Cooling of a single atom in an optical trap inside a resonator

We present detailed discussions of cooling and trapping mechanisms for an atom in an optical trap inside an optical cavity, as relevant to recent experiments. The interference pattern of cavity QED and trapping fields in space makes the trapping wells distinguishable from one another. This adds considerable flexibility to creating effective trapping and cooling conditions and to detection possibilities. Friction and diffusion coefficients are calculated in and beyond the low excitation limit and full 3-D simulations of the quasiclassical motion of a Cs atom are performed.Comment: One more figure and one more autho

CD4-positive T cells and M2 macrophages dominate the peritoneal infiltrate of patients with encapsulating peritoneal sclerosis

Background: Encapsulating peritoneal sclerosis (EPS) is a severe complication of peritoneal dialysis (PD). Previously, it has been shown that infiltrating CD4-positive T cells and M2 macrophages are associated with several fibrotic conditions. Therefore, the characteristics of the peritoneal cell infiltrate in EPS may be of interest to understand EPS pathogenesis. In this study, we aim to elucidate the composition of the peritoneal cell infiltrate in EPS patients and relate the findings to clinical outcome. Study Design, Setting, and Participants: We studied peritoneal membrane biopsies of 23 EPS patients and compared them to biopsies of 15 PD patients without EPS. The cellular infiltrate was characterized by immunohistochemistry to detect T cells(CD3-positive), CD4-positive (CD4+) and CD8-positive T cell subsets, B cells(CD20-positive), granulocytes(CD15-positive), macrophages(CD68-positive), M1(CD80-positive), and M2(CD163-positive) macrophages. Tissues were analysed using digital image analysis. Kaplan-Meier survival analysis was performed to investigate the survival in the different staining groups. Results: The cellular infiltrate in EPS biopsies was dominated by mononuclear cells. For both CD3 and CD68, the median percentage of area stained was higher in biopsies of EPS as opposed to non-EPS patients (p<0.001). EPS biopsies showed a higher percentage of area stained for CD4 (1.29%(0.61-3.20)) compared to CD8 (0.71%(0.46-1.01), p = 0.04), while in the non-EPS group these cells were almost equally represented (respectively 0.28%(0.05-0.83) versus 0.22%(0.17-0.43), p = 0.97). The percentage of area stained for both CD80 and CD163 was higher in EPS than in non-EPS biopsies (p<0.001), with CD163+cells being the most abundant phenotype. Virtually no CD20-positive and CD15-positive cells were present in biopsies of a subgroup of EPS patients. No relation was found between the composition of the mononuclear cell infiltrate and clinical outcome. Conclusions: A characteristic mononuclear cell infiltrate consisting of CD4+ and CD163+ cells dominates the peritoneum of EPS patients. These findings suggest a role for both CD4+ T cells and M2 macrophages in the pathogenesis of EPS

Limited diversity in natal origins of immature anadromous fish during ocean residency

Author Posting. © The Authors, 2009. This is the author's version of the work. It is posted here by permission of NRC Research Press for personal use, not for redistribution. The definitive version was published in Canadian Journal of Fisheries and Aquatic Sciences. 67 (2010): 1699-1707, doi:10.1139/F10-086.Variable migration patterns can play a significant role in promoting diverse life history traits among populations. However, population and stage specific movement patterns are generally unknown yet crucial aspects of life history strategies in many highly migratory species. We used a natural tag approach using geochemical signatures in otoliths to identify natal origins of one-year-old anadromous American shad (Alosa sapidissima) during ocean residency. Otolith signatures of migrants were compared to a database of baseline signatures from 20 source populations throughout their spawning range. Samples were dominated by fish from only two rivers, while all other potential source populations were nearly or completely absent. These data support the hypothesis that American shad exhibit diverse migratory behaviors and immature individuals from populations throughout the native range do not all mix on northern summer feeding grounds. Rather, our results suggest populations of anadromous fish are distributed heterogeneously at sea in the first year of life and thus may encounter different ocean conditions at a critical early life history stage.This work was funded by National Science Foundation grants OCE-0215905 and OCE-0134998 to SRT and by a WHOI Ocean Life Institute grant to BDW

Kinetic Monte Carlo Simulation of Strained Heteroepitaxial Growth with Intermixing

An efficient method for the simulation of strained heteroepitaxial growth with intermixing using kinetic Monte Carlo is presented. The model used is based on a solid-on-solid bond counting formulation in which elastic effects are incorporated using a ball and spring model. While idealized, this model nevertheless captures many aspects of heteroepitaxial growth, including nucleation, surface diffusion, and long range effects due elastic interaction. The algorithm combines a fast evaluation of the elastic displacement field with an efficient implementation of a rejection-reduced kinetic Monte Carlo based on using upper bounds for the rates. The former is achieved by using a multigrid method for global updates of the displacement field and an expanding box method for local updates. The simulations show the importance of intermixing on the growth of a strained film. Further the method is used to simulate the growth of self-assembled stacked quantum dots

Lack of gene-language correlation due to reciprocal female but directional male admixture in Austronesians and non-Austronesians of East Timor

Nusa Tenggara, including East Timor, located at the crossroad between Island Southeast Asia, Near Oceania, and Australia, are characterized by a complex cultural structure harbouring speakers from two different major linguistic groups of different geographic origins (Austronesian (AN) and non-Austronesian (NAN)). This provides suitable possibilities to study gene-language relationship; however, previous studies from other parts of Nusa Tenggara reported conflicting evidence about gene-language correlation in this region. Aiming to investigate gene-language relationships including sex-mediated aspects in East Timor, we analysed the paternally inherited non-recombining part of the Y chromosome (NRY) and the maternally inherited mitochondrial (mt) DNA in a representative collection of AN-and NAN-speaking groups. Y-SNP (single-nucleotide polymorphism) data were newly generated for 273 samples and combined with previously established Y-STR (short tandem repeat) data of the same samples, and with previously established mtDNA data of 290 different samples with, however, very similar representation of geographic and linguistic coverage of the country. We found NRY and mtDNA haplogroups of previously described putative East/Southeast Asian (E/SEA) and Near Oceanian (NO) origins in both AN and NAN speakers of East Timor, albeit in different proportions, suggesting reciprocal genetic admixture between both linguistic groups for females, but directional admixture for males. Our data underline the dual genetic origin of East Timorese in E/SEA and NO, and highlight that substantial genetic admixtur

Influence of a classical homogeneous gravitational field on dissipative dynamics of the Jaynes-Cummings model with phase damping

In this paper, we study the dissipative dynamics of the Jaynes-Cummings model with phase damping in the presence of a classical homogeneous gravitational field. The model consists of a moving two-level atom simultaneously exposed to the gravitational field and a single-mode traveling radiation field in the presence of the phase damping. We present a quantum treatment of the internal and external dynamics of the atom based on an alternative su(2) dynamical algebraic structure. By making use of the super-operator technique, we obtain the solution of the master equation for the density operator of the quantum system, under the Markovian approximation. Assuming that initially the radiation field is prepared in a Glauber coherent state and the two-level atom is in the excited state, we investigate the influence of gravity on the temporal evolution of collapses and revivals of the atomic population inversion, atomic dipole squeezing, atomic momentum diffusion, photon counting statistics and quadrature squeezing of the radiation field in the presence of phase damping.Comment: 25 pages, 15 figure

All-optical switching and strong coupling using tunable whispering-gallery-mode microresonators

We review our recent work on tunable, ultrahigh quality factor whispering-gallery-mode bottle microresonators and highlight their applications in nonlinear optics and in quantum optics experiments. Our resonators combine ultra-high quality factors of up to Q = 3.6 \times 10^8, a small mode volume, and near-lossless fiber coupling, with a simple and customizable mode structure enabling full tunability. We study, theoretically and experimentally, nonlinear all-optical switching via the Kerr effect when the resonator is operated in an add-drop configuration. This allows us to optically route a single-wavelength cw optical signal between two fiber ports with high efficiency. Finally, we report on progress towards strong coupling of single rubidium atoms to an ultra-high Q mode of an actively stabilized bottle microresonator.Comment: 20 pages, 24 figures. Accepted for publication in Applied Physics B. Changes according to referee suggestions: minor corrections to some figures and captions, clarification of some points in the text, added references, added new paragraph with results on atom-resonator interactio