Femorodistal vein grafts: the utility of graft surveillance criteria

PURPOSE: This retrospective review of femorodistal vein grafts was analyzed to determine the usefulness of various graft surveillance criteria. METHOD: The surveillance schedule involved evaluations at 1 month, every 3 months the first year, and then every 6 months. Salvage intervention or graft occlusion occurring within the next follow-up interval defined surveillance end points. One hundred two grafts (329 surveillance visits) had an ankle/brachial index (ABI). A duplex scanning-determined midgraft peak systolic flow velocity (PSFV) was available for 81 grafts (262 visits). Forty-eight grafts (137 visits) had both a PSFV and entire graft duplex scanning (EGDS) to determine stenosis greater than 50%, whereas 40 grafts (91 visits) had simultaneous ABI and EGDS. RESULTS: When a greater than 15% decrease in ABI denoted an abnormal surveillance study result, a positive predictive value (PPV) of 24.3% and negative predictive value of 94.5% were noted. Similarly, a PSFV cutoff of less than 35 cm/sec demonstrated values of 26.3% and 94.2%, respectively. When an EGDS of greater than 50% stenosis or a PSFV of less than 35 cm/sec were the cutoff criteria, the PPV was 36.7% and negative predictive value 99.1%, whereas characterizing abnormal results further with ABI (> 15% decreases) increased the PPV to 83.3%. CONCLUSION: The combination of an EGDS, midgraft PSFV, and ABI provides optimal follow-up for our patients with a femorodistal vein graft.     

Meta-analyses of age–cognition relations in adulthood: Estimates of linear and nonlinear age effects and structural models.

A meta-analysis was conducted on 91 studies to derive a correlation matrix for adult age, speed of processing, primary–working memory, episodic memory, reasoning, and spatial ability. Structural equation modeling with a single latent common cognitive factor showed that all cognitive measures shared substantial portions of age-related variance. A mediational model revealed that speed of processing and primary–working memory appear to be important mediators of age-related differences in the other measures. However, not all of the age-related influences were mediated. An examination of quadratic age effects and correlational patterns for subsamples under and over 50 years of age revealed that (a) negative age–cognition relations were significant for the 18- to 50-year-old sample and (b) the age-related decline accelerated significantly over the adult life span for variables assessing speed, reasoning, and episodic memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A method to estimate local deposition conditions using film profiles in features

A method to estimate the local partial pressures and temperature during low pressure chemical vapor deposition (LPCVD) proceses using film profile data is demonstrated using the chemistry of blanket tungsten deposition by the hydrogen reduction of tungsten hexafluoride. EVREST, the computer program which performs the estimates, uses EVOLVE, a physically based process simulator for ballistic transport and heterogeneous reactions in features on patterned wafers, to compute film profiles for a given set of deposition conditions. In order to validate the estimation method and to demonstrate EVREST, test calculations are performed using film profiles generated by EVOLVE instead of experimental scanning electron microscopy cross-sections. Calculated films profiles are compared with the generated film profiles (the data) and the simulated deposition conditions are adjusted using an algorithm based on Marquardt's method to minimize the sum of squared differences between points on the calculated and generated profiles. Test calculations confirm that film profiles in more than one feature can be used to improve the reliability of the partial pressure and temperature estimates.     

Synthesis,Characterization, and Reactivity of Lanthanide Complexes with Bulky Silylallyl Ligands

The synthesis of new lanthanide allyl complexes of enhanced stability and solubility in saturated hydrocarbons based on silyl-substituted allyl ligands is reported. Thus the potassium salt K(CH₂CHCHSiMe₃) ( 1 ) reacts with YCl₃ in tetrahydrofuran to give the tris-allyl complex Y(CH₂CHCHSiMe₃)₃ ( 2 ), while K(CH₂CHCHSiMe₂^tBu) ( 3 ) affords Y(CH₂CHCHSiMe₂^tBu)₃(THF)_1.5 ( 4 ). Slow re-crystallization of 4 from light petroleum in the presence of tert-butylcyanide led to multiple insertion to give the sec-amido complex Y{NHC(^tBu)(CH)₃SiMe₂^tBu}₂{η₂-NHC(^tBu)CH=CHCH₂SiMe₂^tBu)CH(CHCHSiMe₂^tBu)C^tBuNH}(THF)·(CH₃CH(Me)(CH₂)₂CH₃) ( 5 ), which was crystallographically characterized. The reaction of ScCl₃(THF)₃ with two equivalents of Li{1,3-C₃H₃(SiMe₃)₂} in tetrahydrofuran gives the bis-allyl complex {1,3-C₃H₃(SiMe₃)₂}₂Sc(μ-Cl)₂Li(THF)₂ ( 6 ), while the analogous reaction of K{1,3-C₃H₃(SiMe₃)₂} ( 7 ) with either LaCl₃ or YCl₃ in tetrahydrofuran affords the bis-allyl complexes MCl{1,3-C₃H₃(SiMe₃)₂}₂(THF)_x (8, M = La, x = 1; 9, M = Y, x = 0). An attempt to prepare the similar neodymium complex gave the mono-allyl complex NdI₂{1,3-C₃H₃(SiMe₃)₂}(THF)_1.25 ( 10 ). The reactions of 8 and 9 with triisobutyl aluminum in benzene-d₆ show allyl exchange between lanthanide and aluminum. Complexes 8 , 9 , and 10 have been tested with a variety of activator systems as catalysts for the polymerization of 1,3-butadiene.     

Alcoholism at the time of injury among trauma center patients: Vehicular crash victims compared with other patients

A structured in-depth interview employing standardized criteria was used to determine the prevalence of lifetime and current alcohol dependence (alcoholism) in unselected consecutive patients admitted to a regional Level I trauma center. Of 629 patients, 157 (25.0%) were current alcoholics at the time of injury. An additional 87 (13.8%) were diagnosed as lifetime non-current alcoholics. There was no significant difference in the rates of current alcohol dependence among patients injured in vehicular crashes (23.5%), other unintentional trauma victims (29.3%), and those injured as a result of violence (24.6%). Of BAC + (blood alcohol concentration positive) patients, 54.5% were current alcoholics. However, 14.4% of alcohol-negative patients were also diagnosed as alcohol dependent.     

Alternating,all-trans polyenynes: Model compounds for poly(diacetylene)s with defined conjugation length

The syntheses of polyenynes as model compounds for poly(diacetylene)s (PDAs) are described. Variation of properties (UV–VIS, Raman, NMR and bond geometries) as a function of the chain length was investigated. After extrapolation to infinite chain length these data were compared to those for PDAs. From UV–VIS spectra a value of λ = 551 nm (2.25 eV) was calculated corresponding to the electronic transition of a single polyenyne chain. This energy is located at the low energy end of a yellow PDA solution spectrum. From Raman scattering v_(C?C) = 2108–2128 cm^?1 and v_(C?C) = 1505–1532 cm^?1 were calculated after extrapolation. Similarly sp-C¹³C NMR data yielded a shift of δ = 100 ppm. These data are almost identical to data known for yellow PDA solutions. Bond geometries are almost identical to those of poly(diacetylene)s and theoretical data.     

Improving manufacturing by cost-effective process modeling

Computer-aided engineering tools are routinely used to simulate forging and heat-treatment operations and to perform thermal and stress analyses. This review gives a few examples of the current uses of process modeling tools and outlines some developing capabilities and near-term applications.