Design of the High-Speed Stereo Radiography System

Orthopaedic pathologies often involve disruption of the mechanical environment of a joint at/below the mm scale. The ability to measure biomechanical kinematics at the sub-mm scale is essential for obtaining valuable insight into pathologies, but small motions of the joints are difficult to quantify. Estimates of skeletal kinematics are commonly made from optical motion capture systems and markers placed on the skin. The error caused by external marker movement is largely avoided with x-ray motion capture. Dynamic radiography uses a series of x-ray images recorded at high-speed and captures in-vivo joint motion. Uncovering the mechanical foundation of orthopaedic pathologies requires accurate and high-speed kinematic measurement of in-vivo 3D, six DOF joint motion. To meet these aims, requirements were established to guide the design, construction, and validation of a high-speed stereo radiography (HSSR) system. The completed system is capable of imaging major joints from the ankle to the cervical spine

LTC4 synthase polymorphism modifies efficacy of botanical seed oil combination in asthma

Botanical seed oils reduce the generation of leukotrienes in patients with asthma. Our objective was to determine the efficacy of a botanical seed oil combination against airflow obstruction in asthma, and to determine the pharmacogenomic effect of the leukotriene C4 synthase (LTC4S) polymorphism A-444C. We conducted a randomized, double-blind, placebo-controlled, cross-over clinical trial in mild to moderate asthmatics to determine the change in FEV1 after 6 weeks of therapy with borage and echium seed oils versus corn oil placebo. We also examined the effect of the variant LTC4S -444C allele on the change in lung function. We did not identify a difference in FEV1 in the study cohort as a whole (n = 28), nor in the group of A homozygotes. In the C allele carriers (n = 9), FEV1 improved by 3% after treatment with borage and echium seed oils and declined by 4% after placebo corn oil (p = 0.02). All 9 C allele carriers demonstrated an improvement in their FEV1 on active treatment compared to placebo as compared to only 7 out of 19 A allele homozygotes (p = 0.007). We observed transient differences in ex vivo leukotriene generation from circulating basophils and granulocytes. We did not observe significant differences in urinary LTE4 levels. We conclude that compared to corn oil, a combination of borage and echium seed oils improves airflow obstruction in mild to moderate asthmatics who carry the variant allele in the LTC4S gene (A-444C). Botanical oil supplementation may have therapeutic potential in asthma if used in a personalized manner. Trial registration: This trial was registered at http://www.clinicaltrials.gov as NCT00806442

Probing the upper end of intracontinental earthquake magnitude: a prehistoric example from the Dzhungarian and Lepsy faults of Kazakhstan

The study of surface ruptures is key to understanding the earthquake occurrence of faults especially in the absence of historical events. We present a detailed analysis of geomorphic displacements along the Dzhungarian Fault, which straddles the border of China and Kazakhstan. We use digital elevation models derived from structure-from-motion analysis of Pléiades satellite imagery and drone imagery from specific field sites to measure surface offsets. We provide direct age constraints from alluvial terraces displaced by faulting and indirect dating from morphological analysis of the scarps. We find that the southern 250 km of the fault likely ruptured in a single event in the last 4,000 years, with displacements of 10–15 m, and potentially up to 20 m at one site. We infer that this Dzhungarian rupture is likely linked with a previously identified paleo-earthquake rupture on the Lepsy Fault through a system of splays in the intervening highlands. Though there are remaining uncertainties regarding consistency in age constraints between the two fault ruptures, most of the sites along the two faults are consistent with a most recent event 2,000–4,000 years ago. Rupture on the Dzhungarian Fault alone is likely to have exceeded Mw 8, and the combined Lepsy-Dzhungarian rupture scenario may have been up to Mw 8.4. Despite being at the upper end of known or inferred continental earthquake magnitudes, our proposed scenario combining the 375 km of the Dzhungarian and Lepsy ruptures yields a slip-to-length ratio consistent with global averages and so do other historical intracontinental earthquakes in Central Asia

Equine asthma: current understanding and future directions

The 2019 Havemeyer Workshop brought together researchers and clinicians to discuss the latest information on Equine Asthma and provide future research directions. Current clinical and molecular asthma phenotypes and endotypes in humans were discussed and compared to asthma phenotypes in horses. The role of infectious and non-infectious causes of equine asthma, genetic factors and proposed disease pathophysiology were reviewed. Diagnostic limitations were evident by the limited number of tests and biomarkers available to field practitioners. The participants emphasized the need for more accessible, standardized diagnostics that would help identify specific phenotypes and endotypes in order to create more targeted treatments or management strategies. One important outcome of the workshop was the creation of the Equine Asthma Group that will facilitate communication between veterinary practice and research communities through published and easily accessible guidelines and foster research collaboration

The impact of FADS genetic variants on ω6 polyunsaturated fatty acid metabolism in African Americans

<p>Abstract</p> <p>Background</p> <p>Arachidonic acid (AA) is a long-chain omega-6 polyunsaturated fatty acid (PUFA) synthesized from the precursor dihomo-gamma-linolenic acid (DGLA) that plays a vital role in immunity and inflammation. Variants in the Fatty Acid Desaturase (<it>FADS</it>) family of genes on chromosome 11q have been shown to play a role in PUFA metabolism in populations of European and Asian ancestry; no work has been done in populations of African ancestry to date.</p> <p>Results</p> <p>In this study, we report that African Americans have significantly higher circulating levels of plasma AA (p = 1.35 × 10^-48) and lower DGLA levels (p = 9.80 × 10^-11) than European Americans. Tests for association in N = 329 individuals across 80 nucleotide polymorphisms (SNPs) in the Fatty Acid Desaturase (<it>FADS</it>) locus revealed significant association with AA, DGLA and the AA/DGLA ratio, a measure of enzymatic efficiency, in both racial groups (peak signal p = 2.85 × 10^-16in African Americans, 2.68 × 10^-23in European Americans). Ancestry-related differences were observed at an upstream marker previously associated with AA levels (rs174537), wherein, 79-82% of African Americans carry two copies of the G allele compared to only 42-45% of European Americans. Importantly, the allelic effect of the G allele, which is associated with <it>enhanced </it>conversion of DGLA to AA, on enzymatic efficiency was similar in both groups.</p> <p>Conclusions</p> <p>We conclude that the impact of <it>FADS </it>genetic variants on PUFA metabolism, specifically AA levels, is likely more pronounced in African Americans due to the larger proportion of individuals carrying the genotype associated with increased FADS1 enzymatic conversion of DGLA to AA.</p

Holocene sea level fluctuations and coastal evolution in the central Algarve (southern Portugal)

In Armação de Pêra Bay, southern Portugal, environmental changes during the Holocene can be interpreted based on the morphological and sedimentological similarities between older geomorphic features (cemented beach and dune rocks) and present coastal features. Using knowledge of the present beach and dune processes, we propose a two-step model for the evolution of Armação de Pêra Bay. First, during the rapid sea level rise between about 8800 and 6600 yr cal BP, the bay changed from a positive to a negative budget littoral cell and transgressive dunes formed, favoured by drought conditions. At about 5000 yr cal BP, during a sea level maximum, beach width was less than the critical fetch and dunes stabilized and underwent cementation during the wetter Atlantic climatic event. The second phase of dune accumulation started at about 3200 yr cal BP, due to a regression of sea level during which the bay changed back to a positive budget littoral cell in which beach width was greater than the critical fetch. Currently, the beach width is less than the critical fetch, dunes are inactive, and the sedimentary budget is negative due to sediment storage in local river systems.Fundação para a Ciência e a Tecnologia. FEDER, and OE (Project POCTI/CTA/34162/2000

Fabrication and characterization of Ni-Mn-Ga ferromagnetic shape-memory alloy composites

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2002.Includes bibliographical references (leaves 46-48).Ferromagnetic shape-memory alloys (FSMAs) are a recently-developed class of active materials which show large extensional strains when a magnetic field is applied. Shear strains of 6% have been observed at room temperature in martensitic Ni-Mn-Ga single crystals. The strain effect in Ni-Mn-Ga FSMAs is a result of twin boundary motion in the martensite phase, and can be induced by either field or stress. Most Ni-Mn-Ga FSMA research so far has focused on actuation in single crystals. However, the mechanical loss inherent to twin boundary motion also makes this material attractive for energy absorption/vibration damping applications. This thesis describes the preliminary investigation of FSMA/polymer composites for eventual use in vibration damping, and should serve as a stepping stone toward further studies. The research moved through four stages: suction-casting polycrystalline Ni-Mn-Ga alloys with suitable target compositions, processing the polycrystalline material into powder, fabricating FSMA/polymer composites, and preliminary characterization of the stress-strain behavior of these composites. Suction casting produced three polycrystalline alloys which all showed significant variance from the target compositions as well as a high degree of compositional inhomogeneity. From the composition, structural analysis, and magnetic characterization, it was determined that Alloy 1 was martensite at room temperature, while Alloys 2 and 3 were austenitic. Alloy 3 showed a martensite transition temperature around 10° C. While only one of the three alloys shows a majority of martensite at room temperature, it is likely that the powders made from the polycrystalline material cover a wide range of compositions, so results concerning the structure of the powders reflect only the major phase present. The powders were mixed with urethane polymer at powder volume fractions of 10%, 20%, and 30%, followed by curing in a 4.2 kOe field to align the particles. Scanning electron microscopy and magnetic characterization confirmed the alignment of particles into chains within the polymer matrix. The dynamic stress-strain behavior of composites was characterized for low stresses at various frequencies. The static stress-strain behavior of the composites under compressive loading to stresses of 10 MPa was also characterized. In the FSMA/polymer composite samples, the first compressive loading test gave a stress/strain curve which is linear with one modulus up to a threshold stress. Beyond this threshold stress, the curve is linear but with a smaller modulus. Successive compressive stress-strain curves exhibited a linear stress/strain relationship with a modulus value between those of the two regions in the first test, with some hysteresis in the stress-strain response present between the first and second tests. A urethane sample and a urethane/20% volume fraction Al powder composite, by comparison, showed only linear stress-strain behavior with no significant changes between the first and second compressive loading tests. It is likely that the observed stress-strain behavior of the FSMA composites derives from stress-induced twin boundary motion in the martensite phase present.by Robin H.C. Ivester.S.B