Simplified formulas for three-way chi-square testing

In order to test against contingency in a 3-way table, simplified X²-formulas are given for (1) the general r xcxl-table, (2) for the rxcx2-table, (3) for the 2x2xl-table, and (4) for the 2×2×2-table. The tests are valid only if a sample of N individuals is observed as to 3 discrete or discretisized (dichotomized) variables which are, under H₀, assumed to be totally independent.     

Multiple Comparisons of Polynomial Distributions

Asymptotically correct 90 and 95 percentage points are given for multiple comparisons with control and for all pair comparisons of several independent samples of equal size from polynomial distributions. Test statistics are the maxima of the X²-statistics for single comparisons. For only two categories the asymptotic distributions of these test statistics result from DUNNETT'S many-one tests and TUKEY'S range test (cf. MILLER, 1981). The percentage points for comparisons with control are computed from the limit distribution of the test statistic under the overall hypothesis H₀. To some extent the applicability of these bounds is investigated by simulation. The bounds can also be used to improve Holm's sequentially rejective Bonferroni test procedure (cf. HOLM, 1979). The percentage points for all pair comparisons are obtained by large simulations. Especially for 3×3-tables the limit distribution of the test statistic under H₀ is derived also for samples of unequal size. Also these bounds can improve the corresponding Bonferroni-Holm procedure. Finally from SKIDÁK's probability inequality for normal random vectors (cf. SKIDÁK, 1967) a similar inequality is derived for dependent X²-variables applicable to simultaneous X²-tests.     

黄土丘陵区优势造林树种水分来源对季节性干旱的响应

黄土丘陵区处于季节性干旱生态脆弱地带,探明水分环境变化对区域优势造林树种水分来源的影响,对干旱区植物水分利用及其共生关系具有重要意义。以该地区广泛种植的沙棘(Hippophae rhamnoides)+油松(Pinus tabuliformis)、沙棘(H.rhamnoides)+刺槐(Robinia pseudoacacia)混交林(H_rP_t,H_rR_p)及沙棘(H_r)、油松(P_t)和刺槐(R_p)纯林为对象,测定其茎秆水、土壤水和降水稳定同位素组成,采用IsoSource模型量化水分来源,相似性比例指数(PS)定量分析共生植物间水分利用关系。结果表明：(1)旱季,同一树种纯林和混交林间吸水层位存在差异,纯林中主要利用0—100 cm土层土壤水,其中H_r和R_p对40—100 cm的利用率为46.8%和43.8%,P_t对0—40 cm为83.9%;混交林中则更倾向于利用40...     

A Comparison of Tests for Marginal Homogeneity in Square Contingency Tables

Several asymptotic tests were proposed for testing the null hypothesis of marginal homogeneity in square contingency tables with r categories. A simulation study was performed for comparing the power of four finite conservative conditional test procedures and of two asymptotic tests for twelve different contingency schemes for small sample sizes. While an asymptotic test proposed by STUART (1955) showed a rather satisfactory behaviour for moderate sample sizes, an asymptotic test proposed by BHAPKAR (1966) was quite anticonservative. With no a priori information the performance of (r - 1) simultaneous conditional binomial tests with a Bonferroni adjustment proved to be a quite efficient procedure. With assumptions about where to expect the deviations from the null hypothesis, other procedures favouring the larger or smaller conditional sample sizes, respectively, can have a great efficiency. The procedures are illustrated by means of a numerical example from clinical psychology.     

Rank Tests for Complete Block Designs

In this article a general univariate K-sample rank test for complete block designs with proportional cell frequencies is derived. It is shown that the test statistic has under H₀ and for arbitrary scores asymptotically a X²-distribution with K — 1 degrees of freedom. Special cases of this test are the Kruskal-Wallis test and the Friedman test. The test is compared with the Benard-van-Elteren test, the Mack-Skillings test and a test proposed by Downton. Finally the application of the test is illustrated by two examples.     

Unconditional Non-Asymptotic One-Sided Tests for Independent Binomial Proportions When the Interest Lies in Showing Non-Inferiority and/or Superiority

For two independent binomial proportions Barnard (1947) has introduced a method to construct a non-asymptotic unconditional test by maximisation of the probabilities over the ‘classical’ null hypothesis H₀= {(θ₁, θ₂) ∈ [0, 1]²: θ₁ = θ₂}. It is shown that this method is also useful when studying test problems for different null hypotheses such as, for example, shifted null hypotheses of the form H₀ = {(θ₁, θ₂) ∈ [0, 1]²: θ₂ ≤ θ₁ ± Δ } for non-inferiority and 1-sided superiority problems (including the classical null hypothesis with a 1-sided alternative hypothesis). We will derive some results for the more general ‘shifted’ null hypotheses of the form H₀ = {(θ₁, θ₂) ∈ [0, 1]²: θ₂ ≤ g(θ₁ )} where g is a non decreasing curvilinear function of θ₁. Two examples for such null hypotheses in the regulatory setting are given. It is shown that the usual asymptotic approximations by the normal distribution may be quite unreliable. Non-asymptotic unconditional tests (and the corresponding p-values) may, therefore, be an alternative, particularly because the effort to compute non-asymptotic unconditional p-values for such more complex situations does not increase as compared to the classical situation. For ‘classical’ null hypotheses it is known that the number of possible p-values derived by the unconditional method is very large, albeit finite, and the same is true for the null hypotheses studied in this paper. In most of the situations investigated it becomes obvious that Barnard's CSM test (1947) when adapted to the respective null space is again a very powerful test. A theorem is provided which in addition to allowing fast algorithms to compute unconditional non-asymptotical p-values fills a methodological gap in the calculation of exact unconditional p-values as it is implemented, for example, in Stat Xact 3 for Windows (1995).     

Molecular modeling and QSAR studies of a set of indole and benzimidazole derivatives as H<Subscript>4</Subscript> receptor antagonists

Histamine is an important biogenic amine, which acts with a group of four G-protein coupled receptors (GPCRs), namely H₁ to H₄ (H₁R – H₄R) receptors. The actions of histamine at H₄R are related to immunological and inflammatory processes, particularly in pathophysiology of asthma, and H₄R ligands having antagonistic properties could be helpful as antiinflammatory agents. In this work, molecular modeling and QSAR studies of a set of 30 compounds, indole and benzimidazole derivatives, as H₄R antagonists were performed. The QSAR models were built and optimized using a genetic algorithm function and partial least squares regression (WOLF 5.5 program). The best QSAR model constructed with training set (N = 25) presented the following statistical measures: r ² = 0.76, q ² = 0.62, LOF = 0.15, and LSE = 0.07, and was validated using the LNO and y-randomization techniques. Four of five compounds of test set were well predicted by the selected QSAR model, which presented an external prediction power of 80%. These findings can be quite useful to aid the designing of new anti-H₄ compounds with improved biological response.     

Evaluation of physical fitness from field tests at high altitude in circumpubertal boys: comparison with laboratory data

Field tests of running and laboratory tests were performed in La Paz [high altitude (HA), 3700 m] and in Clermont-Ferrand [low altitude (LA), 300 m] to investigate their validity at HA. Prepubertal boys of mean ages 10.6 years (HA1,n = 16; LA1,n = 28) and pubertal boys of 13.7 years (HA2,n = 12; LA2,n = 41) took part in the study. All the boys performed a 30-m sprint (v _30m), a 30-s shuttle run (v _3os) and a progressive shuttle run test until their maximal aerobic velocity (v _maxsRT). Maximal oxygen consumption was extrapolated from the last test. . In the laboratory, the boys performed a force-velocity test (P _max), a Wingate test (P _Wing) and a graded test to measure maximal oxygen consumption ; direct method) on a cycle ergometer. At similar ages, there was no significant difference between HA and LA boys forv _30m andP _max. Thev _30s of HA boys was 3%–4% lower than those of LA boys (P<0.05); there was no significant difference forP _Wing. Significant relationships were observed at both altitudes betweenP _max (watts per kilogram) andv _30m (HA:r=0.76; LA:r=0.84) and betweenP _Wing andv _30s (HA:r=0.67; LA:r = 0.77); the slopes and the origins were the same at HA and LA. The ,v _maxSRT and were lower by 9%, 12% and 20%, respectively, at HA than at LA (P<0.05). However, the relationships between and (litres per minute) at HA (r=0.88) and at LA (r=0.93) were identical. In conclusion, chronic hypoxia did not modify performance in very short dash exercises. The influence of HA appeared when the exercise duration increased and, during a maximal shuttle run test, performance was reduced by 10% at HA. Moreover, it was possible to assessP _max,P _Wing and at HA as well as at LA from field tests.     

Identification and profiling of 3,5-dimethyl-isoxazole-4-carboxylic acid [2-methyl-4-((2S,3′S)-2-methyl-[1,3′]bipyrrolidinyl-1′-yl)phenyl] amide as histamine H3 receptor antagonist for the treatment of depression

Lead optimization guided by histamine H₃ receptor (H₃R) affinity and calculated physico-chemical properties enabled simultaneous improvement in potency and PK properties leading to the identification of a potent, selective, devoid of hERG issues, orally bioavailable, and CNS penetrable H₃R antagonist/inverse agonist 3h. The compound was active in forced-swimming tests suggesting its potential therapeutic utility as an anti-depressive agent. This Letter further includes its cardiovascular and neuropsychological/behavioral safety assessments.     

Stabilization of collagen structure: Dependence of collagen denaturation enthalpy on the imino acid content

An analysis of the available data on the enthalpy (ΔH_r) of denaturation (melting) of collagens with different imino acid content in solution and in the aggregated state has shown that ΔH_r in solution increases with increasing denaturation temperature, whereas in the aggregated state there is an inverse dependence. ΔH_r in solution correlates with the hydroxyproline content but not with that of proline. No correlation between the change of ΔH_r and the imino acid content is observed for the aggregated state.     

Correlation between chlorophyll fluorescence and photoacoustic signal transients in spinach leaves

Chlorophyll fluorescence and photoacoustic transients from dark adapted spinach leaves were measured and analyzed using the saturating pulse technique. Except for the first 30 s of photosynthetic induction, a good correlation was found between photoacoustically detected oxygen evolution at 35 Hz modulation frequency and electron flow calculated from the fluorescence quenching coefficients q_P and q_N. The induction kinetics of the photothermal signal, i.e., the photoacoustic signal at 370 Hz, reveal a fast (t _r <10 ms) and a slow (t _r 1 s) rise component. The fast component is suggested to be composed of the minimal thermal losses in photosynthesis and thermal losses from non-photosynthetic processes. The slow phase is attributed to variable thermal losses in photosynthesis. The variable thermal losses were normalized by measuring the minimal photothermal signal (H₀) in the dark-adapted state and the maximal photothermal signal (H_m) during a saturating light pulse. The kinetics of the normalized photochemical loss (H-H₀)/(H_m-H₀) obtained from high-frequency PA measurements were found to correlate with the kinetics of oxygen evolution measured at low frequency.Abbreviations F_m maximum fluorescence - F₀ initial fluorescence - F_v variable fluorescence - H photothermal signal - I in-phase - LED light emitting diode - PA photoacoustic - PL photochemical loss - Q quadrature - q_N non-photochemical quenching - q_P photochemical quenching - VCLS voltage controlled light source     

Modulation of glyceraldehyde-3-phosphate dehydrogenase inAnacystis nidulans by glutathione

Glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13; GAPDH) from the cyanobacteriumAnacystis nidulans was activated up to five-fold by reduced glutathione (GSH) in the physiological concentration range (0.1–2 mM GSH). Non-physiological reductants, like dithiothreitol (DTT) and -mercaptoethanol, also activated the enzyme. Oxidized glutathione (GSSG) had no effect on the cyanobacterial GAPDH but treatment with H₂O₂ led to a rapid, reversible deactivation of both untreated and GSH-treated enzyme preparations. GSH reversed the inhibition induced by H₂O₂. An oligomeric form of the enzyme (apparentM _r440,000) was dissociated by GSH into a lower-M _r, more active enzyme form (M _r200,000). The enzyme was shown to obey regular Michaelis-Menten kinetics. The activation of GAPDH by GSH was associated with a decrease inK _m and an increase inV _max values of the enzyme for 3-phosphoglycerate. GSH had virtually no effect on a GAPDH preparation isolated from corn chloroplasts and studied for comparison.Abbreviations GAPDH glyceraldehyde-3-phosphate dehydrogenase - GSH reduced glutathione - GSSG oxidized glutathione - DTT dithiothreitol     

Simultaneous Statistical Inference Concerning the Standardized Mortality Ratios (SMB) of Several Strata in an Epidemiologic Study

In the present paper, simultaneous prediction intervals are constructed for some mortality measures involving real data in a recent retrospective epidemiologic study of a cohort of man-made mineral fiber workers. The object is to compare a test population with a standard population in which the workers are exposed to several levels (say K) of a suspected carcinogen and the number of deaths in the K exposure groups are recorded. The SMR is chosen as a mortality measure for this comparison. If the total number of deaths d. in the entire study is known, the number of deaths in the various strata become dependent random variables. Using univariate statistical procedures to test the significance of the individual SMR's is inappropriate and may give misleading conclusions. The present paper shows how to test the simultaneous statistical significance of the SMR's of the K exposure groups, i.e., to test the simultaneous null hypothesis H_o : E(SMR₁) = E(SMR₂) =…E(SMR_k) = 100. If the null hypothesis H_o is rejected, it is shown how to identify the SMR (or the SMR's) which contributed to the rejection of H_o. The power function of such a test is also constructed for some simple and useful alternative hypotheses.     

Local and Regional vs. Global Contingency Testing

Contingency analysis of r × c-tables is systematized as follows: Global contingency testing based on the total chisquare under H₀ of independent row and column variables is least favorable to exhaustive interpretation. Local contingency testing based on chi-square components of the individual cells of an r × c-table and realized in Configural frequency analysis (KRAUTH and LIENERT, 1973) is more favourable to substantive interpretation. Compromising between global and local contingency testing leads to so-called generalized local and regional contingency testing. Every contingency testing (local, regional and naturally global) is including all N individuals of a sample supposed to have been drawn randomly from a defined population. Extension to 3-and t-dimensional contingency analysis is outlined, and biomedical applications are discussed.     

Hydrophobicity-Related Protein Contents and Surface Areas of Aerial Conidia are Useful Traits for Formulation Design of Fungal Biocontrol Agents

To clarify the potential use of hydrophobicity-related traits of aerial conidia in formulation design of fungal biocontrol agents, hydrophobicity rates (H _r) and surface areas (S _a) of aerial conidia were assessed with 48 strains of Beauveria bassiana, Isaria fumosorosea and Metarhizium spp. Inter- or intra-specific variation was large in H _r (59.7–92.2%) and S _a (7.9–25.3 μm² conidium⁻¹) measurements, which were significantly correlated (r ² = 0.55). Six isolates of the three fungi with distinguished H _r and S _a were further studied. Conidial wall proteins of these isolates were sequentially extracted with sodium dodecyl sulfate (SDS), formic acid (FA) and trifluoroacetic acid (TFA). Their H _r values were significantly correlated to the contents (P _c) of TFA-soluble, but FA-insoluble, proteins (2.7–44.8 μg per 10⁷ conidia; r ² = 0.79) and reduced drastically by the FA/TFA treatments, which eliminated the hydrophobin-based rodlet layers of conidial surfaces. However, the SDS treatments had no effect on either H _r or rodlet layers. The dispersancy of a tested emulsifier to oil formulations of the six isolates in water was adversely correlated to their H _r (r ² = 0.94). The results indicate that both P _c and S _a are inherent hydrophobicity-related traits and can be utilized to select fungal biocontrol candidates for improved formulation and application.     

The calculation and significance testing of genetic correlations across environments

Genetic correlations within a trait across environments (r_g) are important in the analysis of phenotypic plasticity. Not all methods are, however, equally reliable. An overview of all different methods for estimation of r_g with one generation data sets is given. Formulae for the relationship between causal variance components and family means are derived. When these formulae are used covariances derived from family means, thought to be incorrect, are exactly the same as those derived with the ANOVA method. The bias, precision and power of the different methods are compared with Monte Carlo simulations. For all methods bias is small and precision is high for the large balanced data sets analyzed here, except when the variance in one or both of the environments is close to 0. Significance testing causes more problems. Confidence intervals with or without z-transformation are not suitable for testing, nor is testing for g*e interaction in an ANOVA suitable for testing whether the r_g is different from 1. The F-test in a mixed model ANOVA and a likelihood ratio test in a REML-analysis can be used for testing a difference from 0 but not from 1 or other values. Jackknife and Bootstrap, however, are suitable tests both for differences with 0,1 and other values, though negative variances can make these tests difficult to apply.     

Estimated genetic parameters for growth‐related traits in large yellow croaker Larimichthys crocea using microsatellites to assign parentage

To estimate the heritabilities of growth‐related traits in large yellow croaker, Larimichthys crocea, three independent full‐factorial crosses were created by crossing four males × four females, seven males × three females and four males × three females (set 1, set 2 and set 3). At 13 months post‐hatch, the juveniles were collected from three cross sets and measured for body mass (M), standard length (L_S) and body height (H_B). In addition, the parentage of the juveniles was assigned by genotyping six or seven polymorphic microsatellite loci. Out of the 959 juveniles, 99·6% could be assigned to a single parental pair. Heritabilities of growth‐related traits were estimated for individual and combined sets with the pedigrees reconstructed by using microsatellite genotypes. The heritability estimates at 13 month‐old were 0·02–0·30 for M, 0·02–0·25 for L_S and 0·03–0·36 for H_B. These results showed that the heritabilities of M, L_S and H_B were different among three sets, which suggested that different breeding strategies should be adopted for different sets.     

Dielectric relaxation of DNA solutions. III. Effects of DNA concentration, protein contamination, and mixed solvents

As a continuation of previous papers [Biopolymers (1976) 15 , 879; (1978) 17 , 1508], the low-frequency dielectric relaxation of DNA solutions was studied with a four-electrode cell and the simultaneous two-frequency measurement. Below a critical concentration, the dielectric relaxation time agrees with the rotational relaxation time estimated from the reduced viscosity and is almost independent of DNA concentration C_p, and the dielectric increment is proportional to C_p. The critical concentration is approximately 0.02% of DNA for molecular weight M_r 2 × 10⁶ and 0.2% for M_r 4.5 × 10⁵ in 1 mM NaCl. Dielectric relaxations are compared for samples before and after deproteinization, and the protein contamination is found to have a minor effect on the dipole moment of DNA. The effect of a mixed solvent of water and ethanol on the dielectric relaxation of DNA is well interpreted in terms of changes in viscosity and the dielectric constant of the solvent, assuming that the relaxation arises from rotation of the molecule with a quasi-permanent dipole due to counterion fluctuation.     

Genic Variation in Male Haploids under Deterministic Selection

Genic variation in male haploids and male diploids was compared assuming constant fitnesses (derived from computer-generated random numbers) and infinite population size. Several models were studied, differing by the fitness correlation between the sexes (r_s) and genotypes (r_g), and by the intensity of selection as measured by the coefficient of variation (CV) of the fitness distribution. Genic variation was quantified using the proportion of polymorphic loci, P, the gene diversity at polymorphic loci, H_p, and the gene diversity over all loci, H_a. The two genetic systems were compared via variation ratios: variation in male haploidy/variation in male diploidy.—P and H_a were markedly lower for male-haploids than for male diploids, the variation ratios declining with increasing r_s, r_g and CV, but the two genetic systems were similar for H_p. Except for male diploids with r_s = 1, the two sexes had different equilibrium gene frequencies but the sample sizes required to detect such differences reliably were larger than usually possible in surveys of natural populations.—Data from natural populations fit the above trends qualitatively, but the variation ratios are much lower than those from our analyses, except that for H_p, which is higher when Drosophila is excluded. Also, the frequency distribution of most common alleles from electrophoretic data has a deficiency of intermediate frequencies compared to that from the computer-generated sets of fitnesses, possibly reflecting either the influence of stochastic processes shifting frequencies away from equilibrium or the involvement of alleles under selection-mutation balance.——While electrophoretic data suggest that Drosophila has unusually high levels of genic variation, unusually low levels of genic variation in male haploids compared with male diploids are not strongly indicated. However, if further data confirm male haploids as having low levels of genic variation, likely explanations are that the bulk of electrophoretically detected variation involves fixed-fitness balancing selection, selection-mutation balance involving slightly deleterious recessive alleles, new favorable male haploid alleles moving more rapidly to fixation than under male diploidy and thus carrying linked loci to fixation faster, or some combination of these possible factors.     

Effects of mine acid on the longevity and reproductive rate of the gastrotricha Lepidodermella squammata (Dujardin)

Effects of mine acid on longevity and reproductive rate of the parthenogenic gastrotrich Lepidodermella squammata were studied under laboratory culture conditions. Water from unpolluted and polluted streams was used, directly or mixed, to establish a series of test conditions at pH 8.1, 7.1, 6.4, 5.2, 4.6 and 3.3. Eggs, cultured individually under each test condition, were observed at 12 h intervals for hatching, daughter egg laying and death. Data representing 50 animals under each test condition were used in the construction of a series of life tables. From these were calculated maximal life expectancy (e_x), net reproductive rate per individual lifetime (R_o) and intrinsic rate of natural increase (r_max).Values of e_x, R_o and r_max were maximal at pH 7.1 and were reduced slightly at the higher pH; e_x was greatly reduced and R_o zero at pH 6.4 and 5.2; and e_x was zero at pH 4.6 and 3.3. Analysis of variance tests indicate significant differences between e_x values of L. squammata cultured at pH 8.1 and those cultured at pH 7.1, but no differences between R_o or r_max.Associated with the decrease in pH was an increase in total conductivity and a decrease in carbonate alkalinity and hence in carbonate conductivity. It appears that L. squammata is capable of living and reproducing at pH 6.0 to 6.5 under field conditions low in carbonates, providing non-carbonate ions are not abundant, or under field conditions high in non-carbonate ions, providing sufficient carbonates are present.