Measuring the principal Hugoniot of inertial-confinement-fusion-relevant TMPTA plastic foams.

Wetted-foam layers are of significant interest for inertial-confinement-fusion capsules, due to the control they provide over the convergence ratio of the implosion and the opportunity this affords to minimize hydrodynamic instability growth. However, the equation of state for fusion-relevant foams are not well characterized, and many simulations rely on modeling such foams as a homogeneous medium with the foam average density. To address this issue, an experiment was performed using the VULCAN Nd:glass laser at the Central Laser Facility. The aim was to measure the principal Hugoniot of TMPTA plastic foams at 260mg/cm^{3}, corresponding to the density of liquid DT-wetted-foam layers, and their "hydrodynamic equivalent" capsules. A VISAR was used to obtain the shock velocity of both the foam and an α-quartz reference layer, while streaked optical pyrometry provided the temperature of the shocked material. The measurements confirm that, for the 20-120 GPa pressure range accessed, this material can indeed be well described using the equation of state of the homogeneous medium at the foam density.

Collapse dynamics of spherical cavities in a solid under shock loading.

Extraordinary states of highly localised pressure and temperature can be generated upon the collapse of impulsively driven cavities. Direct observation of this phenomenon in solids has proved challenging, but recent advances in high-speed synchrotron radiography now permit the study of highly transient, subsurface events in real time. We present a study on the shock-induced collapse of spherical cavities in a solid polymethyl methacrylate medium, driven to shock states between 0.49 and 16.60 GPa. Utilising multi-MHz phase contrast radiography, extended sequences of the collapse process have been captured, revealing new details of interface motion, material failure and jet instability formation. Results reveal a rich array of collapse characteristics dominated by strength effects at low shock pressures and leading to a hydrodynamic response at the highest loading conditions.

Ultrafast Imaging of Laser Driven Shock Waves using Betatron X-rays from a Laser Wakefield Accelerator.

Betatron radiation from laser wakefield accelerators is an ultrashort pulsed source of hard, synchrotron-like x-ray radiation. It emanates from a centimetre scale plasma accelerator producing GeV level electron beams. In recent years betatron radiation has been developed as a unique source capable of producing high resolution x-ray images in compact geometries. However, until now, the short pulse nature of this radiation has not been exploited. This report details the first experiment to utilize betatron radiation to image a rapidly evolving phenomenon by using it to radiograph a laser driven shock wave in a silicon target. The spatial resolution of the image is comparable to what has been achieved in similar experiments at conventional synchrotron light sources. The intrinsic temporal resolution of betatron radiation is below 100 fs, indicating that significantly faster processes could be probed in future without compromising spatial resolution. Quantitative measurements of the shock velocity and material density were made from the radiographs recorded during shock compression and were consistent with the established shock response of silicon, as determined with traditional velocimetry approaches. This suggests that future compact betatron imaging beamlines could be useful in the imaging and diagnosis of high-energy-density physics experiments.

A well-baby peer counseling program is not associated with human milk receipt in the NICU.

OBJECTIVE: Evaluate the impact of a non-neonatal intensive care unit (NICU)-specific peer counseling (PC) program on the cessation of human milk receipt at and post-NICU discharge. STUDY DESIGN: A multivariable logistic regression model used data from 400 mother-infant dyads from a level IV NICU to compare cessation of human milk receipt at NICU discharge by PC program status. Kaplan-Meier distributions and a multivariable Cox proportional hazards model assessed the relationship between participants/non-participants and cessation of human milk post-NICU discharge. RESULTS: No statistically significant differences between groups in cessation of human milk either by or post-discharge were observed. Identified variables associated with the outcome(s) of interest included maternal and infant age, length of stay, presence of a breastfeeding duration goal and frequency of NICU lactation consultant contact. CONCLUSION: Exposure to a non NICU-specific PC program was not associated with human milk receipt either by or post-NICU discharge.

X-ray imaging of subsurface dynamics in high-Z materials at the Diamond Light Source.

In this paper, we describe a new approach enabling study of subsurface dynamics in high-Z materials using the unique combination of high-energy synchrotron X-rays, a hybrid bunch structure, and a new dynamic loading platform. We detail the design and operation of the purpose-built, portable small bore gas-gun, which was installed on the I12 high-energy beamline at the Diamond Light Source and used to drive compression waves into solid and porous metal targets. Using a hybrid bunch structure and broadband X-ray pulses of up to 300 keV, radiographic snapshots were captured during various dynamic deformation processes in cm-scale specimens, thereby contributing to a more complete understanding of the evolution of mesoscale damage. Importantly, we highlight strategies for overcoming the challenges associated with using high-energy X-rays, and suggest areas for improvement needed to advance dynamic imaging through large-scale samples of relevance to engineering scenarios. These preliminary measurements demonstrate the feasibility of probing highly transient phenomena using the presented methodology.

Validity and public health implications of maternal perception of the onset of lactation: an international analytical overview.

The main objective of this analytical overview is to assess the validity of maternal perception of the onset of lactation (OL) as an indicator of lactogenesis stage II (LS-II). Prospective studies that assessed OL and/or LS-II [based on test-weighing milk volume (MV) and/or breast milk biomarkers (BMB)] were identified. OL is a clearly defined and easily identified event across cultures, with the overwhelming majority of women being able to report when they experience it. Mean OL ranges from 50 to 73 h postpartum across studies and from 1 to 148 h postpartum within studies. The wide range detected within samples is fully consistent with the wide within sample LS-II variability as determined by BMB or MV. Studies have identified similar risk factors for delayed LS-II, such as labor and delivery stress, primiparity and insulin-dependent diabetes mellitus, regardless of marker used (i.e., OL, MV or BMB). The correlation between OL and MV (r = -0.60) is of similar magnitude to that between OL and BMB (r = 0.50) and that between BMB and MV (r = 0.47-0.69). In conclusion, OL is a valid clinical indicator of LS-II. This has public health relevance because studies have identified delayed OL (i.e., >72 h postpartum) as a risk factor for shorter breastfeeding duration and for greater infant weight loss by d 3 postpartum. Multidisciplinary studies are needed to standardize the definition of OL and to confirm its validity in different sociocultural contexts.

Impact of breast pumping on lactogenesis stage II after cesarean delivery: a randomized clinical trial.

OBJECTIVE: Women at risk for delayed onset of lactation are often advised to pump their breasts before lactogenesis stage II to hasten the timing of this process. The effectiveness of this clinical practice has not been previously evaluated. This study investigates the effects of breast pumping before the onset of lactation on early milk transfer and subsequent breastfeeding duration among women giving birth by cesarean delivery. METHODOLOGY: Sixty women were randomly assigned to either the pumping group (n = 30), which used a double electric breast pump for six 10- to 15-minute sessions from 24 to 72 hours postpartum, or to the control group (n = 30), which held the pump to their breasts without suction for the same amount of time. Milk transfer was assessed by test weighing infants before and after 3 breastfeeding sessions daily. Test weight data were fitted to a second-order polynomial curve, to predict milk transfer over time. RESULTS: Breast pumping between 24 and 72 hours after cesarean delivery did not improve milk transfer. Participants in the pumping group tended to have lower milk transfer than did controls. Primiparae in the pumping group breastfed for ~5 months less than their counterparts in the control group; however, this difference was not statistically significant. CONCLUSIONS: Breast pumping did not improve milk transfer during the first 72 hours postpartum and may negatively affect breastfeeding duration among primiparous women. lactation, lactogenesis, breast milk, breast pumping, milk expression, breastfeeding, cesarean delivery.

Maternal perception of the onset of lactation is a valid, public health indicator of lactogenesis stage II.

Test weighing is the "gold standard" for documenting lactogenesis stage II. However, this method is impractical for use in population studies. Maternal perception of the timing of the onset of lactation may be a useful proxy for lactogenesis stage II. This study seeks to validate maternal perception of the onset of lactation as a marker of lactogenesis stage II. Women (n = 60) were recruited after cesarean delivery. Beginning at 24 h postpartum (pp), the onset of lactation was assessed 3 times daily by both test weighing and maternal perception. Delayed onset of lactation was defined as follows: 1) milk transfer < 9.2 g/feeding at 60 h pp and 2) maternal perception >/= 72 h pp. Misclassification analyses were conducted. Multivariate logistic regression, bivariate analyses and Cox survival analyses were used to evaluate the determinants and consequences of delayed onset of lactation, using both definitions. The sensitivity and specificity of delayed maternal perception as an indicator of delayed lactogenesis were 71.4 and 79.3%, respectively. Four risk factors for low milk transfer were significant (P: < 0.05) or nearly significant (P:

Immunoblotting can help the diagnosis of ocular toxoplasmosis.

AIMS: To determine whether IgG immunoblotting can improve the diagnosis of ocular toxoplasmosis. METHODS: Samples of serum were tested from patients with ocular lesions that could be caused by toxoplasmosis. All such samples from Scotland and Northern Ireland are usually referred to the Scottish Toxoplasma Reference Laboratory. From questionnaires filled out by the clinicians, two groups of sera were identified: ocular toxoplasmosis (active and quiescent), n = 54 (group 1); and eye disease as a result of other causes, n = 36 (group 2). Control groups were made up of sera from patients with no eye disease and a normal dye test result (< or = 125 IU/ml), n = 16 (group 3); and toxoplasma seronegative, cytomegalovirus (CMV) positive, and herpes simplex virus (HSV) positive sera (group 4), n = 18. RESULTS: Immunoblots with an active pattern could be identified (IgG antibodies against at least four antigens with molecular weight of 6, 20, 22, 23, 25, and 36 kDa). Significantly more of this pattern was found in group 1 (33 of 54; 61.1%) compared with group 2 (nine of 36; 25%) or group 3 (six of 16; 37.5%). Within group 1, significantly more sera with an active pattern had dye test results > or = 65 IU/ml compared with those without. More sera from patients < 30 years of age were found with the active pattern in group 1 compared with group 2. No group 4 sera had active immunoblot patterns. CONCLUSIONS: The immunoblot result adds more support to the diagnosis of ocular toxoplasmosis. In cases where the clinical diagnosis is difficult, immunoblots are particularly indicated; if negative, other causes of eye disease should be sought.

Does delayed perception of the onset of lactation shorten breastfeeding duration?

This longitudinal study evaluated the impact of the timing of maternal perception of the onset of lactation on breastfeeding duration. Breastfeeding mothers who delivered a full-term infant were interviewed daily from day 1 postpartum until the onset of lactation. Women were recontacted to determine the duration of any breastfeeding at 6.7 months postpartum, and if necessary, at 16.2 months postpartum. Cox survival multivariate analyses indicated that among women planning to breastfeed for at least 6 months, those with onset of lactation < 72 hours postpartum were likely to breastfeed longer than their counterparts with a delayed onset of lactation. Median breastfeeding durations were 11.7 months and 3.4 months, respectively (p < 0.00001). Among women who intended to breastfeed for less than 6 months, the timing of the onset of lactation did not influence breastfeeding duration. All analyses controlled for body build, delivery method, employment status, education, parity, and maternal age. These findings suggest that a delayed onset of lactation is likely to be associated with a shorter breastfeeding duration. This relationship, however, was modified by the mother's intended breastfeeding duration.

The relationship between ocular toxoplasmosis and levels of specific toxoplasma antibodies.

The relationship between ocular toxoplasmosis and levels of toxoplasma specific antibodies was examined in 195 patients. Using clinical information collected by questionnaires, patients were divided into: 97 with ocular toxoplasmosis (group 1) and 98 with ocular lesions not due to toxoplasma (group 2). The geometric mean of dye test titres (+/-S.D. natural log titre) in group 1 was 53.2 (+/-0.95) compared with 24.6 (+/-1.11) in group 2 (P < 0.001). Young females tended to have more active lesions compared with young males (P < 0.05). There was an age-dependent difference in dye test titres between the groups (P < 0.001). Group 1 showed a decline in titre with age compared with an increase in group 2. Ocular toxoplasmosis was diagnosed most frequently among 21-30 year olds. More group 1 patients had dye test titres > or = 65 iu/ml than group 2 (P < 0.05). Dye test titres > or = 65 iu/ml support a diagnosis of ocular toxoplasmosis whereas lower titres suggest other causes for eye lesions.

Identification of risk factors for delayed onset of lactation.

OBJECTIVE: To identify infant feeding, socioeconomic, demographic, and delivery-related factors that affect women's self-reported timing of the onset of lactation. DESIGN: Longitudinal survey of women from day 1 postpartum until self-reported onset of lactation. Subjects were interviewed in person on day 1 postpartum, then surveyed daily by telephone regarding infant feeding method, breast symptoms, and perception of whether the onset of lactation had occurred. Medical records were reviewed. SUBJECTS/SETTING: Data were collected from 192 women after they gave birth to a healthy, term singleton. STATISTICAL ANALYSES PERFORMED: chi 2 Analyses were used to identify variables associated with delayed onset of lactation (onset of lactation > or = 72 hours postpartum). Multivariate logistic regression was used to identify the independent association of each significant variable with delayed onset of lactation. RESULTS: Risk factors for delayed onset of lactation included white/Hispanic ethnicity, heavy/obese body build, delivery of offspring by unscheduled cesarean delivery, vaginal delivery with prolonged stage 2 labor, infant birth weight less than 8 lb, and exclusive formula-feeding before the onset of lactation. APPLICATIONS/CONCLUSIONS: Women who are at risk for delayed onset of lactation need additional breast-feeding support during the first week postpartum. During their hospitalization, these women should be instructed about the normal lactation process and the possibility that onset of lactation may occur later than 72 hours postpartum. Frequent nursing should be recommended, as delayed onset of lactation was associated with the lack of infant suckling.

Family-focused pediatric home care.

Family-focused home care is a way to bring medically fragile children home to familiar surroundings and provide them with quality medical care. But the family unit has to make a number of not-so-simple adjustments for this mode of care to work.

A specific radioimmunoassay for the determination of morphine-6-glucuronide in human plasma.

A specific antiserum for morphine-6-glucuronide (M6G) has been raised in a rabbit in response to immunization with a novel hapten:protein conjugate (N-aminobutylnormorphine-6-glucuronide-thyroglobulin). Cross-reactivity with morphine and structurally related compounds was found to be negligible as expected from the nature of this immunogen. Using this antiserum, a simple, rapid and robust radioimmunoassay (RIA) has been developed for determination of M6G in samples of human plasma. The assay has a sensitivity of 0.05 ng/mL using 100 microL sample volumes and affords complete recovery of M6G over the range 2-200 ng/mL. The presence of morphine or morphine-3-glucuronide at concentrations up to 100 times the levels of M6G did not result in any measurable interference. Close agreement was obtained between M6G results obtained using the RIA and a specific high-performance liquid chromatography assay. This RIA offers an attractive alternative to existing methods for the determination of M6G in human plasma and will facilitate further metabolic and pharmacokinetic studies of morphine and M6G in the clinical setting.

Evaluation of a differential radioimmunoassay technique for the determination of morphine and morphine-6-glucuronide in human plasma.

A modified differential radioimmunoassay (RIA) technique for the measurement of morphine and its active metabolite, morphine-6-glucuronide (M6G), in plasma is described. Plasma samples were assayed following appropriate dilution, using a morphine specific antiserum and the results subtracted from those obtained with an antiserum which cross-reacts with both morphine and M6G. The sensitivity of measurement for morphine and M6G was 0.88 and 0.27 nmol l-1, respectively and inter-assay variation ranged from 3.4 to 11.0%. Recovery of morphine and M6G was quantitative over a range of concentrations (1-5000 nmol l-1). The presence of either M6G or morphine-3-glucuronide (M3G) did not affect the recovery of morphine. M6G was quantitatively recovered in the presence of morphine but high concentrations (> 1:20) of M3G caused some overestimation of M6G. Results obtained by differential RIA for both morphine and M6G correlated well with the results of HPLC analysis. The assay has been applied to the measurement of M6G in plasma following its administration to human volunteers.

Annual student report to the American College of Nurse-Midwives.

This article profiles current areas of concern identified by the student membership at the 38th annual American College of Nurse-Midwives convention in June. Communication, financial aid, education, and practice are identified as topics affecting past, present, and future students, as well as the current membership of certified nurse-midwives. Recommendations are offered and the College is petitioned to address these substantial issues that directly impact the membership.

Inhibition of Water Splitting Increases the Susceptibility of Photosystem II to Photoinhibition.

Photosystem II (PSII)-enriched membrane particles were isolated from peas (Pisum sativum L.) and treated in several different ways to inhibit the water oxidation reactions, but not reaction center function itself, as judged by the light-induced rate of reduction of 2,6-dichlorophenol indophenol with and without the artificial electron donor, diphenyl carbazide. It was shown that such treatments increased the susceptibility of the PSII-enriched membranes to photoinhibition. This trend was further observed if 2,6-dichlorophenol indophenol was present during the illumination with photoinhibitory light. On the other hand, protection against the enhanced photoinhibition was found when the water-splitting activity was reconstituted or when the artificial electron donor diphenyl carbazide was present during the preillumination. The results indicate that irreversible photodamage occurred within the PSII reaction center as a consequence of illumination with strong light and that the rate of this damage was enhanced under conditions that are expected to give rise to a photoaccumulation of oxidizing species such as P680(+) on the donor side of PSII. This mechanism of photoinhibitory damage occurred under both aerobic and anaerobic conditions.

Effect of Cold Treatments on the Binding Stability of Photosystem II Extrinsic Proteins and an Associated Increase in Susceptibility to Photoinhibition.

When pea plants (Pisum sativum L. cv Feltham First) are subjected to freezing conditions (-18 degrees C) followed by a thaw to 18 degrees C, there is a significant inhibition of water-splitting capacity judged by the rate of light-induced reduction of 2,6-dichlorophenol indophenol using isolated thylakoid membrane fragments enriched in photosystem II (PSII). The freeze-thaw-induced inhibition of water-splitting activity has been correlated with the loss of the 17- and 23-kilodalton extrinsic protein of PSII and with a weakening of the binding of the 33-kilodalton protein. There was no apparent loss of bound manganese. Addition of 10 millimolar CaCl(2), however, allowed a full recovery of the water-splitting activity of these modified PSII-enriched particles. The freeze-thaw-induced changes in the organization and functional capacity of PSII was found to increase its susceptibility to photoinhibition in agreement with the concepts presented in the accompanying paper, that oxidative damage can occur within the PSII reaction center as a consequence of extending the lifetime of P680(+).

Comparison of the D1/D2/cytochrome b559 reaction centre complex of photosystem two isolated by two different methods.

Photosystem 2 reaction centre complexes prepared either by solubilisation with Triton X-100 and subsequent exchange into dodecyl maltoside or by a procedure involving a combination of dodecyl maltoside and LiClO4, were characterised in terms of chlorophyll a, pheophytin a, beta-carotene and cytochrome b559 content. Time-resolved chlorophyll fluorescence decay kinetics were measured using both types of complexes. Our data show that the isolated photosystem two reaction centre complex contain, for two pheophytin a molecules, close to six chlorophyll a, two beta-carotene and one cytochrome b559. No major differences were observed in the composition or the kinetic characteristics measured in the samples prepared by the different procedures. Time-resolved fluorescence measurements indicate that more than 94% of the chlorophyll a in both preparations is coupled to the reaction centre complex.