Variational solution to the lattice Boltzmann method for Couette flow.

Literature studies of the lattice Boltzmann method (LBM) demonstrate hydrodynamics beyond the continuum limit. This includes exact analytical solutions to the LBM, for the bulk velocity and shear stress of Couette flow under diffuse reflection at the walls through the solution of equivalent moment equations. We prove that the bulk velocity and shear stress of Couette flow with Maxwell-type boundary conditions at the walls, as specified by two-dimensional isothermal lattice Boltzmann models, are inherently linear in Mach number. Our finding enables a systematic variational approach to be formulated that exhibits superior computational efficiency than the previously reported moment method. Specifically, the number of partial differential equations (PDEs) in the variational method grows linearly with quadrature order while the number of moment method PDEs grows quadratically. The variational method directly yields a system of linear PDEs that provide exact analytical solutions to the LBM bulk velocity field and shear stress for Couette flow with Maxwell-type boundary conditions. It is anticipated that this variational approach will find utility in calculating analytical solutions for novel lattice Boltzmann quadrature schemes and other flows.

Comprehensive Evaluation of an HPLC-MS-MS Method for Quantitation of Seven Anti-Coagulant Rodenticides and Dicoumarol in Animal Serum.

Anti-coagulant rodenticides (ARs) are commonly utilized for controlling rodent populations; however, non-target companion and wildlife animals are also exposed. A method was developed for quantitation of seven ARs (chlorophacinone, coumachlor, bromadiolone, brodifacoum, difethialone, diphacinone and warfarin) and dicoumarol (a naturally occurring anti-coagulant) in animal serum. Analytes were extracted with 10% (v/v) acetone in methanol and analyzed by reverse phase high-performance liquid chromatography-tandem mass spectrometry using electrospray ionization (negative mode) combined with multiple reaction monitoring. In-house method validation in the originating laboratory using non-blinded samples revealed method limits of quantitation at 2.5 ng/mL for all analytes. The inter-assay accuracy ranged from 99% to 104%, and the relative standard deviation ranged from 3.5% to 20.5%. Method performance was then verified in the originating laboratory during an exercise organized by an independent party using blinded samples. The method was successfully transferred to two naïve laboratories and further evaluated for reproducibility among three laboratories by means of Horwitz ratio (HorRat(R)) values. Such extensive validation provides a high degree of confidence that the method is rugged, robust, and will perform as expected if used by others in the future.

Suprasellar Plasmacytoma Leading to the Diagnosis of Multiple Myeloma.

Plasmacytomas are a collection of plasma cells that occur as a solitary lesion or in conjunction with multiple myeloma. Intracranial location is uncommon but should be considered as management differs. Plasmacytomas in the suprasellar region are rare but should be considered in the differential diagnosis of suprasellar masses. Clinical presentation and imaging findings have similarities and overlap between pituitary adenomas and plasmacytomas, so the diagnosis depends on biopsy and pathological evaluation. Immunohistological staining is often necessary due to structural similarities to adenomas. Isolated cases may be treated with radiation alone and surgery is reserved for symptoms due to mass effect. Systemic therapy is given if there is evidence of multiple myeloma. In this case report, we present a 52-year-old male who presented with worsening blurry vision associated with headaches and epistaxis of four months duration. CT of the head showed a large mass involving the sella and skull base. Labs showed normal calcium, creatinine, and intact pituitary function. Biopsy of the mass was initially diagnosed as a pituitary adenoma but repeat pathology revealed plasmacytoma. Body imaging revealed diffuse lytic lesions. Bone marrow biopsy and serum electrophoresis were consistent with a diagnosis of multiple myeloma. The patient underwent radiation therapy to the suprasellar mass followed by systemic therapy for multiple myeloma with bortezomib, lenalidomide, and dexamethasone. The patient achieved a very good partial response.

Pharmacokinetics of tulathromycin following administration to stocker cattle with remote delivery devices.

Remote delivery devices (RDD) are used by some to administer antimicrobials (AM) to cattle when treatment by manual injection is logistically difficult. However, it is not clear that the pharmacokinetics (PK) of AM administered by RDD is comparable to that for AM administered by injection; thus, it is not certain that cattle treated by RDD experience equivalent AM effect. Fifteen crossbred beef steers (body weight [BW] = 302.5 ± 21.7 kg) were used in a three-way crossover study to determine the PK of tulathromycin following administration with RDD in the BQA injection triangle. Cattle were treated by each of three methods at 2.5 mg of tulathromycin per kg of BW with a 60 d washout period between treatments: 1) subcutaneous injection of tulathromycin (SC), 2) treatment by RDD delivered by air pump projector (AIR, Pneudart, Model 178B) at 4.5 m distance, and 3) treatment by RDD delivered by CO2-powered projector at 7.5 m (CO2, Pneudart, Model 176B). Blood was collected prior to injection and at various points up to 552 h post-administration, pharmacokinetic data were analyzed as a mixed model using animal as a random effect and method of administration, order of administration, and their interaction as fixed effects. Plasma creatine kinase (CK) was measured before treatment and at 24 h after treatment to determine the degree of muscle injury resulting from each treatment. Three darts administered by AIR did not discharge (20%; 95% CI = 4% to 48%); and results from these steers were excluded from analysis. Maximum plasma concentration (718, 702.6, and 755.5 µg/mL for SC, AIR, and CO2, respectively) and area under the concentration-time curve (17,885, 17,423, and 18,796 µg • h/mL for SC, AIR and CO, respectively) were similar and not significantly different between methods of administration. There was an effect of time (P = 0.0002), period (P = 0.0001), and interaction between method of administration and study period (P = 0.0210) on plasma concentration of CK. However, method of treatment (P = 0.6091), interaction between method and time (P = 0.6972), interaction between period and time (P = 0.6153), and 3-way interaction between method, period and time (P = 0.6804) were not different. Results suggest that PK of tulathromycin following delivery by RDD can be similar to subcutaneous injection; however, failure of RDD to discharge after delivery by some types of projectors can cause an important proportion of cattle to fail to receive drug as expected.

Quantitation of fumonisin B1 and B2 in feed using FMOC pre-column derivatization with HPLC and fluorescence detection.

Pre-column derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) was determined to be effective for quantitation of fumonisins B1 and B2 in feed. Liquid-solid extraction, clean-up using immunoaffinity solid phase extraction chromatography, and FMOC-derivatization preceded analysis by reverse phase HPLC with fluorescence. Instrument response was unchanged in the presence of matrix, indicating no need to use matrix-matched calibrants. Furthermore, high method recoveries indicated calibrants do not need to undergo clean-up to account for analyte loss. Established method features include linear instrument response from 0.04-2.5µg/mL and stable derivatized calibrants over 7days. Fortified cornmeal method recoveries from 0.1-30.0µg/g were determined for FB1 (75.1%-109%) and FB2 (96.0%-115.2%). Inter-assay precision ranged from 1.0%-16.7%. Method accuracy was further confirmed using certified reference material. Inter-laboratory comparison with naturally-contaminated field corn demonstrated equivalent results with conventional derivatization. These results indicate FMOC derivatization is a suitable alternative for fumonisins B1 and B2 quantitation in corn-based feeds.

Intramedullary screw fixation of the fifth metatarsal: an anatomic study and improved technique.

Intramedullary screw fixation has been found to be a reliable treatment for certain fractures of the fifth metatarsal. Techniques for this treatment have been described relying largely on intraoperative fluoroscopy. Ten human cadaver specimens had their fifth metatarsals osteotomized and underwent retrograde intramedullary pin placement. Anatomic landmarks and the location of the sural nerve in relation to this starting point were measured. The trajectory of a pin reducing the osteotomy was analyzed. Using the resultant starting point and guide pin trajectory, intramedullary screw placement was performed reliably without the aid of fluoroscopy. This study demonstrates that intramedullary screw fixation of proximal fifth metatarsal fractures may be performed with the use of anatomic landmarks, which decreases the amount of intraoperative fluoroscopy needed.