682 research outputs found
A New Non-Perturbative Approach to Quantum Theory in Curved Spacetime Using the Wigner Function
A new non-perturbative approach to quantum theory in curved spacetime and to
quantum gravity, based on a generalisation of the Wigner equation, is proposed.
Our definition for a Wigner equation differs from what have otherwise been
proposed, and does not imply any approximations. It is a completely exact
equation, fully equivalent to the Heisenberg equations of motion. The approach
makes different approximation schemes possible, e.g. it is possible to perform
a systematic calculation of the quantum effects order by order. An iterative
scheme for this is also proposed. The method is illustrated with some simple
examples and applications. A calculation of the trace of the renormalised
energy-momentum tensor is done, and the conformal anomaly is thereby related to
non-conservation of a current in d=2 dimensions and a relationship between a
vector and an axial-vector current in d=4 dimensions.
The corresponding ``hydrodynamic equations'' governing the evolution of
macroscopic quantities are derived by taking appropriate moments. The emphasis
is put on the spin-1/2 case, but it is shown how to extend to arbitrary spins.
Gravity is treated first in the Palatini formalism, which is not very
tractable, and then more successfully in the Ashtekar formalism, where the
constraints lead to infinite order differential equations for the Wigner
functions.Comment: LaTeX2e (uses amssymb), 36 page
No. 7 - The Future of International Trade: An American Perspective
Organized and sponsored by the Dean Rusk Center for International Law and Policy and the University of Georgia’s Terry College of Business, along with the Business Law Society and Graduate Business Association, The Future of International Trade was a daylong conference exploring issues related to the business aspects of international trade, future challenges for trade, and the future of multilateral trade negotiations. Ambassador Demetrios Marantis, deputy U.S. trade representative, served as the keynote speaker for the event
Development and implementation of ISAR, a new synthesis platform for radiopharmaceutical production
Abstract
Background
PET radiopharmaceutical development and the implementation of a production method on a synthesis module is a complex and time-intensive task since new synthesis methods must be adapted to the confines of the synthesis platform in use. Commonly utilized single fluid bus architectures put multiple constraints on synthesis planning and execution, while conventional microfluidic solutions are limited by compatibility at the macro-to-micro interface. In this work we introduce the ISAR synthesis platform and custom-tailored fluid paths leveraging up to 70 individually addressable valves on a chip-based consumable. The ISAR synthesis platform replaces traditional stopcock valve manifolds with a fluidic chip that integrates all fluid paths (tubing) and valves into one consumable and enables channel routing without the single fluid bus constraint. ISAR can scale between the macro- (10 mL), meso- (0.5 mL) and micro- (≤0.05 mL) domain seamlessly, addressing the macro-to-micro interface challenge and enabling custom tailored fluid circuits for a given application. In this paper we demonstrate proof-of-concept by validating a single chip design to address the challenge of synthesizing multiple batches of [13N]NH3 for clinical use throughout the workday.
Results
ISAR was installed at an academic PET Center and used to manufacture [13N]NH3 in > 96% radiochemical yield. Up to 9 batches were manufactured with a single consumable chip having parallel paths without the need to open the hot-cell. Quality control testing confirmed the ISAR-based [13N]NH3 met existing clinical release specifications, and utility was demonstrated by imaging a rodent with [13N]NH3 produced on ISAR.
Conclusions
ISAR represents a new paradigm in radiopharmaceutical production. Through a new system architecture, ISAR integrates the principles of microfluidics with the standard volumes and consumables established in PET Centers all over the world. Proof-of-concept has been demonstrated through validation of a chip design for the synthesis of [13N]NH3 suitable for clinical use.https://deepblue.lib.umich.edu/bitstream/2027.42/152186/1/41181_2019_Article_77.pd
Recurrent venous thromboembolism and bleeding with extended anticoagulation: the VTE-PREDICT risk score
Aims
Deciding to stop or continue anticoagulation for venous thromboembolism (VTE) after initial treatment is challenging, as individual risks of recurrence and bleeding are heterogeneous. The present study aimed to develop and externally validate models for predicting 5-year risks of recurrence and bleeding in patients with VTE without cancer who completed at least 3 months of initial treatment, which can be used to estimate individual absolute benefits and harms of extended anticoagulation.
Methods and results
Competing risk-adjusted models were derived to predict recurrent VTE and clinically relevant bleeding (non-major and major) using 14 readily available patient characteristics. The models were derived from combined individual patient data from the Bleeding Risk Study, Hokusai-VTE, PREFER-VTE, RE-MEDY, and RE-SONATE (n = 15,141, 220 recurrences, 189 bleeding events). External validity was assessed in the Danish VTE cohort, EINSTEIN-CHOICE, GARFIELD-VTE, MEGA, and Tromsø studies (n = 59 257, 2283 recurrences, 3335 bleeding events). Absolute treatment effects were estimated by combining the models with hazard ratios from trials and meta-analyses. External validation in different settings showed agreement between predicted and observed risks up to 5 years, with C-statistics ranging from 0.48–0.71 (recurrence) and 0.61–0.68 (bleeding). In the Danish VTE cohort, 5-year risks ranged from 4% to 19% for recurrent VTE and 1% –19% for bleeding.
Conclusion
The VTE-PREDICT risk score can be applied to estimate the effect of extended anticoagulant treatment for individual patients with VTE and to support shared decision-making
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Spectroscopy of geo-neutrinos from 2056 days of Borexino data
We report an improved geo-neutrino measurement with Borexino from 2056 days
of data taking. The present exposure is
protonyr. Assuming a chondritic Th/U mass ratio of 3.9, we obtain geo-neutrino events. The null
observation of geo-neutrinos with Borexino alone has a probability of (5.9). A geo-neutrino signal from the mantle is
obtained at 98\% C.L. The radiogenic heat production for U and Th from the
present best-fit result is restricted to the range 23-36 TW, taking into
account the uncertainty on the distribution of heat producing elements inside
the Earth.Comment: 4 pages, 4 figure
Measurement of neutrino flux from the primary proton--proton fusion process in the Sun with Borexino detector
Neutrino produced in a chain of nuclear reactions in the Sun starting from
the fusion of two protons, for the first time has been detected in a real-time
detector in spectrometric mode. The unique properties of the Borexino detector
provided an oppurtunity to disentangle pp-neutrino spectrum from the background
components. A comparison of the total neutrino flux from the Sun with Solar
luminosity in photons provides a test of the stability of the Sun on the
10 years time scale, and sets a strong limit on the power production in
the unknown energy sources in the Sun of no more than 4\% of the total energy
production at 90\% C.L.Comment: 15 pages, 2 tables, 3 figure
Final results of Borexino Phase-I on low energy solar neutrino spectroscopy
Borexino has been running since May 2007 at the LNGS with the primary goal of
detecting solar neutrinos. The detector, a large, unsegmented liquid
scintillator calorimeter characterized by unprecedented low levels of intrinsic
radioactivity, is optimized for the study of the lower energy part of the
spectrum. During the Phase-I (2007-2010) Borexino first detected and then
precisely measured the flux of the 7Be solar neutrinos, ruled out any
significant day-night asymmetry of their interaction rate, made the first
direct observation of the pep neutrinos, and set the tightest upper limit on
the flux of CNO neutrinos. In this paper we discuss the signal signature and
provide a comprehensive description of the backgrounds, quantify their event
rates, describe the methods for their identification, selection or subtraction,
and describe data analysis. Key features are an extensive in situ calibration
program using radioactive sources, the detailed modeling of the detector
response, the ability to define an innermost fiducial volume with extremely low
background via software cuts, and the excellent pulse-shape discrimination
capability of the scintillator that allows particle identification. We report a
measurement of the annual modulation of the 7 Be neutrino interaction rate. The
period, the amplitude, and the phase of the observed modulation are consistent
with the solar origin of these events, and the absence of their annual
modulation is rejected with higher than 99% C.L. The physics implications of
phase-I results in the context of the neutrino oscillation physics and solar
models are presented
Identification of a Putative Crf Splice Variant and Generation of Recombinant Antibodies for the Specific Detection of Aspergillus fumigatus
BACKGROUND: Aspergillus fumigatus is a common airborne fungal pathogen for humans. It frequently causes an invasive aspergillosis (IA) in immunocompromised patients with poor prognosis. Potent antifungal drugs are very expensive and cause serious adverse effects. Their correct application requires an early and specific diagnosis of IA, which is still not properly achievable. This work aims to a specific detection of A. fumigatus by immunofluorescence and the generation of recombinant antibodies for the detection of A. fumigatus by ELISA. RESULTS: The A. fumigatus antigen Crf2 was isolated from a human patient with proven IA. It is a novel variant of a group of surface proteins (Crf1, Asp f9, Asp f16) which belong to the glycosylhydrolase family. Single chain fragment variables (scFvs) were obtained by phage display from a human naive antibody gene library and an immune antibody gene library generated from a macaque immunized with recombinant Crf2. Two different selection strategies were performed and shown to influence the selection of scFvs recognizing the Crf2 antigen in its native conformation. Using these antibodies, Crf2 was localized in growing hyphae of A. fumigatus but not in spores. In addition, the antibodies allowed differentiation between A. fumigatus and related Aspergillus species or Candida albicans by immunofluorescence microscopy. The scFv antibody clones were further characterized for their affinity, the nature of their epitope, their serum stability and their detection limit of Crf2 in human serum. CONCLUSION: Crf2 and the corresponding recombinant antibodies offer a novel approach for the early diagnostics of IA caused by A. fumigatus
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