion has not been shown to be persistent or widespread in chaparral, and past range improvement studies present evidence that chaparral type conversion may be difficult and a relatively rare phenomenon across the landscape. With the aid of remote sensing data covering coastal southern California and a historical wildfire dataset, the effects of short interval fires (<8 years) on chaparral recovery were evaluated by comparing areas that burned twice to adjacent areas burned only once. Twelve pairs of once- and twice-burned areas were compared using normalized burn ratio (NBR) distributions. Correlations between measures of recovery and explanatory factors (fire history, climate and elevation) were analyzed by linear regression. Reduced vegetation cover was found in some lower elevation areas that were burned twice in short interval fires, where non-sprouting species are more common. However, extensive type conversion of chaparral to grassland was not evident in this study. Most variables, with the exception of elevation, were moderately or poorly correlated with differences in vegetation recovery. PMID:25337785

Galaxy pairs in the SDSS - XIII. The connection between enhanced star formation and molecular gas properties in galaxy mergers

NASA Astrophysics Data System (ADS)

Violino, Giulio; Ellison, Sara L.; Sargent, Mark; Coppin, Kristen E. K.; Scudder, Jillian M.; Mendel, Trevor J.; Saintonge, Amelie

2018-05-01

We investigate the connection between star formation and molecular gas properties in galaxy mergers at low redshift (z ≤ 0.06). The study we present is based on IRAM 30-m CO(1-0) observations of 11 galaxies with a close companion selected from the Sloan Digital Sky Survey (SDSS). The pairs have mass ratios ≤4, projected separations rp ≤ 30 kpc and velocity separations ΔV ≤ 300 km s-1, and have been selected to exhibit enhanced specific star formation rates (sSFRs). We calculate molecular gas (H2) masses, assigning to each galaxy a physically motivated conversion factor αCO, and we derive molecular gas fractions and depletion times. We compare these quantities with those of isolated galaxies from the extended CO Legacy Data base for the GALEX Arecibo SDSS Survey sample (xCOLDGASS; Saintonge et al.) with gas quantities computed in an identical way. Ours is the first study which directly compares the gas properties of galaxy pairs and those of a control sample of normal galaxies with rigorous control procedures and for which SFR and H2 masses have been estimated using the same method. We find that the galaxy pairs have shorter depletion times and an average molecular gas fraction enhancement of 0.4 dex compared to the mass matched control sample drawn from xCOLDGASS. However, the gas masses (and fractions) in galaxy pairs and their depletion times are consistent with those of non-mergers whose SFRs are similarly elevated. We conclude that both external interactions and internal processes may lead to molecular gas enhancement and decreased depletion times.

Loss of Asparagine-Linked Glycosylation Sites in Variable Region 5 of Human Immunodeficiency Virus Type 1 Envelope Is Associated with Resistance to CD4 Antibody Ibalizumab ▿

PubMed Central

Toma, Jonathan; Weinheimer, Steven P.; Stawiski, Eric; Whitcomb, Jeannette M.; Lewis, Stanley T.; Petropoulos, Christos J.; Huang, Wei

2011-01-01

Ibalizumab (formerly TNX-355) is a first-in-class, monoclonal antibody inhibitor of CD4-mediated human immunodeficiency type 1 (HIV-1) entry. Multiple clinical trials with HIV-infected patients have demonstrated the antiviral activity, safety, and tolerability of ibalizumab treatment. A 9-week phase Ib study adding ibalizumab monotherapy to failing drug regimens led to transient reductions in HIV viral loads and the evolution of HIV-1 variants with reduced susceptibility to ibalizumab. This report characterizes these variants by comparing the phenotypic susceptibilities and envelope (env) sequences of (i) paired baseline and on-treatment virus populations, (ii) individual env clones from selected paired samples, and (iii) env clones containing site-directed mutations. Viruses with reduced susceptibility to ibalizumab were found to exhibit reduced susceptibility to the anti-CD4 antibody RPA-T4. Conversely, susceptibility to soluble CD4, which targets the HIV-1 gp120 envelope protein, was enhanced. No changes in susceptibility to the fusion inhibitor enfuvirtide or the CCR5 antagonist maraviroc were observed. Functionally, viruses with reduced ibalizumab susceptibility also displayed high levels of infectivity relative to those of paired baseline viruses. Individual env clones exhibiting reduced ibalizumab susceptibility contained multiple amino acid changes in different regions relative to the paired baseline clones. In particular, clones with reduced susceptibility to ibalizumab contained fewer potential asparagine-linked glycosylation sites (PNGSs) in variable region 5 (V5) than did paired ibalizumab-susceptible clones. The reduction in ibalizumab susceptibility due to the loss of V5 PNGSs was confirmed by site-directed mutagenesis. Taken together, these findings provide important insights into resistance to this new class of antiretroviral drug. PMID:21289125

An entangled-light-emitting diode.

PubMed

Salter, C L; Stevenson, R M; Farrer, I; Nicoll, C A; Ritchie, D A; Shields, A J

2010-06-03

An optical quantum computer, powerful enough to solve problems so far intractable using conventional digital logic, requires a large number of entangled photons. At present, entangled-light sources are optically driven with lasers, which are impractical for quantum computing owing to the bulk and complexity of the optics required for large-scale applications. Parametric down-conversion is the most widely used source of entangled light, and has been used to implement non-destructive quantum logic gates. However, these sources are Poissonian and probabilistically emit zero or multiple entangled photon pairs in most cycles, fundamentally limiting the success probability of quantum computational operations. These complications can be overcome by using an electrically driven on-demand source of entangled photon pairs, but so far such a source has not been produced. Here we report the realization of an electrically driven source of entangled photon pairs, consisting of a quantum dot embedded in a semiconductor light-emitting diode (LED) structure. We show that the device emits entangled photon pairs under d.c. and a.c. injection, the latter achieving an entanglement fidelity of up to 0.82. Entangled light with such high fidelity is sufficient for application in quantum relays, in core components of quantum computing such as teleportation, and in entanglement swapping. The a.c. operation of the entangled-light-emitting diode (ELED) indicates its potential function as an on-demand source without the need for a complicated laser driving system; consequently, the ELED is at present the best source on which to base future scalable quantum information applications.

Everyday conversation requires cognitive inference: neural bases of comprehending implicated meanings in conversations.

PubMed

Jang, Gijeong; Yoon, Shin-ae; Lee, Sung-Eun; Park, Haeil; Kim, Joohan; Ko, Jeong Hoon; Park, Hae-Jeong

2013-11-01

In ordinary conversations, literal meanings of an utterance are often quite different from implicated meanings and the inference about implicated meanings is essentially required for successful comprehension of the speaker's utterances. Inference of finding implicated meanings is based on the listener's assumption that the conversational partner says only relevant matters according to the maxim of relevance in Grice's theory of conversational implicature. To investigate the neural correlates of comprehending implicated meanings under the maxim of relevance, a total of 23 participants underwent an fMRI task with a series of conversational pairs, each consisting of a question and an answer. The experimental paradigm was composed of three conditions: explicit answers, moderately implicit answers, and highly implicit answers. Participants were asked to decide whether the answer to the Yes/No question meant 'Yes' or 'No'. Longer reaction time was required for the highly implicit answers than for the moderately implicit answers without affecting the accuracy. The fMRI results show that the left anterior temporal lobe, left angular gyrus, and left posterior middle temporal gyrus had stronger activation in both moderately and highly implicit conditions than in the explicit condition. Comprehension of highly implicit answers had increased activations in additional regions including the left inferior frontal gyrus, left medial prefrontal cortex, left posterior cingulate cortex and right anterior temporal lobe. The activation results indicate involvement of these regions in the inference process to build coherence between literally irrelevant but pragmatically associated utterances under the maxim of relevance. Especially, the left anterior temporal lobe showed high sensitivity to the level of implicitness and showed increased activation for highly versus moderately implicit conditions, which imply its central role in inference such as semantic integration. The right hemisphere activation, uniquely found in the anterior temporal lobe for highly implicit utterances, suggests its competence for integrating distant concepts in implied utterances under the relevance principle. Copyright © 2013 Elsevier Inc. All rights reserved.

Cofactors involved in light-driven charge separation in photosystem I identified by subpicosecond infrared spectroscopy.

PubMed

Di Donato, Mariangela; Stahl, Andreas D; van Stokkum, Ivo H M; van Grondelle, Rienk; Groot, Marie-Louise

2011-02-01

Photosystem I is one of the key players in the conversion of solar energy into chemical energy. While the chlorophyll dimer P(700) has long been identified as the primary electron donor, the components involved in the primary charge separation process in PSI remain undetermined. Here, we have studied the charge separation dynamics in Photosystem I trimers from Synechococcus elongatus by femtosecond vis-pump/mid-infrared-probe spectroscopy upon excitation at 700, 710, and 715 nm. Because of the high specificity of the infrared region for the redox state and small differences in the molecular structure of pigments, we were able to clearly identify specific marker bands indicating chlorophyll (Chl) oxidation. Magnitudes of chlorophyll cation signals are observed to increase faster than the time resolution of the experiment (~0.2 ps) upon both excitation conditions: 700 nm and selective red excitation. Two models, involving either ultrafast charge separation or charge transfer character of the red pigments in PSI, are discussed to explain this observation. A further increase in the magnitudes of cation signals on a subpicosecond time scale (0.8-1 ps) indicates the formation of the primary radical pair. Evolution in the cation region with time constants of 7 and 40 ps reveals the formation of the secondary radical pair, involving a secondary electron donor. Modeling of the data allows us to extract the spectra of the two radical pairs, which have IR signatures consistent with A+A₀- and P₇₀₀+A₁-. We conclude that the cofactor chlorophyll A acts as the primary donor in PSI. The existence of an equilibrium between the two radical pairs we interpret as concerted hole/electron transfer between the pairs of electron donors and acceptors, until after 40 ps, relaxation leads to a full population of the P₇₀₀+A₁. radical pair.

Remote heterodyne millimeter-wave over fiber based OFDM-PON with master-to-slave injected dual-mode colorless FPLD pair.

PubMed

Chen, Hsiang-Yu; Chi, Yu-Chieh; Lin, Gong-Ru

2015-08-24

A remote heterodyne millimeter-wave (MMW) carrier at 47.7 GHz over fiber synthesized with the master-to-slave injected dual-mode colorless FPLD pair is proposed, which enables the future connection between the wired fiber-optic 64-QAM OFDM-PON at 24 Gb/s with the MMW 4-QAM OFDM wireless network at 2 Gb/s. Both the single- and dual-mode master-to-slave injection-locked colorless FPLD pairs are compared to optimize the proposed 64-QAM OFDM-PON. For the unamplified single-mode master, the slave colorless FPLD successfully performs the 64-QAM OFDM data at 24 Gb/s with EVM, SNR and BER of 8.5%, 21.5 dB and 2.9 × 10(-3), respectively. In contrast, the dual-mode master-to-slave injection-locked colorless FPLD pair with amplified and unfiltered master can transmit 64-QAM OFDM data at 18 Gb/s over 25-km SMF to provide EVM, SNR and BER of 8.2%, 21.8 dB and 2.2 × 10(-3), respectively. For the dual-mode master-to-slave injection-locked colorless FPLD pair, even though the modal dispersion occurred during 25-km SMF transmission makes it sacrifice the usable OFDM bandwidth by only 1 GHz, which guarantees the sufficient encoding bitrate for the optically generated MMW carrier to implement the fusion of MMW wireless LAN and DWDM-PON with cost-effective and compact architecture. As a result, the 47.7-GHz MMW carrier remotely beat from the dual-mode master-to-slave injection-locked colorless FPLD pair exhibits an extremely narrow bandwidth of only 0.48 MHz. After frequency down-conversion operation, the 47.7-GHz MMW carrier successfully delivers 4-QAM OFDM data up to 2 Gb/s with EVM, SNR and BER of 33.5%, 9.51 dB and 1.4 × 10(-3), respectively.

From Understanding the Development Landscape of the Canonical Fate-Switch Pair to Constructing a Dynamic Landscape for Two-Step Neural Differentiation

PubMed Central

2012-01-01

Abstract Recent progress in stem cell biology, notably cell fate conversion, calls for novel theoretical understanding for cell differentiation. The existing qualitative concept of Waddington’s “epigenetic landscape” has attracted particular attention because it captures subsequent fate decision points, thus manifesting the hierarchical (“tree-like”) nature of cell fate diversification. Here, we generalized a recent work and explored such a developmental landscape for a two-gene fate decision circuit by integrating the underlying probability landscapes with different parameters (corresponding to distinct developmental stages). The change of entropy production rate along the parameter changes indicates which parameter changes can represent a normal developmental process while other parameters’ change can not. The transdifferentiation paths over the landscape under certain conditions reveal the possibility of a direct and reversible phenotypic conversion. As the intensity of noise increases, we found that the landscape becomes flatter and the dominant paths more straight, implying the importance of biological noise processing mechanism in development and reprogramming. We further extended the landscape of the one-step fate decision to that for two-step decisions in central nervous system (CNS) differentiation. A minimal network and dynamic model for CNS differentiation was firstly constructed where two three-gene motifs are coupled. We then implemented the SDEs (Stochastic Differentiation Equations) simulation for the validity of the network and model. By integrating the two landscapes for the two switch gene pairs, we constructed the two-step development landscape for CNS differentiation. Our work provides new insights into cellular differentiation and important clues for better reprogramming strategies. PMID:23300518

Enantiomeric and Diastereomeric Self-Assembled Multivalent (SAMul) Nanostructures - Understanding the Effects of Chirality on Binding to Polyanionic Heparin and DNA.

PubMed

Thornalley, Kiri; Laurini, Erik; Pricl, Sabrina; Smith, David K

2018-05-15

A family of four self-assembling lipopeptides containing Ala-Lys peptides attached to a C16 aliphatic chain was synthesised. These compounds form two enantiomeric pairs that bear a diastereomeric relationship to one another (C16-L-Ala-L-Lys/C16-D-Ala-D-Lys) and (C16-D-Ala-L-Lys/C16-L-Ala-D-Lys). These diastereomeric pairs have very different critical micelle concentrations (CMCs), with LL/DD < DL/LD suggesting more effective assembly of the former. The self-assembled multivalent (SAMul) systems bind biological polyanions as result of the cationic lysine groups on their surfaces. Polyanion binding was investigated using dye displacement assays and isothermal calorimetry (ITC). On heparin binding, there was no significant enantioselectivity, but there was a binding preference for the diastereomeric assemblies with lower CMCs. Conversely, on binding DNA, there was a significant enantioselective preference for systems displaying D-lysine ligands, with a further slight preference for attachment to L-alanine, with the CMC being irrelevant. Binding to adaptive, ill-defined heparin has a large favourable entropic term, suggesting it depends primarily on the cationic SAMul nanostructure maximising surface contact with heparin, which can adapt, displacing solvent and other ions. Conversely, binding to well-defined, shape-persistent DNA has a larger favourable enthalpic term, and combined with the enantioselectivity, this allows us to suggest that its SAMul binding is based on optimised individual electrostatic interactions at the molecular level, with a preference for binding to D-lysine. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Cao, H.

We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We also report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0more » to 970 V/cm. For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm. Furthermore, we report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83mKr internal conversion electrons is comparable to that from 207Bi conversion electrons, we obtained the numbers of excitons (N ex) and ion pairs (N i) and their ratio (N ex/N i) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.« less

Pyrrolic-N-doped graphene oxide/Fe2O3 mesocrystal nanocomposite: Efficient charge transfer and enhanced photo-Fenton catalytic activity

NASA Astrophysics Data System (ADS)

Liu, Bing; Tian, Lihong; Wang, Ran; Yang, Jinfeng; Guan, Rong; Chen, Xiaobo

2017-11-01

Though α-Fe2O3 has attracted much attention in photocatalytic or Fenton-catalytic degradation of organic contaminants, its performance is still unsatisfactory due to fast recombination of electrons and holes in photocatalytic process and the difficult conversion of Fe(II) and Fe(III) in Fenton reaction. Herein, a pyrrolic N-doped graphene oxide/Fe2O3 mesocrystal (NG-Fe2O3) nanocomposite with good distribution is synthesized by a simple solvothermal method and adjusting the oxygen-containing groups on graphene oxide. The morphology of NG-Fe2O3 contributes to a relatively large BET surface area and an intimate contact between NG and Fe2O3. These two important factors along with the excellent electro-conductivity of pyrrolic-N doped GO result in the efficient separation of electron-hole pairs and fast conversion of Fe(II)and Fe(III) in photo-Fenton synergistic reaction. Thus, a remarkably improved photo-Fenton catalytic activity of NG-Fe2O3 is obtained. The degrading rate on methyl blue increases by 1.5 times and the conversion rate of glyphosate increases by 2.3 times under visible light irradiation, compared to pristine α-Fe2O3 mesocrystals.

Stochastic and equilibrium pictures of the ultracold Fano-Feshbach-resonance molecular conversion rate

NASA Astrophysics Data System (ADS)

Yamakoshi, Tomotake; Watanabe, Shinichi; Zhang, Chen; Greene, Chris H.

2013-05-01

The ultracold molecular conversion rate occurring in an adiabatic ramp through a Fano-Feshbach resonance is studied and compared in two statistical models. One model, the so-called stochastic phase-space sampling (SPSS) [Hodby , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.94.120402 94, 120402 (2005)] evaluates the overlap of two atomic distributions in phase space by sampling atomic pairs according to a phase-space criterion. The other model, the chemical equilibrium theory (ChET) [Watabe and Nikuni, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.77.013616 77, 013616 (2008)] considers atomic and molecular distributions in the limit of the chemical and thermal equilibrium. The present study applies SPSS and ChET to a prototypical system of K+K→ K2 in all the symmetry combinations, namely Fermi-Fermi, Bose-Bose, and Bose-Fermi cases. To examine implications of the phase-space criterion for SPSS, the behavior of molecular conversion is analyzed using four distinct geometrical constraints. Our comparison of the results of SPSS with those of ChET shows that while they appear similar in most situations, the two models give rise to rather dissimilar behaviors when the presence of a Bose-Einstein condensate strongly affects the molecule formation.

Statistical thermodynamic foundation for photovoltaic and photothermal conversion. IV. Solar cells with larger-than-unity quantum efficiency revisited

NASA Astrophysics Data System (ADS)

Badescu, Viorel; Landsberg, Peter T.; De Vos, Alexis; Desoete, Bart

2001-02-01

A detailed balance solar energy conversion model offering a single treatment of both photovoltaic and photothermal conversion is expounded. It includes a heat rejection mechanism. The effect of multiple impact ionizations on the solar cell efficiency is reconsidered by including the constraints dictated by the first law of thermodynamics (which already exist in the model) and it improves of course the solar cell efficiency. However the upper bound efficiencies previously derived are too optimistic as they do not take into consideration the necessary increase in solar cell temperature. The cell efficiency operating under unconcentrated radiation is a few percent lower than in the ideal case (i.e., with perfect cooling). Wider band gap materials are recommended for those applications where the cell cooling is not effective. The best operation of naturally ventilated cells is under unconcentrated or slightly concentrated solar radiation. Increasing the (forced) ventilation rate allows an increase of the optimum concentration ratio. Additional effects such as the radiation reflectance and radiative pair recombination efficiency are also considered. A sort of threshold minimum band gap depending on the last effect is emphasized: materials with band gaps narrower than this threshold are characterized by very low cell efficiency.

The influence of atmospheric turbulence on partially coherent two-photon entangled field

NASA Astrophysics Data System (ADS)

Qiu, Y.; She, W.

2012-09-01

The propagation of a two-photon field from down-conversion of a partially coherent Gaussian Schell-model (GSM) pump beam in free space has been reported. However, the propagation of this two-photon field through a turbulent atmosphere has not been investigated yet. In this paper, an analytical expression of the coincidence count rate of the two-photon entangled field is derived. Unlike what has been reported, the field is from a parameter down-conversion of a partially coherent dark hollow pump beam and propagates through a turbulent atmosphere. The effects of the propagation parameters on the coincidence count rate are evaluated and illustrated. The results show that the pump beam parameters and atmospheric turbulence can evidently affect the detection probability of the photon pair at two different positions. It is found that the detection probability of the two-photon field is higher, and thus less susceptible to turbulence, if the field is produced by a lower mode of partially coherent pump beam.

Spontaneous parametric down conversion with a depleted pump as an analogue for black hole evaporation/particle production

NASA Astrophysics Data System (ADS)

Alsing, P. M.; Fanto, M. L.

2016-05-01

In this work we argue that black hole evaporation/particle production has a very close analogy to the laboratory process of spontaneous parametric down conversion, when the pump is allowed to deplete. We present an analytical formulation of the recent one-shot decoupling model that was numerically analyzed in Bradler and Adami Phys. Rev. Lett. 116, 101301 (2016) [arXiv:1505.0284]. We compute the resulting "Page Information" curves, which describe the rate at which information escapes form the black hole as it evaporates, for the reduced density matrices for the evaporating black hole internal degrees of freedom, and emitted Hawking radiation pairs entangled across the horizon. The present work reviews and attempts to elucidate the trilinear Hamiltonian models for black hole evaporation/particle production recently investigated by the authors in Class. Quant. Grav 32, 075010 (2015) [arXiv:1408.4491] and Class. Quant. Grav 33, 015005 (2016) [arXiv:1507.00429].

Fibre multi-wave mixing combs reveal the broken symmetry of Fermi-Pasta-Ulam recurrence

NASA Astrophysics Data System (ADS)

Mussot, Arnaud; Naveau, Corentin; Conforti, Matteo; Kudlinski, Alexandre; Copie, Francois; Szriftgiser, Pascal; Trillo, Stefano

2018-05-01

In optical fibres, weak modulations can grow at the expense of a strong pump to form a triangular comb of sideband pairs, until the process is reversed. Repeated cycles of such conversion and back-conversion constitute a manifestation of the universal nonlinear phenomenon known as Fermi-Pasta-Ulam recurrence. However, it remains a major challenge to observe the coexistence of different types of recurrences owing to the spontaneous symmetry-breaking nature of such a phenomenon. Here, we implement a novel non-destructive technique that allows the evolution in amplitude and phase of frequency modes to be reconstructed via post-processing of the fibre backscattered light. We clearly observe how control of the input modulation seed results in different recursive behaviours emerging from the phase-space structure dictated by the spontaneously broken symmetry. The proposed technique is an important tool to characterize other mixing processes and new regimes of rogue-wave formation and wave turbulence in fibre optics.

Cerium chloride stimulated controlled conversion of B-to-Z DNA in self-assembled nanostructures.

PubMed

Bhanjadeo, Madhabi M; Nayak, Ashok K; Subudhi, Umakanta

2017-01-22

DNA adopts different conformation not only because of novel base pairs but also while interacting with inorganic or organic compounds. Self-assembled branched DNA (bDNA) structures or DNA origami that change conformation in response to environmental cues hold great promises in sensing and actuation at the nanoscale. Recently, the B-Z transition in DNA is being explored to design various nanomechanical devices. In this communication we have demonstrated that Cerium chloride binds to the phosphate backbone of self-assembled bDNA structure and induce B-to-Z transition at physiological concentration. The mechanism of controlled conversion from right-handed to left-handed has been assayed by various dye binding studies using CD and fluorescence spectroscopy. Three different bDNA structures have been identified to display B-Z transition. This approach provides a rapid and reversible means to change bDNA conformation, which can be used for dynamic and progressive control at the nanoscale. Copyright © 2016 Elsevier Inc. All rights reserved.

A terahertz in-line polarization converter based on through-via connected double layer slot structures

PubMed Central

Woo, Jeong Min; Hussain, Sajid; Jang, Jae-Hyung

2017-01-01

A terahertz (THz) in-line polarization converter that yields a polarization conversion ratio as high as 99.9% is demonstrated at 1 THz. It has double-layer slot structures oriented in orthogonal directions that are electrically connected by 1/8-wavelngth-long through-via holes beside the slot structures. The slots on the front metal-plane respond to the incident THz wave with polarization orthogonal to the slots and generates a circulating surface current around the slots. The surface current propagates along a pair of through-via holes that function as a two-wire transmission line. The propagating current generates a surface current around the backside slot structures oriented orthogonal to the slot structures on the front metal layer. The circulating current generates a terahertz wave polarized orthogonal to the backside slot structures and the 90° polarization conversion is completed. The re-radiating THz wave with 90° converted polarization propagates in the same direction as the incident THz wave. PMID:28211498

Tuning single-photon sources for telecom multi-photon experiments.

PubMed

Greganti, Chiara; Schiansky, Peter; Calafell, Irati Alonso; Procopio, Lorenzo M; Rozema, Lee A; Walther, Philip

2018-02-05

Multi-photon state generation is of great interest for near-future quantum simulation and quantum computation experiments. To-date spontaneous parametric down-conversion is still the most promising process, even though two major impediments still exist: accidental photon noise (caused by the probabilistic non-linear process) and imperfect single-photon purity (arising from spectral entanglement between the photon pairs). In this work, we overcome both of these difficulties by (1) exploiting a passive temporal multiplexing scheme and (2) carefully optimizing the spectral properties of the down-converted photons using periodically-poled KTP crystals. We construct two down-conversion sources in the telecom wavelength regime, finding spectral purities of > 91%, while maintaining high four-photon count rates. We use single-photon grating spectrometers together with superconducting nanowire single-photon detectors to perform a detailed characterization of our multi-photon source. Our methods provide practical solutions to produce high-quality multi-photon states, which are in demand for many quantum photonics applications.

Matching in an undisturbed natural human environment.

PubMed

McDowell, J J; Caron, Marcia L

2010-05-01

Data from the Oregon Youth Study, consisting of the verbal behavior of 210 adolescent boys determined to be at risk for delinquency (targets) and 210 of their friends (peers), were analyzed for their conformance to the complete family of matching theory equations in light of recent findings from the basic science, and using recently developed analytic techniques. Equations of the classic and modern theories of matching were fitted as ensembles to rates and time allocations of the boys' rule-break and normative talk obtained from conversations between pairs of boys. The verbal behavior of each boy in a conversation was presumed to be reinforced by positive social responses from the other boy. Consistent with recent findings from the basic science, the boys' verbal behavior was accurately described by the modern but not the classic theory of matching. These findings also add support to the assertion that basic principles and processes that are known to govern behavior in laboratory experiments also govern human social behavior in undisturbed natural environments.

Supramolecular photochemistry and solar cells

PubMed

Iha

2000-01-01

Supramolecular photochemistry as well as solar cells are fascinating topics of current interest in Inorganic Photochemistry and very active research fields which have attracted wide attention in last two decades. A brief outline of the investigations in these fields carried out in our Laboratory of Inorganic Photochemistry and Energy Conversion is given here with no attempt of an exhaustive coverage of the literature. The emphasis is placed on recent work and information on the above mentioned subjects. Three types of supramolecular systems have been the focus of this work: (i) cage-type coordination compounds; (ii) second-sphere coordination compounds, exemplified by ion-pair photochemistry of cobalt complexes and (iii) covalently-linked systems. In the latter, modulation of the photoluminescence and photochemistry of some rhenium complexes are discussed. Solar energy conversion and development of thin-layer photoelectrochemical solar cells based on sensitization of nanocrystalline semiconductor films by some ruthenium polypyridyl complexes are presented as an important application that resulted from specifically engineered artificial assemblies.

Major merging history in CANDELS. I. Evolution of the incidence of massive galaxy-galaxy pairs from z = 3 to z ˜ 0

NASA Astrophysics Data System (ADS)

Mantha, Kameswara Bharadwaj; McIntosh, Daniel H.; Brennan, Ryan; Ferguson, Henry C.; Kodra, Dritan; Newman, Jeffrey A.; Rafelski, Marc; Somerville, Rachel S.; Conselice, Christopher J.; Cook, Joshua S.; Hathi, Nimish P.; Koo, David C.; Lotz, Jennifer M.; Simmons, Brooke D.; Straughn, Amber N.; Snyder, Gregory F.; Wuyts, Stijn; Bell, Eric F.; Dekel, Avishai; Kartaltepe, Jeyhan; Kocevski, Dale D.; Koekemoer, Anton M.; Lee, Seong-Kook; Lucas, Ray A.; Pacifici, Camilla; Peth, Michael A.; Barro, Guillermo; Dahlen, Tomas; Finkelstein, Steven L.; Fontana, Adriano; Galametz, Audrey; Grogin, Norman A.; Guo, Yicheng; Mobasher, Bahram; Nayyeri, Hooshang; Pérez-González, Pablo G.; Pforr, Janine; Santini, Paola; Stefanon, Mauro; Wiklind, Tommy

2018-04-01

The rate of major galaxy-galaxy merging is theoretically predicted to steadily increase with redshift during the peak epoch of massive galaxy development (1 ≤ z ≤ 3). We use close-pair statistics to objectively study the incidence of massive galaxies (stellar M1 > 2 × 1010 M⊙) hosting major companions (1 ≤ M1/M2 ≤ 4; i.e. <4:1) at six epochs spanning 0 < z < 3. We select companions from a nearly complete, mass-limited (≥5 × 109 M⊙) sample of 23 696 galaxies in the five Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey fields and the Sloan Digital Sky Survey. Using 5-50 kpc projected separation and close redshift proximity criteria, we find that the major companion fraction fmc(z) based on stellar mass-ratio (MR) selection increases from 6 per cent (z ˜ 0) to 16 per cent (z ˜ 0.8), then turns over at z ˜ 1 and decreases to 7 per cent (z ˜ 3). Instead, if we use a major F160W flux-ratio (FR) selection, we find that fmc(z) increases steadily until z = 3 owing to increasing contamination from minor (MR > 4:1) companions at z > 1. We show that these evolutionary trends are statistically robust to changes in companion proximity. We find disagreements between published results are resolved when selection criteria are closely matched. If we compute merger rates using constant fraction-to-rate conversion factors (Cmerg,pair = 0.6 and Tobs,pair = 0.65 Gyr), we find that MR rates disagree with theoretical predictions at z > 1.5. Instead, if we use an evolving Tobs,pair(z) ∝ (1 + z)-2 from Snyder et al., our MR-based rates agree with theory at 0 < z < 3. Our analysis underscores the need for detailed calibration of Cmerg,pair and Tobs,pair as a function of redshift, mass, and companion selection criteria to better constrain the empirical major merger history.

Sex differences during humor appreciation in child-sibling pairs.

PubMed

Vrticka, Pascal; Neely, Michelle; Walter Shelly, Elizabeth; Black, Jessica M; Reiss, Allan L

2013-01-01

The developmental origin of sex differences in adult brain function is poorly understood. Elucidating neural mechanisms underlying comparable cognitive functionality in both children and adults is required to address this gap. Humor appreciation represents a particularly relevant target for such developmental research because explanatory theories apply across the life span, and underlying neurocircuitry shows sex differences in adults. As a positive mood state, humor is also of interest due to sex differences in rates of depression, a disorder afflicting twice as many women as men. In this study, we employed functional magnetic resonance imaging (fMRI) to investigate brain responses to funny versus positive (and neutral) video clips in 22 children, ages 6-13 years, including eight sibling-pairs. Our data revealed increased activity to funny clips in bilateral temporo-occipital cortex, midbrain, and amygdala in girls. Conversely, we found heightened activation to positive clips in bilateral inferior parietal lobule, fusiform gyrus, inferior frontal gyrus, amygdala, and ventromedial prefrontal cortex in boys. Many of these effects persisted when looking at sibling-pairs only. We interpret such findings as reflecting the presence of early sex divergence in reward saliency or expectation and stimulus relevance attribution. These findings are discussed in the context of evolutionary and developmental theories of humor function.

Determination of the Point-Spread Function for the FERMI Large Area Telescope from On-Orbit Data and Limits on Pair Halos of Active Galactic Nuclei

DOE PAGES

Ackermann, M.; Ajello, M.; Allafort, A.; ...

2013-02-15

We present the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to detect photons with energies from ≈20 MeV to >300 GeV. The pre-launch response functions of the LAT were determined through extensive Monte Carlo simulations and beam tests. The point-spread function (PSF) characterizing the angular distribution of reconstructed photons as a function of energy and geometry in the detector is determined here from two years of on-orbit data by examining the distributions of γ rays from pulsars and active galactic nuclei (AGNs). Above 3 GeV, the PSF is found to be broadermore » than the pre-launch PSF. We checked for dependence of the PSF on the class of γ-ray source and observation epoch and found none. We also investigated several possible spatial models for pair-halo emission around BL Lac AGNs. Finally, we found no evidence for a component with spatial extension larger than the PSF and set upper limits on the amplitude of halo emission in stacked images of low- and high-redshift BL Lac AGNs and the TeV blazars 1ES0229+200 and 1ES0347–121.« less

Test Rack Development for Extended Operation of Advanced Stirling Convertors at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Dugala, Gina M.

2009-01-01

The U.S. Department of Energy (DOE), Lockheed Martin Space Company (LMSC), Sun power Inc., and NASA Glenn Research Center (GRC) have been developing an Advanced Stirling Radioisotope Generator (ASRG) for use as a power system on space science missions. This generator will make use of free-piston Stirling convertors to achieve higher conversion efficiency than currently available alternatives. NASA GRC's support of ASRG development includes extended operation testing of Advanced Stirling Convertors (ASCs) developed by Sunpower Inc. In the past year, NASA GRC has been building a test facility to support extended operation of a pair of engineering level ASCs. Operation of the convertors in the test facility provides convertor performance data over an extended period of time. Mechanical support hardware, data acquisition software, and an instrumentation rack were developed to prepare the pair of convertors for continuous extended operation. Short-term tests were performed to gather baseline performance data before extended operation was initiated. These tests included workmanship vibration, insulation thermal loss characterization, low-temperature checkout, and fUll-power operation. Hardware and software features are implemented to ensure reliability of support systems. This paper discusses the mechanical support hardware, instrumentation rack, data acquisition software, short-term tests, and safety features designed to support continuous unattended operation of a pair of ASCs.

SEX DIFFERENCES DURING HUMOR APPRECIATION IN CHILD SIBLING-PAIRS

PubMed Central

Vrticka, Pascal; Neely, Michelle; Walter, Elizabeth; Black, Jessica M.; Reiss, Allan L.

2013-01-01

The developmental origin of sex differences in adult brain function is poorly understood. Elucidating neural mechanisms underlying comparable cognitive functionality in both children and adults is required to address this gap. Humor appreciation represents a particularly relevant target for such developmental research because explanatory theories apply across the life span and underlying neurocircuitry shows sex differences in adults. As a positive mood state, humor is also of interest due to sex differences in rates of depression, a disorder afflicting twice as many women as men. In this study, we employed fMRI to investigate brain responses to funny versus positive (and neutral) video clips in 22 children ages 6 to 13 years, including 8 sibling pairs. Our data revealed increased activity to funny clips in bilateral temporo-occipital cortex, midbrain, and amygdala in girls. Conversely, we found heightened activation to positive clips in bilateral inferior parietal lobule, fusiform gyrus, inferior frontal gyrus, amygdala, and ventromedial prefrontal cortex in boys. Many of these effects persisted when looking at sibling-pairs only. We interpret such findings as reflecting the presence of early sex divergence in reward saliency / expectation and stimulus relevance attribution. These findings are discussed in the context of evolutionary and developmental theories of humor function. PMID:23672302

Oxytocin and Social Bonds: The Role of Oxytocin in Perceptions of Romantic Partners’ Bonding Behavior

PubMed Central

Algoe, Sara B.; Kurtz, Laura E.; Grewen, Karen

2017-01-01

In this research, we tested hypotheses about the role of oxytocin in adult human bonding. Inspired by revisiting the research on pair bonding in microtine voles that fueled psychologists’ interest in the role of oxytocin in social life, we drew on recent theory from affective and relationship science to identify a well-defined bonding context for human romantic relationships. We then paired these behaviors and subjective psychological responses with a measure of naturally circulating oxytocin. In 129 romantically involved adults whose partner expressed gratitude to them in the lab, greater oxytocin over the prior 24 hr was associated with greater perceptions of the expresser’s responsiveness and gratitude, as well as greater experienced love, but not general affective reward. Moreover, in this one-time conversation, higher oxytocin acted like rose-colored glasses, attenuating the effect of a partner’s behaviorally coded expressive behavior on perceptions of the expresser’s responsiveness. These results justify future research on the role of oxytocin in psychological aspects of growth processes. PMID:28968183

Oxytocin and Social Bonds: The Role of Oxytocin in Perceptions of Romantic Partners' Bonding Behavior.

PubMed

Algoe, Sara B; Kurtz, Laura E; Grewen, Karen

2017-12-01

In this research, we tested hypotheses about the role of oxytocin in adult human bonding. Inspired by revisiting the research on pair bonding in microtine voles that fueled psychologists' interest in the role of oxytocin in social life, we drew on recent theory from affective and relationship science to identify a well-defined bonding context for human romantic relationships. We then paired these behaviors and subjective psychological responses with a measure of naturally circulating oxytocin. In 129 romantically involved adults whose partner expressed gratitude to them in the lab, greater oxytocin over the prior 24 hr was associated with greater perceptions of the expresser's responsiveness and gratitude, as well as greater experienced love, but not general affective reward. Moreover, in this one-time conversation, higher oxytocin acted like rose-colored glasses, attenuating the effect of a partner's behaviorally coded expressive behavior on perceptions of the expresser's responsiveness. These results justify future research on the role of oxytocin in psychological aspects of growth processes.

Toolbox for the design of LiNbO3-based passive and active integrated quantum circuits

NASA Astrophysics Data System (ADS)

Sharapova, P. R.; Luo, K. H.; Herrmann, H.; Reichelt, M.; Meier, T.; Silberhorn, C.

2017-12-01

We present and discuss perspectives of current developments on advanced quantum optical circuits monolithically integrated in the lithium niobate platform. A set of basic components comprising photon pair sources based on parametric down conversion (PDC), passive routing elements and active electro-optically controllable switches and polarisation converters are building blocks of a toolbox which is the basis for a broad range of diverse quantum circuits. We review the state-of-the-art of these components and provide models that properly describe their performance in quantum circuits. As an example for applications of these models we discuss design issues for a circuit providing on-chip two-photon interference. The circuit comprises a PDC section for photon pair generation followed by an actively controllable modified mach-Zehnder structure for observing Hong-Ou-Mandel interference. The performance of such a chip is simulated theoretically by taking even imperfections of the properties of the individual components into account.

Enhancing photoluminescence yields in lead halide perovskites by photon recycling and light out-coupling

PubMed Central

Richter, Johannes M.; Abdi-Jalebi, Mojtaba; Sadhanala, Aditya; Tabachnyk, Maxim; Rivett, Jasmine P.H.; Pazos-Outón, Luis M.; Gödel, Karl C.; Price, Michael; Deschler, Felix; Friend, Richard H.

2016-01-01

In lead halide perovskite solar cells, there is at least one recycling event of electron–hole pair to photon to electron–hole pair at open circuit under solar illumination. This can lead to a significant reduction in the external photoluminescence yield from the internal yield. Here we show that, for an internal yield of 70%, we measure external yields as low as 15% in planar films, where light out-coupling is inefficient, but observe values as high as 57% in films on textured substrates that enhance out-coupling. We analyse in detail how externally measured rate constants and photoluminescence efficiencies relate to internal recombination processes under photon recycling. For this, we study the photo-excited carrier dynamics and use a rate equation to relate radiative and non-radiative recombination events to measured photoluminescence efficiencies. We conclude that the use of textured active layers has the ability to improve power conversion efficiencies for both LEDs and solar cells. PMID:28008917

Paired related homeobox 1 is associated with the invasive properties of glioblastoma cells.

PubMed

Sugiyama, Mai; Hasegawa, Hitoki; Ito, Satoko; Sugiyama, Kazuya; Maeda, Masao; Aoki, Kosuke; Wakabayashi, Toshihiko; Hamaguchi, Michinari; Natsume, Atsushi; Senga, Takeshi

2015-03-01

Glioblastoma is a highly proliferative and invasive tumor. Despite extensive efforts to develop treatments for glioblastoma, the currently available therapies have only limited effects. To develop novel strategies for glioblastoma treatment, it is crucial to elucidate the molecular mechanisms that promote the invasive properties of glioblastoma. In the present study, we showed that the paired related homeobox 1 (PRRX1) is associated with glioblastoma cell invasion. The depletion of PRRX1 suppressed the invasion and neurosphere formation of glioblastoma cells. Conversely, the exogenous expression of PRRX1 promoted invasion. The Notch signaling pathway, which is an evolutionarily conserved pathway that is essential for developmental processes, plays an important role in the tumorigenesis of glioblastoma. The expression of PRRX1 induced the activation of Notch signaling, and the inhibition of Notch signaling suppressed PRRX1-mediated cell invasion. Our results indicate that activation of Notch signaling by PRRX1 is associated with the promotion of glioblastoma cell invasion.

Quantum nonlinear optics without photons

NASA Astrophysics Data System (ADS)

Stassi, Roberto; Macrı, Vincenzo; Kockum, Anton Frisk; Di Stefano, Omar; Miranowicz, Adam; Savasta, Salvatore; Nori, Franco

2017-08-01

Spontaneous parametric down-conversion is a well-known process in quantum nonlinear optics in which a photon incident on a nonlinear crystal spontaneously splits into two photons. Here we propose an analogous physical process where one excited atom directly transfers its excitation to a pair of spatially separated atoms with probability approaching 1. The interaction is mediated by the exchange of virtual rather than real photons. This nonlinear atomic process is coherent and reversible, so the pair of excited atoms can transfer the excitation back to the first one: the atomic analog of sum-frequency generation of light. The parameters used to investigate this process correspond to experimentally demonstrated values in ultrastrong circuit quantum electrodynamics. This approach can be extended to realize other nonlinear interatomic processes, such as four-atom mixing, and is an attractive architecture for the realization of quantum devices on a chip. We show that four-qubit mixing can efficiently implement quantum repetition codes and, thus, can be used for error-correction codes.

Enhancing photoluminescence yields in lead halide perovskites by photon recycling and light out-coupling.

PubMed

Richter, Johannes M; Abdi-Jalebi, Mojtaba; Sadhanala, Aditya; Tabachnyk, Maxim; Rivett, Jasmine P H; Pazos-Outón, Luis M; Gödel, Karl C; Price, Michael; Deschler, Felix; Friend, Richard H

2016-12-23

In lead halide perovskite solar cells, there is at least one recycling event of electron-hole pair to photon to electron-hole pair at open circuit under solar illumination. This can lead to a significant reduction in the external photoluminescence yield from the internal yield. Here we show that, for an internal yield of 70%, we measure external yields as low as 15% in planar films, where light out-coupling is inefficient, but observe values as high as 57% in films on textured substrates that enhance out-coupling. We analyse in detail how externally measured rate constants and photoluminescence efficiencies relate to internal recombination processes under photon recycling. For this, we study the photo-excited carrier dynamics and use a rate equation to relate radiative and non-radiative recombination events to measured photoluminescence efficiencies. We conclude that the use of textured active layers has the ability to improve power conversion efficiencies for both LEDs and solar cells.

MSP-HTPrimer: a high-throughput primer design tool to improve assay design for DNA methylation analysis in epigenetics.

PubMed

Pandey, Ram Vinay; Pulverer, Walter; Kallmeyer, Rainer; Beikircher, Gabriel; Pabinger, Stephan; Kriegner, Albert; Weinhäusel, Andreas

2016-01-01

Bisulfite (BS) conversion-based and methylation-sensitive restriction enzyme (MSRE)-based PCR methods have been the most commonly used techniques for locus-specific DNA methylation analysis. However, both methods have advantages and limitations. Thus, an integrated approach would be extremely useful to quantify the DNA methylation status successfully with great sensitivity and specificity. Designing specific and optimized primers for target regions is the most critical and challenging step in obtaining the adequate DNA methylation results using PCR-based methods. Currently, no integrated, optimized, and high-throughput methylation-specific primer design software methods are available for both BS- and MSRE-based methods. Therefore an integrated, powerful, and easy-to-use methylation-specific primer design pipeline with great accuracy and success rate will be very useful. We have developed a new web-based pipeline, called MSP-HTPrimer, to design primers pairs for MSP, BSP, pyrosequencing, COBRA, and MSRE assays on both genomic strands. First, our pipeline converts all target sequences into bisulfite-treated templates for both forward and reverse strand and designs all possible primer pairs, followed by filtering for single nucleotide polymorphisms (SNPs) and known repeat regions. Next, each primer pairs are annotated with the upstream and downstream RefSeq genes, CpG island, and cut sites (for COBRA and MSRE). Finally, MSP-HTPrimer selects specific primers from both strands based on custom and user-defined hierarchical selection criteria. MSP-HTPrimer produces a primer pair summary output table in TXT and HTML format for display and UCSC custom tracks for resulting primer pairs in GTF format. MSP-HTPrimer is an integrated, web-based, and high-throughput pipeline and has no limitation on the number and size of target sequences and designs MSP, BSP, pyrosequencing, COBRA, and MSRE assays. It is the only pipeline, which automatically designs primers on both genomic strands to increase the success rate. It is a standalone web-based pipeline, which is fully configured within a virtual machine and thus can be readily used without any configuration. We have experimentally validated primer pairs designed by our pipeline and shown a very high success rate of primer pairs: out of 66 BSP primer pairs, 63 were successfully validated without any further optimization step and using the same qPCR conditions. The MSP-HTPrimer pipeline is freely available from http://sourceforge.net/p/msp-htprimer.

Advection within side-by-side liquid micro-cylinders in a cross-flow

NASA Astrophysics Data System (ADS)

Dong, Qingming; Sau, Amalendu

2017-11-01

The gaseous SO2 entrainment from outer air stream and dispersion in binary and ternary liquid micro-cylinders appearing side-by-side are examined hereby. The separation/attachment regulated non-uniform interfacial momentum exchange creates main stream driven "primary" and shear reversed "secondary" vortices in the liquid cylinders. At separation points, the sense of rotation of the generated "primary-secondary" vortex pair remains inward directed. We define such a vortex pair as the "inflow" type. However, at stagnation or attachment points, the sense of rotation of a "primary-primary" or "secondary-secondary" vortex pair remains outward directed, and such a vortex pair is defined as the "outflow" type. For the coupled water cylinders facing an oncoming stream contaminated by gaseous SO2, its absorption and internal transport are effectively controlled by dominant "inflow" and "outflow" natured dynamics of the said vortex pairs, besides by diffusion. The evolving "inflow" natured "primary-secondary" vortex pairs at separation points actively entrain the outer SO2, whereas the "outflow" natured vortex-pairs oppose SO2 entry through the stagnation regions. Moreover, the blockage induced steady-symmetric, steady-deflected, and flip-flopping air-jets through gaps, for varied gap-ratio (1 ≤ G/R ≤ 4) and Reynolds number (30 ≤ Re ≤ 160), create distinctive impact both on quantitative SO2 absorption (mso2 ') and convective nature of the SO2 transport in upper, lower, and middle cylinders, by virtue of modified strength and size of the inflow and outflow paired vortices. The present study shows that the tiny "secondary vortices" play important roles in SO2 entrainment and in effectively controlling the local absorption rate Rs o2. The sudden acceleration and upward/downward deflection of gap-flows enhanced near-neck advective SO2 entrainment by suitably strengthening the "inflow" natured local vortex dynamics. Conversely, for the reduced size of secondary vortices, the saturation becomes delayed. In addition, for decreased vertical spacing of micro-cylinders (R = 40 μm) falling below the diameter-length "2R," the SO2 absorption (mso2 ') only gets slower. We provide extensive analysis of two-phase transport phenomena in terms of interactive shear-stress, pressure, and characteristic time-ratio "Tr" of advection-diffusion processes, for varied G/R, Re, and liquid phase Peclet number "Pel" (96 ≤ Pel ≤ 1333), to present a better insight into the governing physics.

Free energy gap laws for the pulse-induced and stationary fluorescence quenching by reversible charge transfer in polar solutions.

PubMed

Khokhlova, Svetlana S; Burshtein, Anatoly I

2011-01-21

The Stern-Volmer constants for either pulse-induced or stationary fluorescence being quenched by a contact charge transfer are calculated and their free energy dependencies (the free energy gap laws) are specified. The reversibility of charge transfer is taken into account as well as spin conversion in radical ion pairs, followed by their recombination in either singlet or triplet neutral products. The natural decay of triplets as well as their impurity quenching by ionization are accounted for when estimating the fluorescence quantum yield and its free energy dependence.

Ti:sapphire-pumped diamond Raman laser with sub-100-fs pulse duration.

PubMed

Murtagh, Michelle; Lin, Jipeng; Mildren, Richard P; Spence, David J

2014-05-15

We report a synchronously pumped femtosecond diamond Raman laser operating at 895 nm with a 33% slope efficiency. Pumped using a mode-locked Ti:sapphire laser at 800 nm with a duration of 170 fs, the bandwidth of the Stokes output is broadened and chirped to enable subsequent pulse compression to 95 fs using a prism pair. Modeling results indicate that self-phase modulation drives the broadening of the Stokes spectrum in this highly transient laser. Our results demonstrate the potential for Raman conversion to extend the wavelength coverage and pulse shorten Ti:sapphire lasers.

From SHG to mid-infrared SPDC generation in strained silicon waveguides

NASA Astrophysics Data System (ADS)

Castellan, Claudio; Trenti, Alessandro; Mancinelli, Mattia; Marchesini, Alessandro; Ghulinyan, Mher; Pucker, Georg; Pavesi, Lorenzo

2017-08-01

The centrosymmetric crystalline structure of Silicon inhibits second order nonlinear optical processes in this material. We report here that, by breaking the silicon symmetry with a stressing silicon nitride over-layer, Second Harmonic Generation (SHG) is obtained in suitably designed waveguides where multi-modal phase-matching is achieved. The modeling of the generated signal provides an effective strain-induced second order nonlinear coefficient of χ(2) = (0.30 +/- 0.02) pm/V. Our work opens also interesting perspectives on the reverse process, the Spontaneous Parametric Down Conversion (SPDC), through which it is possible to generate mid-infrared entangled photon pairs.

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

Behaghel, B.; Institute of Research and Development on Photovoltaic Energy; NextPV, RCAST and CNRS, The University of Tokyo, Meguro-ku, Tokyo 153-8904

We study light management in a 430 nm-thick GaAs p-i-n single junction solar cell with 10 pairs of InGaAs/GaAsP multiple quantum wells (MQWs). The epitaxial layer transfer on a gold mirror improves light absorption and increases the external quantum efficiency below GaAs bandgap by a factor of four through the excitation of Fabry-Perot resonances. We show a good agreement with optical simulation and achieve around 10% conversion efficiency. We demonstrate numerically that this promising result can be further improved by anti-reflection layers. This study paves the way to very thin MQWs solar cells.

High-fidelity transmission of polarization encoded qubits from an entangled source over 100 km of fiber.

PubMed

Hübel, Hannes; Vanner, Michael R; Lederer, Thomas; Blauensteiner, Bibiane; Lorünser, Thomas; Poppe, Andreas; Zeilinger, Anton

2007-06-11

We demonstrate non-degenerate down-conversion at 810 and 1550 nm for long-distance fiber based quantum communication using polarization entangled photon pairs. Measurements of the two-photon visibility, without dark count subtraction, have shown that the quantum correlations (raw visibility 89%) allow secure quantum cryptography after 100 km of non-zero dispersion shifted fiber using commercially available single photon detectors. In addition, quantum state tomography has revealed little degradation of state negativity, decreasing from 0.99 at the source to 0.93 after 100 km, indicating minimal loss in fidelity during the transmission.

Must is a Four Letter Word: The Role of Plasma Instabilities in the Intergalactic Magnetic Field Story

NASA Astrophysics Data System (ADS)

Broderick, Avery

2014-06-01

The detection of inverse Compton halos from cosmological TeV sources provide a direct means to constrain the putative intergalactic magnetic field. However, the converse may not be the case! The fate of the pairs generated by TeV gamma rays annihilating on the extragalactic background light is presently unclear, clouded by the possibility that cosmological scale plasma instabilities may dominate their energetic evolution. I will briefly motivate these plasma instabilities theoretically, summarize some empirical evidence that they may be occurring in practice, and assess their potential impact upon studies of intergalactic magnetic fields.

Recombination-dependent replication and gene conversion homogenize repeat sequences and diversify plastid genome structure.

PubMed

Ruhlman, Tracey A; Zhang, Jin; Blazier, John C; Sabir, Jamal S M; Jansen, Robert K

2017-04-01

There is a misinterpretation in the literature regarding the variable orientation of the small single copy region of plastid genomes (plastomes). The common phenomenon of small and large single copy inversion, hypothesized to occur through intramolecular recombination between inverted repeats (IR) in a circular, single unit-genome, in fact, more likely occurs through recombination-dependent replication (RDR) of linear plastome templates. If RDR can be primed through both intra- and intermolecular recombination, then this mechanism could not only create inversion isomers of so-called single copy regions, but also an array of alternative sequence arrangements. We used Illumina paired-end and PacBio single-molecule real-time (SMRT) sequences to characterize repeat structure in the plastome of Monsonia emarginata (Geraniaceae). We used OrgConv and inspected nucleotide alignments to infer ancestral nucleotides and identify gene conversion among repeats and mapped long (>1 kb) SMRT reads against the unit-genome assembly to identify alternative sequence arrangements. Although M. emarginata lacks the canonical IR, we found that large repeats (>1 kilobase; kb) represent ∼22% of the plastome nucleotide content. Among the largest repeats (>2 kb), we identified GC-biased gene conversion and mapping filtered, long SMRT reads to the M. emarginata unit-genome assembly revealed alternative, substoichiometric sequence arrangements. We offer a model based on RDR and gene conversion between long repeated sequences in the M. emarginata plastome and provide support that both intra-and intermolecular recombination between large repeats, particularly in repeat-rich plastomes, varies unit-genome structure while homogenizing the nucleotide sequence of repeats. © 2017 Botanical Society of America.

Differential regulation of metabolic parameters by energy deficit and hunger.

PubMed

Kitka, Tamás; Tuza, Sebestyén; Varga, Balázs; Horváth, Csilla; Kovács, Péter

2015-10-01

Hypocaloric diet decreases both energy expenditure (EE) and respiratory exchange rate (RER), affecting the efficacy of dieting inversely. Energy deficit and hunger may be modulated separately both in human and animal studies by drug treatment or food restriction. Thus it is important to separate the effects of energy deficit and hunger on EE and RER. Three parallel and analogous experiments were performed using three pharmacologically distinct anorectic drugs: rimonabant, sibutramine and tramadol. Metabolic parameters of vehicle- and drug-treated and pair-fed diet-induced obese mice from the three experiments underwent common statistical analysis to identify effects independent of the mechanisms of action. Diet-induced obesity (DIO) test of tramadol was also performed to examine its anti-obesity efficacy. RER was decreased similarly by drug treatments and paired feeding throughout the experiment irrespective of the cause of reduced food intake. Contrarily, during the passive phase, EE was decreased more by paired feeding than by both vehicle and drug treatment irrespective of the drug used. In the active phase, EE was influenced by the pharmacological mechanisms of action. Tramadol decreased body weight in the DIO test. Our results suggest that RER is mainly affected by the actual state of energy balance; conversely, EE is rather influenced by hunger. Therefore, pharmacological medications that decrease hunger may enhance the efficacy of a hypocaloric diet by maintaining metabolic rate. Furthermore, our results yield the proposal that effects of anorectic drugs on EE and RER should be determined compared to vehicle and pair-fed groups, respectively, in animal models. Copyright © 2015 Elsevier Inc. All rights reserved.

Risk Taking and Decision Making in Kidney Paired Donation: A Qualitative Study by Semistructured Interviews.

PubMed

Baines, L S; Dulku, H; Jindal, R M; Papalois, V

2018-06-01

Despite excellent outcomes of kidney paired donation (KPD), little is known about how a patient's frame (apply cognitive bias) or weight (attribute value) and concerns relating to risk, justice, and equity affect his or her decision-making process. A pilot study consisting of 3 KPD transplant recipients and 3 KPD kidney donors in the last year was conducted to identify and explore themes in decision making and risk taking. The pilot study was followed by the main study comprised of 20 recipients who had already undergone KPD transplantation and 20 donors who had undergone donor nephrectomy. We conducted semistructured interviews in this cohort and analyzed the data thematically. Each donor-recipient pair was interviewed together to facilitate dyadic conversation and provide deeper insight into the decision-making process leading to transplant and donation. Common themes to both recipient and donor decision making included quality of life; characteristics of the unknown donor and post-transplant expectations. Recipient-specific themes included failure to reach life span milestones, experiences of fellow patients, and altruistic desire to expand the donor pool. Donor-specific themes included balancing existing life commitments with the recipient's need for a kidney, equity and mental accounting in kidney exchange (comparable quality of the kidney received versus the kidney donated), and logistical justice for the recipient. Donors and recipients frame and weight the concepts of risk, justice, and equity differently. This may have direct implications to facilitating patient-centered communication and engagement in KPD pairs. Copyright © 2018 Elsevier Inc. All rights reserved.

Conversion from cropland to short rotation coppice willow and poplar: Accumulation of soil organic carbon

NASA Astrophysics Data System (ADS)

Georgiadis, Petros; Stupak, Inge; Vesterdal, Lars; Raulund-Rasmussen, Karsten

2015-04-01

Increased demand for bioenergy has intensified the production of Short Rotation Coppice (SRC) willow and poplar in temperate zones. We used a combined chronosequence and paired plot approach to study the potential of SRC willow and poplar stands to increase the soil carbon stock compared to stocks of the previous arable land-use. The study focused on well-drained soils. We sampled soil from 30 SRC stands in Denmark and southern Sweden including soils from their adjacent arable fields. The 18 willow and 12 poplar stands formed a chronosequence ranging between 4 and 29 years after conversion. The soil was sampled both with soil cores taken by fixed depths of 0-5, 5-10, 10-15, 15-25, and 25-40 cm and by genetic horizons from soil pits to 1m depth. The aim of the study was to estimate the difference and the ratio between soil carbon contents of the SRC and annual crop land and analyze the results as a chronosequence to examine the effect of age after conversion on the difference. Covariates such as soil type, fertilization type and harvest frequency were also taken into account. Preliminary results suggest an overall increase in carbon stocks over time with average accumulation rates ranging from 0.25 to 0.4 Mg ha-1 yr-1 in willow and poplar stands. Poplar stands had higher rates of C gain, probably due to less frequent harvesting. The differences in carbon between the SRC and the paired cropland were initially negative but changed to positive over time, implying loss of carbon after conversion and a later gain in soil carbon with stand age. Pairwise differences ranged from -25 Mg C ha-1 to 37 Mg C ha-1 for the top 40 cm. The carbon stock ratio of the SRC stand to the arable land was estimated to minimize the effect of site-related factors. The results of this analysis suggested that the ratio increased significantly with age after conversion for the top 10 cm of the soil, both for poplar and willow. A slight increase with age was also noticed at the deeper depths, but it was not significant. The increasing soil carbon stocks in SRC stands on former cropland can be attributed to the increased leaf and litter input from the perennial SRC plantations as well as less stimulation of organic matter decomposition after cessation of annual. Initial losses of soil carbon after the land use change have also been reported by other studies, but the soil carbon accumulation high rates suggest that SRC can act as sinks at least for some decades. Our results indicate that a steady state has not yet been reached after 29 years. Key words: Bioenergy,Land Use Change, poplar, Short Rotation Coppice, Soil Organic Carbon, willow,

Simulation of ultra-high energy photon propagation in the geomagnetic field

NASA Astrophysics Data System (ADS)

Homola, P.; Góra, D.; Heck, D.; Klages, H.; PeĶala, J.; Risse, M.; Wilczyńska, B.; Wilczyński, H.

2005-12-01

The identification of primary photons or specifying stringent limits on the photon flux is of major importance for understanding the origin of ultra-high energy (UHE) cosmic rays. UHE photons can initiate particle cascades in the geomagnetic field, which leads to significant changes in the subsequent atmospheric shower development. We present a Monte Carlo program allowing detailed studies of conversion and cascading of UHE photons in the geomagnetic field. The program named PRESHOWER can be used both as an independent tool or together with a shower simulation code. With the stand-alone version of the code it is possible to investigate various properties of the particle cascade induced by UHE photons interacting in the Earth's magnetic field before entering the Earth's atmosphere. Combining this program with an extensive air shower simulation code such as CORSIKA offers the possibility of investigating signatures of photon-initiated showers. In particular, features can be studied that help to discern such showers from the ones induced by hadrons. As an illustration, calculations for the conditions of the southern part of the Pierre Auger Observatory are presented. Catalogue identifier:ADWG Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWG Program obtainable: CPC Program Library, Quen's University of Belfast, N. Ireland Computer on which the program has been thoroughly tested:Intel-Pentium based PC Operating system:Linux, DEC-Unix Programming language used:C, FORTRAN 77 Memory required to execute with typical data:<100 kB No. of bits in a word:32 Has the code been vectorized?:no Number of lines in distributed program, including test data, etc.:2567 Number of bytes in distributed program, including test data, etc.:25 690 Distribution format:tar.gz Other procedures used in PRESHOWER:IGRF [N.A. Tsyganenko, National Space Science Data Center, NASA GSFC, Greenbelt, MD 20771, USA, http://nssdc.gsfc.nasa.gov/space/model/magnetos/data-based/geopack.html], bessik, ran2 [Numerical Recipes, http://www.nr.com]. Nature of the physical problem:Simulation of a cascade of particles initiated by UHE photon passing through the geomagnetic field above the Earth's atmosphere. Method of solution: The primary photon is tracked until its conversion into ee pair or until it reaches the upper atmosphere. If conversion occurred each individual particle in the resultant preshower is checked for either bremsstrahlung radiation (electrons) or secondary gamma conversion (photons). The procedure ends at the top of atmosphere and the shower particle data are saved. Restrictions on the complexity of the problem: Gamma conversion into particles other than electron pair has not been taken into account. Typical running time: 100 preshower events with primary energy 10 eV require a 800 MHz CPU time of about 50 min, with 10 eV the simulation time for 100 events grows up to 500 min.

Formation and evolution of oxygen-vacancy clusters in lead and tin doped silicon

NASA Astrophysics Data System (ADS)

Londos, C. A.; Aliprantis, D.; Sgourou, E. N.; Chroneos, A.; Pochet, P.

2012-06-01

Infrared spectroscopy (IR) measurements were used to investigate the effect of lead (Pb), tin (Sn), and (Pb, Sn) codoping on electron radiation-induced defects in silicon (Si). The study was mainly focused on oxygen-vacancy (VOn) clusters and in particular their formation and evolution upon annealing. It was determined that Pb causes a larger reduction in the production of the VO defect than Sn. In (Pb, Sn) co-doped Si isochronal anneals revealed that the evolution of VO increases substantially at ˜170 °C. This is attributed to the release of V from the SnV pair. Interestingly, in the corresponding evolution curves of VO in the Sn- and the Pb-doped samples, this inverse annealing stage is also present for the former while it is not present for the latter. This is attributed to the formation of PbV pairs that do not dissociate below 280 °C. The partial capture of V by Sn in co-doped samples is rationalized through the higher compressive local strain around Pb atoms that leads to a retardation of vacancy diffusion. The conversion of VO to the VO2 defect is substantially reduced in the Pb-doped sample. The evolution curves of VO and VO2 clusters in the isovalent doped Si samples hint the production of VO2 from other mechanisms (i.e., besides VO + Oi → VO2). For larger VOn clusters (n = 3,4), the signals are very weak in the Pb-doped sample, whereas for n ≥ 5, they are not present in the spectra. Conversely, bands related with the VO5 and VOnCs defects are present in the spectra of the Sn-doped and (Pb, Sn) codoped Si.

Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon

DOE PAGES

Cao, H.

2015-05-26

We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We also report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0more » to 970 V/cm. For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm. Furthermore, we report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83mKr internal conversion electrons is comparable to that from 207Bi conversion electrons, we obtained the numbers of excitons (N ex) and ion pairs (N i) and their ratio (N ex/N i) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.« less

Magnetic field effects on electron transfer reactions involving sextet-spin ( S = 5/2) intermediates generated on photoexcitation of a Cr(III)-porphyrin complex

NASA Astrophysics Data System (ADS)

Mori, Yukie; Hoshino, Mikio; Hayashi, Hisaharu

The excited trip-sextet ( 6 T 1 ) state of chloro-(3-methylimidazol)-( meso -tetraphenylporphyrinato) chromium(III) (Cr III P) is quenched by 1,1 '-dibenzyl-4,4 '-bipyridinium (BV 2+ ) in acetonitrile through electron transfer to give 5 (Cr III P .+ ) and 2 BV .+ . The intermediate is a geminate ion pair in the sextet (Sx) state 6 [ 5 (Cr III P .+ ) 2 BV .+ ], which decays through either the escape from a solvent cage to give the free ions or the spin conversion to the quartet (Qa) state followed by back electron transfer. The free ion yield ( ΦFI ) increased with increasing magnetic field from 0 to 4 T and then slightly decreased from 4 T to 10 T. These magnetic field effects are explained as follows. Under low fields where the Zeeman splitting of the spin sublevels is lower than or comparable with the electron spin dipole-dipole interaction within 5 (Cr III P .+ ), this interaction effectively induces the Sx ⇔Qa conversion of [ 5 (Cr III P .+ ) 2 BV + ] to result in low ΦFI values. Under high fields where the Zeeman splitting is larger than the dipole-dipole interaction, the Sx Qa conversion is decreased with increasing field to cause higher ΦFI values. The slight decrease in ΦFI above 4 T may be due to the Δg mechanism.

A 1 kWel thermoelectric stack for geothermal power generation - Modeling and geometrical optimization

NASA Astrophysics Data System (ADS)

Suter, C.; Jovanovic, Z.; Steinfeld, A.

2012-06-01

A thermoelectric stack composed of arrays of Bi-Te alloy thermoelectric converter (TEC) modules is considered for geothermal heat conversion. The TEC modules consist of Al2O3 plates with surface 30×30 mm2 and 127 p-type (Bi0.2Sb0.8)2Te3 and n-type Bi2(Te0.96Se0.04)3 thermoelement pairs, each having a cross-section of 1.05×1.05 mm2, and with a figure-of-merit of 1 and a heat-to-electricity conversion efficiency of ˜5%. A heat transfer model is formulated to couple conduction in the thermoelements with convection between the Al2O3 plates and the water flow in counter-flow channel configuration. The calculated open-circuit voltages are compared to those resulting from the mean temperature differences across the TEC modules computed by CFD. The investigated parameters are: hot water inlet and outlet temperatures (373 - 413 K and 323 - 363 K, respectively), stack length (300 - 1500 mm), thermoelement length (1 - 4 mm) and hot channel heights (0.2 - 2 mm). The heat transfer model is then applied to optimize a 1 kWel stack with hot water inlet at 393 K and outlet at 353 K for either maximum heat-to-electricity conversion efficiency of 2.9% or minimum size of 0.0044 m3.

What limits photosynthetic energy conversion efficiency in nature? Lessons from the oceans.

PubMed

Falkowski, Paul G; Lin, Hanzhi; Gorbunov, Maxim Y

2017-09-26

Constraining photosynthetic energy conversion efficiency in nature is challenging. In principle, two yield measurements must be made simultaneously: photochemistry, fluorescence and/or thermal dissipation. We constructed two different, extremely sensitive and precise active fluorometers: one measures the quantum yield of photochemistry from changes in variable fluorescence, the other measures fluorescence lifetimes in the picosecond time domain. By deploying the pair of instruments on eight transoceanic cruises over six years, we obtained over 200 000 measurements of fluorescence yields and lifetimes from surface waters in five ocean basins. Our results revealed that the average quantum yield of photochemistry was approximately 0.35 while the average quantum yield of fluorescence was approximately 0.07. Thus, closure on the energy budget suggests that, on average, approximately 58% of the photons absorbed by phytoplankton in the world oceans are dissipated as heat. This extraordinary inefficiency is associated with the paucity of nutrients in the upper ocean, especially dissolved inorganic nitrogen and iron. Our results strongly suggest that, in nature, most of the time, most of the phytoplankton community operates at approximately half of its maximal photosynthetic energy conversion efficiency because nutrients limit the synthesis or function of essential components in the photosynthetic apparatus.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'. © 2017 The Author(s).

Validation of graft and standard liver size predictions in right liver living donor liver transplantation.

PubMed

Chan, See Ching; Lo, Chung Mau; Chok, Kenneth S H; Sharr, William W; Cheung, Tan To; Tsang, Simon H Y; Chan, Albert C Y; Fan, Sheung Tat

2011-12-01

To assess the accuracy of a formula derived from 159 living liver donors to estimate the liver size of a normal subject: standard liver weight (g) = 218 + body weight (kg) × 12.3 + 51 (if male). Standard liver volume (SLV) is attained by a conversion factor of 1.19 mL/g. The total liver volume (TLV) of each of the subsequent consecutive 126 living liver donors was determined using the right liver graft weight (RGW) on the back table, right/left liver volume ratio on computed tomography, and the conversion factor. The estimated right liver graft weight (ERGW) was determined by the right liver volume on computed tomography (CT) and the conversion factor. SLV and ERGW were compared with TLV and RGW, respectively, by paired sample t test. Donor characteristics of both series were similar. SLV and TLV were 1,099.6 ± 139.6 and 1,108.5 ± 175.2 mL, respectively, ( R 2  = 0.476) ( p  = 0.435). The difference between SLV and TLV was only -8.9 ± 128.2 mL (-1.0 ± 11.7%). ERGW and RGW were 601.5 ± 104.1 and 597.1 ± 102.2 g, respectively ( R 2  = 0.781) ( p  = 0.332). The conversion factor from liver weight to volume for this series was 1.20 mL/g. The difference between ERGW and RGW was 4.3 ± 49.8 g (0.3 ± 8.8%). ERGW was smaller than RGW for over 10% (range 0.21-40.66 g) in 18 of the 126 donors. None had the underestimation of RGW by over 20%. SLV and graft weight estimations were accurate using the formula and conversion factor.

Validation of the MDS research criteria for prodromal Parkinson's disease: Longitudinal assessment in a REM sleep behavior disorder (RBD) cohort.

PubMed

Fereshtehnejad, Seyed-Mohammad; Montplaisir, Jacques Y; Pelletier, Amelie; Gagnon, Jean-François; Berg, Daniela; Postuma, Ronald B

2017-06-01

Recently, the International Parkinson and Movement Disorder Society introduced the prodromal criteria for PD. Objectives Our study aimed to examine diagnostic accuracy of the criteria as well as the independence of prodromal markers to predict conversion to PD or dementia with Lewy bodies. This prospective cohort study was performed on 121 individuals with rapid eye movement sleep behavior disorder who were followed annually for 1 to 12 years. Using data from a comprehensive panel of prodromal markers, likelihood ratio and post-test probability of the criteria were calculated at baseline and during each follow-up visit. Forty-eight (39.7%) individuals with rapid eye movement sleep behavior disorder converted to PD/dementia with Lewy bodies. The prodromal criteria had 81.3% sensitivity and 67.9% specificity for conversion to PD/dementia with Lewy bodies at 4-year follow-up. One year before conversion, sensitivity was 100%. The criteria predicted dementia with Lewy bodies with even higher accuracy than PD without dementia at onset. Those who met the threshold of prodromal criteria at baseline had significantly more rapid conversion into a neurodegenerative state (4.8 vs. 9.1 years; P < 0.001). Pair-wise combinations of different prodromal markers showed that markers were independent of one another. The prodromal criteria are a promising tool for predicting incidence of PD/dementia with Lewy bodies and conversion time in a rapid eye movement sleep behavior disorder cohort, with high sensitivity and high specificity with long follow-up. Prodromal markers influence the overall likelihood ratio independently, allowing them to be reliably multiplied. Defining additional markers with high likelihood ratio, further studies with longitudinal assessment and testing thresholds in different target populations will improve the criteria. © 2017 International Parkinson and Movement Disorder Society. © 2017 International Parkinson and Movement Disorder Society.

Minimal model for the secondary structures and conformational conversions in proteins

NASA Astrophysics Data System (ADS)

Imamura, Hideo

Better understanding of protein folding process can provide physical insights on the function of proteins and makes it possible to benefit from genetic information accumulated so far. Protein folding process normally takes place in less than seconds but even seconds are beyond reach of current computational power for simulations on a system of all-atom detail. Hence, to model and explore protein folding process it is crucial to construct a proper model that can adequately describe the physical process and mechanism for the relevant time scale. We discuss the reduced off-lattice model that can express _-helix and ?-hairpin conformations defined solely by a given sequence in order to investigate a protein folding mechanism of conformations such as a ?-hairpin and also to investigate conformational conversions in proteins. The first two chapters introduce and review essential concepts in protein folding modelling physical interaction in proteins, various simple models, and also review computational methods, in particular, the Metropolis Monte Carlo method, its dynamic interpretation and thermodynamic Monte Carlo algorithms. Chapter 3 describes the minimalist model that represents both _-helix and ?-sheet conformations using simple potentials. The native conformation can be specified by the sequence without particular conformational biases to a reference state. In Chapter 4, the model is used to investigate the folding mechanism of ?-hairpins exhaustively using the dynamic Monte Carlo and a thermodynamic Monte Carlo method an effcient combination of the multicanonical Monte Carlo and the weighted histogram analysis method. We show that the major folding pathways and folding rate depend on the location of a hydrophobic. The conformational conversions between _-helix and ?-sheet conformations are examined in Chapter 5 and 6. First, the conformational conversion due to mutation in a non-hydrophobic system and then the conformational conversion due to mutation with a hydrophobic pair at a different position at various temperatures are examined.

Efficiency analysis of betavoltaic elements

NASA Astrophysics Data System (ADS)

Sachenko, A. V.; Shkrebtii, A. I.; Korkishko, R. M.; Kostylyov, V. P.; Kulish, M. R.; Sokolovskyi, I. O.

2015-09-01

The conversion of energy of electrons produced by a radioactive β-source into electricity in a Si and SiC p- n junctions is modeled. The features of the generation function that describes the electron-hole pair production by an electron flux and the emergence of a "dead layer" are discussed. The collection efficiency Q that describes the rate of electron-hole pair production by incident beta particles, is calculated taking into account the presence of the dead layer. It is shown that in the case of high-grade Si p- n junctions, the collection efficiency of electron-hole pairs created by a high-energy electrons flux (such as, e.g., Pm-147 beta flux) is close or equal to unity in a wide range of electron energies. For SiC p-n junctions, Q is near unity only for electrons with relatively low energies of about 5 keV (produced, e.g., by a tritium source) and decreases rapidly with further increase of electron energy. The conditions, under which the influence of the dead layer on the collection efficiency is negligible, are determined. The open-circuit voltage is calculated for realistic values of the minority carriers' diffusion coefficients and lifetimes in Si and SiC p- n junctions, irradiated by a high-energy electrons flux. Our calculations allow to estimate the attainable efficiency of betavoltaic elements.

Working better together: joint leadership development for doctors and managers.

PubMed

Kelly, Nicola

2014-01-01

Traditionally, there have been tensions between frontline healthcare professionals and managers, with well-known stereotypes of difficult consultants and pen-pushing managers. Many junior doctors have limited management experience and have often never even met a manager prior to taking on a consultant role. Based on a successful programme pioneered by Dr Robert Klaber (Imperial, London) we have set-up an innovative scheme for Birmingham Children's Hospital, pairing junior doctors and managers to learn and work together. Our aim was to cultivate positive attitudes and understanding between the two groups, break down inter-professional barriers, and to provide practical leadership experience and education. We recruited 60 managers and doctors to participate in shadowing, conversation, and quality improvement projects. Thought-provoking online materials, blogs, socials, and popular monthly workshops consisting of patient-focused debate and discussion around key leadership themes, have helped to support learning and cement shared values. Formal evaluation has demonstrated an improvement in how participants perceive their knowledge and ability based on key NHS Leadership Framework competencies. Participant feedback has been extremely positive, and everyone plans to continue to incorporate Paired Learning into their continuing professional development. We are now embedding Paired Learning in the on-going educational programme offered at Birmingham Children's Hospital, whilst looking at extending the scheme to include different professional groups and other trusts across the region and nationally.

A Flexible Question-and-Answer Task for Measuring Speech Understanding.

PubMed

Best, Virginia; Streeter, Timothy; Roverud, Elin; Mason, Christine R; Kidd, Gerald

2016-11-24

This report introduces a new speech task based on simple questions and answers. The task differs from a traditional sentence recall task in that it involves an element of comprehension and can be implemented in an ongoing fashion. It also contains two target items (the question and the answer) that may be associated with different voices and locations to create dynamic listening scenarios. A set of 227 questions was created, covering six broad categories (days of the week, months of the year, numbers, colors, opposites, and sizes). All questions and their one-word answers were spoken by 11 female and 11 male talkers. In this study, listeners were presented with question-answer pairs and asked to indicate whether the answer was true or false. Responses were given as simple button or key presses, which are quick to make and easy to score. Two preliminary experiments are presented that illustrate different ways of implementing the basic task. In the first experiment, question-answer pairs were presented in speech-shaped noise, and performance was compared across subjects, question categories, and time, to examine the different sources of variability. In the second experiment, sequences of question-answer pairs were presented amidst competing conversations in an ongoing, spatially dynamic listening scenario. Overall, the question-and-answer task appears to be feasible and could be implemented flexibly in a number of different ways. © The Author(s) 2016.

The Advanced Energetic Pair Telescope (AdEPT}: A Future Medium-Energy Gamma-Ray Balloon (and Explorer?) Mission

NASA Technical Reports Server (NTRS)

Hunter, Stanley D.

2011-01-01

Gamma-ray astrophysics probes the highest energy, exotic phenomena in astrophysics. In the medium-energy regime, 0.1-200 MeV, many astrophysical objects exhibit unique and transitory behavior such as the transition from electron dominated to hadron dominated processes, spectral breaks, bursts, and flares. Medium-energy gamma-ray imaging however, continues to be a major challenge particularly because of high background, low effective area, and low source intensities. The sensitivity and angular resolution required to address these challenges requires a leap in technology. The Advance Energetic Pair Telescope (AdEPT) being developed at GSFC is designed to image gamma rays above 5 MeV via pair production with angular resolution of 1-10 deg. In addition AdEPT will, for the first time, provide high polarization sensitivity in this energy range. This performance is achieved by reducing the effective area in favor of enhanced angular resolution through the use of a low-density gaseous conversion medium. AdEPT is based on the Three-Dimensional Track Imager (3-DTI) technology that combines a large volume Negative Ion Time Projection Chamber (NITPC) with 2-D Micro-Well Detector (MWD) readout. I will review the major science topics addressable with medium-energy gamma-rays and discuss the current status of the AdEPT technology, a proposed balloon instrument, and the design of a future satellite mission.

Possible Detection of a Pair Instability Supernova in the Modern Universe, and Implications for the First Stars

NASA Astrophysics Data System (ADS)

Smith, Nathan

2008-03-01

SN 2006gy radiated far more energy in visual light than any other supernova so far, and potential explanations for its energy demands have implications for galactic chemical evolution and the deaths of the first stars. It remained bright for over 200 days, longer than any normal supernova, and it radiated more than 1051 ergs of luminous energy at visual wavelengths. I argue that this Type IIn supernova was probably the explosion of an extremely massive star like Eta Carinae that retained its hydrogen envelope when it exploded, having suffered relatively little mass loss during its lifetime. That this occurred at roughly Solar metallicity challenges current paradigms for mass loss in massive-star evolution. I explore a few potential explanations for SN2006gy's power source, involving either circumstellar interaction, or instead, the decay of 56Ni to 56Co to 56Fe. If SN 2006gy was powered by the conversion of shock energy into light, then the conditions must be truly extraordinary and traditional interaction models don't work. If SN 2006gy was powered by radioactive decay, then the uncomfortably huge 56Ni mass requires that the star exploded as a pair instability supernova. The mere possibility of this makes SN 2006gy interesting, especially at this meeting, because it is the first good candidate for a genuine pair instability supernova.

Results of a paired catchment analysis of forest thinning in Turkey in relation to forest management options.

PubMed

Yurtseven, Ibrahim; Serengil, Yusuf; Gökbulak, Ferhat; Şengönül, Kamil; Ozhan, Süleyman; Kılıç, Umit; Uygur, Betül; Ozçelik, Mehmet Said

2018-03-15

Adaptation to climate change has become a more serious concern as IPCC assessment reports estimate a rise of up to 2°C in average global temperatures by the end of the century. Several recently published studies have underlined the importance of forest management in mitigating the impacts of climate change and in supporting the adaptation capacity of the ecosystem. This study focuses on the role of water-related forest services in this adaptation process. The effects of forestry practices on streamflow can best be determined by paired watershed analysis. The impact of two cutting treatments on runoff was analyzed by a paired experimental watershed study in the Belgrade Forest and the results were evaluated in relation to similar experiments conducted around the world. Forest thinning treatments at 11% and 18% were carried out in a mature oak-beech forest ecosystem over different time periods. Although the thinning increased the runoff statistically, the amount of surplus water remained <5% of the annual water yield. Evidently, the hydrologic response of the watersheds was low due to the reduced intensity of the timber harvest. Finally, the results were combined with those of global studies on thinning, clearcutting and species conversion with the aim of formulating management options for adaptation. Copyright © 2017 Elsevier B.V. All rights reserved.

Are preference and resistance to change convergent expressions of stimulus value?

PubMed

Podlesnik, Christopher A; Jimenez-Gomez, Corina; Shahan, Timothy A

2013-07-01

Behavioral momentum theory asserts that preference and relative resistance to disruption depend on reinforcement rates and provide converging expressions of the conditioned value of discriminative stimuli. However, preference and resistance to disruption diverge when assessing preference during brief extinction probes. We expanded upon this opposing relation by arranging target stimuli signaling equal variable-interval schedules across components of a multiple schedule. We paired one target stimulus with a richer reinforced alternative and the other with a leaner alternative. Furthermore, we varied reinforcement rates for the paired alternatives to assess the effects of manipulating relative conditioned value on preference and resistance to disruption by presession feeding, intercomponent food, and extinction. We replicated the opposing relation between preference and resistance to disruption but varying reinforcement rates for the paired alternatives did not systematically affect preference or resistance to disruption beyond levels observed in our initial condition. Importantly, we found that only preference between the target stimuli was related to relative baseline response rates in the presence of those stimuli. These findings suggest that preference during extinction probes might reveal more about baseline response rates between concurrently available alternatives than relative conditioned value. Resistance to disruption, conversely, appears to better reflect conditioned value because it is less confounded with baseline response rates and is a function of all sources of reinforcement obtained in the presence of a stimulus context. © Society for the Experimental Analysis of Behavior.

A Flexible Question-and-Answer Task for Measuring Speech Understanding

PubMed Central

Streeter, Timothy; Roverud, Elin; Mason, Christine R.; Kidd, Gerald

2016-01-01

This report introduces a new speech task based on simple questions and answers. The task differs from a traditional sentence recall task in that it involves an element of comprehension and can be implemented in an ongoing fashion. It also contains two target items (the question and the answer) that may be associated with different voices and locations to create dynamic listening scenarios. A set of 227 questions was created, covering six broad categories (days of the week, months of the year, numbers, colors, opposites, and sizes). All questions and their one-word answers were spoken by 11 female and 11 male talkers. In this study, listeners were presented with question-answer pairs and asked to indicate whether the answer was true or false. Responses were given as simple button or key presses, which are quick to make and easy to score. Two preliminary experiments are presented that illustrate different ways of implementing the basic task. In the first experiment, question-answer pairs were presented in speech-shaped noise, and performance was compared across subjects, question categories, and time, to examine the different sources of variability. In the second experiment, sequences of question-answer pairs were presented amidst competing conversations in an ongoing, spatially dynamic listening scenario. Overall, the question-and-answer task appears to be feasible and could be implemented flexibly in a number of different ways. PMID:27888257

Kidney Exchange to Overcome Financial Barriers to Kidney Transplantation.

PubMed

Rees, M A; Dunn, T B; Kuhr, C S; Marsh, C L; Rogers, J; Rees, S E; Cicero, A; Reece, L J; Roth, A E; Ekwenna, O; Fumo, D E; Krawiec, K D; Kopke, J E; Jain, S; Tan, M; Paloyo, S R

2017-03-01

Organ shortage is the major limitation to kidney transplantation in the developed world. Conversely, millions of patients in the developing world with end-stage renal disease die because they cannot afford renal replacement therapy-even when willing living kidney donors exist. This juxtaposition between countries with funds but no available kidneys and those with available kidneys but no funds prompts us to propose an exchange program using each nation's unique assets. Our proposal leverages the cost savings achieved through earlier transplantation over dialysis to fund the cost of kidney exchange between developed-world patient-donor pairs with immunological barriers and developing-world patient-donor pairs with financial barriers. By making developed-world health care available to impoverished patients in the developing world, we replace unethical transplant tourism with global kidney exchange-a modality equally benefitting rich and poor. We report the 1-year experience of an initial Filipino pair, whose recipient was transplanted in the United states with an American donor's kidney at no cost to him. The Filipino donor donated to an American in the United States through a kidney exchange chain. Follow-up care and medications in the Philippines were supported by funds from the United States. We show that the logistical obstacles in this approach, although considerable, are surmountable. © 2016 The American Society of Transplantation and the American Society of Transplant Surgeons.

Insights into an original pocket-ligand pair classification: a promising tool for ligand profile prediction.

PubMed

Pérot, Stéphanie; Regad, Leslie; Reynès, Christelle; Spérandio, Olivier; Miteva, Maria A; Villoutreix, Bruno O; Camproux, Anne-Claude

2013-01-01

Pockets are today at the cornerstones of modern drug discovery projects and at the crossroad of several research fields, from structural biology to mathematical modeling. Being able to predict if a small molecule could bind to one or more protein targets or if a protein could bind to some given ligands is very useful for drug discovery endeavors, anticipation of binding to off- and anti-targets. To date, several studies explore such questions from chemogenomic approach to reverse docking methods. Most of these studies have been performed either from the viewpoint of ligands or targets. However it seems valuable to use information from both ligands and target binding pockets. Hence, we present a multivariate approach relating ligand properties with protein pocket properties from the analysis of known ligand-protein interactions. We explored and optimized the pocket-ligand pair space by combining pocket and ligand descriptors using Principal Component Analysis and developed a classification engine on this paired space, revealing five main clusters of pocket-ligand pairs sharing specific and similar structural or physico-chemical properties. These pocket-ligand pair clusters highlight correspondences between pocket and ligand topological and physico-chemical properties and capture relevant information with respect to protein-ligand interactions. Based on these pocket-ligand correspondences, a protocol of prediction of clusters sharing similarity in terms of recognition characteristics is developed for a given pocket-ligand complex and gives high performances. It is then extended to cluster prediction for a given pocket in order to acquire knowledge about its expected ligand profile or to cluster prediction for a given ligand in order to acquire knowledge about its expected pocket profile. This prediction approach shows promising results and could contribute to predict some ligand properties critical for binding to a given pocket, and conversely, some key pocket properties for ligand binding.

Insights into an Original Pocket-Ligand Pair Classification: A Promising Tool for Ligand Profile Prediction

PubMed Central

Reynès, Christelle; Spérandio, Olivier; Miteva, Maria A.; Villoutreix, Bruno O.; Camproux, Anne-Claude

2013-01-01

Pockets are today at the cornerstones of modern drug discovery projects and at the crossroad of several research fields, from structural biology to mathematical modeling. Being able to predict if a small molecule could bind to one or more protein targets or if a protein could bind to some given ligands is very useful for drug discovery endeavors, anticipation of binding to off- and anti-targets. To date, several studies explore such questions from chemogenomic approach to reverse docking methods. Most of these studies have been performed either from the viewpoint of ligands or targets. However it seems valuable to use information from both ligands and target binding pockets. Hence, we present a multivariate approach relating ligand properties with protein pocket properties from the analysis of known ligand-protein interactions. We explored and optimized the pocket-ligand pair space by combining pocket and ligand descriptors using Principal Component Analysis and developed a classification engine on this paired space, revealing five main clusters of pocket-ligand pairs sharing specific and similar structural or physico-chemical properties. These pocket-ligand pair clusters highlight correspondences between pocket and ligand topological and physico-chemical properties and capture relevant information with respect to protein-ligand interactions. Based on these pocket-ligand correspondences, a protocol of prediction of clusters sharing similarity in terms of recognition characteristics is developed for a given pocket-ligand complex and gives high performances. It is then extended to cluster prediction for a given pocket in order to acquire knowledge about its expected ligand profile or to cluster prediction for a given ligand in order to acquire knowledge about its expected pocket profile. This prediction approach shows promising results and could contribute to predict some ligand properties critical for binding to a given pocket, and conversely, some key pocket properties for ligand binding. PMID:23840299

Reversal of alcohol dependence-induced deficits in cue-guided behavior via mGluR2/3 signaling in mice.

PubMed

Barker, Jacqueline M; Lench, Daniel H; Chandler, L Judson

2016-01-01

Alcohol use disorders are associated with deficits in adaptive behavior. While some behavioral impairments that are associated with alcohol use disorders may predate exposure to drugs of abuse, others may result directly from exposure to drugs of abuse, including alcohol. Identifying a causal role for how alcohol exposure leads to these impairments will enable further investigation of the neurobiological mechanisms by which it acts to dysregulate adaptive behavior. In the present study, we examined the effects of chronic intermittent ethanol exposure (CIE) on the use of reward-paired cues to guide consummatory behaviors in a mouse model, and further, how manipulations of mGluR2/3 signaling-known to be dysregulated after chronic alcohol exposure-may alter the expression of this behavior. Adult male C57B/6J mice were trained to self-administer 10 % ethanol and exposed to CIE via vapor inhalation. After CIE exposure, mice were trained in a Pavlovian task wherein a cue (tone) was paired with the delivery of a 10 % sucrose unconditioned stimulus. The use of the reward-paired cue to guide licking behavior was determined across training. The effect of systemic mGluR2/3 manipulation on discrimination between cue-on and cue-off intervals was assessed by administration of the mGluR2/3 agonist LY379268 or the antagonist LY341495 prior to a testing session. Exposure to CIE resulted in reductions in discrimination between cue-on and cue-off intervals, with CIE-exposed mice exhibiting significantly lower consummatory behavior during reward-paired cues than air controls. In addition, systemic administration of an mGluR2/3 agonist restored the use of reward-paired cues in CIE-exposed animals without impacting behavior in air controls. Conversely, administration of an mGluR2/3 antagonist mimicked the effects of CIE on cue-guided licking behavior, indicating that mGluR2/3 signaling can bidirectionally regulate the ability to use reward-paired cues to guide behavior. Together, these data suggest that chronic ethanol exposure drives impairments in the ability to use reward-paired cues to adaptively regulate behavior and that mGluR2/3 receptors represent a therapeutic target for restoration of these deficits in behavioral control in the alcoholic.

The effect of Eimeria maxima infection on the expression of amino acid and sugar transporters aminopeptidase, as well as the di- and tri-peptide transporter PepT1, is not solely due to decreased feed intake.

PubMed

Miska, Katarzyna B; Fetterer, Raymond H

2018-05-01

Coccidiosis caused by Eimeria in poultry is endemic to poultry operations and results in decreased feed intake, diarrhea, and decreased weight gain. The goal was to determine the effect of Eimeria maxima infection on the expression of genes that encode peptide and amino acid transporters (AATs), and also to determine whether decreased feed intake contributes to the change in gene expression by including a pair-fed group of broilers. Three groups of male Ross broilers: 1) not infected, 2) infected, and 3) not infected pair-fed groups were used. Chicks were infected with 1,000 oocysts of E. maxima at 21 d of age. Feed consumption was obtained daily, and at d 0, 3, 5, 7, 10, and 14 post-infection (PI), 6 birds were euthanized, and a portion of the jejunum was removed for qRT-PCR. Infected birds had significantly decreased feed consumption between d 6 to 9 PI. At d 7 PI infected birds had a 45% reduction in weight gain, and pair-fed birds had a 32% reduction in weight gain. The feed conversion ratio at d 7 PI of infected birds was 2.2 while that of pair-fed birds was 1.7, compared to 1.5 in uninfected birds. Growth parameters were more affected in infected birds than in pair-fed birds. By measuring expression levels of nutrient uptake and processing genes via qRT-PCR, it was determined that genes encoding proteins located at the brush border of the gut epithelium were affected by infection as well as change in feed intake. The expression of AATs B°AT, b°,+AT, EAAT3, and PepT1 in infected birds decreased sharply at the height of infection; however, in birds that were pair fed, an increase in expression of b°,+AT, and PepT1 was observed, and little change was seen in expression of B°AT and EAAT3. In summary, the changes in expression of digestive enzymes and nutrient transporters are distinct between coccidia-infected birds compared to healthy pair-fed birds.

Conversion of lowland tropical forests to tree cash crop plantations loses up to one-half of stored soil organic carbon.

PubMed

van Straaten, Oliver; Corre, Marife D; Wolf, Katrin; Tchienkoua, Martin; Cuellar, Eloy; Matthews, Robin B; Veldkamp, Edzo

2015-08-11

Tropical deforestation for the establishment of tree cash crop plantations causes significant alterations to soil organic carbon (SOC) dynamics. Despite this recognition, the current Intergovernmental Panel on Climate Change (IPCC) tier 1 method has a SOC change factor of 1 (no SOC loss) for conversion of forests to perennial tree crops, because of scarcity of SOC data. In this pantropic study, conducted in active deforestation regions of Indonesia, Cameroon, and Peru, we quantified the impact of forest conversion to oil palm (Elaeis guineensis), rubber (Hevea brasiliensis), and cacao (Theobroma cacao) agroforestry plantations on SOC stocks within 3-m depth in deeply weathered mineral soils. We also investigated the underlying biophysical controls regulating SOC stock changes. Using a space-for-time substitution approach, we compared SOC stocks from paired forests (n = 32) and adjacent plantations (n = 54). Our study showed that deforestation for tree plantations decreased SOC stocks by up to 50%. The key variable that predicted SOC changes across plantations was the amount of SOC present in the forest before conversion--the higher the initial SOC, the higher the loss. Decreases in SOC stocks were most pronounced in the topsoil, although older plantations showed considerable SOC losses below 1-m depth. Our results suggest that (i) the IPCC tier 1 method should be revised from its current SOC change factor of 1 to 0.6 ± 0.1 for oil palm and cacao agroforestry plantations and 0.8 ± 0.3 for rubber plantations in the humid tropics; and (ii) land use management policies should protect natural forests on carbon-rich mineral soils to minimize SOC losses.

Advanced laser architectures for high power eyesafe illuminators

NASA Astrophysics Data System (ADS)

Baranova, N.; Pati, B.; Stebbins, K.; Bystryak, I.; Rayno, M.; Ezzo, K.; DePriest, C.

2018-02-01

Q-Peak has demonstrated a novel pulsed eyesafe laser architecture operating with >50 mJ pulse energies at Pulse Repetition Frequencies (PRFs) as high as 320 Hz. The design leverages an Optical Parametric Oscillator (OPO) and Optical Parametric Amplifier (OPA) geometry, which provides the unique capability for high power in a comparatively compact package, while also offering the potential for additional eyesafe power scaling. The laser consists of a Commercial Off-the-Shelf (COTS) Q-switched front-end seed laser to produce pulse-widths around 10 ns at 1.06-μm, which is then followed by a pair of Multi-Pass Amplifier (MPA) architectures (comprised of side-pumped, multi-pass Nd:YAG slabs with a compact diode-pump-array imaging system), and finally involving two sequential nonlinear optical conversion architectures for transfer into the eyesafe regime. The initial seed beam is first amplified through the MPA, and then split into parallel optical paths. An OPO provides effective nonlinear conversion on one optical path, while a second MPA further amplifies the 1.06-μm beam for use in pumping an OPA on the second optical path. These paths are then recombined prior to seeding the OPA. Each nonlinear conversion subsystem utilizes Potassium Titanyl Arsenate (KTA) for effective nonlinear conversion with lower risk to optical damage. This laser architecture efficiently produces pulse energies of >50 mJ in the eyesafe band at PRFs as high as 320 Hz, and has been designed to fit within a volume of 4,500 in3 (0.074 m3 ). We will discuss theoretical and experimental details of the nonlinear optical system for achieving higher eyesafe powers.

Conversion of polycyclic aromatic hydrocarbons on diesel particulate matter upon exposure to ppm levels of ozone

NASA Astrophysics Data System (ADS)

Van Vaeck, L.; Van Cauwenberghe, K.

Diesel exhaust particlulate matter samples were collected from a dilution tunnel using a Hi-Vol cascade impactor. The fraction of the aerosol with aerodynamic diameter below 0.5 μm, retained on the glass fiber back-up filter, was exposed to a flow of ozonised particle free air for periods of 0.5-4 h (1.5 ppm of O 3, flow rate about 40 m 3 h -1). Both exposed and non-exposed reference niters were Soxhlet-extracted with benzene and methanol, and the polycyclic aromatic hydrocarbon fraction (PAH) was isolated by a liquid-liquid partition procedure described in the literature, using cyclohexane and dimethylformamid-water as solvents, modified for quantitative recovery of PAH. The conversion yields of PAH upon exposure to O 3 were determined by single ion monitoring mass spectrometry using a fused silica capillary column for their separation. Significant conversion was observed for PAH from molecular weight 226 to 276. Approximate half lives are of the order of 0.5-1 h for most PAH measured. This high reactivity of PAH on a carbonaceous matrix is probably related to the large specific surface of soot particles as well as to their high adsorptive capacity for gaseous compounds. Lower molecular weight PAH up to chrysene also undergo important physical losses by volatilisation and the extent to which chemical transformations occurred could not be determined accurately. Different reactivities are observed for several isomeric pairs of PAH: benzo(a)pyrene is much faster converted than benzo(e)pyrene, benz(a)anthracene reacts faster than chrysene. The benzo-fluoranthenes are most resistant toward O 3 attack. The implications of these results with respect to atmospheric degradation of PAH, as well as to the occurrence of artefactual conversion upon Hi-Vol sampling are discussed.

In vitro analysis of riboflavin-modified, experimental, two-step etch-and-rinse dentin adhesive: Fourier transform infrared spectroscopy and micro-Raman studies.

PubMed

Daood, Umer; Swee Heng, Chan; Neo Chiew Lian, Jennifer; Fawzy, Amr S

2015-06-26

To modify two-step experimental etch-and-rinse dentin adhesive with different concentrations of riboflavin and to study its effect on the bond strength, degree of conversion, along with resin infiltration within the demineralized dentin substrate, an experimental adhesive-system was modified with different concentrations of riboflavin (m/m, 0, 1%, 3%, 5% and 10%). Dentin surfaces were etched with 37% phosphoric acid, bonded with respective adhesives, restored with restorative composite-resin, and sectioned into resin-dentin slabs and beams to be stored for 24 h or 9 months in artificial saliva. Micro-tensile bond testing was performed with scanning electron microscopy to analyse the failure of debonded beams. The degree of conversion was evaluated with Fourier transform infrared spectroscopy (FTIR) at different time points along with micro-Raman spectroscopy analysis. Data was analyzed with one-way and two-way analysis of variance followed by Tukey's for pair-wise comparison. Modification with 1% and 3% riboflavin increased the micro-tensile bond strength compared to the control at 24 h and 9-month storage with no significant differences in degree of conversion (P<0.05). The most predominant failure mode was the mixed fracture among all specimens except 10% riboflavin-modified adhesive specimens where cohesive failure was predominant. Raman analysis revealed that 1% and 3% riboflavin adhesives specimens showed relatively higher resin infiltration. The incorporation of riboflavin in the experimental two-step etch-and-rinse adhesive at 3% (m/m) improved the immediate bond strengths and bond durability after 9-month storage in artificial saliva without adversely affecting the degree of conversion of the adhesive monomers and resin infiltration.

In vitro analysis of riboflavin-modified, experimental, two-step etch-and-rinse dentin adhesive: Fourier transform infrared spectroscopy and micro-Raman studies

PubMed Central

Daood, Umer; Swee Heng, Chan; Neo Chiew Lian, Jennifer; Fawzy, Amr S

2015-01-01

To modify two-step experimental etch-and-rinse dentin adhesive with different concentrations of riboflavin and to study its effect on the bond strength, degree of conversion, along with resin infiltration within the demineralized dentin substrate, an experimental adhesive-system was modified with different concentrations of riboflavin (m/m, 0, 1%, 3%, 5% and 10%). Dentin surfaces were etched with 37% phosphoric acid, bonded with respective adhesives, restored with restorative composite–resin, and sectioned into resin–dentin slabs and beams to be stored for 24 h or 9 months in artificial saliva. Micro-tensile bond testing was performed with scanning electron microscopy to analyse the failure of debonded beams. The degree of conversion was evaluated with Fourier transform infrared spectroscopy (FTIR) at different time points along with micro-Raman spectroscopy analysis. Data was analyzed with one-way and two-way analysis of variance followed by Tukey's for pair-wise comparison. Modification with 1% and 3% riboflavin increased the micro-tensile bond strength compared to the control at 24 h and 9-month storage with no significant differences in degree of conversion (P<0.05). The most predominant failure mode was the mixed fracture among all specimens except 10% riboflavin-modified adhesive specimens where cohesive failure was predominant. Raman analysis revealed that 1% and 3% riboflavin adhesives specimens showed relatively higher resin infiltration. The incorporation of riboflavin in the experimental two-step etch-and-rinse adhesive at 3% (m/m) improved the immediate bond strengths and bond durability after 9-month storage in artificial saliva without adversely affecting the degree of conversion of the adhesive monomers and resin infiltration. PMID:25257880

Physical aspects of ferroelectric semiconductors for photovoltaic solar energy conversion

NASA Astrophysics Data System (ADS)

Lopez-Varo, Pilar; Bertoluzzi, Luca; Bisquert, Juan; Alexe, Marin; Coll, Mariona; Huang, Jinsong; Jimenez-Tejada, Juan Antonio; Kirchartz, Thomas; Nechache, Riad; Rosei, Federico; Yuan, Yongbo

2016-10-01

Solar energy conversion using semiconductors to fabricate photovoltaic devices relies on efficient light absorption, charge separation of electron-hole pair carriers or excitons, and fast transport and charge extraction to counter recombination processes. Ferroelectric materials are able to host a permanent electrical polarization which provides control over electrical field distribution in bulk and interfacial regions. In this review, we provide a critical overview of the physical principles and mechanisms of solar energy conversion using ferroelectric semiconductors and contact layers, as well as the main achievements reported so far. In a ferroelectric semiconductor film with ideal contacts, the polarization charge would be totally screened by the metal layers and no charge collection field would exist. However, real materials show a depolarization field, smooth termination of polarization, and interfacial energy barriers that do provide the control of interface and bulk electric field by switchable spontaneous polarization. We explore different phenomena as the polarization-modulated Schottky-like barriers at metal/ferroelectric interfaces, depolarization fields, vacancy migration, and the switchable rectifying behavior of ferroelectric thin films. Using a basic physical model of a solar cell, our analysis provides a general picture of the influence of ferroelectric effects on the actual power conversion efficiency of the solar cell device, and we are able to assess whether these effects or their combinations are beneficial or counterproductive. We describe in detail the bulk photovoltaic effect and the contact layers that modify the built-in field and the charge injection and separation in bulk heterojunction organic cells as well as in photocatalytic and water splitting devices. We also review the dominant families of ferroelectric materials that have been most extensively investigated and have provided the best photovoltaic performance.

Uncovering dispersion properties in semiconductor waveguides to study photon-pair generation

NASA Astrophysics Data System (ADS)

Laiho, K.; Pressl, B.; Schlager, A.; Suchomel, H.; Kamp, M.; Höfling, S.; Schneider, C.; Weihs, G.

2016-10-01

We investigate the dispersion properties of ridge Bragg-reflection waveguides to deduce their phasematching characteristics. These are crucial for exploiting them as sources of parametric down-conversion (PDC). In order to estimate the phasematching bandwidth we first determine the group refractive indices of the interacting modes via Fabry-Perot experiments in two distant wavelength regions. Second, by measuring the spectra of the emitted PDC photons, we gain access to their group index dispersion. Our results offer a simple approach for determining the PDC process parameters in the spectral domain, and provide important feedback for designing such sources, especially in the broadband case.

Counter-facing plasma guns for efficient extreme ultra-violet plasma light source

NASA Astrophysics Data System (ADS)

Kuroda, Yusuke; Yamamoto, Akiko; Kuwabara, Hajime; Nakajima, Mitsuo; Kawamura, Tohru; Horioka, Kazuhiko

2013-11-01

A plasma focus system composed of a pair of counter-facing coaxial guns was proposed as a long-pulse and/or repetitive high energy density plasma source. We applied Li as the source of plasma for improvement of the conversion efficiency, the spectral purity, and the repetition capability. For operation of the system with ideal counter-facing plasma focus mode, we changed the system from simple coaxial geometry to a multi-channel configuration. We applied a laser trigger to make synchronous multi-channel discharges with low jitter. The results indicated that the configuration is promising to make a high energy density plasma with high spectral efficiency.

Multi-wavelength and multiband RE-doped optical fiber source array for WDM-GPON applications

NASA Astrophysics Data System (ADS)

Perez-Sanchez, G. G.; Bertoldi-Martins, I.; Gallion, P.; Gosset, C.; Álvarez-Chávez, J. A.

2013-12-01

In this paper, a multiband, multi-wavelength, all-fibre source array consisting of an 810nm pump laser diode, thretwo fiber splitters and three segments of Er-, Tm- and Nd-doped fiber is proposed for PON applications. In the set-up, cascaded pairs of standard fiber gratings are used for extracting the required multiple wavelengths within their corresponding bands. A thorough design parameter description, optical array details and full simulation results, such as: full multi-wavelength spectrum, peak and average powers for each generated wavelength, linewidth at FWHM for each generated signal, and individual and overall conversion efficiency, will be included in the manuscript.

A demonstration of CMOS VLSI circuit prototyping in support of the site facility using the 1.2 micron standard cell library developed by National Security Agency

NASA Technical Reports Server (NTRS)

Smith, Edwyn D.

1991-01-01

Two silicon CMOS application specific integrated circuits (ASICs), a data generation chip, and a data checker chip were designed. The conversion of the data generator circuitry into a pair of CMOS ASIC chips using the 1.2 micron standard cell library is documented. The logic design of the data checker is discussed. The functions of the control circuitry is described. An accurate estimate of timing relationships is essential to make sure that the logic design performs correctly under practical conditions. Timing and delay information are examined.

Quantum circuits for qubit fusion

DOE PAGES

Moussa, Jonathan Edward

2015-12-01

In this article, we consider four-dimensional qudits as qubit pairs and their qudit Pauli operators as qubit Cli ord operators. This introduces a nesting, C 2 1 C C 4 2 C C 2 3, where C m n is the n th level of the m-dimensional qudit Cli ord hierarchy. If we can convert between logical qubits and qudits, then qudit Cli ord operators are qubit non-Cli ord operators. Conversion is achieved by qubit fusion and qudit fission using stabilizer circuits that consume a resource state. This resource is a fused qubit stabilizer state with a fault-tolerant state preparationmore » using stabilizer circuits.« less

Atom-Resonant Heralded Single Photons by Interaction-Free Measurement

NASA Astrophysics Data System (ADS)

Wolfgramm, Florian; de Icaza Astiz, Yannick A.; Beduini, Federica A.; Cerè, Alessandro; Mitchell, Morgan W.

2011-02-01

We demonstrate the generation of rubidium-resonant heralded single photons for quantum memories. Photon pairs are created by cavity-enhanced down-conversion and narrowed in bandwidth to 7 MHz with a novel atom-based filter operating by “interaction-free measurement” principles. At least 94% of the heralded photons are atom-resonant as demonstrated by a direct absorption measurement with rubidium vapor. A heralded autocorrelation measurement shows gc(2)(0)=0.040±0.012, i.e., suppression of multiphoton contributions by a factor of 25 relative to a coherent state. The generated heralded photons can readily be used in quantum memories and quantum networks.

Two-mode thermal-noise squeezing in an electromechanical resonator.

PubMed

Mahboob, I; Okamoto, H; Onomitsu, K; Yamaguchi, H

2014-10-17

An electromechanical resonator is developed in which mechanical nonlinearities can be dynamically engineered to emulate the nondegenerate parametric down-conversion interaction. In this configuration, phonons are simultaneously generated in pairs in two macroscopic vibration modes, resulting in the amplification of their motion. In parallel, two-mode thermal squeezed states are also created, which exhibit fluctuations below the thermal motion of their constituent modes as well as harboring correlations between the modes that become almost perfect as their amplification is increased. The existence of correlations between two massive phonon ensembles paves the way towards an entangled macroscopic mechanical system at the single phonon level.

Using Spatial Correlations of SPDC Sources for Increasing the Signal to Noise Ratio in Images

NASA Astrophysics Data System (ADS)

Ruíz, A. I.; Caudillo, R.; Velázquez, V. M.; Barrios, E.

2017-05-01

We experimentally show that, by using spatial correlations of photon pairs produced by Spontaneous Parametric Down-Conversion, it is possible to increase the Signal to Noise Ratio in images of objects illuminated with those photons; in comparison, objects illuminated with light from a laser present a minor ratio. Our simple experimental set-up was capable to produce an average improvement in signal to noise ratio of 11dB of Parametric Down-Converted light over laser light. This simple method can be easily implemented for obtaining high contrast images of faint objects and for transmitting information with low noise.

All-fiber mode converter based on superimposed long period fiber gratings

NASA Astrophysics Data System (ADS)

Xue, Yan-ru; Bi, Wei-hong; Jin, Wa; Tian, Peng-fei; Jiang, Peng; Liu, Qiang; Jin, Yun

2018-03-01

In this paper, a novel broadband all-fiber mode converter is proposed and experimentally demonstrated. Through writing a pair of superimposed long period fiber gratings (SLPFGs) in tow-mode fiber (TMF) with a CO2 laser, the mode converter can realize the conversion from LP01 to LP11 owing to the phase matching condition. Numerical and experimental results show that the bandwidth of this mode converter is 3 times broader than that of a single grating converter. The converter has low loss, high coupling efficiency, small size and is easy to fabricate, so it can be widely used in mode-division multiplexing.

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

Moussa, Jonathan Edward

In this article, we consider four-dimensional qudits as qubit pairs and their qudit Pauli operators as qubit Cli ord operators. This introduces a nesting, C 2 1 C C 4 2 C C 2 3, where C m n is the n th level of the m-dimensional qudit Cli ord hierarchy. If we can convert between logical qubits and qudits, then qudit Cli ord operators are qubit non-Cli ord operators. Conversion is achieved by qubit fusion and qudit fission using stabilizer circuits that consume a resource state. This resource is a fused qubit stabilizer state with a fault-tolerant state preparationmore » using stabilizer circuits.« less

Cdk1 Phosphorylates Drosophila Sas-4 to Recruit Polo to Daughter Centrioles and Convert Them to Centrosomes.

PubMed

Novak, Zsofia A; Wainman, Alan; Gartenmann, Lisa; Raff, Jordan W

2016-06-20

Centrosomes and cilia are organized by a centriole pair comprising an older mother and a younger daughter. Centriole numbers are tightly regulated, and daughter centrioles (which assemble in S phase) cannot themselves duplicate or organize centrosomes until they have passed through mitosis. It is unclear how this mitotic "centriole conversion" is regulated, but it requires Plk1/Polo kinase. Here we show that in flies, Cdk1 phosphorylates the conserved centriole protein Sas-4 during mitosis. This creates a Polo-docking site that helps recruit Polo to daughter centrioles and is required for the subsequent recruitment of Asterless (Asl), a protein essential for centriole duplication and mitotic centrosome assembly. Point mutations in Sas-4 that prevent Cdk1 phosphorylation or Polo docking do not block centriole disengagement during mitosis, but block efficient centriole conversion and lead to embryonic lethality. These observations can explain why daughter centrioles have to pass through mitosis before they can duplicate and organize a centrosome. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Vacancy-oxygen defects in p-type Si1-xGex

NASA Astrophysics Data System (ADS)

Sgourou, E. N.; Londos, C. A.; Chroneos, A.

2014-10-01

Oxygen-vacancy defects and, in particular, the VO pairs (known as A-centers) are common defects in silicon (Si) with a deleterious impact upon its properties. Although oxygen-vacancy defects have been extensively studied in Si there is far less information about their properties in p-type doped silicon germanium (Si1-xGex). Here, we use Fourier transform infrared spectroscopy to determine the production and evolution of oxygen-vacancy defects in p-type Si1-xGex. It was determined that the increase of Ge content affects the production and the annealing behavior of the VO defect as well as its conversion to the VO2 defect. In particular, both the VO production and the VO annealing temperature are reduced with the increase of Ge. The conversion ratio [VO2]/[VO] also decreases with the increase of x, although the ratios [VO3]/[VO2] and [VO4]/[VO3] show a tendency to increase for larger Ge contents. The results are discussed in view of recent experimental and theoretical studies in Si and Si1-xGex.

Electro-optic voltage sensor with Multiple Beam Splitting

DOEpatents

Woods, Gregory K.; Renak, Todd W.; Crawford, Thomas M.; Davidson, James R.

2000-01-01

A miniature electro-optic voltage sensor system capable of accurate operation at high voltages without use of the dedicated voltage dividing hardware. The invention achieves voltage measurement without significant error contributions from neighboring conductors or environmental perturbations. The invention employs a transmitter, a sensor, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor. Within the sensor the beam undergoes the Pockels electro-optic effect. The electro-optic effect produces a modulation of the beam's polarization, which is in turn converted to a pair of independent conversely-amplitude-modulated signals, from which the voltage of the E-field is determined by the signal processor. The use of converse AM signals enables the signal processor to better distinguish signal from noise. The sensor converts the beam by splitting the beam in accordance with the axes of the beam's polarization state (an ellipse) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured.

High-quality LaVO 3 films as solar energy conversion material

DOE PAGES

Zhang, Hai -Tian; Brahlek, Matthew; Ji, Xiaoyu; ...

2017-03-21

Mott insulating oxides and their heterostructures have recently been identified as potential photovoltaic materials with favorable absorption properties and an intrinsic built-in electric field that can efficiently separate excited electron hole pairs. At the same time, they are predicted to overcome the Shockley-Queisser limit due to strong electron electron interaction present. Despite these premises a high concentration of defects commonly observed in Mott insulating films acting as recombination centers can derogate the photovoltaic conversion efficiency. With use of the self-regulated growth kinetics in hybrid molecular beam epitaxy, this obstacle can be overcome. High-quality, stoichiometric LaVO 3 films were grown withmore » defect densities of in-gap states up to 2 orders of magnitude lower compared to the films in the literature, and a factor of 3 lower than LaVO 3 bulk single crystals. Photoconductivity measurements revealed a significant photoresponsivity increase as high as tenfold of stoichiometric LaVO 3 films compared to their nonstoichiometric counterparts. Furthermore, this work marks a critical step toward the realization of high-performance Mott insulator solar cells beyond conventional semiconductors.« less

Conversions of formaldehyde-modified 2'-deoxyadenosine 5'-monophosphate in conditions modeling formalin-fixed tissue dehydration.

PubMed

Rait, Vladimir K; Zhang, Qingrong; Fabris, Daniele; Mason, Jeffrey T; O'Leary, Timothy J

2006-03-01

Formalin-fixed, paraffin-embedded specimens typically provide molecular biologists with low yields of extractable nucleic acids that exhibit extensive strand cleavage and covalent modification of nucleic acid bases. This study supports the idea that these deleterious effects are promoted by the first step in formalin-fixed tissue processing--i.e., tissue dehydration with a graded series of alcohols. We analyzed the conversions of formaldehyde-modified 2'-deoxyadenosine 5'-monophosphate (dAMP) by reverse-phase ion-pair, high-performance liquid chromatography and found that dehydration does not stabilize N-methylol groups in the modified nucleotide. Furthermore, spontaneous demodification in a dry state or in anhydrous ethanol can be as fast as it is in aqueous solutions if the preparation is contaminated with salts of orthophosphoric acid. In ethanol, orthophosphates also catalyze formation of abundant N6-ethoxymethyl-dAMP, as well as cross-linking and depurination of nucleotides present in the mixture. Identification of the products was performed using ultraviolet absorbance spectroscopy and electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry. Alternatives to the traditional processing of formalin-fixed tissues are discussed.

Status of Kilowatt-Class Stirling Power Conversion Using a Pumped NaK Loop for Thermal Input

NASA Technical Reports Server (NTRS)

Briggs, Maxwell H.; Geng, Steven M.; Robbie, Malcolm G.

2010-01-01

Free-piston Stirling power conversion has been identified as a viable option for potential Fission Surface Power (FSP) systems on the Moon and Mars. Proposed systems consist of two or more Stirling convertors, in a dual-opposed configuration, coupled to a low-temperature uranium-dioxide-fueled, liquid-metal-cooled reactor. To reduce developmental risks associated with liquid-metal loop integration, a test rig has been built to evaluate the performance of a pair of 1-kW free-piston Stirling convertors using a pumped sodium-potassium (NaK) loop for thermal energy input. Baseline performance maps have been generated at the Glenn Research Center (GRC) for these 1-kW convertors operating with an electric heat source. Each convertor was then retrofitted with a custom-made NaK heater head and integrated into a pumped NaK system at the Marshall Space Flight Center (MSFC). This paper documents baseline testing at GRC as well as the progress made in integrating the Stirling convertors into the pumped NaK loop.

The physics of solid-state neutron detector materials and geometries.

PubMed

Caruso, A N

2010-11-10

Detection of neutrons, at high total efficiency, with greater resolution in kinetic energy, time and/or real-space position, is fundamental to the advance of subfields within nuclear medicine, high-energy physics, non-proliferation of special nuclear materials, astrophysics, structural biology and chemistry, magnetism and nuclear energy. Clever indirect-conversion geometries, interaction/transport calculations and modern processing methods for silicon and gallium arsenide allow for the realization of moderate- to high-efficiency neutron detectors as a result of low defect concentrations, tuned reaction product ranges, enhanced effective omnidirectional cross sections and reduced electron-hole pair recombination from more physically abrupt and electronically engineered interfaces. Conversely, semiconductors with high neutron cross sections and unique transduction mechanisms capable of achieving very high total efficiency are gaining greater recognition despite the relative immaturity of their growth, lithographic processing and electronic structure understanding. This review focuses on advances and challenges in charged-particle-based device geometries, materials and associated mechanisms for direct and indirect transduction of thermal to fast neutrons within the context of application. Calorimetry- and radioluminescence-based intermediate processes in the solid state are not included.

High-Quality LaVO3 Films as Solar Energy Conversion Material.

PubMed

Zhang, Hai-Tian; Brahlek, Matthew; Ji, Xiaoyu; Lei, Shiming; Lapano, Jason; Freeland, John W; Gopalan, Venkatraman; Engel-Herbert, Roman

2017-04-12

Mott insulating oxides and their heterostructures have recently been identified as potential photovoltaic materials with favorable absorption properties and an intrinsic built-in electric field that can efficiently separate excited electron-hole pairs. At the same time, they are predicted to overcome the Shockley-Queisser limit due to strong electron-electron interaction present. Despite these premises a high concentration of defects commonly observed in Mott insulating films acting as recombination centers can derogate the photovoltaic conversion efficiency. With use of the self-regulated growth kinetics in hybrid molecular beam epitaxy, this obstacle can be overcome. High-quality, stoichiometric LaVO 3 films were grown with defect densities of in-gap states up to 2 orders of magnitude lower compared to the films in the literature, and a factor of 3 lower than LaVO 3 bulk single crystals. Photoconductivity measurements revealed a significant photoresponsivity increase as high as tenfold of stoichiometric LaVO 3 films compared to their nonstoichiometric counterparts. This work marks a critical step toward the realization of high-performance Mott insulator solar cells beyond conventional semiconductors.

High-Efficiency Selective Electron Tunnelling in a Heterostructure Photovoltaic Diode.

PubMed

Jia, Chuancheng; Ma, Wei; Gu, Chunhui; Chen, Hongliang; Yu, Haomiao; Li, Xinxi; Zhang, Fan; Gu, Lin; Xia, Andong; Hou, Xiaoyuan; Meng, Sheng; Guo, Xuefeng

2016-06-08

A heterostructure photovoltaic diode featuring an all-solid-state TiO2/graphene/dye ternary interface with high-efficiency photogenerated charge separation/transport is described here. Light absorption is accomplished by dye molecules deposited on the outside surface of graphene as photoreceptors to produce photoexcited electron-hole pairs. Unlike conventional photovoltaic conversion, in this heterostructure both photoexcited electrons and holes tunnel along the same direction into graphene, but only electrons display efficient ballistic transport toward the TiO2 transport layer, thus leading to effective photon-to-electricity conversion. On the basis of this ipsilateral selective electron tunnelling (ISET) mechanism, a model monolayer photovoltaic device (PVD) possessing a TiO2/graphene/acridine orange ternary interface showed ∼86.8% interfacial separation/collection efficiency, which guaranteed an ultrahigh absorbed photon-to-current efficiency (APCE, ∼80%). Such an ISET-based PVD may become a fundamental device architecture for photovoltaic solar cells, photoelectric detectors, and other novel optoelectronic applications with obvious advantages, such as high efficiency, easy fabrication, scalability, and universal availability of cost-effective materials.

Structural basis of DNA bending and oriented heterodimer binding by the basic leucine zipper domains of Fos and Jun.

PubMed

Leonard, D A; Rajaram, N; Kerppola, T K

1997-05-13

Interactions among transcription factors that bind to separate sequence elements require bending of the intervening DNA and juxtaposition of interacting molecular surfaces in an appropriate orientation. Here, we examine the effects of single amino acid substitutions adjacent to the basic regions of Fos and Jun as well as changes in sequences flanking the AP-1 site on DNA bending. Substitution of charged amino acid residues at positions adjacent to the basic DNA-binding domains of Fos and Jun altered DNA bending. The change in DNA bending was directly proportional to the change in net charge for all heterodimeric combinations between these proteins. Fos and Jun induced distinct DNA bends at different binding sites. Exchange of a single base pair outside of the region contacted in the x-ray crystal structure altered DNA bending. Substitution of base pairs flanking the AP-1 site had converse effects on the opposite directions of DNA bending induced by homodimers and heterodimers. These results suggest that Fos and Jun induce DNA bending in part through electrostatic interactions between amino acid residues adjacent to the basic region and base pairs flanking the AP-1 site. DNA bending by Fos and Jun at inverted binding sites indicated that heterodimers bind to the AP-1 site in a preferred orientation. Mutation of a conserved arginine within the basic regions of Fos and transversion of the central C:G base pair in the AP-1 site to G:C had complementary effects on the orientation of heterodimer binding and DNA bending. The conformational variability of the Fos-Jun-AP-1 complex may contribute to its functional versatility at different promoters.

Effects of Breeding Configuration on Maternal and Weanling Behavior in Laboratory Mice.

PubMed

Braden, Gillian C; Rasmussen, Skye; Monette, Sebastien; Tolwani, Ravi J

2017-07-01

Although numerous studies have evaluated the effect of housing density on the wellbeing of laboratory mice, little is known about the effect of breeding configuration on mouse behavior. The 8th edition of the Guide for the Care and Use of Laboratory Animals lists the recommended minimal floor area per animal for a female mouse and her litter as 51 in.2 We sought to determine the effects of pair, trio, and harem breeding configurations on the maternal and weanling behavior of C57BL/6J (B6) and 129S6/SvEvTac (129) mice on the basis of nest scores and performance in pup retrieval tests, open-field test (OFT), elevated plus maze, and tail suspension test; we concurrently evaluated cage microenvironment, reproductive indices, and anatomic and clinical pathology. Harem breeding configurations enhanced B6 maternal behaviors as evidenced by significantly shorter pup retrieval times. Trio- and harem-raised B6 weanlings showed increased exploratory behaviors, as evidenced by greater time spent in the center of the OFT, when compared with pair-raised B6 mice. Conversely, breeding configuration did not alter pup retrieval times for 129 mice, and on the day of weaning trio- and harem-raised 129 mice demonstrated increased anxiety-like behavior, as evidenced by greater time spent in the periphery of the OFT, when compared with pair-raised counterparts. Behavioral differences were not noted on subsequent days for either strain. Trio- and harem-raised B6 and 129 weanling mice had significantly higher weaning weights than weanlings raised in a pair breeding configuration. Trio and harem breeding in a standard 67-in.2 shoebox cage did not detrimentally affect the evaluated welfare parameters in either C57BL/6J or 129S6/SvEvTac mice.

Predation on seabirds by red foxes at Shaiak Island, Alaska

USGS Publications Warehouse

Petersen, M.R.

1982-01-01

Two Red Foxes (Vulpes fulva) that invaded Shaiak Island before the 1976 nesting season had a marked impact on the nesting success of five of seven species of seabirds breeding on the island that year. Common Eiders (Somateria mollissima), Glaucous-winged Gulls (Larus glaucescens), and Common Murres (Uria aalge), that nest in areas accessible to foxes, did not raise any young to fledging. Double-crested Cormorants (Phalacrocorax auritus) were only slightly more successful; 13 (4.3%) of 300 pairs raised one or more young to fledging. Evidence suggested that 21 (35.6%) of 62 pairs of Tufted Puffins (Lunda cirrhata) lost eggs or chicks to foxes, and foxes killed at least 13 (8.3%) of 156 adult puffins on ten sample plots. Conversely, Black-Legged Kittiwakes (Rissa tridactyla) and Pelagic Cormorants (Phalacrocorax pelagicus), which nested primarily on cliffs inaccessible to foxes, lost very few nests. There was no apparent change in general nest site selections by seabirds the following year, when foxes were no longer present. Any avoidance by birds of areas vulnerable to fox predation would probably be discernible only after several years of continuous predation.

Thermoluminescence measurements of neutron dose around a medical linac.

PubMed

Barquero, R; Méndez, R; Iñiguez, M P; Vega, H R; Voytchev, M

2002-01-01

The photoncutron ambient dose around a 18 MV medical electron lineal accelerator has been measured with LiF:Mg,Ti chips of 3 x 3 x 1 mm inside moderating spheres. During the measurements a water phantom was irradiated in a field of 40 x 40 cm2. Two methods have been considered for comparison. In the first, a TLD-600/TLD-700 pair at the centre of a 25 cm diameter paraffine sphere was used, with the system behaving as a rem meter. In the second method, TLD-600/TLD-700 pairs, bare and at the centre of 7.6, 12.7, 20.3, 25.4, and 30.5 cm diameter polyethylene Bonner spheres were used to obtain the neutron spectrum. This was unfolded using the BUNKIUT code with the SPUNIT algorithm and the UTA4 and ARKI response functions. The neutron dose was followed by multiplying the unfolded neutron spectrum by the ambient dose equivalent to neutron fluence conversion factors. Both methods result in 0.5 mSv x Gy(-1) m away from the isocentre.

Vibronically coherent ultrafast triplet-pair formation and subsequent thermally activated dissociation control efficient endothermic singlet fission

NASA Astrophysics Data System (ADS)

Stern, Hannah L.; Cheminal, Alexandre; Yost, Shane R.; Broch, Katharina; Bayliss, Sam L.; Chen, Kai; Tabachnyk, Maxim; Thorley, Karl; Greenham, Neil; Hodgkiss, Justin M.; Anthony, John; Head-Gordon, Martin; Musser, Andrew J.; Rao, Akshay; Friend, Richard H.

2017-12-01

Singlet exciton fission (SF), the conversion of one spin-singlet exciton (S1) into two spin-triplet excitons (T1), could provide a means to overcome the Shockley-Queisser limit in photovoltaics. SF as measured by the decay of S1 has been shown to occur efficiently and independently of temperature, even when the energy of S1 is as much as 200 meV less than that of 2T1. Here we study films of triisopropylsilyltetracene using transient optical spectroscopy and show that the triplet pair state (TT), which has been proposed to mediate singlet fission, forms on ultrafast timescales (in 300 fs) and that its formation is mediated by the strong coupling of electronic and vibrational degrees of freedom. This is followed by a slower loss of singlet character as the excitation evolves to become only TT. We observe the TT to be thermally dissociated on 10-100 ns timescales to form free triplets. This provides a model for 'temperature-independent' efficient TT formation and thermally activated TT separation.

Concerted One-Electron Two-Proton Transfer Processes in Models Inspired by the Tyr-His Couple of Photosystem II

DOE PAGES

Huynh, Mioy T.; Mora, S. Jimena; Villalba, Matias; ...

2017-05-09

Nature employs a TyrZ-His pair as a redox relay that couples proton transfer to the redox process between P680 and the water oxidizing catalyst in photosystem II. Artificial redox relays composed of different benzimidazole–phenol dyads (benzimidazole models His and phenol models Tyr) with substituents designed to simulate the hydrogen bond network surrounding the TyrZ-His pair have been prepared. Furthermore, when the benzimidazole substituents are strong proton acceptors such as primary or tertiary amines, theory predicts that a concerted two proton transfer process associated with the electrochemical oxidation of the phenol will take place. Furthermore, theory predicts a decrease in themore » redox potential of the phenol by ~300 mV and a small kinetic isotope effect (KIE). Indeed, electrochemical, spectroelectrochemical, and KIE experimental data are consistent with these predictions. Our results were obtained by using theory to guide the rational design of artificial systems and have implications for managing proton activity to optimize efficiency at energy conversion sites involving water oxidation and reduction.« less

Pseudo-random generator based on Chinese Remainder Theorem

NASA Astrophysics Data System (ADS)

Bajard, Jean Claude; Hördegen, Heinrich

2009-08-01

Pseudo-Random Generators (PRG) are fundamental in cryptography. Their use occurs at different level in cipher protocols. They need to verify some properties for being qualified as robust. The NIST proposes some criteria and a tests suite which gives informations on the behavior of the PRG. In this work, we present a PRG constructed from the conversion between further residue systems of representation of the elements of GF(2)[X]. In this approach, we use some pairs of co-prime polynomials of degree k and a state vector of 2k bits. The algebraic properties are broken by using different independent pairs during the process. Since this method is reversible, we also can use it as a symmetric crypto-system. We evaluate the cost of a such system, taking into account that some operations are commonly implemented on crypto-processors. We give the results of the different NIST Tests and we explain this choice compare to others found in the literature. We describe the behavior of this PRG and explain how the different rounds are chained for ensuring a fine secure randomness.

Heralding efficiency and correlated-mode coupling of near-IR fiber-coupled photon pairs

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

Dixon, P. Ben; Rosenberg, Danna; Stelmakh, Veronika

We report on a systematic experimental study of heralding efficiency and generation rate of telecom-band infrared photon pairs generated by spontaneous parametric down-conversion and coupled to single mode optical fibers. We define the correlated-mode coupling efficiency--an inherent source efficiency--and explain its relation to heralding efficiency. For our experiment, we developed a reconfigurable computer controlled pump-beam and collection-mode optical apparatus which we used to measure the generation rate and correlated-mode coupling efficiency. The use of low-noise, high-efficiency superconducting-nanowire single-photon-detectors in this setup allowed us to explore focus configurations with low overall photon flux. The measured data agree well with theory andmore » we demonstrated a correlated-mode coupling efficiency of 97%±2%, which is the highest efficiency yet achieved for this type of system. These results confirm theoretical treatments and demonstrate that very high overall heralding efficiencies can, in principle, be achieved in quantum optical systems. We expect that these results and techniques will be widely incorporated into future systems that require, or benefit from, a high heralding efficiency.« less

Study on a discal TEM-TE{sub 11} mode converter loaded high-efficiency magnetically insulated transmission line oscillator

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

Zhang, Xiaoping, E-mail: zhangxiaoping@nudt.edu.cn; Yuan, Chengwei; Li, Yangmei

2015-12-15

An integrative high power microwave device is proposed, which consists of a high-efficiency L-band Magnetically Insulated Transmission Line Oscillator (MILO) and a discal TEM–TE{sub 11} mode converter. The MILO with a shrunken load composed of a step-like cathode and a ladder-like beam collector can generate a 1.58 GHz, 5.7 GW microwave with the efficiency of 20.8% at the diode voltage of 560 kV in simulation. The discal converter utilizes a pair of sectorial two-double radial waveguides and a pair of sectorial cross section waveguides to adjust the phase-difference and realizes the mode conversion in a length of less than halfmore » wavelength at 1.58 GHz. In the preliminary experiment, the proposed device generates over 2 GW, 1.575 GHz microwave with the pulse duration of over 50 ns in a 420 kV diode voltage; the corresponding efficiency is 14.9%; the radiation pattern is the ideal TE{sub 11} mode.« less

Destination memory and familiarity: better memory for conversations with Elvis Presley than with unknown people.

PubMed

El Haj, Mohamad; Omigie, Diana; Samson, Séverine

2015-06-01

Familiarity is assumed to exert a beneficial effect on memory in older adults. Our paper investigated this issue specifically for destination memory, that is, memory of the destination of previously relayed information. Young and older adults were told familiar (Experiment 1) and unfamiliar (Experiment 2) proverbs associated with pictures depicting faces of celebrities (e.g., Elvis Presley) or unknown people, with a specific proverb assigned to each face. In a later recognition task, participants were presented with the previously exposed proverb-face pairs and for each pair had to decide whether they had previously relayed the given proverb to the given face. In general, destination performance was found to be higher for familiar than for unfamiliar faces. However while there was no difference between the two groups when the proverbs being relayed were unfamiliar, the advantage of face familiarity on destination memory was present only for older adults when the proverbs being relayed were familiar. Our results show that destination memory in older adults is sensitive to familiarity of both destination and output information.

Children's discrimination of vowel sequences

NASA Astrophysics Data System (ADS)

Coady, Jeffry A.; Kluender, Keith R.; Evans, Julia

2003-10-01

Children's ability to discriminate sequences of steady-state vowels was investigated. Vowels (as in ``beet,'' ``bat,'' ``bought,'' and ``boot'') were synthesized at durations of 40, 80, 160, 320, 640, and 1280 ms. Four different vowel sequences were created by concatenating different orders of vowels for each duration, separated by 10-ms intervening silence. Thus, sequences differed in vowel order and duration (rate). Sequences were 12 s in duration, with amplitude ramped linearly over the first and last 2 s. Sequence pairs included both same (identical sequences) and different trials (sequences with vowels in different orders). Sequences with vowel of equal duration were presented on individual trials. Children aged 7;0 to 10;6 listened to pairs of sequences (with 100 ms between sequences) and responded whether sequences sounded the same or different. Results indicate that children are best able to discriminate sequences of intermediate-duration vowels, typical of conversational speaking rate. Children were less accurate with both shorter and longer vowels. Results are discussed in terms of auditory processing (shortest vowels) and memory (longest vowels). [Research supported by NIDCD DC-05263, DC-04072, and DC-005650.

Heralding efficiency and correlated-mode coupling of near-IR fiber-coupled photon pairs

DOE PAGES

Dixon, P. Ben; Rosenberg, Danna; Stelmakh, Veronika; ...

2014-10-06

We report on a systematic experimental study of heralding efficiency and generation rate of telecom-band infrared photon pairs generated by spontaneous parametric down-conversion and coupled to single mode optical fibers. We define the correlated-mode coupling efficiency--an inherent source efficiency--and explain its relation to heralding efficiency. For our experiment, we developed a reconfigurable computer controlled pump-beam and collection-mode optical apparatus which we used to measure the generation rate and correlated-mode coupling efficiency. The use of low-noise, high-efficiency superconducting-nanowire single-photon-detectors in this setup allowed us to explore focus configurations with low overall photon flux. The measured data agree well with theory andmore » we demonstrated a correlated-mode coupling efficiency of 97%±2%, which is the highest efficiency yet achieved for this type of system. These results confirm theoretical treatments and demonstrate that very high overall heralding efficiencies can, in principle, be achieved in quantum optical systems. We expect that these results and techniques will be widely incorporated into future systems that require, or benefit from, a high heralding efficiency.« less

Unconditional security of time-energy entanglement quantum key distribution using dual-basis interferometry.

PubMed

Zhang, Zheshen; Mower, Jacob; Englund, Dirk; Wong, Franco N C; Shapiro, Jeffrey H

2014-03-28

High-dimensional quantum key distribution (HDQKD) offers the possibility of high secure-key rate with high photon-information efficiency. We consider HDQKD based on the time-energy entanglement produced by spontaneous parametric down-conversion and show that it is secure against collective attacks. Its security rests upon visibility data-obtained from Franson and conjugate-Franson interferometers-that probe photon-pair frequency correlations and arrival-time correlations. From these measurements, an upper bound can be established on the eavesdropper's Holevo information by translating the Gaussian-state security analysis for continuous-variable quantum key distribution so that it applies to our protocol. We show that visibility data from just the Franson interferometer provides a weaker, but nonetheless useful, secure-key rate lower bound. To handle multiple-pair emissions, we incorporate the decoy-state approach into our protocol. Our results show that over a 200-km transmission distance in optical fiber, time-energy entanglement HDQKD could permit a 700-bit/sec secure-key rate and a photon information efficiency of 2 secure-key bits per photon coincidence in the key-generation phase using receivers with a 15% system efficiency.

Time-dependent efficiency measurements of donor-acceptor, dye-sensitized polymer solar cells

NASA Astrophysics Data System (ADS)

Bandaccari, Kyle; Chesmore, Grace; Tajalli-Tehrani Valverde, Parisa; Bugaj, Mitchel; McNelis, Brian; Barber, Richard, Jr.

The fullerene/polymer active layer pairing of PCBM/P3HT has become the model system within the field of polymer solar cell research. A large body of work concerned with reporting improved efficiencies for this system exists, but truly quantitative studies of device lifetime and long-term degradation tendencies are much rarer. Here, we report the effects of two donor-acceptor diazo dye sensitizers on efficiency and lifetime upon addition into the PCBM/P3HT active layer at varied concentrations. The electrical and efficiency measurements were supplemented by time-dependent UV-visible spectroscopy studies and morphology investigations via atomic-force microscopy (AFM). This pairing with spectroscopy offers an internal check on the data as the rate of change in absorbance of the active layer correlates almost exactly to the rate of power conversion efficiency decrease. Additionally, AFM imaging reveals different morphology patterns when dye concentrations and functionalities change. Such observations suggest that such small-molecule sensitizers exert yet undetermined effects on the organization of components within the active layer at the molecular level.

Microdevelopment during an activity-based science lesson

NASA Astrophysics Data System (ADS)

Parziale, Jim

1997-11-01

The purpose of this study was to describe the microdevelopment of task-related skills during a classroom science activity. Pairs of fifth and pairs of seventh grade students were videotaped as they constructed marshmallow and toothpick bridges. A skill theory based system of analysis was developed and used to detect the construction of new understandings. Patterns of change observed in these understandings were used to infer three means of self-construction: shifts of focus, bridging mechanisms and distributed cognition. Shift of focus is a mechanism used by students to efficiently explore a web of possibilities, collect ideas and make observations for later coordination as new understandings. Bridging mechanisms are partially built conversational structures that scaffolded the construction of higher level thinking structures. Students used the distributed cognition mechanism to test the adaptiveness of their design ideas without the need to fully coordinate an understandings of these designs. An integrated model of these three mechanisms is proposed specific to this task. This model describes how these mechanisms spontaneously emerged and interacted to support the construction of mental representations.

Quality versus intelligibility: studying human preferences for American Sign Language video

NASA Astrophysics Data System (ADS)

Ciaramello, Frank M.; Hemami, Sheila S.

2011-03-01

Real-time videoconferencing using cellular devices provides natural communication to the Deaf community. For this application, compressed American Sign Language (ASL) video must be evaluated in terms of the intelligibility of the conversation and not in terms of the overall aesthetic quality of the video. This work presents a paired comparison experiment to determine the subjective preferences of ASL users in terms of the trade-off between intelligibility and quality when varying the proportion of the bitrate allocated explicitly to the regions of the video containing the signer. A rate-distortion optimization technique, which jointly optimizes a quality criteria and an intelligibility criteria according to a user-specified parameter, generates test video pairs for the subjective experiment. Experimental results suggest that at sufficiently high bitrates, all users prefer videos in which the non-signer regions in the video are encoded with some nominal rate. As the total encoding bitrate decreases, users generally prefer video in which a greater proportion of the rate is allocated to the signer. The specific operating points preferred in the quality-intelligibility trade-off vary with the demographics of the users.

Circulating current battery heater

DOEpatents

Ashtiani, Cyrus N.; Stuart, Thomas A.

2001-01-01

A circuit for heating energy storage devices such as batteries is provided. The circuit includes a pair of switches connected in a half-bridge configuration. Unidirectional current conduction devices are connected in parallel with each switch. A series resonant element for storing energy is connected from the energy storage device to the pair of switches. An energy storage device for intermediate storage of energy is connected in a loop with the series resonant element and one of the switches. The energy storage device which is being heated is connected in a loop with the series resonant element and the other switch. Energy from the heated energy storage device is transferred to the switched network and then recirculated back to the battery. The flow of energy through the battery causes internal power dissipation due to electrical to chemical conversion inefficiencies. The dissipated power causes the internal temperature of the battery to increase. Higher internal temperatures expand the cold temperature operating range and energy capacity utilization of the battery. As disclosed, either fixed frequency or variable frequency modulation schemes may be used to control the network.

ERP signs of categorical and supra-categorical processing of visual information.

PubMed

Zani, Alberto; Marsili, Giulia; Senerchia, Annapaola; Orlandi, Andrea; Citron, Francesca M M; Rizzi, Ezia; Proverbio, Alice M

2015-01-01

The aim of the present study was to investigate to what extent shared and distinct brain mechanisms are possibly subserving the processing of visual supra-categorical and categorical knowledge as observed with event-related potentials of the brain. Access time to these knowledge types was also investigated. Picture pairs of animals, objects, and mixed types were presented. Participants were asked to decide whether each pair contained pictures belonging to the same category (either animals or man-made objects) or to different categories by pressing one of two buttons. Response accuracy and reaction times (RTs) were also recorded. Both ERPs and RTs were grand-averaged separately for the same-different supra-categories and the animal-object categories. Behavioral performance was faster for more endomorphic pairs, i.e., animals vs. objects and same vs. different category pairs. For ERPs, a modulation of the earliest C1 and subsequent P1 responses to the same vs. different supra-category pairs, but not to the animal vs. object category pairs, was found. This finding supports the view that early afferent processing in the striate cortex can be boosted as a by-product of attention allocated to the processing of shapes and basic features that are mismatched, but not to their semantic quintessence, during same-different supra-categorical judgment. Most importantly, the fact that this processing accrual occurred independent of a traditional experimental condition requiring selective attention to a stimulus source out of the various sources addressed makes it conceivable that this processing accrual may arise from the attentional demand deriving from the alternate focusing of visual attention within and across stimulus categorical pairs' basic structural features. Additional posterior ERP reflections of the brain more prominently processing animal category and same-category pairs were observed at the N1 and N2 levels, respectively, as well as at a late positive complex level, overall most likely related to different stages of analysis of the greater endomorphy of these shape groups. Conversely, an enhanced fronto-central and fronto-lateral N2 as well as a centro-parietal N400 to man-made objects and different-category pairs were found, possibly indexing processing of these entities' lower endomorphy and isomorphy at the basic features and semantic levels, respectively. Overall, the present ERP results revealed shared and distinct mechanisms of access to supra-categorical and categorical knowledge in the same way in which shared and distinct neural representations underlie the processing of diverse semantic categories. Additionally, they outlined the serial nature of categorical and supra-categorical representations, indicating the sequential steps of access to these separate knowledge types. Copyright © 2014 Elsevier B.V. All rights reserved.

Recent Stirling Conversion Technology Developments and Operational Measurements at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Oriti, Salvatore M.; Schifer, Nicholas A.

2010-01-01

In support of the Advanced Stirling Radioisotope Generator (ASRG) project and other potential applications, NASA Glenn Research Center (GRC) has initiated convertor technology development efforts in the areas of acoustic emission, electromagnetic field mitigation, thermoacoustic Stirling conversion, and multiple-cylinder alpha arrangements of Stirling machines. The acoustic emission measurement effort was developed as a health monitoring metric for several Stirling convertors undergoing life testing. While accelerometers have been used in the past to monitor dynamic signature, the acoustic sensors were chosen to monitor cycle events, such gas bearing operation. Several electromagnetic interference (EMI) experiments were performed on a pair of Advanced Stirling Convertors (ASC). These tests demonstrated that a simple bucking coil was capable of reducing the alternating current (ac) magnetic field below the ASRG system specification. The thermoacoustic Stirling concept eliminates the displacer typically found in Stirling machines by making use of the pressure oscillations of a traveling acoustic wave. A 100 W-class thermoacoustic Stirling prototype manufactured by Northrop Grumman Space and Technology was received and tested. Another thermoacoustic prototype designed and fabricated by Sunpower, Inc., will be tested in the near future. A four cylinder free piston alpha prototype convertor was received from Sunpower, Inc. and has been tested at GRC. This hardware was used as a proof of concept to validate thermodynamic models and demonstrate stable operation of multiple-cylinder free-piston Stirling conversion. This paper will discuss each of these activities and the results they produced.

The neural basis of involuntary episodic memories.

PubMed

Hall, Shana A; Rubin, David C; Miles, Amanda; Davis, Simon W; Wing, Erik A; Cabeza, Roberto; Berntsen, Dorthe

2014-10-01

Voluntary episodic memories require an intentional memory search, whereas involuntary episodic memories come to mind spontaneously without conscious effort. Cognitive neuroscience has largely focused on voluntary memory, leaving the neural mechanisms of involuntary memory largely unknown. We hypothesized that, because the main difference between voluntary and involuntary memory is the controlled retrieval processes required by the former, there would be greater frontal activity for voluntary than involuntary memories. Conversely, we predicted that other components of the episodic retrieval network would be similarly engaged in the two types of memory. During encoding, all participants heard sounds, half paired with pictures of complex scenes and half presented alone. During retrieval, paired and unpaired sounds were presented, panned to the left or to the right. Participants in the involuntary group were instructed to indicate the spatial location of the sound, whereas participants in the voluntary group were asked to additionally recall the pictures that had been paired with the sounds. All participants reported the incidence of their memories in a postscan session. Consistent with our predictions, voluntary memories elicited greater activity in dorsal frontal regions than involuntary memories, whereas other components of the retrieval network, including medial-temporal, ventral occipitotemporal, and ventral parietal regions were similarly engaged by both types of memories. These results clarify the distinct role of dorsal frontal and ventral occipitotemporal regions in predicting strategic retrieval and recalled information, respectively, and suggest that, although there are neural differences in retrieval, involuntary memories share neural components with established voluntary memory systems.

The Neural Basis of Involuntary Episodic Memories

PubMed Central

Hall, Shana A.; Rubin, David C.; Miles, Amanda; Davis, Simon W.; Wing, Erik A.; Cabeza, Roberto; Berntsen, Dorthe

2014-01-01

Voluntary episodic memories require an intentional memory search, whereas involuntary episodic memories come to mind spontaneously without conscious effort. Cognitive neuroscience has largely focused on voluntary memory, leaving the neural mechanisms of involuntary memory largely unknown. We hypothesized that because the main difference between voluntary and involuntary memory is the controlled retrieval processes required by the former, there would be greater frontal activity for voluntary than involuntary memories. Conversely, we predicted that other components of the episodic retrieval network would be similarly engaged in the two types of memory. During encoding, all participants heard sounds, half paired with pictures of complex scenes and half presented alone. During retrieval, paired and unpaired sounds were presented panned to the left or to the right. Participants in the involuntary group were instructed to indicate the spatial location of the sound, whereas participants in the voluntary group were asked to additionally recall the pictures that had been paired with the sounds. All participants reported the incidence of their memories in a post-scan session. Consistent with our predictions, voluntary memories elicited greater activity in dorsal frontal regions than involuntary memories, whereas other components of the retrieval network, including medial temporal, ventral occipitotemporal, and ventral parietal regions were similarly engaged by both types of memories. These results clarify the distinct role of dorsal frontal and ventral occipitotemporal regions in predicting strategic retrieval and recalled information, respectively, and suggest that while there are neural differences in retrieval, involuntary memories share neural components with established voluntary memory systems. PMID:24702453

Structural behavior of Tl-exchanged natrolite at high pressure depending on the composition of pressure-transmitting medium

NASA Astrophysics Data System (ADS)

Seryotkin, Yu. V.; Bakakin, V. V.; Likhacheva, A. Yu.; Dementiev, S. N.; Rashchenko, S. V.

2017-10-01

The structural evolution of Tl-exchanged natrolite with idealized formula Tl2[Al2Si3O10]·2H2O, compressed in penetrating (water:ethanol 1:1) and non-penetrating (paraffin) media, was studied up to 4 GPa. The presence of Tl+ with non-bonded electron lone pairs, which can be either stereo-chemically active or passive, determines distinctive features of the high-pressure behavior of the Tl-form. The effective volume of assemblages Tl+(O,H2O) n depends on the E-pairs activity: single-sided coordination correlates with smaller volumes. At ambient conditions, there are two types of Tl positions, only one of them having a nearly single-sided coordination as a characteristic of stereo-activity of the Tl+ E pair. Upon the compression in paraffin, a phase transition occurs: a 5% volume contraction of flexible natrolite framework is accompanied by the conversion of all the Tl+ cations into stereo-chemically active state with a single-sided coordination. This effect requires the reconstruction of all the extra-framework subsystems with the inversion of the cation and H2O positions. The compression in water-containing medium leads to the increase of H2O content up to three molecules pfu through the filling of partly vacant positions. This hinders a single-sided coordination of Tl ions and preserves the configuration of their ion-molecular subsystem. It is likely that the extra-framework subsystem is responsible for the super-structure modulation.

Multiple ways to the prior occurrence of an event: an electrophysiological dissociation of experimental and conceptually driven familiarity in recognition memory.

PubMed

Wiegand, Iris; Bader, Regine; Mecklinger, Axel

2010-11-11

Recent research has shown that familiarity contributes to associative memory when the to-be-associated stimuli are unitized during encoding. However, the specific processes underlying familiarity-based recognition of unitized representations are still indefinite. In this study, we present electrophysiologically dissociable early old/new effects, presumably related to two different kinds of familiarity inherent in associative recognition tasks. In a study-test associative recognition memory paradigm, we employed encoding conditions that established unitized representations of two pre-experimentally unrelated words, e.g. vegetable-bible. We compared event-related potentials (ERP) during the retrieval of these unitized word pairs using different retrieval cues. Word pairs presented in the same order as during unitization at encoding elicited a parietally distributed early old/new effect which we interpret as reflecting conceptually driven familiarity for newly formed concepts. Conversely, word pairs presented in reversed order only elicited a topographically dissociable early effect, i.e. the mid-frontal old/new effect, the putative correlate of experimental familiarity. The late parietal old/new effect, the putative ERP correlate of recollection, was obtained irrespective of word order, though it was larger for words presented in same order. These results indicate that familiarity may not be a unitary process and that different task demands can promote the assessment of conceptually driven familiarity for novel unitized concepts or experimentally-induced increments of experimental familiarity, respectively. Copyright © 2010 Elsevier B.V. All rights reserved.

Mid-infrared coincidence measurements based on intracavity frequency conversion

NASA Astrophysics Data System (ADS)

Piccione, S.; Mancinelli, M.; Trenti, A.; Fontana, G.; Dam, J.; Tidemand-Lichtenberg, P.; Pedersen, C.; Pavesi, L.

2018-02-01

In the last years, the Mid Infrared (MIR) spectral region has attracted the attention of many areas of science and technology, opening the way to important applications, such as molecular imaging, remote sensing, free- space communication and environmental monitoring. However, the development of new sources of light, such as quantum cascade laser, was not followed by an adequate improvement in the MIR detection system, able to exceed the current challenges. Here we demonstrate the single-photon counting capability of a new detection system, based on efficient up-converter modules, by proving the correlated nature of twin photons pairs at about 3.1μm, opening the way to the extension of quantum optics experiments in the MIR.

Formation of definite GaN p-n junction by Mg-ion implantation to n--GaN epitaxial layers grown on a high-quality free-standing GaN substrate

NASA Astrophysics Data System (ADS)

Oikawa, Takuya; Saijo, Yusuke; Kato, Shigeki; Mishima, Tomoyoshi; Nakamura, Tohru

2015-12-01

P-type conversion of n--GaN by Mg-ion implantation was successfully performed using high quality GaN epitaxial layers grown on free-standing low-dislocation-density GaN substrates. These samples showed low-temperature PL spectra quite similar to those observed from Mg-doped MOVPE-grown p-type GaN, consisting of Mg related donor-acceptor pair (DAP) and acceptor bound exciton (ABE) emission. P-n diodes fabricated by the Mg-ion implantation showed clear rectifying I-V characteristics and UV and blue light emissions were observed at forward biased conditions for the first time.

Widely tunable single photon source with high purity at telecom wavelength.

PubMed

Jin, Rui-Bo; Shimizu, Ryosuke; Wakui, Kentaro; Benichi, Hugo; Sasaki, Masahide

2013-05-06

We theoretically and experimentally investigate the spectral tunability and purity of photon pairs generated from spontaneous parametric down conversion in periodically poled KTiOPO(4) crystal with group-velocity matching condition. The numerical simulation predicts that the spectral purity can be kept higher than 0.81 when the wavelength is tuned from 1460 nm to 1675 nm, which covers the S-, C-, L-, and U-band in telecommunication wavelengths. We also experimentally measured the joint spectral intensity at 1565 nm, 1584 nm and 1565 nm, yielding Schmidt numbers of 1.01, 1.02 and 1.04, respectively. Such a photon source is useful for quantum information and communication systems.

Long-distance practical quantum key distribution by entanglement swapping.

PubMed

Scherer, Artur; Sanders, Barry C; Tittel, Wolfgang

2011-02-14

We develop a model for practical, entanglement-based long-distance quantum key distribution employing entanglement swapping as a key building block. Relying only on existing off-the-shelf technology, we show how to optimize resources so as to maximize secret key distribution rates. The tools comprise lossy transmission links, such as telecom optical fibers or free space, parametric down-conversion sources of entangled photon pairs, and threshold detectors that are inefficient and have dark counts. Our analysis provides the optimal trade-off between detector efficiency and dark counts, which are usually competing, as well as the optimal source brightness that maximizes the secret key rate for specified distances (i.e. loss) between sender and receiver.

Pre-chirp managed nonlinear amplification in fibers delivering 100  W, 60  fs pulses.

PubMed

Liu, Wei; Schimpf, Damian N; Eidam, Tino; Limpert, Jens; Tünnermann, Andreas; Kärtner, Franz X; Chang, Guoqing

2015-01-15

We demonstrate a pre-chirp managed Yb-doped fiber laser system that outputs 75 MHz, 130 W spectrally broadened pulses, which are compressed by a diffraction-grating pair to 60 fs with average powers as high as 100 W. Fine tuning the pulse chirp prior to amplification leads to high-quality compressed pulses. Detailed experiments and numerical simulation reveal that the optimum pre-chirp group-delay dispersion increases from negative to positive with increasing output power for rod-type high-power fiber amplifiers. The resulting laser parameters are suitable for extreme nonlinear optics applications such as frequency conversion in femtosecond enhancement cavities.

Engineered Quasi-Phase Matching for Nonlinear Quantum Optics in Waveguides

NASA Astrophysics Data System (ADS)

Van Camp, Mackenzie A.

Entanglement is the hallmark of quantum mechanics. Quantum entanglement--putting two or more identical particles into a non-factorable state--has been leveraged for applications ranging from quantum computation and encryption to high-precision metrology. Entanglement is a practical engineering resource and a tool for sidestepping certain limitations of classical measurement and communication. Engineered nonlinear optical waveguides are an enabling technology for generating entangled photon pairs and manipulating the state of single photons. This dissertation reports on: i) frequency conversion of single photons from the mid-infrared to 843nm as a tool for incorporating quantum memories in quantum networks, ii) the design, fabrication, and test of a prototype broadband source of polarization and frequency entangled photons; and iii) a roadmap for further investigations of this source, including applications in quantum interferometry and high-precision optical metrology. The devices presented herein are quasi-phase-matched lithium niobate waveguides. Lithium niobate is a second-order nonlinear optical material and can mediate optical energy conversion to different wavelengths. This nonlinear effect is the basis of both quantum frequency conversion and entangled photon generation, and is enhanced by i) confining light in waveguides to increase conversion efficiency, and ii) quasi-phase matching, a technique for engineering the second-order nonlinear response by locally altering the direction of a material's polarization vector. Waveguides are formed by diffusing titanium into a lithium niobate wafer. Quasi-phase matching is achieved by electric field poling, with multiple stages of process development and optimization to fabricate the delicate structures necessary for broadband entangled photon generation. The results presented herein update and optimize past fabrication techniques, demonstrate novel optical devices, and propose future avenues for device development. Quantum frequency conversion from 1848nm to 843nm is demonstrated for the first time, with >75% single-photon conversion efficiency. A new electric field poling methodology is presented, combining elements from multiple historical techniques with a new fast-feedback control system. This poling technique is used to fabricate the first chirped-and-apodized Type-II quasi-phase-matched structures in titanium-diffused lithium niobate waveguides, culminating in a measured phasematching spectrum that is predominantly Gaussian ( R2 = 0.80), nearly eight times broader than the unchirped spectrum, and agrees well with simulations.

Selective methane chlorination to methyl chloride by zeolite Y-based catalysts

NASA Astrophysics Data System (ADS)

Joo, Hyeonho; Kim, Daeho; Lim, Kwang Soo; Choi, Yong Nam; Na, Kyungsu

2018-03-01

The CH4 chlorination over Y zeolites was investigated to produce CH3Cl in a high yield. Three different catalytic systems based on Y zeolite were tested for enhancement of CH4 conversion and CH3Cl selectivity: (i) HY zeolites in H+-form having various Si/Al ratios, (ii) Pt/HY zeolites supporting Pt metal nanoparticles, (iii) Pt/NaY zeolites in Na+-form supporting Pt metal nanoparticles. The reaction was carried out using the gas mixture of CH4 and Cl2 with the respective flow rates of 15 and 10 mL min-1 at 300-350 °C using a fixed-bed reactor under a continuous gas flow condition (gas hourly space velocity = 3000 mL g-1 h-1). Above the reaction temperature of 300 °C, the CH4 chlorination is spontaneous even in the absence of catalyst, achieving 23.6% of CH4 conversion with 73.4% of CH3Cl selectivity. Under sufficient supplement of thermal energy, Cl2 molecules can be dissociated to two chlorine radicals, which triggered the C-H bond activation of CH4 molecule and thereby various chlorinated methane products (i.e., CH3Cl, CH2Cl2, CHCl3, CCl4) could be produced. When the catalysts were used under the same reaction condition, enhancement in the CH4 conversion was observed. The Pt-free HY zeolite series with varied Si/Al ratios gave around 27% of CH4 conversion, but there was a slight decrease in CH3Cl selectivity with about 64%. Despite the difference in acidity of HY zeolites having different Si/Al ratios, no prominent effect of the Si/Al ratios on the catalytic performance was observed. This suggests that the catalytic contribution of HY zeolites under the present reaction condition is not strong enough to overcome the spontaneous CH4 chlorination. When the Pt/HY zeolite catalysts were used, the CH4 conversion reached further up to 30% but the CH3Cl selectivity decreased to 60%. Such an enhancement of CH4 conversion could be attributed to the strong catalytic activity of HY and Pt/HY zeolite catalysts. However, both catalysts induced the radical cleavage of Cl2 more favorably, which ultimately decreased the CH3Cl selectivity. Such trade-off relationship between CH4 conversion and CH3Cl selectivity can be slightly broken by using Pt/NaY zeolite catalyst that is known to possess Frustrated Lewis Pairs (FLP) that are very useful for ionic cleavage of H2 to H+ and H-. Similarly, in the present work, Pt/NaY(FLP) catalysts enhanced the CH4 conversion while keeping the CH3Cl selectivity as compared to the Pt/HY zeolite catalysts.

Optogenetic Central Amygdala Stimulation Intensifies and Narrows Motivation for Cocaine.

PubMed

Warlow, Shelley M; Robinson, Mike J F; Berridge, Kent C

2017-08-30

Addiction is often characterized by intense motivation for a drug, which may be narrowly focused at the expense of other rewards. Here, we examined the role of amygdala-related circuitry in the amplification and narrowing of motivation focus for intravenous cocaine. We paired optogenetic channelrhodopsin (ChR2) stimulation in either central nucleus of amygdala (CeA) or basolateral amygdala (BLA) of female rats with one particular nose-poke porthole option for earning cocaine infusions (0.3 mg/kg, i.v.). A second alternative porthole earned identical cocaine but without ChR2 stimulation. Consequently, CeA rats quickly came to pursue their CeA ChR2-paired cocaine option intensely and exclusively, elevating cocaine intake while ignoring their alternative cocaine alone option. By comparison, BLA ChR2 pairing failed to enhance cocaine motivation. CeA rats also emitted consummatory bites toward their laser-paired porthole, suggesting that higher incentive salience made that cue more attractive. A separate progressive ratio test of incentive motivation confirmed that CeA ChR2 amplified rats' motivation, raising their breakpoint effort price for cocaine by 10-fold. However, CeA ChR2 laser on its own lacked any reinforcement value: laser by itself was never self-stimulated, not even by the same rats in which it amplified motivation for cocaine. Conversely, CeA inhibition by muscimol/baclofen microinjections prevented acquisition of cocaine self-administration and laser preference, whereas CeA inhibition by optogenetic halorhodopsin suppressed cocaine intake, indicating that CeA circuitry is needed for ordinary cocaine motivation. We conclude that CeA ChR2 excitation paired with a cocaine option specifically focuses and amplifies motivation to produce intense pursuit and consumption focused on that single target. SIGNIFICANCE STATEMENT In addiction, intense incentive motivation often becomes narrowly focused on a particular drug of abuse. Here we show that pairing central nucleus of amygdala (CeA) optogenetic stimulation with one option for earning intravenous cocaine makes that option almost the exclusive focus of intense pursuit and consumption. CeA stimulation also elevated the effort cost rats were willing to pay for cocaine and made associated cues become intensely attractive. However, we also show that CeA laser had no reinforcing properties at all when given alone for the same rats. Therefore, CeA laser pairing makes its associated cocaine option and cues become powerfully attractive in a nearly addictive fashion. Copyright © 2017 the authors 0270-6474/17/378330-19$15.00/0.

Optogenetic Central Amygdala Stimulation Intensifies and Narrows Motivation for Cocaine

PubMed Central

2017-01-01

Addiction is often characterized by intense motivation for a drug, which may be narrowly focused at the expense of other rewards. Here, we examined the role of amygdala-related circuitry in the amplification and narrowing of motivation focus for intravenous cocaine. We paired optogenetic channelrhodopsin (ChR2) stimulation in either central nucleus of amygdala (CeA) or basolateral amygdala (BLA) of female rats with one particular nose-poke porthole option for earning cocaine infusions (0.3 mg/kg, i.v.). A second alternative porthole earned identical cocaine but without ChR2 stimulation. Consequently, CeA rats quickly came to pursue their CeA ChR2-paired cocaine option intensely and exclusively, elevating cocaine intake while ignoring their alternative cocaine alone option. By comparison, BLA ChR2 pairing failed to enhance cocaine motivation. CeA rats also emitted consummatory bites toward their laser-paired porthole, suggesting that higher incentive salience made that cue more attractive. A separate progressive ratio test of incentive motivation confirmed that CeA ChR2 amplified rats' motivation, raising their breakpoint effort price for cocaine by 10-fold. However, CeA ChR2 laser on its own lacked any reinforcement value: laser by itself was never self-stimulated, not even by the same rats in which it amplified motivation for cocaine. Conversely, CeA inhibition by muscimol/baclofen microinjections prevented acquisition of cocaine self-administration and laser preference, whereas CeA inhibition by optogenetic halorhodopsin suppressed cocaine intake, indicating that CeA circuitry is needed for ordinary cocaine motivation. We conclude that CeA ChR2 excitation paired with a cocaine option specifically focuses and amplifies motivation to produce intense pursuit and consumption focused on that single target. SIGNIFICANCE STATEMENT In addiction, intense incentive motivation often becomes narrowly focused on a particular drug of abuse. Here we show that pairing central nucleus of amygdala (CeA) optogenetic stimulation with one option for earning intravenous cocaine makes that option almost the exclusive focus of intense pursuit and consumption. CeA stimulation also elevated the effort cost rats were willing to pay for cocaine and made associated cues become intensely attractive. However, we also show that CeA laser had no reinforcing properties at all when given alone for the same rats. Therefore, CeA laser pairing makes its associated cocaine option and cues become powerfully attractive in a nearly addictive fashion. PMID:28751460

Understanding the differences between genome sequences of Escherichia coli B strains REL606 and BL21(DE3), and comparison of the closely related E. coli B and K-12 genomes

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

Studier, F.W.; Daegelen, P.; Lenski, R. E.

2009-12-01

Each difference between the genome sequences of Escherichia coli B strains REL606 and BL21(DE3) can be interpreted in light of known laboratory manipulations plus a gene conversion between ribosomal RNA operons. Two treatments with 1-methyl-3-nitro-1-nitrosoguanidine in the REL606 lineage produced at least 93 single-base-pair mutations ({approx} 90% GC-to-AT transitions) and 3 single-base-pair GC deletions. Two UV treatments in the BL21(DE3) lineage produced only 4 single-base-pair mutations but 16 large deletions. P1 transductions from K-12 into the two B lineages produced 317 single-base-pair differences and 9 insertions or deletions, reflecting differences between B DNA in BL21(DE3) and integrated restriction fragments ofmore » K-12 DNA inherited by REL606. Two sites showed selective enrichment of spontaneous mutations. No unselected spontaneous single-base-pair mutations were evident. The genome sequences revealed that a progenitor of REL606 had been misidentified, explaining initially perplexing differences. Limited sequencing of other B strains defined characteristic properties of B and allowed assembly of the inferred genome of the ancestral B of Delbrueck and Luria. Comparison of the B and K-12 genomes shows that more than half of the 3793 proteins of their basic genomes are predicted to be identical, although {approx} 310 appear to be functional in either B or K-12 but not in both. The ancestral basic genome appears to have had {approx} 4039 coding sequences occupying {approx} 4.0 Mbp. Repeated horizontal transfer from diverged Escherichia coli genomes and homologous recombination may explain the observed variable distribution of single-base-pair differences. Fifteen sites are occupied by phage-related elements, but only six by comparable elements at the same site. More than 50 sites are occupied by IS elements in both B and K, 16 in common, and likely founding IS elements are identified. A signature of widespread cryptic phage P4-type mobile elements was identified. Complex deletions (dense clusters of small deletions and substitutions) apparently removed nonessential genes from {approx} 30 sites in the basic genomes.« less

SU-E-J-122: The CBCT Dose Calculation Using a Patient Specific CBCT Number to Mass Density Conversion Curve Based On a Novel Image Registration and Organ Mapping Method in Head-And-Neck Radiation Therapy

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

Zhou, J; Lasio, G; Chen, S

2015-06-15

Purpose: To develop a CBCT HU correction method using a patient specific HU to mass density conversion curve based on a novel image registration and organ mapping method for head-and-neck radiation therapy. Methods: There are three steps to generate a patient specific CBCT HU to mass density conversion curve. First, we developed a novel robust image registration method based on sparseness analysis to register the planning CT (PCT) and the CBCT. Second, a novel organ mapping method was developed to transfer the organs at risk (OAR) contours from the PCT to the CBCT and corresponding mean HU values of eachmore » OAR were measured in both the PCT and CBCT volumes. Third, a set of PCT and CBCT HU to mass density conversion curves were created based on the mean HU values of OARs and the corresponding mass density of the OAR in the PCT. Then, we compared our proposed conversion curve with the traditional Catphan phantom based CBCT HU to mass density calibration curve. Both curves were input into the treatment planning system (TPS) for dose calculation. Last, the PTV and OAR doses, DVH and dose distributions of CBCT plans are compared to the original treatment plan. Results: One head-and-neck cases which contained a pair of PCT and CBCT was used. The dose differences between the PCT and CBCT plans using the proposed method are −1.33% for the mean PTV, 0.06% for PTV D95%, and −0.56% for the left neck. The dose differences between plans of PCT and CBCT corrected using the CATPhan based method are −4.39% for mean PTV, 4.07% for PTV D95%, and −2.01% for the left neck. Conclusion: The proposed CBCT HU correction method achieves better agreement with the original treatment plan compared to the traditional CATPhan based calibration method.« less

Construction typification as the tool for optimizing the functioning of a robotized manufacturing system

NASA Astrophysics Data System (ADS)

Gwiazda, A.; Banas, W.; Sekala, A.; Foit, K.; Hryniewicz, P.; Kost, G.

2015-11-01

Process of workcell designing is limited by different constructional requirements. They are related to technological parameters of manufactured element, to specifications of purchased elements of a workcell and to technical characteristics of a workcell scene. This shows the complexity of the design-constructional process itself. The results of such approach are individually designed workcell suitable to the specific location and specific production cycle. Changing this parameters one must rebuild the whole configuration of a workcell. Taking into consideration this it is important to elaborate the base of typical elements of a robot kinematic chain that could be used as the tool for building Virtual modelling of kinematic chains of industrial robots requires several preparatory phase. Firstly, it is important to create a database element, which will be models of industrial robot arms. These models could be described as functional primitives that represent elements between components of the kinematic pairs and structural members of industrial robots. A database with following elements is created: the base kinematic pairs, the base robot structural elements, the base of the robot work scenes. The first of these databases includes kinematic pairs being the key component of the manipulator actuator modules. Accordingly, as mentioned previously, it includes the first stage rotary pair of fifth stage. This type of kinematic pairs was chosen due to the fact that it occurs most frequently in the structures of industrial robots. Second base consists of structural robot elements therefore it allows for the conversion of schematic structures of kinematic chains in the structural elements of the arm of industrial robots. It contains, inter alia, the structural elements such as base, stiff members - simple or angular units. They allow converting recorded schematic three-dimensional elements. Last database is a database of scenes. It includes elements of both simple and complex: simple models of technological equipment, conveyors models, models of the obstacles and like that. Using these elements it could be formed various production spaces (robotized workcells), in which it is possible to virtually track the operation of an industrial robot arm modelled in the system.

p-type doping by platinum diffusion in low phosphorus doped silicon

NASA Astrophysics Data System (ADS)

Ventura, L.; Pichaud, B.; Vervisch, W.; Lanois, F.

2003-07-01

In this work we show that the cooling rate following a platinum diffusion strongly influences the electrical conductivity in weakly phosphorus doped silicon. Diffusions were performed at the temperature of 910 °C in the range of 8 32 hours in 0.6, 30, and 60 Ωrm cm phosphorus doped silicon samples. Spreading resistance profile analyses clearly show an n-type to p-type conversion under the surface when samples are cooled slowly. On the other hand, a compensation of the phosphorus donors can only be observed when samples are quenched. One Pt related acceptor deep level at 0.43 eV from the valence band is assumed to be at the origin of the type conversion mechanism. Its concentration increases by lowering the applied cooling rate. A complex formation with fast species such as interstitial Pt atoms or intrinsic point defects is expected. In 0.6 Ωrm cm phosphorus doped silicon, no acceptor deep level in the lower band gap is detected by DLTS measurement. This removes the opportunity of a pairing between phosphorus and platinum and suggests the possibility of a Fermi level controlled complex formation.

Enhanced conversion efficiency in Si solar cells employing photoluminescent down-shifting CdSe/CdS core/shell quantum dots.

PubMed

Lopez-Delgado, R; Zhou, Y; Zazueta-Raynaud, A; Zhao, H; Pelayo, J E; Vomiero, A; Álvarez-Ramos, M E; Rosei, F; Ayon, A

2017-10-26

Silicon solar cells have captured a large portion of the total market of photovoltaic devices mostly due to their relatively high efficiency. However, Silicon exhibits limitations in ultraviolet absorption because high-energy photons are absorbed at the surface of the solar cell, in the heavily doped region, and the photo-generated electron-hole pairs need to diffuse into the junction region, resulting in significant carrier recombination. One of the alternatives to improve the absorption range involves the use of down-shifting nano-structures able to interact with the aforementioned high energy photons. Here, as a proof of concept, we use downshifting CdSe/CdS quantum dots to improve the performance of a silicon solar cell. The incorporation of these nanostructures triggered improvements in the short circuit current density (J sc , from 32.5 to 37.0 mA/cm 2 ). This improvement led to a ∼13% increase in the power conversion efficiency (PCE), from 12.0 to 13.5%. Our results demonstrate that the application of down-shifting materials is a viable strategy to improve the efficiency of Silicon solar cells with mass-compatible techniques that could serve to promote their widespread utilization.

Analysis of the attainable efficiency of a direct-bandgap betavoltaic element

NASA Astrophysics Data System (ADS)

Sachenko, A. V.; Shkrebtii, A. I.; Korkishko, R. M.; Kostylyov, V. P.; Kulish, M. R.; Sokolovskyi, I. O.; Evstigneev, M.

2015-11-01

Conversion of energy of beta-particles into electric energy in a p-n junction based on direct-bandgap semiconductors, such as GaAs, is analyzed considering realistic semiconductor system parameters. An expression for the collection coefficient, Q, of the electron-hole pairs generated by beta-electrons is derived taking into account the existence of the dead layer. We show that the collection coefficient of beta-electrons emitted by a 3H-source to a GaAs p-n junction is close to 1 in a broad range of electron lifetimes in the junction, ranging from 10-9to 10-7 s. For the combination 147Pm/GaAs, Q is relatively large (≥slant 0.4) only for quite long lifetimes (about 10-7 s) and large thicknesses (about 100 μm) of GaAs p-n junctions. For realistic lifetimes of minority carriers and their diffusion coefficients, the open-circuit voltage realized due to the irradiation of a GaAs p-n junction by beta-particles is obtained. The attainable beta-conversion efficiency η in the case of a 3H/GaAs combination is found to exceed that of the 147Pm/GaAs combination.

Electro-optic voltage sensor with beam splitting

DOEpatents

Woods, Gregory K.; Renak, Todd W.; Davidson, James R.; Crawford, Thomas M.

2002-01-01

The invention is a miniature electro-optic voltage sensor system capable of accurate operation at high voltages without use of the dedicated voltage dividing hardware typically found in the prior art. The invention achieves voltage measurement without significant error contributions from neighboring conductors or environmental perturbations. The invention employs a transmitter, a sensor, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor. Within the sensor the beam undergoes the Pockels electro-optic effect. The electro-optic effect produces a modulation of the beam's polarization, which is in turn converted to a pair of independent conversely-amplitude-modulated signals, from which the voltage of the E-field is determined by the signal processor. The use of converse AM signals enables the signal processor to better distinguish signal from noise. The sensor converts the beam by splitting the beam in accordance with the axes of the beam's polarization state (an ellipse) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured.

Dual-band high-efficiency polarization converter using an anisotropic metasurface

NASA Astrophysics Data System (ADS)

Lin, Baoqin; Wang, Buhong; Meng, Wen; Da, Xinyu; Li, Wei; Fang, Yingwu; Zhu, Zihang

2016-05-01

In this work, a dual-band and high-efficiency reflective cross-polarization converter based on an anisotropic metasurface for linearly polarized electromagnetic waves is proposed. Its unit cell is composed of an elliptical disk-ring mounted on grounded dielectric substrate, which is an anisotropic structure with a pair of mutually perpendicular symmetric axes u and v along ± 45 ° directions with respect to y-axis direction. Both the simulation and measured results show that the polarization converter can convert x- or y-polarized incident wave to its cross polarized wave in the two frequency bands (6.99-9.18 GHz, 11.66-20.40 GHz) with the conversion efficiency higher than 90%; moreover, the higher frequency band is an ultra-wide one with a relative bandwidth of 54.5% for multiple plasmon resonances. In addition, we present a detailed analysis for the polarization conversion of the polarization converter, and derive a formula to calculate the cross- and co-polarization reflections at y-polarized incidence according to the phase differences between the two reflected coefficients at u-polarized and v-polarized incidences. The simulated, calculated, and measured results are all in agreement with the entire frequency regions.

Magnetic resonance imaging of (1)H long lived states derived from parahydrogen induced polarization in a clinical system.

PubMed

Graafen, Dirk; Franzoni, María Belén; Schreiber, Laura M; Spiess, Hans W; Münnemann, Kerstin

2016-01-01

Hyperpolarization is a powerful tool to overcome the low sensitivity of nuclear magnetic resonance (NMR). However, applications are limited due to the short lifetime of this non equilibrium spin state caused by relaxation processes. This issue can be addressed by storing hyperpolarization in slowly decaying singlet spin states which was so far mostly demonstrated for non-proton spin pairs, e.g. (13)C-(13)C. Protons hyperpolarized by parahydrogen induced polarization (PHIP) in symmetrical molecules, are very well suited for this strategy because they naturally exhibit a long-lived singlet state. The conversion of the NMR silent singlet spin state to observable magnetization can be achieved by making use of singlet-triplet level anticrossings. In this study, a low-power radiofrequency pulse sequence is used for this purpose, which allows multiple successive singlet-triplet conversions. The generated magnetization is used to record proton images in a clinical magnetic resonance imaging (MRI) system, after 3min waiting time. Our results may open unprecedented opportunities to use the standard MRI nucleus (1)H for e.g. metabolic imaging in the future. Copyright © 2016. Published by Elsevier Inc.

Charging-free electrochemical system for harvesting low-grade thermal energy

PubMed Central

Yang, Yuan; Lee, Seok Woo; Ghasemi, Hadi; Loomis, James; Li, Xiaobo; Kraemer, Daniel; Zheng, Guangyuan; Cui, Yi; Chen, Gang

2014-01-01

Efficient and low-cost systems are needed to harvest the tremendous amount of energy stored in low-grade heat sources (<100 °C). Thermally regenerative electrochemical cycle (TREC) is an attractive approach which uses the temperature dependence of electrochemical cell voltage to construct a thermodynamic cycle for direct heat-to-electricity conversion. By varying temperature, an electrochemical cell is charged at a lower voltage than discharge, converting thermal energy to electricity. Most TREC systems still require external electricity for charging, which complicates system designs and limits their applications. Here, we demonstrate a charging-free TREC consisting of an inexpensive soluble Fe(CN)63−/4− redox pair and solid Prussian blue particles as active materials for the two electrodes. In this system, the spontaneous directions of the full-cell reaction are opposite at low and high temperatures. Therefore, the two electrochemical processes at both low and high temperatures in a cycle are discharge. Heat-to-electricity conversion efficiency of 2.0% can be reached for the TREC operating between 20 and 60 °C. This charging-free TREC system may have potential application for harvesting low-grade heat from the environment, especially in remote areas. PMID:25404325

Measurement of Dielectron Spectra with the Hadron Blind Detector in PHENIX

NASA Astrophysics Data System (ADS)

Sun, Jiayin

2013-04-01

Dielectrons are an important color neutral probe for studying the evolution of the hot dense medium created by heavy ion collisions at RHIC. At low mass region, dielectron spectra consists mainly of direct photons and light vector mesons, and give insight on the earliest stages of the collisions and thus constrain theoretical models on thermalization and chiral symmetry restoration in heavy ion collisions. At intermediate and high mass region, there are significant contributions from charm and bottom. The region was utilized to measure cross sections of open charm and open bottom, as well as quarkonium suppression. The measurement of the dielectron spectra, however, suffers from an unfavorable signal to background ratio. Random combination of electron positron pairs from unrelated sources, mostly Dalitz decay of π0 and external conversion of decay photon to electrons, are the main contributor to the background. The Hadron Blind Detector, a windowless proximity focusing Cerenkov detector, is designed to reduce this background by identifying electron tracks from photon conversions and π0 Dalitz decays. The detector has been installed and operated in PHENIX in 2009 and 2010, where Au+Au and reference p+p data sets were taken. Results from these data sets will be presented.

The general theory of multistage geminate reactions of isolated pairs of reactants. III. Two-stage reversible dissociation in geminate reaction A + A ↔ C ↔ B + B.

PubMed

Kipriyanov, Alexey A; Kipriyanov, Alexander A; Doktorov, Alexander B

2016-04-14

Specific two-stage reversible reaction A + A ↔ C ↔ B + B of the decay of species C reactants by two independent transition channels is considered on the basis of the general theory of multistage reactions of isolated pairs of reactants. It is assumed that at the initial instant of time, the reacting system contains only reactants C. The employed general approach has made it possible to consider, in the general case, the inhomogeneous initial distribution of reactants, and avoid application of model concepts of a reaction system structure (i.e., of the structure of reactants and their molecular mobility). Slowing of multistage reaction kinetics as compared to the kinetics of elementary stages is established and physically interpreted. To test approximations (point approximation) used to develop a universal kinetic law, a widely employed specific model of spherical particles with isotropic reactivity diffusing in solution is applied. With this particular model as an example, ultimate kinetics of chemical conversion of reactants is investigated. The question concerning the depths of chemical transformation at which long-term asymptotes are reached is studied.

Direct Conversion of Wheat Straw into Electricity with a Biomass Flow Fuel Cell Mediated by Two Redox Ion Pairs.

PubMed

Gong, Jian; Liu, Wei; Du, Xu; Liu, Congmin; Zhang, Zhe; Sun, Feifei; Yang, Le; Xu, Dong; Guo, Hua; Deng, Yulin

2017-02-08

In this paper, a biomass flow fuel cell to directly convert wheat straw to electricity at low temperature (80-90 °C) and atmospheric pressure is presented. Two redox ion pairs, Fe 3+ /Fe 2+ and VO 2 + /VO 2+ , acting as redox catalysts and charge carriers, were used in the anode and cathode flow tanks, respectively. The wheat straw was first oxidized by Fe 3+ in the anode tank at approximately 100 °C. The reduced Fe 2+ in the anode was used to construct a fuel cell with VO 2 + in the cathode. The VO 2 + ions were reduced to VO 2+ and regenerated to VO 2 + by oxygen oxidation. The wheat straw flow fuel cell showed a power output of 100 mW cm -2 . Mediated with liquid Fe 3+ carriers, the solid powder of wheat straw could be gradually degraded into low-molecular-weight organic molecules and even oxidized to CO 2 at the anode without using noble-metal catalysts. The overpotential for the electrodes of the flow fuel cell was examined and the energy cost was estimated. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The general theory of multistage geminate reactions of isolated pairs of reactants. III. Two-stage reversible dissociation in geminate reaction A + A↔C↔B + B

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

Kipriyanov, Alexey A.; Kipriyanov, Alexander A.; Doktorov, Alexander B.

2016-04-14

Specific two-stage reversible reaction A + A↔C↔B + B of the decay of species C reactants by two independent transition channels is considered on the basis of the general theory of multistage reactions of isolated pairs of reactants. It is assumed that at the initial instant of time, the reacting system contains only reactants C. The employed general approach has made it possible to consider, in the general case, the inhomogeneous initial distribution of reactants, and avoid application of model concepts of a reaction system structure (i.e., of the structure of reactants and their molecular mobility). Slowing of multistage reactionmore » kinetics as compared to the kinetics of elementary stages is established and physically interpreted. To test approximations (point approximation) used to develop a universal kinetic law, a widely employed specific model of spherical particles with isotropic reactivity diffusing in solution is applied. With this particular model as an example, ultimate kinetics of chemical conversion of reactants is investigated. The question concerning the depths of chemical transformation at which long-term asymptotes are reached is studied.« less

Gamma Ray Large Area Space Telescope (GLAST) Balloon Flight Engineering Model: Overview

NASA Technical Reports Server (NTRS)

Thompson, D. J.; Godfrey, G.; Williams, S. M.; Grove, J. E.; Mizuno, T.; Sadrozinski, H. F.-W.; Kamae, T.; Ampe, J.; Briber, Stuart; Dann, James;

Lattice topology dictates photon statistics.

PubMed

Kondakci, H Esat; Abouraddy, Ayman F; Saleh, Bahaa E A

2017-08-21

Propagation of coherent light through a disordered network is accompanied by randomization and possible conversion into thermal light. Here, we show that network topology plays a decisive role in determining the statistics of the emerging field if the underlying lattice is endowed with chiral symmetry. In such lattices, eigenmode pairs come in skew-symmetric pairs with oppositely signed eigenvalues. By examining one-dimensional arrays of randomly coupled waveguides arranged on linear and ring topologies, we are led to a remarkable prediction: the field circularity and the photon statistics in ring lattices are dictated by its parity while the same quantities are insensitive to the parity of a linear lattice. For a ring lattice, adding or subtracting a single lattice site can switch the photon statistics from super-thermal to sub-thermal, or vice versa. This behavior is understood by examining the real and imaginary fields on a lattice exhibiting chiral symmetry, which form two strands that interleave along the lattice sites. These strands can be fully braided around an even-sited ring lattice thereby producing super-thermal photon statistics, while an odd-sited lattice is incommensurate with such an arrangement and the statistics become sub-thermal.

Analysis of the “naming game” with learning errors in communications

NASA Astrophysics Data System (ADS)

Lou, Yang; Chen, Guanrong

2015-07-01

Naming game simulates the process of naming an objective by a population of agents organized in a certain communication network. By pair-wise iterative interactions, the population reaches consensus asymptotically. We study naming game with communication errors during pair-wise conversations, with error rates in a uniform probability distribution. First, a model of naming game with learning errors in communications (NGLE) is proposed. Then, a strategy for agents to prevent learning errors is suggested. To that end, three typical topologies of communication networks, namely random-graph, small-world and scale-free networks, are employed to investigate the effects of various learning errors. Simulation results on these models show that 1) learning errors slightly affect the convergence speed but distinctively increase the requirement for memory of each agent during lexicon propagation; 2) the maximum number of different words held by the population increases linearly as the error rate increases; 3) without applying any strategy to eliminate learning errors, there is a threshold of the learning errors which impairs the convergence. The new findings may help to better understand the role of learning errors in naming game as well as in human language development from a network science perspective.

Temporal Variability of Upper-level Winds at the Eastern Range, Western Range and Wallops Flight Facility

NASA Technical Reports Server (NTRS)

Decker, Ryan K.; Barbre, Robert E., Jr.

2014-01-01

Space launch vehicle commit-to-launch decisions include an assessment of the upper-level (UL) atmospheric wind environment to assess the vehicle's controllability and structural integrity during ascent. These assessments occur at predetermined times during the launch countdown based on measured wind data obtained prior to the assessment. However, the pre-launch measured winds may not represent the wind environment during the vehicle ascent. Uncertainty in the UL winds over the time period between the assessment and launch can be mitigated by a statistical analysis of wind change over time periods of interest using historical data from the launch range. Without historical data, theoretical wind models must be used, which can result in inaccurate wind placards that misrepresent launch availability. Using an overconservative model could result in overly restrictive vehicle wind placards, thus potentially reducing launch availability. Conversely, using an under-conservative model could result in launching into winds that might damage or destroy the vehicle. A large sample of measured wind profiles best characterizes the wind change environment. These historical databases consist of a certain number of wind pairs, where two wind profile measurements spaced by the time period of interest define a pair.

Tunable surface plasmon instability leading to emission of radiation

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

Gumbs, Godfrey; Donostia International Physics Center; Iurov, Andrii, E-mail: aiurov@chtm.unm.edu

2015-08-07

We propose a new approach for energy conversion from a dc electric field to tunable terahertz emission based on hybrid semiconductors by combining two-dimensional (2D) crystalline layers and a thick conducting material with possible applications for chemical analysis, security scanning, medical (single-molecule) imaging, and telecommunications. The hybrid nano-structure may consist of a single or pair of sheets of graphene, silicene, or a 2D electron gas. When an electric current is passed through a 2D layer, we discover that two low-energy plasmon branches exhibit a characteristic loop in their dispersion before they merge into an unstable region beyond a critical wavemore » vector q{sub c}. This finite q{sub c} gives rise to a wavenumber cutoff in the emission dispersion of the surface plasmon induced instability and emission of radiation (spiler). However, there is no instability for a single driven layer far from the conductor, and the instability of an isolated pair of 2D layers occurs without a wavenumber cutoff. The wavenumber cutoff is found to depend on the conductor electron density, layer separation, distances of layers from the conductor surface, and the driving-current strength.« less

An appetitive conditioned stimulus enhances fear acquisition and impairs fear extinction

PubMed Central

Leung, Hiu T.; Holmes, Nathan M.

2016-01-01

Four experiments used between- and within-subject designs to examine appetitive–aversive interactions in rats. Experiments 1 and 2 examined the effect of an excitatory appetitive conditioned stimulus (CS) on acquisition and extinction of conditioned fear. In Experiment 1, a CS shocked in a compound with an appetitive excitor (i.e., a stimulus previously paired with sucrose) underwent greater fear conditioning than a CS shocked in a compound with a neutral stimulus. Conversely, in Experiment 2, a CS extinguished in a compound with an appetitive excitor underwent less extinction than a CS extinguished in a compound with a neutral stimulus. Experiments 3 and 4 compared the amount of fear conditioning to an appetitive excitor and a familiar but neutral target CS when the compound of these stimuli was paired with shock. In each experiment, more fear accrued to the appetitive excitor than to the neutral CS. These results show that an appetitive excitor influences acquisition and extinction of conditioned fear to a neutral CS and itself undergoes a greater associative change than the neutral CS across compound conditioning. They are discussed with respect to the role of motivational information in regulating an associative change in appetitive–aversive interactions. PMID:26884229

Test Results From a Pair of 1-kWe Dual-Opposed Free-Piston Stirling Power Convertors Integrated With a Pumped NaK Loop

NASA Technical Reports Server (NTRS)

Geng, Steven M.; Briggs, Maxwell H.; Penswick, L. Barry; Pearson, J. Boise; Godfroy, Thomas J.

2011-01-01

As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1-kW-class free-piston Stirling convertors were modified to operate with a NaK (sodium (Na) and potassium (K)) liquid metal pumped loop for thermal energy input. This was the first-ever attempt at powering a free-piston Stirling engine with a pumped liquid metal heat source and is a major FSP project milestone towards demonstrating technical feasibility. The convertors were successfully tested at the Marshall Space Flight Center (MSFC) from June 6 through July 14, 2009. The convertors were operated for a total test time of 66 hr and 16 min. The tests included (a) performance mapping the convertors over various hot- and cold-end temperatures, piston amplitudes, and NaK flow rates and (b) transient test conditions to simulate various startup (i.e., low-, medium-, and high-temperature startups) and fault scenarios (i.e., loss of heat source, loss of NaK pump, convertor stall, etc.). This report documents the results of this testing

Analysis of the "naming game" with learning errors in communications.

PubMed

Lou, Yang; Chen, Guanrong

2015-07-16

Naming game simulates the process of naming an objective by a population of agents organized in a certain communication network. By pair-wise iterative interactions, the population reaches consensus asymptotically. We study naming game with communication errors during pair-wise conversations, with error rates in a uniform probability distribution. First, a model of naming game with learning errors in communications (NGLE) is proposed. Then, a strategy for agents to prevent learning errors is suggested. To that end, three typical topologies of communication networks, namely random-graph, small-world and scale-free networks, are employed to investigate the effects of various learning errors. Simulation results on these models show that 1) learning errors slightly affect the convergence speed but distinctively increase the requirement for memory of each agent during lexicon propagation; 2) the maximum number of different words held by the population increases linearly as the error rate increases; 3) without applying any strategy to eliminate learning errors, there is a threshold of the learning errors which impairs the convergence. The new findings may help to better understand the role of learning errors in naming game as well as in human language development from a network science perspective.

Timing of gazes in child dialogues: a time-course analysis of requests and back channelling in referential communication.

PubMed

Sandgren, Olof; Andersson, Richard; van de Weijer, Joost; Hansson, Kristina; Sahlén, Birgitta

2012-01-01

This study investigates gaze behaviour in child dialogues. In earlier studies the authors have investigated the use of requests for clarification and responses in order to study the co-creation of understanding in a referential communication task. By adding eye tracking, this line of research is now expanded to include non-verbal contributions in conversation. To investigate the timing of gazes in face-to-face interaction and to relate the gaze behaviour to the use of requests for clarification. Eight conversational pairs of typically developing 10-15 year olds participated. The pairs (director and executor) performed a referential communication task requiring the description of faces. During the dialogues both participants wore head-mounted eye trackers. All gazes were recorded and categorized according to the area fixated (Task, Face, Off). The verbal context for all instances of gaze at the partner's face was identified and categorized using time-course analysis. The results showed that the executor spends almost 90% of the time fixating the gaze on the task, 10% on the director's face and less than 0.5% elsewhere. Turn shift, primarily requests for clarification, and back channelling significantly predicted the executors' gaze to the face of the task director. The distribution of types of requests showed that requests for previously unmentioned information were significantly more likely to be associated with gaze at the director. The study shows that the executors' gaze at the director accompanies important dynamic shifts in the dialogue. The association with requests for clarification indicates that gaze at the director can be used to monitor the response with two modalities. Furthermore, the significantly higher association with requests for previously unmentioned information indicates that gaze may be used to emphasize the verbal content. The results will be used as a reference for studies of gaze behaviour in clinical populations with hearing and language impairments. © 2012 Royal College of Speech and Language Therapists.

Distinct properties of the triplet pair state from singlet fission

DOE PAGES

Trinh, M. Tuan; Pinkard, Andrew; Pun, Andrew B.; ...

2017-07-14

Singlet fission, the conversion of a singlet exciton (S 1) to two triplets (2 × T 1), may increase the solar energy conversion efficiency beyond the Shockley-Queisser limit. This process is believed to involve the correlated triplet pair state 1(TT). Despite extensive research, the nature of the 1(TT) state and its spectroscopic signature remain actively debated. We use an end-connected pentacene dimer (BP0) as a model system and show evidence for a tightly bound 1(TT) state. It is characterized in the near-infrared (IR) region (~1.0 eV) by a distinct excited-state absorption (ESA) spectral feature, which closely resembles that of themore » S 1 state; both show vibronic progressions of the aromatic ring breathing mode. We assign these near-IR spectra to 1(TT)→S n and S 1→S n' transitions; S n and S n' likely come from the antisymmetric and symmetric linear combinations, respectively, of the S 2 state localized on each pentacene unit in the dimer molecule. The 1(TT)→S n transition is an indicator of the intertriplet electronic coupling strength, because inserting a phenylene spacer or twisting the dihedral angle between the two pentacene chromophores decreases the intertriplet electronic coupling and diminishes this ESA peak. In addition to spectroscopic signature, the tightly bound 1(TT) state also shows chemical reactivity that is distinctively different from that of an individual T 1 state. Using an electron-accepting iron oxide molecular cluster [Fe 8O 4] linked to the pentacene or pentacene dimer (BP0), we show that electron transfer to the cluster occurs efficiently from an individual T 1 in pentacene but not from the tightly bound 1(TT) state. Thus, reducing intertriplet electronic coupling in 1(TT) via molecular design might be necessary for the efficient harvesting of triplets from intramolecular singlet fission.« less

Distinct properties of the triplet pair state from singlet fission.

PubMed

Trinh, M Tuan; Pinkard, Andrew; Pun, Andrew B; Sanders, Samuel N; Kumarasamy, Elango; Sfeir, Matthew Y; Campos, Luis M; Roy, Xavier; Zhu, X-Y

2017-07-01

Singlet fission, the conversion of a singlet exciton (S 1 ) to two triplets (2 × T 1 ), may increase the solar energy conversion efficiency beyond the Shockley-Queisser limit. This process is believed to involve the correlated triplet pair state 1 (TT). Despite extensive research, the nature of the 1 (TT) state and its spectroscopic signature remain actively debated. We use an end-connected pentacene dimer (BP0) as a model system and show evidence for a tightly bound 1 (TT) state. It is characterized in the near-infrared (IR) region (~1.0 eV) by a distinct excited-state absorption (ESA) spectral feature, which closely resembles that of the S 1 state; both show vibronic progressions of the aromatic ring breathing mode. We assign these near-IR spectra to 1 (TT)→S n and S 1 →S n' transitions; S n and S n' likely come from the antisymmetric and symmetric linear combinations, respectively, of the S 2 state localized on each pentacene unit in the dimer molecule. The 1 (TT)→S n transition is an indicator of the intertriplet electronic coupling strength, because inserting a phenylene spacer or twisting the dihedral angle between the two pentacene chromophores decreases the intertriplet electronic coupling and diminishes this ESA peak. In addition to spectroscopic signature, the tightly bound 1 (TT) state also shows chemical reactivity that is distinctively different from that of an individual T 1 state. Using an electron-accepting iron oxide molecular cluster [Fe 8 O 4 ] linked to the pentacene or pentacene dimer (BP0), we show that electron transfer to the cluster occurs efficiently from an individual T 1 in pentacene but not from the tightly bound 1 (TT) state. Thus, reducing intertriplet electronic coupling in 1 (TT) via molecular design might be necessary for the efficient harvesting of triplets from intramolecular singlet fission.

Distinct properties of the triplet pair state from singlet fission

PubMed Central

Trinh, M. Tuan; Pinkard, Andrew; Pun, Andrew B.; Sanders, Samuel N.; Kumarasamy, Elango; Sfeir, Matthew Y.; Campos, Luis M.; Roy, Xavier; Zhu, X.-Y.

2017-01-01

Singlet fission, the conversion of a singlet exciton (S1) to two triplets (2 × T1), may increase the solar energy conversion efficiency beyond the Shockley-Queisser limit. This process is believed to involve the correlated triplet pair state 1(TT). Despite extensive research, the nature of the 1(TT) state and its spectroscopic signature remain actively debated. We use an end-connected pentacene dimer (BP0) as a model system and show evidence for a tightly bound 1(TT) state. It is characterized in the near-infrared (IR) region (~1.0 eV) by a distinct excited-state absorption (ESA) spectral feature, which closely resembles that of the S1 state; both show vibronic progressions of the aromatic ring breathing mode. We assign these near-IR spectra to 1(TT)→Sn and S1→Sn′ transitions; Sn and Sn′ likely come from the antisymmetric and symmetric linear combinations, respectively, of the S2 state localized on each pentacene unit in the dimer molecule. The 1(TT)→Sn transition is an indicator of the intertriplet electronic coupling strength, because inserting a phenylene spacer or twisting the dihedral angle between the two pentacene chromophores decreases the intertriplet electronic coupling and diminishes this ESA peak. In addition to spectroscopic signature, the tightly bound 1(TT) state also shows chemical reactivity that is distinctively different from that of an individual T1 state. Using an electron-accepting iron oxide molecular cluster [Fe8O4] linked to the pentacene or pentacene dimer (BP0), we show that electron transfer to the cluster occurs efficiently from an individual T1 in pentacene but not from the tightly bound 1(TT) state. Thus, reducing intertriplet electronic coupling in 1(TT) via molecular design might be necessary for the efficient harvesting of triplets from intramolecular singlet fission. PMID:28740866

Community-based game intervention to improve South Asian Indian Americans' engagement with advanced care planning.

PubMed

Radhakrishnan, Kavita; Van Scoy, Lauren Jodi; Jillapalli, Regina; Saxena, Shubhada; Kim, Miyong T

2017-07-27

Advance care planning (ACP) allows individuals to express their preferences for medical treatment in the event that they become incapable of making their own decisions. This study assessed the efficacy of a conversation game intervention for increasing South Asian Indian Americans' (SAIAs') engagement in ACP behaviors as well as the game's acceptability and cultural appropriateness among SAIAs. Eligible community-dwelling SAIAs were recruited at SAIA cultural events held in central Texas during the summer of 2016. Pregame questionnaires included demographics and the 55-item ACP Engagement Survey. Played in groups of 3-5, the game consists of 17 open-ended questions that prompt discussions of end-of-life issues. After each game session, focus groups and questionnaires were used to examine the game's cultural appropriateness and self-rated conversation quality. Postintervention responses on the ACP Engagement Survey and rates of participation in ACP behaviors were collected after 3 months through phone interviews or online surveys. Data were analyzed using descriptive statistics, frequencies, and paired t-tests comparing pre/post averages at a .05 significance level. Of the 47 participants, 64% were female, 62% had graduate degrees, 92% had lived in the U.S. for >10 years, 87% were first-generation immigrants, and 74% had no advance directive prior to the game. At the 3-month follow-up, 58% of participants had completed at least one ACP behavior, 42% had discussed end-of-life issues with loved ones, 15% did so with their healthcare providers, and 18% had created an advanced directive. ACP Engagement Survey scores increased significantly on all four of the process subscales by 3 months postgame. SAIA individuals who played a conversation game had a relatively high rate of performing ACP behaviors 3 months after the intervention. These findings suggest that conversation games may be useful tools for motivating people from minority communities to engage in ACP behaviors.

Unraveling energy conversion modeling in the intrinsic persistent upconverted luminescence of solids: a study of native point defects in antiferromagnetic Er2O3.

PubMed

Huang, Bolong

2016-05-11

We investigated the mechanism of the intrinsic persistent luminescence of Er2O3 in the A-type lattice based on first-principles calculations. We found that the native point defects were engaged in mutual subtle interactions in the form of chemical reactions between different charge states. The release of energy related to lattice distortion facilitates the conversion of energy for electrons to be transported between the valence band and the trap levels or even between the deep trap levels so as to generate persistent luminescence. The defect transitions that take place along the zero-phonon line release energy to enable optical transitions, with the exact amount of negative effective correlation energy determined by the lattice distortions. Our calculations on the thermodynamic transition levels confirm that both the visible and NIR experimentally observed intrinsic persistent luminescence (phosphor or afterglow) are related to the thermodynamic transition levels of oxygen-related defects, and the thermodynamic transition levels within different charge states for these defects are independent of the chemical potentials of the given species. Lattice distortion defects such as anion Frenkel (a-Fr) pair defects play an important role in transporting O-related defects between different lattice sites. To obtain red persistent luminescence that matches the biological therapeutic window, it is suggested to increase the electron transition levels between high-coordinated O vacancies and related metastable a-Fr defects; a close-packed core-shell structure is required to quench low-coordinated O-related defects so as to reduce the green band luminescence. We further established a conversed chain reaction (CCR) model to interpret the energy conversion process of persistent luminescence in terms of the inter-reactions of native point defects between different charge states. It is advantageous to use the study of defect levels combined with formation energies to suggest limits to doping energy and explain photostimulated luminescence in terms of native point defects.

Methane combustion reactivity during the metal→metallic oxide transformation of Pd-Pt catalysts: Effect of oxygen pressure

NASA Astrophysics Data System (ADS)

Qi, Wenjie; Ran, Jingyu; Zhang, Zhien; Niu, Juntian; Zhang, Peng; Fu, Lijuan; Hu, Bo; Li, Qilai

2018-03-01

Density functional theory combined with kinetic models were used to probe different kinetics consequences by which methane activation on different oxygen chemical potential surfaces as oxygen pressure increased. The metallic oxide → metal transformation temperature of Pd-Pt catalysts increased with the increase of the Pd content or/and O2 pressure. The methane conversion rate on Pt catalyst increased and then decreased to a constant value when increasing the O2 pressure, and Pd catalyst showed a poor activity performance in the case of low O2 pressure. Moreover, its activity increased as the oxygen chemical potential for O2 pressure increased in the range of 2.5-10 KPa. For metal clusters, the Csbnd H bond and Odbnd O bond activation steps occurred predominantly on *-* site pairs. The methane conversion rate was determined by O2 pressure because the adsorbed O atoms were rapidly consumed by other adsorbed species in this kinetic regime. As the O2 pressure increased, the metallic active sites for methane activation were decreased and there was no longer lack of adsorbed O atoms, resulting in the decrease of the methane conversion rate. Furthermore, when the metallic surfaces were completely covered by adsorbed oxygen atoms at higher oxygen chemical potentials, Pt catalyst showed a poor activity due to a high Csbnd H bond activation barrier on O*sbnd O*. In the case of high O2 pressure, Pd atoms preferred to segregate to the active surface of Pd-Pt catalysts, leading to the formation of PdO surfaces. The increase of Pd segregation promoted a subsequent increase in active sites and methane conversion rate. The PdO was much more active than metallic and O* saturated surfaces for methane activation, inferred from the theory and experimental study. Pd-rich bimetallic catalyst (75% molar Pd) showed a dual high methane combustion activity on O2-poor and O2-rich conditions.

Measuring interfraction and intrafraction lung function changes during radiation therapy using four-dimensional cone beam CT ventilation imaging

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

Kipritidis, John, E-mail: john.kipritidis@sydney.edu.au; Keall, Paul J.; Hugo, Geoffrey

Purpose: Adaptive ventilation guided radiation therapy could minimize the irradiation of healthy lung based on repeat lung ventilation imaging (VI) during treatment. However the efficacy of adaptive ventilation guidance requires that interfraction (e.g., week-to-week), ventilation changes are not washed out by intrafraction (e.g., pre- and postfraction) changes, for example, due to patient breathing variability. The authors hypothesize that patients undergoing lung cancer radiation therapy exhibit larger interfraction ventilation changes compared to intrafraction function changes. To test this, the authors perform the first comparison of interfraction and intrafraction lung VI pairs using four-dimensional cone beam CT ventilation imaging (4D-CBCT VI), amore » novel technique for functional lung imaging. Methods: The authors analyzed a total of 215 4D-CBCT scans acquired for 19 locally advanced non-small cell lung cancer (LA-NSCLC) patients over 4–6 weeks of radiation therapy. This set of 215 scans was sorted into 56 interfraction pairs (including first day scans and each of treatment weeks 2, 4, and 6) and 78 intrafraction pairs (including pre/postfraction scans on the same-day), with some scans appearing in both sets. VIs were obtained from the Jacobian determinant of the transform between the 4D-CBCT end-exhale and end-inhale images after deformable image registration. All VIs were deformably registered to their corresponding planning CT and normalized to account for differences in breathing effort, thus facilitating image comparison in terms of (i) voxelwise Spearman correlations, (ii) mean image differences, and (iii) gamma pass rates for all interfraction and intrafraction VI pairs. For the side of the lung ipsilateral to the tumor, we applied two-sided t-tests to determine whether interfraction VI pairs were more different than intrafraction VI pairs. Results: The (mean ± standard deviation) Spearman correlation for interfraction VI pairs was r{sup -}{sub Inter}=0.52±0.25, which was significantly lower than for intrafraction pairs (r{sup -}{sub Intra}=0.67±0.20, p = 0.0002). Conversely, mean absolute ventilation differences were larger for interfraction pairs than for intrafraction pairs, with |ΔV{sup -}{sub Inter}|=0.42±0.65 and |ΔV{sup -}{sub Intra}|=0.32±0.53, respectively (p < 10{sup −15}). Applying a gamma analysis with ventilation/distance tolerance of 25%/10 mm, we observed mean pass rate of (69% ± 20%) for interfraction VIs, which was significantly lower compared to intrafraction pairs (80% ± 15%, with p ∼ 0.0003). Compared to the first day scans, all patients experienced at least one subsequent change in median ipsilateral ventilation ≥10%. Patients experienced both positive and negative ventilation changes throughout treatment, with the maximum change occurring at different weeks for different patients. Conclusions: The authors’ data support the hypothesis that interfraction ventilation changes are larger than intrafraction ventilation changes for LA-NSCLC patients over a course of conventional lung cancer radiation therapy. Longitudinal ventilation changes are observed to be highly patient-dependent, supporting a possible role for adaptive ventilation guidance based on repeat 4D-CBCT VIs. We anticipate that future improvement of 4D-CBCT image reconstruction algorithms will improve the capability of 4D-CBCT VI to resolve interfraction ventilation changes.« less

Measuring interfraction and intrafraction lung function changes during radiation therapy using four-dimensional cone beam CT ventilation imaging.

PubMed

Kipritidis, John; Hugo, Geoffrey; Weiss, Elisabeth; Williamson, Jeffrey; Keall, Paul J

2015-03-01

Adaptive ventilation guided radiation therapy could minimize the irradiation of healthy lung based on repeat lung ventilation imaging (VI) during treatment. However the efficacy of adaptive ventilation guidance requires that interfraction (e.g., week-to-week), ventilation changes are not washed out by intrafraction (e.g., pre- and postfraction) changes, for example, due to patient breathing variability. The authors hypothesize that patients undergoing lung cancer radiation therapy exhibit larger interfraction ventilation changes compared to intrafraction function changes. To test this, the authors perform the first comparison of interfraction and intrafraction lung VI pairs using four-dimensional cone beam CT ventilation imaging (4D-CBCT VI), a novel technique for functional lung imaging. The authors analyzed a total of 215 4D-CBCT scans acquired for 19 locally advanced non-small cell lung cancer (LA-NSCLC) patients over 4-6 weeks of radiation therapy. This set of 215 scans was sorted into 56 interfraction pairs (including first day scans and each of treatment weeks 2, 4, and 6) and 78 intrafraction pairs (including pre/postfraction scans on the same-day), with some scans appearing in both sets. VIs were obtained from the Jacobian determinant of the transform between the 4D-CBCT end-exhale and end-inhale images after deformable image registration. All VIs were deformably registered to their corresponding planning CT and normalized to account for differences in breathing effort, thus facilitating image comparison in terms of (i) voxelwise Spearman correlations, (ii) mean image differences, and (iii) gamma pass rates for all interfraction and intrafraction VI pairs. For the side of the lung ipsilateral to the tumor, we applied two-sided t-tests to determine whether interfraction VI pairs were more different than intrafraction VI pairs. The (mean ± standard deviation) Spearman correlation for interfraction VI pairs was r̄(Inter)=0.52±0.25, which was significantly lower than for intrafraction pairs (r̄(Intra)=0.67±0.20, p = 0.0002). Conversely, mean absolute ventilation differences were larger for interfraction pairs than for intrafraction pairs, with |ΔV̄(Inter)|=0.42±0.65 and |ΔV̄(Intra)|=0.32±0.53, respectively (p < 10(-15)). Applying a gamma analysis with ventilation/distance tolerance of 25%/10 mm, we observed mean pass rate of (69% ± 20%) for interfraction VIs, which was significantly lower compared to intrafraction pairs (80% ± 15%, with p ∼ 0.0003). Compared to the first day scans, all patients experienced at least one subsequent change in median ipsilateral ventilation ≥10%. Patients experienced both positive and negative ventilation changes throughout treatment, with the maximum change occurring at different weeks for different patients. The authors' data support the hypothesis that interfraction ventilation changes are larger than intrafraction ventilation changes for LA-NSCLC patients over a course of conventional lung cancer radiation therapy. Longitudinal ventilation changes are observed to be highly patient-dependent, supporting a possible role for adaptive ventilation guidance based on repeat 4D-CBCT VIs. We anticipate that future improvement of 4D-CBCT image reconstruction algorithms will improve the capability of 4D-CBCT VI to resolve interfraction ventilation changes.

2D to 3D conversion implemented in different hardware

NASA Astrophysics Data System (ADS)

Ramos-Diaz, Eduardo; Gonzalez-Huitron, Victor; Ponomaryov, Volodymyr I.; Hernandez-Fragoso, Araceli

2015-02-01

Conversion of available 2D data for release in 3D content is a hot topic for providers and for success of the 3D applications, in general. It naturally completely relies on virtual view synthesis of a second view given by original 2D video. Disparity map (DM) estimation is a central task in 3D generation but still follows a very difficult problem for rendering novel images precisely. There exist different approaches in DM reconstruction, among them manually and semiautomatic methods that can produce high quality DMs but they demonstrate hard time consuming and are computationally expensive. In this paper, several hardware implementations of designed frameworks for an automatic 3D color video generation based on 2D real video sequence are proposed. The novel framework includes simultaneous processing of stereo pairs using the following blocks: CIE L*a*b* color space conversions, stereo matching via pyramidal scheme, color segmentation by k-means on an a*b* color plane, and adaptive post-filtering, DM estimation using stereo matching between left and right images (or neighboring frames in a video), adaptive post-filtering, and finally, the anaglyph 3D scene generation. Novel technique has been implemented on DSP TMS320DM648, Matlab's Simulink module over a PC with Windows 7, and using graphic card (NVIDIA Quadro K2000) demonstrating that the proposed approach can be applied in real-time processing mode. The time values needed, mean Similarity Structural Index Measure (SSIM) and Bad Matching Pixels (B) values for different hardware implementations (GPU, Single CPU, and DSP) are exposed in this paper.

Informed Consent Conversations and Documents: A Quantitative Comparison

PubMed Central

Koyfman, Shlomo A.; Reddy, Chandana A.; Hizlan, Sabahat; Leek, Angela C.; Kodish, Eric

2015-01-01

Background Informed consent for clinical research includes two components: informed consent documents (ICD) and informed consent conversations (ICC). Readability software has been used to help simplify the language of the ICD, but rarely employed to assess the language during the ICC, which may influence the quality of informed consent. This analysis was completed to determine if length and reading levels of transcribed ICCs are lower than their corresponding ICDs for selected clinical trials, and to assess whether investigator experience affected use of simpler language and comprehensiveness. Methods Prospective study where ICCs were audio-recorded at 6 institutions when families were offered participation in pediatric phase I oncology trials. Word count, Flesch-Kincaid Grade Level (FKGL) and Flesch Reading Ease Score (FRES) of ICCs were compared to corresponding ICDs, including the frequency that investigators addressed 8 pre-specified critical consent elements during the ICC. Results Sixty-nine unique physician/protocol pairs were identified. Overall, ICCs contained fewer words (4,677 vs. 6,364; p=0.0016), had lower FKGL (6 vs. 9.7; p=<0.0001) and higher FRES (77.8 vs. 56.7; p<0.0001) than their respective ICDs, but were more likely to omit critical consent elements, such as voluntariness (55%) and dose limiting toxicities (26%). Years of investigator experience was not correlated with reliably covering critical elements or decreased linguistic complexity. Conclusions Clinicians use more understandable language during ICCs than the corresponding ICD, but less reliably cover elements critical to fully informed consent. Focused efforts at providing communication training for clinician-investigators should be done to optimize the synergy between the ICD and conversation. PMID:26505269

Arbitrary associations in animals: what can paired associate recall in rats tell us about the neural basis of episodic memory? Theoretical comment on Kesner, Hunsaker, & Warthen (2008).

PubMed

Langston, Rosamund F; Wood, Emma R

2008-12-01

Detailed memories for unique episodes from an individual's past can be triggered, often effortlessly, when that individual is exposed to a stimulus that was present during the original event. The aim of Kesner et al. is to understand the neural basis of memory encoding that supports this cued recall of episodic memories. Kesner and colleagues make novel use of an object-place paired-associate task for rats to provide evidence for a critical role of dorsal CA3 in certain aspects of episodic memory encoding. Using one-trial cued recall versions of the task they show that when rats are cued with an object stimulus, they can be trained to revisit the location in which the object appeared previously. Conversely, when rats are cued with a location, they can learn to choose the object with which it was associated. Rats with dorsal CA3 lesions are severely impaired at these tasks. These data are consistent with the theory that the autoassociative network in CA3 supports the rapid formation of novel associations and may allow pattern completion--the phenomenom whereby a subset of the cues present at an encoding event triggers recall of the whole event. Although flexible recall of arbitrary associations is not fully demonstrated, the study contributes 2 novel behavioral tasks to the previously limited repertoire for studying paired associate recall in rats. It also builds on previous data to specify the role of the hippocampal CA3 subregion in cued recall--a critical aspect of episodic memory.

Who, what, where, when (and maybe even why)? How the experience of sexual reward connects sexual desire, preference, and performance.

PubMed

Pfaus, James G; Kippin, Tod E; Coria-Avila, Genaro A; Gelez, Hélène; Afonso, Veronica M; Ismail, Nafissa; Parada, Mayte

2012-02-01

Although sexual behavior is controlled by hormonal and neurochemical actions in the brain, sexual experience induces a degree of plasticity that allows animals to form instrumental and Pavlovian associations that predict sexual outcomes, thereby directing the strength of sexual responding. This review describes how experience with sexual reward strengthens the development of sexual behavior and induces sexually-conditioned place and partner preferences in rats. In both male and female rats, early sexual experience with partners scented with a neutral or even noxious odor induces a preference for scented partners in subsequent choice tests. Those preferences can also be induced by injections of morphine or oxytocin paired with a male rat's first exposure to scented females, indicating that pharmacological activation of opioid or oxytocin receptors can "stand in" for the sexual reward-related neurochemical processes normally activated by sexual stimulation. Conversely, conditioned place or partner preferences can be blocked by the opioid receptor antagonist naloxone. A somatosensory cue (a rodent jacket) paired with sexual reward comes to elicit sexual arousal in male rats, such that paired rats with the jacket off show dramatic copulatory deficits. We propose that endogenous opioid activation forms the basis of sexual reward, which also sensitizes hypothalamic and mesolimbic dopamine systems in the presence of cues that predict sexual reward. Those systems act to focus attention on, and activate goal-directed behavior toward, reward-related stimuli. Thus, a critical period exists during an individual's early sexual experience that creates a "love map" or Gestalt of features, movements, feelings, and interpersonal interactions associated with sexual reward.

Impairment of sensory-motor plasticity in mild Alzheimer's disease.

PubMed

Terranova, Carmen; Carmen, Terranova; SantAngelo, Antonino; Antonino, Sant'Angelo; Morgante, Francesca; Francesca, Morgante; Rizzo, Vincenzo; Vincenzo, Rizzo; Allegra, Roberta; Roberta, Allegra; Arena, Maria Grazia; Grazia, Arena Maria; Ricciardi, Lucia; Lucia, Ricciardi; Ghilardi, Marie Felice; Felice, Ghilardi Maria; Girlanda, Paolo; Paolo, Girlanda; Quartarone, Angelo; Angelo, Quartarone

2013-01-01

Primary motor cortex (M1) is relatively spared in the early stages of Alzheimer's disease (AD). Aim of the present study was to investigate whether abnormal M1 synaptic plasticity is present at an early stage of AD. We employed an electrophysiological protocol, named rapid paired associative stimulation (rPAS), involving repetitive transcranial magnetic stimulation (rTMS) paired with electrical stimulation of the contralateral median nerve, that modifies corticospinal excitability and short latency afferent inhibition (SAI). We studied 10 patients with a diagnosis of probable mild AD according to the Mini Mental State Examination score (minimum 21) and 14 age-matched control subjects. Motor evoked potentials (MEP) amplitudes and short-afferent inhibition (SAI) were measured at baseline before and for up to 60 min after 5Hz-rPAS in abductor pollicis brevis (APB). rPAS consisted of 600 pairs of transcranial magnetic stimuli, at a rate of 5 Hz for 2 min, coupled with electrical median nerve stimulation preceding TMS over the contralateral M1 at an inter-stimulus interval of 25 ms. Baseline SAI was significantly reduced in AD patients. In the control subjects rPAS induced a significant increase in MEP amplitudes and a decrease of SAI in the APB muscle persistently for up to 1 h. Conversely 5Hz-rPAS did not induce any significant changes in MEP amplitudes and SAI in mild AD patients. Sensory-motor plasticity is impaired in the motor cortex of AD at an early stage of the disease. Copyright © 2013 Elsevier Inc. All rights reserved.

Family history of psychosis moderates early auditory cortical response abnormalities in non-psychotic bipolar disorder

PubMed Central

Hamm, Jordan P; Ethridge, Lauren E; Shapiro, John R; Pearlson, Godfrey D; Tamminga, Carol A; Sweeney, John A; Keshavan, Matcheri S; Thaker, Gunvant K; Clementz, Brett A

2017-01-01

Objectives Bipolar I disorder is a disabling illness affecting 1% of people worldwide. Family and twin studies suggest that psychotic bipolar disorder (BDP) represents a homogenous subgroup with an etiology distinct from non-psychotic bipolar disorder (BDNP) and partially shared with schizophrenia. Studies of auditory electrophysiology [e.g., paired-stimulus and oddball measured with electroencephalography (EEG)] consistently report deviations in psychotic groups (schizophrenia, BDP), yet such studies comparing BDP and BDNP are sparse and, in some cases, conflicting. Auditory EEG responses are significantly reduced in unaffected relatives of psychosis patients, suggesting that they may relate to both psychosis liability and expression. Methods While 64-sensor EEGs were recorded, age- and gender-matched samples of 70 BDP, 35 BDNP {20 with a family history of psychosis [BDNP(+)]}, and 70 psychiatrically healthy subjects were presented typical auditory paired-stimuli and auditory oddball paradigms. Results Oddball P3b reductions were present and indistinguishable across all patient groups. P2s to paired-stimuli were abnormal only in BDP and BDNP(+). Conversely, N1 reductions to stimuli in both paradigms and P3a reductions were present in both BDP and BDNP(−) groups but were absent in BDNP(+). Conclusions While nearly all auditory neural response components studied were abnormal in BDP, BDNP abnormalities at early- and mid-latencies were moderated by family psychosis history. The relationship between psychosis expression, heritable psychosis risk, and neurophysiology within bipolar disorder, therefore, may be complex. Consideration of such clinical disease heterogeneity may be important for future investigations of the pathophysiology of major psychiatric disturbance. PMID:23941660

Facebook dethroned: Revealing the more likely social media destinations for college students’ depictions of underage drinking

PubMed Central

Boyle, Sarah C.; Earle, Andrew M.; LaBrie, Joseph W.; Ballou, Kayla

2016-01-01

Studies examining representations of college drinking on social media have almost exclusively focused on Facebook. However, recent research suggests college students may be more influenced by peers’ alcohol-related posts on Instagram and Snapchat, two image-based platforms popular among this demographic. One potential explanation for this differential influence is that qualitative distinctions in the types of alcohol-related content posted by students on these three platforms may exist. Informed by undergraduate focus groups, this study examined the hypothesis that, of the three platforms, students tend to use Instagram most often for photos glamourizing drinking and Snapchat for incriminating photos of alcohol misuse and negative consequences. Undergraduate research assistants aided investigators in developing hypothetical vignettes and photographic examples of posts both glamorizing and depicting negative consequences associated with college drinking. In an online survey, vignette and photo stimuli were followed by counterbalanced paired comparisons that presented each possible pair of social media platforms. Undergraduates (N=196) selected the platform from each pair on which they would be more likely to see each post. Generalized Bradley-Terry models examined the probabilities of platform selections. As predicted, Instagram was seen as the most probable destination (and Facebook least probable) for photos depicting alcohol use as attractive and glamorous. Conversely, Snapchat was selected as the most probable destination (and Facebook least probable) for items depicting negative consequences associated with heavy drinking. Results suggest researchers aiming to mitigate the potential influences associated with college students’ glamorous and consequential alcohol-related photos posted social media posts should shift their focus from Facebook to Instagram and Snapchat. PMID:27776267

Synthesis of the signal molecule acetylcholine during the developmental cycle of Paramecium primaurelia (Protista, Ciliophora) and its possible function in conjugation.

PubMed

Delmonte Corrado, M U; Politi, H; Ognibene, M; Angelini, C; Trielli, F; Ballarini, P; Falugi, C

2001-06-01

We recently discovered, in mating-competent Paramecium primaurelia, the presence of functionally related molecules of the cholinergic system: the neurotransmitter acetylcholine (ACh), both its nicotinic and muscarinic receptors and its lytic enzyme acetylcholinesterase (AChE). Our results on the inhibition of mating-cell pairing in vivo in mating-competent cells treated with cholinomimetic drugs support the hypothesis that the cholinergic system plays a role in cell-to-cell adhesion. To investigate the possible function of the signal molecule ACh in conjugation in P. primaurelia, we attempted to detect the intracellular sites of ACh synthesis by localizing the ACh biosynthetic enzyme choline acetyltransferase (ChAT). Using immunocytochemical and histochemical methods, we have demonstrated the presence and activity of ChAT principally on the surface membrane of mating-competent cells and of mature but non-mating-competent cells. No evidence for ChAT activity was found in immature cells. Immunoblot analysis revealed the presence of immunoreactive bands, ranging in molecular mass from 42 to 133 kDa, as reported for ChAT isolated from higher organisms. In vivo experiments showed that inhibition of ChAT activity by Congo Red, known to be a potent competitive inhibitor of acetyl coenzyme A, did not affect mating-cell pairing. Conversely, inhibition of AChE with BW 284c51 or eserine, which block enzyme activity by reacting with a specific serine within the catalytic centre, significantly inhibited mating-cell pairing. Our results suggest that ACh has a negative modulating effect on conjugation in P. primaurelia.

The road to superconducting spintronics

NASA Astrophysics Data System (ADS)

Eschrig, Matthias

Energy efficient computing has become a major challenge, with the increasing importance of large data centres across the world, which already today have a power consumption comparable to that of Spain, with steeply increasing trend. Superconducting computing is progressively becoming an alternative for large-scale applications, with the costs for cooling being largely outweighed by the gain in energy efficiency. The combination of superconductivity and spintronics - ``superspintronics'' - has the potential and flexibility to develop into such a green technology. This young field is based on the observation that new phenomena emerge at interfaces between superconducting and other, competing, phases. The past 15 years have seen a series of pivotal predictions and experimental discoveries relating to the interplay between superconductivity and ferromagnetism. The building blocks of superspintronics are equal-spin Cooper pairs, which are generated at the interface between superconducting and a ferromagnetic materials in the presence of non-collinear magnetism. Such novel, spin-polarised Cooper pairs carry spin-supercurrents in ferromagnets and thus contribute to spin-transport and spin-control. Geometric Berry phases appear during the singlet-triplet conversion process in structures with non-coplanar magnetisation, enhancing functionality of devices, and non-locality introduced by superconducting order leads to long-range effects. With the successful generation and control of equal-spin Cooper pairs the hitherto notorious incompatibility of superconductivity and ferromagnetism has been not only overcome, but turned synergistic. I will discuss these developments and their extraordinary potential. I also will present open questions posed by recent experiments and point out implications for theory. This work is supported by the Engineering and Physical Science Research Council (EPSRC Grant No. EP/J010618/1).

EPR experiment and 2-photon interferometry: Report of a 2-photon interference experiment

NASA Technical Reports Server (NTRS)

Shih, Y. H.; Rubin, M. H.; Sergienko, A. V.

1992-01-01

After a very brief review of the historical Einstein, Podolsky, and Rosen (EPR) experiments, a new two-photon interference type EPR experiment is reported. A two-photon state was generated by optical parametric down conversion. Pairs of light quanta with degenerate frequency but divergent directions of propagation were sent to two independent Michelson interferometers. First and second order interference effectors were studied. Different than other reports, we observed that the second order interference visibility vanished when the optical path difference of the interferometers were much less than the coherence length of the pumping laser beam. However, we also observed that the second order interference behaved differently depending on whether the interferometers were set at equal or different optical path differences.

2D lateral heterostructures of group-III monochalcogenide: Potential photovoltaic applications

NASA Astrophysics Data System (ADS)

Cheng, Kai; Guo, Yu; Han, Nannan; Jiang, Xue; Zhang, Junfeng; Ahuja, Rajeev; Su, Yan; Zhao, Jijun

2018-04-01

Solar photovoltaics provides a practical and sustainable solution to the increasing global energy demand. Using first-principles calculations, we investigate the energetics and electronic properties of two-dimensional lateral heterostructures by group-III monochalcogenides and explore their potential applications in photovoltaics. The band structures and formation energies from supercell calculations demonstrate that these heterostructures retain semiconducting behavior and might be synthesized in laboratory using the chemical vapor deposition technique. According to the computed band offsets, most of the heterojunctions belong to type II band alignment, which can prevent the recombination of electron-hole pairs. Besides, the electronic properties of these lateral heterostructures can be effectively tailored by the number of layers, leading to a high theoretical power conversion efficiency over 20%.

An optical and magnetic resonance study of point defects in silicon, diamond, and aluminum nitride

NASA Astrophysics Data System (ADS)

Mason, Philip Wayne

1998-12-01

Optical and magnetic resonance studies of point defects in silicon, diamond, and aluminum nitride semiconducting crystals are described in this dissertation. In silicon, an optically detected magnetic resonance (ODMR) study of a sulfur-related defect with two stable configurations, Ssb{A} and Ssb{B}, each with its own photoluminescence (PL) band and associated ODMR spectrum, is discussed. Through ODMR and related linear polarization studies, the Ssb{A} configuration is conclusively determined to have Csb1 (triclinic) symmetry (which is also the tentative finding for Ssb{B}), a controversial issue in the literature. A conversion study comparing the PL and PLODMR shows a one-to-one conversion between the two configurations for each type of signal. Related findings also tentatively suggest that the Ssb{B} configuration is metastable in both the neutral and single positive charge states of the defect. In addition, an independent analysis presented of uniaxial stress data obtained at King's College, London, shows evidence that an inverted energy-level ordering of the excited electronic effective mass states (Asb1 above E) explains the data better than the opposite ordering which is usually observed for effective mass systems. The mechanism responsible for inversion is currently not known. In diamond, a 1.4 eV Ni-related band with very sharp zero-phonon lines is studied using magnetic circular dichroism in absorption (MCDA). A tunable laser was used to directly measure circular polarization properties of transitions between individual Zeeman-split spin states. The Zeeman study also provided a determination of their associated g-values. A comparison with a theoretical model involving intra-d-shell transitions of Ni indicates that a transition from a ground state of Gammasb{5,6}(sp2E) symmetry to a Gammasb4(sp2Asb1) excited state explains the experimental MCDA findings and agrees with results from a previous uniaxial stress polarization study of luminescence associated with the same transition. Finally, a PLODMR study of several aluminum nitride crystals is also presented. The crystals were observed to emit a broad PL band comprised of numerous overlapping bands, each with its own signature ODMR signal. These new spectra include four effective spin S = 1 centers and a pair of S = 1/2 centers exhibiting characteristics expected for distant-pair recombinations. Two recombination models, either of which may explain a pair of S = 1 centers that appear to be related, are discussed.

Mode Engineering of Single Photons from Cavity Spontaneous Parametric Down-Conversion Source and Quantum Dots

NASA Astrophysics Data System (ADS)

Paudel, Uttam

Over the past decade, much effort has been made in identifying and characterizing systems that can form a building block of quantum networks, among which semiconductor quantum dots (QD) and spontaneous parametric down-conversion (SPDC) source are two of the most promising candidates. The work presented in this thesis will be centered on investigating and engineering the mentioned systems for generating customizable single photons. A type-II SPDC source can generate a highly flexible pair of entangled photons that can be used to interface disparate quantum systems. In this thesis, we have successfully implemented a cavity-SPDC source that emits polarization correlated photons at 942 nm with a lifetime of 950-1050ps that mode matches closely with InAs/GaAs QD photons. The source emits 80 photon pairs per second per mW pump power within the 150MHz bandwidth. Though the detection of idler photons, the source is capable of emitting heralded photons with g2?0.5 for up to 40 mW pump power. For a low pump power of 5 mW, the heralded g2 is 0.06, indicating that the system is an excellent heralded single photon source. By directly exciting a single QD with cavity-SPDC photons, we have demonstrated a heralded-absorption of SPDC photons by QD, resulting in the coupling of the two systems. Due to the large pump bandwidth, the emitted source is highly multimode in nature, requiring us to post-filter the downconverted field, resulting in a lower photon pair emission rate. We propose placing an intra-cavity etalon to suppress the multi-mode emissions and increase the photon count rate. Understanding and experimentally implementing two-photon interference (HOM) measurements will be crucial for building a scalable quantum network. A detailed theoretical description of HOM measurements is given and is experimentally demonstrated using photons emitted by QD. Through HOM measurements we demonstrated that the QD sample in the study is capable of emitting indistinguishable photons, with the visibility exceeding 95%. As an alternative approach to modifying the spectral mode of single photons, we performed phase modulation of photons emitted by a QD to generate additional sidebands that are separated by several GHz. By performing HOM measurements, we have shown that the central component and the sidebands are in the superposition states and the spectrally modified photons have a well-preserved indistinguishability. Such spectrally engineered photons can be used for phase-encoded cryptography applications. These experimental results should lay the foundations towards building a scalable hybrid quantum network.

Luminescence in Conjugated Molecular Materials under Sub-bandgap Excitation

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

So, Franky

2014-05-08

Light emission in semiconductors occurs when they are under optical and electrical excitation with energy larger than the bandgap energy. In some low-dimensional semiconductor heterostructure systems, this thermodynamic limit can be violated due to radiative Auger recombination (AR), a process in which the sub-bandgap energy released from a recombined electron-hole pair is transferred to a third particle leading to radiative band-to-band recombination.1 Thus far, photoluminescence up-conversion phenomenon has been observed in some low dimensional semiconductor systems, and the effect is very weak and it can only be observed at low temperatures. Recently, we discovered that efficient electroluminescence in poly[2-methoxy-5-(2’-ethylhexyloxy)-1, phenylenevinylene]more » (MEH-PPV) polymer light-emitting devices (PLEDs) at drive voltages below its bandgap voltage could be observed when a ZnO nanoparticles (NPs) electron injection layer was inserted between the polymer and the aluminum electrode. Specifically, emitted photons with energy of 2.13 eV can be detected at operating voltages as low as 1.2 V at room temperature. Based on these data, we propose that the sub-bandgap turn-on in the MEH-PPV device is due to an Auger-assisted energy up-conversion process. The significance of this discovery is three-fold. First, radiative recombination occurs at operating voltages below the thermodynamic bandgap voltage. This process can significantly reduce the device operating voltage. For example, the current density of the device with the ZnO NC layer is almost two orders of magnitude higher than that of the device without the NC layer. Second, a reactive metal is no longer needed for the cathode. Third, this electroluminescence up-conversion process can be applied to inorganic semiconductors systems as well and their operation voltages of inorganic LEDs can be reduced to about half of the bandgap energy. Based on our initial data, we propose that the sub-bandgap turn-on in MEH-PPV devices is due to Auger-assisted energy up-conversion process. Specifically, we propose that the up-conversion process is due to charge accumulation at the polymer/NPs interface. This model requires that holes should be the dominant carriers in the polymer and the polymer/ZnO NCs heterojunction should be a type II alignment. In order to determine the mechanism of the up-conversion process, we will characterize devices fabricated using polymers with different carrier transporting properties to determine whether hole accumulation at the polymer/nanocrystals is required. Likewise, we will also use NPs with different electronic structures to fabricate devices to determine how electron accumulation affects the up-conversion process. Finally, we will measure quantitatively the interface charge accumulation by electroabsorption and correlate the results with the up-conversion photoluminescence efficiency measurements under an applied electric field.« less

The analysis of photon pair source at telecom wavelength based on the BBO crystal (Conference Presentation)

NASA Astrophysics Data System (ADS)

Gajewski, Andrzej; Kolenderski, Piotr L.

2016-10-01

There are several problems that must be solved in order to increase the distance of quantum communication protocols based on photons as an information carriers. One of them is the dispersion, whose effects can be minimized by engineering spectral properties of transmitted photons. In particular, it is expected that positively correlated photon pairs can be very useful. We present the full characterization of a source of single photon pairs at a telecom wavelength based on type II spontaneous parametric down conversion (SPDC) process in a beta-barium borate (BBO) crystal. In the type II process, a pump photon, which is polarized extraordinarily, splits in a nonlinear medium into signal and idler photons, which are polarized perpendicularly to each other. In order for the process to be efficient a phase matching condition must be fulfilled. These conditions originate from momentum and energy conservation rules and put severe restrictions on source parameters. Seemingly, these conditions force the photon pair to be negatively correlated in their spectral domain. However, it is possible to achieve positive correlation for pulsed pumping. The experimentally available degrees of freedom of a source are the width of the pumping beam, the collected modes' widths, the length of the nonlinear crystal and the duration of the pumping pulse. In our numerical model we use the following figures of merit: the pair production rate, the efficiency of photon coupling into a single mode fiber, the spectral correlation of the coupled photon pair. The last one is defined as the Pearson correlation parameter for a joint spectral distribution. The aim here is to find the largest positive spectral correlation and the highest coupling efficiency. By resorting to the numerical model Ref. [1] we showed in Ref. [2], that by careful adjustment of the pump's and the collected modes' characteristics, one can optimize any of the source's parameters. Our numerical outcomes conform to the experimental results presented in Refs [3,4]. Here we investigate typical, experimentally available source parameters: the widths of the pump beam and collected modes ranging from 20μm to 500m, the crystal length ranging from 1mm to 7.5mm while the pulse duration is set to 50fs, 100fs or 150fs. We achieve the correlation coefficient value as high as approximately 0.8, or - for different values of parameters - coupling efficiency equal to 0.76.

Carcass and meat quality traits of chickens fed diets concurrently supplemented with vitamins C and E under constant heat stress.

PubMed

Zeferino, C P; Komiyama, C M; Pelícia, V C; Fascina, V B; Aoyagi, M M; Coutinho, L L; Sartori, J R; Moura, A S A M T

2016-01-01

The objective of this study was to determine if a diet supplemented simultaneously with vitamins C and E would alleviate the negative effects of heat stress, applied between 28 and 42 days of age, on performance, carcass and meat quality traits of broiler chickens. A total of 384 male broiler chickens were assigned to a completely randomized design, with a 2×3 factorial arrangement (diet with or without vitamin supplementation and two ambient temperatures plus a pair-feeding group) and 16 replicates. Chickens were kept in thermoneutral conditions up to 28 days of age. They were then housed in groups of four per cage, in three environmentally controlled chambers: two thermoneutral (22.5 and 22.6°C) and one for heat stress (32°C). Half the chickens were fed a diet supplemented with vitamins C (257 to 288 mg/kg) and E (93 to 109 mg/kg). In the thermoneutral chambers, half of the chickens were pair-fed to heat stressed chickens, receiving each day the average feed intake recorded in the heat stress chamber in the previous day. Meat physical quality analyses were performed on the pectoralis major muscle. No ambient temperature×diet supplementation interaction effects were detected on performance, carcass, or meat quality traits. The supplemented diet resulted in lower growth performance, attributed either to a carry-over effect of the lower initial BW, or to a possible catabolic effect of vitamins C and E when supplemented simultaneously at high levels. Heat stress reduced slaughter and carcass weights, average daily gain and feed intake, and increased feed conversion. Growth performance of pair-fed chickens was similar to that of heat stressed chickens. Exposure to heat stress increased carcass and abdominal fat percentages, but reduced breast, liver and heart percentages. Pair-fed chickens showed the lowest fat percentage and their breast percentage was similar to controls. Heat stress increased meat pH and negatively affected meat color and cooking loss. In pair-fed chickens, meat color was similar to the heat stressed group. Shear force was not influenced by heat stress, but pair-fed chickens showed the tenderest meat. In conclusion, reduction in growth performance and negative changes in meat color in heat stressed chickens were attributed to depression in feed intake, whereas negative changes in body composition, higher meat pH and cooking loss were credited to high ambient temperature per se. Diet supplementation with vitamins C and E as antioxidants did not mitigate any of these negative effects.

Efficient dense blur map estimation for automatic 2D-to-3D conversion

NASA Astrophysics Data System (ADS)

Vosters, L. P. J.; de Haan, G.

2012-03-01

Focus is an important depth cue for 2D-to-3D conversion of low depth-of-field images and video. However, focus can be only reliably estimated on edges. Therefore, Bea et al. [1] first proposed an optimization based approach to propagate focus to non-edge image portions, for single image focus editing. While their approach produces accurate dense blur maps, the computational complexity and memory requirements for solving the resulting sparse linear system with standard multigrid or (multilevel) preconditioning techniques, are infeasible within the stringent requirements of the consumer electronics and broadcast industry. In this paper we propose fast, efficient, low latency, line scanning based focus propagation, which mitigates the need for complex multigrid or (multilevel) preconditioning techniques. In addition we propose facial blur compensation to compensate for false shading edges that cause incorrect blur estimates in people's faces. In general shading leads to incorrect focus estimates, which may lead to unnatural 3D and visual discomfort. Since visual attention mostly tends to faces, our solution solves the most distracting errors. A subjective assessment by paired comparison on a set of challenging low-depth-of-field images shows that the proposed approach achieves equal 3D image quality as optimization based approaches, and that facial blur compensation results in a significant improvement.

A versatile design for resonant guided-wave parametric down-conversion sources for quantum repeaters

NASA Astrophysics Data System (ADS)

Brecht, Benjamin; Luo, Kai-Hong; Herrmann, Harald; Silberhorn, Christine

2016-05-01

Quantum repeaters—fundamental building blocks for long-distance quantum communication—are based on the interaction between photons and quantum memories. The photons must fulfil stringent requirements on central frequency, spectral bandwidth and purity in order for this interaction to be efficient. We present a design scheme for monolithically integrated resonant photon-pair sources based on parametric down-conversion in nonlinear waveguides, which facilitate the generation of such photons. We investigate the impact of different design parameters on the performance of our source. The generated photon spectral bandwidths can be varied between several tens of MHz up to around 1 GHz, facilitating an efficient coupling to different memories. The central frequency of the generated photons can be coarsely tuned by adjusting the pump frequency, poling period and sample temperature, and we identify stability requirements on the pump laser and sample temperature that can be readily fulfilled with off-the-shelf components. We find that our source is capable of generating high-purity photons over a wide range of photon bandwidths. Finally, the PDC emission can be frequency fine-tuned over several GHz by simultaneously adjusting the sample temperature and pump frequency. We conclude our study with demonstrating the adaptability of our source to different quantum memories.

Are shy adults really bolder online? It depends on the context.

PubMed

Brunet, Paul M; Schmidt, Louis A

2008-12-01

We examined whether individual differences in shyness and context influenced the amount of computer-mediated self-disclosure and use of affective language during an unfamiliar dyadic social interaction. Unfamiliar young adults were selected for high and low self-reported shyness and paired in mixed dyads (one shy and one nonshy). Each dyad was randomly assigned to either a live webcam or no webcam condition. Participants then engaged in a 20-minute online free chat over the Internet in the laboratory. Free chat conversations were archived, and the transcripts were objectively coded for traditional communication variables, conversational style, and the use of affective language. As predicted, shy adults engaged in significantly fewer spontaneous self-disclosures than did their nonshy counterparts only in the webcam condition. Shy versus nonshy adults did not differ on spontaneous self-disclosures in the no webcam condition. However, context did not influence the use of computer-mediated affective language. Although shy adults used significantly less active and pleasant words than their nonshy counterparts, these differences were not related to webcam condition. The present findings replicate and extend earlier work on shyness, context, and computer-mediated communication to a selected sample of shy adults. Findings suggest that context may influence some, but not all, aspects of social communication in shy adults.

Ultrabroadband phased-array radio frequency (RF) receivers based on optical techniques

NASA Astrophysics Data System (ADS)

Overmiller, Brock M.; Schuetz, Christopher A.; Schneider, Garrett; Murakowski, Janusz; Prather, Dennis W.

2014-03-01

Military operations require the ability to locate and identify electronic emissions in the battlefield environment. However, recent developments in radio detection and ranging (RADAR) and communications technology are making it harder to effectively identify such emissions. Phased array systems aid in discriminating emitters in the scene by virtue of their relatively high-gain beam steering and nulling capabilities. For the purpose of locating emitters, we present an approach realize a broadband receiver based on optical processing techniques applied to the response of detectors in conformal antenna arrays. This approach utilizes photonic techniques that enable us to capture, route, and process the incoming signals. Optical modulators convert the incoming signals up to and exceeding 110 GHz with appreciable conversion efficiency and route these signals via fiber optics to a central processing location. This central processor consists of a closed loop phase control system which compensates for phase fluctuations induced on the fibers due to thermal or acoustic vibrations as well as an optical heterodyne approach for signal conversion down to baseband. Our optical heterodyne approach uses injection-locked paired optical sources to perform heterodyne downconversion/frequency identification of the detected emission. Preliminary geolocation and frequency identification testing of electronic emissions has been performed demonstrating the capabilities of our RF receiver.

Single nucleotide editing without DNA cleavage using CRISPR/Cas9-deaminase in the sea urchin embryo.

PubMed

Shevidi, Saba; Uchida, Alicia; Schudrowitz, Natalie; Wessel, Gary M; Yajima, Mamiko

2017-12-01

A single base pair mutation in the genome can result in many congenital disorders in humans. The recent gene editing approach using CRISPR/Cas9 has rapidly become a powerful tool to replicate or repair such mutations in the genome. These approaches rely on cleaving DNA, while presenting unexpected risks. In this study, we demonstrate a modified CRISPR/Cas9 system fused to cytosine deaminase (Cas9-DA), which induces a single nucleotide conversion in the genome. Cas9-DA was introduced into sea urchin eggs with sgRNAs targeted for SpAlx1, SpDsh, or SpPks, each of which is critical for skeletogenesis, embryonic axis formation, or pigment formation, respectively. We found that both Cas9 and Cas9-DA edit the genome, and cause predicted phenotypic changes at a similar efficiency. Cas9, however, resulted in significant deletions in the genome centered on the gRNA target sequence, whereas Cas9-DA resulted in single or double nucleotide editing of C to T conversions within the gRNA target sequence. These results suggest that the Cas9-DA approach may be useful for manipulating gene activity with decreased risks of genomic aberrations. Developmental Dynamics 246:1036-1046, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Ethanol dehydration to ethylene in a stratified autothermal millisecond reactor.

PubMed

Skinner, Michael J; Michor, Edward L; Fan, Wei; Tsapatsis, Michael; Bhan, Aditya; Schmidt, Lanny D

2011-08-22

The concurrent decomposition and deoxygenation of ethanol was accomplished in a stratified reactor with 50-80 ms contact times. The stratified reactor comprised an upstream oxidation zone that contained Pt-coated Al(2)O(3) beads and a downstream dehydration zone consisting of H-ZSM-5 zeolite films deposited on Al(2)O(3) monoliths. Ethanol conversion, product selectivity, and reactor temperature profiles were measured for a range of fuel:oxygen ratios for two autothermal reactor configurations using two different sacrificial fuel mixtures: a parallel hydrogen-ethanol feed system and a series methane-ethanol feed system. Increasing the amount of oxygen relative to the fuel resulted in a monotonic increase in ethanol conversion in both reaction zones. The majority of the converted carbon was in the form of ethylene, where the ethanol carbon-carbon bonds stayed intact while the oxygen was removed. Over 90% yield of ethylene was achieved by using methane as a sacrificial fuel. These results demonstrate that noble metals can be successfully paired with zeolites to create a stratified autothermal reactor capable of removing oxygen from biomass model compounds in a compact, continuous flow system that can be configured to have multiple feed inputs, depending on process restrictions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Agmatine attenuates nicotine induced conditioned place preference in mice through modulation of neuropeptide Y system.

PubMed

Kotagale, Nandkishor R; Walke, Sonali; Shelkar, Gajanan P; Kokare, Dadasaheb M; Umekar, Milind J; Taksande, Brijesh G

2014-04-01

The purpose of the present study was to examine the effect of agmatine on nicotine induced conditioned place preference (CPP) in male albino mice. Intra-peritoneal (ip) administration of nicotine (1mg/kg) significantly increased time spent in drug-paired compartment. Agmatine (20 and 40 mg/kg, ip) co-administered with nicotine during the 6 days conditioning sessions completely abolished the acquisition of nicotine-induced CPP in mice. Concomitant administration of neuropeptide Y (NPY) (1 pg/mouse, icv) or [Leu(31), Pro(34)]-NPY (0.1 pg/mouse, icv), selective NPY Y1 receptor agonist potentiated the inhibitory effect of agmatine (10 mg/kg, ip) on nicotine CPP. Conversely, pretreatment with NPY Y1 receptor antagonist, BIBP3226 (0.01 ng/mouse, icv) blocked the effect of agmatine (20 mg/kg, ip) on nicotine induced CPP. In immunohistochemical study, nicotine decreased NPY-immunoreactivity in nucleus accumbens shell (AcbSh), bed nucleus of stria terminalis, lateral part (BNSTl), arcuate nucleus (ARC) and paraventricular nucleus (PVN). Conversely, administration of agmatine prior to the nicotine significantly reversed the effect of nicotine on NPY-immunoreactivity in the above brain nuclei. This data indicate that agmatine attenuate nicotine induced CPP via modulation of NPYergic neurotransmission in brain. Copyright © 2014 Elsevier B.V. All rights reserved.

Cerium chloride stimulated controlled conversion of B-to-Z DNA in self-assembled nanostructures

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

Bhanjadeo, Madhabi M.; Academy of Scientific & Innovative Research; Nayak, Ashok K.

DNA adopts different conformation not only because of novel base pairs but also while interacting with inorganic or organic compounds. Self-assembled branched DNA (bDNA) structures or DNA origami that change conformation in response to environmental cues hold great promises in sensing and actuation at the nanoscale. Recently, the B-Z transition in DNA is being explored to design various nanomechanical devices. In this communication we have demonstrated that Cerium chloride binds to the phosphate backbone of self-assembled bDNA structure and induce B-to-Z transition at physiological concentration. The mechanism of controlled conversion from right-handed to left-handed has been assayed by various dyemore » binding studies using CD and fluorescence spectroscopy. Three different bDNA structures have been identified to display B-Z transition. This approach provides a rapid and reversible means to change bDNA conformation, which can be used for dynamic and progressive control at the nanoscale. - Highlights: • Cerium-induced B-to-Z DNA transition in self-assembled nanostructures. • Lower melting temperature of Z-DNA than B-DNA confirmed by CD spectroscopy. • Binding mechanism of cerium chloride is explained using fluorescence spectroscopy. • Right-handed to left-handed DNA conformation is also noticed in modified bDNA structure.« less

Flexible and Robust Thermoelectric Generators Based on All-Carbon Nanotube Yarn without Metal Electrodes.

PubMed

Choi, Jaeyoo; Jung, Yeonsu; Yang, Seung Jae; Oh, Jun Young; Oh, Jinwoo; Jo, Kiyoung; Son, Jeong Gon; Moon, Seung Eon; Park, Chong Rae; Kim, Heesuk

2017-08-22

As practical interest in flexible/or wearable power-conversion devices increases, the demand for high-performance alternatives to thermoelectric (TE) generators based on brittle inorganic materials is growing. Herein, we propose a flexible and ultralight TE generator (TEG) based on carbon nanotube yarn (CNTY) with excellent TE performance. The as-prepared CNTY shows a superior electrical conductivity of 3147 S/cm due to increased longitudinal carrier mobility derived from a highly aligned structure. Our TEG is innovative in that the CNTY acts as multifunctions in the same device. The CNTY is alternatively doped into n- and p-types using polyethylenimine and FeCl 3 , respectively. The highly conductive CNTY between the doped regions is used as electrodes to minimize the circuit resistance, thereby forming an all-carbon TEG without additional metal deposition. A flexible TEG based on 60 pairs of n- and p-doped CNTY shows the maximum power density of 10.85 and 697 μW/g at temperature differences of 5 and 40 K, respectively, which are the highest values among reported TEGs based on flexible materials. We believe that the strategy proposed here to improve the power density of flexible TEG by introducing highly aligned CNTY and designing a device without metal electrodes shows great potential for the flexible/or wearable power-conversion devices.

Kolakoski sequence as an element to radiate giant forward and backward second harmonic signals

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

Parvini, T. S.; Tehranchi, M. M., E-mail: m-hamidi@sbu.ac.ir, E-mail: teranchi@sbu.ac.ir; Laser and Plasma Research Institute, Shahid Beheshti University, Tehran

2015-11-14

We propose a novel type of aperiodic one-dimensional photonic crystal structures which can be used for generating giant forward and backward second harmonic signals. The studied structure is formed by stacking together the air and nonlinear layers according to the Kolakoski self-generation scheme in which each nonlinear layer contains a pair of antiparallel 180° poled LiNbO{sub 3} crystal layers. For different generation stages of the structure, conversion efficiencies of forward and backward second harmonic waves have been calculated by nonlinear transfer matrix method. Numerical simulations show that conversion efficiencies in the Kolakoski-based multilayer are larger than the perfect ones formore » at least one order of magnitude. Especially for 33rd and 39th generation stages, forward second harmonic wave are 42 and 19 times larger, respectively. In this paper, we validate the strong fundamental field enhancement and localization within Kolakoski-based multilayer due to periodicity breaking which consequently leads to very strong radiation of backward and forward second harmonic signals. Following the applications of analogous aperiodic structures, we expect that Kolakosi-based multilayer can play a role in optical parametric devices such as multicolor second harmonic generators with high efficiency.« less

Parents' experience of a follow-up meeting after a child's death in the Paediatric Intensive Care Unit.

PubMed

Brink, Helle L; Thomsen, Anja K; Laerkner, Eva

2017-02-01

'To identify parents' experience of a follow up meeting and to explore whether the conversation was adequate to meet the needs of parents for a follow-up after their child's death in the Paediatric Intensive Care Unit (PICU). Qualitative method utilising semi-structured interviews with six pairs of parents 2-12 weeks after the follow-up conversation. The interviews were held in the parents' homes at their request. Data were analysed using a qualitative, descriptive approach and thematic analysis. Four main themes emerged: (i) the way back to the PICU; (ii) framework; (iii) relations and (iv) closure. The parents expressed nervousness before the meeting, but were all pleased to have participated in these follow-up meetings. The parents found it meaningful that the follow-up meeting was interdisciplinary, since the parents could have answers to their questions both about treatment and care. It was important that the staff involved in the follow-up meeting were those who had been present through the hospitalisation and at the time of the child's death. Parents experienced the follow-up meeting as being a closure of the course in the PICU, regardless the length of the hospitalisation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Water-Soluble Phosphine-Protected Au₁₁ Clusters: Synthesis, Electronic Structure, and Chiral Phase Transfer in a Synergistic Fashion.

PubMed

Yao, Hiroshi; Iwatsu, Mana

2016-04-05

Synthesis of atomically precise, water-soluble phosphine-protected gold clusters is still currently limited probably due to a stability issue. We here present the synthesis, magic-number isolation, and exploration of the electronic structures as well as the asymmetric conversion of triphenylphosphine monosulfonate (TPPS)-protected gold clusters. Electrospray ionization mass spectrometry and elemental analysis result in the primary formation of Au11(TPPS)9Cl undecagold cluster compound. Magnetic circular dichroism (MCD) spectroscopy clarifies that extremely weak transitions are present in the low-energy region unresolved in the UV-vis absorption, which can be due to the Faraday B-terms based on the magnetically allowed transitions in the cluster. Asymmetric conversion without changing the nuclearity is remarkable by the chiral phase transfer in a synergistic fashion, which yields a rather small anisotropy factor (g-factor) of at most (2.5-7.0) × 10(-5). Quantum chemical calculations for model undecagold cluster compounds are then used to evaluate the optical and chiroptical responses induced by the chiral phase transfer. On this basis, we find that the Au core distortion is ignorable, and the chiral ion-pairing causes a slight increase in the CD response of the Au11 cluster.

SorghumFDB: sorghum functional genomics database with multidimensional network analysis.

PubMed

Tian, Tian; You, Qi; Zhang, Liwei; Yi, Xin; Yan, Hengyu; Xu, Wenying; Su, Zhen

2016-01-01

Sorghum (Sorghum bicolor [L.] Moench) has excellent agronomic traits and biological properties, such as heat and drought-tolerance. It is a C4 grass and potential bioenergy-producing plant, which makes it an important crop worldwide. With the sorghum genome sequence released, it is essential to establish a sorghum functional genomics data mining platform. We collected genomic data and some functional annotations to construct a sorghum functional genomics database (SorghumFDB). SorghumFDB integrated knowledge of sorghum gene family classifications (transcription regulators/factors, carbohydrate-active enzymes, protein kinases, ubiquitins, cytochrome P450, monolignol biosynthesis related enzymes, R-genes and organelle-genes), detailed gene annotations, miRNA and target gene information, orthologous pairs in the model plants Arabidopsis, rice and maize, gene loci conversions and a genome browser. We further constructed a dynamic network of multidimensional biological relationships, comprised of the co-expression data, protein-protein interactions and miRNA-target pairs. We took effective measures to combine the network, gene set enrichment and motif analyses to determine the key regulators that participate in related metabolic pathways, such as the lignin pathway, which is a major biological process in bioenergy-producing plants.Database URL: http://structuralbiology.cau.edu.cn/sorghum/index.html. © The Author(s) 2016. Published by Oxford University Press.

Structure of multiphoton quantum optics. I. Canonical formalism and homodyne squeezed states

NASA Astrophysics Data System (ADS)

dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio

2004-03-01

We introduce a formalism of nonlinear canonical transformations for general systems of multiphoton quantum optics. For single-mode systems the transformations depend on a tunable free parameter, the homodyne local-oscillator angle; for n -mode systems they depend on n heterodyne mixing angles. The canonical formalism realizes nontrivial mixing of pairs of conjugate quadratures of the electromagnetic field in terms of homodyne variables for single-mode systems, and in terms of heterodyne variables for multimode systems. In the first instance the transformations yield nonquadratic model Hamiltonians of degenerate multiphoton processes and define a class of non-Gaussian, nonclassical multiphoton states that exhibit properties of coherence and squeezing. We show that such homodyne multiphoton squeezed states are generated by unitary operators with a nonlinear time evolution that realizes the homodyne mixing of a pair of conjugate quadratures. Tuning of the local-oscillator angle allows us to vary at will the statistical properties of such states. We discuss the relevance of the formalism for the study of degenerate (up-)down-conversion processes. In a companion paper [

Structure of multiphoton quantum optics. I. Canonical formalism and homodyne squeezed states

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

Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio

2004-03-01

We introduce a formalism of nonlinear canonical transformations for general systems of multiphoton quantum optics. For single-mode systems the transformations depend on a tunable free parameter, the homodyne local-oscillator angle; for n-mode systems they depend on n heterodyne mixing angles. The canonical formalism realizes nontrivial mixing of pairs of conjugate quadratures of the electromagnetic field in terms of homodyne variables for single-mode systems, and in terms of heterodyne variables for multimode systems. In the first instance the transformations yield nonquadratic model Hamiltonians of degenerate multiphoton processes and define a class of non-Gaussian, nonclassical multiphoton states that exhibit properties of coherencemore » and squeezing. We show that such homodyne multiphoton squeezed states are generated by unitary operators with a nonlinear time evolution that realizes the homodyne mixing of a pair of conjugate quadratures. Tuning of the local-oscillator angle allows us to vary at will the statistical properties of such states. We discuss the relevance of the formalism for the study of degenerate (up-)down-conversion processes. In a companion paper [F. Dell'Anno, S. De Siena, and F. Illuminati, 69, 033813 (2004)], we provide the extension of the nonlinear canonical formalism to multimode systems, we introduce the associated heterodyne multiphoton squeezed states, and we discuss their possible experimental realization.« less

Cognitive Load Reduces Perceived Linguistic Convergence Between Dyads.

PubMed

Abel, Jennifer; Babel, Molly

2017-09-01

Speech convergence is the tendency of talkers to become more similar to someone they are listening or talking to, whether that person is a conversational partner or merely a voice heard repeating words. To elucidate the nature of the mechanisms underlying convergence, this study uses different levels of task difficulty on speech convergence within dyads collaborating on a task. Dyad members had to build identical LEGO® constructions without being able to see each other's construction, and with each member having half of the instructions required to complete the construction. Three levels of task difficulty were created, with five dyads at each level (30 participants total). Task difficulty was also measured using completion time and error rate. Listeners who heard pairs of utterances from each dyad judged convergence to be occurring in the Easy condition and to a lesser extent in the Medium condition, but not in the Hard condition. Amplitude envelope acoustic similarity analyses of the same utterance pairs showed that convergence occurred in dyads with shorter completion times and lower error rates. Together, these results suggest that while speech convergence is a highly variable behavior, it may occur more in contexts of low cognitive load. The relevance of these results for the current automatic and socially-driven models of convergence is discussed.

Dopaminergic Signaling Mediates the Motivational Response Underlying the Opponent Process to Chronic but Not Acute Nicotine

PubMed Central

Grieder, Taryn E; Sellings, Laurie H; Vargas-Perez, Hector; Ting-A-Kee, Ryan; Siu, Eric C; Tyndale, Rachel F; van der Kooy, Derek

2010-01-01

The mesolimbic dopamine (DA) system is implicated in the processing of the positive reinforcing effect of all drugs of abuse, including nicotine. It has been suggested that the dopaminergic system is also involved in the aversive motivational response to drug withdrawal, particularly for opiates, however, the role for dopaminergic signaling in the processing of the negative motivational properties of nicotine withdrawal is largely unknown. We hypothesized that signaling at dopaminergic receptors mediates chronic nicotine withdrawal aversions and that dopaminergic signaling would differentially mediate acute vs dependent nicotine motivation. We report that nicotine-dependent rats and mice showed conditioned place aversions to an environment paired with abstinence from chronic nicotine that were blocked by the DA receptor antagonist α-flupenthixol (α-flu) and in DA D2 receptor knockout mice. Conversely, α-flu pretreatment had no effect on preferences for an environment paired with abstinence from acute nicotine. Taken together, these results suggest that dopaminergic signaling is necessary for the opponent motivational response to nicotine in dependent, but not non-dependent, rodents. Further, signaling at the DA D2 receptor is critical in mediating withdrawal aversions in nicotine-dependent animals. We suggest that the alleviation of nicotine withdrawal primarily may be driving nicotine motivation in dependent animals. PMID:20032966