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Monochorionic twins have higher mortality rates than dichorionic twins. Selective intrauterine growth restriction (sIUGR) is a common complication found in monochorionic twins. We report such a case of type III sIUGR monochorionic twins. There was positive end-diastolic flow of umbilical arteries, which corresponded to type I sIUGR at 15 weeks. Then, the umbilical arteries showed persistently absent end-diastolic flow at 17 weeks which corresponded to type II sIUGR. Finally, the umbilical artery showed intermittent absent/reversed end-diastolic flow which corresponded to type III sIUGR. This case demonstrated a unique myriad of Doppler changes during the pregnancy, indicating its significance in being reported. The twins were delivered by caesarean section at 32 weeks and were developing well. Placental examination showed unequal placental sharing and the presence of an arterio-arterial anastomosis. These are characteristic findings of a type III sIUGR. Type III sIUGR may not be obvious at the initial examination but may only be obvious at later examinations.

This project contains the material to supplement the PIAAC pre-conference workshop in 2022 (https://www.gesis.org/en/piaac/conference/programme). Topics are: (a) Principles of structural equation modelling and the complexities of the PIAAC data (b) Regression and path models (c) Measurement models (d) Structural regression and mediation models (e) Measurement invariance testing (f) Multilevel structural equation modelling

Preface: This study uses Norway’s national registers to investigate the associations between COVID-19 school closures and students’ learning outcomes. Register datasets overcome sampling issues by preserving information about the entire Norwegian population. Due to our source data’s large sizes, we expect statistical significance for most inferential parameters. In addition to preventing questionable practices such as p-hacking, this preregistration serves to enhance research transparency by declaring our research questions and methodological approaches before key variables become available to the authors. School closures resultant from the COVID-19 pandemic in 2020 and 2021 represented a sudden and unexpected disruption of students' learning in schools. “School systems had to rapidly improvise to ensure some continuity in the education of children and adapt their teaching methods to a situation in which, in the space of a day, the setting in which education took place moved from the school to the home for most children and the mode of instruction shifted from face-to-face contact between pupils and their teachers/instructors to some form of remote or distance learning, often supervised by parents” (Thorn & Vincent-Lancrin, 2021, p. 13). Findings from previous studies suggest that school closures had a negative effect on student achievement (d=-0.005 SD to d=-0.05 SD per week), especially for students with low socioeconomic status (Hammerstein et al., 2021). In their meta-analysis, Betthäuser et al. (2022) found an overall negative effect of school closures on student learning early in the pandemic across 34 studies (Cohen’s d=-0.17). In summary, the results indicate that measures to maintain learning during school closures that began in March 2020 were not effective. Although these findings appeared robust as many studies examined large samples, used administrative or test data, and often employed methods enabling causal inferences (e.g., difference-in-difference approach), most of the prior studies contained weaknesses in their underlying data (Thorn & Vincent-Lancrin, 2021). For example, convenience samples were often used (e.g., Clark et al., 2021), data were not representative of the underlying population (e.g., Kuhfeld et al., 2020), or data were obtained from survey methods such as web-based surveys, mobile apps, or telephone interviews result in distorted samples and/or low response rates (e.g., van der Velde et al., 2021). Moreover, although some consensus has emerged (e.g., greater learning loss among students with lower SES), uncertainties remain among mixed findings between different subjects. Lastly, school closures have prevented achievement assessments from taking place. The lack of data presents educational researchers with additional challenge of generating evidence on the impact of school closures. Against this background, there is a need for both studies that analyze the impact of school closures on student achievement using enhanced methodology based on high quality data (e.g., representative data allowing us to draw conclusions about the entire population including family circumstances that are important for learning at home) and studies on how to accommodate systemic missing data. We aim to conduct two studies using Norway’s register data between 2009 and 2020. In Study 1 (number of archival entries ≈ 12.3million), we will present a Bayesian approach to estimating missing exam data in 2020 using Year 10 students’ teacher-assigned grades and exam grades from the previous 10 years, with particular focus on mathematics, Norwegian and English. In Study 2 (number of archival entries ≈ 5.6 million), we will use Year 8 and 9 students’ national test data in reading and mathematics as measures for students’ learning. Since identical tests are used in Year 8 and 9, learning growths can be operationalized using difference scores. We will use difference-in-difference (DiD) approaches to compare learning progression (i.e., gains or losses) between the cohorts effected by school closures due to COVID-19 and previous cohorts. We therefore aim to provide robust findings that allow causal inferences on the effects of school closures (e.g., duration) on students’ learning progression. That is, the focus of this study is school closure elasticity of student achievement (i.e., percentage change of student academic achievement in response to percentage change in school closure). This study aims to gain insights into the importance of teaching and learning in schools. In addition, we aim to shed light into the differential effects of school closures by looking at important background variables of learning at home (e.g., parental income and education status, and housing conditions in terms of floor areas per person). Findings from this study will assist future policy-formation by quantifying educational costs resultant from major social measures. The entire preregistration is also available as a PDF in our OSF project: https://osf.io/t6myh/?view_only=85ac0580daf54c44979de1b9ffe0c011

We present an alternative proof of the NEXP-hardness of the satisfiability of {\em Dependency Quantified Boolean Formulas} (DQBF). Besides being simple, our proof also gives us a general method to reduce NEXP-complete problems to DQBF. We demonstrate its utility by presenting explicit reductions from a wide variety of NEXP-complete problems to DQBF such as (succinctly represented) 3-colorability, Hamiltonian cycle, set packing and subset-sum as well as NEXP-complete logics such as the Bernays-Sch\"onfinkel-Ramsey class, the two-variable logic and the monadic class. Our results show the vast applications of DQBF solvers which recently have gathered a lot of attention among researchers., Comment: To appear in the proceedings of FMCAD 2022

Xianbin_Li_Supplemental_Material for The Neglect of Left-Behind Children in China: A Meta-Analysis by Yu-Jie Wen, Wen-Peng Hou, Wei Zheng, Xi-Xi Zhao, Xue-Qi Wang, Qi-Jing Bo, Christine Pao, Yi-Lang Tang, Tony Tan, Xian-Bin Li and Chuan-Yue Wang in Trauma, Violence, & Abuse

We consider the extension of two variable logic with quantifiers that state that the number of elements where a formula holds should belong to a given ultimately periodic set. We show that both satisfiability and finite satisfiability of the logic are decidable. We also show that the spectrum of any sentence is definable in Presburger arithmetic. In the process we present several refinements to the ``biregular graph method''. In this method, decidability issues concerning two-variable logics are reduced to questions about Presburger definability of integer vectors associated with partitioned graphs, where nodes in a partition satisfy certain constraints on their in- and out-degrees.

Supplemental material, Appendix for Testing Measurement Invariance Across Unobserved Groups: The Role of Covariates in Factor Mixture Modeling by Yan Wang, Eunsook Kim, John M. Ferron, Robert F. Dedrick, Tony X. Tan and Stephen Stark in Educational and Psychological Measurement

We present another proof for the well-known {\em small model property} of two-variable logic. As far as we know, existing proofs of this property rely heavily on model theoretic concepts. In contrast, ours is purely combinatorial and uses only a very simple counting argument, which we find rather intuitive and elegant.

The spectrum of a first-order sentence is the set of the cardinalities of its finite models. In this paper, we consider the spectra of sentences over binary relations that use at least three variables. We show that for every such sentence $\Phi$, there is a sentence $\Phi'$ that uses the same number of variables, but only one symmetric binary relation, such that its spectrum is linearly proportional to the spectrum of $\Phi$. Moreover, the models of $\Phi'$ are all bipartite graphs. As a corollary, we obtain that to settle Asser's conjecture, i.e., whether the class of spectra is closed under complement, it is sufficient to consider only sentences using only three variables whose models are restricted to undirected bipartite graphs., Logical Methods in Computer Science ; Volume 14, Issue 2 ; 1860-5974

We introduce an automata model for data words, that is words that carry at each position a symbol from a finite alphabet and a value from an unbounded data domain. The model is (semantically) a restriction of data automata, introduced by Bojanczyk, et. al. in 2006, therefore it is called weak data automata. It is strictly less expressive than data automata and the expressive power is incomparable with register automata. The expressive power of weak data automata corresponds exactly to existential monadic second order logic with successor +1 and data value equality \sim, EMSO2(+1,\sim). It follows from previous work, David, et. al. in 2010, that the nonemptiness problem for weak data automata can be decided in 2-NEXPTIME. Furthermore, we study weak B\"uchi automata on data omega-strings. They can be characterized by the extension of EMSO2(+1,\sim) with existential quantifiers for infinite sets. Finally, the same complexity bound for its nonemptiness problem is established by a nondeterministic polynomial time reduction to the nonemptiness problem of weak data automata., Comment: 21 pages

Recently data trees and data words have received considerable amount of attention in connection with XML reasoning and system verification. These are trees or words that, in addition to labels from a finite alphabet, carry data values from an infinite alphabet (data). In general it is rather hard to obtain logics for data words and trees that are sufficiently expressive, but still have reasonable complexity for the satisfiability problem. In this paper we extend and study the notion of B��chi automata for omega-words with data. We prove that the emptiness problem for such extension is decidable in elementary complexity. We then apply our result to show the decidability of two kinds of logics for omega-words with data: the two-variable fragment of first-order logic and some extensions of classical linear temporal logic for omega-words with data.

The field of home automation is expanding rapidly as electronic technologies converge. The home network now encompasses communications, entertainment, security, convenience and information system. So going by this trend, in this project, we will take a look in one of the design and development of a communication portable device wirelessly, bearing in mind the necessary technical parameters and specifications to achieve optimum results. ​Master of Science (Communications Engineering)

While services such as Amazon AWS make computing power abundantly available, adding more computing nodes can incur high costs in, for instance, pay-as-you-go plans while not always significantly improving the net running time (aka wall-clock time) of queries. In this work, we provide algorithms for parallel evaluation of SGF queries in MapReduce that optimize total time, while retaining low net time. Not only can SGF queries specify all semi-join reducers, but also more expressive queries involving disjunction and negation. Since SGF queries can be seen as Boolean combinations of (potentially nested) semi-joins, we introduce a novel multi-semi-join (MSJ) MapReduce operator that enables the evaluation of a set of semi-joins in one job. We use this operator to obtain parallel query plans for SGF queries that outvalue sequential plans w.r.t. net time and provide additional optimizations aimed at minimizing total time without severely affecting net time. Even though the latter optimizations are NP-hard, we present effective greedy algorithms. Our experiments, conducted using our own implementation Gumbo on top of Hadoop, confirm the usefulness of parallel query plans, and the effectiveness and scalability of our optimizations, all with a significant improvement over Pig and Hive., Comment: added Gumbo code reference, added Subset Sum reference, adjusted alignment in Figure 1, adjusted Figure 5 (remove redundant units, larger font), removed capitals in Table 2, boxes for environment ends, clarified proof in appendix, reference cleanup (pages, capitalization), uncapitalized "REQUEST" and "ASSERT" when used in text, small rewordings (no results affected)

The spectrum of a first-order logic sentence is the set of natural numbers that are cardinalities of its finite models. In this paper we study the hierarchy of first-order spectra based on the number of variables. It has been conjectured that it collapses to three variable. We show the opposite: it forms an infinite hierarchy. However, despite the fact that more variables can express more spectra, we show that to establish whether the class of first-order spectra is closed under complement, it is sufficient to consider sentences using only three variables and binary relations., Comment: 13 pages