Provider of Last Resort: Lessons from the Insurance Industry

Among three general alternatives to setting up a provider of last resort, the reinsurance model is superior to assigned risk plans and joint underwriting associations in accomplishing universal service objectives. The electric industry needs to follow the insurance industry’s lead and move to this model.     

New magic numbers in the continent of isotopes

Recently, Lucas has explained that the magic numbers are really composites of several sub shells filling, rather than being single shells. In addition, his theory leads to the conclusion that protons and neutrons fill sub shells differently, because the protons tend to occupy outer shells first, while neutrons tend to occupy both outer and inner shells. Using a simple modification of Lucas’ geometrical packing scheme, new magic proton and neutron numbers were postulated for the superheavy nuclei, which matched the island of stability distribution to a large extent. These magic numbers were also tested against some nuclei in the peninsula of isotopes, and found to be relevant.Now, in consideration of a suggestion made many years ago by Linus Pauling, new magic numbers between 50 and 82 are postulated in the continent of isotopes, and compared to experimental data. These new numbers have strong support among the three elements considered by Pauling, namely Cadmium, Tin and Tellurium, and the results suggest that the range of isotopes found, their stability, and their lifetimes are strongly affected by the new magic numbers. In addition, if 58 nucleons are taken to be magic, then the double hump fission distribution for heavy isotopes may be explained semi-quantitatively.     

Do viral load and CD8 cell count at initiation of tritherapy influence the increase of CD4 T-cell count?

BACKGROUND: Tritherapies including protease inhibitors improve clinical status and usually increase CD4 T cell count. However, the dissociation between the marked decreases in viral load and the incomplete restoration of CD4 cell counts with a three-drug combination has been reported. We assessed this potential difference among our patients. METHODS: Patients were enrolled when a protease inhibitor was prescribed to them for the first time. Using a computerized medical record (ADDIS), we retrospectively assessed a potential relationship between the increase in CD4 T cells (deltaCD4) at M3, M6 and variables including sex, age, CDC staging, protease inhibitor, prior antiviral therapy, CD8 and viral load at baseline. We used Epi-Info 6.4 and BMDP software. RESULTS: Data were analyzed on 154 patients. The median CD4 T cell count was 157 at baseline, 215 at month 3 and 202 at month 6. The median viral load was 52000 copies at baseline, 530 at month 3 and 500 at month 6. In a univariate analysis, a significant relationship was found between deltaCD4 and CD8 at baseline. A statistically significant negative correlation appeared between the CD8 cell count at baseline and deltaCD4 at M6 (r=-0.28, Pearson). Moreover, we found that there also was a relationship between deltaCD4 and viral load at baseline. There was a correlation between deltaCD4 at M6 and the viral load at M0 (r=0.37, Pearson). In a multiple regression model, after CD8 count at baseline had been accounted for, we found a significant correlation between deltaCD4 and viral load at baseline (multiple r=0.33 at M3, and 0.40 at M6). CONCLUSIONS: Patients with a low viral load do not benefit from as great an increase in CD4 T cell count as others when they receive a tritherapy including protease inhibitors. These results suggest that another mechanism rather than direct viral pathogenicity leads to CD4 T cell destruction. This mechanism may not be efficiently stopped by antiviral therapy, especially protease inhibitors.     

Piezoelectric inkjet printing of medical adhesives and sealants

Piezoelectric inkjet printing is a noncontact process that enables microscale processing of biological materials. In this research summary, the use of piezoelectric inkjet printing for patterning medical adhesives and sealants, including a two-component polyethylene glycol hydrogel-based medical sealant, an N-butyl cyanoacrylate tissue adhesive, and a mussel adhesive protein biological adhesive, is described The effect of Fe(III) on mussel adhesive protein structure was evaluated by means of atomic force microscopy. The ability to process microscale patterns of medical sealants and adhesives will provide an improvement in tissue joining, including enhanced tissue integrity, reduced bond lines, and decreased adhesive toxicity. Piezoelectric inkjet deposition of medical adhesives and sealants may be used in wound closure, fracture fixation, and microscale vascular surgery.     

Synthesis of new polyethers derived from isoidide under phase‐transfer catalysis: Reactivity and selectivity under microwaves and classical heating

Microwave irradiation was applied to the synthesis of polyethers from 1,8‐dibromo‐ and 1,8‐dimesyl‐octane under solid–liquid phase‐transfer catalytic conditions. To evaluate the influence of microwaves on the reaction rates and polyether properties, we carried out the polymerization reactions under similar conventional conditions (oil bath) with the same temperature profiles. First, the microwave‐assisted syntheses proceeded more rapidly in comparison with conventional heating, and the reaction time was reduced from 24 h to 30 min with higher yields of polyethers. Second, the structure of the polymers strictly depended on the activation mode. Under microwave conditions, the polyethers were characterized by higher molecular weights with better homogeneity. Third, the mechanism of chain termination was different under microwave and conventional conditions. The polyethers prepared with conventional heating possessed shorter chains with mainly hydroxylated ends, whereas under microwave irradiation, the polymer chains were longer with mainly ethylenic group ends. In fact, under microwave irradiation, ethylenic group ends were formed rather rapidly and set up a hindrance to further polymer growth. In contrast, under conventional conditions terminations were essentially constituted by hydroxyl functions; however, further polymerization was terminated as well. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1255–1266, 2003     

Near Infrared Reflection Spectroscopy: A Versatile Tool for Rapid Characterization of Olefin Copolymers and High‐Throughput Experiments

Near infrared (NIR) spectroscopy was developed as a rapid analytical method for the determination of the composition of olefin copolymers obtained in high‐throughput screening. NIR spectra of ethene/propene and ethene/1‐hexene copolymers, also characterized by means of ¹³C NMR spectroscopy, were recorded and used to design multivariate calibration models. Different methods for the preprocessing of the spectra, including the linearization by non‐linear transformations, were compared. Optimal methods and error estimates were established using crossvalidation. This technique is of particular interest for the rapid on‐line analysis of high‐throughput experiments in the field of polymer and catalyst design employing methods from combinatorial chemistry.

Predicted versus true value of the propene incorporation and standard deviation for ethene/propene copolymers.     

Synthesis of polyurethane/polyethylene grafted polymers using cyclotriphosphazene as a coupling agent

The reaction between a dihydroxyphenoxycyclotriphosphazene containing allylic functions, 3, and hexamethylene‐1,6‐diisocyanate (HDI) leads to a new cyclotriphosphazene‐substituted polyurethane 4. The structures of both classes of compounds involved in that synthesis were investigated by ³¹P‐, ¹³C‐, and ¹H‐NMR, infrared, and mass spectrometries, size‐exclusion chromatography, and elemental analysis. The thermal behavior of 4 was investigated and compared to that of hexaphenoxycyclotriphosphazene, N₃P₃(OC₆H₅)₆, and of a polyurethane synthesized from 1,3‐bis(hydroxy)benzene and HDI. The free‐radical‐promoted grafting of 4 onto the polyethylene surface is described. The resultant surface was studied by ATR–IR, XPS, and contact‐angle techniques. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1925–1934, 2003     

Unveiling hermetic failure of ceramic tubes by digital image correlation and acoustic emission

A new, in situ hermeticity testing apparatus has been developed to allow helium leak evaluation of ceramic tubes, including nuclear-grade SiC/SiC fuel cladding ceramic matrix composites (CMC), during four-point bending with simultaneous monitoring of local deformation and damage, using stereoscopic digital image correlation (DIC) and acoustic emissions. The capabilities of the experimental apparatus are demonstrated using alumina, borosilicate glass, and 4130 steel tubes with representative cladding dimensions and then applied to study the deformation-hermeticity relationship of SiC/SiC CMCs. Results of three CMCs appear to indicate that matrix cracking occurs near the deviation from linearity strain at strains ranging from 0.04% to 0.06% and is shortly followed by an initial loss of gas tightness by 0.09% bending strain. Leaking increased in distinct steps over 0.1%-0.2% bending strain, and within this range, results indicate that prior to fiber fracture, it is likely possible to regain gas tightness upon unloading. This technique and uncovered hermetic failure behavior are intended to progress the standardization of a test methodology for nuclear reactor components and to begin to resolve the mechanisms controlling distinct steps of ceramic matrix composite failure.