Channeling of Electrons in a Crossed Laser Field

In this article a new analytical description of the effective interaction potential for a charged particle in the field of two interfering laser beams is presented. The potential dependence on the lasers intensities, orientation and parameters of the particle entering the considered system is analyzed. It is shown for the case of arbitrary lasers crossing angle that for different values of projectile velocity the attracting potential becomes a scattering one so that the channel axes and borders interchange each other. In addition the projectile radiation spectral distribution is given and general estimations on the expected beam radiation yield are outlined

Relativistic charged particle ejection from optical lattice

We have analyzed relativistic (∼ MeV) electron ejection from potential channels of standing laser wave taking into account both rapid and averaged oscillations within the region of declining field of standing wave. We show that only a few last rapid oscillations can define transverse speed and, therefore, angle at which a particle leaves standing wave. This conclusion might drastically simplify numerical simulations of charged particles channeling and accompanying radiation in crossed lasers field. Moreover, it might provide a valuable information for estimation of charged particle beams parameters after their interaction with finite standing wave

On a quantum particle in laser channels

In this paper the effective potential describing interaction of a scalar quantum particle with arbitrary nonuniform laser field is derived for a wide spectrum of the particle energies. The presented method allows to take into account all the features of the effective potential for a scalar particle. The derived expression for effective potential for quantum particle has the same form as the one presented earlier for a classical particle. A special case for channeling of a quantum particle as well as accompanying channeling radiation in a field formed by two crossed plane laser waves is considered. It is shown that relativistic particles moving near the laser channel bottom should be examined as quantum ones at both arbitrarily large longitudinal energies and laser fields of accessible intensities

Spectral distribution of SPARC photoinjector electrons

SPARC is a photo-injector for production of high-brightness lowemittance electron beams to drive a FEL experiment in various configurations, including SASE-FEL radiation of 1–10nm (SPARCX project). Due to a high-brightness source, the SPARC facility can be used to study the physics of ultrashort beams, plasma-wave based acceleration, production of X-rays by means of Compton backscattering, channeling of electron beams and other experiments. The initial process of electron beam generation inside the RF gun determines the main parameters of the electron beam. Interaction of electrons with high-frequency laser beam leads to modulation of the electron beam. In this paper we present electron beam spectral distribution for SPARC photoinjector parameters. The estimate of electron beam energy loss for such electron distribution also is given

Meaning interventions in schools: Strategies for supporting healthy development and wellbeing in the lives of youth

Human beings inherently make meaning of the world, interpreting themselves in context and utilizing these representations to determine what to think, how to feel, and in what way to act. Developing meaning in life appears to be a highly nuanced, personal journey and yet, research suggests that those who experience their lives as meaningful enjoy multiple physical and psychological benefits and are protected from various health risks. Beyond establishing a firm sense that life is meaningful, studies suggest that people of all ages who can ‘make meaning’ of their experiences, especially difficult experiences, may be protected from developing some mental and physical health concerns. Childhood and adolescence may be pivotal periods for the development of this well-being resource, and school offers an especially promising context for fostering meaning. Yet, there have been few articles that have explored how meaning and meaning-making can be woven into the school day. The current article attempts to address this gap in the literature by defining meaning and meaning-making, discussing the relevance of meaning from a developmental framework, and offering suggestions for applications for teachers and providers during the school day

Experimental study of contact angle and surface energy of a single aramid fibre and its relation on frictional behaviour of fibre-fibre contact

Surface energy has a significant impact on the adhesion and friction behaviour of fibres in composite materials. Finding the surface energy of a single fibre, on the other hand, maybe challenging. In this work, the surface energy of single aramid fibre is calculated using dynamic contact angle measurements. The contact angles of three different types of Twaron® aramid fibres with varying treated materials and thicknesses are tested in a series of test liquids. As a result of the changing surface characteristics of the fibre, the surface energy of treated fibre is found to be approximately 37% greater than that of untreated fibre. The thickness of the fibre also affects its surface energy because thicker fibres have a larger contact area, which increases surface energy in the region of contact. At specific applied normal load conditions, it can be found that the coefficient of friction increased as the total surface energy in the area of the contact interface increased.</p

High singleton live birth rate following classical ovulation induction in normogonadotrophic anovulatory infertility (WHO 2)

BACKGROUND: Medical induction of ovulation using clomiphene citrate (CC) as first line and exogenous gonadotrophins as second line forms the classical treatment algorithm in normogonadotrophic anovulatory infertility. Because the chances of success following classical ovulation induction are not well established, a shift in first-line therapy can be observed towards alternative treatment. The study aim was to: (i) reliably assess the probability of singleton live birth following classical induction of ovulation; and (ii) construct a prediction model, based on individual patient characteristics assessed upon standardized initial screening, to help identify patients with poor chances of success. METHODS: A total of 240 consecutive women visiting a specialist academic fertility unit with a history of infertility, oligomenorrhoea or amenorrhoea, and normal FSH and estradiol serum concentrations (WHO group 2) was prospectively followed. The women had not been previously treated with ovulation-inducing agents. All patients commenced with CC. Patients who did not ovulate within three treatment cycles of incremental daily doses up to 150 mg for 5 consecutive days or ovulatory CC patients who did not conceive within six cycles, subsequently underwent gonadotrophin induction of ovulation applying a step-down dose regimen. The main outcome measure was pregnancy resulting in singleton live birth. Cox regression was used to construct a multivariable prediction model. RESULTS: Overall, there were 134 pregnancies ending in a singleton live birth (56% of women). The cumulative pregnancy rate after 12 and 24 months of follow-up was 50% and 71% respectively. Polycystic ovary syndrome (PCOS) patients (49%), clearly non-PCOS patients (13%) and the in-between group did not differ in prognosis (P = 0.9). The multivariable Cox regression model contained the woman's age, the insulin:glucose ratio and duration of infertility. With a cut-off value of 30% for low chance, the model predicted probabilities at 12 months lower than this cut-off for 25 out of 240 patients (10.4%). CONCLUSIONS: Classical ovulation induction produces very good results in normogonadotrophic anovulatory infertility. Alternative treatment options may not be indicated as first-line therapy in these patients, except for subgroups with poor prognosis. These women can be identified by older age, longer duration of infertility and higher insulin:glucose ratio

Experimental violation of a spin-1 Bell inequality using maximally-entangled four-photon states

We demonstrate the first experimental violation of a spin-1 Bell inequality. The spin-1 inequality is a calculation based on the Clauser, Horne, Shimony and Holt formalism. For entangled spin-1 particles the maximum quantum mechanical prediction is 2.552 as opposed to a maximum of 2, predicted using local hidden variables. We obtained an experimental value of 2.27 $\pm 0.02$ using the four-photon state generated by pulsed, type-II, stimulated parametric down-conversion. This is a violation of the spin-1 Bell inequality by more than 13 standard deviations.Comment: 5 pages, 3 figures, Revtex4. Problem with figures resolve