Let $D=(V,A)$ be a finite simple directed graph. A function$f:Vlongrightarrow {-1,0,1}$ is called a twin minus dominatingfunction (TMDF) if $f(N^-[v])ge 1$ and $f(N^+[v])ge 1$ for eachvertex $vin V$. The twin minus domination number of $D$ is$gamma_{-}^*(D)=min{w(f)mid f mbox{ is a TMDF of } D}$. Inthis paper, we initiate the study of twin minus domination numbersin digraphs and present some lo...

twin reversed arterial perfusion (trap) sequence is a syndrome with poor prognosis, seen only in monochorionic monozygotic twin pregnancies. the incidence is one in 35.000 births and one in 100 monozygotic twin pregnancies. it is characterized with a recipient fetus exhibiting lethal anomalies including acardia and a pump fetus. mortality is usually due to heart failure or premature labor cause...

In order to investigate deformation history preserved in the calcite twins in the hinterland of Zagros, several samples have been collected from calcschists of the Paleozoic Sargaz complex in the Faryab area, SE Iran. These samples are related to F1-recumbent folding and thrust shear zones. The twin width is about 1 and 3.8 µm (thin-twin regime); the twin strain amounts 5 and 10%; twin intensit...

Over the past 25 years the rate of twin and higher - order multifetal birth have increased between 1980 and 2005. The twining rate rose from 18.9 to 32.1 per 1000 live birth. Multifetal gestations are at high risk of fetaland complication such as; growth restricted fetal death, LBW and cerebral palasy. Maternal complication are that also increased such as: preeclampsia, diabetes, maternal death...

this study was designed to investigate the effect of environmental factors on the appearance of polycystic ovaries (pco) during the first two decades of life. ninety-four female-female twins who underwent a transabdominal ultrasound at the royal hospital for women were sent a questionnaire asking about their birth details, feeding history as a baby, childhood illnesses and vaccination as well a...

This paper estimates the health returns to schooling, using a twin design. For this purpose, I use data on monozygotic twins from the Midlife in the United States survey. The results suggest that completing high school improves health, as measured through self-reported health, chronic conditions, and exercise behavior, but that additional schooling does not lead to additional health gains. Cont...

Twins-based estimates of the return to schooling feature prominently in the labor literature. Their validity hinges critically on the assumption that within-pair variation in schooling is explained by factors which are unrelated to wage earning ability. This paper develops a framework for testing this assumption, and …nds, using a unique dataset of monozygotic twins, strong evidence against it....

The main aim of this paper was to resolve the correlation between intelligence test scores and standing height into genetic and environmental components. Data on 1181 identical and 1412 fraternal twin pairs (all males) were retrieved by matching files from the Norwegian Army with twin registries. The data were analyzed by means of a structural equation model comprising latent genetic, shared en...

A retrospective study was carried out on a sample consisting of 89,491 deliveries occurred from 1979 through 1998, in the city of São Paulo, SP, Brazil. These deliveries included 935 twin and 26 triplet births. The mean incidence per 1,000 deliveries was estimated at 10.45 for twins (5.34 for dizygotic and 5.11 for monozygotic twins) and 0.29 for triplets. The average maternal age increased sig...