Unsupervised embedding of trajectories captures the latent structure of scientific migration.

Human migration and mobility drives major societal phenomena including epidemics, economies, innovation, and the diffusion of ideas. Although human mobility and migration have been heavily constrained by geographic distance throughout the history, advances, and globalization are making other factors such as language and culture increasingly more important. Advances in neural embedding models, originally designed for natural language, provide an opportunity to tame this complexity and open new avenues for the study of migration. Here, we demonstrate the ability of the model word2vec to encode nuanced relationships between discrete locations from migration trajectories, producing an accurate, dense, continuous, and meaningful vector-space representation. The resulting representation provides a functional distance between locations, as well as a "digital double" that can be distributed, re-used, and itself interrogated to understand the many dimensions of migration. We show that the unique power of word2vec to encode migration patterns stems from its mathematical equivalence with the gravity model of mobility. Focusing on the case of scientific migration, we apply word2vec to a database of three million migration trajectories of scientists derived from the affiliations listed on their publication records. Using techniques that leverage its semantic structure, we demonstrate that embeddings can learn the rich structure that underpins scientific migration, such as cultural, linguistic, and prestige relationships at multiple levels of granularity. Our results provide a theoretical foundation and methodological framework for using neural embeddings to represent and understand migration both within and beyond science.

Effects of laser-assisted thinning versus opening on clinical outcomes according to maternal age in patients with repeated implantation failure.

Laser-assisted thinning (LAT) and laser-assisted opening (LAO) are performed as part of human in vitro fertilization (IVF) to increase the implantation rate in patients with a poor prognosis and in cases of repeated implantation failure. However, an insufficient number of studies have directly compared LAT and LAO using the same methods. Therefore, we compared the effects of LAT and LAO on clinical outcomes according to maternal age in patients with repeated implantation failure. This retrospective study was performed in 509 IVF cycles (458 patients). The cycles were divided based on maternal age and the method used (< 38 years LAT, n = 119 vs. LAO, n = 179 and ≥ 38 years LAT, n = 72 vs. LAO, n = 139). Cleavage-stage embryos before transfer were either thinned or opened using a 1.46-µm noncontact diode laser. We compared the implantation rates and pregnancy outcomes of cycles between LAT and LAO according to maternal age. The characteristics of patients did not differ significantly among the groups (p > 0.05), with the exception of mixed factor infertility, which was more common in the LAT group than in the LAO group among patients < 38 years of age (10.1% vs. 2.8%, p = 0.008). The LAT and LAO groups showed similar rates of biochemical pregnancy, clinical pregnancy, ongoing pregnancy, abortion, implantation, singleton pregnancy, and twin pregnancy (p > 0.05). In conclusion, LAT and LAO had similar clinical outcomes. Therefore, we did not find any evidence that LAT is superior to LAO. In fact, the patients ≥ 38 years of age who underwent LAO tended to have a lower abortion rate. Further study is necessary to confirm these results in a larger population.

COVID-19 confines recreational gatherings in Seoul to familiar, less crowded, and neighboring urban areas.

Recreational gatherings are sources of the spread of infectious diseases. Understanding the dynamics of recreational gatherings is essential to building effective public health policies but challenging as the interaction between people and recreational places is complex. Recreational activities are concentrated in a set of urban areas and establish a recreational hierarchy. In this hierarchy, higher-level regions attract more people than lower-level regions for recreational purposes. Here, using customers' motel booking records which are highly associated with recreational activities in Korea, we identify that recreational hierarchy, geographical distance, and attachment to a location are crucial factors of recreational gatherings in Seoul, Republic of Korea. Our analyses show that after the COVID-19 outbreak, people are more likely to visit familiar recreational places, avoid the highest level of the recreational hierarchy, and travel close distances. Interestingly, the recreational visitations were reduced not only in the highest but also in low-level regions. Urban areas at low levels of the recreational hierarchy were more severely affected by COVID-19 than urban areas at high and middle levels of the recreational hierarchy.

Persona2vec: a flexible multi-role representations learning framework for graphs.

Graph embedding techniques, which learn low-dimensional representations of a graph, are achieving state-of-the-art performance in many graph mining tasks. Most existing embedding algorithms assign a single vector to each node, implicitly assuming that a single representation is enough to capture all characteristics of the node. However, across many domains, it is common to observe pervasively overlapping community structure, where most nodes belong to multiple communities, playing different roles depending on the contexts. Here, we propose persona2vec, a graph embedding framework that efficiently learns multiple representations of nodes based on their structural contexts. Using link prediction-based evaluation, we show that our framework is significantly faster than the existing state-of-the-art model while achieving better performance.

Efficacy of embryo transfer on day 2 versus day 3 according to maternal age in patients with normal ovarian response.

OBJECTIVE: Delaying embryo transfer (ET) enables us to select among the embryos available for transfer and is associated with positive effects on implantation and pregnancy outcomes. However, the optimal day for ET of human cleavage-stage embryos remains controversial. METHODS: A retrospective study of 3,124 in vitro fertilization/intracytoplasmic sperm injection cycles (2,440 patients) was conducted. We compared the effects of day 2 and 3 ET on rates of implantation and pregnancy outcomes between young maternal age (YMA; <38 years old, n=2,295) and old maternal age (OMA; ≥38 years old, n=829) patient groups. RESULTS: The YMA and OMA groups did not differ in terms of patient characteristics except for the proportion of unexplained factor infertility, which was significantly greater in the OMA group, and the proportion of arrested embryos, which was significantly greater in the YMA group. However, the biochemical pregnancy, clinical pregnancy, ongoing pregnancy, abortion, and implantation rates per cycle were not significantly different between day 2 and 3 ET in the YMA group or the OMA group. CONCLUSION: We suggest that offering patients the opportunity to decide which day would be suitable for ET could be part of a patient-friendly protocol that takes into consideration an infertile woman's circumstances and work schedule by allowing ET to be performed on day 2 instead of the traditional transfer on day 3.

Long Cut Straw Provides Stable the Rates of Survival, Pregnancy and Live Birth for Vitrification of Human Blasotcysts.

Most of the commercial devices for vitrification are directly immersed into the warming solution (WS) for increasing of warming rate. However, the previous modified cut standard straw (MCS) which has reported is difficult to immerse into the WS. The aim of this study was to investigate whether the long cut straw (LCS) could be useful as a stable tool for vitrified-warmed human blastocysts. A total of 138 vitrified-warmed cycles were performed between November 2013 and November 2014 (exclusion criteria: women ≥38 years old, poor responder, surgical retrieval sperm, and severe male factor). The artificial shrinkage was conducted using 29-gauge needles. Ethylene glycol and dimethyl sulfoxide (7.5% and 15% (v/v)) were used as cryoprotectants. Freezing and warming were conducted using the LCS tool. The cap of LCS was removed using the forceps in the liquid nitrogen (LN2) and then directly immersed into the first WS for 1 min at 37℃ (1 M sucrose). Only re-expanded blastocysts were transferred after it was cultured in sequential media for 18-20 h. A total of 294 blastocysts were warmed, and all were recovered (100%). Two hundred eighty-five embryos were survived (96.9%). The vitrifiedwarmed blastocysts of all patients were transferred without any cancellation. We were able to achieve a reasonable implantation (24.2%), following by clinical pregnancy (36.2%), which then continued to ongoing pregnancy (36.2%), and live birth (31.2%). Using LCS is achieved the acceptable rates of survival, pregnancy and live birth. Therefore, the LCS could be considered as a stable and simple tool for human embryo vitrificaton.