Initial Codebook Research Articles

Roadway design and construction in infrastructure limited contexts: a risk breakdown structure

The United Nation's sustainable development goals prioritize roadway development, as it is necessary for socio-economic prosperity. Despite rapid growth in the industry, progress has been crippled by budget and schedule overruns. There is often a lack of knowledge regarding risks that could impact project success. A content analysis of published research is performed to construct a preliminary risk identification and analysis framework—in the form of an initial risk breakdown structure (RBS) and codebook. They include 16 subcategories within the following six categories: ‘construction & planning’, ‘economic & financial’, ‘regulatory & legal’, ‘equipment, materials, & land’, ‘site disposition’, and ‘relations & recruitment’. This study provides researchers and project parties—including owners, contractors, consultants, and financial institutions—with a starting point to discuss and identify context-specific risks. It also suggests areas for future research.

Emergency department staff perceptions about the care of children with mental health conditions

ObjectiveThe number of children with mental health (MH) conditions who present to the emergency department (ED) is increasing. This study aimed to gain insight into the lived experiences of ED staff caring for children with MH conditions and to understand perceptions of current ED resources and what is needed to optimize care. MethodsThis was a qualitative study informed by complexity science theory utilizing a phenomenological approach. We used purposeful sampling from urban and nonurban EDs with varying pediatric volume. Participants were pediatric emergency care coordinators and other ED staff. Semi-structured interviews were completed. The initial codebook was created using a concept driven approach. Constant comparative analysis and deductive reasoning was employed for thematic analysis. ResultsThematic saturation by consensus was achieved with 24 interviews. Analysis found an overarching theme of moral distress of ED staff, compounded by frustration with barriers to care and perceptions of negative impact on care of other ED patients. Participants suggested the need for creation of patient, caregiver, ED staff, and ED leadership resources to enhance care. ConclusionsED staff perceive children with MH conditions experience significant barriers to optimal care in the ED, which causes ED provider moral distress. Additionally, other ED patients are perceived to be subsequently negatively impacted. Our findings highlight urgency for funding for more resources that are dedicated to children in the ED setting to ensure both safe, patient-centered care, and to reduce the distress described by ED staff who care for them.

557-P: Patient and Caregiver Experiences during Severe Hypoglycemia: A Qualitative Assessment

Among people with diabetes (PWD) using insulin, severe hypoglycemia (SH) can be a life threatening complication, if untreated. The personal experiences of SH from the perspective of PWD and their caregivers (CG) are not well characterized. This study assessed the perceptions of the event and decision-making processes of PWD (T1D n=36; T2D n=24) and their CGs during SH.In-depth one-on-one telephone interviews were conducted with dyads of US PWD and CGs (n=120). An initial synopsis and inductive codebook schema were used to analyze the data with 2 independent coders (kappa=0.87-0.89). Themes were developed from the codes, and codes were re-mapped to the themes.The four themes included: (1) CGs scramble to do the right thing and support PWD in treating SH. (2) Decision-making capacity is impaired during a SH event (SHE), often a panicked time. (3) Discussion with healthcare providers (HCPs) about SH, and particularly about treatment, is limited. (4) PWD and CGs learn to manage SH through their own experiences and frequently make lifestyle changes to prevent and treat future events. See Exhibit for details.This study finds that SHEs are characterized by high intensity emotions for PWD and CGs that can impair decision-making. Additionally, much of PWD and CG knowledge about SH treatment derives from prior experience rather than HCP guidance, suggesting a need for more proactive discussions with HCPs regarding SH management.View largeDownload slideView largeDownload slide DisclosureH. L. Stuckey: Consultant; Self; Eli Lilly and Company, Consultant; Spouse/Partner; Eli Lilly and Company. U. Desai: Consultant; Self; Eli Lilly and Company. S. B. King: Consultant; Self; Eli Lilly and Company. L. Popadic: Consultant; Self; Eli Lilly and Company. W. Levinson: Consultant; Self; Eli Lilly and Company. N. Kirson: Consultant; Self; Eli Lilly and Company. E. R. Hankosky: Employee; Self; Eli Lilly and Company, Stock/Shareholder; Self; Eli Lilly and Company. B. Mitchell: Employee; Self; Eli Lilly and Company, Stock/Shareholder; Self; Eli Lilly and Company, Stock/Shareholder; Spouse/Partner; Eli Lilly and Company.FundingEli Lilly and Company

Perceptions and experiences of older patients and healthcare professionals regarding shared decision-making in pulmonary rehabilitation: A qualitative study

Objective: To understand the perceptions and experiences of older patients with chronic obstructive pulmonary disease (COPD) and healthcare professionals (HCPs) regarding shared decision-making in pulmonary rehabilitation (PR). Design: A qualitative study using single, semi-structured interviews, and thematic analysis. Setting: Face-to-face interviews were conducted in the Jiangnan University, in hospital and in patients’ homes. Participants: Twenty-two older patients with COPD and 29 HCPs. Methods: An initial codebook and semi-structured interview guide were developed based on the shared decision-making 3-circle conceptual model. Thematic analysis was used to analyze data. Results: The study identified 10 themes that describe the perceptions and experiences of patients and HCPs involved in PR decision-making: (1) patients’ confidence, (2) patients’ perceptions of the cost-benefit of decisions, (3) patients’ perceived stress about the consequences of decision-making, (4) HCPs’ perceived stress on shared decision-making, (5) cognitive biases of patients toward illness and rehabilitation, (6) shared decision-making as a knowledge gap, (7) the knowledge gap between patients and HCPs, (8) authority effect, (9) family support, (10) human resources. These themes were then divided into three groups according to their characteristics: (1) the feelings of the participants, (2) knowledge barriers, and (3) support from the social system. Conclusion: Patients and HCPs described their negative perceptions and experiences of participating in decision-making in PR. The implementation of shared decision-making in PR is currently limited; therefore, health education for patients and families should be strengthened and a training system for HCPs in shared decision-making should be established.

A Weight Based Hierarchical Vector Quantization Algorithm for Space Environment Volume Data

Visualization has been widely applied in space environment domain. However, compressed volume rendering algorithms based on VQ are concerned on fidelity and compression rate, not combined with specific application. To fulfill the specific visualization requirements for space environment volume data, an application-driven compression and rendering algorithm is proposed, which is Weight Based Hierarchical Vector Quantization (WHVQ). The volume data is initially partitioned into disjoint 4³ blocks. Weights are assigned to the blocks according to their importance. The blocks are then decomposed into a three level hierarchical representation and each block is represented by a mean value and two detail vectors. To the top two levels, a splitting based on principal component analysis and weight is adopted to form their initial codebooks. Then, LBG algorithm based on weight is conducted for codebook refinement and quantization. The experimental results show that WHVQ is able to improve the quality of reconstruction in interested area on the premise of the good overall fidelity.

Withdrawal method inquiries and user experiences: An analysis of content posted on 4 gendered forums on Reddit

ObjectivesLimited research and guidance on the use of “withdrawal” or coitus interruptus for contraception lead to inconsistent or even inaccurate physician recommendations regarding its use. Consequently, patients rely on online communities to learn about this commonly used contraceptive method. To identify knowledge gaps and concerns between men and women, as well as explore how they use withdrawal, we examined withdrawal-related posts on the popular internet discussion forum, Reddit. Study designTo explore gendered variations in withdrawal-related Reddit posts, we extracted posts from the gendered forums: “TwoXChromosomes,” “Askwomen,” “Askmen,” and “OneY” between 2010 and 2019 that contained the search terms: “coitus interruptus,” “withdrawal,” “pull out,” “preejaculate,” or “precum.” We developed an initial codebook with expected codes and augmented it with emerging findings from a random sampling of 10% of posts. We revised iteratively for interrater agreement, after which researchers coded the remaining posts independently. ResultsOf 269 withdrawal-related queries, 19% were submitted by men; 81% referenced the contributor's own withdrawal use. Salient domains included: concerns about pregnancy risk (59%), how to effectively use withdrawal (13%), benefits/pleasure from using withdrawal (12%), impact on personal life/relationship (9%), and problems encountered, inclusive of consent (7%). Posts to female-focused forums more frequently inquired about pregnancy risk, while those on male forums more frequently inquired about withdrawal-related logistics (p < 0.001); domains were not associated with contributor gender. ConclusionWithdrawal-related queries within this Reddit sample are frequently posted by women, the majority of whom want to understand their risk of pregnancy with withdrawal. Research operationalizing withdrawal and more accurately estimating withdrawal-related pregnancy risk is warranted. ImplicationsReddit users discuss their personal experiences with withdrawal as contraception, as well as seek advice regarding its use from the online community. Pregnancy risk, logistics of use, and ongoing stigma are salient topics. Further research on pregnancy risk, operationalizing success, and approaches for discussing this behavioral method is warranted.

A Narrative Study of Equity in Clinical Assessment Through the Antideficit Lens.

Efforts to address inequities in medical education are centered on a dialogue of deficits that highlight negative underrepresented in medicine (UIM) learner experiences and lower performance outcomes. An alternative narrative explores perspectives on achievement and equity in assessment. This study sought to understand UIM learner perceptions of successes and equitable assessment practices. Using narrative research, investigators selected a purposeful sample of self-identified UIM fourth-year medical students and senior-level residents and conducted semistructured interviews. Questions elicited personal stories of achievement during clinical training, clinical assessment practices that captured achievement, and equity in clinical assessment. Using re-storying and thematic analysis, investigators coded transcripts and synthesized data into themes and representative stories. Twenty UIM learners (6 medical students and 14 residents) were interviewed. Learners often thought about equity during clinical training and provided personal definitions of equity in assessment. Learners shared stories that reflected their achievements in patient care, favorable assessment outcomes, and growth throughout clinical training. Sound assessments that captured achievements included frequent observations with real-time feedback on predefined expectations by supportive, longitudinal clinical supervisors. Finally, equitable assessment systems were characterized as sound assessment systems that also avoided comparison to peers, used narrative assessment, assessed patient care and growth, trained supervisors to avoid bias, and acknowledged learner identity. UIM learners characterized equitable and sound assessment systems that captured achievements during clinical training. These findings guide future efforts to create an inclusive, fair, and equitable clinical assessment experience.

The impact of COVID-19 among Black women: evaluating perspectives and sources of information

ABSTRACT Objectives Coronavirus disease 2019 (COVID-19) has burgeoned into a pandemic that highlights the countless social and health disparities that have existed in Black communities within the United States for centuries. Recent epidemiological data show that Black communities are being disproportionately impacted by COVID-19, resulting in higher morbidity and mortality rates compared to other racial and ethnic groups. For Black women in particular, a long-standing history of systemic racism and marginalization has resulted in increased vulnerability and susceptibility to certain adverse health outcomes. Recent data show that COVID-19 knowledge rates among Black participants are low, and that Black women who become infected with COVID-19 have higher risks of complications and mortality compared to their non-Black counterparts. Given this data, there is a need to explore where and how Black women are obtaining information that pertains to COVID-19, along with the impacts that COVID-19 may be having on their daily lives. Design We conducted interviews with 15 Black women who are clients at a community-based family service center to assess their understanding of COVID-19, determine how they were obtaining COVID-19 information, and evaluate the various impacts that COVID-19 was having on their lives. An initial codebook was developed based on the recorded interviews which included deductive and inductive codes. A thematic analysis of the data was then conducted using MaxQDA (Verbi Software), focusing on Black women's experiences related to COVID-19. Results The majority of participants were using a combination of social media platforms and news sources to obtain information about COVID-19. Most participants (79%) expressed confusion, misunderstanding, and mistrust of the information that they were receiving about COVID-19. Conclusion In addressing COVID-19-related health disparities within Black communities, it is imperative for trusted entities and organizations within Black communities to provide accurate and tailored information regarding this novel virus.

Metaheuristic-based vector quantization approach: a new paradigm for neural network-based video compression

Video compression has great significance in the communication of motion pictures. Video compression techniques try to remove the different types of redundancy within or between video sequences. In the temporal domain, the video compression techniques remove the redundancies between the highly correlated consequence frames of the video. In the spatial domain, the video compression techniques remove the redundancies between the highly correlated consequence pixels (samples) in the same frame. Evolving neural-networks based video coding research efforts are focused on improving existing video codecs by performing better predictions that are incorporated within the same codec framework or holistic methods of end-to-end video compression schemes. Current neural network-based video compression adapts static codebook to achieve compression that leads to learning inability from new samples. This paper proposes a modified video compression model that adapts the genetic algorithm to build an optimal codebook for adaptive vector quantization that is used as an activation function inside the neural network’s hidden layer. Background subtraction algorithm is employed to extract motion objects within frames to generate the context-based initial codebook. Furthermore, Differential Pulse Code Modulation (DPCM) is utilized for lossless compression of significant wavelet coefficients; whereas low energy coefficients are lossy compressed using Learning Vector Quantization (LVQ) neural networks. Finally, Run Length Encoding (RLE) is engaged to encode the quantized coefficients to achieve a higher compression ratio. Experiments have proven the system’s ability to achieve higher compression ratio with acceptable efficiency measured by PSNR.

Compression and Rendering of Space Environment Volume Data Based on Improved HVQ Algorithm

We propose an improved HVQ approach by combining two detail levels to compress space environment volumes, based on the variation characteristics including smooth variation and significantly positive correlation between variations in the same direction at two different scales. First, the space environment data is divided into 43 blocks. Then blocks are decomposed into a two-level hierarchical representation and each block is represented by a mean value and a detail vector. Finally, the detail vectors are encoded by a vector quantizer. During the vector quantization process, PCA-split is applied to compute an initial codebook, and then LBG-algorithm is conducted for codebook refinement and quantization. We take advantage of the codebook-retraining method to speed up the quantization of time series with temporal coherence. Furthermore, we employ the progressive rendering based on GPU for realtime interactive visualization. The results of our experiments prove that the algorithm proposed in this paper can significantly improve the compression rate and decoding speed without sacrificing fidelity in space environment domain.

Intestinal Polyp Recognition Based on Salient Codebook Locality-Constrained Linear Coding with Annular Spatial Pyramid Matching

Gastrointestinal endoscopy has become a widely used technique to diagnose intestinal anomalies like polyp. However, the vast quantities of images produced in the detection process greatly increase the burden of clinicians and the misdiagnosis rate. To tackle this problem, a new computer-assisted detection system called Salient Codebook Locality-Constrained Linear Coding (SCLLC) with Annular Spatial Pyramid Matching (ASPM) is proposed in this paper to classify intestinal polyp images automatically. Firstly, SIFT features are extracted from images and k-means clustering method is utilized on the patch features to obtain the initial codebook. Secondly, the proposed SCLLC algorithm is employed to achieve the salient codebook and encode the features by emphasizing the salient basis vectors in feature coding process. Then, a max-pooling strategy of annular region segmentation based on Spatial Pyramid Matching is proposed to improve the effectiveness of processing for intestinal images. Finally, SVM classifier is developed to carry out polyp images classification tasks. The experimental results exhibit promising 94.10% accuracy, 91.20% sensitivity and 97.01% specificity. In addition, the 0.97 s detecting time indicates the feasibility of clinical application. Our proposed method can effectively improve the overall performance of intestinal polyp recognition by integrating the internal base vector correlation of codebook and considering the annular structure of the intestinal images.

“Is the Pre-cum Myth True?” An Analysis of Queries on Using Withdrawal for Contraception on Reddit [02I

INTRODUCTION: Limited research and the lack of guidelines on “withdrawal” or coitus interruptus lead to inconsistent provider-patient recommendations regarding its use. Patients consequently rely on peers or online communities to learn about this neglected contraceptive method. To better understand knowledge gaps and concerns, we examined posts about withdrawal on the popular, anonymous internet discussion forum, Reddit. METHODS: Posts containing the search terms: “coitus interruptus,” “withdrawal,” “pull out,” “pre-ejaculate,” or “pre-cum” were extracted and filtered for relevant content. Data extraction was limited to gendered forums/subreddits from 2010-2019: “TwoXChromosomes,” “Askwomen,” “Askmen,” “OneY.” We developed an initial codebook with expected themes, augmented with salient themes emerging from a random sampling of 10% of posts, and revised iteratively until adequate inter-rater agreement was reached; remaining posts were coded independently. RESULTS: Of 271 withdrawal-related queries, 19% were submitted by men; 81% referenced the contributor’s own use of withdrawal. Salient themes included: concerns about pregnancy risk (52%), using withdrawal with additional contraception (49%), impact on personal life/relationship (27%), benefits/pleasure from using withdrawal (12%), when or how to effectively use withdrawal (7%), and problems encountered (3%). Posts to female-focused forums more frequently inquired about pregnancy risk, while those on men’s forums inquired about when/how to use withdrawal (P&lt;.01); themes were not associated with contributor gender. CONCLUSION: Withdrawal-related queries on Reddit are more frequently posted by women, the majority of whom want to better understand their risk of pregnancy with withdrawal. Research on operationalizing withdrawal and withdrawal-related pregnancy risk may help providers counsel patients and decrease their reliance on online forums.

Readmission drivers for children with medical complexity: Home nursing shortages cause health crises.

Children with medical technology dependence (MTD) are frequently readmitted to the hospital. However, due to their medical fragility, it is often difficult to untangle the root causes for readmissions to identify the most effective preventive approaches. We sought to explore environmental and family factors driving hospital readmissions for children with MTD. Semi-structured, in-person interviews were conducted with state-wide care coordinators for children with MTD in Illinois with at least 1 year of experience. Interview topics related to children with MTD transitioning from hospital-to-home, essential supports for living in the community, and factors which influenced and prevented hospital readmission. The interview guide served as an initial codebook which was iteratively modified as themes emerged. Fifteen care coordinators with on average 6.6 years of experience were interviewed. They described that lack of home nursing was one of the primary drivers of readmissions due to parental exhaustion and lack of medical expertize in the home. Unavoidable medical admissions, a lack of a plan for emergencies, and home environmental factors also contributed to readmissions. Hospital readmission is an expected occurrence for children with MTD, yet still may be substantially reduced through consistent, quality home health nursing to bolster family capacity and allow for respite from constant caregiving. Improved incentives for the home health workforce to increase manpower would be ultimately offset by reduced hospitalizations for children with MTD. Additionally, more research is needed to understand which home nursing structures and skills optimally support families in the reality of manpower scarcity.

The Decline in Community Preceptor Teaching Activity: Exploring the Perspectives of Pediatricians Who No Longer Teach Medical Students.

Difficulty in recruiting and retaining community preceptors for medical student education has been described in the literature. Yet little, if any, information is known about community outpatient preceptors who have stopped or decreased teaching time with students. This study aimed to examine these preceptors' perspectives about this phenomenon. Using a phenomenology framework, this multi-institutional qualitative study used semistructured interviews with community pediatric preceptors who had stopped or reduced teaching time with medical students. Interviews were conducted between October 2017 and January 2018 and transcribed verbatim. Interviews explored factors for engaging in teaching, or decreasing or ceasing teaching, that would enable future teaching. An initial code book was developed and refined as data were analyzed to generate themes. Twenty-seven community pediatricians affiliated with 10 institutions participated. Thirty-seven codes resulted in 4 organizing themes: evolution of health care, personal barriers, educational system, and ideal situations to recruit and retain preceptors, each with subthemes. From the viewpoints of physicians who had decreased or stopped teaching students, this study more deeply explores previously described reasons contributing to the decline of community preceptors, adds newly described barriers, and offers strategies to help counter this phenomenon based on preceptors' perceptions. These findings appear to be manifestations of deeper issues including the professional identify of clinical educators. Understanding the barriers and strategies and how they relate to preceptors themselves should better inform education leaders to more effectively halt the decline of community precepting and enhance the clinical precepting environment for medical students.

Assessing community organization needs for medical school Community Service-Learning

Objective While literature exists on student feedback to community service-learning (CSL), community organizations have played a small role in re-shaping CSL within medical curricula. The objective of this study was to analyze feedback from community supervisors involved in a CSL course at University of Toronto’s Faculty of Medicine. Methods Semi-structured one-to-one qualitative interviews were conducted with community supervisors (n = 9) between October 2018 and January 2019. Interviews were transcribed and thematic analysis was completed using Dedoose software. Researchers independently coded transcripts and developed an initial codebook. Once inter-rater reliability (Cohen's κ coefficient) > 0.80 was achieved, the remaining transcripts were coded deductively, and additional codes were developed inductively when existing code were unable to describe new data. Themes from the analysis were identified. Results Four overarching themes were identified. Perceived benefits to students by supervisors focused on their contributions to the development of future physicians through understanding community needs and exposure to organizations that may be resourceful to physicians. Among organizational benefits of CSL, extra hands, work-specific benefits, and medical student’s unique expertise were subthemes highlighted. CSL benefits were not without challenges. Scheduling difficulties, motivating students to understand their work’s value, and curriculum gaps identified were challenges supervisors faced. Three subthemes emerged under areas for improvement. Supervisors emphasized increasing flexibility to make experiences more meaningful for students. They also wanted more dialogue between organizations to gain insight from one another and a clearer understanding of CSL and its role in the curriculum. Conclusions Community supervisors viewed academic institutions to be in a unique position having established many partnerships with community organizations. Developing networking opportunities between organizations should be encouraged across CSL programs in medical education. As well, clearer understanding of CSL as part of the medical curriculum was important for supervisors to better understand their roles and responsibilities.

"If You Don't Ask, I'm Not Going to Tell You": Using Community-Based Participatory Research to Inform Pregnancy Intention Screening Processes for Black and Latina Women in Primary Care.

Public health and medical professional organizations recommend screening women of reproductive age for pregnancy intention (PI) routinely in primary care. Existing PI screening tools may not address the complexity of intentions for women of color or lower socioeconomic status or be well-suited to primary care settings. This study sought to inform recommendations for carrying out PI screening meaningfully in primary care settings. This community-based participatory research project united staff from a research institution, community health organization, and federally qualified health center in a predominantly Latina community in New York City. The Community Advisory Board members designed the research question, developed qualitative interview guides, and conducted in-depth interviews with 30 English- and Spanish-speaking female federally qualified health center patients ages 15 to 49. Community Advisory Board members developed an initial codebook using an inductive approach and refined themes throughout the coding process. After coding, Community Advisory Board members created a conceptual map representing relationships between key themes, and generated data-informed recommendations for PI screening practices that are relevant and feasible in the community context. Participants expressed a range of experiences with PI screening processes, depending on medical histories, attitudes, norms, and perceived benefits of screening. Three central themes emerged through frequency of occurrence, consistency in content, and relevance as reflected in concept mapping: agency, judgment and shame, and expertise versus authority. Recommendations included specific strategies and wording providers could use to explain the rationale and context for discussing PI. Future work should examine the experience and effectiveness of implementing these community-based participatory research-derived recommendations in primary care.

Vector quantization using the improved differential evolution algorithm for image compression

Vector quantization (VQ) is a popular image compression technique with a simple decoding architecture and high compression ratio. Codebook designing is the most essential part in vector quantization. Linde–Buzo–Gray (LBG) is a traditional method of generation of VQ codebook which results in lower PSNR value. A codebook affects the quality of image compression, so the choice of an appropriate codebook is a must. Several optimization techniques have been proposed for global codebook generation to enhance the quality of image compression. In this paper, a novel algorithm called IDE-LBG is proposed which uses improved differential evolution algorithm coupled with LBG for generating optimum VQ codebooks. The proposed IDE works better than the traditional DE with modifications in the scaling factor and the boundary control mechanism. The IDE generates better solutions by efficient exploration and exploitation of the search space. Then the best optimal solution obtained by the IDE is provided as the initial codebook for the LBG. This approach produces an efficient codebook with less computational time and the consequences include excellent PSNR values and superior quality reconstructed images. It is observed that the proposed IDE-LBG find better VQ Codebooks as compared to IPSO-LBG, BA-LBG and FA-LBG.

Channel-Reconstruction-Based Hybrid Precoding for Millimeter-Wave Multi-User MIMO Systems

The focus of this paper is on multi-user MIMO transmissions for millimeter wave systems with a hybrid precoding architecture at the base-station. To enable multi-user transmissions, the base-station uses a cell-specific codebook of beamforming vectors over an initial beam alignment phase. Each user uses a user-specific codebook of beamforming vectors to learn the top-P (where P >= 1) beam pairs in terms of the observed SNR in a single-user setting. The top-P beam indices along with their SNRs are fed back from each user and the base-station leverages this information to generate beam weights for simultaneous transmissions. A typical method to generate the beam weights is to use only the best beam for each user and either steer energy along this beam, or to utilize this information to reduce multi-user interference. The other beams are used as fall back options to address blockage or mobility. Such an approach completely discards information learned about the channel condition(s) even though each user feeds back this information. With this background, this work develops an advanced directional precoding structure for simultaneous transmissions at the cost of an additional marginal feedback overhead. This construction relies on three main innovations: 1) Additional feedback to allow the base-station to reconstruct a rank-P approximation of the channel matrix between it and each user, 2) A zeroforcing structure that leverages this information to combat multi-user interference by remaining agnostic of the receiver beam knowledge in the precoder design, and 3) A hybrid precoding architecture that allows both amplitude and phase control at low-complexity and cost to allow the implementation of the zeroforcing structure. Numerical studies show that the proposed scheme results in a significant sum rate performance improvement over naive schemes even with a coarse initial beam alignment codebook.

Noncoherent Alamouti Phase-Shift Keying With Full-Rate Encoding and Polynomial-Complexity Maximum-Likelihood Decoding

We consider Alamouti encoding that draws symbols from phase-shift keying and develop a new differential modulation scheme that attains full rate for any constellation order. In contrast to past work, the proposed scheme guarantees that the encoded matrix maintains the characteristics of the initial codebook and, at the same time, attains full rate so that all possible sequences of space-time matrices become valid. Surprisingly, although the validity of all sequences could be thought as a drawback with respect to the cost of noncoherent sequence decoding, in fact it turns out to be an advantage. Based on recent results in the context of quadratic-form maximization over finite alphabets, we exploit the full-rate property of the proposed scheme to develop a polynomial-complexity maximum-likelihood noncoherent sequence decoder whose order is solely determined by the number of receive antennas. Numerical studies show the superiority of the proposed scheme in comparison with contemporary alternatives in terms of encoding rate, decoding complexity, bandwidth efficiency, and throughput.

Barriers, Motivators and Perspectives on Minimizing Lunchtime Food Waste of Early Adolescents in the National School Lunch Program

ObjectiveTo determine barriers, motivators and perspectives on minimizing lunchtime food waste of early adolescents in the National School Lunch Program (NSLP) in Hawai'i.MethodsParticipants were early adolescents 9–13 years of age whose parents received SNAP benefits on O'ahu or Hawai'i Island. A semi‐structured interview guide was developed and pilot tested with three participants. An initial codebook was created based on current literature on barriers, motivators and perspectives on minimizing food waste of early adolescents in the US. Interviews were conducted with additional participants (n=27). Following each interview, one researcher (CP) listened to the recorded interview and added new codes to the codebook. Data saturation was achieved when no new codes were identified. All interviews were transcribed and each transcript was coded twice in NVivo using the codebook to ensure no new codes were required. The two coders (CP and KF) then independently collapsed similar codes into higher‐order categories, agreed on a final set, and developed a codebook based on these higher‐order categories. The two coders then coded three transcripts each in NVivo to evaluate interrater reliability and an average Cohen's kappa coefficient of ≥0.8 was achieved. The two coders then coded all transcripts, with an average Cohen's kappa coefficient of ≥0.8. The two coders independently determined key themes and collectively summarized the results.ResultsDislike of the taste of food and school policy were the key barriers to minimizing food waste. Food that did not taste good was left uneaten and thrown into the trash. Participants also reported throwing more food into the trash if they were served versus offered food choices, and if there was no system in place at the school to share uneaten food, compost or give leftovers to animals. Conversely, school policy was a motivator to minimize food waste if schools allowed participants to share, compost or feed their leftovers at lunch to animals. Participants' perspectives on food waste also depended on the taste of the food. They found it acceptable to throw unwanted food into the trash, but unacceptable to discard desirable food. Participants also perceived that their peers did not care about wasting food and that their parents were against food waste.ConclusionImproving the taste of food served at lunch in the NSLP may help reduce food waste and also influence youth to care about wasting food. Schools should regularly monitor and assess the taste of food served and improve the taste if students dislike the food served in the NSLP. Modification of school policy to present students with food choices instead of serving a standard meal and allow students to share, compost or feed leftovers to animals may also reduce waste.Support or Funding InformationThis work was supported by the USDA National Institute of Food and Agriculture, Hatch project HAW2038‐R, managed by the College of Tropical Agriculture and Human Resources.