Analysis of factors contributing to success in a program of micromanipulation-assisted fertilization

OBJECTIVE: To determine factors important to clinical success in micromanipulation-assisted in vitro fertilization (IVF). DESIGN: Procedures invoked in two separate series of micromanipulation-assisted IVF cycles, one unsuccessful (series I) and the other successful (series II), were compared in an effort to identify changes that led to clinical success. SETTING: University-based IVF clinic. PATIENTS: In both IVF series involving micromanipulation, patients consisted of infertile couples who fit any of five categories of male-factor related infertility. The female patients underwent controlled hyperstimulation for oocyte retrieval and the oocytes were inseminated normally or were subjected either to partial zona dissection or subzonal sperm insertion to assist fertilization. Results in all groups were compared between the two patient series. RESULTS: In the successful series II, a noticeable improvement in fertilization rate and embryo quality was observed compared with series I. A significant increase in the percentage of patients reaching embryo transfer, the pregnancy rate per transfer, and the pregnancy rate per retrieval were noted in series II; a 25% ongoing pregnancy rate per retrieval was observed overall in this successful group, with "ongoing" defined as manifestation of at least a fetal sac on ultrasound with no detectable problems. Patients with a mixed transfer of embryos derived from manipulated and normally inseminated oocytes had a 75% rate of pregnancy per transfer in series II. Differences between the two series could not be attributed to patient selection or biases in selection of oocytes relegated to micromanipulation. However, oocyte handling, micromanipulation, and culture protocols differed significantly between the two series in that temperature and pH of oocytes was better controlled, and micromanipulation time was minimized in series II. CONCLUSION: Success in micromanipulation depends on maintenance of the oocyte in a stable and supportive environment throughout the micromanipulation procedure. It is also important to minimize trauma to the eggs by performing micromanipulation rapidly and with minimal distortion of the egg. Patients with a poor fertilization rate in standard IVF may experience a substantial increase in the likelihood of pregnancy when micromanipulation-assisted fertilization is performed on some eggs.     

Educated insane: a nineteenth-century psychiatric paradigm

In the 1830s the time-honored notion that excess study could lead to madness underwent a significant change in America. Under the influence of Enlightenment pedagogy and phrenology, influential superintendents like Amariah Brigham and Isaac Ray feared that the "unnatural" overstimulation of children in schools would ruin their development. In the second half of the nineteenth century, as belief in environmental determinism waned and assumptions about what is "natural" changed, this psychiatric etiology was debated; then, overthrown. By the turn of the century, education was thought to aid, not harm, the mentally ill.     

Mechanisms of cyclic softening in precipitation-hardening alloys—A ball model approach and tests at 78 K

Tests of random, alternating cuts on a ball-model of in Al–Cu alloy have been run to check the kinetics at which disordering occurs in an initially ordered precipitate subject to cyclic strain. In addition, fatigue tests at low temperature (78 K) and various microscopical observations have been made on Al–Ag alloy containing GP zones to check whether a structure containing an initially disordered precipitate will cyclically soften or not. It was thus found that the ball model disorders as a function of accumulated plastic strain consistently with the kinetics of cyclic softening in actual material. Further, Al–Ag alloy was found not to soften at 78 K. Both of these results supoort the disordering hypothesis of cyclic softening over the dissolution or shearing-off mechanisms, although other systems may be subject to these mechanisms. In spite of the low temperature at which the Al–Ag alloy was tested, small / precipitates were found to have formed in the longest lived test; however, this result did not interfere with the validity of the experiment as it did previously at room temperature. The fatigue lives at 78 K were much longer than those previously measured at room temperature although the failure mechanisms were not affected at high strain and only somewhat affected at low strain (there was increased incidence of transgranular crack nucleation and propagation).

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Résumé Des essais d'application de coups alternés et aléatoires sur un modèle de simulation par des billes de la phase dans les alliages de Cu–Al ont été effectués en vue de vérifier la cinétique suivant laquelle se produisent des désordres dans un précipité initialement ordonné et soumis à des déformations cycliques. En outre, des essais de fatigue à basse température (78°K) ainsi que diverses observations microscopiques ont été effectués sur un alliage Al–Ag comportant des zones GP en vue de vérifier si une structure comportant un précipité initialement en désordre subirait un adoucissement cyclique ou non. On a donc trouvé que le modèle de utilisant des billes fait état de désordres en fonction de l'accumulation de la déformation plastique et ce en rapport avec la cinétique d'adoucissement cyclique dans le matériau réel. En outre, l'alliage Al–Ag s'est révélé ne pas s'adoucir à 78°K. Ces deux résultats soutiennent l'hypothèse suivant laquelle un adoucissement cyclique s'accompagne de désordres plutôt que de mécanismes de disolution ou de séparation par cisaillement, bien que d'autres systèmes puissent être sujets à ces mécanismes. En dépit de la basse température à laquelle l'alliage Al–Ag a été essayé, on a trouvé de petits précipités / qui se sont formés au cours des essais, les plus longs. Cependant, ce résultat ne gène pas la validité de l'expérience comme c'était le cas précédemment à température ambiante. Les vies en fatigue à 78°K ont été trouvées bien plus longues que celles mesurées précédemment à température ambiante, en dépit du fait que le mécanisme de rupture n'ait pas été affecté sous les déformations élevées et ne l'a été que quelque peu sous les déformations faibles, auxquelles apparait une incidence croissante d'une nucléation et d'une propagation d'une fissure transgranulaire.

     

Novel bacterial structures in human blood: cultural isolation

Evidence for the existence of a novel bacteriological system has been obtained from osmotically lysed and filtered human blood (membrane filters with a pore size of 0.22 micronm) placed in special culture media. These blood filtrates gave rise to ordinary bacteria for 71% of the blood specimens processed from diseased humans and for 7% of those from supposedly normal humans. Morphologically, the bacteria resembled streptococcal, staphylococcal, and gram-positive filamentous (cocco-bacillary) forms. Prior to the appearance of bacteria in the media, large and small "dense bodies" were microscopically observed but disappeared when ordinary bacteria were apparent, Cultures of of unlysed blood as conventionally performed were negative. These organisms may represent an adaptation of certain bacteria to life in the blood.     

Benefits of carbon addition on the hydrogen absorption properties of Mg-based thin films grown by Pulsed Laser Deposition

Mg-Ni thin films were grown using Pulsed Laser Deposition. In situ optical changes from shiny metallic to transparent states were observed for films deposited in vacuum and under an Ar/H₂ gas mixture (93/7%), respectively. Optical changes were also achieved by ex situ hydrogenation under hydrogen gas pressure of 15 bars at 200 °C. However, after ex situ hydrogenation, the optical transmittance of the Mg-based hydrogenated thin films did not exceed 25%. Such limitation was attributed to oxygen contamination, as deduced by High Resolution Transmission Electron Microscopy observations, showing the co-existence of both Mg-based and MgO phases for as-deposited films. A significant decrease in oxygen contamination was successfully achieved with the addition of carbon, leading to the preparation of (Mg-based)-C_x (x < 20%) thin films showing a faster and easier hydrogenation.     

High-power high-Modulation-speed 1060-nm DBR lasers for Green-light emission

We report on the static and dynamic performance of high-power and high-modulation-speed 1060-nm distributed Bragg reflector (DBR) lasers for green-light emission by second-harmonic generation. Single-wavelength power of 387 mW at 1060-nm wavelength and green power as high as 99.5 mW were achieved. A thermally induced wavelength tuning of 2.4 nm and a carrier-induced wavelength tuning of -0.85 nm were obtained by injecting current into the DBR section. Measured rise-fall times of 0.2 ns for direct intensity modulation and 0.6 ns for wavelength modulation make the lasers suitable for >50-MHz green-light modulation applications.     

Total radiation dose at geostationary orbit

Active semiconductor components in satellites are sensitive to accumulated ionization radiation dose. Radiation dose and shielding estimations for electronic components are usually carried out using NASA models of space radiation particle flux. Accurate measurement of accumulated dose during the life of a satellite is essential for optimizing radiation shielding design for electronic components. Dosimeters were designed using radiation sensitive field-effect transistors (RADFETs) and accumulated dose at geostationary orbit was measured. Radiation dose as measured by these dosimeters with spherical aluminum shields are presented and compared with NASA model doses.     

SEU reliability improvement due to source-side charge collection in the deep-submicron SRAM cell

The effect of technology scaling (0.5-0.09 /spl mu/m) on single event upset (SEU) phenomena is investigated using full two-dimensional device simulation. The SEU reliability parameters, such as critical charge (Q/sub crit/), feedback time (T/sub fd/) and linear energy transfer (LET), are estimated. For L/sub g/<0.18 /spl mu/m, the source node collects a significant fraction of radiation-induced charge resulting in an increase of LET, despite the lower critical charge at the sensitive drain node. The effect of striking location on LET confirms this finding.     

Stereo and Specular Reflection

The problem of accurate depth estimation using stereo in the presence of specular reflection is addressed. Specular reflection, a fundamental and ubiquitous reflection mechanism, is viewpoint dependent and can cause large intensity differences at corresponding points, resulting in significant depth errors. We analyze the physics of specular reflection and the geometry of stereopsis which lead to a relationship between stereo vergence, surface roughness, and the likelihood of a correct match. Given a lower bound on surface roughness, an optimal binocular stereo configuration can be determined which maximizes precision in depth estimation despite specular reflection. However, surface roughness is difficult to estimate in unstructured environments. Therefore, trinocular configurations, independent of surface roughness are determined such that at each scene point visible to all sensors, at least one stereo pair can produce correct depth. We have developed a simple algorithm to reconstruct depth from the multiple stereo pairs.