59 research outputs found
Signal and Noise Analysis in TRION -Time-Resolved Integrative Optical Fast Neutron Detector
TRION is a sub-mm spatial resolution fast neutron imaging detector, which
employs an integrative optical time-of-flight technique. The detector was
developed for fast neutron resonance radiography, a method capable of detecting
a broad range of conventional and improvised explosives. In this study we have
analyzed in detail, using Monte-Carlo calculations and experimentally
determined parameters, all the processes that influence the signal and noise in
the TRION detector. In contrast to event-counting detectors where the
signal-to-noise ratio is dependent only on the number of detected events
(quantum noise), in an energy-integrating detector additional factors, such as
the fluctuations in imparted energy, number of photoelectrons, system gain and
other factors will contribute to the noise. The excess noise factor (over the
quantum noise) due to these processes was 4.3, 2.7, 2.1, 1.9 and 1.9 for
incident neutron energies of 2, 4, 7.5, 10 and 14 MeV, respectively. It is
shown that, even under ideal light collection conditions, a fast neutron
detection system operating in an integrative mode cannot be
quantum-noise-limited due to the relatively large variance in the imparted
proton energy and the resulting scintillation light distributions.Comment: 18 page
High Spatial Resolution Fast-Neutron Imaging Detectors for Pulsed Fast-Neutron Transmission Spectroscopy
Two generations of a novel detector for high-resolution transmission imaging
and spectrometry of fast-neutrons are presented. These devices are based on a
hydrogenous fiber scintillator screen and single- or multiple-gated intensified
camera systems (ICCD). This detector is designed for energy-selective neutron
radiography with nanosecond-pulsed broad-energy (1 - 10 MeV) neutron beams.
Utilizing the Time-of-Flight (TOF) method, such a detector is capable of
simultaneously capturing several images, each at a different neutron energy
(TOF). In addition, a gamma-ray image can also be simultaneously registered,
allowing combined neutron/gamma inspection of objects. This permits combining
the sensitivity of the fast-neutron resonance method to low-Z elements with
that of gamma radiography to high-Z materials.Comment: Also published in JINST:
http://www.iop.org/EJ/abstract/1748-0221/4/05/P0501
Intercellular Transfer of Oncogenic H-Ras at the Immunological Synapse
Immune cells establish dynamic adhesive cell–cell interactions at a specific contact region, termed the immunological synapse (IS). Intriguing features of the IS are the formation of regions of plasma membrane fusion and the intercellular exchange of membrane fragments between the conjugated cells. It is not known whether upon IS formation, intact intracellular proteins can transfer from target cells to lymphocytes to allow the transmission of signals across cell boundaries. Here we show by both FACS and confocal microscopy that human lymphocytes acquire from the cells they scan the inner-membrane protein H-Ras, a G-protein vital for common lymphocyte functions and a prominent participant in human cancer. The transfer was cell contact-dependent and occurred in the context of cell-conjugate formation. Moreover, the acquisition of oncogenic H-RasG12V by natural killer (NK) and T lymphocytes had important biological functions in the adopting lymphocytes: the transferred H-RasG12V induced ERK phosphorylation, increased interferon-γ and tumor necrosis factor-α secretion, enhanced lymphocyte proliferation, and augmented NK-mediated target cell killing. Our findings reveal a novel mode of cell-to-cell communication—allowing lymphocytes to extend the confines of their own proteome—which may moreover play an important role in natural tumor immunity
Abstracts of papers presented at an international workshop on management of soilborne pathogens sponsored by the United States-Israel binational agricultural research and development fund (bard): March 1-5,1998 Ramat Rachel, Jerusalem, Israel
Efficacy of lamivudine for the treatment of hepatitis B virus infection after liver transplantation in children
Background. There is at present very little information about hepatitis B virus (HBV) infection in children after liver transplantation. This is the first study to assess the safety and efficacy of lamivudine in this patient population.
Methods. We describe three children aged 5-14 years who underwent liver transplantation for fulminant hepatitis A, hyperoxaluria, and cystic fibrosis. Despite adequate immunoprophylaxis, two of the children who were serum hepatitis B surface antigen-positive before transplantation (HBV DNA-negative by hybridization) had a reactivation of the disease, and one had a de novo HBV infection, at 12-18 months after transplantation. Lamivudine 3 mg/kg was administered on a compassionate-use basis for 14-36 months.
Results. After 1 month of therapy, HBV DNA disappeared from the serum in all patients by hybridization and in two patients by polymerase chain reaction. In all three children, alanine transaminase levels normalized. One child developed lamivudine resistance after 22 months with no evidence of hepatic decompensation. Repeated liver histological studies revealed progression of hepatic fibrosis in one child. All children remained serum hepatitis B surface antigen-and hepatitis B e antigen-positive. No adverse effects of the drug were noted.
Conclusion. Lamivudine is beneficial and well tolerated in children with HBV infection after liver transplantation
A non-invasive treatment (apostherapy) accelerates the rehabilitation time of patients following total hip arthroplasty. a prospective study
- …