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OBJECT The Management of Myelomeningocele Study (MOMS) was a multicenter randomized trial comparing the safety and efficacy of prenatal and postnatal closure of myelomeningocele. The trial was stopped early because of the demonstrated efficacy of prenatal surgery, and outcomes on 158 of 183 pregnancies were reported. Here, the authors update the 1-year outcomes for the complete trial, analyze the primary and related outcomes, and evaluate whether specific prerandomization risk factors are associated with prenatal surgery benefit. METHODS The primary outcome was a composite of fetal loss or any of the following: infant death, CSF shunt placement, or meeting the prespecified criteria for shunt placement. Primary outcome, actual shunt placement, and shunt revision rates for prenatal versus postnatal repair were compared. The shunt criteria were reassessed to determine which were most concordant with practice, and a new composite outcome was created from the primary outcome by replacing the original criteria for CSF shunt placement with the revised criteria. The authors used logistic regression to estimate whether there were interactions between the type of surgery and known prenatal risk factors (lesion level, gestational age, degree of hindbrain herniation, and ventricle size) for shunt placement, and to determine which factors were associated with shunting among those infants who underwent prenatal surgery. RESULTS Ninety-one women were randomized to prenatal surgery and 92 to postnatal repair. The primary outcome occurred in 73% of infants in the prenatal surgery group and in 98% in the postnatal group (p < 0.0001). Actual rates of shunt placement were only 44% and 84% in the 2 groups, respectively (p < 0.0001). The authors revised the most commonly met criterion to require overt clinical signs of increased intracranial pressure, defined as split sutures, bulging fontanelle, or sunsetting eyes, in addition to increasing head circumference or hydrocephalus. Using these modified criteria, only 3 patients in each group met criteria but did not receive a shunt. For the revised composite outcome, there was a difference between the prenatal and postnatal surgery groups: 49.5% versus 87.0% (p < 0.0001). There was also a significant reduction in the number of children who had a shunt placed and then required a revision by 1 year of age in the prenatal group (15.4% vs 40.2%, relative risk 0.38 [95% CI 0.22–0.66]). In the prenatal surgery group, 20% of those with ventricle size < 10 mm at initial screening, 45.2% with ventricle size of 10 up to 15 mm, and 79.0% with ventricle size ≥ 15 mm received a shunt, whereas in the postnatal group, 79.4%, 86.0%, and 87.5%, respectively, received a shunt (p = 0.02). Lesion level and degree of hindbrain herniation appeared to have no effect on the eventual need for shunting (p = 0.19 and p = 0.13, respectively). Similar results were obtained for the revised outcome. CONCLUSIONS Larger ventricles at initial screening are associated with an increased need for shunting among those undergoing fetal surgery for myelomeningocele. During prenatal counseling, care should be exercised in recommending prenatal surgery when the ventricles are 15 mm or larger because prenatal surgery does not appear to improve outcome in this group. The revised criteria may be useful as guidelines for treating hydrocephalus in this group.

Objective Non-invasive fetal Rhesus (Rh) D genotyping, using cell-free fetal DNA (cffDNA) in the maternal blood, allows targeted antenatal anti-RhD prophylaxis in unsensitized RhD-negative pregnant women. The purpose of this study was to determine the cost and benefit of this approach as compared to routine antenatal anti-RhD prophylaxis for all unsensitized RhD-negative pregnant women, as is the current policy in the province of Alberta, Canada. Methods This study was a decision analysis based on a theoretical population representing the total number of pregnancies in Alberta over a 1-year period (n = 69 286). A decision tree was created that outlined targeted prophylaxis for unsensitized RhD-negative pregnant women screened for cffDNA (targeted group) vs routine prophylaxis for all unsensitized RhD-negative pregnant women (routine group). Probabilities at each decision point and costs associated with each resource were calculated from local clinical and administrative data. Outcomes measured were cost, number of women sensitized and doses of Rh immunoglobulin (RhIG) administered. Results The estimated cost per pregnancy for the routine group was 71.43 compared with 67.20 Canadian dollars in the targeted group. The sensitization rates per RhD-negative pregnancy were equal, at 0.0012, for the current and targeted programs. Implementing targeted antenatal anti-RhD prophylaxis would save 4072 doses (20.1%) of RhIG over a 1-year period in Alberta when compared to the current program. Conclusions These data support the feasibility of a targeted antenatal anti-RhD prophylaxis program, at a lower cost than that of the existing routine prophylaxis program, with no increased risk of sensitization. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.

To measure nitric oxide (NO) levels, as assessed by methemoglobin (MetHb), in the umbilical cord arterial blood of women with preeclampsia (PE), normotensive pregnancies with intrauterine growth restriction (IUGR,10th percentile for birth weight) and normotensive pregnancies with appropriate for gestational age (AGA) infants.Prospective analysis of MetHb levels in umbilical arterial blood of pregnancies with PE, normotensive IUGR and normotensive AGA infants using spectrophotometry. Exclusion criteria included cigarette smoke exposure, hemolytic disorders, chronic hypertension, any significant medical illness and medications affecting NO or MetHb levels.There were 42 women in the PE, 42 in the AGA and 37 in the IUGR group. Maternal age, mode of delivery, gravidity, parity and infant gender were similar in the three groups. MetHb levels were significantly lower in the IUGR group compared to the AGA group (p 0.01). MetHb levels, while higher in the PE group compared to the AGA group, did not reach statistical significance.Our data suggests that NO may play a key role in the pathogenesis of IUGR. We also, for the first time, provide information on umbilical arterial MetHb levels in PE, normotensive IUGR and normotensive AGA pregnancies.

Objective To determine pregnancy outcomes of patients who present with Stage I twin-to-twin transfusion syndrome (TTTS). Methods This was a retrospective review of all patients with TTTS referred to our institution between January 2005 and December 2006. Quintero criteria were used for staging. Laser ablation was not offered to patients with Stage I disease. Results A total of 155 twin pregnancies were evaluated for TTTS during this period. Forty-two met the criteria for Stage I and were included in the analysis. The overall survival to discharge was 82%. The mean gestational age at the time of consultation was 20.9 ± 0.4 weeks. A total of 23 cases (54.8%) underwent amnioreduction. Progression of TTTS requiring invasive therapy occurred in four cases. The mean gestational age at delivery was 32.5 ± 0.62 weeks. When divided according to use of amnioreduction, there were no statistically significant differences between the groups for gestational age at delivery or for birth weight. Those Stage I cases with a CHOP cardiovascular score of 5 or higher delivered almost 3 weeks earlier than the remainder of the cohort. Conclusions Progression of TTTS beyond Stage I occurred in only 9.5% of the cohort. Mean gestational age at delivery and survival to discharge did not differ between Stage I patients and those treated with placental laser ablation for more advanced stages of TTTS. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.

While the past 15 years have seen rapid development of permeable reactive barriers and other in situ systems for the treatment of groundwater contamination, assessing performance has not received the same attention. In some cases the long-screened monitoring wells installed as part of initial site investigations are used to monitor treatment, while in others a few additional wells may be installed to serve as sentinels. Performance is assessed based on differences in contaminant concentrations, which is unreliable where plumes are spatially complex and/or temporally unstable. In this work, a standard concentration performance metric is compared with that based on mass flux, using data collected during an evaluation of a discontinuous aerobic biobarrier treating a near-source (and spatially complex) BTEX plume. The data were derived from high-resolution multilevel samplers installed up- and down-gradient of the treatment system. Concentrations in screened monitoring wells of various lengths were approximated by interval-weighted concentrations from these multilevels. The accuracy of the different performance assessment methods was measured based on estimated uncertainty generated as a result of observed spatial plume complexity. While more data intensive, mass flux proved to be a more reliable performance metric. Assessment using data from few long-screened wells could not reliably match that of the flux fences, but did come within acceptable limits when the number of wells approached the number of multilevels.

Objectives In the fetus with a structurally normal heart, two conditions – giant chest mass, such as congenital cystic adenomatoid malformation (CCAM), and twin–twin transfusion syndrome (TTTS) – alter ventricular loading conditions and may result in cardiovascular compromise. The aim of this study was to elucidate the mechanism of cardiovascular dysfunction by comparing geometryindependent, Doppler flow-derived measures of ventricular performance in fetuses with altered loading conditions vs. those in normal fetuses. Methods Doppler flow-derived measures of myocardial performance index (MPI) as described by Tei, ventricular ejection force as described by Isaaz, and combined cardiac output (CCO) were obtained by echocardiography in fetuses with a normal cardiovascular system (n = 76) or CCAM (n = 36) and fetal partners with TTTS (n = 22). Results In the CCAM group, systolic performance as evidenced by the ejection forces was preserved, right ventricular (RV) MPI was increased and CCO diminished, suggesting diastolic dysfunction and poor filling secondary to cardiac compression and a tamponade effect. In TTTS, recipient twins exhibited greater left ventricular (LV) ejection forces and higher CCO than donor twins, and had abnormal RV and LV MPI, reflecting increased preload, preserved left systolic performance, but diastolic dysfunction. Donor twins had diminished ejection forces and CCO in comparison with normal controls and recipient partners, reflecting hypovolemia. Conclusions In both CCAM and recipient twins of the TTTS, diastolic dysfunction plays a significant role in the pathophysiology of each disorder and precedes changes in systolic performance. Measures of ventricular performance can help elucidate poorly understood mechanisms of cardiovascular compromise in the developing fetus. Copyright  2007 ISUOG. Published by John Wiley & Sons, Ltd.

Purpose To determine the feasibility of high-dose intra-arterial (IA) cisplatin and concurrent radiation therapy (RT) for head and neck squamous cell carcinoma in the multi-institutional setting (Multi-RADPLAT). Patients and Methods Eligibility included T4 squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx. Patients received cisplatin (150 mg/m2 IA with sodium thiosulfate 9 g/m2 intravenous [IV], followed by 12 g/m2 IV over 6 hours, weekly for 4 weeks) and concurrent RT (70 Gy, 2.0 Gy/fraction, daily for 5 days over 7 weeks). Between May 1997 and December 1999, 67 patients from three experienced and eight inexperienced centers were enrolled, of whom 61 were eligible for analysis. Results Multi-RADPLAT was feasible (ie, three or four infusions of IA cisplatin and full dose of RT) in 53 patients (87%). The complete response (CR) rate was 85% at the primary site and 88% at nodal regions, and the overall CR rate was 80%. At a median follow-up of 3.9 years for alive patients (range, 0.9 to 6.1 years), the estimated 1-year and 2-year locoregional tumor control rates are 66% and 57%, respectively. The estimated 1-year and 2-year survival rates are 72% and 63%, respectively. The estimated 1-year and 2-year disease-free survival rates are 62% and 46%, respectively. The rates of grade 4 and 5 toxicities at the experienced and the inexperienced institutions were 14% and 0% v 47% and 4%, respectively. Conclusion This intensive treatment regimen for head and neck cancer is feasible and effective in a multi-institutional setting.

In a companion paper, a friction model for isothermal forging is described. Extension to a general hot forging case requires consideration of heat transfer across the tooling/workpiece interface, since a chilling of the workpiece by the dies will have evolving material properties that can significantly affect the forging operation. This is a complicated problem, since the film thickness, surface roughness and hence fractional contact area can vary with respect to die location and time in a forging operation. Heat transfer across the tooling/workpiece interface is a complex combination of heat transfer through the asperity contacts and heat transfer across the lubricant film. Like friction, this evolves as deformation proceeds. This paper presents a thermal interface model for forging operations where a temperature difference exists between the workpiece and tooling, which is the most common situation in forging. The model considers heat flow through direct asperity contacts as well as heat flow through the lubricant film, and calculates an effective heat transfer coefficient based on lubricant, material and process parameters. The model is implemented as a user routine in a popular commercially available finite element code, DEFORM 2D. The model yields predictions that match previous experimental observations. Sample hot forging simulations are presented for upsetting, ring compression, spike test and embossing die configurations for Ti-6Al-4V and Rene-88, two popular aerospace alloys.

Air sampling directly onto a methicillin-resistant Staphylococcus aureus (MRSA) selective agar was performed at six locations three times weekly over a period of 32 weeks in a new, initially MRSA-free Intensive Care Unit to examine if MRSA is present in air sample cultures and, if so, whether it is affected by the number of MRSA colonized patients present. A total of 480 air samples were collected on 80 days. A total of 39/480 (8.1%) samples were found to be MRSA positive of which 24/160 (15%) positive air samples were from the single rooms, where MRSA colonised patients were isolated, and 15/320 (4.7%) were from the open bed areas. A significant correlation was found between the daily number of MRSA colonized or infected patients in the Unit and the daily number of MRSA positive air samples cultures obtained (r2=0.128; P

In the practice of clinical genetics chromosomal aneuploidy in both mosaic and nonmosaic forms has long been recognized as a cause of abnormal prenatal and postnatal development. Traditionally, cytogenetic analysis of cultured lymphocytes has been used as a standard test for detection of constitutional aneuploidies. As lymphocytes represent only one lineage, chromosomal mosaicism expressed in other tissues often remains undetected. The purpose of this study was to assess the utilization of molecular cytogenetic analysis for detection of chromosomal aneuploidy in placental tissues. Using placentas from 100 pregnancies with viable nonmalformed livebirths, both trophoblast and chorionic stroma were analyzed using comparative genomic hybridization (CGH). In all cases with an indication of chromosomal imbalance by CGH, fluorescence in situ hybridization (FISH) analysis was performed to confirm the presence of aneuploidy. To differentiate between constitutional aneuploidy and confined placental mosaicism (CPM), amniotic membrane was analyzed by CGH and FISH techniques. Our results demonstrated five placentas with CPM for chromosomes 2, 4, 12, 13, and 18, respectively, and two constitutional nonmosaic aneuploidies (47,XXX and 47,XXY). Molecular cytogenetic studies of human placental tissues enables easy analysis of both embryonic (amnion) and extraembryonic (chorion) cell lineages. Detection at birth of chromosomal defects affecting intrauterine placental and fetal development is important because these chromosomal defects may continue to have an influence on postnatal development. Am. J. Med. Genet. 92:281–284, 2000. © 2000 Wiley-Liss, Inc.

Inspection of 1100-H14 and 5052-0 aluminum alloy surfaces deformed in tension, sheet forming, and rolling with a thick lubricant film indicated that similar mechanisms were involved in the roughening process. The predominant mechanism was associated with the orientation of slip systems in adjacent grains leading to mismatch strains at the grain boundaries. The emergence of slip planes played a lesser role in the roughening process. A roughening model that assumed a spatial hardness variation was developed. Theoretical predictions of the dependence of the Ra surface roughness with bulk strain, based on micro-hardness measurements, show excellent agreement with experiment.

To describe the anesthetic and obstetrical management of a pregnant patient with co-existing Familial Hypokalemic Periodic Paralysis (FHPP) and Wolff-Parkinson-White syndrome (WPW).A 29 yr-old primigravida with FHPP and WPW presented to the antenatal clinic at 18 wk gestation, for consideration of her anesthetic and obstetrical management during labour and delivery. A plan was constructed to avoid the known precipitating factors of FHPP including carbohydrate loading, cold, mental stress and exercise, which could lead to acute attacks of weakness. She presented for induction of labour at 41 wk and three days. An epidural catheter was sited early in labour. The second stage was limited to less than one hour. She had a rotational forceps delivery for which the epidural was extended to provide anesthesia. A healthy male baby was delivered. The patient made an uncomplicated recovery and was discharged home on the second postnatal day. The peripartum potassium was kept within the normal range with intravenous as well as oral potassium supplementation. No arrhythmias were reported.Assessment of the patient at an early stage in her pregnancy allowed for a multidisciplinary approach to this patient and her medical problems. A plan was made to avoid known precipitating factors during labour, delivery and the postnatal period well in advance of her date of confinement, leading to a successful outcome for mother and child.

Research over the last 20 years has considerably changed the understanding of the natural history and prognosis for individuals with a diagnosis of sex chromosome aneuploidy (SCA). A cross-sectional retrospective analysis of factors influencing parental decisions following a prenatal diagnosis of SCA during the time period of 1971-97 was performed. The records of 169 fetuses with a prenatal karyotype of 45,X, 47,XXX, 47,XXY, and 47,XYY were reviewed. Mosaic karyotypes for SCA were also included. Information reviewed involved: parental decision, the type of SCA, the presence or absence of mosaicism, the presence or absence of a fetal anomaly diagnosed by ultrasound examination, indication for prenatal diagnosis, prenatal procedure performed, parental age, marital status, previous pregnancy history, family history, ethnicity, religion, education, and profession. A significant correlation was found between the decision to continue a pregnancy and the type of SCA and the presence of fetal abnormalities on ultrasound examination. In addition, this study examined differences in parental decisions over time for the years in question. A statistically significant trend was observed with a higher rate of pregnancy continuation in the more recent years.

A model of a secondary hydrodynamic lubrication mechanism, which is called micro-pool or micro-plasto hydrodynamic lubrication, has been developed. It shows that, with sufficiently high viscosity and sliding speed, the lubricant trapped in the micro-pools between the tool and workpiece can be drawn into the interface. The friction force is either increased or decreased, depending on the viscosity and sliding speed. Without bulk stretching, the product of the lubricant viscosity and sliding velocity can be used as an index to indicate whether or not micro-pool lubrication will occur. Stretching the workpiece may make a strong influence not only on the thickness of the permeating film but also on the asperity contact area.

The purpose of this study was to identify risk factors for fetal loss and other pregnancy complications associated with genetic amniocentesis. Data were acquired in the Canadian Early Amniocentesis Trial (CEMAT), a multicentered (12) prospective, randomized trial comparing continuous ultrasound-guided early amniocentesis (EA) and mid-trimester amniocentesis (MA) (CEMAT Group, 1998). Details of the procedure were recorded and analysed by allocation (EA versus MA), operator and centre, and correlated with pregnancy outcome. A total of 62 spontaneous pregnancy losses occurred between the procedure and 20 weeks' gestation among the 3691 patients who received their procedures within the allocated window (EA=53/1916, MA=9/1775). Technical factors correlating with these losses included procedures 'judged to be difficult' by the operator, and post-procedure amniotic fluid leakage or bleeding. Maternal risk factors included maternal hypertension (fetal loss 11. 1 per cent, compared with non-hypertensive women, 2.6 per cent) increased body mass index (BMI) and gravidity of three or greater. Allocation to EA was predictive of fetal loss, as well as failed procedure, multiple needle insertions, amniotic fluid leakage, failed culture and talipes equinovarus, in excess compared with MA. In conclusion, in this large prospective randomized trial evaluating amniocentesis, specific maternal, fetal and procedural variables were found to be predictive of fetal loss and adverse pregnancy outcome. Performing amniocentesis before 13 weeks' gestation (EA) was the major predictive factor for adverse outcome. These data suggest that first-trimester chorionic villus sampling (CVS) and MA will likely remain the invasive procedures of choice for evaluation of fetal karyotype.

The authors suggested a boundary friction model which treats the combined influence of surface roughening (due to inhomogeneous deformation) and surface smoothing (due to asperity flattening) on the real area of contact in the presence of plastic strain. Predictions using the new model for sheet metal forming indicate that the friction coefficient tends to decrease with strain for low pressures (when roughening is of dominant importance) and tends to increase with strain for high pressures (when asperity flattening prevails). This behavior was confirmed experimentally by friction measurements for 6022-T4 aluminum sheet stretched over A2 steel pins of different diameters with a commercial lubricant. Average coefficients of friction predicted by the model were in good agreement with those measured experimentally. Presented at the 53rd Annual Meeting in Detroit, Michigan May 17–21, 1998

In the past, many different modes of vibration and causes of rolling chatter have been presented, yet no complete and clear picture of the basic mechanics emerged. In order to control chatter in cold rolling operations, a much better understanding of the basic mechanics of the problem is required. To provide, therefore, a ground work for developing such a basic understanding, in this paper, existing models of a mill stand as well as of the rolling process in the open literature are presented. In addition, existing chatter models, which are formulated to investigate chatter as the consequence of the interaction between the structural dynamics of the mills and the dynamics of the rolling process, are also reviewed.

The central problem of the analysis and prevention of chatter in rolling operations is in understanding the conditions which lead to dynamic instability. By analogy with metal cutting operations, it appears that a few basic mechanisms may be responsible for the occurrence of self-excited vibrations in rolling. The three most significant mechanisms are: negative damping, mode-coupling and regeneration. In this paper, negative damping and mode-coupling are considered separately in an “artificial” manner to make inroads toward a better basic understanding of rolling instability.

This paper presents the development of a new dynamic model of the rolling process which provides estimates of the variations in exit gage, strip speed and tension at entry and exit, rolling force and rolling torque in response to variations in roll separation as well as the rate of change of the roll spacing. This two-dimensional dynamic model employs the Tresca friction factor approach instead of Amontons-Coulomb friction law.

This paper presents the results of dynamic rolling experiments examining the variations in rolling force, back tension and roll gap in response to a sinusoidal dynamic component of various frequencies being superimposed on the roll gap or back tension. Comparisons between the experimental results and the corresponding simulation results are also presented to investigate the validity of the new dynamic model of the rolling process presented in Part 1 of this paper.

To assess anxiety levels in women undergoing early (EA) versus mid-trimester amniocentesis (MA) for prenatal diagnostic testing. Method: Women randomized to EA or MA at 9–11 weeks gestation completed an initial questionnaire, the Spielberger State Anxiety Inventory (STAI) and the Centre for Epidaemiological Studies Depression Scale (CES-D). Prior to and after the procedure, subjects completed a questionnaire and the STAI. Results: All subjects had increased anxiety levels prior to the procedure with a decrease following the procedure. There were no significant differences in pre-test anxiety levels between women receiving EA or MA. Women who received results back earlier in pregnancy had a significantly greater decrease in anxiety (p < 0.01). Women who had genetic terminations or miscarriages after the prenatal testing still tended to be positive about prenatal diagnosis and seemed to prefer earlier procedures.

Thermohydrodynamic lubrication is complicated by the multiplicity of heat transfer paths from the site of dissipation to the surroundings. This has impeded a general understanding of thermohydrodynamic phenomena. The method of lumped variables is applied to a simple slider bearing (as an example) to explore thermohydrodynamic lubrication. This approach leads to a better understanding of the interplay between the different modes of heat transfer and the influence of the associated temperature rises on performance, and how this can be captured by the use of appropriate non-dimensional measures. Such measures also allow the mapping of the problem into a set of regimes characterized by the relative importance of different heat transfer modes.

An alternative average Reynolds equation for use under conditions of large fractional contact area is proposed. The flow factors for this form of the equation are calculated for a variety of longitudinal surfaces and the results are shown to be relatively insensitive to the initial height distribution. Pressure and shear flow factors for the Christensen height distribution and a variety of Peklenik surface pattern parameters are also derived from the work of Patir and Cheng, Lo and Tripp. These are represented by semi-empirical equations over the full range of contact conditions. The implications of the results, with respect to the lubrication of metal forming processes, is discussed.

The tribological aspects of cold metal forming processes is reviewed. Special attention is paid to rolling and stamping operations as these are typical of bulk forming and sheet forming processes, respectively, and are the most important commercial processes. It is shown that a better understanding of tribological fundamentals, as applied to cold metal forming, can result in better lubrication systems and process models.

A retrospective study of cases of fetal anomalies associated with a normal karyotype was conducted (1) to evaluate the accuracy of prenatal diagnosis; and (2) to assess two different tools to assist in determining the correct diagnosis. A total of 201 charts were reviewed. The accuracy of the prenatal diagnosis was assessed subjectively by one physician. The London Dysmorphology Database and a locally developed non-computerized tool (Appendix) were assessed retrospectively using 36 test cases. The population studied presented a spectrum of 97 different groups of single (67%) or multiple (33 %) anomalies. The prenatal diagnosis was accurate in 57% of the cases. The two proposed tools generated an average of 146 and 15 different diagnoses, respectively and the correct one in 26 and 22 of the 36 test cases. The two studied tools have the potential to generate a differential diagnosis in the presence of a fetal anomaly prior to and following normal karyotype analysis. The non-computerized tool presents the advantages of listing antenatal features and creating a shorter differential diagnosis list with a minimal decrease in the identification rate of the correct diagnosis. Its use should be studied prospectively. Copyright © 1997 International Society of Ultrasound in Obstetrics and Gynecology

Emulsions and slurries are commonly encountered in tribology problems. The dispersed phase in the mixture plays an important role in lubrication or wear, but the mechanisms of particle capture by two surfaces have never been well understood. While no similar models have been proposed for slurries, emulsions researchers have attributed lubrication mechanisms to a `plate out' theory through which oil separates from the emulsion and coats the exposed metal surfaces. Observations of particle behavior by Nakahara et al. ( ASME J. Tribol., 110 (1988) 344–353) cast doubt on this theory; particles very close to the tooling were rejected and played no part in the lubrication process. Further, the behavior of a particle depended greatly on its size. This paper offers a potential explanation for this behavior through a computational fluid dynamics model of a rigid particle in an inlet zone. A particle in such a flow field is found to cross streamlines to an equilibrium position a certain distance from the tooling or workpiece. This segregation location is related to the particle size with the same trends of particle penetration as observed by Nakahara et al. The theory applies to emulsion lubrication, slurry lubrication and wear involving solid particles suspended in a liquid.

The aim of this study was to determine the prenatal fetal pyelectasis which requires postnatal evaluation. This was a retrospective analysis involving 65 infants with complete urological follow-up; 59 had shown prenatal evidence of pyelectasis using previously published standards. Males were more common in both the normal (75 per cent) and the abnormal (77 per cent) postnatal outcome groups. Unilateral prenatal lesions were less common than bilateral, but had significant postnatal pathology in 47 and 26 per cent, respectively (n.s.). Persistent dilatation was likely to be associated with postnatal pathology. A 6 mm threshold of dilatation predicted the 19 infants with significant postnatal pathology. The majority of fetuses with pyelectasis in the study had normal outcomes, with males often showing 'transitory pyelectasis'. A repeat prenatal scan at 30-40 weeks' gestation is recommended for all fetuses where 6 mm or more of renal pelvic dilatation is detected prior to 28 weeks. Postnatal follow-up is required for persistent pyelectasis.

The present study provides detailed neonatal and congenital malformation follow-up from 695 women enrolled in a prospective randomized multicenter study comparing the safety and accuracy of early (11-12 weeks of gestation) and midtrimester amniocentesis (15-16 weeks of gestation). No differences were found for total pregnancy loss (difference 0.4%; CI -3.6 to 4.4%), obstetrical or neonatal outcome. The incidence of congenital anomalies was 2.4 and 2.6% for the early amniocentesis and midtrimester amniocentesis groups, respectively. Respiratory problems were present in 2.1 and 1.6%, respectively. Musculoskeletal problems were present in 0.9 and 2.4%, respectively. It must be emphasized that before early amniocentesis can be considered as an alternative to midtrimester amniocentesis or chorionic villus sampling, careful evaluation of any fetal effects must be considered and further large randomized trials are necessary.

Prenatal diagnosis by chorionic villus sampling (CVS) documents placental chromosomal mosaicism in approximately 2% of viable pregnancies at 9-12 weeks of gestation and can involve various chromosomes and placental cell lineages. Confined placental mosaicism (CPM) is the result of postzygotic mitotic errors occurring in either diploid or trisomic zygotes. With trisomic zygote rescue, depending on the parental origin of the chromosome which is lost, uniparental disomy (UPD) or biparental disomy (BPD) may arise [Kalousek et al., Am J Hum Genet 52: 8-16, 1993]. In this paper, we present 14 pregnancies which were diagnosed by CVS as mosaic trisomy 7. All follow-up amniocenteses showed a normal diploid karyotype. Using both classical cytogenetics and interphase analysis, studies of term placentae showed variable levels of trisomy 7. DNA analysis was performed in nine cases to determine whether the diploid fetus had BPD 7 or UPD 7. Fetal UPD 7 was present only in one case; in eight other cases biparental inheritance was demonstrated. DNA analysis to establish the origin of trisomy 7 in the placenta was fully informative in six cases. One trisomy resulted from a meiotic error and was associated with fetal UPD 7, while the rest were somatic in origin. It is difficult to compare the effect of CPM for trisomy 7 to other trisomies confined to the placenta, as for most chromosomes there are few available cases. It appears that intrauterine fetal growth is not greatly affected by the presence of a trisomy 7 cell line in the placenta. This finding is in contrast to the serious effect of high levels of trisomy 16 within the placenta on fetal intrauterine growth in a series of well-documented cases of CPM 16 [Kalousek et al. 1993].

Forms of 2,4-dichlorophenoxyacetic acid (collectively known as 2,4-D) are herbicides used to control a wide variety of broadleaf and woody plants. Subchronic toxicity studies in rats were conducted on three forms of 2,4-D: the parent form, 2,4-D acid; 2,4-D dimethylamine salt (DMA); and 2,4-D 2-ethylhexyl ester (2-EHE). Doses in the subchronic studies (on an acid equivalent basis) were 0, 1, 15, 100, and 300 mg/kg/day. Major treatment related findings in the three studies included decreases in red cell mass, decreases in T3 and T4 levels, decreases in ovary and testes weights, increases in liver, kidney, and thyroid weights, and cataracts and retinal degeneration (high-dose females). These data demonstrated the comparable toxicities of 2,4-D acid, DMA, and 2-EHE and support a subchronic no-observed-effect level of 15 mg/kg/day for all three forms. In summary, the findings of these studies indicate comparable low subchronic toxicity potentials among representative forms of 2,4-D.

A sheet-metal forming simulator which stretches a strip around a cylindrical pin was used to investigate the relationship between friction and process variables including sliding speed, strip strain, and strain rate in the boundary lubrication regime. Measurements were conducted with 3104 aluminum alloy sheet of three different surface conditions on D2 tool steel and cemented carbide tooling. Friction was found to increase with the strain occurring during contact. This supports a friction model which treats the influence of plastic strain on the flattening of strip asperities and real area of contact. The friction measured with stretching and sliding transverse to the rolling direction was 30% to 40% smaller than that measured along the rolling direction. No significant difference in friction coefficient between sand-blasted workpieces stretched and slid along the rolling direction and transverse to the rolling direction was observed and the friction coefficients were found to be close to those obtained with the original workpiece surface transverse to the rolling direction.

A simple analysis for the lubrication of saw-tooth surfaces with longitudinal lay under conditions of high fractional contact area is developed. This is then coupled with Wilson and Sheu’s asperity flattening model to treat the mixed lubrication of a bulk metal forming process (rolling). It is shown that, even under low speed conditions where the inlet zone does not generate significant hydrodynamic pressures, relatively high hydrodynamic pressures can be generated in the work zone. This explains the persistence of hydrodynamic effects noted in low speed experiments.

To determine the mechanism by which low arterial PO2 (PaO2) affects muscle carbohydrate (CHO) metabolism during exercise, dogs inhaled gas consisting of 0.21 (NO; n = 6) or 0.11 (LO; n = 6) inspired oxygen fraction (FIO2) during rest and 150 min of moderate treadmill exercise. Limb arteriovenous difference and isotopic ([3H]- and [14C]glucose) methods were used to assess muscle carbohydrate metabolism: PaO2 was reduced by approximately 50% in LO vs. NO, but limb O2 uptake was similar. Glucose disappearance was increased during rest (13 +/- 2 vs. 19 +/- 1 mumol.kg-1.min-1) and exercise (23 +/- 4 vs. 36 +/- 6 mumol.kg-1.min-1 at 150 min) in LO vs. NO, but arterial glucose was unchanged because hepatic glucose production was increased similarly. Limb glucose and pyruvate oxidation (derived from vein [14C]lactate specific activity) rates were elevated about twofold during rest and exercise in LO vs. NO. Estimated limb glycogenolysis increased at rest (21 +/- 9 vs. 96 +/- 23 mumol/min) and during exercise (70 +/- 21 vs. 184 +/- 41 mumol/min at 150 min) in LO vs. NO. The %CO2 and %lactate from glucose in LO were about twofold the values in NO in rest and exercise. The %CO2 from pyruvate was greater and free fatty acid levels were lower, suggesting reduced fat metabolism in LO. Arterial lactate and pyruvate levels were elevated during rest and the initial 30 min of exercise, even though net limb outputs were no greater. Lactate-to-pyruvate ratios and pH were similar in LO and NO during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced O2 availability, as might occur under some physiological and pathological conditions, stimulates insulin and glucagon release and increases glucose fluxes and muscle carbohydrate metabolism. The aim of this study was to determine the role of reduced PO2, independent of changes in glucagon and insulin. In six dogs, in paired studies separated by 2 wk, glucagon and insulin levels were fixed throughout by infusion of somatostatin with basal intraportal glucagon and insulin replacement. A control period was followed by 90 min of breathing 21% (NO) or 8% (LO) O2. Isotopic and arteriovenous methods were used to assess carbohydrate metabolism. Measured variables were constant over time in NO. Arterial PO2 (Pao2) was approximately 100 mmHg in NO and approximately 30 mmHg in LO, resulting in a 50% fall in O2 content. Insulin, glucagon, and catecholamine levels were similar in NO and LO. Cortisol was significantly increased in LO. Arterial glucose was unchanged in both groups. In the last 45 min of the experimental period in LO, 1) glucose production (14 +/- 1 to 18 +/- 1 mumol.kg-1.min-1), glucose disappearance (15 +/- 1 to 17 +/- 1 mumol.kg-1.min-1), and net hepatic glucose output (11 +/- 1 to 15 +/- 1 mumol.kg-1.min-1) rose, 2) limb pyruvate oxidation (11 +/- 2 to 24 +/- 5 mumol/min) and estimated glycogenolysis (9 +/- 3 to 42 +/- 9 mumol/min) increased, 3) percentages of CO2 from limb pyruvate and glucose increased, and percentage of lactate from blood glucose decreased, and 4) arterial blood lactate was approximately 100% more, although net limb and hepatic lactate balances were unaltered, which suggests that neither liver nor muscle is the source of increased blood lactate. Comparison of these results with our previous study [Zinker et al. Am. J. Physiol. 266 (Endocrinol. Metab. 29): E921-E929, 1994] shows that the response to reduced PaO2, although present, is reduced when glucagon and insulin levels are fixed at basal. The majority of stimulation of glucose production by decreased PaO2 is still present when pancreatic hormones are clamped at basal, while the response by the hindlimb tissues is greatly reduced.

A realistic model for friction in lubricated sheet-metal forming which takes account of the different lubrication regimes which may occur at the sheet/tooling interface is developed. Friction is expressed in terms of internal interface variables (mean lubricant film thickness, sheet roughness and tooling roughness) in addition to the more traditional external variables (interface pressure, sliding speed and strain rate). The new model has been coupled to an existing finite element membrane analysis of axisymmetric stretch forming. Numerical results using the coupled codes showed excellent agreement with measured strain distributions over a range of operating conditions. Computational times with the refined friction model were typically increased by about 10 percent compared to those with a simple Amontons-Coulomb constant friction coefficient model.

The dynamic concentration model for lubrication by oil-in-water emulsions proposed by Wilson el al. (1) is applied to strip rolling to derive a relatively simple equation for inlet film thickness. The predictions of the new model are supported by rolling experiments using emulsions as lubricants, where the film thickness is inferred from the surface roughness that is generated on the workpiece during rolling. The experiments also seem to suggest that the efficiency of oil droplet capture increases with increasing rolling speed. Presented at the 49th Annual Meeting in Pittsburgh, Pennsylvania May 1–5, 1994

Tetrasomy 12p (Pallister-Killian syndrome) is a mosaic aneuploidy syndrome in which the isochromosome is present in amniocytes with a much greater percentage than fetal lymphocytes. Two new cases identified by prenatal diagnosis are reported. Indications for prenatal diagnosis were advanced maternal age and fetal anomalies. The most consistent reported prenatal ultrasound findings for tetrasomy 12p include polyhydramnios with short femurs and a diaphragmatic hernia. Recognition of congenital malformation patterns prenatally may allow appropriate selection of tissue for chromosome analysis. Molecular cytogenetic analysis using fluorescence in situ hybridization was used retrospectively to confirm the presence of the isochromosome 12p in various formalin-fixed fetal tissues. The levels of mosaicism detected in fetal and placental tissues were lower than those detected prenatally.

A mathematical model for liquid lubricated strip rolling in the full-film regime is developed. The model combines slab plasticity, hydrodynamic lubrication and thermal analyses to relate local and global condition to process variables and material properties. The predictions of the model are compared with experimental measurements of outlet speed ratio, roll separating force and roll torque in rolling 1100-H14 aluminum with a viscous mineral oil and 5P4E polyphenyl ether as lubricants. The excellent agreement which is obtained provides powerful support of the validity of the model.

A sheet metal forming simulator which stretches a strip around a cylindrical pin was used to investigate the relationship between friction and process variables including sliding speed, strip strain and strain-rate in the boundary lubrication regime. Measurements were conducted with two different sheet and tooling material combinations: electro-galvanized steel sheet on smooth A2 tool steel and commercially pure aluminum sheet on cemented carbide. In the first system, friction tends to increase with strain in contact. This supports a friction model which treats the influence of plastic strain on the flattening of strip asperities and real area of contact. In the second system friction was found to decrease with the strain in contact. This is apparently due to a decrease in contact area associated with roughening of the strip by plastic deformation.

An oil-in-water emulsion in the inlet zone of a concentrated contact is modeled by treating the oil particles as flattened cylinders surrounded by water. In an independent flow model, the oil and water flows are coupled only through the pressure gradient. However, the model leads to anomalous behavior with regard to the flow of water. To overcome this problem, corrections to the pressure gradients due to interactions between the oil and water were derived. Both models showed that the emulsion became concentrated because the higher viscosity oil was preferentially drawn into the conjunction. The net effect was similar to an inlet starved of oil. The inlet film thickness predicted by the interactive theory was in good agreement with Dow's experimental measurements for an EHL contact. Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

Two mathematical models for axisymmetric stretch forming with a spherical punch are developed. The models combine a finite element representation of the sheet deformation with a hydrodynamic lubrication model. In one model the influence of sheet bending stiffness is taken into account while in the other only the membrane stiffness is considered. Comparison of the predictions of the models with the film thickness measurements of Hector and Wilson indicates that the inclusion of elastic effects is important in predicting lubricant film thickness. The results of the bending model are in particularly good agreement with the experimental data. A useful analytical method for predicting the film thickness at the center of the conjunction at the onset of yield is also developed.

An analytical model for strip rolling operating in the mixed regime is developed. The model combines analysis for the influence of bulk plastic deformation on the effective hardness of the strip asperities with an approach to allow for the influence of roughness on lubricant flow. An approximate correction for thermal effects is also included. The predictions of the model are compared with experimental measurements of film thickness and slip. Presented as a Society of Tribologists and Lubrication Engineers paper at the STLE/ASME Tribology Conference in New Orleans, Louisiana, October 24–27, 1993

A variety of models for lubrication by emulsions are compared with film thickness measurements made by Dow for elastohydrodynamic lubrication contacts lubricated by oil-in-water emulsions. The results of conventional elastohydrodynamic analysis with effective viscosity models tend to under-estimate the lubricant film thickness. A simplified dynamic concentration model shows much better agreement with the experiments.

An upper bound-lower bound model based on the “energy method” has been developed for the hemispherical-punch hydroforming processes. This activity is primarily undertaken to help to define either a suitable level of friction or an operating fluid-pressure path for the purposes of process design and control. The punch deforms the workpiece by moving it against a controlled pressurized fluid. As the punch travels, the workpiece is deformed over its central regions into a hemispherical shape initially, the final shape being that of a hemispherical cup. The present parametric study includes a general friction-force expression as well as an explanation of the change of geometries. Loci representing the critical fluid pressures that result in rupture and wrinkling are presented.