Low Level Of Significance Research Articles

Far-infrared emission from the intracluster medium

We have analyzed IRAS image data using a random position, multiple- aperture photometry method to study diffuse far-infrared emission for a sample of 56 clusters of galaxies at 60 and 100 microns. Five of the clusters in the sample exhibit excess far-infrared emission, but at low levels of significance. For A496 (Perseus) and MKW 1 this emission appears to be associated with a strong point source: in A2344, the observed excess is probably due to a foreground cirrus cloud. Two clusters, A262 and A2670, show evidence for extended diffuse emission. This emission is unlikely to be due to point sources associated with the clusters. In these two clusters, the diffuse emission shows evidence of being extended along the cluster's major axis. Far-infrared maps at 60 and 100 microns are presented for these five clusters. We find that contamination due to diffuse Galactic cirrus represents the major source of uncertainty in the measurement of far-infrared emission. The mean cluster fluxes for the sample as a whole are 44 and 107 mJy for a 4' diameter aperture at 60 and 100 microns, respectively. The corresponding fluxes for a 10' diameter aperture are 138 and 253 mJy at 60 and 100 microns. Photometry for the entire sample shows statistical evidence for excess emission at 60 microns associated with clusters in apertures 4' and 10' in diameter. This result is unlikely to be caused by random sampling errors. The flux distributions are analyzed for evidence that excess far-infrared radiation correlates with cluster environmental characteristics. Although we find evidence that poorer X-ray clusters are stronger fare emitters, this result is tentative owing to the small sample sizes involved. The far-infrared luminosities, dust temperatures, and dust masses which these results imply are also presented. Finally, the origin and possible heating mechanism for dust in the intracluster medium is discussed.

Seasonal changes in the population of the mite Unionicola intermedia (Hydrachnellae, Acari) from the freshwater mussel Anodonta anatina (Unionidae)

Although numbers were low in winter, males of Unionicola intermedia were found throughout the year. A mean of 2.5 (±0.26 SE) males per mussel was found with a range of 0 to 20. Females had a mean of 13.07 (±0.87 SE) per mussel and a range from 0 to 57, with the highest mean in August. The incidence of males was much lower than that of females. Nymphs and females were highly aggregated and males showed aggregation at a lower level of significance for nine months of the year. Although the primary sex ratio is unknown, the tertiary sex ratio is 86% female and on a monthly basis ranged from 68.9% to 96.7% female. It is speculated that reproduction is arrhenotokous. The sex ratio and the significant seasonal variations of the active stages may be influenced by the dispersal pattern of this species and by the biology of its host.

U.S. Common stock prices, 1871?1970: playing with dummies

The received wisdom that the levels of many economic time series are generated by processes with a unit autoregressive root has been called into question by recent work of Perron. When break points, or interventions, in the time series are allowed it emerges that the unit roots hypothesis can often be rejected at quite low significance levels. Taking for illustration a single time series, U.S. common stock prices, we demonstrate that Perron's conclusions are very sensitive to the choice of break point, and that the data contain little support for the particular choice imposed by Perron.

Bulk flows, shear, and the great attractor

view Abstract Citations (16) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Bulk Flows, Shear, and the Great Attractor Kaiser, Nick Abstract The large inferred distance to the great attractor may indicate the need for more large-scale power than is provided by the "standard" cold dark matter model. In an attempt to quantify this I consider some statistics which measure the ratio of the bulk flow speed to the velocity shear averaged over a sample of galaxies. These should correspond approximately to the distance derived in fitting a "great attractor" model, and their probability distributions can be calculated given a theoretical fluctuation power spectrum providing tests for the shape of the power spectrum independent of the uncertain empirical normalization. These statistics are extracted from the elliptical galaxy sample of Dressler et al. and are compared with the predictions for various theoretical power spectra. In all models the distances have a broad distribution. I find no evidence for an excess of large-scale power relative to the cold dark matter predictions; there is, if anything, a suggestion of less large-scale power, though at a low level of significance. Peebles' isocurvature baryon fares less well; here ~ 90% of observers would see a shear to flow ratio less than that observed. If there is a conflict between these observations and the cold dark matter predictions it lies not in the shape of the power spectrum but in the fairly large normalization required. This may prove to be in conflict with the relative velocities of galaxies at small separations, but for the moment this remains an open question. Publication: The Astrophysical Journal Pub Date: January 1991 DOI: 10.1086/169572 Bibcode: 1991ApJ...366..388K Keywords: Computational Astrophysics; Dark Matter; Elliptical Galaxies; Galactic Evolution; Strange Attractors; Astronomical Models; Power Spectra; Taylor Series; Astrophysics; DARK MATTER; GALAXIES: CLUSTERING; GALAXIES: REDSHIFTS full text sources ADS |

A freeze-fracture study of the influence of frost hardening treatments on the plasma membranes of Medicago sativa and Bromus inermis cell suspension cultures

Freeze-fractured suspension cultured cells of alfalfa (Medicago sativa L.) and bromegrass (Bromus inermis Leyss) were examined before and after frost hardening treatments for evidence of plasma membrane adaptation to frost. No chemical fixatives or cryoprotective agents were used and care was taken to ensure that there was no subjective bias in making counts of intramembrane particles. There were no patches of membrane free of intramembrane particles in any of the treatments, and only small differences in intramembrane particles frequencies were found. Cold hardening and abscisic acid hardening may have had different effects on intramembrane particles frequency, but because of the low level of statistical significance this was uncertain. Two arrays of membrane particles (strings and rosettes) were present in all treatments. It is concluded that the technique may be insufficiently sensitive to detect the subtle changes in membrane protein composition that probably accompany adaptation to frost. Key words: Medicago sativa, Bromus inermis, frost hardiness, membrane structure, freeze-fracture.

Persistence of atrazine as affected by selected soil properties

The relationships between selected soil properties and the bioactivity of atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) were investigated in field trials. Bioactivity was determined periodically for up to twelve months on a variety of soil types using oats (Avena sativa L.) as the test plant. The initial bioactivity of atrazine which was assessed 35 days after application was best correlated with the organic matter content (%C) and P reversion characteristics of the soils. Clay content and CEC were also important but at lower levels of significance. Six months after herbicide application, % C, soil pH and P reversion were important predictors of atrazine persistence, whilst both CEC and clay content were poor criteria. Persistence was negatively correlated with % C, but positively with both soil pH and P reversion. Since the dissipation of atrazine in most of the soils was virtually complete after twelve months, the prediction of persistence by the soil properties was poor at that stage. Differences in persistence between trials in close proximity suggest that persistence of the herbicide was more closely linked to soil characteristics than to climatic conditions. Results suggest that current waiting periods, which are recommended for specific crops, can be refined by distinguishing between soils on the basis of soil characteristics that affect adsorption and degradation of atrazine.

Investigating Public Housing Segregation

We investigate the concepts and evidence needed to understand the extent of racial segregation in the federal public housing program operating in metropolitan areas throughout the United States. Over one million units of public housing in urban areas constitute an important, but poorly understood, component of overall housing market segregation. Using data from the U.S. Department of Housing and Urban Development, we describe the degree, distribution, and segregation of minorities in HUD-assisted family and elderly housing. We attempt to explain the level and variation of public housing segregation through examining legislative, programmatic, and regional factors, though differences appear at relatively low levels of statistical significance.

On the existence of the 11‐year cycle in solar activity before the Maunder Minimum

The existence of the 11‐year cycle in solar activity before the Maunder minimum is clearly demonstrated with cosmogenic 10Be in polar ice during 1180‐1500 A.D. For that interval a periodicity of 11.4 ± 0.2 years is found with a high significance level. Indication of a cyclicity that resembles the Hale magnetic cycle is also observed at a lower significance level. A highly variable cyclicity in the band 9.5‐11.5 years is also found in the record of historical aurorae which appears to be well correlated with the 10Be cyclicity for the same time interval. It is concluded that the Schwabe, or 11‐year, cycle and the Hale magnetic cycle were present before and after the Maunder minimum, even though it is not possible to understand the variability of the cycle.

Simulataneous X-ray and optical observations of LMC X-2

The X-ray source LMC X-2 was observed with EXOSAT for -8hours on February 2nd, 1984 with simultaneous photometric and spectroscopic optical coverage. The source was seen at a luminosity of L x ∼ 1.5 10 38erg.s −1 with a mean X-ray spectrum which can be described equally well by either a superposition of a thermal emission of a thin hot (T th∼5keV) plasma and a cooler blackbody radiation (T bb∼1.3keV) or by a comptonized thermal (T co∼3keV) radiation. There is no evidence of iron line. The mean source spectrum is found very alike those of the bright galactic bulge sources. The source is however only moderately variable in X-rays with spectral variations similar to those of Sco X-1 in quiescent state. No coherent periodic (0.016–2500s) pulsations are detected. Large photometric optical variations are present which suggest an orbital period of 6.4h though at a low level of significance. There is no clear correlation however between X-ray and optical variations.

Changes in blood acid-base characteristics, haemoglobin and lactate concentrations due to increasing moderate stress in pigs.

Blood samples were collected by indwelling ear vein catheter from pigs (100 kg body weight) at rest and at different stages of increasing moderate stress. The stress increased from being forced to stand to fixation by maxillary sling alone and combined with stimulation with an electric goad. Stress caused significant decreases in blood pH, base excess and, at lower levels of significance, standard bicarbonate, while pCO2 and lactate increased significantly. Respiration rate was not affected. It is concluded that stress caused a combined respiratory and metabolic acidosis, although both components of the acidosis might originate from changes in muscle metabolism. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Ventriculoatrial or Ventriculoperitoneal Shunts in the Treatment of Hydrocephalus in Children?

The data on all 881 primary or revision shunt operations performed on 158 paediatric patients treated in Gothenburg, Sweden from 1967 to 1984 and 101 patients treated in Oulu, Finland from 1968 to 1983 were pooled for the purpose of comparative evaluation of the function of ventriculoatrial (VA) and ventriculoperitoneal (VP) shunts. Ventriculoperitoneal shunting was the method of choice in Gothenburg and ventriculoatrial shunting in Oulu. The results of the 723 operations (305 VA and 418 VP shunts) were evaluated as the other 158 operations were for ventriculostomas, shunt removals and other procedures. 80 children had exclusively VA shunts and 133 children had exclusively VP shunts. Irrespective of the method of analysis the VP shunts were more frequently infected. The estimated relative risk for obstruction of the shunt (Meyer-Kaplan method) was shown to be significantly higher in VA shunts, but only at a low level of statistical significance (p less than 0.1). All other shunt complications were distributed uniformly in both groups. There was, however, a trend towards a higher mortality among children with exclusively VA shunts. Therefore it was concluded that despite the higher risk for infection in VP shunts, these still should be considered a safer choice, as the complications of VA shunts present greater risks.

Specifying the Dynamics of Industry Concentration

Previous studies generally explain changes in concentration by its initial determinants or by changes in its determinants. Little attention is paid to the dynamic structure of the model. This study provides a framework to sort out adjustment effects in a systematic manner. The empirical model distinguishes from short-term effects and estimates the rate of adjustment when concentration deviates from its level. CONSIDERABLE attention has focused on industry concentration a key element of market structure. While earlier empirical studies examined determinants of the level of industry concentration, a more recent literature focuses on changes in concentration.' These more recent papers typically explain intertemporal changes in concentration by the past levels of industry growth, concentration, advertising intensity and minimum efficient plant size. However, the dynamic relationship between changes in concentration and the levels of the independent variables has not been explicitly specified. Caves and Porter [1980] have argued that explaining changes in concentration by past levels of market structure variables is tantamount to assuming that the sampled industries are in the process of adjusting to a disequilibrium situation. As an alternative, they adopt a long-term equilibrium approach, whereby changes in concentration are explained by lagged changes in the relevant market conditions. They find that this approach as a whole was unsuccessful, exhibiting low levels of significance and a lack of robustness when the cross-section regressions were shifted to different time periods

Stability in Waking-Sleep States in Neonates as a Predictor of Long-Term Neurologic Outcome

Thirty-three full-term neonates were ranked blindly on a scale ranging from the least to the highest "risk" for future neurologic complications on the basis of available perinatal biographies, tests, and examinations performed during the newborn period. Four prolonged polygraphic-behavioral recordings were obtained one week apart beginning at ten days after birth. Five waking and sleep states were scored in each session as percentages of total observation time, giving a total of 20 scores for each baby to be subjected to analysis of variance. These measures also provided individual profile consistency or variability in maintaining waking-sleep states over the selected period of postnatal time. The whole cohort, except three infants who could not be followed adequately, was then reexamined periodically over a period ranging from 3 to 4 years (+/- 6 months) for neurologic and developmental assessments. Except for two scores that produced a low level of statistical significance (P less than .05), the other 18 scores were found to be not associated with long-term outcomes. Even the first two scores were not satisfactory discriminators for the outcome of the individual babies. However, when coefficients of concordance (W) were computed from each individual baby profile, significant statistics (P less than .001) emerged to indicate good correlations between high or low W values in the newborn period and long-term outcomes. All 17 newborns who had W scores greater than 0.9 were found to be normal at follow-up regardless of the poor ranking given several of them during the newborn period. Among the 13 newborns who had W scores less than 0.9, 11 had a poor clinical outcome at follow-up, though several had been ranked initially as falling within the least "risk" group.

Eysenck Personality Inventory and Choice of Psychiatry as a Career

Various investigations have explored motivations behind the choice of the profession of psychiatry. The presence of factors of cultural, social, economic, and psychological origin has been noted, but it is not yet clear which or how factors contribute to the choice in the most determining way. In relation to the psychological factors, emphasis has been placed on neuroticism, extraversion, emotional instability, intolerance of ambiguity, degree of reflectiveness and psychological mindedness (2, 4, 5, 6, 7). It should be noted chat these personality characteristics are assessed in different and sometimes conflicting ways by the various authors. To clarify this problem the Eysenck Personality Inventory (1) was administered to 47 applicants to the School of Specialization in Psychiatry (M age 28.5 + 2.8 yr.; 34 men, 13 women) and to a control group of 60 applicants (48 men, 12 women) to the School of Dentistry at the same university (M age 29.2 2 3.2 yr.). Groups were similar for age and sex. As shown below, applicants to psychiatry scored significantly lower on Neuroticism than applicants to dentistry, a result which conflicts with other findings (3, 6). The dentistry applicants, however, presented a significantly lower index of Psychoticism. No significant difference between the two groups were found for Extraversion. Although the scores on the inventory indicate differences between the groups, these fall within the normal ranges reported by Eysenck This consideration, together with the relatively low levels of statistical significance, suggests that other variables probably play a more incisive role in the choice of psychiatry as a career.

Long-Term Effects of Activity and of Calcium and Phosphorus Intake on Bones and Kidneys of Female Rats

Over a 22-week period, young female rats in conventional cages gained significantly more weight than rats housed with free access to running wheels. A trend toward increased bone density was indicated in runners. In a second test, young female rats were housed under the same conditions for 30 weeks, but the active group was then forced to run in a treadmill for 30 minutes, 5 times a week, over a 43-week period. During this time rats were fed either diets providing adequate Ca (0.5%) and adequate P (0.4%) or high P (1.2%), or low Ca (0.3%) and high P (1.2%). Running appeared to benefit long bone density but could not completely compensate for a high P or a low Ca, high P intake. A bone that received only indirect stress during exercise (atlas) was not significantly affected by running. However, a high P diet significantly decreased atlas bone density, while the negative effect of this diet on the density of long bones was at a lower level of significance. A low Ca, high P diet clearly decreased bone density in all bones investigated. Running had no effect on kidney mineralization, but either a high P or low Ca, high P diet greatly increased the concentration of these minerals in the kidney.

The Relative Importance of Low Significance Level and High Power in Multiple Tests of Significance

When several statistical hypotheses are tested in a study to answer a single research question or to test a single scientific hypothesis, interpretation of the results may be difficult because Type 1 error probabilities cumulate. Researchers often try to solve this problem by reducing the significance level for each test or by applying a multiple-comparison procedure for means. For a constant number of observations, both strategies result in a lower power for each test or comparison of interest, however. Two well-known psychological experiments are reanalyzed in this respect. It is shown that low probabilities of Type 1 error should be given a higher priority only if the scientific hypothesis under scrutiny implies that all null hypotheses of the tests of significance are valid. More often, however, the research hypothesis is supported completely if all alternative hypotheses are accepted. In this case, a high power for each single test is more important than a low significance level.

Phosphate retention in some tropical soils in relation to soil taxonomic classes

Abstract Phosphate sorption values were correlated with other properties, the most ‐important factor relared to P retention seem to be extractable aluminium, free iron oxides also play a significant role in the process of sorption. Clay content affects P‐sorption but only at low level of significance. When adsorption was studied in relation to soil classes, it was found that there is a great variability in oxisols, and within them the oxisol with har‐dened laterite presented the lowest sorbing power. All the ultisols studied had low P‐retention. The ver‐tisols presented moderate to high P‐retention charac‐teristics. In general the entisols present the lowest P‐sorption in tropical soils. Only two alfisols (with a low capacity to sorb phosphate) were included making any comparison difficult. The only inceptisol examined showed high P‐sorption capacity

The characterization of radioaerosol deposition in the healthy lung by histogram distribution analysis.

Thirteen healthy nonsmoking volunteers inhaled an 8.1 micrometers (MMAD) radioaerosol on two occasions. Aerosol deposition pattern within the right lung, as recorded by a gamma camera, was expressed as the 3rd and 4th moments of the distribution histogram (skew and kurtosis) of radioactivity during the first ten minutes after aerosol inhalation. Deposition pattern was also expressed as the percentage of deposited activity retained within the lung at 24 hr (24 hr % retention) and found to be significantly correlated with measures of skew (P less than 0.001). Tests of pulmonary function (FEV1, FVC, and MMFR) were significantly correlated with skew. Correlations were also demonstrated for these pulmonary function tests with 24 hr % retention but at lower levels of significance. Results indicate that changes in measures of forced expiratory airflow in healthy human volunteers influence deposition pattern and that the skew of the distribution of inhaled radioactivity may provide an acceptable index of deposition pattern.

Quandtitative correlation among DNA damaging potency of six N-nitroso compounds and their potency in inducing tumor growth an bacterial mutations.

Six N-nitroso compounds (N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodi-n-propylamine, N-nitroso-N-methylurea, N-nitrosopyrrolidine, and N-nitrosodi-n-butylamine) were tested in rats for liver DNA damaging activity by the alkaline elution technique. On molar basis their DNA damaging potency was found to decrease in the above order, and to vary over a 28-fold range. The elaboration of homogenous data available from literature showed that the carcinogenic potency of the 6 N-nitroso compounds varied over an 18-fold range, and that their mutagenic potency varied over a 490-fold range. Regression analysis indicated that correlation between carcinogenic and DNA damaging potencies was positive but at a low significance level, while the correlation between carcinogenic and mutagenic potencies was negative.

Collusion and the Pattern of Rates of Return

This paper considers methods of separating firms and industries into collusive and competitive subsets, and the differences in patterns of rates of returns which are to be expected among these groups. The approach adopted here is quite distinct, both in structure and in policy implications, from the customary technique of estimating a linear relation between concentration and profitability or margins, which is then used to indicate a level of concentration associated with an excessive exercise of monopoly power.' Elsewhere [6] I have indicated that the low levels of significance which typify estimates of the concentration-profits relationship, their observed nonlinearity, and the heteroskedasticity commonly visible in residuals computed from such estimates all indicate that concentration, while an important determinant of the feasibility of collusion, is far from the only factor conditioning its success. As an alternative this paper outlines a proposed classification scheme for the identification of collusion which is based on price-cost margins in U.S. manufacturing for 1967. Margin data derived from Census industry tabulations are corrected for a variety of inter-industry influences compatible with competition. Following these corrections, the distribution of residuals at high concentration levels is shown to exhibit both positive skewness and more dispersion than is observed for low concentration industries, suggesting the presence of contamination by monopoly elements. The residual distribution is separated into competitive and monopoly components with large positive outliers being regarded as monopolized. One important result of applying this technique to U.S. data is a finding that many high-concentration industries appear to achieve only competitive margins. This result indicates that across-theboard deconcentration would involve restructuring a number of competitive industries. This classification scheme is outlined in more detail in Section II. The second stage of the process of identifying collusive industries involves presentation