1,259 research outputs found
Sexual responsiveness is condition-dependent in female guppies, but preference functions are not
BACKGROUND: Variation in mate choice behaviour among females within a population may influence the strength and form of sexual selection, yet the basis for any such variation is still poorly understood. Condition-dependence may be an important source of variation in female sexual responsiveness and in the preference functions for male display traits that she expresses when choosing. We manipulated food intake of female guppies (Poecilia reticulata), and examined the effect on several measures of condition and various components of mate choice behaviour. RESULTS: Diet significantly influenced four measures of female condition: standard length, weight, reproductive status and somatic fat reserves. Diet also significantly affected female sexual responsiveness, but not preference functions: females in good and poor condition prefer the same males. CONCLUSIONS: Variation in female condition within populations is therefore unlikely to influence the direction of sexual selection imposed by female choice. It may, however, influence the strength of sexual selection due to its effects on female responsiveness. The relative importance of female choice as a sexually selective force may also covary with female condition, however, because low responsiveness may result in sneak copulations being relatively more important as a determinant of the paternity of offspring. Differences among populations in mean condition may also influence geographic differences in the strength of sexual selection
Expression and regulation of the rate-limiting enzymes of the kynurenine pathway in the mouse brain
During the mid-1900’s, early anti-depressants were developed to increase levels of catecholamines within the brain, leading to the theory that depression symptomology was a result of an imbalance of neurotransmitters within the brain. To date, the catecholamine theory of depression is still held to be the prevailing theory as selective serotonin reuptake inhibitors being the most commonly prescribed anti-depressants. However, the incidence of depression is still rising with a vast amount of patients failing to respond to current treatments, and with this knowledge, additional theories of the neurobiology of depression have arisen over the past 30 years. A leading theory is Kynurenine Pathway activation in relation to inflammation- or stress-induced depression-like behaviors. There has been a tremendous amount of data connecting activated immune system (or hypothalamic-pituitary-adrenal axis), increased kynurenine production and depression symptomology. Thus, understanding the factors that activate this pathway, as well as determining a relationship between anti-depressants and regulation of the Kynurenine Pathway, is an important next step in understanding the complex etiology of depression. My work has focused on 1) describing interactions between inflammation and stress to accentuate the expression of rate-limiting enzymes (indoleamine/tryptophan-2,3-dioxygenase: DOs) that metabolize the essential amino acid tryptophan to kynurenine, 2) detailing a novel interaction between galectins and interferon-gamma to accentuate DO expression within the brain, and finally 3) discuss the ability of current anti-depressant desipramine to block these interactions and attenuate DO expression within the brain and periphery as a possible new mechanism by which anti-depressants may be working to reduce depression symptomology
Choreographic and Somatic Approaches for the Development of Expressive Robotic Systems
As robotic systems are moved out of factory work cells into human-facing
environments questions of choreography become central to their design,
placement, and application. With a human viewer or counterpart present, a
system will automatically be interpreted within context, style of movement, and
form factor by human beings as animate elements of their environment. The
interpretation by this human counterpart is critical to the success of the
system's integration: knobs on the system need to make sense to a human
counterpart; an artificial agent should have a way of notifying a human
counterpart of a change in system state, possibly through motion profiles; and
the motion of a human counterpart may have important contextual clues for task
completion. Thus, professional choreographers, dance practitioners, and
movement analysts are critical to research in robotics. They have design
methods for movement that align with human audience perception, can identify
simplified features of movement for human-robot interaction goals, and have
detailed knowledge of the capacity of human movement. This article provides
approaches employed by one research lab, specific impacts on technical and
artistic projects within, and principles that may guide future such work. The
background section reports on choreography, somatic perspectives,
improvisation, the Laban/Bartenieff Movement System, and robotics. From this
context methods including embodied exercises, writing prompts, and community
building activities have been developed to facilitate interdisciplinary
research. The results of this work is presented as an overview of a smattering
of projects in areas like high-level motion planning, software development for
rapid prototyping of movement, artistic output, and user studies that help
understand how people interpret movement. Finally, guiding principles for other
groups to adopt are posited.Comment: Under review at MDPI Arts Special Issue "The Machine as Artist (for
the 21st Century)"
http://www.mdpi.com/journal/arts/special_issues/Machine_Artis
Shifting attention in viewer- and object-based reference frames after unilateral brain injury
The aims of the present study were to investigate the respective roles that object- and viewer-based reference frames play in reorienting visual attention, and to assess their influence after unilateral brain injury. To do so, we studied 16 right hemisphere injured (RHI) and 13 left hemisphere injured (LHI) patients. We used a cueing design that manipulates the location of cues and targets relative to a display comprised of two rectangles (i.e., objects). Unlike previous studies with patients, we presented all cues at midline rather than in the left or right visual fields. Thus, in the critical conditions in which targets were presented laterally, reorienting of attention was always from a midline cue. Performance was measured for lateralized target detection as a function of viewer-based (contra- and ipsilesional sides) and object-based (requiring reorienting within or between objects) reference frames. As expected, contralesional detection was slower than ipsilesional detection for the patients. More importantly, objects influenced target detection differently in the contralesional and ipsilesional fields. Contralesionally, reorienting to a target within the cued object took longer than reorienting to a target in the same location but in the uncued object. This finding is consistent with object-based neglect. Ipsilesionally, the means were in the opposite direction. Furthermore, no significant difference was found in object-based influences between the patient groups (RHI vs. LHI). These findings are discussed in the context of reference frames used in reorienting attention for target detection
Simulated Biological Fluid Exposure Changes Nanoceria’s Surface Properties but not its Biological Response
Nanoscale cerium dioxide (nanoceria) has industrial applications, capitalizing on its catalytic, abrasive, and energy storage properties. It auto-catalytically cycles between Ce3+ and Ce4+, giving it pro-and anti-oxidative properties. The latter mediates beneficial effects in models of diseases that have oxidative stress/inflammation components. Engineered nanoparticles become coated after body fluid exposure, creating a corona, which can greatly influence their fate and effects. Very little has been reported about nanoceria surface changes and biological effects after pulmonary or gastrointestinal fluid exposure. The study objective was to address the hypothesis that simulated biological fluid (SBF) exposure changes nanoceria’s surface properties and biological activity. This was investigated by measuring the physicochemical properties of nanoceria with a citric acid coating (size; morphology; crystal structure; surface elemental composition, charge, and functional groups; and weight) before and after exposure to simulated lung, gastric, and intestinal fluids. SBF-exposed nanoceria biological effect was assessed as A549 or Caco-2 cell resazurin metabolism and mitochondrial oxygen consumption rate. SBF exposure resulted in loss or overcoating of nanoceria’s surface citrate, greater nanoceria agglomeration, deposition of some SBF components on nanoceria’s surface, and small changes in its zeta potential. The engineered nanoceria and SBF-exposed nanoceria produced no statistically significant changes in cell viability or cellular oxygen consumption rates
- …