A pulsed NMR study of 3He-4He solutions

We report a study of the Leggett-Rice effect in dilute ³He-⁴He solutions at a Larmor frequency of 71 MHz. We have measured the height and phase of the spin echoes following 2-pulse NMR sequences of three solutions with ³He concentrations of 0.56%, 1.4%, and 4.0%. The theory of Leggett fits the data extremely well and yields values of the parameter M ₀ and the transverse diffusion coefficient D. We are also able to evaluate M ₀ and D by analyzing multiple spin echoes and find good consistency between the two methods. From values of /(1+F ₀ ^a ) at various concentrations, we are able to determine the scattering length for ³He quasiparticles, a, quite accurately. We find a = –0.97±0.03 Å.     

Developing a computer workshop to facilitate computer skills and minimize anxiety for early childhood educators.

Early childhood educators (n=133) were assigned to 1 of 3 instructional conditions (direct, guided discovery, or no-exposure control) to assess the impact of computer workshops on their level of computer anxiety, computer knowledge, and comfort with computer technology. Groups were matched for computer experience and anxiety, early childhood education (ECE) experience, and ECE center. The direct and guided discovery groups attended a 3-hr hands-on workshop covering hardware, software, and Internet material. Immediately after the workshops, computer anxiety was lower and comfort with computer technology increased. Six months later, the control group had reduced computer anxiety, but the other groups maintained greater knowledge and comfort. Direct instruction reduced computer anxiety slightly but did not promote the acquisition of information of the guided condition. Overall, workshops provided gains that could translate into more effective and efficient computer use in the classroom. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of factor VIII-related antigen and erythrocyte sedimentation rate in outpatient management of vasculitis

Electroimmunodiffusion (Laurell rocket) determinations of factor VIII-related antigen in plasma were ordered to determine the cost/benefit ratio for factor VIII-related antigen as a putative test for endothelial damage in suspected vasculitis. Twenty-seven consecutive patients referred for vasculitis or suspected vasculitis were identified and followed up for an average of 9.1 +/- months (range: one to thirty-three months) in a prospective, unblinded study performed in a clinic, associated with a 1054-bed inner-city university hospital. There was no difference in Westergren erythrocyte sedimentation rate (WESR) in patients with final diagnosis of systemic vasculitis (SV) (38 +/- 12 mm/hour) compared to those without vasculitis (NV) (27 +/- 7) as the final diagnosis. The mean plasma concentration of factor VIII-related antigen was significantly elevated in SV (344 +/- 100%) when compared with NV (147 +/- 39%) (P < 0.016). The factor VIII-related antigen test in this study was 2.56 times more likely (crude odds ratio) than the WESR to contribute to a change in diagnosis or therapy (P = 0.016). Positive and negative predictive values (PPV and NPV) for factor VIII-related antigen (abnormal at greater than 220% of the normal value) were both 70%. PPV and NPV for WESR were 56% and 86%, respectively. The factor VIII-related test was less cost-effective than the WESR in the follow-up period unless it was important to define complete remission or differentiate vasculitis flare from infection. The authors conclude that factor VIII-related antigen is a useful test in the initial diagnosis of vasculitis.     

Vesicoureteral reflux following transurethral resection of bladder tumors

Duodeno-gastric reflux measured in 18 patients without gastrointestinal complaints showed a wide variation of regurgitation rates. Duodeno-gastric reflux was significantly diminished during duodenal acidification. The effect was more intense and lasted longer after olive oil infused intraduodenally, leading practically to a closed pylorus.     

Methionine Enrichment of Milk Protein by Enzymatic Peptide Modification

Methionine-enriched protein was produced from an enzymatically pre-hydrolyzed milk protein using an enzymatic peptide modification (EPM) method with α-chymotrypsin as catalyst. Methionine of the product was twice as high as that of the substrate protein. The incorporated methionine formed a covalent bond with the peptide chain in the product protein. The change in the number of peptide bonds was monitored by the degree of hydrolysis (DH). The slight change of the DH values revealed that a portion of the free amino acids was bound to the peptide chains during the reaction and that transpeptidation was the main process during the EPM treatment. The location of the newly incorporated amino acids was determined by identification of the terminal amino acids. The covalently bound methionine was located in C- and N-terminal positions in a ratio of 3:1.     

Ionisation efficiency improvements for AMS measurement of actinides

Measurements of the isotopic ratios of plutonium and uranium are utilised by the safeguards community, environmental radioactivity and remediation studies, oceanography research, and in the U-series dating of geological samples. Accelerator Mass Spectrometry offers the advantages of high selectivity and sensitivity for such ratio measurements, but suffers from a poorer ionisation and transmission efficiency than some other mass spectrometric techniques. In addition, the ionisation efficiency achieved in caesium-sputter ion sources can be variable depending on the chemical form and geometry of the target used, yielding actinide negative ion beam rates with efficiencies ranging from 0.05% to 0.5%.In this paper we investigate the impact of the crystal structure of the target material, chemical composition and the geometry of the target in order to determine conditions which will allow us to maximise beam output and increase the efficiency of AMS measurements in future. We also examine target stability and “burn in time” (the time taken to generate a stable beam current) in conjunction with these measurements in order to maintain a high precision of measurement during the measurement period.     

Influence of Tertiary Gamma Prime (<Emphasis Type="Italic">γ</Emphasis>′) Size Evolution on Dwell Fatigue Crack Growth Behavior in CG RR1000

This work investigates coarsening behavior of strengthening precipitates (γ′) in coarse-grained RR1000 after isothermal exposure for various times (50 to 500 hours) at 700 °C and 750 °C. The impact of these isothermal treatments is then studied by carrying out dwell (1 hour) fatigue crack growth tests at 700 °C in air. Such dwell periods can increase crack growth rates by nearly two orders of magnitude compared with baseline (0.25 Hz trapezoidal waveform) fatigue crack growth tests. Predominantly, scanning electron microscopy was used for γ′ analysis. Transmission electron microscopy was also utilized when necessary. Overaging as a thermodynamically driven and diffusion-controlled process strongly affects tertiary γ′ precipitates for the temperatures and treatment times investigated here. No influence of overaging on baseline fatigue behavior is observed. However, after overaging at 750 °C for 500 hours (which increases the mean tertiary γ′ size by a factor of two from 17 to 37 nm), dwell crack growth rates at 700 °C are reduced by one order of magnitude. Increased dwell fatigue crack growth resistance is also measured after overaging for 100 hours at 700 °C. The potential influence of γ′ distributions on dwell fatigue crack growth resistance is discussed in terms of stress relaxation behavior during dwell periods.     

Lactate clearance and survival following injury

Previous reports cite optimization of O2 delivery (DO2) to 660 mL/min/m2, O2 consumption (VO2) to 170 mL/min/m2, and cardiac index (CI) of 4.5 L/min as predicting survival. We prospectively evaluated 76 consecutive patients with multiple trauma admitted directly to the ICU from the operating room or emergency department. Patients had serum lactate levels and oxygen transport measured on ICU admission and at 8, 16, 24, 36, and 48 hours. Patients were analyzed with respect to survival (S) versus nonsurvival (NS), lactate clearance to normal (< or = 2 mmol/L) by 24 and 48 hours, hemodynamic optimization as defined above, as well as Injury Severity Score (ISS), ICU stay (LOS), and admission blood pressure. All patients achieved non-flow-dependent VO2. There was no difference in CI, DO2, VO2, or ISS when S was compared with NS. All 27 patients whose lactate level normalized in 24 hours survived. If lactate levels cleared to normal between 24 and 48 hours, the survival rate was 75%. Only 3 of the 22 patients who did not clear their lactate level to normal by 48 hours survived. Ten of the 25 nonsurvivors (40%) achieved the above arbitrary optimization criteria. Fifteen of the survivors never achieved any of these criteria. Optimization alone does not predict survival. However, the time needed to normalize serum lactate levels is an important prognostic factor for survival in severely injured patients.     

Activating and dominant inactivating c-KIT catalytic domain mutations in distinct clinical forms of human mastocytosis

Human mastocytosis is characterized by increased mast cells. It usually occurs as a sporadic disease that is often transient and limited in children and persistent or progressive in adults. The c-KIT protooncogene encodes KIT, a tyrosine kinase that is the receptor for mast cell growth factor. Because mutated KIT can transform cells, we examined c-KIT in skin lesions of 22 patients with sporadic mastocytosis and 3 patients with familial mastocytosis. All patients with adult sporadic mastocytosis had somatic c-KIT mutations in codon 816 causing substitution of valine for aspartate and spontaneous activation of mast cell growth factor receptor (P = 0.0001). A subset of four pediatric onset cases with clinically unusual disease also had codon 816 activating mutations substituting valine, tyrosine, or phenylalanine for aspartate. Typical pediatric patients lacked 816 mutations, but limited sequencing showed three of six had a novel dominant inactivating mutation substituting lysine for glutamic acid in position 839, the site of a potential salt bridge that is highly conserved in receptor tyrosine kinases. No c-KIT mutations were found in the entire coding region of three patients with familial mastocytosis. We conclude that c-KIT somatic mutations substituting valine in position 816 of KIT are characteristic of sporadic adult mastocytosis and may cause this disease. Similar mutations causing activation of the mast cell growth factor receptor are found in children apparently at risk for extensive or persistent disease. In contrast, typical pediatric mastocytosis patients lack these mutations and may express inactivating c-KIT mutations. Familial mastocytosis, however, may occur in the absence of c-KIT coding mutations.