 true model. However, structural equation modeling cannot identify the ACDE model because of a negative degree of freedom. In the present paper, the ACDE model was developed using nnSEM. Simulation studies have suggested that the proposed method can decrease the biases and can be used even in cases in which three latent factors affect a trait if G, C, and E are used as outcomes. The effects of the MZ/DZ ratio on the results were not examined in the simulation study described above. However, a small simulation study was conducted, in which the cases of MZ:DZ = 800:400 and 400:800 were considered. The results showed that the MZ/ DZ ratio has almost no effect on the estimates in this simulation setting.
In the present paper, although power calculation was not discussed, the power would be calculated by setting the true second-and third-order moments and analyzing the moments using a null model. This is the same method used to calculate the power in the SEM using Mx (Neale et al. 2006, p. 96).
There is another method of identifying the ACDE model. Kathryn et al. (2004) identified the ACDE model using sibling data, where one of the siblings is an adopted person, as well as twin data. Such sibling data also provides information of the etiology of human variation, because the siblings (one of whom is an adopted person) are thought to share the same environment, however, there is no genetic relationship between the siblings. Therefore, their similarity is thought to be caused by their shared environment. Unfortunately, gathering data for siblings for the case in which one sibling is adopted is very difficult and costly. In the present paper, however, nnSEM was used to identify the ACDE model in which higher-order moments are used as additional information. Since the method of the present paper can estimate a, c, d, and e effects using only twin data, the proposed method requires a much lower cost and is much easier to perform. Therefore, the proposed method contributes to behavior genetic research.
There are other factors that have possible effects on phenotypes, such as higher-order epistasis (Eaves et al. 1978a), assortative mating (people choose to marry persons similar to themselves; Eaves et al. 1984;Loelin and DeFries 1987), gene-environment correlation (Plomin et al. 1977;Eaves et al. 1977), and gene-environment interaction (Plomin et al. 1977;Eaves et al. 1977;Purcell 2002;Eaves and Erkanli 2003). The presence of higher-order epistasis makes the correlation between D factors of DZ twins lower than 0.25. The presence of assortative mating leads to overestimation of the effect of C and underestimation of the effect of A if these are not included in models. An example of gene-environment correlation is that genetically intellectual parents tend to provide an intellectual environment for their children, which in turn increases the intelligence of the children. The presence of positive gene-environment correlation also leads to overestimation of the effect of C and underestimation of the effect of A if these are not included in models. An extended twin-family design (ETFD, Truett et al. 1994) can estimate the effects of assortative mating and gene-environment correlation, but cannot estimate the higher-order epistatic effect or gene-environment interaction. Although Purcell (2002) proposed a relatively easy method of estimating gene-environment interaction, at present, there is no method that incorporates the higher-order epistatic effect in the model. Therefore, further research on developing a more exhaustive model is needed.
Higher-order epistasis is expressed as the correlation between D factors of DZ twins, and assortative mating is expressed as the correlation between A factors of DZ twins and D factors of DZ twins. gene-environment correlation is expressed as the correlation between A and C factors and between D and C factors, and gene-environment interaction is the interaction between one of the genetic factors and one of the environmental factors. Therefore, these four effects can be expressed as parameters associated with A, C, D, or E. Consequently, proper estimation of a, c, d, and e is an important basis for including these phenomena (such as assortative mating). Although, in the present paper, only the ACDE model was proposed, this is an important first step in the development of a more exhaustive model.
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Appendix
When the ACE model is fit, the expected variance of a phenotype is a 2? c 2? e 2, the expected correlation between MZs (r mz ) is a 2? c 2, and the correlation between DZs (r dz ) is 0.5a 2? c 2. Therefore, the simplest method of estimating a 2, c 2, and e 2 when the ACE model is fit is as follows (when the phenotypes are standardized): a 2 ¼ 2ðr mz À r dz Þ c 2 ¼ 2r dz À r mẑ e 2 ¼ 1 À r mz When the ADE model is fit, the expected variance of a phenotype is a 2? c 2? d 2, the expected correlation between MZs (r mz ) is a 2? d 2, and the correlation between DZs (r dz ) is 0.5a 2? 0.25d 2. Therefore, the simplest method of estimating a 2, d 2, and e 2 when the ADE model is fit is as follows: a 2 ¼ 4r dz À r mẑ d 2 ¼ 2ðr mz À 2r dz Þ e 2 ¼ 1 À r mz If the ACDE model is the true model and the true explained variances are a 2 T ; c 2 T ; d 2 T ; and e 2 T ; respectively, then the expected correlation between MZs (r mz ) is a 2SK Telecom’s Chief executive officer Park Jung-ho called for hyper-cooperation from other Korean companies in the development of the artificial intelligence (AI) sector and to also aggressively advance the smart mobility industry.
The CEO announced during a press conference held Thursday at the Consumers Electronics Show (CES) 2020 that the South Korean mobile carrier aims to expand its collaboration in the field of artificial intelligence with tech and communications companies such as Samsung and Kakao.
Park pointed out that global tech giants such as Google, Apple, Facebook, and Amazon (GAFA) are currently the leaders in the race for the development of AI technology, and South Korean tech companies cannot compete with them singlehandedly.
According to Park, each partner company should conduct its business-specifics services on a shared AI engine that would require a massive amount of capital injection for its advancement. He explained that SK Telecom’s over-the-top (OTT) platform service ‘Wavve,’ which launched last year in collaboration with South Korea’s three significant broadcasters, is an excellent example of hyper-cooperation.
Park stated that the telecommunications company would work closely with Samsung Electronics on developing AI technology, jointly investing resources in its advancement while retaining their platforms.
The increasing influence and integration of AI voice assistants from Google and Amazon inspired the Park’s suggestion.
Google’s Assistant and Amazon’s Alexa have been present in everyday life, from home appliances to autonomous cars. However, SK Telecom’s NUGU and Samsung Electronics’ Bixby still seem to lag behind performance and popularity. Park said Korean tech companies should collaborate and create a global standard to better compete.
Park also hinted on the possibility of a company name change of the mobile carrier to better create an identity as a comprehensive ICT service provider, and not as a telecommunication company.
He added that the company is also targeting initial public offerings (IPO) for some of its subsidiaries very soon. The company’s affiliates can grow further, separately from SK Telecom.
SKT will function as a holding company of the SK Group if several IPOs are completed soon. At the earliest, the IPOs could be launched by the end of this year or could take another year or two.
An event that is now all but ubiquitous, the annual celebration-cum-gathering that is Record Store Day has, in its decade-long existence, proven to be the great watershed for the vinyl revival of the twenty-first century.
Conceived of in 2007, this worldwide get-together is an all-encompassing shindig for both independent record stores and the record-crazed themselves, with shops across the globe participating in special releases and a plethora of in-store performances, which is to say nothing of the music titans who have carried the torch for Record Store Day as ambassadors over the years, such as Iggy Pop, Chuck D, and Dave Grohl.
Hot on the heels of RSD’s tenth anniversary event this April 22nd, we talked with co-founders Carrie Colliton and Michael Kurtz about the day’s history, their favorite releases, and some plans for the future.
So, since you guys got this up and running in 2007, this is the big tenth anniversary, isn’t it?
CARRIE: It is. Our first one was in April of 2008, but we had this idea in September of 2007. Having done it ten times now, I can tell you that the idea that we thought of it in September and did it in April is astounding to me. It’s a year-round process now.
I would assume there’s going a little something extra thrown into the mix for the event this year