Reliability History and Improvements to the ANL 50 MEV H- Accelerator

The H- Accelerator consists of a 750 keV Cockcroft Walton preaccelerator and an Alvarez type 50 MeV linac. The accelerator has been in operation since 1961. Since 1981, it has been used as the injector for the Intense Pulsed Neutron Source (IPNS), a national user facility for neutron scattering. The linac delivers about 3.5x1012 H- ions per pulse, 30 times per second (30 Hz), for multi-turn injection to a 450 MeV Rapid Cycling Synchrotron (RCS). IPNS presently operates about 4,000 hours per year, and operating when scheduled is critical to meeting the needs of the user community. For many years the IPNS injector/RCS has achieved an average reliability of 95%, helped in large part by the preaccelerator/linac which has averaged nearly 99%. To maintain and improve system reliability, records need to show what each subsystem contributes to the total down time. The history of source and linac subsystem reliability, and improvements that have been made to improve reliability, will be described. Plans to maintain or enhance this reliability for at least another ten years of operation, will also be discussed.Comment: 3 pages, 1 figur

Early death or retransplantation in adults after orthotopic liver transplantation: Can outcome be predicted?

Early, reliable outcome prediction after a liver transplant would help improve organ use by minimizing unnecessary retransplantations. At the same time, early intervention in those cases destined to fail may ameliorate the high morbidity and mortality associated with retransplantation. The purpose of this study was to analyze several parameters that have been identified in the past as being associated with patient and graft outcome, and to try to develop a model that would allow us to make predictions based on data available in the early postoperative period. A total of 148 patients were followed in a prospective, observational study. Graft failure was defined as patient death or retransplantation within 3 months of surgery. Preoperative variables studied included patient demographics, need for life support, presence of ascites, serum bilirubin, serum albumin, prothrombin time, serum creatinine, and the results of the cytotoxic crossmatch. During the first 5 postoperative days, standard measurements included serum transaminases, serum bilirubin, ketone body ratio, prothrombin time, factor V, and serum lactate. Oxygen consumption was measured shortly after surgery, once the patients had rewarmed to 36°C. There were 131 successful transplants (88.5%) and 17 failures (11.5%). Most of the variables studied were found to be associated with outcome (by univariate analysis) at different points in the early postoperative period. However, receiver operating characteristic curve analysis showed that the predictive ability of even the best parameter was not adequate to make decisions on individual patients. Multivariate analysis, using stepwise logistic regression, yielded a model with an overall accuracy of 92.7%. Again, receiver operating characteristic curve analysis suggested that this model did not achieve the discriminating power needed for routine clinical use. We are still not able to accurately predict outcome in the early posttransplant period. We must be very careful when evaluating parameters, or scoring systems, that are said to accomplish this. It is especially important in this era of cost containment, with its renewed pressures to guide therapy based on our perceived understanding of a patient’s future clinical course. © 1994 by Williams & Wilkins

Exploiting cross-channel quantizer error correlation in time-interleaved analog-to-digital converters

Uniform quantizers are often modeled as additive uncorrelated noise sources. This paper explores the validity of the additive noise model in the environment of time-interleaved A/D converters. Cross-channel quantizer error correlation is an important discrepancy that arises for channel time delays in close proximity. It is demonstrated through simulation that negative error correlation occurs for different granularity quantizers in close proximity. Statistical analysis is presented to characterize error correlation between quantizers with different granularity. A technique exploiting this correlation often yields significant performance gains above the optimal additive noise model solution.Fullbright FellowshipIrwin Mark Jacobs and Joan Klein Jacobs Presidential FellowshipTexas Instruments Incorporated. Leadership University Consortium ProgramBAE SystemsAnalog Devices, inc.Lincoln Laborator

Methods and materials for detection of multiple sclerosis

Methods and materials for diagnosis of a multiple sclerosis disease state. Antigenic blood fractions from patients clinically diagnosed for multiple sclerosis are employed to generate heterologous species antibodies. Novel antibody preparations are employed to detect the presence or absence, in a blood sample of a patient to be tested, of immunologically significant components specifically associated with a multiple sclerosis disease state

The current status of hepatic transplantation at the University of Pittsburgh.

Tacrolimus is a more potent and satisfactory immunosuppressant than CyA for combination therapy with prednisone. In randomized trials comparing the 2 drugs, the ability of tacrolimus to rescue intractably rejecting grafts on the competing CyA arm allowed equalization of patient and graft survival on both arms when the intent-to-treat analytic methodology was applied. The ability of tacrolimus to systematically rescue the treatment failures of CyA suggested, as a matter of common sense, that it is the preferred baseline drug for hepatic transplantation. This conclusion was supported by analysis of secondary end points, including the ability to prevent rejection. Hepatic-intestinal, multivisceral and isolated intestinal transplantation became feasible on a practical basis only after the advent of tacrolimus. Nevertheless, better management strategies must be devised before intestinal transplantation, alone or with other abdominal viscera, will meet its potential. One such strategy is based on the discovery of the presence of previously unsuspected, low-level donor leukocyte chimerism in long-surviving allograft recipients. We believe that this chimerism is the essential explanation for the feasibility of organ transplantation and a link to the acquired neonatal tolerance demonstrated by Billingham, Brent and Medawar (32). The hematolymphopoietic chimerism in organ recipients explains why weaning to a drug-free state in selected long-term survivors is frequently feasible and particularly if the allograft is a liver. Weaning should never be attempted without a stepwise protocol and careful monitoring of graft function. Recognition of the natural chimerism that develops after whole organ transplantation has led to efforts to augment it with perioperative donor BM infusion. This procedure has been shown to be free of significant complications (including GVHD) in all kinds of whole organ recipients, including those given intestine. The prospects of clinical xenotransplantation must be evaluated in the same context of chimerism as that delineated for allotransplantation with the discovery of spontaneous chimerism. Before addressing chimerism-related questions in xenotransplantation, the additional barrier of the complement activation syndromes that cause hyperacute rejection will have to be surmounted. Although measures to effectively transplant xenografts have so far eluded us, the availability of the more potent drug, tacrolimus, and recognition of the seminal basis of allograft (or xenograft) acceptance via chimerism has inserted an element of reality into the largely wishful thinking that has been evident in discussions about the future of xenotransplantation

Climate change and rising energy costs will change everything: A new mindset and action plan for 21st Century public health

Western governments currently prioritize economic growth and the pursuit of profit above alternative goals of sustainability, health and equality. Climate change and rising energy costs are challenging this consensus. The realization of the transformation required to meet these challenges has provoked denial and conflict, but could lead to a more positive response which leads to a health dividend; enhanced well-being, less overconsumption and greater equality. This paper argues that public health can make its best contribution by adopting a new mindset, discourse, methodology and set of tasks

A Real-Time Energy Monitor System for the Ipns Linac

Injected beam energy and energy spread are critical parameters affecting the performance of our rapid cycling synchrotron (RCS). A real-time energy monitoring system is being installed to examine the H- beam out of the Intense Pulsed Neutron Source (IPNS) 50 MeV linac. The 200 MHz Alvarez linac serves as the injector for the 450 MeV IPNS RCS. The linac provides an 80 ms macropulse of approximately 3x1012 H- ions 30 times per second for coasting-beam injection into the RCS. The RCS delivers protons to a heavy-metal spallation neutron target for material science studies. Using a number of strip-line beam position monitors (BPMs) distributed along the 50 MeV transport line from the linac to the RCS, fast signals from the strip lines are digitized and transferred to a computer which performs an FFT. Corrections for cable attenuation and oscilloscope bandwidth are made in the frequency domain. Rectangular pulse train phasing (RPTP) is imposed on the spectra prior to obtaining the inverse transform (IFFT). After the IFFT, the reconstructed time-domain signal is analyzed for pulse width as it progresses along the transport line. Time-of-flight measurements of the BPM signals provide beam energy. Finally, using the 3-size measurement technique, the longitudinal emittance and energy spread of the beam are determined

Climate change and rising energy costs: a threat but also an opportunity for a healthier future?

Health problems caused by overconsumption, growing inequalities and diminished well-being are issues that have been attributed to the prioritization of economic growth as the central purpose of society. It is also known that climate change and rising energy prices will inevitably bring changes to the globe's economic models. Doctors and the wider public health community have campaigned successfully in the past on issues such as the threat of nuclear war. Is it now time for this constituency to make its distinctive contribution to these new threats to health