Improving Table Compression with Combinatorial Optimization

We study the problem of compressing massive tables within the partition-training paradigm introduced by Buchsbaum et al. [SODA'00], in which a table is partitioned by an off-line training procedure into disjoint intervals of columns, each of which is compressed separately by a standard, on-line compressor like gzip. We provide a new theory that unifies previous experimental observations on partitioning and heuristic observations on column permutation, all of which are used to improve compression rates. Based on the theory, we devise the first on-line training algorithms for table compression, which can be applied to individual files, not just continuously operating sources; and also a new, off-line training algorithm, based on a link to the asymmetric traveling salesman problem, which improves on prior work by rearranging columns prior to partitioning. We demonstrate these results experimentally. On various test files, the on-line algorithms provide 35-55% improvement over gzip with negligible slowdown; the off-line reordering provides up to 20% further improvement over partitioning alone. We also show that a variation of the table compression problem is MAX-SNP hard.Comment: 22 pages, 2 figures, 5 tables, 23 references. Extended abstract appears in Proc. 13th ACM-SIAM SODA, pp. 213-222, 200

Further Evidence that Exclusive Breast-Feeding Reduces Mother-to-Child HIV Transmission Compared With Mixed Feeding

The author discusses the results of the Zambia Exclusive Breastfeeding Study, recently published inPLoS ONE

The IRAS Minor Planet Survey

This report documents the program and data used to identify known asteroids observed by the Infrared Astronomical Satellite (IRAS) and to compute albedos and diameters from their IRAS fluxes. It also presents listings of the results obtained. These results supplant those in the IRAS Asteroid and Comet Survey, 1986. The present version used new and improved asteroid orbital elements for 4679 numbered asteroids and 2632 additional asteroids for which at least two-opposition elements were available as of mid-1991. It employed asteroid absolute magnitudes on the International Astronomical Union system adopted in 1991. In addition, the code was modified to increase the reliability of associating asteroids with IRAS sources and rectify several shortcomings in the final data products released in 1986. Association reliability was improved by decreasing the position difference between an IRAS source and a predicted asteroid position required for an association. The shortcomings addressed included the problem of flux overestimation for low SNR sources and the systematic difference in albedos and diameters among the three wavelength bands (12, 25, and 60 micrometers). Several minor bugs in the original code were also corrected

Changes in Bone Mineral Density During and After Lactation in Ugandan Women With HIV on Tenofovir-Based Antiretroviral Therapy.

Antiretroviral therapy (ART) in people living with human immunodeficiency virus (HIV) is associated with bone loss, but data are limited in lactation, when physiological bone mineral mobilization is occurring. This research charted changes in areal bone mineral density (aBMD) during and after lactation in Ugandan women with HIV (WWH) initiated onto ART in pregnancy, compared to women without HIV (REF). One-hundred WWH on tenofovir-based ART and 100 REF were enrolled in pregnancy. Lumbar spine (LS), total hip (TH), and whole-body-less-head (WBLH) aBMD were measured by dual-energy X-ray absorptiometry (DXA) at 2, 14, and 26 weeks of lactation, and at 3 months postlactation. The primary outcome was the difference between groups in mean percent change in LS aBMD between 2 and 14 weeks. Statistical analysis was performed in hierarchical repeated measures ANOVA models that corrected for multiple testing. Median age was 23.4 (IQR, 21.0 to 26.8) years. WWH had lower body weight. aBMD decreased in both groups during lactation, but WWH had greater decreases at TH (2-to-26 weeks: WWH [n = 63] -5.9% [95% CI, -6.4 to -5.4] versus REF [n = 64] -4.3% [95% CI, -4.8 to -3.8]; group*time point interaction p = .008). Decreases in LS aBMD were similar in WWH and REF (2-to-26 weeks: -2.0% [95% CI, -2.5 to -1.5]), although there was a tendency toward a smaller decrease in WWH between 2 and 14 weeks (WWH [n = 77] -1.8% [95% CI, -2.2 to -1.4] versus REF [n = 69] -2.9% [95% CI, -3.3 to -2.5]; group*time point interaction p = .08). Postlactation, LS aBMD was higher relative to week 2 in both groups. TH and WBLH aBMD did not return to week 2 values in WWH but did in REF (TH postlactation versus week 2: WWH [n = 61] -3.1% [95% CI, -3.6 to -2.6]; REF [n = 29] +0.1% [95% CI, -0.9 to +1.1]). These data show accentuated bone loss during lactation and only partial skeletal recovery by 3 months postlactation in Ugandan WWH on tenofovir-based ART. Studies are ongoing to understand longer-term consequences for bone health. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research

HIV genotypic resistance among pregnant women initiating ART in Uganda: a baseline evaluation of participants in the Option B+ clinical trial

Background: Pre-treatment HIV drug resistance is a threat to elimination of mother to child HIV transmission and could lead to virological failure among HIV-positive pregnant women. We analysed genotypic HIV drug resistance (HIVDR) of baseline samples of participants enrolled in the Option B+ clinical trial in Uganda.Methods: HIV-infected pregnant women attending antenatal care were enrolled from Uganda’s National Referral Hospital (Mulago) and Mityana District general hospital and surrounding health centers (HCs). Genotypic HIV testing was performed on blood samples from the first 135 enrolled women out of a subset of 136 participants (25%) who had a baseline VL>1000 copies/mL as one sample failed to amplify.Results: 159/540 (29.4%) had a VL < 1000 copies/ml and 381/540 (70.6%) had a VL >1,000 copies/ml. Of the women with VL>1000 copies/ml, 32 (23.7%) had resistance mutations including 29/135 (21.5%) NNRTI mutations, 6/135 (4.4%) NRTI mutations and 3/135 (2.2%) had both NNRTI and NRTI mutations. The most common NNRTI resistance mutations were: K103KN (5), K103N (5), V179T (4) and E138A (4).Conclusions: One quarter of the HIV-infected pregnant women in this trial at baseline had NNRTI genotypic resistance mutations. Our findings support new WHO guidelines for first-line ART that were changed to dolutegravir-based regimens

PMTCT Option B+ 2012 to 2018 - Taking stock: barriers and strategies to improve adherence to Option B+ in urban and rural Uganda.

Since 2012, PMTCT Option B+ has been recommended by the World Health Organization to reduce vertical transmission but numerous adherence challenges remain. We conducted a qualitative study at baseline using six focus group discussions and 14 in-depth interviews to explore knowledge, beliefs, attitudes and challenges towards the Option B+ strategy for PMTCT among HIV-infected pregnant and post-partum women and health workers engaged in Uganda's national Option B+ PMTCT programme. Data were analysed using a thematic approach to capture latent and manifest content with the social ecological model as a theoretic foundation in order to make contextual sense of key stakeholders' needs for an effective Option B+ intervention. Overall, among all study participants, we found multi-level barriers to adhering to Option B+ cutting across all levels of the social ecological model. In line with the model, our study revealed barriers at personal, relational, organizational and societal levels. Some personal beliefs such as that the baby's health is more important that the mother's, organizational (negative attitudes and behaviour of health workers), structural such as poverty, work conflicts, fear and lack of disclosure related to community stigma were all critical obstacles to women adhering to the Option B+ programme. We found that both health workers and participants in the programme have a relatively clear understanding of the benefits of adhering to their treatment; though a more nuanced understanding and thus emphasis in counselling on side effects, is critical to helping patients adhere

Pregnant women, their male partners and health care providers' perceptions of HIV self-testing in Kampala, Uganda: Implications for integration in prevention of mother-to-child transmission programs and scale-up.

BACKGROUND: HIV status awareness is critical for HIV prevention and care but HIV testing rates remain low in Uganda, especially among men. One suggested approach to increase access and utilisation of HIV testing services is HIV self-testing. We explored perceptions of pregnant and lactating women and their male partners who attended antenatal care, and health care providers in a government hospital in Kampala, Uganda, about HIV self-testing for initial or repeat testing for women and their partners during pregnancy and postpartum We draw implications for scaling-up this new testing approach in Uganda. METHODS: This was a qualitative study conducted at Mulago National Referral Hospital, Kampala, Uganda, between April and December 2017. We conducted in-depth interviews with five pregnant or lactating women and their five male partners; five focus group discussions (two with women, two with health workers and one with male partners of women attending antenatal care) and five key informant interviews with health workers providing prevention of mother-to-child HIV transmission (PMTCT) services. Data were analysed using content thematic approach. RESULTS: There was limited awareness about HIV self-testing especially among pregnant or lactating women and their male partners. Study participants mentioned that HIV self-testing would enable people to know their HIV status faster, they thought the approach would be cost- and time-saving compared to health facility-based HIV testing, improve confidentiality and reduce stigma for those who test HIV positive. They expressed however, a general fear that HIV self-testing would lead to harm to self and others in case one tested HIV positive, including suicide, violence among couples, intentional transmission of HIV, and limited linkage to care due to lack of counselling. The likely misinterpretation of HIV test results especially among those with no or limited education, and possible coercion exerted by male partners on their wives were other potential concerns raised about the use of HIV self-testing. CONCLUSIONS: There was limited knowledge about HIV self-testing among pregnant and lactating women, their partners and health workers. While the self-testing modality was perceived to be critical for helping people, especially those in casual and distant relationships, to know their HIV status and that of their partners, most study participants believed that HIV self-testing could potentially result in a multitude of negative outcomes in the absence of pre- and post-test counselling. Successful scale-up and integration of self-testing in HIV programs requires community education, provision of information materials and making self-test kits accessible and affordable, especially in rural areas

"[Repeat] testing and counseling is one of the key [services] that the government should continue providing": participants' perceptions on extended repeat HIV testing and enhanced counseling (ERHTEC) for primary HIV prevention in pregnant and lactating women in the PRIMAL study, Uganda.

BACKGROUND: The 'Primary HIV Prevention among Pregnant and Lactating Ugandan Women' (PRIMAL) randomized controlled trial aimed to assess an enhanced counseling strategy linked to extended postpartum repeat HIV testing and enhanced counseling among 820 HIV-negative pregnant and lactating women aged 18-49 years and 410 of their male partners to address the first pillar of the WHO Global Strategy for the Prevention of Mother-to-Child HIV transmission (PMTCT). This paper presents findings of qualitative studies aimed at evaluating participants' and service providers' perceptions on the acceptability and feasibility of the intervention and at understanding the effects of the intervention on risk reduction, couple communication, and emotional support from women's partners. METHODS: PRIMAL Study participants were enrolled from two antenatal care clinics and randomized 1:1 to an intervention or control arm. Both arms received repeat sexually transmitted infections (STI) and HIV testing at enrolment, labor and delivery, and at 3, 6, 12, 18 and 24 months postpartum. The intervention consisted of enhanced quarterly counseling on HIV risk reduction, couple communication, family planning and nutrition delivered by study counselors through up to 24 months post-partum. Control participants received repeat standard post-test counseling. Qualitative data were collected from intervention women participants, counsellors and midwives at baseline, midline and end of the study through 18 focus group discussions and 44 key informant interviews. Data analysis followed a thematic approach using framework analysis and a matrix-based system for organizing, reducing, and synthesizing data. RESULTS: At baseline, FGD participants mentioned multiple sexual partners and lack of condom use as the main risks for pregnant and lactating women to acquire HIV. The main reasons for having multiple sexual partners were 1) the cultural practice not to have sex in the late pre-natal and early post-natal period; 2) increased sexual desire during pregnancy; 3) alcohol abuse; 4) poverty; and 5) conflict in couples. Consistent condom use at baseline was limited due to lack of knowledge and low acceptance of condom use in couples. The majority of intervention participants enrolled as couples felt enhanced counselling improved understanding, faithfulness, mutual support and appreciation within their couple. Another benefit mentioned by participants was improvement of couple communication and negotiation, as well as daily decision-making around sexual needs, family planning and condom use. Participants stressed the importance of providing counselling services to all couples. CONCLUSION: This study shows that enhanced individual and couple counselling linked to extended repeat HIV and STI testing and focusing on HIV prevention, couple communication, family planning and nutrition is a feasible and acceptable intervention that could enhance risk reduction programs among pregnant and lactating women. TRIAL REGISTRATION: ClinicalTrials.gov registration number NCT01882998, date of registration 21st June 2013