412 research outputs found

    Universal restrictions to the conversion of heat into work derived from the analysis of the Nernst theorem as a uniform limit

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    We revisit the relationship between the Nernst theorem and the Kelvin-Planck statement of the second law. We propose that the exchange of entropy uniformly vanishes as the temperature goes to zero. The analysis of this assumption shows that is equivalent to the fact that the compensation of a Carnot engine scales with the absorbed heat so that the Nernst theorem should be embedded in the statement of the second law. ----- Se analiza la relaci{\'o}n entre el teorema de Nernst y el enunciado de Kelvin-Planck del segundo principio de la termodin{\'a}mica. Se{\~n}alamos el hecho de que el cambio de entrop{\'\i}a tiende uniformemente a cero cuando la temperatura tiende a cero. El an{\'a}lisis de esta hip{\'o}tesis muestra que es equivalente al hecho de que la compensaci{\'o}n de una m{\'a}quina de Carnot escala con el calor absorbido del foco caliente, de forma que el teorema de Nernst puede derivarse del enunciado del segundo principio.Comment: 8pp, 4 ff. Original in english. Also available translation into spanish. Twocolumn format. RevTe

    Stereotactic image-guided lung radiotherapy (SBRT) for clinical early-stage NSCLC: a long-term report from a multi-institutional database of patients treated with or without a pathologic diagnosis

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    PURPOSE: Early stage lung cancer is treated with stereotactic body radiation therapy (SBRT) in patients who are unable or unwilling to undergo surgical resection. Some patients' comorbidities are so severe that they are unable to even undergo a biopsy. A clinical diagnosis without biopsy before SBRT has been used, but there are limited data on its efficacy. METHODS AND MATERIALS: Data on patients treated with SBRT for non-small cell lung cancer, with and without tissue confirmation, were collected from multiple institutions across Europe, Canada, and the United States. Patients with a minimum of 2 years of comprehensive follow up were selected for analysis. Treatment and patient characteristics were compared. Overall survival (OS), disease-free survival (DFS), cause-specific survival (CSS), and rates of local recurrence (LR), regional recurrence (RR), and distant metastasis (DM) were calculated and analyzed. RESULTS: A total of 701 patients were identified, of which 67% had tissue confirmation of their tumors. The 3- and 5-year outcomes for OS, CSS, and DFS were 83.8%, 93.1%, 69%, and 60.6%, 86.7%, 45.5%, respectively. The rates for LR, RR, and DM at 3 and 5 years were 6.4%, 9.3%, 14.3%, and 10.5%, 14.3%, 19.7%, respectively. There were no statistically significant differences in survival outcomes or recurrences between the biopsy and no-biopsy cohorts. CONCLUSIONS: SBRT for clinically diagnosed lung cancers is efficacious in appropriately selected patients, with similar outcomes as those with a pathologic diagnosis. Thorough clinical and radiographic evaluations in a multidisciplinary setting are critical to the management of these patients

    Substantial Dose-response Relationship with Clinical Outcome for Lung Stereotactic Body Radiotherapy (SBRT) Delivered via Online Image Guidance

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    Purpose: To examine potential tumor dose-response relationships with various non-small cell lung cancer (NSCLC) SBRT fractionation regimens delivered with online CT-based image guidance. American Society for Therapeutic Radiation Oncology (ASTRO) 52nd Annual Meeting October 31 - November 4, San Diego, C

    Cruciferous vegetable feeding alters UGT1A1 activity: diet- and genotype-dependent changes in serum bilirubin in a controlled feeding trial.

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    Chemoprevention by isothiocyanates from cruciferous vegetables occurs partly through up-regulation of phase-II conjugating enzymes, such as UDP-glucuronosyl-transferases (UGT). UGT1A1 glucuronidates bilirubin, estrogens, and several dietary carcinogens. The UGT1A1*28 polymorphism reduces transcription compared to the wild-type, resulting in decreased enzyme activity. Isothiocyanates are metabolized by glutathione-S-transferases (GST); variants may alter isothiocyanate clearance, such that response to crucifers may vary by genotype. We evaluated, in a randomized, controlled, cross-over feeding trial in humans (n=70), 3 test diets, (single- and double-“dose” cruciferous and cruciferous plus apiaceous) compared to a fruit-and-vegetable-free basal diet. We measured serum bilirubin concentrations on days 0, 7, 11 and 14 of each 2-week feeding period to monitor UGT1A1 activity, and determined effects of UGT1A1*28 and GSTM1/GSTT1-null variants on response. Aggregate bilirubin response to all vegetable-containing diets was statistically significantly lower compared to the basal diet (p<0.03 for all). Within each UGT1A1 genotype, lower bilirubin concentrations were seen in: *1/*1 in both single and double-dose cruciferous diets compared to basal (p<0.03 for both); *1/*28 in double-dose cruciferous and cruciferous plus apiaceous compared to basal, and cruciferous plus apiaceous compared to single-dose cruciferous (p<0.02 for all); and *28/*28 in all vegetable-containing diets compared to basal (p<0.02 for all). Evaluation of the effects of diet stratified by GST genotype revealed some statistically significant genotypic differences however, the magnitude was similar and not statistically significant between genotypes. These results may have implications for altering carcinogen metabolism through dietary intervention, particularly among UGT1A1*28/*28 individuals

    Notes on the Third Law of Thermodynamics.I

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    We analyze some aspects of the third law of thermodynamics. We first review both the entropic version (N) and the unattainability version (U) and the relation occurring between them. Then, we heuristically interpret (N) as a continuity boundary condition for thermodynamics at the boundary T=0 of the thermodynamic domain. On a rigorous mathematical footing, we discuss the third law both in Carath\'eodory's approach and in Gibbs' one. Carath\'eodory's approach is fundamental in order to understand the nature of the surface T=0. In fact, in this approach, under suitable mathematical conditions, T=0 appears as a leaf of the foliation of the thermodynamic manifold associated with the non-singular integrable Pfaffian form δQrev\delta Q_{rev}. Being a leaf, it cannot intersect any other leaf S=S= const. of the foliation. We show that (N) is equivalent to the requirement that T=0 is a leaf. In Gibbs' approach, the peculiar nature of T=0 appears to be less evident because the existence of the entropy is a postulate; nevertheless, it is still possible to conclude that the lowest value of the entropy has to belong to the boundary of the convex set where the function is defined.Comment: 29 pages, 2 figures; RevTex fil

    Cardiac and Pulmonary Dosimetric Parameters in Lung Cancer Patients Undergoing Post-Operative Radiation Therapy in the Real-World Setting

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    Purpose/Objective(s): The recently published Lung ART trial reported increased rates of cardiac and pulmonary toxicity in the post-operative radiation therapy arm. It remains unknown whether the dosimetric parameters reported in Lung ART are representative of real-world practice. The purpose of this study is to examine heart and lung dose exposure in patients receiving post-operative radiation therapy for non-small cell lung cancer (NSCLC) across a statewide consortium. Materials/Methods: From 2012 to 2020, 377 patients at 27 academic and community centers within the Michigan Radiation Oncology Quality Consortium (MROQC) underwent surgical resection followed by post-operative radiation therapy for non-metastatic NSCLC. Demographic and dosimetric data were prospectively collected for these patients. Rates of 3D-CRT and IMRT use were analyzed. Mean heart dose (MHD), heart V5, heart V35, mean lung dose (MLD), lung V20, target volume and minimum dose to 95% PTV were calculated for these patients and the reported dosimetric parameters were stratified by treatment modality. Results: 51% of patients in this cohort had N2 disease at the time of surgery, 18% had a positive margin. 65.8% of patients were treated with IMRT compared to 32.1% treated with 3D-CRT. Average MHD for all patients was 10.3 Gy, mean Heart V5 was 40.3% and mean heart V35 was 12.6%. Average MLD was 11.2 Gy and mean lung V20 was 18.9%. These dosimetric parameters did not significantly differ based on treatment modality, with MHD and MLD 9.9 Gy and 10.1 Gy, respectively, for patients treated with 3D-CRT compared to 10.6 Gy and 11.8 Gy for patients treated with IMRT. Conclusion: Cardiac and lung dosimetric parameters for patients receiving post-operative radiation therapy for NSCLC are similar to the dosimetric characteristics reported in Lung ART. The mean heart and mean lung doses observed are slightly lower (MHD 10.3 Gy, MLD 11.2 Gy) compared to Lung ART (MHD 13 Gy, MLD 13 Gy), possibly owing to increased use of IMRT. These data support application of Lung ART\u27s findings outside of the clinical trial setting

    Poor Pulmonary Function is Not Associated with Increased Rates of Toxicity or Decreased Overall Survival After Stereotactic Body Radiotherapy for Early Stage Non-Small Cell Lung Cancer: Results of a Multi-institutional Analysis

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    Purpose/Objective(s): Stereotactic body radiotherapy (SBRT) is considered as the treatment of choice for stage I non-small cell lung cancer (NSCLC) in medically inoperable patients. It was the purpose of this study to evaluate whether pretreatment pulmonary function is predictive for survival and toxicity after SBRT. American Society for Therapeutic Radiation Oncology (ASTRO) 52nd Annual Meeting October 31 - November 4, San Diego, C

    Time Interval Between Staging FDG Positron Emission Tomography (PET) and Initiation of Stereotactic Lung Radiotherapy (SBRT) Impacts the Risk of Recurrence and Metastasis in Non-small Cell Lung Cancer (NSCLC)

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    Background: To study influence of time interval from staging PET scanning to RT start time on recurrence and survival in patients with NSCLC undergoing lung SBRT. American Society for Therapeutic Radiation Oncology (ASTRO) 52nd Annual Meeting October 31 - November 4, San Diego, C

    Determination of Debye Temperatures and Lamb-Mössbauer Factors for LnFeO3 Orthoferrite Perovskites (Ln = La, Nd, Sm, Eu, Gd)

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    Lanthanide orthoferrites have wide-ranging industrial uses including solar, catalytic and electronic applications. Here a series of lanthanide orthoferrite perovskites, LnFeO3 (Ln = La; Nd; Sm; Eu; Gd), prepared through a standard stoichiometric wet ball milling route using oxide precursors, has been studied. Characterisation through X-ray diffraction and X-ray fluorescence confirmed the synthesis of phase-pure or near-pure LnFeO3 compounds. 57Fe Mössbauer spectroscopy was performed over a temperature range of 10 K to 293 K to observe hyperfine structure and to enable calculation of the recoil-free fraction and Debye temperature (θD) of each orthoferrite. Debye temperatures (Ln = La 474 K; Nd 459 K; Sm 457 K; Eu 452 K; Gd 473 K) and recoil-free fractions (Ln = La 0.827; Nd 0.817; Sm 0.816; Eu 0.812; Gd 0.826) were approximated through minimising the difference in the temperature dependent experimental Centre Shift (CS) and theoretical Isomer Shift (IS), by allowing the Debye temperature and Isomer Shift values to vary. This method of minimising the difference between theoretical and actual values yields Debye temperatures consistent with results from other studies determined through thermal analysis methods. This displays the ability of variable-temperature Mössbauer spectroscopy to approximate Debye temperatures and recoil-free fractions, whilst observing temperature induced transitions over the temperature range observed. X-ray diffraction and Rietveld refinement show an inverse relationship between FeO6 octahedral volume and approximated Debye temperatures. Raman spectroscopy show an increase in the band positions attributed to soft modes of Ag symmetry, Ag(3) and Ag(5) from La to GdFeO3 corresponding to octahedral rotations and tilts in the [010] and [101] planes respectively

    A Multi-national Pooled Analysis of 434 Cases of Stage I Non-small Cell Lung Cancer (NSCLC) Treated with Volumetrically Image-guided Stereotactic Lung Radiotherapy: Results from the Elekta Collaborative Lung Research Group

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    Background: Published lung SBRT outcomes/dose response data for inoperable NSCLC come from small phase I-II studies or larger datasets not requiring image-guided radiotherapy (IGRT) or volumetric prescriptions. This entire cohort of SBRT patients had daily online cone-beam CT. American Society for Therapeutic Radiation Oncology (ASTRO) 52nd Annual Meeting October 31 - November 4, San Diego, C
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