442 research outputs found

    Molecular and morphological evolution of the amphipod radiation of Lake Baikal

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    The amphipods of Lake Baikal, Russia, are a taxonomically and morphologically diverse group, and have been cited as a classic example of adaptive radiation. An unfortunate consequence of this diversity has been an instability of Baikal amphipod classification, with frequent revisions spurred by differing opinions about the phylogenetic utility of different characters. Classifications have never been based on a rigorous phylogenetic analysis of morphological data and only recently has the phylogeny of Lake Baikal\u27s amphipods been examined using molecular tools. Unfortunately, most of these studies have led to a limited expansion of our understanding of Baikal amphipod systematics. Phylogenetic relationships of selected amphipod species from Lake Baikal were constructed using molecular data from portions of two mitochondrial genes, 16S rDNA and COI, and 121 morphological characters. Additionally, patterns of morphological change and the phylogenetic utility of different characters were examined by tracing the 121 morphological characters upon the most parsimonious 16S phylogeny. While the molecular datasets resulted in similar topologies, the morphological data were not congruent with either molecular dataset. A combined molecular/morphological analysis resulted in a topology that was not very different than the combined molecular phylogeny. When plotted on the most parsimonious 16S tree, the morphological data was very homoplastic, although the level of homoplasy differed among types of morphological characters. Contrary to recent popular opinion, body armour and processes characters were the least homoplastic of all types, while characters that have been considered phylogenetically useful, such as mouthpart characters, were the most homoplastic. The molecular phylogenies obtained in this study lead to a better understanding of the phylogenetic history of Baikal\u27s amphipods. The large, morphologically diverse family Acanthogammaridae is strongly supported as a monophyletic group, and likely to have radiated from a single ancestral species within the lake. Conversely, the fossorial, morphologically uniform family Micruropodidae seem to be composed of two relatively unrelated groups, one of which is closely related to the monotypic Macrohectopidae, the lake\u27s morphologically highly modified pelagic planktivore, suggesting a disjunction between morphological and molecular evolution. Finally, this study suggests that the amphipod fauna of Lake Baikal is not monophyletic; the cosmopolitan Gammarus lacustris may share recent common ancestry with some Baikal taxa

    Survival Rates of Teeth with Primary Endodontic Treatment after Core/Post and Crown Placement

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    Introduction The objective of this study was to determine the effect of delayed placement of the core/post and crown on the outcomes of nonsurgical root canal therapy (NSRCT). Methods According to the Delta Dental of Wisconsin claims database, 160,040 NSRCTs were completed with a core/post and a crown placed before the end of the continuous coverage period or occurrence of an untoward event. Untoward events were defined as a retreatment, apicoectomy, or extraction as defined by the Code on Dental Procedures and Nomenclature. Statistical analysis was performed by using a multivariable Cox proportional hazards model. Results The survival rate from the time of crown placement to an untoward event was 99.1% at 1 year, 96.0% at 3 years, 92.3% at 5 years, and 83.8% at 10 years. Failure rates were greater when a core/post was placed more than 60 days after the NSRCT (adjusted hazard ratio, 1.08) and when the crown was placed more than 60 days after the core/post placement (adjusted hazard ratio, 1.14). Overall, the survival rates of NSRCT were greater when performed by an endodontist versus other providers. Conclusions On the basis of the information available from insurance claims data, this study shows that the long-term survival rates of initial endodontic therapy are adversely affected by the delayed placement of the final restoration and full coverage crown

    Biodiversity, host specificity, and dominance by eusocial species among sponge-dwelling alpheid shrimp on the Belize Barrier Reef

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    Alpheid shrimp represent an abundant and diverse, but poorly characterized, component of the cryptic biodiversity of coral reefs worldwide. Sponge-inhabiting alpheids provide a promising model system for exploring patterns of cryptic reef biodiversity because their habitats (hosts) are discrete and qualitatively distinct units. We tabulated data from 14 years of collections at Carrie Bow Cay, Belize to quantify patterns of diversity, host specificity, and dominance among sponge-dwelling shrimp (Synalpheus), with special attention to eusocial species. From \u3e 600 sampled sponges of 17 species, we recognized at least 36 Synalpheus shrimp species. Of these, 15 (42%) were new to science. Species accumulation curves suggest that we have sampled most of the Synalpheus diversity at Carrie Bow Cay. Diversity of sponge-dwelling Synalpheus was slightly higher in shallow water, probably because of greater habitat diversity, than in deep water. Host specificity was surprisingly high, with \u3e 50% of all shrimp species found in only a single sponge species each, although some shrimp species used as many as six hosts. Cohabitation of individual sponges by multiple shrimp species was rarer than expected by chance, supporting previous distributional and behavioural evidence that competition for hosts is strong and moulds patterns of host association. The fauna of most well-sampled sponge species was dominated, both in numbers of individuals and in frequency of occurrence, by eusocial species. Eusocial shrimp species also inhabited a significantly greater number of sponge species than did non-social shrimp. Consequently, \u3e 65% of shrimp in our quantitative samples belonged to the four eusocial species, and on a per-species basis, eusocial species were 17 times as abundant as non-social species. Our data suggest that the highly diverse sponge-dwelling shrimp assemblage of the Belize Barrier Reef is structured by competition, and that eusociality has allowed a small number of species to dominate the sponge resource

    Decline and Local Extinction of Caribbean Eusocial Shrimp

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    The tropical shrimp genus Synalpheus includes the only eusocial marine animals. In much of the Caribbean, eusocial species have dominated the diverse fauna of sponge-dwelling shrimp in coral rubble for at least the past two decades. Here we document a recent, dramatic decline and apparent local extinction of eusocial shrimp species on the Belize Barrier Reef. Our collections from shallow reefs in central Belize in 2012 failed to locate three of the four eusocial species formerly abundant in the area, and showed steep declines in colony size and increases in frequency of queenless colonies prior to their disappearance. Concordant with these declines, several nonsocial, pair-forming Synalpheus species increased in frequency. The decline in eusocial shrimp is explained in part by disappearance of two sponge species on which they specialize. Eusocial shrimp collections from Jamaica in 2012 showed similar patterns of decline in colony size and increased queenlessness compared with prior Jamaican collections. The decline and local extinction of eusocial shrimp happened against a backdrop of changes in coral assemblages during recent decades, and may reflect changes in abundance and quality of dead coral substratum and succession of the diverse cryptic organisms living within it. These changes document potentially worrisome declines in a unique taxon of eusocial marine animals

    Sexual Responsivity and the Effects of Negative Mood on Sexual Arousal in Hypersexual Men Who Have Sex with Men (MSM)

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    This article has been accepted for publication in The Journal of Sexual Medicine Published by Oxford University Press.Background A number of studies have found that hypersexuality is associated with a high propensity for sexual excitation. In comparison, less is known about the relationship between hypersexuality and sexual arousal at the state level. Also, previous research has revealed a relationship between hypersexuality and negative mood. However, the possibility that sexual response might not be as negatively impacted by negative mood in hypersexual individuals has, as yet, not been tested. Aim The purpose of this study was to investigate sexual responsivity and the effects of negative mood on sexual arousal in hypersexual men who have sex with men (MSM). Methods A total of 211 MSM were assigned to a hypersexuality (N = 81) or a control (N = 130) group using an interview patterned with a semi-structured Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders format. Participants filled out questionnaires and were shown neutral, sexual, and anxiety- and sadness-inducing films. Outcomes Changes in penile circumference and self-reported sexual arousal were the primary outcomes analyzed in this study. Results Controlling for age and HIV status, no differences were found in genital response between hypersexual and non-hypersexual men. Also, the 2 groups did not differ in subjective sexual arousal. Moreover, no effects of negative mood were found. Time series clustering analyses revealed 3 groups—low responders and slow and fast high responders. Sexual excitation, but not sexual compulsivity or pornography use, predicted cluster membership. Clinical Translation Hypersexual MSM may benefit more from an exploration of motivational and behavioral, as compared to psychophysiological, mechanisms underlying possible links between (negative) mood and sexual behavior. Strengths & Limitations Strengths of the study include its sample size, making it one of the larger psychophysiological sex studies; the use of clinical interviews for group assignment; the inclusion of genital response measures; and the application of time series clustering to examine differences among participants. Limitations include possible sample heterogeneity and the reliance on researcher-selected stimuli. Conclusion Given the lack of any effects of negative mood on sexual response in hypersexual MSM, future studies could explore in more depth possible motivational and behavioral effects, including, for example, the impact of negative mood on the tendency to seek out sex as a form of distraction or for validation or emotional support

    Effects of sorghum wet distillers grains plus solubles in steam-flaked corn–based finishing diets on steer performance, carcass characteristics, and digestibility characteristics

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    Two studies were conducted to evaluate the effects of sorghum wet distillers grains (SWDGS) in finishing diets on steer performance, carcass characteristics, and nutrient digestibility. In Exp. 1, 240 steers (initial BW = 379 ± 1 kg) were fed steam-flaked corn–based diets with or without 25% SWDGS and 7.5, 10.0, or 12.5% alfalfa hay. There were no effects of alfalfa hay concentration on BW, DMI, ADG, or G:F (P ≥ 0.16). Including SWDGS reduced (P ≤ 0.05) ADG and G:F. Fat thickness decreased (P = 0.03) and DP tended to decrease (P = 0.09) linearly as level of alfalfa hay increased. Final BW of steers consuming diets containing 25% SWDGS were 12 kg lighter (P = 0.05) than those of steers fed diets without SWDGS. Hot carcass weight tended (P = 0.09) to be lighter for steers fed SWDGS. In Exp. 2, effects of corn processing method (steam-flaked corn and dry-rolled corn) and 20% corn wet distillers grains with solubles (CWDGS) or SWDGS inclusion on ruminal pH and in situ digestibility were evaluated. Cattle consuming diets containing SWDGS had a greater (P ≤ 0.05) ruminal pH than steers consuming diets with CWDGS or no wet distillers grains with solubles. Including wet distillers grains with solubles did not affect (P ≥ 0.37) steam-flaked corn or dry-rolled corn in situ DM digestibility. In situ digestibility of DM and NDF differed between CWDGS and SWDGS (P \u3c 0.0001). Differences in performance and nutrient digestibility between CWDGS and SWDGS are the result of differences in the product rather than an interaction with corn processing method

    Cognition in schizophrenia and schizo-affective disorder: Impairments that are more similar than different

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    BACKGROUND: Cognition is increasingly being recognized as an important aspect of psychotic disorders and a key contributor to functional outcome. In the past, comparative studies have been performed in schizophrenia and schizo-affective disorder with regard to cognitive performance, but the results have been mixed and the cognitive measures used have not always assessed the cognitive deficits found to be specific to psychosis. A set of optimized cognitive paradigms designed by the Cognitive Neuroscience Test Reliability and Clinical Applications for Schizophrenia (CNTRACS) Consortium to assess deficits specific to schizophrenia was used to measure cognition in a large group of individuals with schizophrenia and schizo-affective disorder. METHOD: A total of 519 participants (188 with schizophrenia, 63 with schizo-affective disorder and 268 controls) were administered three cognitive paradigms assessing the domains of goal maintenance in working memory, relational encoding and retrieval in episodic memory and visual integration. RESULTS: Across the three domains, the results showed no major quantitative differences between patient groups, with both groups uniformly performing worse than healthy subjects. CONCLUSIONS: The findings of this study suggests that, with regard to deficits in cognition, considered a major aspect of psychotic disorder, schizophrenia and schizo-affective disorder do not demonstrate major significant distinctions. These results have important implications for our understanding of the nosological structure of major psychopathology, providing evidence consistent with the hypothesis that there is no natural distinction between cognitive functioning in schizophrenia and schizo-affective disorder

    Communications Biophysics

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    COntains reports on six research projects.National Institutes of Health (Grant 2 P01 MH-04737-06)National Institutes of Health (Grant 5 ROl NB-05462-02)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 36-039-AMC-03200(E)National Science Foundation (Grant GK-835)National Aeronautics and Space Administration (Grant NsG-496
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