Single Particle and Fermi Liquid Properties of He-3/--He-4 Mixtures: A Microscopic Analysis

We calculate microscopically the properties of the dilute He-3 component in a He-3/--He-4 mixture. These depend on both, the dominant interaction between the impurity atom and the background, and the Fermi liquid contribution due to the interaction between the constituents of the He-3 component. We first calculate the dynamic structure function of a He-3 impurity atom moving in He-3. From that we obtain the excitation spectrum and the momentum dependent effective mass. The pole strength of this excitation mode is strongly reduced from the free particle value in agreement with experiments; part of the strength is distributed over high frequency excitations. Above k > 1.7$\AA$^{-1}$ the motion of the impurity is damped due to the decay into a roton and a low energy impurity mode. Next we determine the Fermi--Liquid interaction between He-4 atoms and calculate the pressure-- and concentration dependence of the effective mass, magnetic susceptibility, and the He-3--He-3 scattering phase shifts. The calculations are based on a dynamic theory that uses, as input, effective interactions provided by the Fermi hypernetted--chain theory. The relationship between both theories is discussed. Our theoretical effective masses agree well with recent measurements by Yorozu et al. (Phys. Rev. B 48, 9660 (1993)) as well as those by R. Simons and R. M. Mueller (Czekoslowak Journal of Physics Suppl. 46, 201 (1996)), but our analysis suggests a new extrapolation to the zero-concentration limit. With that effective mass we also find a good agreement with the measured Landau parameter F_0^a.Comment: 47 pages, 15 figure

Spatio-temporal gait analysis based on human-smart rollator interaction

The ability to walk is typically related to several biomechanical components that are involved in the gait cycle (or stride), including free mobility of joints, particularly in the legs; coordination of muscle activity in terms of timing and intensity; and normal sensory input, such as vision and vestibular system. As people age, they tend to slow their gait speed, and their balance is also affected. Also, the retirement from the working life and the consequent reduction of physical and social activity contribute to the increased incidence of falls in older adults. Moreover, older adults suffer different kinds of cognitive decline, such as dementia or attention problems, which also accentuate gait disorders and its consequences. In this paper we present a methodology for gait identification using the on-board sensors of a smart rollator: the i-Walker. This technique provides the number of steps performed in walking exercises, as well as the time and distance travelled for each stride. It also allows to extract spatio-temporal metrics used in medical gait analysis from the interpretation of the interaction between the individual and the i-Walker. In addition, two metrics to assess users’ driving skills, laterality and directivity, are proposed.Peer ReviewedPostprint (author's final draft

Concentration Dependence of the Effective Mass of He-3 Atoms in He-3/He-4 Mixtures

Recent measurements by Yorozu et al. (S. Yorozu, H. Fukuyama, and H. Ishimoto, Phys. Rev. B 48, 9660 (1993)) as well as by Simons and Mueller (R. Simons and R. M. Mueller, Czhechoslowak Journal of Physics Suppl. 46, 201 (1976)) have determined the effective mass of He-3 atoms in a He-3/He-4 mixture with great accuracy. We here report theoretical calculations for the dependence of that effective mass on the He-3 concentration. Using correlated basis functions perturbation theory to infinite order to compute effective interactions in the appropriate channels, we obtain good agreement between theory and experiment.Comment: 4 pages, 1 figur

Orientation cues for high-flying nocturnal insect migrants: do turbulence-induced temperature and velocity fluctuations indicate the mean wind flow?

Migratory insects flying at high altitude at night often show a degree of common alignment, sometimes with quite small angular dispersions around the mean. The observed orientation directions are often close to the downwind direction and this would seemingly be adaptive in that large insects could add their self-propelled speed to the wind speed, thus maximising their displacement in a given time. There are increasing indications that high-altitude orientation may be maintained by some intrinsic property of the wind rather than by visual perception of relative ground movement. Therefore, we first examined whether migrating insects could deduce the mean wind direction from the turbulent fluctuations in temperature. Within the atmospheric boundary-layer, temperature records show characteristic ramp-cliff structures, and insects flying downwind would move through these ramps whilst those flying crosswind would not. However, analysis of vertical-looking radar data on the common orientations of nocturnally migrating insects in the UK produced no evidence that the migrants actually use temperature ramps as orientation cues. This suggests that insects rely on turbulent velocity and acceleration cues, and refocuses attention on how these can be detected, especially as small-scale turbulence is usually held to be directionally invariant (isotropic). In the second part of the paper we present a theoretical analysis and simulations showing that velocity fluctuations and accelerations felt by an insect are predicted to be anisotropic even when the small-scale turbulence (measured at a fixed point or along the trajectory of a fluid-particle) is isotropic. Our results thus provide further evidence that insects do indeed use turbulent velocity and acceleration cues as indicators of the mean wind direction

DEVELOPMENT OF HIGH-BRIGHTNESS FEMTOSECOND X-RAY SOURCE

Abstract A high-brightness femtosecond X-ray source, based on Thomson scattering of a low-emittance electron beam with a femtosecond pulse laser at a 90-degree interaction configuration, has been developed and will be expected for the study of ultra-fast structural dynamics of materials. The electron beam was generated by a laser-driven photocathode RF gun and accelerated up to 14MeV with a linac. A 270fs pulse X-rays with a peak energy of 2.3keV were achieved experimentally in the interaction of a 3ps electron bunch with a 100fs Ti:Sapphire laser light. The intensity of the X-rays was obtained to be 1.4x10 4 /pulse under the experimental conditions of a 0.5nC electron bunch and a 100mJ laser pulse energy. The stability of the X-ray intensity was obtained to be 25%(rms)

Spatial profile measurement of femtosecond laser - Compton xrays

Abstract A femtosecond X-ray source was developed by Thomson scattering through interaction between a lowemittance picosecond electron beam and a terawatt femtosecond laser light at 90 o configuration. The observed X-ray intensity with peak energy of 2.3 keV and pulse duration of 270 fs rms was typically 1.4x10 4 photons/pulse. The pulse-to-pulse fluctuation of the X-ray intensity was measured to be 25%. The spatial profile of the X-rays was measured with a technique of X-ray imaging on a phosphor screen using an image-intensified CCD camera. The dependence of the X-ray beam profile on the scattering laser polarization was obtained and compared with theoretical analysis. INTRODUCATION A short pulse X-ray source is an important tool for studying the dynamics of the materials in the fundamental time scale. The development of femtosecond laser has made it possible to generate such ultrashort X-ray pulses in femtosecond region by means of 90-degree (90 o ) Thomson scattering with a relativistic ultrashort-pulse electron beam The intensity of the X-rays generated in Thomson scattering is proportional to the densities of both the electron and laser beam. It is important to tightly focus both the beams in the transverse direction to generate high-brightness X-rays. In addition, the small focused beam size should be required to reduce the interaction time in 90 o Thomson scattering for the generation of femtosecond X-ray pulse EXPERIMENTAL ARRANGEMENT The Thomson femtosecond X-ray source was consisted of a picosecond electron source and a tabletop terawatt femtosecond pulse laser An Electron Source The electron beam was produced by a S-band (2856 MHz) photocathode rf gun. The rf gun, which was constructed under the BNL/KEK/SHI collaboration [6], was consisted of two cells: a half cell and a full cell. A copper cathode was located on the side of the half cell. The length of the half cell was designed to be 0.6 times of the full cell length to reduce the beam divergence. At the exit of the rf gun, a single solenoid magnet was mounted for space-charge emittance compensation. The rf gun was driven by an all solid-state LD-pumped Nd:YAG picosecond laser. The laser was consisted of a passive mode-locked oscillator, a regenerative amplifier, a post amplifier and a frequency converter. The oscillator was phase-locked with a frequency of 119 MHz, the 24 th sub-harmonic of the accelerating 2856 MHz rf, by dynamically adjusting the cavity length of the oscillator with a semiconductor saturable absorber mirror controlled by a timing stabilizer. The output of the oscillator was amplified the pulse energy up to 2mJ in the regenerative amplifier and the post amplifier. The amplified laser pulse was frequency quadrupled to 262 nm ultraviolet (UV) light by a pair of frequency conversion crystals. The UV light was injected on the cathode surface at an incident angle of 68 o along the electron beam direction. The electron beam produced from the rf gun was accelerated with a 70 cm long standing-wave linear accelerator (linac) produced with an alternating-periodic structure. The linac is located at a position of 1.2 m from the cathode. The input rf peak power of both the rf gun and the linac was 7.5 MW that was produced with a 15 MW Klystron. The peak electric fields on axis in the rf gun and the linac were approximately 100 and 25 MV/m, respectively. The repetition rate of the operation was 10 Hz in the experiments. The accelerated electron beam was focused at the interaction point for scattering with the laser light by a triplet quadrupole magnet downstream of the linac. The scattered electrons were bended by a 90 o dipole magnet A Terawatt Femtosecond Laser The terawatt femtosecond laser was consisted of a mode-locked Ti:Sapphire laser oscillator, a pulse stretcher, a regenerative amplifier, a multi-pass post amplifier, and a pulse compressor. The oscillator generated 50 fs pulses at the repetition rate of 119 MHz. The frequency of the laser oscillator was phase-locked with the 119 MHz rf by the same method as the driving laser of the rf gun. ___________________________________________

Stereodifferentiation in the formation and decay of the encounter complex in bimolecular electron transfer with photoactivated acceptors

Experimental evidence has been obtained for the involvement of encounter complexes between both enantiomers of a π,π* triplet excited ketone and a chiral phenol or indole. Determination of the pre-equilibrium constants (KEC) and the intrinsic decay rate constants (kd) indicates a significant stereodifferentiation in both steps of the quenching process.Perez Prieto, Julia, [email protected] ; Galian, Raquel Eugenia, [email protected] ; Morant Miñana, Maria Carmen, [email protected]

Comunidades en acción : aprendizaje a lo largo de toda la vida para el desarrollo sostenible

El objetivo de este manual es servir de guía informativa básica para funcionarios gubernamentales de nivel nacional y municipal, y para las personas que trabajan con centros de aprendizaje comunitario (CAC) y otras organizaciones basadas en la comunidad. Lo que se pretende es establecer lazos más sólidos a fin de mejorar la calidad de la educación comunitaria para el desarrollo sostenible (EDS). Al estrecharse los vínculos entre los socios se contribuye a fomentar la EDS a nivel comunitario, brindando oportunidades de aprendizaje no formal e informal, con el objetivo último de alcanzar el desarrollo sostenible. Más de 700 participantes —entre ellos educadores comunitarios, investigadores y representantes de gobiernos, de agencias de las Naciones Unidas y de organizaciones de desarrollo— se congregaron con ocasión de la Conferencia Internacional Kominkan-CAC sobre Educación para el Desarrollo Sostenible, celebrada en la ciudad de Okayama, Japón, entre el 9 y el 12 de octubre de 2014. Los participantes debatieron sobre cómo mantener en el tiempo y promover la EDS mediante el aprendizaje basado en la comunidad, aprovechando la vasta experiencia adquirida en esta área gracias al trabajo junto a las comunidades locales. El principal resultado de la conferencia fue el Compromiso de Okayama 2014: Promoción de la EDS más allá del DEDS a través de aprendizaje basado en las comunidades, un documento que destaca las importantes aportaciones del aprendizaje comunitario durante el DEDS (2005-2014), y especifica los compromisos para continuar fomentando la práctica de la EDS. (En el Anexo se incluye el texto completo del Compromiso de Okayama). Este manual se enmarca en el contexto del Compromiso de Okayama 2014. Su objetivo es garantizar que dicho compromiso no se transforme en un documento estático, sino que continúe sirviendo de referencia para los profesionales dedicados a la EDS comunitaria, a fin de alcanzar los objetivos de desarrollo sostenible para 2030, que fueron acordados por la comunidad mundial en 2015. El manual consta de tres partes: panorama mundial, estudios de casos y resumen. En la primera parte se dan a conocer a los lectores los conceptos y los marcos normativos fundamentales que sirven de referencia para la práctica de la EDS comunitaria. Se responde a las siguientes preguntas clave: (1) ¿Qué es el desarrollo sostenible? (2) ¿Qué es la Educación para el Desarrollo Sostenible (EDS)? (3) ¿Por qué es importante adoptar un enfoque comunitario para el desarrollo sostenible y la EDS? (4) ¿De qué manera se vincula la EDS comunitaria con los actuales debates mundiales sobre los Objetivos de Desarrollo Sostenible y el Programa de Acción Mundial (PAM) sobre la Educación para el Desarrollo Sostenible? (5) ¿Qué son los centros de aprendizaje comunitario (CAC) y las organizaciones comunitarias, y cuál es su labor? En la segunda parte se analizan más detalladamente los conceptos y los marcos de referencia mencionados en la primera parte, y se dan a conocer breves estudios de casos sobre prácticas y políticas que describen una amplia gama de modalidades de EDS basadas en la comunidad, e identifican los mecanismos asociados a políticas que respaldan estas iniciativas de enseñanza en todo el mundo. Los casos basados en actividades comunitarias fueron escogidos en función de cinco cuestiones temáticas destacadas en el Compromiso de Okayama 2014, a saber: i) Conservación del medio ambiente. ii) Reducción del riesgo de desastres (RRD). iii) Generación de ingresos, espíritu emprendedor, desarrollo comunitario. iv) Diversidad cultural y diálogo, intercambio intergeneracional. v) Alfabetización. vi) Empoderamiento

Drosophila TRPN( = NOMPC) Channel Localizes to the Distal End of Mechanosensory Cilia

BACKGROUND: A TRPN channel protein is essential for sensory transduction in insect mechanosensory neurons and in vertebrate hair cells. The Drosophila TRPN homolog, NOMPC, is required to generate mechanoreceptor potentials and currents in tactile bristles. NOMPC is also required, together with a TRPV channel, for transduction by chordotonal neurons of the fly's antennal ear, but the TRPN or TRPV channels have distinct roles in transduction and in regulating active antennal mechanics. The evidence suggests that NOMPC is a primary mechanotransducer channel, but its subcellular location-key for understanding its exact role in transduction-has not yet been established. METHODOLOGY/PRINCIPAL FINDINGS: Here, by immunostaining, we locate NOMPC at the tips of mechanosensory cilia in both external and chordotonal sensory neurons, as predicted for a mechanotransducer channel. In chordotonal neurons, the TRPN and TRPV channels are respectively segregated into distal and proximal ciliary zones. This zonal separation is demarcated by and requires the ciliary dilation, an intraciliary assembly of intraflagellar transport (IFT) proteins. CONCLUSIONS: Our results provide a strong evidence for NOMPC as a primary transduction channel in Drosophila mechansensory organs. The data also reveals a structural basis for the model of auditory chordotonal transduction in which the TRPN and TRPV channels play sequential roles in generating and amplifying the receptor potential, but have opposing roles in regulating active ciliary motility

Upregulation of AEBP1 in endothelial cells promotes tumor angiogenesis in colorectal cancer

血管新生は大腸がんの重要な治療標的である．本論文では，大腸がんの腫瘍血管関連遺伝子を探索し，AEBP1（Adipocyte enhancer binding protein 1）の血管内皮細胞における高発現を同定し，AEBP1が腫瘍血管新生促進に働くことを明らかにした