The Cryogenic Target for the G0^0 Experiment at Jefferson Lab

A cryogenic horizontal single loop target has been designed, built, tested and operated for the G$^0$ experiment in Hall C at Jefferson Lab. The target cell is 20 cm long, the loop volume is 6.5 l and the target operates with the cryogenic pump fully immersed in the fluid. The target has been designed to operate at 30 Hz rotational pump speed with either liquid hydrogen or liquid deuterium. The high power heat exchanger is able to remove 1000 W of heat from the liquid hydrogen, while the nominal electron beam with current of 40 $\mu$A and energy of 3 GeV deposits about 320 W of heat into the liquid. The increase in the systematic uncertainty due to the liquid hydrogen target is negligible on the scale of a parity violation experiment. The global normalized yield reduction for 40 $\mu$A beam is about 1.5 % and the target density fluctuations contribute less than 238 ppm (parts per million) to the total asymmetry width, typically about 1200 ppm, in a Q$^2$ bin.Comment: 27 pages, 14 figure

Integral-based filtering of continuous glucose sensor measurements for glycaemic control in critical care

Hyperglycaemia is prevalent in critical illness and increases the risk of further complications and mortality, while tight control can reduce mortality up to 43%. Adaptive control methods are capable of highly accurate, targeted blood glucose regulation using limited numbers of manual measurements due to patient discomfort and labour intensity. Therefore, the option to obtain greater data density using emerging continuous glucose sensing devices is attractive. However, the few such systems currently available can have errors in excess of 20-30%. In contrast, typical bedside testing kits have errors of approximately 7-10%. Despite greater measurement frequency larger errors significantly impact the resulting glucose and patient specific parameter estimates, and thus the control actions determined creating an important safety and performance issue. This paper models the impact of the Continuous Glucose Monitoring System (CGMS, Medtronic, Northridge, CA) on model-based parameter identification and glucose prediction. An integral-based fitting and filtering method is developed to reduce the effect of these errors. A noise model is developed based on CGMS data reported in the literature, and is slightly conservative with a mean Clarke Error Grid (CEG) correlation of R=0.81 (range: 0.68-0.88) as compared to a reported value of R=0.82 in a critical care study. Using 17 virtual patient profiles developed from retrospective clinical data, this noise model was used to test the methods developed. Monte-Carlo simulation for each patient resulted in an average absolute one-hour glucose prediction error of 6.20% (range: 4.97-8.06%) with an average standard deviation per patient of 5.22% (range: 3.26-8.55%). Note that all the methods and results are generalisable to similar applications outside of critical care, such as less acute wards and eventually ambulatory individuals. Clinically, the results show one possible computational method for managing the larger errors encountered in emerging continuous blood glucose sensors, thus enabling their more effective use in clinical glucose regulation studies

Development of a Clinical Type 1 Diabetes Metabolic System Model and in Silico Simulation Tool

Invited journal symposium paperObjectives: To develop a safe and effective protocol for the clinical control of Type 1 diabetes using conventional self-monitoring blood glucose (SMBG) measurements, and multiple daily injection (MDI) with insulin analogues. To develop an in silico simulation tool of Type 1 diabetes to predict long-term glycaemic control outcomes of clinical interventions. Methods: The virtual patient method is used to develop a simulation tool for Type 1 diabetes using data from a Type 1 diabetes patient cohort (n=40). The tool is used to test the adaptive protocol (AC) and a conventional intensive insulin therapy (CC) against results from a representative control cohort. Optimal and suboptimal basal insulin replacement are evaluated as a function of self-monitoring blood glucose (SMBG) frequency in conjunction with the (AC and CC) prandial control protocols. Results: In long-term glycaemic control, the AC protocol significantly decreases HbA1c in conditions of suboptimal basal insulin replacement for SMBG frequencies =6/day, and reduced the occurrence of mild and severe hypoglycaemia by 86-100% over controls over all SMBG frequencies in conditions of optimal basal insulin. Conclusions: A simulation tool to predict long-term glycaemic control outcomes from clinical interventions is developed to test a novel, adaptive control protocol for Type 1 diabetes. The protocol is effective and safe compared to conventional intensive insulin therapy and controls. As fear of hypoglycaemia is a large psychological barrier to glycaemic control, the AC protocol may represent the next evolution of intensive insulin therapy to deliver increased glycaemic control with increased safety. Further clinical or experimental validation is needed to fully prove the concept

Overview of Glycemic Control in Critical Care - Relating Performance and Clinical Results

Inagural review article invited for inaugural journalBackground: Hyperglycemia is prevalent in critical care and tight control can save lives. Current ad-hoc clinical protocols require significant clinical effort and produce highly variable results. Model-based methods can provide tight, patient specific control, while addressing practical clinical difficulties and dynamic patient evolution. However, tight control remains elusive as there is not enough understanding of the relationship between control performance and clinical outcome. Methods: The general problem and performance criteria are defined. The clinical studies performed to date using both ad-hoc titration and model-based methods are reviewed. Studies reporting mortality outcome are analysed in terms of standardized mortality ratio (SMR) and a 95th percentile (±2 ) standard error (SE95%) to enable better comparison across cohorts. Results: Model-based control trials lower blood glucose into a 72-110mg/dL band within 10 hours, have target accuracy over 90%, produce fewer hypoglycemic episodes, and require no additional clinical intervention. Plotting SMR versus SE95% shows potentially high correlation (r=0.84) between ICU mortality and tightness of control. Summary: Model-based methods provide tighter, more adaptable “one method fits all” solutions, using methods that enable patient-specific modeling and control. Correlation between tightness of control and clinical outcome suggests that performance metrics, such as time in a relevant glycemic band, may provide better guidelines. Overall, compared to current “one size fits all” sliding scale and ad-hoc regimens, patient-specific pharmacodynamic and pharmacokinetic model-based, or “one method fits all”, control, utilizing computational and emerging sensor technologies, offers improved treatment and better potential outcomes when treating hyperglycemia in the highly dynamic critically ill patient

A Compact 3H(p,gamma)4He 19.8-MeV Gamma-Ray Source for Energy Calibration at the Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory (SNO) is a new 1000-tonne D2O Cerenkov solar neutrino detector. A high energy gamma-ray source is needed to calibrate SNO beyond the 8B solar neutrino endpoint of 15 MeV. This paper describes the design and construction of a source that generates 19.8-MeV gamma rays using the 3H(p,gamma)4He reaction (``pt''), and demonstrates that the source meets all the physical, operational and lifetime requirements for calibrating SNO. An ion source was built into this unit to generate and to accelerate protons up to 30 keV, and a high purity scandium tritide target with a scandium-tritium atomic ratio of 1:2.0+/-0.2 was included. This pt source is the first self-contained, compact, and portable high energy gamma-ray source (E>10 MeV).Comment: 33 pages (including 2 table, 12 figures) This is the revised manuscript, accepted for publication in NIM A. This revision relfects minor editorial changes from the previous versio

Insulin + nutrition control for tight critical care glycaemic regulation

A new insulin and nutrition control method for tight glycaemic control in critical care is presented from concept to clinical trials to clinical practice change. The primary results show that the method can provide very tight glycaemic control in critical care for a very critically ill cohort. More specifically, the final clinical practice change protocol provided 2100 hours of control with average blood glucose of 5.8 +/- 0.9 mmol/L for an initial 10 patient pilot study. It also used less insulin, while providing the same or greater nutritional input, as compared to retrospective hospital control for a relatively very critically ill cohort with high insulin resistance

Serum antioxidants as predictors of the adult respiratory distress syndrome in septic patients

Adult respiratory distress syndrome (ARDS) can develop as a complication of various disorders, including sepsis, but it has not been possible to identify which of the patients at risk will develop this serious disorder. We have investigated the ability of six markers, measured sequentially in blood, to predict development of ARDS in 26 patients with sepsis. At the initial diagnosis of sepsis (6-24 h before the development of ARDS), serum manganese superoxide dismutase concentration and catalase activity were higher in the 6 patients who subsequently developed ARDS than in 20 patients who did not develop ARDS. These changes in antioxidant enzymes predicted the development of ARDS in septic patients with the same sensitivity, specificity, and efficiency as simultaneous assessments of serum lactate dehydrogenase activity and factor VIII concentration. By contrast, serum glutathione peroxidase activity and α1Pi-elastase complex concentration did not differ at the initial diagnosis of sepsis between patients who did and did not subsequently develop ARDS, and were not as effective in predicting the development of ARDS. Measurement of manganese superoxide dismutase and catalase, in addition to the other markers, should facilitate identification of patients at highest risk of ARDS and allow prospective treatment

A high-flux source of polarization-entangled photons from a periodically-poled KTP parametric downconverter

We have demonstrated a high-flux source of polarization-entangled photons using a type-II phase-matched periodically-poled KTP parametric downconverter in a collinearly propagating configuration. We have observed quantum interference between the single-beam downconverted photons with a visibility of 99% and a measured coincidence flux of 300/s/mW of pump. The Clauser-Horne-Shimony-Holt version of Bell's inequality was violated with a value of 2.711 +/- 0.017.Comment: 7 pages submitted to Physical Review

Remarks on the forces generated by two-neutrino exchange

A brief up-to-date review of the long range forces generated by two neutrino exchange is presented. The potential due to exchange of a massive neutrino-antineutrino pair between particles carrying weak charge might be larger than expected if the neutrinos have not only masses but also magnetic moments close to the present experimental bounds. It still remains too small to be observable.Comment: 10 pages, 3 figures. One figure added. Accepted for publication in EPJ

Estimates of hypolimnetic oxygen deficits in ponds

Shallow tropical integrated culture ponds in the Pearl River Delta, China, have been found to stratify almost daily, with high organic loadings and dense algal growth. The dissolved oxygen (DO) concentration is super-saturated in the epilimnion and is under 2 mg/l in the hypolimnion (>1m). The compensation depth corresponds to twice the Secchi disk depth ranging from 50 to 80cm. As a result, little or no net oxygen is produced in the hypolimnion (>1m). The low DO concentration in the hypolimnion causes organic materials, such as unused organic wastes and senescent algae cells, to be incompletely oxidized, since the rate of oxygen consumption by oxidable matter in water is dependent on the dissolved oxygen concentration in water. This material becomes the source of hypolimnetic oxygen deficits (HOD) which can drive whole pond DO to a dangerously low level, should sudden destratification occur. An improved estimate of hypolimnetic oxygen deficits is introduced in this article, and the advantages of this method are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72126/1/j.1365-2109.1989.tb00341.x.pd