Brain morphology of the threespine stickleback (Gasterosteus aculeatus) varies inconsistently with respect to habitat complexity: A test of the Clever Foraging Hypothesis

The Clever Foraging Hypothesis asserts that organisms living in a more spatially complex environment will have a greater neurological capacity for cognitive processes related to spatial memory, navigation, and foraging. Because the telencephalon is often associated with spatial memory and navigation tasks, this hypothesis predicts a positive association between telencephalon size and environmental complexity. The association between habitat complexity and brain size has been supported by comparative studies across multiple species but has not been widely studied at the within‐species level. We tested for covariation between environmental complexity and neuroanatomy of threespine stickleback (Gasterosteus aculeatus ) collected from 15 pairs of lakes and their parapatric streams on Vancouver Island. In most pairs, neuroanatomy differed between the adjoining lake and stream populations. However, the magnitude and direction of this difference were inconsistent between watersheds and did not covary strongly with measures of within‐site environmental heterogeneity. Overall, we find weak support for the Clever Foraging Hypothesis in our study.     

Utility of Hantzsch reaction for development of highly sensitive spectrofluorimetric method for determination of alfuzosin and terazosin in bulk,dosage forms and human plasma

A highly sensitive, cheap, simple and accurate spectrofluorimetric method has been developed and validated for the determination of alfuzosin hydrochloride and terazosin hydrochloride in their pharmaceutical dosage forms and in human plasma. The developed method is based on the reaction of the primary amine moiety in the studied drugs with acetylacetone and formaldehyde according to the Hantzsch reaction, producing yellow fluorescent products that can be measured spectrofluorimetrically at 480 nm after excitation at 415 nm. Different experimental parameters affecting the development and stability of the reaction products were carefully studied and optimized. The fluorescence–concentration plots of alfuzosin and terazosin were rectilinear over a concentration range of 70–900 ng ml^?1, with quantitation limits 27.1 and 32.2 ng ml^?1 for alfuzosin and terazosin, respectively. The proposed method was validated according to ICH guidelines and successfully applied to the analysis of the investigated drugs in dosage forms, content uniformity test and spiked human plasma with high accuracy.     

Experimental demonstration of the insurance value of extra eggs in an obligately siblicidal seabird

A variety of organisms regularly produce more offspring thanthey raise. Despite the apparent energetic waste of such areproductive tactic, overproduction may be favored by naturalselection in some cases. One such case is when surplus offspringcan serve as replacements, or insurance, for failed siblings.We tested the Insurance Egg Hypothesis (IEH) as an explanationfor the overproduction of offspring in an obligately siblicidal seabird, the Nazca booby (Sula grant)i, which fledges a maximumof one nestling regardless of its clutch size. We manipulatedclutch sizes within the range of natural variation encounteredin this species (one-two eggs). The IEH predicts that parentswith two-egg clutches should have higher reproductive successthan those with one-egg clutches because the second egg canprovide a nestling when the first egg fails to hatch, or when the first chick dies young. Consistent with the IEH, naturalone-egg clutches that were enlarged to two eggs produced morehatchlings and fledglings than control one-egg clutches did,and natural two-egg clutches that were reduced to one egg producedfewer hatchlings and fledglings than control two-egg clutchesdid. We also evaluated aspects of the Individual Optimization Hypothesis, which proposes that individual optimal clutch sizesdiffer, as an explanation for clutch size variation in thisspecies. In Nazca boobies, selection driven by replacementvalue appears to favor clutches larger than one even thoughfinal brood size is invariably one. One-egg clutches may be produced by parents experiencing some proximate limitation,such as a lack of food.     

The role of bivalve molluscs as tools in estuarine sediment toxicity testing: a review

Estuarine sediments frequently are repositories and therefore potential sources of anthropogenic contaminants. Many organic and metallic chemical compounds released into aquatic systems bind to particulates and so accumulate in the sediments, thus, sediments become repositories of contaminants in estuaries. These may also cause contamination through diffusion of porewater, resuspension of particulates and dispersal of benthic fauna. There is a need to assess the biological affects of these anthropogenic contaminants because they may be toxic to infauna and bottomfish. Sediment toxicity bioassays are a means for carrying out such an assessment and primarily provide data on toxicity by measuring the effects on the test organism. Existing sediment toxicity bioassays rely on a battery of aquatic toxicity tests, which are based on the extraction of pore water, and elutriate from sediments and then subjecting these sediment phases to toxicity testing regimes. Two estuarine bivalve molluscs, Scrobicularia plana and Tapes semidecussatus were used to assess the ecotoxicity of field-collected sediments from estuarine and coastal areas around the Irish and English Coast over a 3-year study period. A variety of endpoints were measured during the study including survival in air, behaviour, animal condition, biochemistry, soft tissue metal concentrations, lysosomal membrane integrity and histopathology. Of these endpoints, the most sensitive were survival, survival in air, lysosomal membrane integrity, behaviour and histopathology.     

Technology and Affect: HIV/AIDS Testing in Brazil

Contemporary techno-scientific and medical developments are restructuring social interactions and the very processes by which individual subjectivity is formed. This essay elaborates on the experiential and ethical impact of such transformations from the perspective of people who, in ordinary and unexpected ways, act science and technology out. We carried out ethnographic research in an HIV/AIDS Testing and Counseling Center (CTA) in northeastern Brazil, combining participant observation with epidemiological analyses and clinical survey. We found a high demand for free testing by low-risk clients, largely working and middle class, experiencing anxiety and complaining of AIDS-like symptoms. Most of the clients were sero-negative and many returned for a second and third testing. We understand this to be a new techno-cultural phenomenon and call it imaginary AIDS. Throughout this essay, we describe CTA's routine practices, place these practices in historical, political, economic and cross-cultural perspective, and analyze the subjective data we collected from the clients of our pilot study. We explore how clinical epidemiological expertise and HIV testing technology are integrated into new forms of bio-politics aimed at specific marketable and disease-free populations, and on the affective absorption of bio-technical truth and the engendering of a technoneurosis in this testing center.     

Why the null matters: statistical tests,random walks and evolution

A number of statistical tests have been developed to determine what type of dynamics underlie observed changes in morphology in evolutionary time series, based on the pattern of change within the time series. The theory of the scaled maximum, the log-rate-interval (LRI) method, and the Hurst exponent all operate on the same principle of comparing the maximum change, or rate of change, in the observed dataset to the maximum change expected of a random walk. Less change in a dataset than expected of a random walk has been interpreted as indicating stabilizing selection, while more change implies directional selection. The runs test in contrast, operates on the sequencing of steps, rather than on excursion. Applications of these tests to computer generated, simulated time series of known dynamical form and various levels of additive noise indicate that there is a fundamental asymmetry in the rate of type II errors of the tests based on excursion: they are all highly sensitive to noise in models of directional selection that result in a linear trend within a time series, but are largely noise immune in the case of a simple model of stabilizing selection. Additionally, the LRI method has a lower sensitivity than originally claimed, due to the large range of LRI rates produced by random walks. Examination of the published results of these tests show that they have seldom produced a conclusion that an observed evolutionary time series was due to directional selection, a result which needs closer examination in light of the asymmetric response of these tests.     

Statistical decoding of potent pools based on chemical structure

Pooling experiments are used as a cost-effective approach for screening chemical compounds as part of the drug discovery process in pharmaceutical companies. When a biologically potent pool is found, the goal is to decode the pool, i.e., to determine which of the individual compounds are potent. We propose augmenting the data on pooled testing with information on the chemical structure of compounds in order to complete the decoding process. This proposal is based on the well-known relationship between biological potency of a compound and its chemical structure. Application to real data from a drug discovery process at GlaxoSmithKline reveals a 100% increase in hit rate, namely, the number of potent compounds identified divided by the number of tests required.     

Likelihood ratio tests for a mixture of two von Mises distributions

It is proposed that the orientation of elongate objects, such as bones, may be used to identify the flow direction of ancient river deposits. If true, elongate objects could be of great value when ancient bedforms such as ripples and dunes are not visible. Two sandstone quarries were investigated wherein the paleoflow direction was determined from both bedforms and elongate dinosaur bones. A mixture of two von Mises distributions captures the observation that elongate bones transported under unidirectional flow conditions will align both parallel and perpendicular to the flow direction. Likelihood ratio tests for a mixture of two von Mises distributions are given. The power of these tests is investigated by simulation since the direction of dinosaur bones agrees with the primary bedforms if the hypothesis test comparing the dominant mean direction of the bones to the paleoflow direction fails to reject. The likelihood ratio test on the dominant mean direction has reasonable power. If the two mean directions in the mixture distribution are pi apart, a more powerful likelihood ratio test can be used. The likelihood ratio test on the hypothesis that the two mean directions are exactly pi apart is useful in determining if the assumptions of the more powerful test are satisfied.     

Testing equality of survival functions of quality-adjusted lifetime

We present a method for comparing the survival functions of quality-adjusted lifetime from two treatments. This test statistic becomes the ordinary log-rank test when quality-adjusted lifetime is the same as the survival time. Simulation experiments are conducted to examine the behavior of our proposed test statistic under both null and alternative hypotheses. In addition, we apply our method to a breast cancer trial for comparing the distribution of quality-adjusted lifetime between two treatment regimes.     

Qualified testing of single-locus codominant inheritance using single tree progenies

In forest trees, classical techniques of studying modes of inheritance are usually not feasible due to the difficulty of performing controlled crosses. The limited information on inheritance extractable from readily available data, such as the large progenies collectable from single seed trees, must be compensated by the design of appropriately parameterized models. For this purpose, a system analytic approach is used to develop a new inferential framework for testing a single-locus codominant mode of inheritance of genetic traits using the inferred genotypes within progenies of single trees of inferred heterozygous genotype. Model assumptions are random gametic fusion between the local gamete pools and absence of postzygotic selection; ovule segregation distortion is allowed. The method yields estimates of the allele frequencies in both local gamete pools. Since tests of modes of inheritance must be tests of models rather than of parameters, the utility of the classical statistical testing procedures is limited, particularly concerning the qualification of a sampling method to attain a preassigned level of precision. Consistent application of this principle makes it possible to design qualified sampling methods prior to the actual experiment as well as to specify qualification levels for tests of completed experiments.