Three-dimensional (3D) Fast Neutron Tomography at the Low Energy Neutron Source (LENS)

AbstractWe have constructed a neutron imaging station at the Low Energy Neutron Source (LENS), located within the Center for the Exploration of Energy and Matter at Indiana University. In contrast to many existing neutron imaging stations, we utilize a broad range of neutron energies, extending into the fast neutron regime, to take advantage of the higher fluxes and larger penetrating power of these high-energy neutrons. The imaging station consists of a collimator to define the beam, a rotating sample stage, and a cooled charge-coupled device camera (Alta U6) using a scintillator. A LiF + ZnS screen is used to produce scintillation light. Typical image collection times are a few seconds for a aperture to sample distance ratio of 100, yielding a spatial resolution of 0.2 × 0.2 mm2. Examples of the scanned and calculated image are presented

A continuous isotropic-nematic liquid crystalline transition of F-actin solutions

The phase transition from the isotropic (I) to nematic (N) liquid crystalline suspension of F-actin of average length $3~\mu$m or above was studied by local measurements of optical birefringence and protein concentration. Both parameters were detected to be continuous in the transition region, suggesting that the I-N transition is higher than 1st order. This finding is consistent with a recent theory by Lammert, Rokhsar & Toner (PRL, 1993, 70:1650), predicting that the I-N transition may become continuous due to suppression of disclinations. Indeed, few line defects occur in the aligned phase of F-actin. Individual filaments in solutions of a few mg/ml F-actin undergo fast translational diffusion along the filament axis, whereas both lateral and rotational diffusions are suppressed.Comment: 4 pages with 4 figures. Submitted to Physical Review Letter

Natural Radioactivity and Geological Influence on Subsurface Layers at Kubwa and Gosa Area of Abuja, Northcentral Nigeria

The concentration of 238U, 232Th and 40K in rock samples were analysed using gamma ray spectrometry. In Kubwa, the concentration ranges from 15 to 52 Bq kg-1 for 238U, 32 to 84 Bq kg-1 for 232Th and 119 to 705 for 40K Bq kg-1. In Gosa area, the concentration of 238U ranges from 23 to 30 Bq kg-1, 232Th varied from 48 to 76 Bq kg-1, and 40K varied from 438 to 820 Bq kg-1. The dose rate, radium equivalent activity and annual effective dose rate at Kubwa and Gosa were calculated and compared with international standard values

An Overview of the Field of Semiotics

AbstractThe quantitative increase in recent years of research into semiotics, among other methods of reading works of art, is notable. Since semiotics is the act of reading as based on a meta-language that is constructed and grounded in logic, understanding the methods applied by the field requires time and experience. In addition, the application of models that differ in relation to each other under different schools of thought and under different names makes its yet more difficult to comprehend the field of semiotics. Despite the different models that are available, approaches display certain commonalities as they are born of the same foundations and objectives. This study will aim to pinpoint the common aspects of the intellectual foundations, methods, objectives and research limitations of the different schools of thought and the models that are involved in the study of semiotics

Statistical properties of thermodynamically predicted RNA secondary structures in viral genomes

By performing a comprehensive study on 1832 segments of 1212 complete genomes of viruses, we show that in viral genomes the hairpin structures of thermodynamically predicted RNA secondary structures are more abundant than expected under a simple random null hypothesis. The detected hairpin structures of RNA secondary structures are present both in coding and in noncoding regions for the four groups of viruses categorized as dsDNA, dsRNA, ssDNA and ssRNA. For all groups hairpin structures of RNA secondary structures are detected more frequently than expected for a random null hypothesis in noncoding rather than in coding regions. However, potential RNA secondary structures are also present in coding regions of dsDNA group. In fact we detect evolutionary conserved RNA secondary structures in conserved coding and noncoding regions of a large set of complete genomes of dsDNA herpesviruses.Comment: 9 pages, 2 figure

A Modular Functional Electrical Stimulation (FES) System for Gait Assistance in Pediatric Cerebral Palsy

Foot drop, the inability to lift the forefoot during gait, is a common symptom of disorders such as diabetes, stroke, spina bifida, and cerebral palsy. This condition makes walking difficult and unsafe, often resulting in stumbles and falls due to lack of ground clearance. The current standard of care is orthotic bracing, which presents donning and doffing challenges, restricts ankle motion, and contributes to social stigma in many parts of the world. Functional electrical stimulation (FES) is an alternative approach which uses small amounts of electrical current delivered through skin-surface electrodes to stimulate peripheral nerves, thus generating muscle contraction and ultimately functional movement of a human limb. When packaged in a wearable device with onboard sensors capable of detecting gait phase, stimulation current can be applied to the lower leg to cause the foot to lift during the swing phase of gait. While several FES foot-drop systems are commercially available, they cost upward of $13,000 and provide a level of adjustability and complexity not needed for many conditions. The Messiah FES team is working to develop a low-cost, portable, easy-to-use, and durable electrical stimulation device to restore legged ambulation to children with mobility impairments resulting from cerebral palsy, spina bifida, and other conditions with similar effects. Our clinical partner is CURE Ethiopia, with our primary contacts being Dr. Tim Nunn and Dr. Laurence Wicks at the CURE Ethiopia Children\u27s Hospital in Addis Ababa, Ethiopia. Funding for this work provided by The Collaboratory for Strategic Partnerships and Applied Research.https://mosaic.messiah.edu/engr2022/1007/thumbnail.jp

Haemophilus influenzae type b reemergence after combination immunization

An increase in Haemophilus influenzae type b (Hib) in British children has been linked to the widespread use of a diphtheria/tetanus/acellular pertussis combination vaccine (DTaP-Hib). We measured anti-polyribosyl-ribitol phos- phate antibody concentration and avidity before and after a Hib booster in 176 children 2–4 years of age who had received 3 doses of DTP-Hib (either DT whole cell pertus- sis-Hib or DTaP-Hib) combination vaccine in infancy. We also measured pharyngeal carriage of Hib. Antibody con- centrations before and avidity indices after vaccination were low (geometric mean concentration 0.46μg/mL, 95% confidence interval [CI] 0.36–0.58; geometric mean avidity index 0.16, 95% CI 0.14–0.18) and inversely related to the number of previous doses of DTaP-Hib (p = 0.02 and p<0.001, respectively). Hib was found in 2.1% (95% CI 0.7%–6.0%) of study participants. Our data support an association between DTaP-Hib vaccine combinations and clinical Hib disease through an effect on antibody concen- tration and avidit

Supersymmetry in carbon nanotubes in a transverse magnetic field

Electron properties of Carbon nanotubes in a transverse magnetic field are studied using a model of a massless Dirac particle on a cylinder. The problem possesses supersymmetry which protects low energy states and ensures stability of the metallic behavior in arbitrarily large fields. In metallic tubes we find suppression of the Fermi velocity at half-filling and enhancement of the density of states. In semiconducting tubes the energy gap is suppressed. These features qualitatively persist (although to a smaller degree) in the presence of electron interactions. The possibilities of experimental observation of these effects are discussed.Comment: A new section on electron interaction effects added and explanation on roles of supersymmetry expanded. Revtex4, 6 EPS figure file

Anderson localization of polaron states

Using the vanishing of the typical polaron tunneling rate as an indicator of the breakdown of itinerancy, we study the localization of polaron states in a generic model for a disordered polaronic material. We find that extremely small disorder causes an Anderson localization of small polaron states. However, the ratio between the critical disorder strength needed to localize all states in the polaron band and the renormalized bandwidth is not necessarily smaller than for a bare electron.Comment: 4 pages, 3 figure