A rubber-modified thermoplastic where the morphology produced by phase-separation induced by polymerization disappears at high conversions

An unexpected experimental finding is reported where the primary morphology developed during polymerization-induced phase separation in a rubber-modified thermoplastic practically disappears at high conversions. This process was evidenced by light scattering (LS) and scanning electron microscopy (SEM) for a particular composition of solutions of polyisobutylene oligomers (PIB) in isobornylmethacrylate (IBoMA), during the free-radical polymerization of the monomer. The primary phase separation produced a dispersion of domains rich in PIB containing significant amounts of the monomer (IBoMA). Polymerization of the monomer in these domains occurred at high overall conversions producing the filling of dispersed domains with a PIBoMA-PIB blend that could not be distinguished from the matrix. Under these conditions the final material had the appearance of a homogeneous blend.     

Effects of urbanization on the aquatic fauna of the Line Creek watershed, Atlanta—a satellite perspective

Impervious surface area (ISA) was derived for a period from 1979 to 1997 from Landsat MSS and TM data for the Line Creek watershed that lies to the south of the city of Atlanta, GA. The change in ISA is presented as an ecological indicator to examine the cumulative water resource impacts on mussel population in three sub-watersheds of Line Creek—namely, Line, Flat, and Whitewater creeks. The satellite analysis shows that ISA expansion occurred substantially from 1987 to 1997 and is predominantly in industrial, commercial, and shopping center (ICS) complexes but also in smaller lot-size residential development. Evidence of mussel habitat degradation is indicated and loss of species (in the region of 50 to 70%) is present in areas where ISA expansion is observed—specifically in ICS complex development in and around Peachtree City that drains directly into the Line and Flat creeks. This is in marked contrast to Whitewater Creek where overall development of ISA is less and no major loss of mussel species is observed.     

Rectus abdominis muscle flap (RAMF) technique for the management of bladder exstrophies: late clinical outcome and urodynamic findings

OBJECTIVE: To investigate the efficacy of the rectus abdominis muscle flap (RAMF) technique for the closure and augmentation of small, non-compliant bladder exstrophies. PATIENTS AND METHODS: The RAMF technique was used in two girls and two boys (mean age at operation, 31.7 months, range 3-72) with bladder exstrophy. The clinical outcome and urodynamics were assessed during a follow-up of 29 months to 6 years (mean 49.2 months) and included imaging, cystoscopy, biochemical and microbiological studies. RESULTS: There were no urinary tract infections, metabolic problems or electrolyte disturbances and kidney function remained normal in all patients. Radiography confirmed intact function and anatomy of the urinary tract and cystoscopy showed complete coverage of the inner peritoneal layer of RAMF with uroepithelium. No stone formation or mucus production were detected. Currently, three patients void using clean intermittent catheterization through the native urethra and the fourth through an appendiceal Mitrofanoff valve. However, the bladder volume was insufficient at the late follow-up and three patients required bladder augmentation. CONCLUSIONS: The RAMF technique is a good alternative for closing bladder exstrophies and achieves an increase in bladder capacity; however, although there is a mild improvement in bladder capacity and compliance. RAMF should not be used as a bladder augmentation procedure. The technique is indicated in the closure of large bladder defects, bladder exstrophies with small, inelastic, non-compliant bladder remnants and failed primary closures.     

Bone marrow and renal injury associated with haloalkene cysteine conjugates in calves

Almost 40 years ago, it was reported that cattle-feed which had been extracted with hot trichloroethylene and then fed to calves produced renal injury and a fatal aplastic anaemia. The toxic factor was subsequently identified as S-(1,2-dichlorovinyl)-L-cysteine (DCVC). These original findings have been confirmed, a single intravenous dose of DCVC at 4 mg/kg, or 0.4 mg/kg intravenously per day administered for 10 days to calves produced aplastic anaemia, and renal injury after a single dose of 4 mg/kg. The toxicity to calves of a number of other haloalkene cysteine conjugates has been examined to ascertain whether, like DCVC, they produce bone marrow and renal injury. Intravenous administration of the N-acetyl cysteine conjugate of DCVC produced renal but not bone marrow injury at a molar equivalent dose to DCVC, indicating that the calf can deacetylate the mercapturic acid and further that sufficient chemical had reached the kidney to be a substrate for the enzyme cysteine conjugate beta-lyase. However, intravenous administration of the alpha-methyl analogue of DCVC, which cannot undergo metabolism via the enzyme cysteine conjugate beta-lyase, was without toxicity at doses about five-fold higher than DCVC. These latter findings provide strong evidence that metabolism of DCVC via the enzyme beta-lyase is necessary for bone marrow and renal injury to occur. The cysteine conjugates of perchloroethylene and hexachloro-1,3-butadiene(HCBD) when given intravenously to calves at molar equivalent doses to DCVC, or above, did not produce either bone marrow or renal injury. In contrast, intravenous administration of the cysteine conjugate of tetrafluoroethylene (TFEC) produced severe renal tubular injury in calves without affecting the bone marrow. In vitro studies with these haloalkene cysteine conjugates showed, like DCVC, that they were good substrates for calf renal cysteine conjugate beta-lyase and toxic to renal cells as judged by their ability to reduce organic anion and cation transport by slices of calf renal cortex and inhibit the renal enzyme glutathione reductase. Calves were also dosed either orally or intravenously with HCBD to assess its toxicity. HCBD at higher molar equivalent doses than DCVC produced mid-zonal necrosis in the liver, renal tubular necrosis but no bone marrow injury in calves. The key findings emerging from these studies are (1) that none of the other cysteine conjugates, at molar equivalent doses to DCVC and above, produce bone marrow injury in calves, (2) TFEC produced only renal injury, suggesting that sufficient of the other conjugates had not reached the kidney for metabolism by beta-lyase to produce cytotoxicity and (3) that HCBD itself is more toxic than its cysteine or mercapturic acid conjugate, suggesting that pharmaco-kinetics and disposition are important factors in determining the toxicity of these conjugates to calves. Further studies are needed to understand the basis for the selective toxicity of DCVC to the bone marrow of calves.     

The parallel complexity of scheduling with precedence constraints

We study the problem of parallel computation of a schedule for a system of n unit-length tasks on m identical machines, when the tasks are related by a set of precedence constraints. We present NC algorithms for computing an optimal schedule in the case where m, the number of available machines, does not vary with time and the precedence constraints are represented by a collection of outtrees. The algorithms run on an exclusive read, exclusive write (EREW) PRAM. Their complexities are O(log n) and O((log n)²) parallel time using O(n²) and O(n) processors, respectively. The schedule computed by our algorithms is a height-priority schedule. As a complementary result we show that it is very unlikely that computing such a schedule is in NC when any of the above conditions is significantly relaxed. We prove that the problem is P-complete under logspace reductions when the precedence constraints are a collection of intrees and outtrees, or for a collection of outtrees when the number of available machines is allowed to increase with time. The time span of a height-priority schedule for an arbitrary precedence constraints graph is at most 2 − 1/(m − 1) times longer than the optimal (N. E Chen and C. L. Liu, Proc. 1974 Sagamore Computer Conference on Parallel Processing, T. Fend (Ed.), Springer-Verlag, Berlin, 1975, pp. 1–16). Whereas it is P-complete to produce the classical height-priority schedules even for very restricted precedence constraints graphs, we present a simple NC parallel algorithm which produces a different schedule that is only 2 − 1/m times the optimal.     

Individual differences in vulnerability to inescapable shock in rats.

The present study determined whether individual differences in neophobia during an open-field pretest predict vulnerability to inescapable electric shock, as measured by 2 tests of learned helplessness in rats. Shuttle-escape latencies and saccharin finickiness increased across groups that had received increasing numbers of inescapable shocks 24 hr earlier. Dispersion in the test measure as well as the percentage of variance explained by pretest neophobia were greater when no or few shocks were delivered in the interpolated stress phase. Pretest neophobia was positively related to stress vulnerability in both tests under these conditions. Further increments in stressor severity overwhelmed even the most stress-resistant rats, thereby decreasing dispersion in the test measure and eliminating the predictive value of pretest neophobia. This pattern of outcomes was more robust for the shuttle-escape measure of helplessness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Blends of poly(vinyl chloride) with plasticized polyaniline

A series of poly(vinyl chloride) (PVC)/polyaniline (PANI) blends plasticized and protonated simulataneously by bis(2-ethylhexyl) hydrogen phosphate, bis(4-nitrophenyl) phosphate, diphenyl phosphate, or dibenzyl phosphate was prepared by a mass homogenization technique. Thermal analysis studies by means of thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed that PVC/PANI blends with bis(2-ethylhexyl) hydrogen phosphate were characterized by the highest thermal stability values. Kinetic analysis of the decomposition process by the isoconversional Friedman method showed that the activation energy did not change substantially over the broad conversion range; further advanced kinetic analysis by a nonlinear regression method revealed that the kinetic function that was the best approximation for the experimental data was based on a reaction of nth order.     

"I Buy American": The American Image as Reflected in Israeli Advertising

Analysis of advertisements in Israeli newspapers over the past decade has shown that American symbols have been widely used to market an array of consumer goods. Products made in America, Israel, or other countries are marketed with some sort of American angle by invoking America's values, symbols, landscapes, or lifestyle. Using both qualitative and quantitative methods, we analyzed how central components of the nation-state/national sphere—language, flag, political leaders, borders, landscapes, and sights—are reflected in advertising. We attempt to show how social values metamorphose, shedding their "Israeliness" and taking on an American veneer. Using Israel as an example may provide a test case for the Americanization process in other societies at the turn of the millennium.     

Outcome of different treatment mixes in a multidimensional neuropsychological rehabilitation program.

Within a clinical demonstration program, 59 traumatically brain-injured patients were treated with 1 of 3 mixes of treatment. Mix 1 included cognitive remediation (CGR), small-group interpersonal (SGI) communication training, therapeutic community activities, and personal counseling. Mix 2 was similar to Mix 1 but stressed SGI exercises and eliminated CGR. Mix 3 emphasized CGR and eliminated SGI exercises. The efficacy of the treatment mixes was evaluated with performance on neuropsychological tests, improved independence in functional activities, measures of intra- and interpersonal functioning, and vocational outcome. Ss' participation in the program, irrespective of treatment mix, yielded improvements in (1) self-image, (2) quality of interpersonal relatedness and interaction, (3) involvement with others in naturalistic settings, and (4) vocational outcome. Overall, data point to the superiority of the balanced mix (Mix 1) over Mixes 2 and 3. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstress estimate of stochastically heterogeneous structures by the functional perturbation method: A one dimensional example

A new functional perturbation method (FPM) for calculating the probabilistic response of stochastically heterogeneous, linear elastic structures is developed. The method is based on treating the governing differential operator as well as the unknown displacement function as a functional of material modulus field. By executing a functional perturbation around the homogeneous case, a set of successive differential equations is obtained and solved, from which the average and variance of any local parameter (displacements, stresses, strains) can be found. For a linear problem, the equations to be solved in each approximation order differ from the one for the homogeneous case by a pseudo external loading (right hand side) part only. Thus, only the Green function for the homogeneous case is needed for an analytical solution of the corresponding heterogeneous problem. A one dimensional stochastically heterogeneous rod embedded in a uniform shear resistant elastic medium is solved as an example. The statistical variance of displacements and stresses are found analytically, including the edge regions. Morphological (grain size) and material (modulus) effects on the stochastic response are demonstrated. The above results are essential for estimating the stochastic features of local stress concentrations, which are the source for many strength-related macro properties of materials. Extensive usage of generalized functions (Dirac operator and its derivatives) is needed for the analysis.