A modified two temperature molecular dynamics (2T-MD) model for cascades.

Two-Temperature molecular dynamics (2T-MD) is a common approach for describing how electrons contribute to the evolution of a damage cascade by addressing their role in the redistribution of energy in the system. However, inaccuracies in 2T-MD's treatment of the high-energy particles have limited its utilisation. Here, we propose a reformulation of the traditional 2T-MD scheme to overcome this limitation by addressing the spurious double-interaction of high-energy atoms with electrons. We conduct a series of radiation damage cascades for 30, 50, and 100 keV primary knock-on atoms in increasingly large cubic W cells. In the simulations, we employ our modified 2T-MD scheme along with other treatments of electron-phonon coupling to explore their impact on the cascade evolution and the number of remnant defects. The results suggest that with the proposed modification, 2T-MD simulations account for the temperature time evolution during the ballistic phase and remove arbitrary choices, thus providing a better description of the underlying physics of the damage process.

Modeling Water Quality in Watersheds: From Here to the Next Generation.

In this synthesis, we assess present research and anticipate future development needs in modeling water quality in watersheds. We first discuss areas of potential improvement in the representation of freshwater systems pertaining to water quality, including representation of environmental interfaces, in-stream water quality and process interactions, soil health and land management, and (peri-)urban areas. In addition, we provide insights into the contemporary challenges in the practices of watershed water quality modeling, including quality control of monitoring data, model parameterization and calibration, uncertainty management, scale mismatches, and provisioning of modeling tools. Finally, we make three recommendations to provide a path forward for improving watershed water quality modeling science, infrastructure, and practices. These include building stronger collaborations between experimentalists and modelers, bridging gaps between modelers and stakeholders, and cultivating and applying procedural knowledge to better govern and support water quality modeling processes within organizations.

Field Test of a Hybrid Finite-Difference and Analytic Element Regional Model.

Regional finite-difference models often have cell sizes that are too large to sufficiently model well-stream interactions. Here, a steady-state hybrid model is applied whereby the upper layer or layers of a coarse MODFLOW model are replaced by the analytic element model GFLOW, which represents surface waters and wells as line and point sinks. The two models are coupled by transferring cell-by-cell leakage obtained from the original MODFLOW model to the bottom of the GFLOW model. A real-world test of the hybrid model approach is applied on a subdomain of an existing model of the Lake Michigan Basin. The original (coarse) MODFLOW model consists of six layers, the top four of which are aggregated into GFLOW as a single layer, while the bottom two layers remain part of MODFLOW in the hybrid model. The hybrid model and a refined "benchmark" MODFLOW model simulate similar baseflows. The hybrid and benchmark models also simulate similar baseflow reductions due to nearby pumping when the well is located within the layers represented by GFLOW. However, the benchmark model requires refinement of the model grid in the local area of interest, while the hybrid approach uses a gridless top layer and is thus unaffected by grid discretization errors. The hybrid approach is well suited to facilitate cost-effective retrofitting of existing coarse grid MODFLOW models commonly used for regional studies because it leverages the strengths of both finite-difference and analytic element methods for predictions in mildly heterogeneous systems that can be simulated with steady-state conditions.

Lesions of uncertain malignant potential (B3) on core biopsy in the NHS Breast Screening Programme: is the screening round relevant?

INTRODUCTION: Most women who have screening mammography and undergo subsequent open biopsy following an indeterminate core biopsy result are eventually found to have benign disease. However, a significant number have malignant disease and the rate of malignancy in such cases may be influenced by various factors. This study examined the effect of the type of screening round (prevalent or incident) on the likelihood of breast cancer being present. METHODS: A total of 199 women who had NHS breast screening mammograms and subsequent indeterminate (B3) core biopsy results followed by excision biopsy over an 11-year period in a single breast screening unit were reviewed. RESULTS: The rate of malignancy following excision of a lesion graded as B3 on core biopsy was 21% for women in the prevalent screening round compared to 33% in subsequent rounds (Fisher's exact test, p=0.038). CONCLUSIONS: The incidence of malignancy associated with a B3 core biopsy result appears to be related to the screening round in which the lesion is detected, being approximately 50% higher in the subsequent incident rounds compared to the initial prevalent round. This finding may be useful in formulating management plans for women who have an indeterminate biopsy result.

A hybrid finite-difference and analytic element groundwater model.

Regional finite-difference models tend to have large cell sizes, often on the order of 1-2 km on a side. Although the regional flow patterns in deeper formations may be adequately represented by such a model, the intricate surface water and groundwater interactions in the shallower layers are not. Several stream reaches and nearby wells may occur in a single cell, precluding any meaningful modeling of the surface water and groundwater interactions between the individual features. We propose to replace the upper MODFLOW layer or layers, in which the surface water and groundwater interactions occur, by an analytic element model (GFLOW) that does not employ a model grid; instead, it represents wells and surface waters directly by the use of point-sinks and line-sinks. For many practical cases it suffices to provide GFLOW with the vertical leakage rates calculated in the original coarse MODFLOW model in order to obtain a good representation of surface water and groundwater interactions. However, when the combined transmissivities in the deeper (MODFLOW) layers dominate, the accuracy of the GFLOW solution diminishes. For those cases, an iterative coupling procedure, whereby the leakages between the GFLOW and MODFLOW model are updated, appreciably improves the overall solution, albeit at considerable computational cost. The coupled GFLOW-MODFLOW model is applicable to relatively large areas, in many cases to the entire model domain, thus forming an attractive alternative to local grid refinement or inset models.

Long-term prognosis of gastrojejunostomy in foals with gastric outflow obstruction: 16 cases (2001-2006).

REASONS FOR PERFORMING STUDY: It has been suggested that the success of gastric bypass surgery in foals for the treatment of gastric outflow obstruction is poor. However, few reports exist evaluating the long-term prognosis of these cases. OBJECTIVES: To determine the long-term success of foals, including racing records, surgically treated for gastric outflow obstruction secondary to gastroduodenal ulceration. METHODS: Medical records of foals undergoing surgical treatment of gastric outflow obstruction secondary to gastroduodenal ulceration were evaluated for clinical information. Owners, trainers and race records were evaluated regarding long-term survival and racing success. RESULTS AND CONCLUSIONS: Sixteen foals were included in the study, all treated with a gastrojejunostomy. All foals survived to immediate discharge from the hospital; 8 survived to racing age, with 7 of those entering training and 3 actually racing. Foals that did not survive to racing age had various post operative complications. The success rate for these foals appears somewhat better than that previously reported. POTENTIAL RELEVANCE: Gastrojejunostomy for the treatment of gastric outflow obstruction, secondary to gastric ulceration, is a valid treatment option for foals.

Estimating recharge rates with analytic element models and parameter estimation.

Quantifying the spatial and temporal distribution of recharge is usually a prerequisite for effective ground water flow modeling. In this study, an analytic element (AE) code (GFLOW) was used with a nonlinear parameter estimation code (UCODE) to quantify the spatial and temporal distribution of recharge using measured base flows as calibration targets. The ease and flexibility of AE model construction and evaluation make this approach well suited for recharge estimation. An AE flow model of an undeveloped watershed in northern Wisconsin was optimized to match median annual base flows at four stream gages for 1996 to 2000 to demonstrate the approach. Initial optimizations that assumed a constant distributed recharge rate provided good matches (within 5%) to most of the annual base flow estimates, but discrepancies of >12% at certain gages suggested that a single value of recharge for the entire watershed is inappropriate. Subsequent optimizations that allowed for spatially distributed recharge zones based on the distribution of vegetation types improved the fit and confirmed that vegetation can influence spatial recharge variability in this watershed. Temporally, the annual recharge values varied >2.5-fold between 1996 and 2000 during which there was an observed 1.7-fold difference in annual precipitation, underscoring the influence of nonclimatic factors on interannual recharge variability for regional flow modeling. The final recharge values compared favorably with more labor-intensive field measurements of recharge and results from studies, supporting the utility of using linked AE-parameter estimation codes for recharge estimation.

Surgical repair of rib fractures in 14 neonatal foals: case selection, surgical technique and results.

REASONS FOR PERFORMING STUDY: Fractured ribs are encountered quite frequently in newborn Thoroughbred foals, often with fatal outcome. Surgical repair of fractures therefore requires consideration as a means of reducing mortality. OBJECTIVES: To evaluate the repair of rib fractures using internal fixation techniques in foals at 2 different equine hospitals following similar diagnostics and case selection. METHODS: The records of 14 foals that underwent internal fixation of fracture ribs were reviewed. Subject details, clinical presentation, diagnosis, surgical technique, post operative care and complications were recorded. Follow-up information was obtained in 7 foals. RESULTS: The fractured ribs were reduced and stabilised using reconstruction plate(s), self-tapping cortical screws and cerclage wire in 12 cases, Steinmann pins and cerclage wires in 1 case and both techniques in 1 case. Not every rib was reduced on each case. Surgical reduction was performed on an average of 2 ribs, range 1-3 ribs in each foal. At the time of writing, 4 foals had been sold, one age 2 years was in training and 2 others died from unrelated causes. CONCLUSIONS: Our data support the use of surgical stabilisation utilising reconstruction plates, self-tapping cortical screws and cerclage wire for selected cases of thoracic trauma in neonatal foals. The use of Steinmann pins may be suboptimal due to cyclic failure, implant migration and the potential for iatrogenic internal thoracic trauma. POTENTIAL RELEVANCE: Foals with existing extensive internal thoracic trauma resulting from rib fracture(s), or the potential for such trauma, previously considered to have a guarded to poor prognosis for survival, may be successfully managed with internal fixation of selected fracture sites.

Survival analysis of posterior restorations using an insurance claims database.

This study indicates that composite restorations do not last as long as amalgam restorations in posterior teeth. Dentists can use this information to better inform their patients when choosing restorative materials.

Delineating a recharge area for a spring using numerical modeling, Monte Carlo techniques, and geochemical investigation.

Recharge areas of spring systems can be hard to identify, but they can be critically important for protection of a spring resource. A recharge area for a spring complex in southern Wisconsin was delineated using a variety of complementary techniques. A telescopic mesh refinement (TMR) model was constructed from an existing regional-scale ground water flow model. This TMR model was formally optimized using parameter estimation techniques; the optimized "best fit" to measured heads and fluxes was obtained by using a horizontal hydraulic conductivity 200% larger than the original regional model for the upper bedrock aquifer and 80% smaller for the lower bedrock aquifer. The uncertainty in hydraulic conductivity was formally considered using a stochastic Monte Carlo approach. Two-hundred model runs used uniformly distributed, randomly sampled, horizontal hydraulic conductivity values within the range given by the TMR optimized values and the previously constructed regional model. A probability distribution of particles captured by the spring, or a "probabilistic capture zone," was calculated from the realistic Monte Carlo results (136 runs of 200). In addition to portions of the local surface watershed, the capture zone encompassed areas outside of the watershed--demonstrating that the ground watershed and surface watershed do not coincide. Analysis of water collected from the site identified relatively large contrasts in chemistry, even for springs within 15 m of one another. The differences showed a distinct gradation from Ordovician-carbonate-dominated water in western spring vents to Cambrian-sandstone-influenced water in eastern spring vents. The difference in chemistry was attributed to distinctive bedrock geology as demonstrated by overlaying the capture zone derived from numerical modeling over a bedrock geology map for the area. This finding gives additional confidence to the capture zone calculated by modeling.

Scedosporium prolificans infection associated with arthritis and osteomyelitis in a horse.

Scedosporium prolificans was associated with arthritis and degenerative osteomyelitis in a 6-year-old Thoroughbred racehorse. The horse was suspected to have an inflammatory lesion of the interosseous tendon, but treatment had resulted in only a minimal response. Shortly after diagnostic arthrocentesis of the left metacarpophalangeal joint was performed, the joint became severely swollen, and radiography of the area revealed lysis of the distal end of the third metacarpal bone, the proximal sesamoid bones, and the proximal end of the proximal phalanx. The horse did not respond to treatment and was euthanatized. At necropsy, severe erosive arthritis and degenerative osteomyelitis of the left metacarpophalangeal joint were seen. Swab specimens of the ulcerated lesions of the articular cartilage were submitted for microbial culture, and Scedosporium prolificans was isolated. Scedosporium prolificans is a newly recognized opportunistic fungal pathogen of humans and animals. In humans, S prolificans typically causes focal locally invasive infections that primarily involve musculoskeletal tissues; most often, infection is a result of penetrating trauma or surgical incision. In immunocompromised patients, fatal disseminated infection can occur. The fungus is resistant to almost all currently available antimycotic agents.

Career satisfaction and job characteristics of dental hygiene master's degree graduates.

PURPOSE: The primary objectives of this study were to assess career and degree satisfaction as well as job characteristics of individuals graduating from programs awarding the master of science in dental hygiene or dental hygiene education degree. METHODS: A pilot-tested questionnaire was mailed to all 252 individuals who graduated between 1980 and 1995 from eight dental hygiene master's degree programs (MSDH). The questionnaire included both closed- and open-ended items regarding career history/career path, career satisfaction, professional involvement, and opinions/perceptions about the graduate program the participant attended. Responses were analyzed using descriptive statistics and two-way tables. RESULTS: After three complete mailings, the response rate was 69% (n = 174). The majority of respondents reported currently working approximately five days per week (54%), with 62% having annual salaries over $40,000. Eighty-six percent were satisfied overall with their career choices, although 30% stated that they would not pursue the same degree again. CONCLUSION: Overall, graduates from MSDH programs are satisfied with their degree choice as well as the opportunities it has afforded them. These findings serve to expand the knowledge base of graduate dental hygiene education and of the graduates from these programs as well as provide suggestions for improvement to graduate dental hygiene programs.

Adjustment of the M-component of the DMFS index for prevalence studies of older adults.

Cross-sectional studies of caries in older adults report a substantial number of missing teeth, making it difficult to estimate caries experience accurately. The goal of this study was to improve the method of estimating caries experience as expressed by the DMFS index in population groups with missing teeth. The adjustment was demonstrated with reference to the Piedmont 65+ Dental Study conducted on a random sample of 363 community-dwelling older adults in North Carolina who were followed for 5 years. These older dentate adults had a mean (+/-SE) of 11.7 +/- 0.5 teeth missing at baseline, 56.1 +/- 2.5 missing surfaces and a DMFS of 86.7 +/- 2.0. A predicted caries prevalence was determined from the DFS at 5 yrs plus the 5-yr DFS incidence and the baseline DFS of teeth lost during the study period. Then a formula was developed that would estimate the predicted caries prevalence as a function of the observed 5-yr DMFS. This formula provided a good estimation of caries prevalence at 5 yrs (DMFSadj) when compared with the predicted prevalence (paired t-test, p > 0.05), while prevalence was underestimated by the DFS and greatly overestimated by the traditional DMFS index. Subgroup analyses by race, sex, and periodontal status also indicated that the DMFSadj resulted in patterns of estimates similar to the predicted prevalence, while the DFS and the DMFS were likely to result in different findings. The DMFS from the time of tooth eruption also was adjusted using this formula. The resulting analyses of subgroup differences in caries were not different from the previous estimates based on the 5-yr historical data, indicating that the adjustment of all M surfaces avoids the biases inherent in the traditional DMFS and DFS indices. This study showed that predicted caries prevalence could be estimated by adjusting the M component of the DMFS. It appears that this adjustment formula can be used without obvious bias, but additional studies are needed to provide adjustment figures for populations with different caries prevalences.

Variations in the social impact of oral conditions among older adults in South Australia, Ontario, and North Carolina.

Previous studies among older adults have demonstrated that oral disease frequently leads to dysfunction, discomfort, and disability. This study aimed to assess variations in the social impact of oral conditions among six strata of people aged 65 years and older: residents of metropolitan Adelaide and rural Mt Gambier, South Australia; residents of metropolitan Toronto-North York and non-metropolitan Simcoe-Sudbury counties, Ontario, Canada; and blacks and whites in the Piedmont region of North Carolina (NC), United States. Subjects were participants in three oral epidemiological studies of random samples of the elderly populations in the six strata. Some 1,642 participants completed a 49-item Oral Health Impact Profile (OHIP) questionnaire which asked about impacts caused by problems with the teeth, mouth, or dentures during the previous 12 months. The percentage of dentate people reporting impacts fairly often or very often was greatest among NC blacks for 41 of the OHIP items. Two summary variables of social impact were used as dependent variables in bivariate and multivariate least-squares regression analyses. Among dentate people, mean levels of social impact were greatest for NC blacks and lowest for NC whites, while people from South Australia and Ontario had intermediate levels of social impact (P < 0.01). Missing teeth, retained root fragments, root-surface decay, periodontal pockets, and problem-motivated dental visits were associated with higher levels of social impact (P < 0.05), although there persisted a two-fold difference in social impact across the six strata after adjustment for those factors Among edentulous people, there was no statistically significant variation in social impact among strata. The findings suggest that there are social and cultural factors influencing oral health and its social impact, and that those factors differ most between dentate blacks and whites in NC.

Salivary flow and risk of tooth loss in an elderly population.

To investigate the relationship between salivary flow and tooth loss, 818 randomly selected dentate people aged 65 and older and living in North Carolina were administered a dental health interview and examination. A single paraffin-stimulated whole saliva sample of 3 ml was collected and flow rate was calculated. Three years later, 490 people were re-examined and tooth loss was determined. Thirty-five percent of the participants had salivary flow rates of 1.0 ml/min or less at baseline and 41% lost at least one tooth over the 3-yr follow-up. A logistic regression model controlling for marital status, race, and socioeconomic status showed that those with low salivary flow were more likely to lose at least one tooth during the 3-yr study period than were those with normal flow (odds ratio = 1.52, 95% CI = 1.02-2.24). Results from this representative study of community-dwelling older adults support the concept that compromised salivary flow is related to tooth loss. This finding should be considered in the management and prevention of oral diseases.

Five-year incidence rates and intraoral distribution of root caries among community-dwelling older adults.

The 5-year incidence and intraoral distribution of decayed and filled root surfaces were evaluated in 379 black and 323 white residents of North Carolina aged 65 and older. During the period of study, approximately 39% of blacks developed at least one root DFS compared with 52% for whites (Wald X(2) test, p = 0.062). When the results were calculated using the net root DFS increment, blacks did not have significantly higher rates than whites over the 5-year study period (0.52 surfaces/person versus 0.42 surfaces/person, Survey Regression, n = 363, p = 0.708). However, for blacks, the 5-year incidence density rate of root DFS was 0.26 per 60 surface-months at risk, and for whites the rate was 0.19 new root DFS per 60 surface-months (incidence density ratio = 1.33, 95% CI = 1.01-1.76, p = 0.047). Intraoral distribution patterns for root caries incidence revealed that the approximal surfaces of the anterior teeth were involved most frequently, particularly in the mandible and maxilla in whites, followed in decreasing order by the buccal surfaces of the lower anteriors and the mesial surfaces of the upper anteriors in blacks. Although root caries incidence rates were obviously low, there were significant differences in the occurrence of caries between blacks and whites. The pattern of occurrence was similar for both races with root surface disease being concentrated in the approximal surfaces of the anterior teeth in a small proportion of affected individuals, with whites presenting more filled root increments than blacks. These findings suggest a need for more caries treatment in blacks and increased monitoring of this population since they are at a higher risk for root caries.

Unilateral choanal atresia in a foal.

A 4-month-old Thoroughbred foal was examined because of a history of exercise intolerance and lack of airflow from the right nostril since birth. Endoscopy of the airways revealed complete membranous obstruction of the right nasal passage at the level of the nasopharynx and marked narrowing of the caudal aspect of the right ventral meatus. Unilateral choanal atresia was diagnosed. Laser ablation of the obstructing tissues was attempted through a videoendoscope. Scar tissue occluded the right nasal passage at follow-up examination 7 weeks later. Intranasal resection, using laparoscopic instruments, was then performed, and a nasal stent was maintained for 2 weeks after surgery. At 1 year of age, the foal was reported to have decreased airflow from the right nares and excessive respiratory noise during exercise. Atresia of the choanae in horses usually is bilateral and, therefore, life-threatening and detectable at birth. Unilateral choanal atresia may not be suspected until later, but should be considered in horses with decreased or no airflow from 1 naris.

Physicochemical properties, pharmacokinetics, and biodistribution of gadoteridol injection in rats and dogs.

RATIONALE AND OBJECTIVES: The physicochemical properties of gadoteridol, a macrocyclic nonionic gadolinium complex, were studied together with its pharmacokinetics and biodistribution in rats and dogs. METHODS: Studies in rats were conducted after single intravenous injections at 0.1 or 0.35 mmol/kg using 153Gd-labeled gadoteridol or with seven daily doses of 0.1 mmol/kg to examine the levels of residual gadolinium in organs. Nonradioactive biodistribution and excretion studies were performed in dogs following injection at 0.1 mmol/kg. RESULTS: After injection, the dose was rapidly cleared from rat blood and excreted such that more than 90% of the dose appeared in the urine within 4 hr of injection. At 7 and 14 days postinjection, only extremely low levels of gadolinium were observed in liver and bone; these levels were two to eight times lower than the levels reported after the injection of gadopentetate dimeglumine. CONCLUSION: The extracellular distribution and rapid urinary excretion of gadoteridol is in agreement with data obtained with other gadolinium-containing chelates used as intravascular magnetic resonance imaging contrast agents. Differences observed in the long-term retention of gadolinium between gadoteridol and gadopentetate dimeglumine were consistent with the reported greater in vivo resistance to transmetallation of gadolinium macrocycles compared with the linear gadolinium chelate molecules.

Eighteen-month incidence of tooth loss among older adults in North Carolina.

This study investigated tooth loss in North Carolina adults 65 years of age or older. A random sample of 335 Blacks and 284 Whites participated in dental examinations and interviews at baseline and again after 18 months. Blacks were more likely than Whites to lose at least one tooth (36% vs 19%), and they lost more teeth on average (1.0 vs 0.4). Several oral disease conditions and symptoms were related to tooth loss, but many other hypothesized factors were not. Risk models were inconclusive in the identification of factors related to risk of tooth loss.

Intraperitoneal use of sodium carboxymethylcellulose in horses undergoing exploratory celiotomy.

The effect of intraperitoneal sodium carboxymethylcellulose (SCMC) administration on clinical outcome and survival was evaluated in horses undergoing exploratory celiotomy for acute gastrointestinal disease. Comparison of variables was made retrospectively between 44 horses that had SCMC and 92 horses (controls) not treated with SCMC. Mean age, body weight, heart rate, packed cell volume and plasma total protein of horses at admission, and convalescent period were not significantly different between control and SCMC groups. No significant differences were noted between control horses and SCMC horses with respect to incisional infection, hernia formation, recurrent episodes of colic, clinical outcome, and long-term survival (> 6 months). Seventy-six (83%) control horses and 34 (77%) SCMC horses survived long-term. Seventy (76%) control horses and 30 (68%) SCMC horses survived without complications and returned to their previous use. These results suggest that intraperitoneal use of SCMC does not adversely affect abdominal incisional wound healing, clinical outcome or long-term survival, however, the efficacy of SCMC in prevention of postoperative intestinal adhesions in horses requires further investigation.