Environmental Site Characterization and Risk-Based Evaluation of a Site Contaminated with Tetrachloroethene (PCE) and Trichloroethene (TCE)

A healthcare company purchased property in eastern Iowa for a facility expansion. Before the purchase, a Phase I environmental site assessment (ESA) revealed that the property was the site of a former dry cleaning business. Phase II sampling and testing indicated that tetrachloroethene (PCE) and trichloroethene (TCE) had affected site soil and groundwater. Maximum concentrations of PCE and TCE in groundwater were 538 and 209 µg/L, respectively, and 105 and 1.51 mg/kg in soil. Additional sampling delineated the vertical and horizontal extent of contamination in the soil. The concentrations of the chlorinated solvents in both the soil and groundwater were below levels of regulatory concern. However, the company was concerned that the Iowa statewide standard for PCE in soil (780 mg/kg) might not provide adequate protection for several exposure pathways and wanted to assess the risk to the public from the contamination at the site. The results of a receptor survey were used to develop site-specific target levels (SSTLs) for contamination, using accepted human health exposure factors, models, and chemical-specific toxicity values. The recommended remedial options allowed the company to minimize the human health risks posed by contamination at the site

Early and late results of surgery for Wolff-Parkinson-White syndrome

Surgical treatment for accessory atrioventricular connections was performed in 60 patients with Wolff-Parkinson-White syndrome between 1981 and 1986. The initial procedure successfully divided 69 of 73 pathways identified preoperatively, including 39 of 40 left free wall pathways, 23 of 24 posteroseptal pathways, six of seven right free wall pathways, and one of two anteroseptal pathways. Three additional pathways were identified for the first time during follow-up. The primary procedure was successful in curing 53 (88%) of the 60 patients and in dividing 69 (91%) of the total of 76 pathways. Subsequent procedures increased the overall clinical cure rate to 97%. The surgery was performed with low morbidity and no perioperative or late mortality. Patients were followed-up for a mean of 6.4 years (range four to nine years). No patient showed clinical or electrocardiographic evidence of recurrence of a pathway which had been divided surgically. We conclude that regardless of pathway site, surgical treatment carries a low risk and has a high probability of avoiding lifelong antiarrhythmic therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75341/1/j.1445-5994.1991.tb04698.x.pd

Clinical Experience and Sexual Function Outcome of Patients With Priapism Treated With Penile Cavernosal-Dorsal Vein Shunt Using Saphenous Vein Graft

OBJECTIVES To assess the outcome of new penile cavernosal-dorsal vein shunt using a saphenous vein graft. Traditional surgeries for priapism have high failure rate and subsequent impotence. METHODS We reviewed the medical records of, and administered a questionnaire and the International Index of Erectile Function to, 16 consecutive patients with priapism who had treated with the penile cavernosal-dorsal vein shunt from 1997 to 2007. Their age was 15-65 years. The duration of ischemic priapism was 32 hours to 8 days. Ten patients had previously undergone shunt surgery by other urologists. Of the 16 patients, 5 returned the questionnaires. RESULTS Priapism resolved or was improved after surgery in all 16 patients. One patient was lost to follow-up. One pediatric patient was excluded from the analysis. One patient with nonischemic priapism continued to have sexual intercourse. Of the 13 adult patients with ischemic priapism and follow-up for ≤ 6.5 years, 3 patients had no erection, 1 had very little erection, and 9 (69%) had erection. Of the 9 patients with erections possible, six had had sexual intercourse (International Index of Erectile Function score 32-70) and 3 had not; 1 had a mental disorder, 1 was in prison, and for 1, the reason was unknown. After surgery, color Doppler ultrasound studies showed a patent shunt in all patients and restoration of cavernosal arterial flow in 12 of 13 patients studied. CONCLUSIONS A penile cavernosal-dorsal shunt appears effective for priapism. It resulted in priapism resolution even in patients who had experienced a previous failed cavernosal-glandular shunt or cavernosalspongiosal shunt, with a high rate of sexual function preservation

An Empirical Charge Transfer Potential with Correct Dissociation Limits

The empirical valence bond (EVB) method [J. Chem. Phys. 52, 1262 (1970)] has always embodied charge transfer processes. The mechanism of that behavior is examined here and recast for use as a new empirical potential energy surface for large-scale simulations. A two-state model is explored. The main features of the model are: (1) Explicit decomposition of the total system electron density is invoked; (2) The charge is defined through the density decomposition into constituent contributions; (3) The charge transfer behavior is controlled through the resonance energy matrix elements which cannot be ignored; and (4) A reference-state approach, similar in spirit to the EVB method, is used to define the resonance state energy contributions in terms of "knowable" quantities. With equal validity, the new potential energy can be expressed as a nonthermal ensemble average with a nonlinear but analytical charge dependence in the occupation number. Dissociation to neutral species for a gas-phase process is preserved. A variant of constrained search density functional theory is advocated as the preferred way to define an energy for a given charge.Comment: Submitted to J. Chem. Phys. 11/12/03. 14 pages, 8 figure

Highly efficient and genotype-independent barley gene-editing based on anther culture

Recalcitrance to tissue culture and genetic transformation is the major bottleneck for gene manipulation in crops. In barley, immature embryos of Golden Promise have been mainly used as explants for transformation. However, the genotype-dependent approach limits the genetic modification in commercial varieties. Here, we develop an anther culture-based system that effectively creates transgenic and gene-edited plants from commercial barley varieties. The protocol was tested in four Australian varieties and Golden Promise with different phenology, callus induction and green plant regeneration responses. Agrobacterium-mediated transformation was performed on microspore-derived callus when targeting the HvPDS gene, and T0 albinos with targeted mutations were successfully obtained from commercial varieties. Further editing of three targets was achieved with an average mutation rate of 53% in the five varieties. In the 51 analysed T0 individuals, Cas9 induced about 69% of single-base insertion/deletions and two-base deletions in targeting sites, with variable mutation rates among targets and varieties. Both on-target and off-target activities were detected in T1 progenies. Compared with immature embryo protocols, this genotype-independent platform can deliver a high editing efficiency and more regenerants within a similar time frame. It is promising for functional genomics and application of CRISPR technologies for precise improvement in commercial varieties

Thermoelastic Damping in Micro- and Nano-Mechanical Systems

The importance of thermoelastic damping as a fundamental dissipation mechanism for small-scale mechanical resonators is evaluated in light of recent efforts to design high-Q micrometer- and nanometer-scale electro-mechanical systems (MEMS and NEMS). The equations of linear thermoelasticity are used to give a simple derivation for thermoelastic damping of small flexural vibrations in thin beams. It is shown that Zener's well-known approximation by a Lorentzian with a single thermal relaxation time slightly deviates from the exact expression.Comment: 10 pages. Submitted to Phys. Rev.

Application of robotics In the clinical laboratory

The basic types of robot are explained, and the performances and costs of some commercial examples are given. The potential advantages and problems of introducing robots into clinical laboratories are identified and the specifcation of a suitable robot is developed. None of the commercially available robots meets all aspects of the specificalion, and currently the purchase of a robot is considered premature for most clinical laboratories

The wear of fixed and mobile bearing unicompartmental knee replacements

Unicompartmental knee replacements (UKR) are an option for surgical intervention for the treatment of single-compartment osteoarthritis. The aim of this study was to compare the wear of a low-conformity fixed-bearing UKR with a conforming mobile bearing UKR under two kinematic conditions, to investigate the effect of implant design and kinematics on wear performance in a physiological knee wear simulator. Under both sets of kinematic conditions, the relatively low-conforming fixed UKR showed lower wear, compared with the more conforming anterior-posterior sliding mobile bearing. However, it should be noted that differences in materials between the two designs also contribute to the relative wear performance of the bearings. The combined wear of the medial and lateral bearings of the fixed-bearing UKR as a ‘total knee’ were significantly reduced compared with a fixed-bearing total knee replacement studied under the same kinematic condition