Two-photon emission in detuned resonance fluorescence

We discuss two-photon correlations from the side peaks that are formed when a two-level system emitter is driven coherently, with a detuning between the driving source and the emitter (quasi-resonance fluorescence). We do so in the context of the theories of frequency-resolved photon correlations and homodyning, showing that their combination leads to a neat picture compatible with perturbative two-photon scattering that was popular in the early days of quantum electrodynamics. This should help to control, enhance and open new regimes of multiphoton emission. We also propose a way to evidence the quantum coherent nature of the process from photoluminescence only, through the observation of a collapse of the symmetry of the lineshape accompanied by a surge of its intensity of emission. We discuss several of our results in the light of recent experimental works.Comment: 17 pages, 4 figures -- added ideal two-photon cascade formula (Eq. 3), additional references, corrected some typos & other minor changes. Submitted to Quantum Sci. Techno

Professional Transitions in Honors: Challenges, Opportunities, and Tips

Authors reflect on ways that honors practitioners have experienced various professional transitions and provide insights to help others successfully manage such changes. Honors transitions are inevitable. Many of us in honors, for example, have relocated from other disciplines, moving from the prescribed boundaries of our academic areas to the diverse and challenging demands of honors, quickly learning new leadership skills and approaches to navigating challenges and prospects within and outside our institutions. Some of us have relocated to different institutions; some have negotiated growth from programs to colleges; some have advanced to positions in higher administration; some have witnessed changes in directors or deans; some have needed to adjust to the rapid succession of top administrators and their assorted agendas; some have retired. With creative approaches to change, such shifts to new faces, leadership styles, program ideas, and professional priorities can become opportunities rather than obstacles in our professional development in honors. The authors of this piece represent honors professionals who have experienced various transitions, and we offer our reflections and tips to help others in our field to manage such changes successfully

First principles quasiparticle damping rates in bulk lead

First principles calculations of the damping rates (inverse inelastic lifetimes) of low energy quasiparticles in bulk Pb are presented. Damping rates are obtained both for excited electrons and holes with energies up to 8 eV on a set of k vectors throughout the Brillouin zone (BZ). Strong localization effects in the calculated lifetimes are found. Averaged over the BZ inelastic lifetimes versus quasiparticle energy are reported as well. In addition, the effect of the spin-orbit induced splitting in the band structure on the calculated lifetimes in Pb is investigated.Comment: 10 pages, 8 figures, 5 table

Differences in branch characteristics of Scots pine (Pinus sylvestris L.) genetic entries grown at different spacing

• We studied the differences in branch characteristics along the stems of six different genetic entries of 20 year old Scots pines (Pinus sylvestris L.) grown at different spacing (current stand density range 2000–4000 trees ha−1) in central Finland. Furthermore, we studied the phenotypic correlations between yield, wood density traits and branch characteristics. All the genetic entries had Kanerva pine (plus tree S1101) as a father tree, whereas the mother tree represented Finnish plus trees from southern, central and northern Finland. • Spacing affected all yield traits, wood density and living branch characteristics such as relative average branch diameter and relative cumulative branch area (p < 0.05). As a comparison, genetic entry affected height, while origin group (southern, central and northern ones) affected most of the studied traits. Regardless of spacing, the northern origin had, on average, the largest stem diameter and highest wood density, while the central one was the tallest one. Furthermore, average branch diameter along the stem was affected by branch age, origin group and spacing, while average branch angle was affected by branch age and genetic entry (p < 0.05). • In general the average branch size could be decreased especially in lower tree canopy by denser spacing during the early phase of the rotation, but only at the expense of tree growth. Correspondingly differences between origins are mainly related to their differences in stem growth

Enhancement of tribological behavior of rolling bearings by applying a multilayer ZrN/ZrCN coating

This paper focuses on the tribological behaviour of ZrN/ZrCN coating on bearing steel substrates DIN 17230, 100Cr6/1.3505. Coatings are applied at room temperature processes by means of Cathodic Arc Evaporation (CAE), a kind of Physical Vapor Deposition (PVD) technique. In order to achieve a satisfactory compromise between coating-substrate adhesion and the surface roughness requirement of the bearing rings, a polish post-processing is proposed. Different polish post-processing times and conditions are applied. The coated and polished bearing rings are tested under real friction torque test protocols. These tests show that the application of the coating does not entail a significant improvement in friction performance of the bearing. However, fatigue tests in real test bench are pending to evaluate the possible improvement in bearing life time

Loss of antibunching

We describe some of the main external mechanisms that lead to a loss of antibunching, i.e., that spoil the character of a given quantum light to deliver its photons separated from each other. Namely, we consider contamination by noise, a time jitter in the photon detection, and the effect of frequency filtering (or detection with finite bandwidth). The formalism to describe time jitter is derived and connected to the already existing one for frequency filtering. The emission from a two-level system under both incoherent and coherent driving is taken as a particular case of special interest. The coherent case is further separated into its vanishing- (Heitler) and high- (Mollow) driving regimes. We provide analytical solutions which, in the case of filtering, reveal an unsuspected structure in the transitions from perfect antibunching to thermal (incoherent case) or uncorrelated (coherent case) emission. The experimental observations of these basic and fundamental transitions would provide additional compelling evidence of the correctness and importance of the theory of frequency-resolved photon correlation

Prevalencia de candidiasis vaginal en una población obstétrica de bajo riesgo en Santander

ObjetivoConocer la prevalencia de candidiasis vaginal en embarazadas controladas desde atención primaria y ver si está aumentando con el paso del tiempo.DiseñoEstudio descriptivo, retrospectivo del universo de mujeres embarazadas.EmplazamientoZona Básica de Salud Cazoña (34.783 habitantes).SujetosToda la población obstétrica controlada en nuestro centro de salud desde 1992 a 1997, ambos inclusive.Mediciones y resultadosEstudio retrospectivo de las historias clínicas de todas las mujeres embarazadas captadas en nuestro centro de salud (878 embarazos). Descartados los derivados a tocólogo, abortos y partos prematuros, se han valorado 549 embarazos (62,30% del total) normales, de bajo riesgo, controlados hasta el final por atención primaria, con un rango de edad de 16-40 años. La prevalencia media de candidiasis es de un 18% (IC, 15,0-21,6). Su frecuencia aumenta a medida que se incrementa el número de gestaciones y disminuye a medida que aumenta la edad de la embarazada.ConclusionesLa prevalencia encontrada en nuestro estudio es de un 18%, y no está aumentando a medida que pasan los años.ObjectivesTo find the prevalence of vaginal candidiasis in pregnant women monitored through primary care and to see whether it is on the increase.DesignDescriptive and retrospective study of pregnant women.SettingCazoña Health District (34783 inhabitants).SubjectsThe entire obstetric population monitored by our health centre between 1992 and 1997 inclusive.Measurements and resultsRetrospective study of clinical histories of all the pregnant women seen at our health centre (878 pregnancies). After discounting those referred to obstetricians, abortions/ miscarriages and premature births, 549 normal low-risk pregnancies (62.30% of the total) were monitored to completion in primary care. The women's age range was 16 to 40. The mean prevalence of candidiasis was 18% (CI, 15.0-21.6). Its frequency increased as the number of pregnancies increased and dropped as the age of the pregnant women increased.ConclusionsPrevalence found in our study was 18% and did not increase as the years passed