PDV-based estimation of ejecta particles' mass-velocity function from shock-loaded tin experiment.

A metallic tin plate with a given surface finish of wavelength λ ≃ 60 µm and amplitude h ≃ 8 µm is explosively driven by an electro-detonator with a shock-induced breakout pressure PSB = 28 GPa (unsupported). The resulting dynamic fragmentation process, the so-called "micro-jetting," is the creation of high-speed jets of matter moving faster than the bulk metallic surface. Hydrodynamic instabilities result in the fragmentation of these jets into micron-sized metallic particles constituting a self-expanding cloud of droplets, whose areal mass, velocity, and particle size distributions are unknown. Lithium-niobate-piezoelectric sensor measured areal mass and Photonic Doppler Velocimetry (PDV) was used to get a time-velocity spectrogram of the cloud. In this article, we present both experimental mass and velocity results and we relate the integrated areal mass of the cloud to the PDV power spectral density with the assumption of a power law particle size distribution. Two models of PDV spectrograms are described. The first one accounts for the speckle statistics of the spectrum and the second one describes an average spectrum for which speckle fluctuations are removed. Finally, the second model is used for a maximum likelihood estimation of the cloud's parameters from PDV data. The estimated integrated areal mass from PDV data is found to agree well with piezoelectric results. We highlight the relevance of analyzing PDV data and correlating different diagnostics to retrieve the physical properties of ejecta particles.

Management and outcome of triplet pregnancy.

The parameters involved in obstetrical follow-up of triplet pregnancies were evaluated in a retrospective study between 1975-1993 of the follow-up of 91 triplet pregnancies. During this long interval of time, many changes in management of triplets occurred. Considering these differences, two periods in the present study were compared: 1975-1986, which consists of a previously published retrospective analysis of 21 triplet pregnancies; and 1987-1993, during which the modalities of the 7-year follow-up described previously were applied to 70 triplet pregnancies. No improvement was observed between the two periods. Nineteen pregnancies were spontaneous. Thirty-seven allowed treatment with ovulation induction agents and 35 were due to in vitro Fertilization. Early diagnosis of multiple pregnancies allows installation measures for the prevention of prematurity. Management, initiated upon diagnosis, included home rest and a weekly follow-up at home by a midwife every week. Monthly consultations and ultrasounds were performed at the hospital. Hospitalization was not systematic but was done in cases of maternal complications. The mean term for the diagnosis of triplet pregnancy was 13.9 +/- 5.3 weeks. The mean gestational age was 33.4 weeks; 90% of the deliveries were by cesarean section. The mean weight of the neonates was 1716 g. The mean Apgar score at 1 and 5 m was 7.7 and 9.3, respectively. The perinatal mortality was 80 per 1000. The main neonatal complications resulted from prematurity. Authors compared rates of Hyaline Membrane Disease in infants of patients treated with corticosteroids and of patients who were not. Hyaline Membrane Disease occurred in 13% of the corticotherapy group and in 31% of the untreated group. The present study supports systematic corticotherapy between 28 and 34 weeks for triplet pregnancies.

Biparietal diameter in twins at gestational weeks 18-32. Differences and similarities. Le Groupe Romulus.

OBJECTIVE: To examine twin similarities on biparietal diameter (BPD) measurements by zygosity (monozygotic [MZ] and dizygotic [DZ]) and chorionicity (monochorionic [MC] and dichorionic [DC]) and their evolution during pregnancy. METHOD: A sample of 54 pairs of twins (43 DZ sets, 11 MZ sets [7 MC and 4 DC]) was constructed using retrospective data. Despite the small sample size, our data were complete, and, for the first time we measured different fetal parameters on digital ultrasound images outside routine examination. The intraexaminer and interexaminer reliability of BPD measurement was significant (r = .95, P < .001). RESULTS: In this study, developmental results indicate significant linear regression coefficient (R) through the whole period of gestation (r = .96, P < .001), though product moment correlations comparing the periods of gestation two by two are weaker. The distribution of BPD values was slightly wider at the 28th week and markedly wider at the 32nd week than that at the 18th and 23rd weeks. The intraclass correlations of DZ and MZ (MC and DC) twins were examined at the 18th, 23rd, 28th and 32nd weeks of amenorhea. The intraclass correlations of DZ twins were significant through the whole period of gestation (r = .45, P = .001; r = .27, P = .04; r = .36, P = .008; and r = .42, P = .002, respectively), whereas the intraclass correlations of MZ twins were significant only at the 18th, 23rd and 28th weeks (r = .73, P = .002; r = .69, P = .005; r = .49, P = .047, respectively). We found significant within-variance differences not only between DZ and DC-MZ but also between DC-MZ and MC-MZ in late gestation. CONCLUSION: Our analysis of twin BPD development demonstrated that zygosity and chorionicity type are both important determinants of twin fetal development.

Prenatal exposure to diethylstilbestrol and the mother-daughter relationship.

The psychological consequences resulting from the exposure to diethylstilbestrol (DES), a non-steroidal oestrogen, on the mother-daughter relationship are studied using semi-directive interviews with 43 daughters and 7 mothers treated with DES during their pregnancies. These women referred to gynaecological consultation for DES-related problems. The daughters, exposed to DES during their foetal life, learned about DES after a pregnancy mishap (35% of the cases), or by accident (65% of the cases). All of them were shocked when the existence of DES and its side effects were revealed to them. Consequences on the mother-daughter relationship were absent in 60% of the cases, favourable in 20%, and negative in 20%. Five percent of the women showed hostility towards the medical practice, but 65% were not suspicious of the drugs administered to them during their pregnancies. For 64% of them, administration of DES to their mother had been kept secret. In 7 out of 50 cases, parents alone came for medical assistance in order to manage the secret. Exposure to DES may reveal pre-existing difficulties not only between the mother and the daughter, but sometimes beyond from generation to generation.

Stability of drinking prior to alcoholism treatment.

This study assessed how many months of pretreatment drinking data would represent a stable baseline. Fifty-one couples were interviewed using the time-line follow-back interviewing procedure to obtain 365 days of pretreatment drinking data. The pattern (binge, episodic, steady) and frequency of drinking did not differ when comparing 30 days prior to treatment with the rest of the year. However, there were significantly more abstinent days in the last 3 months than in the remainder of the pretreatment year. Implications for baseline data collection in alcoholism treatment research are discussed.