736 research outputs found

    An efficient approach to the quantum dynamics and rates of processes induced by natural incoherent light

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    In many important cases, the rate of excitation of a system embedded in an environment is significantly smaller than the internal system relaxation rates. An important example is that of light-induced processes under natural conditions, in which the system is excited by weak, incoherent (e.g., solar) radiation. Simulating the dynamics on the time scale of the excitation source can thus be computationally intractable. Here we describe a method for obtaining the dynamics of quantum systems without directly solving the master equation. We present an algorithm for the numerical implementation of this method, and, as an example, use it to reconstruct the internal conversion dynamics of pyrazine excited by sunlight. Significantly, this approach also allows us to assess the role of quantum coherence on biological time scales, which is a topic of ongoing interest

    Consistent 3D Quantum Gravity on Lens Spaces

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    We study non-perturbative quantization of 3d gravity with positive cosmological constant (de Sitter space being the prototype vacuum solution, whose Euclideanization of course gives the three sphere) on the background topology of lens space, which is a three spheres modulo a discrete group. Instead of the strategy followed by a recent work \cite{Castro:2011xb}, which compares results in the second and first order formulations of gravity, we concentrate on the later solely. We note, as a striking feature, that the quantization, that relies heavily on the axiomatics of topological quantum field theory (TQFT) can only be consistently carried by augmenting the conventional theory by an additional topological term coupled through a dimensionless parameter. More importantly the introduction of this additional parameter renders the theory finite.Comment: New section and references added. Accepted in Phys. Rev. D for publicatio

    Phase i study of \u27dose-dense\u27 pemetrexed plus carboplatin/radiotherapy for locally advanced non-small cell lung carcinoma.

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    BACKGROUND: This phase I study investigates the feasibility of carboplatin plus dose-dense (q2-week) pemetrexed given concurrently with radiotherapy (XRT) for locally advanced and oligometastatic non-small cell lung cancer (NSCLC). METHODS: Eligible patients had Stage III or IV (oligometastatic) NSCLC. Patients received XRT to 63 Gy in standard fractionation. Patients received concurrent carboplatin (AUC = 6) during weeks 1 and 5 of XRT, and pemetrexed during weeks 1, 3, 5, and 7 of XRT. The starting dose level (level 1) of pemetrexed was 300 mg/m2. Following the finding of dose limiting toxicity (DLT) in dose level 1, an amended dose level (level 1A) continued pemetrexed at 300 mg/m2, but with involved field radiation instead of extended nodal irradiation. Consolidation consisted of carboplatin (AUC = 6) and pemetrexed (500 mg/m2) q3 weeks × 2 -3 cycles. RESULTS: Eighteen patients were enrolled. Fourteen patients are evaluable for toxicity analysis. Of the initial 6 patients treated on dose level 1, two experienced DLTs (one grade 4 sepsis, one prolonged grade 3 esophagitis). There was one DLT (grade 5 pneumonitis) in the 8 patients treated on dose level 1A. In 16 patients evaluable for response (4 with oligometastatic stage IV disease and 12 with stage III disease), the median follow-up time is 17.8 months. Thirteen of 16 patients had in field local regional response. The actuarial median survival time was 28.6 months in all patients and 34.7 months (estimated) in stage III patients. CONCLUSIONS: Concurrent carboplatin with dose-dense (q2week) pemetrexed at 300 mg/m2 with involved field XRT is feasible and encouraging in patients with locally advanced and oligometastatic NSCLC

    E5501: phase II study of topotecan sequenced with etoposide/cisplatin, and irinotecan/cisplatin sequenced with etoposide for extensive-stage small-cell lung cancer.

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    PURPOSE: Sequence-dependent improved efficacy of topoisomerase I followed by topoisomerase 2 inhibitors was assessed in a randomized phase II study in extensive-stage small-cell lung cancer (SCLC). METHODS: Patients with previously untreated extensive-stage SCLC with measurable disease, ECOG performance status of 0-3 and stable brain metastases were eligible. Arm A consisted of topotecan (0.75 mg/m(2)) on days 1, 2 and 3, etoposide (70 mg/m(2)) and cisplatin (20 mg/m(2)) (PET) on days 8, 9 and 10 in a 3-week cycle. Arm B consisted of irinotecan (50 mg/m(2)) and cisplatin (20 mg/m(2)) on days 1 and 8 followed by etoposide (85 mg/m(2) PO bid) on days 3 and 10 (PIE) in a 3-week cycle. RESULTS: We enrolled 140 patients and randomized 66 eligible patients to each arm. Only 54.5 % of all patients completed the planned maximum 6 cycles. There were grade ≥3 treatment-related adverse events in approximately 70 % of the patients on both arms including 6 treatment-related grade 5 events. The overall response rates (CR + PR) were 69.7 % (90 % CI 59.1-78.9, 95 % CI 57.1-80.4 %) for arm A and 57.6 % (90 % CI 46.7-67.9, 95 % CI 44.8-69.7 %) for arm B. The median progression-free survival and overall survival were 6.4 months (95 % CI 5.4-7.5 months) and 11.9 months (95 % CI 9.6-13.7 months) for arm A and 6.0 months (95 % CI 5.4-7.0 months) and 11.0 months (95 % CI 8.6-13.1 months) for arm B. CONCLUSION: Sequential administration of topoisomerase inhibitors did not improve on the historical efficacy of standard platinum-doublet chemotherapy for extensive-stage SCLC

    Ronald D. Cohen — Children of the Mill: Schooling and Society in Gary, Indiana, 1906-1960

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    McGill University on the Landscape of Canadian Higher Education: Historical Reflections

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    Student Life in Canadian Universities: The Lessons of History

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    This article explores the relationship between the history of the student experience and contemporary student life. It identifies enduring patterns in three areas: the social origins of students, student culture and activism, and the perceived academic quality of students. Reflecting their predominantly middle class backgrounds, university students have craved social status and feared the prospect of downward mobility, particularly in hard economic times. They have forged a student culture which serves to relieve academic tensions and strengthen their claim to social distinctiveness. Sexist outbursts by male students, past and present, speak to fundamental feelings of insecurity in the face of feminist movements. Political activism among a sizable minority of students, which predated the 1960s, now shows signs of re-emergence at a time when students sense that their long term goals may be frustrated. Finally, the professorial contention that students are academically less competent than ever has been heard before. A historical perspective, brought to this and other issues, should deepen understanding of the nature of student life.Cet article étudie le rapport qui existe entre l'histoire vécue de l'étudiant et la nature de sa vie étudiante. L'auteur constate qu'il existe des comportements persistants dépendant de trois facteurs : l'origine sociale de l'étudiant, sa culture et son dynamisme, et enfin la façon dont il perçoit sa valeur en tant qu'étudiant. Les étudiants universitaires, en grande majorité originaires de classes moyennes, sont à la recherche d'un statut social prestigieux et craignent de tomber dans une classe inférieure à celle dont ils sont issus, surtout à une époque difficile du point de vue économique. Ils se forgent des valeurs dont le but est de les soulager des tensions liées aux études et de renforcer leurs prétentions de distinction sociale. Les éclats sexistes passés ou présents expriment le profond sentiment d'insécurité que certains étudiants éprouvent vis-à-vis des mouvements féministes. L'activisme politique, anciennement associé aux années soixante, semble renaître dans une minorité non négligeable d'étudiants du fait que ceux-ci sentent bien qu'ils risquent de ne pas parvenir à leurs fins à long terme. De plus, c'est un lieu commun, dans le corps professoral, d'affirmer que les étudiants sont de plus en plus médiocres. Si l'on étudie la question d'un point de vue historique, tant dans ce numéro que dans ceux qui vont suivre, on devrait être en mesure de mieux comprendre de quoi est faite la vie quotidienne des étudiants

    How to overcome the detrimental effects of noise in social interaction: the benefits of generosity

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    Interpersonal misunderstanding is often rooted in noise, or discrepancies between intended and actual outcomes for an interaction partner due to unintended errors (e.g., not being able to respond to an E-mail because of a local network breakdown). How can one effectively cope with noise in social dilemmas, situations in which self-interest and collective interests are conflicting? Consistent with hypotheses, the present research revealed that incidents of noise exert a detrimental effect on level of cooperation when a partner follows strict reciprocity (i.e., tit for tat) but that this effect can be overcome if a partner behaves somewhat more cooperatively than the actor did in the previous interaction (i.e., tit for tat plus 1). Also, when noise was present, tit for tat plus 1 elicited greater levels of cooperation than did tit for tat, thereby underscoring the benefits of adding generosity to reciprocity in coping with noise in social dilemmas. The Discussion outlines implications of the present work for theories focusing on self-presentation and attribution, communication, and trust and prorelationship behavior
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