Nanosecond Dynamics of Single-Molecule Fluorescence Resonance Energy Transfer

Motivated by recent experiments on photon statistics from individual dye pairs planted on biomolecules and coupled by fluorescence resonance energy transfer (FRET), we show here that the FRET dynamics can be modelled by Gaussian random processes with colored noise. Using Monte-Carlo numerical simulations, the photon intensity correlations from the FRET pairs are calculated, and are turned out to be very close to those observed in experiment. The proposed stochastic description of FRET is consistent with existing theories for microscopic dynamics of the biomolecule that carries the FRET coupled dye pairs.Comment: 8 pages, 1 figure. accepted to J.Phys.Chem.

A New Measurement of the Temperature Density Relation of the IGM From Voigt Profile Fitting

We decompose the Lyman-{\alpha} (Ly{\alpha}) forest of an extensive sample of 74 high signal-to-noise ratio and high-resolution quasar spectra into a collection of Voigt profiles. Absorbers located near caustics in the peculiar velocity field have the smallest Doppler parameters, resulting in a low-$b$ cutoff in the $b$-$N_{\text{HI}}$ set by the thermal state of intergalactic medium (IGM). We fit this cutoff as a function of redshift over the range $2.0\leq z \leq 3.4$, which allows us to measure the evolution of the IGM temperature-density ($T= T_0 (\rho/ \rho_0)^{\gamma-1}$) relation parameters $T_0$ and $\gamma$. We calibrate our measurements against Ly$\alpha$ forest simulations, using 21 different thermal models of the IGM at each redshift, also allowing for different values of the IGM pressure smoothing scale. We adopt a forward-modeling approach and self-consistently apply the same algorithms to both data and simulations, propagating both statistical and modeling uncertainties via Monte Carlo. The redshift evolution of $T_0$ shows a suggestive peak at $z=2.8$, while our evolution of $\gamma$ is consistent with $\gamma\simeq 1.4$ and disfavors inverted temperature-density relations. Our measured evolution of $T_0$ and $\gamma$ are generally in good agreement with previous determinations in the literature. Both the peak in the evolution of $T_0$ at $z = 2.8$, as well as the high temperatures $T_0\simeq 15000-20000\,$K that we observe at $2.4 < z < 3.4$, strongly suggest that a significant episode of heating occurred after the end of HI reionization, which was most likely the cosmic reionization of HeII.Comment: Accepted for publication in ApJ, 23 pages, 26 figures, machine readable tables available onlin

Heralded generation of entangled photon pairs

Entangled photons are a crucial resource for quantum communication and linear optical quantum computation. Unfortunately, the applicability of many photon-based schemes is limited due to the stochastic character of the photon sources. Therefore, a worldwide effort has focused in overcoming the limitation of probabilistic emission by generating two-photon entangled states conditioned on the detection of auxiliary photons. Here we present the first heralded generation of photon states that are maximally entangled in polarization with linear optics and standard photon detection from spontaneous parametric down-conversion. We utilize the down-conversion state corresponding to the generation of three photon pairs, where the coincident detection of four auxiliary photons unambiguously heralds the successful preparation of the entangled state. This controlled generation of entangled photon states is a significant step towards the applicability of a linear optics quantum network, in particular for entanglement swapping, quantum teleportation, quantum cryptography and scalable approaches towards photonics-based quantum computing

Estilos de ense?anza de los docentes de la instituci?n educativa Totarco Dinde del municipio de Coyaima Tolima

54 p. Recurso Electr?nicoComprender mejor y con bases cient?ficas las relaciones entre las concepciones sobre la ense?anza y la pr?ctica de los docentes en el aula de clase, permite tanto a las instituciones de educaci?n como a los profesores, iniciar acciones de mejoramiento. (De Vinzenci, 2009). El estilo de ense?anza de los docentes es uno de esos elementos a comprender, definido como un conjunto de recursos subjetivos de forma. Relacionados con la manera de hablar, la actitud y las expectativas que los docentes transmiten. (Delgado, 1991). El objetivo general de esta investigaci?n fue caracterizar los estilos de ense?anza, presentes en los profesores de educaci?n secundaria y media de la instituci?n educativa Totarco Dinde del Municipio de Coyaima Tolima. La investigaci?n se desarroll? con un m?todo cuantitativo descriptivo no experimental o esfosfacto. La poblaci?n objeto de la investigaci?n fueron los 15 docentes que orientan clase en Secundaria y Media de la Instituci?n Educativa Totarco Dinde del municipio de Coyaima Tolima. Y se tom? como muestra a 12 docentes por ser este un n?mero significativo para representar a la poblaci?n. Se les aplico una adaptaci?n del cuestionario ?DEMEVI? (Delgado, 1998) teniendo en cuenta que el cuestionario ?DEMEVI? ha sido validado y usado con ?xito en varias ocasiones. La investigaci?n mostro que los docentes de Secundaria y Media de la Instituci?n Educativa Totarco Dinde del municipio de Coyaima departamento del Tolima, hacen una mezcla de estilos de ense?anza, hay muestra de pr?cticas relacionadas con los seis (6) estilos de ense?anza planteados por Delgado, (1991) en suma est?n presentes en la Instituci?n los seis (6) estilos. Siendo el m?s predominante el estilo Creativo, seguido del estilo Socializador. Se recomienda complementar el trabajo realizado con la realizaci?n de una investigaci?n que incluya un instrumento de observaci?n que permita cruzar resultados y as? confirmar que en la pr?ctica los docentes est?n aplicando los estilos conforme a los resultados arrojados en esta investigaci?n. Palabras claves: Estilos de ense?anza docente, estilo de ense?anza, Estilo docente, Totarco Dinde.Having a better scientific-based understanding of the relations between teaching conceptions and teachers? practice in the classroom, allows both educational institutions and teachers to initiate improvement actions. (De Vinzenci, 2009). Teaching style is one of those elements to be understood, defined as a set of subjective resources of form; related to the way of speaking, the attitude and the expectations that teachers transmit (Delgado, 1991). The general objective of this research was to characterize the teaching styles present in middle and secondary school teachers of Totarco Dinde school of the Municipality of Coyaima-Tolima. The research was developed with a non-experimental quantitative descriptive method. The target population was the 15 teachers of the school, from which, 12 were taken as a sample, given they were a significant number to represent the population. An adaptation of the ?DEMEVI? questionnaire (Delgado 1998) was administered, considering that this questionnaire has been validated and successfully used on several occasions. The research showed that the middle and secondary school teachers of Totarco Dinde school of the Municipality of Coyaima in the Department of Tolima have a mixture of teaching styles; there is a sample of practices related to the six (6) teaching styles posed by Delgado (1991). In short, the six (6) teaching styles are present in the school, being the creative style the most commonly found, followed by the socializer style. It is recommended to complement the work done with a research study that includes an observation instrument that allows to cross results and thus confirm that in practice, teachers are applying styles according to the results of this research. Keywords: Teachers? teaching styles, teaching styles, Teacher?s style, Totarco Dinde

Male depression risk, psychological distress, and psychotherapy uptake: Validation of the German version of the male depression risk scale

Background Screening for depressive disorders in men may be complicated by traditional male role norms. The Male Depression Risk Scale (MDRS) was developed to aid screening for depression in men adhering to traditional male role norms and to facilitate identification of depression in men in general and to promote treatment uptake. Aims Validation of a German version of the MDRS and examination of its potential to predict clinical characteristics. Methods In an anonymous online survey comprising of 1605 participants (male: N = 671; 42%), information was obtained on psychological distress, diagnosed psychological disorders, psychotherapy and psychopharmacological treatment. Additional measures included a German version of the MDRS as further mental-health-related constructs. Results The German version of the MDRS showed good validity and reliability. The previously identified 6-factor structure could be replicated for the German version. Compared to the Patient Health Questionnaire 9, the MDRS showed similar detection performance in identifying men who self-reported psychological distress, psychological disorders, depression, psychotherapy usage, or usage of psychopharmacological therapy. Conclusions The German version of the MDRS shows good psychometric validity and represents a valid screening instrument for the identification of psychological distress specifically in men

Angiogenic gene expression and vascular density are reflected in ultrasonographic features of synovitis in early Rheumatoid Arthritis: an observational study.

INTRODUCTION: Neovascularization contributes to the development of sustained synovial inflammation in the early stages of Rheumatoid Arthritis. Ultrasound (US) provides an indirect method of assessing synovial blood flow and has been shown to correlate with clinical disease activity in patients with Rheumatoid Arthritis. This study examines the relationship of US determined synovitis with synovial vascularity, angiogenic/lymphangiogenic factors and cellular mediators of inflammation in a cohort of patients with early Rheumatoid Arthritis (RA) patients prior to therapeutic intervention with disease modifying therapy or corticosteroids. METHODS: An ultrasound guided synovial biopsy of the supra-patella pouch was performed in 12 patients with early RA prior to treatment. Clinical, US and biochemical assessments were undertaken prior to the procedure. Ultrasound images and histological samples were obtained from the supra-patella pouch. Histological samples were stained for Factor VIII and a-SMA (a-smooth muscle actin). Using digital imaging analysis a vascular area score was recorded. QT-PCR (quantitative-PCR) of samples provided quantification of angiogenic and lymphangiogenic gene expression and immunohistochemistry stained tissue was scored for macrophage, T cell and B cell infiltration using an existing semi-quantitative score. RESULTS: Power Doppler showed a good correlation with histological vascular area (Spearman r--0.73) and angiogenic factors such as vascular endothelial growth factor-A (VEGF-A), Angiopoietin 2 and Tie-2. In addition, lymphangiogenic factors such as VEGF-C and VEGF-R3 correlated well with US assessment of synovitis. A significant correlation was also found between power Doppler and synovial thickness, pro-inflammatory cytokines and sub-lining macrophage infiltrate. Within the supra-patella pouch there was no significant difference in US findings, gene expression or inflammatory cell infiltrate between any regions of synovium biopsied. CONCLUSION: Ultrasound assessment of synovial tissue faithfully reflects synovial vascularity. Both grey scale and power Doppler synovitis in early RA patients correlate with a pro-angiogenic and lymphangiogenic gene expression profile. In early RA both grey scale and power Doppler synovitis are associated with a pro-inflammatory cellular and cytokine profile providing considerable validity in its use as an objective assessment of synovial inflammation in clinical practice

Distributed coherent manipulation of qutrits by virtual excitation processes

We propose a scheme for the deterministic coherent manipulation of two atomic qutrits, trapped in separate cavities coupled through a short optical fibre or optical resonator. We study such a system in the regime of dispersive atom-field interactions, where the dynamics of atoms, cavities and fibre operates through virtual population of both the atomic excited states and photonic states in the cavities and fibre. We show that the resulting effective dynamics allows for the creation of robust qutrit entanglement, and thoroughly investigate the influence of imperfections and dissipation, due to atomic spontaneous emission and photon leakage, on the entanglement of the two qutrits state.Comment: 15 pages, 4 figure

Bitwise Bell inequality violations for an entangled state involving 2N ions

Following on from previous work [J. A. Larsson, Phys. Rev. A 67, 022108 (2003)], Bell inequalities based on correlations between binary digits are considered for a particular entangled state involving 2N trapped ions. These inequalities involve applying displacement operations to half of the ions and then measuring correlations between pairs of corresponding bits in the binary representations of the number of centre-of-mass phonons of N particular ions. It is shown that the state violates the inequalities and thus displays nonclassical correlations. It is also demonstrated that it violates a Bell inequality when the displacements are replaced by squeezing operations.Comment: 12 pages, 5 figures, accepted for publication in Phys. Rev.

Fresnel Representation of the Wigner Function: An Operational Approach

We present an operational definition of the Wigner function. Our method relies on the Fresnel transform of measured Rabi oscillations and applies to motional states of trapped atoms as well as to field states in cavities. We illustrate this technique using data from recent experiments in ion traps [D. M. Meekhof et al., Phys. Rev. Lett. 76, 1796 (1996)] and in cavity QED [B. Varcoe et al., Nature 403, 743 (2000)]. The values of the Wigner functions of the underlying states at the origin of phase space are W(0)=+1.75 for the vibrational ground state and W(0)=-1.4 for the one-photon number state. We generalize this method to wave packets in arbitrary potentials.Comment: 4 pages include 4 figures, submitted to PR