Free-energy barrier to melting of single-chain polymer crystallite

We report Monte Carlo simulations of the melting of a single-polymer crystallite. We find that, unlike most atomic and molecular crystals, such crystallites can be heated appreciably above their melting temperature before they transform to the disordered "coil" state. The surface of the superheated crystallite is found to be disordered. The thickness of the disordered layer increases with superheating. However, the order-disorder transition is not gradual but sudden. Free-energy calculations reveal the presence of a large free-energy barrier to melting.Comment: AMS-Latex, 4 pages with 5 figures, submitted to Phys. Rev. Let

Lattice model study of the thermodynamic interplay of polymer crystallization and liquid-liquid demixing

We report Monte Carlo simulations of a lattice-polymer model that can account for both polymer crystallization and liquid-liquid demixing in solutions of semiflexible homopolymers. In our model, neighboring polymer segments can have isotropic interactions that affect demixing, and anisotropic interactions that are responsible for freezing. However, our simulations show that the isotropic interactions also have a noticeable effect on the freezing curve, as do the anisotropic interactions on demixing. As the relative strength of the isotropic interactions is reduced, the liquid-liquid demixing transition disappears below the freezing curve. A simple, extended Flory-Huggins theory accounts quite well for the phase behavior observed in the simulations.Comment: Revtex, 7 pages, the content accepted by J. Chem. Phy

A segmented Hybrid Photon Detector with integrated auto-triggering front-end electronics for a PET scanner

We describe the design, fabrication and test results of a segmented Hybrid Photon Detector with integrated auto-triggering front-end electronics. Both the photodetector and its VLSI readout electronics are custom designed and have been tailored to the requirements of a recently proposed novel geometrical concept of a Positron Emission Tomograph. Emphasis is put on the PET specific features of the device. The detector has been fabricated in the photocathode facility at CERN

Relationship between Dose, Factor IX Activity Levels and Bleeding Probability for rIX-FP Prophylaxis in Hemophilia B:A Repeated Time-to-Event Analysis

In hemophilia B, pharmacokinetic (PK)-guided dosing of extended half-life factor IX (EHL-FIX) concentrates can secure targeted FIX exposure. Target FIX activity levels in plasma should be individually set primarily taking bleeding tendency into account, alongside the presence of target joints, physical activity, and preferred dosing schedules. In other words, both PK and pharmacodynamics (PD) are relevant when individualizing therapy. Our objective was to examine the relationship between dose, FIX activity levels, and bleeding specifically for EHL-FIX concentrate recombinant fusion protein linking coagulation factor IX with albumin (rIX-FP). Data from hemophilia B patients with endogenous FIX activity level <= 2 IU/dL from five clinical trials were combined. Bleeding probability was described with a parametric repeated time-to-event (RTTE) model. Data included 2,493 FIX activity levels and 514 bleeds from 114 unique patients with a median age of 26 years (range: 1-61) followed for a median of 416 days (range: 6-1,233). Joints were the most frequent bleeding site (46%), and more than half of the bleeds were trauma-related (52%). Overall, 60% and 40% were categorized as damage-causing or nuisance bleeds, respectively. A baseline hazard of 7.3 bleeds per year was calculated when FIX activity levels were set at zero. The probability of all bleeding decreased by 50% when the FIX activity level was 12 IU/dL. Variability in bleeding hazard between individuals with similar FIX activity levels was substantial (182%). Simulations showed that targeting trough FIX activity levels to 20 IU/dL resulted in a median annual bleeding rate (ABR) of zero (range: 0-3)

Potential for improvement of docetaxel-based chemotherapy: a pharmacological review

Since the introduction of docetaxel, research has focused on various approaches to overcome treatment limitations and improve outcome. This review discusses the pharmacological attempts at treatment optimisation, which include reducing interindividual pharmacokinetic and pharmacodynamic variability, optimising schedule, route of administration, reversing drug resistance and the development of structurally related second-generation taxanes

Global atmospheric particle formation from CERN CLOUD measurements

Fundamental questions remain about the origin of newly formed atmospheric aerosol particles because data from laboratory measurements have been insufficient to build global models. In contrast, gas-phase chemistry models have been based on laboratory kinetics measurements for decades. Here we build a global model of aerosol formation using extensive laboratory-measured nucleation rates involving sulfuric acid, ammonia, ions and organic compounds. The simulations and a comparison with atmospheric observations show that nearly all nucleation throughout the present-day atmosphere involves ammonia or biogenic organic compounds in addition to sulfuric acid. A significant fraction of nucleation involves ions, but the relatively weak dependence on ion concentrations indicates that for the processes studied variations in cosmic ray intensity do not significantly affect climate via nucleation in the present-day atmosphere

Altered multisensory temporal integration in obesity

Eating is a multisensory behavior. The act of placing food in the mouth provides us with a variety of sensory information, including gustatory, olfactory, somatosensory, visual, and auditory. Evidence suggests altered eating behavior in obesity. Nonetheless, multisensory integration in obesity has been scantily investigated so far. Starting from this gap in the literature, we seek to provide the first comprehensive investigation of multisensory integration in obesity. Twenty male obese participants and twenty male healthy-weight participants took part in the study aimed at describing the multisensory temporal binding window (TBW). The TBW is defined as the range of stimulus onset asynchrony in which multiple sensory inputs have a high probability of being integrated. To investigate possible multisensory temporal processing deficits in obesity, we investigated performance in two multisensory audiovisual temporal tasks, namely simultaneity judgment and temporal order judgment. Results showed a wider TBW in obese participants as compared to healthy-weight controls. This holds true for both the simultaneity judgment and the temporal order judgment tasks. An explanatory hypothesis would regard the effect of metabolic alterations and low-grade inflammatory state, clinically observed in obesity, on the temporal organization of brain ongoing activity, which one of the neural mechanisms enabling multisensory integration