Fire Ant Decapitating Fly Cooperative Release Programs (1994–2008): Two Pseudacteon Species, P. tricuspis and P. curvatus, Rapidly Expand Across Imported Fire Ant Populations in the Southeastern United States

Natural enemies of the imported fire ants, Solenopsis invicta Buren S. richteri Forel (Hymenoptera: Formicidae), and their hybrid, include a suite of more than 20 fire ant decapitating phorid flies from South America in the genus Pseudacteon. Over the past 12 years, many researchers and associates have cooperated in introducing several species as classical or self-sustaining biological control agents in the United States. As a result, two species of flies, Pseudacteon tricuspis Borgmeier and P. curvatus Borgmeier (Diptera: Phoridae), are well established across large areas of the southeastern United States. Whereas many researchers have published local and state information about the establishment and spread of these flies, here distribution data from both published and unpublished sources has been compiled for the entire United States with the goal of presenting confirmed and probable distributions as of the fall of 2008. Documented rates of expansion were also used to predict the distribution of these flies three years later in the fall of 2011. In the fall of 2008, eleven years after the first successful release, we estimate that P. tricuspis covered about 50% of the fire ant quarantined area and that it will occur in almost 65% of the quarantine area by 2011. Complete coverage of the fire ant quarantined area will be delayed or limited by this species' slow rate of spread and frequent failure to establish in more northerly portions of the fire ant range and also, perhaps, by its preference for red imported fire ants (S. invicta). Eight years after the first successful release of P. curvatus, two biotypes of this species (one biotype occurring predominantly in the black and hybrid imported fire ants and the other occurring in red imported fire ants) covered almost 60% of the fire ant quarantined area. We estimate these two biotypes will cover almost 90% of the quarantine area by 2011 and 100% by 2012 or 2013. Strategic selection of several distributional gaps for future releases will accelerate complete coverage of quarantine areas. However, some gaps may be best used for the release of additional species of decapitating flies because establishment rates may be higher in areas without competing species

Parasite Lost: Chemical and Visual Cues Used by Pseudacteon in Search of Azteca instabilis

An undescribed species of phorid fly (genus: Pseudacteon) parasitizes the ant Azteca instabilis F Smith, by first locating these ants through the use of both chemical and visual cues. Experiments were performed in Chiapas, Mexico to examine a) the anatomical source of phorid attractants, b) the specific chemicals produced that attract phorids, and c) the nature of the visual cues used by phorids to locate the ants. We determined that phorid-attracting chemicals were present within the dorsal section of the abdomen, the location of the pygidial gland. Further experiments indicate that a pygidial gland compound, 1-acetyl-2-methylcyclopentane, is at least partially responsible for attracting phorid flies to their host. Finally, although visual cues such as movement were important for host location, size and color of objects did not influence the frequency with which phorids attacked moving targets

Monitoring one-electron photo-oxidation of guanine in DNA crystals using ultrafast infrared spectroscopy

To understand the molecular origins of diseases caused by ultraviolet and visible light, and also to develop photodynamic therapy, it is important to resolve the mechanism of photoinduced DNA damage. Damage to DNA bound to a photosensitizer molecule frequently proceeds by one-electron photo-oxidation of guanine, but the precise dynamics of this process are sensitive to the location and the orientation of the photosensitizer, which are very difficult to define in solution. To overcome this, ultrafast time-resolved infrared (TRIR) spectroscopy was performed on photoexcited ruthenium polypyridyl–DNA crystals, the atomic structure of which was determined by X-ray crystallography. By combining the X-ray and TRIR data we are able to define both the geometry of the reaction site and the rates of individual steps in a reversible photoinduced electron-transfer process. This allows us to propose an individual guanine as the reaction site and, intriguingly, reveals that the dynamics in the crystal state are quite similar to those observed in the solvent medium

Differential attraction and repulsion of Staphylococcus aureus and Pseudomonas aeruginosa on molecularly smooth titanium films

Magnetron sputtering techniques were used to prepare molecularly smooth titanium thin films possessing an average roughness between 0.18 nm and 0.52 nm over 5 μm × 5 μm AFM scanning areas. Films with an average roughness of 0.52 nm or lower were found to restrict the extent of P. aeruginosa cell attachment, with less than 0.5% of all available cells being retained on the surface. The attachment of S. aureus cells was also limited on films with an average surface roughness of 0.52 nm, however they exhibited a remarkable propensity for attachment on the nano-smoother 0.18 nm average surface roughness films, with the attachment density being almost twice as great as that observed on the nano-rougher film. The difference in attachment behaviour can be attributed to the difference in morphology of the rod-shaped P. aeruginosa compared to the spherical S. aureus cells

The Dirac form factor predicts the Pauli form factor in the Endpoint Model

We compute the momentum-transfer dependence of the proton Pauli form factor $F_{2}$ in the endpoint overlap model. We find the model correctly reproduces the scaling of the ratio of $F_{2}$ with the Dirac Form factor $F_{1}$ observed at the Jefferson Laboratory. The calculation uses the leading-power, leading twist Dirac structure of the quark light-cone wave function, and the same endpoint dependence previously determined from the Dirac form factor $F_{1}$. There are no parameters and no adjustable functions in the endpoint model's prediction for $F_{2}$. The model's predicted ratio $F_{2}(Q^{2})/F_{1}(Q^{2})$ is quite insensitive to the endpoint wave function, which explains why the observed ratio scales like $1/Q$ down to rather low momentum transfers. The endpoint model appears to be the only comprehensive model consistent with all form factor information as well as reproducing fixed-angle proton-proton scattering at large momentum transfer. Any one of the processes is capable of predicting the others.Comment: 12 pages, 3 figure

Gender Nonconformity During Adolescence:Links with Stigma, Sexual Minority Status, and Psychosocial Outcomes

Both gender nonconformity and sexual minority status during adolescence are associated with elevated levels of victimization and harassment, experiences that have serious consequences for adolescent psychosocial outcomes. While gender nonconformity and sexual minority status reflect separate constructs, they are associated because (1) sexual minority youth report higher levels of gender nonconformity and (2) gender nonconformity is frequently used to attribute sexual minority status by others. Following from classic stigma theory, the current chapter focuses on the role of gender nonconformity in explaining variation in social exclusion and victimization among both sexual minority and sexual majority youth. Of particular interest is the potential for gender nonconformity to mediate or moderate the association between sexual minority status and individual mental health and wellbeing outcomes. Gender differences will also be discussed, focusing on differences between girls and boys in the links between sexual minority status, gender nonconformity, experiences of victimization, and negative psychosocial outcomes. Additionally, the emerging literature on conceptualizing gender nonconformity among trans and non-binary youth will be addressed. Finally, the current chapter will finish with a discussion of how and why gender nonconformity must be taken into consideration in the development of programs aimed at reducing homophobia among adolescent populations

Early Staphylococcal Biofilm Formation on Solid Orthopaedic Implant Materials: In Vitro Study

Biofilms forming on the surface of biomaterials can cause intractable implant-related infections. Bacterial adherence and early biofilm formation are influenced by the type of biomaterial used and the physical characteristics of implant surface. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis, the main pathogen in implant-related infections, to form biofilms on the surface of the solid orthopaedic biomaterials, oxidized zirconium-niobium alloy, cobalt-chromium-molybdenum alloy (Co-Cr-Mo), titanium alloy (Ti-6Al-4V), commercially pure titanium (cp-Ti) and stainless steel. A bacterial suspension of Staphylococcus epidermidis strain RP62A (ATCC35984) was added to the surface of specimens and incubated. The stained biofilms were imaged with a digital optical microscope and the biofilm coverage rate (BCR) was calculated. The total amount of biofilm was determined with the crystal violet assay and the number of viable cells in the biofilm was counted using the plate count method. The BCR of all the biomaterials rose in proportion to culture duration. After culturing for 2-4 hours, the BCR was similar for all materials. However, after culturing for 6 hours, the BCR for Co-Cr-Mo alloy was significantly lower than for Ti-6Al-4V, cp-Ti and stainless steel (P0.05). These results suggest that surface properties, such as hydrophobicity or the low surface free energy of Co-Cr-Mo, may have some influence in inhibiting or delaying the two-dimensional expansion of biofilm on surfaces with a similar degree of smoothness