Coherent π^0 photoproduction on the deuteron up to 4 GeV

The differential cross section for ^2H(γ,d)π^0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions

The Jefferson Lab Frozen Spin Target

A frozen spin polarized target, constructed at Jefferson Lab for use inside a large acceptance spectrometer, is described. The target has been utilized for photoproduction measurements with polarized tagged photons of both longitudinal and circular polarization. Protons in TEMPO-doped butanol were dynamically polarized to approximately 90% outside the spectrometer at 5 T and 200--300 mK. Photoproduction data were acquired with the target inside the spectrometer at a frozen-spin temperature of approximately 30 mK with the polarization maintained by a thin, superconducting coil installed inside the target cryostat. A 0.56 T solenoid was used for longitudinal target polarization and a 0.50 T dipole for transverse polarization. Spin-lattice relaxation times as high as 4000 hours were observed. We also report polarization results for deuterated propanediol doped with the trityl radical OX063.Comment: 11 pages, 12 figures, preprint submitted to Nuclear Instruments and Methods in Physics Research, Section

Mechanistic Insights into Glucan Phosphatase Activity against Polyglucan Substrates

Glucan phosphatases are central to the regulation of starch and glycogen metabolism. Plants contain two known glucan phosphatases, Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2), which dephosphorylate starch. Starch is water-insoluble and reversible phosphorylation solubilizes its outer surface allowing processive degradation. Vertebrates contain a single known glucan phosphatase, laforin, that dephosphorylates glycogen. In the absence of laforin, water-soluble glycogen becomes insoluble, leading to the neurodegenerative disorder Lafora Disease. Because of their essential role in starch and glycogen metabolism glucan phosphatases are of significant interest, yet a comparative analysis of their activities against diverse glucan substrates has not been established. We identify active site residues required for specific glucan dephosphorylation, defining a glucan phosphatase signature motif (CζAGΨGR) in the active site loop. We further explore the basis for phosphate position-specific activity of these enzymes and determine that their diverse phosphate position-specific activity is governed by the phosphatase domain. In addition, we find key differences in glucan phosphatase activity toward soluble and insoluble polyglucan substrates, resulting from the participation of ancillary glucan-binding domains. Together, these data provide fundamental insights into the specific activity of glucan phosphatases against diverse polyglucan substrates

Prosthetic Knee

Amputations, specifically lower limb amputations, are common in Sub Saharan Africa and across the broader global community largely due to infection and disease. Our project, The Prosthetic Knee Team, partners with the orthopedic workshop at the CURE International Hospital in Kijabe, Kenya to create a prosthetic knee design for a specific type of amputation known as a Knee Disarticulation (also called through-knee). Currently, the orthopedic workshop is only able to provide one very expensive prosthetic knee option for these patients, and they often elect to undergo a second surgery, a trans-femoral amputation, because the cost of the second surgery and trans-femoral prosthesis combined is less than the currently available through-knee prosthetic. The goal of our project is to provide the orthopedic workshop with a manufacturable prosthetic knee design that provides through-knee amputees with a cheaper prosthetic option and removes the need to have a second amputation above the knee. Throughout the past two semesters, our focus was on organizing collected data, researching knee-disarticulations, and communicating with our client to more fully understand the scope of our project. After determining that moving forward our project will be manufacturing the prosthetic knees at Messiah College’s machine shop and shipping them to CURE Kenya to be fit on patients, we began to brainstorm potential design ideas. We are presently working on modifying and improving our chosen design to best meet all of the specifications laid out by our partner. Those specifications include minimized thigh-lengthening, low weight, maximized stability and durability, and aesthetically pleasing.https://mosaic.messiah.edu/engr2020/1017/thumbnail.jp

Force Characterization and Manufacturing of a Dynamic Unilateral Clubfoot Brace

Clubfoot is a musculoskeletal birth defect characterized by an inward twisting of an infant’s feet. Currently, a series of casts are used to correct the clubfoot, and a boots-and-bar brace is used to maintain the correction. However, this method has concerns with compliance, comfort, and social stigma. Hope Walks and their clinic in Kijabe, Kenya are interested in implementing a new maintenance brace that addresses these concerns. Mr. Jerald Cunningham, CPO, designed and is utilizing a unilateral clubfoot maintenance brace called the Cunningham Clubfoot Brace. He asserts his brace reduces treatment time, lessens social stigma, and increases child mobility. However, to date, there is not enough published research on its biomechanics and patient success rates to confirm his findings. The Cunningham Clubfoot Brace Collaboratory project seeks to validate the effectiveness of the Cunningham design through biomedical testing and increase brace availability through sustainable manufacturing. To do this, the team is measuring the biomechanical forces applied by the brace with multiple force sensor systems and an infant foot model. The team is assisting Mr. Cunningham in his plans to use injection molding to increase brace production by scanning and creating CAD files of the brace. The team is also completing a failure and reuse analysis of the Cunningham Brace for the clinic in Kijabe. Furthermore, the ongoing clinical study at CURE International\u27s hospital in Kijabe, Kenya, and Dr. Emily Farrar’s research paper will provide greater insight into the effectiveness of the Cunningham Brace. These collaborative efforts will allow for further understanding of the effectiveness of the Cunningham Brace and its acceptance as an alternative clubfoot maintenance brace.https://mosaic.messiah.edu/engr2021/1001/thumbnail.jp

Force Characterization and Manufacturing of a Dynamic Unilateral Clubfoot Brace

Clubfoot is a musculoskeletal birth defect characterized by an inward twisting of an infant’s feet. Currently, a series of casts are used to correct clubfoot and the Steenbeek brace is used to maintain the correction. However, this method has issues with compliance, comfort, and social stigma. Mr. Jerald Cunningham, CPO, designed and is utilizing a unilateral clubfoot maintenance brace called the Cunningham Clubfoot Brace. He expects his brace to reduce treatment time, lessen social stigma, and increase child mobility. Hope Walks, in Kijabe, Kenya, is interested in implementing this new maintenance brace at their clinics. However, there is not enough published research on its biomechanics and patient success rates to confirm Mr. Cunningham’s findings. The Cunningham Clubfoot Brace Collaboratory project seeks to validate the effectiveness of this design through biomedical testing and increase brace accessibility through sustainable manufacturing. The team is measuring the biomechanical forces applied by the brace with multiple force sensors on the Cunningham and Steenbeek braces. Mr. Cunningham plans to use injection molding to increase brace production. The team is completing Finite Element Analysis to determine how the brace’s properties change with injection molding. The team is also completing fatigue analysis with the Cunningham Brace to quantify its reusability. Furthermore, the clinical study in Kenya and Dr. Emily Farrar’s retrospective research paper will contribute to the published research on the Cunningham Brace. The collaborative efforts of the team will increase further understanding of the Cunningham Brace and its acceptance as an alternative clubfoot maintenance brace.https://mosaic.messiah.edu/engr2022/1002/thumbnail.jp

First Measurement of the Helicity Asymmetry E in ƞ Photoproduction on the Proton

Results are presented for the first measurement of the double-polarization helicity asymmetry E for the ƞ photoproduction reaction ɣp -\u3e ηp. Data were obtained using the FROzen Spin Target (FROST) with the CLAS spectrometer in Hall B at Jefferson Lab, covering a range of center-of-mass energy W from threshold to 2.15 GeV and a large range in center-of-mass polar angle. As an initial application of these data, the results have been incorporated into the Jülich-Bonn model to examine the case for the existence of a narrow N* resonance between 1.66 and 1.70 GeV. The addition of these data to the world database results in marked changes in the predictions for the Eobservable from that model. Further comparison with several theoretical approaches indicates these data will significantly enhance our understanding of nucleon resonances