The Simons Observatory: Cryogenic half wave plate rotation mechanism for the small aperture telescopes.

We present the requirements, design, and evaluation of the cryogenic continuously rotating half-wave plate (CHWP) for the Simons Observatory (SO). SO is a cosmic microwave background polarization experiment at Parque Astronómico de Atacama in northern Chile that covers a wide range of angular scales using both small (⌀0.42 m) and large (⌀6 m) aperture telescopes. In particular, the small aperture telescopes (SATs) focus on large angular scales for primordial B-mode polarization. To this end, the SATs employ a CHWP to modulate the polarization of the incident light at 8 Hz, suppressing atmospheric 1/f noise and mitigating systematic uncertainties that would otherwise arise due to the differential response of detectors sensitive to orthogonal polarizations. The CHWP consists of a 505 mm diameter achromatic sapphire HWP and a cryogenic rotation mechanism, both of which are cooled down to ∼50 K to reduce detector thermal loading. Under normal operation, the HWP is suspended by a superconducting magnetic bearing and rotates with a constant 2 Hz frequency, controlled by an electromagnetic synchronous motor. We find that the number of superconductors and the number of magnets that make up the superconducting magnetic bearing are important design parameters, especially for the rotation mechanism's vibration performance. The rotation angle is detected through an angular encoder with a noise level of 0.07 µrad s. During a cooldown process, the rotor is held in place by a grip-and-release mechanism that serves as both an alignment device and a thermal path. In this paper, we provide an overview of the SO SAT CHWP: its requirements, hardware design, and laboratory performance.

Interaction structure of husbands' and wives' disclosure of marital conflict to their respective best friend.

Husbands' and wives' conversations with their respective best friend (N = 88) were coded to assess spouses' and friends' mutual influence in regulating support and interference with regard to spouses' marriage and to assess the impact of spouses' sex and marital satisfaction on the conversation processes. Dissatisfied husbands and wives expressed fewer positive and more negative views of marriage than satisfied husbands and wives and the friends in the 2 groups. There were no group and no sex differences in interference sequences. There were group and sex differences in support sequences. Friends of satisfied wives and those of dissatisfied husbands were more likely than satisfied wives and dissatisfied husbands to get support for their positive views of marriage. The findings are discussed with reference to the specific effects of outsiders' support and interference on satisfied and dissatisfied spouses.

Categorization in unsupervised neural networks: the Eidos model.

Proulx and Begin (1995) recently explained the power of a learning rule that combines Hebbian and anti-Hebbian learning in unsupervised auto-associative neural networks. Combined with the brain-state-in-a-box transmission rule, this learning rule defines a new model of categorization: the Eidos model. To test this model, a simulated neural network, composed of 35 interconnected units, is subjected to an alphabetical characters recognition task. The results indicate the necessity of adding two parameters to the model: a restraining parameter and a forgetting parameter. The study shows the outstanding capacity of the model to categorize highly altered stimuli after a suitable learning process. Thus, the Eidos model seems to be an interesting option to achieve categorization in unsupervised neural networks.

Selecting dominants and subordinates at conflict outcome can confound the effects of prior dominance or subordination experience.

Individuals with a previous experience of dominance are likely to be dominants in further encounters. To test this effect, individuals with a previous experience of dominance are used for the experiments. One way to obtain such individuals is to let opponents 'self-select': encounters between pairs of more or less equivalent opponents are staged and one selects ex post facto the dominant and subordinate from the ensuing conflict. This paper formally shows that the selection of dominant and subordinate animals modifies the dominance probability functions of the two corresponding sub-samples of animals. As a result, the propensity of previous winners to win again and of previous losers to repeat their loss can be attributed to this artefact rather than to prior social experience. This result has serious methodological implications. When one relies solely on selection to obtain winners and losers, equiprobability is no longer the appropriate null hypothesis against which prior social experience effects have to be tested. To clearly demonstrate the effect of dominance experience, one must show that prior winners defeat neutral opponents in at least two-thirds of all cases; reciprocally, to show that prior subordinate experience plays a role, prior losers must win in less than one-third of all fights against neutral opponents; finally, to conclude that a combined effect of the two kinds of prior experience is in operation, one must obtain that prior winners defeat prior losers in more than 83% of all planned conflicts. The present result does not imply that experience effects are not at work when the selection procedure is used, but that the procedure used to show their effects is inadequate because effects of experience on a subsequent encounter are confounded with those introduced by statistical selection.

Effect of fiber on cholesterol metabolism in the Coturnix quail.

This experiment involving 288 Coturnix quail was conducted to determine the effects of various fiber sources (alfalfa, wheat bran, dried brewer's grain, cellulose, and pectin) on serum, liver and egg yolk cholesterol, and egg production. The fiber sources were added at a rate to provide 6.25% fiber to a corn-soybean meal diet and fed for a 28-day experimental period. Serum, liver, and egg cholesterol levels were measured as pen composite samples at the end of the experimental period. No difference was exhibited in egg yolk cholesterol among any of the groups (P greater than .10). Liver and serum cholesterol levels were elevated in the birds fed the pectin and wheat brain diets as compared with that in birds fed the other fiber source; also, metabolizable energy intakes and eggs per hen day (EHD) were decreased for both groups. When data were adjusted for EHD by covariance analysis, the treatment differences no longer appeared (P greater than .05). These results indicate that 1) there is a basal quantity of cholesterol deposited in the egg on which fiber intake, energy consumed, or egg production have very little effect and that 2) there is an inverse relationship between serum and tissue cholesterol levels and the total quantity of cholesterol excreted via the egg.

Feed efficiency and gain responses to protein levels in two lines of birds selected for oxygen consumption.

Two experiments were conducted to investigate the response of two populations of chickens, divergently selected for high and low oxygen consumption, to varying protein levels. Protein levels used for Experiments 1 and 2 were 16, 18, 20, and 22% and 20, 22, 24, and 26%, respectively. The birds were weighed initially and weekly to 4 weeks of age. Feed consumption was ad libitum with amounts consumed recorded weekly. Gross feed efficiency was computed per pen as the difference between initial and weight at 4 weeks divided by feed consumed adjusted for spillage. The results from these experiments indicate that at low protein levels both lines were equally efficient, but, as the level of protein was increased, the low line was increasingly more efficient while the high line became less efficient. Gain for the low O2 birds was greater than the high O2 birds in all cases with both lines increasing in gains equally with increased protein levels.

The effect of non-protein energy source and age on hexokinase concentration in chick muscle.

Muscle hexokinase was ascertained in the gastrocnemius muscles of 160 male chicks. Observations were made in four age groups and two diets. No differences in enzyme activity were observed which could be attributed to the feeding of either the high-carbohydrate or high-fat diet. Hexokinase activity declined significantly between 6 and 12 days of age in the chicks fed the respective diets.

The effect of pantothenic acid on the diet of growing chicks on energy utilization and body composition.

Two experiments were conducted to investigate the effects of varying levels of pantothenic acid on the efficiency of energy utilization and changes in body composition of the growing chick. The results indicate that a pantothenic acid deficiency does not interfere with the chick's ability to obtain metabolizable energy from the diet. The data do show that the efficiency of energy utilization and body composition were markedly affected when chicks were fed diets deficient in pantothenic acid. In both experiments, protein, fat and energy stores were significantly reduced when pantothenic acid-deficient diets were fed. Increased estimates of heat increment per gram of diet were observed when levels of pantothenic acid below the N.R.C. (1971) recommended level of 10 mg. per kg of diet were fed.

The effect of non-protein energy sources on the ability of the chick to synthesize glucose-6-phosphatase.

Two experiments were conducted to investigate the relationship of energy source, age and glucose-6-phosphatase activity in the chick. In the first experiment liver glycogen and glucose-6-phosphatase were assayed in chicks of four age groups being fed either a high-fat or high-carbohydrate diet. It was observed that the feeding of the high-fat diet resulted in higher glucose-6-phosphatase activity and lower glycogen levels than did the feeding of the carbohydrate diet. Age was found to significantly influence enzyme activity. Both glucose-6-phosphatase and liver glycogen were found to be negatively correlated in the fat fed chicks. In the second experiment chicks were fed either a high-fat or high-carbohydrate diet for 28 days. Liver glucose-6-phosphatase activity was determined in representative samples of chicks from each group to establish basal levels. The diets were then reversed for a three-day period, after which the chicks were returned to their initial diets. Glucose-6-phosphatase was analysed at each step. Variation in enzyme activity in the chicks initially fed the high-fat diet could be attributed to differences in body weight. However, those chicks originally fed the carbohydrate diet did exhibit a true metabolic adaption when fed the high-fat diet.

The effect of non-protein energy source and age on the blood glucose level and the muscle glycogen content of young chicks.

Blood glucose levels and skeletal muscle glycogen concentrations were observed in 160 male chicks. Observations were made in four age groups and two diets. Carbohydrate diets resulted in higher blood glucose levels and glycogen concentrations than did fat diets. Age was found to significantly influence glycogen concentration in both diets. The linear regression of skeletal glycogen on blood glucose levels was significant in carbohydrate fed chicks.