748 research outputs found
The effects of dopamine and dopaminergic agents on an identified cockroach motoneurone
Dopamine is one of a number of neurotransmitter candidates found in the insect CNS, It has been localised in a number of neurones, and others have been shown to respond to the application of dopamine. This study investigates the response of the common inhibitory motoneurone D3 to dopamine, and its ionic basis. The response to dopamine is distinguished pharmacologically from responses to noradrenaline, octopamlne and acetylcholine, all neurotransmitter candidates within the insect CNS, and it is concluded that a receptor specific for dopamine is present on this cell. Finally, this putative dopamine receptor is characterised pharmacologically, and its position relative to the extant classification schemes for mammalian receptors, and its similarity or otherwise to other invertebrate dopamine receptors is discussed
Supercritical solvothermal synthesis under reducing conditions to increase stability and durability of Mo/ZSM-5 catalysts in methane dehydroaromatization
Natural gas is currently envisioned as a potential energy and hydrocarbon feedstock in the forthcoming years. To overcome the detrimental flaring of this natural gas and the partial release of its major component, methane, novel and more effective strategies are required. These include the development of new, efficient and seemingly stable catalysts able to rapidly convert methane into valuable feedstocks. We show a novel synthesis method of Mo/ZSM-5 based on a solvothermal synthesis under supercritical conditions and reducing atmosphere (SC-STSE) to improve metal dispersion and enhance catalyst stability and durability during the methane dehydroaromatization (MDA) reaction. In contrast to the conventional impregnation method, SC-STS-E provides a superhigh atom-like metal dispersion at the zeolite pores resulting in the most stable Mo/ZSM-5 catalyst for MDA with the highest long-term hydrocarbon yield (xCH4=11.6% and yC2+ = 8.9%, after 15 h on stream) among the catalysts reported in literature for this reaction
Age- and sex-dependent role of osteocytic pannexin1 on bone and muscle mass and strength
Pannexins (Panxs), glycoproteins that oligomerize to form hemichannels on the cell membrane, are topologically similar to connexins, but do not form cell-to-cell gap junction channels. There are 3 members of the family, 1-3, with Panx1 being the most abundant. All Panxs are expressed in bone, but their role in bone cell biology is not completely understood. We now report that osteocytic Panx1 deletion (Panx1Δot) alters bone mass and strength in female mice. Bone mineral density after reaching skeletal maturity is higher in female Panx1Δot mice than in control Panx1fl/fl mice. Further, osteocytic Panx1 deletion partially prevented aging effects on cortical bone structure and mechanical properties. Young 4-month-old female Panx1Δot mice exhibited increased lean body mass, even though pannexin levels in skeletal muscle were not affected; whereas no difference in lean body mass was detected in male mice. Furthermore, female Panx1-deficient mice exhibited increased muscle mass without changes in strength, whereas Panx1Δot males showed unchanged muscle mass and decreased in vivo maximum plantarflexion torque, indicating reduced muscle strength. Our results suggest that osteocytic Panx1 deletion increases bone mass in young and old female mice and muscle mass in young female mice, but has deleterious effects on muscle strength only in males
Numerical Methods in Cosmological Global Texture Simulations
Numerical simulations of the evolution of a global topological defect field
have two characteristic length scales --- one macrophysical, of order the field
correlation length, and the other microphysical, of order the field width. The
situation currently of most interest to particle cosmologists involves the
behaviour of a GUT-scale defect field at the epoch of decoupling, where the
ratio of these scales is typically of order . Such a ratio is
unrealisable in numerical work, and we consider the approximations which may be
employed to deal with this. Focusing on the case of global texture we outline
the implementation of the associated algorithms, and in particular note the
subtleties involved in handling texture unwinding events. Comparing the results
in each approach then establishes that, subject to certain constraints on the
minimum grid resolution, the methods described are both robust and consistent
with one another.Comment: LaTeX, IMPERIAL/TP/93-94/2
Recommended curriculum for subspecialty training in transplant infectious disease on behalf of the American Society of Transplantation Infectious Diseases Community of Practice Educational Initiatives Working Group
R. Avery, H. Clauss, L. Danziger-Isakov, J. Davis, K. Doucette, D. van Duin, J. Fishman, F. Gunseren, A. Humar, S. Husain, C. Isada, K. Julian, D. Kaul, D. Kumar, S. Martin, M. Michaels, M. Morris, F. Silveira, A. Subramanian. Recommended curriculum for subspecialty training in transplant infectious disease on behalf of the American Society of Transplantation Infectious Diseases Community of Practice Educational Initiatives Working Group. Transpl Infect Dis 2010: 12: 190–194. All rights reservedThe American Society of Transplantation Infectious Diseases (ID) Community of Practice has established an education workgroup to identify core components of a curriculum for training specialists in transplant ID. Clinical, laboratory, and research training form the triad of components on which an additional year of ID training, dedicated to the care of solid organ and hematopoietic stem cell transplant recipients, should be based. The recommended training environment would have access to adequate numbers of transplant patients, along with qualified faculty committed to teaching specialized fellows in this area. The learning objectives for both inpatient and outpatient clinical training are presented. The laboratory component requires trainees to attain expertize in utilizing and interpreting cutting-edge diagnostics used in transplant medicine. The research component may involve basic science, and translational or clinical research individualized to the trainee. Finally, suggestions for evaluation of both the fellows and the training program are provided.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79192/1/j.1399-3062.2010.00510.x.pd
Genome-Wide Association Studies of Coffee Intake in UK/US Participants of European Ancestry Uncover Gene-Cohort Influences
Coffee is one of the most widely consumed beverages. We performed a genome-wide association study (GWAS) of coffee intake in US-based 23andMe participants (N =130,153) and identified 7 significant loci, with many replicating in three multi-ancestral cohorts. We examined genetic correlations and performed a phenome-wide association study across thousands of biomarkers and health and lifestyle traits, then compared our results to the largest available GWAS of coffee intake from UK Biobank (UKB; N =334,659). The results of these two GWAS were highly discrepant. We observed positive genetic correlations between coffee intake and psychiatric illnesses, pain, and gastrointestinal traits in 23andMe that were absent or negative in UKB. Genetic correlations with cognition were negative in 23andMe but positive in UKB. The only consistent observations were positive genetic correlations with substance use and obesity. Our study shows that GWAS in different cohorts could capture cultural differences in the relationship between behavior and genetics
Genome Sequence of the Saprophyte Leptospira biflexa Provides Insights into the Evolution of Leptospira and the Pathogenesis of Leptospirosis
Leptospira biflexa is a free-living saprophytic spirochete present in aquatic environments. We determined the genome sequence of L. biflexa, making it the first saprophytic Leptospira to be sequenced. The L. biflexa genome has 3,590 protein-coding genes distributed across three circular replicons: the major 3,604 chromosome, a smaller 278-kb replicon that also carries essential genes, and a third 74-kb replicon. Comparative sequence analysis provides evidence that L. biflexa is an excellent model for the study of Leptospira evolution; we conclude that 2052 genes (61%) represent a progenitor genome that existed before divergence of pathogenic and saprophytic Leptospira species. Comparisons of the L. biflexa genome with two pathogenic Leptospira species reveal several major findings. Nearly one-third of the L. biflexa genes are absent in pathogenic Leptospira. We suggest that once incorporated into the L. biflexa genome, laterally transferred DNA undergoes minimal rearrangement due to physical restrictions imposed by high gene density and limited presence of transposable elements. In contrast, the genomes of pathogenic Leptospira species undergo frequent rearrangements, often involving recombination between insertion sequences. Identification of genes common to the two pathogenic species, L. borgpetersenii and L. interrogans, but absent in L. biflexa, is consistent with a role for these genes in pathogenesis. Differences in environmental sensing capacities of L. biflexa, L. borgpetersenii, and L. interrogans suggest a model which postulates that loss of signal transduction functions in L. borgpetersenii has impaired its survival outside a mammalian host, whereas L. interrogans has retained environmental sensory functions that facilitate disease transmission through water
A threatened ecological community: Research advances and priorities for Banksia woodlands
The rapid expansion of urban areas worldwide is leading to native habitat loss and ecosystem fragmentation and degradation. Although the study of urbanisation\u27s impact on biodiversity is gaining increasing interest globally, there is still a disconnect between research recommendations and urbanisation strategies. Expansion of the Perth metropolitan area on the Swan Coastal Plain in south-western Australia, one of the world\u27s thirty-six biodiversity hotspots, continues to affect the Banksia Woodlands (BWs) ecosystem, a federally listed Threatened Ecological Community (TEC). Here, we utilise the framework of a 1989 review of the state of knowledge of BWs ecology and conservation to examine scientific advances made in understanding the composition, processes and functions of BWs and BWs\u27 species over the last 30 years. We highlight key advances in our understanding of the ecological function and role of mechanisms in BWs that are critical to the management of this ecosystem. The most encouraging change since 1989 is the integration of research between historically disparate ecological disciplines. We outline remaining ecological knowledge gaps and identify key research priorities to improve conservation efforts for this TEC. We promote a holistic consideration of BWs with our review providing a comprehensive document that researchers, planners and managers may reference. To effectively conserve ecosystems threatened by urban expansion, a range of stakeholders must be involved in the development and implementation of best practices to conserve and maintain both biodiversity and human wellbeing
Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae
We systematically surveyed period variations of superhumps in SU UMa-type
dwarf novae based on newly obtained data and past publications. In many
systems, the evolution of superhump period are found to be composed of three
distinct stages: early evolutionary stage with a longer superhump period,
middle stage with systematically varying periods, final stage with a shorter,
stable superhump period. During the middle stage, many systems with superhump
periods less than 0.08 d show positive period derivatives. Contrary to the
earlier claim, we found no clear evidence for variation of period derivatives
between superoutburst of the same object. We present an interpretation that the
lengthening of the superhump period is a result of outward propagation of the
eccentricity wave and is limited by the radius near the tidal truncation. We
interpret that late stage superhumps are rejuvenized excitation of 3:1
resonance when the superhumps in the outer disk is effectively quenched. Many
of WZ Sge-type dwarf novae showed long-enduring superhumps during the
post-superoutburst stage having periods longer than those during the main
superoutburst. The period derivatives in WZ Sge-type dwarf novae are found to
be strongly correlated with the fractional superhump excess, or consequently,
mass ratio. WZ Sge-type dwarf novae with a long-lasting rebrightening or with
multiple rebrightenings tend to have smaller period derivatives and are
excellent candidate for the systems around or after the period minimum of
evolution of cataclysmic variables (abridged).Comment: 239 pages, 225 figures, PASJ accepte
- …