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1. Deeply virtual Compton scattering cross section at high Bjorken $x_B$

Author

Georges, F., Rashad, M. N. H., Stefanko, A., Dlamini, M., Karki, B., Ali, S. F., Lin, P-J., Ko, H-S, Israel, N., Adikaram, D., Ahmed, Z., Albataineh, H., Aljawrneh, B., Allada, K., Allison, S., Alsalmi, S., Androic, D., Aniol, K., Annand, J., Atac, H., Averett, T., Gayoso, C. Ayerbe, Bai, X., Bane, J., Barcus, S., Bartlett, K., Bellini, V., Beminiwattha, R., Bericic, J., Biswas, D., Brash, E., Bulumulla, D., Campbell, J., Camsonne, A., Carmignotto, M., Castellano, J., Chen, C., Chen, J-P., Chetry, T., Christy, M. E., Cisbani, E., Clary, B., Cohen, E., Compton, N., Cornejo, J. C., Dusa, S. Covrig, Crowe, B., Danagoulian, S., Danley, T., De Persio, F., Deconinck, W., Defurne, M., Desnault, C., Di, D., Duer, M., Duran, B., Ent, R., Fanelli, C., Franklin, G., Fuchey, E., Gal, C., Gaskell, D., Gautam, T., Glamazdin, O., Gnanvo, K., Gray, V. M., Gu, C., Hague, T., Hamad, G., Hamilton, D., Hamilton, K., Hansen, O., Hauenstein, F., Henry, W., Higinbotham, D. W., Holmstrom, T., Horn, T., Huang, Y., Huber, G. M., Hyde, C., Ibrahim, H., Jen, C-M., Jin, K., Jones, M., Kabir, A., Keppel, C., Khachatryan, V., King, P. M., Li, S., Li, W. B., Liu, J., Liu, H., Liyanage, A., Magee, J., Malace, S., Mammei, J., Markowitz, P., McClellan, E., Mazouz, M., Meddi, F., Meekins, D., Mesik, K., Michaels, R., Mkrtchyan, A., Montgomery, R., Camacho, C. Muñoz, Myers, L. S., Nadel-Turonski, P., Nazeer, S. J., Nelyubin, V., Nguyen, D., Nuruzzaman, N., Nycz, M., Obretch, O. F., Ou, L., Palatchi, C., Pandey, B., Park, S., Park, K., Peng, C., Pomatsalyuk, R., Pooser, E., Puckett, A. J. R., Punjabi, V., Quinn, B., Rahman, S., Reimer, P. E., Roche, J., Sapkota, I., Sarty, A., Sawatzky, B., Saylor, N. H., Schmookler, B., Shabestari, M. H., Shahinyan, A., Sirca, S., Smith, G. R., Sooriyaarachchilage, S., Sparveris, N., Spies, R., Su, T., Subedi, A., Sulkosky, V., Sun, A., Thorne, L., Tian, Y., Ton, N., Tortorici, F., Trotta, R., Urciuoli, G. M., Voutier, E., Waidyawansa, B., Wang, Y., Wojtsekhowski, B., Wood, S., Yan, X., Ye, L., Ye, Z., Yero, C., Zhang, J., Zhao, Y., and Zhu, P.

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Experiment, Nuclear Experiment
Abstract

We report high-precision measurements of the Deeply Virtual Compton Scattering (DVCS) cross section at high values of the Bjorken variable $x_B$. DVCS is sensitive to the Generalized Parton Distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton Form Factors (CFFs) of the nucleon as a function of $x_B$, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

Published
2022
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2. Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

Author

Christy, M. E., Gautam, T., Ou, L., Schmookler, B., Wang, Y., Adikaram, D., Ahmed, Z., Albataineh, H., Ali, S. F., Aljawrneh, B., Allada, K., Allison, S. L., Alsalmi, S., Androic, D., Aniol, K., Annand, J., Arrington, J., Atac, H., Averett, T., Gayoso, C. Ayerbe, Bai, X., Bane, J., Barcus, S., Bartlett, K., Bellini, V., Beminiwattha, R., Bericic, J., Bhatt, H., Bhetuwal, D., Biswas, D., Brash, E., Bulumulla, D., Camacho, C. M., Campbell, J., Camsonne, A., Carmignotto, M., Castellanos, J., Chen, C., Chen, J-P., Chetry, T., Cisbani, E., Clary, B., Cohen, E., Compton, N., Cornejo, J. C., Dusa, S. Covrig, Crowe, B., Danagoulian, S., Danley, T., Deconinck, W., Defurne, M., Desnault, C., Di, D., Dlamini, M., Duer, M., Duran, B., Ent, R., Fanelli, C., Fuchey, E., Gal, C., Gaskell, D., Georges, F., Gilad, S., Glamazdin, O., Gnanvo, K., Gramolin, A. V., Gray, V. M., Gu, C., Habarakada, A., Hague, T., Hamad, G., Hamilton, D., Hamilton, K., Hansen, O., Hauenstein, F., Hernandez, A. V., Henry, W., Higinbotham, D. W., Holmstrom, T., Horn, T., Huang, Y., Huber, G. M., Hyde, C., Ibrahim, H., Israel, N., Jen, C-M., Jin, K., Jones, M., Kabir, A., Karki, B., Keppel, C., Khachatryan, V., King, P. M., Li, S., Li, W., Liu, H., Liu, J., Liyanage, A. H., Mack, D., Magee, J., Malace, S., Mammei, J., Markowitz, P., Mayilyan, S., McClellan, E., Meddi, F., Meekins, D., Mesick, K., Michaels, R., Mkrtchyan, A., Moffit, B., Montgomery, R., Myers, L. S., Nadel-Turonski, P., Nazeer, S. J., Nelyubin, V., Nguyen, D., Nuruzzaman, N., Nycz, M., Obrecht, R. F., Ohanyan, K., Palatchi, C., Pandey, B., Park, K., Park, S., Peng, C., Persio, F. D., Pomatsalyuk, R., Pooser, E., Puckett, A. J. R., Punjabi, V., Quinn, B., Rahman, S., Rashad, M. N. H., Riordan, S., Roche, J., Sapkota, I., Sarty, A., Sawatzky, B., Saylor, N. H., Shabestari, M. H., Shahinyan, A., Sirca, S., Smith, G. R., Sooriyaarachchilage, S., Sparveris, N., Spies, R., Stefanko, A., Su, T., Subedi, A., Sulkosky, V., Sun, A., Tan, Y., Thorne, L., Ton, N., Tortorici, F., Trotta, R., Uniyal, R., Urciuoli, G. M., Voutier, E., Waidyawansa, B., Wojtsekhowski, B., Wood, S., Yan, X., Ye, L., Ye, Z. H., Yero, C., Zhang, J., Zhao, Y. X., and Zhu, P.

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q$^2$) up to 15.75~\gevsq. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q$^2$ and double the range over which a longitudinal/transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q$^2$ and attributed to hard two-photon exchange (TPE) effects, extending to 8~(GeV/c)$^2$ the range of Q$^2$ for which a discrepancy is established at $>$95\% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q$^2$., Comment: 7 pages, 2 figures

Published
2021
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3. Deep exclusive electroproduction of $\pi^0$ at high $Q^2$ in the quark valence regime

Author

The Jefferson Lab Hall A Collaboration, Dlamini, M., Karki, B., Ali, S. F., Lin, P-J., Georges, F., Ko, H-S, Israel, N., Rashad, M. N. H., Stefanko, A., Adikaram, D., Ahmed, Z., Albataineh, H., Aljawrneh, B., Allada, K., Allison, S., Alsalmi, S., Androic, D., Aniol, K., Annand, J., Atac, H., Averett, T., Gayoso, C. Ayerbe, Bai, X., Bane, J., Barcus, S., Bartlett, K., Bellini, V., Beminiwattha, R., Bericic, J., Biswas, D., Brash, E., Bulumulla, D., Campbell, J., Camsonne, A., Carmignotto, M., Castellano, J., Chen, C., Chen, J-P., Chetry, T., Christy, M. E., Cisbani, E., Clary, B., Cohen, E., Compton, N., Cornejo, J. C., Dusa, S. Covrig, Crowe, B., Danagoulian, S., Danley, T., De Persio, F., Deconinck, W., Defurne, M., Desnault, C., Di, D., Duer, M., Duran, B., Ent, R., Fanelli, C., Franklin, G., Fuchey, E., Gal, C., Gaskell, D., Gautam, T., Glamazdin, O., Gnanvo, K., Gray, V. M., Gu, C., Hague, T., Hamad, G., Hamilton, D., Hamilton, K., Hansen, O., Hauenstein, F., Henry, W., Higinbotham, D. W., Holmstrom, T., Horn, T., Huang, Y., Huber, G. M., Hyde, C., Ibrahim, H., Jen, C-M., Jin, K., Jones, M., Kabir, A., Keppel, C., Khachatryan, V., King, P. M., Li, S., Li, W., Liu, J., Liu, H., Liyanage, A., Magee, J., Malace, S., Mammei, J., Markowitz, P., McClellan, E., Meddi, F., Meekins, D., Mesik, K., Michaels, R., Mkrtchyan, A., Montgomery, R., Camacho, C. Munoz, Myers, L. S., Nadel-Turonski, P., Nazeer, S. J., Nelyubin, V., Nguyen, D., Nuruzzaman, N., Nycz, M., Obretch, O. F., Ou, L., Palatchi, C., Pandey, B., Park, S., Park, K., Peng, C., Pomatsalyuk, R., Pooser, E., Puckett, A. J. R., Punjabi, V., Quinn, B., Rahman, S., Reimer, P. E., Roche, J., Sapkota, I., Sarty, A., Sawatzky, B., Saylor, N. H., Schmookler, B., Shabestari, M. H., Shahinyan, A., Sirca, S., Smith, G. R., Sooriyaarachchilage, S., Sparveris, N., Spies, R., Su, T., Subedi, A., Sulkosky, V., Sun, A., Thorne, L., Tian, Y., Ton, N., Tortorici, F., Trotta, R., Urciuoli, G. M., Voutier, E., Waidyawansa, B., Wang, Y., Wojtsekhowski, B., Wood, S., Yan, X., Ye, L., Ye, Z., Yero, C., Zhang, J., Zhao, Y., and Zhu, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of $x_B$ (0.36, 0.48 and 0.60) and $Q^2$ (3.1 to 8.4 GeV$^2$) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions $d\sigma_L/dt+\epsilon d\sigma_T/dt$, $d\sigma_{TT}/dt$, $d\sigma_{LT}/dt$ and $d\sigma_{LT'}/dt$ are extracted as a function of the proton momentum transfer $t-t_{min}$. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross-section throughout this kinematic range. The data are well described by calculations based on transversity Generalized Parton Distributions coupled to a helicity flip Distribution Amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Published
2020
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4. Automatic scoring of apnea and hypopnea events using blood oxygen saturation signals

Author

Rolon, R. E., Gareis, I. E., Larrateguy, L. D., Di Persia, L. E., Spies, R. D., and Rufiner, H. L.

Subjects
Electrical Engineering and Systems Science - Signal Processing, Computer Science - Computers and Society
Abstract

The obstructive sleep apnea-hypopnea (OSAH) syndrome is a very common and frequently undiagnosed sleep disorder. It is characterized by repeated events of partial (hypopnea) or total (apnea) obstruction of the upper airway while sleeping. This study makes use of a previously developed method called DAS-KSVD for multiclass structured dictionary learning to automatically detect individual events of apnea and hypopnea using only blood oxygen saturation signals. The method uses a combined discriminant measure which is capable of efficiently quantifying the degree of discriminability of each one of the atoms in a dictionary. DAS-KSVD was applied to detect and classify apnea and hypopnea events from signals obtained from the Sleep Heart Health Study database. For moderate to severe OSAH screening, a receiver operating characteristic curve analysis of the results shows an area under the curve of 0.957 and diagnostic sensitivity and specificity of 87.56% and 88.32%, respectively. These results represent improvements as compared to most state-of-the-art procedures. Hence, the method could be used for screening OSAH syndrome more reliably and conveniently, using only a pulse oximeter., Comment: 15 pages, 7 figures

Published
2020

5. A multi-class structured dictionary learning method using discriminant atom selection

Author

Rolón, R. E., Di Persia, L. E., Spies, R. D., and Rufiner, H. L.

Subjects
Computer Science - Machine Learning, Computer Science - Computer Vision and Pattern Recognition, Statistics - Machine Learning
Abstract

In the last decade, traditional dictionary learning methods have been successfully applied to various pattern classification tasks. Although these methods produce sparse representations of signals which are robust against distortions and missing data, such representations quite often turn out to be unsuitable if the final objective is signal classification. In order to overcome or at least to attenuate such a weakness, several new methods which incorporate discriminative information into sparse-inducing models have emerged in recent years. In particular, methods for discriminative dictionary learning have shown to be more accurate (in terms of signal classification) than the traditional ones, which are only focused on minimizing the total representation error. In this work, we present both a novel multi-class discriminative measure and an innovative dictionary learning method. For a given dictionary, this new measure, which takes into account not only when a particular atom is used for representing signals coming from a certain class and the magnitude of its corresponding representation coefficient, but also the effect that such an atom has in the total representation error, is capable of efficiently quantifying the degree of discriminability of each one of the atoms. On the other hand, the new dictionary construction method yields dictionaries which are highly suitable for multi-class classification tasks. Our method was tested with a widely used database for handwritten digit recognition and compared with three state-of-the-art classification methods. The results show that our method significantly outperforms the other three achieving good recognition rates and additionally, reducing the computational cost of the classifier., Comment: 18 pages, 8 figures and 3 tables

Published
2018

10. Learn-teach-learn: Evaluating a South African near-peer teaching programme

Author

Spies, R, Lee, H, Esack, I, Hollamby, R., and Viljoen, C

Abstract

Background. Near-peer teaching (NPT) programmes may benefit both student learners (SLs) and near-peer tutors (NTs). However, data evaluating NPT programmes in developing countries such as South Africa are lacking.Objectives. To evaluate the efficacy of an NPT programme in improving the knowledge and confidence of SLs and NTs, and to evaluate student perceptions of the NPT programme.Methods. An NPT programme in which clinical year students provided tutorials to pre-clinical year students was developed. Participants completed a knowledge-assessing multiple-choice questionnaire (MCQ) and a confidence-assessing questionnaire at commencement and conclusion of the programme. Participants also completed an evaluation at the end of the programme.Results. For 38 SLs, the median MCQ score improved from 58.9% at baseline to 78.6% at completion of the programme (p

Published
2022

11. Introducing the youth residential rehabilitation service: An operational and experiential overview of a psychosocial residential support option for young people experiencing mental health challenges

Author

Spies, R, Ennals, P, Egan, R, Hemus, P, Gonzales, R, Droppert, K, Tidhar, M, McMullan, S, Lessing, K, Wood, T, Bride, R, Bendall, S, Simmons, M, Spies, R, Ennals, P, Egan, R, Hemus, P, Gonzales, R, Droppert, K, Tidhar, M, McMullan, S, Lessing, K, Wood, T, Bride, R, Bendall, S, and Simmons, M

Abstract

AIM: A range of residential supports is available for young people experiencing mental health challenges. One Australian example is the Youth Residential Rehabilitation Service, which provides up to 12 months of intensive psychosocial support in a residential setting to young people aged 16-25 experiencing serious mental health challenges. This paper aimed to add to the scant literature on these services, describing the experiences of young people and staff members across the duration of a stay. METHODS: This study drew on collaborative autoethnography to engage and centre the direct lived experience of young people who had lived, and staff who had worked, in a Youth Residential Rehabilitation Service. RESULTS: We identified three phases that young people typically journey through during their stay at the service. The Arriving phase was marked by appropriate referrals, a warm welcome, a period of settling in and the development of trusting relationships. The Discovering phase saw young people identifying and enacting their strengths, hopes and values. Community connections were a focus of the Continuing phase as lives after service exit were envisioned and created. CONCLUSIONS: Drawing on collaborative autoethnography methods represents one approach to amplify the voice of young people in service design and evaluation. This paper richly described some of the possibilities and complexities of the Youth Residential Rehabilitation Service experience, which can be used to inform the service's pacing and structure of support.

Published
2022

12. Co-producing to understand what matters to young people living in youth residential rehabilitation services

Author

Ennals, P, Lessing, K, Spies, R, Egan, R, Hemus, P, Droppert, K, Tidhar, M, Wood, T, van Dijk, C, Bride, R, Asche, A, Bendall, S, Simmons, M, Ennals, P, Lessing, K, Spies, R, Egan, R, Hemus, P, Droppert, K, Tidhar, M, Wood, T, van Dijk, C, Bride, R, Asche, A, Bendall, S, and Simmons, M

Abstract

AIM: Residential group care is an important service for vulnerable young people experiencing mental health, substance abuse and/or behavioural challenges. Yet little is written about specific models and their outcomes, especially from the perspectives of the young people who use these services. This project aimed to explore what matters to young people living in a 12-month voluntary residential program for young people aged 16-25. METHODS: This participatory action research study was co-produced with Youth Residential Rehabilitation Service residents and staff as co-researchers. A steering group comprising residents, staff and researchers oversaw all research stages. 18 young people and 17 staff members participated in either individual or group interviews to discuss what was important in Youth Residential Rehabilitation Services. Data analysis drew on grounded theory techniques; subsequent codes and themes were refined in the steering group. RESULTS: We identified the 'change work' that young people were expected to do, and the milieu factors that created a supportive environment. As young people were figuring out their directions and learning new skills, they needed to be understood as the developing expert of their own lives. Real relationships with staff and other young people created a culture of belonging, safety and feeling known. These findings are metaphorically captured in the image of an egg. CONCLUSIONS: Our study highlights that real relationships between all Youth Residential Rehabilitation Service community members are central to creating the atmosphere of safety and belonging that enables healing and self-development to occur.

Published
2022

13. Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

Author

Christy, M. E., primary, Gautam, T., additional, Ou, L., additional, Schmookler, B., additional, Wang, Y., additional, Adikaram, D., additional, Ahmed, Z., additional, Albataineh, H., additional, Ali, S. F., additional, Aljawrneh, B., additional, Allada, K., additional, Allison, S. L., additional, Alsalmi, S., additional, Androic, D., additional, Aniol, K., additional, Annand, J., additional, Arrington, J., additional, Atac, H., additional, Averett, T., additional, Ayerbe Gayoso, C., additional, Bai, X., additional, Bane, J., additional, Barcus, S., additional, Bartlett, K., additional, Bellini, V., additional, Beminiwattha, R., additional, Bericic, J., additional, Bhatt, H., additional, Bhetuwal, D., additional, Biswas, D., additional, Brash, E., additional, Bulumulla, D., additional, Camacho, C. M., additional, Campbell, J., additional, Camsonne, A., additional, Carmignotto, M., additional, Castellanos, J., additional, Chen, C., additional, Chen, J-P., additional, Chetry, T., additional, Cisbani, E., additional, Clary, B., additional, Cohen, E., additional, Compton, N., additional, Cornejo, J. C., additional, Covrig Dusa, S., additional, Crowe, B., additional, Danagoulian, S., additional, Danley, T., additional, Deconinck, W., additional, Defurne, M., additional, Desnault, C., additional, Di, D., additional, Dlamini, M., additional, Duer, M., additional, Duran, B., additional, Ent, R., additional, Fanelli, C., additional, Fuchey, E., additional, Gal, C., additional, Gaskell, D., additional, Georges, F., additional, Gilad, S., additional, Glamazdin, O., additional, Gnanvo, K., additional, Gramolin, A. V., additional, Gray, V. M., additional, Gu, C., additional, Habarakada, A., additional, Hague, T., additional, Hamad, G., additional, Hamilton, D., additional, Hamilton, K., additional, Hansen, O., additional, Hauenstein, F., additional, Hernandez, A. V., additional, Henry, W., additional, Higinbotham, D. W., additional, Holmstrom, T., additional, Horn, T., additional, Huang, Y., additional, Huber, G. M., additional, Hyde, C., additional, Ibrahim, H., additional, Israel, N., additional, Jen, C-M., additional, Jin, K., additional, Jones, M., additional, Kabir, A., additional, Karki, B., additional, Keppel, C., additional, Khachatryan, V., additional, King, P. M., additional, Li, S., additional, Li, W., additional, Liu, H., additional, Liu, J., additional, Liyanage, A. H., additional, Mack, D., additional, Magee, J., additional, Malace, S., additional, Mammei, J., additional, Markowitz, P., additional, Mayilyan, S., additional, McClellan, E., additional, Meddi, F., additional, Meekins, D., additional, Mesick, K., additional, Michaels, R., additional, Mkrtchyan, A., additional, Moffit, B., additional, Montgomery, R., additional, Myers, L. S., additional, Nadel-Turonski, P., additional, Nazeer, S. J., additional, Nelyubin, V., additional, Nguyen, D., additional, Nuruzzaman, N., additional, Nycz, M., additional, Obrecht, R. F., additional, Ohanyan, K., additional, Palatchi, C., additional, Pandey, B., additional, Park, K., additional, Park, S., additional, Peng, C., additional, Persio, F. D., additional, Pomatsalyuk, R., additional, Pooser, E., additional, Puckett, A. J. R., additional, Punjabi, V., additional, Quinn, B., additional, Rahman, S., additional, Rashad, M. N. H., additional, Reimer, P. E., additional, Riordan, S., additional, Roche, J., additional, Sapkota, I., additional, Sarty, A., additional, Sawatzky, B., additional, Saylor, N. H., additional, Shabestari, M. H., additional, Shahinyan, A., additional, Širca, S., additional, Smith, G. R., additional, Sooriyaarachchilage, S., additional, Sparveris, N., additional, Spies, R., additional, Stefanko, A., additional, Su, T., additional, Subedi, A., additional, Sulkosky, V., additional, Sun, A., additional, Tan, Y., additional, Thorne, L., additional, Ton, N., additional, Tortorici, F., additional, Trotta, R., additional, Uniyal, R., additional, Urciuoli, G. M., additional, Voutier, E., additional, Waidyawansa, B., additional, Wojtsekhowski, B., additional, Wood, S., additional, Yan, X., additional, Ye, L., additional, Ye, Z. H., additional, Yero, C., additional, Zhang, J., additional, Zhao, Y. X., additional, and Zhu, P., additional

Published
2022
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14. Deeply virtual Compton scattering cross section at high Bjorken x_{B}

Author

Georges, F, Rashad, M. N. H., Stefanko, A, Dlamini, M, Karki, B, Ali, S. F., Lin, P-J, Ko, H-S, Israel, N, Adikaram, D, Ahmed, Z, Albataineh, H, Aljawrneh, B, Allada, K, Allison, S, Alsalmi, S, Androic, D, Aniol, K, Annand, John, Atac, H, Averett, T, Ayerbe Gayoso, C, Bai, X, Bane, J, Barcus, S, Bartlett, K, Bellini, V, Beminiwattha, R, Bericic, J, Biswas, D, Brash, E, Bulumulla, D, Campbell, J, Camsonne, A, Carmignotto, M, Castellano, J, Chen, C, Chen, J-P, Chetry, T, Christy, M. E., Cisbani, E, Clary, B, Cohen, E, Compton, N, Cornejo, J. C., Covrig Dusa, S, Crowe, B, Danagoulian, S, Danley, T, De Persio, F, Deconinck, W, Defurne, M, Desnault, C, Di, D, Duer, M, Duran, B, Ent, R, Fanelli, C, Franklin, G, Fuchey, E, Gal, C, Gaskell, D, Gautam, T, Glamazdin, O, Gnanvo, K, Gray, V. M., Gu, C, Hague, T, Hamad, G, Hamilton, David, Hamilton, K., Hansen, O, Hauenstein, F, Henry, W, Higinbotham, D. W., Holmstrom, T, Horn, T, Huang, Y, Huber, G. M., Hyde, C. E., Ibrahim, H, Jen, C-M, Jin, K, Jones, M, Kabir, A, Keppel, C, Khachatryan, V, King, P. M., Li, S, Li, W. B., Liu, J, Liu, H, Liyanage, A, Magee, J, Malace, S, Mammei, J, Markowitz, P, McClellan, E, Mazouz, M, Meddi, F, Meekins, D, Mesik, K, Michaels, R, Mkrtchyan, A, Montgomery, Rachel, Muñoz Camacho, C, Myers, L. S., Nadel-Turonski, P, Nazeer, S. J., Nelyubin, V, Nguyen, D, Nuruzzaman, N, Nycz, M, Obretch, O. F., Ou, L, Palatchi, C, Pandey, B, Park, S, Park, K, Peng, C, Pomatsalyuk, R, Pooser, E, Puckett, A. J. R., Punjabi, V, Quinn, B, Rahman, S, Reimer, P. E., Roche, J, Sapkota, I, Sarty, A, Sawatzky, B, Saylor, N. H., Schmookler, B, Shabestari, M. H., Shahinyan, A, Sirca, S, Smith, G. R., Sooriyaarachchilage, S, Sparveris, N, Spies, R, Su, T, Subedi, A, Sulkosky, V, Sun, A, Thorne, L, Tian, Y, Ton, N, Tortorici, F, Trotta, R, Urciuoli, G. M., Voutier, E, Waidyawansa, B, Wang, Y, Wojtsekhowski, B, Wood, S, Yan, X, Ye, L, Ye, Z, Yero, C, Zhang, J, Zhao, Y, Zhu, P, and Jefferson Lab Hall A Collaboration

Abstract

We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable x_{B}. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of x_{B}, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

Published
2022

16. Deep Exclusive Electroproduction of π0 at High Q2 in the Quark Valence Regime

Author

The Jefferson Lab Hall A Collaboration, Dlamini, M., Karki, B., Ali, S. F., Lin, P-J., Georges, F., Ko, H-S, Israel, N., Rashad, M. N. H., Stefanko, A., Adikaram, D., Ahmed, Z., Albataineh, H., Aljawrneh, B., Allada, K., Allison, S., Alsalmi, S., Androic, D., Aniol, K., Annand, J., Atac, H., Averett, T., Gayoso, C. Ayerbe, Bai, X., Bane, J., Barcus, S., Bartlett, K., Bellini, V., Beminiwattha, R., Bericic, J., Biswas, D., Brash, E., Bulumulla, D., Campbell, J., Camsonne, A., Carmignotto, M., Castellano, J., Chen, C., Chen, J-P., Chetry, T., Christy, M. E., Cisbani, E., Clary, B., Cohen, E., Compton, N., Cornejo, J. C., Dusa, S. Covrig, Crowe, B., Danagoulian, S., Danley, T., De Persio, F., Deconinck, W., Defurne, M., Desnault, C., Di, D., Duer, M., Duran, B., Ent, R., Fanelli, C., Franklin, G., Fuchey, E., Gal, C., Gaskell, D., Gautam, T., Glamazdin, O., Gnanvo, K., Gray, V. M., Gu, C., Hague, T., Hamad, G., Hamilton, D., Hamilton, K., Hansen, O., Hauenstein, F., Henry, W., Higinbotham, D. W., Holmstrom, T., Horn, T., Huang, Y., Huber, G. M., Hyde, C., Ibrahim, H., Jen, C-M., Jin, K., Jones, M., Kabir, A., Keppel, C., Khachatryan, V., King, P. M., Li, S., Li, W., Liu, J., Liu, H., Liyanage, A., Magee, J., Malace, S., Mammei, J., Markowitz, P., McClellan, E., Meddi, F., Meekins, D., Mesik, K., Michaels, R., Mkrtchyan, A., Montgomery, R., Camacho, C. Munoz, Myers, L. S., Nadel-Turonski, P., Nazeer, S. J., Nelyubin, V., Nguyen, D., Nuruzzaman, N., Nycz, M., Obretch, O. F., Ou, L., Palatchi, C., Pandey, B., Park, S., Park, K., Peng, C., Pomatsalyuk, R., Pooser, E., Puckett, A. J. R., Punjabi, V., Quinn, B., Rahman, S., Reimer, P. E., Roche, J., Sapkota, I., Sarty, A., Sawatzky, B., Saylor, N. H., Schmookler, B., Shabestari, M. H., Shahinyan, A., Sirca, S., Smith, G. R., Sooriyaarachchilage, S., Sparveris, N., Spies, R., Su, T., Subedi, A., Sulkosky, V., Sun, A., Thorne, L., Tian, Y., Ton, N., Tortorici, F., Trotta, R., Urciuoli, G. M., Voutier, E., Waidyawansa, B., Wang, Y., Wojtsekhowski, B., Wood, S., Yan, X., Ye, L., Ye, Z., Yero, C., Zhang, J., Zhao, Y., Zhu, P., Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Jefferson Lab Hall A

Subjects
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], momentum transfer dependence, helicity, High Energy Physics - Experiment, pi: distribution amplitude, generalized parton distribution: transversity, kinematics, pi0: electroproduction, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], quark: valence, polarization: transverse, High Energy Physics::Experiment, p: structure function, Nuclear Experiment, experimental results, photon: virtual, Jefferson Lab
Abstract

International audience; We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of xB (0.36, 0.48, and 0.60) and Q2 (3.1 to 8.4 GeV2) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσT/dt+εdσL/dt, dσTT/dt, dσLT/dt, and dσLT′/dt are extracted as a function of the proton momentum transfer t-tmin. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Published
2021
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17. Concept and development of an interactive tool for trial recruitment planning and management

Author

Spies, R., Siegfried, N., Myers-Franchi, Bronwyn, Grobbelaar, S.S., Spies, R., Siegfried, N., Myers-Franchi, Bronwyn, and Grobbelaar, S.S.

Abstract

Background: Predicting and monitoring recruitment in large, complex trials is essential to ensure appropriate resource management and budgeting. In a novel partnership between clinical trial investigators of the South African Medical Research Council and industrial engineers from the Stellenbosch University Health Systems Engineering and Innovation Hub, we developed a trial recruitment tool (TRT). The objective of the tool is to serve as a computerised decisions-support system to aid the planning and management phases of the trial recruitment process. Method: The specific requirements of the TRT were determined in several workshops between the partners. A Poisson process simulation model was formulated and incorporated in the TRT to predict the recruitment duration. The assumptions underlying the model were made in consultation with the trial team at the start of the project and were deemed reasonable. Real-world data extracted from a current cluster trial, Project MIND, based in 24 sites in South Africa was used to verify the simulation model and to develop the monitoring component of the TRT. Results: The TRT comprises a planning and monitoring component. The planning component generates different trial scenarios for predicted trial recruitment duration based on user inputs, e.g. number of sites, initiation delays. The monitoring component uses and analyses the data retrieved from the trial management information system to generate different levels of information, displayed visually on an interactive, user-friendly dashboard. Users can analyse the results at trial or site level, changing input parameters to see the resultant effect on the duration of trial recruitment. Conclusion: This TRT is an easy-to-use tool that assists in the management of the trial recruitment process. The TRT has potential to expedite improved management of clinical trials by providing the appropriate information needed for the planning and monitoring of the trial recruitment phase. This T

Published
2021

19. Indiscriminate friendliness in foster children: Associations with attachment security, foster parents' sensitivity, and child inhibitory control

Author

Schoemaker, N.K., Vermeer, H.J., Juffer, F., Spies, R., Ee, E. van, Maras, A., Alink, L.R.A., Schoemaker, N.K., Vermeer, H.J., Juffer, F., Spies, R., Ee, E. van, Maras, A., and Alink, L.R.A.

Abstract

Contains fulltext : 226861.pdf (publisher's version ) (Open Access), Indiscriminate friendliness (IF) is atypical behavior often seen in postinstitutionalized and foster children. The current exploratory study examined the associations of children's attachment security, parental sensitivity, and child inhibitory control with reported and observed IF in 60 family-reared, never-institutionalized foster children. IF was measured with a parent-report questionnaire (Indiscriminate Friendliness Questionnaire) and an observational measure (adapted version of the Stranger at the Door procedure; Bucharest Early Intervention Project). Attachment security and inhibitory control were related to reported IF (i.e., a secure attachment and poor inhibitory control were associated with higher levels of IF), but parental sensitivity was not. No associations were found between observed IF and attachment security, parental sensitivity, or inhibitory control. Thus, foster children with a secure attachment relationship may be more prone to socially interact with others including strangers, whereas better inhibitory control may serve as a buffer against IF but these results were found for reported IF only. More research is needed to gain more knowledge about different measures, other possible correlates, and underlying mechanisms of IF.

Published
2020

21. A multi-class structured dictionary learning method using discriminant atom selection

Author

Rol��n, R. E., Di Persia, L. E., Spies, R. D., and Rufiner, H. L.

Subjects
FOS: Computer and information sciences, Computer Science - Machine Learning, Statistics - Machine Learning, Computer Vision and Pattern Recognition (cs.CV), Computer Science - Computer Vision and Pattern Recognition, Machine Learning (stat.ML), Machine Learning (cs.LG)
Abstract

In the last decade, traditional dictionary learning methods have been successfully applied to various pattern classification tasks. Although these methods produce sparse representations of signals which are robust against distortions and missing data, such representations quite often turn out to be unsuitable if the final objective is signal classification. In order to overcome or at least to attenuate such a weakness, several new methods which incorporate discriminative information into sparse-inducing models have emerged in recent years. In particular, methods for discriminative dictionary learning have shown to be more accurate (in terms of signal classification) than the traditional ones, which are only focused on minimizing the total representation error. In this work, we present both a novel multi-class discriminative measure and an innovative dictionary learning method. For a given dictionary, this new measure, which takes into account not only when a particular atom is used for representing signals coming from a certain class and the magnitude of its corresponding representation coefficient, but also the effect that such an atom has in the total representation error, is capable of efficiently quantifying the degree of discriminability of each one of the atoms. On the other hand, the new dictionary construction method yields dictionaries which are highly suitable for multi-class classification tasks. Our method was tested with a widely used database for handwritten digit recognition and compared with three state-of-the-art classification methods. The results show that our method significantly outperforms the other three achieving good recognition rates and additionally, reducing the computational cost of the classifier., 18 pages, 8 figures and 3 tables

Published
2018

26. Learn-teach-learn: Evaluating a South African near-peer teaching programme.

Author

Spies, R., Lee, H., Esack, I., Hollamby, R., and Viljoen, C.

Subjects
*PEER teaching, *STUDENT attitudes, *MEDICAL students, *EDUCATIONAL standards, *CONFIDENCE, DEVELOPING countries
Abstract

Background. Near-peer teaching (NPT) programmes may benefit both student learners (SLs) and near-peer tutors (NTs). However, data evaluating NPT programmes in developing countries such as South Africa are lacking. Objectives. To evaluate the efficacy of an NPT programme in improving the knowledge and confidence of SLs and NTs, and to evaluate student perceptions of the NPT programme. Methods. An NPT programme in which clinical year students provided tutorials to pre-clinical year students was developed. Participants completed a knowledge-assessing multiple-choice questionnaire (MCQ) and a confidence-assessing questionnaire at commencement and conclusion of the programme. Participants also completed an evaluation at the end of the programme. Results. For 38 SLs, the median MCQ score improved from 58.9% at baseline to 78.6% at completion of the programme (p<0.001; d=1.3). The mean overall confidence score improved from 2.6/5 at baseline to 3.6/5 at completion (p<0.001; d=1.3). All SLs agreed that the NPT programme was a useful addition to the standard curriculum and that they would recommend the programme to other students at developmental level. The effect of the NPT programme was less pronounced for the 16 NTs, with median MCQ scores of 87.5% and 89.3% at baseline and completion of the programme, respectively (p=0.179; d=0.4). The mean overall confidence score improved from 3.8/5 at baseline to 4.2/5 at completion (p=0.004; d=1). Ninety-four percent of NTs agreed that their role as NTs reinforced their existing knowledge. Conclusion. NPT programmes may improve the knowledge and confidence of SLs, while consolidating the knowledge of NTs. The NTP programme was well received by medical students. In resource-limited settings, the effectiveness and acceptability of NPT make it an attractive adjunct to traditional teaching. [ABSTRACT FROM AUTHOR]

Published
2021
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28. HIV/Aids and psychosis: needs, challenges and support of affected mothers

Author

Spies, R., Sterkenburg, P.S., van Rensburg, E, Schuengel, C., Spies, R., Sterkenburg, P.S., van Rensburg, E, and Schuengel, C.

Abstract

Little is known about parenting in the context of HIV and psychosis, two co-existing conditions affecting many mothers in South Africa. In this study a mixed methods approach was used to firstly do qualitative investigation of the illness and parenting experiences of a case group of mothers living with HIV/AIDS and psychosis (n = 41). Secondly, the support networks of this group are compared with a control group of mothers with HIV/AIDS without psychosis (n = 44). Integrating qualitative and quantitative data highlight the emotional and physical disruption experienced by the case group that contribute to dysfunctional mother–child interactions. This experience may be detrimental to the child’s well-being and formation of attachment relationships. Healthy support networks may buffer these adversities. The availability of support figures is similar between the groups, but the case group has less spousal support. Paranoia associated with the case group predicted fewer support figures, thus emphasizing the vulnerability of this group of mothers and children.

Published
2017
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29. Attachment relationships of preschool-aged children of mothers with HIV and HIV-related psychosis

Author

12835471 - Spies, Abraham Gerhardus, 10194118 - Van Rensburg, Esmé, Spies, R., Sterkenburg, P.S., Van Rensburg, E., Schuengel, C., 12835471 - Spies, Abraham Gerhardus, 10194118 - Van Rensburg, Esmé, Spies, R., Sterkenburg, P.S., Van Rensburg, E., and Schuengel, C.

Abstract

Children from mothers with HIV-related psychosis are frequently raised in challenging contexts, yet the extent to which these children grow up in insecure or disordered attachment relationships is unknown. Using the Strange Situation Procedure the distribution of attachment relationships of children from mothers with HIV and psychosis (n = 45) was compared with children from mothers with HIV without psychosis (n = 41). No significant differences in the distributions were found between the two groups and attachment was not associated with specific psychotic symptomatology. Security of attachment was associated with more people providing the mother with emotional support, but only in the psychosis group. Disordered attachment (24%) was more often found in the total sample than in studies with other normal and high risk populations. Recommendations were made for future research about factors facilitating resilience in the children and on interventions increasing emotional support for affected mothers

Published
2016

39. Parenting difficulties of mothers with HIV/AIDS and HIV/AIDS-psychosis: a systematic literature review

Author

Spies, R., Schuengel, C., Sterkenburg, P.S., van Rensburg, E, and Clinical Child and Family Studies

Subjects
SDG 10 - Reduced Inequalities
Abstract

Aim: South Africa has the world’s highest prevalence of HIV/AIDS: in 2009 approximately 5.6 million people lived with HIV/AIDS, that is approximately 11% of the national population. HIV/AIDS is reported for 32.7% of the women aged between 25 and 29 years and 29.1% between 30 and 34 years. Psychotic disorder associated with HIV tends to surface when the illness has progressed to its later stages of development and affects an estimated 0.2 to 15% of HIV+ patients. Due to her chronic physical symptoms, but also due to her psychiatric symptoms the infectedmother may be less physically or emotionally available for her developing child or display confusing or frightening behavior, resulting in insecure or disorganized attachment relationships. This systematic literature review describes and synthesises studies addressing the parenting difficulties of mothers with HIV/AIDS and HIV/AIDS-psychosis in order to better understand its effects on parenting. Method: Academic Search Premier, Africa-Wide Information, CINAHL, ERIC, Health Source, Medline/Pubmed, PsycARTICLES and PsycINFO databases were searched via EBSCOhost for relevant articles from 1997 to 2011 resulting in 4370 articles. Findings from fifty-one peer reviewed articles were deemed relevant using defined inclusion criteria. Results: None of the studies simultaneously focusedon the topics HIV/AIDS, psychotic disorders and parenting. Studies identified a number of resilience factors that partly offset the risk of HIV/AIDS, namely an improved maternal bond and motherhood being a source of hope, esteem, motivation. Identified risks include parental concerns and stressors as well as physical illness and hospitalization; with social relations and support being a risk factor as well as a resiliency factor. Studies on parents with psychosis report decreased theory of mind and -mentalization, poor social relationships and –support networks, abnormal parental behavior, insensitive caregiving and problematic attachment representations which result in poor parenting outcomes. Conclusion: A moderation model integrates the results. Psychosis is likely to exacerbate the effects of HIV/AIDS on parenting. Increased awareness of the likelihood and importance of these symptoms may beused to improve care for families with a mother affected by HIV/AIDS-psychosis.

Published
2012
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41. Existence, Uniqueness and Stability of Solutions of Generalized Tikhonov-Phillips Functionals

Author

MINNESOTA UNIV MINNEAPOLIS INST FOR MATHEMATICS AND ITS APPLICATIONS, Mazzieri, G L, Spies, R D, Temperini, K G, MINNESOTA UNIV MINNEAPOLIS INST FOR MATHEMATICS AND ITS APPLICATIONS, Mazzieri, G L, Spies, R D, and Temperini, K G

Abstract

The Tikhonov-Phillips method is widely used for regularizing ill-posed inverse problems mainly due to the simplicity of its formulation as an optimization problem. The use of different penalizers in the functionals associated to the corresponding optimization problems has originated a variety other methods which can be considered as variants of the traditional Tikhonov-Phillips method of order zero. Such is the case for instance of the Tikhonov-Phillips method of order one, the total variation regularization method, etc. In this article we find sufficient conditions on the penalizers in generalized Tikhonov-Phillips functionals which guarantee existence and uniqueness and stability of the minimizers. The particular cases in which the penalizers are given by the bounded variation norm, by powers of seminorms and by linear combinations of powers of seminorms associated to closed operators, are studied. Several examples are presented and a few results on image restoration are shown.

Published
2011

48. Preliminary design of an auxiliary power unit for the space shuttle: Component and system configuration screening analysis

Author

Binsley, R. L, Maddox, J. P, Marcy, R. D, Siegler, R. S, and Spies, R

Subjects
Auxiliary Systems
Abstract

The auxiliary power unit (APU) for the space shuttle is required to provide hydraulic and electrical power on board the booster and orbiter vehicles. Five systems and their associated components, which utilize hot gas turbines to supply horsepower at gearbox output pads, were studied. Hydrogen-oxygen and storable propellants were considered for the hot gas supply. All APU's were required to be self-contained with respect to dissipating internally generated heat. These five systems were evaluated relative to a consistent criteria. The system supplied with high pressure gaseous hydrogen and oxygen was recommended as the best approach. It included a two-stage pressure-compounded partial-admission turbine, a propellant conditioning system with recuperation, a control system, and a gearbox. The gearbox output used was 240 hp. At the close of the study a 400 hp level was considered more appropriate for meeting the prime shuttle vehicle needs, and an in-depth analysis of the system at the 400 hp output level was recommended.

Published
1971

49. Variables in turbine erosion

Author

Baughman, J. R and Spies, R

Subjects
Physical Sciences
Abstract

Study of impact erosion in the operation of turbomachinery is undertaken to predict the results for particular designs. The test program investigates the effects of turbine stator blade shape, rotor blade shape, and variations in test conditions.

Published
1970

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