Growth and claw regeneration of the stone crab, Menippe mercenaria

Savage, T. and J.R. Sullivan. 1978. Growth and Claw Regeneration of the Stone Crab, Menippe mercenaria. Fla. Mar. Res. Publ. No. 32.23 pp. Laboratory-maintained and feral crabs were observed for incremental carapace width and major and minor claw growth. Morphometric relationships for male and female carapace width against length and carapace width against major and minor claw sizes were derived. Only slopes of carapace width us. female major and male minor claws were not significantly different at the 95% confidence level. Feral normal male incremental growth exceeded that of normal females for all parameters. Normal laboratory females possessed greater average carapace width growth but less claw growth than did their male counterparts. All laboratory growth was more uniform but incrementally smaller than corresponding field growth. A hypothetical growth plot constructed from incremental growth of several crabs indicated ages at attainment of sexual maturity and legal size to be 10 and 30 months. A pictorial description of stone crab claw regeneration is presented. Minor claws realized greater regeneration after one and two molts (73.5% and 96.5% of pre-autotomized sizes) than did major claws (68.6% and 89.0%). Intermolt interval of laboratory crabs increased with larger carapace width sizes. Claw loss shortened or lengthened duration of the intermolt period depending upon whether the claw was removed shortly after a molt or later in the cycle. (Document has 27 pages.

Advantageous selection in private health insurance: The case of Australia

When consumers have private information about risk of suffering a loss, or equivalently, if insurers are prohibited from using observable information on risk in underwriting, theoretical models of insurance predict adverse selection. Yet the most common finding in empirical studies is that of no positive correlation between risk and insurance coverage. This is found for different types of insurance (e.g. car, health, life) and in different countries (e.g. France, US, UK, Israel) suggesting a fundamental relationship involving private information and consumer preferences. In this paper, we investigate the nature of risk selection in the Australian market for private health insurance in which community rated private health insurance complements a universal public health care system. We use National Health Survey data on hospital utilisation and individual characteristics to construct an empirical analogue for the risk variable in the Rothschild and Stiglitz model. Estimating the relationship between insurance and risk semi-parametrically, we find robust evidence of favourable selection. To explore the extent to which underlying risk preferences rather than risk drives the decision to purchase health insurance, we use Household Expenditure Survey data to model decisions to purchase a range of insurance products (health, life, accident, home, car) and to engage in risky behaviours (smoking and various forms of gambling). Correlations between residuals in the model suggest that advantageous selection is driven by risk aversion, which theoretical models do not typically capture.health insurance, adverse selection, Australia

Tailoring Thermoresponsive Poly(N-Isopropylacrylamide) Toward Sensing Perfluoroalkyl Acids

Widespread distribution of poly- and perfluoroalkyl substances (PFAS) in the environment combined with concerns for their potentially negative health effects has motivated regulators to establish strict standards for their surveillance. The United States Environmental Protection Agency issued a cumulative domestic threshold of 70 ppt for water supplies, and this bar is even lower in some local districts and other countries. Monitoring PFAS consequently requires sensitive analytical equipment to meet regulatory specifications, and liquid chromatography with tandem mass spectroscopy (LC/MS/MS) is the most common technique used to satisfy these requirements. Though extremely sensitive, the instrument is often burdened by pretreatment regimens, sedentation, and user proficiency barriers that encumber or limit its effectiveness. As an alternative, polymeric strategies for detecting PFAS are promising candidates for funneling recognition, transduction, and receptor elements into a single sensing platform to overcome some of the hurdles affecting LC/MS/MS. Toward this end, poly(N-isopropylacrylamide) (PNIPAM), an extensively studied thermoresponsive polymer, is a hydrogel with tailorable swelling properties dependent upon its polymeric composition and surrounding media. This polymer holds a lower critical solution temperature (LCST) around 32 °C that marks its transition from a relatively hydrophilic, swollen state to a hydrophobic, collapsed state once heated, and prior research indicates that surfactants such as sodium dodecyl sulfate can heavily influence the temperature at which this transition occurs and the ultimate swelling ratio for crosslinked hydrogels. Two particularly concerning fluorosurfactants, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), were hypothesized to act similarly to their non-fluorinated analogs by augmenting the swelling of PNIPAM in a dose-dependent manner. The effect of these fluoropollutants on PNIPAM was therefore studied to identify 1) if PFOS and PFOA would have an appreciable effect on the swelling behavior of varying PNIPAM morphologies, 2) if the swelling response could be enhanced by adding functional comonomers into the PNIPAM backbone, and 3) if the swelling behavior could be outfitted with Förster resonance energy transfer (FRET)-compatible dyes to signal the contaminants’ concentration. As such, crosslinked PNIPAM hydrogels were functionalized with fluorinated comonomers to induce fluorine-fluorine attraction amongst the polymers and their analytes to strengthen their recognition capability and microgels were equipped with FRET-capable dyes to achieve a fluorescent transduction motif indicative of the contaminants’ presence. Results indicated that PFOS augments the swelling of PNIPAM hydrogels significantly while PFOA causes microgels to collapse at temperatures below their innate LCST. FRET primarily replicated swelling observations as expected for the distance-mediated fluorescent phenomenon. Though the fluoropollutants generated appreciable swelling perturbations at concentrations within the micromolar range, additional functionalization is necessary to exploit the molecular-level interactions between PNIPAM and target fluorosurfactants to yield detection limits within the range needed for environmental applications

Two-Nucleon Systems in a Finite Volume: (II) 3S1-3D1 Coupled Channels and the Deuteron

The energy spectra of two nucleons in a cubic volume provide access to the two phase shifts and one mixing angle that define the S-matrix in the 3S1-3D1 coupled channels containing the deuteron. With the aid of recently derived energy quantization conditions for such systems, and the known scattering parameters, these spectra are predicted for a range of volumes. It is found that extractions of the infinite-volume deuteron binding energy and leading scattering parameters, including the S-D mixing angle at the deuteron pole, are possible from Lattice QCD calculations of two-nucleon systems with boosts of |P| <= 2pi sqrt{3}/L in volumes with 10 fm <~ L <~ 14 fm. The viability of extracting the asymptotic D/S ratio of the deuteron wavefunction from Lattice QCD calculations is discussed.Comment: 31 pages, 17 figure

Two-Baryon Systems with Twisted Boundary Conditions

We explore the use of twisted boundary conditions in extracting the nucleon mass and the binding energy of two-baryon systems, such as the deuteron, from Lattice QCD calculations. Averaging the results of calculations performed with periodic and anti-periodic boundary conditions imposed upon the light-quark fields, or other pair-wise averages, improves the volume dependence of the deuteron binding energy from ~exp(-kappa*L)/L to ~exp(-sqrt(2)kappa*L)/L. However, a twist angle of pi/2 in each of the spatial directions improves the volume dependence from ~exp(-kappa*L)/L to ~exp(-2kappa*L)/L. Twist averaging the binding energy with a random sampling of twist angles improves the volume dependence from ~exp^(-kappa*L)/L to ~exp(-2kappa*L)/L, but with a standard deviation of ~exp(-kappa*L)/L, introducing a signal-to-noise issue in modest lattice volumes. Using the experimentally determined phase shifts and mixing angles, we determine the expected energies of the deuteron states over a range of cubic lattice volumes for a selection of twisted boundary conditions.Comment: 20 pages, 3 figure

Thomas Savage Correspondence

Entry is a book review newspaper clipping with a photographic image of Thomas and Betty Savage in their Indian Point, Georgetown, Maine, home with biographical information about the couple and Tom Savage\u27s descriptive, playful quotes

Systematic Power Counting in Cutoff Effective Field Theories for Nucleon-Nucleon Interactions and the Equivalence With PDS

An analytic expression for the ${}^1S_0$ phase shifts in nucleon-nucleon scattering is derived in the context of the Schr\"odinger equation in configuration space with a short distance cutoff and with a consistent power counting scheme including pionic effects. The scheme treats the pion mass and the inverse scattering length over the intrinsic short distance scale as small parameters. Working at next-to-leading order in this scheme, we show that the expression obtained is identical to one obtained using the recently introduced PDS approach which is based on dimensional regularization with a novel subtraction scheme. This strongly supports the conjecture that the schemes are equivalent provided one works to the same order in the power counting.Comment: 6 pages; replaced version has corrected typos (We thank Mike Birse for pointing them out to u