874 research outputs found
Geographic variability in Calligrapha verrucosa (Suffrian 1858), a willow-feeding leaf beetle from western North America(Coleoptera: Chrysomelidae)
A diagnosis is provided to separate Calligrapha verrucosa (Suffrian) from similar species. Geographic variability is described and illustrated for various populations of C. verrucosa. A map is provided to indicate the distribution of this species
ENDOSYMBIOTIC BACTERIA IN THE BED BUG, \u3cem\u3eCimex Lectularius\u3c/em\u3e L. (HEMIPTERA: CIMICIDAE)
The return of bed bugs to prominence as an urban pest has precipitated an emphatic research response from the scientific community in an effort to better understand their biology and management. However, not all aspects of bed bug biology have received equal attention. The role of symbiotic bacteria in the normal function and biology of insects is often underappreciated, and this is true of bed bugs. Bed bugs have two main endosymbiotic bacteria, a Wolbachia species and a poorly-characterized gamma-proteobacterium referred to as BLS. However, their interactions with the host are poorly understood. I explored various aspects of these symbionts and their relationship with bed bugs. Major objectives included studies of the methods for symbiont elimination to create aposymbiotic strains, modes of endosymbiont transmission within a bed bug population, and impacts of symbiont loss on the host. Additional studies of bed bugs measured the impact of juvenile hormone analogs for the control of bed bugs.
Endosymbionts often form close interdependent relationships with the host, making it difficult to create a truly aposymbiotic strain. Maintaining bed bugs at elevated temperature (36°C) for five weeks or feeding for eight weeks with the antibiotic rifamycin were determined to be the most effective methods of those examined, including the use of other antibiotics. Although these two treatments were not successful in eliminating symbionts completely from treated adults, aposymbiotic strains were successfully created by harvesting the offspring of treated bugs soon after treatment.
Transovarial transmission of endosymbionts in bed bugs is well documented, but additional methods of transmission have not been explored. The reproductive strategy exhibited by bed bugs, traumatic insemination, has been suggested as a possible avenue of horizontal transmission of symbionts. My experiments demonstrated horizontal transmission of BLS from the male to the female during mating, but there was no indication that the new infection was passed from females to males or directly to offspring. No horizontal transmission of Wolbachia was detected. There was also no evidence of transmission through coprophagy.
In contrast with normal symbiotic controls, bed bugs which lacked both symbionts took a significantly longer time to develop to the adult stage. Successive generations of aposymbiotic bugs took longer to develop, up to several months. Supplemental B Vitamins administered through blood meals did not compensate fully for the slowed development. Upon reaching the adult stage, aposymbiotic bugs were significantly smaller than normal bugs in total body length and head-capsule width. Symbiont loss did not directly affect fecundity of adults.
Hydroprene and methoprene administered as the active ingredients of formulated products produced negative effects such as reduced fecundity and increased mortality only at doses much greater than label rate, and did not inhibit feeding or activity at sub-lethal doses. This work with Juvenile Hormone analogs has been published in Pest Management Science
Magnetohydrodynamics of the Weakly Ionized Solar Photosphere
We investigate the importance of ambipolar diffusion and Hall currents for
high-resolution comprehensive ('realistic') photospheric simulations. To do so
we extended the radiative magnetohydrodynamics code \emph{MURaM} to use the
generalized Ohm's law under the assumption of local thermodynamic equilibrium.
We present test cases comparing analytical solutions with numerical simulations
for validation of the code. Furthermore, we carried out a number of numerical
experiments to investigate the impact of these neutral-ion effects in the
photosphere. We find that, at the spatial resolutions currently used (5-20 km
per grid point), the Hall currents and ambipolar diffusion begin to become
significant -- with flows of 100 m/s in sunspot light bridges, and changes of a
few percent in the thermodynamic structure of quiet-Sun magnetic features. The
magnitude of the effects is expected to increase rapidly as smaller-scale
variations are resolved by the simulations.Comment: accepted Ap
Population Variation In and Selection For Resistance to Pyrethroid-Neonicotinoid Insecticides in the Bed Bug
Pyrethroid resistance in bed bugs, Cimex lectularius, has prompted a change to combination products that include a pyrethroid and a neonicotinoid. Ten populations of bed bugs were challenged with two combination products (Temprid SC and Transport GHP). Susceptibility of these populations varied, with the correlated response of the two products indicating cross resistance. We imposed selection on three populations using label rate Temprid, and then reared progeny from unselected and selected strains. All selected strains were significantly less susceptible to Temprid SC than unselected strains. Temprid selected strains were also less susceptible to Transport. The pyrethroid component of Temprid showed a significantly higher LD50 in selected strains, but susceptibility to the neonicotinoid remained unchanged. Taken together these results indicate resistance to combination insecticides is present in field populations at levels that should be of concern, and that short-term selection affecting existing variance in susceptibility can quickly increase resistance
Health Care Delivery Practices in Huntington's Disease Specialty Clinics : An International Survey
The CHDI Foundation, Inc. funds Enroll-HD and the activities of the Enroll-HD Care Improvement Committee, including the present survey. We would like to acknowledge the Enroll-HD and REGISTRY administrative staff that assisted in the recruitment of sites and sites that completed the survey.Peer reviewedPublisher PD
Determination of the diffusion constant using phase-sensitive measurements
We apply a pulsed-light interferometer to measure both the intensity and the
phase of light that is transmitted through a strongly scattering disordered
material. From a single set of measurements we obtain the time-resolved
intensity, frequency correlations and statistical phase information
simultaneously. We compare several independent techniques of measuring the
diffusion constant for diffuse propagation of light. By comparing these
independent measurements, we obtain experimental proof of the consistency of
the diffusion model and corroborate phase statistics theory.Comment: 9 pages, 8 figures, submitted to Phys. Rev.
Generalized Analysis of Weakly-Interacting Massive Particle Searches
We perform a generalized analysis of data from WIMP search experiments for
point-like WIMPs of arbitrary spin and general Lorenz-invariant WIMP-nucleus
interaction. We show that in the non-relativistic limit only spin-independent
(SI) and spin-dependent (SD) WIMP-nucleon interactions survive, which can be
parameterized by only five independent parameters. We explore this
five-dimensional parameter space to determine whether the annual modulation
observed in the DAMA experiment can be consistent with all other experiments.
The pure SI interaction is ruled out except for very small region of parameter
space with the WIMP mass close to 50 GeV and the ratio of the WIMP-neutron to
WIMP-proton SI couplings . For the predominantly SD
interaction, we find an upper limit to the WIMP mass of about 18 GeV, which can
only be weakened if the constraint stemming from null searches for energetic
neutrinos from WIMP annihilation the Sun is evaded. None of the regions of the
parameter space that can reconcile all WIMP search results can be easily
accommodated in the minimal supersymmetric extension of the standard model.Comment: 27 pages, 3 figure
The COMPLETE Survey of Star-Forming Regions: Phase I Data
We present an overview of data available for the Ophiuchus and Perseus
molecular clouds from ``Phase I'' of the COMPLETE Survey of Star-Forming
Regions. This survey provides a range of data complementary to the Spitzer
Legacy Program ``From Molecular Cores to Planet Forming Disks.'' Phase I
includes: Extinction maps derived from 2MASS near-infrared data using the NICER
algorithm; extinction and temperature maps derived from IRAS 60 and 100um
emission; HI maps of atomic gas; 12CO and 13CO maps of molecular gas; and
submillimetre continuum images of emission from dust in dense cores. Not
unexpectedly, the morphology of the regions appears quite different depending
on the column-density tracer which is used, with IRAS tracing mainly warmer
dust and CO being biased by chemical, excitation and optical depth effects.
Histograms of column-density distribution are presented, showing that
extinction as derived from 2MASS/NICER gives the closest match to a log-normal
distribution as is predicted by numerical simulations. All the data presented
in this paper, and links to more detailed publications on their implications
are publically available at the COMPLETE website.Comment: Accepted by AJ. Full resolution version available from:
http://www.cfa.harvard.edu/COMPLETE/papers/complete_phase1.pd
Sex-Related Differences in Violence Exposure, Neural Reactivity to Threat, and Mental Health
The prefrontal cortex (PFC), hippocampus, and amygdala play an important role in emotional health. However, adverse life events (e.g., violence exposure) affect the function of these brain regions, which may lead to disorders such as depression and anxiety. Depression and anxiety disproportionately affect women compared to men, and this disparity may reflect sex differences in the neural processes that underlie emotion expression and regulation. The present study investigated sex differences in the relationship between violence exposure and the neural processes that underlie emotion regulation. In the present study, 200 participants completed a Pavlovian fear conditioning procedure in which cued and non-cued threats (i.e., unconditioned stimuli) were presented during functional magnetic resonance imaging. Violence exposure was previously assessed at four separate time points when participants were 11-19 years of age. Significant threat type (cued versus non-cued)âĂâsex and sexâĂâviolence exposure interactions were observed. Specifically, women and men differed in amygdala and parahippocampal gyrus reactivity to cued versus non-cued threat. Further, dorsolateral PFC (dlPFC) and inferior parietal lobule (IPL) reactivity to threat varied positively with violence exposure among women, but not men. Similarly, threat-elicited skin conductance responses varied positively with violence exposure among women. Finally, women reported greater depression and anxiety symptoms than men. These findings suggest that sex differences in threat-related brain and psychophysiological activity may have implications for mental health
Atypical audiovisual speech integration in infants at risk for autism
The language difficulties often seen in individuals with autism might stem from an inability to integrate audiovisual information, a skill important for language development. We investigated whether 9-month-old siblings of older children with autism, who are at an increased risk of developing autism, are able to integrate audiovisual speech cues. We used an eye-tracker to record where infants looked when shown a screen displaying two faces of the same model, where one face is articulating/ba/and the other/ga/, with one face congruent with the syllable sound being presented simultaneously, the other face incongruent. This method was successful in showing that infants at low risk can integrate audiovisual speech: they looked for the same amount of time at the mouths in both the fusible visual/ga/â audio/ba/and the congruent visual/ba/â audio/ba/displays, indicating that the auditory and visual streams fuse into a McGurk-type of syllabic percept in the incongruent condition. It also showed that low-risk infants could perceive a mismatch between auditory and visual cues: they looked longer at the mouth in the mismatched, non-fusible visual/ba/â audio/ga/display compared with the congruent visual/ga/â audio/ga/display, demonstrating that they perceive an uncommon, and therefore interesting, speech-like percept when looking at the incongruent mouth (repeated ANOVA: displays x fusion/mismatch conditions interaction: F(1,16) = 17.153, p = 0.001). The looking behaviour of high-risk infants did not differ according to the type of display, suggesting difficulties in matching auditory and visual information (repeated ANOVA, displays x conditions interaction: F(1,25) = 0.09, p = 0.767), in contrast to low-risk infants (repeated ANOVA: displays x conditions x low/high-risk groups interaction: F(1,41) = 4.466, p = 0.041). In some cases this reduced ability might lead to the poor communication skills characteristic of autism
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