430 research outputs found

    Venous tumor thrombus from a pelvic osteosarcoma

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    AbstractWe present a case of pelvic osteosarcoma in an 18-year-old woman with a tumor thrombus in the left iliac vein, extending to the inferior vena cava. Tumor thrombus has been rarely described with osteosarcoma, with only 14 cases in the literature

    Assessing data quality in the community health worker (CHW) program in Eastern province, Rwanda

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    Background In order to achieve global development goals, the international community has called for the use of community health workers (CHWs) to deliver important health services. CHWs are routinely collecting large amounts of information. As program managers use these data to monitor and evaluate community-based activities, achieving and maintaining high data quality is critical. Objectives Measuring: 1) data accuracy of household registers compared to household interviews and client records in one district; 2) data reliability of monthly village reports compared to program registers in three districts; and 3) CHW and program factors related to data accuracy and reliability. Methods We used lot quality assurance sampling (LQAS) to determine data quality May 2011- June 2012. We randomly sampled: 1) six CHWs per cell, six households per CHW and classified cells as having ‘poor’ or ‘good’ accuracy for household registers based on five health indicators and a composite one, calculating point estimates by health center; and 2) 19 villages per health center classifying health centers as having ‘poor’ or ‘good’ reliability for village reports for three program indicators and a composite one, calculating point estimates by district. We administered a structured interview to CHWs in three districts measuring CHW and program factors, using logistic regression to measure associations with binary dependent variables data accuracy and reliability. Results Accuracy of household data varied by health center: point estimates were 61-72% for the composite indicator. Data reliability was poor across all districts: point estimates for the composite indicator were 26-60%. CHW having logged a visit to the household in the last month in the household register significantly increased odds of accurate data (OR: 1.71; 95%CI: 1.22, 2.39). The more sick children seen by CHWs significantly worsened data reliability: for four or more sick children versus none, OR: 0.283; 95%CI: 0.180, 0.445. Conclusions Community level data quality is variable in Rwanda, with CHWs generally able to collect data accurately, but not aggregate it correctly due to some program factors. To ensure dependable utilization of information by program managers, we recommend improved supervision and training and LQAS-based routine data quality assessments

    Towards an eficient atomic frequency comb quantum memory

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    We present an efficient photon-echo experiment based on atomic frequency combs [Phys. Rev. A 79, 052329 (2009)]. Echoes containing an energy of up to 35% of that of the input pulse are observed in a Pr3+-doped Y2SiO5 crystal. This material allows for the precise spectral holeburning needed to make a sharp and highly absorbing comb structure. We compare our results with a simple theoretical model with satisfactory agreement. Our results show that atomic frequency combs has the potential for high-efficiency storage of single photons as required in future long-distance communication based on quantum repeaters.Comment: 10 pages, 5 figure

    Spectroscopic investigations of a Ti:Tm:LiNbO3 waveguide for photon-echo quantum memory

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    We report the fabrication and characterization of a Ti4+^{4+}:Tm3+^{3+}:LiNbO3_3 optical waveguide in view of photon-echo quantum memory applications. In particular, we investigated room- and cryogenic-temperature properties via absorption, spectral hole burning, photon echo, and Stark spectroscopy. We found radiative lifetimes of 82 ÎŒ\mus and 2.4 ms for the 3^3H4_4 and 3^3F4_4 levels, respectively, and a 44% branching ratio from the 3^3H4_{4} to the 3^3F4_4 level. We also measured an optical coherence time of 1.6 ÎŒ\mus for the 3^3H6↔3_6\leftrightarrow{}^3H4_4, 795 nm wavelength transition, and investigated the limitation of spectral diffusion to spectral hole burning. Upon application of magnetic fields of a few hundred Gauss, we observed persistent spectral holes with lifetimes up to seconds. Furthermore, we measured a linear Stark shift of 25 kHz⋅\cdotcm/V. Our results are promising for integrated, electro-optical, waveguide quantum memory for photons.Comment: 11 pages, 14 figure

    Dynamics of evaporative cooling in magnetically trapped atomic hydrogen

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    We study the evaporative cooling of magnetically trapped atomic hydrogen on the basis of the kinetic theory of a Bose gas. The dynamics of trapped atoms is described by the coupled differential equations, considering both the evaporation and dipolar spin relaxation processes. The numerical time-evolution calculations quantitatively agree with the recent experiment of Bose-Einstein condensation with atomic hydrogen. It is demonstrated that the balance between evaporative cooling and heating due to dipolar relaxation limits the number of condensates to 9x10^8 and the corresponding condensate fraction to a small value of 4% as observed experimentally.Comment: 5 pages, REVTeX, 3 eps figures, Phys. Rev. A in pres

    A solid state light-matter interface at the single photon level

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    Coherent and reversible mapping of quantum information between light and matter is an important experimental challenge in quantum information science. In particular, it is a decisive milestone for the implementation of quantum networks and quantum repeaters. So far, quantum interfaces between light and atoms have been demonstrated with atomic gases, and with single trapped atoms in cavities. Here we demonstrate the coherent and reversible mapping of a light field with less than one photon per pulse onto an ensemble of 10 millions atoms naturally trapped in a solid. This is achieved by coherently absorbing the light field in a suitably prepared solid state atomic medium. The state of the light is mapped onto collective atomic excitations on an optical transition and stored for a pre-programmed time up of to 1 mu s before being released in a well defined spatio-temporal mode as a result of a collective interference. The coherence of the process is verified by performing an interference experiment with two stored weak pulses with a variable phase relation. Visibilities of more than 95% are obtained, which demonstrates the high coherence of the mapping process at the single photon level. In addition, we show experimentally that our interface allows one to store and retrieve light fields in multiple temporal modes. Our results represent the first observation of collective enhancement at the single photon level in a solid and open the way to multimode solid state quantum memories as a promising alternative to atomic gases.Comment: 5 pages, 5 figures, version submitted on June 27 200

    Seasonal effects on reconciliation in Macaca Fuscata Yakui

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    Dietary composition may have profound effects on the activity budgets, levelof food competition, and social behavior of a species. Similarly, in seasonally breeding species, the mating season is a period in which competition for mating partners increases, affecting amicable social interactions among group members. We analyzed the importance of the mating season and of seasonal variations in dietary composition and food competition on econciliation in wild female Japanese macaques (Macaca fuscata yakui) on Yakushima Island, Japan. Yakushima macaques are appropriate subjects because they are seasonal breeders and their dietary composition significantly changes among the seasons. Though large differences occurred between the summer months and the winter and early spring months in activity budgets and the consumption of the main food sources, i.e., fruits, seeds, and leaves, the level of food competition and conciliatory tendency remained unaffected. Conversely,conciliatory tendency is significantly lower during the mating season than in the nonmating season. Moreover, conciliatory tendency is lower when 1 or both female opponents is in estrous than when they are not. Thus the mating season has profound effects on reconciliation, whereas seasonal changes in activity budgets and dietary composition do not. The detrimental effects of the mating season on female social relationships and reconciliation may be due to the importance of female competition for access to male partners in multimale, multifemale societies

    Increase in immune cell infiltration with progression of oral epithelium from hyperkeratosis to dysplasia and carcinoma

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    In the present study, epithelium derived lesions of various pathological manifestations were examined histologically and immunohistochemically for mononuclear cell infiltration. The infiltrate under the transformed epithelium of oral lesions, was examined for differences in the composition of immune mononuclear cells as the epithelium moves from hyperkeratosis through various degrees of dysplasia to squamous cell carcinoma. The study was performed on 53 human tongue tissues diagnosed as hyperkeratosis (11 cases), mild dysplasia (nine cases), moderate and severe dysplasia (14 cases) and squamous cell carcinoma (19 cases). A similar analysis was performed on 30 parotid gland tissues diagnosed as pleomorphic adenoma (14 cases) and carcinoma ex-pleomorphic adenoma (16 cases). Immunohistochemical analysis of various surface markers of the tumour infiltrating immune cells was performed and correlated with the transformation level as defined by morphology and the expression of p53 in the epithelium. The results revealed that, in the tongue lesions, the changes in the epithelium from normal appearance to transformed were accompanied by a corresponding increase in the infiltration of CD4, CD8, CD14, CD19+20, and HLA/DR positive cells. The most significant change was an increase in B lymphocytes in tongue lesions, that was in accordance with the transformation level (P<0.001). In the salivary gland, a significant number of cases did not show an infiltrate. In cases where an infiltrate was present, a similar pattern was observed and the more malignant tissues exhibited a higher degree of immune cell infiltration
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