Which Way Was I Going? Contextual Retrieval Supports the Disambiguation of Well Learned Overlapping Navigational Routes

Groundbreaking research in animals has demonstrated that the hippocampus contains neurons that distinguish betweenoverlapping navigational trajectories. These hippocampal neurons respond selectively to the context of specific episodes despite interference from overlapping memory representations. The present study used functional magnetic resonanceimaging in humans to examine the role of the hippocampus and related structures when participants need to retrievecontextual information to navigate well learned spatial sequences that share common elements. Participants were trained outside the scanner to navigate through 12 virtual mazes from a ground-level first-person perspective. Six of the 12 mazes shared overlapping components. Overlapping mazes began and ended at distinct locations, but converged in the middle to share some hallways with another maze. Non-overlapping mazes did not share any hallways with any other maze. Successful navigation through the overlapping hallways required the retrieval of contextual information relevant to thecurrent navigational episode. Results revealed greater activation during the successful navigation of the overlapping mazes compared with the non-overlapping mazes in regions typically associated with spatial and episodic memory, including thehippocampus, parahippocampal cortex, and orbitofrontal cortex. When combined with previous research, the current findings suggest that an anatomically integrated system including the hippocampus, parahippocampal cortex, and orbitofrontal cortexis critical for the contextually dependent retrieval of well learned overlapping navigational routes

Nonmedical Limits in Individual Life Insurance

This paper shows data that illustrate the substantial variation among nonmedical schedules and the dramatic increase in their amount limits from 1972 through 1992. Coefficients of variation are analyzed for several data subsets. We find that the variation of schedules in the sample of all firms has increased throughout the 1972-1992 period for issue ages up to 30, but has declined for issue ages beyond 30 during the 1982-1992 period. For the non-New York and stock companies our statistical tests indicate an increase in the variability of schedules over the full period 1972 to 1992

Novel audio lures to improve interaction and encounter rates of possums (Trichosurus vulpecula) with control methods in New Zealand

The brushtail possum (Trichosurus vulpecula), a marsupial native to Australia, was widely introduced in both the North and South Islands of New Zealand between 1890 and 1930 to support the fur industry that was booming in Australia at the time. Possums were one of the many mammalian species that humans introduced when they discovered and settled in New Zealand. Before the settlement of humans in New Zealand, there were no terrestrial mammals; therefore, the local species evolved in the absence of mammalian predators. This resulted in native species populations falling at alarming rates and possibly facing extinction due to numerous predators and species that had not been intended to coexist alongside one another. The government's initiative to reduce New Zealand's predators (possums, rats, and stoats) by 2050 has significantly expanded efforts to eliminate these pest mammals in recent years. Managing these pest mammal populations is crucial to protect the native bird, reptile, and invertebrate species. In New Zealand, predator control has been practiced for a long time, but what started with simple trapping has since developed into a thriving industry full of expertise to boost the efficiency of trapping and toxins, including species-specific attractants. The number of traps and bait stations needed to be set up and the associated labour and expense would be significantly reduced if animals could be reliably drawn from a distance to a bait station or trap. Any sound played to encourage or discourage interaction with a control tool/area is known as an audio lure. This research aims to identify if audio lures can significantly increase possum encounter and interaction rates of control devices and establish an audio lure tool that is durable, easy to use, and cost-effective for the wider public to use. Preliminary captive trials found that an aggressive possum sound is significantly more attractive to possums than an alarmed possum sound, a beeping sound, or a control (no sound). Preliminary field trials have found that the audio lure being developed performs similarly to an already established audio lure included as part of the Cacophony Project Thermal Camera. The price point of the audio lure being developed is around $250 (NZD) and should last 30 days in the field. At the conference, I will present the final captive trial results and more field trial research. The field trial research will investigate encounter and interaction rates of possums feeding in live-capture traps with and without audio lures. I will also, report the final audio lure costings and field life before servicing is required

A statistical model with a standard Gamma distribution

We study a statistical model consisting of $N$ basic units which interact with each other by exchanging a physical entity, according to a given microscopic random law, depending on a parameter $\lambda$. We focus on the equilibrium or stationary distribution of the entity exchanged and verify through numerical fitting of the simulation data that the final form of the equilibrium distribution is that of a standard Gamma distribution. The model can be interpreted as a simple closed economy in which economic agents trade money and a saving criterion is fixed by the saving propensity $\lambda$. Alternatively, from the nature of the equilibrium distribution, we show that the model can also be interpreted as a perfect gas at an effective temperature $T(\lambda)$, where particles exchange energy in a space with an effective dimension $D(\lambda)$.Comment: 5 pages, including 4 figures. Uses REVTeX styl

Regioselective and stoichiometrically controlled conjugation of photodynamic sensitizers to a HER2 targeting antibody fragment

The rapidly increasing interest in the synthesis of antibody–drug conjugates as powerful targeted anticancer agents demonstrates the growing appreciation of the power of antibodies and antibody fragments as highly selective targeting moieties. This targeting ability is of particular interest in the area of photodynamic therapy, as the applicability of current clinical photosensitizers is limited by their relatively poor accumulation in target tissue in comparison to healthy tissue. Although synthesis of porphyrin–antibody conjugates has been previously demonstrated, existing work in this area has been hindered by the limitations of conventional antibody conjugation methods. This work describes the attachment of azide-functionalized, water-soluble porphyrins to a tratuzumab Fab fragment via a novel conjugation methodology. This method allows for the synthesis of a homogeneous product without the loss of structural stability associated with conventional methods of disulfide modification. Biological evaluation of the synthesized conjugates demonstrates excellent selectivity for a HER2 positive cell line over the control, with no dark toxicity observed in either case

Viscous Torque and Dissipation in the Inner Region of a Thin Accretion Disk: Implications for Measuring Black Hole Spin

We consider a simple Newtonian model of a steady accretion disk around a black hole. The model is based on height-integrated hydrodynamic equations, alpha-viscosity, and a pseudo-Newtonian potential that results in an innermost stable circular orbit (ISCO) that closely approximates the one predicted by GR. We find that the hydrodynamic models exhibit increasing deviations from the standard disk model of Shakura & Sunyaev as disk thickness H/R or the value of alpha increases. The latter is an analytical model in which the viscous torque is assumed to vanish at the ISCO. We consider the implications of the results for attempts to estimate black hole spin by using the standard disk model to fit continuum spectra of black hole accretion disks. We find that the error in the spin estimate is quite modest so long as H/R < 0.1 and alpha < 0.2. At worst the error in the estimated value of the spin parameter is 0.1 for a non-spinning black hole; the error is much less for a rapidly spinning hole. We also consider the density and disk thickness contrast between the gas in the disk and that inside the ISCO. The contrast needs to be large if black hole spin is to be successfully estimated by fitting the relativistically-broadened X-ray line profile of fluorescent iron emission from reflection off an accretion disk. In our hydrodynamic models, the contrast in density and thickness is low when H/R>0.1, sugesting that the iron line technique may be most reliable in extemely thin disks. We caution that these results have been obtained with a viscous hydrodynamic model and need to be confirmed with MHD simulations of radiatively cooled thin disks.Comment: 32 pages, 10 figures; accepted by Ap

Prewetting transitions of Ar and Ne on alkali metal surfaces

We have studied by means of Density-Functional calculations the wetting properties of Ar and Ne adsorbed on a plane whose adsorption properties simulate the Li and Na surfaces. We use reliable ab-initio potentials to model the gas-substrate interactions. Evidence for prewetting transitions is found for all the systems investigated and their wetting phase diagrams are calculated.Comment: 6 pages, 8 figures, submitted for publication in Phys. Rev.

In vivo cranial bone strain and bite force in the agamid lizard Uromastyx geyri

In vivo bone strain data are the most direct evidence of deformation and strain regimes in the vertebrate cranium during feeding and can provide important insights into skull morphology. Strain data have been collected during feeding across a wide range of mammals; in contrast, in vivo cranial bone strain data have been collected from few sauropsid taxa. Here we present bone strain data recorded from the jugal of the herbivorous agamid lizard Uromastyx geyri along with simultaneously recorded bite force. Principal and shear strain magnitudes in Uromastyx geyri were lower than cranial bone strains recorded in Alligator mississippiensis, but higher than those reported from herbivorous mammals. Our results suggest that variations in principal strain orientations in the facial skeleton are largely due to differences in feeding behavior and bite location, whereas food type has little impact on strain orientations. Furthermore, mean principal strain orientations differ between male and female Uromastyx during feeding, potentially because of sexual dimorphism in skull morphology