Search

An estrus-associated glycoprotein (oEGP) secreted by the ampulla of the ovine oviduct for 3 to 6 d around the time of estrus is known to bind to the zona pellucida of newly ovulated oocytes, as well as embryos but does not appear to bind to spermatozoa. The objective of this paper was to establish whether or not the association of oEGP with the zona pellucida influences fertilization and subsequent embryo development. Four separate experiments were carried out to examine the specific effects of different concentrations (0, 2.5, 5.0, 10.0, 20.0% v/v) of an oEGP-enriched fraction of oviducial fluid (F1) in in vitro fertilization (IVF) medium. This medium was synthetic oviduct fluid (SOF) containing either no serum or supplemented with human serum (HS) or sheep serum. Fertilization did not occur in the absence of serum, while both cleavage rate and the developmental competence of embryos were significantly greater in SOF + sheep serum than in SOF + HS. The presence of F1 in the HS-containing medium significantly improved cleavage rates. The specificity of this effect was confirmed in a study which substituted F1 with a comparable concentration of BSA. In the IVF medium (SOF + sheep serum), the addition of F1 at a concentration of 10% significantly (P

Oviduct specific estrus-associated glycoproteins (EGP) secreted around the time of estrus are known to be present in several species. Many of these glycoproteins, including that of the sheep (oEGP), have been shown to bind to the zona pellucida and to become associated with individual blastomere membranes, indicating a role for these proteins in early embryo development. Given that the culture of ovine embryos can result in a number of developmental abnormalities as well as a reduction in viability, the present study examined the effects of oviducal fluid and gel filtration fractions of oviducal fluid on the in vitro development of ovine embryos. The first fraction of oviducal fluid (F1) contained predominantly oEGP, while the second (F2) contained albumin and was included in the study as a control. The culture medium was synthetic oviduct fluid (SOF) supplemented with 20% human serum (HS). The study consisted of 2 experiments; the first examined the effects of oviducal fluid, F1 and F2 in combination with 0, 10 and 20% HS; while the second, which aimed to investigate the effect of F1 during the first 72 h of culture, examined the influence of oviducal fluid and the fractions in the presence of either a low concentration of serum or no serum for the first 72 h. The presence of Fl significantly decreased the proportion of zygotes undergoing first cleavage, increased the mean number of nuclei per blastocyst and increased the mean time taken for blastocyst formation. Unfractionated oviducal fluid appeared to be detrimental to embryo development while F2 had no influence. The use of a low concentration of serum during the first 72 h of culturewas not beneficial to development. Removing F1 from the culture medium after the initial 72 h of culture did not reverse the effects of this protein, implying that it is required only during the first 2 to 3 d of development. It is postulated that oEGP is involved in a selection mechanism at the zygote stage and may improve the viability of in vitro cultured embryos.

We have studied the influence of placing a soluble, homogeneous catalyst onto a solid support. We determined that such a 'heterogenized' homogeneous catalyst can have improved activity and selectivity for the asymmetric hydrogenation of enamides to amino acid derivatives. The route of heterogenization of RhDuPhos(COD){sup +} cations occurs via electrostatic interactions with anions that are capable of strong hydrogen bonding to silica surfaces. This is a novel approach to supported catalysis. Supported RhDuPhos(COD){sup +} is a recyclable, non-leaching catalyst in non-polar media. This is one of the few heterogenized catalysts that exhibits improved catalytic performance as compared to its homogeneous analog.

EDITORIAL COMMENT: We accepted this case for publication to remind readers that the HELLP Syndrome does exist and can be present in patients who do not exhibit hypertension or marked generalized oedema; it tends to occur when preeclampsia is treated conservatively. When diagnosed, prompt delivery is indicated, after commencement of the preferred drug regimen for treatment of severe preeclampsia, but Caesarean section is not necessarily the preferred route of delivery, as illustrated by the following case, courtesy of Dr Ian Maclsaac, seen 2 days after the editor read this paper. A 29-year-old primigravida presented with severe pain and tenderness under the right costal margin, at 35.5 weeks' gestation, after a normal antenatal course; she had proteinuria (urine 1/10 solid on boiling), BP120/70, platelet count 44× 109/I and elevated serum enzymes levels (aspartate aminotransferase 364 (0–31 μ/l), alanine aminotransferase 513 (0–31 μ/l); there was no haemolysis and the coagulation profile was otherwise normal. Two days later labour was induced by amniotomy and oxytocin infusion because the epigastric pain, thrombocytopenia, proteinuria and abnormal liver function tests had persisted; 8 hours after induction a 2,860 g infant was born normally in good condition. Two days later the platelet count had fallen to 19×109/l, and microscopic haematuria was present; the patient was given a 6-unit platelet transfusion; 2 days later the platelet count was 122× 109/l and there were no further problems with mother or baby. Readers may debate whether this is a genuine case of HELLP syndrome without evidence of intravascular haemolysis or abnormal coagulation profile apart from thrombocytopenia. However, this case does undoubtedly endorse the author's message that patients with preeclampsia treated conservatively, and all those with epigastric pain associated with proteinuria, should have coagulation profile, full blood examination and tests of liver function performed, in addition to renal function tests and assessment of fetal well-being by cardiotocography. Summary: We describe a case of preeclampsia with the HELLP (Haemolysis, Elevated Liver enzymes, Low Platelets) syndrome and highlight the delayed diagnosis due to its nonspecific presentation. This syndrome is associated with significant maternal and perinatal mortality and morbidity and we discuss the importance of early recognition of the condition, aggressive management and a multidisciplinary approach.

A nonaromatic nematic solvent consisting of an equimolar mixture of trans-4-n-butyl and trans-4-n-hexyl-cyclohexane-l-carboxylic acid was used to study the hydrogen NMR spectrum of partially oriented benzene. Variations in linewidths between 0.7 and 2.6 Hz could be observed but there was no strong correlation between splitting frequency and linewidth. The spectrum was analyzed using the Redfield theory considering intramolecular and intermolecular dipolar relaxation separately. Best agreement with the experiment is obtained by combining intermolecular relaxation effects with the zero frequency term of the intramolecular relaxation which gives contributions to the linewidths that are proportional to the square of the splitting frequency. The results indicate that the intermolecular interactions dominate and that intramolecular interactions become of importance only due to relatively slow director fluctuations.

This paper deals with the application of regression procedures and cross-validation for predicting the resultant fiber-length characteristics of tops from raw wool measurements. Alternative methods of choosing raw wool variables and then estimating regression coefficients for prediction are compared. Data from 39 commercial batches from a single mill are used for this evaluation. The statistical problems associated with prediction are discussed; however, further mill studies will be required to assess the potential of the predictive relationship obtained in this study.

Batches in a combing plant were monitored to examine the relative influence of a number of greasy wool characteristics on the early stages of worsted processing. Characteristics measured for each batch included those normally available from core testing (mean fiber diameter, yield, and vegetable matter content), together with staple length and its variability, staple strength and the position of staple weakness, clean color, resistance to bulk compression of clean wool, and variability of fiber diameter. Combing noilage, the mean and distribution of fiber length, and the mean fiber diameter of the resultant tops were the processing factors considered. High levels of association were found between selected subsets of the characteristics of the greasy wool and the processing factors. There is some discussion of the appropriateness of the methods of regression analysis and the refevance of the work to the commercial situation.

A plausible model is used to derive formulas for the expected number of fibers with zero, one, or two ends in a given length segment of a random assembly of aligned fibers. These results are then combined to form the expectation of the number of ends and various related quantities. By making a stronger assumption, an expression for the variance of the number of ends is found. A numerical illustration is used to show how the variance depends on the length of the segment involved. Various definitions for the proportion of ends are given and discussed. A brief discussion of the relevance of these results to the study of the mechanics of staple fiber yarns is included.

A two sample cest is proposea ior Liie hypuLiiefexo in.; LUSL observations from a second sample are equivalent, in distribution, to the smallest of r independent realisations of the first sample. Assuming H to be true the efficiency of parameter estimation for the exponential and normal distributions is then considered

A model of human perception is presented which describes the results of a photointerpreter's annotation of discrete features in an image. In this example, the features are geological lineaments. However the model carries no assumptions as to connectivity or shape and is, in principle, applicable to discrete features of any type, such as multispectral or textural themes in geology, agriculture, forestry, and hydrology. It is believed to be the first perception model fitted to an observational process in geology and a novel description of the human feature-extraction process in remote sensing. The model ascribes the classification of pixels in a digitized annotation to their being drawn from a mixture of binomial distributions. The two distributions of the model represent the presence or absence of a message at each pixel. Depending on whether the message was correctly marked on the annotation or not, the quantities positive signal, negative signal, additive noise and subtractive noise may be defined for an annotation. The model may also be used to provide estimates of annotation quality, defined as the probability that a message exists at a pixel. Photointerpreter's annotations may be issued as shade prints, where the shade of grey indicates the annotation quality. Different methods of preparing such shade prints are described.

Formulas for the moments of fiber length properties for those fibers that intersect a segment of an assembly of aligned fibers are derived. These, where relevant. have been reconciled with earlier formulas given in the literature.

The accurate measurement of the distribution of wool fiber diameter in a top using the projection microscope is described. The work is directed towards establishing the best way of generating reference standard tops. The fiber diameters are shown to conform to a lognormal distribution.

The beta distribution is used as a model for obtaining sampling plans when material is in bulk form and the random variable is the fraction of material having a given characteristic. The model seems to be particularly appropriate when observations are c..

A method of constructing simultaneous interval estimates for linear combinations involving q (at most) of p group means is given. To obtain percentage points to cover the case of unequal group variances the requirement of equal replications within groups is needed. Tables for q=2 are given, which includes the important practical application of all paired comparisons. Extension of the tables to q>2 involves tedious numerical integration and is of less practical utility. The method also applies when the within group variances are equal (or a known ratio of a common variance, for there is now no need for equal within group replication) but does not give, for most practical circumstances, shorter intervals than established techniques.

The principle upon which the operation of direct-reading wattmeters is based has been known for many years. The contribution of this paper lies in the application of this principle to a practical operating instrument for the measurement of high power at radio frequencies. Two instruments are described. The first is useful in the range of frequencies from 500 to 2000 kilocycles. This instrument contains circuits which permit operation at any frequency in this band with no tuning or other change in the instrument. The second instrument operates in the region near 50 megacycles. It is inherently a single-frequency device constructed from sections of transmission lines. The theory of operation is discussed, as well as calibration methods. Test data taken with the instruments with loads having a wide range of power factors are compared with power measurements made on water-cooled loads.

The feasibility of a small scale analogy to study radio transmission problems is briefly discussed as an introduction to the description of model apparatus developed for this purpose. This consists of a model transmitter operating near 75 megacycles and a receiver of the screen-grid voltmeter type. Use is made of these devices to study the effect of the separation of resonant and nonresonant towers on the field patterns of the transmitter. Experimental patterns are shown and compared with corresponding ones computed from formulas derived in the included theoretical study of the problem. It is concluded that a further development of the method of models in conjunction with a study of an actual transmitting system should prove of value as a means of discovery and generalization.

The factors influencing the action of towers when used as radiators are considered. It is shown that the results predicted from the simple theory of sinusoidal distribution of current on the tower differ to a major extent from the actual results. A series of measurements using small models of actual antenna structures resulted in data correlating closely with the performance of the full-sized structures. These measurements showed that departures from the simple theory are due to nonsinusoidal current distribution. Several types of recently installed antenna towers are shown to be less effective than the simple theory prediction, particularly with regard to reduction of sky wave and fading. Means for correcting the current distribution and thereby improving the performance are pointed out. The statement that low base capacity is essential to high antenna efficiency is shown to be a fallacy providing simple precautions are taken to reduce conduction losses. The ground system and earth currents are considered from both a theoretical and experimental viewpoint. A simple method of measuring the earth currents is described and it is pointed out that such measurements indicate whether the antenna current is sinusoidal or not. Appendix A gives a method of computing the radiation characteristics and the radiation resistance when the current distribution is known but is not expressed analytically. Appendix B contains the theory behind the ground current measurements. Appendix C shows the influence of the base insulator capacitance on the operating characteristics.

Theoretical considerations concerning the losses in ground systems are advanced. These considerations indicate the feasibility of antennas much less than a quarter wave length tall, for low power broadcast use. The desirability of large ground systems is also indicated. Experimental data are given which show that an eighth-wave antenna is practically as efficient as a quarter-wave antenna. It is also found that a ground system consisting of 120 buried radial wires, each one-half wave long, is desirable. Tests of ground screens show them to be of no importance when adequate ground systems are used. The experimental data include antenna resistance and reactance, field intensity at one mile, current in the buried wires, and total earth currents, for many combinations of antenna height, number of radial wires, and length of radial wires.

The action of broadcast antennas with various current distributions is examined in an endeavor to determine the combinations which are most likely to be useful. In each case, the vertical radiation characteristics, the radiation resistance, and the electric field intensity at the surface of the earth one mile from the antenna are determined. The relative merits with respect to fading suppression are also considered. Of the several arrangements examined, some have been very disappointing. In no case where the total antenna height is at all reasonable for broadcast use does the field strength at one mile go to exceptionally high values. For heights of the order of a half wavelength, it is hard to find anything better than a straight vertical wire. Some of the arrangements save a small amount in height, but in no other respect do they improve on the straight wire. The analysis of the antenna with decreased velocity and antennas spread in the horizontal plane shows that both are definitely ruled out of the picture. The results show that the Franklin antenna would be very useful if it were not for the great heights required.

Measurements of resistance and reactance of cylindrical antennas operated against ground have been made, with a wide variation of both antenna length and diameter. These data are displayed by means of a series of graphs. The maximum values of resistance encountered are displayed. The shortening effect near the quarter-wave resonance point is also shown. Terminal conditions, such as capacitance of the base of the antenna to ground, are briefly considered, and a series of measurements shows the wide variation in impedance for varying terminal conditions. Measurements made in the course of the investigation show that the impedance of the antenna is independent of whether the top of the radiator is open or closed. The measured impedance data are also directly applicable to the case of a center-fed dipole.

A knowledge of the radio-frequency voltages on the insulation of broadcast tower antennas is important to the design engineer, since a too-large factor of safety may add unduly to the tower cost. Attention is first given to the base-insulator voltage. The magnitude of this voltage is also of interest in the design of lighting chokes and coupling equipment. Theoretical values are derived and shown in curveform as a function of antenna height. The theoretical curves are supplemented by experimental data taken on self-supporting tapered towers, guyed cantilever towers, guyed uniform-cross-section towers, and guyed tubular steel masts. A theoretical treatment is then given concerning the role of guy wires from an electrical standpoint. Consideration is given to the currents in the guys, and the voltages on the guy insulators. Measurements are presented of the voltages existing on the guy insulators of two guyed masts of different constructions. These voltages are found to be so small that there seems little need for elaborate insulation except for the presence of high static or induced lightning voltages. The paper is concluded by some considerations of ways of providing protection against these high instantaneous and random voltages without the use of expensive and elaborate insulation.

The equations for the radiation patterns of directional antenna systems are well known, but the arithmetical work necessary to secure a plot of the radiation pattern is tedious and time-consuming. Several mechanical plotting devices to assist with the problem have been described in the literature. A brief review of a few of these instruments is presented. These mechanical devices yield the radiation pattern for a given choice of configuration and antenna constants. In general, however, the designer of a directional antenna for broadcast-station use knows the pattern required and is faced with the problem of determining the antenna configuration which will yield this pattern. The RCA Antennalyzer was developed to synthesize or to analyze. The instrument is entirely electrical, with no moving parts except the potentiometers which change the various parameters. Developed specifically for the design of directional antennas for broadcast use, the Antennalyzer, as constructed, will yield the radiation pattern of directional antennas which have as many as five towers or sources of radiation. Each source is characterized by four parameters: (1) the distance from a reference point; (2) the azimuth angle with respect to a base line; (3) the amount of current in the antenna; and (4) the phase angle of this antenna current. Thus the Antennalyzer has four potentiometers associated with each antenna, with one exception. One antenna is located at the reference point and carries unit current at zero phase. Hence, no controls are required for this antenna.

The application of heat-flow equations to the heat-flow problems in wood-gluing presses is considered. By means of a transmission-line analogy, the solution of heat-flow problems with internally generated heat is greatly simplified. The general equation is set up and applied specifically to the problem of radio-frequency heating of wood, while the wood is contained between two cool plates. Comparison of this type of heating with the usual hot-plate-press method reveals important advantages for the radio-frequency method. The formulas developed have been illustrated by means of curves based upon the constants of wood. However, the general equations apply as well to the heating of any other insulating material, where the heating by radio frequency is done by essentially a dielectric-loss phenomena.

This paper recounts the adventures of the two National Television System Committees (NTSC's)in preparing monochrome and color television service for the American public. The first NTSC had the active encouragement of the Federal Communications Commission (FCC). Building on the important prior work of the Television Standards and Allocations Committeees of the trade association of the time, the Radio Manufacturers Association, it was able to complete its task of setting up the system standards for black-and-white television in less than nine months, from July 1940 to March 1941. These standards, with narrower tolerances but otherwise unchanged, now serve as the basis for the compatible color service now universally broadcast to the American people. The second NTSC had a rougher road to follow. The FCC, having approved an incompatible color system over strong-and strongly resented-objections of the industry's engineers, did not welcome the formation of the second NTSC. The second NTSC had, in addition to these political and institutional pressures, a very difficult technical task, one thought by many at the time to be flatly impossible: to impose high-quality color on the black and white system without injuring reception on black-and-white receivers. Combining and refining the work of many contributors, the second NTSC cogitated and tested from early 1950 to mid-1953 until it had the system we now enjoy-one that has been adopted in its essentials throughout the World. One aim of the paper is to reveal the constructive forces that led to these successes, and the near misses with defeat that were encountered on the way.