Measurement of Impact Forces on Teeth and Jaw when Wearing Sports Mouth Guards

The objective of this project is to accurately measure the forces the teeth and jaw experience when subjected to impact. For this purpose piezoelectric technology (PVDF), which converts voltage to force and vice versa can be used to measure forces applied to teeth. A PVDF cable is calibrated and used for measuring force along with a control measuring device (PCB Piezotronics). The method involves wrapping the PVDF cable around a 3D home-printed, customized denture. The cable was chosen due to the fact that it allows for adequate fit between mouth guard and denture. Two masses, a baseball and 2 lbs - 3D printed projectile, were dropped from a height of 1m onto the denture with and without mouth guard. Results showed a significant force absorption by the mouth guard (more than 50% of initial impact force). After several trials, (n=10 for each group, baseball with and without mouthguard, as well as 2lbs), it was found that the impact shock absorption by the mouth guard ranged between 60-70%. Figure 1 shows the values at which the denture was impacted, with and without a mouth guard for baseball and 2 lbm cylinder. Finally, FEA Analysis was also used to show the regional stress and strain along the denture.https://scholarscompass.vcu.edu/capstone/1201/thumbnail.jp

Carbon K-shell Photo Ionization of CO: Molecular frame angular Distributions of normal and conjugate shakeup Satellites

We have measured the molecular frame angular distributions of photoelectrons emitted from the Carbon K shell of fixed-in-space CO molecules for the case of simultaneous excitation of the remaining molecular ion. Normal and conjugate shake up states are observed. Photo electrons belonging to normal \Sigma -satellite lines show an angular distribution resembling that observed for the main photoline at the same electron energy. Surprisingly a similar shape is found for conjugate shake up states with \Pi -symmetry. In our data we identify shake rather than electron scattering (PEVE) as the mechanism producing the conjugate lines. The angular distributions clearly show the presence of a \Sigma -shape resonance for all of the satellite lines.Comment: 8 pages, 2 figure

Steering proton migration in hydrocarbons using intense few-cycle laser fields

Proton migration is a ubiquitous process in chemical reactions related to biology, combustion, and catalysis. Thus, the ability to control the movement of nuclei with tailored light, within a hydrocarbon molecule holds promise for far-reaching applications. Here, we demonstrate the steering of hydrogen migration in simple hydrocarbons, namely acetylene and allene, using waveform-controlled, few-cycle laser pulses. The rearrangement dynamics are monitored using coincident 3D momentum imaging spectroscopy, and described with a quantum-dynamical model. Our observations reveal that the underlying control mechanism is due to the manipulation of the phases in a vibrational wavepacket by the intense off-resonant laser field.Comment: 5 pages, 4 figure

Capture into Rydberg states and momentum distributions of ionized electrons

The yield of neutral excited atoms and low-energy photoelectrons generated by the electron dynamics in the combined Coulomb and laser field after tunneling is investigated. We present results of Monte-Carlo simulations built on the two-step semiclassical model, as well as analytic estimates and scaling relations for the population trapping into the Rydberg states. It is shown that mainly those electrons are captured into bound states of the neutral atom that due to their initial conditions (i) have moderate drift momentum imparted by the laser field and (ii) avoid strong interaction ("hard" collision) with the ion. In addition, it is demonstrated that the channel of capture, when accounted for in semiclassical calculations, has a pronounced effect on the momentum distribution of electrons with small positive energy. For the parameters that we investigated its presence leads to a dip at zero momentum in the longitudinal momentum distribution of the ionized electrons.Comment: 9 pages, 8 figures in one zip-archiv

Are we ready for a person-centered care model for patient- physician consultation? A survey from family physicians and their patients of East Mediterranean Region

Background: Person-centered care has long been identified as a key component of health systems and one of the six domains of quality. This study aimed to identify the perceptions of patients and physicians regarding person-centered care in the Eastern Mediterranean Region (EMR). Methods: A multicountry, cross-sectional study was conducted in 6 countries of EMR during July 2012 to September 2012. From each country, an expert Family Physician (FP) was identified and invited for the study. During the first phase, 190 FPs practising for at least 6 months were recruited. In the second phase, the recruited FPs approached 300 patients aged > 18 years with 1 or more recurring problems. Data analysis was conducted using SPSS version 19. Results: Of a total of 360 patients, 53% were between 25-40 years of age and the majority 55.7% were females. Among physicians, 66.8% were females and 72.1% had undergone specialization in Family Medicine from EMR. About 36% of the patients, while 62.6% of the physicians, preferred a person-centered care model of care. Among physicians, field of specialization (AOR= 0.7; 95% C.I: 0.3-0.9) and regularity in continuing medical education sessions (AOR= 0.3; 95% C.I: 0.1-0.5) were significant factors for preferring a person-centered care model. Educational status (AOR= 3.0; 95% C.I: 1.1- 7.9) was associated with a preference for person-centered care among patients. Conclusion: The results of the study highlight that a majority of physicians prefer person-centered care, while patients prefer a mix of both patient- and physician-centered care. Strategies should be developed that will help physicians and patients to embrace person-centered care practices

Master of Science

thesisTi-6Al-4V is an alloy that has been developed to be used in medical implants due to its compatibility with the human body. Additive manufacturing technology has also become useful in constructing human bone design (marrow) from Ti-6Al-4V, imitating bone function. This research focuses on studying mechanical properties of Ti-6Al-4V using powder laser bed fusion (PLBF). This thesis describes the lattice structure for Ti-6Al-4V and discusses the design and the properties of the material based on tensile testing and other tests. This thesis focuses on understanding the mechanical properties of Ti-6Al-4V by presenting a literature review and comparing the structural strengths of the lattice and the full solid. Then, the research examines the powder comprising the fabricated specimen, the design that was chosen, and the parameters that affect the design mechanical properties in the results. Also, part of the discussion discusses heat affected zones (HAZ) comparing welding to additive manufacturing (AM) as a micro-weld. This section reveals some of the answers about the variability of mechanical properties in AM technologies, especially in PLBF. Lastly, microstructure images and CT scan images were analyzed through Image J. The image processing helps relate theoretical data and experimental results to quantitative data acquired from image processing. After compiling the analyses from the various sources, a design model was created to enhance the investigation of mechanical properties by giving visual evidence to support the conclusions

Improving The adelic Version of The Minkowski-Hlawka Theorem

In this dissertation we take a method developed by Schmidt to improve the classical version of the Minkowski-Hlawka Theorem and extend that to certain number fields. This leads to an analogous improvement to the adelic Minkowski-Hlawka Theorem in certain cases. We also demonstrate that the adelic version, even in the case where the number field is the field of rational numbers, is more general than the classical version

Multi-word Items in Dictionaries from a Translator's Perspective

Translation dictionaries are the tools of translators who use them to transfer from the source text to the target text, as they use them whenever they encounter puzzling words. Thus, this research investigates the degree of usefulness of these dictionaries when rendering English and Arabic multi-word items, such as idioms, collocations, phrasal/prepositional verbs, and compounds/iḍāfas. The aforementioned multi-word items are known for their metaphorical meanings and fixed structures, as both characteristics cause confusion to the translator/foreign language learner. The usefulness of the translation dictionaries was determined based on two criteria. First, by evaluating the use of these dictionaries for the rendering of the aforementioned multi-word items in undergraduate translation and lexicography classes. Second, by assessing the lexicographical documentation and treatment of these items in those dictionaries. It has been concluded that the percentages of dictionary use in advanced classes of translation were higher, which indicates the awareness of the importance of dictionaries in these classes. In addition, students of Arabic-English translation classes used dictionaries less than the English-Arabic classes since they dealt with texts of their native language and that English multi-word items were more difficult to render than the Arabic ones. Moreover, findings show that Arabic multi-word items were treated better than the English multi-word items in their respective dictionaries even though the English-Arabic dictionaries document more than the Arabic-English dictionaries

Two Classes of Optimal Fourth-Order Iterative Methods Free from Second Derivative for Solving Nonlinear Equations

This work proposes new fourth-order iterative methods to solve non-linear equations   . The iterative methods proposed here are presented by modifications of a third-order iterative method to be two classes of optimal fourth order. Convergence analysis was done for the iterative methods proposed in this paper. Multiple numerical examples were taken to explain the accuracy and efficiency of the proposed iterative methods