Hot Glue Gun Releasing Biocompatible Tissue Adhesive

Tissue bioadhesives are widely used in dermatology, surgery rooms, and in the field. Despite their advantages over sutures and staples, currently available tissue glues are limited by their mechanical properties and toxicity. Here, a new approach is described for wound closure that is based on a biocompatible, low melting point four‐armed N‐hydroxy succinimide‐modified polycaprolactone (star‐PCL‐NHS). Star‐PCL‐NHS is inserted into a hot melt glue gun, melts upon minimal pressure, and is extruded directly onto the wound, where it solidifies, bonding strongly with both edges of the wound. Changes in molecular weight allow control of adhesive strength, melting point, and elasticity properties. In vitro and in vivo evaluations confirm the biocompatibility of this system. The straightforward synthetic scheme and the simple delivery method, combined with the desirable mechanical properties, tunability, and tissue compatibility, are desirable traits in wound management.     

Scheduling multipacket frames with frame deadlines

We consider scheduling information units called frames, each with a delivery deadline. Frames consist of packets, which arrive online in a roughly periodic fashion, and compete on allocation of transmission slots. A frame is deemed useful only if all its packets are delivered before its deadline. We focus on a “proportional” variant, where the value of each frame is proportional to its size, but the sizes and periods of the frames are arbitrary. We give a constant-competitive algorithm for this setting, assuming bounded jitter and some slack in the frames’ deadlines, the latter of which is necessary. Using standard techniques, our algorithm yields polylog-competitive algorithms for general instances with slack and bounded jitter.     

On the Galerkin/Finite-Element Method for the Serre Equations

A highly accurate numerical scheme is presented for the Serre system of partial differential equations, which models the propagation of dispersive shallow water waves in the fully-nonlinear regime. The fully-discrete scheme utilizes the Galerkin / finite-element method based on smooth periodic splines in space, and an explicit fourth-order Runge–Kutta method in time. Computations compared with exact solitary and cnoidal wave solutions show that the scheme achieves the optimal orders of accuracy in space and time. These computations also show that the stability of this scheme does not impose very restrictive conditions on the temporal stepsize. In addition, solitary, cnoidal, and dispersive shock waves are studied in detail using this numerical scheme for the Serre system and compared with the ‘classical’ Boussinesq system for small-amplitude shallow water waves. The results show that the interaction of solitary waves in the Serre system is more inelastic. The efficacy of the numerical scheme for modeling dispersive shocks is shown by comparison with asymptotic results. These results have application to the modeling of shallow water waves of intermediate or large amplitude.     

Determination of robotic melon harvesting efficiency: a probabilistic approach

To automate the harvesting of melons, a mobile Cartesian robot is developed that traverses at a constant velocity over a row of precut melons whose global coordinates are known. The motion planner is programmed to have the robot harvest as many melons as possible. Numerous simulations of the robot over a field with different sets of randomly distributed melons resulted in nearly identical percentages of melons harvested. This result holds true over a wide range of robot dimensions, motor capabilities, velocities and melon distributions. Using probabilistic methods, we derive these results by modelling the robotic harvesting procedure as a stochastic process. In this simplified model, a harvest ratio is predicted analytically using Poisson and geometric distributions. Further analysis demonstrates that this model of robotic harvesting is an example of an infinite length Markov chain. Applying the mathematical tools of Markov processes to our model yields a formula for the harvest percentage that is in strong agreement with the results of the simulation. The significance of the approach is demonstrated in two of its applications: to select the most efficient actuators for maximal melon harvesting and determine the set of optimal velocities along a row of melons of varying densities.     

Arrest trajectories of adult offenders with a serious mental illness.

We examined patterns and correlates of arrest/re-arrests among offenders with a serious mental illness over a 4-year period. County criminal justice records and health and social service datasets were used to identify and describe inmates jailed in Pinellas County, Florida, between 7/03 and 6/04. A total of 3,769 participants (10.1% of arrestees) had a serious mental illness. Participants averaged 4.6 arrests (SD = 3.9, median = 4) and 150.6 days in jail (SD = 175.0, median = 90).Working from the trajectories of offending theory and literature we used latent class growth analysis to identify three classes of offenders with consistent numbers of arrests over a 4-year period and nearly parallel arrest trajectories; a sporadic arrest class (n = 469) with minimal arrests, a low arrest chronic class (n = 3,090, about one arrest/year); and a high arrest chronic class (n = 210, about four arrests/year). Analysis of arrests by age group within each of the classes suggested that for the low and high arrest chronic classes arrest rates persist throughout adult life. In multinomial logistic regression, homelessness, a co-occurring substance abuse diagnosis, fewer mental health outpatient service contacts and more mental health emergency room/inpatient contacts were associated with being in a class with more arrests. Arrests among offenders with a serious mental illness appear to be unusually high, to be firmly established in late adolescence and to persist over time. Successful strategies to reduce the arrest rates of this population must address the needs of these offenders early in their criminal careers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Screening the Incorporation of Amino Acids into an Inorganic Crystalline Host: the Case of Calcite

Organisms have the ability to produce structures with superior characteristics as in the course of biomineralization. One of the most intriguing characteristics of biominerals is the existence of intracrystalline macromolecules. Despite several studies over the last two decades and efforts to mimic the incoporation of macromolecules synthetically, a fundamental understanding of the mechanism of incorporation is as yet lacking. For example, which of the common 20 amino acids are really responsible for the interaction with the mineral phase? Here a reductionist approach, based on high‐resolution synchrotron powder diffraction and analytical chemistry, is utilized to screen all of these amino acids in terms of their incorporation into calcite. We showed that the important factors are amino‐acid charge, size, rigidity and the relative pKa of the carboxyl and amino functional groups. It is also demonstrated that cysteine, surprisingly, interacts very strongly with the mineral phase and therefore, like acidic amino acids, becomes richly incorporated. The insights gained from this study shed new light on the incorporation of organic molecules into an inorganic host in general, and in particular on the biomineralization process.     

预促进不饱和聚酯树脂的研究

本文研究了不同氢醌含量、不同钻用量下，Ｃｏ—ＣＤＥ—ＴＡＥ三组分预促进剂的最佳协同量及其对不饱和聚酯树脂固化特性、贮存稳定性等性能的影响。