2,415 research outputs found
MODULATING MALE AGGRESSION AND COURTSHIP: DETECTING EXTERNAL PHEROMONAL AND NUTRITIONAL INFORMATION
Survival and reproduction in the natural world requires an organism to identify and react to the presence of environmental stimuli in a time and cue dependent manner. Such temporal specificity requires the development and use of specialized sensory organs that receive this external sensory information. Neurons within the specialized sensory organs respond to touch, taste, pheromones, chemicals, and light, and transduce this information to the central brain. In many systems, gustatory and olfactory chemosensation in particular, provides critical information regarding sex and species identification as well as the status of food resources. The output of neurons which receive chemical information is regulated by the action of biogenic amines, including serotonin, dopamine, and norepinephrine. In this dissertation I examined the role of octopamine (the invertebrate structural homologue of norepinephrine) signaling in the regulation of two behaviors required for survival and reproduction; aggression and courtship.
In chapter II, I, along with my colleagues, demonstrate that neurons bearing the taste receptor Gr32a form putative synapses with octopamine neurons within the subesophageal zone, and that octopamine neurons promote male aggression and courtship behavior. These findings help to explain how an organism selects appropriate behavioral responses when confronted with the pheromonal signals of a rival male.
In chapter III, I examined the effects of octopamine signaling on taste sensitization. In this section, I examined the distribution and function of neurons that express the OaÎČ1R receptor, and found that these neurons are sugar sensitive. As the presence of a food source is known to be a major contributor to the generation of aggressive and courtship behavior, these findings imply a mechanism by which exposure to an environmental stimulus or changes in internal octopamine signaling may sensitize a particular form of sensory input
Engineering in German
WPIâs German curriculum provides students with fast-paced language learning and culture exploration, but lacks STEM topics that engineering students would like to use in a global workplace. We have created a framework for slowly introducing STEM topics into the German curriculum. From conducting two separate surveys among students and interviews with faculty, we found there is mixed interest from the current WPI community in STEM inclusion with German courses. With these results we structured the framework to maintain the current curriculum and slowly add STEM topics in small amounts. This additive process can continue until new courses and international connections with companies and universities can be established
ALMA Observations of the Orion Proplyds
We present ALMA observations of protoplanetary disks ("proplyds") in the
Orion Nebula Cluster. We imaged 5 individual fields at 856um containing 22
HST-identified proplyds and detected 21 of them. Eight of those disks were
detected for the first time at submillimeter wavelengths, including the most
prominent, well-known proplyd in the entire Orion Nebula, 114-426. Thermal dust
emission in excess of any free-free component was measured in all but one of
the detected disks, and ranged between 1-163 mJy, with resulting disk masses of
0.3-79 Mjup. An additional 26 stars with no prior evidence of associated disks
in HST observations were also imaged within the 5 fields, but only 2 were
detected. The disk mass upper limits for the undetected targets, which include
OB stars, theta1Ori C and theta1Ori F, range from 0.1-0.6 Mjup. Combining these
ALMA data with previous SMA observations, we find a lack of massive (>3 Mjup)
disks in the extreme-UV dominated region of Orion, within 0.03 pc of O-star
theta1Ori C. At larger separations from theta1Ori C, in the far-UV dominated
region, there is a wide range of disk masses, similar to what is found in
low-mass star forming regions. Taken together, these results suggest that a
rapid dissipation of disk masses likely inhibits potential planet formation in
the extreme-UV dominated regions of OB associations, but leaves disks in the
far-UV dominated regions relatively unaffected.Comment: ApJ, in pres
Accounting for changing temperature patterns increases historical estimates of climate sensitivity
Eight atmospheric general circulation models (AGCMs) are forced with observed historical (1871â2010) monthly sea surface temperature and sea ice variations using the Atmospheric Model Intercomparison Project II data set. The AGCMs therefore have a similar temperature pattern and trend to that of observed historical climate change. The AGCMs simulate a spread in climate feedback similar to that seen in coupled simulations of the response to CO2 quadrupling. However, the feedbacks are robustly more stabilizing and the effective climate sensitivity (EffCS) smaller. This is due to a pattern effect, whereby the pattern of observed historical sea surface temperature change gives rise to more negative cloud and longwave clearâsky feedbacks. Assuming the patterns of longâterm temperature change simulated by models, and the radiative response to them, are credible; this implies that existing constraints on EffCS from historical energy budget variations give values that are too low and overly constrained, particularly at the upper end. For example, the pattern effect increases the longâterm Otto et al. (2013, https://doi.org/10.1038/ngeo1836) EffCS median and 5â95% confidence interval from 1.9 K (0.9â5.0 K) to 3.2 K (1.5â8.1 K
Study protocol - A systematic review and meta-analysis of hypothermia in experimental traumatic brain injury: Why have promising animal studies not been replicated in pragmatic clinical trials?
Traumatic brain injury (TBI) is a major cause of death and permanent disability. Systemic hypothermia, a treatment used in TBI for many decades, has recently been found to be associated with neutral or unfavourable clinical outcomes despite apparently promising preclinical research. Systematic review and metaâanalysis is a tool to summarize literature and observe trends in experimental design and quality that underpin its general conclusions. Here we aim to use these techniques to describe the use of hypothermia in animal TBI models, collating data relating to outcome and both study design and quality. From here we intend to observe correlations between features and attempt to explain any discrepancies found between animal and clinical data. This protocol describes the relevant methodology in detail
Submillimeter Array Observations of the RX J1633.9-2442 Transition Disk: Evidence for Multiple Planets in the Making
We present continuum high resolution Submillimeter Array (SMA) observations
of the transition disk object RX J1633.9-2442, which is located in the
Ophiuchus molecular cloud and has recently been identified as a likely site of
ongoing giant planet formation. The observations were taken at 340 GHz (880
micron) with the SMA in its most extended configuration, resulting in an
angular resolution of 0.3" (35 AU at the distance of the target). We find that
the disk is highly inclined (i ~50 deg) and has an inner cavity ~25 AU in
radius, which is clearly resolved by our observations. We simultaneously model
the entire optical to millimeter wavelength spectral energy distribution (SED)
and SMA visibilities of RX J1633.9-2442 in order to constrain the structure of
its disk. We find that an empty cavity ~25 AU in radius is inconsistent with
the excess emission observed at 12, 22, and 24 micron. Instead, the mid-IR
excess can be modeled by either a narrow, optically thick ring at ~10 AU or an
optically thin region extending from ~7 AU to ~25 AU. The inner disk (r < 5 AU)
is mostly depleted of small dust grains as attested by the lack of detectable
near-IR excess. We also present deep Keck aperture masking observations in the
near-IR, which rule out the presence of a companion up to 500 times fainter
than the primary star (in K-band) for projected separations in the 5-20 AU
range. We argue that the complex structure of the RX J1633.9-2442 disk is best
explained by multiple planets embedded within the disk. We also suggest that
the properties and incidence of objects such as RX J1633.9-2442, T Cha, and
LkCa 15 (and those of the companions recently identified to these two latter
objects) are most consistent with the runaway gas accretion phase of the core
accretion model, when giant planets gain their envelopes and suddenly become
massive enough to open wide gaps in the disk.Comment: Accepted for publication in Ap
Realistic boundary conditions for stochastic simulations of reaction-diffusion processes
Many cellular and subcellular biological processes can be described in terms
of diffusing and chemically reacting species (e.g. enzymes). Such
reaction-diffusion processes can be mathematically modelled using either
deterministic partial-differential equations or stochastic simulation
algorithms. The latter provide a more detailed and precise picture, and several
stochastic simulation algorithms have been proposed in recent years. Such
models typically give the same description of the reaction-diffusion processes
far from the boundary of the simulated domain, but the behaviour close to a
reactive boundary (e.g. a membrane with receptors) is unfortunately
model-dependent. In this paper, we study four different approaches to
stochastic modelling of reaction-diffusion problems and show the correct choice
of the boundary condition for each model. The reactive boundary is treated as
partially reflective, which means that some molecules hitting the boundary are
adsorbed (e.g. bound to the receptor) and some molecules are reflected. The
probability that the molecule is adsorbed rather than reflected depends on the
reactivity of the boundary (e.g. on the rate constant of the adsorbing chemical
reaction and on the number of available receptors), and on the stochastic model
used. This dependence is derived for each model.Comment: 24 pages, submitted to Physical Biolog
Acceleration of hippocampal atrophy rates in asymptomatic amyloidosis.
Increased rates of brain atrophy measured from serial magnetic resonance imaging precede symptom onset in Alzheimer's disease and may be useful outcome measures for prodromal clinical trials. Appropriate trial design requires a detailed understanding of the relationships between ÎČ-amyloid load and accumulation, and rate of brain change at this stage of the disease. Fifty-two healthy individuals (72.3 ± 6.9 years) from Australian Imaging, Biomarkers and Lifestyle Study of Aging had serial (0, 18 m, 36 m) magnetic resonance imaging, (0, 18 m) Pittsburgh compound B positron emission tomography, and clinical assessments. We calculated rates of whole brain and hippocampal atrophy, ventricular enlargement, amyloid accumulation, and cognitive decline. Over 3 years, rates of whole brain atrophy (p < 0.001), left and right hippocampal atrophy (p = 0.001, p = 0.023), and ventricular expansion (p < 0.001) were associated with baseline ÎČ-amyloid load. Whole brain atrophy rates were also independently associated with ÎČ-amyloid accumulation over the first 18 months (p = 0.003). Acceleration of left hippocampal atrophy rate was associated with baseline ÎČ-amyloid load across the cohort (p < 0.02). We provide evidence that rates of atrophy are associated with both baseline ÎČ-amyloid load and accumulation, and that there is presymptomatic, amyloid-mediated acceleration of hippocampal atrophy. Clinical trials using rate of hippocampal atrophy as an outcome measure should not assume linear decline in the presymptomatic phase
Octopamine Neuromodulation Regulates Gr32a-Linked Aggression and Courtship Pathways in Drosophila Males
Chemosensory pheromonal information regulates aggression and reproduction in many species, but how pheromonal signals are transduced to reliably produce behavior is not well understood. Here we demonstrate that the pheromonal signals detected by Gr32a-expressing chemosensory neurons to enhance male aggression are filtered through octopamine (OA, invertebrate equivalent of norepinephrine) neurons. Using behavioral assays, we find males lacking both octopamine and Gr32a gustatory receptors exhibit parallel delays in the onset of aggression and reductions in aggression. Physiological and anatomical experiments identify Gr32a to octopamine neuron synaptic and functional connections in the suboesophageal ganglion. Refining the Gr32a-expressing population indicates that mouth Gr32a neurons promote male aggression and form synaptic contacts with OA neurons. By restricting the monoamine neuron target population, we show that three previously identified OA-FruM neurons involved in behavioral choice are among the Gr32a-OA connections. Our findings demonstrate that octopaminergic neuromodulatory neurons function as early as a second-order step in this chemosensory-driven male social behavior pathway
Octopamine Neuromodulation Regulates Gr32a-Linked Aggression and Courtship Pathways in \u3ci\u3eDrosophila\u3c/i\u3e Males
Chemosensory pheromonal information regulates aggression and reproduction in many species, but how pheromonal signals are transduced to reliably produce behavior is not well understood. Here we demonstrate that the pheromonal signals detected by Gr32a-expressing chemosensory neurons to enhance male aggression are filtered through octopamine (OA, invertebrate equivalent of norepinephrine) neurons. Using behavioral assays, we find males lacking both octopamine and Gr32a gustatory receptors exhibit parallel delays in the onset of aggression and reductions in aggression. Physiological and anatomical experiments identify Gr32a to octopamine neuron synaptic and functional connections in the suboesophageal ganglion. Refining the Gr32a-expressing population indicates that mouth Gr32a neurons promote male aggression and form synaptic contacts with OA neurons. By restricting the monoamine neuron target population, we show that three previously identified OA-FruM neurons involved in behavioral choice are among the Gr32a-OA connections. Our findings demonstrate that octopaminergic neuromodulatory neurons function as early as a second-order step in this chemosensory-driven male social behavior pathway
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