Population Reference Bureau

Abstract Laser powder bed fusion (LPBF) is a key technique in metal additive manufacturing (AM) that enables the fabrication of parts with complex geometries and enhanced mechanical properties. Despite its advantages, LPBF's susceptibility to defects remains a challenge, directly linked to melt pool instability. Real-time melt pool monitoring (MPM) systems offer immediate feedback on melt pool states, which is crucial for identifying potential defects during the LPBF process. Recently, machine learning (ML)-based approaches with these monitoring systems have been introduced for real-time process anomaly detection and classification. However, one major hurdle is the requirement for large volumes of labeled and balanced data for ML model development, which is necessary for accurate process outlier identification and categorization. To address the issues, this article introduces a self-supervised learning-based visual transformer (SiT) for multilabel classification of melt pool anomalies, such as abnormal sizes, irregular shapes, spatters, and plumes. Experiments reveal that the self-supervised approach, with an average F1 score of 0.979, surpasses the performance of the supervised approach, which has an average F1 score of 0.836 across all classification cases, particularly in imbalanced datasets. The SiT model efficiently classifies multiple anomalies simultaneously, without extensive manual labeling, addressing data imbalance and enhancing MPM systems' efficiency and reliability. This advancement marks a significant contribution to improving part quality in LPBF processes.

Abstract Closed-loop recycling streams are increasingly taking importance on the development of a sustainable future. Neodymium-iron-boron (Nd-Fe-B) permanent magnets are applied in a variety of applications, including direct-drive wind turbines, electric motors for electric vehicles, hard disk drives (HDDs) in laptops, and other electric devices. End-of-life HDDs are available in the United States to be collected and recycled for the production of Nd-Fe-B magnets for the exponentially increasing demand in electric vehicles and other industries. A comparative assessment of the environmental impact of HDD recycling pathways is conducted for the production of Nd-Fe-B magnets in the United States. The results show that the magnet-to-magnet recycling route has the lowest footprint. A techno-economic assessment is conducted to compare the added value of a harvesting process versus shredding HDDs. After conducting an uncertainty analysis with an optimization technique, multiple scenarios for a harvesting facility are economically feasible. Future work will be needed to reduce financial risks.

Family Planning 2020 (FP2020) was established in 2012 with the goal of expanding contraceptive access. By 2020, 46 countries had made commitments to FP2020. A sustained focus on adolescents and youth (AY) began in 2016. During the commitment formulation process, substantial support was offered to countries to develop AY commitments based on sound data, research evidence, and programmatic experience. This study assesses how country commitments under FP2020 and FP2030 have evolved over time with respect to improving attention to and focus on the needs of adolescents and youth sexual and reproductive health (AYSRH). We analyzed the content of FP2020 and FP2030 country commitments focusing on AY (aged 10-24 years) using a scoring guideline we developed to measure the AY commitments in terms of completeness, clarity, and quality. This analysis shows that FP2030 commitments better articulate strategies and activities to reach AY with contraceptive information and services when compared to FP2020 commitments. FP2030 commitments are stronger in some areas on AYSRH, such as commitment to establish national or local policies, strategies, and guidance for AY programming, specifying the target audience of the AY commitment, and partnering with AY or youth-led organizations in commitments. However, more work remains to be done by countries to dedicate a budget for achieving AY objectives, including measurable targets for monitoring progress, identifying and addressing the root causes that impact AY access to and use of contraception, including child marriage and gender-based violence, and reducing financial barriers to access contraception.

With the share of US adults living in households with cell phones climbing over 90 percent (Blumberg and Luke 2016), survey researchers are considering whether it is necessary to continue sampling landlines in addition to cell phones in RDD surveys. This transition raises a number of questions, including whether it will systematically change public opinion estimates, subgroup estimates, long-standing trends, as well as precision. To address these questions, we analyzed data from Pew Research Center national dual-frame RDD surveys conducted from 2012 to 2015. We compared the final survey estimates to those computed with an experimental weight that excluded the landline sample, thus simulating a single-frame cell-phone design. Analysis of more than 250 survey questions shows that when landlines are excluded, estimates change by less than one percentage point, on average. In addition, responding samples of adults reached via cell phone are much more demographically representative of the United States than responding samples of adults reached via landline, thus requiring less aggressive weighting and yielding lower design effects and smaller margins of error, relative to dual-frame RDD. While most estimates commonly reported from public opinion surveys seem unaffected by this design change, there are some exceptions. While considerations of cost and concerns about maximizing the population coverage rate may continue to favor dual-frame RDD for some time, these results demonstrate that by and large public opinion researchers have little to fear and potentially much to gain when landlines become a thing of the past.

In Burkina Faso and Togo, key populations of men who have sex with men (MSM) and sex workers (SW) have a disproportionately higher HIV prevalence. This study analyzed the 2 countries' policies impacting MSM and SW; to what extent the policies and programs have been implemented; and the role of the enabling environment, country leadership, and donor support. The Health Policy Project's Policy Assessment and Advocacy Decision Model methodology was used to analyze policy and program documents related to key populations, conduct key informant interviews, and hold stakeholder meetings to validate the findings. Several policy barriers restrict MSM/SW from accessing services. Laws criminalizing MSM/SW, particularly anti-solicitation laws, result in harassment and arrests of even nonsoliciting MSM/SW. Policy gaps exist, including few MSM/SW-supportive policies and HIV prevention measures, e.g., lubricant not included in the essential medicines list. The needs of key populations are generally not met due to policy gaps around MSM/SW participation in decision-making and funding allocation for MSM/SW-specific programming. Misaligned policies, eg, contradictory informed consent laws and protocols, and uneven policy implementation, such as stockouts of sexually transmitted infection kits, HIV testing materials, and antiretrovirals, undermine evidence-based policies. Even in the presence of a supportive donor and political community, public stigma and discrimination (S&D) create a hostile enabling environment. Policies are needed to address S&D, particularly health care provider and law enforcement training, and to authorize, fund, guide, and monitor services for key populations. MSM/SW participation and development of operational guidelines can improve policy implementation and service uptake.

The literature is reviewed on the relationships between population, poverty, and climate change. While developed countries are largely responsible for global warming, the brunt of the fallout will be borne by the developing world, in lower agricultural output, poorer health, and more frequent natural disasters. Carbon emissions in the developed world have leveled off, but are projected to rise rapidly in the developing world due to their economic growth and population growth-the latter most notably in the poorest countries. Lowering fertility has many benefits for the poorest countries. Studies indicate that, in high fertility settings, fertility decline facilitates economic growth and poverty reduction. It also reduces the pressure on livelihoods, and frees up resources to cope with climate change. And it helps avert some of the projected global warming, which will benefit these countries far more than those that lie at higher latitudes and/or have more resources to cope with climate change. Natural experiments indicate that family planning programs are effective in helping reduce fertility, and that they are highly pro-poor in their impact. While the rest of the world wrestles with the complexities of reducing emissions, the poorest countries will gain much from simple programs to lower fertility

Books reviewed in this article: Paul‐André Rosental L'intelligence démographique: sciences et politiques des populations en France (1930–1960) James R. Carey Longevity: The Biology and Demography of Life Span Susan Scott and Christopher J. Duncan Demography and Nutrition: Evidence from Historical and Contemporary Populations Laura R. Woliver The Political Geographies of Pregnancy