Performance of the Los Alamos National Laboratory spallation-driven solid-deuterium ultra-cold neutron source.

In this paper, we describe the performance of the Los Alamos spallation-driven solid-deuterium ultra-cold neutron (UCN) source. Measurements of the cold neutron flux, the very low energy neutron production rate, and the UCN rates and density at the exit from the biological shield are presented and compared to Monte Carlo predictions. The cold neutron rates compare well with predictions from the Monte Carlo code MCNPX and the UCN rates agree with our custom UCN Monte Carlo code. The source is shown to perform as modeled. The maximum delivered UCN density at the exit from the biological shield is 52(9) UCN/cc with a solid deuterium volume of ~1500 cm(3).

Determination of the axial-vector weak coupling constant with ultracold neutrons.

A precise measurement of the neutron decay ß asymmetry A0 has been carried out using polarized ultracold neutrons from the pulsed spallation ultracold neutron source at the Los Alamos Neutron Science Center. Combining data obtained in 2008 and 2009, we report A0 = -0.119 66±0.000 89{-0.001 40}{+0.001 23}, from which we determine the ratio of the axial-vector to vector weak coupling of the nucleon g{A}/g{V}=-1.275 90{-0.004 45}{+0.004 09}.

Costs of sedation using oral midazolam: money, time, and parental attitudes.

OBJECTIVE: Many agents suitable for pediatric outpatient sedation have been identified and compared, but less data have appeared on the effect of sedation use on Emergency Department (ED) length of stay (LOS) or visit costs. We sought to discover the relationship between one commonly used method of sedation, orally administered midazolam, and ED LOS and visit costs. Parents were then surveyed to determine their attitudes toward sedation given knowledge of these costs. METHODS: All ED patients under 10 years of age seen in a pediatric ED during April and May of 1996 for repair of lacerations <2.5 cm in length were identified via retrospective chart review. Children were excluded if they had other significant injuries, received sedatives other than oral midazolam, or were repaired by non-ED physicians. Preliminary cost and LOS data from this review was used to create a parental survey measuring attitudes toward the costs of an unnamed form of sedation (not mentioning oral midazolam). A convenience sample of parents in an ED waiting room were asked if they would want sedation administered to a child needing sutures if this increased the visit cost by $100 and/or increased LOS by 30 minutes. Parents were then asked to re-answer these questions assuming that the sedation medication was effective only 50% of the time. RESULTS: Of 120 patients meeting entry criteria, 57 (48%) received oral midazolam. Children sedated with this agent were significantly younger (3.6 vs. 4.6 years, P = 0.015), had more layered repairs (30% vs. 14%, P = 0.047), and more facial lacerations (84% vs. 63%, P = 0.01) when compared with nonsedated patients. Mean LOS for patients with simple lacerations receiving oral midazolam increased by 17.1 minutes (P = 0.03) compared with nonsedated children; for layered repairs, the mean increase was 30.9 minutes (P<0.05). The use of oral midazolam did not effect physician charges, but did significantly increase mean combined nurse/hospital charges and total charges by 73 to 87 dollars, depending on laceration type (P<0.001 all cases). Of 81 parents surveyed, 81% said that they would be willing to wait 30 extra minutes for sedation to be used; this figure fell to 73% if sedation was effective 50% of the time. Seventy-five percent of parents were willing to pay $100 extra for sedation; 67% if sedation was effective only half the time. Willingness to endure a longer LOS or pay increased charges was not associated with parental sex or insurance status. CONCLUSION: The use of oral midazolam significantly increases ED visit LOS and cost. This information is important to review with parents when discussing sedation options. Up to one third of parents surveyed would not want to wait extra time or pay extra money for sedation to be administered, especially if the efficacy of the chosen method was not assured.

Pseudoephedrine and air travel-associated ear pain in children.

BACKGROUND: Young children often appear bothered by ear pain during ascent and descent while traveling on commercial airplanes. While pseudoephedrine hydrochloride is effective in decreasing the risk for earache in adults with recurrent air travel-associated ear pain, such use in children has not been studied. OBJECTIVE: To assess the efficacy and side effects of prophylactic pseudoephedrine in children traveling by air. DESIGN: A placebo-controlled, double-blind clinical trial. SUBJECTS AND METHODS: Children aged 6 months to 6 years were included in this study. Pseudoephedrine hydrochloride (1 mg/kg body weight) or placebo was administered 30 to 60 minutes prior to departure on commercial air flights. Caregivers noted historical details and the degree of apparent ear pain, drowsiness, and excitability with ascent and descent. RESULTS: Ninety-one flights involving 50 children were studied, with ear pain being reported in 13 (14%) of flights. Ear pain was not associated with a history of air travel-associated ear pain, recent ear infection, or recent upper airway symptoms. Pseudoephedrine use was not associated with a decrease in ear pain during either ascent (4% with pseudoephedrine vs 5% with placebo; P approximately 1.00) or descent (12% with pseudoephedrine vs. 13% with placebo; P approximately 1.00). Pseudoephedrine use was, however, linked to drowsiness at takeoff (60% with pseudoephedrine vs. 27% with placebo; P = .003) but not at landing (P = .39). Treatment was not associated with excitability at takeoff (P = .09) or landing (P approximately 1.00). CONCLUSIONS: Ear pain is not uncommon in children traveling by commercial aircraft. The predeparture use of pseudoephedrine does not decrease the risk for in-flight ear pain in children but is associated with drowsiness.

Tumor-derived suppressor factors (TDSFs) in normal and neoplastic colon and rectum.

Acid tumor-derived suppressor factors (TDSFs, isoelectric pH less than 3.0) in extracts of murine fibrosarcomas and human colorectal adenocarcinoma cell lines induce normal murine spleen cells to inhibit delayed-type hypersensitivity (DTH) to the sensitizer dinitrochlorobenzene (DNCB). We sought to determine if TDSF from normal and neoplastic human colon and rectum also inhibited normal human peripheral blood mononuclear cells (PBMC) responses to mitogen and to alloantigens. Collagenase-DNase digests of five freshly isolated carcinomas and paired autologous normal tissues were subjected to preparative isoelectric focusing (pIEF) over a pH range of 2.5 to 9.5. Fractions with isoelectric pH less than 3.0 from three of the five tumors induced normal C3H/HeN spleen cells to inhibit DTH to DNCB. Acid fractions from three tumors and four normal tissues also significantly inhibited the PBMC proliferative response to mitogen and alloantigens. However, the ability of acid fractions to suppress lymphocyte proliferation did not correlate with the induction of suppression of DTH to DNCB. Incubation of human PBMC with acid proliferation inhibitors did not induce suppressor cells that would inhibit the subsequent proliferative response of fresh, autologous PBMC. The acid suppressant from colorectal carcinoma was sensitive to treatment with trypsin but not RNase or DNase, whereas murine TDSF is sensitive to RNase and resistant to treatment with trypsin. The suppressive moiety from one tumor had an apparent mass of 45 kDa by gel filtration chromatography, in contrast to murine TDSF that has a mass of more than 300 kDa. Thus, the acid inhibitor in digests of human colorectal carcinoma is distinct from the TDSF that induces suppressor cells for DTH to DNCB.

Evaluation of individuals deferred from blood donation for medical reasons.

Modern techniques of blood collection require health screening of donors by non-physicians using general guidelines. Health problems of concern to the donor and possible loss to future donation of actually individuals are inherent in this acceptance and deferral process. Of the 108,908 donors presenting at the bloodmobiles of regional blood center from September 1978 to February 1979, 9,542 were deferred. Of these, 1,203 with possible medical problems other than hepatitis, hypertension, or infectious disease were referred to their physician for further information concerning their suitability as donors. Over 80% had irregular pulses or histories suggestive of potential cardiovascular problems. The purpose of this study was to review the evaluation mechanism. Responses for evaluation were received from only 222 out of 1,203 (18%), and of these all but 29 (13%) were granted full permission to donate. Since only one evaluated individual with pulse or cardiovascular findings of possible significance was under the age of 35 years, this age is a reasonable cutoff for such deferrals. The minimum increase in collections with this change in deferral screening would be over 1,000 units per year in Connecticut, and perhaps 60,000 nationwide.