Fundamental dissipation due to bound fermions in the zero-temperature limit.

The ground state of a fermionic condensate is well protected against perturbations in the presence of an isotropic gap. Regions of gap suppression, surfaces and vortex cores which host Andreev-bound states, seemingly lift that strict protection. Here we show that in superfluid 3He the role of bound states is more subtle: when a macroscopic object moves in the superfluid at velocities exceeding the Landau critical velocity, little to no bulk pair breaking takes place, while the damping observed originates from the bound states covering the moving object. We identify two separate timescales that govern the bound state dynamics, one of them much longer than theoretically anticipated, and show that the bound states do not interact with bulk excitations.

Operating Nanobeams in a Quantum Fluid.

Microelectromechanical (MEMS) and nanoelectromechanical systems (NEMS) are ideal candidates for exploring quantum fluids, since they can be manufactured reproducibly, cover the frequency range from hundreds of kilohertz up to gigahertz and usually have very low power dissipation. Their small size offers the possibility of probing the superfluid on scales comparable to, and below, the coherence length. That said, there have been hitherto no successful measurements of NEMS resonators in the liquid phases of helium. Here we report the operation of doubly-clamped aluminium nanobeams in superfluid 4He at temperatures spanning the superfluid transition. The devices are shown to be very sensitive detectors of the superfluid density and the normal fluid damping. However, a further and very important outcome of this work is the knowledge that now we have demonstrated that these devices can be successfully operated in superfluid 4He, it is straightforward to apply them in superfluid 3He which can be routinely cooled to below 100 µK. This brings us into the regime where nanomechanical devices operating at a few MHz frequencies may enter their mechanical quantum ground state.

Sampling large geographic areas for rare species using environmental DNA: a study of bull trout Salvelinus confluentus occupancy in western Montana.

This study tested the efficacy of environmental DNA (eDNA) sampling to delineate the distribution of bull trout Salvelinus confluentus in headwater streams in western Montana, U.S.A. Surveys proved fast, reliable and sensitive: 124 samples were collected across five basins by a single crew in c. 8 days. Results were largely consistent with past electrofishing, but, in a basin where S. confluentus were known to be scarce, eDNA samples indicated that S. confluentus were more broadly distributed than previously thought.

High-precision genetic mapping of behavioral traits in the diversity outbred mouse population.

Historically our ability to identify genetic variants underlying complex behavioral traits in mice has been limited by low mapping resolution of conventional mouse crosses. The newly developed Diversity Outbred (DO) population promises to deliver improved resolution that will circumvent costly fine-mapping studies. The DO is derived from the same founder strains as the Collaborative Cross (CC), including three wild-derived strains. Thus the DO provides more allelic diversity and greater potential for discovery compared to crosses involving standard mouse strains. We have characterized 283 male and female DO mice using open-field, light-dark box, tail-suspension and visual-cliff avoidance tests to generate 38 behavioral measures. We identified several quantitative trait loci (QTL) for these traits with support intervals ranging from 1 to 3 Mb in size. These intervals contain relatively few genes (ranging from 5 to 96). For a majority of QTL, using the founder allelic effects together with whole genome sequence data, we could further narrow the positional candidates. Several QTL replicate previously published loci. Novel loci were also identified for anxiety- and activity-related traits. Half of the QTLs are associated with wild-derived alleles, confirming the value to behavioral genetics of added genetic diversity in the DO. In the presence of wild-alleles we sometimes observe behaviors that are qualitatively different from the expected response. Our results demonstrate that high-precision mapping of behavioral traits can be achieved with moderate numbers of DO animals, representing a significant advance in our ability to leverage the mouse as a tool for behavioral genetics.

Cost of healthcare for patients with migraine in five European countries: results from the International Burden of Migraine Study (IBMS).

Migraine is a disabling neurological disease that affects 14.7 % of Europeans. Studies evaluating the economic impact of migraine are complex to conduct adequately and with time become outdated as healthcare systems evolve. This study sought to quantify and compare direct medical costs of chronic migraine (CM) and episodic migraine (EM) in five European countries. Cross-sectional data collected via a web-based survey were screened for migraine and classified as CM (≥15 headache days/month) or EM (<15 headache days/month), and included sociodemographics, resource use data and medication use. Unit cost data, gathered using publicly available sources, were analyzed for each type of service, stratified by migraine status. Univariate and multivariate log-normal regression models were used to examine the relationship between various factors and their impact on total healthcare costs. This economic analysis included data from respondents with migraine in the UK, France, Germany, Italy, and Spain. CM participants had higher level of disability and more prevalent psychiatric disorders compared to EM. CM participants had more provider visits, emergency department/hospital visits, and diagnostic tests; the medical costs were three times higher for CM than EM. Per patient annual costs were highest in the UK and Spain and lower in France and Germany. CM was associated with higher medical resource use and total costs compared to EM in all study countries, suggesting that treatments that reduce headache frequency could decrease the clinical and economic burden of migraine in Europe. Comparing patterns of care and outcomes among countries may facilitate the development of more cost-effective care, and bring greater recognition to patients affected by migraine.

Disability, HRQoL and resource use among chronic and episodic migraineurs: results from the International Burden of Migraine Study (IBMS).

BACKGROUND: Migraine imposes significant burden on patients, their families and health care systems. In this study, we compared episodic to chronic migraine sufferers to determine if migraine status predicted headache-related disability, health-related quality of life (HRQoL) and health care resource utilization. METHODS: A Web-based survey was administered to panelists from nine countries. Participants were classified as having chronic migraine (CM), episodic migraine (EM) or neither using a validated questionnaire. Data collected and then analyzed included sociodemographics, clinical characteristics, Migraine Disability Assessment, Migraine-Specific Quality of Life v2.1, Patient Health Questionnaire and health care resource utilization. FINDINGS: Of the respondents, 5.7% had CM and 94.3% had EM, with CM patients reporting significantly more severe disability, lower HRQoL, higher levels of anxiety and depression and greater health care resource utilization compared to those with EM. INTERPRETATION: These results provide evidence that will enhance our understanding of the factors driving health care costs and will contribute to development of cost-effective health care strategies.

Convergence among cave catfishes: long-branch attraction and a Bayesian relative rates test.

Convergence has long been of interest to evolutionary biologists. Cave organisms appear to be ideal candidates for studying convergence in morphological, physiological, and developmental traits. Here we report apparent convergence in two cave-catfishes that were described on morphological grounds as congeners: Prietella phreatophila and Prietella lundbergi. We collected mitochondrial DNA sequence data from 10 species of catfishes, representing five of the seven genera in Ictaluridae, as well as seven species from a broad range of siluriform outgroups. Analysis of the sequence data under parsimony supports a monophyletic Prietella. However, both maximum-likelihood and Bayesian analyses support polyphyly of the genus, with P. lundbergi sister to Ictalurus and P. phreatophila sister to Ameiurus. The topological difference between parsimony and the other methods appears to result from long-branch attraction between the Prietella species. Similarly, the sequence data do not support several other relationships within Ictaluridae supported by morphology. We develop a new Bayesian method for examining variation in molecular rates of evolution across a phylogeny.

Evolution and divergence of sodium channel genes in vertebrates.

Invertebrate species possess one or two Na+ channel genes, yet there are 10 in mammals. When did this explosive growth come about during vertebrate evolution? All mammalian Na+ channel genes reside on four chromosomes. It has been suggested that this came about by multiple duplications of an ancestral chromosome with a single Na+ channel gene followed by tandem duplications of Na+ channel genes on some of these chromosomes. Because a large-scale expansion of the vertebrate genome likely occurred before the divergence of teleosts and tetrapods, we tested this hypothesis by cloning Na+ channel genes in a teleost fish. Using an approach designed to clone all of the Na+ channel genes in a genome, we found six Na+ channel genes. Phylogenetic comparisons show that each teleost gene is orthologous to a Na+ channel gene or gene cluster on a different mammalian chromosome, supporting the hypothesis that four Na+ channel genes were present in the ancestors of teleosts and tetrapods. Further duplications occurred independently in the teleost and tetrapod lineages, with a greater number of duplications in tetrapods. This pattern has implications for the evolution of function and specialization of Na+ channel genes in vertebrates. Sodium channel genes also are linked to homeobox (Hox) gene clusters in mammals. Using our phylogeny of Na+ channel genes to independently test between two models of Hox gene evolution, we support the hypothesis that Hox gene clusters evolved as (AB) (CD) rather than [D[A(BC)]].

Object individuation: infants' use of shape, size, pattern, and color.

Recent research indicates that when an event-monitoring paradigm is used, infants as young as 4.5 months of age demonstrate the ability to use featural information to individuate objects involved in occlusion events (Wilcox & Baillargeon, 1998a, Object individuation in infancy: The use of featural information in reasoning about occlusion events. Cognitive Psychology 37, 97-155; Wilcox & Baillargeon, 1998b, Object individuation in young infants: Further evidence with an event monitoring task. Developmental Science 1, 127-142). For example, in one experiment (Wilcox & Baillargeon, 1998b, Object individuation in young infants: Further evidence with an event monitoring task. Developmental Science 1, 127-142) 4.5-month-old infants saw a test event in which a green ball with colored dots disappeared behind one edge of a narrow or wide screen, and a red box with silver thumbtacks appeared at the other edge; the narrow screen was too narrow to hide both objects simultaneously, whereas the wide screen was sufficiently wide to hide both objects at the same time. The infants looked reliably longer at the narrow- than at the wide-screen test event. These and control results suggested that the infants had: (a) used the featural differences between the ball and box to conclude that two objects were involved in the event; (b) judged that both objects could fit simultaneously behind the wide but not the narrow screen; and hence (c) were surprised by the narrow-screen event. The present experiments build on these initial findings by investigating the features to which infants are most sensitive. Four experiments were conducted with infants 4.5-11.5 months of age using the same procedure, except that only one feature was manipulated at a time: shape, size, pattern, or color. The results indicated that 4.5-month-olds use both shape and size features to individuate objects involved in occlusion events. However, it is not until 7.5 months that infants use pattern, and 11.5 months that infants use color, to reason about object identity. It is suggested that these results reflect biases in the kind of information that infants attend to when reasoning about occlusion events. Possible sources of bias are discussed.

Two living species of coelacanths?

During the period of September 1997 through July 1998, two coelacanth fishes were captured off Manado Tua Island, Sulawesi, Indonesia. These specimens were caught almost 10,000 km from the only other known population of living coelacanths, Latimeria chalumnae, near the Comores. The Indonesian fish was described recently as a new species, Latimeria menadoensis, based on morphological differentiation and DNA sequence divergence in fragments of the cytochrome b and 12S rRNA genes. We have obtained the sequence of 4,823 bp of mitochondrial DNA from the same specimen, including the entire genes for cytochrome b, 12S rRNA, 16S rRNA, four tRNAs, and the control region. The sequence is 4.1% different from the published sequence of an animal captured from the Comores, indicating substantial divergence between the Indonesian and Comorean populations. Nine morphological and meristic differences are purported to distinguish L. menadoensis and L. chalumnae, based on comparison of a single specimen of L. menadoensis to a description of five individuals of L. chalumnae from the Comores. A survey of the literature provided data on 4 of the characters used to distinguish L. menadoensis from L. chalumnae from an additional 16 African coelacanths; for all 4 characters, the Indonesian sample was within the range of variation reported for the African specimens. Nonetheless, L. chalumnae and L. menadoensis appear to be separate species based on divergence of mitochondrial DNA.

The relationship between symptoms and IgG and IgE antibodies in an office environment.

Airborne fungi have been postulated as a cause of symptoms among office workers. Using the MAST chemiluminescent system, this study evaluated 36 IgG and 36 IgE antibody levels in 47 office workers from an area with elevated airborne fungal concentrations and 44 office workers from an otherwise similar area with lower airborne fungal exposure. No difference was found in IgG antibody to fungi between the lower and higher exposure areas, but high IgG antibody to one or more of the fungi studied was detected in 67% of all the workers tested. IgE antibody to one or more antigens was detected in 40% of the participants. Workers who reported atopic symptoms (sneezing, runny nose, and itchy eyes) or "sick building" symptoms (any three of the following temporally related to work: headache, fatigue, stuffy nose, irritated eyes, or sore throat) were more likely to have one positive IgE antibody test. Type I hypersensitivity to aeroallergens besides fungi may play a role in some symptoms reported by some participants in this office building.

Dermoid cyst of the lateral neck: a case report and literature review.

Dermoid cysts of the lateral neck are rare, with the majority of head and neck dermoids occurring in the midline. The demonstration of a fat-fluid level on MRI or CT is diagnostic for a cervical dermoid cyst. The treatment of choice remains surgical excision.

Object individuation in infancy: the use of featural information in reasoning about occlusion events.

Recent findings by Xu and Carey (1996) indicate that, after seeing two distinct objects (e.g., a duck and a ball) emerge on the opposite sides of a screen, 10-month-olds show no surprise when the screen is removed to reveal one (e.g., a duck) as opposed to two objects (e.g., a duck and a ball). The authors took their results to mean that 10-month-olds are unable to use featural information to individuate objects. The present research examined a different interpretation of the results. This interpretation was based on a distinction between event mapping, in which infants see a sequence of two distinct events and judge whether the two are consistent, and event monitoring, in which infants see a single event and judge whether successive portions of the event are consistent. The present research contrasted infants' performances in event-mapping tasks in which they saw first an occlusion and then a no-occlusion situation (as in Xu & Carey) and in event-monitoring tasks in which they saw only an occlusion situation. It was hypothesized that infants would be more likely to give evidence of correct individuation when tested with the event-monitoring as opposed to the event-mapping tasks. Eight experiments were conducted with infants ages 7.5 to 11.5 months. These experiments yielded two main findings. First, when tested with an event-monitoring task, even 7.5-month-olds give evidence that they can use featural information to individuate the objects involved in an occlusion event. Second, when tested with an event-mapping task, even 9.5-month-olds give evidence that they can use featural information to interpret an occlusion event as long as the event is made extremely simple. These findings give weight to the distinction between event mapping and monitoring and more generally begin to shed light on the fundamental processes involved in infants' formation and use of event representations.

Large-subunit ribosomal RNA systematics of symbiotic dinoflagellates: morphology does not recapitulate phylogeny.

Biochemical, histological, physiological, and genetic evidence indicates that dinoflagellates symbiotic with marine invertebrates are a heterogeneous complex of taxa, representing at least five genera in three orders. Despite a wealth of data regarding morphological, biochemical, and behavioral differences among symbiotic dinoflagellates, knowledge concerning patterns of diversification is limited. I analyzed approximately 900 bp of the 5' end of the large-subunit ribosomal RNA gene from 14 dinoflagellate isolates: six cultured Symbiodinium specimens, two cultured symbiotic Gymnodinium, two algal samples isolated from reef-building corals, an algal sample obtained from cultures of the jellyfish Cassiopea xamachana, and three free-living Gymnodinium isolates. Results show that morphological similarities among the examined symbiotic taxa do not necessarily correspond with molecular phylogeny. The included Symbiodinium taxa represent a paraphyletic assemblage while Gymnodinium is reconstructed as a polyphyletic assemblage. Analysis indicates that all the included symbiotic dinoflagellates descended from a common, symbiotic ancestor (though within the dinoflagellates, symbiosis is a polyphyletic trait). Additionally, two free-living dinoflagellates emerge within the symbiotic clade, suggesting that the symbiotic lifestyle has been lost at least once in this group. It has been hypothesized that rates of evolution within mutualistic endosymbioses should be reduced relative to free-living taxa. However, results indicate that rates of molecular, morphological, biochemical and behavioral change are similar among branches leading to symbiotic and free-living dinoflagellates.

Mitochondrial DNA sequencing reveals extreme genetic differentiation in a cryptic species complex of neotropical pseudoscorpions.

The neotropical pseudoscorpion Cordylochernes scorpioides (Chernetidae: Lamprochernetinae) is currently described as a single species ranging from Central America to northern Argentina. However, interpopulation crosses have recently demonstrated that C. scorpioides actually represents a complex of cryptic species. Here we present mitochondrial COI gene sequence data from C. scorpioides individuals from Panama, Trinidad, and French Guiana which demonstrate little or no intrapopulation variability but divergence ranging from 2.6 to 13.8% between geographic populations. Phylogenetic analysis provides evidence of a major split between C. scorpioides lineages from Central and South America. Levels of interpopulation mtDNA divergence correspond well with previously established patterns of postzygotic reproductive incompatibility between geographically distinct units within the C. scorpioides complex. By contrast, multivariate morphometric analysis demonstrates that extensive sequence divergence has occurred in the absence of appreciable morphological differentiation between the populations. To provide a framework for assessing the scale of geographic divergence in C. scorpioides, Cordylochernes sequences were compared with homologous sequence from its presumed sister taxon, Lustrochernes, and from Parachernes and Semeiochernes, representatives of the second chernetid subfamily, the Chernetinae. Our preliminary, generic-level analysis suggests that COI sequence data may prove useful in resolving relationships within this problematic family.

Raw shellfish consumption and warning labels: results from the 1993 Texas Behavioral Risk Factor Surveillance System (BRFSS) survey.

We used the 1993 Texas Behavioral Risk Factor Surveillance System survey to assess the prevalence of raw shellfish consumption and to find the demographic and behavioral characteristics of raw shellfish consumers. We studied the general impact of warning labels reported by survey respondents. Data were analyzed using univariate and multiple logistic regression methods. Fourteen percent of the Texas surveyed reported consuming raw shellfish. Respondents with incomes greater than or equal to $25,000 and with education beyond high school were more likely to report consuming raw shellfish than were those with incomes less than $25,000 and with high school diplomas or less. Respondents at risk for acute and chronic drinking, driving while intoxicated, and driving without a seat belt were more likely than those not at risk of these behaviors to report consumption of raw shellfish. We did not find a significant difference between eaters and noneaters of raw shellfish regarding the impact of warning labels: however, among eaters of raw shellfish, older respondents were more likely than younger respondents to report that warning labels had no effect on them.

Hypersensitivity reactions and specific antibodies in workers exposed to industrial enzymes at a biotechnology plant.

Thirty-six employees who produced industrial enzymes from selected strains of bacteria and fungi were evaluated by epicutaneous threshold testing and enzyme-linked immunosorbent assays (ELISA) for specific IgE and IgG antibodies. The workers complained of 'asthma- and flu-like' symptoms, which generally lessened away from work. The enzymes evaluated were: alpha-amylase (1,4-alpha-d-glucan glucanohydrolase) from Bacillus licheniformis (alpha ABl), B. subtilis formation 1 (alpha A1Bs) and B. subtilis formation 2 (alpha A2Bs); purified alpha-amylase from B. licheniformis (C alpha ABl) and A. oryzae (C alpha AAo); alkaline protease from B. licheniformis (APBl) and purified alkaline protease (CAPBl); amyloglucosidase (1,4-alpha-d-glucan glucohydrolase) from A. niger (AGAn) and purified amyloglucosidase (CAGAn). Statistically significant increases (P > 0.05) in the proportion of workers having positive skin tests to CAPBl, AGAn and CAGAn were found. Significantly elevated (P > 0.05) mean specific IgE results were observed for C alpha AAo CAGAn and AGAn, and elevated (P > 0.05) mean specific IgGs were observed for C alpha AAo, CAGAn, AGAn, alpha A1Bs, alpha AB1 and alpha A2Bs. These results indicate that occupational exposure to some industrial enzymes can cause immediate-onset cutaneous hypersensitivity reactions, pulmonary function deficits and significantly elevated specific antibody levels. Our results are equivocal as to whether work-related respiratory and cutaneous hypersensitivity reactions are antibody mediated, as there was no statistically significant association between these reactions and specific IgE or IgG levels.