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In this note the results of an experiment to determine the effects of aggregation and disaggregation in forecasting the median growth rate of eighteen industrialized countries' annual output (GDP) growth rates are reported.

Using data from the National Longitudinal Survey of Youth (NLSY) we introduce and estimate various Bayesian hierarchical models that investigate the nature of unobserved heterogeneity in returns to schooling. We consider a variety of possible forms for the heterogeneity, some motivated by previous theoretical and empirical work and some new ones, and let the data decide among the competing specifications. Empirical results indicate that heterogeneity is present in returns to education. Furthermore, we find strong evidence that the heterogeneity follows a continuous rather than a discrete distribution, and that bivariate normality provides a very reasonable description of individual-level heterogeneity in intercepts and returns to schooling.

The estrogenic steroid hormones, acting primarily through the nuclear estrogen receptors ERalpha and ERbeta, regulate sexual differentiation in a wide variety of vertebrates. In the frog Xenopus laevis, estrogen regulates the strength of vocal neuromuscular synapses and contributes to the physiological basis of sexually differentiated songs. To understand the mechanisms by which estrogen produces these effects, we have characterized the ERs of X. laevis and their expression in laryngeal muscle and other tissues. We found a remarkable molecular diversity in the estrogen receptor population within individuals. First, we have identified two distinct ERalpha genes, xlERalpha1 and xlERalpha2, which represent, to our knowledge, the first discovery of retained duplicates of the ERalpha gene in any species. These two genes are highly conserved at the amino acid level but have distinct nucleotide sequences; moreover, ERalpha2 has no N-terminal domain. Cloning of ERalpha and ERbeta in the related species Xenopus tropicalis and phylogenetic analysis indicate that the two xlERalpha loci were generated by a duplication specific to the X. laevis lineage-most likely the genome duplication that led to a doubling of the X. laevis chromosome number about 30 million years ago. The primary ER expressed in X. laevis laryngeal muscle is the novel gene xlERalpha2; ERalpha1 is primarily expressed in liver, forebrain, and oviduct. Alternatively spliced transcripts of both xlERalpha1 and xlERalpha2 are also expressed in a tissue-specific manner. We propose that complementary spatial expression of these two genes and their alternatively spliced transcripts contributes to their conservation over such a long period of time, consistent with the subfunctionalization model for evolution after gene duplication.

Synaptic transmission at the vocal synapse, the laryngeal neuromuscular junction, of Xenopus laevis has been shown to be regulated by long-term changes in circulating estrogen. In females, high levels of circulating estrogen also accompany gonadotropin-induced ovulation and oviposition and the switch from sexually unreceptive to receptive states, including changes in vocal behaviors (ticking to rapping). Here we examine the effects of gonadotropin injection on laryngeal synaptic strength and call type. Gonadotropin acutely reduced quantal content values of laryngeal synapses in intact, adult females; the lowest values were attained by 12 h post-injection. Estrogen and progesterone levels increased following human chorionic gonadotropin (hCG) injection; the time course was similar to, but negatively correlated with, changes in synaptic strength. In ovariectomized frogs, exogenous estrogen, but not progesterone or hCG, mimicked the acute effects of hCG in weakening laryngeal synapses of intact frogs. hCG injection suppressed ticking and sometimes induced rapping. Females could tick with either strong or weakened laryngeal synapses while rapping was only produced during the weakening action of hCG. The normally strong synapses of females may enable vocal production even when laryngeal synapses are weakened by hormones that induce ovulation. In contrast to the acute effect of estrogen on weakening laryngeal synapses, juveniles required more than 2 weeks of estrogen treatment to strengthen laryngeal synapses while at least 4 weeks postovariectomy were required to weaken synapses in adult females. We conclude that acute (hours) increases in circulating levels of estrogen weaken synapses while chronic (weeks) increases strengthen laryngeal synapses.

This paper derives simply computed closed-form expressions for the Average Treatment Effect (ATE), the effect of Treatment on the Treated (TT), Local Average Treatment Effect (LATE) and Marginal Treatment Effect (MTE) in a latent variable framework for both normal and non-normal models. The techniques presented in the paper are applied to estimating a variety of treatment parameters capturing the returns to a college education for various populations using data from the National Longitudinal Survey of Youth (NLSY).

Synaptic efficacy at the laryngeal neuromuscular synapse differs markedly in adult male and female Xenopus laevis. Here, we examined the relation between circulating estrogen and synapse strength in developing and adult female frogs. Circulating estrogen levels in males and females during juvenile and adult stages were measured using radioimmunoassays. Synaptic strength was determined by quantal analysis in isolated female larynges. In males, estrogen levels are low (40 pg/mL) throughout development. In females, estrogen levels are similar to those in males until 9 months after metamorphosis is complete and then increase throughout development. Female laryngeal synapses have low quantal contents until 24 months; quantal content increases significantly between 24 and 26 months, and high quantal contents are maintained thereafter. Measures of reproductive maturation, ovary, and oviduct weights, are strongly and positively correlated with estrogen level in 16- to 26-month females, while oocyte maturation is age dependent. Estrogen level and quantal content are not well correlated in these females. Ovariectomy at 24 months prevents the expected increase in quantal content and ovariectomy at 28 months results in a decrease in quantal content. Thus, the sex difference in efficacy of the laryngeal synapse develops under the influence of the ovary and requires the ovary for maintenance of strong synapses in adulthood. While the influence of the ovary is most likely due to estrogen secretion, the pattern of estrogen secretion required for maturation of the synapse in females is not known.

The Air Pollution and Health: a European Approach (APHEA) project is a coordinated study of the short-term effects of air pollution on mortality and hospital admissions. Five West European cities (i.e., London, Amsterdam, Rotterdam, Paris, Milano) contributed several years of hospital admissions data for all respiratory causes. In the current study, the authors describe the results obtained from the quantitative pooling (meta-analysis) of local analyses. The diagnostic group was defined by ICD 460-519. The age groups studied were 15-64 y (i.e., adults) and 65 + y (elderly). The air pollutants studied were sulfur dioxide; particles (i.e., Black Smoke or total suspended particles); ozone; and nitrogen dioxide. The pollutants were obtained from existing fixed-site monitors in a standardized manner. We used Poisson models and standardized confounder models to examine the associations between daily hospital admissions and air pollution. We conducted quantitative pooling by calculating the weighted means of local regression coefficients. We used a fixed-effects model when no heterogeneity could be detected; otherwise, we used a random-effects model. When possible, the authors investigated the factors correlated with heterogeneity. The most consistent and strong finding was a significant increase of daily admissions for respiratory diseases (adults and elderly) with elevated levels of ozone. This finding was stronger in the elderly, had a rather immediate effect (same or next day), and was homogeneous over cities. The elderly were affected more during the warm season. The Sulfur dioxide daily mean was available in all cities, and it was not associated consistently with an adverse effect. Effects were present in areas in which more than one station was used in the assessment of daily exposure. Some significant associations were observed, although no conclusion that related to an overall particle effect could be drawn. The effect of Black Smoke was significantly stronger with high nitrogen dioxide levels on the same day, but nitrogen dioxide itself was not associated with admissions. The ozone results were in good agreement with the results of similar U.S. studies. The coherence of the results of this study and other results gained under different conditions strengthens the argument for causality.

In Xenopus laevis frogs, sex differences in adult laryngeal synapses contribute to sex differences in vocal behavior. This study explores the development of sex differences in types of neuromuscular synapses and the development and hormone regulation of sex differences in transmitter release. Synapses in the juvenile larynx have characteristics not found in adults: juvenile muscle fibers can produce subthreshold or suprathreshold potentials in response to the same strength of nerve stimulation and can also produce multiple spikes to a single nerve stimulus. Juvenile laryngeal muscle also contains the same synapse types (I, II, and III) as are found in adult laryngeal muscle. The distribution of laryngeal synapse types in juveniles is less sexually dimorphic than the distribution in adults. Analysis of quantal content indicates that laryngeal synapses characteristically release low amounts of transmitter prior to sexual differentiation. Quantal content values from male and female juveniles are similar to values for adult males and are lower than values for adult females. When juveniles are gonadectomized and treated with exogenous estrogen, quantal content values increase significantly, suggesting that this hormone may increase transmitter release at laryngeal synapses during development. Gonadectomy alone does not affect quantal content of laryngeal synapses in either sex. Androgen treatment decreases quantal content in juvenile females but not males; the effect is opposite to and smaller than that of estrogen. Thus, muscle fiber responses to nerve stimulation and transmitter release are not sexually dimorphic in juvenile larynges. Transmitter release is strengthened, or feminized, by the administration of estradiol, an ovarian steroid hormone. © 1995 John Wiley & Sons, Inc.

Under physiological conditions, the response of Xenopus laevis laryngeal muscle fibers to nerve stimulation is sexually differentiated; subthreshold potentials are common in males and rare in females. This sex difference in muscle fiber response is correlated with sex differences in vocal behavior. Quantal analyses at male and female laryngeal synapses were performed to determine if there is a sex difference in synaptic strength. Quantal content at laryngeal synapses is significantly higher in females than in males. Values for quantal content in males can be increased by raising extracellular calcium concentration. There is no sex difference in miniature endplate potential amplitude suggesting that ACh receptor number or properties are not different in the sexes. Sex differences in synaptic strength thus appear presynaptic in origin; transmitter release is less in males. Ultrastructural analyses of the laryngeal motor terminal indicate that there is no sex difference in the length of active zones or in the number of channels per length of active zone. Thus, ultrastructural characteristics of the laryngeal motor terminal do not account for the pronounced sex difference in quantal content.

The relative contributions of innervation and androgen to three muscle fiber properties--twitch type, size, and number--were examined in the sexually dimorphic, androgen-sensitive laryngeal muscle of Xenopus laevis. In adults, the muscle contains all fast-twitch fibers in males and fast- and slow-twitch fibers in females; laryngeal muscle fibers are larger and more numerous in males than in females. Juvenile larynges are female-like in both sexes; male laryngeal muscle is subsequently masculinized by androgen secretion during postmetamorphic development. Because both laryngeal motor neurons and muscle fibers are androgen sensitive during masculinization, we examined the role of the nerve in androgen-regulated muscle fiber development. Laryngeal muscle of male and female juvenile frogs was unilaterally denervated, and effects on muscle fiber type, size, and number were examined 4 weeks later. Half of the frogs received a dihydrotestosterone pellet at the time of denervation. Androgen treatment converts laryngeal muscle from mixed slow and fast to all fast twitch in both innervated and denervated muscle. Thus, the nerve is not required for androgen- regulated fiber type expression in either sex. Denervation produces muscle fiber atrophy and androgen treatment induces muscle fiber hypertrophy in male and female larynx. Nerve and hormone effects are independent and additive; fiber size in androgen-treated denervated muscle is greater than in untreated innervated muscle, and fiber size in androgen-treated denervated muscle is smaller than in androgen- treated innervated muscle. There is no sex difference in the effects of innervation or androgen on fiber size. Denervation causes laryngeal muscle fiber loss in males but not in females. Androgen treatment protects male laryngeal muscle from denervation-induced fiber loss and causes fiber addition in innervated female laryngeal muscle. We conclude that there is a sexually dimorphic interaction between innervation and androgen in control of laryngeal muscle fiber number.

Masculinization of the larynx in Xenopus laevis frogs is essential for the performance of male courtship song. During postmetamorphic (PM) development, the initially female-like phenotype of laryngeal muscle (slow and fast twitch fibers) is converted to the masculine form (entirely fast twitch) under the influence of androgenic steroids. To explore the molecular basis of androgen-directed masculinization, we have isolated cDNA clones encoding portions of a new Xenopus myosin heavy chain (MHC) gene. We have detected expression of this gene only in laryngeal muscle and specifically in males. All adult male laryngeal muscle fibers express the laryngeal myosin (LM). Adult female laryngeal muscle expresses LM only in some fibers. Expression of LM during PM development was examined using Northern blots and in situ hybridization. Males express higher levels of LM than females throughout PM development and attain adult levels by PM3. In females, LM expression peaks transiently at PM2. Treatment of juvenile female frogs with the androgen dihydrotestosterone masculinizes LM expression. Thus, LM appears to be a male-specific, testosterone-regulated MHC isoform in Xenopus laevis. The LM gene will permit analysis of androgen-directed sexual differentiation in this highly sexually dimorphic tissue.

Evaluation of the temporomandibular joint has been limited by the inability of current technology to image complex morphology and motion in three dimensions. An engineering design program, I-DEAS, has been used to construct solid models from magnetic resonance images. A dried skull with an acrylic resin temporomandibular disc replica, immersed in water, provided sagittal and coronal MR images. Linear dimensions and disc volumes obtained from the models were compared with the original and found to be consistent, within the limits imposed by the slice thickness. We have applied the method to the living joint in an asymptomatic volunteer, and report our initial experience in demonstrating the spatial relationships and motion of the joint components.

A German shepherd dog was treated initially for signs of urinary tract infection; subsequently, signs of spinal pain and neurologic deficits developed. Fungal hyphae were found in the urine sediment, and spinal radiography revealed changes in the vertebrae and intervertebral disks at the levels of T3 to T8, T12 to T13, L3-4, and L5-6, consistent with diskospondylitis. Fungal cultures of urine and specimens from spinal lesions yielded Aspergillus terreus. Itraconazole (5 mg/kg of body weight, PO, q 24 h) was used to treat this infection, and locomotion improved. Sudden death occurred 4 weeks after treatment was initiated; this was attributed to exsanguination associated with a weakened renal artery. This dog was raised in Florida and resided in central Virginia. The disseminated aspergillosis found in this dog was not limited to the hot arid climates that some reports suggest are optimal conditions for growth.

Temporal constraints on androgen regulated masculinization of three sexually dimorphic laryngeal properties--tension, fiber type, and fiber recruitment--were examined in Xenopus laevis frogs. Endocrine state was manipulated at PM0 when the larynx is similar in males and females, at PM2 when the larynx begins sexual differentiation, and at PM6 when sexual differentiation is complete. Removing the testes in developing males (PM0 or PM2) completely arrests laryngeal masculinization. Masculinization resumes when testosterone is replaced later in development (PM2 or PM6, respectively). Thus, testicular secretions, in particular androgens, are required for laryngeal masculinization. The ability of androgens to masculinize tension, fiber type, and fiber recruitment in developing and adult larynges was also determined. Five weeks of testosterone treatment in PM0 or PM2 males and females completely masculinizes laryngeal tension and fiber type, but only partially masculinizes fiber recruitment. However, fiber recruitment can be fully masculinized in PM6 males castrated at PM2. We conclude that androgen induced masculinization of tension and fiber type are not temporally constrained but that androgen induced masculinization of fiber recruitment is. Prolonged androgen treatment can override the temporal constraints on masculinization of the larynx. Testosterone treatment for more than 6 months fully masculinizes fiber recruitment in developing (PM0 or PM2) females. In addition, prolonged treatment (greater than 9 months) completely masculinizes tension, fiber type, and fiber recruitment in adult females; these properties were not fully masculinized by shorter (1-3 months) treatments in adult females. Testosterone induced masculinization in females is maintained for up to 8 months following testosterone removal; thus androgen effects are long lasting and possibly permanent.

Here we describe a new octoploid species of clawed frog from the Itombwe Massif of South Kivu Province, Democratic Republic of the Congo. This new species is the sister taxon of Xenopus wittei, but is substantially diverged in morphology, male vocalization, and mitochondrial and autosomal DNA. Analysis of mitochondrial “DNA barcodes” in polyploid clawed frogs demonstrates that they are variable between most species, but also reveals limitations of this type of information for distinguishing closely related species of differing ploidy level. The discovery of this new species highlights the importance of the Itombwe Massif for conservation of African biodiversity south of the Sahara.

A 3-year-old 4-kg neutered male domestic shorthair cat died within 5 days after onset of fever and respiratory distress. At necropsy, all tissues were icteric, and the liver had a diffuse reticular pattern. Histologically, hepatitis and encephalitis were associated with Toxoplasma gondii tachyzoites. Toxoplasma gondii female gamonts and oocysts were found in epithelial cells of intact villi and in epithelial cells desquamated into the lumen. Finding of acute hepatitis and T gondii oocysts in an adult cat without detectable immunodeficiency is unusual, because adult cats rarely have clinical signs of toxoplasmosis during the oocyst-shedding phase.

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

This paper reviews four treatment parameters that have become commonly used in the program evaluation literature: the average treatment effect, the effect of treatment on the treated, the local average treatment effect, and the marginal treatment effect. We derive simply computed closed-form expressions for these treatment parameters in a latent variable framework with Gaussian error terms. These parameters can be estimated using nothing more than output from a standard two-step procedure. We also briefly describe recent work that seeks to go beyond mean effects and estimate the distributions associated with various outcome gains. The techniques presented in the paper are applied to estimate the return to some form of college education for various populations using data from the National Longitudinal Survey of Youth.

The problem of mixing four-dimensional (4-D) equipped aircraft (aircraft equipped with onboard guidance systems that can predict and control the touchdown time of an aircraft to an accuracy of a few seconds throughout the descent) with unequipped aircraft in the terminal area has been investigated via a real-time air traffic control simulation study. The objective of this study was to develop scheduling algorithms and operational procedures for various traffic mixes that ranged from 25 to 15% 4-D equipped aircraft. Results indicate substantial reduction in controller workload and an increase in orderliness when more than 25% of the aircraft are 4-D equipped. Moreover, this is accomplished without increasing the workload or adding delays for the unequipped aircraft.

1. During wind-evoked turning in the cockroach the mesothoracic (T2) legs tend to move in antiphase with the ipsilateral metathoracic (T3) legs, although this relationship is not absolute. 2. Intracellular stimulation of giant interneurons coupled with extracellular records from leg nerves 6Br4 and 5r1 indicate some substantial differences between the responses in T2 and those in T3. 3. In T2 there is a predominance of depressor outputs for all dGIs, whereas, in T3 the biases between dGIs are more balanced. Thus, taking the responses of all dGIs into consideration, levator and depressor motor neurons should be equally excited in T3 but not in T2. 4. Also, in T2 there is more variability in the responses than in T3. Although most motor responses in T2 involve initial depressor activity, some cases were found for each dGI in which levator activity consistently preceded depressor activation and some cases where both sets of motor neurons responded essentially at the same time. 5. These data suggest that, in response to GI activity, more factors may be involved in determining the direction of leg movement in T2 than in T3.

Fuel-conservative procedures have been investigated using real-time air traffic control simulations linked to two piloted simulators. The fuel-conservative procedures studied were profile descents and two types of landing approaches, delayed flap and IATA. The investigation determined the effect of these procedures on the ATC system operation. It examined the mixing of aircraft executing fuel-conservative approaches with those executing conventional approaches. The most difficult approach type mix of traffic was found to be 50% conventional and 50% delayed flap. However, for the test scenario chosen, arrival rates of at least 30 aircraft per hour were feasible and resulted in a net average fuel saving, even for the most difficult mix. Also, there is a fuel savings and reduced controller workload for the profile descent procedures.

In order to study the interactions of the EcoRI restriction endonuclease and modification methylase with DNA, we have synthesized the self-complementary octanucleotide, pT-G-A-A-T-T-C-A, which contains the nucleotide sequence of the EcoRI substrate. This octamer can act as a substrate for both the endonuclease and methylase; the enzymatic alteration of this molecule is the same as that of DNA, with cleavage and methylation both occurring at the same positions on either substrate. The optimum temperature for the reaction of the octanucleotide with the endonuclease is 15°C and that with the methylase is 12·5°C. The optimum temperature for the reactions of both of the enzymes with DNA is 37°C. The low temperatures for reactions with the octanucleotide reflect the conditions under which this molecule can serve as a substrate for the enzymes. The Km values and turnover numbers for the EcoRI endonuclease using both the synthetic octanucleotide and simian virus 40 (SV40) DNA as substrates were determined. These constants are, respectively, 7 × 10−6 m and 4 min−1 for the endonuclease-octamer reaction and 3 × 10−8 m and 3 min−1 with SV40 DNA. Although the Km does not measure affinity directly, the similarity of turnover numbers on both substrates allows us to conclude that the affinity of the enzyme for SV40 DNA is approximately 200 times greater than for the octanucleotide. The synthetic octanucleotide is self-complementary and can form a duplex structure. Computer analysis of initial reaction-rate data shows that in order to act as a substrate the octamer must be a dimer. This observation, together with the correspondence of the temperature optima for both enzymatic reactions to the tm value for the double-stranded form of the octanucleotide (17 to 19°C), lead us to conclude that the substrate for both EcoRI enzymes is a double-helical segment of DNA containing the central hexamer of the octanucleotide. It is unlikely that any cruciform rearrangement is required for enzyme activity.

Microcomputers could help reduce two of the principal fears of the elderly: inadequate income and loss of independence; yet there are indications that the elderly do not use computers very extensively because they see them as too complicated or because some of the physical impairments of advancing age make using standard systems too difficult for them. Previous research has shown a high degree of interest in computers among the aging, even in those over 85; however, the research has not focused on the elderly's special needs in the human-computer interface. Research is required on alternative input devices, such as the touchscreen and voice recognition, on menus and screen design, and on the use of color for coding or display background.

1. Flight activity can be initiated in legless cockroaches by stimulating a single dorsal giant interneuron (dGI) intracellularly with a train of current pulses. Ventral giant interneurons (vGIs) do not initiate flight activity. 2. The initial directional responses in leg motor neurons which are characteristic of running are still evoked prior to flight initiation. 3. For short flights the number of bursts in wing muscles (flight bursts) increases as the number of action potentials in the dGI is increased. 4. Paired stimulation of dGIs evokes longer flight sequences. Moreover, a subthreshold train of action potentials in a single dGI can evoke flight if the train arrives within 500 ms of a previous flight. 5. In flight motor neurons (FMNs), an initial depolarization precedes rhythmic oscillations that are associated with flight bursts. The timing of dGI activity is appropriate for eliciting the initial depolarization as well as the rhythmic oscillations. Stimulation of single dGIs with trains of current pulses evokes both phases of the FMN response, probably via polysynaptic pathways. 6. Activity in the intracellularly stimulated dGI need not reach the mesothoracic ganglion directly in order to evoke coordinated flight activity in both the meso- and metathoracic ganglia.

The clawed frog Xenopus laevis uses sexually dimorphic vocalizations, mate calling and ticking, to advertise reproductive state. The basic unit of vocalization is a brief click, produced by the movement of cartilagenous disks located within the larynx. The rate of click production in the male-specific mate call (71 Hz) is an order of magnitude faster than the rate of click production in female typical ticking (6 Hz). To determine if vocalization rate is constrained by the periphery, male and female larynges were isolated and response of the muscles to nerve stimulation was studied. Laryngeal muscle response is markedly dimorphic in the 2 sexes, both in the amplitude potentiation of electromyograms and in the rate at which discrete tension transients can be produced. At 6 Hz (ticking), both sexes generate discrete tension transients in response to each stimulus pulse. In response to nerve stimulation at 71 Hz (mate calling), male laryngeal muscle generates discrete tension transients while female laryngeal muscle does not. Since expression of sex-specific vocalizations is regulated by androgenic hormones, responses of laryngeal muscle to nerve stimulation in androgen-treated adult females and castrated adult males were also examined. The responses of laryngeal muscle from castrated and intact males are similar. Androgen-treated female larynx is partially masculinized but does not produce tension transients at the mate call rate. These physiological results are in close agreement with behavioral observations. Sounds produced by the isolated larynx were nearly identical in spectral properties to those produced by an intact male. We determined that the production of a discrete tension transient is prerequisite to click production. Thus, one reason females do not mate call, even when treated with androgens, is that female laryngeal muscle cannot produce discrete tension transients at a rapid rate.

ONE OF THE MOST PERSISTENT MYTHS that Canadian historians perpetuate is that of the honourable and just policy Canada followed in dealing with the Plains Indians. First enunciated in the Canadian expansionist literature of the 187os as a means to emphasize the distinctive Canadian approach to and the unique character of the Canadian west, 1 it has been given credence by G.F.G. Stanley in his classic The Birth of Western Canada, • and by all those who use Stanley's work as the standard interpretation of Canada's relationship with the Plains Indians in the period 187o-85 . Thus students are taught that the Canadian government was paternalistic and far-sighted in offering the Indians a means to become civilized and assimilated into white society by the reserve system, and honest and fair-minded in honouring legal commitments made in the treaties. • The Plains Indians, and particularly the Plains Cree, are said to be a primitive people adhering to an inflexible system of tradition and custom, seeking to protect themselves against he advance of civilization, and taking up arms in rejection of the reserve system and an agricultural way of life. 4 This traditional

1. The influence of ablating metathoracic legs upon the GI-to-motor response was studied inPeriplaneta americana. 2. The motor response to intracellular stimulation of individual dGIs was significantly greater after the metathoracic legs were removed than before ablation. 3. No change was seen in the response of metathoracic motor neurons when mesothoracic legs were removed. 4. This effect could also be detected in long term experiments. Motor responses in animals that had undergone leg ablation 3–7 days prior to recording motor responses also showed significant increases over control animals. 5. A similar effect could be seen by simply tying the metathoracic legs in such a way as to prevent them from making leg contact. 6. Leg removal does not significantly impair the animal's ability to escape from a natural predator. 7. The results indicate that the state of the metathoracic legs influences the response of mesothoracic motor neurons to GI activation. However, the reverse is not the case.

Although social behavior has been studied by sociologists, the absence of references to such work is strikingly apparent in many discussions of the behavioral aspects of obesity. This paper presents some sociologic notions and research that can contribute to the health care professional's understanding of the problems of obesity and its treatment possibilities. One such approach could well be the use of weight control programs predicated on rearranging the social environment in which obese people live and eat.

1 Alexander, B. (chairman), "Report of Department of Transportation Air Traffic Advisory Committee," Vols. 1 and 2, Dept. of Transportation, Washington, D.C., Dec. 1969. Blumstein, A., "The Landing Capacity of a Runway," Operations Research, Vol. 7, No. 6,1959, pp. 752-763. FAA, "The National Aviation System Plan, Ten Year Plan 1972-1981," (71-01686), March 1971, FAA, Washington, D.C. FAA, "The National Aviation System Policy Summary 1971," (7-10686), March 1971, FAA, Washington, D.C. Lister, S. F. and Raisbeck, G., "Approach to the Establishment of Practical Air Traffic Control Safety Goals," Contract No. FA70WA-2141, Little, Cambridge, Mass., May 1971. Raisbeck, G., Koopman, B. O., et al., "Air Traffic Control System Capacity," Contract No. DOT-FA70WA-2141, Little, Cambridge, Mass., Aug. 1970. Schriever, B. A. and Seifert, W. W., Air Transportation 1975 and Beyond: A Systems Approach, The MIT Press, Cambridge, Mass., 1968. Simpson, R., "Evaluation of Air Traffic Control Models and Simulations," Contract No. DOT-TSC-77, June 1971, MIT, Cambridge, Mass. Wilhelm, W. E., "Following Theory With Applications," Ph.D. dissertation, 1972, Virginia Polytechnic Inst. and State Univ., Blacksburg, Va.

The design of d small experimental breeder reactor which it is believed will not be subject to the chemical difficulties characteristic of the HRE-2 is presented. The reactor simulates in a small size the nuclear, chemical, mechanical, and hydrodynamic characteristics believed typical of large reactors of this type. The simulation is made possible largely by the use of a beryllium reflector between the uranyl sulfate solution core and the thoria pellet fertile blanket. The nuclear calculations indicate an initial gross breeding ratio of 1.07 for a completely blanketed reactor fueled with U/sup 233/. (auth)

The application of the sand columm extraction, fractional coacervation, and coacervate extraction methods to the molecular weight fractionation of polypropylene is described. Extremely reproducible results are given by the sand column method, and ten fractions taken by this method are adequate for characterization of the usual polypropylene distribution. The variation between the molecular weight distributions derived from six fractionations of a test polypropylene by the three methods was small and indicates that fraction polydispersity probably contributes negligibly to any deviation of the experimental distributions from the true distribution. Polypropylenes made with aluminum triethyl-transition metal trichloride catalysts contain relatively large amounts of low molecular weight polymer and have broad distributions similar to that of low-pressure polyethylene. All such polypropylene samples had distributions which were described well by a logarithmic normal equation with a constant standard deviation. The distribution was not altered when the aluminum triethyl in the catalysts was replaced by aluminum triisobutyl. Catalysts containing vanadium as the transition metal, however, produced polypropylenes with distributions distinctively different from those made with titanium trichloride.

Randomly sampled linear systems with linear or non-linear feedback loops are studied by a stochastic Lyapunov function method. The input in this paper is assumed zero; driven systems will be treated in a later paper. Improved criteria for stability (with prebability one, on s th moment s > 1 , or in mean-square) are given when the sequence of holding times are independent. The method is relatively straightforward to apply, especially in comparison with the direct methods, and allows the study with nonlinear feedback or nonstationary holding times. A randomly sampled Lur'e problem is studied. Numerical results, describing some interesting phenomena, such as, jitter stabilized systems are presented.

The chemical synthesis of a tetradecadeoxyribonucleotide, d-EtSp(A-T-G-G-A-A-A-C-T-G-C-G-G-C), is described. This oligomer, designated Fragment 4δ, constitutes the 5′-terminus of the plus strand of a projected duplex coding for S-Peptide 2–14 derived from Ribonuclease A. The Fragment was constructed by block condensation via a phosphorothioate anchor. Complications due to inadvertent phosphotriester condensations are discussed. Arguments justifying the sequence selection are presented.

Maximum clenching on an equilibrated occlusal splint yielded an increase of 17% in overall muscle activity over that of maximum intercuspation contributed mainly by masseter muscles. Maximum clenching on an anterior occlusal splint yielded a decrease of 13% in overall muscle activity compared with that of an equilibrated occlusal splint. When maximum clenching was performed with six left-sided teeth removed from contact while the left second molar remained in contact, there was no significant change in muscle activity when compared with that of an equilibrated occlusal splint. When left-sided muscles were compared with right-sided muscles for the same situation, there was no significant change. When maximum clenching was performed with all left-sided teeth removed from contact, there was a decrease of 21% in overall muscle activity compared with that of an equilibrated occlusal splint. When left-sided muscles were compared with right-sided muscles for the same situation, there was no significant change. Changes in the number of tooth contacts did not cause changes in the overall muscle activity during maximum clenching. Changes in the position of the tooth contacts altered the overall muscle activity during maximum clenching. Changes in occlusal contact symmetry did not cause changes in symmetry of muscle pairs during maximum clenching. Unilateral support produced the subjective response of pressure on the contralateral TMJ during maximum clenching.

This data record report summarizes the results from two tests involving limestone concrete test aerosol in a steam-air environment and one test in a dry air environment. This research sponsored by the US Nuclear Regulatory Commission was conducted in the Nuclear Safety Pilot Plant at the Oak Ridge National Laboratory. The purpose of this project is to provide a data base on the behavior of aerosols in containment under conditions assumed to occur in postulated LWR accident sequences; this data base will provide experimental validation of aerosol behavioral codes under development. In the report a brief description is given of each test together with the results in the form of tables and graphs. Included are data on aerosol mass concentration, aerosol fallout and plateout rates, total mass fallout and plateout, aerosol particle size, vessel atmosphere pressure, vessel atmosphere temperatures, temperature gradients near the vessel wall, and steam condensation rates on the vessel wall.