24,149 research outputs found
Line versus Flux Statistics -- Considerations for the Low Redshift Lyman-alpha Forest
The flux/transmission power spectrum has become a popular statistical tool in
studies of the high redshift () Lyman-alpha forest. At low redshifts,
where the forest has thinned out into a series of well-isolated absorption
lines, the motivation for flux statistics is less obvious. Here, we study the
relative merits of flux versus line correlations, and derive a simple condition
under which one is favored over the other on purely statistical grounds.
Systematic errors probably play an important role in this discussion, and they
are outlined as well.Comment: 6 pages, to appear in "The IGM/Galaxy Connection: The Distribution of
Baryons at z=0", eds. J. L. Rosenberg and M. E. Putma
Slow light in paraffin-coated Rb vapor cells
We present preliminary results from an experimental study of slow light in
anti-relaxation-coated Rb vapor cells, and describe the construction and
testing of such cells. The slow ground state decoherence rate allowed by coated
cell walls leads to a dual-structured electromagnetically induced transparency
(EIT) spectrum with a very narrow (<100 Hz) transparency peak on top of a broad
pedestal. Such dual-structure EIT permits optical probe pulses to propagate
with greatly reduced group velocity on two time scales. We discuss ongoing
efforts to optimize the pulse delay in such coated cell systems.Comment: 6 pages, 6 figures, submitted to Journal of Modern Optic
The PML-RAR alpha transcript in long-term follow-up of acute promyelocytic leukemia patients
Background and Objectives. Detection of PML-RAR alpha transcripts by RT-PCR is now established as a rapid and sensitive method for diagnosis of acute promyelocytic leukemia (APL), Although the majority of patients in longterm clinical remission are negative by consecutive reverse transcription polymerase chain reaction (RT-PCR) assays, negative tests are still observed in patients who ultimately relapse. Conversion from negative to positive PCR has been observed after consolidation and found to be a much stronger predictor of relapse. This study reports on 47 APL patients to determine the correlation between minimal residual disease (MRD) status and clinical outcome in our cohort of patients. Design and Methods. The presence of PML-RAR alpha t transcripts was investigated in 47 APL patients (37 adults and 10 children) using a semi-nested reverse transcriptase-polymerase chain reaction to evaluate the prognostic value of RT-PCR tests. Results. All patients achieved complete clinical remission (CCR) following induction treatment with all-trans retinoic acid (ATRA) and chemotherapy (CHT) or ATRA alone. Patients were followed up between 2 and 117.6 months (median: 37 months). Relapses occurred in 11 patients (9 adults and 2 children) between 11.4 and 19 months after diagnosis (median: 15.1 months) while 36 patients (28 adults and 8 children) remained in CCR, Seventy-five percent of patients carried the PML-RARa long isoform (bcr 1/2) which also predominated among the relapsed cases (9 of 11) but did not associate with any adverse outcome (p = 0.37), For the purpose of this analysis, minimal residual disease tests were clustered into four time-intervals: 0-2 months, 3-5 months, 5-9 months and 10-24 months. Interpretation and Conclusions. Children showed persisting disease for longer than adults during the first 2 months of treatment, At 2 months, 10 (50%) of 20 patients who remained in CCR and 4 (80%) of 5 patients who subsequently relapsed were positive. Patients who remained in CCR had repeatedly negative results beyond 5.5 months from diagnosis. A positive MRD test preceded relapse in 3 of 4 tested patients. The ability of a negative test to predict CCR (predictive negative value, PNV) was greater after 6 months (> 83%), while the ability of a positive test to predict relapse (predictive positive value, PPV) was most valuable only beyond 10 months (100%). This study (i) highlights the prognostic value of RT-PCR monitoring after treatment of APL patients but only from the end of treatment, (ii) shows an association between conversion to a positive test and relapse and (iii) suggests that PCR assessments should be carried out at 3-month intervals to provide a more accurate prediction of hematologic relapses but only after the end of treatment, (C) 2001, Ferrata Storti Foundatio
Local well-posedness for the nonlinear Schr\"odinger equation in the intersection of modulation spaces
We introduce a Littlewood-Paley characterization of modulation spaces and use
it to give an alternative proof of the algebra property, somehow implicitly
contained in Sugimoto (2011), of the intersection for , and
. We employ this algebra property to show the local well-posedness of
the Cauchy problem for the cubic nonlinear Schr\"odinger equation in the above
intersection. This improves Theorem 1.1 by B\'enyi and Okoudjou (2009), where
only the case is considered, and closes a gap in the literature. If and or if and then
and the
above intersection is superfluous. For this case we also reobtain a
H\"older-type inequality for modulation spaces.Comment: 14 page
Suivi ecologique du groupe de gorille ââBukaââ en cours dâhabituation a la presence humaine en vue de sa promotion ecotouristique
LâhumanitĂ© est en quĂȘte de modĂšles dâexploitation durables des ressources naturelles. Câest dans cette optique que se dĂ©veloppe depuis plusieurs annĂ©es,la notion dâĂ©cotourisme. Celle-ci paraĂźt ĂȘtre un remĂšdeĂ la difficile conciliation des enjeux de la conservation, dâune part et du dĂ©veloppement, dâautre part, surtout autour des grands singes, notamment les Gorilles qui constituent un groupe zoologique dâun grand attrait touristique. Conscient de cet enjeu, nous avons menĂ© au Centre de Recherche Mondika, pendant neuf mois, une Ă©tude portant sur le suivi Ă©cologique du groupe de Gorilles nommĂ© ââBukaââ en cours dâhabituation Ă la prĂ©sence humaine en vue de connaĂźtre son rythme circadien (rythme biologique pendant une pĂ©riode dâenviron 24 h). Les objectifs spĂ©cifiques se rĂ©sument Ă identifier les diffĂ©rentes activitĂ©s du groupe, leurs frĂ©quences dâapparition et leurs variations au cours de la journĂ©e, Ă dĂ©terminer les meilleurs moments pour lâobservation du groupe, Ă Ă©valuer la durĂ©e de marche du groupe et ses variations au cours de la journĂ©e.Pour atteindre ces objectifs, nous avons procĂ©dĂ© Ă la recherche documentaire singuliĂšrement sur lâĂ©thologie des gorilles et Ă la rĂ©colte de donnĂ©es qualitative et quantitative de terrain, suivant la mĂ©thode de Masi et al. (2008). Les rĂ©sultats de cette Ă©tude montrent que lâalimentation constitue lâessentiel des activitĂ©s du groupe ââBukaââ. En effet, on note la prĂ©dominance de la rĂ©alisation de lâactivitĂ© alimentaire (A) pendant toute la journĂ©e, avec des pics le matin (de 7 Ă 9 h) et le soir Ă partir de 17 h. Lâalimentation est suivie par des pics de pourcentages de locomotion (L) le matin (de 9 Ă 11 h) et le soir (de 15 Ă 17 h). Lâamusement et le tambourinage sur la poitrine constituent les activitĂ©s sociales les plus menĂ©es. Les fruits et les feuilles sont les aliments les plus consommĂ©s. Les heures allant de 10 Ă 15 h sont celles pendant lesquelles le groupe ââBukaââ est plus visible dans son habitat. Enfin, la pĂ©riode allant de fin aoĂ»t Ă fin octobre est celle pendant laquelle la durĂ©e de marche pour contacter le groupe ââBukaââ est la plus courte.Mots clĂ©s : Ecotourisme, Gorille, attrait touristique, rythme circadien, groupe Buka
Synthesis, optical properties and applications of red/near-infrared carbon dots
Compared to inorganic quantum dots, fluorescent carbon nanomaterials (C-dots) have gained significant attention because of their unique optoelectrical properties and low toxicity. Although many review articles summarized the last research achievements, only a few of them are focusing on red/near-infrared C-dots. Due to their unique optical and optoelectrical properties in the red/near-infrared region, this interesting subclass of C-dots may be applied as important building blocks for several applications spanning from bioimaging and nano-thermometry, to luminescent solar concentrators (LSCs) and photoelectrochemical systems. Therefore, in this review the synthesis and the fluorescence mechanism together with the most important applications in thermometry, bio-imaging, LSCs and photocatalysis of red/near-infrared C-dots are considered. Furthermore, another aim is to highlight the available approaches to improve the carbonization degree and, additionally, to discuss the structure/composition correlated optical properties. Finally, outlooks, future perspectives and challenges are also discussed for these highly promising nanostructures
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