Direct numerical simulations of interface dynamics to link capillary pressure and total surface energy

The flow of two immiscible fluids through a porous medium depends on the complex interplay between gravity, capillarity, and viscous forces. The interaction between these forces and the geometry of the medium gives rise to a variety of complex flow regimes that are difficult to describe using continuum models. Although a number of pore-scale models have been employed, a careful investigation of the macroscopic effects of pore-scale processes requires methods based on conservation principles in order to reduce the number of modeling assumptions. In this work we perform direct numerical simulations of drainage by solving Navier-Stokes equations in the pore space and employing the Volume Of Fluid (VOF) method to track the evolution of the fluid-fluid interface. After demonstrating that the method is able to deal with large viscosity contrasts and model the transition from stable flow to viscous fingering, we focus on the macroscopic capillary pressure and we compare different definitions of this quantity under quasi-static and dynamic conditions. We show that the difference between the intrinsic phase-average pressures, which is commonly used as definition of Darcy-scale capillary pressure, is subject to several limitations and it is not accurate in presence of viscous effects or trapping. In contrast, a definition based on the variation of the total surface energy provides an accurate estimate of the macroscopic capillary pressure. This definition, which links the capillary pressure to its physical origin, allows a better separation of viscous effects and does not depend on the presence of trapped fluid clusters.

Total Cost of Transportation Analysis of Road and Highway Issues, TR-477, Phase 2, 2003

A prior project, HR-388, (which was entitled "Total Cost of Transportation analysis of road and highway issues"), explored the use of a total economic cost basis for evaluation of road based transportation issues. It was conducted as a proof-of-concept effort between 1996 and 2002, with the final report presented in May 2002. TR-477 rebuilt the analytical model using current data, then performed general, system level, county level, and road segment level analyses. The results are presented herein and will be distributed to all county engineers for information and local use.

Total Cost of Transportation Analysis of Road and Highway Issues, TR-477, Phase 2 Supplement, 2003

Please see TR-477 Phase 2 Final Report -- http://publications.iowa.gov/id/eprint/20041

Total synthesis of (-)-isoavenaciolide

An enantioselective approach to (-)-isoavenaciolide was achieved starting from 1- undecyn-3-ol. The synthesis relied upon the preparation of a chiral 4-silyloxy-2-alkenylborane by hydroboration of a protected 2,3-allenol and subsequent stereoselective addition to 2- thiophenecarboxaldehyde

Cable fixation and early total hip arthroplasty in the treatment of acetabular fractures in elderly patients.

Eighteen patients with acetabular fractures, with a mean age of 76 years, were treated with cable fixation and acute total hip arthroplasty. Nine were T-shaped fractures, 4 associated transverse and posterior wall, 2 transverse, 2 posterior column and posterior wall, and 1 anterior and posterior hemitransverse fractures. One patient experienced 3 episodes of hip dislocation within 10 months after surgery. All the others had a good outcome at a mean follow-up time of 36 months. Radiographic assessment showed healing of the fracture and a satisfactory alignment of the cup without loosening. This option provides good primary fixation, stabilizes complex acetabular fractures in elderly patients, and permits early postoperative mobilization.

FM127: Systemic metal ion levels in patients with modular neck total hip arthroplasties: a prospective cohort study

There is increasing evidence that modular neck stems are prone to corrosion-related complications. Recent studies showed elevated metal ions levels and occasional pseudotumor formation in patients with such implants. The purpose of this study was to compare systemic metal-ion levels in patients after primary THA with modular neck stems to those of patients after non-modular implants. To our knowledge, this is the first cohort study including a control group, THA without CoCr heads and dry-assembled neck-stem connections. Methods: 50 patients after THA at a minimum follow-up of 1 year have been selected for the study. Patients with multiple prosthesis or other implants have been deselected. All received a cementless SPS stem from Symbios (Ti6Al4V). 40 patients have the modular neck (CoCr) version and 10 a monobloc version. All bearings were either ceramic-ceramic or ceramic-polyethylene to minimize other sources of CoCr ion release. In the modular group, the neck was chosen pre-operatively based on a 3D planning, allowing for a dry assembly of the stem and neck on the back table before implantation. A plasma system coupled to mass spectrometry was used for a complete elementary quantification in blood and serum separately. Clinical outcome was measured using the Oxford Hip Score. Results : Complete data sets of 29 patients (24 in the modular neck-group (10male, mean age 63y, 35-84y) and 5 in the monobloc-group (3 male, 69 y, 51-83y) are available to date. Mean Co blood levels were .95 ug/L (.14-12.4) in the modular group vs .27 ug/L (.10-.73) in the monobloc group (p=.2). Respective values for Cr were significantly higher in the modular group (.99 g/L; range .75-1.21) compared to those in the monobloc group (.74 g/L ;.62-.86; p=.001). No significant difference was found when comparing serum levels. 5/24 patients had Co levels above 1 g/L (12/24 for Cr), which is by some considered as a relevant elevation. The maximum Co level was measured in an asymptomatic patient. The Oxford Hip Scores were similar in both groups. Conclusion: Cr levels were significantly elevated in the modular neck group compared to those in the monobloc group. 1/24 patients with a modular prosthesis exhibited Co levels, which are beyond the threshold accepted even for metal-on-metal bearing couples. These results have contributed to our decision to abandon the use of modular neck stems. Routine follow-up including annual measurements of systemic CoCr concentrations should be considered.

Cross-Cultural Adaptation and Validation of the Spinal Function Sort (SFS) for French- and German-Speaking Patients with Back Complaints

Aim: Functional subjective evaluation through questionnaire is fundamental, but not often realized in patients with back complaints, notably because of lack of validated tools, in accordance with recognized psychometric criteria. The Spinal Function Sort (SFS), developed according to actual standards, was only validated in English. The aim of this study is to translate, adapt and validate the French and German version of the SFS.Method and material: The translation and cross-cultural adaptation were performed following the methodology proposed by the American Association of Orthopedist Surgeon. A total of 344 patients, presenting varied back complaints (especially degenerative and traumatic), took part in this study in a tertiary French- (n=87; mean age 44y; 17 women) and German-speaking (n=257; mean age 41y; 53 women) center. Test-retest reliability was quantified using the intraclass correlation coefficient (ICC) and construct validity was assessed by estimating the Pearson's correlation with the SF-36 physical and mental scales, the Visual Analogue Scale for Pain Intensity (VAS), and subscales of the Hospital Anxiety and Depression Scale (HADS).Results: Respectively for the French and German version, ICC were 0.98 and 0.94. Correlations 0.63 and 0.67 with the SF-36 Physical Functioning subscale; 0.60 and 0.52 with the SF-36 Physical Summary Scale ; -0.33 and -0.51 with the VAS ; -0.08 and 0.25 with the SF-36 Mental Health scale; 0.01 and 0.28 with the SF-36 Mental Summary Scale; -0.26 and -0.42 with the HADS depression; -0.17 and -0.45 with the HADS anxiety.Discussion: For both the French and German version of the SFS, the reliability was excellent. Convergent construct validity with SF-36 physical scales is good, moderated with the VAS. We find out a low correlation with SF-36 mental scales (divergent construct validity). We find out a low correlation with HADS subscales in the French version, and a moderate one in the German version. Selection bias, chronicity of the complaints, as well as cultural differences could explain these results. In conclusion, both the French and German version of the SFS are valid and reliable for evaluation of perceived functional capacity for patients with back complaints.

Fatal intrahepatic hemorrhage after nadroparin use for total hip arthroplasty.

Low-molecular-weight heparins have become the predominant choice for deep venous thrombosis prophylaxis and treatment. However, their use may cause bleeding complications. Intrahepatic bleeding is exceptional and only very few cases have been described. The authors present a unique case of fatal intrahepatic hematoma complicating nadroparin use in a 65-year-old woman with a hepatic cyst who was admitted to hospital for unilateral total hip arthroplasty. At autopsy, hemoperitoneum (2,000 ml of blood and clots) was evident. A ruptured sub-capsular hematoma involving the right lobe of the liver was observed. The hemorrhage within the cyst induced by the nadroparin use was likely responsible for the subsequent hepatic hematoma, liver rupture, and death. This case highlights the need for pathologists and surgeons to be aware of the possibility of intrahepatic hematoma in patients who have received low-molecular-weight heparins, undergone major surgery and present postoperative hemodynamic instability, especially in those with preoperative diagnosis of hepatic cyst.

Clinical presentation and outcome in a series of 88 patients with the cblC defect.

The cblC defect is the most common inborn error of vitamin B12 metabolism. Despite therapeutic measures, the long-term outcome is often unsatisfactory. This retrospective multicentre study evaluates clinical, biochemical and genetic findings in 88 cblC patients. The questionnaire designed for the study evaluates clinical and biochemical features at both initial presentation and during follow up. Also the development of severity scores allows investigation of individual disease load, statistical evaluation of parameters between the different age of presentation groups, as well as a search for correlations between clinical endpoints and potential modifying factors. RESULTS: No major differences were found between neonatal and early onset patients so that these groups were combined as an infantile-onset group representing 88 % of all cases. Hypotonia, lethargy, feeding problems and developmental delay were predominant in this group, while late-onset patients frequently presented with psychiatric/behaviour problems and myelopathy. Plasma total homocysteine was higher and methionine lower in infantile-onset patients. Plasma methionine levels correlated with "overall impression" as judged by treating physicians. Physician's impression of patient's well-being correlated with assessed disease load. We confirmed the association between homozygosity for the c.271dupA mutation and infantile-onset but not between homozygosity for c.394C>T and late-onset. Patients were treated with parenteral hydroxocobalamin, betaine, folate/folinic acid and carnitine resulting in improvement of biochemical abnormalities, non-neurological signs and mortality. However the long-term neurological and ophthalmological outcome is not significantly influenced. In summary the survey points to the need for prospective studies in a large cohort using agreed treatment modalities and monitoring criteria.

Total hip replacement with a collarless polished cemented anatomic stem: clinical and gait analysis results at ten years follow-up.

PURPOSE: The aim of this study was to determine outcomes of total hip replacement (THR) with the Lemania cemented femoral stem. METHODS: A total of 78 THR patients were followed and compared to 17 "fit", healthy, elderly and 72 "frail" elderly subjects without THR, using clinical outcome measures and a portable, in-field gait analysis device at five and ten years follow-up. RESULTS: Forty-one patients (53%), mean age 83.4 years, available at ten years follow-up, reported very good to excellent satisfaction. Mean Harris Hip and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were 81.2 and 10.5 points, respectively, with excellent radiological preservation of proximal femur bone stock. Spatial and temporal gait parameters were close to the fit group and better than the frail group. CONCLUSIONS: Lemania THR demonstrated very good, stable clinical and radiological results at ten years in an older patient group, comparable to other cemented systems for primary THR. Gait analysis confirmed good walking performance in a real-life environment.

Determinants of the essential one-carbon metabolism metabolites, homocysteine, S-adenosylmethionine, S-adenosylhomocysteine and folate, in cerebrospinal fluid.

BACKGROUND: Disturbances in the levels of one-carbon (1C) metabolism metabolites have been associated with a wide variety of neuropsychiatric diseases. Cerebrospinal fluid (CSF) levels of homocysteine (Hcy) and the other 1C metabolites, nor their interrelatedness and putative determinants, have been studied extensively in a healthy population. METHODS: Plasma and CSF samples from 100 individuals free from neuropsychiatric diseases were analyzed (55 male, 45 female; age 50±17 years). In blood, we measured plasma Hcy, serum folate and serum vitamin B12. In CSF, we measured total Hcy, S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH) and 5-methyltetrahydrofolate (5-methylTHF). Highly selective analytical methods like liquid chromatography combined with either mass spectrometry or fluorescence detection were used. RESULTS: CSF Hcy was inversely correlated with CSF 5-methylTHF and positively with plasma Hcy, independent of serum folate status. CSF SAH correlated with age, lower CSF 5-methylTHF and higher CSF Hcy. CSF 5-methylTHF showed independent negative correlations with age and positive correlations with serum folate. CSF SAM did not correlate with any of the 1C metabolites. CONCLUSIONS: Aging is characterized by a reduction in CSF 5-methylTHF levels and increased CSF levels of the potentially neurotoxic transmethylation inhibitor SAH. CSF 5-methylTHF, which is itself determined in part by systemic folate status, is a powerful independent determinant of CSF levels of Hcy and SAH.

A genome-wide screen for interactions reveals a new locus on 4p15 modifying the effect of waist-to-hip ratio on total cholesterol.

Recent genome-wide association (GWA) studies described 95 loci controlling serum lipid levels. These common variants explain ∼25% of the heritability of the phenotypes. To date, no unbiased screen for gene-environment interactions for circulating lipids has been reported. We screened for variants that modify the relationship between known epidemiological risk factors and circulating lipid levels in a meta-analysis of genome-wide association (GWA) data from 18 population-based cohorts with European ancestry (maximum N = 32,225). We collected 8 further cohorts (N = 17,102) for replication, and rs6448771 on 4p15 demonstrated genome-wide significant interaction with waist-to-hip-ratio (WHR) on total cholesterol (TC) with a combined P-value of 4.79×10(-9). There were two potential candidate genes in the region, PCDH7 and CCKAR, with differential expression levels for rs6448771 genotypes in adipose tissue. The effect of WHR on TC was strongest for individuals carrying two copies of G allele, for whom a one standard deviation (sd) difference in WHR corresponds to 0.19 sd difference in TC concentration, while for A allele homozygous the difference was 0.12 sd. Our findings may open up possibilities for targeted intervention strategies for people characterized by specific genomic profiles. However, more refined measures of both body-fat distribution and metabolic measures are needed to understand how their joint dynamics are modified by the newly found locus.

Correlations between Vocal Input and Visual Response Apparently Enhance Presence in a Virtual Environment

This work investigates novel alternative means of interaction in a virtual environment (VE).We analyze whether humans can remap established body functions to learn to interact with digital information in an environment that is cross-sensory by nature and uses vocal utterances in order to influence (abstract) virtual objects. We thus establish a correlation among learning, control of the interface, and the perceived sense of presence in the VE. The application enables intuitive interaction by mapping actions (the prosodic aspects of the human voice) to a certain response (i.e., visualization). A series of single-user and multiuser studies shows that users can gain control of the intuitive interface and learn to adapt to new and previously unseen tasks in VEs. Despite the abstract nature of the presented environment, presence scores were generally very high.

Total and segmental liver volume variations: implications for liver surgery.

BACKGROUND: Liver remnant volumes after major hepatic resection and graft volumes for liver transplantation correlate with surgical outcome. The relative contributions of the hepatic segments to total liver volume (TLV) are not well established. METHODS: TLV and hepatic segment volumes were measured with computed tomography (CT) in 102 patients without liver disease who underwent CT for conditions unrelated to the liver or biliary tree. RESULTS: TLV ranged from 911 to 2729 cm(3). On average, the right liver (segments V, VI, VII, and VIII) contributed approximately two thirds of TLV (997+/-279 cm(3)), and the left liver (segments II, III and IV) contributed approximately one third of TLV (493+/-127 cm(3)). Bisegment II+III (left lateral section) contributed about half the volume of the left liver (242+/-79 cm(3)), or 16% of TLV. Liver volumes varied significantly between patients--the right liver varied from 49% to 82% of TLV, the left liver, 17% to 49% of TLV, and bisegment II+III (left lateral section) 5% to 27% of TLV. Bisegment II+III contributed less than 20% of TLV in more than 75% of patients and the left liver contributed 25% or less of TLV in more than 10% of patients. DISCUSSION: There is clinically significant interpatient variation in hepatic volumes. Therefore, in the absence of appreciable hypertrophy, we recommend routine measurement of the future liver remnant before extended right hepatectomy (right trisectionectomy) and in selected patients before right hepatectomy if a small left liver is anticipated.