Comparison of Cuticular Hydrocarbons in Three Populations of the Carpenter Bee “Ceratina calcarata” to help Understand their Role in Social Evolution

For the second summer in a row I analysed the composition of cuticular hydrocarbons (CHCs) on carpenter bees Ceratina calcarata, this time in populations from Missouri and Georgia as well as from New Hampshire. My goal was to find out if the CHC compositions differed significantly among these three populations. My results affirmed our prediction that the CHC composition varies by population, though there does appear to be some overlap across populations. The CHC variation observed suggests that chemical composition changes with latitude. CHCs are thought to have initially evolved to prevent water loss and then became part of chemical communication among individuals. Communication among insects plays a large role in their behavior and is critical to the development of complex social systems

Beehavior and Beyond: Realizations in Research

Most people would mistake the small carpenter bee Ceratina calcarata and its relatives for ants with wings,and I won’t pretend that I could tell the difference before I spent a summer researching this particular bee species. We are conditioned to associate bees with three things: black and yellow coloration, honey, and stinging pain. The small carpenter bee species that I studied, however, did not exhibit a single characteristic from that list, which I found shocking, given that they are native to North America and locally abundant. Was I asleep during the lecture on the North American native insect ecosystems in biology class? Even if I reviewed every lecture since kindergarten, I doubt that information would have popped up. This was the first of many realizations stimulated by my initial experiences with research as an undergraduate

Job Satisfaction Among Staff Nurses in Mental Health Units in a VA facility

Studies have indicated that work environment in mental health is stressful, however, few studies have focused on staff working in acute mental health settings (Jenkins & Elliott, 2004). The purpose of this study was to describe job satisfaction among a sample of mental health staff nurses who were caring for patients with acute psychiatric disorders in a federal hospital. The second purpose was to determine if there were relationships between global job satisfaction and ethnicity, years in the organization, current unit, field of nursing, working with patients with mental disorders and age of staff nurses. An anonymous survey was distributed to a convenience sample of 69 registered nurses who worked on the four mental health units using the McCloskey/Mueller Satisfaction Scale (MMSS). The scale is a 31-item questionnaire that identifies eight types of satisfaction. Thirty two responses were received out of 69 surveys distributed, a response rate of 46%. The findings revealed that mental health staff nurses were neither satisfied nor dissatisfied with the current jobs (mean score 3.4). Nurses were most happy about flexibility in work schedules and were most unhappy with balance and work. The demographic findings indicated that over 70% of the nurses were concerned about their personal safety while on duty. A Pearson correlations test revealed that there is no significant relationship between global job satisfaction and the seven variables mentioned. A chi-square test found no correlation between ethnicity and global job satisfaction. The study used a small, convenience non random sample, therefore findings cannot be generalized to all nurses at the VA or general nursing population. To determine the levels of nurses\u27 job satisfaction with a larger random sample, a repeat study is recommended to include mental health nurses in different facilities in California and other states. This research may guide future research in examining job satisfaction as a measure to the delivery of quality patient care and patient outcomes

Numerical modeling of elastic waves across imperfect contacts

A numerical method is described for studying how elastic waves interact with imperfect contacts such as fractures or glue layers existing between elastic solids. These contacts have been classicaly modeled by interfaces, using a simple rheological model consisting of a combination of normal and tangential linear springs and masses. The jump conditions satisfied by the elastic fields along the interfaces are called the "spring-mass conditions". By tuning the stiffness and mass values, it is possible to model various degrees of contact, from perfect bonding to stress-free surfaces. The conservation laws satisfied outside the interfaces are integrated using classical finite-difference schemes. The key problem arising here is how to discretize the spring-mass conditions, and how to insert them into a finite-difference scheme: this was the aim of the present paper. For this purpose, we adapted an interface method previously developed for use with perfect contacts [J. Comput. Phys. 195 (2004) 90-116]. This numerical method also describes closely the geometry of arbitrarily-shaped interfaces on a uniform Cartesian grid, at negligible extra computational cost. Comparisons with original analytical solutions show the efficiency of this approach.Comment: to be published in SIAM Journal of Scientific Computing (2006

Diffusive approximation of a time-fractional Burger's equation in nonlinear acoustics

A fractional time derivative is introduced into the Burger's equation to model losses of nonlinear waves. This term amounts to a time convolution product, which greatly penalizes the numerical modeling. A diffusive representation of the fractional derivative is adopted here, replacing this nonlocal operator by a continuum of memory variables that satisfy local-in-time ordinary differential equations. Then a quadrature formula yields a system of local partial differential equations, well-suited to numerical integration. The determination of the quadrature coefficients is crucial to ensure both the well-posedness of the system and the computational efficiency of the diffusive approximation. For this purpose, optimization with constraint is shown to be a very efficient strategy. Strang splitting is used to solve successively the hyperbolic part by a shock-capturing scheme, and the diffusive part exactly. Numerical experiments are proposed to assess the efficiency of the numerical modeling, and to illustrate the effect of the fractional attenuation on the wave propagation.Comment: submitted to Siam SIA

Development of an orbit determination program to regress for lunar potential constants

Orbit calculation program modified to provide corrected state vectors for lunar potential constants in moon centered coordinate syste

'Home game': domestic abuse and football

Increased reports of domestic violence and abuse (DVA) following football matches have been documented, within both quantitative studies and the media, leading to questions about the policy and practice responses required. However, qualitative research facilitating understanding of the apparent link between football and DVA is lacking. Drawing upon research with key stakeholders across England and Scotland, this paper provides a rare insight into their understanding of the contested and complex relationship between football and DVA, including the role of contributory and confounding factors such as alcohol, match expectations, masculinity, entitlement and permissions. It is argued that while football may provide a potential platform for challenging DVA, focusing on football (or other specific factors or events) as causative risks re-incidentalising DVA and detaching it from feminist frameworks that have established DVA as a sustained behaviour grounded in gendered inequalities. This paper concludes by considering the broader conceptual implications of these findings for future research, policy and practice

Short versus long range interactions and the size of two-body weakly bound objects

Very weakly bound systems may manifest intriguing "universal" properties, independent of the specific interaction which keeps the system bound. An interesting example is given by relations between the size of the system and the separation energy, or scaling laws. So far, scaling laws have been investigated for short-range and long-range (repulsive) potentials. We report here on scaling laws for weakly bound two-body systems valid for a larger class of potentials, i.e. short-range potentials having a repulsive core and long-range attractive potentials. We emphasize analogies and differences between the short- and the long-range case. In particular, we show that the emergence of halos is a threshold phenomenon which can arise when the system is bound not only by short-range interactions but also by long-range ones, and this for any value of the orbital angular momentum $\ell$. These results enlarge the image of halo systems we are accustomed to.Comment: 6 pages, 1 figure. To be published in the Proceedings of the Workshop "Hirschegg 2003: Nuclear Structure and Dynamics at the Limits", Hirschegg, January 12 - 18, 200

Honey from the Hives: A Theoretical and Computational Exploration of Combinatorial Hives

In the first half of this manuscript, we begin with a brief review of combinatorial hives as introduced by Knutson and Tao, and focus on a conjecture by Danilov and Koshevoy for generating such a hive from Hermitian matrix pairs through an optimization scheme. We examine a proposal by Appleby and Whitehead in the spirit of this conjecture and analytically elucidate an obstruction in their construction for guaranteeing hive generation, while detailing stronger conditions under which we can produce hives with almost certain probability. We provide the first mapping of this prescription onto a practical algorithmic space that enables us to produce affirming computational results and open a new area of research into the analysis of the random geometries and curvatures of hive surfaces from select matrix ensembles. The second part of this manuscript concerns Littlewood-Richardson coefficients and methods of estimating them from the hive construction. We illustrate experimental confirmation of two numerical algorithms that we provide as tools for the community: one as a rounded estimator on the continuous hive polytope volume following a proposal by Narayanan, and the other as a novel construction using a coordinate hit-and-run on the hive lattice itself. We compare the advantages of each, and include numerical results on their accuracies for some tested cases.Comment: 25 pages, 20 figure